METHOD IN A WIRELESS CELLULAR TELECOMMUNICATIONS DEVICE, WIRELESS CELLULAR TELECOMMUNICATIONS DEVICE

专利摘要:
cell reselection in a cellular telecommunications network. In accordance with one aspect of the present disclosure, a method may be provided in a wireless cellular telecommunications device camped in a service cell, the device stored in a first parameter obtained from a first cell's system information. the method comprises: measuring an attribute of a signal received from a candidate cell; determining whether the cell is a candidate; determining whether the candidate cell is a closed subscriber group cell; and evaluating the candidate cell for a reselection. if the candidate cell is determined to be a closed subscriber group cell, the evaluation of the candidate cell for a reselection will be based on at least the measured attribute independently of the first stored parameter, said first stored parameter indicating a minimum value for the measured attribute. additionally or alternatively, if the candidate cell has an identifier equivalent to an identifier of the first cell, the candidate cell evaluation for a reselection will be based at least on the measured attribute and the stored parameter, otherwise the cell evaluation candidate for a reselection will be performed without using the stored parameter. a device and a computer readable medium are also provided.
公开号:BR112013013382B1
申请号:R112013013382-1
申请日:2011-11-30
公开日:2022-01-11
发明作者:Raghavendra MAGADI RANGAIAH；David Philip Hole；Johanna Lisa Dwyer
申请人:Blackberry Limited；
IPC主号:

专利说明:

Technical Field
[001] The present disclosure relates to a cellular telecommunications system and, in particular, to a method of cell reselection in a mobile device camped in a cell of the cellular telecommunications system. Background of the Invention
[002] In a typical cellular radio system, a wireless telecommunication device communicates over one or more radio access networks (RAN) with one or more core networks. In a UMTS system, these devices are typically referred to as User Equipment (UE), and, in a GSM system, these devices are typically referred to as mobile stations (MS). The terms can be considered equivalent. In the description here, both terms may be used interchangeably, although it is noted that the term MS will be used predominantly, as the present disclosure primarily refers to a cell reselection from the GSM EDGE radio access network ( GERAN) to a UMTS terrestrial radio access network (UTRAN) or an evolved UMTS terrestrial radio access network (e-UTRAN). It will be clear, however, that the present disclosure is not limited to this type of cell reselection.
[003] The mobile station (MS) comprises various types of equipment, such as mobile phones (also known as cellular or cell phones), laptops with wireless communication capability, tablet computers and personal digital assistants (PDAs) among others. These can be portable, hand-held, pocket-sized or installed in a vehicle, for example, and communicate voice or data signals or both with the radio access network (RAN). Obviously, the MS may not be mobile, but it can be fixed in one location. In this context, the term mobile can simply refer to the device's communication capabilities.
[004] In the following, reference will be made to the global system for mobile communications (GSM), universal mobile telecommunications system (UMTS), long-term evolution (LTE) and standards in particular. However, it should be understood that the present disclosure is not intended to be limited to any particular mobile telecommunications system or standard.
[005] The RAN covers a geographic area divided into a plurality of cell areas. Each cell area is served by at least one base station, which in UMTS may be referred to as a Node B or an enhanced Node B in LTE. Each cell can be identified by a unique identifier, which is broadcast throughout the cell. The base stations communicate at radio frequencies over a radio interface with the UEs, which are camped in the cell (these may be all or some of the UEs which are in range of the base station). Multiple base stations can be connected to a radio network controller (RNC), which controls various base station activities. RNCs are typically connected to a core network. Each cell implements a particular radio access technology (RAT), such as UMTS terrestrial radio access (UTRA) among others. In a GERAN (Global System for Mobile Communications (GSM) / Enhanced Data Rates for GSM Evolution Radio Access Network (EDGE)), the radio access network may include one or more base stations (BTSs) and a or more base station controllers (BSCs), which together implement base station subsystem (BSS) functionality with respect to any particular cell.
[006] A cell selection, sometimes referred to as a cell lookup, for a UE is described in the 3GPP TS 25.304, V8.1.0 specification, “User Equipment (UE) procedures in idle mode and procedures for cell re-selection in connected mode”, which is incorporated herein by reference and referred to herein as the 25.304 specification. Section 5.2.3 and, in particular, section 5.2.3.1.1 of the 25.304 specification describes the cell selection process. One of the considerations in the cell selection process is whether a cell is “suitable”. Criteria for suitability include criteria related to signal strength and/or signal quality (with reference to the signal transmitted by the candidate cell base station as received by the UE). Some of the criteria that are used in the suitability assessment are based on parameters which must be decoded by the device, after tuning with the frequency of the candidate cell.
[007] When inactive, an MS will evaluate the properties of detected telecommunications cells, other than the cell it is currently connected to or camped in (often known as a service cell), in order to identify whether detected or candidate cells would be better suited for connection, rather than the service cell. The MS process that autonomously changes the serving cell while in idle mode is known as cell reselection (although a reselection may not be restricted to idle mode or a purely autonomous cell change or both). The process by which an MS first camps in a cell following a power activation or loss of radio coverage is known as cell selection. Criteria for cell reselection can include such things as received signal strength and signal quality. The parameters associated with these criteria can be broadcast or transmitted in another way in the service cell. One of the requirements for cell reselection (and selection) may be that the candidate cell is suitable. Criteria for suitability may include criteria related to signal strength and/or signal quality (with reference to the signal transmitted by the candidate cell base station as received by the MS). Some of the criteria that are used in the suitability assessment are based on parameters which must be decoded by the MS, after tuning into the candidate cell frequency. Decoding parameters from the candidate cell may require significant battery power for the MS. Regular evaluation based on decoding suitability parameters in this way is particularly undesirable on mobile devices where battery life is limited.
[008] The existing solution to this problem is to store and reuse the most recently decoded suitability criteria parameters. This solution is highlighted in the 3GPP TS 45.008 specification V9.4.0, which is incorporated herein by reference and referred to herein as the '45.008 specification'. Section 6.6.5, section 6.6.6 and section 6.6.7 of specification 45.008 describe the cell reselection processes, entitled “Algorithm for cell re-selection from GSM to UTRAN”, “Algorithm for inter-RAT cell re -selection based on priority information”, and “Cell selection and re-selection to CSG cells and hybrid cells”, respectively. The algorithm defined in Section 6.6.5 can be described as the 'scoring algorithm' and the algorithm defined in Section 6.6.6 can be described as the 'priority-based algorithm'. These terms may be used throughout the description here.
[009] According to the existing solution, when evaluating the suitability of a candidate cell, the suitability parameters of a cell from which the suitability parameters were most recently decoded can be used. This solution, while it may reduce battery usage or the MS's long-term power requirements, has inherent limitations. Specifically, for example, it is easy for an MS to discount candidate cell suitability and thus not reselect the cell when it should. This could be because the parameters used to assess its suitability are incorrect, for example, because the suitability parameters of the candidate cell are not the same as those being applied. Alternatively, an MS may incorrectly consider a cell to be a valid cell for reselection and proceed to wastefully tune the candidate cell frequency and decode parameters from that cell. This can be a problem in particular if a wide range of threshold parameters is applicable to cells that MS could potentially reselect. When one of these threshold parameters is stored, it can be used to incorrectly evaluate another cell in the network for which a different value is applicable.
[0010] In an example scenario, an operator may want devices in an idle mode to camp in cells of one frequency and devices in connected mode, i.e. with active data in progress or voice calls, to operate in cells of a different frequency. The operator may try to achieve this by discouraging an idle reselection for a particular frequency by suitability criteria, i.e. suitability criteria are set so that an MS is very unlikely to meet those criteria. In this scenario, the MS can assess these cells for suitability using a considerable amount of power in the process, based on criteria that are easier to meet. Additionally, if the MS is stored at these incorrect parameters for reuse in assessing suitability for other cells, the MS may not camp in a cell where it should.
[0011] It would be desirable for a candidate cell meeting the reselection criteria to not fail in the suitability aspect of the reselection tests. The present exposition addresses the problem of how to efficiently and effectively evaluate a reselection against reselection. The present disclosure minimizes the need to tune to the frequency of a candidate cell and decode suitability parameters from candidate cells, while avoiding the risk of incorrectly discounting a candidate cell. Brief Description of Drawings
[0012] The examples of the present exhibition will now be described in detail, with reference to the associated drawings, in which:
[0013] Figure 1A is a diagram showing an overview of a network and a UE device;
[0014] Figure 1B shows a schematic system suitable for implementing a first embodiment of the present invention;
[0015] Figure 2 shows a flowchart of a known scoring algorithm for cell reselection;
[0016] Figure 3 shows a flowchart of a known method of storing suitability parameters when performing a cell reselection;
[0017] Figure 4 shows a flowchart illustrating an example of the present exposition, in which the stored suitability parameters are applied on a per-frequency basis;
[0018] Figure 5 shows an information flow view illustrating an example of the present disclosure in which stored suitability parameters are applied on a per-frequency basis;
[0019] Figure 6 shows a flowchart illustrating an example of the present exhibit in which stored suitability parameters are applied on a per-cell basis;
[0020] Figure 7 shows a flowchart illustrating an example of the present disclosure with respect to closed subscriber group (CSG) cells;
[0021] Figure 8 shows a flowchart illustrating an example of the present exposition in relation to the storage of suitability criteria;
[0022] Figure 9 shows a flowchart illustrating an example of the present exposition with respect to a priority-based reselection;
[0023] Figure 10 shows a process illustrating an example of the present disclosure in which stored suitability parameters are applied on a per-frequency basis;
[0024] Figure 11 shows a process illustrating an example of the present disclosure in which stored suitability parameters are applied on a per cell basis;
[0025] Figure 12 shows a process illustrating an example of the present disclosure with respect to closed subscriber group (CSG) cells;
[0026] Figure 13 shows a process illustrating an example of the present disclosure with respect to closed subscriber group (CSG) cells;
[0027] Figure 14 shows a process illustrating an example of the present disclosure with respect to closed subscriber group (CSG) cells;
[0028] Figure 15 shows a process illustrating an example of the present exposition with respect to a priority-based reselection; and
[0029] Figure 16 shows a flowchart illustrating an example of the present exposure in which certain radio-related assessments are not performed.
[0030] The same reference numbers used in different figures denote similar elements.
[0031] Detailed Description
[0032] The modalities set out in this application generally refer to a method of cell reselection in an electronic device. Embodiments can efficiently evaluate a candidate cell when performing a reselection, without having to tune to the frequency of a candidate cell and decode suitability parameters from that cell each time the evaluation is performed.
[0033] In accordance with an aspect of the present invention, there is provided a method in a wireless cellular telecommunications device camped in a service cell, the device storing a parameter obtained from a first cell, the method comprising:
[0034] measuring an attribute of a signal received from a candidate cell; and
[0035] the evaluation of the candidate cell for reselection;
[0036] wherein, if a carrier frequency of the candidate cell matches a carrier frequency of the first cell, the candidate cell's assessment for reselection will be based at least on the measured attribute and the stored parameter; otherwise,
[0037] the candidate cell evaluation for reselection will be performed without using the stored parameter.
[0038] In accordance with an aspect of the present disclosure, a method may be provided in a wireless cellular telecommunications device camped in a service cell, the device storing a parameter obtained from a first cell, the method comprising:
[0039] measuring an attribute of a signal received from a candidate cell; and
[0040] the evaluation of the candidate cell for reselection;
[0041] wherein, if a carrier frequency of the candidate cell matches a carrier frequency of the first cell, the candidate cell's assessment for reselection will be based on at least the measured attribute and the stored parameter; otherwise,
[0042] the candidate cell evaluation for reselection will be performed without using the stored parameter.
[0043] In accordance with an aspect of the present disclosure, a method may be provided in a wireless cellular telecommunications device camped in a service cell, the device storing a parameter obtained from a first cell, the method comprising:
[0044] measuring an attribute of a signal received from a candidate cell; and
[0045] evaluating the candidate cell for reselection according to a scoring algorithm;
[0046] wherein, if a carrier frequency of the candidate cell matches a carrier frequency of the first cell, the candidate cell's assessment for reselection will be based at least on the measured attribute and the stored parameter; otherwise,
[0047] the candidate cell evaluation for reselection will be performed without using the stored parameter. The candidate cell may be a UTRAN cell.
[0048] In certain embodiments, the method may further comprise performing reselection from the serving cell to the candidate cell, based on the evaluation.
[0049] Additionally, if the frequency of the candidate cell matches the frequency of the first cell, the evaluation may also include determining whether the candidate cell meets reselection requirements, where if the measured attribute fails to exceed the parameter stored by a first predetermined amount, the evaluation will include determining that the candidate cell does not meet reselection requirements. The first preset amount can be +10 dB.
[0050] Further, if the carrier frequency of the candidate cell does not match the carrier frequency of the first cell, the candidate cell's evaluation for reselection may include: determining whether the measured attribute exceeds a predetermined default value; and, if the measured attribute fails to exceed the predetermined default value, determining that the candidate cell does not meet reselection requirements.
[0051] Additionally, the first cell may be different from the serving cell, the device having been previously camped in the first cell. Alternatively, the first cell and candidate cell may be of the same wireless radio access technology.
[0052] In certain embodiments, evaluation of the candidate cell may include: acquiring a system information of the candidate cell, the system information including a parameter; determining whether the measured attribute exceeds the candidate cell parameter by a second predetermined amount; and, if the measured attribute exceeds the candidate cell parameter by the second predetermined amount, performing the reselection for the candidate cell. The second predetermined amount can be 0 dB.
[0053] Also, the stored parameter may include a minimum required reception level. The measured attribute may be a received signal code power (RSCP). Additionally, the service cell can be a GERAN cell.
[0054] In certain embodiments, the method may further comprise: acquiring a parameter from a second cell; and, if the carrier frequency of the second cell does not match the carrier frequency of the first cell, storing said second cell parameter; otherwise, if the carrier frequency of the second cell matches the carrier frequency of the first cell, replacing the stored parameter with the second cell parameter, so that when evaluating the candidate cell for reselection, if the carrier frequency of the cell candidate match with the carrier frequency of the second cell, the candidate cell's assessment for reselection is based at least on the measured attribute and the stored second cell parameter. If the candidate cell has an identifier equivalent to an identifier of the first cell, the candidate cell's assessment for reselection may be based at least on the measured attribute and the stored parameter; otherwise, the candidate cell evaluation for reselection can be performed without using the stored parameter. The identifier can be a primary scrambling code.
[0055] Additionally, the method may further comprise: determining whether a candidate cell is a closed subscriber group cell; and, if the candidate cell and the first cell are closed subscriber group cells, the candidate cell's evaluation for reselection will be based on at least the measured attribute and the stored parameter; otherwise, the candidate cell evaluation for reselection will be performed without using the stored parameter.
[0056] Service and candidate cells can be from the same wireless radio network. Alternatively, the service and candidate cells may be from different wireless radio networks.
[0057] In accordance with one aspect of the present disclosure, there may be provided a wireless cellular telecommunications device adapted for: camping in a service cell; storing a parameter obtained from a first cell; measuring an attribute of a signal received from a candidate UTRAN cell; and evaluating the candidate cell for reselection, wherein, if a carrier frequency of the candidate cell matches a carrier frequency of the first cell, the evaluation of the candidate cell for reselection will be based on at least the measured attribute and the stored parameter; otherwise, the candidate cell evaluation for reselection will be performed without using the stored parameter.
[0058] In accordance with one aspect of the present disclosure, there may be provided a wireless cellular telecommunications device adapted for: camping in a service cell; storing a parameter obtained from a first cell; measuring an attribute of a signal received from a candidate cell; and evaluating the candidate cell for reselection according to a scoring algorithm, wherein, if a carrier frequency of the candidate cell matches a carrier frequency of the first cell, the candidate cell's evaluation for reselection will be based on at least the attribute measured and stored parameter; otherwise, the candidate cell evaluation for reselection will be performed without using the stored parameter.
[0059] In accordance with one aspect of the present disclosure, a computer readable storage medium may be provided which has stored therein instructions which may be executed by a device for: camping in a service cell; storing a parameter obtained from a first cell; measuring an attribute of a signal received from a candidate UTRAN cell; and evaluating the candidate cell for reselection, wherein, if a carrier frequency of the candidate cell matches a carrier frequency of the first cell, the evaluation of the candidate cell for reselection will be based on at least the measured attribute and the stored parameter; otherwise, the candidate cell evaluation for reselection will be performed without using the stored parameter.
[0060] In accordance with one aspect of the present disclosure, a computer readable storage medium may be provided which has stored therein instructions which may be executed by a device for: camping in a service cell; storing a parameter obtained from a first cell; measuring an attribute of a signal received from a candidate cell; and evaluating the candidate cell for reselection according to a scoring algorithm, wherein, if a carrier frequency of the candidate cell matches a carrier frequency of the first cell, the candidate cell's evaluation for reselection will be based on at least the attribute measured and stored parameter; otherwise, the candidate cell evaluation for reselection will be performed without using the stored parameter.
[0061] In accordance with an aspect of the present disclosure, a method may be provided in a wireless cellular telecommunications device camped in a service cell, the device storing a parameter obtained from a first cell, the method comprising:
[0062] measuring an attribute of a signal received from a candidate cell; and
[0063] the evaluation of the candidate cell for reselection,
[0064] if the candidate cell has an identifier equivalent to an identifier of the first cell, the candidate cell evaluation for reselection will be based at least on the measured attribute and the stored parameter; otherwise,
[0065] the candidate cell evaluation for reselection will be performed without using the stored parameter.
[0066] In certain embodiments, if the candidate cell has an identifier equivalent to the identifier of the first cell, the evaluation may include determining whether the candidate cell meets reselection requirements, where if the measured attribute fails to exceed the stored parameter by a first predetermined amount, the evaluation will include determining that the candidate cell does not meet the reselection requirements. The first predetermined amount can be 0 dB. Alternatively, the first preset amount can be +10 dB.
[0067] In accordance with one aspect of the present disclosure, a method may be provided in a wireless cellular telecommunications device camped in a service cell, the device storing a first parameter obtained from a system information of a first cell , the method comprising:
[0068] measuring an attribute of a signal received from a candidate cell;
[0069] determine whether the candidate cell is a closed subscriber group cell; and
[0070] the evaluation of the candidate cell for reselection,
[0071] wherein, if the candidate cell is determined to be a closed subscriber group cell, the candidate cell's evaluation for reselection will be based on at least the measured attribute, regardless of the first stored parameter, said first stored parameter indicating a minimum value for the measured attribute.
[0072] In certain embodiments, the device has a second stored parameter obtained from a closed subscriber group cell, and in which the first cell is not a closed subscriber group cell, wherein, if the candidate cell is determined to be a closed subscriber group cell, the candidate cell's evaluation for reselection will be based on at least the measured attribute and the second stored parameter.
[0073] Additionally, if the assessment is based on at least the measured attribute and the second stored parameter, the assessment may include determining whether the cell meets the reselection requirements, where if the measured attribute fails to exceed the second parameter stored for a first predetermined amount, there will be a determination that the candidate cell does not meet reselection requirements. The first predetermined amount can be 0 dB. Alternatively, the first preset amount can be +10 dB.
[0074] Further, if the candidate cell has an identifier equivalent to an identifier of the second cell and the candidate cell is determined to be a closed subscriber group cell, the candidate cell's assessment for reselection may be based at least on the second parameter stored; otherwise, the candidate cell evaluation for reselection will be performed without using the second stored parameter.
[0075] Distributor can be a locally unique identifier. The identifier can be a physical layer identifier. The identifier can be a primary scrambling code.
[0076] In certain embodiments, if the candidate cell has a carrier frequency matching a carrier frequency of the second cell and the candidate cell has a primary scrambling code matching the primary scrambling code of the second cell and the candidate cell is determined to be being a closed subscriber group cell, the evaluation of the candidate cell for reselection will be based on at least the measured attribute and the second stored parameter; otherwise, the candidate cell evaluation for reselection will be performed without using the second stored parameter.
[0077] Additionally, if the evaluation is performed without the use of the parameter, the evaluation of the candidate cell may include: determining if the measured attribute exceeds a predetermined default value; and, if the measured attribute fails to exceed the predetermined default value, determining that the candidate cell does not meet reselection requirements.
[0078] The candidate cell can be a UTRAN cell. The candidate cell may be an E-UTRAN cell. The first cell identifier can also be a physical layer cell identifier. The service cell can be a GERAN cell.
[0079] In certain embodiments, the method may further comprise performing reselection from the serving cell to the candidate cell based on the evaluation. Evaluating the candidate cell may also include: acquiring a candidate cell system information, the system information including a parameter; determining whether the measured attribute exceeds the candidate cell parameter; determining whether the measured attribute exceeds the candidate cell parameter by a second predetermined amount; and, if the measured attribute exceeds the candidate cell parameter by the second predetermined amount, performing the reselection for the candidate cell. The second predetermined amount can be 0 dB.
[0080] Also, the stored parameter may include a minimum reception level required. The measured attribute may be a received signal code power (RSCP).
[0081] Also, the service and candidate cells can be from the same wireless radio network. Alternatively, the service and candidate cells may be from different wireless radio networks.
[0082] In accordance with one aspect of the present disclosure, a wireless cellular telecommunications device adapted for: camping in a service cell; storing a parameter obtained from a first cell; measuring an attribute of a signal received from a candidate cell; and evaluating the candidate cell for reselection, wherein, if a carrier frequency of the candidate cell matches a carrier frequency of the first cell, the evaluation of the candidate cell for reselection will be based on at least the measured attribute and the stored parameter; otherwise, the candidate cell evaluation for reselection will be performed without using the stored parameter.
[0083] In accordance with one aspect of the present disclosure, there may be provided a wireless cellular telecommunications device adapted for: camping in a service cell; storing a parameter obtained from a first cell system information; measuring an attribute of a signal received from a candidate cell; determining whether the candidate cell is a closed subscriber group cell; and evaluating the candidate cell for reselection, wherein, if the candidate cell is determined to be a closed subscriber group cell, the candidate cell evaluating for reselection will be based on at least the measured attribute, regardless of the first parameter stored , the parameter indicating a minimum value for the measured attribute.
[0084] In accordance with one aspect of the present disclosure, a computer readable storage medium may be provided which has stored therein instructions which may be executed by a device for: camping in a service cell; storing a parameter obtained from a first cell; measuring an attribute of a signal received from a candidate cell; and evaluating the candidate cell for reselection, wherein, if the candidate cell has an identifier equivalent to an identifier of the first cell, the evaluation of the candidate cell for reselection will be based on at least the measured attribute and the stored parameter; otherwise, the candidate cell evaluation for reselection will be performed without using the stored parameter.
[0085] In accordance with one aspect of the present disclosure, a computer readable storage medium may be provided which has stored therein instructions which may be executed by a device for: camping in a service cell; storing a parameter obtained from a first cell system information; measuring an attribute of a signal received from a candidate cell; determining whether the candidate cell is a closed subscriber group cell; and evaluating the candidate cell for reselection, wherein, if the candidate cell is determined to be a closed subscriber group cell, the candidate cell evaluating for reselection will be based on at least the measured attribute, regardless of the first parameter stored , the parameter indicating a minimum value for the measured attribute.
[0086] According to one aspect of the present disclosure, a method can be provided in a wireless cellular telecommunications device camped in a service cell, the device storing a parameter obtained by decoding the detailed information and system of a first cell, the method comprising:
[0087] measuring an attribute of a signal received from a candidate cell; and
[0088] the evaluation of the candidate cell for reselection based on the measured attribute in accordance with a priority-based reselection algorithm regardless of the stored parameter, where the parameter indicates a required minimum received signal code power.
[0089] In certain embodiments, the method may further comprise performing a reselection from the serving cell to the candidate cell based on the evaluation. Evaluating the candidate cell may also include acquiring a candidate cell system information, the system information including a parameter, determining whether the measured attribute exceeds the candidate cell parameter by a predetermined amount; and, if the measured attribute exceeds the candidate cell parameter by a predetermined amount, performing the reselection for the candidate cell. The predetermined amount can be 0 dB.
[0090] Additionally, the evaluation of the candidate cell for reselection may include: determining whether the measured attribute exceeds a predetermined default value; and, if the measured attribute fails to exceed the predetermined default value, determining that the candidate cell does not meet reselection requirements.
[0091] In certain embodiments, the measured attribute may be a received signal code power (RSCP). The candidate cell may be a UTRAN cell. The service cell can be a GERAN cell.
[0092] Further, the method may also comprise: measuring an attribute of a signal received from a second cell; and evaluating the second cell for reselection based on the measured attribute and stored parameter according to a scoring algorithm.
[0093] Additionally, the service and candidate cells can be from the same wireless radio network. Alternatively, the service and candidate cells may be from different wireless radio networks.
[0094] In accordance with one aspect of the present disclosure, a wireless cellular telecommunications device adapted for: camping in a service cell; storing a parameter obtained by decoding the system information of a first cell; measuring an attribute of a signal received from a candidate cell; and evaluating the candidate cell for reselection based on the measured attribute in accordance with a priority-based reselection algorithm, wherein the parameter indicates a minimum required signal code power.
[0095] In accordance with one aspect of the present disclosure, a computer-readable storage medium may be provided which has stored therein instructions which may be executed by a device to: camp in a service cell; storing a parameter obtained by decoding the system information of a first cell; measuring an attribute of a signal received from a candidate cell; and evaluating the candidate cell for reselection based on the measured attribute in accordance with a priority-based reselection algorithm, wherein the parameter indicates a minimum required signal code power.
[0096] Other aspects and features of the present teaching will become apparent to those skilled in the art upon a review of the following description of specific embodiments of a method and apparatus for cell reselection in a telecommunication system and the associated claims. . Any method exposed here can be implemented in a mobile station device of a wireless communications network.
[0097] Radio access networks of type GSM / EDGE (GSM / EDGE radio access network, GERAN), UMTS (UMTS terrestrial radio access network, UTRAN) or LTE (radio access network UMTS terrestrial, e-UTRAN) typically include multiple cells covering a geographic area, each of which may implement a different radio access technology (RAT). 2G may refer to GSM and 3G may refer to UMTS, and the terms may be used interchangeably. As described above, a mobile station (MS), once connected to a cell, known as the serving cell, can evaluate other detected cells, known as candidate cells, to determine if they would be more suitable for connection than the serving cell. service. When operating in a cell, the MS is referred to as being camped in the cell. In the description here, the MS may be referred to as being "in a cell", "camped in a cell", or using a "service cell". These terms may be used interchangeably and define that the MS is capable of being radioed for downlink data by that cell. The description here may refer to 2G and 3G.
[0098] By the terms 'scoring algorithm' and 'priority-based reselection algorithm', which are used throughout the description here, we mean the following:
[0099] In a scoring algorithm, cell radio measurements (possibly modified by offsets and/or scaling factors, and possibly subject to minimum thresholds) are compared and a reselection is usually done on the thus highest scoring cell . In a scoring algorithm, cells on different frequencies, or using different radio access technologies, can be compared directly and thus scored against each other. Radio measurements (or values derived, for example, based on a received cell signal quality or strength) are the key basis for comparing candidate cells. An example of a scoring algorithm is shown in Figure 2.
[00100] In a priority-based reselection algorithm, cells (typically grouped according to their operating frequency and/or radio access technology) are assigned priorities. These priorities are the primary means by which cells are considered (radio measurements of neighboring cells being a secondary consideration) when determining which cell, if any, the device should reselect. (Note that other considerations may be made, such as based on measurements of the serving cell, in addition to the priority level.) Under current 3GPP priority-based reselection, priorities are assigned on a per-frequency basis (ie. is such that all cells operating using the same radio access technology and the same carrier frequency are assigned the same priority), or (in the case of GSM cells) in a radio access technology (cells operating in accordance with with GSM-based technologies operating on different carrier frequencies may be assigned the same priority). In particular, radio measurements from cells of different priorities do not need to be compared with each other (although radio measurements can be used for any cell, regardless of its respective priority, to check if it meets minimum camp/service criteria or to evaluate it with respect to a measurement limit). For example, a cell of a priority can be determined with service offering meeting all applicable re-selection criteria, without regard to any radio measurements of a cell of a lower priority.
[00101] With reference to the drawings, Figure 1A is a schematic diagram showing an overview of a UMTS network and user equipment device. Clearly, in practice, there may be many user equipment devices operating with the network, but for the sake of simplicity, Figure 1A only shows a single user equipment device 100.
[00102] For purposes of illustration, Figure 1A also shows a radio access network 119 (UTRAN) used in a UMTS system having few components. It will be clear to a person skilled in the art that, in practice, a network will include far more components than those shown.
[00103] Network 119, as shown in Figure 1A, comprises three radio network subsystems (RNS) 102. Each RNS has a radio network controller (RNC) 104. Each RNS 102 has one or more B-Nodes 102, which are similar in function to a base station transmitting a GSM radio access network. User equipment UE 100 may be mobile in the radio access network. Radio connections (indicated by straight dotted lines in Figure 1A) are established between the UE and one or more Nodes B in the UTRAN.
[00104] Figure 1B shows an additional schematic of a network system. Typically, each radio access network (RAN) includes radio access devices 156 for providing the radio link between the wireless communications device, the MS 160, and the remainder of the radio access network. These radio access devices 156 are known as base stations in GSM and Node B in UMTS. The RAN in e-UTRAN comprises only eNodes B. In GSM and UMTS, the RAN also comprises a radio network controller (RNC) or a base station controller (BSC), 152, 154, and base stations; RNCs and BSCs are connected to one or more core networks (typically at least one for packet switched services and one for circuit switched services). RNCs connect to 3G base stations (B Nodes) and BSCs connect to 2G base stations (in which case the BSC and base station combined perform the functionality of a base station subsystem (BSS)), although they may be physically colocated or even be on the same unit. The core network (not shown) is associated with a public land mobile network (PLMN) 150; it is possible for a single RAN to connect to the core networks of multiple PLMNs (not shown).
[00105] Each 3G cell can be uniquely identified (in the local area) by a frequency and a primary scrambling code. Generally, a cell refers to a radio network object that can be uniquely identified by an MS 160 from a cell identifier that is broadcast over geographic areas by a base station, a Node B and a Node B or a similar entity. A single physical Node B can generate more than one cell, as it can operate on multiple frequencies, or with multiple scrambling codes, or both. A candidate cell can finally be connected to the same PLMN as the serving cell.
[00106] Figure 2 shows a flowchart illustrating known processes performed by an MS during a known cell reselection procedure, according to a scoring algorithm. Referring to Figure 2, the process begins at step 201. At step 202, cell measurements, for example intrafrequency, interfrequency and inter-RAT cell measurements are generated or received by the MS. In step 203, score values are calculated for each frequency. In one example, these cells are the service cell and neighboring cells. An example of the calculation usable for calculating a score value in the form of a cell scoring criterion R is defined in section 5.2.6.1.4 of 3GPP TS 25.304, V8.1.0, “User Equipment (UE) procedures in idle mode and procedures for cell re-selection in connected mode”, which is incorporated here by reference and referred to here as specification 25.304 (see calculations for R for serving cells and R for neighboring cells in that section). In that example, score values are calculated for cells if they satisfy the conditions set out in section 5.2.6.1.4 of the 25.304 specification.
[00107] In step 204, cells are sorted on score values. In one example, only cells with score values better than those of the service cell are considered, and these are compiled into a list. In step 205, the resulting cell score list is created. At step 206, if the MS finds that the serving cell is better (i.e., has a higher score value), then the MS will remain camped in the serving cell and the process will revert to step 202.
[00108] If, in step 206, the MS finds that the serving cell is not the best (i.e., does not have the highest score value), then, in step 207, the MS will attempt to reselect to a neighboring cell with the highest score value. For this purpose, at 208 a channel (in an example a physical primary common control channel (PCCPCH)) is established, at 209 a system information (in an example in the form of master information blocks (MIBs) and (SIBs)) is read from the neighboring cell and, at 210, a check is made that the cell is a suitable cell. A suitable cell is a cell in which an MS can camp; examples include a cell which has an acceptable signal strength and/or is not a location prohibited area and/or is not barred and/or for an automatic search, belongs to the public land mobile network (PLMN). If the cell is suitable, the MS will camp in the neighboring cell at 211. If the cell is not a suitable cell, the process will revert to approximately 202. The process ends at 212.
[00109] As noted above, the process shown in Figure 2 requires that a communications channel be established with the candidate cell in order to determine the system information from the cell and hence the suitability of the cell for selection. Generally, the described process of establishing a channel with the candidate cell is simply to allow the decoding of a system information, which is broadcast. In the context of the present exposition, the establishment of a communications channel does not necessarily imply any particular behavior by the network, i.e., the network does not positively 'establish' the channel, as it can continuously broadcast system information.
[00110] This decoding is particularly power intensive and time consuming for the MS. If the service cell is a GERAN cell, then this is likely to be often below a neighboring cell in the score list as a result of the score calculation. Consequently, the MS may be repeatedly checking neighboring cells for suitability and therefore establishing communication channels in those cells for decoding system information.
[00111] It may be the case that the system information received from neighboring cells contains a suitability parameter, so that the MS is unlikely to even determine that the cell is suitable. The parameter may have been regulated by the network operator, so that the MS can vary, rarely, if ever, the encampment in that cell. In this scenario, the MS will repeatedly establish a communication channel in the cell using a large and unnecessary amount of power in the process.
[00112] In an example scenario, the operator may want devices in idle mode to camp in cells of one frequency, and devices in connected mode, i.e. with active data in progress or voice calls, to operate in cells of one frequency different. The operator may try to achieve this by discouraging an idle reselection for a particular frequency by means of the suitability criteria, that is, the suitability criteria are set so that an MS is very unlikely to meet those criteria. In the above scenario, MS will consistently rate a cell like this for suitability using a considerable amount of power in the process, although the cell may never be suitable.
[00113] It was previously proposed that, in order to reduce the power requirements of the MS, it can store previously decoded suitability parameters. The reason for requiring storage of suitability criteria is to allow the MS to evaluate a candidate cell, using these criteria, without first having to read the candidate cell's SIBs (which would otherwise have to be read in order to determine the candidate cell's SIBs). suitability criteria applicable to that cell). In many cases, the cell will not meet the suitability criteria (based on stored parameters), and no further evaluation of this cell is necessary; thus, storing criteria from a previous attempt can significantly reduce battery consumption, as SIBs do not need to be read from cells which do not meet these criteria.
[00114] However, such storage can cause problems if networks are configured as described above, particularly if stored parameters are associated with (i.e. decoded from) a cell where a mode reselection is intended. inactive is restricted, that is, those with unobtainable (or rarely obtainable) parameters. Since the stored suitability criteria are unlikely to be met, the MS will not attempt a reselection (noting that the MS may abandon a reselection at this stage, without reading the target cell's system information and therefore without being able to determine that, in a real fact, the suitability criteria would be met for this cell). Under certain circumstances, the MS could remain camped in a GSM cell longer than intended in cases where a UMTS cell would be more appropriate.
[00115] Suitability parameters or threshold criteria may indicate a minimum required reception level. The signal quality, signal strength or cell signal strength may need to exceed this by a predetermined amount, for example 0 dB or +10 dB. The suitability parameters or threshold criteria in practice can be the Qrxlevmin value or the Pcompensation value or both. Other suitability parameters or threshold criteria are obviously considered.
[00116] The stored Qrxlevmin value can have a range of -115 to -24 dBm, and there is no default value (a value to be used if a value is not explicitly flagged), as its inclusion in the system information of 3G cell is mandatory. Qrxlevmin can be a suitability parameter for that cell.
[00117] Pcompensation is another suitability parameter derived (at least partially) from one or more cell broadcast parameters also currently referred to in Section 6.6.5 of the 45.008 specification. Its value is most likely 0 dB.
[00118] Figure 3 illustrates the known process of cell reselection using stored parameters. The applicable algorithm is highlighted in specification 45.008. Specifically, in section 6.6.5 entitled “Algorithm for cell re-selection from GSM to UTRAN”.
[00119] The illustrated process starts at step 302 with the MS camped in the service cell. Depending on the configuration and algorithm used, the neighbor cell is received from the serving cell (step 304), and the reselection parameters are decoded from that list (step 306). The MS then identifies a candidate cell and performs measurements (step 308). These can include signal strength and signal quality, among others. Then, in step 310, the MS determines whether the candidate cell meets the reselection criteria. This test can be limited to those criteria which can be derived from the parameters received in the service cell. In some cases, depending on the parameters broadcast in the serving cell and whether it has suitability parameters stored or not, the MS may omit evaluation of the candidate cell based on the suitability parameters stored. If the candidate cell does not meet the reselection criteria, the process will start over as the cell is not acceptable (step 312).
[00120] Between steps 312 and 314 (not shown), if the service cell transmits received signal code power (RSCP) parameters to be used in place of the 'suitability test' in the reselection algorithm, then the candidate cell will be evaluated with respect to these, regardless of whether it has suitability parameters stored or not. If the test passes and she passes (not shown), the process moves to step 318.
[00121] If the candidate cell is acceptable, the MS will check if it has suitability parameters stored from a previous attempt (step 314). If it does, the candidate cell will be evaluated to determine if it meets the suitability criteria based on these stored parameters (step 316). If the candidate cell does not meet the suitability criteria, the cell will be deemed unacceptable and the process will be restarted (step 312). If the cell actually meets the suitability criteria based on the stored parameters, then the MS will establish a communication channel with the cell and acquire system information from the candidate cell (step 318). Similarly, if the MS has no suitability parameters stored from a previous attempt, the MS will establish a communication channel with the cell and acquire system information from the candidate cell (step 318).
[00122] The suitability of the cell is then evaluated using parameters in the system information (step 320). If the candidate cell meets the suitability criteria, the MS camps in the cell (step 324). If the candidate cell does not meet the suitability requirements, the cell will be judged not acceptable (step 312), and the MS will remain camped in the serving cell.
[00123] Section 6.6.5, “Algorithm for cell re-selection from GSM to UTRAN”, outlines the algorithm for determining reselection suitability described above and based on a scoring algorithm. The scoring algorithm is used where a priority-based reselection is not, for example, due to a network configuration or device capability. Section 6.6.6., entitled “Algorithm for inter-RAT cell re-selection based on priority information”, highlights a priority-based re-selection. Typically, a priority-based reselection is preferred. For example, a device which is LTE capable must support priority-based reselection. In the scoring algorithm, criteria for reselection from GERAN to UTRAN may be referred to as criteria based on RSCP of CPICH. CPICH stands for Common Pilot Channel and RSCP stands for Received Signal Code Power. For reference, an excerpt of the algorithm defined in section 6.6.5 of the 45.008 specification is as follows, where FDD stands for frequency division duplexing and MS mobile station:
[00124] “If the 3G cell reselection list includes UTRAN frequencies, the MS shall update, at least every 5 s, the RLA_C value for the serving cell and each of at least non-service GSM cells .
[00125] The MS must then reselect a suitable UTRAN cell (see TS 25.304) if:
[00126] for a TDD cell the measured RSCP value exceeds the RLA_C value,
[00127] for the serving cell and all suitable non-serving GSM cells (see 3GPP TS 03.22) by the value XXX_Qoffset for a period of 5 s, and
[00128] for an FDD cell, the following criteria are all met for a period of 5 s:
[00129] Your measured RSCP value exceeds the RLA_C value for the serving cell and all suitable non-serving GSM cells (see 3GPP TS 03.22) by the XXX_Qoffset value,
[00130] your measured Ec/No value is equal to or greater than the FDD_Qmin value, and
[00131] Your measured RSCP value is equal to or greater than FDD_RSCP_threshold, if supported by MS.
[00132] In the case of a cell reselection occurring within the previous 15 seconds, XXX_Qoffset is increased by 5 dB, where:
[00133] FDD_RSCP_threshold equals Qrxlevmin + Pcompensation + 10 dB if these parameters are available, otherwise -<x (criterion not effective),
[00134] Qrxlevmin is the minimum RX level required in the UTRAN FDD cell (dBm), see 3GPP TS 25.304,
[00135] Pcompensation is max(UE_TXPWR_MAX_RACH - P_MAX, 0) (dB), see 3GPP TS 25.304,
[00136] UE_TXPWR_MAX_RACH is the maximum TX power level that an MS can use when accessing the UTRAN FDD cell in RACH (dBm), see 3GPP TS 25.304,
[00137] P_MAX is the maximum RF output power of the MS (dBm) in UTRAN FDD mode, see 3GPP TS 25.304,
[00138] FDD_Qmin and XXX_Qoffset are broadcast in BCCH of the serving cell. XXX indicates another radio access technology/mode.
[00139] Note: The parameters required to determine if a UTRAN cell is suitable are broadcast in BCCH of the UTRAN cell. An MS may start a reselection towards the UTRAN cell prior to decoding the BCCH of the UTRAN cell, leading to a short interruption of service if the UTRAN cell is unsuitable.
[00140] The MS can store the above UTRAN cell RSCP suitability criteria parameters, always decoded from a UTRAN FDD cell of an equivalent PLMN. The most recently decoded parameters are valid reselection criteria towards all UTRAN FDD cells. This parameter list must be cleared after a PLMN selection (see 3GPP TS 23.122).”
[00141] It should be noted that the definition of suitable in the above algorithm requires that the cell selection criteria be met. These criteria for UMTS cells are defined in the 3GPP TS specification 25.304 subitem 5.2.3.1.2. The suitability parameters referred to in the 45.008 specification, when defining a reselection, are Qrxlevmin and Pcompensation (which depends on UE_TXPWR_MAX_RACH). The 25.304 specification defines other parameters affecting suitability that are not used in the reselection tests defined in the 45.008 specification.
[00142] For later versions of the specification, the phrase “if supported by MS” in item 3 above has been removed, making this consideration mandatory for mobile stations complying with later versions of the specification.
[00143] The definition of FDD_RSCP_threshold has also been previously modified, to read as follows:
[00144] “FDD_RSCP_threshold is equivalent to FDD_RSCPmin-min((P_MAX-21 dBm), 3 dB) if FDD_RSCPmin is broadcast in the service cell; otherwise, Qrxlevmin + Pcompensation + 10 dB, if these parameters are available; otherwise the default value of FDD_RSCPmin.”
[00145] Additionally, the paragraph starting with “MS can store” of the algorithm has been updated to read as follows:
[00146] “The MS shall store the UTRAN cell RSCP suitability criteria parameters, whenever decoded from a UTRAN FDD cell of an equivalent PLMN, while attempting to camp in the UTRAN FDD cell. The parameters most recently decoded from a UTRAN FDD cell of an equivalent PLMN are valid suitability criteria towards all UTRAN FDD cells. This parameter list must be cleared after a PLMN selection (see 3GPP TS 23.122).”
[00147] This change was made for the following reasons:
[00148] “If the FDD_RSCPmin parameters are not provided in the broadcast of the GSM service cell, the FDD_RSCP_threshold will be derived from the broadcast information of the UTRAN cells. These parameters could be different for each UTRAN cell.
[00149] It is not clear from which UTRAN cell and when the MS should read these parameters and when they should be re-read. Furthermore, it is unclear whether a regulated parameter of a UTRAN cell is valid for reselection towards all cells or only towards the UTRAN cell from which the parameters were read.”
[00150] When this specification change was made, a summary was given as follows:
[00151] “It is clarified that the MS must renew the parameter setting when it tries to camp in a UTRAN FDD cell of an equivalent PLMN and thus it is not required to read this parameter from neighboring UTRAN cells while camping in a GSM cell.
[00152] It is further clarified that parameters received from a UTRAN cell are valid suitability criteria towards all UTRAN FDD cells.”
[00153] As previously mentioned, the reason for requiring the storage of suitability criteria is to allow the MS to evaluate a candidate cell, using these criteria, without having to primarily read the system information blocks (SIBs) of the candidate cell (the that would otherwise have to be read in order to determine suitability criteria applicable to that cell). In many cases, the cell will not meet the criteria and no further evaluation of this cell will be necessary; thus, storing criteria from a previous attempt can significantly reduce battery consumption, as SIBs do not need to be read from cells that do not meet these criteria.
[00154] It was mentioned above that Section 6.6.5 only applies when a priority-based reselection does not. Specifically, Section 6.6.5 says that: “The algorithm in this subitem shall be used for reselection from GSM to UTRAN, if the conditions for using the cell reselection algorithm based on priority information (see subitem 6.6 .6) are not satisfied”. Section 6.6.6, “Algorithm for inter-RAT cell re-selection based on priority information”, defines that priority-based re-selection criteria allow an operator to configure a set of cells (on the same frequency and using the same RAT) as having a particular priority; different priorities can be assigned to different RATs or frequencies or both. Multiple frequencies of the same RAT can share a priority level. Two frequencies cannot share a priority level if they are used for different RATs. As with the algorithm defined in section 6.6.5 and discussed above, there is a requirement that the target cell or candidate cell be suitable as defined in specification 25.304 and described above. For reference, an excerpt of the algorithm defined in section 6.6.6 of the 45.008 specification is as follows:
[00155] “The MS must then reselect a suitable cell (see 3GPP TS 25.304 for UTRAN and 3GPP TS 36.304 for E-UTRAN) from another radio access technology, if the criteria below are met. S_non_serving_XXX is the metering quantity of a non-serving inter-RAT cell and XXX indicates the other radio access technology/mode and is defined as follows:
[00156] for a UTRAN cell, is the measured RSCP value for the cell minus UTRAN_Qrxlevmin for the cell frequency;
[00157] for an E-UTRAN cell, is the measured RSRP value for the cell minus E-UTRAN_Qrxlevmin for the cell frequency, if THRESH_E-UTRAN_high_Q is not provided; otherwise, if THRESH_E-UTRAN_high_Q is provided, it will be the measured RSRQ value for the cell minus E-UTRAN_QQUALQMIN for the cell frequency.
[00158] (...)
[00159] A cell reselection for a cell of another inter-RAT frequency must be performed if any of the conditions below (to be evaluated in the order shown) is satisfied:
[00160] the S_non-serving_XXXX of one or more cells of a higher priority inter-RAT frequency is greater than THRESH_XXX_high (or, in the case of an E-UTRAN target, THRESH_E-UTRAN_high_Q, if provided) during a time interval T_re-selection; in this case, the mobile station shall consider the cells for reselection in descending order of priority and, for cells of the same interRAT frequency or of equal priority inter-RAT frequencies, in descending order of S_non-serving_XXX, and reselect the first cell that satisfies the above conditions;
[00161] S_GSM value is less than THRESH_GSM_low for serving cell and all GSM cells measured during a time interval T_re-selection; in this case, the mobile station must consider a reselect of the interRAT cells in the following order, and reselect the first one that satisfies the following criteria:
[00162] cells of a lower priority inter-RAT frequency whose S_non-serving_XXX is greater than THRESH_XXX_low (or, in the case of an E-UTRAN target, THRESH_E-UTRAN_low_Q, if provided) during a time interval T_re - selection; these cells must be considered in descending order of priority and, for cells of the same RAT, in descending order of S_non-serving_XXX;
[00163] if no cell meets the above criterion, inter-RAT cells for which, during a time interval T_re-selection, S_non-serving_XXX is higher than S_GSM for the serving cell by at least one specific hysteresis H_PRIO; these cells must be considered in descending order from _non-serving_XXX.
[00164] A UTRAN FDD cell should only be reselected if, in addition to the above criteria, its measured Ec/No value is equal to or greater than FDD_Qmin - FDD_Qmin_Offset.
[00165] If THRESH_E-UTRAN_high_Q is provided for an E-UTRAN frequency, and if E-UTRAN_RSRPmin is provided, an E-UTRAN cell at that frequency shall only be reselected if, in addition to the above criteria, its measured RSRP value is equal to or greater than E-UTRAN_RSRPmin. If E-UTRAN_RSRPmin is not provided, the default value must be used.
[00166] E-UTRAN cells which are included in the disallowed cell list should not be considered as candidates for cell reselection. If the strongest cells on an E-UTRAN frequency are included in the disallowed cell list, the mobile station can reselect the strongest valid cell (see subitem 8.4.7) on that frequency.
[00167] A cell re-selection to a cell of another radio access technology (e.g. a UTRAN or E-UTRAN) must not occur within 5 seconds after the MS has re-selected a GSM cell to an interRAT cell, if a suitable GSM cell can be found.
[00168] If the mobile station applies common priorities or individual priorities received via dedicated signaling and priorities are only available for some inter-RAT frequencies, cells belonging to frequencies for which no priority is available or no threshold is provided by the cell of service shall not be considered for measurement and cell reselection.
[00169] If a mobile station in a 'normally camped' state (see 3GPP TS 43.022) applies individual priorities received via dedicated signaling and no priority is available for the serving cell, the mobile station shall consider any GSM cell ( including the service cell) to have a lower priority (that is, lower than the eight configured network values).
[00170] A mobile station in a 'camped in any cell' state (see 3GPP TS 43.022) shall ignore individual priorities received through dedicated signaling and shall apply priorities received from the serving cell's system information, while trying to find a suitable cell. If the mobile station supports CS voice services, the MS should avoid reselecting acceptable (but not suitable) E-UTRA cells, regardless of the priorities provided in the system information.
[00171] NOTE 4: If the MS is camping in an acceptable cell, the individual priorities will not be discarded, until an event leading to their detection occurs”.
[00172] If a cell supports priority-based reselection in accordance with section 6.6.6 of the 45.008 specification, it will transmit to an MS camped in the cell a list of its neighboring cells - the 'neighbor cell list' (this may identify individual cells, or frequencies at which neighboring cells operate, or both). Along with the list, a system information type 2quater (SI2quater) message may indicate a parameter applicable to one or more cells in the list, referred to as UTRAN_Qrxlevmin in the above excerpt. This candidate cell parameter, which is broadcast in the serving cell, i.e. the UTRAN_Qrxlevmin, is expected in normal operation to be closely related to the corresponding RSCP threshold sent by the respective cell(s), as used in the suitability check. As such, this parameter allows the MS to identify whether the cell meets an RSCP-based criterion, without power intensive decoding and evaluation of the system information broadcast by the candidate cell, unless this criterion is met.
[00173] However, support for priority-based reselection remains optional for non-LTE capable devices. For LTE capable devices, a priority-based reselection must be used. Furthermore, a priority-based reselection is not supported on any pre-version 7 devices. Also, there is a possibility that a priority-based reselection is not applicable in the service cell, for example, if AC e is a GERAN cell. . It is quite possible that operators will not upgrade GERAN networks to support priority-based reselection, even when LTE is employed, especially near the edges of LTE coverage. Therefore, while LTE cells or UTRAN cells are more likely to support priority-based reselection, overlapping or close GSM cells cannot. A device supporting a priority based reselection is required to use the old rules of 6.6.5, ie a reselection according to the scoring algorithm in this case. In this scenario, the problems described above are applicable, in that an MS may remain camped in a GSM cell for longer than is appropriate when a UMTS or LTE capable cell is available, but the MS does not consider it to be adequate, or intense power system information reception and decoding are required.
[00174] The Priority Based Reselection (PBR) RSCP threshold parameter broadcast in the service cell is optional and is regulated in the network configuration. The parameter is likely to be (or to correlate with) the minimum required measured RSCP level. Additionally, the PBR parameter can be broadcast as a specific value and associated with one or more explicitly flagged frequencies, or it can be broadcast as a 'default' value to be used with cells of frequencies not explicitly flagged in conjunction with the parameter value. . The parameter is only applicable to cells which operate at the same frequency associated with the parameter. The default value only applies to frequencies in the neighbor cell list. An example of a widespread default parameter is the DEFAULT_UTRAN_QRXLEVMIN parameter encoded in the 3G Priority Parameter Description Structure; an example of a parameter associated with explicitly signaled frequencies is the parameter UTRAN_QRXLEVMIN encoded in the UTRAN Repeated Priority Parameters structure (see 3GPP TS 44.018 v.10.3.0). If no parameters are broadcast in the cell, the algorithm will specify a value to use, ie the UTRAN_Qrxlevmin. The PBR parameter may not have been broadcast in the cell, due to the network configuration, or it may not have been fully received by the MS.
[00175] For the purposes of this discussion, a network comprising three cells may be considered, although it is understood that this is only an example and more cells implementing a variety of radio access technologies (RATs) may also be used with the present exposition. . In the described examples, unless otherwise indicated, a first candidate cell, cell A, is a UTRAN cell. Another cell, cell B, is the cell currently serving the MS and is a GERAN cell. Another cell, cell C, is a second candidate cell and is also a UTRAN cell. Although GERAN and UTRAN cells are used in this description, it should be understood that any RAT can be implemented by each cell, although for the purposes of the exposition, cells A and C must be implementing the same RAT.
[00176] As described with reference to the above nomenclature, when an MS is connected to, or, as is known, is camped in cell B (the service cell), the MS may assess cells A and C to determine their suitability for reselection.
[00177] During a cell reselection from GSM to UMTS or LTE, the existing 3GPP TS 45.008 section 6.6.5 described above, i.e. a reselection according to a scoring algorithm, requires storage and, in some cases, the use of previously received suitability requirements for UTRAN FDD cells.
[00178] Specification 45.008 refers to “equivalent PLMNs”, which may include a registered PLMN (generally, these procedures are agnostic as to which PLMN is being considered, as long as it is on the list of equivalent PLMNs - PLMNs on this list are “considered as equivalent to each other for PLMN selection, cell selection/reselection and point-to-point transfer”; TS 23.122 sub-item 4.4.3). The text follows to indicate that these values are cleared on PLMN selection; however, a reselection between different equivalent PLMNs is not considered a PLMN selection.
[00179] This can lead to a scenario where, for example, in national roaming scenarios, where the PLMNs of two operators are regulated equivalent to each other, the suitability criteria of a roaming partner are applied to a cell of a second roaming partner (or domestic or service PLMN). The use of equivalent PLMNs is for the operator(s) to determine, and the scope of these issues is not limited to how or why equivalent PLMNs are used, or if they are used at all.
[00180] More importantly and more generally, there is a potential that if threshold criteria for a cell or a category of cells (such as those operating at a particular frequency) are different from those for another cell or a category of cells (such as those operating on a different frequency, on the same PLMN or on a different equivalent PLMN), then the behavior of the mobile station will vary considerably depending on stored requirements, which may in turn depend on the cell of most recent UTRAN from which it received (and stored) the requirements.
[00181] More specifically, one could consider an example scenario, where an operator wants devices in idle mode to camp in cells of a frequency, and devices in connected mode (i.e. with data in progress active / voice calls) operate on cells of a different frequency. The operator may try to achieve this by discouraging (to the point of making it practically impossible) an idle re-selection to a particular frequency through suitability criteria, i.e. suitability criteria are set so that it is very unlikely if suit these criteria.
[00182] According to existing rules, the UE can store and apply these same criteria (which are decoded as part of an attempt - most likely unsuccessful - to reselect a cell on the first frequency), when evaluating a UTRAN cell on any frequency, including cells on the second frequency where an idle-mode reselection is not intended to be restricted.
[00183] Since the stored criteria are unlikely to be met, the MS will not attempt a reselection (noting that the MS may abandon a reselection at this stage, without reading the target cell's system information and therefore without being able to to determine that, in an actual event, the suitability criteria would be met for this e).
[00184] This issue could restrict a cell reselection from 2G to 3G potentially causing the device to essentially get stuck on 2G (or at least stay on longer than intended). In some cases, the device may move to 3G only if the power is turned off or a PLMN reselection occurs (see 3GPP TS 23.122).
[00185] In the case of a priority-based reselection, considering the example case where a mobile has stored restricted criteria from one cell, this may improperly abandon an evaluation of a second cell as part of the priority-based reselection , although all the (correct) criteria to allow a reselection evaluation were available in the service cell.
[00186] In addition to the above scenarios, other issues are created by the use of closed subscriber group (CSG) cells. A home Node B (HNB), home eNB (HeNB) or femtocell are concepts introduced for UMTS and LTE (E-UTRAN) to improve indoor and microcell coverage as well as to leverage wired line backhaul for 'House'. Note that “femtocell” is widely used outside of 3GPP to mean any cell with very small coverage, and typically installed in a private facility (private or corporate). The terms HeNB/HNB are used in 3GPP with specific meanings, namely that the cell is a closed subscriber group (CSG) cell or a hybrid cell.
[00187] An important aspect of HeNB/HNB functionality is the ability to restrict access to particular users. For example, to company employees on whose site the H(e)NB is used, to consumers of a particular coffee shop chain or (in the case of H(e)NBs employed in private households) to individuals.
[00188] To achieve this functionality, 3GPP has defined the concept of a closed subscriber group. A CSG cell is one which indicates that it is a CSG cell (by means of 1 bit broadcast in the system information) and broadcasts a CSG ID (also in a system information). A cell can only indicate one (or no) CSG ID, although multiple cells can share a CSG ID. A device (UE or MS) may have signed multiple CSGs. These subscriptions can be temporary in nature (eg, a coffee shop allows a consumer 1 hour of access to their CSG).
[00189] CSG cells are a specific category of cells, which can be used as “femtocells” or for the provision of uncoordinated coverage (i.e. not subject to normal radio planning as is used for “macrocells”). ") or both. They can be limited to users with specific subscriptions (eg associated with an employer, school, university, cafeteria, etc.).
[00190] The term "macrocell", while not having significance in the 3GPP specification, is widely used to mean a cell other than a CSG cell and is used accordingly in this description.
[00191] A CSG cell may operate using UTRAN and E-UTRAN protocols and radio specifications, and may operate on the same or a different frequency than non-CSG cells.
[00192] UMTS CSG cells will not be listed in cell neighbor lists of non-CSG cells; therefore legacy UMTS devices (ie Version 7 or earlier) will not look for these cells. If such a device attempts to access a CSG cell, its registration attempt will be rejected.
[00193] E-UTRAN is first specified in Version 8 and therefore all E-UTRAN capable devices will necessarily be “CSG aware” devices even if they do not have a CSG signature.
[00194] The reselection criteria for these cells are different. It is simply required that the cell be suitable, the strongest in frequency, and accessible to the device (ie, have a signature on the cell).
[00195] Generally, network operators are prone to devices which have a subscription to a CSG cell to camp in that cell in preference to a non-CSG cell. However, the device's determination to fetch CSG cells is implementation-specific, and can be triggered manually. Devices are expected to store some information (such as GPS coordinates, a list of macrocells, which are detected) corresponding to the location of cells, which they are able to access and use this to speed up subsequent accesses - this is referred to as 'fingerprint'.
[00196] The decision as to which target cell to camp on is also dependent on the cell selection and reselection rule defined for UTRAN and E-UTRAN. Currently, in Version 8, it is specified that a UE can reselect a cell only if it is the best cell (that is, the cell with the strongest signal strength) of any cells using its particular carrier frequency. It is also specified that even though the UE is camped in a suitable CSG cell, the UE should always consider the current frequency to be the highest priority frequency.
[00197] An idle-mode reselection away from CSG cells towards a non-CSG cell follows a legacy behavior for reselection of these cells. However, no cell reselection parameters for CSG cells are likely to be available in the service cell, and therefore there is no storage compartment partition for the device as to what the criteria would be (as there is in the case of a priority-based reselection, as discussed above). Furthermore, these cells are likely to be configured to provide very limited coverage, meaning that their suitability requirements can be relatively stringent compared to non-CSG cells. Storing suitability requirements from CSG cells and using them in non-CSG cells (or vice versa) can result in very infrequent reselection attempts (because the stored criteria are too high) or a lifetime of drained battery (if cells are incorrectly determined to meet suitability requirements prior to reading candidate cell system information). Even within CSG cells, different cells can have very different requirements.
[00198] CSG cells can be identifiable, such as based on their physical layer identities (frequency, physical layer identity, primary scrambling code, etc.) - because they operate on a dedicated frequency, or because the range of physical layer identities is transmitted on the network.
[00199] Hybrid cells (introduced in Version 9) are yet another category of cells that may have different suitability requirements than non-hybrid cells.
[00200] In E-UTRAN, neighbor cell lists are not explicit, that is, they do not positively identify cells: they simply indicate a frequency and, optionally, a list of “not allowed” (blacklisted) cells that the mobile should not try to access. Devices are expected to detect cells at a frequency by blind search. However, this can lead to a significant problem in the case where many of the cells detected are CSG cells. In order to minimize unnecessary processing of these cells by devices which do not have a CSG signature, the network can optionally indicate the “PCI division” applicable to CSG cells, i.e. the set of physical layer cell identities/identifiers. which are reserved for CSG cells.
[00201] PSC division is the analogous indication for UMTS cells, in the case where an operator does not list the CSG cells in the neighbor cell list.
[00202] There has also been discussion regarding the use of a PCI/PSC split to distinguish between hybrid cells and non-hybrid cells.
[00203] It is worth noting that CSG cells may have significantly different criteria for reselection (compared to other non-CSG cells or possibly even compared to other CSG cells) and that they may be identifiable as being CSG cells without the need for a decoding of broadcast system information (eg based on physical layer parameters: frequency / PSC / PCI , etc.), as described above.
[00204] Currently, there is no solution for solving the problems identified and described above.
[00205] Example of this exhibition
[00206] In accordance with the present exposition, it is proposed that threshold criteria decoded from cells be selectively stored and used, so that the evaluation of candidate cells is efficient and more accurate than the present solutions.
[00207] It is proposed and described by way of example implementation that the storage and use of stored suitability requirements discriminate between cells (or classes of cells) that can be discriminated at the physical layer, for example, where physical layer addresses ( or ranges thereof) and/or operating frequencies are used to distinguish cell categories. In this way, an MS can discriminate stored suitability requirements according to a cell class or an individual cell, without having to establish a communication channel in that cell. In one example, requirements are used according to cell frequency or cell identity. In one example, requirements for CSG cells versus non-CSG cells in an example breakdown (CSG cells are likely to use a dedicated range of physical layer addresses, which could be PCI (E-UTRAN cells) or PSC (UTRAN cells)). Additionally, the use of stored parameters can be restricted to individual CSG cells (ie it can only be used in the evaluation of the same cell as the one from which they were received).
[00208] Additionally, previously stored suitability requirements (which may have been obtained as a result of a priority-based reselection) should not be used when evaluating cells according to priority-based reselection rules. This may be dependent on the corresponding parameters (signal quality / signal strength) being available in the current service cell. The network can be configured not to send these parameters, ie the parameters may not be included in the system information of the current service cell.
[00209] In a first embodiment, the threshold criteria are stored and used according to the applicable cell frequency. For example, threshold parameters are stored on the device and linked to the cell frequency from which they were encoded. These parameters are then only used when evaluating cells of that frequency. In this way, defined network configurations of cells having particular frequencies are prevented from causing an MS to be incorrectly camped in a cell. In an additional example, for priority-based reselection, threshold criteria can be stored and reused on a per-priority-level basis.
[00210] As illustrated in Figure 4, the storage and use of stored suitability requirements can be on a per-frequency basis. In other words, the decoded requirements of a cell on frequency A are only used for the evaluation of other cells on the same frequency.
[00211] The illustrated process starts with the MS being camped in a service cell. In this description, the service cell can be described as the 'B cell'. The serving cell can be from any RAT, but in this example it can be thought of as a GSM cell for convenience. It is irrelevant whether the MS camped in the service cell by using cell reselection or cell selection. Optionally, the MS will acquire the UMTS or LTE neighbor cell list. This can be broadcast in the service cell or can be acquired in another way (step 404). The reselection parameters can be decoded from the neighbor cell list (step 406).
[00212] Once these optional steps have been performed, the MS can then identify a candidate cell. This may or may not be from the neighbor cell list. The MS then acquires measurements from the identified cell to identify characteristics of the cell, such as signal strength, signal quality, or signal strength (step 408). It will be understood that the steps may be performed in any particular order. In a specific example, it can be envisaged that measurements are performed for all cells in the list, before a candidate cell is identified.
[00213] Once a candidate cell has been identified and measurements of that cell have been performed, the MS determines if the cell meets the initial reselection requirements (step 410). This test can be based on the parameters decoded from the serving cell in the neighbor cell list. If the cell is judged not to meet these initial reselection requirements, then the MS will remain camped in the service cell and will not continue the reselection process.
[00214] If the MS determines that the cell meets the initial reselection criteria, then the MS will check if it has any stored suitability-related criteria previously decoded from another cell (step 412). The parameters may have been decoded from a cell's system information when assessing cell suitability. If the MS has criteria stored, the MS will then determine if the criteria are from a cell having the same frequency as the candidate cell (step 414). The criteria must have been decoded from the system information of a cell operating on the same frequency as the candidate cell. To enable this, the MS may be required to keep an indication of the frequency of the cell from which the criterion was determined, in association with the criteria in the data store. In this description, the candidate cell may be referred to as the 'C cell' for convenience.
[00215] If the parameters are determined to be from a cell having the same frequency as the candidate cell, the candidate cell will be checked for its reselection property (step 416). Criteria stored from a previous suitability check are used to determine if the cell meets these requirements. In one example, measurements performed by the MS are used to determine if the cell meets a particular threshold. If the candidate cell does not meet or exceed the requirements based on the stored parameter, for example, the characteristics of a signal received by the MS from a cell do not exceed the limit indicated by the parameter, the process will stop and the MS will remain camped in the cell. service cell. It should be noted that the signal attribute(s) may have to exceed the threshold by a predetermined amount, which may be, for example, 0 dB or +10 dB. The parameter can be the minimum reception level, the value QRXLEVMIN.
[00216] Conventionally, the stored Qrxlevmin value can have a range of -115 to -24 dBm, and there is no default value as its inclusion in the 3G cell system information is mandatory. Qrxlevmin can be a suitability parameter for that cell.
[00217] Pcompensation is another suitability parameter derived (at least partially) from one or more cell broadcast parameters also currently referred to in Section 6.6.5 of the 45.008 specification. Its value is most likely 0 dB.
[00218] Based on the parameter, if it is determined that the candidate cell meets or exceeds the requirement, then the MS can go ahead to evaluate the cell in the known manner, for example, by tuning to the cell frequency and evaluating it using the decoded data. If the MS has no stored criteria available (step 412), or if the MS has no stored criteria obtained from a cell having the same frequency as the candidate cell (step 414), then this decoding will be performed.
[00219] Optionally, prior to acquiring the candidate cell system information for decoding suitability parameters in step 418, not shown is that the MS can evaluate the candidate cell using the default parameters which are not explicitly flagged. In one example, the default parameter is a predetermined amount and is specified in the reselection specification. If the candidate cell does not meet the requirements based on this standardized parameter, the MS will not proceed with the reselection, and the MS will remain camped in the service cell. If the MS really meets these requirements based on the standardized parameter, the MS will continue with the reselection process.
[00220] In the illustrated example, at step 418, the MS may acquire the candidate cell's system information. To do this, the MS can establish a communication channel and tune into its frequency. The system information may be in the form of a system information block (SIB) and may be obtained by tuning to the cell frequency and establishing a communication channel therein. System information is generic and can be derived from blocks other than the SIB referred to throughout this exposition. The MS will then decode the system information to acquire suitability parameters and evaluate the cell based on these parameters (step 420). If it is determined that the MS meets these requirements (step 422), for example, based on measurements previously taken in addition to the decoded parameters, the MS may camp at the candidate cell and perform a reselection for it (step 424). If the MS is judged to be unsuitable, the MS will remain camped out in the service cell.
[00221] Additionally and optionally, a record update can be performed when the MS has camped in the new cell (not shown). This registry update can explicitly notify the network that MS has reselected a new cell or a new registry area. Additionally and optionally, data can be transmitted and received to and from the network in the new cell (not shown). The record update step (not shown) may include, for example, a routing area update, a location update, a combined routing area update, or the like. For additional information regarding registry updates, please see the 3GPP TS 24.008 specification, “Mobile radio interface Layer 3 specification; Core network protocols; Stage 3”, which is incorporated here as cooling.
[00222] Figure 5 provides a high-level view of the information flow. When an MS is camped in a 3G 504 cell, RSCP suitability criteria parameters are stored according to the cell frequency. This storage 506 may contain multiple parameters and frequencies. As shown, when performing a cell reselection from 2G to 3G, that is, from cell 502 to cell 504, the stored information is used on a per-frequency basis.
[00223] In order to carry out the above example, it may be advantageous for an MS to maintain a list of frequencies and threshold parameters. For example, for every cell having a new found frequency, threshold parameters for that frequency are stored. Additionally, each time new threshold parameters are decoded from a cell having a particular frequency, the stored criteria may be overwritten. This can occur once the MS has decoded the system information of a cell (step 420), if the cell previously met the criteria (step 616).
[00224] In another embodiment, instead of being stored and used on a frequency basis, each threshold parameter can only be used on a per-cell basis. Figure 6 illustrates this example. In step 602, the MS is camped in the serving cell. The MS may first receive a neighbor cell list from the serving cell (step 604). The MS can then decode certain reselection parameters from the neighbor cell list broadcast by the serving cell (step 606). The MS then identifies a candidate cell and performs measurements on it, such as signal strength, quality, or power (step 608). If the cell does not meet the reselection requirements, the MS will remain camped out in the service cell. If the candidate cell actually meets the reselection requirements (step 610), the MS will go ahead to check if it has any stored criteria available (step 612). If no stored criteria are available at all, the MS will continue with the reselection process and tune to the cell frequency for decoding the system information.
[00225] The MS then checks if there are any stored criteria available, which were obtained from a cell having the same cell_ID as the candidate cell (step 614). If there are no applicable stored criteria, i.e. none were obtained from a cell having the same cell_ID as the candidate cell, the MS will continue with the reselection process and tune to the cell frequency for decoding the system information.
[00226] The cell_ID can be the cell scrambling code or it can be another cell identifier. cell_ID does not have to be globally unique, but can be locally unique. The identifier used to differentiate between cells in this particular example is an identifier that can be derived from the physical layer, i.e., a physical layer identifier, so that the candidate cell can be identified without having to decode information from cell system. Examples of such locally unique identifiers (which may be derived from the physical layer) include the 'physical layer cell identifier' of an E-UTRAN cell and the 'primary scrambling code' of an UTRAN cell.
[00227] In this way, the criteria can only be applied to the cell from which they were obtained. This eliminates the limitations of conventional reselection, where an MS can be 'stuck' unnecessarily. Battery life is still minimized, when compared to known storage methods, and where no parameters are stored, since an MS will not be tuned to the frequency of a cell multiple times to decode the parameters; once it is sufficient for them to be stored and reused (eg they can be reused if measurements change).
[00228] If the MS has stored criteria taken from a cell having the same cell_ID as the candidate cell, the candidate cell will be checked against these criteria (step 616), for example, using measurements taken in step 608. If the test is successful, MS will proceed with the reselection process. If not, the MS will remain camped in the service cell.
[00229] Optionally, prior to acquiring the candidate cell system information for decoding suitability parameters in step 618, not shown is that the MS can evaluate the candidate cell using default parameters, which are not explicitly flagged. In one example, the default parameter is a predetermined quantity and is specified in the reselection specification. If the candidate cell does not meet the requirements based on this standardized parameter, the MS will proceed with the reselection process. If not, the MS will remain camped in the service cell.
[00230] Optionally, prior to acquiring the candidate cell system information for decoding suitability parameters, in step 618, not shown is that the MS can evaluate the candidate cell using default parameters, which are not explicitly flagged. In one example, the default parameter is a predetermined quantity and is specified in the reselection specification. If the candidate cell does not meet the requirements based on this standardized parameter, the MS will not proceed with the reselection process and the MS will remain camped out in the service cell. If the MS really meets these requirements based on the standardized parameter, the MS will continue with the reselection process.
[00231] The MS will then, if the conditions described above are met or not as the case may be, will tune into the candidate cell frequency and acquire the system information (step 618). The suitability of the cell for reselection is then evaluated, based on parameters decoded from the system information (step 620). If the cell meets the suitability requirements (step 622), the MS can camp in the cell (step 624). If not, the MS may remain camped in the service cell (step 602). The MS can maintain a cell parameter list so that for each cell_ID the last decoded parameters are stored and replaced. In this way, each time the stored criteria are used, they are more likely to be as accurate as possible for that cell.
[00232] In another example, closed subscriber group (CSG) cells may be treated differently from non-CSG cells. In the known algorithms, there is no discrimination as to which parameters can be applied to and retrieved from these cells. In one embodiment, in a manner similar to that described above, a parameter may be stored separately if it has already been decoded from a CSG cell. This parameter can then only be applied to cells which are also CSG cells. In an additional example, stored CSG criteria can be applied only to CSG candidate cells operating at the same frequency as the cell from which the criteria were obtained. Also, stored CSG criteria can be applied only to CSG candidate cells having the same ID as the cell from which the criteria were obtained. Thus, the fact that a CSG cell may have significantly different re-selection criteria does not affect the re-selection of a non-CSG cell; since CSG parameters are not stored and used with respect to non-CSG cells and CSG parameters are only applied with respect to CSG cells.
[00233] Figure 7 illustrates this example, where parameters are only applied to CSG cells if they are derived from a CSG cell. In step 702, the MS is camped in the serving cell. The MS may first receive a neighbor cell list from the serving cell (step 704). The MS can then decode certain reselection parameters from the neighbor cell list broadcast by the serving cell (step 706). The MS then identifies a candidate cell and takes measurements of it, such as signal strength, quality, or power (step 708). The candidate cell is a CSG cell. If the cell does not meet the reselection requirements, the MS will remain camped out in the service cell. If the candidate cell actually meets the reselection requirements (step 710), the MS will proceed to check if it has any stored criteria available (step 712). If there is none, the MS will continue with the reselection process and will tune to the cell frequency for decoding the system information.
[00234] The MS then checks if the stored criteria are available, which were obtained from a CSG cell (step 714). If not, the MS continues with the reselection process and tunes to the cell frequency for decoding the system information.
[00235] If the MS has stored criteria obtained from a CSG cell, the candidate CSG cell will be checked against these criteria (step 716), for example using measurements taken in step 708. If the test is successful, MS will proceed with the re-selection process. If not, the MS will remain camped in the service cell.
[00236] The MS will then, if the conditions described above are met, will not, as the case may be, tune to the frequency of the candidate cell and acquire the system information (step 718). The suitability of the cell for reselection is then evaluated, based on the parameters decoded from the system information (step 720). If the cell meets the suitability requirements (step 722), the MS can camp in the cell (step 724). If not, the MS can remain camped in the service cell (step 702).
[00237] Optionally, prior to acquiring the candidate cell system information for decoding the suitability parameters in step 718, not shown is that the MS can evaluate the candidate cell using default parameters which are not explicitly flagged. In one example, the default parameter is a predetermined quantity and is specified in the reselection specification. If the candidate cell does not meet the requirements based on this standardized parameter, the MS will not proceed with the reselection and the MS will remain camped in the serving cell. If MS does not meet these requirements based on the standardized parameter, MS will continue with the reselection process.
[00238] Figure 8 illustrates a storage process in accordance with the present disclosure. In figure 8, the process stop step if the cell is a CSG cell is only applied, where the parameters from the CSG cells are not stored or reused. Additionally, the step of erasing previously stored parameters is optional. While this illustrates storing CSG criteria, the illustration is also applicable to non-CSG cells storing frequency or identity specific parameters, whereby the criteria for storing the parameters are changed as required.
[00239] With the MS camped in a service cell (step 802), the MS can decode a cell's system information (step 804). The cell, referred to herein as the 'cell A' may be a candidate cell that the MS has previously evaluated, or it may be any other cell. In a known manner, the MS can assess whether the cell from which the parameters are decoded, cell A, is the same as or an equivalent PLMN as the serving cell (step 806). If not, the parameters cannot be stored and the process may stop (step 806). If so, the process can continue. This ensures that unnecessary parameters are not stored and the network can be able to control the configuration of stored parameters. Then, according to the present example, the MS will check whether the parameters are derived from a CSG cell (step 810). If they are, then the process will stop and the parameters will not be stored (step 812). This is merely an example of the present exposition. Other examples are described here, where the parameter is stored independently of the non-CSG parameters and the CSG parameters are only used for evaluating the CSG cells.
[00240] According to an example described above, the MS can then identify the cell frequency from which the parameters were derived (step 814). The suitability criteria decoded from the system information are then stored by the MS and associated with the cell frequency for subsequent use (step 816). Any previous parameters associated with the frequency of this cell, ie F_A, can then be optionally deleted (step 818). The process can then be finished (step 820). The above storage process is equally applicable to the storage parameters process in association with a unique cell identifier or any combination of the described suitability of criteria.
[00241] In an additional example, it is contemplated that cells can broadcast a “do not store” flag type indicator to indicate that the MS should not store parameters for that cell. This can be useful, for example, for test cells, which may have very particular or unique settings. Alternatively, there may be some implicit indication or definition of cells for which parameters should not be stored at all; for example, one or more of the CSG cells, as illustrated in Figure 8, barred cells, or cells in which a particular cause of rejection was received.
[00242] Stored values are also subject to a timer expiration to ensure that stored parameters (in particular very restrictive parameters) expire and do not permanently restrict a reselection.
[00243] Replacement of most recently stored values can also be constrained based on:
[00244] in the absolute value of the decoded values
[00245] in the value relative to a previously stored value (higher / lower / greater than some difference).
[00246] This can be useful to avoid storing obviously very restrictive parameters or unusual parameters, or to generally ensure that the most optimistic values are stored to avoid incorrectly abandoning a reselection evaluation based on stored parameters .
[00247] The parameters stored by the MS may have been obtained through an idle mode reselection or may have been alternatively obtained in connected mode or through some other method. It is described that the parameters are obtained by decoding system information. This need not always be the case, for example parameters can be passed separately from system information. Other methods of obtaining and storing parameters for those described above are envisaged.
[00248] Figures 10 to 14 illustrate certain examples of the present exhibition. Of course, it is envisioned that any of these described examples can be combined. Figure 10 illustrates an MS which first reads the system information block (SIB) of a first cell of UTRAN 1. The parameter Qrxlevmin is stored in the MS and associated with the frequency, FREQ1, of cell of UTRAN 1, from which the parameters come. The MS remains in the GSM serving cell, perhaps because Cell 1 is not suitable for reselection; however, the reason is irrelevant. The MS then evaluates the UTRAN Cell 2 for a reselection. If the frequency of Cell 2, FREQ2, is equal to FREQ1, then the MS will use the stored Qrxlevmin value to evaluate Cell 2. It is not shown that if the evaluation succeeds, the MS will reselect Cell 2 or, alternatively, the MS will continue or complete the reselection process towards Cell 2, because it cannot be conclusive after this test that a reselection will be successful. Also, it is not shown that if the frequencies are not equal, the evaluation will be performed without the stored parameter.
[00249] Figure 11 illustrates an MS, which first reads the SIB of a first Cell of UTRAN 1. The parameter Qrxlevmin is stored in the MS and associated with the identity, ID1, of Cell of UTRAN 1, from which the parameters come. The ID1 identity can be, for example, the scrambling code. The MS remains in the GSM service cell. The MS then evaluates the UTRAN Cell 2 for a reselection. If the cell_ID of Cell 2, ID2, is equal to ID1, then the MS will use the stored Qrxlevmin value for evaluation of Cell 2. It is not shown that if the evaluation is successful, the MS will reselect Cell 2. Also it is not shown that if the cell_IDs are not equal, the evaluation will be performed without the stored parameter.
[00250] Figure 12 illustrates an example of the present exposure with respect to CSG cells. The MS first decodes the system information block (SIB) of a first UTRAN cell. The MS stores the Qrxlevmin as the cell is a UTRAN cell, not a CSG cell. The MS then decodes the SIB of a CSG cell (which can also be a UTRAN cell). In this example, the Qrxlevmin is not stored as the cell is a CSG cell. The MS then evaluates the UTRAN cell for a reselection. The MS uses the stored Qrxlevmin value obtained from the first UTRAN cell in the evaluation, since it was stored and the Qrxlevmin from the CSG cell was not.
[00251] Figure 13 illustrates another example of the present disclosure with respect to CSG cells. The MS reads the Drill Drill Instrument SIB from a First Cell of CSG 1 and decodes the SIB. The MS then stores the Qrxlevmin and associates it in its datastore with an indication that the parameter was taken from a CSG cell. The MS remains camped in the service cell, in this case a GSM cell. The MS then evaluates a second Cell of CSG 2 for a reselection using the stored Qrxlevmin value, since Cell 2 is a cell of CSG.
[00252] Figure 14 illustrates another example of the present exposition. The MS is camped in a GSM cell. The MS reads and decodes the SIB from a First cell of CSG 1. The MS then stores the Qrxlevmin and associates it in its data store with an indication that the cell is a cell of CSG and the cell's cell_ID, ID1, from from which Qrxlevmin is derived. The MS remains camped in the GSM Cell. The MS then evaluates a second cell of CSG 2 for a reselection using the stored Qrxlevmin only if the cell is a cell of CSG and the cell_ID of the second cell, ID2, equals ID1. Preferably, the cell frequency and cell_ID can be considered together as described above, for example the CSG cell can be evaluated using the stored parameters only if the frequency and cell_ID of the cell from which the parameters were obtained are the same as those for the candidate cell.
[00253] A specific example implementation of an example from the present exhibit will now be described. In a multi-RAT system, whenever the UE attempts to camp in a UTRAN FDD cell (and/or is camped in the cell, and/or has any other reason to read the SIB of a UTRAN FDD cell), it decodes RSCP policy parameters from SIBs and stores it for future use. The UE can store the cell frequency in addition to other parameters. When a UE moves to 2G, the UE can start applying the stored suitability criteria parameters for cell reselections from 2G to 3G towards all UTRAN FDD cells configured on the frequency for which the last information was stored. .
[00254] Currently, only the RSCP policy is stored and used in the system, but with this change, the UE needs to store the frequency associated with the RSCP policy. The UE may have to maintain a list of frequency and associated RSCP criteria parameters. If the UE subsequently reads the SIB from another UTRAN FDD cell operating at a frequency for which it has stored suitability parameters, then it may replace the stored values with those from the SIBs it has just read. The list will be cleared after a PLMN selection (see 3GPP TS 23.122).
[00255] The present disclosure reduces the chances of a device being stuck on 2G in certain configurations, provides improved flexibility for operators in setting suitability criteria (since these will only be used for other cells of the same frequency), and allows a cell reselection from 2G to 3G to PLMN non-“restricted” frequencies, in the event that certain frequencies are “restricted” by means of high suitability limits.
[00256] Considering the scenario of cells A, B and C described above, where cell B is the service cell, cell A is a cell from which parameters were previously decoded and cell C is the current candidate cell, the parameters associated with Cell A can be:
[00257] PLMN ID (referred to as PLMN_A),
[00258] Frequency, [F_A],
[00259] Physical Layer Address (PCI/PSC) [P_A], or
[00260] Whether it is a CSG cell [isCSG_A].
[00261] These parameters can all be determined by decoding the system information (SIB) of cell A. The system information is generic, and can be derived from blocks other than the SIB referred to throughout this disclosure. The PLMN rules in these examples are examples only and are not necessary for the present exposition. They are an additional independent constraint.
[00262] The parameters associated with Cell B, which is the service cell in this example scenario, can be:
[00263] PLMN ID [PLMN_B], or
[00264] [Frequency, Physical Layer Address (PCI/PSC), which is only relevant if Cell B is from the same RAT as Cells A, C].
[00265] The parameters associated with Cell C can be:
[00266] Frequency, [F_C];
[00267] Physical Layer Address (PCI/PSC) [P_C];
[00268] Whether it is a CSG cell [isCSG_C] - this can be determinable based on F_C alone, or, based on P_C and knowledge of the physical layer address range reserved for CSG cells; or
[00269] [PLMN_C, which may not be known at the time when the initial radio signal quality/strength assessment is performed].
[00270] Typically, conventional specifications specify that parameters from Cell A can be used for the evaluation of Cell C, if PLMN_A = PMLN_B or PLMN_A and PMLN_B are equivalent.
[00271] One of the exposition examples is to modify this rule to be the one that parameters from Cell A can be used for the evaluation of Cell C, if: i) PLMN_A = PMLN_B or PLMN_A and PMLN_B are equivalent, and ii) F_A = F_C.
[00272] Considering another example, illustrated in figure 8, taking into account CSG cells, this can be expressed as: parameters from Cell A can be used for the evaluation of Cell C, if i) PLMN_A = PMLN_B or PLMN_A and PMLN_B are equivalent, and ii) F_A = F_C, and iii) neither Cell A nor Cell C are CSG cells (ie isCSG_A = false and isCSG_C = false).
[00273] A further example concerning CSG cells (which, in effect, states that cells A and C must both be CSG cells) can be expressed as:
[00274] Cell A parameters can be used to evaluate Cell C, if: i) PLMN_A = PMLN_B or PLMN_A and PMLN_B are equivalent, and ii) F_A = F_C, and iii) Cell A and Cell C are cells of CSG (ie isCSG_A = true and isCSG_C = true).
[00275] A further example concerning CSG cells (which, in effect, states that cells A and C must be, with high probability, the same cell) can be expressed as the above conditions, in which, in addition:
[00276] iv) P_A = P_C
[00277] Other modifications to the above rules may be considered to address the case where different (but equivalent) PLMNs have different re-selection criteria, by modifying rule i), in each or any combination of the above cases to: i) PLMN_A = PMLN_B.
[00278] In another example of the present exposition, previously stored suitability requirements (which may have been obtained as a result of a score-based reselection) should not be used when evaluating cells according to criteria-based reselection rules. priority. In a priority-based reselection algorithm, the threshold parameters
[00279] can be transmitted in the serving cell as described above. In the present example, the restriction on the use of stored suitability criteria parameters may be dependent on the corresponding parameters (signal quality, signal strength) being available in the current serving cell, eg, broadcast by the cell. This is not always the case.
[00280] Figure 9 illustrates this particular example. The process can optionally start with an MS attempting a reselection to a 3G cell. The MS receives the system information blocks (SIBs) from the 3G cell (step 904) and then decodes and stores the received signal code power (RSCP) criteria parameters (step 906). The MS can then evaluate a candidate 3G cell using priority-based reselection rules in the known manner (step 908).
[00281] Conventionally, the MS will then evaluate the candidate cell against the stored RSCP criteria (step 912) and, if the cell does not meet the criteria based on the stored RSCP parameters (step 914), the process will stop and the MS will not reselect for the cell (step 916). If the candidate cell does not meet the criteria (step 914), then the cell will be evaluated to see if it meets the priority-based reselection criteria as stated in section 6.6.6. specification 45.008.
[00282] In accordance with the present exposition, however, the steps covered by the marked area 910 are not to be carried out. In accordance with the present disclosure, in a priority-based radio frequency reselection algorithm, the candidate cell is not to be evaluated using the threshold criteria. These criteria may have been obtained as part of a scoring algorithm and by decoding system information from another cell, or from the same cell.
[00283] In the present example, when the MS has evaluated a candidate cell using the priority-based reselection rules (step 908), then it will determine whether the candidate cell meets the priority-based reselection criteria regardless or without regard to any stored parameters (step 918). If the cell does not meet the criteria, the evaluation will end and the MS will not reselect for the cell (step 916). If the candidate cell actually meets the reselection criteria according to the priority-based reselection rules, the MS will perform a reselection for the cell (step 920).
[00284] In this way, the priority-based reselection algorithm is not harmed by incorrect parameters, which may have been stored during a priority-based reselection. If the parameters were broadcast across the serving cell, they would remain the primary criteria to be used in a priority-based reselection. If the parameters are not broadcast, then the MS must determine the cell's ownership of a reselection, without using stored parameters which may be unreliable.
[00285] Figure 15 illustrates an MS which first reads the system information block (SIB) of a UTRAN cell while camped in a first cell of GSM 1. In the cell of GSM 1, only scoring algorithms are used for reselection for UTRAN cells. The Qrxlevmin parameter is stored in the MS. The MS can perform a reselection from GSM cell 1 to a second GSM cell 2. GSM cell 2 supports priority-based reselection. From the GSM cell 2, the MS can evaluate the UTRAN cell using a priority-based reselection. When performing the priority-based assessment, the MS will not use the stored criteria that were obtained from the UTRAN cell during the scoring algorithm. It is not shown that if the evaluation is successful, the MS will reselect to the UTRAN cell.
[00286] An example algorithm which can be used to implement the above exposition principles will now be described. While the language of the algorithm on which this example is built may be altered or clarified, the principles illustrated by the text which has been inserted and amended, when compared to the original algorithm, are equally applicable to any amended algorithm.
[00287] This is an algorithm for cell reselection from GSM to UMTS based on cell score. The algorithm in this subitem shall be used for reselection from GSM to UMTS if the conditions for using the cell reselection algorithm based on priority information are not satisfied.
[00288] If the 3G cell reselection list includes UTRAN frequencies, the MS must update, at least every 5 s, the RLA_C value for the serving cell and each of at least 6 non-serving GSM cells stronger.
[00289] The MS must then reselect a suitable UTRAN cell (see TS 25.304) if:
[00290] for a TDD cell the measured RSCP value is equal to or greater than TDD_Qoffset for a period of 5 s, and
[00291] for an FDD cell, the following criteria are all met for a period of 5 s:
[00292] Your measured RSCP value exceeds the RLA_C value for the serving cell and all suitable non-serving GSM cells (see 3GPP TS 03.22) by the FDD_Qoffset value,
[00293] your measured Ec/No value is equal to or greater than the FDD_Qmin - FDD_Qmin_Offset value, and
[00294] Your measured RSCP value is equal to or greater than FDD_RSCP_threshold.
[00295] In the case of a cell reselection occurring within the previous 15 seconds, FDD_Qoffset or TDD_Qoffset is increased by 5 dB.
[00296] Ec/No and RSCP are the measured quantities, see sub-item 8.1.5,
[00297] FDD_RSCP_threshold equals FDD_RSCPmin - min((P_MAX - 21 dBm), 3 dB), if FDD_RSCPmin is broadcast in the service cell, otherwise Qrxlevmin + Pcompensation + 10 dB if these parameters are available, otherwise the default value of FDD_RSCPmin,
[00298] Qrxlevmin is the minimum RX level required in the UTRAN FDD cell (dBm), see 3GPP TS 25.304,
[00299] Pcompensation is max(UE_TXPWR_MAX_RACH - P_MAX, 0) (dB), see 3GPP TS 25.304,
[00300] UE_TXPWR_MAX_RACH is the maximum TX power level that an MS can use when accessing the UTRAN FDD cell in RACH (dBm), see 3GPP TS 25.304,
[00301] P_MAX is the maximum RF output power of the MS (dBm) in UTRAN FDD mode, see 3GPP TS 25.304,
[00302] FDD_Qmin, FDD_Qoffset and optionally FDD_RSCPmin and FDD_Qmin_Offset are broadcast in BCCH of the serving cell,
[00303] TDD_Qoffset is broadcast on the BCCH of the serving cell.
[00304] Note 1: The parameters required to determine if a UTRAN cell is suitable are broadcast in BCCH of the UTRAN cell. An MS may start a reselection towards the UTRAN cell prior to decoding the BCCH of the UTRAN cell, leading to a short interruption of service if the UTRAN cell is unsuitable.
[00305] Note 2: if FDD_RSCPmin is broadcast, an optimal GSM to UTRAN reselection performance is obtained, if UTRAN cells in UTRAN coverage edge areas are planned for a UE power of +24 dBm.
[00306] Note 3: The TDD_Qoffsset parameter is an absolute limit for reselection for a target UTRAN TDD cell.
[00307] The MS shall store the above UTRAN cell RSCP suitability criteria parameters, whenever decoded from an equivalent PLMN UTRAN FDD cell, while attempting to camp in the UTRAN FDD cell, unless that the cell is a CSG cell / indicating 'do not store' / is inappropriate because {is part of the “no roaming LA list”} present invention is barred / or would result in an RSCP limit of FDD, which is higher than currently stored for cells at the same frequency greater than [XX] dB. The most recently stored parameters from a UTRAN FDD cell of an equivalent PLMN are valid reselection criteria towards all UTRAN FDD cells except CSG cells and cells evaluated according to the reselection algorithm based on priority (see sub-items 6.6.7 and 6.6.6, respectively). Stored values which were received more than [5] minutes ago must be released. This parameter list must be cleared after a PLMN selection (see 3GPP TS 23.122).
[00308] It should be noted that “/” here is used to distinguish different aspects of the exposure, although they may be combinable.
[00309] A cell reselection for UTRAN shall not occur within 5 seconds after the MS has reselected a GSM cell from a UTRAN cell, if a suitable GSM cell can be found.
[00310] In the event of a reselection attempt towards a barred UTRAN cell, the MS must abandon further reselection attempts towards this cell, as defined by the Tbarred value of the barred UTRAN cell (see 3GPP TS 25.331).
[00311] In case the highest scoring UTRAN cell is not suitable (see 3GPP TS 25.304), due to being part of the “Roaming Prohibited List” or belonging to a PLMN which is not indicated as being equivalent to the PLMN registered, the MS may abandon further reselection attempts towards this UTRAN cell and all other cells on the same frequency, for a period of up to 20 min.. If the MS has to perform a cell selection, this limitation shall be be removed. If the MS is redirected under GERAN control to a frequency for which the timer is running, any limitation on that frequency must be removed.
[00312] If more than one UTRAN cell meets the above criteria, the MS must select the cell with the highest RSCP value.
[00313] An additional example algorithm which can be used to implement the above exposition principles will now be described. Although the language of the algorithm on which this example is built can be changed or clarified, the principles illustrated by the text which has been inserted and changed, when compared to the original algorithm, are equally applicable to any amended algorithm.
[00314] This is an algorithm for inter-RAT cell reselection based on priority information. The algorithm in this subitem shall be used for inter-RAT cell reselection, if priorities are available to the MS and thresholds are provided by the network, and if the mobile station supports priority-based inter-RAT cell reselection and information priority for the service cell is provided by the network. A mobile station supporting E-UTRAN must support a priority-based inter-RAT cell reselection towards all supported RATs. A mobile station not supporting E-UTRAN and supporting UTRAN and supporting priority-based reselection from UTRAN to GERAN must support priority-based inter-RAT cell reselection towards UTRAN.
[00315] The network must provide priority information if E-UTRAN frequencies are included in the neighbor cell list; the network may provide priority information if only UTRAN frequencies are included in the neighbor cell list. If priority information is available to the mobile station and the mobile station supports priority-based inter-RAT cell reselection, the algorithm in this subitem shall be used for inter-RAT reselection towards all RATs. The rules with reference to which set of priorities is valid at any given time are defined in 3GPP TRANSACTION 44.018.
[00316] NOTE 1: “Priority information” includes priorities and thresholds which are related to each UTRAN or E-UTRAN frequency (e.g. UTRAN_PRIORITY, E-UTRAN_PRIORITY, THRESH_UTRAN_high, THRESH_E-UTRAN_high) and information related to the service cell (eg GERAN_PRIORITY, THRESH_GSM_low).
[00317] NOTE 2: Throughout the specification, the phrase “neighbor cell list” shall also include the E-UTRAN cell neighbor list, where appropriate.
[00318] NOTE 3: Priorities must also be provided for network frequencies that do not support priority-based cell reselection.
[00319] If the 3G cell reselection list or the E-UTRAN neighbor cell list includes the frequencies of other radio access technologies, the MS shall at least every 5 s update the RLA_C value for the serving cell and each of at least 6 strongest non-service GSM cells.
[00320] The MS must then reselect a suitable cell (see 3GPP TS 25.304 for UTRAN and 3GPP TS 36.304 for E-UTRAN) from another radio access technology, if the criteria below are met. S_non_serving_XXX is the metering quantity of a non-serving inter-RAT cell and XXX indicates the other radio access technology/mode, and is defined as follows:
[00321] - for a UTRAN cell, is the RSCP value measured for the UTRAN_QRXLEVMIN menu cell for the light emitting layer frequency;
[00322] - for an E-UTRAN cell, is the measured RSRP value for the cell minus E-UTRAN-QRXLEVMIN for the cell frequency, if THRES_E-UTRAN_high_Q is not provided; otherwise, if THRES_E-UTRAN_high_Q is provided, it is the measured RSRQ value for the cell minus E-UTRAN_QQUALQMIN for the cell frequency.
[00323] Stored suitability requirements (eg such as stored RSCP suitability requirements as specified in subitem 6.6.5) shall not be used for UTRAN cells when evaluating cells against the criteria in this subitem.
[00324] For a GSM cell, S_GSM is defined as the C1 value for the cell (see subitem 6.4);
[00325] A cell reselection for a cell of another inter-RAT frequency must be performed if any of the conditions below (to be evaluated in the order shown) is satisfied:
[00326] the S_non-serving_XXX of one or more cells of a higher priority inter-RAT frequency is greater than THRESH_XXX_high (or, in the case of an E-UTRAN target, THRESH_E-UTRAN_high_Q, if provided) during an interval time T_re-selection; in this case, the mobile station shall consider the cells for reselection in descending order of priority and, for cells of the same inter-RAT frequency or of inter-RAT frequencies of equal priority, in descending order of S_non-serving_XXX, and reselect the first cell that satisfies the above conditions;
[00327] S_GSM value is lower than THRESH_GSM_low for a for the serving cell and all GSM cells measured during a time interval T_re-selection; in this case, the mobile station must consider a re-selection of the inter-RAT cells in the following order, and re-select the first one that satisfies the following criteria:
[00328] cells of a lower priority inter-RAT frequency whose S_non-serving_XXX is greater than THRESH_XXX_low (or, in the case of an E-UTRAN target, THRESH_E-UTRAN_low_Q, if provided) during a time interval T_re - selection; these cells must be considered in descending order of priority and, for cells of the same RAT, in descending order of S_non-serving_XXX;
[00329] if no cell satisfies the above criterion, inter-RAT cells for which, during a time interval T_re-selection, S_non-serving_XXX is higher than S_GSM for the serving cell by at least one specific hysteresis H_PRIO; these cells must be considered in descending order from S_non-serving_XXX.
[00330] A UTRAN FDD cell should only be reselected if, in addition to the above criteria, its measured Ec/No value is equal to or greater than FDD_Qmin - FDD_Qmin_Offset.
[00331] If E-UTRAN_Qmin is provided for an E-UTRAN frequency, an E-UTRAN cell at that frequency should only be reselected if, in addition to the above criteria, its measured RSRQ value is equal to or greater than E- UTRAN_Qmin. A mobile station shall store {all / related RSRQ} suitability requirements from an E-UTRAN cell in the same PLMN or in a PLMN equivalent to that of the serving cell, [which attempted a reselection], [unless received an indication from that cell, for example in a system information that the suitability requirements for that cell should not be stored], [or the cell was a CSG cell], [or it was not suitable]. When evaluating an E-UTRAN cell, the most recently stored RSRQ-related suitability requirements received from an E-UTRAN cell [other than those obtained from a CSG cell] at the same frequency / at the same frequency of the same priority shall be used, if E-UTRANQmin is not provided by the service cell.
[00332] If THRESH_E-UTRAN_high_Q is provided for an E-UTRAN frequency, and if E-UTRAN_RSRPmin is provided, an E-UTRAN cell at that frequency shall only be reselected if, in addition to the above criteria, its measured RSRP value is equal to or greater than E-UTRAN_RSRPmin. If E-UTRAN_RSRPmin is not provided, the default value must be used.
[00333] E-UTRAN cells which are included in the disallowed cell list should not be considered as candidates for cell reselection. If the strongest cells on an E-UTRAN frequency are included in the disallowed cell list, the mobile station can reselect the strongest valid cell (see subitem 8.4.7) on that frequency.
[00334] A cell re-selection to a cell of another radio access technology (e.g. a UTRAN or E-UTRAN) must not occur within 5 seconds after the MS has re-selected a GSM cell to an interRAT cell, if a suitable GSM cell can be found.
[00335] If the mobile station applies common priorities or individual priorities received via dedicated signaling and priorities are only available for some inter-RAT frequencies, cells belonging to frequencies for which no priority is available or no threshold is provided by the cell of service shall not be considered for measurement and cell reselection.
[00336] If a mobile station in a normally camped state (see 3GPP TS 43.022) applies individual priorities received through dedicated signaling and no priority is available for the serving cell, the mobile station shall consider any GSM cell (including the service cell) to have a lower priority (that is, lower than the eight configured network values).
[00337] A mobile station in a camped state in any cell (see 3GPP TS 43.022) must ignore individual priorities received through dedicated signaling and must apply priorities received from the serving cell's system information while trying to find a cell proper. If the mobile station supports CS voice services, the MS should avoid reselecting acceptable (but not suitable) E-UTRA cells, regardless of the priorities provided in the system information.
[00338] NOTE 4: If the MS is camping in an acceptable cell, the individual priorities will not be discarded, until an event leading to their detection occurs.
[00339] In the event of a reselection attempt towards a barred UTRAN cell, the MS must abandon further reselection attempts towards this cell, as defined by the Tbarred value of the barred UTRAN cell (see 3GPP TS 25.331).
[00340] In case of a reselection attempt towards a barred E-UTRAN cell, the MS must abandon further reselection attempts towards this UTRAN cell, for a period of up to 20 min..
[00341] In case the highest scoring UTRAN cell is not suitable (see 3GPP TS 25.304), due to being part of the “Roaming Prohibited List” or belonging to a PLMN which is not indicated as being equivalent to the PLMN registered, the MS may abandon further reselection attempts towards this UTRAN cell and all other cells on the same frequency, for a period of up to 20 min.. If the MS has to perform a cell selection, this limitation shall be be removed. If the MS is redirected under GERAN control to a frequency for which the timer is running, any limitation on that frequency must be removed.
[00342] In the event that the MS attempts a reselection for an E-UTRAN cell which is not suitable (see 3GPP TS 36.304), due to being part of the “list of tracking areas prohibited for roaming” (see 3GPP TS 24.301), and if the MS has received the PCID to TA Mapping information element (see 3GPP TS 44.018 and 3GPP TS 344.060) for the cell frequency, it must abandon further reselection attempts towards this UTRAN cell and any cell of E-UTRAN which is known to belong to the same tracking area, until the PCID to TA Mapping information changes in the serving cell, or until a cell reselection occurs. If the mobile station has not received the PCID to TA Mapping information element for the cell frequency, the MS may abandon further reselection attempts towards this E-UTRAN cell and all other cells on the same frequency, for a period of time. up to 20 min. If the MS has to perform a cell selection, this limitation must be removed. If the MS is redirected under GERAN control to a frequency for which the timer is running, any limitation on that frequency must be removed.
[00343] In the event that the MS attempts a reselection for an E-UTRAN cell which is not suitable (see 3GPP TS 36.304), due to belonging to a PLMN which is not indicated as being equivalent to the registered PLMN, the MS may abandon further reselection attempts towards this E-UTRAN cell and all other cells on the same frequency, for a period of up to 20 min. If the MS has to perform a cell selection, this limitation must be removed . If the MS is redirected under GERAN control to a frequency for which the timer is running, any limitation on that frequency must be removed.
[00344] An additional example algorithm which can be used to implement the principles of the above exposition will now be discussed. While the language of the algorithm on which this example is built may be altered or clarified, the principles illustrated by the text which has been inserted and amended, when compared to the original algorithm, are equally applicable to any amended algorithm.
[00345] This is an algorithm for cell selection and reselection for CSG cells and hybrid cells. First, for a cell reselection for CSG cells, if a mobile station is a member of at least one closed subscriber group, i.e. at least one CSG ID is included in the MS CSG whitelist, then in addition to a normal cell reselection, the MS shall use an autonomous search function for the detection of UTRAN and/or E-UTRAN CSG cells. The autonomous search function must detect at least previously visited allowed CSG cells, according to the performance requirements.
[00346] NOTE 1: The autonomous search function is implementation dependent and controls when and/or where to search for allowed CSG cells.
[00347] NOTE 1a: (empty).
[00348] NOTE 2: (empty).
[00349] NOTE 3: (empty).
[00350] If the strongest cell (see 3GPP TS 25.304 and 3GPP TS 36.304 for the definition of the strongest cell) which the MS detected at a frequency of UTRAN or E-UTRAN during a time interval T_re-selection is a cell CSG (see 3GPP TS 25.304 and 3GPP TS 36.304 for suitability criteria for CSG cells of UTRAN and E-UTRAN, respectively), shall reselect for this cell, regardless of the cell reselection rules applicable to the cell in which the MS is currently camped.
[00351] MS should disable autonomous search function for CSG cells if MS has no CSG whitelist or MS CSG whitelist is empty.
[00352] When the MS does not have a CSG whitelist or has an empty one, and the MS has stored a “CSG PSC split information” or “CSG PCI split information”, the MS shall ignore for measurement and cell reselection cells known to be CSG cells, i.e.:
[00353] - cells on a UTRAN frequency with PSC in the stored band “PSC splitting information from CSG” for that frequency (see 3GPP TS 25.331);
[00354] - cells on an E-UTRAN frequency with PCI in the stored band “CSG CI division information” for that frequency (see 3GPP TS 36.331).
[00355] In addition, when the MS does not have a CSG whitelist or has an empty one, the MS may skip to measurement and cell reselection cells known to be CSG cells according to specific means of implementation on a frequency for which no “CSG PSC split information” or “CSG PCI split information” is stored.
[00356] The network may provide information about dedicated UTRAN CSG frequencies and/or dedicated E-UTRAN CSG frequencies. In this case, the MS can use the autonomous search function only on these dedicated frequencies and on the other frequencies listed in the system information. When the MS does not have a CSG whitelist or has an empty one, the MS should ignore those frequencies for measurement and cell reselection.
[00357] A mobile station shall store RSRP / RSCP / RSRQ [ie, signal quality and/or signal strength] related to suitability requirements received from a CSG cell; these must be maintained independently of criteria stored for non-CSG cells. When evaluating a CSG cell, the mobile station shall use the most recently stored values from a [CSG] cell {at the same frequency / with the same CSG ID or, when evaluating a CSG cell, the station mobile must use the values stored from the same cell (or from a cell with the same frequency and PCI/PSC) {provided they were received less than [2] minutes ago.
[00358] Second, for a cell reselection for hybrid cells, if a mobile station is a member of at least one closed subscriber group, then in addition to a normal cell reselection, the MS must use a search function autonomously for the detection of hybrid cells. The autonomous search function must detect at least previously visited hybrid cells whose cell IDs are included in the MS CSG whitelist, according to performance requirements.
[00359] NOTE: Autonomous searching for hybrid cells does not imply that the MS needs to constantly check the CSG IDs of every cell it sees, and the impact on battery consumption should be minimized.
[00360] If a neighboring cell has been detected as a hybrid cell and the CSG ID of the hybrid cell is included in the MS CSG whitelist, a reselection for that cell must follow the rules for CSG cells in subitem 6.6.7.1 . Otherwise, normal cell reselection rules should apply.
[00361] Third, for manual CSG ID selection, if NAS requests AS to search for available CSG IDs, MS shall perform search and report results to NAS as described in 3GPP TS 25.304 for UTRAN and as described in 3GPP TS 36.304 for E-UTRAN. If a CSG ID is manually selected by the NAS, the MS must behave as specified in 3GPP TS 25.304 or 3GPP TS 36.304, depending on the RAT type of the selected CSG cell.
[00362] A further example of the present exposition will now be described.
[00363] In some cases, as part of the typically known reselection algorithm, the device is required to evaluate one or more aspects of the target cell (such as signal quality or signal strength, etc.) broadcast by the service cell (in this example scenario, by cell B).
[00364] However, it is currently required to re-evaluate these aspects once it has read the system information from the candidate cell (cell C), as part of the suitability check (since suitability criteria include tests based on parameters diffused by the candidate cell). This results in the device evaluating the same aspects twice. In a well-configured network, the parameters must be such that a cell, which meets the reselection criteria (based on parameters broadcast in the serving cell) should not fail the corresponding tests based on parameters broadcast in the candidate cell. In this scenario, the second test is redundant.
[00365] However, and even more so, if the device performs evaluations and fails the second test (ie, based on the parameters broadcast in candidate cell C), it will return to the service cell. Then it can repeat this process endlessly, until cell C no longer meets the criteria based on the parameters broadcast by cell B. This is likely a network misconfiguration. In this scenario, the second test may result in the mobile station repeatedly attempting a reselection for the same cell.
[00366] Storing and reusing parameters from cells A or C may address this latter problem, although no provision is currently made in the priority-based reselection scheme for storing criteria from a candidate cell ( see 6.6.6 of 45,008).
[00367] Furthermore, as noted elsewhere, storing the suitability criteria broadcast by cell C in this scenario may cause incorrect abandonment of reselection attempts to other cells (i.e., other than cell C), since a likely problem here is that the C-cell suitability criteria (as determined based on the parameters passed by the C-cell) are set incorrectly, such as the criteria are too high.
[00368] In an additional example implementation of the exposure, it would be preferable for the device not to perform some or any tests (e.g. as part of testing for suitability) based on the criteria broadcast by cell C, if the criteria for reselection with based on parameters broadcast in the service cell have already been tested and met. If the reselection criteria are met and the subset of suitability criteria is met, the device may remain camped in the candidate cell, regardless of the value(s) of the parameter(s) associated with the ) pervasive deviated suitability check(s) in the candidate cell. This process is illustrated in figure 16.
[00369] As an additional example implementation: it should omit only those suitability tests which evaluate specific aspects (signal strength, signal quality), which were tested as part of the reselection procedure. In some cases, only one signal strength/quality could be tested as part of the reselection algorithm.
[00370] As yet another example implementation, it should omit only those tests which evaluate specific aspects (signal strength / signal quality), which were tested as part of the reselection procedure and which were based on parameters the which were broadcast or transmitted by the serving cell (as opposed to using default/standard values).
[00371] As an additional example implementation, the above exception may apply only to “threshold-based” tests (i.e., where a measured quantity of the candidate cell must meet or exceed some given absolute value), but not to “relative value” tests - for example, where a measured value must exceed some other measured value (from the candidate cell, from the service cell and/or from one or more other cells) by some minor difference.
[00372] In an example scenario of the last example implementation, for CSG cells, a candidate CSG cell can meet the reselection criteria if it is the strongest in its frequency. This is considered a 'relative' test of signal strength, rather than an absolute test.
[00373] In typical conventional networks, where a device may currently be required to check suitability criteria twice: once using stored values (obtained from the same or a different cell), and once using the values received from the candidate cell once it has decoded the relevant system information.
[00374] Currently, there is a relatively high risk that the suitability parameters stored by the device and used for the initial suitability assessment (i.e. before candidate cell system information has been received) may differ from those broadcast by the cell candidate itself. Therefore, it is reasonably possible that the suitability criteria can be met with respect to the first test, but not for the second.
[00375] In another example implementation of the exposure, which is illustrated in Figure 16, if a restriction on the use of parameters stored from cell A when evaluating cell C is in effect (such as that they must be in the same frequency or both must be non-CSG cells), then the risk of the parameters being different is significantly reduced. Therefore, in accordance with this example implementation of the exposure, to further reduce the need for parameter evaluation and/or to reduce the risk of a device determining (based on stored parameters) that it is to perform a reselection, it acquires a candidate cell system and then determines that reselection is not possible. The device may omit the second suitability check. This is similar to the omission in the previous example implementation from the exhibit.
[00376] This can be conditional on the frequency of cell A and cell C being the same; optionally, other criteria may apply - such as the physical layer address of cell A and cell C must be the same; in general, any suitable criteria can be used, such as those listed above.
[00377] An additional condition could be that cell A and cell C were both candidates for reselection while the device was initially camped in cell B - for example, in the following case: i) the device is camped in cell B; ii) the device attempts a reselection to cell A; reads suitability criteria for cell A and determines that these are not met; remains in cell B; iii) the device attempts a reselection to cell C - cell C and cell A operate on the same frequency; cell C meets the suitability criteria as obtained from cell A; the device does not re-evaluate the suitability criteria based on the parameters obtained from cell C. (In other words, the device camps at cell C regardless of the suitability parameters signaled by cell C).
[00378] It is worth noting that if operators coordinate the configuration of suitability parameters for cells across a service PLMN or equivalent PLMNs to an extent that these parameters are similar across all cells, then this solution may be applicable , even without any restrictions on cell A and cell C.
[00379] In figure 16, the illustrated process begins with the MS encamped in a service cell, cell B (step 1602). The MS can then optionally receive a neighbor cell list from the serving cell (step 1604). The MS then decodes the reselection parameters from the list (step 1606). The MS then identifies a candidate cell and performs measurements on it (step 1608). If the cell does not meet the reselection criteria, the MS will remain camped in the service cell (step 1610). If the criteria are met, the MS will check that it has stored the suitability parameters available (step 1612). If the MS has stored the available suitability parameters, the MS will check the cell against these criteria (step 1614). If the criteria are not met, the MS will remain camped out in the service cell. If the criteria are met or the MS has no parameters stored and available for testing, the MS will move to acquire system information from the candidate cell (step 1616).
[00380] After acquiring system information, the MS considers radio-related aspects such as signal strength or quality (step 1618). If these were evaluated when determining whether the cell met the reselection criteria (step 1620), and the evaluation was not based on standardized parameters which were not explicitly flagged (step 1622), then the MS will move to check another radio related aspect (step 1626). If there are no more aspects, then the cell will be determined to meet the criteria (step 1632) and the non-radio criteria will be evaluated (step 1634). Thus, if flagged criteria have been used and checked with respect to radio related aspects, then the MS will not redetermine suitability.
[00381] If radio-related aspects were evaluated when determining whether the cell met the reselection criteria (step 1620) and if the evaluation was done based on standardized parameters which were not explicitly flagged (step 1622), then the MS will check whether the assessment used stored suitability parameters (step 1624). If it has done so, the MS will move on to check another radio related aspect (step 1626). If there are no more aspects, then the cell will be determined to meet the criteria (step 1632) and the non-radio criteria will be evaluated (step 1634). Thus, if flagged criteria have been used and checked with respect to radio related aspects, then the MS will not redetermine suitability.
[00382] If the MS has not used the stored suitability parameters (step 1624), the MS will evaluate the cell using parameters from the candidate cell system information (step 1628), by establishing a communication channel, and by decoding of the parameters. If the cell does not meet the criteria, it will be determined to be unacceptable and the MS will remain camped out in the service cell (step 1636). If it really meets the criteria, MS will move on to check another radio-related aspect (step 1626). If there are no more aspects, then the cell will be determined to meet the criteria (step 1632) and the non-radio criteria will be evaluated (step 1634). Thus, if flagged criteria have been used and checked with respect to radio related aspects, then the MS will not redetermine suitability.
[00383] An example algorithm for implementing the examples in the present exposition will now be described. This is an algorithm for inter-RAT cell reselection based on priority information.
[00384] This is an algorithm for inter-RAT cell reselection based on priority information. The algorithm in this subitem shall be used for inter-RAT cell reselection, if priorities are available to the MS and thresholds are provided by the network, and if the mobile station supports priority-based inter-RAT cell reselection and information priority for the service cell is provided by the network. A mobile station supporting E-UTRAN must support a priority-based inter-RAT cell reselection towards all supported RATs. A mobile station not supporting E-UTRAN and supporting UTRAN and supporting priority-based reselection from UTRAN to GERAN must support priority-based inter-RAT cell reselection towards UTRAN.
[00385] The network must provide priority information if E-UTRAN frequencies are included in the neighbor cell list; the network may provide priority information if only UTRAN frequencies are included in the neighbor cell list. If priority information is available to the mobile station and the mobile station supports priority-based inter-RAT cell reselection, the algorithm in this subitem shall be used for inter-RAT reselection towards all RATs. The rules with reference to which set of priorities is valid at any given time are defined in 3GPP TRANSACTION 44.018.
[00386] NOTE 1: “Priority information” includes priorities and limits which are related to each UTRAN or E-UTRAN frequency (e.g. UTRAN_PRIORITY, E-UTRAN_PRIORITY, THRESH_UTRAN_high, THRESH_E-UTRAN_high) and information related to the service cell (eg GERAN_PRIORITY, THRESH_GSM_low).
[00387] NOTE 2: Throughout the specification, the phrase “neighbor cell list” shall also include the E-UTRAN neighbor cell list, where appropriate.
[00388] NOTE 3: Priorities must also be provided for network frequencies that do not support priority-based cell reselection.
[00389] If the 3G cell reselection list or the E-UTRAN neighbor cell list includes the frequencies of other radio access technologies, the MS shall at least every 5 s update the RLA_C value for the serving cell and each of at least 6 strongest non-service GSM cells.
[00390] The MS must then reselect a suitable cell from another radio access technology if the criteria below are met. S_non_serving_XXX is the metering quantity of a non-serving inter-RAT cell and XXX indicates the other radio access technology/mode, and is defined as follows:
[00391] - for a UTRAN cell, is the measured RSCP value for the UTRAN_QRXLEVMIN menu cell for the light emitting layer frequency;
[00392] - for an E-UTRAN cell, is the measured RSRP value for the cell minus E-UTRAN-QRXLEVMIN for the cell frequency, if THRES_E-UTRAN_high_Q is not provided; otherwise, if THRES_E-UTRAN_high_Q is provided, it is the measured RSRQ value for the cell minus E-UTRAN_QQUALQMIN for the cell frequency.
[00393] For a GSM cell, S_GSM is defined as the C1 value for the cell (see subitem 6.4);
[00394] The definition of a suitable cell is specified in 3GPP TS 25.304 for UTRAN and 3GPP TS 36.304 for E-UTRAN. However, for cell reselection purposes, suitability requirements related to signal strength (respectively signal quality ) do not need to be evaluated (i.e., the cell can be considered suitable, even if it does not meet the requirements for signal strength (respectively signal quality), as specified in the suitability definition, using parameters obtained from data from candidate cell system), if: - any: - the signal strength (respectively the signal quality) has been evaluated as part of the reselection algorithm, and - the corresponding parameters used in the reselection algorithm (e.g. for quality for UMTS FDD signal strength, FDDQmin, FDD QminOffset; for UMTS signal strength, UTRAN Qrxlevmin) were explicitly signaled in the serving cell (i.e., the default values were not used), - or: - the cell meets suitability criteria for signal strength (respectively, signal quality), based on stored parameters which were received from a cell operating using the same technology radio access and on the same frequency.
[00395] It should be noted and understood that the list of corresponding parameters above is not exhaustive. Exposure applies where all or some specified portion of the parameters must be explicitly flagged and not default values.
[00396] A cell reselection for a cell of another inter-RAT frequency must be performed if any of the conditions below (to be evaluated in the order shown) is satisfied:
[00397] the S_non-serving_XXX of one or more cells of a higher priority inter-RAT frequency is greater than THRESH_XXX_high (or, in the case of an E-UTRAN target, THRESH_E-UTRAN_high_Q, if provided) during an interval time T_re-selection; in this case, the mobile station shall consider the cells for reselection in descending order of priority and, for cells of the same inter-RAT frequency or of inter-RAT frequencies of equal priority, in descending order of S_non-serving_XXX, and reselect the first cell that satisfies the above conditions;
[00398] S_GSM value is lower than THRESH_GSM_low for a for the serving cell and all GSM cells measured during a time interval T_re-selection; in this case, the mobile station must consider a re-selection of the inter-RAT cells in the following order, and re-select the first one that satisfies the following criteria:
[00399] cells of a lower priority inter-RAT frequency whose S_non-serving_XXX is greater than THRESH_XXX_low (or, in the case of an E-UTRAN target, THRESH_E-UTRAN_low_Q, if provided) during a time interval T_re - selection; these cells must be considered in descending order of priority and, for cells of the same RAT, in descending order of S_non-serving_XXX;
[00400] if no cell meets the above criteria, inter-RAT cells for which, during a time interval T_re-selection, S_non-serving_XXX is higher than S_GSM for the serving cell by at least one specific hysteresis H_PRIO; these cells must be considered in descending order from S_non-serving_XXX.
[00401] A UTRAN FDD cell should only be reselected if, in addition to the above criteria, its measured Ec/No value is equal to or greater than FDD_Qmin - FDD_Qmin_Offset.
[00402] If E-UTRAN_Qmin is provided for an E-UTRAN frequency, an E-UTRAN cell at that frequency should only be reselected if, in addition to the above criteria, its measured RSRQ value is equal to or greater than E- UTRAN_Qmin.
[00403] If THRESH_E-UTRAN_high_Q is provided for an E-UTRAN frequency, and if E-UTRAN_RSRPmin is provided, an E-UTRAN cell at that frequency shall only be reselected if, in addition to the above criteria, its measured RSRP value is equal to or greater than E-UTRAN_RSRPmin. If E-UTRAN_RSRPmin is not provided, the default value must be used.
[00404] E-UTRAN cells which are included in the disallowed cell list should not be considered as candidates for cell reselection. If the strongest cells on an E-UTRAN frequency are included in the disallowed cell list, the mobile station can reselect the strongest valid cell (see subitem 8.4.7) on that frequency.
[00405] A cell re-selection to a cell of another radio access technology (e.g. a UTRAN or E-UTRAN) must not occur within 5 seconds after the MS has re-selected a GSM cell to an interRAT cell, if a suitable GSM cell can be found.
[00406] If the mobile station applies common priorities or individual priorities received through dedicated signaling and priorities are only available for some inter-RAT frequencies, cells belonging to frequencies for which no priority is available or no threshold is provided by the cell of service shall not be considered for measurement and cell reselection.
[00407] If a mobile station in a normally camped state (see 3GPP TS 43.022) applies individual priorities received through dedicated signaling and no priority is available for the serving cell, the mobile station shall consider any GSM cell (including the service cell) to have a lower priority (that is, lower than the eight configured network values).
[00408] A mobile station in a camped state in any cell (see 3GPP TS 43.022) shall ignore individual priorities received through dedicated signaling and shall apply priorities received from the serving cell's system information while trying to find a cell proper. If the mobile station supports CS voice services, the MS should avoid reselecting acceptable (but not suitable) E-UTRA cells, regardless of the priorities provided in the system information.
[00409] NOTE 4: If the MS is camping in an acceptable cell, the individual priorities will not be discarded, until an event leading to their detection occurs.
[00410] In the event of a reselection attempt towards a barred UTRAN cell, the MS must abandon further reselection attempts towards this cell, as defined by the Tbarred value of the barred UTRAN cell (see 3GPP TS 25.331).
[00411] In case of a reselection attempt towards a barred E-UTRAN cell, the MS must abandon further reselection attempts towards this UTRAN cell, for a period of up to 20 min.
[00412] In the event that the MS attempts a reselection for a UTRAN cell which is not suitable (see 3GPP TS 25.304), due to being part of the “Roaming Prohibited List” or belonging to a PLMN which is not is indicated as being equivalent to the registered PLMN, the MS may abandon further reselection attempts towards this UTRAN cell and any other cell on the same frequency, for a period of up to 20 minutes. If the MS has to perform a cell selection, this limitation must be removed. If the MS is redirected under GERAN control to a frequency for which the timer is running, any limitation on that frequency must be removed.
[00413] In the event that the MS attempts a reselection for an E-UTRAN cell which is not suitable (see 3GPP TS 36.304), due to being part of the “list of tracking areas prohibited for roaming” (see 3GPP TS 24.301), and if the MS has received the PCID to TA Mapping information element (see 3GPP TS 44.018 and 3GPP TS 344.060) for the cell frequency, it must abandon further reselection attempts towards this UTRAN cell and any cell of E-UTRAN which is known to belong to the same tracking area, until the PCID to TA Mapping information changes in the serving cell, or until a cell reselection occurs. If the mobile station has not received the PCID to TA Mapping information element for the cell frequency, the MS may abandon further reselection attempts towards this E-UTRAN cell and all other cells on the same frequency, for a period of time. up to 20 min. If the MS has to perform a cell selection, this limitation must be removed. If the MS is redirected under GERAN control to a frequency for which the timer is running, any limitation on that frequency must be removed.
[00414] In the event that the MS attempts a reselection for an E-UTRAN cell which is not suitable (see 3GPP TS 36.304), due to belonging to a PLMN which is not indicated as being equivalent to the registered PLMN, the MS may abandon further reselection attempts towards this E-UTRAN cell and all other cells on the same frequency, for a period of up to 20 min. If the MS has to perform a cell selection, this limitation must be removed . If the MS is redirected under GERAN control to a frequency for which the timer is running, any limitation on that frequency must be removed.
[00415] While the present disclosure is primarily described in terms of methods, a person of ordinary skill in the art will understand that the present disclosure is also directed to various apparatus, such as a portable electronic device, including components for performing at least some aspects and features detector methods described, whether through hardware components, software or any combination of the two, or in any other way. Further, an article of manufacture for use with the apparatus, such as a pre-recorded storage device or other similar computer readable medium including program instructions recorded thereon, or a computer data signal carrying program instructions that can be read by computer, you can drive an apparatus to facilitate the practice of the methods described. It will be understood that such an apparatus, articles of manufacture and computer digital signals also come within the scope of the present exposition.
[00416] The term "computer readable medium" as used herein means any medium which can store instructions for use by or execution by a computer or other computing device, including, but not limited to, a computer floppy disk. portable hard disk drive (HDD), random access memory (RAM), read-only memory (ROM), erasable programmable read-only memory (EPROM) or flash memory, an optical disk, such as a compact disc (CD), a digital versatile disc (DVD), or a Blu-Ray™ disc, and a solid-state storage device (for example, a NAND flash or synchronous dynamic RAM (SDRAM)).
[00417] The example modalities of the present disclosure are not limited to any particular operating system, system architecture, mobile device architecture, server architecture, or computer programming language.
[00418] The various embodiments presented above are merely examples and variations of the innovations described herein, and will be apparent to persons of ordinary skill in the art. As the modalities may be implemented in various forms without departing from the features thereof, it is also to be understood that the modalities described above are not limited by any of the details of the preceding description, unless otherwise specified, but, at the same time, rather, they must be broadly construed within their scope as defined in the appended claims. Therefore, it is intended that various changes and modifications that fall within the scope of the claims, or equivalents of that scope, are therefore intended to be encompassed by the appended claims.
[00419] It is to be noted that the methods as described have actions performed in a particular order. However, it will be clear that the order of any actions performed, where the context permits, may be varied, and thus the ordering as described here is not intended to be limiting.
[00420] It is also to be noted that where a method has been described, protection is also intended to be sought for a device arranged to carry out the method, and where resources have been claimed independently of each other, these may be used. in conjunction with other claimed features.
[00421] Further, it will be appreciated that the apparatus described herein may comprise a single component, such as a wireless telecommunications device or a UTRAN or other user equipment or access network components, a combination of multiples of these components, for for example, in communication with each other or a subnet or a network full of these components.
[00422] The modalities have been described here in relation to 3GPP specifications. However, the method and apparatus described herein are not intended to be limited to the specifications or versions thereof referred to herein, but may be applicable to future versions or other specifications.
[00423] According to an aspect of the disclosure, there can be provided a method performed by a device in a wireless network, the method comprising: storing a parameter of a first cell associated with a characteristic of the first cell; and determining the suitability of a second cell for reselection by the device, wherein, if the second cell has a characteristic in common with said characteristic of the first cell, determining the reselection suitability of the second cell in accordance with said stored parameter .
[00424] The method may further comprise: erasing from the device any previously stored stored parameters associated with said first cell characteristic.
[00425] The characteristic of the first cell may be the carrier frequency of the first cell.
[00426] According to another aspect of the disclosure, there can be provided a method performed by a device in a wireless network, the method comprising: determining the network identification information of said first cell; determining a suitability criterion parameter of a second cell; determining a network identification information of said second cell; and, if said network identification information of said first cell is equal to or equivalent to said network identification information of said second cell, storing said parameter.
[00427] The method may also comprise: after the act of storing said parameter, associating said stored parameter with a characteristic of the second cell and determining the suitability of a third cell for a reselection by the device, in which , if the third cell has a characteristic of the third cell in common with said characteristic of the second cell associated with said stored parameter, determining the reselection suitability of the third cell in accordance with said stored parameter.
[00428] The method may also further comprise: erasing from the device any stored parameters associated with said second cell feature.
[00429] According to another aspect of the disclosure, there can be provided a method performed by a device in a wireless network, the method comprising: determining a suitability criteria parameter of a second cell; determining whether said second cell belongs to a closed subscriber group; and, if said second cell happens to belong to a closed subscriber group, storing said parameter.
[00430] The method may also comprise: after the act of storing said parameter, associating said stored parameter with a characteristic of the second cell and determining the suitability of a third cell for reselection by the device, in which, if the third cell has a characteristic in common with said characteristic of the second cell associated with said stored parameter, determining the reselection suitability of the third cell in accordance with said stored parameter.
[00431] The method may further comprise: erasing from the device any previously stored parameters associated with said second cell feature.
[00432] According to another aspect of the disclosure, a device for use in a wireless network can be provided, the device comprising one or more processors; a wireless transceiver coupled to one or more processors; and a memory coupled to one or more processors, the one or more processors being operative for: storing a parameter of a first cell associated with a characteristic of the first cell; and determining the suitability of a second cell for reselection by the device, wherein, if the second cell has a characteristic in common with said characteristic of the first cell, the reselection suitability of the second cell is determined in accordance with said stored parameter .
[00433] The device may still be operative to: erase from the device any previously stored parameters associated with said first cell characteristic.
[00434] The characteristic of the first cell can also be the carrier frequency of the first cell.
[00435] According to another aspect of the disclosure, there is provided a device for use in a wireless network, the device comprising one or more processors; and a memory coupled to one or more processors, the one or more processors being operative for: communicating with a first cell; determining a network identification information of said first cell; determining a second cell suitability criteria parameter; determining network identification information from said second cell; and, if said network identification information of said first cell is the same as said network identification information of said second cell, storing said parameter.
[00436] The device may still be operative to: after said parameter has been stored, associate said stored parameter with a characteristic of the second cell and determine the suitability of a third cell for reselection by the device, wherein if the third cell has a characteristic in common with said characteristic of the second cell associated with said stored parameter, the reselection suitability of the third cell will be determined in accordance with said stored parameter.
[00437] The device may still be operative to: delete any previously stored parameters associated with said second cell feature.
[00438] According to another aspect of the disclosure, a device for use in a wireless network can be provided, the device comprising one or more processors; and a memory coupled to one or more processors, the one or more processors being operative for: communicating with a first cell; determining a second cell suitability criteria parameter; determining whether said second cell belongs to a closed subscriber group; and, if said second cell fails to belong to a closed subscriber group, storing said parameter.
[00439] The device may still be operative to: after said parameter has been stored, associate said stored parameter with a characteristic of the second cell and determine the suitability of a third cell for reselection by the device, wherein if the third cell has a characteristic in common with said characteristic of the second cell associated with said stored parameter, the reselection suitability of the third cell will be determined in accordance with said stored parameter.
[00440] The device may still be operative for: erasing any previously stored parameters associated with said second cell feature.
[00441] According to another aspect of the disclosure, a device for use in a wireless network can be provided, the method comprising: determining a parameter from a first set of criteria, said criteria being reselection criteria , of a second cell, and, if said parameter satisfies a predetermined condition: determining a system information of said second cell, and determining the suitability of the second cell for reselection by the device using a second set of criteria, the said second set of criteria being suitability criteria, wherein, if said criteria contain the parameter included in said set of re-selection criteria, determining suitability without redetermining said parameter for use in said suitability criteria.
[00442] The method may also comprise: performing a cell reselection for said second cell.
[00443] According to another aspect of the disclosure, a device for use in a wireless network can be provided, the device comprising one or more processors; and a memory coupled to one or more processors, the one or more processors being operative for: determining a parameter from a first set of criteria, said criteria being second cell reselection criteria, and, if said parameter satisfying a predetermined condition: determining a system information of said second cell; and determining the suitability of the second cell for reselection by the device using a second set of criteria, said second set of criteria being suitability criteria, wherein, if said suitability criteria contains the parameter included in said set of reselection criteria , the device being operative for determining suitability without redetermining said parameter for use in said suitability criteria.
[00444] The method according to the first aspect may also further comprise: if the second cell is determined to be suitable according to said stored parameter, acquiring a system information from the second cell.
[00445] The method according to the first aspect may also further comprise: if the second cell is determined to be unsuitable according to said stored parameter, omitting to stop acquiring system information from the second cell.
[00446] According to another aspect of the disclosure, there can be provided a method performed by a device in a first cell of a radio access network, the method comprising evaluating an aspect of a second cell with respect to a criterion reselecting, receiving a system information from said second cell; and determining the suitability of said second cell, without evaluating said aspect with respect to a suitability criterion using parameters received in said system information.
[00447] The method may further comprise: performing cell reselection for said second cell.
[00448] According to another aspect of the disclosure, there can be provided a method performed by a device in a first cell of a radio access network, the method comprising evaluating an aspect of a second cell with respect to a criterion of stored suitability, receiving a system information from said second cell; and determining the suitability of said second cell without evaluating said aspect with respect to a suitability criterion using parameters received in said system information.
[00449] The method may further comprise: performing cell reselection for said second cell.
[00450] Additionally, the characteristic of the second cell can be determined by referring to one or more aspects of the physical layer, in isolation or in combination with data stored in the UE.

权利要求:
Claims (19)
[0001]
1. Method in a wireless cellular telecommunications device camped in a service cell (602), the device storing a parameter obtained from a first cell other than the service cell, the method characterized in that it comprises: measuring an attribute of a signal received from a candidate cell (608); and evaluating the candidate cell for a reselection (610), wherein, if the candidate cell has an identifier equivalent to an identifier of the first cell, the candidate cell's evaluating for a reselection will be based on at least the measured attribute and in the stored parameter (614), otherwise the evaluation of the candidate cell for a reselection will be performed without using the stored parameter.
[0002]
2. Method according to claim 1, characterized in that, if the candidate cell has an identifier equivalent to the identifier of the first cell, the evaluation includes determining whether the candidate cell (608) meets the reselection requirements, in that if the measured attribute fails to exceed the stored parameter by a first predetermined amount, the evaluation includes determining that the candidate cell does not meet the reselection requirements.
[0003]
3. Method according to claim 2, characterized in that the first predetermined amount is +10 dB.
[0004]
4. Method in a wireless cellular telecommunications device camped in a service cell (702), the device storing a parameter obtained from system information of a first cell other than the service cell, the method characterized in that comprises: measuring an attribute of a signal received from a candidate cell (708); determining whether the candidate cell is a closed subscriber group cell; and evaluating the candidate cell for a reselection, wherein, if the candidate cell is determined to be a closed subscriber group cell (714), the candidate cell (608) evaluating for a reselection will be based on at least in the measured attribute independently of the first stored parameter, said first stored parameter indicating a minimum value for the measured attribute.
[0005]
5. Method according to claim 4, characterized in that the device has a second stored parameter obtained from a closed subscriber group cell and wherein the first cell is not a closed subscriber group cell, wherein, if the candidate cell (608) is determined to be a closed subscriber group cell (714), the candidate cell's evaluation for a reselection (610) will be based on at least the measured attribute and the second stored parameter .
[0006]
6. Method according to claim 5, characterized in that, if the evaluation is based on at least the measured attribute and the second stored parameter, the evaluation includes determining whether the cell meets reselection requirements (610) , wherein, if the measured attribute fails to exceed the second stored parameter by a first predetermined amount, the candidate cell (608) is determined not to meet the reselection requirements (610).
[0007]
7. Method according to claim 6, characterized in that the first predetermined amount is +10 dB.
[0008]
Method according to any one of claims 5 to 7, characterized in that if the candidate cell has an identifier equivalent to an identifier of the second cell and the candidate cell (608) is determined to be a group cell subscriber (714), the evaluation of the candidate cell for a reselection (610) is based on at least the second stored parameter, otherwise, the evaluation of the candidate cell (608) for a reselection is performed without using the second parameter stored.
[0009]
9. Method according to any one of claims 1 to 3 or 8, characterized in that the identifier is a physical layer identifier.
[0010]
Method according to claim 9, characterized in that the identifier is a primary scrambling code and the candidate cell (608) has a carrier frequency matching a carrier frequency of the second cell and the candidate cell (608). ) has a primary scrambling code matching the primary scrambling code of the second cell and the candidate cell is determined to be a closed subscriber group cell, the candidate cell (608) evaluates for a reselection (610) with based on at least the measured attribute and the second stored parameter, otherwise, the evaluation of the candidate cell (608) for a reselection is performed without using the second stored parameter.
[0011]
11. Method according to any one of claims 1 to 10, characterized in that, if the evaluation is performed without using the stored parameter, the evaluation of the candidate cell (608) includes: determining whether the measured attribute exceeds the a predetermined default value; and, if the measured attribute fails to exceed the predetermined default value, determining that the candidate cell (608) does not meet the reselection requirements (610).
[0012]
12. Method according to any one of claims 1 to 11, characterized in that the candidate cell is a UTRAN cell.
[0013]
13. Method according to any one of claims 1 to 12, characterized in that it further comprises performing the reselection (610) from the service cell to the candidate cell (608) based on the evaluation (624, 724). ).
[0014]
Method according to any one of claims 1 to 13, characterized in that the evaluation of the candidate cell (608) includes: acquiring system information from the candidate cell, the system information including a parameter; determining whether the measured attribute exceeds the candidate cell parameter by a second predetermined amount; and if the measured attribute exceeds the candidate cell parameter by the second predetermined amount, performing reselection (610) of the candidate cell (608).
[0015]
15. Method according to claim 14, characterized in that the second predetermined amount is
[0016]
16. Method, 0 dB. according to any one of claims 1 to 15, characterized in that the stored parameter indicates a minimum required reception level.
[0017]
17. Method according to any one of claims 1 to 16, characterized in that the measured attribute is a received signal code power (RSCP).
[0018]
18. Wireless cellular telecommunications device, characterized in that it is adapted for: camping in a service cell; storing a parameter obtained from a first cell; and carrying out the method as defined in any one of claims 1 to 17.
[0019]
19. Storage medium that can be read in a computer, characterized by the fact that it has instructions stored in it which can be executed by a device to carry out the actions of the method, as defined in any one of claims 1 to 17.

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法律状态:
2018-01-02| B25D| Requested change of name of applicant approved|Owner name: BLACKBERRY LIMITED (CA) |

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2018-01-23| B25G| Requested change of headquarter approved|Owner name: BLACKBERRY LIMITED (CA) |

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2018-12-18| B06F| Objections, documents and/or translations needed after an examination request according [chapter 6.6 patent gazette]|

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2020-05-19| B06U| Preliminary requirement: requests with searches performed by other patent offices: procedure suspended [chapter 6.21 patent gazette]|

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2020-06-30| B15G| Petition not considered as such [chapter 15.7 patent gazette]|Free format text: NAO CONHECIDA A PETICAO NO 020130072956 DE 29/08/2013, EM VIRTUDE DO DISPOSTO NO ARTIGO 219 INCISO II DA LPI NO 9.279/96, UMA VEZ QUE NAO TEM FUNDAMENTACAO LEGAL. |

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2021-10-26| B09A| Decision: intention to grant [chapter 9.1 patent gazette]|

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2022-01-11| B16A| Patent or certificate of addition of invention granted [chapter 16.1 patent gazette]|Free format text: PRAZO DE VALIDADE: 20 (VINTE) ANOS CONTADOS A PARTIR DE 30/11/2011, OBSERVADAS AS CONDICOES LEGAIS. PATENTE CONCEDIDA CONFORME ADI 5.529/DF, QUE DETERMINA A ALTERACAO DO PRAZO DE CONCESSAO. |

优先权:

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申请号 | 申请日 | 专利标题

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US41831210P| true| 2010-11-30|2010-11-30|

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US61/418,312|2010-11-30|

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PCT/EP2011/071443|WO2012072712A1|2010-11-30|2011-11-30|Cell re-selection in a cellular telecommunications network|

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