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    • 专利摘要:
    ACQUISITION OF TIMING AND / OR FREQUENCY PER CELL AND ITS USE IN CHANNEL ESTIMATES IN WIRELESS NETWORKS. A computer program method, apparatus and product for wireless communication are provided where a system timing is estimated, derived from the timing of one or more cells, a timing deviation is determined for a plurality of cells with respect to timing of estimated system, and signals received from the plurality of cells are processed using the time offsets. In addition, a method, an apparatus, and a computer program product for wireless communication are provided in which a carrier frequency is estimated, derived from a frequency of one or more cells, a frequency deviation is determined for a plurality of cells with respect to the estimated system timing, and received signals form the plurality of cells and are processed using frequency deviations.
    公开号:BR112012011661B1
    申请号:R112012011661-4
    申请日:2010-11-19
    公开日:2021-02-23
    发明作者:Tao Luo；Taesang Yoo；Xiaoxia Zhang；Ke Liu
    申请人:Qualcomm Incorporated；
    IPC主号:
    专利说明:

    Field
    [0001] The present description generally refers to communication systems, and more particularly, to the use of timing pickup per cell, frequency pickup per cell, or a combination thereof, for channel estimation in wireless networks. Foundations
    [0002] Wireless communication systems are widely developed to provide various telecommunications services such as telephony, video, data, messaging, and broadcasts. Typical wireless communication systems can employ multiple access technologies capable of supporting communication with multiple users by sharing available system resources (for example, bandwidth, transmission power). Examples of such multiple access technologies include code division multiple access systems (CDMA), time division multiple access systems (TDMA), frequency division multiple access systems (FDMA), division multiple access systems orthogonal frequency (OFDMA), single carrier frequency division multiple access systems (SC-FDMA), and time division synchronized code division multiple access systems (TD-SCDMA).
    [0003] These multiple access technologies have been adopted in various telecommunications standards to provide a common protocol that allows different wireless devices to communicate at a municipal, national, regional or even global level. An example of an emerging telecommunication standard is Long Term Evolution (LTE). LTE is a set of improvements to the mobile standard of the Universal Mobile Telecommunications System (UMTS) promulgated by the Third Generation Partnership Project (3GPP). It is designed to better support mobile broadband Internet access by improving spectral efficiency, reduced costs, improved services, use of new spectrum and better integration with other open standards using OFDMA on downlink (DL), SC-FDMA on link ascending (UL) and antenna technology of multiple inputs and multiple outputs (MIMO). However, as the demand for access to mobile broadband continues to grow, there is a need to further improve LTE technology. Preferably, these improvements should be applicable to other multiple access technologies and telecommunication standards that employ these technologies. summary
    [0004] In some situations, a UE may need to connect to a weak cell instead of the nearest strong cell. For example, this can occur during range expansion or where the strongest cell can be a closed subscriber group (CSG) cell. In such situations, it may be beneficial for the UE to track the timing, carrier frequency, or both of the stronger cell instead of the weaker server cells. As a UE tracks a single timing (be it the timing of a server cell, the timing of a strong interferer, or a compound timing), there is naturally a gap between the timing that the UE is tracking and the timing of each cell that the UE wants to monitor.
    [0005] In the aspects of description, methods, devices and computer program products for wireless communication are provided, generally involving the estimation of system timing, where the estimated system timing is derived from the timing of one or more cells, determination of the timing shifts, with respect to the estimated system timing, for a plurality of cells, and processing of signals received from the plurality of cells with a set of channel tapping windows determined based on the timing shifts .
    [0006] In aspects of the description, methods, devices and computer program products for wireless communication are provided, usually involving the estimation of a carrier frequency, where the estimated frequency is derived from the frequency of one or more cells, determination of the displacements frequency, with respect to the estimated carrier frequency, for a plurality of cells, and processing signals received from the plurality of cells based on one or more frequency shifts. Brief Description of Drawings
    [0007] Figure 1 is a conceptual diagram illustrating an example of a hardware implementation for an appliance employing a processing system;
    [0008] Figure 2 is a conceptual diagram illustrating an example of a network architecture;
    [0009] Figure 3 is a conceptual diagram illustrating an example of an access network;
    [0010] Figure 4 is a conceptual diagram of an example of a frame structure for use in an access network.
    [0011] Figure 5 is a conceptual diagram illustrating an example of a radio protocol architecture for the user and control plan;
    [0012] Figure 6 is a conceptual diagram illustrating an example of an eNodeB and UE in an access network;
    [0013] Figure 7 is a conceptual diagram illustrating a UE receiving signals from a plurality of eNósB;
    [0014] Figure 8 is a flow chart of a wireless communication method;
    [0015] Figure 9 is another flow chart of a wireless communication method;
    [0016] Figure 10 is a conceptual block diagram illustrating the functionality of an illustrative device;
    [0017] Figure 11 is a flow chart of a wireless communication method;
    [0018] Figure 12 is another flow chart of a wireless communication method. Detailed Description
    [0019] The detailed description presented below with respect to the attached drawings should serve as a description of the various configurations and should not represent the only ones with figures in which the concepts described here can be practiced. The detailed description includes specific details for the purpose of providing an in-depth understanding of the various concepts. However, it will be apparent to those skilled in the art that these concepts can be practiced without these specific details. In some cases, well-known structures and components are illustrated in the form of a block diagram in order to avoid obscuring such concepts.
    [0020] Various aspects of telecommunication systems will be presented with reference to various devices and methods. These devices and methods will be described in the detailed description below and illustrated in the attached drawings by various blocks, modules, components, circuits, steps, processes, algorithms, etc. (collectively referred to as "elements"). These elements can be implemented using electronic hardware, computer software, or any combination of them. Whether these elements are implemented as hardware or software depends on the particular application and the design restrictions imposed on the system as a whole.
    [0021] By way of example, an element, or any part of an element, or any combination of elements can be implemented with a "processing system" that includes one or more processors. Examples of processors include microprocessors, micro controllers, digital signal processors (DSPs), field programmable port sets (FPGAs), programmable logic devices (PLDs), state machine, gated logic, discrete hardware circuits or other suitable configured hardware to carry out the various features described throughout this description. One or more processors in the processing system can run software. Software should be considered broadly to mean instructions, instruction sets, code, code segments, program code, programs, subprograms, software modules, applications, software applications, software packages, routines, subroutines, objects , executable elements, sequences of execution, procedures, functions, etc., where referred to as software, firmware, middleware, micro code, hardware description language, or otherwise. The software may reside in a computer-readable medium. A computer-readable medium may include, for example, a magnetic storage device (for example, hard disk, floppy disk, magnetic strip), an optical disk (for example, compact disk (CD), digital versatile disk (DVD) ), a smart card, a flash memory device (eg, card, stick, key drive), random access memory (RAM), read-only memory (ROM), programmable ROM (PROM), erasable PROM (EPROM) , Electrically eliminable PROM (EEPROM), register, removable disk, carrier wave, transmission line and any other means suitable for the storage or transmission of software. The computer-readable medium can reside within the processing system, outside the processing system, or it can be distributed across multiple entities including the processing system. The computer-readable medium can be embodied in a computer program product. For example, a computer program product may include a computer-readable medium in the packaging materials. Those skilled in the art will recognize how best to implement the described functionality presented throughout this description depending on the particular application and design restrictions imposed on the system as a whole.
    [0022] Figure 1 is a conceptual diagram illustrating an example of a hardware implementation for a device 100 employing a processing system 114. In this example, the processing system 114 can be implemented with a bus architecture, generally represented by the bus 102. Bus 102 can include any number of interconnect buses and bridges depending on the specific application of the processing system 114 and design constraints as a whole. Bus 102 connects several circuits including one or more processors, usually represented by processor 104, and computer-readable media, usually represented by computer-readable medium 106. Bus 102 can also connect several other circuits such as timing sources, peripherals, voltage regulators, and power management circuits that are well known in the art and therefore will not be described further. A bus interface 108 provides an interface between bus 102 and a transceiver 110. Transceiver 110 provides a means of communicating with various other devices via a transmission means. Depending on the nature of the device, a 112 user interface (for example, keyboard, monitor, speaker, microphone, joystick) may also be provided.
    [0023] Processor 104 is responsible for managing bus 102 and general processing, including running software stored in computer-readable medium 106. The software, when run by processor 104, causes processing system 114 to perform the various functions described below for any particular device. Computer-readable medium 106 can also be used for storing data that is handled by processor 104 when running the software.
    [0024] An example of a telecommunications system employing several devices will now be presented with reference to an LTE network architecture as illustrated in figure 2. The LTE 200 network architecture is illustrated with a core network 202 and an access network 204. In this example, core network 202 provides packet-swapped services for access network 204, however, as those skilled in the art will readily appreciate, the various concepts presented throughout this description can be extended to core networks providing circuit-swapped services.
    [0025] The access network 204 is illustrated with a single device 212, which is commonly referred to as an evolved Node B in LTE applications, but can also be referred to by those skilled in the art as a base station, a base transceiver station, a radio base station, a radio transceiver, a transceiver function, a basic service set (BSS), an extended service set (ESS), or some other suitable terminology. ENóB 212 provides an access point for core network 202 for a mobile device 214. Examples of a mobile device include a cell phone, a smart phone, a session initiation protocol (SIP) phone, a laptop, an assistant personal digital device (PDA), a satellite radio, a global positioning system, a multimedia device, a video device, a digital audio device (for example, an MP3 player), a camera, a game console, or any other device of similar operation. Mobile device 214 is commonly referred to as a UE in LTE applications, but can also be referred to by those skilled in the art as a mobile station, a subscriber station, a mobile unit, a subscriber unit, a wireless unit, a remote unit , a mobile device, a wireless device, a wireless communications device, a remote device, a mobile subscriber station, an access terminal, a mobile terminal, a wireless terminal, a remote terminal, an appliance, an agent user, a mobile client, a client, or some other suitable terminology.
    [0026] The core network 202 is illustrated with several devices including a packet data node access circuit (PDN) 208 and a server access circuit 210. The PDN access circuit 208 provides a connection to the access network 204 for a 206 packet-based network. In this example, the 206 packet-based network is the Internet, but the concepts presented throughout this description are not limited to Internet applications. The primary function of the PDN 208 access circuit is to provide the UE 214 with network connectivity. Data packets are transferred between the PDN 208 access circuit and the UE 214 through the server access circuit 210, which serves as the local mobility anchor as the UE 214 wanders through the access network 204.
    [0027] An example of an access network in an LTE network architecture will now be presented with reference to figure 3. In this example, the access network 300 is divided into several cellular regions (cells) 302. An eNodeB 304 is assigned to a cell 302 and is configured to provide an access point to a core network 202 (see figure 2) for all UEs 306 in cell 302. There is no centralized controller in this example of an access network 300, but a centralized controller can be used in alternative configurations. ENóB 304 is responsible for all radio related functions including radio support control, admission control, mobility control, programming, security and connectivity for server 210 access circuit in core 202 network (see figure 2).
    [0028] The modulation and multiple access scheme employed by the access network 300 may vary depending on the particular telecommunications standard being developed. In LTE applications, OFDM is used in DL and SC-FDMA is used in UL to support both frequency division duplexing (FDD) and time division duplexing (TDD). As those skilled in the art will readily appreciate from the detailed description that follows, the various concepts presented here are well suited for LTE applications. However, these concepts can be readily extended to other telecommunication standards using other modulation and multiple access techniques. For example, these concepts can be extended to EV-DO or UMB. EV-DO and UMB are air interface standards promulgated by 3GPP2 with part of the CDMA2000 family of standards and employs CDMA to provide broadband Internet access for mobile stations. These concepts can also be extended to Universal Terrestrial Radio Access (UTRA) employing Broadband CDMA (W-CDMA) and other variations of CDMA, such as TD-SCDMA; Global System for Mobile Communications (UMB) employing TDMA; and Evolved UTRA (E-UTRA), Ultra Mobile Broadband (UMB), IEEE 802.11 (Wi-Fi), IEEE 802.16 (WiMAX), IEEE 802.20, and Flash-OFDM using OFDMA. UTRA, E-UTRA, UMTS, LTE and GSM are described in documents of the organization 3GPP2. The actual wireless communication standard and multiple access technology employed will depend on the specific application and design restrictions imposed on the system as a whole.
    [0029] eNóB 304 can have multiple antennas supporting MIMO technology. The use of MIMO technology allows eNóB 304 to explore the spatial domain to support spatial multiplexing, beam formation, and transmission diversity.
    [0030] Spatial multiplexing can be used to transmit different sequences of data simultaneously on the same frequency. The data streams can be transmitted to a single UE 306 to increase the data rate or to multiple UEs 306 to increase the total capacity of the system. This is achieved by the spatial pre-coding of each data sequence and then transmission of each spatially pre-coded sequence through a different transmitting antenna on a downlink. The spatially pre-coded data streams reach UEs 306 with different spatial signatures, which allows each UE 306 to retrieve one or more data strings destined for that UE 306. In an uplink, each UE 306 transmits a data stream spatially pre-coded, which allows eNodeB 304 to identify the source of each spatially pre-coded data sequence.
    [0031] Spatial multiplexing is generally used when channel conditions are good. When channel conditions are less favorable, beam formation can be used to focus on the transmission energy in one or more directions. This can be achieved by spatial pre-coding the data for transmission over multiple antennas. To achieve good coverage at the edges of the cell, a single sequence beam-forming transmission can be used in combination with the diversity of transmission.
    [0032] In the detailed description that follows, several aspects of an access network will be described with reference to a MIMO system supporting OFDM in downlink. OFDM is a spread spectrum technique that modulates data across various frequencies. Spacing provides "orthogonality" that allows a receiver to retrieve data from subcarriers. In the time domain, a protection interval (for example, cyclic prefix) can be added to each OFDM symbol to combat inter-symbol-OFDM interference. The uplink can use SC-FDMA in the form of a DFT spreading OFDM signal to think about the high peak-to-average power ratio (PARR).
    [0033] Several frame structures can be used to support DL and UL transmissions. An example of a DL frame structure will now be presented with reference to figure 4. However, as those skilled in the art will readily appreciate, the frame structure for any particular application can be different depending on any number of factors. In this example, a frame (10 ms) is divided into 10 subframes of equal size. Each subframe includes two consecutive time partitions.
    [0034] A resource grid can be used to represent two time partitions, each time partition including a resource block. The resource grid is divided into multiple resource elements. In LTE, a resource block contains 12 consecutive subcarriers in the frequency domain and, for a normal cyclic prefix in each OFDM symbol, 7 consecutive OFDM symbols in the time domain, or 84 resource elements. The number of bits carried by each resource element depends on the modulation scheme. Thus, the more resource blocks that an UE receives and the larger the modulation scheme, the higher the data rate for the UE.
    [0035] The radio protocol architecture can take many forms depending on the particular application. An example for an LTE system will now be presented with reference to figure 5. Figure 5 is a conceptual diagram illustrating an example of the radio protocol architecture for the user and control plans.
    [0036] Turning to figure 5, the radio protocol architecture for the UE and eNóB is illustrated with three layers: Layer 1, Layer 2, Layer 3. Layer 1 is the lowest layer and implements several processing functions physical layer signal. Layer 1 will be referred to here as physical layer 506. Layer 2 (layer L2) 508 is above physical layer 506 and is responsible for the link between the UE and eNodeB through physical layer 506.
    [0037] In the user plane, the L2 layer 508 includes a sub-layer of access control to medium (MAC) 510, a sub-layer of radio link control (RLC) 512, and a sub-layer of packet data convergence protocol (PDCP ) 514, which are closed in the eNodeB on the network side. Although not shown, the UE may have several upper layers above the L2 508 layer including a network layer (for example, IP layer) that is terminated in the PDN access circuit (see figure 2) on the network side, and a layer application that terminates at the other end of the connection (for example, furthest UE, server, etc.).
    [0038] The PDCP 514 sublayer provides multiplexing between different radio supports and logical channels. The PDCP 514 sublayer also provides header compression for upper layer data packets to reduce radio transmission overhead, security for encrypting data packets, and transfer support for UEs between eNósB. The RLC 512 sublayer provides segmentation and re-assembly of upper layer data packets, retransmission of lost data packets, and reordering of data packets to compensate for out-of-order reception due to HARQ. The MAC 510 sublayer provides multiplexing between logical and transport channels. The MAC 510 sublayer is also responsible for allocating the various radio resources (for example, resource blocks) in a cell between the UEs. The MAC 510 sublayer is also responsible for HARQ operations.
    [0039] In the control plane, the radio protocol architecture for UE and eNodeB is substantially the same for the physical layer 506 and the L2 layer 508 with the exception that there is no header compression function for the control plane. The control plan also includes an RRC 516 sublayer on Layer 3. The RRC 516 sublayer is responsible for obtaining radio resources (that is, radio supports) and for configuring the lower layers using the RRC signaling between the eNóB and the UE .
    [0040] Figure 6 is a block diagram of an eNodeB in communication with a UE on an access network. In DL, the upper layer packets of the core network are provided for a transmission processor (TX) L2 614. The processor TX L2 614 implements the use of a Fast Fourier Transformation (FFT). The frequency domain signal comprises a separate OFDM symbol sequence for each OFDM signal sub-carrier. The symbols in each subcarrier, and the reference signal, are retrieved and demodulated by determining the most likely signal constellation points transmitted by eNóB 610. These soft decisions can be based on channel estimates computed by the channel estimator 658. The soft decisions are then decoded and deinterleaved to retrieve the data and control signals that were originally transmitted by eNóB 610 on the physical channel. The data and control signals are then provided to an RX L2 660 processor.
    [0041] The RX L2 660 processor implements the L2 layer functionality previously described with reference to figure 5. More specifically, the RX L2 660 processor provides the demultiplexing between the transport and logical channels, repackages data packets in layer packets upper, decrypts the upper layer packets, decompresses the headers and processes the control signals. The upper layer packets are then supplied to a 662 data store, which represents all protocol layers above the L2 layer. The RX L2 660 processor is also responsible for error detection using an ACK / NACK protocol to support HARQ operations. Control signals are provided for an RX 661 radio resource controller.
    [0042] In UL, a data source 667 is used to supply data packets to a transmission L2 processor (TX) 664. Data source 667 represents all protocol layers above the L2 layer (L2). Similar to the functionality described with respect to DL transmission by eNóB 610, the L2 TX 664 processor implements the L2 layer for the user plane and the control plane. The latter is in response to a TX 665 radio resource controller. The TX 668 data processor implements the physical layer. Channel estimates derived by a channel estimator 658 from a reference or feedback signal transmitted by eNodeB 610 can be used by the TX 668 data processor to select the appropriate coding and modulation schemes, and to facilitate spatial processing. The spatial sequences generated by the TX 668 data processor are provided to different antennas 652 via separate transmitters 654 TX. Each 654TX transmitter modulates an RF carrier with a respective spatial sequence for transmission.
    [0043] The UL transmission is processed in eNóB 610 in a similar way to that described with respect to the receiving function in UE 650. Each 618RX receiver receives a signal through its respective antenna 620. Each 618RX receiver retrieves the modulated information in a carrier RF and provides the information for an RX 670 data processor. The RX 670 data processor implements the physical layer and the L2 TX 672 processor implements the L2 layer. The upper layer packets of the L2 RX processor can be delivered to the core network and control signals can be delivered to an RX 676 radio resource controller.
    [0044] Figure 7 is a conceptual diagram illustrating a UE 708 receiving signals from a plurality of eNósB 702, 704, 706. In some situations, a UE may need to connect with a weaker cell instead of the stronger cell. As an example, for the expansion of beech, it may be beneficial to associate a UE with a weaker cell with less loss of path although the cell's transmission power may be less than the strongest cell. In addition, the strongest cell may be a closed subscriber group (CSG) cell, and therefore may not be accessible to the UE.
    [0045] In such situations, it may be beneficial for the UE to track the timing, carrier frequency, or both of the stronger cell instead of the weaker serving cell. Conventionally, an EU timing tracking circuit (TTL) and frequency tracking circuit (FTL) attempt to obtain the timing and frequency of the server cell. In certain situations, however, it may be beneficial for a UE to track the timing / frequency of the serving cell, timing / frequency for a dominant interferer, or combined timing / frequency for all cells, including the serving cell and all interferers. Benefits may include, for example, improved signal cancellation from interference cells.
    [0046] As an UE tracks a single delay (be it a server cell delay, a strong interferer delay, or a composite delay), there is naturally a space between the delay of the UE it is tracking (that is, the delay of the UE with respect to the timing alignment of a frame, the subframes within the frame, and the OFDM symbols within each subframe) and the timing of each cell that the UE wants to monitor. For example, with reference to figure 7, there may be a space between the timing of the UE 708 you are tracking and the timing of each of the eNósB 702, 704. 706.
    [0047] According to certain aspects presented here, UE 708 can track a single system timing and / or system frequency and estimate the timing per cell or frequency shifts for each cell. System and / or frequency timing can be derived from a single cell (for example, with a stronger receive signal strength) or from multiple cells. As a simple example, a first cell (for example, "cell A" with eNodeB 702) can have a frequency of 2GHz + 100 Hz and a second cell ("cell B" with eNodeB 704) can have a frequency of 2GHz + 200 Hz. Considering that the UE 708 sees similar received powers from the two cells, the UE may wish to track 2GHz + 150 Hz and determine the frequency error per cell in cell A as -50 Hz (with respect to the tracked frequency of 2GHz + 150 Hz) and cell B as + 50 Hz. In other words, in this example, UE 708 is not tracking the frequency of any particular cell, but instead is tracking an average frequency of the two cells. Similarly, for timing tracking a UE can track single cell timing or "composite" timing derived from multiple cell timing.
    [0048] The cell timing of a cell can be estimated using signals transmitted from the cells, such as a cell specific reference signal (CRS), a primary synchronization signal (PSS), a secondary synchronization signal (SSS ), or cyclic prefix (CP). The timing offset per cell can be estimated simultaneously, assuming the UE 708 has adequate duplicated hardware, or the offset can be estimated sequentially. Timing displacement estimates per cell can be used to improve the performance of UE 708, for example, by increasing the accuracy of the channel estimate between UEs and different eNósB. In one configuration, tracking with particular timing is performed by combining signals from the cells. The signals include at least one of the CRS, PSS, SSS tones or a cyclic prefix. In one configuration, the signals are combined according to specific signal strengths.
    [0049] As noted above, as the UE 708 tracks the carrier frequency (or frequency error with respect to a particular carrier frequency) of a single cell (either a serving cell or a strong interferer) or a compound frequency shift , there is a space between the carrier frequency that the UE 708 is tracking (that is, the carrier frequency including the carrier frequency error to which the UE is tuned) and the carrier frequency error of each cell that the UE 708 wants to monitor.
    [0050] As such, according to certain aspects, UE 708 can also estimate the frequency shift per cell of each cell. The frequency shift per cell of a cell is the shift between the carrier frequency (or frequency error) that the UE is tracking (tuned) and the frequency error of a particular cell that the UE 708 is tracking. The frequency shift per cell of a cell can also be estimated by using signals transmitted from the cell (for example, RS tones, PSS, SSS, cyclic prefix, etc.). Frequency shift estimates per cell can also be used to improve the performance of UE 708. Additionally, carrier frequency error estimates per cell can be used to track a particular carrier frequency error. In one configuration, tracking of the particular carrier frequency error is performed by combining signals from the cells. The signals include at least one of the CRS, PSS, SSS tones or a cyclic prefix. In a configuration, the signals are combined according to the strengths received from the signals.
    [0051] In some cases, what the UE 708 may be tracking (estimating) is the error or displacement of the eNB carrier frequency from the known carrier frequency value. For example, it is assumed that the carrier frequency is 2GHz, which is known in the UE through a cell capture procedure. It is also assumed that the eNóB 704 oscillator is operating at 2GHz + 100 Hz and the eNóB 706 oscillator is operating at 2GHz + 200 Hz. In this case, the average carrier frequency error is 150 Hz, the carrier frequency error eNodeB 704 is 100 Hz, and the eNodeB 706 carrier frequency error is 200 Hz. The UE 708 is assumed to be tracking the average 150 Hz carrier frequency error, which is equal to - 50 Hz, and the frequency shift for eNóB 706 is 200 Hz minus 150 Hz, which is equal to 50 Hz.
    [0052] The timing offset per cell can be used to improve the channel estimate of each cell, since the timing per cell allows the UE to accurately locate the cell's channel outlets. For example, the UE 708 can determine its channel tap truncation windows based on the timings per cell. That is, UE 708 can determine a first channel bypass truncation window based on eNodeB 702 timing, a second channel bypass truncation window based on eNodeB 704 timing, and a third bypass truncation window based on the timing of eNodeB 706. For the serving cell, the improved channel estimate is directly translated into an improved UE performance. For an interference cell, the improved channel estimate can translate into better cell interference cancellation and, therefore, improved UE performance. For example, if eNodeB 702 is a server cell for UE 708, the first channel bypass truncation window will provide the improved server cell channel estimate. In addition, signals processed through the second and third channel bypass truncation windows can lead to improved channel estimation between eNósB 704 and 706, which can result in better interference cancellation.
    [0053] The frequency shift per cell can also be used to improve the channel estimate of each cell. For example, UE 708 can apply a rotation (i.e., phase change) to the RS and channel estimates of a cell to help remove the residual frequency error in the cell's RS. The amount of rotation can be determined based on the estimated frequency shift per cell to cell. For the serving cell, the improved channel estimate is translated directly into the improved UE performance. For an interference cell, the improved channel estimation translates into better cell interference cancellation and therefore improved UE performance.
    [0054] Figure 8 illustrates illustrative operations 800 for estimating timing displacement per cell. Operations 800 can be performed, for example, by a UE, such as UE 708 illustrated in figure 7 to estimate the time shift per cell for eNósB 702706.
    [0055] Operations 800 begin, in 802, by estimating the timing for tracking (for example, the timing of a particular cell or a combination of a plurality of cells. As noted above, this timing can be derived from the received signals ( CRS, etc.) of a stronger cell or by combining signals from multiple cells with appropriate averaging and weighting). In 804, the timing offsets per cell (with respect to the timing mentioned above that the UE is tracking) for all cells are determined. In 806, signals received from the plurality of cells are processed using one or more sets of channel bypass truncation windows determined based on timing shifts.
    [0056] As described above, the timing offset for a cell generally refers to a difference between the timing for the cell and the timing that a UE is tracking. According to certain aspects, a channel bypass truncation window can be determined for each cell based on the timing offset for that cell. According to certain aspects, a channel can be estimated from each cell through the channel derivation truncation window for that cell. These estimated channels can be used in the processing signals received from each cell.
    [0057] Figure 9 illustrates illustrative operations 900 for estimating frequency shifts per cell. Operations 900 can also be performed by a UE, such as UE 708 illustrated in figure 7 to estimate frequency shifts per cell for eNósB 702706.
    [0058] Operations 900 begin, in 902, by estimating the frequency of a particular cell or combination of a plurality of cells. As noted above, this frequency can be derived from the received signals (CRS, etc.) from a stronger cell or by combining multiple cell signals with proper averaging and weighting. In 904, the frequency shifts per cell (with respect to the carrier frequency mentioned above that the UE is tracking) for all cells are determined. In 906, signals received from the plurality of cells are processed using frequency shifts per cell.
    [0059] In one configuration, a particular carrier frequency that is tracked can be derived based on an average of the frequency error estimates per cell. As described above, the frequency shift for a cell generally refers to a difference between the carrier frequency (or frequency error) for the cell and the particular cell being tracked.
    [0060] According to certain aspects, 906 processing may include applying a phase shift to cell-specific reference signals from each of the cells to remove a residual frequency error in the cell-specific reference signals. The phase shift in the cell-specific reference signals of a cell can be determined as a function of the frequency shift determined for that cell.
    [0061] According to certain aspects, the averages of time and / or frequency displacement can be weighted, for example, according to the signal intensities received from the participating cells in the realization of the average.
    [0062] Figure 10 is a conceptual block diagram illustrating the functionality of an illustrative apparatus 1000. Apparatus 1000 may include a module 1002 that estimates the timing of a particular cell or combination of a plurality of cells, a module 1004 that determines the timing offsets per cell, with respect to the timing that the UE is tracking, for all cells in the plurality of cells, and a module 1006 that processes the signals received from the plurality of cells by configuring one or more truncation windows of channel bypass based on time offsets per cell.
    [0063] In addition to, or as an alternative to modules 1002-1006, device 1000 may also include a module 1008 that determines the frequency shifts per cell, with respect to the carrier frequency that the UE is tracking, for all of the plurality of cells, and a module 1010 that processes signals received from the plurality of cells based on frequency shifts per cell.
    [0064] Depending on a particular configuration, a device can use the time offsets per cell, the frequency offsets per cell, or both. Thus, in a configuration, the device 1000 can include modules 1002-1006. In another configuration, device 1000 includes modules 1008-1012. In another configuration, device 1000 may include modules 10021012.
    [0065] In one configuration, the apparatus 1000 for wireless communication may include means for carrying out the functionality illustrated in figure 10. The means may comprise any suitable component or combination of components. According to certain aspects, the means can be implemented with the processing system 114 of figure 1, configured to perform the functions described here.
    [0066] In multi-point cooperative systems (CoMP), signals destined for a UE are transmitted from multiple cells (called "CoMP transmission points") and combined in the air. In some cases, CoMP transmission points may be transparent to the UE, meaning that the UE may not know which cells correspond to its CoMP transmission points. The transparency of CoMP transmission points can be made possible by the use of dedicated UE-specific RS (UE-RS).
    [0067] Figure 11 illustrates illustrative operations 1100 for using time shifts in a CoMP system. Operations begin, in 1102, by determining the timing offsets per cell, with respect to the timing of a particular cell, for the remaining cells of a plurality of cells including CoMP cells. For example, these timing offsets per cell can be determined as described above, with reference to figure 8.
    [0068] In order to accurately estimate the CoMP channel, the UE can identify the cell timings at its CoMP transmission points. If the CoMP transmission points are known to the UE, as determined in 1104, the UE can calculate an average timing offset using the timing shifts of those known CoMP cells, in 1106. If the CoMP transmission points are unknown to the UE, the UE can exclude the timing shifts of known non-CoMP cells when calculating an average timing shift, in 1108. Known non-CoMP cells may include certain cells that cannot participate in a UE CoMP. Examples of executable cells may include cells where the UE has barred access (for example, CSG cells).
    [0069] The UE can determine its channel bypass truncation window based on the determined average timing offset (calculated for known CoMP transmission points and / or by excluding known non-CoMP transmission points).
    [0070] As an example, with reference to figure 7, it can be assumed that eNóB 702 and eNóB 704 are CoMP transmission points and eNóB 706 is not a CoMP transmission point. It is also assumed that UE 708 is aware that eNóB 702 and eNóB 704 are CoMP transmission points and that eNóB 706 is not a CoMP transmission point. UE 708 can estimate a timing offset for each of cells 702, 704, 706. Additionally, UE 708 can determine a timing offset for CoMP transmission points 702, 704 by combining signals from a subset of cells. The subset of cells includes cells 702, 704 and UE 708 knows that these cells are CoMP transmission points. If UE 708 does not know which cells are CoMP transmission points, the subset of cells can include all cells excluding cells known to be not CoMP transmission points. UE 708 can determine a channel bypass truncation window for the CoMP channel estimate based on the determined timing offset. The CoMP channel estimate is based on the UE-specific reference signals from the CoMP 702, 704 transmission points.
    [0071] In order to accurately estimate the CoMP channel, the UE can additionally (or alternatively) identify the frequency shift of the cells at their CoMP transmission points.
    [0072] Figure 12 illustrates illustrative operations 1200 to use frequency shifts in a CoMP system. Operations begin, in 1202, by determining the frequency shifts per cell, with respect to the frequency of a particular cell, for the remaining cells of a plurality of cells including CoMP cells. For example, these frequency shifts per cell can be determined as described above, with reference to figure 9.
    [0073] In order to accurately estimate the CoMP channel, the UE can identify the frequency of the cells at their CoMP transmission points. If the CoMP transmission points are known to the UE, as determined in 1204, the UE can calculate an average frequency shift using the frequency shifts of those known CoMP cells, in 1206. If the CoMP transmission points are unknown to the UE, the UE can exclude frequency shifts of known non-CoMP cells when calculating an average frequency shift at 1208.
    [0074] The UE can use the medium frequency offset to minimize the impact of frequency errors between CoMP transmission points. For example, the UE may attempt to minimize the impact of frequency errors by applying rotation to the received UE-RS signals. That is, the UE can apply a phase shift to the UE-specific reference signals from the CoMP transmission points to minimize a residual frequency error in the UE-specific reference signals. The phase shift applied to EU-specific reference signals may be a function of the determined average carrier frequency shift.
    [0075] The various operations of the methods described above can be performed by any suitable means capable of carrying out the corresponding functions. The means may include various hardware and / or software components and / or modules, including, but not limited to, a circuit, an application specific integrated circuit (ASIC), or a processor.
    [0076] The various illustrative logic blocks, modules and circuits described in relation to this description can be implemented or carried out with a general purpose processor, a digital signal processor (DSP), an ASIC, a field programmable set signal ( FPGA), or other programmable logic device (PLD), discrete port or transistor logic, discrete hardware components or any combination of them designed to perform the functions described here. A general purpose processor can be a microprocessor, but in the alternative, the processor can be any commercially available processor, controller, microcontroller or state machine. A processor can also be implemented as a combination of computing devices, for example, a combination of a DSP and a microprocessor, a plurality of microprocessors, one or more microprocessors in conjunction with a DSP core, or any other similar configuration.
    [0077] The steps of a method or algorithm described in relation to this description can be embodied directly in hardware, in a software module executed by a processor, or in a combination of the two. A software module can reside in any form of storage medium that is known in the art. Some examples of storage media that can be used include random access memory (RAM), read-only memory (ROM), flash memory, EPROM memory, EEPROM memory, registers, hard disk, removable disk, CD-ROM, and so on. onwards. A software module can comprise a single instruction, or many instructions, and can be distributed across several different code segments, between different programs, and across multiple storage media. A storage medium can be coupled to a processor so that the processor can read information from, and write information to, the storage medium. Alternatively, the storage medium can be integral to the processor.
    [0078] The methods described here comprise one or more steps or actions to achieve the described method. The method steps and / or actions can be interchanged with each other without departing from the scope of the claims. In other words, unless a specific order of steps or actions is specified, the running and / or use of specific steps and / or actions can be modified without departing from the scope of the claims.
    [0079] The functions described can be implemented in hardware, software, firmware or any combination thereof. If implemented in software, functions can be stored as one or more instructions in a computer-readable medium. A storage medium can be any available medium that can be accessed by a computer. By way of example, and not limitation, such a computer-readable medium may comprise RAM, ROM, EEPROM, CD-ROM or other optical disk storage, magnetic disk storage or other magnetic storage devices, or any other medium that may be used to input or store the desired program code in the form of instructions or data structures and which can be accessed by a computer. Floppy disk and disk, as used here, include compact disk (CD), laser disk, optical disk, digital versatile disk (DVD), floppy disk, and Blu-ray disk, where floppy disks normally reproduce data magnetically, while disks reproduce data optically with lasers.
    [0080] For example, such a device can be coupled to a server to facilitate the transfer of means for carrying out the methods described here. Alternatively, various methods described here can be provided via storage media (for example, RAM, ROM, a physical storage medium such as a compact disc (CD) or floppy disk, etc.), so that a user terminal and / or base station can obtain the various methods by coupling or providing storage media for the device. In addition, any other technique suitable for providing the methods and techniques described here for a device can be used.
    [0081] It should be understood that the claims are not limited to the precise configuration and components illustrated above. Various modifications, changes and variations can be made in the arrangement, operation and details of the methods and apparatus described above without departing from the scope of the claims.
    [0082] While the above is directed to aspects of the present description, other additional aspects of the description can be glimpsed without departing from the basic scope of the description, and the scope of the description is determined by the following claims.
    权利要求:
    Claims (10)
    [0001]
    1. Wireless communication method by a user device, UE (306, 708), comprising: estimating (800) system timing, in which the estimated system timing is derived from the timing of one or more cells (302); determining (804) timing shifts, with respect to the estimated system timing, for a plurality of cells (302); and processing (806) signals received from the plurality of cells (302); characterized by the fact that it additionally comprises: determining a weighted average timing offset based on the determined timing offsets, where the weighting is based on received signal strengths; and in which processing (806) signals received from the plurality of cells (302) is performed with a set of channel bypass truncation windows based on the weighted average time offsets.
    [0002]
    2. Method, according to claim 1, characterized by the fact that estimating (800) the timing is performed by using a received signal comprising at least one of a cell-specific reference signal, a primary synchronization signal, a secondary sync signal or cyclic prefix.
    [0003]
    Method according to claim 2, characterized in that the received signal comprises a signal received from a particular cell.
    [0004]
    Method according to claim 3, characterized in that the particular cell (302) comprises a cell with a stronger received signal strength for one or more reference signals.
    [0005]
    5. Method according to claim 2, characterized in that the received signal comprises a combination of multiple cell signals.
    [0006]
    6. Method according to claim 1, characterized by the fact that all or a subset of the plurality of cells are able to participate in cooperative multi-point transmissions, CoMP, to the UE (306, 708).
    [0007]
    7. Method according to claim 1, characterized by the fact that: determining the average timing offset comprises using (1106) timing offsets for cells (302) known to be capable of participating in CoMP transmissions.
    [0008]
    8. Method according to claim 1, characterized by the fact that: determining the average timing offset comprises excluding (1108) timing shifts for one or more cells (302) known to be unable to participate in CoMP transmissions.
    [0009]
    9. Apparatus for wireless communication, comprising: mechanisms for estimating (1002) system timing, in which the estimated system timing is derived from the timing of one or more cells (302); mechanisms for determining (1004) timing shifts, with respect to the estimated system timing, for a plurality of cells (302); mechanisms for processing (1006) signals received from the plurality of cells (302); characterized by the fact that it comprises: mechanisms to determine a weighted average timing offset based on the determined timing offsets, where the weighting is based on received signal strengths; and wherein the mechanisms for processing (1006) the signals process the signals received from the plurality of cells (302) with a set of channel bypass truncation windows based on the weighted average time offsets.
    [0010]
    10. Memory characterized by the fact that it comprises instructions stored in it that, when executed by a computer, cause the computer to perform a method as defined in any one of claims 1 to 8.
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    同族专利:
    公开号 | 公开日
    KR101549052B1|2015-09-11|
    JP5813730B2|2015-11-17|
    TW201134269A|2011-10-01|
    KR20140010172A|2014-01-23|
    EP2574121A3|2014-02-26|
    KR20140138343A|2014-12-03|
    WO2011063291A3|2011-08-18|
    US9100843B2|2015-08-04|
    CN102612848A|2012-07-25|
    EP2502453A2|2012-09-26|
    JP2014078951A|2014-05-01|
    JP2016006965A|2016-01-14|
    JP2017143520A|2017-08-17|
    JP6129908B2|2017-05-17|
    JP6456988B2|2019-01-23|
    US10111111B2|2018-10-23|
    CN102612848B|2015-07-01|
    CN104640196B|2018-04-10|
    JP5675836B2|2015-02-25|
    KR20120095446A|2012-08-28|
    EP2502453B1|2014-02-26|
    JP2013511919A|2013-04-04|
    TWI492649B|2015-07-11|
    US20110286376A1|2011-11-24|
    KR101486401B1|2015-01-26|
    US20130231123A1|2013-09-05|
    EP2574121B1|2016-04-27|
    EP2574121A2|2013-03-27|
    WO2011063291A2|2011-05-26|
    CN104640196A|2015-05-20|
    BR112012011661A2|2016-07-05|
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    法律状态:
    2019-01-08| B06F| Objections, documents and/or translations needed after an examination request according [chapter 6.6 patent gazette]|
    2020-01-21| B06U| Preliminary requirement: requests with searches performed by other patent offices: procedure suspended [chapter 6.21 patent gazette]|
    2020-12-08| B09A| Decision: intention to grant [chapter 9.1 patent gazette]|
    2021-02-23| B16A| Patent or certificate of addition of invention granted [chapter 16.1 patent gazette]|Free format text: PRAZO DE VALIDADE: 10 (DEZ) ANOS CONTADOS A PARTIR DE 23/02/2021, OBSERVADAS AS CONDICOES LEGAIS. |
    优先权:
    申请号 | 申请日 | 专利标题
    US26291109P| true| 2009-11-19|2009-11-19|
    US61/262,911|2009-11-19|
    US12/949,020|2010-11-18|
    US12/949,020|US10111111B2|2009-11-19|2010-11-18|Per-cell timing and/or frequency acquisition and their use on channel estimation in wireless networks|
    PCT/US2010/057513|WO2011063291A2|2009-11-19|2010-11-19|Per-cell timing and/or frequency acquisition and their use on channel estimation in wireless networks|
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