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    • 专利摘要:
    METHOD FOR ESTABLISHING A FIRST AND A SECOND DETACHED ASSOCIATION The invention relates to a method for establishing a first and a second association between a main node and, respectively, a first and second wireless nodes, the first association associating a first connection point. virtual access point VAP1 of the head node and the first node, the first virtual access point transmitting, to the first node, first advertisement frames comprising a first information item BSSID1 representing said first association BSS1, the first virtual access point VAP1 being identified by an SSID service set identifier. According to the invention, when the main node receives a request from the node to establish the second BSS2 association, the method comprises, at the controller level, a step of creating a second virtual access point in order to isolate the transmissions across associations.
    公开号:BR112013028047B1
    申请号:R112013028047-6
    申请日:2012-05-07
    公开日:2022-02-01
    发明作者:Patrick Fontaine；Kandaraj Piamrat；Renaud Dore
    申请人:Interdigital Ce Patent Holdings；
    IPC主号:
    专利说明:

    1. Domain of the Invention.
    The invention relates to the field of telecommunications, and more specifically to the management of a wired or wireless local area network comprising at least two wireless nodes. 2. Prior Art
    According to the prior art, various WLAN (Wireless Local Area Network) or LAN (Local Area Network) network architectures are known. Some of them use a single access point to cover a space, such as a house or a building's floor, for example, by using an intensified transmission energy associated with various sophisticated technologies, such as MIMO (Multiple Inputs Multiple Outputs) or OFDM (Orthogonal Frequency Division Multiplexing). Thus, a Wi-Fi® network access point (based on the 802.11n standard) achieves a true bit rate of 100 Mbits/s within a 90 meter radius using MIMO and OFDM technologies and an access point for a HyperLAN2 achieves a bit rate of 50 Mbits/s within a radius of 45 meters. Such architectures based on a single access point have the disadvantage of producing a high level of interference with the adjacent area and the risk of covering the entire space to be covered, particularly in some regions separated from the access point by physical obstacles, such as walls or panels that cause strong attenuations of the transmitted signal. Furthermore, the use of an enhanced transmission energy raises health concerns related to the risks associated with prolonged exposure to electromagnetic radiation.
    Heusse et al. in “Performance anomaly of 802.11b” in Proc. of IEEE INFOCOM 2003 noted that when some nodes connected to the same access point have a lower bit rate than others, the performance of all nodes is generally degraded even if they are located close to the access point. Such situations are generally found in local networks within which the signal transmitted by a node placed very far from the access point is subject to interference.
    To overcome this problem, the node modifies its modulation type, which degrades the bit rate of its connection. As a general rule, nodes conforming to the 802.11b standard degrade their bit rate progressively from 11 Mb/s to 5.5 or 1Mb/s when transmission failures are detected. In such a situation, this bitrate reduction impacts the bitrate of all other transmit nodes due to the CSMA/CA channel access method that ensures long-term equality of channel access probability for all channels. we. When a node consumes the channel for a long period because its bitrate is slow, it penalizes other nodes that have a higher bitrate.
    There are solutions to solve this problem when data is transmitted only by the access point (that is, only on the downlink) or when a scheduling mechanism performs temporal multiplexing, coordinates the various nodes and removes contention zones: this is the case, for example, of the 802.16 standard or the PCF mode of the 802.11 standard.
    The invention is situated in the context of a wired or wireless CSMA network, where at least 2 wireless nodes wish to transmit data to the same access point (i.e. an uplink) and must share the same channel to do so. In fact, if a scheduling engine is able to coordinate the downlink data transmissions using different access points, the scheduling engine is not able to coordinate the uplink data transmissions. In the case of an uplink data transmission, a wireless node can monopolize the resource, thus blocking all other communications. Among the networks that implement a random method to access the channel, it is possible to mention, for wired networks: GNeT using CSMA/CA, Apples LocalTalk using CSMA/CA, Ethernet (based on the IEEE 802.3 standard) using CSMA/CD (Carrier Sense Access with Collision Detection) or ITU-T H.hn using CSMA/CA, and for wireless networks: the Wi-Fi® network (based on the IEEE 802.11-2007 standard) using CSMA/CA, wireless personal network WPAN (Wireless Personal Area Network) wire, based on the IEEE 802.15 standard using CSMA/CA or WaveLAN using CSMA/CA. 3. Summary of the Invention
    The object of the invention is to overcome the disadvantages of the prior art. More specifically, the object of the invention is to isolate traffic flows in such a way that a degradation of the link between a main node (or access point) and a first node does not degrade the links between that head node and the other nodes on the network, particularly in the scope of adaptive streaming communications based on the http standard. To do so, the main node will be decoupled from the same number of virtual access points as the links, a controller sharing access to the media according to the bandwidth (or bit rate) requirements expressed by each of the clients, the modulation used or, again, the type of stream to be transmitted demanding a guaranteed quality of service or satisfying a best effort mode. Sharing is performed at the access point level by evaluating the periods during which each client is configured to communicate while the other clients remain silent. The duration of these periods is determined using knowledge of the total available bitrate, the frame duration, and the available bitrate at each client level, and is notably a function of the modulation rate employed and the bitrate required per stream. of data.
    The invention relates to a method for establishing a first and a second association between a master node 11 and, respectively, a first and second wireless nodes 111, 112, the first association associating a first virtual access point VAP1 of the master node. 11 and from the first node 111, the first virtual access point VAP1 sending to the first node 111 first beacon frames 411 (beacon frames 411) comprising a first information item BSSID1 representing said first association BSS1, the first access point virtual VAP1 being identified by an SSID service set identifier.
    According to the invention, when the main node 11 receives, from the node 112, a request for the establishment of the second association BSS2, the method comprises, at the level of a controller, steps of:- collecting parameters of the first and second association - creating a second virtual access point VAP2 of the main node 11 sending to the second node 112 second beacon frames 421 comprising a second information item BSSID2 representing said second association, said second virtual access point VAP2 being identified by the service set identifier SSID, - estimation, from said parameters, of a first and a second time slot 42, 41 during which, respectively, the first node 111 and the first virtual access point VAP1 on the one hand, the second node 112 and the second virtual access point VAP2 are prohibited from sending, - establishment of the second association between the second node 112 and the second virtual access point VAP2, - trans issuing, to the first and second nodes 111, 112, at least one item of silence information representing a prohibition to send 410, 420 during the first or second time slot 42, 41.
    Advantageously, a first and second transmission bit rate dr1, dr2 practiced by the first and second nodes linked to the physical modulation employed, respectively, by the first and second nodes 111, 112 in the first and second association, and a first and second rate of transmission DR1, DR2 data transmission bits required respectively by the first and second nodes 111, 112 according to the nature of data transmitted in the first and second association are collected parameters.
    Advantageously, the controller defines a frame duration and the first and second time slots 42, 41 have a duration proportional to the duration of said frame and proportional to the first data transmission bit rate dr1 practiced by the first node 111 and the first DR1 data transmission bit rate required by the first node 111 and relative to the second DR2 data transmission bit rate required by the second node 112.
    Advantageously, a bit rate of total data transmission bit rate dr practiced by the first and second nodes linked to the physical modulation employed, respectively, by the first and second nodes 111, 112 in the first and second association, and a first and second data transmission bit rate DR1, DR2 displayed respectively by the first and second nodes 111, 112 according to the nature of data transmitted in the first and second association are collected parameters. Advantageously, the controller sets a frame duration and the second and first time slots 42, 43 have a duration proportional to the duration of said frame and proportional to the first data transmission bit rate DR1 required by the first node 111 related to the data rate. practiced total data transmission bits related to the second DR2 data transmission bit rate required by the second node 112 related to the practiced total data transmission bit rate.
    Advantageously, the main node 11 is an access point, and the first and second nodes 111, 112 are associated with the access point.
    Advantageously, the silence information item is comprised of at least one silence element 56 of a beacon frame 411, 421.
    One of the advantages of the invention is that it allows data exchanges from the various nodes to be decoupled. In particular, the quality of the link between a client and an access point is not a function of the quality of the links between that access point and other clients.
    Furthermore, the invention allows an access point on a wireless CSMA network to allocate bandwidth to its clients.
    The invention can be implemented by updating the firmware or controller of the access points, in particular it can be implemented in the existing access points.
    Finally, the invention is directly compatible with wireless stations that support the 802.11h standard (mandatory in the 5GHz band). 4. List of figures
    The invention will be better understood, and other specific aspects and advantages will emerge when reading the following description, which makes reference to the accompanying drawings, in which:- Figure 1 shows a wireless system implementing several virtual access points in an access point associated with several stations, according to a particular embodiment of the invention, figures 2 and 3 illustrate in diagrammatic form, respectively, an access point and a station of the system of figure 1, according to a particular embodiment of the invention, - figure 4 illustrates, in diagram form, the structure of a communication board of the system of figure 1, according to a particular embodiment of the invention, - figure 5 illustrates, in diagram form, the content of a beacon transmitted by at least one node of the system of figure 1, according to a particular embodiment of the invention, figure 6 shows a method for establishing a first and a second decoupled association between a main node and a first and second nodes, respectively, according to a particular embodiment of the invention, figure 7 is a table showing different data bit rates of a node of a wireless system according to the mode of physical modulation. 5. Detailed description of embodiments of the invention.
    The invention is now described, in a non-restrictive manner, in accordance with a particular embodiment implementing a wireless local area network of the Wi-Fi type (referring to IEEE 802.11a, IEEE 802.11b, IEEE 802.11d, IEEE 802.11e, IEEE 802.11g, IEEE 802.11h, IEEE 802.11i, IEEE 802.11j (issued by the IEEE under the reference IEEE 802.11TM-2007 with the title “IEEE Standard for Information technology - telecommunications and information exchange between systems - Local and metropolitan area networks - Specific requirements / Part 11: Wireless LAN Medium Access Control (MAC) and Physical Layer (PHY) Specifications”) or IEEE 802.11n). Of course, the invention is not limited to an implementation on a wireless network of the Wi-Fi® type, the principles of the invention being applied by those skilled in the art to any type of wired or wireless local area network using a channel access method. partially random type, e.g. ALOHA, CSMA, CSMA/CA or CSMA/CD type, e.g. a wired local area network such as GNeT, Apple's LocalTalk, Ethernet (based on the IEEE 802.3 standard), ITU-T G .hn or a wireless local area network such as WPAN (based on the IEEE 802.15 standard), WaveLAN or ALOHAnet
    In order to reduce collisions, the airtime in a network is divided into n partitions, with n corresponding to the number of nodes in the network. Equality between the different nodes is guaranteed since each node will have a dedicated time corresponding to the time needed to transmit its traffic using the highest modulation. An unsaturated network is hypothesized in which the overall traffic (when it is transmitted at the highest bit rate) does not exceed the maximum capacity of the network. Each time partition corresponds to a virtual local area network managed by a virtual access point, its implementation is described here later in the description.
    The implementation of channel allocation and its protection is carried out through a Silence Element (indicated as QE) available in the standard. This element, transmitted via the beacon frame, allows a virtual access point to prohibit all transmissions to its stations during a time slot allotted to other virtual access points. The beacon frames of each BSS can comprise multiple silence elements. Therefore, as shown in Figure 4, two silence elements 410, 420 are used to create two subframes in a beacon interval (time between transmission of two beacons). If transmissions of beacon frames are shunted (between the two BSS), the silence intervals are always synchronized. Also, if the transmission of the beacon frames were also delayed by a busy channel, the silence intervals still remain synchronized as the silence intervals are defined in relation to the TBTT (Target Beacon Transmission Time).
    Figure 1 shows a wireless local area network type wireless communication system 1 according to a particular embodiment of the invention, implementing several nodes. In network infrastructure mode, node 11 acts as a mobile or fixed access point and the other nodes 111, 112 act as fixed or mobile stations. Station 111 is associated with access point 11 for data communication (i.e. transmission and/or reception) and forms, with access point 11, a first BSS (Basic Services Set) 1. This association is produced by a first virtual access point VAP1 comprised in the access point 11. The association between the station 111 and the virtual access point VAP1 or the station and the defined virtual access point are used in the same way hereafter in the description and are called of BSS1. A Basic Service Set Identifier information element BSSID1 representing that first association BSS1 is transmitted in beacon frames transmitted by the first virtual access point VAP1. Station 112 is associated with access point 11 for data communication and forms, with access point 11, a second set BSS 2. This association is produced by a second virtual access point VAP2 also comprised in access point 11 A BSSSID2 information element representing that second association is transmitted in beacon frames transmitted by the second virtual access point VAP2.
    The two sets BSS 1 and BSS 2 are natively connected in access point 11 to form an ESS (Extended Service Set). An SSID information element (Service Set Identifier) representing the set comprising BSS 1 and BSS 2 representing the name of wireless system 1 is also transmitted in beacon frames transmitted via virtual access points VAP1, VAP2.
    Station 111, respectively, 112, is capable of exchanging (sending or receiving) data (or data packets) with the virtual access point VAP1, respectively, VAP2, with which it forms BSS 1, respectively, BSS 2. Advantageously, a BSS uses a particular physical channel to exchange data, a physical channel being characterized by a group of parameters comprising a list of sub-carriers, a time slot, an interference level and, in the case of a CDMA (Multiple Access by Code Division), access the same spreading code.
    The 5 GHz band corresponds, for example, to frequency bands for which all frequencies are between 5.15 GHz and 5.35 GHz or between 5.47 GHz and 5.875 GHz. A physical channel of 5 GHz corresponds to a channel of width 10, 20 or 40 MHz, for example, for which all frequencies are situated in one of the frequency ranges mentioned above. The 2.4 GHz band corresponds, for example, to frequency bands for which all frequencies are between 2.4 GHz and 2.5 GHz. A physical channel of 2.4 GHz corresponds to a channel of width 10, 20 or 22 MHz, for example, for which all frequencies are situated in one of the frequency ranges mentioned above.
    Advantageously, particularly in the case of a CSMA access that does not provide a mechanism for coordinating the data exchanges, but instead a random access to the physical channel, the sharing of the physical channel for exchanging downlink or uplink data is performed via a time division of the channel according to the different bit rates required for each link. The implementation of this temporal division comprises the definition of silence elements 410, 420 available in the standard. A silence element, belonging to the beacon frame, allows an access point (VAP) to prohibit any transmission of data from the virtual access point to the station with which it is associated and from the station to that virtual access point during the time reserved for other virtual access points. The definition of the silence time intervals of the virtual access points and the corresponding beacon frame sent by the virtual access point will be listed with reference to Figures 4 and 5.
    Advantageously, the access point 11 of the system 1 is a fixed device. However, the invention is compatible with a mobile hotspot 11.
    Stations 111 to 112 can be fixed or mobile stations, for example a mobile phone, a mobile terminal, a laptop, a PC (Personal Computer) or a PDA (Personal Digital Assistant).
    Figure 2 diagrammatically illustrates a hardware embodiment of an access point 2 corresponding, for example, to node 11 of figure 1.
    The access point 2 comprises the following elements, connected to each other by an address and data bus 24 that also carry a clock signal: - a microprocessor 21 (or CPU), - a non-volatile memory of the ROM type (Memory Read Only) 22, - a Random Access Memory or RAM 23, - a radio interface 26, - an interface 27 adapted for data transmission (e.g. service transmission or multipoint transmission to point or point-to-point point) and execution, namely the functions of an OFDM encoder and/or modulators, - an interface 28 adapted to calculate a synchronization offset between the virtual access points, i.e. between the BSS beacon frame time references 1 and BSS 2, and synchronizing the interface 27, and/or- an MMI (Human-Machine Interface) interface 29 or for a specific application suitable for displaying information to a user and/or inputting data or parameters (e.g. , the definition of the parameters of the sub -carriers and the data to be transmitted).
    Note that the word “record” used in the description of memories 22 and 23 designates, in each of the aforementioned memories, both a low-capacity memory region (some binary data), as well as a large-capacity memory region ( allowing an entire program to be stored or all or part of the data representing the received data to be transmitted). The ROM memory 22 comprises, namely: - a program "prog" 220, and - parameters 221 of the physical layers.
    The algorithms implementing the steps of the method specific to the invention and described below are stored in the ROM 22 associated with the access point 2 implementing these steps. When initialized, the microprocessor 21 loads and executes the instructions of these algorithms.
    The random access memory 23 particularly comprises: - in a register 230, the operating programs of the microprocessor 21, responsible for activating in the access point 2, - transmission parameters 231 (for example, parameters for modulation, for encoding, for recurrence of frames, a table with the time allotted to each station, and possibly other parameters (stream type, station identifier, MAC address, required bit rate and priority)),- Receive parameters 232 (e.g. , parameters for modulation, encoding, and frame recurrence), - input data 233, - encoded data 234 for transmitting the data, - a silence information item 235, and - physical channel parameters 236 (e.g., the allocation of specified time slots, a specified code and/or specified subcarrier slots in the transmission of data by the access point 2).
    The radio interface 26 is adapted to receive signals transmitted, if necessary, by nodes 111 or 112 of system 1.
    The controller performing the allocation of the virtual access points to the different stations and estimating the temporal sharing of the media is advantageously implemented by means of an application on the processor 21. The virtual access points are also advantageously implemented by means of an application on the processor 21 .
    Figure 3 diagrammatically illustrates a hardware embodiment of a station 3 belonging to the system 1, corresponding, for example, to the node 111 or 112 and adapted to receive and decode the signals transmitted through the access point 2, to transmit signals to the point of access 2.
    Station 3 comprises the following elements, connected to each other by an address and data bus 34 that also carry a clock signal: - a microprocessor 31 (or CPU), - a non-volatile memory of the ROM type (Memory Only for Readout) 32,- a Random Access Memory or RAM 33,- a radio interface 36, and- an interface 37 adapted for transmitting data, and- an MMI interface 38 adapted to display information to a user and/or inform data or parameters (eg the definition of the parameters of the subcarriers and the transmitted data).
    Note that the word "register" used in the description of memories 32 and 33 designates, in each of the aforementioned memories, a low-capacity memory region as well as a large-capacity memory region (allowing an entire program to be stored or that all or part of the data representing the received or decoded data sets). The ROM memory 32 comprises, namely: - a program "prog" 320, and - parameters 321 of the physical layers.
    The algorithms implementing the steps of the method specific to the invention and described below are stored in the ROM 32 associated with the station 3 implementing these steps. When initialized, the microprocessor 31 loads and executes the instructions of these algorithms.- random access memory 33 particularly comprises:- in a register 330, the operating programs of the microprocessor 31, responsible for the activation in the mobile terminal 3,- The parameters of reception 331 (e.g. parameters for modulation, encoding and recurrence of frames), - transmission parameters 332 (e.g. parameters for modulation, encoding and recurrence of frames), - input data 333 corresponding to received data and decoded by the receiver 36, - decoded data 334 formed to be transmitted on the interface to the application 39, - a silence information item 235, and -physical channel parameters 236 (e.g., allocation of a determined frequency band, from a code determined in the transmission of the data).
    Access point 2 and/or station 3 structures other than those described in relation to figures 2 and 3 are compatible with the invention. In particular, according to variants, the access points and/or mobile terminals compatible with the invention are implemented according to an embodiment purely in hardware, e.g. in the form of a dedicated component (e.g. in an ASIC (Application Specific Integrated Circuit) or FPGA (Field Programmable Gate Array) or VLSI (Very Large Scale Integration) or multiple electronic components integrated into one device or even in a form of a combination of hardware elements and elements of software.
    The radio interface 36 is suitable for receiving the signals transmitted by the node 11 of the system 1. Figure 4 illustrates, in diagrammatic form, the structure of a communication frame of the system 1, according to a particularly non-restrictive embodiment. advantage of the invention.
    Communication frame 4 is temporally divided into two subframes 41, 42, each subframe being allocated for communications settling between nodes of a given BSS. In the case of an infrastructure mode network, each subframe is allocated to the access point of each BSS. In system 1, subframe 41 is allocated to virtual access point VAP1 of BSS1 and subframe 42 is allocated to virtual access point VAP2 of BSS2. In each subframe, the BSS nodes (namely, the virtual access point and the station that is associated with it) use standard MAC mechanisms from the IEEE 802.11-2007 standard known to those skilled in the art: CSMA/CA mechanisms, for For example, using RTS/CTS frames to reserve the channel, the “backoff”, Quality of Service QoS EDCA frames, A-MPDU, ACK, acknowledgment block, etc. or any other mechanism described in the IEEE 802.11 standard -2007. Advantageously, the allocation of temporal frames from the communication frame to the BSS is performed by the controller. The controller is implemented, for example, in access point 11 of the ESS network of system 1 in addition to the virtual access points. Each point ESS network virtual access point comprising two BSS receives, from the controller, an item of information representing the allocation of subframes. According to a variant, one of the ESS network virtual access points operates as a controller and transmits the information representing the allocation o to other virtual access points. According to another variant, the allocation of subframes is recorded in the memory of each virtual access point of BSS1 and BSS2, for example, by a network manager user.
    During the first subframe 41, the virtual access point VAP1 of the BSS1 transmits a beacon frame 411 destined for the station 111 with which it is associated. The beacon frame advantageously comprises a silence information item representing the prohibition to transmit during subframe 42 allocated to BSS2. Upon receiving this prohibition to transmit during subframe 42, station 111 positions its network allocation vector (according to the IEE 802.11-2007 standard) NAV (Network Allocation Vector), thus prohibiting any data transmission during the ( s) time slot(s) corresponding to subframe 42. Virtual access point VAP1 also positions its NAV during the same time slot(s). Data communication between the virtual access point VAP1, thus, the access point 11 on one side and the station 111 on the other is performed during the interval(s) 412 and a silence element 410 is imposed. at the nodes of BSS1 during the timeslots allocated for subframe 42.
    During the second subframe 42, the virtual access point VAP2 of the BSS2 transmits a beacon frame 421 destined for the station 112 with which it is associated. The beacon frame 421 advantageously comprises a silence information item representing the prohibition to transmit during the subframe 41 allocated to BSS1. Upon receiving this prohibition for transmission during subframe 41, each of the virtual access point VAP2 and station 112 positions its NAV network allocation vector, thereby prohibiting them from any data transmission during the time slots corresponding to subframes 41 Data communication between the virtual access point VAP2, thus, the access point 11 on one side and the station 112 on the other is performed during the interval(s) 422 and a silence element 420 is enforced on BSS2 nodes during subframe 41 timeslots.
    Figure 5 illustrates, in diagrammatic form, the contents of a beacon frame in accordance with a particularly advantageous non-restrictive embodiment of the invention.
    Advantageously, beacon frame 5 complies with the 802.11-2007 standard. The MAC (Media Access Control Header) field 51 contains an information item representing the source and destination MAC addresses, the destination address being, for example, configured for all station addresses (corresponding to an address of type broadcast) of the considered BSS to force all stations of the considered BSS to receive and process each beacon frame. The MAC field header 51 also comprises, for example, the type and subtype of the frame (for example, type = management frame, subtype = beacon), or, again, the identifier of the BSS BSSID comprising the access point virtual transmitting the beacon frame (corresponding, for example, to the source address, i.e. the address at the virtual access point transmitting the beacon frame)
    The beacon frame body comprises all the fields placed between the MAC header and an FCS (Frame Verification Sequence) field. The timestamp field 52 comprises an information item representing a time used by a station to update its local clock. This information allows stations associated with the beacon frame transmitter access point to synchronize.
    The Beacon Interval field 53 comprises an information item representing the time that elapses between the transmission of two beacon frames. This information particularly allows stations that wish to go on hold to know when they must enter the listening state to receive the beacon frame. The beacon interval can be set, for example, in 100 TU (time units), that is, in 100*1024μs = 102.4 ms.
    The Capability Information field 54 comprises an information item representing the necessary prerequisites for a station to belong to the BSS comprising the access point that transmitted the beacon frame, such as, for example, the need to use a WEP key (Wired Equivalent Privacy) to join the network, or again, for example, an information item representing support for managing the DFS (Dynamic Frequency Selection) spectrum. To indicate spectral management support, the capability field 54 comprises an item of spectral management support information which translates, for example, as a Spectrum Management bit set to 1. A station receiving this information should set dot11SpectrumManagementRequired to true before to bind to the data point that transmitted the beacon frame. If a station does not support spectral management, then it cannot associate with the considered BSS.
    The SSID (Service Set Identifier) field comprises an information item representing the identification of the BSS comprising the sender access point of the beacon frame. Before being able to join a particular BSS, a station must have the same SSID as the virtual access point. The virtual access point then includes, by default, the SSID in the beacon frame it broadcasts.
    The silence field 56 comprises an information item representing a silence element, i.e. an information item that prohibits the virtual access point and the station belonging to the same BSS from transmitting data or data packets during one or more certain intervals. of one or more communication frames in a network. The silence field comprises several fields, including:- an "Element ID" field 561 comprising an information item representing the silence element identifier, a silence element being identified by ID 40 in the 802.11-2007 standard,- a “Length” field 562 comprising an information item representing the accumulated length (in bytes) of the fields following the length field and specific to the silence element, this length being 8 bytes according to the 802.11-2008 standard, as well as four fields specific to a silence element:- a “Counter” field 563 comprising an information item representing the number of the TBTT until the next beacon interval during which the silence interval begins. a value of 1 for the “Counter” field means that the next silence interval will start during the silence interval following the next TBT, i.e. following the first TBTT positioned after the transmission of the beacon frame describing the considered silence element ,- a "Period" field 564 comprising an information item representing the number of beacon intervals between two silence intervals corresponding to a silence element of the same BSS, - a "Duration" field 565 comprising an information item representing the duration of a silence interval represented, for example, by a number of TU time units, for example, 44 TU, or 44*1024μs = 45,056 ms. This duration corresponds to the duration during which the virtual access point and the station(s) of a given BSS cannot transmit data, and- a "Deviation" field 566 comprising an information item representing the time deviation, expressed in TU time units, existing between the beginning of the silence interval and the TBTT (Target Beacon Transmission Time) frame, the considered TBTT being specified in the “Counter” field 563.
    Advantageously, beacon frame 5 describes several silence elements (e.g. 2, 3, 5, 10 or 20), i.e. frame 5 comprises several silence fields, each silence field comprising an information item representing a silence element. Each silence field being associated with a single silence element, the beacon frame 5 comprises the same number of silence fields as the silence elements described in the beacon frame. When a communication frame of a network comprising, for example, 2 BSS, is, for example, divided into 10 subframes, 5 subframes being allocated to each BSS, the beacon frame transmitted by the first BSS comprises, for example, five fields of silence for the description of five silence elements, each corresponding to one of the five subframes allocated for the communication of the second BSS and the beacon frame transmitted by the second BSS comprises, for example, five silence fields for the description of five elements silence, each corresponding to one of the five subframes allocated for communication from the first BSS.
    The beacon frame 5 also comprises an FCS (Frame Check Sequence) field or a CRC (Cyclic Redundancy Check) field used for error correction and detection.
    Advantageously, each beacon frame transmitted by a virtual access point comprises the description of the silence element(s).
    Figure 6 illustrates a method for establishing a first and a second association between a master node, and, respectively, a first and second wireless node, implemented by the master node of the system 1, according to a particularly advantageous and non-restrictive embodiment. of the invention.
    During a boot step 60, the different parameters of the head node are updated. In particular, parameters corresponding to the signals to be transmitted or received and for the corresponding channels are initialized anyway (e.g. upon receipt of initialization messages transmitted by one of the network nodes, known as the master node, or by a peer network access or by an unrepresented system 1 controller or server, or by operator commands.
    Then, during a step 61, a plurality of virtual hotspots are created. According to a first variant, a first virtual access point VAP1 is created in the access point 11. The first station 111 is associated with this virtual access point and forms, with it, a BSS set 1 identified by its BSSID1. The second virtual access point VAP2 is created later when the access point 11 receives a request to establish a second association through a station 112. The sets BSS1 and BSS2 advantageously belong to the same network identified by their SSID. According to a second variant, the virtual access points VAP1 and VAP2 are created when the access point 11 receives a request to establish a second association. Access point 11 is then transformed into a first virtual access point VAP1. According to a third variant, a set of virtual access points are created simultaneously after the initialization phase, thus forming a provision of virtual access points available for the association establishment requests to arrive. According to an advantageous embodiment, as many virtual access points, and therefore BSSs, are created as there are stations to be isolated. In one variant, a single station is isolated from other stations. This variant is particularly well suited to an environment in which the aim is to ensure quality of service, for example through a TV broadcast. Therefore, a VAP1 will be created and associated with several stations that share access to the media during a certain time interval, forming a BSS1 set. In this BSS1 set, the problems of collision or degradation of the links can occur. A VAP2 will be created and associated with a single station, in the example it is the TV broadcast station. Advantageously, this station is isolated from the other stations and is not affected by collisions or degradation of the links in the BSS1, which has a gap. The quality of service for TV transmission is thus ensured as the link between VAP2 and the station is not degraded. In another variant, the access point is considered as a station and is isolated from other stations grouped together in the same BSS set. This variant has the advantage of allowing the downlink communication flows to be isolated from the access point from the stations' uplink communication flows. According to an advantageous embodiment, the access point (or the access point controller) decides in which VAP the station will be associated.
    Then, during step 62, an estimation of the time slots reserved for each of the BSS is performed using parameters from the first and second association. The parameters gathered for each association belong to the group comprising: - the bandwidth requirements (or DR1, DR2 bit rate) expressed (or required) by each of the stations, - the bandwidth (or dr1 bit rate, dr2) actual available (or practiced) on the channel linked to the physical modulation used,- the total bandwidth or total remaining bandwidth,- a predefined modulation,- the modulation actually used between a virtual access point and a station,- the nature of the stream to be transmitted, e.g. a TV stream requiring guaranteed quality of service, or e.g. a pure data stream satisfying a best-effort transmission mode, the stream priority.
    According to one variant, the group of parameters for estimating the reserved access time (or by extension, the silence time of the other stations) of each of the stations comprises only one or two parameters listed above. According to another variant, the group of parameters for estimating the access time is a combination of at least two parameters from the group defined above, for example, the ratio between the actual bitrate and the required bitrate of the first and second associations, namely DR1/dr1 and DR/dr2. The access time of BSS1 is, for example, proportional to DR1/dr1. The silence time of BSS2 is then proportional to (1-DR1/dr1) in the case of two BSS sets. The access time of BSS2 is, for example, proportional to DR2/dr2. The silence time of BSS2 is then proportional to (1-DR1/dr1) in the case of two BSS sets. According to another variant in which the clients are adapted to communicate with an identical modulation (dr1=dr2=dr), the access time is calculated according to a predefined modulation. For example, for the calculation, the modulation allowing the highest bit rate is selected as the default modulation. Different bit rates available according to modulation are thus illustrated in figure 7. Thus, the total bandwidth or total bandwidth remaining is calculated according to this predefined modulation. Furthermore, the required DR bit rate, i.e. the bandwidth to be allocated to the station, is calculated according to the required bit rate for a video data carrier, to which the transport data is added. (MAC / physical layers) of the video. The time to allocate to a client is then equal to the ratio of the bitrate needed by the client to the total bitrate to the total time ((DR1/dr)*T). The time interval of silence is then (1-DR1/dr)*T.
    The controller determines a media access temporal sharing frame duration (TDMA frame) according to the calculated times. The controller divides the frame into time slots which are allocated to the BSS. That is, the controller determines the time slots in which it will prohibit a station from transmitting, thus in the time slots allotted to the other stations. Access time is that reserved for a BSS (thus, its stations).
    According to one variant, the parameters are fixed (eg the same bit rate is required for the same station), the time slots can then be fixed at the beginning.
    Advantageously, the access point or controller maintains a table with the time allocated to each station, and possibly other parameters (stream type, station identifier, MAC address, required bit rate, priority, etc.). When a first station 111 associates with a first virtual access point VAP1, the controller estimates the media access time it will reserve at the first station 111 for its transmissions including transmission to the station and receptions from the station ( downlink and uplink data). Then, when a second station 112 wishes to associate with the access point, the controller again calculates the allocated access time for each station 111, 112, subtracting the silence time for the other stations, and updates the table (silence element intervals). , etc.). Thus, the method according to the invention is advantageously dynamic and adapts to requests to establish an association at the access point 11.
    Finally, during a step 63, the access point transmits an item of silence information destined for one or more associated nodes in the BSS. The AP (or, instead, the VAPs) construct beacon frame packets that contain transmission-prohibition information (silence elements). This silence information comprises an item of information representing a prohibition to transmit data or data packets during one or more time slots allocated to one or more stations of a second BSS set. The hotspot converts the time slots into silence elements that it will insert into beacon frames. A silence element allows a BSS to be prohibited from transmitting during a time interval. The time interval of the silence element is referenced in relation to the TBTT (Target Beacon Transmission Time) of the next beacon. Furthermore, the timeslots of 2 distinct BSSs are referenced against the target beacon transmission time (TBTT) of the first beacon 411. Therefore, the silence interval 410 of the beacon frame of BSS1 will be referenced against a TBTT of the beacon 411. The silence interval 420 of the beacon frame BSS2 will be referenced with respect to a TBTT of the beacon 421. It then serves to correct the reference of the silence element 420 of a synchronization deviation 430. According to a variant not illustrated in figure 4, a frame comprising a beacon frame comprises several silence elements for which the same station is prohibited from accessing the channel. Conversely, a frame may comprise several time slots 412, 422 during which the station may transmit data.
    According to a particularly advantageous embodiment, the nodes form a Wi-Fi® network, in accordance with the IEEE 802.11-2007 standard, in infrastructure mode. The silence information transmitted by the virtual access point VAP1 of the first set BSS1 is received by the station(s) 111 of the first set BSS1 and comprises an information item that prohibits the stations of the first set from transmitting during one or more intervals times allocated to the second set, and usually during one or several time slots allocated to the other sets of nodes in the network besides the first set. The second set of nodes BSS2 also comprises a virtual access point VAP2, different from the access point VAP1 of the first set, transmitting an item of silence information intended for the station(s) 112 of the second set, these stations being associated to the access point of the second set to establish all communications with the network. The silence information transmitted by the access point of the second set is received by the station(s) of the second set and comprises an information item that prohibits the stations of the second set from transmitting during one or more time slots allocated to the first set. set, and usually during one or more time slots allocated to the other sets of nodes in the network beyond the second set. According to an embodiment, the network comprises more than two sets of nodes, each set comprising a virtual access point transmitting an item of information representing a prohibition to transmit during one or more time slots allocated to other sets of the network, the information being transmitted through each access point to the stations that are associated with it.
    Advantageously, silence information transmitted via a first virtual access point of the first set is comprised in a silence element of a beacon frame, as defined in the IEEE 802.11-20077 standard. The silence element advantageously comprises the description of a set of specific parameters that allow the positioning of a silence interval by the nodes or stations of the first set receiving the silence information. This parameter set comprises the following parameters: the silence count, the silence period, the silence duration, and the silence offset. In one embodiment, the beacon frame comprises a plurality of silence elements, each silence element comprising describing a set of parameters specific to a silence interval. This variant allows multiple silence intervals to be positioned, particularly when a communication frame is divided into n subframes (n>2) and one silence interval must be positioned per subframe by a given set of stations.
    According to different variants, the elements of the steps described above are carried out in any order. Therefore, the association of a second virtual access point with a station can be performed before parameters are collected and/or before time intervals are estimated. Thus, the creation of a second virtual access point can be performed before or after estimating the time slots for the first virtual access point. Of course, the present invention is not limited to the above-described embodiments.
    In particular, the invention is not limited to a Wi-Fi® type network according to the IEEE 802.11-2007 standard, but extends to any wired or wireless network implementing a method for accessing a partially random type channel.
    Advantageously, a virtual access point is not associated with a single node for association, but with multiple nodes, thus isolating that set of nodes from another node.
    Advantageously, the invention is not limited to the embodiments described above, it comprises two BSS sets, each comprising a station and a virtual access point. The invention is compatible with a BSS number greater than two, any number of stations can be regrouped into these BSSs.
    Advantageously, each access point transmitting an item of silence information prohibits any transmission during the time interval(s) described in the silence information.
    Advantageously, when a client can communicate with the preset boosted modulation, it gets the expected bitrate (which is guaranteed), and when it cannot communicate with the preset boosted modulation, its available bitrate decreases (or the number of errors increases). When one client cannot communicate with enhanced modulation, another client does not see its available bit rate affected. Thus, the available bit rate of a client depends on its reception conditions and no longer depends on the reception conditions of other clients on the network. The invention, then, has the advantage of isolating wireless links between clients.
    In one variant, an access point transmits an item of silence information intended for stations associated with it and performs measurements during the time interval(s) specified in the silence information, for example, to the detection of another set of nodes or BSS belonging or not to the network (known as the ESS) formed by the BSS.
    Advantageously, all sets of nodes (or BSS) forming a network (or ESS) use the same method to access the channel and the same communication protocols.
    According to one variant, there are several time intervals during which all nodes or all sets of nodes are prohibited from transmitting to allow one of the nodes to obtain a measurement, for example, a radar interference detection measurement. . According to another variant, there are one or several time slots during which all nodes of all sets are allowed to transmit, for example during a flow without quality of service for which the risks of collision, and thus loss of data must be limited.
    权利要求:
    Claims (7)
    [0001]
    1. Method for establishing a first and a second association between a primary node (11) and, respectively, a first and a second wireless node (111, 112), the first association associating a first virtual access point (VAP1) of the head node (11) and the first node (111), the first virtual access point (VAP1) transmitting to the first node (111) first beacon frames (431) comprising a first information item (BSSID1) representing said first association BSS1, the first virtual access point (VAP1) being identified by a service set identifier (SSID), CHARACTERIZED by the fact that when the main node (11) receives from the second node (112) a request for the establishment of the second association, the method comprises, at the level of a controller, steps to:- initialize parameters of said first and second associations,- create a second virtual access point (VAP2) of the main node (11) transmitting to the second node ( 112) next on the beacon frames (432) comprising a second information item (BSSID2) representative of said second association, said second virtual access point (VAP2) being identified by the service set identifier (SSID), - determining, from the said parameters, a first and a second time slots (42, 43) during which, respectively, the first node (111) and the first virtual access point (VAP1) on the one hand, the second node (112) and the second virtual access point (VAP2) are prohibited from sending, - establishing the second association between the second node (112) and the second virtual access point (VAP2), - transmitting, to the first and second nodes (111, 112), at least one item of silence information representing a prohibition to transmit (410) during the first or second time slots (42, 43).
    [0002]
    2. Method, according to claim 1, CHARACTERIZED by the fact that a first and second data transmission bit rates (dr1, dr2) practiced by the first and second nodes linked to the physical modulation employed, respectively, by the first and second nodes (111, 112) in the first and second associations, and a first and second data transmission bit rates (DR1, DR2) required, respectively, by the first and second nodes (111, 112) according to the nature of the data transmitted in the first and second bindings are parameters.
    [0003]
    3. Method, according to claim 2, CHARACTERIZED by the fact that the controller defines a frame duration and by the fact that the first and second time intervals (42, 43) have a duration proportional to the duration of said frame and proportional with respect to the first data transmission bit rate (dr1) practiced by the first node (111) and the first data transmission bit rate (DR1) required by the first node (111) and with respect to the second data transmission bit rate (DR1) data transmission (DR2) required by the second node (112).
    [0004]
    4. Method, according to claim 1, CHARACTERIZED by the fact that a total data transmission bit rate (dr) practiced by the first and second nodes linked to the physical modulation employed, respectively, by the first and second nodes (111, 112) in the first and second associations, and a first and second data transmission bit rates (DR1, DR2) required, respectively, by the first and second nodes (111, 112) according to the nature of data transmitted in the first and in the second associations, are parameters, where the controller defines a frame duration, and where the second and first time slots (42, 43) have a duration that is proportional to the duration of said frame and proportional to the first frame rate. data transmission bits (DR1) required by the first node (111) in relation to the total data transmission bit rate practiced and in relation to the second data transmission bit rate (DR2) required by the second node (112) in in relation to practiced total data transmission bit rate.
    [0005]
    5. Method according to any one of claims 1 to 4, CHARACTERIZED by the fact that said main node (11) is an access point, and by the fact that said first and second nodes (111, 112) are associated to that access point.
    [0006]
    6. Method according to any one of claims 1 to 4, CHARACTERIZED in that the silence information is comprised in at least one silence element (56) of a beacon frame (431, 432).
    [0007]
    7. Controller for establishing a first and a second association between a primary node (11) and, respectively, a first and a second wireless node (111, 112), the first association associating a first virtual access point (VAP1) of the head node (11) and the first node (111), the first virtual access point (VAP1) transmitting to the first node (111) first beacon frames (431) comprising a first information item (BSSID1) representing said first association BSS1, the first virtual access point (VAP1) being identified by a service set identifier (SSID), CHARACTERIZED by the fact that the controller comprises:- means for initializing parameters of said first and second associations, - means for creating a second virtual access point (VAP2) of the main node (11) transmitting to the second node (112) second beacon frames (432) comprising a second information item (BSSID2) representing said second the association, said second virtual access point (VAP2) being identified by the service set identifier (SSID), - means for determining, from said parameters, a first and a second time slot (42, 43) during which, respectively, the first node (111) and the first virtual access point (VAP1) on the one hand, the second node (112) and the second virtual access point (VAP2) are prohibited from sending, for establishing the second association between the second node (112) and the second virtual access point (VAP2), and - means for transmitting to the first and second nodes (111, 112) at least one silence information item representing a prohibition to transmit (410) during the first or second time slots (42, 43).
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    EP2705723A1|2014-03-12|
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    EP2705723B1|2017-08-09|
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    WO2012152733A1|2012-11-15|
    US20140064257A1|2014-03-06|
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    法律状态:
    2018-03-27| B15K| Others concerning applications: alteration of classification|Ipc: H04W 72/04 (2009.01), H04B 7/26 (2006.01), H04W 72 |
    2018-12-11| B06F| Objections, documents and/or translations needed after an examination request according [chapter 6.6 patent gazette]|
    2019-07-23| B25G| Requested change of headquarter approved|Owner name: THOMSON LICENSING (FR) |
    2019-08-06| B25A| Requested transfer of rights approved|Owner name: INTERDIGITAL CE PATENT HOLDINGS (FR) |
    2020-04-07| B06U| Preliminary requirement: requests with searches performed by other patent offices: procedure suspended [chapter 6.21 patent gazette]|
    2021-11-30| B09A| Decision: intention to grant [chapter 9.1 patent gazette]|
    2022-02-01| 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 07/05/2012, OBSERVADAS AS CONDICOES LEGAIS. |
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    PCT/EP2012/058326|WO2012152733A1|2011-05-06|2012-05-07|Method of establishing a first and a second association which are decoupled|
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