Collision detection and recoil window adaptation for multi-user mimo streaming

专利摘要:
COLLISION DETECTION AND BACK WINDOW ADAPTATION FOR MIMO MULTI-USER TRANSMISSION Certain aspects of this description apply generally to a wireless local area network (WLAN), where an access point (AP) has data to be sent to multiple stations (STAS). Using the Downlink Spatial Division Multiple Access (DL-SDMA) technique, the AP can send data to multiple STAs at the same time. Certain aspects of the present description provide techniques and apparatus for detecting that a multi-user multiple-input multiple-output (MU-MIMO) transmission has suffered a collision and for adapting the size of a contention window (CW) to a backoff counter applied to a subsequent MU-MIMO transmission.
公开号:BR112012028152B1
申请号:R112012028152-6
申请日:2011-05-05
公开日:2022-02-01
发明作者:Santosh Paul Abraham；Simone Merlin；Vincent Knowles Iv Jones；Hemanth Sampath；Maarten Menzo Wentink
申请人:Qualcomm Incorporated；
IPC主号:

专利说明:

Field of Invention
Certain aspects of the present description pertain generally to wireless communications and, more specifically, to detecting that a multi-user multiple-input multiple-output (MU-MIMO) transmission has suffered a collision and adapting the size of the backoff window for a subsequent MU-MIMO transmission. Prior Art Description
In order to solve the problem of increasing bandwidth requirements for wireless communication systems, different schemes are being developed to allow multiple user terminals to communicate with a single access point by sharing channel resources obtaining up at the same time high data transmission capacity. Multiple Input Multiple Output (MIMO) technology represents an approach that has recently emerged as a popular technique for next-generation communication systems. MIMO technology has been adopted in several emerging wireless communication standards, such as the Institute of Electrical and Electronics Engineers (IEEE) 802.11 standard. IEEE 802.11 denotes a set of Wireless Local Area Network (WLAN) air interface standards developed by the IEEE 802.11 commission for short-range communications (from tens of meters to a few hundred meters, for example).
A MIMO system uses multiple (NT) transmit antennas and multiple (NR) receive antennas for data transmission. A MIMO channel formed by the NT transmit antennas and the NR receive antennas can be decomposed into NS independent channels, which are also referred to as spatial channels, where NS < min{NT, NR}. Each of the NS independent channels corresponds to a dimension. The MIMO system can present improved performance (greater transmission capacity and/or greater security, for example) if the additional dimensionalities created by the multiple transmit and receive antennas are used.
In wireless networks with a single Access Point (AP) and multiple user stations (STAs), concurrent transmissions can occur on multiple channels to different stations, in either the uplink or downlink directions. Many challenges are present in such systems. Summary of the Invention
Certain aspects of the present description generally apply to a wireless local area network (WLAN), in which an access point (AP) has data to be sent to multiple stations (STAs). Using the Downlink Spatial Division Multiple Access (DL-SDMA) technique, the AP can send data to multiple STAs at the same time. Certain aspects of the present description generally pertain to detecting that a multi-user multiple-input multiple-output (MU-MIMO) transmission has suffered a collision and adapting the size of a contention window to a backoff counter. applied to a subsequent MU-MIMO transmission.
Certain aspects of the present disclosure provide a method for wireless communications. The method generally includes simultaneously transmitting a first plurality of packets to a plurality of apparatus in a first transmission, determining that at least one of a plurality of acknowledgments corresponding to the first plurality of packets has not been received from at least one of the plurality of appliances and increase a containment window (CW) for a setback counter based on determination.
Certain aspects of the present description provide for an apparatus for wireless communications. The apparatus generally includes a transmitter configured to simultaneously transmit a first plurality of packets to a plurality of apparatus in a first transmission and a processing system configured to determine that at least one of a plurality of acknowledgments corresponding to the first plurality of packets has not been received from at least one of the plurality of apparatus and to increment a CW for a backoff counter based on the determination.
Certain aspects of the present disclosure provide for an apparatus for wireless communications. The apparatus generally includes mechanisms for simultaneously transmitting a first plurality of packets to a plurality of apparatus in a first transmission, mechanisms for determining that at least one of a plurality of acknowledgments corresponding to the first plurality of packets has not been received from at least one of a plurality of apparatus and mechanisms for increasing a CW to a setback counter based on determination.
Certain aspects of the present disclosure provide a computer program product for wireless communications. The computer program product generally includes computer readable medium comprising executable instructions for simultaneously transmitting a first plurality of packets to a plurality of apparatus in a first transmission to determine that at least one of a plurality of acknowledgments that correspond to the first plurality of packets not received from at least one of the plurality of apparatus and to increment a CW for a backoff counter based on the determination.
Certain aspects of the present description provide an access point. The access point generally includes at least one antenna; a transmitter configured to simultaneously transmit, via the at least one antenna, a first plurality of packets to a plurality of apparatus in a first transmission; and a processing system configured to determine that at least one of a plurality of acknowledgments corresponding to the first plurality of packets has not been received from at least one of the plurality of apparatus and to increment a CW for a backoff counter based on the determination.
Certain aspects of the present disclosure provide a method for wireless communications. The method generally includes simultaneously transmitting a first plurality of packets to a plurality of apparatus in a first transmission, wherein the first plurality of packets comprises a packet associated with an access category selected from a plurality of access categories, determining that an acknowledgment corresponding to the packet has not been received from a designated device of the plurality of devices, wherein the designated device is associated with the selected access category and increasing a contention window (CW) for a backoff counter associated with the selected access category , based on the determination.
Certain aspects of the present disclosure provide for an apparatus for wireless communications. The apparatus generally includes a transmitter configured to simultaneously transmit a first plurality of packets to a plurality of apparatus in a first transmission, wherein the first plurality of packets comprises a packet associated with an access category selected from a plurality of categories of access. access, a first circuit for determining that an acknowledgment corresponding to the packet has not been received from a designated device of the plurality of devices, wherein the designated device is associated with the selected access category, and a second circuit configured to increase a contention window ( CW) for a setback counter associated with the selected access category, based on the determination.
Certain aspects of the present disclosure provide for an apparatus for wireless communications. The apparatus generally includes mechanisms for simultaneously transmitting a first plurality of packets to a plurality of apparatus in a first transmission, wherein the first plurality of packets comprises a packet associated with an access category selected from a plurality of access categories, mechanisms for determining that an acknowledgment corresponding to the packet has not been received from a designated device of the plurality of devices, wherein the designated device is associated with the selected access category, and mechanisms for increasing a contention window (CW) for a counter of indentations associated with the selected access category, based on the determination.
Certain aspects of the present disclosure provide a computer program product for wireless communications. The computer program product generally includes computer readable medium comprising executable instructions for simultaneously transmitting a first plurality of packets to a plurality of apparatus in a first transmission, wherein the first plurality of packets comprises a packet associated with a selected access category from a plurality of access categories, determining that an acknowledgment corresponding to the packet has not been received from a designated device of the plurality of devices, wherein the designated device is associated with the selected access category, and increasing an access window contention (CW) for a setback counter associated with the selected access category, based on the determination.
Certain aspects of the present description provide an access point. The access point generally includes at least one antenna, a transmitter configured to simultaneously transmit a first plurality of packets to a plurality of apparatus in a first transmission, wherein the first plurality of packets comprises a packet associated with an access category selected from a plurality of access categories, a first circuit configured to determine that an acknowledgment corresponding to the packet has not been received from a designated device of the plurality of devices, wherein the designated device is associated with the selected access category, and a second circuit configured to increase a contention window (CW) for a setback counter associated with the selected access category, based on the determination. Brief Description of Drawings
In order that the manner in which the above enumerated features of the present description are implemented may be understood in detail, a more specific description, briefly summarized above, may be made with reference to aspects, some of which are shown in the accompanying drawings. It should be noted, however, that the accompanying drawings only show certain aspects of this description and, therefore, should not be considered as limiting its scope, as the description may admit other equally effective aspects.
Figure 1 shows a diagram of a wireless communications network in accordance with certain aspects of the present description.
Figure 2 shows a block diagram of an exemplary access point and user terminals in accordance with certain aspects of the present disclosure.
Figure 3 shows a block diagram of an exemplary wireless device in accordance with certain aspects of the present disclosure.
Figure 4 shows an exemplary multi-input, multi-output downlink multi-user (DL-MU-MIMO) protocol in accordance with certain aspects of the present disclosure.
Figure 5 shows exemplary operations that can be performed on an access point to detect a collision and update a contention window in accordance with certain aspects of the present description.
Figure 5A shows exemplary mechanisms capable of performing the operations shown in Figure 5.
Figure 6 is a graph enumerating different options for detecting a collision and rules for calculating the contention window depending on the different options, in accordance with certain aspects of the present description.
Figure 7 shows exemplary operations that can be performed on an access point to detect a collision and update a contention window in accordance with certain aspects of the present description.
Figure 7A shows exemplary mechanisms capable of performing the operations shown in Figure 7. Detailed Description of the Invention
Various aspects of the description are described more fully below with reference to the accompanying drawings. This description may, however, be embodied in many different forms and should not be construed as limited to any specific structure or function presented throughout this description. Rather, these aspects are presented so that this description is complete and fully conveys the scope of the description to those skilled in the art. Based on the present teachings, those skilled in the art should understand that the scope of the description is intended to cover any aspect of the description described herein, whether implemented independently of or combined with any other aspect of the description. For example, an apparatus may be implemented or a method may be practiced using any number of the aspects presented herein. Furthermore, the scope of the description is intended to cover such apparatus or method which is put into practice using another structure, functionality, or structure and functionality in addition to or other than the various aspects of the description described herein. It is to be understood that any aspect of the description described herein may be embodied by one or more elements of a claim.
The word "exemplary" is used herein to mean "which serves as an example, occurrence or illustration". Any aspect described herein as "exemplary" should not necessarily be interpreted as preferred or advantageous compared to other aspects.
While specific aspects are described herein, many variations and permutations of these aspects are included within the scope of the description. Although some benefits and advantages of preferred aspects are mentioned, the scope of the description is not intended to be limited to specific benefits, uses or objectives. Rather, aspects of the description are intended to be broadly applicable to different wireless technologies, system configurations, networks and transmission protocols, some of which are shown by way of example in the figures and in the following description of preferred aspects. The detailed description and drawings are merely illustrative of the description and not limiting of the scope of the description which is defined by the appended claims and equivalents thereof. Exemplary Wireless Communication System
The techniques described here can be used in a variety of broadband wireless communication systems, which include communication systems that are based on an orthogonal multiplexing scheme. Examples of such communication systems include Spatial Division Multiple Access (SDMA), Time Division Multiple Access (TDMA), Orthogonal Frequency Division Multiple Access (OFDMA), Carrier Frequency Division Multiple Access (TDMA) systems. Single (SC-FDMA) and so on. An SDMA system can use sufficiently different directions to simultaneously transmit data belonging to multiple user terminals. A TDMA system can allow multiple user terminals to share the same frequency channel by dividing the transmission signal into different time slots, each time slot being assigned to a different user terminal. An OFDMA system uses orthogonal frequency division multiplexing (OFDM), which is a modulation technique that partitions the total system bandwidth into multiple orthogonal subcarriers. These subcarriers may also be called tones, binaries, etc. With OFDM, each subcarrier can be modulated with data independently. An SC system
FDMA can use interleaved FDMA (IFDMA) to transmit on subcarriers that are distributed across the system bandwidth, localized FDMA (LFDMA) to transmit on a block of adjacent subcarriers, or Enhanced FDMA (EFDMA) to transmit on multiple blocks of subcarriers adjacent. In general, modulation symbols are sent in the frequency domain with OFDM and in the time domain with SC-FDMA.
The present teachings can be incorporated into (implemented within or executed, for example) various wired or wireless devices (nodes, for example). In some aspects, a wireless node implemented in accordance with the present teachings may comprise an access point or an access terminal.
An access point (“AP”) may comprise, be implemented or known as, a NodeB, Radio Network Controller (“RNC”), eNodeB, Base Station Controller (“BSC”), Base Transceiver Station (“BTS”). ”), Base Station (“BS”), Transceiver Function (“TF”), Radio Router, Radio Transceiver, Basic Service Suite (“BSS”), Extended Service Suite (“ESS”), Radio- Base Station (“RBS”) or some other terminology.
An access terminal ("AT") may comprise, be implemented or known as, an access terminal, a subscriber station, a subscriber unit, a mobile station, a remote station, a remote terminal, a user terminal, a user agent, a user device, a user equipment, a user station, or some other terminology. In some implementations, an access terminal may comprise a cellular phone, a cordless phone, a Session Initiation Protocol (“SIP”) phone, a wireless local loop station (“WLL”), a personal digital assistant. (“PDA”), a handheld device that has wireless connectivity, a Station (“STA”) or some other suitable processing device connected to a wireless modem. Accordingly, one or more aspects taught herein may be incorporated into a telephone (a cell phone or a smart phone, for example), a computer (a laptop, for example), a portable communication device, a portable computing device ( a personal data assistant, for example), an entertainment device (a music or video device or a satellite radio, for example), a global positioning system device, or any other suitable device that is configured to communicate through a wireless or wired medium. In some ways, the node is a wireless node. Such a wireless node may, for example, provide connectivity to or with a network (a wide area network such as the Internet or a cellular network, for example) via a wired or wireless communication link.
Figure 1 shows a multiple-input multiple-output (MIMO) multiple access system 100 with access points and user terminals. For simplicity, only one access point 110 is shown in Figure 1. An access point is generally a fixed station that communicates with user terminals and may also be referred to as a base station or some other terminology. A user terminal may be fixed or mobile and may also be referred to as a mobile station, wireless device or some other terminology. Access point 110 may communicate with one or more user terminals 120 at any given time on the downlink and uplink. The downlink (i.e. forward link) is the communication link from the access point to the user terminals, and the uplink (i.e. reverse link) is the communication link from the user terminals to the access point . A user terminal can also communicate non-hierarchically with another user terminal. A system controller 130 couples to and provides coordination and control for the access points.
Although parts of the following description describe user terminals 120 capable of communicating via Spatial Division Multiple Access (SDMA), for certain aspects the user terminals 120 may also include some user terminals that do not support SDMA. Thus, for such purposes, an AP 110 can be configured to communicate with both SDMA and non-SDMA user terminals. This approach can properly allow older versions of user terminals ('legacy' stations) to remain in use within an enterprise, prolonging their lifespan, while allowing newer SDMA user terminals to be introduced as deemed appropriate.
System 100 uses multiple transmit and receive antennas for downlink and uplink data transmission. Access point 110 is equipped with Nap antennas and represents the multiple input (MI) scheme for downlink transmissions the multiple output (MO) scheme for uplink transmissions. A set of K selected user terminals 120 collectively represent the multiple outputs for downlink transmissions and the multiple inputs for uplink transmissions. For pure SDMA, it is desirable to have Nap > K > 1 if the data symbol streams to the K user terminals are not multiplexed in code, frequency or time by some mechanisms, K may be greater than Nap if the symbol streams from data can be multiplexed using TDMA technique, different code channels with CDMA, disjointed sets of subbands with OFDM and so on. Each selected user terminal transmits user-specific data to and/or receives user-specific data from the access point. In general, each selected user terminal can be equipped with one or multiple antennas (ie Nut > 1). The K selected user terminals can have the same or different number of antennas.
The MIMO 100 system can be a time division duplex (TDD) system or a frequency division duplex (FDD) system. For a TDD system, the downlink and uplink share the same frequency band. For an FDD system, the downlink and uplink use different frequency bands. The MIMO system 100 can also use single or multiple carriers for transmission. Each user terminal can be equipped with a single antenna (so as to keep costs down, for example) or multiple antennas (where the additional cost can be borne, for example). System 100 can also be a TDMA system if user terminals 120 share the same frequency channel by dividing the transmit/receive into different time slots, each time slot being assigned to a different user terminal 120.
Figure 2 shows a block diagram of the access point 110 and two user terminals 120m and 120x in the MIMO system 100. The access point 110 is equipped with Nt antennas 224a to 224t. The 120m user terminal is equipped with Nut,m antennas 252ma to 252mu, and the 120x user terminal is equipped with Nut,x antennas 252xa to 252xu. Access point 110 is a transmitting entity for the downlink and a receiving entity for the uplink. Each user terminal 120 is a transmit entity for the uplink and a receive entity for the downlink. As used herein, a "transmitting entity" is an independently operated apparatus or device capable of transmitting data over a wireless channel and a "receiving entity" is an independently operated apparatus or device capable of receiving data. through a wireless channel. In the following description, the subscript “dn” denotes the downlink, the subscript “up” denotes the uplink, Nup user terminals are selected for simultaneous transmission on the uplink, Ndn user terminals are selected for simultaneous transmission on the downlink, Nup may or may not be equal to Ndn and Nup and Ndn may be static values or may change for each schedule interval. Beam steering or some other spatial processing technique can be used at the access point and at the user terminal.
On the uplink, at each user terminal 120 selected for uplink transmission, a TX data processor 288 receives traffic data from a data source 286 and control data from a controller 280. The TX data processor 288 processes ( encodes, encodes, interleave and modulates, for example) the traffic data for the user terminal based on the coding and modulation schemes associated with the selected rate to the user terminal and generates a stream of data symbols. A TX spatial processor 290 performs spatial processing on the data symbol stream and generates Nut,m transmission symbol streams for the Nut,m antennas. Each transmitter unit (TMTR) 254 receives and processes (converts to analog, amplifies, filters and upconverts, for example) a respective stream of transmission symbols to generate an uplink signal. Nut,m transmitter units 254 generate Nut,m uplink signals for transmission from Nut,m antennas 252 to the access point.
Nup user terminals can be programmed for simultaneous transmission on the uplink. Each of these user terminals performs spatial processing on its data symbol stream and transmits its set of uplink transmission symbol streams to the access point.
At access point 110, Nup antennas 224 to 224ap receive the uplink signals from all Nup user terminals transmitting on the uplink. Each antenna 224 sends a received signal to a respective receiver unit (RCVR) 222. Each receiver unit 222 performs processing complementary to that performed by the transmitter unit 254 and generates a stream of received symbols. An RX spatial processor 240 performs receiver spatial processing on the Nap symbol streams received from the Nap receiver units 222 and generates Nup retrieved uplink data symbol streams. Receiver spatial processing is performed according to channel correlation matrix inversion (CCMI), minimum mean square error (MMSE), provisional cancellation cancellation (SIC), or some other technique. Each retrieved uplink data symbol stream is an estimate of a data symbol stream transmitted by a respective user terminal. A data processor RX 242 processes (demodulates, deinterleave and decodes, for example) each stream of retrieved uplink data symbols according to the rate used for that stream in order to obtain decoded data. The decoded data for each user terminal may be sent to a data warehouse 244 for storage and/or to a controller 230 for further processing.
Downlink, at access point 110, a TX data processor 210 receives traffic data from a data source 208 to Ndn user terminals scheduled for transmission on the downlink, control data from a controller 230, and possibly other data from a scheduler 234. Different types of data can be sent on different transport channels. The TX data processor 210 processes (encodes, interleaves and modulates, for example) the traffic data for each user terminal based on the rate selected for that user terminal. The TX data processor 210 generates Ndn downlink data symbol streams for the Ndn user terminals. A TX spatial processor 220 performs spatial processing (such as precoding or beamforming as described in the present description) on the Ndn downlink data symbol streams and generates Nap transmit symbol streams for the Nap antennas. Each transmitter unit 222 receives and processes a respective stream of transmission symbols to generate a downlink signal. Nap transmitter units 222 generate Nap downlink signals for transmission from the Nap antennas 224 to the user terminals.
At each user terminal 120, Nut,m antennas 252 receive the Nap downlink signals from access point 110. Each receiver unit 254 processes a signal received from a connected antenna 252 and generates a stream of received symbols. An RX spatial processor 260 performs receiver spatial processing on Nut,m symbol streams received from Nut,m receiver units 254 and generates a retrieved downlink data symbol stream for the user terminal. Receiver spatial processing is performed according to CCMI, MMSE or some other technique. An RX data processor 270 processes (demodulates, deinterleave and decodes, for example) the retrieved downlink data symbol stream in order to obtain decoded data for the user terminal.
At each user terminal 120, a channel estimator 278 estimates the downlink channel response and generates downlink channel estimates, which may include channel gain estimates, SNR estimates, noise variance, and so on. Similarly, a channel estimator 228 estimates the uplink channel response and generates uplink channel estimates. Controller 280 for each user terminal derives the spatial filter matrix for the user terminal based on the downlink channel response matrix Hdn,m for that user terminal. Controller 230 derives the spatial filter matrix for the access point based on the effective uplink channel response matrix Hup,eff. Controller 280 for each user terminal can send feedback information (such as, for example, downlink and/or uplink eigenvectors, eigenvalues, SNR estimates, and so on) to the access point. Controllers 230 and 280 also control the operation of various processing units at access point 110 and user terminal 120, respectively.
Figure 3 shows various components that can be used in a wireless device 302, which can be used within a wireless communication system, such as the MIMO system 100. The wireless device 302 is an example of a device that can be used. configured to implement the various methods described here. Wireless device 302 may be an access point 110 or a user terminal 120.
Wireless device 302 may include a processor 304, which controls the operation of wireless device 302. Processor 304 may also be referred to as a central processing unit (CPU). Memory 306, which may include both read-only memory (ROM) and random access memory (RAM), provides instructions and data for the processor 304. A portion of memory 306 may also include non-volatile random access memory (NVRAM). . Processor 304 typically performs arithmetic and logic operations based on program instructions stored within memory 306. Instructions in memory 306 may be executed to implement the methods described herein.
Wireless device 302 may also include housing 308, which may include transmitter 310 and receiver 312 to allow transmission and reception of data between wireless device 302 and a remote location. Transmitter 310 and receiver 312 may be combined in a transceiver 314. A single or a plurality of transmit antennas 316 may be attached to housing 308 and electrically coupled to transceiver 314. Wireless device 302 may also include multiple transmitters, multiple receivers and multiple transceivers (not shown).
Wireless device 302 may also include a signal detector 318, which may be used in an effort to detect and quantify the level of signals received by transceiver 314. Signal detector 318 may detect such signals as total power, power per subcarrier by symbol, energy spectral density and other signals. Wireless device 302 may also include a digital signal processor (DSP) 320 for use in signal processing.
The various components of the wireless device 302 may be coupled together by a bus system 322, which may include a power bus, a control signal bus, and a condition signal bus in addition to a data bus.
Collision Detection and Containment Window Update Exemplars
In next-generation WLANs, such as the MIMO 100 system of Figure 1, a downlink (DL) multi-user (MU) MIMO transmission represents a promising technique for increasing total network transmission capacity. Under most aspects of a MU-MIMO DL transmission, a non-beamed portion of a preamble transmitted from an access point (AP) to a plurality of user stations (STAs) may carry a spatial stream allocation field. which includes allocation of spatial flows to the STAs.
In an effort to parse this allocation information from the perspective of an STA, each STA may determine its rank or a number of STAs in a set of STAs from the plurality of STAs scheduled to receive the MU transmission. This determination can lead to the formation of groups, where a group identification (group ID) field in the preamble can transmit, to the STAs, the set of STAs (and their order) that is transmitted in a given MU transmission. With the addition of preamble bits to the transmission overhead, it is desirable to spend as few bits as possible on the group ID, while not sacrificing the flexibility related to STAs that can be programmed together in a MU-MIMO transmission at a given time. instant in time.
In single user (SU) transmissions, a packet is sent to a given STA, which in turn typically sends back an acknowledgment (ACK). Based on the received ACK (or a missing ACK), the sender (the AP, for example) can determine whether the transmission was successful (or experienced a collision). In IEEE 802.11, if a packet experiences a collision, some rules set the backoff value for successive transmissions.
Before each transmission, the AP can generate a random number between 0 and CW (CW = contention window) called backsliding counter. The AP can then begin to count down the recoil value while the (wireless) medium is idle. Once the backoff counter reaches 0, the AP is allowed to send a packet through the medium.
The packet may not be received or may be incorrectly received by the intended recipient, and in such cases, a block acknowledgment (BA) is not sent by the recipient as a response. In response to this event, the AP can retransmit the same packet.
The CW value in the current IEEE 802.11 standard is fixed to an initial value CWmin for the first transmission of a given packet and then computed as for each consecutive packet retransmission, where R is a counter that counts the number of consecutive collisions of the same packet ( R = 1 for the first retransmission and so on). A transmission can be considered “failed” if the BA for the data packet is not received.
The rationale behind this choice to increase the CW is based on the assumption that a transmitted packet was not received correctly because the packet collided with another transmission. Thus, the absence of a BA can be used as a way to detect a collision. In response to the collision, the CW can be increased so that the AP can more likely wait longer before accessing the medium, avoiding successive collisions.
Figure 4 shows a downlink multi-user multiple-input multiple-output (DL-MU-MIMO) protocol in accordance with certain aspects of the present disclosure. To begin with, the AP may transmit a Request to Send (RTS) message 402 to one of the STAs (STA1, for example) selected to receive the DL-MU-MIMO transmission. All data in the MU-MIMO aggregate can be of the same priority class. The RTS message 402 can be sent using contention parameters of a data class in the MU-MIMO aggregate.
Upon receiving the RTS message 402, the selected STA (STA1, for example) may transmit a Remove to Send (CTS) 404 message to the AP. The RTS message 402 and the CTS message 404 may be separated by a short interframe space (SIFS), a small gap between a data frame or other message and its acknowledgment (ACK). In response to receipt of the CTS message 404, the AP may send DL-MU-MIMO data 406 to scheduler-selected STAs (typically part of the AP's processing system, such as the scheduler 234 of Figure 2 ). STAs receiving DL-MU-MIMO data 406 can transmit BAs 408 on the uplink (UL) in series, starting with BA to STA1 and ending with BA to STA3, as shown in Figure 4. STA transmissions BA can be separated by SIFS. The order and timing for STA BA transmissions can be sent in the DL-MU-MIMO 406 data.
In DL-MU-MIMO transmissions, multiple packets are sent at the same time to different STAS. If all acknowledgments (ACKs) are received, the transmission can be considered successful. If no ACK is received, all packets presumably have failed, and this event can reasonably be interpreted as a collision. If only some of the ACKs are missing, while others are received, then the significance of this event (i.e., whether this was a collision or a collision for only some of the STAs) and the appropriate reaction in terms of increasing the contention window (CW ) can be set. In Figures 1 and 4, for example, the MU-MIMO data 406 was sent to STA1 (user terminal 120a), STA2 (user terminal 120b) and STA3 (user terminal 120c) and a BA was then received from each of STA1 and STA2, but not from STA2.
Figure 5 shows 500 exemplary operations that can be performed on an access point, for example, to detect a collision and update a contention window in accordance with certain aspects of the present description. Operations 500 may begin, at 502, by simultaneously transmitting a first plurality of packets to a plurality of apparatus (STAs, for example) in a first transmission. For certain aspects, the first plurality of packets may comprise DL-MU-MIMO packets. At 504, the access point may determine that at least one of a plurality of acknowledgments corresponding to the first plurality of packets has not been received from at least one of the plurality of appliances. For certain aspects, the plurality of acknowledgments may comprise block acknowledgments. The access point may, at 506, increase a contention window (CW) for a backstop counter based on the determination at 504.
For certain aspects, operations 500 may comprise implementing a counter based on the determination at 504, such that increasing the CW by 506 comprises calculating the CW based on the counter. Calculating CW may comprise raising a minimum CW value (CWmin) up to the sum power of the counter and 1 for certain aspects, as described in detail below.
For certain aspects, the AP can optionally initialize the fallback counter to 508. The fallback counter can be generated as a random number between 0 and a value associated with the CW. At 510, the AP can optionally count down the rollback counter (from the random number at startup, for example). In response to the backoff counter reaching the end of the countdown (a value of zero, for example), the AP may simultaneously transmit, at 512, a second plurality of packets in a second transmission. For certain aspects, the second plurality of packets may comprise DL-MU-MIMO packets.
For certain aspects, the AP may optionally provide a plurality of counters, one counter for each of the plurality of appliances (STAs, for example). For each of the plurality of counters, the AP may: (1) increment the counter for a specific device among the devices in response to failure to receive one of the plurality of acknowledgments that corresponds to the specific device among the devices; and (2) resetting the counter for a specific device among the devices in response to receipt of one of the plurality of acknowledgments corresponding to the specific device among the devices.
After a DL-MU-MIMO data transmission, the access point can determine whether each expected and valid BA is received or missing and update the CW for the next transmission based on the BAs received or missing from the transmission(s). ) previous(s). A valid block can be defined in any of several suitable ways, which include: • any block ACK; • any block ACK of a specific class, where the specific class can be the class used to access the medium in data transmission above;• specifically for IEEE 802.11e networks, a BA from an STA may be considered valid if that BA contains affirmative acknowledgment from at least one of the media access control (MAC) protocol data units (MPDUs) sent to the STA on exactly preceding MU-MIMO broadcast; or• specifically for IEEE 802.11e networks, a BA of an STA may be considered valid if that BA contains an affirmative acknowledgment of all MPDUs sent to the STA in the exactly preceding MU-MIMO transmission.
The present description describes different solutions for how a missing acknowledgment can be interpreted and can affect the fallback rules by increasing the contention window (CW). The CW increase can be performed according to any of Options 1 to 4 described below and summarized in Graph 600 of Figure 6, which shows several rules for determining the contention window based on the options for declaring the occurrence of a collision. Option 1
For certain aspects of the description, if the first STA in the plurality of STAs for DL-MU-MIMO transmission does not send back a valid BA, the transmission may be considered to have experienced a collision. For example, if the BA from STA1 of Figure 4 has not been received, the AP may interpret this result to mean that a collision has occurred. In contrast, if the BA from STA1 of Figure 1 is received, but the BA from STA1 or STA3 has not been received, the AP may consider this to be a successful transmission and may not interpret this to mean that a collision has occurred accordingly. with Option 1.
The AP may maintain a counter R, which counts successive collisions. The CW can be increased as a function of R. For example, the contention window can be initially set to a value of C'.' = C','... . and the CW can be calculated to be equal to for each consecutive collision, as shown in Figure 6. As another example, the contention window can be initially set to a value of C'.'= C'.'.. . and CW can be calculated as equal to for each consecutive collision. For certain aspects, the CW can be limited to an increase of no more than a maximum value called CWmax. Option 2
For certain aspects of the description, if any of the STAs does not send back a valid BA, the transmission is considered to have suffered a collision.
For example, if any BA from STA1, STA2 or STA3 of Figure 4 has not been received, the AP can interpret this result to mean that a collision has occurred.
Similar to Option 1, the contention window for Option 2 can be initially set to a value of C'.r = . and CW can be calculated to be equal to for each consecutive collision, as shown in Figure 6. For other aspects, CW can be calculated to be equal to for each consecutive collision. For certain aspects, CW can be limited to an increase not greater than a maximum value called CWmax. Option 3
For certain aspects of the description, if all STAs do not send back a valid BA, the transmission is considered to have suffered a collision. For example, if none of the STA1, STA2, and STA3 BAs in Figure 4 have not been received, the AP can reasonably decide that a collision has occurred. However, if at least one of the BAs from STA1, STA2 or STA3 has been received, the AP may not consider that a collision has occurred under this option.
Similar to Option 1, the contention window for Option 3 may be initially set to a value of C'.' = C'/.... and CW can be calculated to be equal to for each consecutive collision, as shown in Figure 6. For other aspects, CW can be calculated to be equal to for each consecutive collision.
For certain aspects, the CW can be limited to an increase no greater than a maximum value called CWmax. Option 4
For certain aspects of the description, collisions can be counted on a per STA basis, where the
AP can assume that a specific STA has suffered a collision if that STA does not send back a valid BA. For example, if the BA of STA2 of Figure 4 has not been received, but the BAs of STA1 and STA3 have been received, the AP can determine that STA2 has suffered a collision and that STA1 and STA3 have not suffered a collision.
For this option, the AP can maintain a counter Ri for each STAi and can count the number of consecutive collisions that correspond to that specific STAi. Before a transmission, the contention window can be computed as a function of {Ri,..., Rj}, where {Ri,..., Rj} indicates the counters that correspond to the individual STAs {STAi,... , STAj} that will be included in the broadcast. For example, such a function might include computing CW as r r J , , , where Rmax is the maximum of the set {Ri,..., Rj}.
With any of these options described above, the collision detection and backtracking rules specified for an IEEE 802.11 network can be extended to the case of downlink multi-user MIMO (DL-MU-MIMO) transmissions. This can preserve fairness with respect to legacy IEEE 802.11 devices in mixed networks that include both legacy and MUMIMO capable devices.
Collision Detection and Exemplary Backward Window Adaptation for Multi-Access Category MU-MIMO Transmission
An exponential backoff after a collision can be essential to the functioning of Enhanced Distributed Channel Access (EDCA) in an IEEE 802.11 network. Collision detection may not be straightforward when a single downlink multi-user (DLMP) packet (ie, transmission) from an access point (AP) has block acknowledgments (BAs) from multiple destinations. For certain aspects, detection of a collision can be extended to MU-MIMO transmissions of multiple access categories (multi-AC), where BAs referring to different classes (ie, access categories) can be received on each DLMP.
For certain aspects, collisions may occur in a subset of STAs for a MUMIMO transmission. Furthermore, collisions in subsequent transmissions can affect different subsets of STAs. Collisions can be caused by (and affect) a different contending STA by each target STA in the DLMP (ie STAs can be hidden from each other). For certain aspects, a collision-detection-and-increase-of-dispute-window (CW) mechanism may be involved that does not penalize IEEE 802-11ac APs over IEEE 802.11n APs. co-located disputants (that is, as aggressive as an IEEE 802.11n AP). In addition, a collision-detection-and-CW-augmentation mechanism that is unbiased with contending STAs (ie, at least as unbiased as an IEEE 802.11n AP) is desirable. Furthermore, collision detection can be extended to multi-AC MU-MIMO transmissions.
For Option 2, described above, the AP can be collision sensitive on individual STAs (as in IEEE 802.11n). In other words, the AP can be as aggressive or less aggressive than an IEEE 802.11n AP. However, the CW at the AP may tend to a higher value due to only one STA suffering a high packet error rate. In other words, there may be lower transmission capacity for IEEE 802.11ac BSSs if they are in dispute with IEEE 802.11n BSSs. In addition, consecutive losses may originate from different STAs, where Option 2 may not distinguish between different STAs and the AP may continue to increase CW (ie, too conservative).
For Option 3, described above, the CW for an AP may not be biased by the worst STA. However, the AP may not be sensitive to collisions in individual STAs. In other words, exponential backoff can never occur if there is a “lucky” STA that is unaffected by collisions while other STAs experience collision (ie, more aggressive than an IEEE 802.11n AP).
For certain aspects, a mechanism can be designed that behaves similarly to an IEEE 802.11n AP. A primary STA can be defined by each class (ie, the STA that would have been served if that class had won the dispute, if the AP were IEEE 802.11n). The fallback rules can be based on the primary STA of the class that wins the contest. In other words, what happens to other MU-MIMO data can be ignored.
An IEEE 802.11n AP can transmit to a single STA, but the interference produced can cause collisions at other locations. The IEEE 802.11n AP may not detect these collisions. The MU-MIMO scheme may involve broadcasting to multiple STAs at the same time and may include the ability to detect collisions at multiple destinations. However, multi-destination collision detection can lead to more conservative access than IEEE 802.11n. While Option 2, described above, can account for collisions in a single STA, that STA can be any STA and can be a different STA on each transmission (ie, no memory). Also, Option 2 does not specify how to handle multiple classes. In other words, Option 2 may not be a correct extension to the IEEE 802.11n mechanism.
In IEEE 802.11n, each class can compete with other classes internally (ie, within the AP). The winning class can send a packet header (HOL). For certain aspects, the HOL packet can also be a packet that is retransmitted. If the packet fails, the contention window for that access category (CW[AC]) can be increased. If the packet passes through or reaches the maximum retries limit, the CW can be reset. A new containment window can be started again for the next access. The new contest winner can be from any of the classes. The appropriate CW[AC] can be used.
For certain aspects, an AP may designate a primary STA for each class. The primary STA by each class can be the destination of the HOL data (ie primary data) belonging to the class. After the internal dispute, there may be a “winning class”, where the AP can send data to the winning class. The winning class can be selected according to the IEEE 802.11n Enhanced Distributed Channel Access (EDCA) rules. For certain aspects, the AP may also piggyback (ie MU-MIMO) some other data of the same or different classes, where the selection of the other data may even be a programmer of APs. In each transmission, only the CW[AC] for the winning class can be updated, based on the acknowledgment (ACK) from the primary STA of the winning class only. If the ACK is received, the CW of the winning class can be reset. In addition, the STA's “primary” title can be removed, and a new STA can be elected as a primary. If the queue of winning classes is registered retroactively, a new indentation can be generated, based on the CW, as in IEEE 802.11n.
However, if the ACK is not received, the CW of the winning class can be increased. In addition, the primary STA may remain the same for the winning class.
Furthermore, the backoff counter can be regenerated based on the Quality of Service (QoS) Short Retry Counter (QSRC) as in 802.11n. QSRC can determine how often a frame is retransmitted after a collision until the frame is discarded. In response to the backoff counter reaching the end of the countdown, a second plurality of packets in a second transmission may be transmitted, wherein the second plurality of packets comprises the packet associated with the winning class. The CW and recoil value for classes other than the winning class may not be modified. Therefore, all collisions or successful transmissions other than successful transmissions to the primary STA of the winning class can be ignored (ie for QSRC update). However, aggregated MAC protocol data unit (A-MPDU) retry counters can always be updated for all STAs in order to avoid continually resubmitting some MPDUs. On the next transmission, the AP can perform internal contention between the classes again. Therefore, the winning class may be different in each broadcast.
If only one STA can be served on each transmission (ie, no MU-MIMO), that STA can be the primary STA for the class that wins the dispute (ie, the behavior is the same as IEEE 802.11n). However, if multiple STAs are served on each transmission, the behavior of STAs other than the primary STA may not affect backoff (ie, the MIMO scheme can be completely transparent). In other words, the mechanism can have the same fallback behavior as the IEEE 802.11n AP.
Figure 7 shows 700 exemplary operations that can be performed on an access point, for example, to detect a collision and update a contention window in accordance with certain aspects of the present description. Operations 700 may begin, at 702, by simultaneously transmitting a first plurality of packets to a plurality of apparatus (STAs, for example) in a first transmission, wherein the first plurality of packets comprises a packet associated with an access category. selected from a plurality of access categories. The first plurality of packets may comprise DL-MU-MIMO packets. Furthermore, each of the packages in the plurality of packages may be associated with one of the access categories. For certain aspects, the access category may be selected from the plurality of access categories in an effort to resolve resource disputes among the plurality of access categories. At 704, the access point may determine that an acknowledgment corresponding to the packet has not been received from a designated device of the plurality of devices, wherein the designated device is associated with the selected access category. At 706, the access point can increase the contention window (CW) by a setback counter associated with the selected access category, based on the determination.
The various method operations described above may be performed by any suitable mechanisms capable of performing the corresponding functions. The mechanisms may include various hardware and/or software components and/or modules, which include, but are not limited to, a circuit, an application-specific integrated circuit (ASIC), or processor. Generally, where there are operations shown in the figures, those operations may have corresponding engine-plus-function components with similar numbering. For example, the operations 500 shown in Figure 5 correspond to the mechanism 500A shown in Figure 5A.
For example, mechanisms for transmitting may comprise a transmitter, such as the transmitter unit 222 of access point 110 shown in Figure 2. Mechanisms for processing, mechanisms for determining, mechanisms for raising, mechanisms for incrementing, mechanisms for raising, mechanisms for initializing, resetting mechanisms, calculating mechanisms, or counting mechanisms may comprise a processing system, which may include one or more processors, such as programmer 234, data processor RX 242, data processor TX 210 and/or the controller 230 of the access point 110 shown in Figure 2. Mechanisms for receiving may comprise a receiver, such as the receiver unit 222 of the access point 110 shown in Figure 2.
As used herein, the term "determine" encompasses a wide variety of actions. For example, “determine” may include calculating, computing, processing, deriving, investigating, searching (such as searching a table, database, or other data structure), verifying, and the like. Furthermore, “determining” can include receiving (eg receiving information), accessing (eg accessing data in a memory) and the like. Furthermore, “determine” may include resolving, selecting, choosing, establishing and the like.
As used herein, a phrase referring to “at least one of” a list of items refers to any combination of those items, including single elements. As an example, “at least one of: a, b or c” is intended to cover: a, b, c, a-b, a-c, b-c and a-b-c.
The various illustrative logic blocks, modules and circuits described in connection with the present description may be implemented or executed with a general purpose processor, a digital signal processor (DSP), an application specific integrated circuit (ASIC), an array of field programmable gates (FPGA) or other programmable logic device, discrete gate or transistor logic, discrete hardware components, or any combination thereof designed to perform the functions described herein. A general purpose processor may be a microprocessor, but alternatively the processor may be any conventional processor, controller, microcontroller, or state machine. A processor may also be implemented as a combination of computing devices, for example, a DSP and microprocessor combination, a plurality of microprocessors, one or more microprocessors together with a DSP core, or any other such configuration.
The method or algorithm steps described in connection with the present description may be embodied directly in hardware, in a software module executed by a processor, or in a combination of the two. A software module may reside on any form of storage medium that is known in the art. Some examples of storage media that can be used include RAM memory, flash memory, ROM memory, EPROM memory, EEPROM memory, registers, a hard disk, a removable disk, a CD-ROM, and so on. A software module may comprise a single instruction, or many instructions, and may be distributed across multiple different code segments, between different programs, and across multiple storage media. A storage medium may be coupled to a processor so that the processor can read information from, and write information to, the storage medium. Alternatively, the storage medium may be integral with the processor.
The methods described herein comprise one or more steps or actions to obtain the method described. Method steps and/or actions may be interchanged with each other without abandoning the scope of the claims. In other words, unless a specific order of steps or actions is specified, the order and/or use of specific steps and/or actions may be used without departing from the scope of the claims.
The functions described can be implemented in hardware, software, firmware or any combination of them. If implemented in hardware, an exemplary hardware configuration might comprise a processing system on a wireless node. The processing system can be implemented with a bus architecture. The bus can include any number of interconnecting buses and bridges depending on the specific processing system application and overall design constraints. The bus can connect several circuits together, which include a processor, machine-readable media, and a bus interface. The bus interface can be used to connect a network adapter, among other things, to the processing system via the bus. The network adapter can be used to implement PHY layer signal processing functions. In the case of a user terminal 120 (see Figure 1), a user interface (such as keyboard, monitor, mouse, joystick, etc.) can also be connected to the bus. The bus may also connect various other circuits, such as timing sources, peripherals, voltage regulators, power management circuits, and the like, which are well known in the art and therefore will not be described in more detail.
The processor may be responsible for managing the bus and general processing, including running software stored on machine-readable media. The processor may be implemented with one or more general-purpose and/or special-purpose processors. Examples include microprocessors, microcontrollers, DSP processors, and other circuitry that can run software. Software will be interpreted broadly to mean instructions, data, or any combination thereof, whether referred to as software, firmware, middleware, microcode, hardware description language, or otherwise. Machine readable media may include, by way of example, RAM (Random Access Memory), flash memory, ROM (Read Exclusive Memory), PROM (Programmable Read Exclusive Memory, EPROM (Erasable Programmable Read Exclusive Memory), EEPROM (Electrically Erasable Programmable Read Only Memory), recorders, magnetic disks, optical disks, hard drives or any other suitable storage medium or any combination thereof. Machine-readable media may be embodied in a computer program product. computer program product may comprise packaging materials.
In a hardware implementation, the machine-readable media may be part of the processing system separate from the processor. However, as will be readily understood by those skilled in the art, the machine readable media, or any portion thereof, may be external to the processing system. By way of example, the machine-readable media may include a transmission line, a data-modulated carrier wave, and/or a computer product separate from the wireless node, all of which may be accessed by the processor through the bus interface. Alternatively, or in addition, the machine-readable media, or any part thereof, may be integrated into the processor, as is the case with cache and/or general log files.
The processing system may be configured as a general-purpose processing system with one or more microprocessors that provide the processor functionality and an external memory that provides at least a portion of the machine-readable media, all connected together with other processing circuitry. support through an external bus architecture. Alternatively, the processing system may be implemented with an ASIC (Application-Specific Integrated Circuit) with the processor, the bus interface, the user interface in the case of an access terminal, supporting circuitry and at least a portion of the media. machine-readable integrated into a single chip or with FPGAs (Field Programmable Gate Arrays), PLDs (Programmable Logic Devices), controllers, state machines, gate-connected logic, discrete hardware components or any other suitable circuitry or any combination of circuits that can perform the various functionalities described throughout this description. Those skilled in the art will recognize how best to implement the described functionality for the processing system depending on the specific application and overall design constraints imposed on the system as a whole.
The machine readable media may comprise multiple software modules. Software modules include instructions that, when executed by the processor, cause the processing system to perform various functions. Software modules may include a transmit module and a receive module. Each software module can reside on a single storage device or be distributed across multiple storage devices. As an example, a software module can be loaded into the RAM of a hard drive when a trigger event occurs. During the execution of the software module, the processor may load some of the instructions in cache in order to increase the access speed. One or more cache lines can then be loaded into a general log file for execution by the processor. When reference is made to functionality of a software module below, it should be understood that such functionality is implemented by the processor when executing instructions for that software module.
If implemented in software, functions can be stored in or transmitted through one or more instructions or code on a computer-readable medium. Computer readable media include both computer storage media and communication media that include any medium that facilitates the transfer of a computer program from one place to another. A storage medium can be any available medium that can be accessed by a general-purpose or special-purpose computer. By way of example, and not limitation, such computer readable medium may comprise RAM, ROM, EEPROM, CD-ROM or any other optical disc storage, magnetic disk storage or other magnetic storage devices or any other medium which may be used to carry or store desired program code in the form of instructions or data structures that can be accessed by a computer. Furthermore, any connection is aptly termed a computer-readable medium. For example, if the software is transmitted from a network site, server, or other remote source using coaxial cable, fiber optic cable, twisted pair, digital subscriber line (DSL), or wireless technologies such as infrared, radio and microwave, then coaxial cable, fiber optic cable, twisted pair, DSL or wireless technologies such as infrared, radio and microwave are included in the definition of medium. The term disc (disk and disc), as used herein, includes compact disc (CD), laser disc, optical disc, digital versatile disc (DVD), floppy disc and blu-ray disc, on which discs (disks) usually play magnetically, while discs (discs) reproduce data optically with lasers. Thus, in some respects computer-readable media may comprise non-transient computer-readable media (tangible media, for example). Furthermore, for other aspects the computer readable media may comprise transient computer readable media (a signal, for example). Combinations of these must also be included within the range of computer readable media.
Thus, certain aspects may comprise a computer program product to perform the operations presented herein. For example, such a computer program product may comprise a computer-readable medium that has instructions stored (and/or encoded) therein, the instructions being executable by one or more processors to perform the operations described herein. For certain aspects, the computer program product may include packaging material.
In addition, it should be understood that modules and/or other mechanisms suitable for executing the methods and techniques described herein may be downloaded and/or otherwise obtained by a user terminal and/or base station, as applicable. For example, such a device may be coupled to a server to facilitate the transfer of mechanisms to perform the methods described herein. Alternatively, various methods described herein may be provided by means of storage mechanisms (e.g. RAM, ROM, a physical storage medium such as a compact disk (CD) or floppy disk, etc.) user and/or a base station can obtain the various methods by coupling or providing storage mechanisms for the device. Furthermore, any other suitable technique can be used to provide the methods and techniques described herein for a device.
It is also to be understood that the claims are not limited to the configuration and precise components shown above. Various modifications, alterations and variations may be made in the arrangement, operation and details of the methods and apparatus described above without departing from the scope of the claims.

权利要求:
Claims (15)
[0001]
1. Method for wireless communication, characterized in that it comprises: simultaneously transmitting from a first apparatus a first plurality of downlink multi-input multiple-output multi-output packets (DL-MU-MIMO) to a plurality of second apparatuses in a first transmission (502); determining in the first apparatus that at least one of a plurality of acknowledgments corresponding to the first plurality of packets has not been received and at least one of the plurality of acknowledgments corresponding to the first plurality of packets has been received from at least one of the plurality of second apparatuses (504); and in the first apparatus increase a containment window (CW) by a setback counter based on determination (506).
[0002]
2. Method, according to claim 1, characterized in that it also comprises: initializing the setback counter, wherein the setback counter comprises a random number between 0 and a value of CW; counting down the setback counter; and in response to the countdown timer reaching the end of the countdown, simultaneously transmitting a second plurality of packets in a second transmission.
[0003]
3. Method according to claim 1, characterized in that it also comprises incrementing a recoil counter based on the determination, wherein increasing the CW comprises calculating the CW based on the recoil counter.
[0004]
4. Method according to claim 1, characterized in that determining that at least one of the plurality of acknowledgments has not been received comprises determining that a first acknowledgment of the plurality of acknowledgments expected to be first received in time has not been received.
[0005]
5. Method according to claim 1, characterized in that it also comprises: providing a plurality of setback counters, a setback counter for each of the plurality of second apparatuses; for each of the plurality of backoff counters: incrementing the backoff counter for a specific apparatus among the second apparatuses in response to failure to receive one of the plurality of acknowledgments corresponding to the specific apparatus among the second apparatuses; and resetting the backoff counter for a specific apparatus of the second apparatus in response to receipt of one of the plurality of acknowledgments corresponding to a specific apparatus of the second apparatus.
[0006]
6. Method according to claim 1, characterized in that the CW is a function of a class used in the first transmission.
[0007]
7. Method according to claim 1, characterized in that the plurality of acknowledgments comprises a plurality of valid block acknowledgments (BAs).
[0008]
8. Method, according to claim 7, characterized in that each one of the valid BAs comprises a block confirmation (BA) associated with a class used in the first transmission; and/or wherein each of the valid BAs comprises an affirmative acknowledgment of at least one medium access control protocol (MAC) data unit (MPDU) in a corresponding packet from among the first plurality of packets.
[0009]
Method according to claim 1, characterized in that the first plurality of packets comprises a packet associated with an access category selected from a plurality of access categories, wherein determining comprises determining that an acknowledgment corresponding to the packet has not been received from a designated second apparatus from among the plurality of second apparatuses, wherein the designated second apparatus is associated with the selected access category, and wherein increasing comprises increasing the CW for the backoff counter associated with the selected access category , based on the determination.
[0010]
10. Method, according to claim 9, characterized in that each one of the packets in the first plurality of packets is associated with one of the access categories; and/or wherein the packet comprises a head-of-line (HOL) packet from a packet queue associated with the selected access category.
[0011]
11. Method, according to claim 9, characterized in that it also comprises: initializing the setback counter, wherein the setback counter comprises a random number between 0 and a value of CW; counting down the setback counter; and in response to the backcounter reaching the end of the countdown, simultaneously transmitting a second plurality of packets in a second transmission, wherein the second plurality of packets comprises the packet associated with the selected access category.
[0012]
12. Method according to claim 11, characterized in that it also comprises: determining that another acknowledgment corresponding to the packet transmitted in the second plurality of packets has been received from the second designated apparatus; ereset the CW for the setback counter associated with the selected access category, based on the determination.
[0013]
13. Method according to claim 9, characterized in that the packet associated with the selected access category is retransmitted until the acknowledgment corresponding to the packet is received from the second designated device, up to a maximum retransmission limit; and/or where the access category is selected in accordance with the Institute of Electrical and Electronics Engineers (IEEE) 802.11n Enhanced Distributed Channel Access (EDCA) rules.
[0014]
14. Apparatus for wireless communication (110, 302), characterized in that it comprises: mechanisms for simultaneously transmitting (310) a first plurality of downlink multi-input multi-output multi-output packets (DL-MU- MIMO) to a plurality of second apparatuses (120, 302) in a first transmission; mechanisms for determining (312, 304, 306, 318, 320) that at least one of a plurality of acknowledgments corresponding to the first plurality of packets has not been received and at least one of the plurality of acknowledgments corresponding to the first plurality of packets has been received from at least one of the plurality of second apparatuses; mechanisms to increase (304, 306, 329) a contention window (CW) for a backoff counter based on determination.
[0015]
15. Computer readable memory characterized in that it comprises instructions stored therein, the instructions being executable by a computer to perform the method steps as defined in any one of claims 1 to 13.

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法律状态:
2020-09-01| B15K| Others concerning applications: alteration of classification|Free format text: A CLASSIFICACAO ANTERIOR ERA: H04W 74/08 Ipc: H04B 7/0452 (2017.01), H04L 1/18 (2006.01), H04W 8 |

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2020-09-01| B06U| Preliminary requirement: requests with searches performed by other patent offices: procedure suspended [chapter 6.21 patent gazette]|

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2021-11-09| B09A| Decision: intention to grant [chapter 9.1 patent gazette]|

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2021-11-23| B350| Update of information on the portal [chapter 15.35 patent gazette]|

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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 05/05/2011, OBSERVADAS AS CONDICOES LEGAIS. PATENTE CONCEDIDA CONFORME ADI 5.529/DF, QUE DETERMINA A ALTERACAO DO PRAZO DE CONCESSAO. |

优先权:

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申请号 | 申请日 | 专利标题

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US33163110P| true| 2010-05-05|2010-05-05|

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US61/331,631|2010-05-05|

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