Classifications

• • H—ELECTRICITY
  • H04—ELECTRIC COMMUNICATION TECHNIQUE
  • H04W—WIRELESS COMMUNICATION NETWORKS
  • H04W74/00—Wireless channel access
  • H04W74/04—Scheduled access
• • H—ELECTRICITY
  • H04—ELECTRIC COMMUNICATION TECHNIQUE
  • H04W—WIRELESS COMMUNICATION NETWORKS
  • H04W72/00—Local resource management
  • H04W72/04—Wireless resource allocation
  • H04W72/044—Wireless resource allocation based on the type of the allocated resource
  • H04W72/0446—Resources in time domain, e.g. slots or frames
• • H—ELECTRICITY
  • H04—ELECTRIC COMMUNICATION TECHNIQUE
  • H04W—WIRELESS COMMUNICATION NETWORKS
  • H04W74/00—Wireless channel access
  • H04W74/002—Transmission of channel access control information
• • H—ELECTRICITY
  • H04—ELECTRIC COMMUNICATION TECHNIQUE
  • H04W—WIRELESS COMMUNICATION NETWORKS
  • H04W74/00—Wireless channel access
  • H04W74/08—Non-scheduled access, e.g. ALOHA
  • H04W74/0833—Random access procedures, e.g. with 4-step access
  • H04W74/0841—Random access procedures, e.g. with 4-step access with collision treatment
  • H04W74/085—Random access procedures, e.g. with 4-step access with collision treatment collision avoidance
• • H—ELECTRICITY
  • H04—ELECTRIC COMMUNICATION TECHNIQUE
  • H04W—WIRELESS COMMUNICATION NETWORKS
  • H04W76/00—Connection management
  • H04W76/10—Connection setup
  • H04W76/14—Direct-mode setup
• • H—ELECTRICITY
  • H04—ELECTRIC COMMUNICATION TECHNIQUE
  • H04W—WIRELESS COMMUNICATION NETWORKS
  • H04W72/00—Local resource management
  • H04W72/50—Allocation or scheduling criteria for wireless resources
  • H04W72/52—Allocation or scheduling criteria for wireless resources based on load
• • H—ELECTRICITY
  • H04—ELECTRIC COMMUNICATION TECHNIQUE
  • H04W—WIRELESS COMMUNICATION NETWORKS
  • H04W84/00—Network topologies
  • H04W84/18—Self-organising networks, e.g. ad-hoc networks or sensor networks

Definitions

• Certain aspects of the present disclosure generally relate to wireless communications and, more particularly, to transmit opportunity scheduling in uplink spatial division multiple access (SDMA).
• SDMA uplink spatial division multiple access
• MIMO Multiple Input or Multiple Output
• IEEE 802.11 denotes a set of Wireless Local Area Network (WLAN) air interface standards developed by the IEEE 802.11 committee for short-range communications, for example, tens of meters to a few hundred meters.
• WLAN Wireless Local Area Network
• a MIMO wireless system employs a number (NT) of transmit antennas and a number (NR) of receive antennas for data transmission.
• the N ⁇ spatial streams may be used to transmit N ⁇ independent data streams to achieve greater overall throughput.
• Certain aspects of the present disclosure provide a method for wireless communications.
• the method generally includes receiving, from one or more apparatuses, one or more request messages for a transmission slot for a spatial division multiple access (SDMA) transmission, and transmitting a transmit opportunity (TXOP) start frame to one or more of the apparatuses to indicate start of a SDMA TXOP.
• SDMA spatial division multiple access
• TXOP transmit opportunity
• Certain aspects of the present disclosure provide a method for wireless communications.
• the method generally includes transmitting a request message for a transmission slot for a spatial division multiple access (SDMA) transmission, receiving a transmit opportunity (TXOP) start frame comprising an indication of start of a SDMA transmission, and transmitting SDMA data during a TXOP in accordance with the TXOP start frame.
• SDMA spatial division multiple access
• TXOP transmit opportunity
• the apparatus generally includes a receiver configured to receive, from one or more apparatuses, one or more request messages for a transmission slot for a spatial division multiple access (SDMA) transmission, and a transmitter configured to transmit a transmit opportunity (TXOP) start frame to one or more of the apparatuses to indicate start of a SDMA TXOP.
• SDMA spatial division multiple access
• TXOP transmit opportunity
• the apparatus generally includes a transmitter configured to transmit a request message for a transmission slot for a spatial division multiple access (SDMA) transmission, a receiver configured to receive a transmit opportunity (TXOP) start frame comprising an indication of start of a SDMA transmission, and wherein the transmitter is further configured to transmit SDMA data during a TXOP in accordance with the TXOP start frame.
• SDMA spatial division multiple access
• TXOP transmit opportunity
• the apparatus generally includes means for receiving, from one or more apparatuses, one or more request messages for a transmission slot for a spatial division multiple access (SDMA) transmission, and means for transmitting a transmit opportunity (TXOP) start frame to one or more of the apparatuses to indicate start of a SDMA TXOP.
• SDMA spatial division multiple access
• TXOP transmit opportunity
• the apparatus generally includes means for transmitting a request message for a transmission slot for a spatial division multiple access (SDMA) transmission, means for receiving a transmit opportunity (TXOP) start frame comprising an indication of start of a SDMA transmission, and wherein the means for transmitting further comprises means for transmitting SDMA data during a TXOP in accordance with the TXOP start frame.
• SDMA spatial division multiple access
• TXOP transmit opportunity
• Certain aspects of the present disclosure provide a computer-program product for wireless communications, comprising a computer-readable medium comprising instructions.
• the instructions executable for receiving, from one or more apparatuses, one or more request messages for a transmission slot for a spatial division multiple access (SDMA) transmission, and transmitting a transmit opportunity (TXOP) start frame to one or more of the apparatuses to indicate start of a SDMA TXOP.
• SDMA spatial division multiple access
• TXOP transmit opportunity
• Certain aspects of the present disclosure provide a computer-program product for wireless communications, comprising a computer-readable medium comprising instructions.
• the instructions executable for transmitting a request message for a transmission slot for a spatial division multiple access (SDMA) transmission, receiving a transmit opportunity (TXOP) start frame comprising an indication of start of a SDMA transmission, and transmitting SDMA data during a TXOP in accordance with the TXOP start frame.
• SDMA spatial division multiple access
• TXOP transmit opportunity
• the access point generally includes a plurality of antennas, a receiver configured to receive, via the plurality of antennas, from one or more apparatuses, one or more request messages for a transmission slot for a spatial division multiple access (SDMA) transmission, and a transmitter configured to transmit a transmit opportunity (TXOP) start frame to one or more of the apparatuses to indicate start of a SDMA TXOP.
• SDMA spatial division multiple access
• TXOP transmit opportunity
• the station generally includes at least one antenna, a transmitter configured to transmit, via the at least one antenna, a request message for a transmission slot for a spatial division multiple access (SDMA) transmission, a receiver configured to receive a transmit opportunity (TXOP) start frame comprising an indication of start of a SDMA transmission, and wherein the transmitter is further configured to transmit SDMA data during a TXOP in accordance with the TXOP start frame.
• SDMA spatial division multiple access
• TXOP transmit opportunity
• Certain aspects provide a method of wireless communication, performed by a access point (AP).
• the method generally includes transmitting, to one or more apparatuses, an indication of a threshold duration for single -user (SU) transmissions, receiving, from at least one of the one or more apparatuses having data with a corresponding transmission time greater than the indicated threshold duration for SU transmissions, a request message for a transmission slot for a spatial division multiple access (SDMA) transmission for transmitting the data, and transmitting a transmit opportunity (TXOP) start frame to the at least one apparatus to indicate start of a SDMA TXOP.
• SU single -user
• SDMA spatial division multiple access
• TXOP transmit opportunity
• Certain aspects provide a method of wireless communication, performed by a station (STA).
• the method generally includes receiving, from an access point, an indication of a threshold duration for single -user (SU) transmissions, determining a transmission time of data will exceed the threshold duration for SU transmissions, and transmitting a request message for a transmission slot for a spatial division multiple access (SDMA) transmission, in response to the determination.
• SU single -user
• SDMA spatial division multiple access
• the apparatus generally includes means for transmitting, to one or more apparatuses, an indication of a threshold duration for single-user (SU) transmissions, means for receiving, from at least one of the one or more apparatuses having data with a corresponding transmission time greater than the indicated threshold duration for SU transmissions, a request message for a transmission slot for a spatial division multiple access (SDMA) transmission for transmitting the data, and means for transmitting a transmit opportunity (TXOP) start frame to the at least one apparatus to indicate start of a SDMA TXOP.
• SU single-user
• SDMA spatial division multiple access
• the apparatus generally includes means for receiving, from an access point, an indication of a threshold duration for single-user (SU) transmissions, means for determining a transmission time of data will exceed the threshold duration for SU transmissions, and means for transmitting a request message for a transmission slot for a spatial division multiple access (SDMA) transmission, in response to the determination.
• SU single-user
• SDMA spatial division multiple access
• the apparatus generally includes a transmitter for transmitting, to one or more apparatuses, an indication of a threshold duration for single-user (SU) transmissions and a receiver for receiving, from at least one of the one or more apparatuses having data with a corresponding transmission time greater than the indicated threshold duration for SU transmissions, a request message for a transmission slot for a spatial division multiple access (SDMA) transmission for transmitting the data, wherein the transmitter is also for transmitting a transmit opportunity (TXOP) start frame to the at least one apparatus to indicate start of a SDMA TXOP.
• SU single-user
• SDMA spatial division multiple access
• the apparatus generally includes a receiver for receiving, from an access point, an indication of a threshold duration for single-user (SU) transmissions, a processing system for determining a transmission time of data will exceed the threshold duration for SU transmissions, and a transmitter for transmitting a request message for a transmission slot for a spatial division multiple access (SDMA) transmission, in response to the determination.
• SU single-user
• SDMA spatial division multiple access
• Certain aspects provide a computer-program product for wireless communications, comprising a computer-readable medium.
• the computer-readable medium generally includes instructions executable for transmitting, to one or more apparatuses, an indication of a threshold duration for single -user (SU) transmissions, receiving, from at least one of the one or more apparatuses having data with a corresponding transmission time greater than the indicated threshold duration for SU transmissions, a request message for a transmission slot for a spatial division multiple access (SDMA) transmission for transmitting the data, and transmitting a transmit opportunity (TXOP) start frame to the at least one apparatus to indicate start of a SDMA TXOP.
• SU single -user
• SDMA spatial division multiple access
• TXOP transmit opportunity
• Certain aspects provide a computer-program product for wireless communications, comprising a computer-readable medium.
• the computer-readable medium generally includes instructions executable for receiving, from an access point, an indication of a threshold duration for single -user (SU) transmissions, determining a transmission time of data will exceed the threshold duration for SU transmissions, and transmitting a request message for a transmission slot for a spatial division multiple access (SDMA) transmission, in response to the determination.
• SU single -user
• SDMA spatial division multiple access
• FIG. 1 illustrates a diagram of a wireless communications network in accordance with certain aspects of the present disclosure.
• FIG. 2 illustrates a block diagram of an example access point and user terminals in accordance with certain aspects of the present disclosure.
• FIG. 3 illustrates a block diagram of an example wireless device in accordance with certain aspects of the present disclosure.
• FIG. 4 illustrates an example network consisting of an access point and a plurality of stations, in accordance with certain aspects of the present disclosure.
• FIG. 5 illustrates message exchange between an access point and two stations utilizing enhanced distributed channel access (EDCA) procedure.
• EDCA enhanced distributed channel access
• FIG. 6 illustrates message exchange between an access point and two stations utilizing uplink SDMA procedure, in accordance with certain aspects of the present disclosure.
• FIG. 7 illustrates a comparison between an EDCA protocol and a proposed uplink SDMA protocol, in accordance with certain aspects of the present disclosure.
• FIG. 8 illustrates example operations for performing uplink spatial division multiple access (SDMA) that may be employed by an access point, in accordance with certain aspects of the present disclosure.
• SDMA uplink spatial division multiple access
• FIG. 8A illustrates example components capable of performing the operations shown in FIG. 8.
• FIG. 9 illustrates example operations for performing uplink SDMA that may be employed by a station, in accordance with certain aspects of the present disclosure.
• FIG. 9A illustrates example components capable of performing the operations shown in FIG. 9.
• FIG. 10 illustrates example operations for wireless communications, in accordance with certain aspects of the present disclosure.
• legacy stations generally refers to wireless network nodes that support IEEE 802.11 ⁇ or earlier versions of the IEEE 802.11 standard.
• the multi-antenna transmission techniques described herein may be used in combination with various wireless technologies such as Code Division Multiple Access (CDMA), Orthogonal Frequency Division Multiplexing (OFDM), Time Division Multiple Access (TDMA), Spatial Division Multiple Access (SDMA), and so on.
• Multiple user terminals can concurrently transmit/receive data via different (1) orthogonal code channels for CDMA, (2) time slots for TDMA, or (3) sub-bands for OFDM.
• a CDMA system may implement IS-2000, IS-95, IS-856, Wideband-CDMA (W-CDMA), or some other standards.
• An OFDM system may implement IEEE 802.11 or some other standards.
• a TDMA system may implement Global System for Mobile communications (GSM) or some other standards. These various standards are known in the art.
• FIG. 1 illustrates a multiple-access MIMO system 100 with access points and user terminals.
• An access point is generally a fixed station that communicates with the user terminals and may also be referred to as a base station, a Node B, an evolved Node B (eNB) or some other terminology.
• a user terminal may be fixed or mobile and may also be referred to as a mobile station, a station (STA), a client, a wireless device, or some other terminology.
• a user terminal may be a wireless device, such as a cellular phone, a personal digital assistant (PDA), a handheld device, a wireless modem, a laptop computer, a personal computer, etc.
• PDA personal digital assistant
• Access point 110 may communicate with one or more user terminals 120 at any given moment on the downlink and uplink.
• the downlink i.e., forward link
• the uplink i.e., reverse link
• a user terminal may also communicate peer-to-peer with another user terminal.
• a system controller 130 couples to and provides coordination and control for the access points.
• System 100 employs multiple transmit and multiple receive antennas for data transmission on the downlink and uplink.
• Access point 110 is equipped with a number N ap of antennas and represents the multiple-input (MI) for downlink transmissions and the multiple-output (MO) for uplink transmissions.
• a set N u of selected user terminals 120 collectively represents the multiple-output for downlink transmissions and the multiple-input for uplink transmissions.
• N ap ⁇ N «> 1 if the data symbol streams for the N u user terminals are not multiplexed in code, frequency, or time by some means.
• N u may be greater than N ap if the data symbol streams can be multiplexed using different code channels with CDMA, disjoint sets of sub-bands with OFDM, and so on.
• Each selected user terminal transmits user-specific data to and/or receives user-specific data from the access point.
• each selected user terminal may be equipped with one or multiple antennas (i.e., N ut > 1).
• the N u selected user terminals can have the same or different number of antennas.
• MIMO system 100 may be a time division duplex (TDD) system or a frequency division duplex (FDD) system.
• TDD time division duplex
• FDD frequency division duplex
• the downlink and uplink share the same frequency band.
• the downlink and uplink use different frequency bands.
• MIMO system 100 may also utilize a single carrier or multiple carriers for transmission.
• Each user terminal may be equipped with a single antenna (e.g., in order to keep costs down) or multiple antennas (e.g., where the additional cost can be supported).
• FIG. 2 shows a block diagram of access point 110 and two user terminals 120m and 120x in MIMO system 100.
• Access point 110 is equipped with N ap antennas 224a through 224ap.
• User terminal 120m is equipped with N m antennas 252ma through 252mu, and user terminal 120x is equipped with N x antennas 252xa through 252xu.
• Access point 110 is a transmitting entity for the downlink and a receiving entity for the uplink.
• Each user terminal 120 is a transmitting entity for the uplink and a receiving entity for the downlink.
• a “transmitting entity” is an independently operated apparatus or device capable of transmitting data via a frequency channel
• a “receiving entity” is an independently operated apparatus or device capable of receiving data via a frequency channel.
• the subscript "dn” denotes the downlink
• the subscript "up” denotes the uplink
• N up user terminals are selected for simultaneous transmission on the uplink
• N d n user terminals are selected for simultaneous transmission on the downlink
• N up may or may not be equal to N d n
• N up and N d n may be static values or can change for each scheduling interval.
• the beam-steering or some other spatial processing technique may be used at the access point and user terminal.
• a TX data processor 288 receives traffic data from a data source 286 and control data from a controller 280.
• the controller 280 may also be attached to a memory 282.
• TX data processor 288 processes (e.g., encodes, interleaves, and modulates) the traffic data ⁇ dup.m ⁇ for the user terminal based on the coding and modulation schemes associated with the rate selected for the user terminal and provides a data symbol stream ⁇ s uP tn ⁇ .
• a TX spatial processor 290 performs spatial processing on the data symbol stream ⁇ s uPtm ⁇ and provides N ut,m transmit symbol streams for the N m antennas.
• Each transmitter unit (TMTR) 254 receives and processes (e.g., converts to analog, amplifies, filters, and frequency upconverts) a respective transmit symbol stream to generate an uplink signal.
• N m transmitter units 254 provide N m uplink signals for transmission from N m antennas 252 to the access point 110.
• a number N up of user terminals may be scheduled for simultaneous transmission on the uplink.
• Each of these user terminals performs spatial processing on its data symbol stream and transmits its set of transmit symbol streams on the uplink to the access point.
• N ap antennas 224a through 224ap receive the uplink signals from all N up user terminals transmitting on the uplink.
• Each antenna 224 provides a received signal to a respective receiver unit (RCVR) 222.
• Each receiver unit 222 performs processing complementary to that performed by transmitter unit 254 and provides a received symbol stream.
• An RX spatial processor 240 performs receiver spatial processing on the N ap received symbol streams from N ap receiver units 222 and provides N up recovered uplink data symbol streams.
• the receiver spatial processing is performed in accordance with the channel correlation matrix inversion (CCMI), minimum mean square error (MMSE), successive interference cancellation (SIC), or some other technique.
• CCMI channel correlation matrix inversion
• MMSE minimum mean square error
• SIC successive interference cancellation
• Each recovered uplink data symbol stream ⁇ s uPtm ⁇ is an estimate of a data symbol stream ⁇ s uPtm ⁇ transmitted by a respective user terminal.
• An RX data processor 242 processes (e.g., demodulates, deinterleaves, and decodes) each recovered uplink data symbol stream ⁇ s uPtm ⁇ in accordance with the rate used for that stream to obtain decoded data.
• the decoded data for each user terminal may be provided to a data sink 244 for storage and/or a controller 230 for further processing.
• the controller 230 may also be attached to a memory 232.
• a TX data processor 210 receives traffic data from a data source 208 for N dn user terminals scheduled for downlink transmission, control data from a controller 230, and possibly other data from a scheduler 234. The various types of data may be sent on different transport channels. TX data processor 210 processes (e.g., encodes, interleaves, and modulates) the traffic data for each user terminal based on the rate selected for that user terminal. TX data processor 210 provides Ndn downlink data symbol streams for the Ndn user terminals. A TX spatial processor 220 performs spatial processing on the Ndn downlink data symbol streams, and provides N ap transmit symbol streams for the N ap antennas. Each transmitter unit (TMTR) 222 receives and processes a respective transmit symbol stream to generate a downlink signal. N ap transmitter units 222 provide N ap downlink signals for transmission from N ap antennas 224 to the user terminals.
• TMTR transmitter unit
• N m antennas 252 receive the N ap downlink signals from access point 110.
• Each receiver unit (RCVR) 254 processes a received signal from an associated antenna 252 and provides a received symbol stream.
• An RX spatial processor 260 performs receiver spatial processing on N m received symbol streams from N m receiver units 254 and provides a recovered downlink data symbol stream ⁇ 3 ⁇ 4n,m ⁇ for the user terminal. The receiver spatial processing is performed in accordance with the CCMI, MMSE, or some other technique.
• An RX data processor 270 processes (e.g., demodulates, deinterleaves, and decodes) the recovered downlink data symbol stream to obtain decoded data for the user terminal.
• FIG. 3 illustrates various components that may be utilized in a wireless device 302 that may be employed within the system 100.
• the wireless device 302 is an example of a device that may be configured to implement the various methods described herein.
• the wireless device 302 may be an access point 110 or a user terminal 120.
• the wireless device 302 may include a processor 304 which controls operation of the wireless device 302.
• the 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 to the processor 304.
• a portion of the memory 306 may also include non-volatile random access memory (NVRAM).
• the processor 304 typically performs logical and arithmetic operations based on program instructions stored within the memory 306.
• the instructions in the memory 306 may be executable to implement the methods described herein.
• the wireless device 302 may also include a housing 308 that may include a transmitter 310 and a receiver 312 to allow transmission and reception of data between the wireless device 302 and a remote location.
• the transmitter 310 and receiver 312 may be combined into a transceiver 314.
• a plurality of transmit antennas 316 may be attached to the housing 308 and electrically coupled to the transceiver 314.
• the wireless device 302 may also include (not shown) multiple transmitters, multiple receivers, and multiple transceivers.
• the wireless device 302 may also include a signal detector 318 that may be used in an effort to detect and quantify the level of signals received by the transceiver 314.
• the signal detector 318 may detect such signals as total energy, energy per subcarrier per symbol, power spectral density and other signals.
• the wireless device 302 may also include a digital signal processor (DSP) 320 for use in processing signals.
• DSP digital signal processor
• 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 status signal bus in addition to a data bus.
• a bus system 322 may include a power bus, a control signal bus, and a status signal bus in addition to a data bus.
• Those skilled in the art will recognize the techniques described herein may be generally applied in systems utilizing any type of multiple access schemes, such as SDMA, OFDMA, CDMA, SDMA, and combinations thereof.
• MAC medium access control
• uplink SDMA may also be referred to as uplink multi-user multiple-input multiple-output (MU-MIMO), uplink OFDMA, or more generally, as uplink MU.
• An access point may receive one or more requests for uplink SDMA transmission from a plurality of stations. The access point may schedule the transmissions and send a message to the stations. The message may include parameters of the uplink SDMA transmissions such as starting time, duration of the transmission, spatial streams assigned to each station, and so on.
• FIG. 4 illustrates an example network consisting of an access point and a plurality of stations, in accordance with certain aspects of the present disclosure.
• two or more of the STAs 404 may transmit data to the access point 402 simultaneously.
• a Request to Send (RTS) / Clear to Send (CTS) procedure may be used to reserve a portion of a wireless medium for a pending data transmission.
• RTS Request to Send
• CTS Clear to Send
• one or more uplink transmissions i.e., transmit opportunities (TXOP)
• TXOP transmit opportunities
• a plurality of stations may transmit to an access point simultaneously.
• Each STA may use different spatial streams.
• the AP may schedule uplink SDMA transmissions of different stations and assign one or more spatial streams to each of the stations through a TXOP Start (TXS) frame.
• TXS TXOP Start
• an AP may enable uplink SDMA at selected STAs and for selected Access Categories (ACs) within those STAs.
• An Access Category is an equivalent of a frame queue that contends for medium access independent of the other ACs inside an STA.
• a STA may have four internal ACs.
• Contention access may be based on Enhanced Distributed Channel Access (EDCA) (i.e., the IEEE 802. lie standard).
• EDCA Enhanced Distributed Channel Access
• the EDCA supports differentiated and distributed access to the wireless medium supporting different access categories such as voice, video, best effort and background.
• FIG. 5 illustrates message exchange between an access point and two stations utilizing EDCA procedure.
• STA1 may send an RTS message 502 to the AP.
• the AP may send a CTS message 504 in response to the RTS.
• STA1 may then transmit its data in TXOP STA1 506.
• the access point may acknowledge reception of the data from STA1 by transmitting a block acknowledgement (BA) message 508.
• BA block acknowledgement
• STA2 may monitor the wireless medium.
• STA2 may transmit an RTS message to the AP to request access to the wireless medium.
• the AP may also transmit a CTS message and receive transmissions from STA2.
• FIG. 6 illustrates message exchange between an access point and two stations utilizing uplink SDMA procedure, in accordance with certain aspects of the present disclosure.
• the stations are capable of uplink SDMA transmission and uplink SDMA is enabled.
• An STA may send a TXOP Request (TXR) 602 to the AP instead of sending an RTS 502 (FIG. 5).
• TXR is sent when an AC in the STA, that is capable of performing uplink SDMA, gains access to the wireless medium.
• the TXR 602 may also specify which AC has gained access to the medium (e.g., a back-off timer for the AC has reached zero or expired).
• the AP may start an uplink SDMA TXOP 608 by sending a TXOP Start (TXS) 606 frame to the stations when it received a sufficient number of TXR frames.
• the TXS frame may specify STA Identifiers (IDs) for the STAs that are included in the uplink SDMA TXOP 608, the spatial streams that are assigned to each of the STAs, and the duration of the uplink SDMA TXOP.
• the TXS frame may also set a network allocation vector (NAV) for the duration of the uplink SDMA TXOP 608.
• the NAV may cause other stations that are not participating in uplink SDMA transmissions, to hold off on their transmissions until the uplink SDMA duration is finished.
• the access point may transmit one or more acknowledgement frames 612 to the STAs to acknowledge reception of the one or more SDMA transmissions.
• the AP may start an uplink SDMA TXOP when a time threshold value is exceeded after receiving a TXR from a STA without receiving additional TXR frames from other STAs.
• a plurality of STAs may transmit data using the spatial streams that are assigned to them in the TXS frame.
• the transmissions may contain one or more MAC Service Data Units (MSDUs) that are aggregated using Aggregated MSDU (A-MSDU) and one or more MAC Protocol Data Units (MPDUs) that are aggregated using Aggregated MPDU (A-MPDU), or both.
• MSDUs MAC Service Data Units
• MPDUs MAC Protocol Data Units
• the MPDUs in the uplink SDMA transmission may indicate an acknowledgement (ACK) policy that does not require an immediate response by the AP.
• ACK acknowledgement
• a Block ACK acknowledgement policy may be used on the uplink transmissions instead of an implicit Block Acknowledgement Request (BAR) acknowledgement policy that is normally used.
• the uplink transmissions may include a BAR frame, that may request the AP to send a Block Acknowledgement (BA) 612 frame in the next available TXOP for the AP.
• BA Block Acknowledgement
• the AP may send the requested BA frames.
• the AP may send the BA frames for one or more stations sequentially.
• the AP may send a first BA frame 612 for a first station when a Short Inter-frame Space (SIFS) time is passed after the end of the uplink SDMA TXOP 608.
• the AP may send a second BA frame for the second station when a SIFS time is passed after the end of transmission of the first BA.
• SIFS Short Inter-frame Space
• FIG. 7 illustrates a comparison between a regular enhanced distributed channel access (EDCA) and a proposed uplink SDMA protocol, in accordance with certain aspects of the present disclosure.
• the top portion of the figure illustrates packet exchange between an access point and two stations using EDCA procedure, when the stations do not have the ability to perform uplink SDMA.
• the lower portion of the figure illustrates packet exchange between the access point and two stations using uplink SDMA.
• the time taken for the communication between the AP and a plurality of stations is much smaller in the system utilizing uplink SDMA than the system utilizing the EDCA procedure.
• FIG. 8 illustrates example operations 800 for performing uplink SDMA that may be employed by an access point, in accordance with certain aspects of the present disclosure.
• one or more request messages for a transmission slot for a spatial division multiple access (SDMA) transmission may be received from one or more apparatuses (e.g., stations).
• the access point may transmit a transmit opportunity (TXOP) start frame to one or more of the apparatuses to indicate start of an SDMA TXOP.
• TXOP transmit opportunity
• the access point may determine amount of resource requested by the apparatuses that sent the request messages. If the amount of resource is greater than or equal to a threshold value, the AP may transmit the TXOP start frame.
• the access point may receive one or more SDMA transmissions from the apparatuses according to the TXOP start frame. At least one of the SDMA transmissions may indicate an acknowledgement policy that does not require immediate transmission of an acknowledgement frame.
• FIG. 9 illustrates example operations 900 for performing uplink SDMA that may be employed by a station, in accordance with certain aspects of the present disclosure.
• a request message for a transmission slot for a spatial division multiple access (SDMA) transmission is transmitted to an apparatus.
• a TXS frame is received from the apparatus comprising an indication of start of a SDMA transmission.
• SDMA data is transmitted during the TXOP in accordance with the TXOP start frame.
• the station may transmit the SDMA data on one or more spatial streams utilizing an assigned duration for the TXOP, wherein the spatial streams and the assigned duration are received in the TXOP start frame
• the uplink transmissions may not include a BAR frame, and the STAs may send a BAR frame separately after the end of the uplink SDMA TXOP, using EDCA contention.
• the advantage of this method is that the STA can set a NAV locally through the BAR frame to clear the medium for the duration of the BA reception.
• the AP may provide the STAs with fixed back-off timer values that they may use for this purpose.
• the AP may disable uplink SDMA for the stations so that the stations use normal EDCA operations.
• Uplink SDMA may also be referred to as uplink MU-MIMO, uplink OFDMA, or more generally, uplink multi-user (MU) (as opposed to uplink single-user (SU)).
• MU multi-user
• SU uplink single-user
• the techniques described herein are generally applicable to uplink MU (and the terms uplink MU and uplink SDMA may be used interchangeably).
• an AP may determine and transmit a threshold duration (e.g., a maximum) for uplink single-user (SU) transmissions to one or more STAs.
• a threshold may be provided for one or more certain access categories (ACs).
• ACs access categories
• the STA may request an uplink MU TXOP by transmitting a TXR frame, a QoS-Null frame that indicates the buffer size at the STA, or a QoS Data frame that does not exceed the maximum duration and which indicates the buffer size at the STA.
• the AP may initiate an uplink MU TXOP.
• FIG. 10 illustrates example operations 1000 that may be performed, for example, by a station (STA), for transmitting using uplink SDMA or single-user (SU) transmissions.
• STA station
• SU single-user
• the operations 1000 begin, at 1002, by determining a threshold duration for SU transmissions.
• the threshold duration may be determined per access category (AC) and may be signaled from an access point (AP).
• the STA generates a data frame and determines, at 1006, whether the transmission time for the data frame will exceed the threshold duration for SU transmissions. If the transmission time for the data frame will not exceed the threshold for SU transmissions, at 1008, the STA transmits the data frame as a SU transmission. On the other hand, if the transmission time for the data frame will exceed the threshold for SU transmissions, at 1010, the STA requests a SDMA TXOP (i.e., a MU TXOP), and transmits the data frame at 1012.
• SDMA TXOP i.e., a MU TXOP
• the AP may initiate a backoff counter with a predetermined number of backoff slots (i.e., a predetermined backoff). When this predetermined backoff expires in the absence of enough subsequent uplink MU TXOP requests being received, the AP may send a TXS frame to start an uplink MU TXOP that serves the uplink MU TXOP requests received thus far. According to certain aspects, if the AP receives enough TXOP requests to fill an uplink MU TXOP, the AP may transmit a TXS in response to the TXR that causes the uplink MU TXOP to become filled.
• a predetermined backoff i.e., a predetermined backoff
• the STA may increase the backoff for the next uplink TXOP with a number of timeslots that the AP will use to initiate an uplink MU TXOP. The STA may then transmit an indication of this increased backoff to the AP.
• the STA may increase the backoff for the next uplink TXOP with a number of timeslots that the AP should use to initiate an uplink MU TXOP.
• the AP may initiate a subsequent uplink MU TXOP based on the queue size information received during the prior uplink MU TXOP.
• the various operations of methods described above may be performed by any suitable means capable of performing the corresponding functions.
• the means may include various hardware and/or software component(s) and/or module(s), including, but not limited to a circuit, an application specific integrate circuit (ASIC), or processor.
• ASIC application specific integrate circuit
• those operations may have corresponding counterpart means-plus-function components with similar numbering.
• blocks 802-804 in FIG. 8 correspond to circuit blocks 802A-804A illustrated in FIG. 8A.
• blocks 902-906 in FIG. 9 correspond to circuit blocks 902A-906A illustrated in FIG. 9A.
• determining encompasses a wide variety of actions. For example, “determining” may include calculating, computing, processing, deriving, investigating, looking up (e.g., looking up in a table, a database or another data structure), ascertaining and the like. Also, “determining” may include receiving (e.g., receiving information), accessing (e.g., accessing data in a memory) and the like. Also, “determining” may include resolving, selecting, choosing, establishing and the like.
• the phrase "at least one of A or B" is meant to include any combination of A and B.
• at least one of A or B comprises A or B or A and B. It could also comrpise a plurality of A, a plurality of B, or a combination of a plurality of A and a plurality of B.
• means for transmitting comprises a transmitter
• means for receiving comprises a receiver
• means for determining comprises a circuit or a processor.
• DSP digital signal processor
• ASIC application specific integrated circuit
• FPGA field programmable gate array signal
• PLD programmable logic device
• a general purpose processor may be a microprocessor, but in the alternative, the processor may be any commercially available processor, controller, microcontroller or state machine.
• a processor may also be implemented as a combination of computing devices, e.g., a combination of a DSP and a microprocessor, a plurality of microprocessors, one or more microprocessors in conjunction with a DSP core, or any other such configuration.
• the functions described may be implemented in hardware, software, firmware, or any combination thereof. If implemented in software, the functions may be stored on or transmitted over as one or more instructions or code on a computer-readable medium.
• Computer-readable media includes both computer storage media and communication media including any medium that facilitates transfer of a computer program from one place to another.
• a storage media may be any available media that can be accessed by a computer.
• such computer-readable media can comprise RAM, ROM, EEPROM, CD-ROM or other optical disk storage, magnetic disk storage or other magnetic storage devices, or any other medium that can be used to carry or store desired program code in the form of instructions or data structures and that can be accessed by a computer.
• any connection is properly termed a computer-readable medium.
• the software is transmitted from a website, server, or other remote source using a coaxial cable, fiber optic cable, twisted pair, digital subscriber line (DSL), or wireless technologies such as infrared, radio, and microwave
• the coaxial cable, fiber optic cable, twisted pair, DSL, or wireless technologies such as infrared, radio, and microwave are included in the definition of medium.
• Disk and disc includes compact disc (CD), laser disc, optical disc, digital versatile disc (DVD), floppy disk and blu-ray disc where disks usually reproduce data magnetically, while discs reproduce data optically with lasers.
• computer readable medium may comprise non-transitory computer readable medium (e.g., tangible media).
• computer readable medium may comprise transitory computer readable medium (e.g., a signal). Combinations of the above should also be included within the scope of computer-readable media.
• the methods disclosed herein comprise one or more steps or actions for achieving the described method.
• the method steps and/or actions may be interchanged with one another without departing from the scope of the claims.
• the order and/or use of specific steps and/or actions may be modified without departing from the scope of the claims.
• a storage media may be any available media that can be accessed by a computer.
• such computer-readable media can comprise RAM, ROM, EEPROM, CD-ROM or other optical disk storage, magnetic disk storage or other magnetic storage devices, or any other medium that can be used to carry or store desired program code in the form of instructions or data structures and that can be accessed by a computer.
• Disk and disc include compact disc (CD), laser disc, optical disc, digital versatile disc (DVD), floppy disk, and Blu-ray ® disc where disks usually reproduce data magnetically, while discs reproduce data optically with lasers.
• certain aspects may comprise a computer program product for performing the operations presented herein.
• a computer program product may comprise a computer readable medium having instructions stored (and/or encoded) thereon, the instructions being executable by one or more processors to perform the operations described herein.
• the computer program product may include packaging material.
• Software or instructions may also be transmitted over a transmission medium.
• a transmission medium For example, if the software is transmitted from a website, server, or other remote source using a coaxial cable, fiber optic cable, twisted pair, digital subscriber line (DSL), or wireless technologies such as infrared, radio, and microwave, then the coaxial cable, fiber optic cable, twisted pair, DSL, or wireless technologies such as infrared, radio, and microwave are included in the definition of transmission medium.
• modules and/or other appropriate means for performing the methods and techniques described herein can be downloaded and/or otherwise obtained by a user terminal and/or base station as applicable.
• a user terminal and/or base station can be coupled to a server to facilitate the transfer of means for performing the methods described herein.
• various methods described herein can be provided via storage means (e.g., RAM, ROM, a physical storage medium such as a compact disc (CD) or floppy disk, etc.), such that a user terminal and/or base station can obtain the various methods upon coupling or providing the storage means to the device.
• storage means e.g., RAM, ROM, a physical storage medium such as a compact disc (CD) or floppy disk, etc.
• CD compact disc
• floppy disk etc.
• any other suitable technique for providing the methods and techniques described herein to a device can be utilized.
• the techniques provided herein may be utilized in a variety of applications.
• the techniques presented herein may be incorporated in an access point station, an access terminal, a mobile handset, or other type of wireless device with processing logic and elements to perform the techniques provided herein.

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• 2015
  • 2015-10-29 JP JP2017522933A patent/JP2017539125A/ja active Pending
  • 2015-10-29 CN CN201580058468.9A patent/CN107079486A/zh active Pending
  • 2015-10-29 KR KR1020177010775A patent/KR20170077127A/ko unknown
  • 2015-10-29 EP EP15791195.9A patent/EP3213575A1/en not_active Withdrawn
  • 2015-10-29 WO PCT/US2015/058126 patent/WO2016069931A1/en active Application Filing

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