WO2016111838A1 - Procédés et appareil de retour d'informations d'état de canal - Google Patents

Procédés et appareil de retour d'informations d'état de canal Download PDF

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Publication number
WO2016111838A1
WO2016111838A1 PCT/US2015/067074 US2015067074W WO2016111838A1 WO 2016111838 A1 WO2016111838 A1 WO 2016111838A1 US 2015067074 W US2015067074 W US 2015067074W WO 2016111838 A1 WO2016111838 A1 WO 2016111838A1
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WO
WIPO (PCT)
Prior art keywords
ppdu
stations
csi
transmission
indication
Prior art date
Application number
PCT/US2015/067074
Other languages
English (en)
Inventor
Simone Merlin
Gwendolyn Denise Barriac
Hemanth Sampath
Sameer Vermani
Original Assignee
Qualcomm Incorporated
Priority date (The priority date is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the date listed.)
Filing date
Publication date
Priority claimed from US14/975,681 external-priority patent/US20160142122A1/en
Application filed by Qualcomm Incorporated filed Critical Qualcomm Incorporated
Publication of WO2016111838A1 publication Critical patent/WO2016111838A1/fr

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Classifications

    • H—ELECTRICITY
    • H04—ELECTRIC COMMUNICATION TECHNIQUE
    • H04L—TRANSMISSION OF DIGITAL INFORMATION, e.g. TELEGRAPHIC COMMUNICATION
    • H04L5/00—Arrangements affording multiple use of the transmission path
    • H04L5/0001—Arrangements for dividing the transmission path
    • H04L5/0014—Three-dimensional division
    • H04L5/0023—Time-frequency-space
    • H—ELECTRICITY
    • H04—ELECTRIC COMMUNICATION TECHNIQUE
    • H04B—TRANSMISSION
    • H04B7/00—Radio transmission systems, i.e. using radiation field
    • H04B7/02—Diversity systems; Multi-antenna system, i.e. transmission or reception using multiple antennas
    • H04B7/04—Diversity systems; Multi-antenna system, i.e. transmission or reception using multiple antennas using two or more spaced independent antennas
    • H04B7/0413—MIMO systems
    • H04B7/0452—Multi-user MIMO systems
    • H—ELECTRICITY
    • H04—ELECTRIC COMMUNICATION TECHNIQUE
    • H04B—TRANSMISSION
    • H04B7/00—Radio transmission systems, i.e. using radiation field
    • H04B7/02—Diversity systems; Multi-antenna system, i.e. transmission or reception using multiple antennas
    • H04B7/04—Diversity systems; Multi-antenna system, i.e. transmission or reception using multiple antennas using two or more spaced independent antennas
    • H04B7/06—Diversity systems; Multi-antenna system, i.e. transmission or reception using multiple antennas using two or more spaced independent antennas at the transmitting station
    • H04B7/0613—Diversity systems; Multi-antenna system, i.e. transmission or reception using multiple antennas using two or more spaced independent antennas at the transmitting station using simultaneous transmission
    • H04B7/0615—Diversity systems; Multi-antenna system, i.e. transmission or reception using multiple antennas using two or more spaced independent antennas at the transmitting station using simultaneous transmission of weighted versions of same signal
    • H04B7/0619—Diversity systems; Multi-antenna system, i.e. transmission or reception using multiple antennas using two or more spaced independent antennas at the transmitting station using simultaneous transmission of weighted versions of same signal using feedback from receiving side
    • H04B7/0621—Feedback content
    • H04B7/0626—Channel coefficients, e.g. channel state information [CSI]
    • H—ELECTRICITY
    • H04—ELECTRIC COMMUNICATION TECHNIQUE
    • H04B—TRANSMISSION
    • H04B7/00—Radio transmission systems, i.e. using radiation field
    • H04B7/02—Diversity systems; Multi-antenna system, i.e. transmission or reception using multiple antennas
    • H04B7/04—Diversity systems; Multi-antenna system, i.e. transmission or reception using multiple antennas using two or more spaced independent antennas
    • H04B7/06—Diversity systems; Multi-antenna system, i.e. transmission or reception using multiple antennas using two or more spaced independent antennas at the transmitting station
    • H04B7/0613—Diversity systems; Multi-antenna system, i.e. transmission or reception using multiple antennas using two or more spaced independent antennas at the transmitting station using simultaneous transmission
    • H04B7/0615—Diversity systems; Multi-antenna system, i.e. transmission or reception using multiple antennas using two or more spaced independent antennas at the transmitting station using simultaneous transmission of weighted versions of same signal
    • H04B7/0619—Diversity systems; Multi-antenna system, i.e. transmission or reception using multiple antennas using two or more spaced independent antennas at the transmitting station using simultaneous transmission of weighted versions of same signal using feedback from receiving side
    • H04B7/0621—Feedback content
    • H04B7/0632—Channel quality parameters, e.g. channel quality indicator [CQI]
    • H—ELECTRICITY
    • H04—ELECTRIC COMMUNICATION TECHNIQUE
    • H04B—TRANSMISSION
    • H04B7/00—Radio transmission systems, i.e. using radiation field
    • H04B7/02—Diversity systems; Multi-antenna system, i.e. transmission or reception using multiple antennas
    • H04B7/04—Diversity systems; Multi-antenna system, i.e. transmission or reception using multiple antennas using two or more spaced independent antennas
    • H04B7/06—Diversity systems; Multi-antenna system, i.e. transmission or reception using multiple antennas using two or more spaced independent antennas at the transmitting station
    • H04B7/0613—Diversity systems; Multi-antenna system, i.e. transmission or reception using multiple antennas using two or more spaced independent antennas at the transmitting station using simultaneous transmission
    • H04B7/0615—Diversity systems; Multi-antenna system, i.e. transmission or reception using multiple antennas using two or more spaced independent antennas at the transmitting station using simultaneous transmission of weighted versions of same signal
    • H04B7/0619—Diversity systems; Multi-antenna system, i.e. transmission or reception using multiple antennas using two or more spaced independent antennas at the transmitting station using simultaneous transmission of weighted versions of same signal using feedback from receiving side
    • H04B7/0636—Feedback format
    • H04B7/0643—Feedback on request
    • H—ELECTRICITY
    • H04—ELECTRIC COMMUNICATION TECHNIQUE
    • H04L—TRANSMISSION OF DIGITAL INFORMATION, e.g. TELEGRAPHIC COMMUNICATION
    • H04L25/00—Baseband systems
    • H04L25/02—Details ; arrangements for supplying electrical power along data transmission lines
    • H04L25/0202—Channel estimation
    • H04L25/0204—Channel estimation of multiple channels
    • H—ELECTRICITY
    • H04—ELECTRIC COMMUNICATION TECHNIQUE
    • H04L—TRANSMISSION OF DIGITAL INFORMATION, e.g. TELEGRAPHIC COMMUNICATION
    • H04L5/00—Arrangements affording multiple use of the transmission path
    • H04L5/003—Arrangements for allocating sub-channels of the transmission path
    • H04L5/0048—Allocation of pilot signals, i.e. of signals known to the receiver
    • H—ELECTRICITY
    • H04—ELECTRIC COMMUNICATION TECHNIQUE
    • H04L—TRANSMISSION OF DIGITAL INFORMATION, e.g. TELEGRAPHIC COMMUNICATION
    • H04L5/00—Arrangements affording multiple use of the transmission path
    • H04L5/003—Arrangements for allocating sub-channels of the transmission path
    • H04L5/0053—Allocation of signaling, i.e. of overhead other than pilot signals
    • H04L5/0057—Physical resource allocation for CQI
    • H—ELECTRICITY
    • H04—ELECTRIC COMMUNICATION TECHNIQUE
    • H04L—TRANSMISSION OF DIGITAL INFORMATION, e.g. TELEGRAPHIC COMMUNICATION
    • H04L1/00—Arrangements for detecting or preventing errors in the information received
    • H04L1/0001—Systems modifying transmission characteristics according to link quality, e.g. power backoff
    • H04L1/0023—Systems modifying transmission characteristics according to link quality, e.g. power backoff characterised by the signalling
    • H04L1/0026—Transmission of channel quality indication

Definitions

  • Certain aspects of the present disclosure generally relate to wireless communications, and more particularly, to methods and apparatus for channel state information feedback
  • communications networks are used to exchange messages among several interacting spatially-separated devices.
  • Networks may be classified according to geographic scope, which could be, for example, a metropolitan area, a local area, or a personal area. Such networks may be designated respectively as a wide area network (WAN), metropolitan area network (MAN), local area network (LAN), or personal area network (PAN).
  • WAN wide area network
  • MAN metropolitan area network
  • LAN local area network
  • PAN personal area network
  • Networks also differ according to the switching/routing technique used to interconnect the various network nodes and devices (e.g., circuit switching vs. packet switching), the type of physical media employed for transmission (e.g., wired vs. wireless), and the set of communication protocols used (e.g., Internet protocol suite, SONET (Synchronous Optical Networking), Ethernet, etc.).
  • SONET Synchronous Optical Networking
  • Wireless networks are often preferred when the network elements are mobile and thus have dynamic connectivity needs, or if the network architecture is formed in an ad hoc, rather than fixed, topology.
  • Wireless networks employ intangible physical media in an unguided propagation mode using electromagnetic waves in the radio, microwave, infra-red, optical, etc. frequency bands. Wireless networks advantageously facilitate user mobility and rapid field deployment when compared to fixed wired networks.
  • One aspect of the disclosure provides a method of wireless communication.
  • the method comprises communicating a request from an access point to two or more stations for the two or more stations to transmit channel state information (CSI) concurrently at a specific time.
  • the method further comprises receiving at the access point the channel state information from each of the two or more stations.
  • CSI channel state information
  • Another aspect of the disclosure provides an apparatus for wireless communication.
  • the apparatus comprising a transmitter configured to transmit a request to two or more stations for the two or more stations to transmit channel state information (CSI) concurrently at a specific time.
  • the apparatus further comprising a receiver configured to receive the channel state information from each of the two or more stations.
  • CSI channel state information
  • Another aspect of the disclosure provides an apparatus for wireless communication.
  • the apparatus comprising means for transmitting a request to two or more stations for the two or more stations to transmit channel state information (CSI) concurrently at a specific time.
  • the apparatus further comprising means for receiving the channel state information from each of the two or more stations.
  • CSI channel state information
  • Another aspect of the disclosure provides a non-transitory computer readable medium.
  • the medium comprising instructions that when executed cause a processor to perform a method of transmitting a request to two or more stations for the two or more stations to transmit channel state information (CSI) concurrently at a specific time.
  • the medium further comprising instructions that when executed cause a processor to perform a method of receiving the channel state information from each of the two or more stations.
  • CSI channel state information
  • FIG. 1 illustrates a multiple-access multiple-input multiple-output (MIMO) system with access points and user terminals.
  • MIMO multiple-access multiple-input multiple-output
  • FIG. 2 illustrates a block diagram of the access point 110 and two user terminals 120m and 120x in a MIMO system.
  • FIG. 3 illustrates various components that may be utilized in a wireless device that may be employed within a wireless communication system.
  • FIG. 4 shows a time diagram of an example frame exchange of channel state information (CSI) feedback.
  • CSI channel state information
  • FIG. 5 shows a time diagram of another example frame exchange of CSI feedback.
  • FIG. 6 shows a time diagram of another example frame exchange of CSI feedback.
  • FIG. 7 A shows a diagram of one embodiment of a null data packet announcement (NDPA) frame.
  • NDPA null data packet announcement
  • FIG. 7B shows a diagram of one embodiment of a modified null data packet announcement (NDPA) frame.
  • NDPA null data packet announcement
  • FIG. 8 shows a diagram of one embodiment of a clear to transmit (CTX) frame.
  • FIG. 9 shows a time diagram of another example frame exchange of CSI feedback.
  • FIG. 10 shows a time diagram of another example frame exchange of CSI feedback.
  • FIG. 11 is a flow chart of an aspect of an exemplary method for providing wireless communication. DETAILED DESCRIPTION
  • Wireless network technologies may include various types of wireless local area networks (WLANs).
  • a WLAN may be used to interconnect nearby devices together, employing widely used networking protocols.
  • the various aspects described herein may apply to any communication standard, such as Wi-Fi or, more generally, any member of the IEEE 802.11 family of wireless protocols.
  • wireless signals may be transmitted according to a high- efficiency 802.11 protocol using orthogonal frequency-division multiplexing (OFDM), direct-sequence spread spectrum (DSSS) communications, a combination of OFDM and DSSS communications, or other schemes.
  • OFDM orthogonal frequency-division multiplexing
  • DSSS direct-sequence spread spectrum
  • Implementations of the high-efficiency 802.11 protocol may be used for Internet access, sensors, metering, smart grid networks, or other wireless applications.
  • aspects of certain devices implementing this particular wireless protocol may consume less power than devices implementing other wireless protocols, may be used to transmit wireless signals across short distances, and/or may be able to transmit signals less likely to be
  • a WLAN includes various devices which are the components that access the wireless network.
  • access points access points
  • STAs stations
  • an AP serves as a hub or base station for the WLAN and an STA serves as a user of the WLAN.
  • a STA may be a laptop computer, a personal digital assistant (PDA), a mobile phone, etc.
  • PDA personal digital assistant
  • an STA connects to an AP via a Wi-Fi (e.g., IEEE 802.11 protocol such as 802.11ah) compliant wireless link to obtain general connectivity to the Internet or to other wide area networks.
  • Wi-Fi e.g., IEEE 802.11 protocol such as 802.11ah
  • an STA may also be used as an AP.
  • the techniques described herein may be used for various broadband wireless communication systems, including 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) systems, Single-Carrier Frequency Division Multiple Access (SC-FDMA) systems, and so forth.
  • SDMA Spatial Division Multiple Access
  • TDMA Time Division Multiple Access
  • OFDMA Orthogonal Frequency Division Multiple Access
  • SC-FDMA Single-Carrier Frequency Division Multiple Access
  • An SDMA system may utilize sufficiently different directions to concurrently transmit data belonging to multiple user terminals.
  • a TDMA system may 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 different user terminal.
  • a TDMA system may implement GSM or some other standards known in the art.
  • An OFDMA system utilizes orthogonal frequency division multiplexing (OFDM), which is a modulation technique that partitions the overall system bandwidth into multiple orthogonal sub-carriers. These sub-carriers may also be called tones, bins, etc. With OFDM, each sub-carrier may be independently modulated with data.
  • An OFDM system may implement IEEE 802.11 or some other standards known in the art.
  • An SC-FDMA system may utilize interleaved FDMA (IFDMA) to transmit on sub-carriers that are distributed across the system bandwidth, localized FDMA (LFDMA) to transmit on a block of adjacent sub-carriers, or enhanced FDMA (EFDMA) to transmit on multiple blocks of adjacent sub-carriers.
  • IFDMA interleaved FDMA
  • LFDMA localized FDMA
  • EFDMA enhanced FDMA
  • modulation symbols are sent in the frequency domain with OFDM and in the time domain with SC-FDMA.
  • a SC-FDMA system may implement
  • a wireless node implemented in accordance with the teachings herein may comprise an access point or an access terminal.
  • An access point may comprise, be implemented as, or known as a
  • NodeB Radio Network Controller
  • RNC Radio Network Controller
  • BSC Base Station Controller
  • BTS Base Transceiver Station
  • BS Base Station
  • TF Transceiver Function
  • RNC Radio Network Controller
  • BSS Base Station Controller
  • TF Transceiver Function
  • RBS Basic Service Set
  • ESS Extended Service Set
  • RBS Radio Base Station
  • a station may also comprise, be implemented as, or known as a user terminal, an access terminal ("AT”), a subscriber station, a subscriber unit, a mobile station, a remote station, a remote terminal, a user agent, a user device, user equipment, or some other terminology.
  • an access terminal may comprise a cellular telephone, a cordless telephone, a Session Initiation Protocol ("SIP”) phone, a wireless local loop (“WLL”) station, a personal digital assistant (“PDA”), a handheld device having wireless connection capability, or some other suitable processing device connected to a wireless modem.
  • SIP Session Initiation Protocol
  • WLL wireless local loop
  • PDA personal digital assistant
  • a phone e.g., a cellular phone or smartphone
  • a computer e.g., a laptop
  • a portable communication device e.g., a headset
  • a portable computing device e.g., a personal data assistant
  • an entertainment device e.g., a music or video device, or a satellite radio
  • gaming device or system e.g., a gaming console, a global positioning system device, or any other suitable device that is configured to communicate via a wireless medium.
  • FIG. 1 is a diagram that illustrates a multiple-access multiple-input multiple- output (MIMO) system 100 with access points and user terminals.
  • MIMO multiple-access multiple-input multiple- output
  • An access point is generally a fixed station that communicates with the user terminals and may also be referred to as a base station or using some other terminology.
  • a user terminal or STA may be fixed or mobile and may also be referred to as a mobile station or a wireless device, or using some other terminology.
  • the 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) is the communication link from the access point to the user terminals
  • the uplink (i.e., reverse link) is the communication link from the user terminals to the access point.
  • 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.
  • the user terminals 120 may also include some user terminals that do not support SDMA.
  • the AP 110 may be configured to communicate with both SDMA and non-SDMA user terminals. This approach may conveniently allow older versions of user terminals (“legacy" stations) that do not support SDMA to remain deployed in an enterprise, extending their useful lifetime, while allowing newer SDMA user terminals to be introduced as deemed appropriate.
  • the system 100 employs multiple transmit and multiple receive antennas for data transmission on the downlink and uplink.
  • the access point 110 is equipped with Nap antennas and represents the multiple-input (MI) for downlink transmissions and the multiple-output (MO) for uplink transmissions.
  • a set of K selected user terminals 120 collectively represents the multiple-output for downlink transmissions and the multiple- input for uplink transmissions.
  • MI multiple-input
  • MO multiple-output
  • K selected user terminals 120 collectively represents the multiple-output for downlink transmissions and the multiple- input for uplink transmissions.
  • N ap ⁇ K ⁇ 1 if the data symbol streams for the K user terminals are not multiplexed in code, frequency or time by some means.
  • K may be greater than N ap if the data symbol streams can be multiplexed using TDMA technique, different code channels with CDMA, disjoint sets of sub-bands with OFDM, and so on.
  • Each selected user terminal may transmit user- specific data to and/or receive user-specific data from the access point.
  • each selected user terminal may be equipped with one or multiple antennas (i.e., N Ht ⁇ 1).
  • the K selected user terminals can have the same number of antennas, or one or more user terminals may have a different number of antennas.
  • the SDMA system 100 may 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.
  • TDD time division duplex
  • FDD frequency division duplex
  • the downlink and uplink use different frequency bands.
  • the 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).
  • the system 100 may also be a TDMA system if the user terminals 120 share the same frequency channel by dividing transmission/reception into different time slots, where each time slot may be assigned to a different user terminal 120.
  • FIG. 2 illustrates a block diagram of the access point 110 and two user terminals 120m and 120x in MIMO system 100.
  • the access point 110 is equipped with N t antennas 224a through 224ap.
  • the user terminal 120m is equipped with N utim antennas 252 ma through 252 mu
  • the user terminal 120x is equipped with N ut x antennas 252 xa through 252 xu .
  • the access point 110 is a transmitting entity for the downlink and a receiving entity for the uplink.
  • the 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 wireless channel
  • a “receiving entity” is an independently operated apparatus or device capable of receiving data via a wireless 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 dn user terminals are selected for simultaneous transmission on the downlink.
  • N up may or may not be equal to N dn
  • N up and N dn may be static values or may change for each scheduling interval. Beam-steering or some other spatial processing technique may be used at the access point 110 and/or the user terminal 120.
  • 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 (e.g., encodes, interleaves, and modulates) the traffic data 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.
  • a TX spatial processor 290 performs spatial processing on the data symbol stream and provides N utim transmit symbol streams for the N utim 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 utim transmitter units 254 provide N utim uplink signals for transmission from N ut m antennas 252, for example to transmit to the access point 110.
  • N up user terminals may be scheduled for simultaneous transmission on the uplink.
  • Each of these user terminals may perform spatial processing on its respective data symbol stream and transmit its respective set of transmit symbol streams on the uplink to the access point 110.
  • N up antennas 224a through 224 ap 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 up received symbol streams from N up receiver units 222 and provides N up recovered uplink data symbol streams.
  • the receiver spatial processing may be performed in accordance with the channel correlation matrix inversion (CCMI), minimum mean square error (MMSE), soft interference cancellation (SIC), or some other technique.
  • Each recovered uplink data symbol stream is an estimate of a data symbol stream transmitted by a respective user terminal.
  • An RX data processor 242 processes (e.g., demodulates, deinterleaves, and decodes) each recovered uplink data symbol stream 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.
  • 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. The TX data processor 210 provides N dn downlink data symbol streams for the N dn user terminals.
  • a TX spatial processor 220 performs spatial processing (such as a precoding or beamforming) on the N dn downlink data symbol streams, and provides N up transmit symbol streams for the N up antennas.
  • Each transmitter unit 222 receives and processes a respective transmit symbol stream to generate a downlink signal.
  • N up transmitter units 222 may provide N up downlink signals for transmission from N up antennas 224, for example to transmit to the user terminals 120.
  • N utim antennas 252 receive the N up downlink signals from the access point 110.
  • Each receiver unit 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 utim received symbol streams from N ut m receiver units 254 and provides a recovered downlink data symbol stream for the user terminal 120. The receiver spatial processing may be 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.
  • a channel estimator 278 estimates the downlink channel response and provides downlink channel estimates, which may include channel gain estimates, SNR estimates, noise variance and so on.
  • a channel estimator 228 estimates the uplink channel response and provides uplink channel estimates.
  • Controller 280 for each user terminal typically derives the spatial filter matrix for the user terminal based on the downlink channel response matrix H dn,m for that user terminal.
  • Controller 230 derives the spatial filter matrix for the access point based on the effective uplink channel response matrix H up eff .
  • the controller 280 for each user terminal may send feedback information (e.g., the downlink and/or uplink eigenvectors, eigenvalues, SNR estimates, and so on) to the access point 110.
  • the controllers 230 and 280 may also control the operation of various processing units at the access point 110 and user terminal 120, respectively.
  • FIG. 3 illustrates various components that may be utilized in a wireless device
  • the wireless device 302 may be employed within the wireless communication 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 implement 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 may perform 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 processor 304 may comprise or be a component of a processing system implemented with one or more processors.
  • the one or more processors may be implemented with any combination of general-purpose microprocessors, microcontrollers, digital signal processors (DSPs), field programmable gate array (FPGAs), programmable logic devices (PLDs), controllers, state machines, gated logic, discrete hardware components, dedicated hardware finite state machines, or any other suitable entities that can perform calculations or other manipulations of information.
  • the processing system may also include machine-readable media for storing software.
  • Software shall be construed broadly to mean any type of instructions, whether referred to as software, firmware, middleware, microcode, hardware description language, or otherwise. Instructions may include code (e.g., in source code format, binary code format, executable code format, or any other suitable format of code). The instructions, when executed by the one or more processors, cause the processing system to perform the various functions 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 single or a plurality of transceiver 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.
  • the UL CSI may be transmitted in a multi-user MIMO (MU-MIMO) system.
  • the UL CSI may be transmitted in a multi-user FDMA (MU-FDMA), multi-user OFDMA (MU-OFDMA) or similar FDMA system.
  • FIGs. 4-6 illustrate UL-MU-MIMO transmissions 41 OA and 410B that would apply equally to UL-FDMA, UL-OFDMA, or similar UL FDMA system transmissions.
  • UL-MU-MIMO, UL-OFDMA, or similar UL FDMA system transmissions can be sent simultaneously from multiple STAs to an AP and may create efficiencies in wireless communication.
  • the sounding procedure described herein comprises at least an "announcement frame” and a "CSI frame”, and may further comprise a "null data packet (NDP) frame” and a "report poll frame".
  • the "frame” may be identified as a physical layer data unit (PPDU).
  • the announcement frame(s) may convey at least sounding announcement information which instructs the STAs on if/how to compute the CSI, and UL-MU resource allocation information which instructs the STAs on how to send the CSI by using UL-MU-MIMO or UL-OFDMA.
  • the sounding announcement PPDU may carry sounding announcement information in the MAC payload or in its PHY header.
  • the sounding announcement information comprises identifiers of the STAs that are used to report the CSI and may comprise additional parameters for the computation and transmissions of the CSI.
  • the sounding NDP frame provides a reference signal that allows STAs to estimate the channel between the one or more antennas of the transmitter and the one or more antennas of the STA and may be an 802.11 ax NDP frame, an 802.1 lac NDP frame, an 802.1 In NDP frame, an 802.11 ah NDP frame, or other 802.11 based NDP frame.
  • the announcement PPDU may include the reference signaling for channel estimation, so that the NDP frame may not be sent.
  • channel state information may comprise known channel properties of a communication link.
  • the CSI may describe how a signal propagates and represents the combined effect of, for example, scattering, fading, and power decay with distance.
  • the CSI may comprise one or more of a beamforming matrix, received signal strength, and other information that allows weighting of antennas to mitigate interference in the spatial domain.
  • FIG. 4 is a time sequence diagram illustrating an example of a frame exchange of channel state information (CSI) feedback between an AP 110 and multiple user terminals using UL-MU-MIMO protocol.
  • an AP 110 may transmit a sounding announcement PPDU 401 to the user terminals 120 indicating which STAs are the intended recipients and the format of the forthcoming sounding frame.
  • the sounding announcement PPDU 401 may also instruct some or all of the recipient user terminals 120 to respond simultaneously after the sounding frame (null data packet (NDP) 405, as shown in FIG 4).
  • NDP sound data packet
  • the sounding announcement PPDU 401 may further instruct the user terminals to use UL-MU-MIMO, UL-OFDMA, or a combination of both and the corresponding parameters for transmission.
  • the time in between the sounding announcement PPDU 401 and the sounding NDP 405 may be a short interframe space (SIFS) time and the timing in between the sounding NDP 405 and the CSI UL-MU-MIMO transmissions 41 OA and 410B may be a SIFS (or point interframe space (PIFS)) time.
  • SIFS short interframe space
  • the AP 110 may then transmit the sounding null data packet (NDP) 405 frame following the sounding announcement PPDU 401.
  • NDP sounding null data packet
  • the user terminals 120 may transmit CSI to the AP 110 using a UL-MU-MIMO transmission or an UL-OFDMA transmission.
  • STA1 and STA2 transmit CSI to the AP 110 using UL-MU-MIMO or UL-OFDMA transmissions 410A and 410B.
  • the concurrent transmission may occur at the same time or within a certain threshold time period.
  • the STAs listed in the sounding announcement PPDU 401 may estimate the channel based on the sounding NDP 405 frame and send a representation of the estimated channel in a sounding feedback (CSI UL-MU- MIMO/UL-OFDMA transmissions 41 OA and 410B) packet.
  • CSI UL-MU- MIMO/UL-OFDMA transmissions 41 OA and 410B sounding feedback
  • the AP 110 Upon receiving the CSI UL-MU-MIMO/UL-OFDMA transmissions 410A and 410B, the AP 110 knows the channel from the AP 110 to each of STA1 and STA2.
  • FIG. 5 is a time sequence diagram illustrating an example of a frame exchange of channel state information (CSI) feedback between an AP 110 and multiple user terminals using UL-MU-MIMO or UL-OFDMA protocol.
  • the sounding announcement frame may also be used as the sounding frame.
  • the sounding announcement packet 402 includes the sounding announcement PPDU 401 and long training fields (LTFs) 404 at the end of the sounding announcement packet 402.
  • the LTFs 404 (or similar fields) may be used as the sounding frame and the user terminals 120 may transmit CSI to the AP 110 using a UL- MU-MIMO or a UL-OFDMA transmission in response to the sounding announcement packet 402.
  • the LTFs 404 may comprise a training sequence for channel estimation.
  • the LTFs 404 (or similar fields) may be included in the preamble of the sounding announcement packet 402.
  • the presence and other parameters describing the sounding signal may be indicated in the PHY header of the sounding announcement PPDU or indicated by the MAC payload as described earlier.
  • a non-limiting advantage of this option is the lower overhead (allow to save SIFS time, plus the initial portion of the sounding NDP, which need not be sent).
  • the STAs may have a limited time to identify whether they are sounded STAs, before estimating the channel from the LTFs.
  • the sounding signal may be prepended and be part of the PHY preamble of the sounding announcement PPDU.
  • a sounding announcement may be signaled by a MAC frame which may be aggregated with data packets.
  • FIG. 6 is a time sequence diagram that illustrates an example of sending the sounding announcement within STA data messages 403 and 406.
  • the sounding announcement portion of the STA data messages 403 and 406 contain information for one STA (STA1 and STA2, respectively) and STA1 and STA2 receive the messages 403 and 406 followed by the sounding NDP 405 or other sounding frame.
  • STA1 and STA2 then begin the CSI UL- MU-MIMO (or UL-OFDMA) transmissions 410A and 410B.
  • the CSI feedback in UL-MU-MIMO (or UL-OFDMA) transmissions 41 OA and 410B may also be aggregated with data packets.
  • the CSI may be aggregated with data packets if the physical layer data unit (PPDU) duration indicated by the sounding announcement is long enough so that the PPDU can host additional bytes after the CSI.
  • PPDU physical layer data unit
  • the sounding announcement frame (as shown in FIGs. 4-6) may comprise a lx or 4x PPDU, which carries in its payload a MAC frame denominated NDP A.
  • the PPDU may be a single-user (SU) PPDU or MU (MIMO or OFDMA) PPDU and may include one or more MAC protocol data units (MPDUs), at least one of which is an NDPA MAC frame.
  • MPDUs MAC protocol data units
  • the aggregation discussed in relation to FIG. 6 may be realized by aggregating the NDPA MAC frame in an aggregated MPDU (A-MPDU) with other MAC frames.
  • the NDPA MAC frame provides at least an identification of the STAs that are to estimate and report the CSI, the parameters for the format of the CSI (band, resolution, quantization ), and may include parameters for the transmission of the CSI (UL-MU-MIMO/OFDMA resource allocation, MCS etc.).
  • FIG. 7A is a diagram of an example of a NDPA MAC frame format structure.
  • the NDPA frame 700 includes a frame control (FC) field 705, a duration field 710, a receiver address (RA) field 715, a transmitter address (TA) field 720, sounding dialog token field 725, a per STA information (info) field 730, and a frame check sequence (FCS) field 750.
  • FC frame control
  • the FC field 705 indicates a control subtype or an extension subtype.
  • the protocol version, type, and subtype may be the same as defined for the NDP announcement frame defined by the 802.1 lac standard.
  • one or more bits in one of the FC field 705, duration field 710, TA field 720, RA field 715, or sounding dialog token field 725 may be used to indicate that the NDPA frame 700 has a modified format for its use as described in this application.
  • a new type and new subtype may be used to indicate that the NDPA frame 700 has a specific format for the use as described in this application.
  • 2 reserved bits in the sounding dialog token field 725 may be used to indicate whether the user terminals 120 should send their responses to the NDPA 700 via UL-MU-MIMO transmissions, UL-OFDMA transmissions, or according to 802.1 lac behavior (i.e. one STA sends CSI immediately and the other STAs wait to be polled).
  • the duration field 710 indicates to any receiver of the NDPA frame 700 to set the network allocation vector (NAV).
  • the RA field 715 indicates the user terminals 120 (or STAs) that are the intended recipients of the frame.
  • the RA field 715 may be set to broadcast or to a multicast group that includes the STAs listed in the STA info fields 730-740. If the type or subtype are set to a new value, the RA field 715 may be omitted, as the type/subtype implicitly indicates that the destination is broadcast.
  • the TA field 720 indicates the transmitter address or a BSSID.
  • the sounding dialog token field 725 indicates the particular sounding announcement to the STAs.
  • the STAs listed in the STA info fields 730-740 may respond by using UL-MU-MIMO.
  • the stream ordering may follow the same ordering of STA info fields 730-740.
  • the number of streams to be allocated and the power offsets for each of the STAs may be pre-negotiated.
  • the number of streams allocated per STA may be based on the number of streams sounded by the sounding NDP. For example, the number of streams per STA may be equal to the number of sounded streams divided by the maximum number of streams available for all STAs listed.
  • the STAs listed in the STA info fields 730-740 may respond by using UL-OFDMA.
  • the channel ordering may follow the same ordering of STA info fields 730-740.
  • the number of channels to be allocated and the power offsets for each of the STAs may be pre-negotiated.
  • the number of channels allocated per STA may be based on the number of channels sounded by the sounding NDP.
  • the STA info 730 field contains information regarding a particular STA and may include a per-STA (per user terminal 120) set of information (see STA info 1 730 and STA info N 740).
  • the STA info field 730 may include an allocation identifier (AID) field 732 which identifies a STA, a feedback type field 734, and an Nc index field 736.
  • the FCS field 750 carries an FCS value used for error detection of the NDPA frame 700.
  • the NDPA frame 700 may also include a PPDU duration field (not shown).
  • the PPDU duration field indicates the duration of the following UL- MU-MIMO (or UL-OFDMA) PPDU that the user terminals 120 are allowed to send.
  • the PPDU duration may be agreed to beforehand between an AP 110 and the user terminals 120.
  • the PPDU duration field may not be included if the duration field 710 is used to compute the duration of the response that the user terminals 120 are allowed to send.
  • a sounding announcement PPDU may comprise a modified null data packet announcement (NDPA) frame.
  • FIG. 7B is a diagram of an example of a modified MAC NDPA structure.
  • the NDPA frame 701 contains the same fields as the NDPA frame 700 except the RA field 715 may be omitted and the STA info fields 730-740 are extended by one or two bytes to include new fields.
  • STA info fields 760-770 may include a number of spatial streams field (Nss) field 733 which indicates the number of spatial streams a STA may use (in an UL-MU-MIMO system), a time adjustment field 735 which indicates a time that a STA should adjust its transmission compared to the reception of a trigger frame, a power adjustment field 737 which indicates a power backoff a STA should take from a declared transmit power, an indication field 738 which indicates the allowed transmission modes, and a MCS field 739 which indicates the MCS the STA should use or the backoff the STA should use.
  • the STA info field 730 may include a 1 bit indication of whether the STA may respond immediately or wait to be polled later.
  • the NDPA 700 or 701 may include a field indicating that a certain number of STAs should respond immediately and the remaining STA should wait to be polled later.
  • the NDPA frame 700 may also include a PPDU duration field
  • the PPDU duration field indicates the duration of the following UL-MU- MIMO PPDU that the user terminals 120 are allowed to send.
  • the PPDU duration may be agreed to beforehand between an AP 110 and the user terminals 120.
  • the PPDU duration field may not be included if the duration field 710 carries a value that allows computation of the duration of the response that the user terminals 120 are allowed to send.
  • a sounding announcement PPDU may comprise a clear to transmit (CTX) frame.
  • FIG. 8 is a diagram of an example of a CTX structure.
  • the CTX frame 800 may comprise a MAC NDPA frame.
  • the CTX frame 800 includes a frame control (FC) field 805, a duration field 810, a transmitter address (TA) field 815, a control (CTRL) field 820, a PPDU duration field 825, a STA info field 830, and a frame check sequence (FCS) field 855.
  • the FC field 805 indicates a control subtype or an extension subtype.
  • the duration field 810 indicates to any receiver of the CTX frame 800 to set the network allocation vector (NAV).
  • the TA field 815 indicates the transmitter address or a BSSID.
  • the CTRL field 820 is a generic field that may include information regarding the format of the remaining portion of the frame (e.g., the number of STA info fields and the presence or absence of any subfields within a STA info field), indications for rate adaptation for the user terminals 120 (e.g., a number indicating how the STA should lower their MCSs, compared to the MCS the STA would have used in a single- user (SU) transmission or a number indicating the signal-to-interference-plus-noise ratio (SINR) loss that the STA should account for when computing the MCS in the UL transmission opportunity (TXOP), compared to the MCS computation in the SU transmission), indication of allowed TID, and indication that a CTS must be sent immediately following the CTX frame 800.
  • the format of the remaining portion of the frame
  • the CTRL field 820 may also indicate if the CTX frame 800 is being used for UL-MU-MIMO or for UL-OFDMA or both, indicating whether an Nss or tone allocation field is present in the STA Info field 830.
  • the indication of whether the CTX is for UL-MU-MIMO or for UL- OFDMA can be based on the value of the subtype.
  • the UL-MU- MIMO and UL-OFDMA operations can be jointly performed by specifying to a STA both the spatial streams to be used and the channel to be used, in which case both fields are present in the CTX; in this case, the Nss indication is referred to a specific tone allocation.
  • the PPDU duration field 825 indicates the duration of the following UL- MU-MIMO PPDU that the user terminals 120 are allowed to send.
  • the STA info field 830 contains information regarding a particular STA and may include a per-STA (per user terminal 120) set of information (see STA Info 1 830 and STA Info N 850).
  • the STA info field 830 may include an AID or MAC address field 832 which identifies a STA, a number of spatial streams field (Nss) 834 field which indicates the number of spatial streams a STA may use (in an UL-MU-MIMO system), a time adjustment field 836 which indicates a time that a STA should adjust its transmission compared to the reception of a trigger frame (the CTX in this case), a power adjustment field 838 which indicates a power backoff a STA should take from a declared transmit power, a tone allocation field 840 which indicates the tones or frequencies a STA may use (in a UL- OFDMA system), an allowed transmission (TX) mode field 842 which indicates the allowed transmission modes, and a MCS 844 field which indicates the MCS the STA should use.
  • the FCS 855 field carries an FCS value used for error detection of the CTX frame 800.
  • the PPDU duration field 825 may be omitted from the
  • CTX 800 frame if the duration field 810 carries a value that allows computation of the duration of the response that the user terminals 120 are allowed to send.
  • the CTX 800 frame may include a sounding sequence number or a token number which STAs may use in their responses to indicate to the AP 110 that its messages are in response to the same CTX 800 frame.
  • the STA info field 830 may include a 1 bit indication of whether the STA may respond immediately or wait to be polled later.
  • the FC field 805 or the CTRL field 820 may indicate that the CTX 800 frame is a sounding announcement CTX frame (i.e. the CTX is followed by a sounding frame (NDP) and requests responses from multiple STAs).
  • NDP sounding frame
  • the sounding announcement PPDU may carry the announcement information in one or more of the SIG field(s) in the PHY header.
  • the sounding announcement PPDU may not carry a MAC payload.
  • the sounding announcement PPDU may include a MAC payload with data, control or management information.
  • the sounding announcement PPDU 401 may be an 802.11 ax
  • PPDU with a high efficiency (HE) SIG-B field comprising at least an identification of the transmitter AP, an identification of the STAs that are supposed to compute the CSI, identification of the STAs that are supposed to respond with UL-MU-MIMO/OFDMA CSI and the corresponding transmission parameters.
  • the SIG field may include any of the information described in relation to FIGs. 7, 8, or 9.
  • the sounding announcement PPDU carries in the PHY header only the UL resource allocation information, instructing the STA on the transmission parameters for sending the response UL-MU-MIMO/OFDMA PPDU, but does not include sounding announcement information in the PHY header.
  • the sounding announcement information may instead be carried by a NDPA MAC frame in the payload.
  • the announcement frame may be a lx or 4x PPDU carrying an NDPA MAC frame substantially the same as in 802.1 lac, and hence does not include UL resource allocation information.
  • FIG. 9 is a time sequence diagram illustrating an example of a frame exchange of channel state information (CSI) feedback between an AP 110 and multiple user terminals using UL-MU-MIMO protocol.
  • the l lac NDPA 901 may be followed in SIFS time by a sounding NDP frame 905 which provides the sounding signal for HE STAs and also indicates the UL allocation for the immediate response.
  • the sounding NDP frame 905 comprises a HE NDP and a separate trigger.
  • the UL resource allocation information may be included in one of the SIG fields of the HE NDP PHY header in the sounding NDP frame 905.
  • the l lac NDP A frame 901 identifies the STAs that need to prepare the CSI, while the sounding NDP frame 905 indicates the STAs that need to respond in SIFS time with UL-MU-MIMO or UL-OFDMA CSI.
  • the l lac NDPA 901 also identifies the STAs that are supposed to respond immediately after the sounding NDP frame 905, in which case the sounding NDP frame 905 may provide only the allocation indication per each STA.
  • the announcement PPDU described herein may be used in any of the exchanges in FIGs. 4, 5, or 6.
  • the sounding procedure may target a number of STAs greater than the number of STAs that may respond immediately, or some of the STAs may not respond with CSI due to a missed announcement, or some STAs may response but the CSI may not have been correctly received by the AP.
  • the AP may poll the STAs from which CSI was not received in order to retrieve the missing CSI.
  • the AP may repeat the operation described in relation to FIGs. 4, 5, or 6 for the remaining STAs.
  • the AP may send a report poll frame soliciting certain
  • the report poll frame may have essentially the same structure of the sounding announcement PPDU, in any of the options described above (MAC, PHY, hybrid, etc.), with an indication that there is no sounding NDP following the frame (hence differentiating it from an announcement frame).
  • the identified STAs may respond with UL- MU-MIMO/OFDMA after a SIFS time.
  • the transmission of the CSI (via UL-MU-MIMO or UL- OFDMA) from multiple STAs may be followed by an acknowledgment (ACK) frame from an AP 110.
  • FIG. 10 is a time sequence diagram illustrating an example of a frame exchange of channel state information (CSI) feedback between an AP 110 and multiple user terminals using UL-MU-MIMO protocol followed by a block acknowledgement (BA) frame 1025.
  • the acknowledgments may be sent by using a multicast ACK frame (BA frame 1025) including an ACK indication for the multiple STAs.
  • the acknowledgements may also be sent by using multiple ACKs, one per each STA, which may be sent at the same time by using downlink (DL) MU-MIMO or DL MU-FDMA, or may be sent sequentially.
  • the acknowledgements may be sent only upon request by a STA, the request by the STA may be communicated by the STA in a management frame sent to the AP 110.
  • the request for acknowledgement may be indicated by a CSI frame, which may be an action frame with an ACK request.
  • the acknowledgments may be sent after every CSI transmission.
  • the acknowledgments may be sent at an AP 110's discretion, as indicated in a management frame (such as a beacon) or as indicated by using one bit in the sounding announcement PPDU 401.
  • the indication that the AP 110 may send an ACK frame in response to the received may also be specified per STA, by including one bit in each STA info field.
  • FIG. 11 is a flow chart of an exemplary method 1100 for wireless communication in accordance with certain embodiments described herein. As discussed above with respect to FIGs. 4-6 a person having ordinary skill in the art will appreciate that the method 1100 may be implemented by other suitable devices and systems.
  • operation block 1105 a request for two or more stations to transmit channel state information at a specific time is communicated to the two or more stations.
  • channel state information is received from each of the two or more stations.
  • an apparatus for wireless communication may perform the method 1100 described in FIG. 11.
  • the apparatus comprises means for transmitting a request to two or more stations for the two or more stations to transmit channel state information at a specific time.
  • the apparatus may further comprise means for receiving channel state information, from each of the two or more stations.
  • a phrase referring to "at least one of a list of items refers to any combination of those items, including single members.
  • "at least one of: A, B or C” is intended to cover A or B or C or A and B or A and C or B and C or A, B and C or 2A or 2B or 2C and so on.
  • an interface may refer to hardware or software configured to connect two or more devices together.
  • an interface may be a part of a processor or a bus and may be configured to allow communication of information or data between the devices.
  • the interface may be integrated into a chip or other device.
  • an interface may comprise a receiver configured to receive information or communications from a device at another device.
  • the interface e.g., of a processor or a bus
  • an interface may comprise a transmitter configured to transmit or communicate information or data to another device.
  • the interface may transmit information or data or may prepare information or data for outputting for transmission (e.g., via a bus).
  • 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.
  • 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.

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Abstract

La présente invention concerne des procédés et un appareil de retour d'informations d'état de canal. Selon un aspect, l'invention concerne un procédé de communication sans fil. Le procédé consiste à fournir une demande en provenance d'un point d'accès à deux stations ou plus afin que les deux stations ou plus transmettent des informations d'état de canal (CSI) en même temps à un instant spécifique. La demande comprenant une unité de données de couche physique (PPDU) comprenant une indication à savoir laquelle des deux ou plusieurs stations doit calculer et transmettre les CSI en réponse à la demande. Le procédé comprend en outre la réception, au niveau du point d'accès, des CSI en provenance de chaque station parmi les deux stations ou plus.
PCT/US2015/067074 2015-01-07 2015-12-21 Procédés et appareil de retour d'informations d'état de canal WO2016111838A1 (fr)

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US14/975,681 US20160142122A1 (en) 2013-10-17 2015-12-18 Methods and apparatus for channel state information feedback
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