Access point, method performed thereby, and station for receiving null data packet announcement

Abstract

A method for resource feedback from an access point in a wireless local area network (WLAN) may include using either orthogonal frequency division multiple access (OFDMA) or multiple-input multiple-output (MIMO) communication in the WLAN to relay communication from the access point to multiple stations. The method may include sending a resource element channel quality feedback request for at least one resource element within a first bandwidth to each of the plurality of stations in a Null Data Packet Announcement (NDPA) frame; sending null data packets (NDP) from the access point to each of the plurality of stations to measure and provide channel quality for the at least one resource element within the first bandwidth for each of the plurality of stations; receiving a resource element channel quality feedback response at the access point from at least one of the plurality of stations, the resource element channel quality feedback response including an indication of channel quality for the resource element within the first bandwidth for at least one of the plurality of stations; and / or scheduling at the access point at at least one allocated resource element for at least one of the plurality of stations to transmit data to the access point based on the feedback response, or sending a request to at least one of the plurality of stations to transmit channel information based on the feedback response.

Description

Technical Field

[0001] Cross-citation of related applications

[0002] This application is in the interest of U.S. Provisional Patent Application No. 62 / 191,100, filed July 10, 2015; U.S. Provisional Patent Application No. 62 / 217,559, filed September 11, 2015; and U.S. Provisional Patent Application No. 62 / 251,482, filed November 5, 2015, the contents of which are incorporated herein by reference, and this application claims the benefit of the filing date of these priority applications. Prior Technology

[0003] Wireless Local Area Networks (WLANs) can operate in various modes, such as Infrastructure Basic Services Set (BSS) mode and Standalone BSS (IBSS) mode. In Infrastructure BSS mode, a WLAN can have Access Points (APs) for the BSS. One or more Wireless Transmitter Receivers (WTRUs), such as stations (STAs), can be associated with an AP. The AP can have access or interfaces to a Distribution System (DS) or other types of wired / wireless networks, carrying traffic both within and outside the BSS. Traffic originating outside the BSS and destined for a STA can arrive via the AP, which can deliver the traffic to the STA. Summary of the Invention

[0004] This invention addresses the problem of improving unified feedback in systems, as described in the prior art. It discloses systems, methods, and means for unified feedback in Orthogonal Frequency Division Multiple Access (OFDMA) for Wireless Local Area Networks (WLANs). Unified feedback can be provided by per-RU modulation and coding scheme (MCS) feedback, per-RU channel state information (CSI) feedback, and / or feedback with symmetric RU allocation. RU-based MCS feedback can include, for example, RU feedback compression with signal-to-noise ratio (SNR) deviation reporting and / or RU label compression using source coding or hierarchical RU labels (e.g., RU trees). RU-based CSI feedback can be provided, for example, based on RU-based CSI feedback capability, RU feedback mode, multi-stage RU-based feedback, and / or indication of RU feedback granularity.

[0005] This method may include a method for resource feedback at an access point in a wireless local area network (WLAN). The method may include transmitting communication from an access point to a plurality of stations using either Orthogonal Frequency Division Multiple Access (OFDMA) or Multiple-Input Multiple-Output (MIMO) communication in the WLAN; sending a resource element channel quality feedback request for at least one resource element within a first bandwidth from the access point to each of the plurality of stations in a Null Data Packet Announcement (NDPA) frame; sending null data packets (NDP) from the access point to each of the plurality of stations to measure and provide channel quality for at least one resource element within the first bandwidth for each of the plurality of stations; receiving a resource element channel quality feedback response at the access point from at least one of the plurality of stations, the resource element channel quality feedback response including an indication of channel quality for the resource element within the first bandwidth for at least one of the plurality of stations; and / or scheduling at the access point at at least one allocated resource element for at least one of the plurality of stations to transmit data to the access point based on the feedback response, or sending a request to at least one of the plurality of stations to transmit channel information based on the feedback response.

[0006] The channel quality indication may include at least one of Signal-to-Noise Ratio (SNR), Signal-to-Interference-to-Noise Ratio (SINR), and Modulation and Coding (MCS) feedback. The first bandwidth may be smaller than the transmission bandwidth between the access point and the plurality of stations. The access point may send a Null Data Packet Announcement (NDPA) frame to the plurality of stations, the NDPA frame including at least one of feedback bandwidth, packet, noise criterion index, SNR index, and feedback type. The access point may schedule at least one of the plurality of stations to send feedback upon receiving a feedback request, when polled by the access point in a cascaded manner, or at a time provided by the access point. Sending channel information based on a feedback response request to at least one of the plurality of stations may include sending the request within the first bandwidth or a second bandwidth that is a subset of the first bandwidth.

[0007] The channel information may include channel status information or explicitly compressed channel status information. The channel quality may include SNR, channel status information, channel quality indicator, precoding matrix indicator, or rank indicator.

[0008] The NDPA frame may include channel feedback parameters. These channel feedback parameters may be determined by the access point or the multiple stations.

[0009] An access point in a wireless local area network (WLAN) may include a processor configured with a plurality of executable instructions to: transmit communication from the access point to a plurality of stations using either Orthogonal Frequency Division Multiple Access (OFDMA) or Multiple-Input Multiple-Output (MIMO) communication within the WLAN; transmit a resource element channel quality feedback request for at least one resource element within a first bandwidth from the access point to each of the plurality of stations in a Null Data Packet Announcement (NDPA) frame; and transmit null data packets (NDP) from the access point to each of the plurality of stations to measure and provide information on the channel quality feedback request sent to the network. The channel quality of at least one resource unit within the first bandwidth of each of the plurality of stations; receiving a resource unit channel quality feedback response from at least one of the plurality of stations at the access point, the resource unit channel quality feedback response including an indication of the channel quality of the resource unit within the first bandwidth for at least one of the plurality of stations; and / or scheduling at the access point at at least one allocated resource unit for at least one of the plurality of stations to transmit data to the access point based on the feedback response, or sending a request to at least one of the plurality of stations to transmit channel information based on the feedback response.

[0010] The access point processor may include a plurality of executable instructions for sending Null Data Packet Announcement (NDPA) frames to a plurality of stations, the NDPA frames including at least one of feedback bandwidth, packet, noise criterion index, signal-to-noise ratio index, and feedback type; scheduling a station to send feedback upon receiving a feedback request, when polled by the access point in a cascading manner, or at a time provided by the access point; and / or sending requests in a first bandwidth or a second bandwidth, a subset of the first bandwidth, to at least one of the plurality of stations to send channel information based on the feedback response. The access point processor may be programmed using instructions to perform any access point description herein. Simple Explanation of the Diagram

[0011] Figure 1A is a system diagram of an example communication system in which one or more of the disclosed features may be implemented. Figure 1B illustrates an example wireless transmit / receive unit (WTRU). Figure 1C illustrates an exemplary wireless local area network (WLAN) device. Figure 2 shows an example of OFDMA numerology used for 20 MHz building blocks. Figure 3 shows an example of OFDMA digitization used for 40 MHz building blocks. Figure 4 shows an example of OFDMA digitization used for 80 MHz building blocks. Figure 4A shows an example of a resource unit. Figure 5 shows an example of the VHT variable HT control field in MCS feedback in 802.11ac. Figure 5A shows an example of a bottom-chain detection sequence. Figure 6 shows an example of the power spectral density for a partially loaded OFDM signal with RF I / Q imbalance. Figure 7 shows an example of bit error rate (BER) performance for interference signals. Figure 8 shows an example of a 20 MHz BSS allocation with RU allocation labels. Figure 9 shows an example of feedback granularity at the receiver. Figures 9A, 9B, or 9C show examples related to feedback and / or granularity. Figure 10 shows an example of MCS feedback frame 1. Figure 11 shows an example of MCS feedback frame 2. Figure 12 shows an example of RU granularity. Figure 13 shows an example of receiver granularity with multi-RU scheduling granularity. Figure 14 shows the scheduled transport volume for four examples of the scenarios in Figure 13. Figure 14A shows an example of scheduling gain with different bit quantization. Figure 15 shows an example of entropy coding. Figure 16 shows an example of a simplified RU designation. Figure 17 shows an example of a hierarchical RU labeling structure. Figure 18 shows an example of hierarchical feedback with layer constraints. Figure 19 shows an example of hierarchical feedback without layer restrictions. Figures 20A and 20B show examples of NDP / NDPA CSI feedback. Figure 21 shows an example of a modified NDPA frame. Figure 22 shows an example of a unified CSI feedback frame. Figure 23 shows an example of the MU control field. Figure 24 shows an example of the MU CSI report fields. Figure 25 shows an example of the MU SINR report field. Figure 26 shows an example of symmetric RU allocation. Figure 27 shows an example of multi-stage CSI feedback with a scheduling stage 1 / 2 trigger frame and no explicit downlink data trigger frame. Figure 28 shows an example of multi-stage CSI feedback with a scheduling stage 1 / 2 trigger frame and an explicit downlink data trigger frame. Figure 29 shows an example of a multi-stage CSI feedback with scheduling and random access stage 1 and 2 trigger frames but no explicit downlink data trigger frame. Figure 30 shows an example of a multi-stage CSI feedback with scheduling and random access stage 1 and 2 trigger frames and no downlink data transmission. Figure 31 shows an example of feedback saving. Implementation

[0012] The exemplary embodiments are described in detail below with reference to the accompanying drawings. While this description provides detailed examples of possible embodiments, it should be understood that these details are intended to be exemplary and do not limit the scope of this work.

[0013] Figure 1A is a diagram of an example communication system 100 in which one or more of the disclosed features may be implemented. For example, a wireless network (e.g., a wireless network including one or more elements of the communication system 100) may be configured such that bearers extending under the wireless network (e.g., under a walled garden associated with the wireless network) may be assigned QoS characteristics.

[0014] Communication system 100 can be a multiple access system that provides content such as voice, data, video, messages, and broadcasts to multiple wireless users. Communication system 100 can enable multiple wireless users to access this content through the sharing of system resources (including wireless bandwidth). For example, communication system 100 can use one or more channel access methods, such as Code Division Multiple Access (CDMA), Time Division Multiple Access (TDMA), Frequency Division Multiple Access (FDMA), Orthogonal FDMA (OFDMA), Single Carrier FDMA (SC-FDMA), etc.

[0015] As shown in Figure 1A, the communication system 100 may include at least one wireless transmit / receive unit (WTRU) (such as multiple WTRUs, e.g., WTRUs 102a, 102b, 102c, and 102d), a radio access network (RAN) 104, a core network 106, a public switched telephone network (PSTN) 108, an internet 110, and other networks 112. However, it is understood that the disclosed embodiments may cover any number of WTRUs, base stations, networks, and / or network elements. Each of WTRUs 102a, 102b, 102c, and 102d may be any type of device configured to operate and / or communicate in a wireless environment. As examples, WTRU 102a, 102b, 102c, and 102d can be configured to transmit and / or receive wireless signals and can include user equipment (UE), mobile station, fixed or mobile user unit, pager, mobile phone, personal digital assistant (PDA), smartphone, portable computer, portable eNet device, personal computer, wireless sensor, consumer electronics, etc.

[0016] The communication system 100 may also include base stations 114a and 114b. Each of base stations 114a and 114b may be any type of device configured to wirelessly interact with at least one of WTRUs 102a, 102b, 102c, and 102d to access one or more communication networks (e.g., core network 106, internet 110, and / or network 112). For example, base stations 114a and 114b may be base transceiver stations (BTS), node B, e-node B, home node B, home e-node B, site controllers, access points (APs), wireless routers, and similar devices. Although each of base stations 114a and 114b is described as a single element, it is understood that base stations 114a and 114b may include any number of interconnected base stations and / or network elements.

[0017] Base station 114a may be part of RAN 104, which may also include other base stations and / or network elements (not shown), such as a site controller (BSC), radio network controller (RNC), and relay nodes. Base station 114a and / or base station 114b may be configured to transmit and / or receive radio signals within a specific geographic area, which may be referred to as a cell (not shown). A cell may also be divided into cell sectors. For example, a cell associated with base station 114a may be divided into three sectors. Thus, in one embodiment, base station 114a may include three transceivers, i.e., one transceiver for each sector of the cell. In another embodiment, base station 114a may use multiple-input multiple-output (MIMO) technology, and thus may use multiple transceivers for each sector of the cell.

[0018] Base stations 114a and 114b can communicate with one or more of WTRUs 102a, 102b, 102c, and 102d via an air interface 116, which can be any suitable wireless communication link (e.g., radio frequency (RF), microwave, infrared (IR), ultraviolet (UV), visible light, etc.). The air interface 116 can be established using any suitable radio access technology (RAT).

[0019] More specifically, as previously described, the communication system 100 can be a multiple access system and can use one or more channel access schemes, such as CDMA, TDMA, FDMA, OFDMA, SC-FDMA, and similar schemes. For example, base stations 114a and WTRUs 102a, 102b, and 102c in RAN 104 can implement radio technologies such as Universal Mobile Telecommunications System (UMTS) Terrestrial Radio Access (UTRA), which can use wideband CDMA (WCDMA) to establish an air interface 116. WCDMA can include technologies such as High-Speed ​​Packet Access (HSPA) and / or Evolved HSPA (HSPA+). HSPA can include High-Speed ​​Downlink Packet Access (HSDPA) and / or High-Speed ​​Uplink Packet Access (HSUPA).

[0020] In another embodiment, base stations 114a and WTRUs 102a, 102b, 102c may implement radio technologies such as Evolved UMTS Terrestrial Radio Access (E-UTRA), which may use Long Term Evolution (LTE) and / or LTE-Advanced (LTE-A) to establish an airspace intermediate plane 116.

[0021] In other implementations, base station 114a and WTRUs 102a, 102b, and 102c may implement radio technologies such as IEEE 802.16 (i.e., WiMAX), CDMA2000, CDMA2000 1x, CDMA2000 EV-DO, Provisional Standard 2000 (IS-2000), Provisional Standard 95 (IS-95), Provisional Standard 856 (IS-856), Global System for Mobile Communications (GSM), Enhanced Data Rate GSM Evolution (EDGE), and GSM EDGE (GERAN).

[0022] For example, base station 114b in Figure 1A can be a wireless router, home node B, home e-node B, or access point, and can use any suitable RAT to facilitate wireless connectivity in localized areas such as offices, homes, vehicles, or campuses. In one implementation, base station 114b and WTRUs 102c and 102d can implement radio technologies such as IEEE 802.11 to establish a wireless local area network (WLAN). In another implementation, base station 114b and WTRUs 102c and 102d can implement radio technologies such as IEEE 802.15 to establish a wireless personal area network (WPAN). In yet another implementation, base station 114b and WTRUs 102c and 102d can use cellular-based RATs (e.g., WCDMA, CDMA2000, GSM, LTE, LTE-A, etc.) to establish picocells and femtocells. As shown in Figure 1A, base station 114b can have a direct connection to Internet 110. Therefore, base station 114b does not need to access Internet 110 through core network 106.

[0023] RAN 104 can communicate with core network 106, which can be any type of network configured to provide voice, data, application, and / or Voice over Internet Protocol (VoIP) services to one or more of WTRUs 102a, 102b, 102c, and 102d. For example, core network 106 can provide call control, billing services, location-based services, prepaid calling, internet connectivity, video distribution, and / or perform advanced security functions such as user authentication. Although not shown in Figure 1A, it should be understood that RAN 104 and / or core network 106 can communicate directly or indirectly with other RANs, which may use the same RAT as RAN 104 or a different RAT. For example, in addition to connecting to RAN 104, which may employ E-UTRA radio technology, core network 106 can also communicate with other RANs (not shown) using GSM radio technology.

[0024] Core network 106 may also act as a gateway for WTRUs 102a, 102b, 102c, and 102d to access PSTN 108, Internet 110, and / or other networks 112. PSTN 108 may include a circuit-switched telephone network providing Common Old-Style Telephone Service (POTS). Internet 110 may include a global system interconnecting computer networks and devices using common communication protocols such as Transmission Control Protocol (TCP) / Internet Protocol (IP) suite, including TCP, User Data Packet Protocol (UDP), and IP. Network 112 may include wireless or wired communication networks owned and / or operated by other service providers. For example, network 112 may include another core network connected to one or more RANs, which may use the same RAT as RAN 104 or a different RAT.

[0025] One or more, or all of the WTRUs 102a, 102b, 102c, and 102d in the communication system 100 may include multi-mode capability, meaning that WTRUs 102a, 102b, 102c, and 102d may include multiple transceivers for communicating with different wireless networks via different wireless links. For example, WTRU 102c shown in Figure 1A may be configured to communicate with base station 114a using cellular-based radio technology and with base station 114b using IEEE 802 radio technology.

[0026] Figure 1B illustrates an exemplary wireless transmit / receive unit WTRU 102. WTRU 102 can be used in one or more communication systems described below. As shown in Figure 1B, WTRU 102 may include a processor 118, a transceiver 120, a transmit / receive element 122, a speaker / microphone 124, a keyboard 126, a display / touchpad 128, non-removable memory 130, removable memory 132, a power supply 134, a Global Positioning System (GPS) chipset 136, and other peripheral devices 138. It should be understood that, while consistent with the above embodiments, WTRU 102 may include any subset of the above-described elements.

[0027] Processor 118 may be a general-purpose processor, a special-purpose processor, a conventional processor, a digital signal processor (DSP), multiple microprocessors, one or more microprocessors associated with a DSP core, a controller, a microcontroller, an application-specific integrated circuit (ASIC), a field-programmable gate array (FPGA) circuit, any other type of integrated circuit (IC), a state machine, etc. Processor 118 may perform signal encoding, data processing, power control, input / output processing, and / or any other function that enables WTRU 102 to operate in a wireless environment. Processor 118 may be coupled to transceiver 120, which may be coupled to transmit / receive element 122. Although processor 118 and transceiver 120 are described as separate components in Figure 1B, it is understood that processor 118 and transceiver 120 may be integrated together into an electronic package or chip.

[0028] The transmitting / receiving element 122 can be configured to transmit signals to or receive signals from a base station (e.g., base station 114a) via the air interface 116. For example, in one embodiment, the transmitting / receiving element 122 can be an antenna configured to transmit and / or receive RF signals. In another embodiment, the transmitting / receiving element 122 can be a transmitter / detector configured to transmit and / or receive, for example, IR, UV, or visible light signals. In yet another embodiment, the transmitting / receiving element 122 can be configured to transmit and receive both RF signals and optical signals. It should be understood that the transmitting / receiving element 122 can be configured to transmit and / or receive any combination of wireless signals.

[0029] Furthermore, although the transmit / receive element 122 is depicted as a single element in Figure 1B, the WTRU 102 may include any number of transmit / receive elements 122. More specifically, the WTRU 102 may use MIMO technology. Thus, in one embodiment, the WTRU 102 may include two or more transmit / receive elements 122 (e.g., multiple antennas) for transmitting and receiving wireless signals via the air interface 116.

[0030] Transceiver 120 can be configured to modulate signals to be transmitted by transmit / receive element 122 and to demodulate signals received by transmit / receive element 122. As described above, WTRU 102 can have multi-mode capability. Thus, transceiver 120 can include multiple transceivers to enable WTRU 102 to communicate via multiple RATs such as UTRA and IEEE 802.11.

[0031] The processor 118 of WTRU 102 can be coupled to a speaker / microphone 124, a keyboard 126, and / or a display / touchpad 128 (e.g., a liquid crystal display (LCD) unit or an organic light-emitting diode (OLED) display unit) and can receive user input data from the aforementioned devices. The processor 118 can also output data to the speaker / microphone 124, the keyboard 126, and / or the display / touchpad 128. Furthermore, the processor 118 can access information from any type of suitable memory and store data in any type of suitable memory, such as non-removable memory 130 and / or removable memory 132. Non-removable memory 130 can include random access memory (RAM), read-only memory (ROM), a hard disk, or any other type of memory storage device. Removable memory 132 can include a SIM card, a memory stick, a secure SD card, or similar devices. In other embodiments, the processor 118 may access data from memory that is not physically located on the WTRU 102, for example, on a server or home computer (not shown), and store data in the aforementioned memory.

[0032] The processor 118 can receive power from the power supply 134 and can be configured to distribute power to other components in the WTRU 102 and / or control the power to other components in the WTRU 102. The power supply 134 can be any device suitable for powering the WTRU 102. For example, the power supply 134 may include one or more dry cell batteries (NiCd, NiZn, NiMH, Li-ion, etc.), solar cells, fuel cells, etc.

[0033] The processor 118 may also be coupled to a GPS chipset 136, which may be configured to provide location information (e.g., longitude and latitude) about the current location of the WTRU 102. As a supplement to or alternative to the information from the GPS chipset 136, the WTRU 102 may receive location information from base stations (e.g., base stations 114a, 114b) via an air interface 116 and / or determine its location based on the timing of signals received from two or more adjacent base stations. It should be understood that, consistent with the implementation method, the WTRU 102 may use any suitable location determination method to obtain location information.

[0034] The processor 118 may also be coupled to other peripheral devices 138, which may include one or more software and / or hardware modules that provide additional features, functionality, and / or wireless or wired connectivity. For example, peripheral devices 138 may include accelerometers, e-compasses, satellite transceivers, digital cameras (for photos or videos), Universal Serial Bus (USB) ports, vibration devices, television transceivers, hands-free headsets, Bluetooth® modules, FM radio units, digital music players, media players, video game player modules, internet browsers, and so on.

[0035] Figure 1C illustrates an exemplary Wireless Local Area Network (WLAN) apparatus. One or more apparatuses may be used to implement one or more features described herein. The WLAN includes, but is not limited to, Access Point (AP) 102, Station (STA) 110, and STA 112. STA 110 and 112 are associated with the AP. The WLAN may be configured to implement one or more protocols in the IEEE 802.11 communication standard, which may include channel access mechanisms such as DSSS, OFDM, OFDMA, etc. The WLAN may operate in modes such as infrastructure mode, ad-hoc mode, etc.

[0036] A WLAN operating in infrastructure mode may include one or more APs communicating with one or more associated STAs. APs and associated STAs may include a Basic Service Set (BSS). For example, AP 102, STA 110, and STA 112 may include BSS 122. An Extended Service Set (ESS) may include one or more APs (each with one or more BSSs) and associated STAs. APs may have access and / or interfaces to a wired and / or wireless Distribution System (DS) 116 and transmit traffic to and / or from the AP. Traffic originating outside the WLAN and destined for STAs within the WLAN can be received at an AP within the WLAN, which can then transmit the traffic to the STAs within the WLAN. Traffic originating from STAs within the WLAN and destined for a destination outside the WLAN (e.g., to server 118) can be transmitted to an AP within the WLAN, which can then transmit the traffic to the destination, for example, via DS 116 to network 114, and thus to server 118. Traffic between STAs within the WLAN can be transmitted via one or more APs. For example, a source STA (e.g., STA 10) may have traffic intended for a destination STA (e.g., STA 112). STA 110 may send traffic to AP 102, and AP 102 may send traffic to STA 112.

[0037] WLAN can operate in ad-hoc mode. Ad-hoc mode WLAN can be called Independent Basic Service Set (IBBS). In ad-hoc mode WLAN, STAs can communicate directly with each other (for example, STA 110 can communicate with STA 112, and this communication is not routed through the AP).

[0038] IEEE 802.11 devices (such as IEEE 802.11 APs in a BSS) can use beacon frames to announce the presence of a WLAN network. For example, an AP like AP 102 can transmit beacons on a fixed channel (such as the main channel). STAs can use a channel such as the main channel to establish a connection with the AP.

[0039] STAs and / or APs can use a carrier sense multiple access (CSMA / CA) channel access mechanism with collision avoidance. In CSMA / CA, STAs and / or APs can sense the primary channel. For example, if a STA has no data to transmit, it can sense the primary channel. If the primary channel is detected as busy, the STA postpones. For example, a WLAN or a portion thereof can be configured so that a STA can transmit, for example, at a given time within a given BSS. Channel access can include RTS and / or CTS communication. For example, the exchange of Request to Transmit (RTS) frames can be transmitted by the transmitting device, and Clear to Transmit (CTS) frames can be transmitted by the receiving device. For example, if an AP has data to send to a STA, the AP can send an RTS frame to the STA. If the STA is ready to receive data, the STA can respond with a CTS frame. The CTS frame can include a time value that can warn other STAs to hold off on accessing the medium while the AP that initiated the RTS can transmit its data. Upon receiving a CTS frame from a STA, the AP can send data to the STA.

[0040] Devices can reserve spectrum via the Network Allocation Vector (NAV) field. For example, in an IEEE 802.11 frame, the NAV field can be used to reserve a channel for a period of time. STAs wishing to transmit data can set the NAV to indicate the time they wish to use the channel. When a STA sets the NAV, it can be set for the associated WLAN or a subset thereof (such as a BSS). Other STAs can count down from the NAV to zero. When the counter reaches zero, the NAV function indicates to other STAs that the channel is now available.

[0041] Devices in a WLAN (e.g., APs or STAs) may include one or more of the following: a processor, memory, a radio receiver and / or transmitter (e.g., which may be integrated into a transceiver), one or more antennas (e.g., antenna 106 in Figure 1C), etc. Processor functionality may include one or more processors. For example, a processor may include one or more of the following: a general-purpose processor, a special-purpose processor (e.g., a baseband processor, a MAC processor, etc.), a digital signal processor (DSP), an application-specific integrated circuit (ASIC), a field-programmable gate array (FPGA) circuit, any other type of integrated circuit (IC), a state machine, etc. One or more processors may be integrated with each other or not. A processor (e.g., one or more processors or a subset thereof) may be integrated with one or more other functions (e.g., other functions such as memory). A processor may perform signal decoding, data processing, power control, input / output processing, modulation, demodulation, and / or any other function that enables the device to operate in a wireless environment (e.g., a WLAN in Figure 1C). A processor may be configured to execute processor-executable code (e.g., instructions), including, for example, software and / or firmware instructions. For example, a processor can be configured to execute computer-readable instructions included on one or more processors (e.g., a chip including memory and a processor) or memory. Execution of the instructions can cause the device to perform one or more functions described herein.

[0042] The device may include one or more antennas. The device may use multiple-input multiple-output (MIMO) technology. The one or more antennas may receive radio signals. The processor may receive radio signals, for example, via the one or more antennas. The one or more antennas may transmit radio signals (e.g., based on signals sent from the processor).

[0043] The device may have one or more memory units, which may include programmable and / or data such as processor executable code or instructions (e.g., software firmware), electronic data, databases, or other digital information. The memory unit may include one or more memory cells. The one or more memory cells may be integrated with one or more other functions (e.g., other functions included in a device such as a processor). The memory unit may include read-only memory (ROM) (e.g., erasable programmable read-only memory (EPROM), electrically erasable programmable read-only memory (EEPROM), etc.), random access memory (RAM), magnetic storage media, optical storage media, flash memory devices, and / or other non-transitory computer-readable media for storing information. The memory unit may be coupled to a processor. The processor may communicate with one or more memory units, for example, directly via a system bus.

[0044] A system, method, and means for unified feedback for OFDMA WLAN are disclosed. Unified feedback can be provided by per-RU based MCS feedback, per-RU based CSI feedback, and / or feedback with symmetrical RU allocation.

[0045] Wireless Local Area Networks (WLANs) can operate in various modes, such as Infrastructure Basic Services Set (BSS) mode and Standalone BSS (IBSS) mode. In BSS mode, a WLAN can have Access Points (APs) for the BSS. One or more Stations (STAs) can be associated with an AP. The AP can have access or interfaces to a Distribution System (DS) or other types of wired / wireless networks, carrying traffic both within and outside the BSS. Traffic originating outside the BSS and destined for a STA can arrive via an AP that can deliver the traffic to the STA. Traffic originating from a STA and destined for a destination outside the BSS can be sent to an AP that can deliver the traffic to its respective destination. Traffic between STAs within the BSS can be transmitted via APs, for example, from a source STA to an AP and from an AP to a destination STA. Traffic between STAs within the BSS can be end-to-end traffic. End-to-end traffic can be transmitted directly between source and destination STAs, for example, using Direct Link Establishment (DLS) with 802.11e DLS or 802.11z Tunneling DLS (TDLS). In Standalone BSS (IBSS) mode, a WLAN may not have an access point (AP), and STAs can communicate directly with each other. IBSS communication mode can be referred to as "ad-hoc" communication mode.

[0046] The AP can, for example, transmit beacons on a fixed channel (e.g., the primary channel) in 802.11ac infrastructure operating mode. The channel can be, for example, 20 MHz wide. The channel can be the operating channel of the BSS. The channel can be used by STAs to, for example, establish a connection with the AP. The channel access mechanism in the 802.11 system is Carrier-Sense Multiple Access with Collision Avoidance (CSMA / CA). STAs, including the AP, can, for example, sense the primary channel in CSMA / CA operating mode. STAs can, for example, shift back when the channel is detected as busy so that only one STA can transmit within a given BSS time.

[0047] High throughput (HT) STAs can use, for example, a 40 MHz wide channel for communication, such as in 802.11n. The primary 20 MHz channel can be combined with an adjacent 20 MHz channel to form a 40 MHz wide continuous channel.

[0048] Very High Transmission Capability (VHT) STAs can, for example, support wide channels of 20 MHz, 40 MHz, 80 MHz, and 160 MHz in 802.11ac. 40 MHz and 80 MHz channels can be formed, for example, by combining consecutive 20 MHz channels. A 160 MHz channel can be formed, for example, by combining eight consecutive 20 MHz channels or by combining two non-consecutive 80 MHz channels, which can be referred to as an 80+80 configuration. The 80+80 configuration can be achieved through a segmented resolver, which, for example, divides the data into two streams after channel coding. Inverse Fast Fourier Transform (IFFT) and time-domain processing can be performed, for example, separately for each stream. Streams can be mapped to two channels. Data can be transmitted on both channels. The receiver can be the inverse of the transmitter mechanism. The receiver can reassemble the data transmitted on multiple channels. The reassembled data can be sent to the Media Access Control (MAC).

[0049] Sub-GHz (e.g., MHz) operating modes can be supported, for example, by 802.11af and 802.11ah. Channel operating bandwidth and carrier can be reduced, for example, by the relative bandwidth and carrier used in 802.11n and 802.11ac. 802.11af can support, for example, 5 MHz, 10 MHz, and 20 MHz bandwidths in the TV whitespace (TVWS) spectrum. 802.11ah can support, for example, 1 MHz, 2 MHz, 4 MHz, 8 MHz, and 16 MHz in the non-TVWS spectrum. An example of 802.11ah usage is to support meter type control (MTC) devices in macro coverage areas. MTC devices have limited capabilities (e.g., limited bandwidth) and can be designed to have very long battery life.

[0050] WLAN systems (such as 802.11n, 802.11ac, 802.11af, and 802.11ah systems) can support multiple channels and channel bandwidths, such as a channel designated as the primary channel. The primary channel can, for example, have a bandwidth equal to the maximum common operating bandwidth supported by STAs in the BSS. The bandwidth of the primary channel can be limited by STAs supporting the minimum bandwidth operating mode. In the 802.11ah example, for instance, when one or more STAs (e.g., MTC type devices) support the 1 MHz mode while the AP and other STAs support 2 MHz, 4 MHz, 8 MHz, 16 MHz, or other channel bandwidth operating modes, the primary channel can be 1 MHz wide. Carrier sensing and NAV settings can depend on the state of the primary channel. As an example, for instance, when the primary channel is busy because STAs supporting the 1 MHz operating mode are transmitting to the AP on the primary channel, all available frequency bands can be considered busy and kept idle despite their availability.

[0051] Available frequency bands can vary between different regions. For example, in the United States, the available frequency bands used by 802.11ah are 902 MHz to 928 MHz, in South Korea 917.5 MHz to 923.5 MHz, and in Japan 916.5 MHz to 927.5 MHz. Total available bandwidth can also vary between different regions. For example, the total available bandwidth for 802.11ah can range from 6 MHz to 26 MHz, depending on the country code.

[0052] Spectral efficiency can be improved, for example, by downlinked multiple-user multiple-input multiple-output (MU-MIMO) transmissions to multiple STAs within the same symbol time frame (e.g., during the downlinked OFDM symbol period). Downlinked MU-MIMO can be implemented, for example, in 802.11ac and 802.11ah. For example, when downlinked MU-MIMO uses the same symbol timing to multiple STAs, waveform transmission interference to multiple STAs can be avoided. The operating bandwidth of MU-MIMO transmission can be limited to the minimum channel bandwidth supported by the STAs performing MU-MIMO transmissions with the AP, for example, when the STAs involved in the MU-MIMO transmission with the AP use the same channel or band.

[0053] IEEE 802.11™ High-Efficiency WLAN (HEW), also known as HE, enhances the Quality of Service (QoS) experience for wireless users in many use cases, such as high-density deployments of APs and STAs in the 2.4 GHz and 5 GHz bands. HEW Radio Resource Management (RRM) technology can support a variety of applications and use cases, such as data delivery for stadium events, high-user-density scenarios like train stations or corporate / retail environments, and video delivery and wireless services for medical applications. HEW can be implemented, for example, in IEEE 802.11ax.

[0054] Short packets generated by network applications can be used in a variety of applications, such as virtual offices, TPC acknowledgments (ACK), video streaming ACK, devices / controllers (e.g., mouse, keyboard, game controls), access (e.g., probe requests / responses), network selection (e.g., probe requests, Access Query Protocol (ANQP)), and network management (e.g., control frames).

[0055] For example, MU features such as uplink (UL) and downlink (DL) orthogonal frequency division multiple access (OFDMA) and UL and DL MU-MIMO can be implemented in 802.11ax. OFDMA can develop channel selectivity to, for example, improve or maximize frequency selection multiplexing gain in dense network conditions. Mechanisms can be designed and defined for feedback to, for example, enable fast link adaptation, frequency selection scheduling, and resource unit-based feedback.

[0056] OFDMA digitization for HEW can be provided. OFDMA building blocks can be, for example, 20 MHz, 40 MHz, and 80 MHz.

[0057] Figure 2 shows an example of OFDMA digitization for a 20 MHz building block. A 20 MHz OFDMA building block can be defined, for example, with 2 pilots for 26 tones, 4 pilots for 52 tones, and 4 pilots for 106 tones. As an example, at the location shown in Figure 2, there can be 7 DC empty spaces and (6,5) guard tones (e.g., 6 guard tones on the upper left side and 5 guard tones on the upper right side). The OFDMA PPDU can carry a mixture of different tone unit sizes within the boundaries of 242 tone units.

[0058] Figure 3 shows an example of OFDMA digitization for a 40 MHz building block. A 40 MHz OFDMA building block can be defined as, for example, 2 pilots with 26 tones, 4 pilots with 52 tones, 4 pilots with 106 tones, and 8 pilots with 242 tones. As an example, for instance, at the location shown in Figure 3, there can be 5 DC empty spaces and (12,11) guard tones.

[0059] Figure 4 shows an example of OFDMA digitization for an 80 MHz building block. An 80 MHz OFDMA building block can be defined, for example, with 2 pilots for 26 tones, 4 pilots for 52 tones, 4 pilots for 106 tones, 8 pilots for 242 tones, and 16 pilots for 484 tones. As an example, for instance, at the location shown in Figure 4, there can be 7 DC empty spaces and (12,11) guard tones.

[0060] Figure 4A shows an example of resource unit 402. A resource unit (RU) can be a collection of resources (e.g., tones) that include temporal and spatial allocations. A resource unit can be defined to describe a minimum feedback granularity smaller than a specific bandwidth (e.g., 20 MHz). Similarly, the definition of an RU can include tones allocated on a specific spatial / frequency block in OFDMA digitization.

[0061] One or more of the following can be provided: a traditional Short Training Field (STF), a Long Training Field (LTF), and a Signal (SIG) Field. High-Efficiency (HE) SIG-A and SIG-B designs can also be provided.

[0062] HE PLCP (Physical Layer Overlay Protocol) Protocol Data Units (PPDUs) may include legacy (L) preambles (e.g., L-STF, L-LTF, and L-SIG), which can be copied on every 20 MHz block for, for example, backward compatibility with legacy devices.

[0063] HE-SIG-A can be replicated, for example, every 20 MHz block after the conventional preamble to indicate common control information. As an example, HE-SIG-A can be implemented using a 3.2 µs Discrete Fourier Transform (DFT) time period and a 312.5 kHz subcarrier spacing.

[0064] HE-SIG-B can be implemented using a 3.2µs DFT period and a 312.5kHz subcarrier spacing resource configuration in other technologies.

[0065] Feedback methods in 3GPP Long Term Evolution (LTE) may include, for example, depending on the feedback mode, a combination of Channel Quality Indicator (CQI), Precoding Matrix Indicator (PMI), and Rank Indicator (RI) sent back by the WTRU.

[0066] Feedback can be periodic or non-periodic. In periodic reporting, WTRU can report CQI, PMI, and / or RI. WTRU can report using a reporting cycle, which can be configured by a higher layer. Feedback can be transmitted on the Entity On-Chain Control Channel (PUCCH). Below are examples of CQI and PMI feedback types used in PUCCH reporting mode. [surface] [1]: used for [PUCCH] Reporting Mode [CQI] and [PMI] Feedback Type [PMI] Feedback Type [No] PMI [Single] PMI [PUCCH CQI] Feedback Type [broadband] [(]broadband [CQI] Mode 1-0 Mode 1-1 [Selected] WTRU [(] Subband [CQI] Mode 2-0 Mode 2-1

[0067] The transmission mode can be: Transmission Mode 1: Mode 1-0, 2-0 Transmission Mode 2: Mode 1-0, 2-0 Transmission Mode 3: Mode 1-0, 2-0 Transmission mode 4: Mode 1-1, 2-1 Transmission mode 5: Mode 1-1, 2-1 Transmission Mode 6: Mode 1-1, 2-1 Transmission Mode 7: Mode 1-0, 2-0 Transmission mode 8: Mode 1-1, 2-1, if the WTRU is configured with PMI / RI reporting; Mode 1-0, 2-0, if the WTRU is not configured with PMI / RI reporting. Transmission mode 9: Mode 1-1, 2-1, if the WTRU is configured with PMI / RI reporting and the number of CSI-RS ports is >1; Mode 1-0, 2-0, if the WTRU is not configured with PMI / RI reporting or the number of CSI-RS ports is 1. Transmission mode 10: Mode 1-1, 2-1, if the WTRU is configured with PMI / RI reporting and the number of CSI-RS ports is >1; Mode 1-0, 2-0, if the WTRU is not configured with PMI / RI reporting or the number of CSI-RS ports is 1.

[0068] In non-periodic reporting, WTRU can provide more detailed information within a single reporting instance. Feedback can be transmitted on the entity's on-chain shared channel (PUSCH), and reporting timing can be triggered by off-chain control information (DCI). Examples of CQI and PMI feedback types used in the PUSCH reporting mode are shown below. [surface] [2]: used for [PUSCH] Reporting Mode [CQI] and [PMI] Feedback Type [PMI] Feedback Type [No] PMI [Single] PMI [Multiple] PMIs PUSCH CQI [ ] Feedback type [broadband] [(]broadband [CQI] Mode 1-2 [Selected] WTRU [(] Subband [CQI] Mode 2-0 Mode 2-2 [Higher-level configuration] [(] Subband [CQI] Mode 3-0 Mode 3-1

[0069] The transmission mode can be: Transmission Mode 1: Mode 2-0, 3-0 Transmission Mode 2: Mode 2-0, 3-0 Transmission Mode 3: Mode 2-0, 3-0 Transmission Mode 4: Modes 1-2, 2-2, 3-1 Transmission Mode 5: Mode 3-1 Transmission Mode 6: Modes 1-2, 2-2, 3-1 Transmission Mode 7: Mode 2-0, 3-0 Transmission mode 8: Mode 1-2, 2-2, 3-1, if WTRU is configured with PMI / RI reporting; Mode 2-0, 3-0, if WTRU is not configured with PMI / RI reporting. Transmission mode 9: Mode 1-2, 2-2, 3-1, if the WTRU is configured with PMI / RI reporting and the number of CSI-RS ports is >1; Mode 2-0, 3-0, if the WTRU is not configured with PMI / RI reporting or the number of CSI-RS ports is 1. Transmission mode 10: Mode 1-2, 2-2, 3-1, if the WTRU is configured with PMI / RI reporting and the number of CSI-RS ports is >1; Mode 2-0, 3-0, if the WTRU is not configured with PMI / RI reporting or the number of CSI-RS ports is 1.

[0070] The extension of the CQI / PMI / RI feedback mode can be used for aperiodic PUSCH and periodic PUCCH. In PUSCH and PUCCH feedback, the precoder for the subband can include two matrices, each belonging to a separate codebook, and the codebook is known (or synchronized) at e-node B and WTRU. The codebook index can determine the precoder, for example, where one of the two matrices targets broadband and / or long-term channel attributes, while the other targets frequency selection and / or short-term channel attributes. Precoding feedback can be considered a specific case of this structure.

[0071] WiMax (Global Interoperability Microwave Access) feedback methods can include codebook-based feedback and quantized channel feedback.

[0072] WiMax can support codebook-based feedback, where WTRUs (e.g., mobile stations (MS)) use predefined codebook entries to indicate to base stations (BSs) the optimal precoding matrix to be used.

[0073] WiMax can support quantized channel feedback, where the WTRU (e.g., MS) can quantize a multiple-input multiple-output (MIMO) channel and send this information to the BS using a MIMO_FEEDBACK message. The BS can then use the quantized MIMO channel to, for example, compute the optimal precoding matrix.

[0074] 802.11 feedback methods may include Modulation and Coding Scheme (MCS) feedback and Channel Status Information (CSI) feedback. In MCS feedback, the WTRU (e.g., a station (STA)) may send back (e.g., unrequested or requested) the MCS, signal-to-noise ratio (SNR), and number of spatial-temporal streams (N_STS). Feedback can be provided in the VHT variable HT control field as shown in Figure 5.

[0075] Figure 5 shows an example of the Very High Delivery (VHT) variable in the High Delivery (HT) control field of the MCS feedback in 802.11ac. The fields in the HT control field include the following.

[0076] A VHT field (e.g., 1 bit) can indicate that an HT control field is of type VHT variable.

[0077] The MCS Request (MRQ) field (e.g., 1 bit) can indicate a feedback request.

[0078] The MRQ Sequence Indicator (MSI) Spatial-Time Block Code (STBC) field (e.g., 3 bits) can indicate the MRC Sequence Indicator or MCS Feedback Request.

[0079] The MCS Feedback Sequence Identifier (MFSI) / General Interference Detection and Location (GID-L) field (e.g., 3 bits) can indicate the MCS Feedback Sequence Identifier, such as the sequence identifier of the MSI that this frame responds to.

[0080] The MCS Feedback (MFB) field (e.g., 15 bits) can include Num_STS, MCS, bandwidth, and SNR feedback. The number of spatial-time streams (NUM_STS) indicates the recommended number of spatial-time streams. NUM_STS can be an unsigned integer representing the number of STS minus one. MCS indicates the recommended MCS. MCS can be an unsigned integer, such as within the range of 0 to 9. BW can include the bandwidth of the recommended MCS; for example, 0 can indicate 20 MHz, 1 can indicate 40 MHz, 2 can indicate 80 MHz, and 3 can indicate 160 MHz and 80+80 MHz. SNR feedback can include the average SNR over the data subcarriers and spatial-time streams. This SNR can be encoded as the number of 6-bit binary complements of SNR_average – 22.

[0081] The Group ID (High) (GID-H) field (e.g., 3 bits) can include the most significant bit (MSB) of the group ID from the PPDU used to estimate the unrequested MFB, such as the highest three bits. For example, when the MFB is estimated from the SU-PPDU, GID-H can be set to all bits as one.

[0082] The encoding type field can include encoding information used to estimate PPDUs that have not requested an MFB (e.g., 0 can indicate BCC, and 1 can indicate LDPC).

[0083] For example, when MFB is Unrequested MFB, the Unrequested MFB field can be set to 1.

[0084] STAs can send explicit feedback about the channel, for example, in Channel Status Information (CSI) feedback. CSI channel feedback can include, for example, the actual channel coefficient, uncompressed BF coefficient and STS SNR, compressed BF coefficient and STS SNR, where compression can be based on Givens rotation.

[0085] For example, detection methods for 802.11ax can be used. The 802.11ax framework can include a CSI feedback mechanism. The CSI feedback mechanism can allow feedback granularity, which can be a minimum feedback granularity (e.g., less than 20 MHz). The 802.11ax framework can have a mechanism enabling multiplexing of compressed beamforming action frames (e.g., CSI feedback) from multiple stations using, for example, UL MU (MIMO or OFDMA) modes. The 802.11ax framework can have a channel detection sequence. The channel detection sequence can include trigger information to facilitate UL MU mode compressed beamforming action frames from multiple STAs. Figure 5A shows an example of a downlink (DL) detection sequence.

[0086] CSI-based WiFi feedback can be improved by one or more of the following: (i) line-of-sight / non-line-of-sight (LOS / NLOS) multi-component feedback, such as primary and other intrinsic (Eigen) modes; (ii) feedback based on improved Givens rotation to reduce feedback load; (iii) codebook design for new antenna geometry; (iv) time-domain and hybrid implicit / explicit feedback, time / frequency feedback; (v) hybrid implicit / explicit feedback; (vi) preamble design for channel smoothing; (vii) receiver processing for channel smoothing; (viii) inequality protection of feedback bits; and (ix) differential feedback, such as Givens-based feedback, transmitting at different angles between current and previous feedback instances.

[0087] Using OFDMA in the BSS for RU-based MCS and CSI request processing can be complex. The BSS can request MCS or CSI information from RUs, subsets of RUs, and all RUs in a band. Operation using SU-MIMO or MU-MIMO may result in SU-MIMO or MU-MIMO-specific processing for those operating modes. It is necessary to determine the resources that the STA can provide feedback to.

[0088] RU-based MCS and CSI feedback from the STA to one or more APs can be requested or not. Feedback can be sent back immediately or after a delay. Information (such as MCS or CSI) can be fed back in an efficient manner. Resources corresponding to the feedback data can be identified. Load can be effectively controlled, for example, assuming there are many RUs requiring feedback. For 802.11ax digitization using 256 pt FFT (242 used tones), feedback can be increased fourfold. Feedback required for specific transmissions is reduced.

[0089] Interference can occur in OFDMA due to RF I / Q imbalance. In OFDMA, frequency resources, represented as subchannels, can be allocated to different radio links in either the uplink or downlink direction. A subchannel can be understood as a set of RUs defined in a specific order or arrangement. Due to RF I / Q amplitude and phase imbalance, signals transmitted on subchannels allocated on one side of the channel opposite the center frequency can create interference on the other side of the channel as a representation of the original signal.

[0090] Figure 6 shows an example of the power spectral density for a specific loaded OFDM signal with RF I / Q imbalance. Figure 6 shows a snapshot of a scenario with 256 subcarriers in a 20 MHz channel. Subchannels with 199 to 224 subcarriers (shown as subchannel (SC)A) are loaded with data. RF I / Q imbalance may produce approximately 23 dBr interference in the image of a subchannel with -119 to -224 subcarriers (shown as SC B).

[0091] In a single BSS scenario, such as in OFDMA DL, interference may be insignificant because the transmit (Tx) power on all sub-channels is the same as the Rx power on those sub-channels at each STA. However, in OFDMA UL, for example, when there is no power control or the power control is inaccurate, interference at the image sub-channel (e.g., SC B) can be significant. A STA using sub-channel B can be farther from the AP than a STA using channel A.

[0092] Figure 7 shows an example of bit error rate (BER) performance for interference signals. Figure 7 illustrates the BER performance of a signal transmitted on sub-channel B, which is subject to interference due to transmission on sub-channel A with I / Q imbalance. The line dP represents the power difference between sub-channels A and B. dP > 0 means that the signal power on SC B is lower than the signal power on SC A. As shown in Figure 6, there is a significant performance loss when power is not well controlled.

[0093] 802.11ax STAs can use L-SIG after a conventional preamble to signal the remaining duration of the PPDU to both 11ax and conventional STAs. An equation can be used to convert this time into an octet L_LENGTH (L_length) that 11a / g compatible devices can understand.

[0094] Figure 8 shows an example of a 20 MHz BSS allocation with RU allocation labels.

[0095] A system, method, and means for unified feedback for OFDMA WLAN are disclosed. Unified feedback can be provided by per-RU based MCS feedback, per-RU based CSI feedback, and / or feedback with symmetrical RU allocation.

[0096] RU-based MCS feedback can be achieved through RU-based feedback (MFB), RU label compression using source coding, RU label compression using hierarchical RU labels (RU tree), and / or RU feedback compression using feedback labels.

[0097] RU-based MCS feedback (MFB) can be provided. RU-based MCS / SINR feedback can include the number of MCS, SNR / SINR, and spatial-time streams (N_STS) fed back by the STA on a per RU basis. Traditional 802.11 can transmit one of the values ​​of MCS, SNR / SINR, and N_STS for the entire bandwidth (e.g., Channel Status Indicator (CSI) feedback mechanisms). The feedback overhead of RU-based MCS / SINR feedback can be reduced or minimized, for example, by considering various factors such as feedback granularity, quantization, and feedback / delay.

[0098] Feedback granularity can include the bandwidth in which the feedback metric is located. As an example, a value per 26 tones can indicate a 9RU granularity in a 20 MHz bandwidth.

[0099] Feedback quantification can indicate how feedback is measured / quantified.

[0100] Feedback frequency / delay indicates how frequently information is fed back to the transmitter and how long after it is fed back can the scheduler use that information for scheduling.

[0101] These and / or other factors can affect, for example: (i) feedback load and (ii) the gain achievable from the user schedule (at the transmitter) feedback load, and the scheduling gain obtained from the feedback information. Feedback schemes can attempt to minimize i and maximize ii.

[0102] Figure 9 illustrates an example of feedback granularity (e.g., at the receiver and / or transmitter). The receiver can feed back the average SINR, N_STS, and / or MCS to the transmitter, and the transmitter can use this information for scheduling. The feedback information can allow the scheduler to estimate smaller or larger granularities.

[0103] An example of RU-based MCS feedback for OFDMA in 802.11 is shown below. One or more of the following can be applied.

[0104] STA A can join the network based on one of the following conditions: by initiating authentication (e.g., the process of AP and STA establishing their identification codes) and by sending an association request to AP.

[0105] AP A can transmit beacons. For example, when a beacon indicates a network with RU-based link adaptation capability and STA A also has RU-based link adaptation capability, STA A can join the network. AP A and STA A can operate using RU-based link adaptation with associated feedback.

[0106] For example, when a beacon indicates a network with non-RU-based link adaptation capability, STA A can join the network. AP A and STA A can operate, for example, in a non-RU-based link adaptation capability mode, regardless of STA A's OFDMA capability.

[0107] For example, when a beacon indicates that a network has RU-based link adaptation capability and STA A has non-RU-based link adaptation capability, AP A may not allow STA A to access the network (e.g., STA A does not join the network or start the authentication process).

[0108] Capability information elements (such as new capability information elements) can be sent by STA A in an association request or reassociation request window. AP A can accept or reject STA based on the (re)association request.

[0109] Capability information elements can indicate, for example, the type of link adaptation and compression type supported. The type of link adaptation supported can indicate, for example, (a) not supported; (b) link adaptation based only on unrequested RUs; or (c) link adaptation based on both requested and unrequested RUs. The type of compression can indicate, for example, (a) link adaptation feedback based on uncompressed RUs; or (b) link adaptation feedback based on compressed RUs.

[0110] AP A can send probe sequences and MCS requests, for example, for link adaptation based on the requested RU. MCS requests (MRQs) can be sent in staggered probe PPDUs or null data packets (NDPs). MRQs may include, for example: (i) information indicating that it is a request, (ii) the granularity of the requested response (e.g., responses based on 26 RUs, 52 RUs, 104 RUs, etc.), (iii) the response pattern, and / or (iv) the identified MCS request sequence (MSFI) to, for example, enable STA A to indicate that it responds to the targeted request in the response.

[0111] STA A can measure channels and provide feedback based on feedback patterns, for example, for unsolicited RU-based link adaptation.

[0112] In one option, we can define a scheduling or RU granularity (RG) that indicates the granularity at which scheduling occurs. We can define a feedback granularity (FG) that indicates the granularity at which feedback occurs. @Receiver: The instantaneous rate on the sub-channel (e.g., defined based on the feedback granularity (FG)) can be calculated and fed back to the transmitter. @Transmitter: The instantaneous rate on the RU (e.g., defined based on the RU granularity (RG)) can be calculated for each station, and proportional fair scheduling is performed.

[0113] RG can be transmitted from AP to STA. It can be transmitted during STA association, in a field of an MCS request frame, or via a dedicated RG request frame. FG can be determined by the STA. One or more of the diagrams 9A, 9B, or 9C may be applied.

[0114] Feedback patterns determine the feedback granularity (FG) and amount sent by each STA to the AP. Examples of feedback patterns include: (i) feedback information for all RUs (e.g., 1 to 16), (ii) feedback information for a specific RU (e.g., 1, 2, ..., 16), (iii) feedback information for a specific type of RU (e.g., a RU of a certain size to indicate to the AP a preference for allocating that size, such as an RU size of 104 subcarriers [RU14, RU15], an RU size of 52 subcarriers [RU10, RU11, RU12, RU13]), (iv) feedback information based on a desired feedback compression pattern, and (v) feedback information for the top N RUs (e.g., the optimal N bands to be fed back from each STA). The number of bands can be specified by the AP or determined independently by each STA, for example, by access class and buffer occupancy (e.g., in the on-chain).

[0115] The feedback mode can be determined by the AP, determined by the AP but covered by each STA, or determined independently by each STA.

[0116] The feedback information may include one or more of the following: the number of spatial-time streams (N_STS) for the STA and / or the effective SNR value and the recommended MCS for each RU. For example, when only one value is needed for the entire transmission bandwidth, the feedback on the number of spatial-time streams (N_STS) for the STA may include a value that is semi-statically set at the start of the transmission. The SNR can be estimated for use by (or in combination for) multiple RUs. As an example, the information on RU10 is implied from the feedback information on RU1 and RU2.

[0117] Feedback information for each RU can be sent in a MAC frame. This information can be sent in the frame header or frame body. In the example, the feedback frame can be sent without a frame body.

[0118] Figure 10 shows an example of MCS feedback frame 1.

[0119] Figure 11 shows an example of MCS feedback frame 2.

[0120] As illustrated in Figures 10 and 11, fields in the frame header (such as HT control fields) can be reused to provide feedback on MCS information, where one or more of the following can be applied: HE variables can be defined for HT control fields. The first bit of an HT control field can be used to indicate a VHT or HT variable. The first two bits of an HT control field can be used to indicate a HE, VHT, or HT variable.

[0121] The HE field (e.g., 1 bit) can be a reserved bit in the HT control intermediate subfield of the VHT variable HT control field. The HE field can be set to 1, for example, to indicate the HE variable MCS signal.

[0122] The MFB field (e.g., 15 bits) can include NUM_STS, MCS, bandwidth, and SNR feedback. In the example, the MCS feedback field (MFB) in the VHT field can be used, for example, to provide feedback information as if no OFDMA transmission would occur (e.g., conventional feedback), and additional fields can be used to provide feedback information on a specific RU (e.g., as shown in Figure 10). In the example, the MFB can be used (e.g., only) for a specific RU (e.g., as shown in Figure 11). For example, by sending the NUM_STS and BW fields for all RUs in a common parameter field (e.g., which can be inserted into other frames disclosed here), and / or by eliminating the BW field (e.g., 2 bits) for example when the RU size implicitly indicates the BW, the number of bits used for feedback MFB is reduced.

[0123] The number of RU fields (e.g., 4 bits for a 20 MHz transmission) can be set to allow the AP to know or determine how many RUs are being fed back. The number of RU fields can be adjusted as the transmission bandwidth increases. The number of RU fields can be reduced, for example, based on the maximum number of RUs scheduled per STA. The AP can (e.g., blindly) decode the number of RUs being fed back.

[0124] The RU index field can indicate the field that MFB implies. This field can depend on label compression. The RU index field can be omitted, for example, when there is a scenario where the RUs to be fed back are predetermined (e.g., the feeding back of RU1 to RU9).

[0125] The MFBi field can provide MCS feedback for the RU index i. The MFB used for the RU index can, for example, use the same table as a traditional MFB index (e.g., 15 bits). The MFB used for the RU index can, for example, use desired compression to reduce the overall feedback load. For example, the CSI feedback mechanism can allow feedback (e.g., minimum feedback) granularity (e.g., less than 20 MHz).

[0126] Figure 12 shows an example of RU granularity. Figure 12 illustrates four different granularities, but it should be understood that any number of granularities is possible.

[0127] Figure 13 shows an example of receiver granularity with multi-RU scheduling. Figure 13 illustrates 9 RUs scheduled at 4 different granularities.

[0128] Figures 12 and 13 illustrate efficient channels based on the 20 MHz digitization shown in Figure 8 and various corresponding feedback granularities. In each example, the average SINR or MCS can be fed back to the transmitter.

[0129] Figure 14 shows examples of scheduled delivery volumes for the four cases illustrated in Figure 13. The results in Figure 14 show that, for example, case 3 with 5 feedback values ​​achieves the same delivery volume as case 4 with 9 feedback values, implying a lower feedback load without any scheduling losses. The number of bits used for feedback, or the number of bits used in labeling the feedback, is optimized. This reduces the feedback load.

[0130] RU feedback compression using SNR bias reporting can be employed. The number of bits used for feedback MFB, for example in OFDMA for WLAN, can affect the feasibility of scheduling gain and / or feedback load. Scheduling gain increases with the number of quantization bits. Increasing the number of quantization bits can increase the feedback load. Figure 14A shows an example of the effect of quantization on scheduling gain. Figure 14A illustrates that a scheduling gain with 6-bit quantization may be equal to a scheduling gain without quantization. Figure 14A shows scheduling gains with different bit quantizations. Case 1 uses 1 bit. Case 2 uses 3 bits. Case 3 uses 6 bits. Case 4 has no quantization. SINR values ​​can be quantized and fed back to the transmitter, with [-10, 53] dB mapped to 2N-1 values. Results show that 6-bit quantization of SINR for each RU (e.g., MFB:SNR quantization in 802.11ac) is sufficient for extracting scheduling gain.

[0131] SNR / MCS deviation reporting can be fed back (e.g., on a per RU basis). SNR / MCS deviation reporting feedback can reduce the feedback load. This reporting feedback can be supplementary to the MFB for the transmission bandwidth. SNR / MCS deviation reporting can feed back the SNR deviation in dB and / or the MCS change of the group or per RU from the average SNR / MCS of the subcarriers across the transmission bandwidth. The number of bits required can be reduced. This can allow for an overall reduction in the feedback size. This can be the deviation. SNR / MCS deviation feedback can be fed back (e.g., in the MFBi in an RU-based MFB procedure, as shown in Figure 10). In this example case, the MFB can be set to the average SNR / MCS. As an example, the MFBi element can be set to the SNR / MCS deviation. The feedback load can be saved as follows: 20 MHz: 16 RUs 80 MHz: 37 RUs MFB six-bit quantization 16 x 6 = 96 bits 37 x 6 = 222 bits Transmitted MFB = 6 bits SNR deviation = 2 bits 1 x 6 + 16 x 2 = 38 bits 1 x 6 + 37 x 3 = 80 bits Transmitted MFB = 6 bits SNR deviation = 3 bits 1 x 6 + 16 x 3 = 54 bits 1 x 6 + 37 x 3 = 117 bits The number of bits used in both the average SNR and SNR deviation feedback can be set, negotiated between the AP and STA, and / or set by the STA based on an estimate of the required feedback accuracy. The average SNR can be fed back in the common RU feedback field. RU-specific deviations can be fed back in the RU or subcarrier-specific fields.

[0132] Source-coded RU label compression can be provided. For example, the size of the RU index field in Figures 10 and 11 can be reduced. In the example, each RU can be identified using a variable-length bitmap. The label can be based on the type of source coding mechanism, such as Shannon-Fanno coding or Huffman coding. The label can be empirically based, for example, on the number of times different RUs can be scheduled. For example, based on the frequency selectivity of the channel that causes local maximization at the RU, the interference from neighboring BSSs that causes local minimization at the RU, and the inter-BSS interference coordination that gives the RU a higher priority than others, an RU can have a higher probability of being selected. RUs with a higher probability of being selected can be labeled with a lower bit number than other RUs.

[0133] For example, the overall feedback can be compressed due to the lower number of RUs being fed back and / or the limitations on the number of bits used to identify each selected RU.

[0134] Compression can be specific to a particular STA or group of STAs, or it can be universal across the entire BSS. For example, by communicating associated labels between APs and STAs, an AP can be enabled to identify the corresponding RU. An AP may be able to blindly know the length of the bitmap it decodes. In the example, the maximum number of bits used can be negotiated between the AP and STAs. Parameters can limit the number of RUs that may be fed back. Labels can be used for resource allocation.

[0135] Figure 15 illustrates an example of entropy coding. Figure 15 shows a 20 MHz RU allocation with its associated resource allocation frequency. Shannon-Fanno coding is used to label the RUs, with RU labels ranging from 3 bits (e.g., for RUs 6, 1, 8, and 7 scheduled at higher frequencies) to 9 bits (e.g., for RU 16, which was never scheduled). For example, when the AP and STA negotiate and agree on 3-bit communication, the reduction from 4-bit communication across the entire band to 3-bit communication for RUs 6, 1, 8, and 2 can be achieved. Further enhanced compression techniques can lead to additional savings.

[0136] Figure 16 shows an example of RU labeling. In compression technology, the optimal 8 RUs can be selected for 3-bit communication, as shown in the example in Figure 16.

[0137] For example, when the label has been determined, the RU label request / report technology can be used to send information between the AP and STA.

[0138] RU label compression using hierarchical RU labeling (RU tree) can be provided. The size of the RU index field in Figures 10 and 11 can be reduced. In the example, RUs can be classified as a hierarchical tree structure separated by layers.

[0139] Figure 17 shows an example of a hierarchical RU labeling structure. Outside the hierarchy of the tree structure (e.g., independent of it), the sides of the tree structure (e.g., left, right) can be indicated. Sides and hierarchy can be used to reduce the number of bits in the feedback.

[0140] Information feedback for the entire bandwidth can occur in the MFB field, as shown in Figure 14, while feedback for other RUs can occur in the MFBi field.

[0141] Figure 18 illustrates an example of hierarchical feedback with layer restrictions. In this example, feedback (or resource allocation) can be restricted to a single layer, for example. A single field can be dedicated to the restricted layer, such as layer 11. The size of the RU index field can be sent based, for example, on the amount of resources in that layer, such as 3 bits for layer 11, 2 bits for layer 01, 1 bit for layer 10, and zero bits for layer 00.

[0142] Figure 19 illustrates an example of hierarchical feedback without layer limitations. In this example, fields can be dedicated to the current layer being fed back. All elements in the current layer are transmitted sequentially. RU index and MFBi information can then be fed back. The size of the RU index layer can depend on the number of elements in the layer. Various techniques can be deployed to differentiate between layers. In the first example, the number of RUs used for that layer is signaled. In the second example, the boundaries between layer signals can be indicated, for example, by changing the modulation type (e.g., from BPSK to rotated BPSK (e.g., 90 degrees) or from QPSK to offset QPSK). The receiver can automatically detect changes in layers.

[0143] In the example, layer information can be encoded as QPSK or O-QPSK. This can determine whether a label (or resource) is in the 0 subtree (left) or 1 subtree (right) of the tree. This encoding or other techniques that distinguish the sides of the tree can reduce the number of bits required to transmit the actual resource label. As an example, resources (3,4) on layer 01 can be transmitted by (a) layer 01 using QPSK or (b) a 1-bit number.

[0144] RU feedback using feedback label compression can be provided. Feedback label compression can be implemented by the STA and AP. One or more of the following can be applied.

[0145] The AP can communicate the maximum number of bits used to identify the RU to the STA. The maximum number of bits can be set, for example, during the association between the STA and the AP, or sent to the STA via a dedicated MAC frame.

[0146] In an example of the AP guidance scheme, the AP can use an RU label reporting frame to communicate the RU index and its associated label to the STA. The label can be based on an entropy-based compression algorithm, as shown in Figure 15. The label can be implemented, for example, by selecting the optimal 2n RUs, where n is the number of bits, as shown in Figure 16.

[0147] In an example of the STA guidance scheme, the STA can, for instance, communicate the RU index and associated label to the AP based on an RU label request / report procedure. For example, when there is a label change suggested by a change on its channel, the STA can send an unrequested RU label report frame. The label can be based on an entropy-based compression algorithm, as shown in Figure 15. The label can be implemented, for instance, by selecting the optimal 2n RUs, where n is the number of bits, as shown in Figure 16.

[0148] RU label request frames can be transmitted from AP to STA. The request frame may include, for example, the number of bits per label and / or the destination address of the STA.

[0149] RU label response frames can be transmitted from STA to AP, either unsolicited or in response to an RU label request. RU label response frames can be transmitted from AP to STA, for example, in an AP directing system. RU label frames can include, for example, the address of the STA, the actual RU label such as RU1, RU2, ..., RU16, or any alternative label indicating the RU and / or a corresponding compressed bit map indicating the new RU label.

[0150] STAs can use RU labels (aliases) during CSI or MCS feedback to reduce load, for example. APs can use RU labels (aliases) during OFDMA transmissions for resource allocation.

[0151] RU-based CSI feedback can be provided by RU-based CSI feedback capability, RU-based CSI feedback and / or communication used for RU-based CSI feedback.

[0152] RU-based CSI feedback capabilities can be provided. A HE STA can declare itself as a HE STA, for example, by transmitting a HE capability element. The HE capability element can be transmitted in beacon frames, association request / response frames, reassociation request / response frames, probe request / response frames, etc. The HE capability element may include HE capability information fields.

[0153] The HE capability information field can carry subfields, such as one or more of the following subfields.

[0154] The OFDMA Beamformer capability field indicates the support for OFDMA operation as a beamformer.

[0155] The OFDMA Beamformee Capabilities field indicates the support for OFDMA operation as a beamforming receiver.

[0156] The OFDMA SU beamformer capability field indicates the support for OFDMA operation as a SU beamformer.

[0157] The OFDMA SU beamforming receiver capability field indicates the support for OFDMA operation as a SU beamforming receiver.

[0158] The OFDMA MU-MIMO beamformer capability field indicates support for OFDMA operation as a MU-MIMO beamformer.

[0159] The OFDMA MU-MIMO beamforming receiver capability field indicates the support for OFDMA operation as a MU-MIMO beamforming receiver.

[0160] The "RU-based real-time CSI feedback capability" field indicates support for RU-based real-time CSI feedback.

[0161] The RU-based delayed CSI feedback capability field indicates support for RU-based delayed CSI feedback.

[0162] The "RU-based instant and delayed CSI feedback capability" field indicates support for RU-based instant and delayed CSI feedback.

[0163] RU-based CSI feedback technology can be provided. RU-based CSI feedback can modify NDP / NDPA CSI feedback technology.

[0164] Figures 20A and 20B show examples of NDP / NDPA CSI feedback. Figure 20A illustrates an example of CSI training and feedback interaction between the transmitting STA and the receiving STA. Figure 20B illustrates an example of interaction between the transmitting STA, the AP, and multiple receiving STAs. The NDPA frame and CSI feedback frame can be modified.

[0165] CSI training and feedback based on a single-user RU can be implemented, for example, as follows: STA 1 can acquire media and transmit NDPA frames, which may be followed by NDP frames. STA 1 can, for example, indicate in the NDPA frames a request for RU-based CSI feedback and a detailed feedback mode. STA 2 can detect the NDPA frames and prepare RU-based CSI feedback accordingly. STA 2 can, for example, transmit the feedback frame SIFS time after the NDP frames based on the feedback mode, or it can transmit the feedback frame in a delayed mode.

[0166] CSI training and feedback based on a multi-user RU can be implemented, for example, according to one or more of the following: The AP can acquire media and can transmit NDPA frames to a group of STAs, followed by NDP frames. The AP can, for example, indicate in the NDPA frames a request for RU-based CSI feedback and a detailed feedback mode. The STAs can detect the NDPA frames and prepare RU-based CSI feedback accordingly. Depending on the feedback mode, for example, based on the feedback mode, the STAs can transmit the NDP frames immediately after the NDP frames or can transmit the feedback frames in a delayed mode.

[0167] RU-based CSI feedback messaging can be provided. NDPA frames can be modified to declare RU-based CSI training.

[0168] Figure 21 shows an example of a modified NDPA frame. One or more of the following can be applied.

[0169] The frame control field can be modified to indicate RU-based CSI training. The STA information field can include various information about one or more STAs. The STA information field can include one or more of the following information about each STA.

[0170] The AID field can be used to transmit the STA ID. The ID can be an AID, a compressed version of the AID, a partial AID (PAID), etc.

[0171] The RU feedback mode field can, for example, carry one or a combination of the following feedback modes.

[0172] The first mode (e.g., mode 1) can indicate the driver of the feedback. Specifying the transmitter for the RU feedback mode can indicate the transmitter of the NDPA frame, and can specify the RU used for CSI feedback. Specifying the receiver for the RU feedback mode can indicate the receiver of the NDPA frame, or the STA specified by the AID field can determine the CSI feedback at a particular RU.

[0173] The second mode (e.g., mode 2) can indicate the timing of the feedback. The Immediate RU Feedback mode field can be used to indicate that the STA can immediately feed back CSI information after receiving the NDPA / NDP frame. The Delayed Feedback mode field can be used to indicate that the STA can feed back CSI information after a delay when it is ready.

[0174] The third mode (e.g., mode 3) can illustrate the MU feedback mechanism. In examples where more than one STA can be involved in NDPA / NDP switching, the STA can use various techniques, such as time domain, RU domain, or spatial domain, to feed back RU-based CSI. In the time domain technique example, the STA feeds back CSI sequentially in the time domain. The STA may or may not be polled before feeding back its CSI. In the RU domain technique example, the STA can use different RUs to feed back CSI. The RU used to transmit CSI information can be the same as or different from the RU where the STA measures the CSI. In the spatial domain technique example, the STA can use multiple antennas with spatial domain segmentation to feed back CSI.

[0175] The fourth mode (e.g., mode 4) can indicate the content, type, or status of the feedback. The content, type, or status of the feedback can include, for example, compressed feedback, uncompressed feedback, and codebook-based feedback.

[0176] The fifth mode (e.g., mode 5) can indicate, for example, independent feedback or differential feedback.

[0177] The RU information field can be used to communicate CSI feedback for the RU in question. The RU information field can be represented in bitmap format or by RU index. In bitmap format, for example, when a maximum of K RUs are allowed, a K-bit array can be used to identify each RU. Alternatively, the RU index can be defined as a specific label identifying a particular RU or group of RUs. As an example, RU index 10 could indicate RU1 and RU2.

[0178] The feedback granularity field can indicate the feedback granularity for each STA and each RU. The feedback granularity field can be carried in the STA information field, allowing each STA to use its own granularity. Each STA can be set to a BSS-wide feedback granularity. In the example, the feedback granularity field can be carried in the RU information field, allowing each RU to use a set of granularities. Feedback granularity can depend on the feedback pattern. Some examples are shown below.

[0179] RU-based CSI feedback can indicate, for example, the requested 4 / 5 / 6 / 8-bit real / imaginary CSI values ​​for a specific RU / RU band. In this mode, the actual CSI is used, and this allows for better interpolation between the feedback subcarriers. This allows for finer feedback granularity, such as feeding back fewer subcarriers to be able to estimate the channel for each RU.

[0180] Uncompressed beamforming weights based on RU can represent, for example, 8 / 6 / 4 / 2-bit real / imaginary values ​​plus the SNR value for each STS. In this mode, the feedback granularity may need to be higher than that of RU-based CSI feedback. Because it may be uncompressed, there is a trade-off between granularity and load.

[0181] RU-based compressed beamforming weights can be expressed, for example, by adding an average SNR to the 1 / 2 / 3 / 4-bit quantization angle values ​​for each stream. In this case, the feedback granularity can be higher without increasing the load.

[0182] Figure 22 shows an example of a unified CSI feedback frame. The NDPA frame used for RU-based CSI feedback mechanisms can be used and modified. The above description can be applied to other types of control frames or certain fields (e.g., STA information can be transmitted in the SIG-A / B field of the PLCP header). The unified CSI feedback frame can be used by the STA to provide feedback on RU-based CSI. The unified CSI feedback frame can be implemented, for example, by modifying the compressed beamforming report frame. The unified CSI feedback frame can carry, for example, at least three fields: (i) MU control field, (ii) MU CSI report field, and (iii) MU SINR report field, as shown in Figure 22.

[0183] Figure 23 shows an example of a MU control field. MU control fields can be designed and / or implemented as shown in Figure 23, wherein one or more of the following can be applied.

[0184] The noise criterion (“NC”) index and the noise rate (“Nr”) index can be used to indicate the size of the CSI matrix.

[0185] The channel width field can be used to indicate the channel being measured in order to create a CSI feedback matrix. Note that with different channel widths, a set of RU indices can be fed back and correspond to the specified channel width.

[0186] The grouping field can indicate the grouping of the subcarrier, such as Ng.

[0187] The feedback granularity field indicates the granularity of the feedback.

[0188] The feedback type field can indicate one or more RU feedback modes described in the NDPA frame.

[0189] The RU information field can indicate the index of the RU, where the frame carries its CSI. RU-based CSI information can be fed back in more than one unified CSI feedback frame.

[0190] The probe dialog identifier field can be used to request feedback from the NDPA frame.

[0191] Figure 24 shows an example of a MU CSI report field. The MU CSI report field can be used to transmit (e.g., explicit) CSI feedback in the corresponding RU identified in the MU control field, as shown in Figure 24. The RU k field can transmit a compressed beamforming report for the k-th RU. The report can include the average SNR per stream per RU.

[0192] The report may include CSI information about, for example, a specified subcarrier. The CSI information may be compressed CSI information. For example, angles compressed from the channel matrix or V matrix using Givens rotation may be used.

[0193] The report may include differential CSI information. CSI information may include average SNR and / or CSI information (e.g., on a specified subcarrier). CSI information may be time-domain or frequency-domain differential information.

[0194] Time-domain differential CSI information can be used. Reports can use past reports as references. Deviation values ​​compared to reference reports can be used. Deviation values ​​can be used instead of absolute values ​​of compressed or uncompressed CSI information in the report. Each BF report can carry a beacon. Beacons can be used to uniquely identify reports (e.g., within a time period). Beacons for reference CSI reports can be explicitly included when using time-domain differential CSI reports. The difference between the timestamps of the current CSI report and the reference CSI report can be transmitted.

[0195] Frequency domain differential information can be used. Reports can use subcarriers as a reference. CSI information on the remaining subcarriers can be the deviation compared to the reference subcarrier. The reference subcarrier can be specified and communicated in the detection and / or reporting frame or dependent implementation.

[0196] Figure 25 shows an example of the MU SINR report field. The MU SINR report field can be used to transmit SINR measurements in the corresponding RU identified in the MU control field, as shown in Figure 25. The SINR report can be the average SINR on the RU or a detailed SINR per subcarrier or subcarrier group. Granularity can be defined in the MU control field.

[0197] Subcarrier group SNR deviation reports can be fed back (e.g., per RU or per subcarrier group). The deviation of the SNR of each subcarrier or subcarrier group from the average SNR on the RU (or subcarrier group), in dB, can be fed back to the beamformer. The HE-SIG-B field of the feedback frame can retain common and / or RU-specific information (e.g., both CSI feedback information and subcarrier SNR deviation reports) on the RU being fed back. A defined subset of subcarriers (e.g., not associated with a specific RU) can be fed back. CSI request frames (e.g., NDP frames) can specify the indices of the start and / or end subcarriers used for feedback. This allows CSI feedback to be used for different transmission bandwidths (e.g., because subcarriers used for different transmission bandwidths do not overlap).

[0198] Unified feedback can be used. This can include one or more of the following: The AP can send an NDP announcement to a specific STA or a group of stations. The AP can send an NDP to a specific STA. The NDP can have a preamble without data to enable the station to measure the channel based on the parameters sent in the NDPA announcement. The NDPA frame can include a resource element channel quality feedback request on a station-by-station basis for each resource element within the bandwidth (e.g., for one or more resource elements per station). The NDP announcement frame can signal / indicate a resource element channel quality feedback request for at least one resource element within a first bandwidth for each or more stations. The NDPA can request all stations to respond with the same resource element, or request each station to send back information in a different resource element. The AP can request specific RUs and / or subcarriers (e.g., start subcarriers and end subcarriers) for feedback (e.g., in the NDPA frame). Each STA can send CSI feedback to the AP and can use a feedback frame to send CSI feedback. The STA can use an HE-SIG-B or actual feedback frame to indicate the start and / or end subcarrier RU represented by the feedback information. The feedback MAC frame includes one or more of the following fields: Category: set to HE, HE Action: set to HE Feedback or MU HE Control. One or more of the following can be applied relative to the MU HE Control field. The MU HE Control field can be set as described above. A 2-bit field can specify the actual type of feedback. For example, for 00: SINR / MCS: SINR can be combined with the recommended MCS and the recommended number of spatial-temporal streams. SINR / MCS can be relayed independently for each RU (or subcarrier group) or the average SINR / MCS can be relayed (e.g., with SINR / MCS offset for each subcarrier group). For 01: SINR + Channel Status Information / Beamforming Information, the SINR for each stream can be combined with information about the channel. The information can be the actual channel coefficients or compressed / uncompressed beamforming information. For 10: SINR + CSI + MU exclusive information, the information in type 01 can be combined with the deviation in SNR / MCS of each subcarrier being fed back (e.g., based on a specific RU or subcarrier range). The order in which CSO information is fed back can be based on the RU allocation or subcarrier specified in the HE-SIG-B field or the feedback frame. Field 11 can be left blank.

[0199] Feedback patterns determine the granularity and amount of feedback sent by a STA (e.g., each STA) to an AP. Example feedback patterns include one or more of the following: Feedback information for all RUs: 1 to 16; Feedback information for a specific RU: 1, 2, ..., 16; Feedback information for a specific subcarrier group (e.g., this subcarrier group can span multiple RUs); Feedback information for a specific type of RU (e.g., a STA can feed back RUs of a specific size only to the AP, indicating its preferred allocation size, e.g., RU size for 104 subcarriers, e.g., [RU14, RU15], RU size for 52 subcarriers, e.g., [RU10, RU11, RU12, RU13]); Feedback information for the top N RUs (e.g., the optimal N bands are fed back from each STA and the number of bands can be specified by the AP or determined independently by each STA, e.g., determined by access class and buffer occupancy (e.g., on-chain); and / or feedback information can be based on a desired feedback compression pattern.

[0200] Feedback based on multi-stage RUs can be used. The amount of feedback required to enable single-user MIMO OFDMA beamforming or multi-user MIMO OFDMA beamforming can be reduced. The AP can identify the desired band / RU based on first-stage feedback (e.g., SNR or MCS feedback). The AP can request second-stage full CSI feedback for a specific RU or band of interest. One or more of the following can be performed.

[0201] The AP can send NDP announcements. NDPs enable STAs to estimate their next-chain channel.

[0202] An AP can send a Phase 1 CSI request or trigger frame. A trigger frame can request limited CSI information (e.g., non-MIMO or scalar value). This allows the AP to request more detailed information about a specific subset of subcarriers at a future time. The subcarrier set can be based on Resource Unit (RU) granularity or the range of signaled subcarriers. A feedback request can indicate a request for an RU (e.g., all RUs, best N RUs, or best subcarrier range). A feedback request can be a scheduling trigger frame. In a scheduling trigger frame, the AP can request information from a specific STA. A feedback request can be a random access trigger frame. For a random access trigger frame, each STA randomly accesses UL multi-user resources. A feedback request can be for both random access and / or scheduled resources. When the schedule responds, the access point can allocate one or more resource units for each station to provide data.

[0203] STAs can send responses to AP Phase 1 CSI feedback requests. Feedback can be scheduled or random access on-chain multi-user (UL-MU) transmissions. Feedback can be scheduled by UL-MU triggered frames or automatically sent by each STA in response to an on-chain random access triggered frame. Feedback can be non-MIMO CSI feedback, which includes the average SNR of the spatial-temporal stream based on rank and / or channel condition number, the total SNR of the spatial-temporal stream, and / or the SNR of the MCS feedback (MFB) based on resource units.

[0204] The AP can issue multiple scheduled or random access triggers to the STA. These triggers ensure that the STA (e.g., all STAs) sends back its Phase 1 CSI feedback. This information is smaller and has a lower load compared to full CSI feedback.

[0205] The AP scheduler can determine the STA and the band of interest or the desired RU.

[0206] The AP can send a Stage 2 CSI trigger to the STA (e.g., for a specific band of interest). Upon receiving the CSI, a data transmission trigger frame for DL ​​beamforming transmission can be sent, as shown in Figure 28. Figure 28 is an example of multi-stage CSI feedback with a scheduled Stage 1 / 2 trigger frame and an explicit downlink data trigger frame. The STA can respond with UL MU CSI feedback using one or more of the following (e.g., for a specific band): Feedback can be based on time-domain or frequency-domain differential feedback. Feedback can be based on scalar difference or vector difference (e.g., based on range / blank space mapping adjacent subcarriers in time / frequency to the base subcarrier). The quantization level used for feedback can be specified differently for each user, or per (φi, ψi) for a specific user. The AP can specify long-term, short-term, and / or instantaneous feedback from a specific user. The AP can use CSI to transmit multi-user beamforming signals to the STA of interest. The transmission acts as an ACK for the Stage 2 CSI feedback.

[0207] The AP can combine user scheduling frames and stage 2 CSI feedback frames, as shown in Figures 27 and 29. Figure 27 shows an example of multi-stage CSI feedback with scheduling stage 1 / 2 trigger frames and no explicit downlink data trigger frame. Figure 29 shows an example of multi-stage CSI feedback with scheduling and random access stage 1 and 2 trigger frames and no explicit downlink data trigger frame. The STA can respond with stage 2 CSI feedback. The AP can send multi-user beamforming signals to the STA. The feedback is similar to that discussed above.

[0208] The STA can send an ACK to the AP.

[0209] An AP can request multi-stage 2 feedback from a STA without sending beamforming transmissions to the STA. Stage 2 feedback can be requested via a random access triggered frame. The AP can respond with an ACK after the stage 2 CSI feedback, as shown in Figure 30. Figure 30 shows an example of multi-stage CSI feedback with scheduled and random access stage 1 and 2 triggered frames and no downlink data transmission. The terms stage 1 and stage 2 feedback are conceptual and can be replaced by other terms. Using CSI feedback based on a multi-stage RU can result in savings of up to 90% on feedback across the entire band, as shown in Figure 31. AP requests to send channel information to each station based on feedback responses can be sent in the same bandwidth as the NDP, a subset of the NDP bandwidth, or a bandwidth different from the NDP bandwidth.

[0210] Feedback with symmetric RU allocation is provided. Constraints can be applied to the RU allocation rules to, for example, restrict some or all RU allocations to symmetric RU allocations.

[0211] Figure 26 shows an example of symmetric RU allocation. In the example shown in Figure 26, RU1 (always, for example) is paired with RU9 for symmetric RU allocation.

[0212] Symmetric RU1 (SRU1) can be used to represent, for example, RU1 and RU9, e.g., SRU1 = [RU1, RU9]. Similarly, SRU2 = [RU2, RU8]; SRU3 = [RU3, RU7]; SRU4 = [RU4, RU6]. Feedback requests can indicate symmetric RU allocation, for example, by using SRU indices instead of RU indices in the feedback request. SRU indices can be used, for example, when specifying symmetric RU allocation in the feedback report box. Symmetric RU allocation can limit the impact of disturbances caused by imbalance. Feedback information (e.g., CSI or MCS) can represent those on two paired RUs (e.g., simple average or weighted average). Other disclosure techniques (e.g., RU-based MCS feedback and RU-based CSI feedback) can be applied to symmetric RU allocation. For symmetric RU allocation, the load associated with the RU allocation (RU index) can be reduced, for example, by nearly half.

[0213] The L_LENGTH(L_length) calculation can be used and can be as follows: have TXTIME = TL_PREAMBLE (L_preamble) + THE_PREAMBLE (HE_preamble) + THE_DATA (HE_data) + TPE THE_DATA = THE_SYM × NSYM = (12.8+TGI) × NSYM TPE is the duration of PE. For STAs operating in the 5GHz band, the L_LENGTH field in L_SIG is set as follows: LLENGTH = ((TXTIME - 20) / 4) × 3 – 3 - m, m = 1 or 2 or alternative LLENGTH = ((TXTIME - 20) / 4) × 3 – 6 + m, m = 1 or 2 For STAs operating in the 2.4 GHz band, the L_LENGTH field in L_SIG is set as follows: LLENGTH = ((TXTIME - 20 - SignalExtention) / 4) × 3 – 3 - m, m = 1 or 2 SignalExtension is 6 µs. or, LLENGTH = ((TXTIME – 20 – SignalExtention) / 4) x 3 – 6 + m, m=1 or 2.

[0214] The systems, methods, and means disclosed herein can be applied in any combination, to other wireless technologies, and for other services.

[0215] Although the disclosed features, elements, and techniques (e.g., the disclosed techniques) are described in different combinations and examples, each feature, element, or technique can be implemented alone or in various combinations with and without other described features, elements, and techniques.

[0216] Although the examples are shown for 802.11, the techniques disclosed are applicable to other wireless systems and protocols.

[0217] Although examples using Short Frame Space (SIFS) are presented to illustrate various inter-frame intervals, the disclosed techniques can be applied to other inter-frame intervals, such as Reduced Frame Space (RIFS) or other agreed time intervals.

[0218] The WTRU can reference the physical device identifier or the user identifier, such as user-related identifiers like MSISDN or SIP URI. The WTRU can also reference application-based identifiers, such as the username used for each application.

[0219] The processes described herein can be implemented in a computer program, software, or firmware executed by a computer or processor, wherein the computer program, software, or firmware is contained in a computer-readable storage medium. Examples of computer-readable media include, but are not limited to, electronic signals (transmitted via wired or wireless connections) and / or computer-readable storage media. Examples of computer-readable storage media include, but are not limited to, read-only memory (ROM), random access memory (RAM), temporary registers, cache memory, semiconductor storage devices, magnetic media (e.g., but not limited to internal hard and removable disks), magneto-optical media, and / or optical media such as CD-ROMs and / or DVDs. The processor associated with the software can be used to implement radio frequency transceivers used in WTRUs, terminals, base stations, RNCs, and / or any host computer.

[0220] 100: Communication System 102, 102a, 102b, 102c, 102d: Wireless Transmit / Receive Unit (WTRU) 104: Radio Access Network (RAN) 106: Core Network 108: Public Switched Telephone Network (PSTN) 110: Internet 112: Other networks 114a, 114b: Base stations 116: Empty Intermediate Surface 118: Processor 120: Transceiver 122: Transmit / receive element 124: Speaker / Microphone 126: Keyboard 128: Monitor / Touchpad 130: Non-removable memory 132: Portable Memory 134: Power Supply 136: Global Positioning System (GPS) Chipset 138: Peripheral Devices 402: Resource Unit ACK: Confirmation AP: Access Point BER: Bit Error Rate BSS: Basic Services Set CSI: Channel Status Information FG: Feedback Granularity GID-H: Group ID (High) GID-L: General Interference Detection and Location HE: High efficiency HT: High Delivery Capacity MCS: Modulation and Coding Scheme MFB:MCS Feedback MFSI: MCS Feedback Sequence Identifier MRQ:MCS Request MSI:MRQ sequence indicator NC: Noise Standard Nr: Noise rate NDP: Empty Data Packet NDPA: Empty Data Packet Announcement OFDMA: Orthogonal Frequency Division Multiple Access QoS: Quality of Service RF: Radio Frequency RG:RU granularity RU: Resource Unit SC: Sub-channel SINR: Signal-to-Interference-to-Noise Ratio STA: Station STBC: Spatial-Time Block Coding Tx: Transmission VHT: Very High Transport Capacity

Claims

1. A first station (STA) including a transceiver and a processor, the transceiver and the processor being configured to: receive a null data packet announcement (NDPA), the NDPA including a first STA information field and a second STA information field, wherein the first STA information field includes: A first subcarrier packet, a first AID subfield configured to include a first STA identifier (ID) identifying the first STA, and at least one first subfield including a first resource element (RU) start index for the first STA and a second subfield including a first RU end index for the first STA, wherein the first RU start index indicated in the first subfield and the first RU end index indicated in the second subfield indicate a first group of RUs of a first group of subcarriers associated with channel status feedback, wherein the first group of RUs for the first STA is less than a 20 MHz channel bandwidth; and wherein the second STA information field includes: a second subcarrier packet, a second AID subfield configured to include a second STA ID, the second STA... ID identifies a second STA, and includes at least one third subfield including a second RU start index for the second STA and one fourth subfield including a second RU end index for the second STA, wherein the second RU start index indicated in the third subfield and the second RU end index indicated in the fourth subfield indicate a second group of RUs including a second group of subcarriers associated with channel status feedback, wherein the second group of RUs for the second STA is less than a 20 MHz channel bandwidth; Receives a null data packet (NDP) for measuring a channel quality; After the NDP, receives a trigger frame specifying a resource allocation for a feedback response from each of the first STA and the second STA, wherein the resource allocation for the feedback response from each of the first STA and the second STA is different; Based on the first STA The AID is used to identify one of the identifiers in the corresponding trigger frame to determine the channel status feedback; and in a short frame space (SIFS) following the trigger frame, the feedback response is transmitted using the resource allocation of the first STA, wherein the feedback response includes signal-to-noise ratio (SNR) information.

2. The STA as described in Request 1, wherein the feedback response includes per-RU feedback, which is associated with a subset of RUs in the first group of RUs.

3. The STA as described in claim 1, wherein the feedback response is provided in terms of a signal-to-noise ratio (SNR).

4. The STA as described in claim 1, wherein the feedback response includes the average signal-to-noise ratio (SNR) per RU associated with one of the spatial-temporal streams of the first group of RUs.

5. The STA as described in claim 1, wherein the second set of subcarriers is different from the first set of subcarriers.

6. A method for execution of a first station (STA), the method comprising: A Null Data Packet Announcement (NDPA) is received, the NDPA including a first STA information field and a second STA information field, wherein the first STA information field includes: a first subcarrier packet; a first AID subfield configured to include a first STA identifier (ID) identifying the first STA; and at least one first subfield including a first resource element (RU) start index for the first STA and a second subfield including a first RU end index for the first STA, wherein the first RU start index indicated in the first subfield and the first RU end index indicated in the second subfield indicate a first group of RUs including a first group of subcarriers associated with channel status feedback, wherein the first group of RUs for the first STA is less than a 20 MHz channel bandwidth; and wherein the second STA information field includes: a second subcarrier packet; a second AID subfield configured to include a second STA ID, the second STA... ID identifies a second STA, and includes at least one third subfield of a second RU start index for the second STA and one fourth subfield of a second RU end index for the second STA, wherein the second RU start index indicated in the third subfield and the second RU end index indicated in the fourth subfield indicate a second group of RUs of a second group of subcarriers associated with channel status feedback, wherein the second group of RUs for the second STA is less than a 20 MHz channel bandwidth; receives a null data packet (NDP) for measuring a channel quality; receives a trigger frame after the NDP, the trigger frame specifying a resource allocation for a feedback response from each of the first STA and the second STA, wherein the resource allocation for the feedback response from each of the first STA and the second STA is different; based on the first STA The AID is used to identify one of the identifiers in the corresponding trigger frame to determine the channel status feedback; and in a short frame space (SIFS) following the trigger frame, the feedback response is transmitted using the resource allocation of the first STA, wherein the feedback response includes signal-to-noise ratio (SNR) information.

7. The method as described in Request 6, wherein the feedback response includes perRU feedback, the perRU feedback being associated with a subset of RUs of the first group of RUs.

8. The method as described in claim 6, wherein the feedback response is provided in terms of a signal-to-noise ratio (SNR).

9. The method as described in claim 6, wherein the feedback response includes the average signal-to-noise ratio (SNR) per RU associated with one of the spatial-temporal streams of the first group of RUs.

10. The method as described in claim 6, wherein the second set of subcarriers is different from the first set of subcarriers.

11. An access point (AP) including a transceiver and a processor, the transceiver and the processor being configured to: transmit a null data packet announcement (NDPA), the NDPA including a first STA information field and a second STA information field, wherein the first STA information field includes: A first subcarrier packet, a first AID subfield configured to include a first STA identifier (ID) identifying the first STA, and at least one first subfield including a first resource element (RU) start index for the first STA and a second subfield including a first RU end index for the first STA, wherein the first RU start index indicated in the first subfield and the first RU end index indicated in the second subfield indicate a first group of RUs of a first group of subcarriers associated with channel status feedback, wherein the first group of RUs for the first STA is less than a 20 MHz channel bandwidth; and wherein the second STA information field includes: a second subcarrier packet, a second AID subfield configured to include a second STA ID, the second STA... The system identifies a second STA and includes at least one third subfield for a second RU start index for the second STA and one fourth subfield for a second RU end index for the second STA, wherein the second RU start index indicated in the third subfield and the second RU end index indicated in the fourth subfield indicate a second group of RUs including a second group of subcarriers associated with channel status feedback, wherein the second RU group for the second STA is less than a 20MHz channel bandwidth; transmits a null data packet (NDP) for measuring a channel quality; transmits a trigger frame after the NDP, the trigger frame specifying a resource allocation for a feedback response from each of the first and second STAs, wherein the resource allocation for the feedback response from each of the first and second STAs is different; and receives the feedback response in a short frame space (SIFS) following the trigger frame using the resource allocation of the first STA, wherein the feedback response includes signal-to-noise ratio (SNR) information.

12. The AP as described in request item 11, wherein the feedback response includes perRU feedback, the perRU feedback being associated with a subset of RUs of the first group of RUs.

13. The AP as described in claim 11, wherein the feedback response is provided in terms of a signal-to-noise ratio (SNR).

14. The AP as described in claim 11, wherein the feedback response includes the average signal-to-noise ratio (SNR) per RU associated with one of the spatial-temporal streams of the first group of RUs.

15. The AP as described in claim 11, wherein the second group of subcarriers is different from the first group of subcarriers.

16. A method performed by an access point (AP), the method comprising: Sending a Null Data Packet Announcement (NDPA) containing a first STA information field and a second STA information field, wherein the first STA information field includes: a first subcarrier packet; a first AID subfield configured to include a first STA identifier (ID) identifying the first STA; and at least one first subfield including a first resource element (RU) start index for the first STA and a second subfield including a first RU end index for the first STA, wherein the first RU start index indicated in the first subfield and the first RU end index indicated in the second subfield indicate a first group of RUs of a first group of subcarriers associated with channel status feedback, wherein the first group of RUs for the first STA is less than a 20 MHz channel; and wherein the second STA information field includes: a second subcarrier packet; a second AID subfield configured to include a second STA ID, wherein the second STA... The system identifies a second STA and includes at least one third subfield containing a second RU start index for the second STA and one fourth subfield containing a second RU end index for the second STA, wherein the second RU start index indicated in the third subfield and the second RU end index indicated in the fourth subfield indicate a second group of RUs associated with a second group of subcarriers for channel status feedback, wherein the second group of RUs for the second STA is less than a 20 MHz channel bandwidth; transmits a null data packet (NDP) for measuring a channel quality; transmits a trigger frame after the NDP, the trigger frame specifying a resource allocation for a feedback response from each of the first and second STAs, wherein the resource allocation for the feedback response from each of the first and second STAs is different; and receives the feedback response in a short frame space (SIFS) following the trigger frame using the resource allocation of the first STA, wherein the feedback response includes signal-to-noise ratio (SNR) information.

17. The method as described in request item 16, wherein the feedback response includes perRU feedback, the perRU feedback being associated with a subset of RUs of the first group of RUs.

18. The method of claim 16, wherein the feedback response is provided in terms of a signal-to-noise ratio (SNR).

19. The method of claim 16, wherein the feedback response includes the average signal-to-noise ratio (SNR) per RU associated with one of the spatial-temporal streams of the first group of RUs.

20. The method as described in claim 16, wherein the second group of subcarriers is different from the first group of subcarriers.

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