Reusable beamforming information at a station

Abstract

A first station (STA) receives, from an access point (AP), a first trigger frame. The first trigger frame includes: precoding information for use by the first STA to transmit a first frame to the AP, and an index value associated with the precoding information. In response to the first trigger frame the first STA transmits, to the AP, the first frame using the precoding information. The first STA receives, from the AP, a second trigger frame including the index value. In response to the second trigger frame the first STA transmits, to a second STA and using the precoding information, a second frame.

Description

TITLEREUSABLE BEAMFORMING INFORMATION ATA STATIONCROSS-REFERENCE TO RELATED APPLICATIONS

[0001] This application claims the benefit of U.S. Provisional Application No. 63 / 571,636, filed March 29, 2024, which is hereby incorporated by reference in its entirety.BRIEF DESCRIPTION OF THE DRAWINGS

[0002] Examples of several of the various embodiments of the present disclosure are described herein with reference to the drawings.

[0003] FIG. 1 illustrates example wireless communication networks in which embodiments of the present disclosure may be implemented.

[0004] FIG. 2 is a block diagram illustrating example implementations of a station (STA) and an access point (AP).

[0005] FIG. 3 illustrates a non-High Throughput (non-HT) Physical Layer Protocol Data Unit(PPDU), a High Throughput (HT) mixed PPDU, and a Very High Throughput (VHT) PPDU.

[0006] FIG. 4 illustrates a High Efficiency (HE) Single User (SU) PPDU, an HE Multi-User (MU) PPDU, and an HE Extended Range (ER) SU PPDU.

[0007] FIG. 5 illustrates an Extremely High Throughput (EHT) Multi-user (MU) PPDU.

[0008] FIG. 6 illustrates examples of Trigger Based (TB) PPDUs which may be used by a STA for UL OFDMA or UL MU MIMO.

[0009] FIG. 7 illustrates an example trigger frame.

[0010] FIG. 8 illustrates an example Common Info field.

[0011] FIG. 9 illustrates an example management frame which may be used as an action frame.

[0012] FIG. 10 is an example that illustrates an example of using a TB PPDU.

[0013] FIG. 11 illustrates an example of a multi-user (MU) beamforming procedure.

[0014] FIG. 12 illustrates an example of an uplink beamforming procedure.

[0015] FIG. 13 illustrates an example of an uplink beamforming procedure.

[0016] FIG. 14 illustrates an example that highlights a problem that may arise in association with an uplink beamforming procedure.

[0017] FIG. 15 illustrates an example uplink beamforming procedure, according to an embodiment.

[0018] FIG. 16 illustrates an example uplink beamforming procedure, according to an embodiment.

[0019] FIG. 17 illustrates an example uplink beamforming procedure, according to an embodiment.

[0020] FIG. 18 illustrates an example process according to an embodiment.

[0021] FIG. 19 illustrates another example process according to an embodiment.DETAILED DESCRIPTION

[0022] In the present disclosure, various embodiments are presented as examples of how the disclosed techniques may be implemented and / or how the disclosed techniques may be practiced in environments and scenarios. It will be apparent to persons skilled in the relevant art that various changes in form and detail can be made therein without departing from the scope. After reading the description, it will be apparent to one skilled in the relevant art how to implement alternative embodiments. The present embodiments may not be limited by any of the described exemplary embodiments. The embodiments of the present disclosure will be described with reference to the accompanying drawings. Limitations, features, and / or elements from the disclosed example embodiments may be combined to create further embodiments within the scope of the disclosure. Any figures which highlight the functionality and advantages, are presented for example purposes only. The disclosed architecture is sufficiently flexible and configurable, such that it may be utilized in ways other than that shown. For example, the actions listed in any flowchart may be re-ordered or only optionally used in some embodiments.

[0023] Embodiments may be configured to operate as needed. The disclosed mechanism may be performed when certain criteria are met, for example, in a station, an access point, a radio environment, a network, a combination of the above, and / or the like. Example criteria may be based, at least in part, on for example, wireless device or network node configurations, traffic load, initial system set up, packet sizes, traffic characteristics, a combination of the above, and / or the like. When the one or more criteria are met, various example embodiments may be applied. Therefore, it may be possible to implement example embodiments that selectively implement disclosed protocols.

[0024] In this disclosure, “a” and “an” and similar phrases are to be interpreted as “at least one” and “one or more.” Similarly, any term that ends with the suffix “(s)” is to be interpreted as “at least one” and “one or more.” In this disclosure, the term “may” is to be interpreted as “may, for example.” In other words, the term “may” is indicative that the phrase following the term “may” is an example of one of a multitude of suitable possibilities that may, or may not, be employed by one or more of the various embodiments. The terms “comprises” and “consists of”, as used herein, enumerate one or more components of the element being described. The term “comprises” is interchangeable with “includes” and does not exclude unenumerated components from being included in the element being described. By contrast, “consists of provides a complete enumeration of the one or more components of the element being described. The term “based on”, as used herein, may be interpreted as “based at least in part on” rather than, for example, “based solely on”. The term “and / or” as used herein represents any possible combination of enumerated elements. For example, “A, B, and / or C” may represent A; B; C; A and B; A and C; B and C; or A, B, and C.

[0025] If A and B are sets and every element of A is an element of B, A is called a subset of B. In this specification, only non-empty sets and subsets are considered. For example, possible subsets of B = {STA1, STA2) are: {STA1 }, {STA2}, and {STA1, STA2). The phrase “based on” (or equally “based at least on”) is indicative that the phrase following the term “based on” is an example of one of a multitude of suitable possibilities that may, or may not, be employed to one or more of the various embodiments. The phrase “in response to” (or equally “in response at least to”) is indicative that the phrase following the phrase “in response to” is an example of one of a multitude of suitable possibilities that may, ormay not, be employed to one or more of the various embodiments. The phrase “depending on” (or equally “depending at least to”) is indicative that the phrase following the phrase “depending on” is an example of one of a multitude of suitable possibilities that may, or may not, be employed to one or more of the various embodiments. The phrase “employi ng / using” (or equally “employing / using at least”) is indicative that the phrase following the phrase “employing / using” is an example of one of a multitude of suitable possibilities that may, or may not, be employed to one or more of the various embodiments.

[0026] The term configured may relate to the capacity of a device whether the device is in an operational or non- operational state. Configured may refer to specific settings in a device that effect the operational characteristics of the device whether the device is in an operational or non-operational state. In other words, the hardware, software, firmware, registers, memory values, and / or the like may be “configured” within a device, whether the device is in an operational or nonoperational state, to provide the device with specific characteristics. Terms such as “a control message to cause in a device” may mean that a control message has parameters that may be used to configure specific characteristics or may be used to implement certain actions in the device, whether the device is in an operational or non-operational state.

[0027] In this disclosure, parameters (or equally called, fields, or Information elements: lEs) may comprise one or more information objects, and an information object may comprise one or more other objects. For example, if parameter (IE) N comprises parameter (IE) M, and parameter (IE) M comprises parameter (IE) K, and parameter (IE) K comprises parameter (information element) J. Then, for example, N comprises K, and N comprises J. In an example embodiment, when one or more messages / frames comprise a plurality of parameters, it implies that a parameter in the plurality of parameters is in at least one of the one or more messages / frames but does not have to be in each of the one or more messages / frames.

[0028] Many features presented are described as being optional through the use of “may” or the use of parentheses. For the sake of brevity and legibility, the present disclosure does not explicitly recite each and every permutation that may be obtained by choosing from the set of optional features. The present disclosure is to be interpreted as explicitly disclosing all such permutations. For example, a system described as having three optional features may be embodied in seven ways, namely with just one of the three possible features, with any two of the three possible features or with three of the three possible features.

[0029] Many of the elements described in the disclosed embodiments may be implemented as modules. A module is defined here as an element that performs a defined function and has a defined interface to other elements. The modules described in this disclosure may be implemented in hardware, software in combination with hardware, firmware, wetware (e g., hardware with a biological element) or a combination thereof, which may be behaviorally equivalent. For example, modules may be implemented as a software routine written in a computer language configured to be executed by a hardware machine (such as C, C++, Fortran, Java, Basic, Matlab or the like) or a modeling / simulation program such as Simulink, Stateflow, GNU Octave, or LabVIEWMathScript. It may be possible to implement modules using physical hardware that incorporates discrete or programmable analog, digital and / or quantum hardware. Examples of programmable hardware comprise computers, microcontrollers, microprocessors, application-specific integrated circuits(ASICs); field programmable gate arrays (FPGAs); and complex programmable logic devices (CPLDs). Computers, microcontrollers, and microprocessors are programmed using languages such as assembly, C, C++ or the like. FPGAs, ASICs and CPLDs are often programmed using hardware description languages (HDL) such as VHSIC hardware description language (VHDL) or Verilog that configure connections between internal hardware modules with lesser functionality on a programmable device. The mentioned technologies are often used in combination to achieve the result of a functional module.

[0030] FIG. 1 illustrates example wireless communication network 100 in which embodiments of the present disclosure may be implemented. As shown in FIG. 1, the example wireless communication networks may include an Institute of Electrical and Electronic Engineers (IEEE) 802.11 (WLAN) infra-structure network 102. WLAN infra-structure network 102 may include one or more basic service sets (BSSs) 110 and 120 and a distribution system (DS) 130.

[0031] BSS 110-1 and 110-2 each includes a set of an access point (AP or AP STA) and at least one station (STA or non-AP STA). For example, BSS 110-1 includes an AP 104-1 and a STA 106-1, and BSS 110-2 includes an AP 104-2 and STAs 106-2 and 106-3. The AP and the at least one STA in a BSS perform an association procedure to communicate with each other.

[0032] DS 130 may be configured to connect BSS 110-1 and BSS 110-2. As such, DS 130 may enable an extended service set (ESS) 150. Within ESS 150, APs 104-1 and 104-2 are connected via DS 130and may have the same service set identification (SSID).

[0033] WLAN infra-structure network 102 may be coupled to one or more external networks. For example, as shown in FIG. 1, WLAN infra-structure network 102 may be connected to another network 108 (e.g., 802.X) via a portal 140. Portal 140 may function as a bridge connecting DS 130 of WLAN infra-structure network 102 with the other network 108.

[0034] The example wireless communication networks illustrated in FIG. 1 may further include one or more ad-hoc networks or independent BSSs (IBSSs). An ad-hoc network or IBSS is a network that includes a plurality of STAs that are within communication range of each other. The plurality of STAs are configured so that they may communicate with each other using direct peer-to-peer communication (e.g., not via an AP).

[0035] For example, in FIG. 1, STAs 106-4, 106-5, and 106-6 may be configured to form a first IBSS 112-1. Similarly, STAs 106-7 and 106-8 may be configured to form a second IBSS 112-2. Since an IBSS does not include an AP, it does not include a centralized management entity. Rather, STAs within an IBSS are managed in a distributed manner. STAs forming an IBSS may be fixed or mobile.

[0036] A STA as a predetermined functional medium may include a medium access control (MAC) layer that complies with an IEEE 802.11 standard. A physical layer interface for a radio medium may be used among the APs and the non- AP stations (STAs). The STA may also be referred to using various other terms, including mobile terminal, wireless device, wireless transmit / receive unit (WTRU), user equipment (UE), mobile station (MS), mobile subscriber unit, or user. For example, the term “user" maybe used to denote a STA participating in uplink Multi-user Multiple Input, Multiple Output (MU MIMO) and / or uplink Orthogonal Frequency Division Multiple Access (OFDMA) transmission.

[0037] A physical layer (PHY) protocol data unit (PPDU) may be a composite structure that includes a PHY preamble and a payload in the form of a PLCP service data unit (PSDU). For example, the PSDU may include a PHY Convergence Protocol (PLCP) preamble and header and / or one or more MAC protocol data units (MPDUs). The information provided in the PHY preamble may be used by a receiving device to decode the subsequent data in the PSDU. In instances in which PPDUs are transmitted over a bonded channel (channel formed through channel bonding), the preamble fields may be duplicated and transmitted in each of the multiple component channels. The PHY preamble may include both a legacy portion (or “legacy preamble”) and a non-legacy portion (or “non-legacy preamble”). The legacy preamble may be used for packet detection, automatic gain control and channel estimation, among other uses. The legacy preamble also may generally be used to maintain compatibility with legacy devices. The format of, coding of, and information provided in the non-legacy portion of the preamble is based on the particular IEEE 802.11 protocol to be used to transmit the payload.

[0038] A frequency band may include one or more sub-bands or frequency channels. For example, PPDUs conforming to the IEEE 802.11n, 802.11ac, 802.11 ax and / or 802.11 be standard amendments may be transmitted over the 2.4 GHz, 5 GHz, and / or 6 GHz bands, each of which may be divided into multiple 20 MHz channels. The PPDUs may be transmitted over a physical channel having a minimum bandwidth of 20 MHz. Larger channels may be formed through channel bonding. For example, PPDUs may be transmitted over physical channels having bandwidths of 40 MHz, 80 MHz, 160 MHz, or 520 MHz by bonding together multiple 20 MHz channels.

[0039] FIG. 2 is a block diagram 200 illustrating example implementations of a STA 210 and an AP 260. As shown in FIG. 2, STA 210 may include at least one processor 220, a memory 230, and at least one transceiver 240. AP 260 may include at least one processor 270, a memory 280, and at least one transceiver 290. Processor 220 / 270 may be operatively connected to memory 230 / 280 and / or to transceiver 240 / 290.

[0040] Processor 220 / 270 may implement functions of the PHY layer, the MAC layer, and / or the logical link control (LLC) layer of the corresponding device (STA 210 or AP 260). Processor 220 / 270 may include one or more processors and / or one or more controllers. The one or more processors and / or one or more controllers may comprise, for example, a general-purpose processor, a digital signal processor (DSP), a microcontroller, an application specific integrated circuit (ASIC), a field programmable gate array (FPGA), a logic circuit, or a chipset, for example.

[0041] Memory 230 / 280 may include a read-only memory (ROM), a random-access memory (RAM), a flash memory, a memory card, a storage medium, and / or other storage unit. Memory 230 / 280 may comprise one or more non-transi tory computer readable mediums. Memory 230 / 280 may store computer program instructions or code that may be executed by processor 220 / 270 to carry out one or more of the operations / embodiments discussed in the present application. Memory 230 / 280 may be implemented (or positioned) within processor 220 / 270 or external to processor 220 / 270. Memory 230 / 280 may be operatively connected to processor 220 / 270 via various means known in the art.

[0042] Transceiver 240 / 290 may be configured to transmit / receive radio signals. In an embodiment, transceiver 240 / 290 may implement a PHY layer of the corresponding device (STA 210 or AP 260). In an embodiment, STA 210 and / or AP 260 may be a multi-link device (MLD), that is a device capable of operating over multiple links as defined bythe IEEE 802.11 standard. As such, STA 210 and / or AP 260 may each implement multiple PHY layers. The multiple PHY layers may be implemented using one or more of transceivers 240 / 290.

[0043] FIG. 3 illustrates an example 300 of non-High Throughput (non-HT) PPDU 310, a High Throughput (HT) mixed mode PPDU 320, and a Very High Throughput (VHT) PPDU 330.

[0044] Non-HT PPDU 310 may be used by STAs conforming to the IEEE 802.11a standard amendment. As shown in FIG. 3, non-HT PPDU 310 includes a non-HT Short Training field (L-STF), a non-HT Long Training field (L-LTF), a non- HT Signal field (L-SIG), and a Data field. The L-STF, L-LTF, and L-SIG form a 20 pis preamble of non-HT PPDU 310.

[0045] The L-STF may be used by a receiver of non-HT PPDU 310 to synchronize with the carrier frequency and frame timing of a transmitter of non-HT PPDU 310 and to adjust the receiver signal gain. The L-LTF may be used by the receiver of non-HT PPDU 310 to estimate channel coefficients in order to equalize the channel response (e.g., amplitude and phase distortion) in both the L-SIG and the Data fields of non-HT PPDU 310.

[0046] The L-SIG contains parameters needed to demodulate the Data field, which contains a payload of non-HT PPDU 310. The L-SIG may be equalized using the channel coefficients estimated using the L-LTF and demodulated to obtain the demodulation parameters of the Data field. The Data Field includes one or more symbols each having a duration of 4 pis, where 3.2 pis carry symbol information and 0.8 pis carry a Guard Interval (Gl).

[0047] For non-HT PPDUs, the only supported bandwidth is 20 MHz, which is divided into 64 subcarriers. As such, non- HT PPDU 310 may be encoded using a subcarrier spacing of 20MHz / 64 or 312.5kHz.

[0048] HT mixed mode PPDU 320 may be used by STAs conforming to the IEEE 802.11n standard amendment. HT mixed mode PPDU 320 can support MIMO to up to 4 spatial streams, which enhances spectral efficiency four folds. HT mixed mode PPDU 320 has a minimum preamble duration of 35.6 pis, which may increase depending on the number of spatial streams carried by the PPDU.

[0049] As shown in FIG. 3, HT mixed mode PPDU 320 includes an L-STF, an L-LTF, an L-SIG, an HT Signal field (HT- SIG) field, an HT Short Training field (HT-STF) field, one or more HT Long Training field (HT-LTF), and a data field. The HT-LTF and data fields include of one or more symbols each having a duration of 3.6 pis or 4 pis. In both cases, 3.2 pis carry symbol information while the remaining 0.4 pis or 0.8 pis carry a Gl. The 0.4 pis long Gl is called short Gl while the 0.8 pis long Gl is called regular or normal Gl.

[0050] For HT mixed mode PPDUs, two bandwidths, 20 MHz and 140 MHz, may be supported. When the PPDU bandwidth is 20MHz, the band is divided into 64 subcarriers. When the PPDU bandwidth is 140 MHz, the band is divided into 128 subcarriers. In both cases, subcarrier spacing of 312.5 kHz is maintained.

[0051] VHT PPDU 330 may be used by STAs conforming to the IEEE 802.11 ac standard amendment. VHT PPDU 330 can support MIMO transmission to up to 8 spatial streams, which enhances spectral efficiency eight folds. VHT PPDU 330 has a minimum preamble duration of 39.6 pis, which may increase depending on the number of spatial streams carried by VHT PPDU 330.

[0052] As shown in FIG. 3, VHT PPDU 330 includes an L-STF, an L-LTF, an L-SIG, a VHT Signal A field (VHT-SIG- A), a VHT Short Training field (VHT-STF), one or more VHT Long Training field (VHT-LTF), a VHT Signal B field (VHT-SIG-B), and a Data field. The VHT-LTF and Data fields of VHT PPDU 330 include one or more symbols each having a duration of 3.6 ps or 4 ps. In both cases, 3.2 ps carry symbol information while the remaining 0.4 ps or 0.8 ps carry of the Gl. The 0.4 ps long Gl is called the Short Gl while the 0.8ps long is called regular or normal Gl.

[0053] For VHT PPDUs, four bandwidths, 20 MHz, 40 MHz, 80 MHz, and 160 MHz, may be supported. When the PPDU bandwidth is 20MHz, the band is divided into 64 subcarriers. When the PPDU bandwidth is 40 MHz, the band is divided into 128 subcarriers. When the PPDU bandwidth is 80MHz, the band is divided into 256 subcarriers. When the PPDU bandwidth is 160 MHz, the band is divided into two 256-subcarrier 80 MHz bands. In all cases, a subcarrier spacing of 312.5 kHz is maintained.

[0054] FIG. 4 illustrates an example 400 of a High Efficiency (HE) Single User (SU) PPDU 410, and an HE Multi-User (MU) PPDU 420, and an HE Extended Range (ER) SU PPDU 430. HE SU PPDU 410, HE MU PPDU 420, and HE ER SU PPDU 430 may be used by STAs conforming to the IEEE 802.11 ax standard amendment.

[0055] HE SU PPDU 410 supports higher spectral efficiency compared to VHT PPDU 330 due to increased subcarrier spacing and higher order modulation support. HE SU PPDU 410 has a minimum preamble duration of 44 s.

[0056] As shown in FIG. 4, HE SU PPDU 410 includes an L-STF, an L-LTF, an L-SIG, a Repeated L-SIG (RL-SIG), an HE Signal A field (HE-SIG-A), an HE Short Training field (HE-STF) field, one or more HE Long Training field (HE-LTF), a Data field, and a PE field.

[0057] Similar to HE SU PPDU 410, HE MU PPDU 420 supports higher spectral efficiency compared to VHT PPDU 330. HE MU PPDU 420 also supports OFDMA. Due to denser subcarrier spacing (as in HE SU PPDU 410), HE MU PPDU 420 allows for payloads of multiple users to be multiplexed in the frequency domain in the Data field. HE MU PPDU 420 supports multiplexing the payload of up to 9 users in a single 20 MHz band. HE MU PPDU 420 has a minimum preamble duration of 47.2 ps, which may increase depending on the number of spatial streams carried by HE MU PPDU 420.

[0058] As shown in FIG. 4, HE MU PPDU 420 includes an L-STF, an L-LTF, an L-SIG, an RL-SIG, an HE-SIG-A, an HE Signal B Field (HE-SIG-B), an HE-STF field, one or more HE-LTF field, a Data field, and a PE field. It is noted that compared to HE SU PPDU 410, HE MU PPDU 420 further includes HE-SIG-B. HE-SIG-B contains indications per STA of RU allocations. A STA may use the indications in HE-SIG-B to locate its payload in HE MU PPDU 420.

[0059] For HE SU PPDU 410 and HE MU PPDU 420, the Gl portion of the HE-LTF and Data field may be one of one of 0.8 ps, 1.6 ps, and 3.2 ps. An AP or STA may use a suitable Gl duration depending on the channel conditions or capability of the target STA or AP.

[0060] For both HE SU PPDU 410 and HE MU PPDU 420, the information portion of the HE-LTF may be one of 3.2 ps, 6.4 ps, or 12.8 ps. Depending on the information portion duration, a subcarrier spacing of the HE-LTF may be one of: 312.5kHz if the information potion is 3.2 ps, 156.25kHz if the information portion is 6.4 ps, and 78.125kHz if the information portion is 12.8 ps. Unlike the HE-LTF, the information portion of the Data field for both HE SU PPDU 410 and HE MU PPDU 420 is always 12.8 ps. Hence, a subcarrier spacing of the Data field is always 78.125kHz corresponding to the duration of the information portion being 12.8 ps. When a 3.2 ps or 6.4 ps long HE-LTF is used by a transmittingSTA to transmit HE SU PPDU 410 or HE MU PPDU 420, a receiving STA is required to interpolate the channel estimates to a subcarrier spacing resolution of 78.125kHz to match the subcarrier spacing of the Data field.

[0061] As shown in FIG. 4, HE ER SU PPDU 430 includes an L-STF, an L-LTF, an L-SIG, an RL-SIG, an HE-SIG-A, an HE-STF, one or more HE-LTF, a Data field, and a PE field. It is noted that compared to HE SU PPDU 410, HE ERSU PPDU 430 has an HE-SIG-A that is duplicated in the time domain (16 pis long instead of 8 ps long in HE SU PPDU 410). As such, both L-SIG (duplicated using RL-SIG) and HE-SIG-A are sent in duplicates, which allows a receiving STA to combine the two copies to increase the energy of the received signal. This results in an extended range of reception and increases transmission reliability between the transmitting STA and the receiving STA.

[0062] FIG. 5 illustrates an example 500 of an Extremely High Throughput (EHT) Multi-user (MU) PPDU. EHT MU PPDU 510 supports OFDMA up to a bandwidth of 320MHz. EHT MU PPDU 510 can improve spectral efficiency due to support of a higher order modulation compared to other PPDUs (e.g. , HE SU PPDU 410 and HE MU PPDU 420) while supporting the same number of spatial streams. EHT MU PPDU 510 has a minimum preamble duration of 47.2 ps, which may increase depending on the number of spatial streams carried by EHT MU PPDU 510.

[0063] As shown in FIG.5, EHT MU PPDU 510 includes an L-STF, an L-LTF, an L-SIG, an RL-SIG, a Universal Signal field (U-SIG), an EHT Signal field (EHT-SIG), an EHT Short Training Field (EHT-STF), one or more EHT Long Training fields (EHT-LTF), a Data field, and a PE field. It is noted that according to the IEEE 802.11 be standard amendment, EHT MU PPDU 510 may be used by a transmitting STA for both SU and MU transmissions. Ultra-High Reliability (UHR) MU PPDU maybe similar to EHT MU PPDU 510 (e.g., may contain EHT / UHR modulated fields (EHT-STF and beyond) and non-EHT / UHR modulated fields (L-STF to EHT-SIG)).

[0064] The U-SIG is intended to ensure forward compatibility of EHT MU PPDU 510. This means that any future PPDUs that are backward compatible to IEEE 802.11be will contain the same U-SIG field and interpretation. Because of this, IEEE 802.11 be STAs will be able to understand at least in part a PPDU developed in a future amendment.

[0065] The EHT-SIG contains indications per STA of resource unit (RU) allocations. A STA may use the indications in the EHT-SIG to locate its payload in EHT MU PPDU 510.

[0066] The G I portion of the EHT-LTF and Data fields of EHT MU PPDU 510 may be one of: 0.8 s, 1.6 ps, or 3.2 ps. An AP or STA may use a suitable Gl duration depending on the channel conditions or capability of the target STA or AP.

[0067] The information portion of the EHT-LTF maybe one of 3.2 ps, 6.4 ps, or 12.8 ps. Depending on the information portion duration, a subcarrier spacing of the EHT-LTF may be one of: 312.5kHz if the information potion is 3.2 ps, 156.25kHz if the information portion is 6.4 ps, or 78.125kHz if the information portion is 12.8 ps. The information portion of the Data field of EHT MU PPDU 510 is always 12.8 ps. Hence, a subcarrier spacing of the Data field is always 78.125kHz corresponding to the duration of the information portion being 12.8 ps. When a 3.2 ps long or a 6.4 ps long EHT-LTF is used by a transmitting STA to transmit EHT MU PPDU 510, a receiving STA is required to interpolate the channel estimates to a subcarrier spacing resolution of 78.125kHz to match the Data field subcarrier spacing.

[0068] FIG. 6 illustrates examples of TB PPDUs which may be used by a STA for UL OFDMA (e.g., as in example 400) or UL MU MIMO (e.g., as in example 500). HE TB PPDU 610 maybe used by a STA conforming to the IEEE 802.11axstandard amendment. HE TB PPDU 610 shares the high spectral efficiency of HE SU PPDU 410 and HE MU PPDU 420 described with FIG. 4. As shown in FIG. 6, HE TB PPDU 610 includes an L-STF, an L-LTF, an L-SIG, a Repeated L-SIG (RL-SIG), an HE-SIG-A, an HE-STF, one or more HE-LTF, a Data field, and a PE field. It is noted that compared to HE SU PPDU 410, HE TB PPDU 610 has a double duration HE-STF (8 ps instead of 4 ps). This improves time and carrier frequency synchronization needed to receive a TB PPDU such as HE TB PPDU 610.

[0069] UHR TB PPDU may be similar to HE / EHT TB PPDU (e.g. may contain HE / EHT / UHR modulated fields (HE- STF / E HT-STF and beyond) and non-HE / EHT / UHR modulated fields (L-STF to HE-SIG-A / U-SIG)).

[0070] The Gl portion of the HE-LTF and Data field of HE TB PPDU 610 may be one of: 0.8 ps, 1.6 ps, or 3.2 ps. An AP or a STA may use a suitable Gl duration depending on the channel conditions or capability of the target STA or AP.

[0071] The information portion of the HE-LTF of HE TB PPDU 610 may be one of: 3.2 ps, 6.4 ps, or 12.8 ps. Depending on the information portion duration, a subcarrier spacing of the HE-LTF maybe one of: 312.5kHz if the information potion is 3.2 ps, 156.25kHz if the information portion is 6.4 ps, or 78 125kHz if the information portion is 12.8 ps.

[0072] The information portion of the Data field of HE TB PPDU 610 is always 12.8 ps. Hence, a subcarrier spacing of the Data field is always 78.125kHz corresponding to the duration of the information portion being 12.8 ps.

[0073] When a 3.2 ps long or a 6.4 ps long HE-LTF is used by a transmitting STA to transmit HE TB PPDU 610, a receiving STA is required to interpolate the channel estimates to a subcarrier spacing resolution of 78.125kHz to match the Data field subcarrier spacing.

[0074] EHT TB PPDU 620 may be used by a STA conforming to the IEEE 802.11 be standard amendment. As shown in FIG. 6, EHT TB PPDU 620 includes an L-STF, an L-LTF, an L-SIG, an RL-SIG, a U-SIG, an EHT-STF, one or more EHT-LTF, a Data field, and a PE field.

[0075] Similar to HE TB PPDU 610, the Gl portion of the Data field EHT TB PPDU 620 can be one of: 0.8 ps, 1 6 ps, or 3.2 ps. In consequence, the non-GI portion of the Data Field, which has a fixed duration of 12.8 ps, may have a duration of 13.6 ps, 14.4 ps, or 16 ps. An AP or STA may use a suitable Gl depending on the channel conditions or capability of the target STA or AP. The subcarrier spacing at the Data field is equal to 78.125 kHz regardless of PPDU bandwidth.

[0076] The non-GI portion of the EHT-LTF of EHT TB PPDU 620 may be 3.2 ps, 6.4 ps or 12.8 ps long. This results in a subcarrier spacing of 312.5 kHz, 156.25 kHz, or 78.125 kHz, respectively. When a 3.2ps long or a 6.4ps long EHT- LTF is used by a transmitting STA, a receiving STA is required to interpolate the channel estimates to a subcarrier spacing resolution of 78.125kHz to match the Data field subcarrier spacing.

[0077] As mentioned above, HE-LTFs in HE PPDUs such as HE SU PPDU 410, HE MU PPDU 420, HE ER SU PPDU 430, and HE TB PPDU 610 may be transmitted using a subcarrier spacing of 312.5kHz (information duration of 3.2 ps) or a subcarrier spacing of156.25 kHz (information duration of 6.4 ps), instead of a subcarrier spacing of 78.125kHz (information duration of 12.8 ps).

[0078] Similarly, EHT-LTFs in EHT PPDUs such as EHT MU PPDU 510 and EHT TB PPDU 620 may be transmitted using a subcarrier spacing of 312.5kHz (information duration of 3.2 ps) or a subcarrier spacing of 156.25 kHz (information duration of 6.4 ps), instead of a subcarrier spacing of 78.125kHz (information duration of 12.8 ps).

[0079] An HE-LTF or an EHT-LTF with a subcarrier spacing of 78.125kHz (e.g., equal to the subcarrier spacing of the Data field) increases decoding accuracy but results in a larger overhead especially when the PPDU includes several HE- LTFs or EHT-LTFs. Using an HE-LTF or an EHT-LTF with a larger subcarrier spacing reduces the overhead. However, a larger subcarrier spacing may require an interpolation circuitry at the receiver to generate intermediate channel estimates for subcarriers present in the Data field that are not present in the HE-LTF or EHT-LTF. In addition to increasing receiver complexity and cost, an interpolation circuit may degrade performance due to processing noise added by the interpolation step.

[0080] FIG. 7 illustrates an example trigger frame 700. Trigger frame 700 may correspond to a basic trigger frame as defined in the existing IEEE 802.11ax standard amendment. Trigger frame 700 may be used by an AP to allocate resources for and solicit one or more TB PPDU transmissions from one or more STAs. Trigger frame 700 may also carry other information required by a responding STA to transmit a TB PPDU to the AP.

[0081] As shown in FIG. 7, trigger frame 700 includes a Frame Control field, a Duration field, a receiver address (RA) field, a transmitter address (TA) field, a Common Info field, a User List Info field, a Padding field, and an FCS field.

[0082] The Frame Control field includes the following subfields: protocol version, type, subtype, To DS, From DS, more fragments, retry, power management, more data, protected frame, and +HTC.

[0083] The Duration field indicates various contents depending on frame type and subtype and the QoS capabilities of the sending STA. For example, in control frames of the power save poll (PS-Poll) subtype, the Duration field carries an association identifier (AID) of the STA that transmitted the frame in the 16 least significant bits (LSB), and the 2 most significant bits (MSB) are both set to 1 . In other frames sent by STAs, the Duration field contains a duration value (in microseconds) which is used by a recipient to update a network allocation vector (NAV).

[0084] The RA field is the address of the STA that is intended to receive the incoming transmission from the transmitting station. The TA field is the address of the STA transmitting trigger frame 700 if trigger frame 700 is addressed to STAs that belong to a single BSS. The TA field is the transmitted BSSID if the trigger frame 700 is addressed to STAs from at least two different BSSs of the multiple BSSID set.

[0085] The common info field may have a format as illustrated by common info field in example common info field 800 described further below. The common info field specifies a trigger frame type of trigger frame 700, a transmit power of trigger frame 700 in dBm, and several key parameters of a TB PPDU that is transmitted by a STA in response to trigger frame 700. The trigger frame type of a trigger frame used by an AP to receive QoS data using UL MU operation is referred to as a basic trigger frame.

[0086] The User List Info field contains a User Info field per STA addressed in trigger frame 700. The per STA User Info field includes, among others, an AID subfield, an RU Allocation subfield, a Spatial Stream (SS) Allocation subfield, an MCS subfield to be used by a STA in a TB PPDU transmitted in response to trigger frame 700, and a TriggerDependent User Info subfield. The Trigger Dependent User Info subfield can be used by an AP to specify a preferred access category (AC) per STA. The preferred AC sets the minimum priority AC traffic that can be sent by a participating STA The AP determines the list of participating STAs, along with the BW, MCS, RU allocation, SS allocation, Tx power, preferred AC, and maximum duration of the TB PPDU per participating STA.

[0087] The Padding field is optionally present in trigger frame 700 to extend the frame length to give recipient STAs enough time to prepare a response for transmission one SIPS (short interframe spacing) after the frame is received. The Padding field, if present, is at least two octets in length and is set to all 1s.

[0088] The FCS field is used by a STA to validate a received frame and to interpret certain fields from the MAC headers of a frame.

[0089] FIG. 8 illustrates an example Common Info field 800. Common Info field 800 may be an embodiment of the Common Info field of trigger frame 700 or an MU-RTS trigger frame, for example. As shown in FIG. 8, Common Info field 800 may include a Trigger Type subfield, a UL Length subfield, a More TF subfield, a CS required subfield, a UL BW subfield, a Gl and HE / EHT-LTF Type / Triggered TXS Mode subfield, a first Reserved subfield, a Number of HE / EHT-LTF Symbols subfield, a second Reserved subfield, an LDPC Extra Symbol Segment subfield, an AP Tx Power subfield, a Pre-FEC Padding Factor subfield, a PE Disambiguity subfield, an UL Spatial Reuse subfield, a third Reserved subfield, an HE / EHT P160 subfield, a Special User Info Field Flag subfield, an EHT Reserved subfield, a fourth Reserved subfield, and a Trigger Dependent Common Info subfield. The Trigger Type subfield, UL Length subfield, More TF subfield, CS required subfield, UL BW subfield, Gl and HE-LTF Type / Triggered TXS Mode subfield, first Reserved subfield, Number of HE / EHT-LTF Symbols subfield, second Reserved subfield, LDPC Extra Symbol Segment subfield, AP Tx Power subfield, Pre-FEC Padding Factor subfield, PE Disambiguity subfield, UL Spatial Reuse subfield, third Reserved subfield, HE / EHT P160 subfield, Special User Info Field Flag subfield, EHT Reserved subfield, fourth Reserved subfield, and Trigger Dependent Common Info subfield may have the same content and interpretation as corresponding subfields of an EHT variant Common Info field defined in the IEEE 802.11be draft amendment (“IEEE P802.11be / D3.1, March 2023”).

[0090] FIG. 9 illustrates an example management frame 900 which may be used as an action frame. In an example, management frame 900 includes a MAC header, a variable length frame body, and a frame check sequence (FCS). The MAC header includes a frame control field, a duration field, an address 1 field, an address 2 field, an address 3 field, a sequence control field, and an optional HT control field. The presence of the HT control field is determined by the setting of a +HTC subfield of the frame control field.

[0091] As shown in FIG. 9, when used as an action frame, the frame body of management frame includes an action field, vendor specific elements, management message integrity code element (MME), message integrity code (MIC), and an authenticated mesh peering exchange element.

[0092] The action field includes a category field and an action details field. The action field provides a mechanism for specifying extended management actions. The category field indicates a category of the action frame. The action details field contains the details of the action requested by the action frame.

[0093] The MME is present when management frame protection is negotiated, the frame is a group addressed robust Action frame, and (MBSS only) the category of the action frame does not support group addressed privacy as indicated by category values; otherwise not present.

[0094] The MIC element is present in a self-protected action frame if a shared pairwise master key (PMK) exists between the sender and recipient of this frame; otherwise not present.

[0095] The authenticated mesh peering exchange element is present in a self-protected action frame if a shared PMK exists between the sender and recipient of this frame; otherwise not present.

[0096] FIG. 10 is an example 1000 that illustrates an example of using a TB PPDU. As shown in FIG. 10, example 1000 includes an AP 1041 and a plurality of STAs 1052-1 to 1052-8.

[0097] In an example, AP 1041 may transmit an HE MU PPDU 1010 to STAs 1052-1 to 1052-8. In an example, to reduce protocol overhead, HE MU PPDU 1010 may aggregate within the same MU PPDU both TFs and BA frames. For example, HE MU PPDU 1010 may include a plurality of BA frames transmitted respectively in response to a plurality of TB PPDUs (not shown in FIG. 10) transmitted by STAs 1052-1 to 1052-8. In addition, HE MU PPDU 1010 may include a plurality of TFs soliciting UL frames from STAs 1052-1 to 1052-8.

[0098] STAs 1052-1 to 1052-8 may respond simultaneously to HE MU PPDU 1010 by each transmitting an MU MIMO TB PPDU 1020. In an example, MU MIMO TB PPDU 1020 may have an 80 MHz bandwidth. As shown in FIG. 8, a STA 1052-1 to 1052-8 may duplicate four times over frequency each of fields L-STF, L-LTF, L-SIG, RL-SIG, U-SIG, and EHT- STF to fill out the 80 MHz bandwidth. EHT-LTFs 1040-1 to 1040-8 and a data field 1050 of PPDU 1020 may fill out the entire 80 MHz bandwidth and are not duplicated over frequency. The number of EHT-LTFs transmitted by the STA (in time) is based on the number of users accessing the channel using MU MIMO TB PPDU 1020. In example 1000, MU MIMO TB PPDU 1020 includes eight EHT-LTFs 1040-1 to 1040-8.

[0099] AP 1041 may acknowledge MU MIMO TB PPDU 1020 by transmitting HE MU PPDU 1030. Like HE MU PPDU 1010, HE MU PPDU 1030 may aggregate both TFs (soliciting further UL frames from STAs 1052-1 to 1052-8) and BA frames (acknowledging the TB PPDUs contained in MU MIMO TB PPDU 1020).

[0100] In an example 1000, it is assumed that PPDUs 1010, 1020, and 1030 are all transmitted using a bandwidth of 80 MHz. Further, EHT-LTFs 1040-1 to 1040-8 of MU MIMO TB PPDU 1020 use the same subcarrier spacing (78.125 kHz) as data field 1050 of TB PPDU 1020. As such, each EHT-LTF 1040-1 to 1040-8 has a 16 pis duration.

[0101] As shown in FIG. 10, the total access latency of a STA 1052-1 to 1052-8 is equal to the combined duration of an HE MU PPDU (e.g. , HE MU PPDU 1010), a SIFS duration, and a TB PPDU (e.g., 1020). To reduce the access latency, the HE MU PPDU may be replaced with a single spatial stream EHT MU PPDU in order to avoid a long string of EHT- LTFs in the time domain. On the other hand, the same cannot be done with MU-MIMO TB PPDU 1020, which is a multiple spatial stream PPDU. This results in a large overhead due to the EHT-LTFs 1040-1 to 1040-8 of TB PPDU 1020. For example, in the case of 8 UL STAs, the total overhead due to the EHT-LTFs is 128 pis. In some scenarios, such as real time control where the payload can fit in a single 16 ps data field, a total EHT-LTF duration of 128 pis per 8 STA is highly inefficient.

[0102] FIG. 11 illustrates an example 1100 of a multi-user (MU) beamforming procedure. An MU beamforming transmission procedure allows an AP to transmit a frame to multiple STAs using the same time and frequency resources by applying a set of beamforming weights to cancel inter-user interference to each STA. As shown in FIG. 11, example 1100 includes an AP 1102 and STAs 1104, 1106, and 1108. STAs 1104, 1106, and 1108 may be associated with AP 1102.

[0103] In an implementation, the MU beamforming procedure may include a sounding phase / procedure, which AP 1102 may use to acquire channel state information from STAs 1104, 1106, and 1108. The sounding phase / procedure may begin with AP 1102 transmitting a null data packet announcement (NDPA) frame 1110 to STAs 1104, 1106, and 1108. NDPA frame 1110 announces to STAs 1104, 1106, and 1108 the transmission of one or more sounding frames by AP 1102.

[0104] Next, AP 1102 may transmit a null data packet (NDP) frame 1112 to STAs 1104, 1106, and 1108. STAs 1104, 1106, and 1108 each receives NDP frame 1112 and uses NDP frame 1112 to estimate the downlink channel from AP 1102. Specifically, STA 1104 estimates the downlink channel from AP 1102 to STA 1104; STA 1106 estimates the downlink channel from AP 1102 to STA 1106; and STA 1108 estimates the downlink channel from AP 1102 to STA 1108.

[0105] Subsequently, AP 1102 may transmit a beamforming report poll (BFRP) frame 1114 to STAs 1104, 1106, and 1108 to retrieve the downlink channel estimates from STAs 1104, 1106, and 1108. STAs 1104, 1106, and 1108 may respond to BFRP frame 1114 by transmitting respectively beamforming report (BFR) frames 1116, 1118, and 1120 to AP 1102. BFR frames 1116, 1118, and 1120 may include the downlink channel estimates calculated respectively by STAs 1104, 1106, and 1108.

[0106] In an implementation, AP 1102 may use the downlink channel estimates calculated by STAs 1104, 1106, and 1108 to perform a MU beamforming transmission 1122 to one or more of STAs 1104, 1106, and 1108. The MU beamforming transmission may include a beamformed transmission to one or more of STAs 1104, 1106, and 1108.

[0107] FIG. 12 illustrates an example 1200 of an uplink beamforming procedure. As shown in FIG. 12, example 1200 includes AP 1202 and STAs 1204, 1206, and 1208. STAs 1204, 1206, and 1208 maybe associated with AP 1202.

[0108] An uplink beamforming procedure may be done in a similar manner as the sounding phase / procedure described for the downlink MU beamforming procedure described in example 1100. As described below, instead of AP 1202 transmitting an NDP and receiving BFR frames from non-AP STAs 1204, 1206, and 1208, as in FIG. 11, AP 1202 solicits NDP frames from non-AP STAs 1204, 1206, and 1208, and transmit BFR frames 1230A-B to the non-AP STAs in a feedback frame 1220.

[0109] The uplink beamforming procedure of example 1200 may begin with AP 1202 transmitting a beamforming sounding NDP poll (BSNP) trigger frame 1205 for requesting a sounding NDP from STAs 1204, 1206, and 1208 to obtain uplink channel state information for the respective STAs. After receiving BNSP trigger frame 1205, STAs 1204, 1206, and 1208 respectively provide sounding NDPs 1260A-C to AP 1202. Based on NDPs 1260A-C, AP 1202 estimates an uplink channel state information and may generate respective compressed matrix V from the uplink channel state information for STAs 1204, 1206, and 1208.

[0110] Based on the respective compressed matrix V, AP 1202 generates respective Beamforming Reports (BFRs) 1230A-C for STAs 1204, 1206, and 1208. In this example, BFRs 1230A-C may be respectively used by STAs 1204, 1206, and 1208 to generate steering matrices for beamforming transmission of data frames 1250A-C. Based on BFRs 1230A-C, STAs 1204, 1206, and 1208 may perform decompression of the compressed matrix V contained in the respective BFRs. Then, each of STAs 1204, 1206, and 1208 may each generate steering matrices based on the uncompressed matrix V. In an alternative approach, AP 1202 may send channel state information directly to STAs 1204, 1206, and 1208 without generating respective matrix V from the channel state information. In this example, STAs 1204, 1206, and 1208 may directly generate steering matrices from the channel state information without a decompression procedure.

[0111] To request data frames 1250A-C, AP 1202 transmits trigger frame 1210 with BFRs 1230A-C included in feedback frame 1220. Similar to example 1000, data frames 1250A-C may be included in respective TB PPDUs, with each TB PPDU being transmitted in response to trigger frame 1210. In an example, feedback frame 1220 may be characterized as an uplink beamforming compressed beamforming frame (ULBF CBF). Trigger frame 1210 and feedback frame 1220 may be provided by independent PPDUs sent after SIFS of each other or through one PPDU, e.g., an aggregated message access control protocol data unit (A-MPDU) as in PPDU 1010 in example 1000.

[0112] To facilitate the generation of the steering matrices by STAs 1204, 1206, and 1208, AP 1202 may add padding 1230 to allow the generation of the steering matrices to be completed. Based on trigger frame 1210, respective STAs 1204, 1206, and 1208 transmit data frames 1250A-C, based on the respectively generated steering matrices. In response, AP 1202 transmits BA 1240.

[0113] FIG. 13 illustrates an example 1300 of an uplink beamforming procedure. As shown in FIG. 13, example 1300 includes AP 1302 and STAs 1304, 1306, and 1308. STAs 1304, 1306, and 1308 maybe associated with AP 1302.

[0114] The uplink beamforming procedure of example 1300 may begin with AP 1302 transmitting a beamforming sounding NDP poll (BSNP) trigger frame 1305 for requesting a sounding NDP from STAs 1304, 1306, and 1308 to obtain uplink channel state information for the respective STAs. After receiving BNSP trigger frame 1305, STAs 1304, 1306, and 1308 respectively provide sounding NDPs 1360A-C to AP 1302. Based on NDPs 1360A-C, AP 1302 estimates an uplink channel state information and, instead of generating respective compressed matrix V (e.g., for providing feedback to STAs 1304, 1306, and 1308 for the STAs to generate respective beam steering matrices as in FIG. 12), AP 1302 may directly generate respective beam steering matrices for STAs 1304, 1306, and 1308, based on the uplink channel state information. Based on the steering matrices, AP 1302 generates respective Beamforming Reports (BFRs) 1330A-C for STAs 1304, 1306, and 1308. AP 1302 may perform compression of respective steering matrices, before transmitting to STAs 1304, 1306, and 1308 in BFRs 1330A-C.

[0115] To request data frames 1350A-C, AP 1302 transmits trigger frame 1310 with BFRs 1330A-C included in feedback frame 1320. Similar to example 1000, data frames 1350A-C may be included in respective TB PPDUs, with each TB PPDU being transmitted in response to trigger frame 1310. In an example, feedback frame 1320 may be characterized as an uplink beamforming compressed beamforming frame (ULBF CBF). Triggerframe 1310 and feedbackframe 1320 may be provided by independent PPDUs sent after SIPS of each other or through one PPDU, e.g., an aggregated message access control protocol data unit (A-MPDU), as in PPDU 1010 in example 1000.

[0116] Based on trigger frame 1310, respective STAs 1304, 1306, and 1308 transmit data frames 1350A-C, based on BFRs 1330A-C. In response, AP 1302 transmits BA 1340.

[0117] FIG. 14 illustrates an example 1400 that highlights a problem that may arise in association with an uplink beamforming procedure. As shown in FIG. 14, example 1400 includes AP 1402 and STAs 1404 and 1406. STAs 1404 and 1406 may be associated with AP 1402.

[0118] The uplink beamforming procedure of example 1400 may begin with AP 1402 transmitting frame 1470A to STA 1404. Frame 1470A may include a trigger frame that schedules and allocates resources to receive uplink data from STA 1404. Frame 1470A may further include precoding information 1490A for STA 1404. STA 1404 may use precoding information 1490A to perform a beamformed transmission of a data frame 1480A to AP 1402. As used herein, precoding information (e.g., precoding information 1490A) may include information that facilitates uplink beamforming transmission by non-AP STAs, including, but not limited to, beamforming reports (BFRs), sounding information, channel state information feedback, channel feedback, steering matrices, and / or other similar information.

[0119] Continuing example 1400, AP 1402 may transmit a frame 1470B to STA 1404 and STA 1406. Frame 1470B may include a trigger frame that schedules and allocates resources to receive uplink data from STA 1404 and STA 1406. Frame 1470B may further include precoding information 1490C for STA 1404 and precoding information 1490B for STA 1406. STA 1404 may use precoding information 1490C to perform a beamformed uplink transmission of a data frame 1480B to AP 1402, and STA 1406 may use precoding information 1490B to perform a beamformed transmission of a data frame 1480D to AP 1402. In an example, AP 1402 may trigger STAs 1404 and 1406 to transmit data frames 1480B and 1480D respectively, using the same time and frequency resources. As such, precoding information 1490C for STA 1404 and precoding information 1490B for STA 1406 may be tailored to enable overlapping uplink beamforming transmissions from STAs 1404 and 1406. Precoding information 1490C may thus be different than precoding information 1490A provided in frame 1470A to enable the beamformed transmission of data frame 1470A to AP 1402.

[0120] In an example, at the time that STA 1404 receives frame 1470B, the memory of STA 1404 contains precoding information 1490A and the storing of precoding information 1490C in the memory of STA 1404 overwrites the storage of precoding information 1490A in the memory of STA 1404. For example, this may happen if STA 1404 predicts that precoding information 1490A will no longer be used by AP 1402.

[0121] Continuing example 1400, AP 1402 may transmit a frame 1470C to STA 1404. Frame 1470C may include a trigger frame that schedules and allocates resources to receive uplink data from STA 1404. In an example, as frame 1470C allocates resources to receive uplink data only from STA 1404, AP 1402 may determine that STA 1404 may reuse precoding information 1490A (previously sent in frame 1470A) to perform a beamformed transmission of a data frame 1480C to AP 1402.

[0122] In an example, as described above, because precoding information 1490A may have been overwritten in the memory of STA 1404, to enable STA 1404 to reuse precoding information 1490A to perform the beamformed transmissionof data frame 1480C, AP 1402 is required to retransmit precoding information 1490A to STA 1404 in frame 1470C. Depending on the bandwidth for which precoding information 1490A was computed and resolution of precoding information 1490A, retransmitting precoding information 1490A may involve retransmitting several kilobytes of information which may add 1 or 2 ms of channel overhead depending on the modulation and coding rate. This retransmission of precoding information 1490A may be an inefficient and wasteful use of network resources, including wireless channel resources required to resend precoding information 1490A, processing and power resources of AP 1402 to process and retransmit precoding information 1490A, and the processing and power resources of STA 1404 to receive and process precoding information 1490A. This is especially the case if AP 1402 retransmits precoding information 1490A when precoding information 1490A has not been overwritten by STA 1404 (e.g. STA 1404 has enough memory capacity when frame 1470B was received or when STA 1404 memory management algorithm determined not to overwrite precoding information 1490A).

[0123] Embodiments of the present disclosure, as further described below, address the above-described problem. In an aspect, a first STA may receive from a second STA, a first frame (e.g., a first trigger frame) comprising first precoding information for use by the first STA to transmit a second frame to the second STA. In embodiments, the first frame may further include a first index associated with the first precoding information. The presence of the first index in the first frame may be used by first STA as an indication from the second STA that the first precoding information may be reused in a subsequent beamformed transmission. As described herein, to facilitate reuse of the precoding information by the second STA, the first index of the first frame may include an index value that references the precoding information. In an example, the first STA may be a non-AP STA and the second STA may be an AP STA.

[0124] In another aspect, in response to a third frame (e.g., a second trigger frame) comprising the first index, the first STA may transmit to the second STA and using the first precoding information, a fourth frame. In this aspect, when the first precoding information is stored in a memory of the first STA for reuse, the first index being included with the third frame may facilitate reuse of the first precoding information without a need for the second STA to retransmit the first precoding information. Thus, in accordance with one or more embodiments, the second STA (e.g., an AP) may avoid unnecessarily wasting resources of the first STA (e.g., a non-AP STA), second STA, and the communication channel, by retransmitting the first precoding information to the first STA.

[0125] FIG. 15 illustrates an example 1500 of an uplink beamforming procedure according to an embodiment. As shown in FIG. 15, example 1500 includes AP 1502 and STAs 1504 and 1506. STAs 1504 and 1506 maybe associated with AP 1502.

[0126] The uplink beamforming procedure may begin with AP 1502 transmitting a frame 1570A to STA 1504. Frame 1570A may comprise first precoding information for use by STA 1504 to transmit a frame 1580A to AP 1502. As depicted in FIG. 15, frame 1570A includes precoding information 1590A (e.g., first precoding information) for use by STA 1504 to transmit frame 1580A to AP 1502. In different implementations, frames 1570A-C may broadly include one or more of a data frame, a management frame (e.g., discussed with FIG. 9 above), and / or a control frame (e.g., discussed with FIG. 7 above).

[0127] In embodiments, precoding information 1590A may include steering matrices (e.g., per tone or per group of tones) that STA 1504 may apply to transmit frame 1580A, e.g., similar to an approach described above with FIG. 13 in relation to the generation of precoding information 1330A-1330B. Precoding information 1590A may include beamforming matrix V (e.g., per tone or group of tones) for the MIMO channel between AP 1502 and STA 1504, e.g., similar to an approach described above with FIG. 12 in relation to the generation of precoding information 1230A-1230B. Precoding information 1590A may include channel state information comprising coefficient estimates (e.g., per tone or group of tones) for the MIMO channel between AP 1502 and STA 1504, e.g., similar to the alternative approach described above with FIG. 12 in relation to the generation of precoding information 1230A-1230B, without generating respective matrix V from channel state information.

[0128] Steering matrices may be determined by STA 1504 using the beamforming matrix V before transmitting frame 1580A. STA 1504 may determine steering matrices using the channel state information before transmitting frame 1580A. Padding may be added to frame 1570A in order to give STA 1504 time to finish determining the steering matrices from the channel state information. Padding for frame 1570A may be selected, for example, in accordance to padding 1230 in described above with FIG. 12.

[0129] STA 1504 may use precoding information 1590A of frame 1570A to perform a beamforming transmission of frame 1580A to AP 1502. Frame 1570A may comprise a trigger frame that schedules and allocates resources of AP 1502 to receive beamformed uplink data (e.g., frame 1580A) from STA 1504. With frame 1570A being a trigger frame, precoding information 1590A may be included in different ways within frame 1570A, e.g., in a common info field of the trigger frame, and / or a user info field of the trigger frame. FIG. 7 describes how user info fields and common info fields may be integrated into a trigger frame. Additionally, in FIG. 8 above, reserved and common info fields are further discussed as potentially signaling indexing and precoding information discussed herein.

[0130] In additional or alternative embodiments, frame 1570A may be implemented in an action frame. In embodiments, precoding information 1590A may be included in a UHR steering matrix field of frame 1570A, e.g., within frame 1570A as an action frame.

[0131] Continuing example 1500, after being received from AP 1502, precoding information 1590A may be stored in a memory of STA 1504 for reuse with the beamformed uplink channel in accordance with precoding information 1590A. In embodiments, frame 1570A may further include a first index 1572A associated with the storage of precoding information 1590A. In embodiments, the presence of the first index 1572A in frame 1570A may be used by STA 1504 as an indication from AP 1502 that precoding information 1590A may be reused in a subsequent beamformed transmission.

[0132] In an example implementation of the memory of STA 1504, first index 1572A may reference a first storage location within the memory for storage of channel feedback from AP 1502. With frame 1570A implemented as a trigger frame, first index 1572A may be included within frame 1570A in different ways, e.g., in the common info field of the trigger frame, the user info field of the trigger frame, and / or a UHR MIMO control field of the trigger frame.

[0133] Continuing example 1500, AP 1502 may transmit a frame 1570B to STA 1504 and STA 1506. Frame 1570B may include a trigger frame that schedules and allocates resources of AP 1502 to receive beamformed uplink data, e.g.,frame 1580B from STA 1504, and frame 1580D from STA 1506. Frame 1570B may further include precoding information 1590B for STA 1504 and precoding information 1590C for STA 1506. STA 1504 may use precoding information 1590B toperform a beamformed uplink transmission of a frame 1580 B to AP 1502, and STA 1506 may use precoding information 1590C to perform a beamforming transmission of a data frame 1580D to AP 1502.

[0134] In an example, AP 1502 may trigger STAs 1504 and 1506 to transmit frames 1580B and 1580D respectively, using the same time and frequency resources. As such, precoding information 1590B for STA 1504 and precoding information 1590C for STA 1506 may be tailored to enable overlapping uplink beamforming transmissions from STAs 1504 and 1506. Precoding information 1590B for STA 1504 may thus be different than precoding information 1590A provided for STA 1504 in frame 1570A to enable the beamformed transmission of data frame 1570A to AP 1502.

[0135] STA 1504 and STA 1506 may respectively store precoding information 1590B and precoding information 1590C for reuse with the beamformed uplink channels from STA 1504 to AP 1502, and from STA 1506 to AP 1502. Frame 1570B may include a second index 1572B associated with the storage of precoding information 1590B in a second memory location of STA 1504. Frame 1570B may include a first index 1572C associated with the storage of precoding information 1590C in a first memory location of STA 1506.

[0136] In contrast to the example discussed above in FIG. 14 however, when precoding information 1590B is stored in the memory of STA 1504, precoding information 1590A is not necessarily overwritten by precoding information 1590B. In embodiments, precoding information 1590A is not overwritten based on second index 1572B referencing a second memory location in the memory of STA 1504. In the memory of STA 1504, precoding information 1590B may be stored in the second memory location, and precoding information 1590A may remain stored in the first memory location.

[0137] Alternatively, AP 1502 may explicitly use the same memory location of previously stored precoding information (e g., the first memory location of STA 1504) to store new precoding information. For example, for precoding information 1590B, instead of second index 1572B referencing the second memory location of STA 1504, AP 1502 may include an index reference to the first memory location of STA 1504 (not shown). AP 1502 may determine to overwrite the first memory location of STA 1504 based on a determination that precoding information 1590A is not subject to a scheduled transmission.

[0138] Continuing example 1500, AP 1502 may transmit a frame 1570C to STA 1504. Frame 1570C may include a trigger frame that schedules and allocates resources of AP 1502 to receive beamformed uplink data, e.g., frame 1580C from STA 1504. Frame 1570C includes a reference to first index 1572A and no channel feedback data for use by STA 1504 to transmit frame 1580C to AP 1502. In contrast to the need for retransmission of precoding information 1490A depicted with FIG. 14, in example 1500 precoding information 1590A may remain stored in the memory of STA 1504. Precoding information 1590A may be specified by AP 1502 to be used to transmit frame 1580C, by inclusion of first index 1572A referencing stored precoding information 1590A in the first memory location of STA 1504. Thus, at least based on the foregoing, embodiments depicted with FIG. 15 may avoid the problem described above with FIG. 14.

[0139] Continuing the discussion of FIG. 15, in accordance with the process used to store precoding information 1590A based on first index 1572A described above, precoding information 1590C may be stored in memory of STA 1506 based on first index 1572C. In an example, first index 1572C may refer to a first memory location in the memory of STA 1506.

[0140] FIG. 16 illustrates an example 1600 of an uplink beamforming procedure according to an embodiment. As shown in FIG. 16, example 1600 includes an AP 1602 and STAs 1604 and 1606. STAs 1604 and 1606 maybe associated with AP 1602.

[0141] The uplink beamforming procedure may begin with AP 1602 transmitting a frame 1670A to STA 1604. Frame 1670A may comprise first precoding information for use by STA 1604 to transmit a frame 1680A to AP 1602. As depicted in FIG. 16, frame 1670A includes precoding information 1690A (e.g., the first precoding information) for use by STA 1604 to transmit frame 1680A to AP 1602. Frame 1670A may further include a request to store 1675 associated with the first precoding information. In embodiments, request to store 1675 may be included with precoding information as an indication that the precoding information is to be stored at the STA for reuse. Use of a request to store indication (e.g. request to store 1675) may be preferred for a STA with limited memory for storing precoding information. For example, AP 1602 may use request to store 1675 when STA 1604 can only store a single instance of precoding information, e.g., compared to the multiple instances of precoding information stored by STA 1504 in example 1500.

[0142] Continuing example 1600, in an embodiment, after being received from AP 1602, based on request to store 1675, precoding information 1690A may be stored in a memory of STA 1604 for reuse with the beamformed uplink channel in accordance with precoding information 1690A. In contrast to FIG. 15 above, AP 1602 may use frame 1670A to implement embodiments by including request to store 1675, as an alternative or addition to the inclusion of indices specifying that precoding information be stored, e.g., first index 1572A and second index 1572B sent by AP 1502 and described with FIG. 15 above. In an embodiment, including request to store 1675 in frame 1670A by AP 1602 may be achieved by setting a flag in frame 1670A, e.g., setting (e.g., to 1) a reserved bit in the common info field or user info field of frame 1670A, as a trigger frame. Similarly, not including request to store 1675 in frame 1670A may be achieved by AP 1602 by setting the flag in frame 1670A, e.g., setting (e.g., to 0) the reserved bit in the common info field or user info field of frame 1670A, as a trigger frame

[0143] Continuing example 1600, AP 1602 may transmit frame 1670B to STA 1604 and STA 1606. Frame 1670B includes precoding information 1690B associated with the beamformed uplink channel from STA 1604 to AP 1602, and precoding information 1690C associated with a beamformed uplink channel from STA 1606 to AP 1602. STA 1604 may use precoding information 1690B of frame 1670B to perform a beamformed uplink transmission of frame 1680B to AP 1602, and STA 1606 may use precoding information 1690C of frame 1670B to perform a beamforming transmission of frame 1680D to AP 1602.

[0144] In embodiments, based on precoding information 1690B not being accompanied by a request to store, precoding information 1690B is not stored in the memory of STA 1604. Thus, in embodiments depicted in example 1600, precoding information 1690A is not overwritten by precoding information 1690B.

[0145] Continuing example 1600, AP 1602 may transmit frame 1670C to STA 1604. Frame 1670C does not include indexes referencing the storage of precoding information discussed with FIG. 15 above. In embodiments, based on the lack of an inclusion of a request to store for precoding information 1690B in frame 1670B, precoding information 1690A was not overwritten by precoding information 1690B. Thus, precoding information 1690A remains stored for reuse in the memory of STA 1604.

[0146] Continuing the example 1600, in embodiments, based on precoding information 1690A being stored at STA 1604, STA 1604 may use precoding information 1690A to perform a beamformed uplink transmission of frame 1680C to AP 1602. Thus, in contrast to the need for retransmission of precoding information 1490A depicted with FIG. 14, in example 1600 precoding information 1690A may remain stored in the memory of STA 1604 thereby avoiding the problem described with FIG. 14 above.

[0147] FIG. 17 illustrates an example 1700 of an uplink beamforming procedure according to an embodiment. As shown in FIG. 17, example 1700 includes an AP 1702 and STA 1704. STA 1704 maybe associated with AP 1702

[0148] The uplink beamforming procedure may begin with AP 1702 transmitting a frame 1770A to STA 1704. Frame 1770A may comprise first precoding information for use by STA 1704 to transmit a frame 1780A to AP 1702. As depicted in FIG. 17, frame 1770A includes precoding information 1790A (e.g., the first precoding information) for use by STA 1704 to transmit frame 1780A to AP 1702. In embodiments, frame 1770A may further include a request to store 1775A associated with precoding information 1790A. Request to store 1775A may be included with precoding information as an indication that the precoding information is to be stored at the STA for reuse. In embodiments, after being received from AP 1702, based on request to store 1775A, STA 1704 may store precoding information 1790A in memory of STA 1704 for reuse with the beamformed uplink channel in accordance with precoding information 1790A. In an embodiment, including request to store 1775A in frame 1770A by AP 1702 may be achieved by setting a flag in frame 1770A (e.g. a reserved bit in the common info field or user info field if frame 1770A is a trigger frame) to one value (e.g. 1). Similarly, not including request to store 1775A in frame 1770A maybe achieved by the AP 1702, by setting the flag in frame 1770A (e.g. the reserved bit in the common info field or user info field if frame 1770A is a trigger frame) to another value (e.g. 0).

[0149] Continuing example 1700, AP 1702 may transmit a frame 1770B to STA 1704. Frame 1770B may comprise first precoding information for use by STA 1704 to transmit a frame 1780B to AP 1702. As depicted in FIG. 17, frame 1770B includes precoding information 1790B (e.g., the first precoding information) for use by STA 1704 to transmit frame 1780B to AP 1702. Frame 1770B may further include a request to store 1775B associated with precoding information 1790B. In embodiments, request to store 1775B may be included with precoding information as an indication that precoding information 1790B is to be stored at STA 1704 for reuse.

[0150] In embodiments, based on precoding information 1790B being accompanied by request to store 1775B, precoding information 1790B is stored for reuse in the memory of STA 1704. This storage of precoding information 1790B may overwrite the storage of precoding information 1790A in the memory of STA 1704.

[0151] Continuing example 1700, AP 1702 may transmit frame 1770C to STA 1704. Frame 1770C does not include indexes referencing the storage of precoding information discussed with FIG. 15 above. In embodiments, based on the inclusion of request to store 1775B for precoding information 1790B in frame 1770B, precoding information 1790A was overwritten by precoding information 1790B. Based on precoding information 1790B being stored at STA 1704, STA 1704 may use precoding information 1790B to perform a beamformed uplink transmission of frame 1780C to AP 1702. Thus, in contrast to the need for retransmission of precoding information 1490A depicted with FIG. 14, in example 1700 precoding information 1790B may be selected to remain stored in the memory of STA 1704 thereby avoiding the problem described with FIG. 14 above.

[0152] FIG. 18 illustrates an example process 1800 according to an embodiment. Example process 1800 is provided for the purpose of illustration only and is not limiting of embodiments. Example process 1800 may be performed by a first STA, such as non-AP STAs STA 1504, STA 1506, STA 1604, STA 1606, and / or STA 1704, for example. As shown in FIG. 18, process 1800 may include steps 1802 and 1804

[0153] Step 1802 includes receiving, by a first STA from a second STA, a first frame that may comprise first precoding information for use by the first STA to transmit a second frame to the second STA, and a first index associated with the first precoding information. In an embodiment, the first STA may be a non-AP STA and the second STA may be an AP STA. In an embodiment, the presence of the first index in the first frame may be used by the first STA as an indication from the second STA that precoding information may be reused in a subsequent beamformed transmission. In different implementations, the first frame may include a data frame, a management frame, and / or a control frame. In different implementations, the second frame may include a data frame, a management frame, and / or a control frame.

[0154] In an embodiment, first precoding information may include information that facilitates uplink beamforming transmission by non-AP STAs, including, but not limited to, beam forming reports (BFRs), sounding information, channel state information feedback, channel feedback, steering matrices, and / or other similar information. In an embodiment, the first precoding information may comprise a set of steering matrices for an ultra-high reliability (UHR) modulated field of a physical layer protocol data unit (PPDU) carrying the second frame. In an embodiment, the first precoding information may comprise a set of UHR beamforming matrices V used to determine a set of steering matrices for an ultra-high reliability (UHR) modulated field of a physical layer protocol data unit (PPDU) carrying the second frame. In an embodiment, the first precoding information may further comprise a set of uplink channel state information used to determine a set of steering matrices for an ultra-high reliability (UHR) modulated field of a PPDU carrying the second frame. In an embodiment, padding may be added to the first frame in order to give the first STA time to finish determining the steering matrices from the uplink channel state information. In an embodiment, padding may be added to the first frame in order to give the first STA time to finish determining the steering matrices from the set of UHR beamforming matrices V.

[0155] In an embodiment, the first frame may comprise a trigger frame. In an embodiment, the first precoding information may be comprised in a field of the trigger frame. In another embodiment, the first precoding information may be comprised in a common info field of the trigger frame. In another embodiment, the first precoding information may becomprised in a user info field of the trigger frame. In another embodiment, the first index may be comprised in a common info field of the trigger frame. In another embodiment, the first index may be comprised in a user info field of the trigger frame.

[0156] In additional or alternative embodiments, the first frame may comprise an action frame. In an embodiment, the first precoding information may be comprised in an ultra-high reliability (U H R) steering matrix field of the action frame. In another embodiment, the first index may be comprised in a UHR M I MO control field of the action frame.

[0157] In an embodiment, the first index associated with the first precoding information may comprise an indication of whether or not at least one frame transmitted using the first precoding information will be solicited by the second STA after the first STA transmits the second frame.

[0158] In an embodiment, the first frame further comprises a modulation and coding rate feedback (MFB) associated with the first precoding information. In an embodiment, the MFB may be used by the STA to transmit the second frame. In another embodiment, the MFB may comprise unequal modulation for at least two spatial streams of a PPDU carrying the second frame.

[0159] Step 1804 includes, in response to a third frame that may comprise the first index, transmitting, by the first STA to the second STA and using the first precoding information, a fourth frame. Step 1804 may include receiving, by the first STA from the second STA, the third frame that may comprise the first index. In an embodiment, the third frame may comprise a trigger frame and / or an action frame similar to the first frame describe above, that triggers a beamforming transmission by the first STA of the fourth frame based on the first precoding information. In an embodiment, the fourth frame may include a data frame, a management frame, and / or a control frame.

[0160] In embodiments, process 1800 may further comprise, transmitting, by the first STA to the second STA and in response to the first frame, the second frame using first precoding information. In embodiments, the first index associated with the first precoding information comprises an indication whether or not at least one frame transmitted using the first precoding information will be solicited by the second STA after the first STA transmits the second frame.

[0161] In embodiments, process 1800, may further comprise, before receiving the third frame, the first STA receives from the second STA, a fifth frame comprising second precoding information for use by the first STA to transmit a sixth frame to the second STA, and a second index associated with the second precoding information. In an embodiment, based on the first index being different from the second index, the first STA stores the first precoding information and the second precoding information for reuse by the first STA. In an additional or alternative embodiment, the first index comprises a first indication specifying that the first precoding information be stored for reuse by the first STA. In an additional or alternative embodiment, based on the first indication, the second precoding information is not stored for reuse by the first STA. In an additional or alternative embodiment, the second index comprises a second indication specifying that the second precoding information be stored for reuse by the first STA. In an additional or alternative embodiment, based on the second indication, the second precoding information replaces the first precoding information in storage of the first STA.

[0162] FIG. 19 illustrates an example process 1900 according to an embodiment. Example process 1900 is provided for the purpose of illustration only and is not limiting of embodiments. Example process 1900 may be performed by AP STAs such as AP 1502, AP 1602, and / or AP 1702, for example As shown in FIG. 19, process 1900 may include steps 1902 and 1904.

[0163] Step 1902 includes transmitting, by a second STA to a first STA, a first frame that may comprise first precoding information for use by the first STA to transmit a second frame to the second STA, and a first index associated with the first precoding information. In an embodiment, the first frame may comprise a trigger frame that triggers the transmitting of the second frame, wherein the second frame is transmitted using the first precoding information. In an embodiment, the second frame may include a data frame, a management frame, or a control frame. In an embodiment, the presence of the first index in the first frame may be used by the first STA as an indication from the second STA that precoding information may be reused in a subsequent beamformed transmission.

[0164] Step 1904 includes, based on a third frame and the first precoding information, receiving, by the second STA from the first STA, a fourth frame. Step 1904 may further include transmitting, by the second STA to the first STA, the third frame that includes the first index. In an embodiment, the third frame may comprise a trigger frame that triggers the transmitting of the fourth frame based on the first precoding information. In an embodiment, the fourth frame may include a data frame, a management frame, or a control frame.

[0165] In an embodiment, process 1900 may further comprise, receiving, by the second STA from the first STA, the second frame, wherein the second frame was transmitted using the first precoding information.

[0166] In an embodiment, process 1900 may further comprise, transmitting, by the second STA to the first STA, a fifth frame comprising, second precoding information for use by the first STA to transmit a sixth frame to the second STA, and a second index associated with the second precoding information. In an embodiment, process 1900 may further comprise, based on a fifth frame and the second precoding information, receiving, by the second STA from the first STA, the sixth frame. In an embodiment, the fifth frame may comprise a trigger frame that triggers the transmitting of the sixth frame based on the first precoding information. In an embodiment, the sixth frame may include a PPDU or other similar data frame.

[0167] In an embodiment, first precoding information may include information that facilitates uplink beamforming transmission by non-AP STAs, including, but not limited to, BFRs, sounding information, channel state information feedback, channel feedback, steering matrices, and / or other similar information. In an embodiment, the first precoding information may comprise a set of steering matrices for an ultra-high reliability (UHR) modulated field of a physical layer protocol data unit (PPDU) carrying the second frame. In an embodiment, the first precoding information may comprise a set of UHR beamforming matrix V used to determine a set of steering matrices for an ultra-high reliability (UHR) modulated field of a physical layer protocol data unit (PPDU) carrying the second frame. In an embodiment, the first precoding information may comprise a set of uplink channel state information used to determine a set of steering matrices for an ultra-high reliability (UHR) modulated field of a PPDU carrying the second frame. In an embodiment, padding may be added to the first frame in order to give the first STA time to finish determining the steering matrices from the uplinkchannel state information. In an embodiment, padding may be added to the first frame in order to give the first STA time to finish determining the steering matrices from the set of UHR beamforming matrices V.

[0168] In an embodiment, the first frame may comprise a trigger frame. In an embodiment, the first precoding information may be comprised in a field of the trigger frame. In another embodiment, the first precoding information may be comprised in a common info field of the trigger frame. In another embodiment, the first precoding information may be comprised in a user info field of the trigger frame. In another embodiment, the first index may be comprised in a common info field of the trigger frame. In another embodiment, the first index may be comprised in a user info field of the trigger frame.

[0169] In additional or alternative embodiments, the first frame may comprise an action frame. In an embodiment, the first precoding information may be comprised in an ultra-high reliability (UHR) steering matrix field of the action frame. In another embodiment, the first index may be comprised in a UHR M I MO control field of the action frame.

[0170] In an embodiment, the first index associated with the first precoding information may comprise an indication of whether or not at least one frame transmitted using the first precoding information will be solicited by the second STA after the first STA transmits the second frame.

[0171] In an embodiment, the first frame further comprises a modulation and coding rate feedback (MFB) associated with the first precoding information. In an embodiment, the MFB may be used by the first STA to transmit the second frame. In another embodiment, the MFB may comprise unequal modulation for at least two spatial streams of a PPDU carrying the second frame.

[0172] In an embodiment, process 1900 may further comprise transmitting, by the second STA from the first STA, a seventh frame comprising a third precoding information for use by the first STA to transmit the second frame to the second STA, and a second index associated with the third precoding information. In an embodiment, process 1900 may further comprise receiving, by the second STA from the first STA, the second frame, wherein the first index comprises the second index, and wherein the second frame is transmitted using the first precoding information.

Claims

CLAIMSWhat is claimed is:

1. A method comprising: receiving, by a first station (STA) from an access point (AP), a first trigger frame comprising: precoding information for use by the first STA to transmit a first frame to the AP; and an index value associated with the precoding information; in response to the first trigger frame, transmitting, by the first STA to the AP, the first frame using the precoding information; receiving, by the first STA from the AP, a second trigger frame comprising the index value; and in response to the second trigger frame, transmitting, by the first STA to a second STA and using the precoding information, a second frame.

2. A method comprising: receiving, by a first station (STA) from a second STA, a first frame comprising: first precoding information for use by the first STA to transmit a second frame to the second STA; and a first index associated with the first precoding information; and in response to a third frame comprising the first index, transmitting, by the first STA to the second STA and using the first precoding information, a fourth frame.

3. The method of claim 2, further comprising transmitting, by the first STA to the second STA and in response to the first frame, the second frame using first precoding information.

4. The method of any of claims 2 or 3, further comprising receiving, by the first STA from the second STA, the third frame comprising the first index.

5. The method of claim 2, wherein the first frame comprises a trigger frame, and wherein the first precoding information is provided in a common info field of the trigger frame.

6. The method of claim 2, wherein the first frame comprises a trigger frame, and wherein the first precoding information is provided in a user info field of the trigger frame.

7. The method of claim 2, wherein the first frame comprises a trigger frame, and wherein the first index is provided in a common info field of the trigger frame.

8. The method of claim 2, wherein the first frame comprises a trigger frame, wherein the first index is provided in a user info field of the trigger frame.

9. The method of claim 2, wherein the first frame comprises an action frame, wherein the first precoding information is provided in a UHR steering matrix field of the action frame.

10. The method of claim 2, wherein the first frame comprises an action frame, wherein the first index is provided in a UHR multiple input multiple output (Ml MO) Control field of the action frame.

11. The method of any of claims 2-10, further comprising:before receiving the third frame, receiving, by the first STA from the second STA, a fifth frame comprising: second precoding information for use by the first STA to transmit a sixth frame to the second STA; and a second index associated with the second precoding information.

12. The method of claim 11 , wherein, based on the first index being different from the second index, storing the first precoding information and the second precoding information for reuse by the first STA.

13. The method of claim 11 , wherein the first index comprises a first indication specifying that the first precoding information be stored for reuse by the first STA.

14. The method of claim 13, based on the first indication, the second precoding information is not stored for reuse by the first STA.

15. The method of claim 11 , wherein the second index comprises a second indication specifying that the second precoding information be stored for reuse by the first STA.

16. The method of claim 15, based on the second indication, the second precoding information replaces the first precoding information in storage of the first STA.

17. The method of claim 2, wherein the first precoding information comprises a set of steering matrices for an ultra- high reliability (UHR) modulated field of a physical layer protocol data unit (PPDU) carrying the second frame.

18. The method of claim 17, wherein the first precoding information comprises a set of UHR beamforming matrix V used to determine the set of steering matrices for the UHR modulated field of the PPDU carrying the second frame.

19. The method of claim 17, wherein the first precoding information comprises a set of uplink channel state information used to determine the set of steering matrices for the UHR modulated field of the PPDU carrying the second frame.

20. The method of claim 2-19, wherein the first frame further comprises a modulation and coding rate feedback (MFB) associated with the first precoding information.

21. The method of claim 20, wherein the MFB is used by the first STA to transmit the second frame.

22. The method of claim 20, wherein the MFB comprises unequal modulation for at least two spatial streams of a PPDU carrying the second frame.

23. The method of claim 2-20, wherein the second STA comprises an access point (AP) STA and the first STA comprises a non-AP STA.

24. A method comprising: transmitting, by an access point (AP) to a station (STA), a first trigger frame comprising: precoding information for use by the STA to transmit a first frame to the AP; and an index value associated with the precoding information; based on the precoding information and the index value, receiving, by the AP from the STA, the first frame; transmitting, by the AP to the STA, a second trigger frame comprising the index value; andbased on the precoding information and the index value, receiving, by the AP from the STA, a second frame.

25. A method comprising: transmitting, by an access point (AP) to a station (STA), a first frame comprising: first precoding information for use by the STA to transmit a second frame to the AP; and a first index associated with the first precoding information; and based on a third frame and the first precoding information, receiving, by the AP from the STA, a fourth frame.

26. The method of claim 25, further comprising, based on the first precoding information, receiving, by the AP from the STA, the second frame.

27. The method of any of claims 25 or 26, further comprising, transmitting, by the AP to the STA, the third frame comprising the first index.

28. The method of claims 25-27, wherein the first frame comprises a trigger frame, and wherein the first precoding information is comprised in a field of the trigger frame29. The method of claim 28, wherein the first precoding information is comprised in a common info field of the trigger frame.

30. The method of claim 28, wherein the first precoding information is comprised in a user info field of the trigger frame.

31. The method of claim 28, wherein the first index is comprised in a common info field of the trigger frame.

32. The method of claim 28, wherein the first index is comprised in a user info field of the trigger frame.

33. The method of claims 25-27, wherein the first frame comprises an action frame, and wherein the first precoding information is comprised in an ultra-high reliability (UHR) steering matrix field of the action frame.

34. The method of claim 25-27, wherein the first frame comprises an action frame, wherein the first index is comprised in a UHR multiple input multiple output (MIMO) Control field of the action frame.

35. The method of any of claims 25-34, further comprising: before the STA receives the third frame, transmitting, by the AP to the STA, a fifth frame comprising: second precoding information for use by the STA to transmit a sixth frame to the AP; and a second index associated with the second precoding information; and based on the fifth frame and the second precoding information, receiving, by the AP from the STA, the sixth frame.

36. The method of any of claims 25-35, wherein the first index associated with the first precoding information comprises an indication whether or not at least one frame transmitted using the first precoding information will be solicited by the AP after the STA transmits the second frame.

37. The method of claim 36, further comprising: transmitting, by the AP to the STA, a seventh frame comprising: a third precoding information for use by the STA to transmit the second frame to the AP; and a second index associated with the third precoding information.

38. The method of claim 37, further comprising receiving, by the AP from the STA, the second frame, wherein the first index comprises the second index, and wherein the second frame is transmitted using the first precoding information.

39. The method of any of claims 25-38, wherein the first precoding information comprises a set of steering matrices for an ultra-high reliability (UHR) modulated field of a physical layer protocol data unit (PPDU) carrying the second frame.

40. The method of any of claims 25-38, wherein the first precoding information comprises a set of UHR beamforming matrix V used to determine a set of steering matrices for an ultra-high reliability (UHR) modulated field of a physical layer protocol data unit (PPDU) carrying the second frame.

41. The method of any of claims 25-38, wherein the first precoding information comprises a set of uplink channel state information used to determine a set of steering matrices for an ultra-high reliability (UHR) modulated field of a physical layer protocol data unit (PPDU) carrying the second frame.

42. The method of claim 25-41 , wherein the first frame further comprises a modulation and coding rate feedback (MFB) associated with the first precoding information.

43. The method of claim 42, wherein the MFB is used by the STA to transmit the second frame.

44. The method of claim 42, wherein the MFB comprises unequal modulation for at least two spatial streams of a PPDU carrying the second frame.

45. A device comprising: one or more processors; and memory storing instructions that, when executed by the one or more processors, cause the device to perform a method according to any of claims 1-44.

46. A non-transitory computer-readable medium comprising instructions that, when executed by one or more processors, cause the one or more processors to perform a method according to any of claims 1-44.

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