Beamforming information persistence at a station

Abstract

An access point (AP) transmits, to a station (STA), a first trigger frame comprising precoding information for use by the STA to transmit a first frame to the AP. The AP receives, from the STA, the first frame. The AP transmits, to the STA, a second trigger frame, wherein based on the second trigger frame being transmitted within a duration of transmitting the first trigger frame, the second trigger frame indicates to the STA to use the precoding information to transmit a second frame to the AP.

Description

TITLEBeamforming Information Persistence at a StationCROSS-REFERENCE TO RELATED APPLICATIONS

[0001] This application claims the benefit of U.S. Provisional Application No. 63 / 632,848, filed April 11 , 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 uplink beamforming procedure, according to an embodiment.

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

[0022] FIG. 20 illustrates another example process according to an embodiment.DETAILED DESCRIPTION

[0023] 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.

[0024] 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.

[0025] 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.

[0026] 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 “em ploying / using at least”) is indicative that the phrase following the phrase “em ploying / 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.(0027] 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.

[0028] 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.

[0029] 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.

[0030] 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.(0031] 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.

[0032] 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.

[0033] 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).

[0034] 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.

[0035] 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).

[0036] 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.

[0037] 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 (DE), mobile station (MS), mobile subscriber unit, or user. For example, the term “user” may be 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.

[0038] 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.

[0039] A frequency band may include one or more sub-bands or frequency channels. For example, PPDUs conforming to the IEEE 802.11n, 802.11ac, 802.11ax 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.

[0040] 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.

[0041] 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.

[0042] 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-transitory 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.

[0043] 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.

[0044] 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.

[0045] 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 ps preamble of non-HT PPDU 310.

[0046] 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.

[0047] 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 ps, where 3.2 ps carry symbol information and 0.8 ps carry a Guard Interval (Gl).

[0048] 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.

[0049] 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 ps, which may increase depending on the number of spatial streams carried by the PPDU.

[0050] 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 ps or 4 ps. In both cases, 3.2 ps carry symbol information while the remaining 0.4 ps or 0.8 ps carry a Gl. The 0.4 ps long Gl is called short Gl while the 0.8 ps long Gl is called regular or normal Gl.

[0051] 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.

[0052] 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 ps, which may increase depending on the number of spatial streams carried by VHT PPDU 330.

[0053] 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 0.8 ps long is called regular or normal Gl.

[0054] 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 80MHz bands. In all cases, a subcarrier spacing of 312.5 kHz is maintained.

[0055] 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.

[0056] 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 pis.

[0057] 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.

[0058] 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.

[0059] 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.

[0060] 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 s. An AP or STA may use a suitable Gl duration depending on the channel conditions or capability of the target STA or AP.

[0061] 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.

[0062] 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 ER SU 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.

[0063] 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.

[0064] 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 may be similar to EHT MU PPDU 510 (e.g., may contain EHT / U HR modulated fields (EHT-STF and beyond) and non-EHT / UHR modulated fields (L-STF to EHT-SIG)).

[0065] 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 802.11 be 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.

[0066] 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.

[0067] The Gl portion of the EHT-LTF and Data fields of EHT MU PPDU 510 may be one of: 0.8 ps, 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.

[0068] The information portion of the EHT-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 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.

[0069] FIG.6 illustrates examples 600 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 may be used by a STA conforming to the IEEE802.11 ax standard 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.

[0070] UHR TB PPDU may be similar to HE / EHT TB PPDU (e.g. may contain HE / EHT / UHR modulated fields (HE- STF / EHT-STF and beyond) and non-HE / EHT / UHR modulated fields (L-STF to HE-SIG-A / U-SIG)).

[0071] 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.

[0072] 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 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.

[0073] 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.

[0074] 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.

[0075] 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.

[0076] 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.

[0077] 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.

[0078] 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).

[0079] 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 pis) or a subcarrier spacing of 156.25 kHz (information duration of 6.4 pis), instead of a subcarrier spacing of 78.125kHz (information duration of 12.8 s).

[0080] 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 may reduce 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.

[0081] FIG. 7 illustrates an example trigger frame 700. Trigger frame 700 may correspond to a basic trigger frame as defined in the existing IEEE 802.11 ax 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.

[0082] 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 Info List field, a Padding field, and an FCS field.

[0083] 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.

[0084] 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).

[0085] 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.

[0086] 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.

[0087] 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.

[0088] 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.

[0089] 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.

[0090] 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 802.11 be draft amendment (“IEEE P802.11be / D3.1, March 2023”).

[0091] 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.

[0092] 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.

[0093] 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.

[0094] 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.

[0095] 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.

[0096] 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.

[0097] 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 1051-8.

[0098] 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.

[0099] 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 may duplicate four times over frequency each of the 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.

[0100] 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).

[0101] 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.

[0102] As shown in FIG. 10, the total access latency of a STA 1052 is equal to the combined duration of an HE MU PPDU (e.g., 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.

[0103] 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.

[0104] 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.

[0105] 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.

[0106] 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.

[0107] 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.

[0108] 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 may be associated with AP 1202.

[0109] An uplink beamforming procedure may be performed in a similar manner as the sounding phase / procedure of 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 transmits BFR frames to non-AP STAs 1204, 1206, and 1208 in a feedback frame.

[0110] As shown in FIG. 12, the uplink beamforming procedure of example 1200 may begin with AP 1202 transmitting a beamforming sounding NDP poll (BSNP) trigger frame 1205 that requests a sounding NDP from each of STAs 1204, 1206, and 1208. After receiving BNSP trigger frame 1205, STAs 1204, 1206, and 1208 respectively transmit sounding NDPs 1260A-C to AP 1202. Based on NDPs 1260A-C, AP 1202 estimates respective uplink channel state information for each of uplink channels from STAs 1204, 1206, and 1208 to AP 1202. AP 1202 may generate a respective compressed matrix V from the respective uplink channel state information for each of the uplink channels from STAs1204, 1206, and 1208 to AP 1202. Based on the respective compressed matrices V, AP 1202 generates respective Beamforming Reports (BFRs) 1230A-C for STAs 1204, 1206, and 1208.

[0111] To request data frames 1250A-C from respectively STAs 1204, 1206, and 1206, AP 1202 transmits a trigger frame 1210 to STAs 1204, 1206, and 1208. AP 1202 may also transmit BFRs 1230A-C in a feedback frame 1220 to STAs 1204, 1206, and 1208. 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. 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.

[0112] On receiving feedback frame 1220, STAs 1204, 1206, and 1208 may use respectively BFRs 1230A-C to generate respective steering matrices for beamforming transmission of data frames 1250A-C respectively. In an example, STAs 1204, 1206, and 1208 may perform decompression of the respective compressed matrices V contained respectively in BFRs 1230A-C. Then, STAs 1204, 1206, and 1208 may each generate a respective steering matrix based on a respective uncompressed matrix. In an alternative approach, AP 1202 may send channel state information to STAs 1204, 1206, and 1208 instead of sending respective compressed matrices V generated from the channel state information. In this example, STAs 1204, 1206, and 1208 may generate respective steering matrices from the channel state information without a decompression procedure. In an example, to facilitate the generation of the steering matrices by STAs 1204, 1206, and 1208, AP 1202 may add padding (e.g., using the Padding field described with FIG. 7 in trigger frame 700) to allow the generation of the steering matrices to be completed.

[0113] Based on trigger frame 1210, STAs 1204, 1206, and 1208 transmit respectively data frames 1250A-C, based on the respectively generated steering matrices. In response, AP 1202 transmits a BA frame 1240 to STAs 1204, 1206, and 1208.

[0114] 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 may be associated with AP 1302.

[0115] As shown in FIG. 13, the uplink beamforming procedure of example 1300 may begin with AP 1302 transmitting a beamforming sounding NDP poll (BSNP) trigger frame 1305 that requests a sounding NDP from each of STAs 1304, 1306, and 1308. After receiving BNSP trigger frame 1305, STAs 1304, 1306, and 1308 respectively transmit sounding NDPs 1360A-C to AP 1302. Based on NDPs 1360A-C, AP 1302 estimates respective uplink channel state information for each of uplink channels from STAs 1304, 1306, and 1308 to AP 1302.

[0116] Instead of generating respective compressed matrix V for each of the uplink channels from STAs 1304, 1306, and 1308 to AP 1302, as in FIG. 13, in example 1300, AP 1302 may directly generate respective beam steering matrices for STAs 1304, 1306, and 1308, based on the uplink channel state information received from STAs 1304, 1306, and 1308. Directly generating the steering matrices to be used by STAs 1304, 1306, and 1308 by the AP may result in a reduction of computation burden by STAs 1304, 1306 and 1308. As illustrated in example 1300, AP 1302 may not add padding to trigger frame 1310, in contrast to example 1200 where padding was added to trigger frame 1210. Based onthe steering matrices, AP 1302 generates respective 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. For example, the steering matrices may be compressed using Givens rotation in order to reduce the number of bits of the respective BFRs.

[0117] To request data frames 1350A-C from STAs 1304, 1306, and 1306 respectively, AP 1302 transmits a trigger frame 1310 to STAs 1304, 1306, and 1308. AP 1302, with BFRs 1330A-C included in a feedback frame 1320. In an example, feedback frame 1320 may be characterized as an ULBF CBF. Trigger frame 1310 and feedback frame 1320 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. 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.

[0118] Based on trigger frame 1310, STAs 1304, 1306, and 1308 transmit respectively data frames 1350A-C, based on BFRs 1330A-C. In response, AP 1302 transmits a BA frame 1340 to STAs 1304, 1306, and 1308.

[0119] 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 STA 1404. STA 1404 may be associated with AP 1402.

[0120] The uplink beamforming procedure of example 1400 may begin with AP 1402 transmitting a frame 1470 to STA 1404. Frame 1470 may include a trigger frame that schedules and allocates resources to receive uplink data from STA 1404. Frame 1470 may further include precoding information 1490 for STA 1404. STA 1404 may use precoding information 1490 to perform a beamformed transmission of a data frame 1480 to AP 1402. As used herein, precoding information (e.g., precoding information 1490) 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.

[0121] After being received from AP 1402, precoding information 1490 may be stored in a memory of STA 1404 for reuse in a subsequent beamformed transmission to AP 1402. Notwithstanding this storage, after precoding information 1490 is stored in the memory of STA 1404, STA 1404 may discard precoding information 1490 at a time 1468. This operation by STA 1404 may occur for a variety of reasons, including, but not limited to, information storage rules for the memory, the receipt of other information to store, and / or other similar conditions.

[0122] Continuing example 1400, AP 1402 may transmit a frame 1471 to STA 1404. Frame 1471 may include a trigger frame that schedules and allocates resources to receive uplink data from STA 1404. In an example, as frame 1471 allocates resources to receive uplink data from STA 1404 via the same uplink channel used to receive data frame 1480, AP 1402 may determine that STA 1404 may reuse precoding information 1490 (previously sent in frame 1470 and use to perform the beamformed transmission of data frame 1480 to AP 1402) to transmit the uplink data to AP 1402 in a beamformed transmission. As such, AP 1402 may not retransmit precoding information 1490 in frame 1471. Additionally,to indicate to STA 1404 that precoding information 1490 is specified to be reused for the beamformed transmission, AP 1402 may include a reuse indication 1495 in frame 1471.

[0123] In an example, as described above, because STA 1404 may have discarded from memory, at time 1468, precoding information 1490, STA 1404 may not be able to reuse precoding information 1490 as specified by reuse indication 1495 of frame 1471 for the beamformed transmission to AP 1402. In an example, STA 1404 may use different precoding information than precoding information 1490 for the beamformed transmission or may not use beamforming to transmit the uplink data to AP 1402. This, however, may result in a suboptimal transmission or a transmission failure of the uplink data to AP 1402. This suboptimal transmission or transmission failure may lead to an inefficient and wasteful use of network resources, including wireless channel resources required to retransmit a frame that requests the data, and precoding information 1490, which was erroneously discarded.

[0124] In another example, instead of discarding precoding information 1490 at time 1468, STA 1404 may retain precoding information 1490 in memory after a time that AP 1402 does not require the use of precoding information 1490. This use of the memory of STA 1404 to store information that is not needed may lead to an inefficient and wasteful use of the memory resources of STA 1404, including inefficiencies based on a potential failure to store other, more useful information to facilitate network communications.

[0125] In embodiments that address the above-described problem, a STA may receive from an AP, a first frame comprising precoding information for use by the STA to transmit a second frame to the AP. Based on a third frame being received from the AP within a duration of the receiving of the first frame, the STA may use the precoding information to transmit a fourth frame to the AP. Stated differently, when the second trigger frame is transmitted by the AP to the STA within the duration, the transmission of the second trigger frame indicates to the STA to not discard the precoding information.

[0126] In this aspect, when the second trigger frame is received by the STA during the duration, the STA may use the precoding information, which has not been discarded by the STA, to perform a beamforming transmission of the second frame to the AP. In additional or alternative embodiments, instead of a duration between trigger frames being used as an indication to the STA, the STA may operate based on an indication to retain the precoding information until an indication to discard the precoding information is received from the AP. In an example, where the second trigger frame is received by the STA before an indication to discard the precoding information is received by the STA, the STA may use precoding information, which has not been discarded by the STA, to perform the beamforming transmission of the second frame to the AP.

[0127] Thus, in accordance with one or more embodiments, the STA may avoid unnecessarily wasting network and memory resources, by retaining (e.g., not discarding) the precoding information for use in transmitting the second frame to the AP.

[0128] 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 STA 1504. STA 1504 may be associated with AP 1502.

[0129] As shown in FIG. 15, the uplink beamforming procedure may begin with AP 1502 transmitting a frame 1570 to STA 1504. Frame 1570 may correspond to a trigger frame that schedules and allocates resources of STA 1504 to transmit beamformed uplink data (e.g., a frame 1580) to AP 1502. In different implementations, frames 1570 and 1580 may broadly correspond to 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).

[0130] Frame 1570 comprises precoding information 1590 for use by STA 1504 to perform a beamforming transmission of frame 1580 to AP 1502. Frame 1570 may further comprise an indication of a duration 1595 transmitted to STA 1504 with frame 1570. As described below, duration 1595 may provide a length of time that STA 1504 is specified by AP 1502 to store precoding information 1590 for reuse by STA 1504 with the beamformed uplink channel to AP 1502.

[0131] With frame 1570 being a trigger frame, precoding information 1590 may be included in different ways within frame 1570, 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 such as is discussed herein. In additional or alternative embodiments, frame 1570 may be implemented in an action frame. With frame 1570 being an action frame, precoding information 1590 may be included in a UHR steering matrix field of frame 1570.

[0132] In an embodiment, precoding information 1590 may include steering matrices (e.g., per tone or per group of tones) that STA 1504 may apply to transmit frame 1580. Directly providing steering matrices to STA 1504 may reduce the computational burden of STA 1504 for transmitting frame 1580, and may allow AP 1502 to not add padding to the trigger frame so as to provide enough time for STA 1504 to generate the steering matrices. This approach is similar to the approach described above with FIG. 13, where, instead of generating respective compressed matrix V for each of the uplink channels from STAs 1304, 1306, and 1308, AP 1302 directly generated respective beam steering matrices for STAs 1304, 1306, and 1308, thereby avoiding the need for the addition of padding by AP 1302.

[0133] In an alternative or additional embodiment, precoding information 1590 may include a beamforming matrix V (e.g., per tone or group of tones) for a multiple input, multiple output (MIMO) channel between AP 1502 and STA 1504. The beamforming matrix V may be used by STA 1504 to generate steering matrices (e.g., per tone or group of tones) to apply for transmitting frame 1580 to AP 1502. To facilitate the generation of the steering matrices by STA 1504, AP 1502 may add padding (e.g., using the Padding field described in trigger frame 700. This approach is similar to the approach described above with FIG. 12, where STAs 1204, 1206, and 1208 generated respective steering matrices from channel state information provided by AP 1202. In example 1200, to facilitate the generation of the steering matrices by STAs 1204, 1206, and 1208, AP 1202 adds padding to allow the generation of the steering matrices to be completed.

[0134] Frame 1570 may further comprise duration 1595, that may provide a length of time that STA 1504 is specified by AP 1502 to store precoding information 1590 for reuse by STA 1504. In embodiments, duration 1595 may be an indication from AP 1502 of a minimum time to retain precoding information in the memory of STA 1504. Alternatively, duration 1595 may be characterized as an indication from AP 1502 of a time for STA 1504 to wait before discardingpreceding information 1590, e.g., at a time 1565. In different implementations not depicted, duration 1595 may be conveyed to STA 1504 by being transmitted in a management frame received by STA 1504 before the receipt of frame 1570 by STA 1504. The management frame used to convey duration 1595 may be an action frame and / or a beacon frame.

[0135] Continuing example 1500, after receiving frame 1570 from AP 1502, STA 1504 may use precoding information 1590 to perform a beamforming transmission of frame 1580 to AP 1502 via the beamformed uplink channel to AP 1502. After transmitting frame 1580 to AP 1502, STA 1504 may store precoding information 1590 in a memory of STA 1504, e.g., to have precoding information 1590 available for reuse by STA 1504 fora subsequent beamformed transmission to AP 1502.

[0136] Duration interval 1550 depicts a time interval for STA 1504 to track the length of time that STA 1504 is specified by duration 1595 to store precoding information 1590. Duration interval 1550 may commence upon receipt of frame 1570. In an embodiment, STA 1504 may be configured to discard precoding information 1590 at expiration of duration interval 1550. In another embodiment, the expiration of duration interval 1550 may not mandate the discarding of precoding information 1590; rather, after the expiration of duration interval 1550, the determination of whether to discard precoding information 1590 may again be based on memory management factors evaluated by STA 1504.

[0137] Precoding information 1590 may further include a first indication 1596 which corresponds to an indication by AP 1502 to STA 1504 to reuse precoding information 1590 (stored within the memory of STA 1504) in transmitting uplink data in response to subsequently received frames.

[0138] Continuing example 1500, AP 1502 may transmit a frame 1571 to STA 1504. Frame 1571 may comprise a trigger frame that schedules and allocates resources of STA 1504 to transmit beamformed uplink data (e.g., frame 1581) toAP 1502. In an example, because AP 1502 included duration 1595 within frame 1570, and frame 1571 is transmitted to STA 1504 within duration interval 1550 (e.g., determined based on duration 1595), AP 1502 does not resend precoding information 1590 with frame 1571 , e.g., because conditions that might cause precoding information 1590 to be discarded from the memory of STA 1504 have not occurred. Additionally or alternatively, because AP 1502 included first indication 1596 within precoding information 1590, and first indication 1596 corresponds to an indication by AP 1502 to STA 1504 to reuse precoding information 1590, AP 1502 does not resend precoding information 1590 with frame 1571.

[0139] Because frame 1571 is received by STA 1504 within duration interval 1550 (e.g., specified by duration 1595), STA 1504 does not discard precoding information 1590 before receiving frame 1571, including first indication 1596 to reuse precoding information 1590. This contrasts with example 1400 discussed with FIG. 14 above, where precoding information 1490 was discarded from storage in the memory of STA 1404, thereby being unavailable for reuse by STA 1404 to transmit frame 1480 to AP 1402. Thus, at least based on the foregoing, embodiments depicted with FIG. 15 may avoid the problem described above with FIG. 14.

[0140] Based on one or more of, the storage of precoding information 1590 in the memory of STA 1504, frame 1571 being received during the pendency of duration interval 1550, and first indication 1596 from AP 1502 to reuse precodinginformation 1590, STA 1504 may use preceding information 1590 to perform a beamformed transmission of frame 1581 to AP 1502.

[0141] FIG. 16 illustrates an example 1600 of an uplink beamforming procedure according to an embodiment. As shown in FIG. 16, example 1600 includes AP 1602 and STA 1604. STA 1604 may be associated with AP 1602.

[0142] As shown in FIG. 16, the uplink beamforming procedure may begin with AP 1602 transmitting a frame 1670 to STA 1604. Frame 1670 may correspond to a trigger frame that schedules and allocates resources of STA 1604 to transmit beamformed uplink data (e.g., frame 1680) to AP 1602. In different implementations, frames 1670 and 1680 may broadly correspond to 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).

[0143] Frame 1670 comprises first precoding information 1690A that may be used by STA 1604 to transmit a frame 1680 to AP 1602. With frame 1670 being a trigger frame, first precoding information 1690A may be included in different ways within frame 1670, 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 such as is discussed herein. In additional or alternative embodiments, frame 1670 may be implemented in an action frame. With frame 1670 being an action frame, first precoding information 1690A may be included in a UHR steering matrix field of frame 1670.

[0144]

[0145] In an embodiment, precoding information 1790 may include steering matrices (e.g., per tone or per group of tones) that STA 1604 may apply to transmit frame 1580. Directly providing steering matrices to STA 1604 may reduce the computational burden of STA 1604 for transmitting frame 1680, and may allow AP 1602 to not add padding to the trigger frame so as to provide enough time for STA 1604 to generate the steering matrices. This approach is similar to the approach described above with FIG. 13, where, instead of generating respective compressed matrix V for each of the uplink channels from STAs 1304, 1306, and 1308, AP 1302 directly generated respective beam steering matrices for STAs 1304, 1306, and 1308, thereby avoiding the need for the addition of padding by AP 1302.

[0146] In an alternative or additional embodiment, first precoding information 1690A may include a beamforming matrix V (e.g., per tone or group of tones) fora multiple input, multiple output (MIMO) channel between AP 1602 and STA 1604. The beamforming matrix V may be used by STA 1504 to generate steering matrices (e.g., per tone or group of tones) to apply for transmitting frame 1680 to AP 1602. To facilitate the generation of the steering matrices by STA 1604, AP 1602 may add padding (e.g., using the Padding field described in trigger frame 700. This approach is similar to the approach described above with FIG. 12, where STAs 1204, 1206, and 1208 generated respective steering matrices from channel state information provided by AP 1202. In example 1200, to facilitate the generation of the steering matrices by STAs 1204, 1206, and 1208, AP 1202 adds padding to allow the generation of the steering matrices to be completed.

[0147] Precoding information 1690A may include a second indication 1696, which corresponds to an indication by AP 1602 to STA 1604 of whether at least one frame transmitted by STA 1604 using first precoding information 1690A will besolicited by the AP after the STA transmits frame 1670. In an embodiment, second indication 1696 may be provided in a user info field of frame 1670.

[0148] Continuing example 1600, after receiving frame 1670 from AP 1602, STA 1604 may use first precoding information 1690A to perform a beamforming transmission of frame 1680 to AP 1602 via the beamformed uplink channel to AP 1602. In example 1600, precoding information 1690A includes second indication 1696 that indicates that at least one frame transmitted by STA 1604 using first precoding information 1690A will not be solicited by AP 1602 after the STA 1604 transmits frame 1670. Depending upon the configuration of STA 1604, second indication 1696 may indicate that precoding information 1690A will not be reused in transmitting uplink data in response to subsequently received frames.

[0149] Continuing example 1600, AP 1602 may transmit a frame 1671 to STA 1604. Frame 1671 may comprise a trigger frame that schedules and allocates resources of STA 1604 to transmit beamformed uplink data (e.g., frame 1681) to AP 1602. In an example, because AP 1602 included within frame 1670, second indication 1696 that indicates that first precoding information 1690A will not be solicited by AP 1602, AP 1602 sends second precoding information 1690B with frame 1671, e.g., because, as indicated by second indication 1696, precoding information different from precoding information 1690A will be used by STA 1604 to transmit frame 1681.

[0150] Frame 1670 may further include a second indication 1696 associated with first precoding information 1690A. In embodiments, second indication 1696 may be included with precoding information as an indication whether the precoding information is requested to be stored at the STA for reuse transmitting additional frames. After being received from AP 1602, 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.

[0151] In example 1600, second indication 1696 specifies that first precoding information 1690A is not requested to be stored for reuse, e.g., that first precoding information 1690A will not be solicited by AP 1602 after STA 1604 transmits frame 1680. This indication that first precoding information 1690A is not requested to be stored for reuse does not mandate the discarding of precoding information 1690A, the determination of whether to discard precoding information 1690A may again be based on memory management factors evaluated by STA 1604. Further, a duration value (e.g., similar to duration interval 1550) may have been conveyed to STA 1604 (not shown), but because of second indication 1696 that first precoding information 1690A is not requested to be stored for reuse, STA 1604 may or may not discard first precoding information 1690A during a duration interval 1650.

[0152] In an example, because AP 1602 included second indication 1696 that first precoding information 1690A is not requested to be stored for reuse, AP 1602 sends second precoding information 1690B for the transmission of frame 1681. After receiving frame 1671 from AP 1602, STA 1604 may use second precoding information 1690B to transmit frame 1681 to AP 1602 via the beamformed uplink channel to AP 1602.

[0153] FIG. 17 illustrates an example 1700 of an uplink beamforming procedure according to an embodiment. As shown in FIG. 17, example 1700 includes AP 1702 and STA 1704. STA 1704 may be associated with AP 1702.

[0154] As shown in FIG. 17, the uplink beamforming procedure may begin with AP 1702 transmitting a frame 1770 to STA 1704. Frame 1770 may correspond to a trigger frame that schedules and allocates resources of STA 1704 to transmitbeamformed uplink data (e.g., frame 1780) to AP 1702. In different implementations, frames 1770 and 1780 may broadly correspond to 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).

[0155] Frame 1770 comprises precoding information 1790 that may be used by STA 1704 to perform a beamforming transmission of a frame 1780 to AP 1702. With frame 1770 being a trigger frame, precoding information 1790 may be included in different ways within frame 1770, 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 such as is discussed herein. In additional or alternative embodiments, frame 1770 may be implemented in an action frame. With frame 1770 being an action frame, precoding information 1790 may be included in a UHR steering matrix field of frame 1770.

[0156] In an embodiment, precoding information 1790 may include steering matrices (e.g., per tone or per group of tones) that STA 1704 may apply to transmit frame 1780. Directly providing steering matrices to STA 1704 may reduce the computational burden of STA 1704 for transmitting frame 1780, and may allow AP 1702 to not add padding to the trigger frame so as to provide enough time for STA 1704 to generate the steering matrices. This approach is similar to the approach described above with FIG. 13, where, instead of generating respective compressed matrix V for each of the uplink channels from STAs 1304, 1306, and 1308, AP 1302 directly generated respective beam steering matrices for STAs 1304, 1306, and 1308, thereby avoiding the need for the addition of padding byAP 1302.

[0157] In an alternative or additional embodiment, precoding information 1790 may include a beamforming matrix V (e.g., per tone or group of tones) for a multiple input, multiple output (Ml MO) channel between AP 1702 and STA 1704. The beamforming matrix V may be used by STA 1704 to generate steering matrices (e.g., per tone or group of tones) to apply for transmitting frame 1780 to AP 1702. To facilitate the generation of the steering matrices by STA 1704, AP 1702 may add padding (e.g., using the Padding field described in trigger frame 700. This approach is similar to the approach described above with FIG. 12, where STAs 1204, 1206, and 1208 generated respective steering matrices from channel state information provided by AP 1202. In example 1200, to facilitate the generation of the steering matrices by STAs 1204, 1206, and 1208, AP 1202 adds padding to allow the generation of the steering matrices to be completed.

[0158] Frame 1770 may further comprise duration 1795, that may provide a length of time that STA 1704 is specified by AP 1702 to store precoding information 1790 for reuse by STA 1704. In embodiments, duration 1795 may be an indication from AP 1702 of a minimum time to retain precoding information in the memory of STA 1704. Alternatively, duration 1795 may be characterized as an indication from AP 1702 of a time for STA 1704 to wait before discarding precoding information 1790, e.g., at a time 1765. In different implementations not depicted, duration 1795 may be conveyed to STA 1704 by being transmitted in a management frame received by STA 1704 before the receipt of frame 1770 by STA 1704.

[0159] Continuing example 1700, after receiving frame 1770 from AP 1702, STA 1704 may use precoding information 1790 to perform a beamforming transmission of frame 1780 to AP 1702. After transmitting frame 1780 to AP 1702, STA1704 may store precoding information 1790 in a memory of STA 1704, for reuse for a subsequent beamformed transmission to AP 1702.

[0160] Duration interval 1750 depicts a time interval for STA 1704 to track the length of time that STA 1704 is specified by duration 1795 to store precoding information 1790. Duration interval 1750 may commence upon receipt of frame 1770. In an embodiment, STA 1704 may be configured to discard precoding information 1790 at expiration of duration interval 1750. In another embodiment, the expiration of duration interval 1750 may not mandate the discarding of precoding information 1790; rather, after the expiration of duration interval 1750, the determination of whether to discard precoding information 1790 may again be based on memory management factors evaluated by STA 1704.

[0161] In this example, frame 1780 from STA 1704 includes a third indication 1797. Third indication 1797 may provide information from STA 1704 to AP 1702 regarding different determinations made by STA 1704 with respect to precoding information 1790, and precoding information generally. For example, third indication 1797 may specify to AP 1702 that precoding information 1790 will be discarded after precoding information 1790 is used transmitting frame 1780 to AP 1702, and thus may need to be resent by AP 1702 if required for subsequent frames. In this example,

[0162] Continuing example 1700, AP 1702 may transmit a frame 1771 to STA 1704. Frame 1771 may include a trigger frame that schedules and allocates resources of STA 1704 to transmit beamformed uplink data (e.g., frame 1781) to AP 1702. In an example, because STA 1704 conveyed third indication 1797 that precoding information 1790 will be discarded after use transmitting frame 1780, AP 1702 sends precoding information for the transmission of frame 1781. In this example, AP 1702 resends precoding information 1790 in frame 1771, for the beamformed transmission of frame 1781.

[0163] Alternative or additional information that may be conveyed using third indication 1797 include information corresponding to a duration interval 1750 that STA 1704 will wait before discarding precoding information 1790 In this example, although frame 1770 includes duration 1795, by specifying a different duration interval 1750 with third indication 1797, STA 1704 notifies AP 1702 that duration 1795 from AP 1702 may not control the time of storage of precoding information 1790. This contrasts with the example of FIG. 17 above, where duration 1795 from AP 1702 was used to by STA 1704 to set duration interval 1750. In this alternative example, because STA 1704 conveyed third indication 1797 that precoding information 1790 will be retained during duration interval 1750, and because frame 1771 was transmitted to STA 1704 during duration interval 1750, AP 1702 did not resend the previously sent precoding information 1790 (not shown).

[0164] Alternative or additional information that may be conveyed using third indication 1797 further include a request from STA 1704 for different precoding data, e.g., to improve the transmission using the beamformed uplink channel to AP 1702.

[0165] FIG. 18 illustrates an example 1800 of an uplink beamforming procedure according to an embodiment. As shown in FIG. 18, example 1800 includes AP 1802 and STA 1804. STA 1804 may be associated with AP 1802.

[0166] As shown in FIG. 18, the uplink beamforming procedure may begin with AP 1802 transmitting a frame 1870 to STA 1804. Frame 1870 may correspond to a trigger frame that schedules and allocates resources of STA 1804 to transmitbeamformed uplink data (e.g., a frame 1880) to AP 1802. In different implementations, frames 1870 and 1880 may broadly correspond to 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)

[0167] Frame 1870 comprises precoding information 1890 for use by STA 1804 to perform a beamforming transmission of frame 1880 to AP 1802. Frame 1870 may further comprise an indication of a duration 1896 transmitted to STA 1804 with frame 1870. As described below, duration 1896 may provide a length of time that STA 1804 is specified by AP 1802 to store precoding information 1890 for reuse by STA 1804 with the beamformed uplink channel to AP 1802.

[0168] With frame 1870 being a trigger frame, precoding information 1890 may be included in different ways within frame 1870, 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 maybe 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 such as is discussed herein. In additional or alternative embodiments, frame 1870 may be implemented in an action frame. With frame 1870 being an action frame, precoding information 1890 may be included in a UHR steering matrix field of frame 1870.

[0169] In an embodiment, precoding information 1890 may include steering matrices (e.g., per tone or per group of tones) that STA 1804 may apply to transmit frame 1880. Directly providing steering matrices to STA 1804 may reduce the computational burden of STA 1804 for transmitting frame 1880, and may allow AP 1802 to not add padding to the trigger frame so as to provide enough time for STA 1804 to generate the steering matrices. This approach is similar to the approach described above with FIG. 13, where, instead of generating respective compressed matrix V for each of the uplink channels from STAs 1304, 1306, and 1308, AP 1302 directly generated respective beam steering matrices for STAs 1304, 1306, and 1308, thereby avoiding the need for the addition of padding byAP 1302.

[0170] In an alternative or additional embodiment, precoding information 1890 may include a beamforming matrix V (e.g., per tone or group of tones) for a multiple input, multiple output (Ml MO) channel between AP 1802 and STA 1804. The beamforming matrix V may be used by STA 1804 to generate steering matrices (e.g., per tone or group of tones) to apply for transmitting frame 1880 to AP 1802. To facilitate the generation of the steering matrices by STA 1804, AP 1802 may add padding (e.g., using the Padding field described in trigger frame 700. This approach is similar to the approach described above with FIG. 12, where STAs 1204, 1206, and 1208 generated respective steering matrices from channel state information provided by AP 1202. In example 1200, to facilitate the generation of the steering matrices by STAs 1204, 1206, and 1208, AP 1202 adds padding to allow the generation of the steering matrices to be completed.

[0171] Frame 1870 may further comprise duration 1896, that may provide a length of time that STA 1804 is specified by AP 1802 to store precoding information 1890 for reuse by STA 1804. In embodiments, duration 1896may be an indication from AP 1802 of a minimum time to retain precoding information in the memory of STA 1804. Alternatively, duration 1896 may be characterized as an indication from AP 1802 of a time for STA 1804 to wait before discarding precoding information 1890, e.g., at a time 1865. In different implementations not depicted, duration 1896 may be conveyed to STA 1804 by being transmitted in a management frame received by STA 1804 before the receipt of frame1870 by STA 1804. The management frame used to convey duration 1896 may be an action frame and / or a beacon frame.

[0172] Continuing example 1800, after being received from AP 1802, STA 1804 may use precoding information 1890 to perform a beamforming transmission of frame 1880 to AP 1802 via the beamformed uplink channel to AP 1802. After transmitting frame 1880 to AP 1802, STA 1804 may store precoding information 1890 in a memory of STA 1804, e.g., to have precoding information 1890 available for reuse by STA 1804 for a subsequent beamformed transmission to AP 1802. Duration 1896 may provide a length of time that STA 1804 is specified to by AP 1802 to store precoding information 1890 for reuse. Depicted in FIG. 18, first duration interval 1850 maybe determined and applied by STA 1804 to implement the limits of duration 1896, as requested by AP 1802. As noted with the description of some embodiments herein, the expiration of first duration interval 1850 does not mandate an immediate discarding of precoding information 1890. For example, ata time 1865, STA 1804 may discard precoding information 1890 ata time after the expiration of first duration interval 1850.

[0173] After discarding precoding information 1890, STA 1804 may transmit frame 1881 that includes request 1895. In an embodiment, request 1895 requests AP 1802 to initiate a sounding procedure. In another example, after STA 1804 discards precoding information 1890 (e.g., at time 1865), STA 1804 may determine that precoding information is to be used to transmit an additional frame. Request 1895 may request a resending of precoding information 1890 to STA 1804. In additional implementations, frame 1881 and request 1895 may be transmitted by STA 1804 at a selected time independent of the discarding of precoding information 1890. Also, in some implementations, frame 1881 may be transmitted using a TXOP obtained by STA 1804 (e.g., not in response to a trigger frame such as frame 1870). In such implementations, frame 1881 may be a management frame (e.g., action frame), a data frame, a null frame or a control frame.

[0174] In another example, the request by STA 1804 to initiate a sounding procedure may be implicitly conveyed to AP 1802 based on different events. As depicted in FIG. 18, a second duration 1852 is shown beginning at the end of transmission of frame 1880. In an implementation, second duration 1852 represents a time period within which, if certain events occur with respect to STA 1804, AP 1802 will respond as if explicit request 1895 had been transmitted. In this example, frame 1881 may be transmitted to AP 1802 without request 1895, but within second duration 1852, and thus, AP 1802, having received frame 1881 within second duration 1852, initiates a sounding procedure, and / or performs other operations discussed above with respect to request 1895.

[0175] 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 a first STA, such as non-AP STAs STA 1504, STA 1604, STA 1704, and STA 1804, for example. As shown in FIG. 19, process 1900 may include steps 1902 and 1904.

[0176] Step 1902 includes receiving, by a STA from an access point AP, a first frame comprising precoding information (steering matrices) for use by the STA to transmit a second frame to the AP. In an embodiment, the first frame maycomprise a trigger frame that triggers the transmitting of the second frame based on the precoding information. In an embodiment, the second frame may include a data frame, a management frame, or a control frame.

[0177] In an embodiment, 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 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 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 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.

[0178] In an embodiment, the first frame may comprise a trigger frame. In an embodiment, the precoding information may be comprised in a field of the trigger frame. In another embodiment, the precoding information may be comprised in a common info field of the trigger frame. In another embodiment, the 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 an embodiment, the second indication is provided in a user info field of the first trigger frame.

[0179] In additional or alternative embodiments, the first frame may comprise an action frame. In an embodiment, the 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.

[0180] In an embodiment, the first frame may further indicate whether or not at least one frame transmitted using the precoding information will be solicited by the AP after the STA transmits the second frame. In an embodiment, the first frame may include a second indication that at least one frame transmitted using the precoding information will be solicited by the AP after the STA transmits the second frame.

[0181] Step 1904 includes, based on a third frame being received from the AP within a first duration of the receiving of the first frame, transmitting, by the STA to the AP, a fourth frame using the precoding information. In an embodiment, the third frame may comprise a trigger frame that triggers the transmitting of the fourth frame based on the precoding information. In an embodiment, the fourth frame may include a data frame, a management frame, ora control frame.

[0182] In embodiments, process 1900 may further comprise, before the first frame is transmitted by the AP, transmitting, by the AP to the STA, a fifth frame including the first duration. In an embodiment, the first duration may correspond to a predetermined duration. In an implementation, the predetermined duration may be set to 100 ms. In an embodiment, the fifth frame may correspond to a management frame, including a beacon frame and / or an action frame.In embodiments, process 1900 may further comprise, transmitting, by the STA to the AP, the fourth frame in response to the third frame.

[0183] In embodiments, process 1900 may further comprise, transmitting, by the STA to the AP, the second frame in response to the first frame, with the second frame being transmitted using the precoding information. In an embodiment, the second frame may indicate to the AP whether or not the precoding information is available at the STA after the second frame is transmitted. In an embodiment, the second frame may include a third indication whether or not the precoding information is available at the STA after transmitting the second frame. In an embodiment, the third frame may further indicate that the STA use the precoding information to transmit a fourth frame to the AP. In an embodiment, the third frame may correspond to a second trigger frame, and the third frame may indicate to the STA to use the precoding information further based on the second indication.

[0184] In embodiments, process 1900 may further comprise, when the STA receives the third frame after the first duration of the receiving of the first frame, discarding, by the STA, the precoding information. In embodiments, process 1900 may further comprise, when the STA does not receive the third frame, discarding, by the STA, the precoding information.

[0185] FIG. 20 illustrates an example process 2000 according to an embodiment. Example process 2000 is provided for the purpose of illustration only and is not limiting of embodiments. Example process 2000 may be performed by AP STAs such as AP 1502, AP 1602, and / or AP 1702, for example. As shown in FIG. 20, process 2000 may include steps 2002 and 2004.

[0186] Step 2002 includes transmitting, by an AP to a STA, afirstframe comprising precoding information (e.g., steering matrices) for use by the STA to transmit a second frame to the AP. In an embodiment, the first frame may comprise a trigger frame that triggers the transmitting of the second frame based on the precoding information. In an embodiment, the second frame may include a data frame, a management frame, or a control frame.

[0187] In an embodiment, 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 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 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 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.

[0188] In an embodiment, the first frame may comprise a trigger frame. In an embodiment, the precoding information may be comprised in a field of the trigger frame. In another embodiment, the precoding information may be comprised in a common info field of the trigger frame. In another embodiment, the 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 an embodiment, the second indication is provided in a user info field of the first trigger frame.

[0189] In additional or alternative embodiments, the first frame may comprise an action frame. In an embodiment, the 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.

[0190] In an embodiment, the first frame may further indicate whether or not at least one frame transmitted using the precoding information will be solicited by the AP after the STA transmits the second frame. In an embodiment, the first frame may include a second indication that at least one frame transmitted using the precoding information will be solicited by the AP after the STA transmits the second frame.

[0191] Step 2004 includes transmitting, by the AP to the STA, a third frame within a duration of transmitting the first frame, wherein based on the third frame being transmitted within the duration, the third frame may indicate to the STA to use the precoding information to transmit a fourth frame to the AP. In an embodiment, the third frame may comprise a trigger frame that triggers the transmitting of the fourth frame based on the precoding information. In an embodiment, the fourth frame may include a data frame, a management frame, or a control frame.

[0192] In embodiments, process 2000 may further comprise, before the first frame is transmitted by the AP, transmitting, by the AP to the STA, a fifth frame including the duration. In an embodiment, the duration may correspond to a predetermined duration. In an implementation, the predetermined duration may be set to 100 ms. In an embodiment, the fifth frame may correspond to a management frame, including a beacon frame and / or an action frame.

[0193] In an embodiment, process 2000 may further comprise, receiving, by the AP from the STA, the second frame, with the second frame being transmitted using the precoding information. In an embodiment, the second frame may indicate to the AP whether or not the precoding information is available at the STA after the second frame is transmitted. In an embodiment, the second frame may include a third indication whether or not the precoding information is available at the STA after transmitting the second frame. In an embodiment, the third frame may further indicate that the STA use the precoding information to transmit a fourth frame to the AP. In an embodiment, the third frame may correspond to a second trigger frame, and the third frame may indicate to the STA to use the precoding information further based on the second indication.

Claims

CLAIMSWhat is claimed is:

1. 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; receiving, by the AP from the STA, the first frame; and transmitting, by the AP to the STA, a second trigger frame, wherein based on the second trigger frame being transmitted within a duration of transmitting the first trigger frame, the second trigger frame indicates to the STA to use the precoding information to transmit a second frame to the AP.

2. A method comprising: transmitting, by an access point (AP) to a station (STA), a first frame comprising precoding information for use by the STA to transmit a second frame to the AP; and transmitting, by the AP to the STA, a third frame within a duration of transmitting the first frame, wherein based on the third frame being transmitted within the duration, the third frame indicates to the STA to use the precoding information to transmit a fourth frame to the AP.

3. The method of claim 2, further comprising receiving, by the AP from the STA, the second frame in response to the first frame.

4. The method of any of claims 2-3, further comprising receiving, by the AP from the STA, the fourth frame in response to the third frame.

5. The method of any of claims 2-4, wherein the first frame comprises a trigger frame, and wherein the precoding information is provided in a common info field of the trigger frame6. The method of claim 2-5, wherein the first frame comprises a first trigger frame, and wherein the precoding information is provided in a user info field of the first trigger frame.

7. The method of any of claims 2-5, wherein the first frame comprises an action frame, wherein the precoding information is provided in a field of the action frame.

8. The method of claim 7, wherein the field of the action frame comprises a UHR steering matrix field of the action frame.

9. The method of claim 7, wherein the field of the action frame comprises a UHR multiple input multiple output (MIMO) Control field of the action frame.

10. The method of any of claims 2-9, wherein the third frame comprises a first indication to use the precoding information to transmit the fourth frame to the AP.

11. The method of claim 10, wherein the third frame comprises a first trigger frame, and wherein the first indication is provided in a field of the first trigger frame.

12. The method of claim 11 , wherein the field comprises a common info field of the first trigger frame.

13. The method of claim 11 , wherein the field comprises a user info field of the first trigger frame.

14. The method of any of claims 2-13, wherein the duration comprises a predetermined duration.

15. The method of claim 14, wherein the predetermined duration is less than or equal to 100 ms.

16. The method of any of claims 2-15, further comprising transmitting, by the AP to the STA, a fifth frame comprising the duration.

17. The method of claim 16, wherein the fifth frame comprises a management frame.

18. The method of claim 17, wherein the management frame comprises a beacon frame or an action frame.

19. The method of claim 17, wherein the transmitting of the fifth frame comprises transmitting the fifth frame to the STA before the transmitting of the first frame to the STA.

20. The method of any of claims 2-19, wherein the first frame comprises a second indication whether at least one frame transmitted by the STA using the precoding information will be solicited by the AP after the STA transmits the second frame.

21. The method of claim 20, wherein the second indication is provided in a common info field of the first frame.

22. The method of claim 20, wherein the second indication is provided in a user info field of the first frame.

23. The method of any of claims 20-22, wherein the third frame comprises a trigger frame, and wherein the third frame indicates to the STA to use the precoding information further based on the second indication.

24. The method of any of claims 2-23, wherein the second frame indicates to the AP whether the precoding information is available at the STA after the second frame is transmitted by the STA.

25. The method of claim 24, wherein the second frame requests the AP to initiate a sounding procedure.

26. The method of claim 24, wherein the second frame requests the AP to retransmit the precoding information.

27. The method of claim 26, further comprising transmitting, by the AP to the STA, a seventh frame comprising the precoding information.

28. A method comprising: receiving, by a station (STA) from an access point (AP), a first frame comprising precoding information for use by the STA to transmit a second frame to the AP; transmitting, by the STA to the AP, the second frame using the precoding information; receiving, by the STA from the AP, a third frame for transmission of a fourth frame to the AP; based on the third frame being received within a first duration of the receiving of the first frame, determining, by the STA, to use the precoding information to transmit the fourth frame to the AP; and transmitting, by the STA to the AP, the fourth frame.

29. A method comprising: receiving, by a station (STA) from an access point (AP), a first frame comprising precoding information for use by the STA to transmit a second frame to the AP; and based on a third frame being received from the AP within a first duration of the receiving of the first frame, transmitting, by the STA to the AP, a fourth frame using the precoding information.

30. The method of claim 29, further comprising transmitting, by the STA to the AP, the second frame in response to the first frame.

31. The method of any of claims 29-30, further comprising, transmitting, by the STA to the AP, the fourth frame in response to the third frame.

32. The method of any of claims 29-31, wherein the first frame comprises a trigger frame, wherein the precoding information is provided in a common info field of the trigger frame.

33. The method of any of claims 29-32, wherein the third frame comprises a first indication to the STA to use the precoding information to transmit the fourth frame to the AP.

34. The method of claim 33, wherein the first frame comprises a first trigger frame, wherein the first indication is provided in a field of the first trigger frame.

35. The method of claim 34, wherein the first indication is provided in a common info field of the first trigger frame.

36. The method of claim 34, wherein the first indication is provided in a user info field of the first trigger frame.

37. The method of claim 29-33, wherein the first frame comprises a first trigger frame, and wherein the precoding information is provided in a user info field of the first trigger frame.

38. The method of any of claims 29-37, wherein the first frame comprises an action frame, wherein the precoding information is provided in a field of the action frame.

39. The method of claim 38, wherein the precoding information is provided in a UHR steering matrix field of the action frame.

40. The method of claim 38, wherein the precoding information is provided in a UHR multiple input multiple output (MIMO) Control field of the action frame.

41. The method of any of claims 29-40, wherein the first duration comprises a predetermined duration.

42. The method of claim 41 , wherein the predetermined duration comprises 100 ms.

43. The method of claim 29-42, further comprising, before receiving the first frame, receiving, by the STA from theAP, a fifth frame comprising the first duration.

44. The method of claim 43, wherein the fifth frame comprises a management frame.

45. The method of claim 44, wherein the management frame comprises a beacon frame or an action frame.

46. The method of any of claims 29-45, wherein the first frame further indicates to the STA whether or not at least one frame transmitted using the precoding information will be solicited by the AP after the STA transmits the second frame.

47. The method of claim 46, wherein the first frame comprises a second indication to the STA that at least one frame transmitted using the precoding information will be solicited by the AP after the STA transmits the second frame, and wherein the first frame comprises a first trigger frame.

48. The method of claim 47, wherein the second indication is provided in a common info field of the first trigger frame.

49. The method of claim 47, wherein the second indication is provided in a user info field of the first trigger frame.

50. The method of any of claims 47-49, wherein the third frame comprises a second trigger frame, and wherein the third frame indicates to the STA to use the precoding information further based on the second indication.

51. The method of any of claims 29-50, wherein the second frame indicates to the AP whether or not the precoding information is available at the STA after transmitting the second frame.

52. The method of claim 51 , wherein the second frame comprises a third indication to the AP whether or not the precoding information is available at the STA after transmitting the second frame.

53. The method of claim 52, wherein the third frame comprises the precoding information, based on the third indication.

54. The method of claim 52, wherein the precoding information comprises first precoding information, and wherein, based on the third indication, the third frame comprises second precoding information, different from the first precoding information.

55. The method of claim 29, further comprising, when the STA receives the third frame after the first duration of the receiving of the first frame or the STA does not receive the third frame, discarding, by the STA, the precoding information.

56. 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 1-55.

57. 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 1-55.

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