Patent ID: 12218884

Like reference numbers and designations in the various drawings indicate like elements.

DETAILED DESCRIPTION

The following description is directed to certain implementations for the purposes of describing innovative aspects of this disclosure. However, a person having ordinary skill in the art will readily recognize that the teachings herein can be applied in a multitude of different ways. The described implementations can be implemented in any device, system or network that is capable of transmitting and receiving radio frequency (RF) signals according to one or more of the Institute of Electrical and Electronics Engineers (IEEE) 802.11 standards, the IEEE 802.15 standards, the Bluetooth® standards as defined by the Bluetooth Special Interest Group (SIG), or the Long Term Evolution (LTE), 3G, 4G or 5G (New Radio (NR)) standards promulgated by the 3rd Generation Partnership Project (3GPP), among others. The described implementations can be implemented in any device, system or network that is capable of transmitting and receiving RF signals according to one or more of the following technologies or techniques: code division multiple access (CDMA), time division multiple access (TDMA), frequency division multiple access (FDMA), orthogonal FDMA (OFDMA), single-carrier FDMA (SC-FDMA), single-user (SU) multiple-input multiple-output (MIMO) and multi-user (MU) MIMO. The described implementations also can be implemented using other wireless communication protocols or RF signals suitable for use in one or more of a wireless personal area network (WPAN), a wireless local area network (WLAN), a wireless wide area network (WWAN), or an internet of things (IOT) network.

As used herein, the term “distributed transmission” refers to the transmission of a physical layer convergence protocol (PLCP) protocol data unit (PPDU) on noncontiguous tones (or subcarriers) of a wireless channel (such as in accordance with a “distributed tone plan”). Such noncontiguous tones represent a “distributed” resource unit (dRU). In contrast, a “regular” resource unit (rRU) is any set of contiguous tones defined by existing versions of the IEEE 802.11 standard (also referred to as a “non-distributed tone plan”). Distributed transmissions provide greater flexibility in medium utilization for power spectral density (PSD)-limited wireless channels. As described above, the low power indoor (LPI) power class limits the transmit power of APs and STAs in the 6 GHz band to 5 dBm/MHz and −1 dBm/MHz, respectively. By allowing a wireless communication device to distribute the tones allocated for the transmission of a PPDU across noncontiguous subcarrier indices of a wireless channel, distributed transmissions may increase the overall transmit power of the PPDU without exceeding the PSD limits of the wireless channel. For example, a distributed tone plan may reduce the total number of tones modulated by the device on any 1-MHz subchannel of the wireless channel. As a result, the wireless communication device may increase its per-tone transmit power without exceeding the PSD limits.

The IEEE 802.11 standard defines a PPDU format, to be used for wireless communication, which includes one or more short training fields (STFs). STFs are generally used for automatic gain control (AGC) and carrier frequency (DC) estimation at a receiving device. For example, a transmitting device may transmit a known pattern of symbols, in an STF, to the receiving device. The receiving device may use its knowledge of the symbol pattern and its periodicity in the received STF (also referred to as an “STF sequence”) to estimate the power of the received signals and perform DC estimation. Further, the receiving device may dynamically adjust the gain of its amplifiers based on the estimated power of the STF and correct the DC of the received signals to ensure more accurate reception of the data portion of the PPDU. Existing versions of the IEEE 802.11 standard define various STF sequences and tone plans (also referred to as “existing STF tone plans”) associated with various PPDU formats and bandwidths. According to existing versions of the IEEE 802.11 standard, rRUs are transmitted over respective bandwidths (or sub-bands) allocated exclusively for the rRUs, and an STF associated with each rRU is transmitted over the STF tones within that rRU. However, in distributed transmissions, multiple dRUs can be transmitted on interleaved tones of a shared bandwidth (also referred to as the “spreading bandwidth” or “distribution bandwidth”). Because the STF is used to estimate the signal power of the modulated tones, changing the tone plan used for PPDU transmissions (such as from a non-distributed tone plan to a distributed tone plan) may require new dRU-related signaling and STF designs.

Various aspects relate generally to distributed transmissions, and more particularly, to STF designs and signaling that support distributed transmissions. In some aspects, a transmitting device may transmit data on a dRU and may transmit an STF sequence over a spreading bandwidth of the dRU according to an existing STF tone plan. Thus, in a trigger-based (TB) PPDU, wireless stations (STAs) that are assigned dRUs in the same spreading bandwidth may transmit the same STF sequence on the same set of tones. In some implementations, each STA that is allocated a dRU for transmission in a TB PPDU may map its STF sequence to one or more spatial streams and may apply one or more global cyclic shift delays (CSDs) to the STF sequence mapped to the one or more spatial streams, respectively. As used herein, the term “global CSD” refers to CSD assignments that account for a position of each STA associated with a PPDU. For example, different global CSDs may be assigned to different STAs so that each STA transmits its STF sequence with different amounts of delay. In some implementations, each STA may randomly generate its global CSD values. In some other implementations, each STA may select its global CSD values from a CSD table based on information assigned to the STA (such as an association identifier (AID) value or an RU index, an RU assignment index, or a start tone offset associated with the dRU). Still further, in some implementations, each STA may receive an indication of its global CSD index or values in a trigger frame soliciting the TB PPDU. In some aspects, the trigger frame may carry distributed transmission information indicating which STAs are allocated dRUs for transmission in the TB PPDU and may carry dRU distribution bandwidth information indicating the spreading bandwidths associated with the dRUs.

Particular implementations of the subject matter described in this disclosure can be implemented to realize one or more of the following potential advantages. As described above, transmitting the data portion of a PPDU on noncontiguous tones of a wireless channel allows the transmitting device to increase the overall transmit power of the data without exceeding the PSD limits of the wireless channel. Transmitting the STF of the PPDU over the spreading bandwidth of the dRU allows a receiving device to more accurately estimate the power of the received signals associated with the data portion. By reusing existing STF tone plans, aspects of the present disclosure may support AGC for distributed transmissions with only minor changes to the IEEE 802.11 standard. However, aspects of the present disclosure recognize that unintentional beamforming may result from multiple STAs concurrently transmitting the same STF sequence on the same set of tones (such as in a TB PPDU). For example, such superimposed STF transmissions may constructively, or destructively, interfere at the receiving device, causing the receiving device to obtain inaccurate power measurements for the received signals. By applying global CSDs to the STF sequence transmitted by each STA on each spatial stream, aspects of the present disclosure may decouple the STF transmissions from multiple STAs in the time domain. More specifically, the global CSDs may stagger the phases of the STF transmissions across different STAs and different spatial streams, thereby preventing or reducing unintentional beamforming at the receiving device.

FIG.1shows a block diagram of an example wireless communication network100. According to some aspects, the wireless communication network100can be an example of a wireless local area network (WLAN) such as a Wi-Fi network (and will hereinafter be referred to as WLAN100). For example, the WLAN100can be a network implementing at least one of the IEEE 802.11 family of wireless communication protocol standards (such as that defined by the IEEE 802.11-2020 specification or amendments thereof including, but not limited to, 802.11ah, 802.11ad, 802.11ay, 802.11ax, 802.11az, 802.11ba and 802.11be). The WLAN100may include numerous wireless communication devices such as an access point (AP)102and multiple stations (STAs)104. While only one AP102is shown, the WLAN network100also can include multiple APs102.

Each of the STAs104also may be referred to as a mobile station (MS), a mobile device, a mobile handset, a wireless handset, an access terminal (AT), a user equipment (UE), a subscriber station (SS), or a subscriber unit, among other possibilities. The STAs104may represent various devices such as mobile phones, personal digital assistant (PDAs), other handheld devices, netbooks, notebook computers, tablet computers, laptops, display devices (for example, TVs, computer monitors, navigation systems, among others), music or other audio or stereo devices, remote control devices (“remotes”), printers, kitchen or other household appliances, key fobs (for example, for passive keyless entry and start (PKES) systems), among other possibilities.

A single AP102and an associated set of STAs104may be referred to as a basic service set (BSS), which is managed by the respective AP102.FIG.1additionally shows an example coverage area108of the AP102, which may represent a basic service area (BSA) of the WLAN100. The BSS may be identified to users by a service set identifier (SSID), as well as to other devices by a basic service set identifier (BSSID), which may be a medium access control (MAC) address of the AP102. The AP102periodically broadcasts beacon frames (“beacons”) including the BSSID to enable any STAs104within wireless range of the AP102to “associate” or re-associate with the AP102to establish a respective communication link106(hereinafter also referred to as a “Wi-Fi link”), or to maintain a communication link106, with the AP102. For example, the beacons can include an identification of a primary channel used by the respective AP102as well as a timing synchronization function for establishing or maintaining timing synchronization with the AP102. The AP102may provide access to external networks to various STAs104in the WLAN via respective communication links106.

To establish a communication link106with an AP102, each of the STAs104is configured to perform passive or active scanning operations (“scans”) on frequency channels in one or more frequency bands (for example, the 2.4 GHz, 5 GHz, 6 GHz or 60 GHz bands). To perform passive scanning, a STA104listens for beacons, which are transmitted by respective APs102at a periodic time interval referred to as the target beacon transmission time (TBTT) (measured in time units (TUs) where one TU may be equal to 1024 microseconds (μs)). To perform active scanning, a STA104generates and sequentially transmits probe requests on each channel to be scanned and listens for probe responses from APs102. Each STA104may be configured to identify or select an AP102with which to associate based on the scanning information obtained through the passive or active scans, and to perform authentication and association operations to establish a communication link106with the selected AP102. The AP102assigns an association identifier (AID) to the STA104at the culmination of the association operations, which the AP102uses to track the STA104.

As a result of the increasing ubiquity of wireless networks, a STA104may have the opportunity to select one of many BSSs within range of the STA or to select among multiple APs102that together form an extended service set (ESS) including multiple connected BSSs. An extended network station associated with the WLAN100may be connected to a wired or wireless distribution system that may allow multiple APs102to be connected in such an ESS. As such, a STA104can be covered by more than one AP102and can associate with different APs102at different times for different transmissions. Additionally, after association with an AP102, a STA104also may be configured to periodically scan its surroundings to find a more suitable AP102with which to associate. For example, a STA104that is moving relative to its associated AP102may perform a “roaming” scan to find another AP102having more desirable network characteristics such as a greater received signal strength indicator (RSSI) or a reduced traffic load.

In some cases, STAs104may form networks without APs102or other equipment other than the STAs104themselves. One example of such a network is an ad hoc network (or wireless ad hoc network). Ad hoc networks may alternatively be referred to as mesh networks or peer-to-peer (P2P) networks. In some cases, ad hoc networks may be implemented within a larger wireless network such as the WLAN100. In such implementations, while the STAs104may be capable of communicating with each other through the AP102using communication links106, STAs104also can communicate directly with each other via direct wireless links110. Additionally, two STAs104may communicate via a direct communication link110regardless of whether both STAs104are associated with and served by the same AP102. In such an ad hoc system, one or more of the STAs104may assume the role filled by the AP102in a BSS. Such a STA104may be referred to as a group owner (GO) and may coordinate transmissions within the ad hoc network. Examples of direct wireless links110include Wi-Fi Direct connections, connections established by using a Wi-Fi Tunneled Direct Link Setup (TDLS) link, and other P2P group connections.

The APs102and STAs104may function and communicate (via the respective communication links106) according to the IEEE 802.11 family of wireless communication protocol standards (such as that defined by the IEEE 802.11-2016 specification or amendments thereof including, but not limited to, 802.11ah, 802.11ad, 802.11ay, 802.11ax, 802.11az, 802.11ba and 802.11be). These standards define the WLAN radio and baseband protocols for the PHY and medium access control (MAC) layers. The APs102and STAs104transmit and receive wireless communications (hereinafter also referred to as “Wi-Fi communications”) to and from one another in the form of physical layer convergence protocol (PLCP) protocol data units (PPDUs). The APs102and STAs104in the WLAN100may transmit PPDUs over an unlicensed spectrum, which may be a portion of spectrum that includes frequency bands traditionally used by Wi-Fi technology, such as the 2.4 GHz band, the 5 GHz band, the 60 GHz band, the 3.6 GHz band, and the 700 MHz band. Some implementations of the APs102and STAs104described herein also may communicate in other frequency bands, such as the 6 GHz band, which may support both licensed and unlicensed communications. The APs102and STAs104also can be configured to communicate over other frequency bands such as shared licensed frequency bands, where multiple operators may have a license to operate in the same or overlapping frequency band or bands.

Each of the frequency bands may include multiple sub-bands or frequency channels. For example, PPDUs conforming to the IEEE 802.11n, 802.11ac, 802.11ax and 802.11be standard amendments may be transmitted over the 2.4, 5 GHz or 6 GHz bands, each of which is divided into multiple 20 MHz channels. As such, these PPDUs are transmitted over a physical channel having a minimum bandwidth of 20 MHz, but larger channels can be formed through channel bonding. For example, PPDUs may be transmitted over physical channels having bandwidths of 40 MHz, 80 MHz, 160 or 320 MHz by bonding together multiple 20 MHz channels.

Each PPDU is a composite structure that includes a PHY preamble and a payload in the form of a PHY service data unit (PSDU). The information provided in the 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, 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.

FIG.2Ashows an example protocol data unit (PDU)200usable for wireless communication between an AP102and one or more STAs104. For example, the PDU200can be configured as a PPDU. As shown, the PDU200includes a PHY preamble202and a PHY payload204. For example, the preamble202may include a legacy portion that itself includes a legacy short training field (L-STF)206, which may consist of two BPSK symbols, a legacy long training field (L-LTF)208, which may consist of two BPSK symbols, and a legacy signal field (L-SIG)210, which may consist of two BPSK symbols. The legacy portion of the preamble202may be configured according to the IEEE 802.11a wireless communication protocol standard. The preamble202may also include a non-legacy portion including one or more non-legacy fields212, for example, conforming to an IEEE wireless communication protocol such as the IEEE 802.11ac, 802.11ax, 802.11be or later wireless communication protocol protocols.

The L-STF206generally enables a receiving device to perform automatic gain control (AGC) and coarse timing and frequency estimation. The L-LTF208generally enables a receiving device to perform fine timing and frequency estimation and also to perform an initial estimate of the wireless channel. The L-SIG210generally enables a receiving device to determine a duration of the PDU and to use the determined duration to avoid transmitting on top of the PDU. For example, the L-STF206, the L-LTF208and the L-SIG210may be modulated according to a binary phase shift keying (BPSK) modulation scheme. The payload204may be modulated according to a BPSK modulation scheme, a quadrature BPSK (Q-BPSK) modulation scheme, a quadrature amplitude modulation (QAM) modulation scheme, or another appropriate modulation scheme. The payload204may include a PSDU including a data field (DATA)214that, in turn, may carry higher layer data, for example, in the form of medium access control (MAC) protocol data units (MPDUs) or an aggregated MPDU (A-MPDU).

FIG.2Bshows an example L-SIG210in the PDU200ofFIG.2A. The L-SIG210includes a data rate field222, a reserved bit224, a length field226, a parity bit228, and a tail field230. The data rate field222indicates a data rate (note that the data rate indicated in the data rate field212may not be the actual data rate of the data carried in the payload204). The length field226indicates a length of the packet in units of, for example, symbols or bytes. The parity bit228may be used to detect bit errors. The tail field230includes tail bits that may be used by the receiving device to terminate operation of a decoder (for example, a Viterbi decoder). The receiving device may utilize the data rate and the length indicated in the data rate field222and the length field226to determine a duration of the packet in units of, for example, microseconds (μs) or other time units.

FIG.3shows an example PPDU300usable for communications between an AP102and one or more STAs104. As described above, each PPDU300includes a PHY preamble302and a PSDU304. Each PSDU304may represent (or “carry”) one or more MAC protocol data units (MPDUs)316. For example, each PSDU304may carry an aggregated MPDU (A-MPDU)306that includes an aggregation of multiple A-MPDU subframes308. Each A-MPDU subframe306may include an MPDU frame310that includes a MAC delimiter312and a MAC header314prior to the accompanying MPDU316, which comprises the data portion (“payload” or “frame body”) of the MPDU frame310. Each MPDU frame310may also include a frame check sequence (FCS) field318for error detection (for example, the FCS field may include a cyclic redundancy check (CRC)) and padding bits320. The MPDU316may carry one or more MAC service data units (MSDUs)326. For example, the MPDU316may carry an aggregated MSDU (A-MSDU)322including multiple A-MSDU subframes324. Each A-MSDU subframe324contains a corresponding MSDU330preceded by a subframe header328and in some cases followed by padding bits332.

Referring back to the MPDU frame310, the MAC delimiter312may serve as a marker of the start of the associated MPDU316and indicate the length of the associated MPDU316. The MAC header314may include multiple fields containing information that defines or indicates characteristics or attributes of data encapsulated within the frame body316. The MAC header314includes a duration field indicating a duration extending from the end of the PPDU until at least the end of an acknowledgment (ACK) or Block ACK (BA) of the PPDU that is to be transmitted by the receiving wireless communication device. The use of the duration field serves to reserve the wireless medium for the indicated duration, and enables the receiving device to establish its network allocation vector (NAV). The MAC header314also includes one or more fields indicating addresses for the data encapsulated within the frame body316. For example, the MAC header314may include a combination of a source address, a transmitter address, a receiver address or a destination address. The MAC header314may further include a frame control field containing control information. The frame control field may specify a frame type, for example, a data frame, a control frame, or a management frame.

FIG.4shows a block diagram of an example wireless communication device400. In some implementations, the wireless communication device400can be an example of a device for use in a STA such as one of the STAs104described with reference toFIG.1. In some implementations, the wireless communication device400can be an example of a device for use in an AP such as the AP102described with reference toFIG.1. The wireless communication device400is capable of transmitting (or outputting for transmission) and receiving wireless communications (for example, in the form of wireless packets). For example, the wireless communication device can be configured to transmit and receive packets in the form of physical layer convergence protocol (PLCP) protocol data units (PPDUs) and medium access control (MAC) protocol data units (MPDUs) conforming to an IEEE 802.11 wireless communication protocol standard, such as that defined by the IEEE 802.11-2016 specification or amendments thereof including, but not limited to, 802.11ah, 802.11ad, 802.11ay, 802.11ax, 802.11az, 802.11ba and 802.11be.

The wireless communication device400can be, or can include, a chip, system on chip (SoC), chipset, package or device that includes one or more modems402, for example, a Wi-Fi (IEEE 802.11 compliant) modem. In some implementations, the one or more modems402(collectively “the modem402”) additionally include a WWAN modem (for example, a 3GPP 4G LTE or 5G compliant modem). In some implementations, the wireless communication device400also includes one or more radios404(collectively “the radio404”). In some implementations, the wireless communication device406further includes one or more processors, processing blocks or processing elements406(collectively “the processor406”) and one or more memory blocks or elements408(collectively “the memory408”).

The modem402can include an intelligent hardware block or device such as, for example, an application-specific integrated circuit (ASIC) among other possibilities. The modem402is generally configured to implement a PHY layer. For example, the modem402is configured to modulate packets and to output the modulated packets to the radio404for transmission over the wireless medium. The modem402is similarly configured to obtain modulated packets received by the radio404and to demodulate the packets to provide demodulated packets. In addition to a modulator and a demodulator, the modem402may further include digital signal processing (DSP) circuitry, automatic gain control (AGC), a coder, a decoder, a multiplexer and a demultiplexer. For example, while in a transmission mode, data obtained from the processor406is provided to a coder, which encodes the data to provide encoded bits. The encoded bits are then mapped to points in a modulation constellation (using a selected MCS) to provide modulated symbols. The modulated symbols may then be mapped to a number NSSof spatial streams or a number NSTSof space-time streams. The modulated symbols in the respective spatial or space-time streams may then be multiplexed, transformed via an inverse fast Fourier transform (IFFT) block, and subsequently provided to the DSP circuitry for Tx windowing and filtering. The digital signals may then be provided to a digital-to-analog converter (DAC). The resultant analog signals may then be provided to a frequency upconverter, and ultimately, the radio404. In implementations involving beamforming, the modulated symbols in the respective spatial streams are precoded via a steering matrix prior to their provision to the IFFT block.

While in a reception mode, digital signals received from the radio404are provided to the DSP circuitry, which is configured to acquire a received signal, for example, by detecting the presence of the signal and estimating the initial timing and frequency offsets. The DSP circuitry is further configured to digitally condition the digital signals, for example, using channel (narrowband) filtering, analog impairment conditioning (such as correcting for UQ imbalance), and applying digital gain to ultimately obtain a narrowband signal. The output of the DSP circuitry may then be fed to the AGC, which is configured to use information extracted from the digital signals, for example, in one or more received training fields, to determine an appropriate gain. The output of the DSP circuitry also is coupled with the demodulator, which is configured to extract modulated symbols from the signal and, for example, compute the logarithm likelihood ratios (LLRs) for each bit position of each subcarrier in each spatial stream. The demodulator is coupled with the decoder, which may be configured to process the LLRs to provide decoded bits. The decoded bits from all of the spatial streams are then fed to the demultiplexer for demultiplexing. The demultiplexed bits may then be descrambled and provided to the MAC layer (the processor406) for processing, evaluation or interpretation.

The radio404generally includes at least one radio frequency (RF) transmitter (or “transmitter chain”) and at least one RF receiver (or “receiver chain”), which may be combined into one or more transceivers. For example, the RF transmitters and receivers may include various DSP circuitry including at least one power amplifier (PA) and at least one low-noise amplifier (LNA), respectively. The RF transmitters and receivers may, in turn, be coupled to one or more antennas. For example, in some implementations, the wireless communication device400can include, or be coupled with, multiple transmit antennas (each with a corresponding transmit chain) and multiple receive antennas (each with a corresponding receive chain). The symbols output from the modem402are provided to the radio404, which then transmits the symbols via the coupled antennas. Similarly, symbols received via the antennas are obtained by the radio404, which then provides the symbols to the modem402.

The processor406can include an intelligent hardware block or device such as, for example, a processing core, a processing block, a central processing unit (CPU), a microprocessor, a microcontroller, a digital signal processor (DSP), an application-specific integrated circuit (ASIC), a programmable logic device (PLD) such as a field programmable gate array (FPGA), discrete gate or transistor logic, discrete hardware components, or any combination thereof designed to perform the functions described herein. The processor406processes information received through the radio404and the modem402, and processes information to be output through the modem402and the radio404for transmission through the wireless medium. For example, the processor406may implement a control plane and MAC layer configured to perform various operations related to the generation and transmission of MPDUs, frames or packets. The MAC layer is configured to perform or facilitate the coding and decoding of frames, spatial multiplexing, space-time block coding (STBC), beamforming, and OFDMA resource allocation, among other operations or techniques. In some implementations, the processor406may generally control the modem402to cause the modem to perform various operations described above.

The memory408can include tangible storage media such as random-access memory (RAM) or read-only memory (ROM), or combinations thereof. The memory408also can store non-transitory processor- or computer-executable software (SW) code containing instructions that, when executed by the processor406, cause the processor to perform various operations described herein for wireless communication, including the generation, transmission, reception and interpretation of MPDUs, frames or packets. For example, various functions of components disclosed herein, or various blocks or steps of a method, operation, process or algorithm disclosed herein, can be implemented as one or more modules of one or more computer programs.

FIG.5Ashows a block diagram of an example AP502. For example, the AP502can be an example implementation of the AP102described with reference toFIG.1. The AP502includes a wireless communication device (WCD)510(although the AP502may itself also be referred to generally as a wireless communication device as used herein). For example, the wireless communication device510may be an example implementation of the wireless communication device400described with reference toFIG.4. The AP502also includes multiple antennas520coupled with the wireless communication device510to transmit and receive wireless communications. In some implementations, the AP502additionally includes an application processor530coupled with the wireless communication device510, and a memory540coupled with the application processor530. The AP502further includes at least one external network interface550that enables the AP502to communicate with a core network or backhaul network to gain access to external networks including the Internet. For example, the external network interface550may include one or both of a wired (for example, Ethernet) network interface and a wireless network interface (such as a WWAN interface). Ones of the aforementioned components can communicate with other ones of the components directly or indirectly, over at least one bus. The AP502further includes a housing that encompasses the wireless communication device510, the application processor530, the memory540, and at least portions of the antennas520and external network interface550.

FIG.5Bshows a block diagram of an example STA504. For example, the STA504can be an example implementation of the STA104described with reference toFIG.1. The STA504includes a wireless communication device515(although the STA504may itself also be referred to generally as a wireless communication device as used herein). For example, the wireless communication device515may be an example implementation of the wireless communication device400described with reference toFIG.4. The STA504also includes one or more antennas525coupled with the wireless communication device515to transmit and receive wireless communications. The STA504additionally includes an application processor535coupled with the wireless communication device515, and a memory545coupled with the application processor535. In some implementations, the STA504further includes a user interface (UI)555(such as a touchscreen or keypad) and a display565, which may be integrated with the UI555to form a touchscreen display. In some implementations, the STA504may further include one or more sensors575such as, for example, one or more inertial sensors, accelerometers, temperature sensors, pressure sensors, or altitude sensors. Ones of the aforementioned components can communicate with other ones of the components directly or indirectly, over at least one bus. The STA504further includes a housing that encompasses the wireless communication device515, the application processor535, the memory545, and at least portions of the antennas525, UI555, and display565.

As described above, the term “distributed transmission” refers to the transmission of a PPDU on noncontiguous tones (or subcarriers) of a wireless channel (such as in accordance with a “distributed tone plan”). Such noncontiguous tones represent a dRU. In contrast, an rRU is any set of contiguous tones defined by existing versions of the IEEE 802.11 standard (also referred to as a “non-distributed tone plan”). Distributed transmissions provide greater flexibility in medium utilization for PSD-limited wireless channels. As described above, the LPI power class limits the transmit power of APs and STAs in the 6 GHz band to 5 dBm/MHz and −1 dBm/MHz, respectively. By allowing a wireless communication device to distribute the tones allocated for the transmission of a PPDU across noncontiguous subcarrier indices of a wireless channel, distributed transmissions may increase the overall transmit power of the PPDU without exceeding the PSD limits of the wireless channel. For example, a distributed tone plan may reduce the total number of tones modulated by the device on any 1-MHz subchannel of the wireless channel. As a result, the wireless communication device may increase its per-tone transmit power without exceeding the PSD limits.

Various aspects relate generally to distributed transmissions, and more particularly, to STF designs and signaling that support distributed transmissions. In some aspects, a transmitting device may transmit data on a dRU and may transmit an STF sequence over a spreading bandwidth of the dRU according to an existing STF tone plan. Thus, in a TB PPDU, STAs that are assigned dRUs in the same spreading bandwidth may transmit the same STF sequence on the same set of tones. In some implementations, each STA that is allocated a dRU for transmission in a TB PPDU may map its STF sequence to one or more spatial streams and may apply one or more global CSDs to the STF sequence mapped to the one or more spatial streams, respectively. As used herein, the term “global CSD” refers to CSD assignments that account for a position of each STA associated with a PPDU. For example, different global CSDs may be assigned to different STAs so that each STA transmits its STF sequence with different amounts of delay. In some implementations, each STA may randomly generate its global CSD values. In some other implementations, each STA may select its global CSD values from a CSD table based on information assigned to the STA (such as an AID value or an RU index, an RU assignment index, or a start tone offset associated with the dRU). Still further, in some implementations, each STA may receive an indication of its global CSD index or values in a trigger frame soliciting the TB PPDU. In some aspects, the trigger frame may carry distributed transmission information indicating which STAs are allocated dRUs for transmission in the TB PPDU and may carry dRU distribution bandwidth information indicating the spreading bandwidths associated with the dRUs.

Particular implementations of the subject matter described in this disclosure can be implemented to realize one or more of the following potential advantages. As described above, transmitting the data portion of a PPDU on noncontiguous tones of a wireless channel allows the transmitting device to increase the overall transmit power of the data without exceeding the PSD limits of the wireless channel. Transmitting the STF of the PPDU over the spreading bandwidth of the dRU allows a receiving device to more accurately estimate the power of the received signals associated with the data portion. By reusing existing STF tone plans, aspects of the present disclosure may support AGC for distributed transmissions with only minor changes to the IEEE 802.11 standard. However, aspects of the present disclosure recognize that unintentional beamforming may result from multiple STAs concurrently transmitting the same STF sequence on the same set of tones (such as in a TB PPDU). For example, such superimposed STF transmissions may constructively, or destructively, interfere at the receiving device, causing the receiving device to obtain inaccurate power measurements for the received signals. By applying global CSDs to the STF sequence transmitted by each STA on each spatial stream, aspects of the present disclosure may decouple the STF transmissions from multiple STAs in the time domain. More specifically, the global CSDs may stagger the phases of the STF transmissions across different STAs and different spatial streams, thereby preventing or reducing unintentional beamforming at the receiving device.

FIG.6shows a frequency diagram600depicting an example distributed tone mapping according to some implementations. More specifically,FIG.6shows an example mapping of a payload601of a PPDU602to a set of tones or subcarriers for transmission over a wireless channel. In some implementations, the payload601may be modulated on a logical RU604associated with a non-distributed tone plan (such as a legacy tone plan or a non-legacy tone plan) and further mapped to a dRU606in accordance with a distributed tone plan. The logical RU604represents a number of tones or subcarriers that are allocated for the transmission of the PPDU602. In contrast, the dRU606represents the physical resources (identified by subcarrier indices) that are modulated to transmit the PPDU602. As used herein, the term “distributed RU” or dRU refers to any logical RU that is distributed across a set of noncontiguous subcarrier indices, and the term “distributed tone plan” refers to the set of noncontiguous subcarrier indices associated with a dRU.

Existing versions of the IEEE 802.11 standard define a number of RUs and multiple RUs (MRUs) of various sizes that map to contiguous tones or subcarriers spanning a frequency bandwidth (or wireless channel). For example, a 242-tone RU maps to 242 contiguous subcarrier indices spanning a 20 MHz bandwidth. Similarly, a 484+242-tone MRU maps to 484 contiguous subcarrier indices spanning a 40 MHz bandwidth and to 242 contiguous subcarrier indices spanning a 20 MHz bandwidth. As used herein, the term “regular RU” or rRU refers to any RU or MRU configuration that is supported by existing versions of the IEEE 802.11 standard (up to, and including, the IEEE 802.11be amendment of the IEEE 802.11 standard), and the term “non-distributed tone plan” refers to any tone plan defined by existing versions of the IEEE 802.11 standard. Further, the term “legacy” is used herein to refer to PPDU formats and communication protocols conforming to the IEEE 802.11ax amendment, or earlier versions, of the IEEE 802.11 standard. For example, a “legacy tone plan” may be any non-distributed tone plan supported by the IEEE 802.11ax amendment. In contrast, the term “non-legacy” is used herein to refer to PPDU formats and communication protocols conforming to the IEEE 802.11be amendment, and future generations, of the IEEE 802.11 standard. For example, a “non-legacy tone plan” may be any non-distributed tone plan supported by the IEEE 802.11be amendment.

In some implementations, the logical RU604may represent an rRU as defined by existing versions of the IEEE 802.11 standard. In other words, the logical RU604maps directly to a respective rRU according to a non-distributed tone plan. In the example ofFIG.6, the logical RU604includes 26 tones. Thus, in accordance with a non-distributed tone plan, the logical RU604would map directly to 26 contiguous or consecutive subcarrier indices spanning a 2 MHz subchannel. However, when mapped to an rRU, the transmit power of the logical RU604may be severely limited based on the PSD of the wireless channel. For example, the LPI power class limits the transmit power of APs and STAs to 5 dBm/MHz and −1 dBm/MHz, respectively, in the 6 GHz band. As such, the per-tone transmit power of the logical RU604is limited by the number of tones mapped to each 1 MHz subchannel of the wireless channel. Accordingly, each 1 MHz subchannel of a PSD-limited channel may be referred to herein as a “PSD-limited subchannel.”

Aspects of the present disclosure recognize that the per-tone transmit power of the logical RU604can be increased by distributing the tones across a wider bandwidth. Increasing the per-tone transmit power can also increase the overall transmit power of the logical RU604. Thus, in some implementations, the logical RU604may be mapped to a set of noncontiguous subcarrier indices spanning a wider-bandwidth channel (referred to herein as a “spreading bandwidth” or “distribution bandwidth”). With reference for example toFIG.6, the logical RU604is mapped to the dRU606according to a distributed tone plan. More specifically, the logical RU604is mapped to 26 noncontiguous subcarrier indices spread across a 40 MHz wireless channel (where the spreading bandwidth is equal to 40 MHz). Compared to the tone mapping described above with respect to the non-distributed tone plan, the distributed tone mapping depicted inFIG.6effectively reduces the number of tones (of the logical RU604) in each 1 MHz subchannel. For example, each of the 26 tones can be mapped to a different 1 MHz subchannel of the 40 MHz channel. As a result, each AP or STA implementing the distributed tone mapping ofFIG.6can maximize its per-tone transmit power (which may maximize the overall transmit power of the logical RU604).

In some implementations, a transmitting device (such as a STA or an AP) may include a distributed tone mapper that maps the logical RU604to the dRU606in the frequency domain (such as described with reference toFIG.6). The dRU606is then converted to a time-domain signal (such as by an inverse fast Fourier transform (IFFT)) for transmission over a wireless channel. A receiving device (such as an AP or a STA) receives the time-domain signal over the wireless channel and converts the time-domain signal back to the dRU606(such as by a fast Fourier transform (FFT)). In some implementations, the receiving device may include a distributed tone demapper that demaps the dRU606to the logical RU604. In other words, the distributed tone demapper reverses the mapping performed by the distributed tone mapper at the transmitting device. The receiving device can then recover the information carried (or modulated) on the logical RU604as a result of the demapping.

In the example ofFIG.6, the logical RU604is distributed evenly across a 40 MHz wireless channel. However, in actual implementations, the logical RU604can be mapped to any suitable pattern of noncontiguous subcarrier indices. For example, in some aspects, the distance between any pair of modulated tones may be different (such as less or greater) than the distances depicted inFIG.6. Still further, in some aspects, multiple logical RUs may be mapped to interleaved subcarrier indices of a shared wireless channel.

FIG.7shows a frequency diagram depicting an example mapping of logical RUs702and704to dRUs706and708, respectively, according to some implementations. In some implementations, each of the logical RUs702and704may carry user data for a respective AP or STA (not shown for simplicity).

In the example ofFIG.7, each of the logical RUs702and704includes 26 tones and the spreading bandwidth is equal to 40 MHz. In some implementations, the logical RUs702and704are mapped to the dRUs706and708, respectively, according to a distributed tone plan. More specifically, the 26 tones associated with each of the logical RUs702and704is mapped to a respective set of 26 noncontiguous subcarrier indices spread across a 40 MHz wireless channel. In some implementations, the distributed tone plan maps the 26 tones of the first logical RU702to every 18thsubcarrier index starting at subcarrier index1and maps the 26 tones of the second logical RU704to every 18thsubcarrier index starting at subcarrier index10. As a result, the first dRU706includes every 18thtone modulated on subcarrier indices1through451, and the second dRU708includes every 18thtone modulated on subcarrier indices10through460.

As shown inFIG.7, the first tone of the logical RU702(tone_idx=1) is mapped to subcarrier index1, the second tone of the logical RU702(tone_idx=2) is mapped to subcarrier index19, and the mapping pattern continues until the 26thtone of the logical RU702(tone_idx=26) is mapped to subcarrier index451. Similarly, the first tone of the logical RU704(tone_idx=1) is mapped to subcarrier index10, the second tone of the logical RU704(tone_idx=2) is mapped to subcarrier index28, and the mapping pattern continues until the 26thtone of the logical RU704(tone_idx=26) is mapped to subcarrier index460. Thus, as shown inFIG.7, the distributed tone plan interleaves the logical RUs702and704, offset by 9 subcarrier indices, across the dRU spreading bandwidth. Aspects of the present disclosure recognize that, by interleaving the dRUs706and708, the per-tone transmit power of each dRU can be significantly increased without sacrificing spectral efficiency.

Aspects of the present disclosure recognize that new packet designs are needed to support distributed transmissions. For example, existing versions of the IEEE 802.11 standard define a PPDU format that includes a PHY preamble followed by a payload. As described with reference toFIGS.6and7, the payload may be transmitted on a dRU to achieve increased transmit power. The PHY preamble includes one or more STFs which may be used for AGC or DC estimation at a receiving device. For example, a transmitting device may transmit a known pattern of symbols, in an STF, to the receiving device. The receiving device may use its knowledge of the symbol pattern and its periodicity in the received STF (also referred to as an “STF sequence”) to estimate the power of the received signals and perform DC estimation. Further, the receiving device may dynamically adjust the gain of its amplifiers based on the estimated power of the STF and correct the DC of the received signals to ensure more accurate reception of the data portion of the PPDU. Existing versions of the IEEE 802.11 standard define various STF sequences and tone plans (also referred to as “existing STF tone plans”) associated with various PPDU formats and bandwidths. According to existing versions of the IEEE 802.11 standard, rRUs are transmitted over respective bandwidths (or sub-bands) allocated exclusively for the rRUs, and an STF associated with each rRU is transmitted over the STF tones within that rRU. However, as shown inFIG.7, multiple dRUs can be transmitted on interleaved tones of a shared bandwidth. Because the STF is used to estimate the signal power of the modulated tones, changing the tone plan used for PPDU transmissions (such as from a non-distributed tone plan to a distributed tone plan) may require new dRU-related signaling and STF designs.

FIG.8shows an example PPDU800usable for communications between an AP and one or more STAs according to some implementations. In some implementations, the PPDU800may be one example of the PPDU602ofFIG.6. The PPDU800includes a PHY preamble including a first portion802and a second portion804. The PPDU800may further include a PHY payload806after the preamble, for example, in the form of a PSDU carrying a DATA field826. In some implementations, the PPDU800may be formatted as a non-legacy or Extremely High Throughput (EHT) PPDU.

The first portion802of the PHY preamble includes L-STF808, L-LTF810, L-SIG812, a repeated legacy signal field (RL-SIG)814, and a universal signal field (U-SIG)816. In some implementations, the first portion804of the PHY preamble may further include a non-legacy signal field (EHT-SIG)818. With reference to the IEEE 802.11be amendment of the IEEE 802.11 standard, the first portion802may be referred to as a “pre-EHT modulated portion” of the PPDU800. The second portion804of the PHY preamble includes a non-legacy short training field (EHT-STF)822and a number of non-legacy long training fields (EHT-LTFs)824. With reference to the IEEE 802.11be amendment of the IEEE 802.11 standard, the second portion804, together with the PHY payload806, may be referred to as the “EHT modulated portion” of the PPDU800.

With reference for example toFIG.6, the PHY payload806may be one example of the payload601. The PHY payload806may be modulated on a logical RU that is further mapped to a dRU, for example, to achieve gains in transmit power. As described with reference toFIGS.6and7, the tones of the dRU are distributed across noncontiguous subcarrier indices associated with a wireless channel. The bandwidth of the wireless channel is referred to as the spreading bandwidth (BW) or “distribution bandwidth.” To achieve a noncontiguous tone distribution, the bandwidth of the logical RU on which the PHY payload806is modulated must be smaller than the spreading bandwidth. For example, as shown inFIG.6, the payload601is modulated on a 26-tone logical RU604having a bandwidth of approximately 2 MHz, and the tones of the logical RU604are further distributed across 26 noncontiguous subcarrier indices associated with the 40 MHz spreading bandwidth.

The EHT-STF822carries a sequence of values (or STF sequence) that is used for AGC at a receiving device. More specifically, the receiving device measures the power of the received STF signals and adjusts the gain of its amplifiers to more accurately receive the PHY payload806based on the measured power of the EHT-STF822. Thus, in some aspects, the EHT-STF822also may be transmitted across the spreading bandwidth of the dRU. Existing versions of the IEEE 802.11 standard define an STF tone plan that maps the values of the STF sequence to respective tones associated with a wireless channel. For example, the existing STF tone plan associated with a TB PPDU modulates every 8thtone in the wireless channel with a respective STF value. In some implementations, the EHT-STF822may be mapped to a series of tones spanning the spreading bandwidth in accordance with an existing STF tone plan. In other words, distributed transmissions may reuse existing EHT-STF sequence that are mapped to respective tones in the spreading bandwidth according to an existing STF tone plan.

FIG.9shows a frequency diagram900depicting an example STF sequence902usable for AGC in distributed transmissions. In some implementations, the STF sequence902may be one example of the EHT-STF822ofFIG.8. In the example ofFIG.9, the STF sequence902is mapped to a 40 MHz spreading bandwidth according to an existing STF tone plan defined for TB PPDUs. In some implementations, the STF sequence902may be an existing STF sequence defined for a 484-tone rRU. As shown inFIG.9, the values of the STF sequence902are mapped to every 8thsubcarrier index in a range of subcarrier indices from −248 to 248 (centered around DC) spanning the 40 MHz spreading bandwidth. As shown inFIG.9, the 1stvalue of the STF sequence902is modulated on subcarrier index −248, the 2ndvalue of the STF sequence902is modulated on subcarrier index −240, the 3rdvalue of the STF sequence902is modulated on subcarrier index −232, and the mapping is repeated until the last value of the STF sequence902is mapped to subcarrier index248.

Aspects of the present disclosure recognize that, by defining each STF sequence and tone mapping scheme for a given spreading bandwidth, the same STF sequence may be transmitted (on the same set of tones) by multiple STAs assigned to different dRUs that are allocated for transmission within the same spreading bandwidth. With reference for example toFIG.7, the STF sequence902may be transmitted by a first STA assigned to the dRU706and also may be transmitted by a second STA assigned to the dRU708. In some aspects, the first and second STAs may concurrently transmit the STF sequence902to a receiving device (such as in a TB PPDU), which may result in unintentional beamforming at the receiving device. For example, the receiving device may receive multiple copies of the STF sequence902that are superimposed on one another. However, random phase from each transmitter of the first and second STAs may cause the received signals to constructively, or destructively, interfere with one another, which is most prominent when they have the same channel response (such as additive white gaussian noise (AWGN)). As a result, the measured power associated with the STF may be significantly higher or lower than the actual power associated with any of the dRUs706or708.

FIG.10shows an example frame structure of a TB PPDU1000according to some implementations. The TB PPDU1000includes a pre-EHT modulated portion1002followed by an EHT modulated portion1004. The pre-EHT modulated portion1002includes an L-STF, an L-LTF, an L-SIG, an RL-SIG, and a U-SIG. The EHT modulated portion1004includes an EHT-STF, an EHT-LTF, and a data portion. In some implementations, the TB PPDU1000may be one example of the PPDU800ofFIG.8(excluding the EHT-SIG818).

In the example ofFIG.10, the TB PPDU1000may be transmitted over a 40 MHz bandwidth. To ensure proper packet detection and backwards compatibility with wireless communication devices that conform to existing versions of the IEEE 802.11 standard, the pre-EHT modulated portion1002of the TB PPDU1000may be duplicated on each 20 MHz sub-band of the 40 MHz bandwidth. For example, the information carried in L-STF, L-LTF, L-SIG, RL-SIG, and U-SIG may be transmitted on the 1st20 MHz sub-band and the same information may be duplicated on the 2nd20 MHz sub-band.

In contrast, the EHT modulated portion1004may be configured for transmission over the 40 MHz bandwidth as a whole. For example, a first data portion of the TB PPDU1000may be assigned to a first dRU1002mapped to the 40 MHz bandwidth and a second data portion of the TB PPDU1000may be assigned to a second dRU1004mapped to the 40 MHz bandwidth. In some implementations, the dRUs1002and1004may be examples of the dRUs702and704, respectively, ofFIG.7. Thus, the dRUs1002and1004may be transmitted on interleaved tones within the same 40 MHz spreading bandwidth.

In some implementations, the first dRU1002may be assigned to a first STA (STA1) and the second dRU1004may be assigned to a second STA (STA2). In other words, STA1 may transmit its data on dRU1002in the first data portion of the TB PPDU1000and STA2 may transmit its data on dRU1004in the second data portion of the TB PPDU1000. The EHT-LTFs carry a sequence of values (also referred to as an “LTF sequence”) that is used for channel estimation at the receiving device. As such, the EHT-LTFs may be transmitted on the same tones as the data portion of the TB PPDU1000. For example, STA1 may transmit an LTF sequence on dRU1002in the EHT-LTF of the TB PPDU1000and STA2 may transmit an LTF sequence on dRU1004in the EHT-LTF of the TB PPDU. In some aspects, the EHT-STF may carry an existing STF sequence associated with a 40 MHz bandwidth (such as shown inFIG.9). As such, STA1 and STA2 may transmit the same STF sequence on the same set of tones in the EHT-STF of the TB PPDU1000.

In some aspects, STA1 and STA2 may each transmit a respective portion of the TB PPDU1000over one or more spatial streams. For example, STA1 may transmit its portion of the TB PPDU1000(including EHT-STF and the EHT modulated portion1004mapped to dRU1002) on a number (m) of spatial streams. In some implementations, STA1 may apply m CSDs to the portion of the TB PPDU1000mapped to the m spatial streams, respectively, to avoid unintentional beamforming across the m spatial streams at the receiving device. Similarly, STA2 may transmit its portion of the TB PPDU1000(including EHT-STF and the EHT modulated portion1004mapped to dRU1004) on a number (n) of spatial streams. In some implementations, STA2 may apply n CSDs to the portion of the TB PPDU1000mapped to the n spatial streams, respectively, to avoid unintentional beamforming across the n spatial streams at the receiving device.

Aspects of the present disclosure recognize that, because the dRUs1002and1004are separated in frequency, local CSDs may be sufficient to overcome unintentional beamforming in the EHT-LTF and data portions of the TB PPDU1000. In other words, STA1 may apply its m CSDs “locally” or without regard for the n CSDs applied by STA2. Unintentional beamforming may be avoided in the EHT-LTF and data portions of the TB PPDU1000even if the m CSDs applied to the EHT-LTF and data portions mapped to the m spatial streams are equal to (or a subset or superset of) the n CSDs applied to the EHT-LTF and data portions mapped to the n spatial streams.

However, because STA1 and STA2 transmit the EHT-STF of the TB PPDU1000on the same set of tones, unintentional beamforming may still occur across the m+n spatial streams if STA1 and STA2 only apply local CSDs to their respective spatial streams. For example, if the m CSDs applied to the EHT-STF mapped to the m spatial streams are equal to (or a subset or superset of) the n CSDs applied to the EHT-STF mapped to the n spatial streams, unintentional beamforming may still occur in the EHT-STF of the TB PPDU1000as a result of cross-correlation between the m spatial streams transmitted by STA1 and the n spatial streams transmitted by STA2.

In some aspects, each STA that is assigned a dRU for transmission in a TB PPDU may apply one or more global CSDs to the EHT-STF of the TB PPDU mapped to one or more spatial streams, respectively. As described above, global CSDs account for the position of each STA associated with a TB PPDU. For example, the global CSD values assigned to each STA associated with a TB PPDU may be different than the global CSD values assigned to any other STAs associated with the TB PPDU. With reference for example toFIG.10, STA1 may apply m global CSD values to the EHT-STF mapped to the m spatial streams, respectively, and STA 2 may apply n global CSD values to the EHT-STF mapped to the n spatial streams, respectively, resulting in a different CSD being applied to the EHT-STF mapped to each of the m+n spatial streams. Accordingly, global CSDs effectively decouple the EHT-STF transmissions from multiple STAs in the time domain, thereby avoiding unintentional beamforming at the receiving device.

In some implementations, global CSDs may be applied to the entire EHT modulated portion1004of the TB PPDU1000. In such implementations, the transmitting device may apply the same phase slope (or the same CSD values) to EHT-STF, EHT-LTF, and the data portion of the TB PPDU1000, which may simplify the implementation of the transmitter of the TB PPDU1000. In some implementations, applying global CSDs to EHT-LTF may help reduce the receiver side peak-to-average power ratio (PAPR) or resolve unintentional beamforming issues associated with the transmission of the EHT-LTF. However, aspects of the present disclosure also recognize that existing versions of the IEEE 802.11 standard only support the use of local CSDs in the transmission and reception of EHT-LTF and data in a TB PPDU with UL OFDMA. Thus, applying global CSDs to the entire EHT modulated portion1004may require changes to the implementations of the transmitter and receiver of the TB PPDU1000.

In some other implementations, global CSDs may be applied only to the EHT-STF of the TB PPDU1000. In such implementations, the transmitting device may apply a different phase slope (or different CSD values) to EHT-STF than to EHT-LTF and the data portion of the TB PPDU1000, which may add more complexity to the implementation of the transmitter of the TB PPDU1000. However, local CSDs may be applied to the EHT-LTF and data portion of the TB PPD1000in conformance with existing versions of the IEEE 802.11 standard. Aspects of the present disclosure further recognize that the processing of EHT-STF at the receiving device is agnostic to (or unaffected by) the values of the CSDs. Thus, applying global CSDs exclusively to EHT-STF may reduce or minimize the required changes to the implementations of the transmitter and receiver of the TB PPDU1000.

FIG.11shows a block diagram of an example transmit (TX) processing chain1100of a wireless communication device according to some implementations. More specifically, the TX processing chain1100may be configured to transmit an STF sequence1102representing an EHT-STF of a PPDU (such as the EHT-STF822ofFIG.8or the EHT-STF ofFIG.10). In some implementations, the wireless communication device may be an AP such as any of the APs102or502ofFIGS.1and5A, respectively. In some other implementations, the wireless communication device may be a STA such as any of the STAs104or504ofFIGS.1and5B, respectively.

The TX processing chain1100includes an STF sequence selector1110, a CSD phase rotator1130, a spatial stream (SS) mapper1140, and a number (N) of inverse fast Fourier transforms (IFFTs)1150(1)-1150(n). The STF sequence selector1110selects the STF sequence1102to be transmitted in the PPDU. In some aspects, the STF sequence selector1110may select the STF sequence1102based on a spreading bandwidth1101associated with a dRU allocated for transmission, in the PPDU, by the wireless communication device. In some implementations, the STF sequence selector1110may select an STF sequence1102that maps to the spreading bandwidth1101in accordance with existing versions of the IEEE 802.11 standard (such as described with reference toFIGS.8and9). The selected STF sequence1102is copied onto a number (n) of data streams.

The phase rotator1130is configured to apply n CSDs to the n data streams, respectively, of the STF sequence1102to produce a phase rotated STF sequence1104. For example, the CSDs may add phase rotations or delays to one or more of the n data streams to prevent unintentional beamforming at the receiving device. As described with reference toFIGS.8-10, multiple STAs may concurrently transmit the same STF sequence on the same set of tones when assigned respective dRUs within the same spreading bandwidth. In some aspects, the phase rotator1130may assign a respective global CSD value to each of the n CSDs to prevent unintentional beamforming across multiple STAs. For example, the phase rotator1130may determine or select the n global CSD values responsive to being allocated a dRU for transmission in a TB PPDU.

The SS mapper1120maps the phase-rotated n-stream STF sequence1104to N TX chain signals SS1-SSNto produce a spatially mapped STF sequence1106. For example, the SS mapper1120may apply a spatial mapping matrix (such as a Q matrix) to the modulation values associated with the STF sequence1104. As a result of the spatial mapping, each of the data streams is projected on a respective transmitter chain (as the spatially mapped STF sequence1106). The IFFTs1150(1)-1150(N) convert the STF sequence1106on the N TX chain signals SS1-SSN, respectively, from the frequency domain to the time domain. For example, each IFFT1150may produce a respective series of time-varying samples representative of the modulation values mapped to each spatial stream. The time-varying samples represent a time-domain STF signal1108that can be transmitted, over a wireless channel, via n transmitter chains (not shown for simplicity).

Aspects of the present disclosure recognize that the effectiveness of the phase rotator1130at decoupling the STF signals1108from any STF signals that are concurrently transmitted concurrently by other wireless communication devices depends on the uniqueness of the global CSD values. Ideally, the global CSD values applied by the phase rotator1130should be different than the global CSD values applied by any other wireless communication devices associated with the same TB PPDU. Thus, in some implementations, the phase rotator1130may derive the global CSD values based on global CSD derivation information1103that is unique to the wireless communication device. In some aspects, the global CSD derivation information1103may include information that is assigned to the wireless communication device. Example suitable information may include an association identifier (AID) value, an RU index or an RU assignment index associated with its assigned dRU, or a start tone offset associated with its assigned dRU, among other examples.

In some implementations, the phase rotator1130may randomly generate the n global CSD values, for example, using a random number generator or as a function of the information assigned to the wireless communication device. For example, the global CSD values may be generated as a function of the AID value, a maximum (M) global CSD value (such as 800 ns), a granularity (Δ) of the global CSD values (such as 25 ns), and a desired distance or spacing (D) between AID values, according to Equation 1.

CSD0=mod⁡(AID*D,MΔ)*Δ(1)
The phase rotator1130can generate an initial global CSD value (CSD0) for the wireless communication device based on Equation 1. In some implementations, the phase rotator1130may generate the remaining n−1 global CSD values by incrementing CSD0by a factor of A (for example, n−1 times). The value of D is used to increase the spacing between AID values to reduce the likelihood of assigning overlapping global CSD values to different STAs (also referred to herein as “collisions”). For example, D may be set to

M2⁢Δ-1.

In some other implementations, a number (N) of global CSD values may be generally defined for all dRU transmissions. In such implementations, each wireless communication device that supports distributed transmissions has knowledge of the same N global CSD values. For example, each of the N global CSD values may be stored as a respective entry in a CSD table1132. In some implementations, N may be equal to 8. An example CSD table having 8 entries (N=8) is shown below, where the value of each entry indicates a respective amount of delay (in ns):
[0 −400 −200 −600 −350 −650 −100 −750]

In some other implementations, N may be equal to 16. Aspects of the present disclosure recognize that increasing the number of distinct global CSD values (larger values of N) reduces the likelihood of collisions. However, larger CSD tables also may require changes to the IEEE 802.11 standard and to the implementation of the transmitter. An example CSD table having 16 entries (N=16) is shown below, where the value of each entry indicates a respective amount of delay (in ns):
[0 −400 −200 −600 −350 −650 −100 −750 −250 −550 −300 −450 −50 −700 −150 −500]

Another example CSD table having 16 entries (N=16) is shown below, where the values of the last 8 entries are rotated versions of the first 8 entries:
[0 −400 −200 −600 −350 −650 −100 −750(0+Δ)(−400+Δ)(−200+Δ)(−600+Δ)(−350+Δ) (−650+Δ)(−100+Δ)(−750+Δ)]
In the CSD table above, A represents a phase offset (such as 50 ns) that can be applied to each of the first 8 entries of the CSD table to produce the last 8 entries of the CSD table.

In some implementations, the phase rotator1130may algorithmically determine a start index associated with the CSD table1132based on the information assigned to the wireless communication device (STA_assignment_info). For example, the start index may be calculated as a function of STA_assignment_info and N, according to Equation 2.
start index=mod(STA_assignment_info,N)+1  (2)
Based on Equation 2, the start index will have a value between 0 and N−1, which points to one of the N entries of the CSD table1132. Thus, the phase rotator1130may use the start index to determine an initial global CSD value for the wireless communication device. In some implementations, the phase rotator1130may determine the remaining n−1 global CSD values by incrementing the start index (for example, n−1 times) and retrieving the corresponding entries from the CSD table1132.

In some implementations, STA_assignment_info may be an AID value assigned to the wireless communication device. For example, each STA associated with a BSS is assigned an AID value that identifies the STA within the BSS. The AID value is known to the wireless communication device upon associating with the BSS and may be used to identify user-specific information carried in a trigger frame (such as in a user information field). In some other implementations, STA_assignment_info may be an RU assignment index or RU index associated with the dRU assigned to the wireless communication device. For example, a trigger frame may allocate a dRU to a STA based on an RU assignment index that conforms with an existing RU allocation table. The RU assignment index or RU index may indicate the size and relative position of the dRU within a given bandwidth (such as the first 26-tone dRU of a 40 MHz bandwidth, the second 26-tone dRU of a 40 MHz bandwidth, the first 52-tone dRU of an 80 MHz bandwidth, or the second 52-tone dRU of an 80 MHz bandwidth, among other examples).

Still further, in some implementations, STA_assignment_info may be a start tone offset associated with the DRU assigned to the wireless communication device. For example, dRUs that are mapped to the same spreading bandwidth are offset from one another by a number of subcarrier indices depending on the size of each dRU and its RU index. The distance between the first tone of a dRU of a given size and the first tone of the first dRU of that size is referred to herein as the “start tone offset.” With reference for example toFIG.7, the dRU706has a start tone offset equal to 0 because it is the first 26-tone dRU mapped to the 40 MHz spreading bandwidth. In contrast, the dRU708has a start tone offset equal to 9 because it is the second 26-tone dRU mapped to the 40 MHz spreading bandwidth and the first tone of the dRU708(mapped to subcarrier index10) is offset by 9 subcarrier indices from the first tone of the dRU706(mapped to subcarrier index1).

Aspects of the present disclosure recognize that collisions cannot be entirely avoided when each STA derives its own global CSD values (randomly or algorithmically). For example, some BSSs may randomly assign the same AID value to multiple STAs. Thus, when STA_assignment_info is the AID value of the wireless communication device, Equations 1 and 2 may produce the same CSD values for STAs that are assigned the same AID value. Further, when STA_assignment_info is the RU assignment index, Equation 2 may produce the same CSD values for multiple RU assignment indices (because the RU allocation table is fixed). For example, the modulo operation produces the same CSD value of 1 for RU assignment indices0and8(where N=8). A similar issue may occur when STA_assignment_info is the start tone offset. For example, the first 26-tone dRU in a 20 MHz spreading bandwidth has a start tone offset equal to 0 and the fifth 26-tone dRU in the 20 MHz bandwidth has a start tone offset equal to 8. Thus, when STA_assignment_info is the start tone offset, Equation 2 may produce the same CSD values for multiple dRU assignments.

Aspects of the present disclosure further recognize that dRU construction follows a hierarchical structure. In other words, larger dRUs are constructed from multiple smaller dRUs. Table 1 shows an example hierarchical dRU structure of 26-tone dRUs (dRU26), 52-tone dRUs (dRU52), and 106-tone dRUs (dRU106) associated with a 20 MHz bandwidth.

TABLE 1dRU261dRU262dRU263dRU264dRU265dRU266dRU267dRU268dRU269dRU521dRU522dRU523dRU524dRU1061dRU1062

This hierarchical structure can prevent overlapping dRUs from being allocated for transmission in the same frequency bandwidth or sub-band. Thus, in some aspects, new global CSD start index tables can be designed based on the hierarchical dRU structure to further reduce the probability of CSD collisions. Table 2 shows an example global CSD start index table associated with a 20 MHz bandwidth, where each entry of Table 2 maps to a respective dRU index (or dRU assignment index) in Table 1.

TABLE 2123445678135715

In some implementations, the values of the global CSD start index tables can be used, in lieu of Equation 2, to determine each STA's global CSD values. For example, a STA that is assigned dRU261in a 20 MHz spreading bandwidth (RU assignment index=0 and start tone offset=0) determines its start index to be equal to 1 according to Table 2.

In some aspects, the receiving device (or the device soliciting the TB PPDU) may assign the global CSD values to each STA associated with the TB PPDU. For example, the receiving device may provide an indication of the global CSD values assigned to each STA in the trigger frame soliciting the TB PPDU. In some implementations, the trigger frame may carry CSD information indicating a respective start index assigned to each of the STAs associated with the TB PPDU. In such implementations, the phase rotator1130may receive the start index as the global CSD derivation information1103and may retrieve the appropriate CSD values from the CSD table1132pointed to by the start index. In some implementations, the trigger frame may carry distributed transmission information indicating whether the RU assignment index allocated to each STA represents an rRU or a dRU and may carry dRU distribution bandwidth information indicating the spreading bandwidth associated with each dRU.

FIG.12shows an example trigger frame1200usable for communications between an AP and one or more STAs according to some implementations. The trigger frame1200may be used to solicit a TB PPDU (such as the TB PPDU1000ofFIG.10) from one or more STAs. With reference for example toFIG.1, the AP102may transmit the trigger frame1200to solicit a TB PPDU from one or more of the STAs104. The trigger frame1200may allocate resources (such as one or more rRUs or dRUs) for transmission in the TB PPDU.

The trigger frame1200includes a MAC header1210, a common information field1220, a user information list1230, zero or more padding bits1240, and an FCS 1250. The MAC header1210includes a frame control field, a duration field, a receiver address (RA) field, and a transmitter address (TA) field. The common information field1220and user information list1230carry configuration information which may be used by a receiving device to configure a TB PPDU to be transmitted in response to receiving the trigger frame1200. In some aspects, the user information list1230may include one or more user information fields1232each carrying per-user information for a respective user. In contrast, the common information field1220may carry information that is common to all recipients of the trigger frame1200(such as any users identified in the user information list1230).

In some implementations, each user information field1232may carry RU allocation information1233, distributed transmission information1234, dRU distribution bandwidth information1235, and a dRU CSD start index1236. The RU allocation information1233indicates a logical RU (or MRU) that is allocated for the user associated with the user information field1232and the distributed transmission information1234indicates whether the logical RU maps to an rRU or a dRU. If the distributed transmission information1234indicates that the logical RU is a dRU, the dRU distribution bandwidth information1235may indicate the spreading bandwidth associated with the dRU and the dRU CSD start index1236may point to a respective entry of a global CSD table that stores a number (N) of global CSD values.

In some implementations, the global CSD table (such as the CSD table1132ofFIG.11) may store 8 global CSD values (N=8). In such implementations, the dRU CSD start index1236may be a 3-bit value that points to a distinct entry of the global CSD table. In some other implementations, the global CSD table may store 16 global CSD values (N=16). In such implementations, the dRU CSD start index1236may be a 3-bit value that points to a respective entry in the upper half of the global CSD table or a respective entry in the lower half of the global CSD table. In some implementations, the user information field1232may further carry disambiguation information (such as an additional bit) signaling whether the dRU CSD start index1236points to an entry in the upper half of the global CSD table or the lower half of the global CSD table.

In some other implementations, the disambiguation information may be signaled implicitly. For example, the STA associated with the user information field1232may derive the disambiguation information based on other information assigned to the STA. In some implementations, the disambiguation information may be derived based on the AID value assigned to the STA. For example, STAs assigned to even AID values may interpret the dRU CSD start index1236as pointing to an entry in the upper half of the CSD table whereas STAs assigned to odd AID values may interpret the dRU CSD start index1236as pointing to an entry in the lower half of the CSD table.

The RU allocation information1233may be carried in an RU allocation subfield of the user information field1232, such as defined by existing versions of the IEEE 802.11 standard. In other words, the existing RU allocation subfield can be reused to indicate the logical RU associated with an rRU or dRU transmission. In contrast, the distributed transmission information1234, the dRU distribution bandwidth information1235, and the dRU CSD start index1236represent new signaling that is currently not included in existing trigger frame formats. The distributed transmission information1234may require at least 1 bit (to indicate rRU or dRU), the dRU distribution bandwidth information1235may require at least 2 bits (to indicate a 20 MHz, 40 MHz, or 80 MHz spreading bandwidth), and the dRU CSD start index1236may require at least 3 bits.

Aspects of the present disclosure recognize that the trigger frame1200may include a number of reserved bits. Reserved bits represent unused bits that are reserved for future implementations of the IEEE 802.11 standard. For example, one or more reserved bits in an earlier version or release of the IEEE 802.11 standard may be repurposed (to carry information) in a later version or release. In some implementations, a number of reserved bits associated with an existing trigger frame format may be repurposed to carry the distributed transmission information1234, the dRU distribution bandwidth information1235, or the dRU CSD start index1236. As described above, the new signaling may require at least 6 total bits to convey.

FIG.13shows a user information field1300for a trigger frame formatted in accordance with an existing trigger frame format. More specifically, the user information field1300conforms to the EHT variant user information field format defined by an initial release of the IEEE 802.11be amendment of the IEEE 802.11 standard. With reference for example toFIG.12, the user information field1300may be one example of the user information field1232. Each user information field in a user information list is identified by a respective AID value in the AID12 subfield (in bit positions B0-B11). In some aspects, the AID value may uniquely identify a particular STA (or user) in a BSS.

The user information field1300also includes an RU allocation subfield (in bit positions B12-B19) and a PS160 subfield (in bit position B39). A combined value of the RU allocation subfield and the PS160 subfield maps to an entry in an RU allocation table. The RU allocation table is a lookup table that stores a number of entries representing respective RU or MRU allocations. Specifically, each entry in the RU allocation table may indicate a bandwidth, an RU size, and an RU index. In some aspects, the RU allocation subfield may carry the RU allocation information1233ofFIG.12. In some implementations, any entry in the RU allocation table may be allocated for distributed transmissions. In some other implementations, only a subset of the entries in the RU allocation table may be allocated for distributed transmissions (such as 26-tone, 52-tone, 106-tone, and 242-tone RUs).

As shown inFIG.13, the user information field1300includes a reserved bit (in bit position B25). In some aspects, the reserved bit (B25) of the user information field1300may be repurposed to carry the distributed transmission information1234ofFIG.12. For example, the reserved bit may be replaced by a distributed transmission bit (or subfield) in future releases or versions of the IEEE 802.11 standard. More specifically, a first value of the distributed transmission bit (such as “0”) may indicate that the logical RU (or MRU) allocated by the RU allocation subfield maps to an rRU. On the other hand, a second value of the distributed transmission bit (such as “1”) may indicate that the logical RU (or MRU) allocated by the RU allocation subfield maps to a dRU.

Aspects of the present disclosure recognize that MU MIMO may not be supported for distributed transmissions. As such, the SS allocation subfield (in bit positions B26-B31) can be repurposed to carry dRU-related signaling when the distributed transmission bit indicates that the logical RU maps to a dRU. In some implementations, 2 bits of the SS allocation subfield may be repurposed to carry the dRU distribution bandwidth information1235, 3 bits of the SS allocation subfield may be repurposed to carry the dRU CSD start index1236, and the last remaining bit of the SS allocation subfield may be repurposed to carry spatial stream information indicating a number of spatial streams assigned to the STA (such as 1 spatial stream or 2 spatial streams).

FIG.14shows another example trigger frame1400usable for communications between an AP and one or more STAs according to some implementations. The trigger frame1400may be used to solicit a TB PPDU (such as the TB PPDU1000ofFIG.10) from one or more STAs. With reference for example toFIG.1, the AP102may transmit the trigger frame1400to solicit a TB PPDU from one or more of the STAs104. The trigger frame1400may allocate resources (such as one or more rRUs or dRUs) for transmission in the TB PPDU.

The trigger frame1400includes a MAC header1410, a common information field1420, a user information list1430, zero or more padding bits1440, and an FCS 1450. The MAC header1410includes a frame control field, a duration field, an RA field, and a TA field. The common information field1420and user information list1430carry configuration information which may be used by a receiving device to configure a TB PPDU to be transmitted in response to receiving the trigger frame1400. In some aspects, the user information list1430may include one or more user information fields1432each carrying per-user information for a respective user. In contrast, the common information field1420may carry information that is common to all recipients of the trigger frame1400(such as any users identified in the user information list1430).

In some implementations, the common information field1420may carry dRU and distribution bandwidth information1422indicating whether the logical RUs allocated for transmission in a particular bandwidth or sub-band associated with the TB PPDU map to an rRU or a dRU. The dRU and distribution bandwidth information1422may further indicate a spreading bandwidth associated with any dRUs allocated for transmission within the given sub-band. In some implementations, the dRU and distribution bandwidth information1422may include a 3-bit bitmap per 80 MHz sub-band associated with the TB PPDU. Each bitmap may indicate whether the logical RUs associated with an 80 MHz sub-band map to:an rRU;a dRU spread over the first 20 MHz sub-band;a dRU spread over the first 40 MHz sub-band;a dRU spread over a 40 MHz portion of an 80 MHz sub-band;a dRU spread over an 80 MHz sub-band;a dRU spread over a 20 MHz portion plus a dRU spread over a 40 MHz portion of a (punctured) 80 MHz sub-band; ora dRU spread over a 40 MHz portion plus a dRU spread over a 20 MHz portion of a (punctured) 80 MHz sub-band.

Aspects of the present disclosure recognize that 12 bits are needed for the dRU and distribution bandwidth information1422to cover an entire 320 MHz PPDU bandwidth. However, 12 bits may not be available to be repurposed in the common information field1420. Thus, in some other implementations, some or all of the dRU and distribution bandwidth information1422may be carried in a special user information field1438of the user information list1430. As described with reference toFIG.13, each user information field1432of the user information list1430is identified by an AID value that is assigned to a particular STA in a BSS. In contrast, the special user information field1438may be identified by an AID value that is not assigned to any STA in the BSS (such as2007). In some aspects, the special user information field1438may be an extension of the common information field1420. In other words, the special user information field1438may carry information that is common to all users associated with the trigger frame.

In some implementations, each user information field1432may carry RU allocation information1434and a dRU CSD start index1436. The RU allocation information1434indicates a logical RU (or MRU) that is allocated for the user associated with the user information field1432. The STA may determine whether the logical RU maps to an rRU or a dRU based on the dRU and distribution bandwidth information1422. For example, if the logical RU is allocated for transmission in an 80 MHz sub-band that is designated for rRUs, the STA may determine that its logical RU assignment maps to an rRU. On the other hand, if the logical RU is allocated for transmission in an 80 MHz sub-band that is designated for dRUs, the STA may determine that its logical RU assignment maps to a dRU. The spreading bandwidth associated with the dRU is further indicated by the dRU and distribution bandwidth information1422.

If the dRU and distribution bandwidth information1422indicates that the logical RU is a dRU, the dRU CSD start index1436may point to a respective entry of a global CSD table that stores a number (N) of global CSD values. In some implementations, the global CSD table (such as the CSD table1132ofFIG.11) may store 8 global CSD values (N=8). In such implementations, the CSD start index1436may be a 3-bit value that points to a distinct entry of the global CSD table. In some other implementations, the global CSD table may store 16 global CSD values (N=16). In such implementations, the CSD start index1436may be a 3-bit value that points to a respective entry in the upper half of the global CSD table or a respective entry in the lower half of the global CSD table. The STA associated with the user information field1432may determine whether the dRU CSD start index1436points to an entry in the upper or lower half of the global CSD table based on explicit or implicit disambiguation information (such as described with reference toFIG.12).

The RU allocation information1434may be carried in an RU allocation subfield of the user information field1432, such as defined by existing versions of the IEEE 802.11 standard. In other words, the existing RU allocation subfield can be reused to indicate the logical RU associated with an rRU or dRU transmission. In contrast, the dRU and distribution bandwidth information1422and the dRU CSD start index1436represent new signaling that is currently not included in existing trigger frame formats. As described above, the dRU and distribution bandwidth information1422may require at least 12 bits and the dRU CSD start index1436may require at least 3 bits. In some implementations, the dRU CSD start index1436may be signaled by repurposing 3 bits of an SS allocation subfield of the user information field1432(such as described with reference toFIG.13). In some implementations, the dRU and distribution bandwidth information1422may be signaled by repurposing a number of reserved bits in the common information field1420or a number of reserved bits in the special user information field1438.

FIG.15shows a common information field1500for a trigger frame formatted in accordance with an existing trigger frame format. More specifically, the common information field1500conforms to the EHT variant common information field format defined by an initial release of the IEEE 802.11be amendment of the IEEE 802.11 standard. With reference for example toFIG.14, the common information field1500may be one example of the common field1420. In the example ofFIG.15, the common information field1500may be included in a trigger frame that is configured to solicit an EHT TB PPDU.

As shown inFIG.15, the common information field1500includes a total of 8 reserved bits (in bit positions B56-B62 and B63). In some aspects, any number of the reserved bits may be repurposed to carry at least part of the dRU and distribution bandwidth information1422ofFIG.14. For example, the reserved bits may be replaced by a dRU and distribution bandwidth subfield in future releases or versions of the IEEE 802.11 standard. More specifically, the dRU and distribution bandwidth subfield may include at least 3 bits representing a bitmap associated with an 80 MHz sub-band of the PPDU bandwidth (such as described with reference toFIG.14). In some implementations, the dRU and distribution bandwidth subfield may include an additional 3 bits representing a bitmap associated with another 80 MHz sub-band of the PPDU bandwidth.

FIG.16shows a special user information field1600for a trigger frame formatted in accordance with an existing trigger frame format. More specifically, the special user information field1600conforms to the special user information field format defined by an initial release of the IEEE 802.11be amendment of the IEEE 802.11 standard. Thus, the AID12 subfield (in bit positions B0-B11) may carry an AID value equal to 2007. With reference for example toFIG.14, the special user information field1600may be one example of the special user information field1438. More specifically, the special user information field1600may be an extension of a common information field of the underlying trigger frame (such as the common information field1420).

As shown inFIG.16, the special user information field1600includes a total of 3 reserved bits (in bit position B37-B39) and 12 U-SIG disregard and validate bits (in bit positions B25-B36). In accordance with the EHT TB PPDU format, reserved bits are further subdivided into validate bits and disregard bits. The validate bits are used to indicate whether a STA should continue receiving the PPDU whereas the disregard bits may be ignored by the receiving STA. In some aspects, any number of the reserved bits may be repurposed to carry at least a portion of the dRU and distribution bandwidth information1422ofFIG.14. For example, the reserved bits may be replaced by a dRU and distribution bandwidth subfield in future releases or versions of the IEEE 802.11 standard. More specifically, the dRU and distribution bandwidth subfield may include 3 bits representing a bitmap associated with an 80 MHz sub-band of the PPDU bandwidth (such as described with reference toFIG.14).

In some other aspects, any number of the U-SIG disregard and validate bits may be repurposed to carry at least a portion of the dRU and distribution bandwidth information1422. For example, the U-SIG disregard and validate bits may be replaced by a dRU and distribution bandwidth subfield in future releases or versions of the IEEE 802.11 standard. More specifically, the dRU and distribution bandwidth subfield may include at least 3 bits representing a bitmap associated with an 80 MHz sub-band of the PPDU bandwidth. In some implementations, all 12 U-SIG disregard and validate bits may be repurposed to carry the dRU and distribution bandwidth information1422in its entirety. For example, the dRU and distribution bandwidth subfield may carry four 3-bit bitmaps that cover all 80 MHz sub-bands of a 320 MHz PPDU bandwidth. In such implementations, the dRU and distribution bandwidth information1422may be carried exclusively in the special user information field1438(in lieu of the common information field1420).

FIG.17shows another example trigger frame1700usable for communications between an AP and one or more STAs according to some implementations. The trigger frame1700may be used to solicit a TB PPDU (such as the TB PPDU1000ofFIG.10) from one or more STAs. With reference for example toFIG.1, the AP102may transmit the trigger frame1700to solicit a TB PPDU from one or more of the STAs104. The trigger frame1700may allocate resources (such as one or more rRUs or dRUs) for transmission in the TB PPDU.

The trigger frame1700includes a MAC header1710, a common information field1720, a user information list1730, zero or more padding bits1740, and an FCS 1750. The MAC header1710includes a frame control field, a duration field, an RA field, and a TA field. The common information field1720and user information list1730carry configuration information which may be used by a receiving device to configure a TB PPDU to be transmitted in response to receiving the trigger frame1700. In some aspects, the user information list1730may include one or more user information fields1732each carrying per-user information for a respective user. In contrast, the common information field1720may carry information that is common to all recipients of the trigger frame1700(such as any users identified in the user information list1730).

In some implementations, the common information field1720may carry distributed transmission information1722indicating whether the logical RUs allocated for transmission in a particular bandwidth or sub-band associated with the TB PPDU map to an rRU or a dRU. In some implementations, the distributed transmission information1722may include a 4-bit bitmap, where each bit corresponds to a respective 80 MHz sub-band associated with the TB PPDU. More specifically, each bit of the bitmap may indicate whether the logical RUs associated with a respective 80 MHz sub-band map to an rRU or a dRU.

In some implementations, each user information field1732may carry RU allocation information1734, dRU distribution bandwidth information1736, and a dRU CSD start index1738. The RU allocation information1734indicates a logical RU (or MRU) that is allocated for the user associated with the user information field1732. The STA may determine whether the logical RU maps to an rRU or a dRU based on the distributed transmission information1722. For example, if the logical RU is allocated for transmission in an 80 MHz sub-band that is designated for rRUs, the STA may determine that its logical RU assignment maps to an rRU. On the other hand, if the logical RU is allocated for transmission in an 80 MHz sub-band that is designated for dRUs, the STA may determine that its logical RU assignment maps to a dRU. If the distributed transmission information1722indicates that the logical RU is a dRU, the dRU distribution bandwidth information1736may indicate the spreading bandwidth associated with the dRU and the dRU CSD start index1738may point to a respective entry of a global CSD table that stores a number (N) of global CSD values.

In some implementations, the global CSD table (such as the CSD table1132ofFIG.11) may store 8 global CSD values (N=8). In such implementations, the CSD start index1738may be a 3-bit value that points to a distinct entry of the global CSD table. In some other implementations, the global CSD table may store 16 global CSD values (N=16). In such implementations, the CSD start index1738may be a 3-bit value that points to a respective entry in the upper half of the global CSD table or a respective entry in the lower half of the global CSD table. The STA associated with the user information field1732may determine whether the dRU CSD start index1738points to an entry in the upper or lower half of the global CSD table based on explicit or implicit disambiguation information (such as described with reference toFIG.12).

The RU allocation information1734may be carried in an RU allocation subfield of the user information field1732, such as defined by existing versions of the IEEE 802.11 standard. In other words, the existing RU allocation subfield can be reused to indicate the logical RU associated with an rRU or dRU transmission. In contrast, the distributed transmission information1722, the dRU distribution bandwidth information1736, and the dRU CSD start index1738represent new signaling that is currently not included in existing trigger frame formats. As described above, the distributed transmission information1722may require at least 4 bits, the dRU distribution bandwidth information1736may require at least 2 bits (to indicate a 20 MHz, 40 MHz, or 80 MHz spreading bandwidth), and the dRU CSD start index1738may require at least 3 bits.

In some implementations, the dRU distribution bandwidth information1736may be signaled by repurposing 2 bits of an SS allocation subfield of the user information field1732, and the dRU CSD start index1738may be signaled by repurposing 3 bits of the SS allocation subfield (such as described with reference toFIG.13). In some implementations, the distributed transmission information1722may be signaled by repurposing 4 reserved bits in the common information field1720(as shown inFIG.15). Still further, in some implementations, the distributed transmission information1722may be signaled by repurposing any number of reserved bits or U-SIG disregard and validate bits in a special user information field in the user information list1730(such as the special user information field1600ofFIG.16).

FIG.18shows a flowchart illustrating an example process1800for wireless communication that supports global CSD in distributed transmissions according to some implementations. In some other implementations, the process1800may be performed by a wireless communication device operating as or within a network node, such as one of the STAs104or504described above with reference toFIGS.1and5B, respectively.

In some implementations, the process1800begins in block1802with obtaining data for transmission in a PPDU. In block1804, the process1800proceeds with modulating the data on a number (M) of tones mapped to M noncontiguous subcarrier indices of a plurality of subcarrier indices spanning a wireless channel according to a distributed tone plan, where the M tones mapped to the M noncontiguous subcarrier indices represent a dRU assigned to the wireless communication device. In block1806, the process1800proceeds with obtaining a sequence of first values representing an STF of the PPDU based on a bandwidth associated with the wireless channel. In block1808, the process1800proceeds with mapping the data and the sequence of first values to one or more spatial streams.

In block1810, the process1800proceeds with applying one or more first CSDs to the sequence of first values mapped to the one or more spatial streams, respectively, based on the dRU assignment. In some aspects, the one or more first CSDs may be further applied to the data and an LTF of the PPDU mapped to the one or more spatial streams, respectively. In some other aspects, one or more second CSDs may be applied to the data and the LTF of the PPDU mapped to the one or more spatial streams, respectively, where the one or more second CSDs are different than the one or more first CSDs. In block1812, the process1800proceeds with transmitting the PPDU, including the sequence of first values mapped to the one or more spatial streams, over the wireless channel.

In some aspects, the one or more first CSDs may be generated as a function of an AID value assigned to the wireless communication device. In some other aspects, the one or more first CSDs may be obtained from a CSD table having a number (N) of entries each indicating a respective CSD associated with the distributed tone plan. In some implementations, N may be equal to 8 or 16.

In some aspects, the one or more first CSDs may be obtained by calculating a start index associated with the one or more first CSDs based on information assigned to the wireless communication device, where the start index points to one of the N entries of the CSD table. In some implementations, the information assigned to the wireless communication device may include at least one of an AID value, an RU assignment index associated with the dRU, or a start tone offset associated with the dRU. In some implementations, the start index may be calculated as a modulo operation of the information assigned to the wireless communication device and N.

In some other aspects, the one or more first CSDs may be obtained from a trigger frame soliciting the PPDU from the wireless communication device, where the trigger frame carries CSD information indicating a start index associated with the one or more first CSDs, and where the start index points to one of the N entries of the CSD table. In some implementations, the CSD information may be carried in a user information field associated with the wireless communication device.

In some aspects, the trigger frame may further carry distributed transmission information indicating that the data is to be transmitted according to the distributed tone plan and may carry dRU distribution bandwidth information indicating the bandwidth associated with the wireless channel. In some implementations, the distributed transmission information and the dRU distribution bandwidth information may be carried in a user information field associated with the wireless communication device. In some other implementations, the distributed transmission information may be carried in a common information field, or a special user information field immediately following the common information field, and the dRU distribution bandwidth information may be carried in a user information field associated with the wireless communication device.

FIG.19shows a flowchart illustrating an example process1900for wireless communication that supports global CSD in distributed transmissions according to some implementations. In some implementations, the process1900may be performed by a wireless communication device operating as or within an AP, such as one of the APs102or502described above with reference toFIGS.1and5A, respectively.

In some implementations, the process1900begins in block1902with transmitting a trigger frame soliciting a TB PPDU from one or more STAs, where the trigger frame carries first distributed transmission information indicating that a first data portion of the TB PPDU is to be transmitted according to a distributed tone plan and further carrying first dRU distribution bandwidth information indicating a bandwidth of a wireless channel allocated for the transmission of the first data portion. In block1904, the process1900proceeds with receiving the TB PPDU from the one or more STAs responsive to the trigger frame. In block1906, the process1900proceeds with recovering the first data portion of the TB PPDU from a number (M) of tones mapped to M noncontiguous subcarrier indices of a plurality of subcarrier indices spanning the wireless channel according to the distributed tone plan.

In some implementations, the first distributed transmission information and the first dRU distribution bandwidth information may be carried in a user information field associated with a first STA of the one or more STAs. In some other implementations, the first distributed transmission information may be carried in a common information field, or a special user information field immediately following the common information field, and the first dRU distribution bandwidth information may be carried in a user information field associated with a first STA of the one or more STAs.

In some implementations, the trigger frame may further carry second distributed transmission information indicating that a second data portion of the TB PPDU is to be transmitted according to the distributed tone plan and may carry second dRU distribution bandwidth information indicating that the bandwidth of the wireless channel is allocated for the transmission of the second data portion. In some implementations, the first data portion may be received on one or more first spatial streams and the second data portion may be received on one or more second spatial streams, where the TB PPDU further includes an STF carrying a sequence of first values that is received on each of the one or more first spatial streams and on each of the one or more second spatial streams.

In some aspects, the sequence of first values received on the one or more first spatial streams may be delayed by one or more first CSDs, respectively, and the sequence of first values received on the one or more second spatial streams may be delayed by one or more second CSDs, respectively. In some implementations, the trigger frame may further carry first CSD information indicating a first start index associated with the one or more first CSDs and may carry second CSD information indicating a second start index associated with the one or more second CSDs, where the first start index points to a first entry of a CSD table having a number (N) of entries each indicating a respective CSD associated with the distributed tone plan and where the second start index points to a second entry of the CSD table that is different than the first entry. In some implementations, N may be equal to 8 or 16. In some implementations, the first CSD information may be carried in a user information field associated with a first STA of the one or more STAs and the second CSD information may be carried in a user information field associated with a second STA of the one or more STAs.

In some implementations, the TB PPDU may further include an LTF carrying a sequence of second values that is received on each of the one or more first spatial streams and a sequence of third values that is received on each of the one or more second spatial streams, where the first data portion and the sequence of second values received on the one or more first spatial streams are delayed by the one or more first CSDs, respectively, and where the second data portion and the sequence of third values received on the one or more second spatial streams are delayed by the one or more second CSDs, respectively.

In some other implementations, the TB PPDU may further include an LTF carrying a sequence of second values that is received on each of the one or more first spatial streams and a sequence of third values that is received on each of the one or more second spatial streams, where the first data portion and the sequence of second values received on the one or more first spatial streams are delayed by one or more third CSDs, respectively, that are different than the one or more first CSDs, and where the second data portion and the sequence of third values received on the one or more second spatial streams are delayed by one or more fourth CSDs, respectively, that are different than the one or more second CSDs.

FIG.20shows a block diagram of an example wireless communication device2000according to some implementations. In some implementations, the wireless communication device2000is configured to perform the process1800described above with reference toFIG.18. The wireless communication device2000can be an example implementation of the wireless communication device400described above with reference toFIG.4. For example, the wireless communication device2000can be a chip, SoC, chipset, package or device that includes at least one processor and at least one modem (for example, a Wi-Fi (IEEE 802.11) modem or a cellular modem).

The wireless communication device2000includes a reception component2010, a communication manager2020, and a transmission component2030. The communication manager2020further includes a data acquisition component2021, a modulation component2022, an STF determination component2023, a spatial stream (SS) mapping component2024, and a CSD component2025. Portions of one or more of the components2021-2025may be implemented at least in part in hardware or firmware. In some implementations, at least some of the components2021,2022,2023,2024, or2025are implemented at least in part as software stored in a memory (such as the memory408). For example, portions of one or more of the components2021-2025can be implemented as non-transitory instructions (or “code”) executable by a processor (such as the processor406) to perform the functions or operations of the respective component.

The reception component2010is configured to receive RX signals, over a wireless channel, from one or more other wireless communication devices. The communication manager2020is configured to control or manage communications with one or more other wireless communication devices. In some implementations, the data acquisition component2021may obtain data for transmission in a PPDU; the modulation component2022may modulate the data on a number (M) of tones mapped to M noncontiguous subcarrier indices of a plurality of subcarrier indices spanning a wireless channel according to a distributed tone plan, where the M tones mapped to the M noncontiguous subcarrier indices represent a dRU assigned to the wireless communication device; the STF determination component2023may obtain a sequence of values representing an STF of the PPDU based on a bandwidth associated with the wireless channel; the SS mapping component2024may map the data and the sequence of values to one or more spatial streams; and the CSD component2025may apply one or more CSDs to the sequence of values mapped to the one or more spatial streams, respectively, based on the dRU assignment. The transmission component2030is configured to transmit TX signals, over a wireless channel, to one or more other wireless communication devices. In some implementations, the transmission component2030may transmit the PPDU, including the sequence of values mapped to the one or more spatial streams, over the wireless channel.

FIG.21shows a block diagram of an example wireless communication device2100according to some implementations. In some implementations, the wireless communication device2100is configured to perform the process1900described above with reference toFIG.19. The wireless communication device2100can be an example implementation of the wireless communication device400described above with reference toFIG.4. For example, the wireless communication device2100can be a chip, SoC, chipset, package or device that includes at least one processor and at least one modem (for example, a Wi-Fi (IEEE 802.11) modem or a cellular modem).

The wireless communication device2100includes a reception component2110, a communication manager2120, and a transmission component2130. The communication manager2120further includes a dRU demapping component2122. Portions of the dRU demapping component2122may be implemented at least in part in hardware or firmware. In some implementations, the dRU demapping component2122may be implemented at least in part as software stored in a memory (such as the memory408). For example, portions of the dRU demapping component2122can be implemented as non-transitory instructions (or “code”) executable by a processor (such as the processor406) to perform the functions or operations of the respective component.

The reception component2110is configured to receive RX signals, over a wireless channel, from one or more other wireless communication devices and the transmission component2130is configured to transmit TX signals, over the wireless channel, to one or more other wireless communication devices. In some implementations, the transmission component2130may transmit a trigger frame soliciting a TB PPDU from one or more STAs, where the trigger frame carries distributed transmission information indicating that a data portion of the TB PPDU is to be transmitted according to a distributed tone plan and further carries dRU distribution bandwidth information indicating a bandwidth of a wireless channel allocated for the transmission of the first data portion. In some implementations, the reception component2110may receive the TB PPDU from the one or more STAs responsive to the trigger frame. The communication manager2120is configured to control or manage communications with one or more other wireless communication devices. In some implementations, the dRU demapping component2122may recover the data portion of the TB PPDU from a number (M) of tones mapped to M noncontiguous subcarrier indices of a plurality of subcarrier indices spanning the wireless channel according to the distributed tone plan.

Implementation examples are described in the following numbered clauses:1. A method for wireless communication by a wireless communication device, including:obtaining data for transmission in a physical layer convergence protocol (PLCP) protocol data unit (PPDU);modulating the data on a number (M) of tones mapped to M noncontiguous subcarrier indices of a plurality of subcarrier indices spanning a wireless channel according to a distributed tone plan, the M tones mapped to the M noncontiguous subcarrier indices representing a distributed resource unit (dRU) assigned to the wireless communication device; andobtaining a sequence of first values representing a short training field (STF) of the PPDU based on a bandwidth associated with the wireless channel;mapping the data and the sequence of first values to one or more spatial streams;applying one or more first cyclic shift delays (CSDs) to the sequence of first values mapped to the one or more spatial streams, respectively, based on the dRU assignment; andtransmitting the PPDU, including the sequence of first values mapped to the one or more spatial streams, over the wireless channel2. The method of clause 1, further including:obtaining a sequence of second values representing a long training field (LTF) of the PPDU;mapping the sequence of second values to the one or more spatial streams; andapplying the one or more first CSDs to the data and the sequence of second values mapped to the one or more spatial streams, respectively.3. The method of clause 1, further including: obtaining a sequence of second values representing an LTF of the PPDU; mapping the sequence of second values to the one or more spatial streams; and applying one or more second CSDs to the data and the sequence of second values mapped to the one or more spatial streams, respectively, the one or more second CSDs being different than the one or more first CSDs.4. The method of any of clauses 1-3, further including:generating the one or more first CSDs as a function of an association identifier (AID) value assigned to the wireless communication device.5. The method of any of clauses 1-3, further including:

obtaining the one or more first CSDs from a CSD table having a number (N) of entries each indicating a respective CSD associated with the distributed tone plan.6. The method of any of clauses 1-3 or 5, where N is equal to 8 or 16.7. The method of any of clauses 1-3, 5, or 6, where the obtaining of the one or more first CSDs includes:calculating a start index associated with the one or more first CSDs based on information assigned to the wireless communication device, the start index pointing to one of the N entries of the CSD table.8. The method of any of clauses 1-3 or 5-7, where the information assigned to the wireless communication device includes at least one of an AID value, a resource unit (RU) assignment index associated with the dRU, or a start tone offset associated with the dRU.9. The method of any of clauses 1-3 or 5-8, where the start index is calculated as a modulo operation of the information assigned to the wireless communication device and N.10. The method of any of clauses 1-3, 5, or 6, further including:receiving a trigger frame soliciting the PPDU from the wireless communication device, the trigger frame carrying CSD information indicating a start index associated with the one or more first CSDs, the start index pointing to one of the N entries of the CSD table.11. The method of any of clauses 1-3, 5, 6, or 10, where the CSD information is carried in a user information field associated with the wireless communication device.12. The method of any of clauses 1-3, 5, 6, 10, or 11, where the trigger frame further carries distributed transmission information indicating that the data is to be transmitted according to the distributed tone plan and carries dRU distribution bandwidth information indicating the bandwidth associated with the wireless channel.13. The method of any of clauses 1-3, 5, 6, or 10-12, where the distributed transmission information and the dRU distribution bandwidth information are carried in a user information field associated with the wireless communication device.14. The method of any of clauses 1-3, 5, 6, or 10-12, where the distributed transmission information is carried in a common information field, or a special user information field immediately following the common information field, and the dRU distribution bandwidth information is carried in a user information field associated with the wireless communication device.15. A wireless communication device including:at least one processor; andat least one memory communicatively coupled with the at least one processor and storing processor-readable code that, when executed by the at least one processor, is configured to perform the method of any one or more of clauses 1-14.16. A method for wireless communication performed by a wireless communication device, including:

transmitting a trigger frame soliciting a trigger-based (TB) physical layer convergence protocol (PLCP) protocol data unit (PPDU) from one or more wireless stations (STAs), the trigger frame carrying first distributed transmission information indicating that a first data portion of the TB PPDU is to be transmitted according to a distributed tone plan and further carrying first distributed resource unit (dRU) distribution bandwidth information indicating a bandwidth of a wireless channel allocated for the transmission of the first data portion;

receiving the TB PPDU from the one or more STAs responsive to the trigger frame; andrecovering the first data portion of the TB PPDU from a number (M) of tones mapped to M noncontiguous subcarrier indices of a plurality of subcarrier indices spanning the wireless channel according to the distributed tone plan.17. The method of clause 16, where the first distributed transmission information and the first dRU distribution bandwidth information are carried in a user information field associated with a first STA of the one or more STAs.18. The method of clause 16, where the first distributed transmission information is carried in a common information field, or a special user information field immediately following the common information field, and the first dRU distribution bandwidth information is carried in a user information field associated with a first STA of the one or more STAs.19. The method of any of clauses 16-18, where the trigger frame further carries second distributed transmission information indicating that a second data portion of the TB PPDU is to be transmitted according to the distributed tone plan and carries second dRU distribution bandwidth information indicating that the bandwidth of the wireless channel is allocated for the transmission of the second data portion.20. The method of any of clauses 16-19, where the first data portion is received on one or more first spatial streams and the second data portion is received on one or more second spatial streams, the TB PPDU further including a short training field (STF) carrying a sequence of first values that is received on each of the one or more first spatial streams and on each of the one or more second spatial streams.

21. The method of any of clauses 16-20, where the sequence of first values received on the one or more first spatial streams is delayed by one or more first cyclic shift delays (CSDs), respectively, and the sequence of first values received on the one or more second spatial streams is delayed by one or more second CSDs, respectively.22. The method of any of clauses 16-21, where the trigger frame further carries first CSD information indicating a first start index associated with the one or more first CSDs and carries second CSD information indicating a second start index associated with the one or more second CSDs, the first start index pointing to a first entry of a CSD table having a number (N) of entries each indicating a respective CSD associated with the distributed tone plan and the second start index pointing to a second entry of the CSD table that is different than the first entry.23. The method of any of clauses 16-22, where N is equal to 8 or 16.24. The method of any of clauses 16-23, where the first CSD information is carried in a user information field associated with a first STA of the one or more STAs and the second CSD information is carried in a user information field associated with a second STA of the one or more STAs.25. The method of any of clauses 16-24, where the TB PPDU further includes a long training field (LTF) carrying a sequence of second values that is received on each of the one or more first spatial streams and a sequence of third values that is received on each of the one or more second spatial streams, the first data portion and the sequence of second values received on the one or more first spatial streams being delayed by the one or more first CSDs, respectively, and the second data portion and the sequence of third values received on the one or more second spatial streams being delayed by the one or more second CSDs, respectively.26. The method of any of clauses 16-24, where the TB PPDU further includes an LTF carrying a sequence of second values that is received on each of the one or more first spatial streams and a sequence of third values that is received on each of the one or more second spatial streams, the first data portion and the sequence of second values received on the one or more first spatial streams being delayed by one or more third CSDs, respectively, that are different than the one or more first CSDs, and the second data portion and the sequence of third values received on the one or more second spatial streams being delayed by one or more fourth CSDs, respectively, that are different than the one or more second CSDs.27. A wireless communication device including:at least one processor; andat least one memory communicatively coupled with the at least one processor and storing processor-readable code that, when executed by the at least one processor, is configured to perform the method of any one or more of clauses 16-26.

As used herein, a phrase referring to “at least one of” or “one or more of” a list of items refers to any combination of those items, including single members. For example, “at least one of: a, b, or c” is intended to cover the possibilities of: a only, b only, c only, a combination of a and b, a combination of a and c, a combination of b and c, and a combination of a and b and c.

The various illustrative components, logic, logical blocks, modules, circuits, operations and algorithm processes described in connection with the implementations disclosed herein may be implemented as electronic hardware, firmware, software, or combinations of hardware, firmware or software, including the structures disclosed in this specification and the structural equivalents thereof. The interchangeability of hardware, firmware and software has been described generally, in terms of functionality, and illustrated in the various illustrative components, blocks, modules, circuits and processes described above. Whether such functionality is implemented in hardware, firmware or software depends upon the particular application and design constraints imposed on the overall system.

Various modifications to the implementations described in this disclosure may be readily apparent to persons having ordinary skill in the art, and the generic principles defined herein may be applied to other implementations without departing from the spirit or scope of this disclosure. Thus, the claims are not intended to be limited to the implementations shown herein, but are to be accorded the widest scope consistent with this disclosure, the principles and the novel features disclosed herein.

Additionally, various features that are described in this specification in the context of separate implementations also can be implemented in combination in a single implementation. Conversely, various features that are described in the context of a single implementation also can be implemented in multiple implementations separately or in any suitable subcombination. As such, although features may be described above as acting in particular combinations, and even initially claimed as such, one or more features from a claimed combination can in some cases be excised from the combination, and the claimed combination may be directed to a subcombination or variation of a subcombination.

Similarly, while operations are depicted in the drawings in a particular order, this should not be understood as requiring that such operations be performed in the particular order shown or in sequential order, or that all illustrated operations be performed, to achieve desirable results. Further, the drawings may schematically depict one more example processes in the form of a flowchart or flow diagram. However, other operations that are not depicted can be incorporated in the example processes that are schematically illustrated. For example, one or more additional operations can be performed before, after, simultaneously, or between any of the illustrated operations. In some circumstances, multitasking and parallel processing may be advantageous. Moreover, the separation of various system components in the implementations described above should not be understood as requiring such separation in all implementations, and it should be understood that the described program components and systems can generally be integrated together in a single software product or packaged into multiple software products.