WO2024025339A1

WO2024025339A1 - Device and method for transmitting ppdu

Info

Publication number: WO2024025339A1
Application number: PCT/KR2023/010835
Authority: WO
Inventors: Jeong Soo Lee
Original assignee: Kstl
Priority date: 2022-07-27
Filing date: 2023-07-26
Publication date: 2024-02-01

Abstract

A device for transmitting a physical layer protocol data unit (PPDU) in a wireless local area network is provided. The device receives a request-to-send (RTS) frame from a station over a first frqeuncy segment. If a second frequency segment is idle, the device transmits a trigger frame to the staion over the second frequency segment. The trigger frame allows the station to transmit the station's PPDU in the second frequency segment.

Description

DEVICE AND METHOD FOR TRANSMITTING PPDU

The present disclosure relates to a wireless local area network (WLAN), and more particularly, to data unit transmission in the WLAN.

A wireless local area network (WLAN) may be formed by one or more access points (APs) that provide a shared wireless communication medium for use by a number of client devices also referred to as stations (STAs).

Orthogonal frequency division multiple access (OFDMA) is a multiple access scheme where different subsets of subcarriers are allocated to different users, and this scheme allows simultaneous data transmission to or from one or more users.

A physical layer protocol data unit (PPDU) is a data unit (or data packet) to carry various information in the WLAN. In OFDMA, users are allocated different subsets of subcarriers that can change from one PPDU to the next. Using OFDMA, an AP may allocate different RUs for STAs. The AP can simultaneously transmit various formats of PPDUs to multiple STAs.

This disclosure relates to how various formats of PPDUs are trasnmitted or received.

The present disclosure provides a method for transmitting a physical layer protocol data unit (PPDU) in a wireless local area network.

The present disclosure further provides a device for transmitting a PPDU in a wireless local area network.

In an aspect, a method for transmitting a physical layer protocol data unit (PPDU) in a wireless local area network is provided. The method includes receiving, by a second station, a request-to-send (RTS) frame from a first station over a first frqeuncy segment, checking, by the second sation, whether at least one of the first frequency segment and a second frequency segment is idle during a predefined time based on receiving the RTS frame, and, if the second frequency segment is idle, transmitting, by the second sation, a trigger frame to the first staion over the second frequency segment. The trigger frame allows the first station to transmit the first station's PPDU in the second frequency segment.

In anotehr aspect, a device for a wireless local area network (WLAN) is provided. The device includes a processor, and a memory operatively coupled with the processor and configured to store instructions that, when executed by the processor, cause the device to perform functions. The functions includes receiving a request-to-send (RTS) frame from a first station over a first frqeuncy segment, checking whether at least one of the first frequency segment and a second frequency segment is idle during a predefined time based on receiving the RTS frame, and, if the second frequency segment is idle, transmitting a trigger frame to the first staion over the second frequency segment. The trigger frame allows the first station to transmit the first station's PPDU in the second frequency segment.

As new WLAN communication protocols enable enhanced features, new PPDU trasnmssion designs are provided to support signaling regarding features and resource allocations.

FIG. 1 shows a block diagram of an example wireless communication network.

FIG. 2 shows a block diagram of an example wireless communication device.

FIGs. 3 and 4 show various examples of PPDUs usable for wireless communication between an AP and a number of STAs.

FIG. 5 shows an example of wireless channel that includes multiple subchannels.

FIG. 6 shows an example of PPDU transmission.

FIG. 7 shows an example of UL MU transmission.

FIG. 8 shows an example of DL PPDU transmission.

FIG. 9 shows another example of DL PPDU transmission.

FIG. 10 shows an example of UL PPDU transmission.

FIG. 11 shows another example of UL PPDU transmission.

FIG. 12 shows an example of PPDU phase rotation.

FIG. 13 shows an example of intra-PPDU phase rotation.

FIG. 14 shows an example of intra/inter-PPDU phase rotation.

FIG. 15 shows an example of DL MU transmission for NAV setting using an aggregated PPDU.

FIG. 16 show a frame format for NDP Announcement frame.

FIG. 17 shows an example of HE Sounding NDP format.

FIG. 18 shows a example of EHT Sounding NDP format.

FIG. 19 shows an example of OFDMA Aggregated PPDU Sounding Operation.

FIG. 20 shows another example of OFDMA Aggregated PPDU Sounding Operation.

FIG. 21 show an example for setting dialog token for Sounding PPDUs.

FIG. 22 show another example for setting dialog token for Sounding PPDUs.

FIG. 23 shows another example of OFDMA Aggregated PPDU Sounding Operation.

FIG. 24 shows an example of Ack Policy in DL OFDMA Aggregated PPDU.

FIG. 25 shows another example of Ack Policy in DL OFDMA Aggregated PPDU.

FIG. 26 shows an example of UL Length in UL OFDMA Aggregated PPDU.

FIG. 27 shows another example of UL Length in UL OFDMA Aggregated PPDU.

FIG. 28 shows an example of STA initiated OFDMA Aggregated PPDU.

FIG. 29 shows another example of STA initiated OFDMA Aggregated PPDU.

FIG. 30 shows still another example of STA initiated OFDMA Aggregated PPDU.

FIG. 31 shows still another example of STA initiated OFDMA Aggregated PPDU.

FIG. 32 shows still another example of STA initiated OFDMA Aggregated PPDU.

FIG. 33 shows an example of STA initiated OFDMA Aggregated PPDU using RTS and CTS.

FIG. 34 shows an example of STA initiated OFDMA Aggregated PPDU using direct link.

FIG. 35 shows an example of STA initiated OFDMA Aggregated PPDU to align the OFDMA symbol boundaries.

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.

OFDMA is an OFDM-based multiple access scheme where different subsets of subcarriers are allocated to different users, and this scheme allows simultaneous data transmission to or from one or more users. In OFDMA, users are allocated different subsets of subcarriers that can change from one PPDU to the next. Similar to OFDM, OFDMA employs multiple subcarriers, but the subcarriers are divided into several groups where each group is referred to as a resource unit (RU).

A physical layer protocol data unit (PPDU) may span one or more subchannels and may include a preamble portion and a data portion. Signaling refers to control fields or information in the preamble portion that can be used by a wireless communication device to interpret another field or portion of the preamble portion or the data portion of the PPDU. A wireless channel may be formed from multiple subchannels. A subchannel may include a set of subcarriers. Portions of the wireless channel bandwidth can be divided or grouped to form different resource units (RUs). An RU may be a unit for resource allocation and may include one or more subcarriers. Among other things, a preamble portion of a PPDU may include signaling to indicate which RUs are allocated to different devices. Other types of signaling include indicators regarding which subchannels include further signaling or which subchannels may be punctured. There are several formats of PPDUs (and related structures) defined for current wireless communication protocols. As new wireless communication protocols enable enhanced features, new preamble designs are needed support signaling regarding features and resource allocations. Furthermore, it desirable to define a new preamble signaling protocol that can support future wireless communication protocols.

FIG. 1 shows a block diagram of an example wireless communication network.

According to some aspects, the wireless communication network 10 can be an example of a wireless local area network (WLAN) such as a Wi-Fi network (and will hereinafter be referred to as WLAN 10). For example, the WLAN 10 can 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 802.11-2016 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 WLAN 10 may include numerous wireless communication devices such as an access point (AP) 11 and multiple stations (STAs) 12. While only one AP 11 is shown, the WLAN network 10 also can include multiple APs.

Each of the STAs 12 also 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 STAs 12 may 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 AP 11 and an associated set of STAs 12 may be referred to as a basic service set (BSS), which is managed by the respective AP 11. 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 AP 11. The AP 11 periodically broadcasts beacon frames (“beacons”) including the BSSID to enable any STAs 12 within wireless range of the AP 11 to “associate” or re-associate with the AP 11 to establish a respective communication link (hereinafter also referred to as a “Wi-Fi link”), or to maintain a communication link, with the AP 11. For example, the beacons can include an identification of a primary channel used by the respective AP 11 as well as a timing synchronization function for establishing or maintaining timing synchronization with the AP 11. The AP 11 may provide access to external networks to various STAs 12 in the WLAN via respective communication link.

To establish a communication link with an AP 11, each of the STAs 12 is 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 STA 12 listens for beacons, which are transmitted by respective APs 11 at 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 STA 12 generates and sequentially transmits probe requests on each channel to be scanned and listens for probe responses from APs 11. Each STA 12 may be configured to identify or select an AP 11 with 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 link with the selected AP 11. The AP 11 assigns an association identifier (AID) to the STA 12 at the culmination of the association operations, which the AP 11 uses to track the STA 104.

In some cases, STAs 12 may form networks without APs 11 or other equipment other than the STA. 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 WLAN 10. In such implementations, while the STAs 12 may be capable of communicating with each other through the AP 11 using communication links, STAs 12 also can communicate directly with each other via direct wireless links. Additionally, two STAs 12 may communicate via a direct communication link regardless of whether both STAs 12 are associated with and served by the same AP 11. In such an ad hoc system, one or more of the STAs 12 may assume the role filled by the AP 11 in a BSS. Such a STA may be referred to as a group owner (GO) and may coordinate transmissions within the ad hoc network.

The AP 11 and STAs 12 may function and communicate (via the respective communication links) 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 AP 11 and STAs 12 transmit and receive wireless communications (hereinafter also referred to as “Wi-Fi communications”) to and from one another in the form of PPDUs. The AP 11 and STAs 12 in the WLAN 10 may 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 900 MHz band. Some implementations of the AP 11 and STAs 12 described herein also may communicate in other frequency bands, such as the 6 GHz band, which may support both licensed and unlicensed communications. The AP 11 and STAs 12 also 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 channels (which may be used as subchannels of a larger bandwidth channel). For example, PPDUs conforming to the IEEE 802.11n, 802.11ac and 802.11ax standard may be transmitted over the 2.4 and 5 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 (which may be referred to as subchannels).

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 first portion (or “legacy preamble”) and a second portion (or “non-legacy preamble”). The first portion may be used for packet detection, automatic gain control and channel estimation, among other uses. The first portion also may generally be used to maintain compatibility with legacy devices as well as non-legacy devices. The format of, coding of, and information provided in the second portion of the preamble is based on the particular IEEE 802.11 protocol to be used to transmit the payload.

Uplink (UL) means that the signal (or message or PPDU) is transmitted by a STA to an AP, and downlink (DL) means that the signal (or message or PPDU) is transmitted by the AP to one or more STAs.

FIG. 2 shows a block diagram of an example wireless communication device.

In some implementations, the wireless communication device 50 can be an example of a device for use in a STA such as one of the STAs 12 described above with reference to FIG. 1. In some implementations, the wireless communication device 50 can be an example of a device for use in an AP such as the AP 11 described above with reference to FIG. 1. The wireless communication device 50 is 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 PPDUs and/or 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 device 800 can be, or can include, a chip, system on chip (SoC), chipset, package or device that includes one or more processor 51. The processor 51 can 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 processor 51 processes information received through a transceiver 53, and processes information to be output through the transceiver 53 through the wireless medium. For example, the processor 806 may implement a physical (PHY) layer and/or a MAC layer configured to perform various operations related to the generation and transmission of PPDUs, MPDUs, frames or packets.

A memory 52 can include tangible storage media such as random-access memory (RAM) or read-only memory (ROM), or combinations thereof. The memory 808 also can store non-transitory processor- or computer-executable software code containing instructions that, when executed by the processor 51, cause the wireless communication device 50 to perform various operations described herein for wireless communication, including the generation, transmission, reception and interpretation of PPDUs, 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.

The transceiver 53 generally includes at least one radio frequency (RF) transmitter (or “transmitter chain”) for transmitting radio signals and at least one RF receiver (or “receiver chain”) for receiving radio signals. 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 device 50 can include, or be coupled with, multiple transmit antennas (each with a corresponding transmit chain) and multiple receive antennas (each with a corresponding receive chain).

An PPDU may include a preamble portion and a data portion. ‘Data’ of FIGs. 3-4 denotes the data portion which includes one or more PSDUs and appears after the preamble portion. The data portion may be referred to as a payload.

A non-high-throughput (non-HT) PPDU supporting IEEE 802.11a/g includes a Legacy-Short Training Field (L-STF), a Legacy-Long Training Field (L-LTF), a Legacy-Signal (L-SIG) and a data portion. L-SIG may be called as non-HT Signal. A high-throughput (HT) PPDU supporting IEEE 802.11n includes an L-STF, a HT-SIG, a HT-STF, a HT-LTF and a data portion. A very high throughput (VHT) PPDU supporting IEEE 802.11ac includes an L-STF, L-SIG, a VHT-SIG-A, a VHT-STF, a VHT-LTF, a VHT-SIG-B and a data portion.

A high-efficiency (HE) PPDU supporting IEEE 802.11ax may include an HE single-user (SU) PPDU for SU transmission and an HE multi-user (MU) PPDU for MU transmission. An extremely high throughput (EHT) PPDU supporting IEEE 802.11be may include an EHT MU PPDU for MU transmission and an EHT trigger based (TB) PPDU.

The preamble portion of a PPDU may include a first portion (or "legacy preamble") and a second portion (or “non-legacy preamble”). The first portion may include L-STF, L-LTF and L-SIG. The second portion may include at least one of HT-SIG, HT-STF, HT-LTF, VHT-SIG-A, VHT-STF, VHT-LTF, VHT-SIG-B, RL-SIG, HE-SIG-A, HE-STF, HE-LTF, HE-SIG-B, EHT-SIG, EHT-STF, EHT-LTF and U-SIG.

The L-STF may be used for frame detection, Automatic Gain Control (AGC), diversity detection, and coarse frequency/time synchronization. The L-LTF may be used for fine frequency/time synchronization and channel estimation. The L-SIG may include information indicating a total length of a corresponding PPDU (or information indicating a transmission time of a PSDU).

The VHT-SIG-A field carries information required to interpret VHT PPDUs. The VHT-STF field is used to improve automatic gain control estimation in a MIMO. The VHT-LTF field provides a means for the receiver to estimate the MIMO channel between the set of constellation mapper outputs and the receive chains. The VHT-SIG-B field may be used for MU transmissions and may contain as signaling information usable by the STAs to decode data received in the DATA field, including, for example, a modulation and coding scheme (MCS) and beamforming information.

The repeated legacy (RL)-SIG field in the HE PPDU and EHT PPDU is a repeat of the L-SIG field and is used to differentiate the HE PPDU and the EHT PPDU from non-HT PPDU, HT PPDU, and VHT PPDU.

HE-SIG-A carries information necessary to interpret HE PPDUs. HE-SIG-A may indicate locations and lengths of HE-SIG-Bs, available channel bandwidths, etc. HE-SIG-B may carry STA-specific scheduling information such as, for example, per-user MCS values and per-user RU allocation information. In the context of DL MU-OFDMA, such information enables the respective STA to identify and decode corresponding RUs in the associated data field.

VHT-STF, HE-STF or EHT-STF may be used to improve an AGC estimation in a MIMO transmission. VHT-LTF, HE-LTF or EHT-LTF may be used to estimate a MIMO channel.

The universal signal field (U-SIG) field of EHT PPDU carries information necessary to interpret EHT PPDUs. The U-SIG may include version independent fields and version dependent fields. The version independent fields may include at least one of a version identifier, a PPDU bandwidth, an indication of whether the PPDU is a UL or a DL PPDU, a BSS color identifying a BSS, and a transmission opportunity (TXOP). The PPDU bandwidth in the version independent fields indicates a transmission bandwidth of the PPDU, for example, 20 MHz, 40 MHz, 80 MHz, 160 MHz or 320 MHz. The version identifier in the version independent fields may indicate a version (and associated format) for the version dependent fields. A PPDU format may determine which other indicators are included in the version dependent fields as well as the version identifier. In some implementations, if the PPDU format indicates that the PPDU is an EHT TB PPDU, then the EHT-SIG may be omitted as shown in EHT TB PPDU of FIG. 4. The version dependent fields of U-SIG may include punctured channel Information and EHT-SIG MCS. The EHT-SIG MCS may Indicate an MCS used for modulating the EHT-SIG. The PPDU bandwidth and the punctured channel information may be referred to collectively as frequency occupation indications. The frequency occupation indications may permit WLAN devices on the wireless channel to determine the utilization of the various parts of the wireless channel. For example, the frequency occupation information may be used to indicate puncturing of some subchannels.

The EHT-SIG field provides additional signaling to the U-SIG field for STAs to interpret an EHT MU PPDU. The EHT-SIG may carry STA-specific scheduling information such as, for example, per-user MCS values and per-user RU allocation information. EHT-SIG includes a common field and at least one STA-specific field ("user specific field”). The common field can indicate RU distributions to multiple STAs, indicate the RU assignments in the frequency domain, indicate which RUs are allocated for MU-MIMO transmissions and which RUs correspond to MU-OFDMA transmissions, and the number of users in allocations. The user specific fields are assigned to particular STAs 104 and may be used to schedule specific RUs and to indicate the scheduling to other WLAN devices.

The EHT-SIG field of a 20 MHz EHT MU PPDU contains one EHT-SIG content channel. For OFDMA transmission and for non-OFDMA transmission to multiple users, the EHT-SIG field of an EHT MU PPDU that is 40 MHz or 80 MHz contains two EHT-SIG content channels. For OFDMA transmission and for non-OFDMA transmission to multiple users, the EHT-SIG field of an MU PPDU that is 160 MHz or wider contains two EHT-SIG content channels per 80 MHz. The EHT-SIG content channels per 80 MHz are allowed to carry different information when EHT MU PPDU bandwidth for OFDMA transmission is wider than 80 MHz. The EHT-SIG field of an EHT MU PPDU sent to a single user and the EHT-SIG field of an EHT sounding NDP contains one EHT-SIG content channel and it is duplicated in each non-punctured 20 MHz when the EHT PPDU is equal to or wider than 40 MHz

For OFDMA transmission, the Common field of an EHT-SIG content channel contains information regarding the resource unit allocation such as the RU assignment to be used in the EHT modulated fields of the PPDU, the RUs allocated for MU-MIMO and the number of users in MU-MIMO allocations. In non-OFDMA transmission, the Common field of the EHT-SIG content channel does not contain the RU allocation.

The User Specific fields in the EHT-SIG content channels contains information for all users in the PPDU on how to decode their payload.

A device receiving an PPDU may initially begin or continue its determination of the wireless communication protocol version used to transmit the PPD based on the presence of RL-SIG and the modulation scheme used to modulate the symbols in U-SIG (or HE-SIG-A). In some implementations, the receiving device may initially determine that the wireless communication protocol used to transmit the PPDU is an HE or later version based on the presence of RL-SIG (that is, a determination that the first symbol of the second portion of the preamble is identical to L-SIG) and a determination that both the first symbol and the second symbol following RL-SIG are modulated according to a BPSK modulation scheme.

The techniques in this description are not limited to PPDU formats shown in FIGs. 3-4, but the concepts may apply to any PPDU conforming to IEEE 802.11 wireless communication protocol version.

FIG. 5 shows an example of wireless channel that includes multiple subchannels.

A channel map for a frequency band (such as the 2.5 GHz, 5 GHz, 6 GHz frequency band, etc.) may define multiple subchannels. Each subchannel may have a uniform channel width W=20 MHz, but the techniques in this description are not limited to 20 MHz. The channel width W may be smaller than or larger than 20 MHz.

Some WLAN devices are capable of transmitting at higher bandwidths using a wireless channel that is made up of multiple subchannels. When WLAN devices is capable of transmitting at BSS operating channel width is 80 MHz, a group of four subchannels (a primary 20 MHz channel, a secondary 20 MHz channel and a secondary 40 MHz channel) are used. In FIG. 5, BSS operating channel has a bandwidth of 20 MHz, 40 MHz, 80 MHz and 160 MHz. Although depicted as contiguous subchannels in the channel map, in some implementations, the BSS operating channel may contain one or more subchannel which are not adjacent in the channel map. Additionally, larger groups of channels may be used in some implementations. For example, operating channel has a bandwidth of 320 MHz, 640- MHz or larger. The 320 MHz bandwidth may be divided into sixteen 20 MHz subchannels.

FIG. 6 shows an example of PPDU transmission.

A WLAN device transmits a PPDU by using a four subchannels CH1, CH2, CH3 and CH4 of 80 MHz operating channel. The PPDU may have any PDDU format shown in FIGs. 3-4. A preamble and data in the PPDU may be duplicated every 20 MHz subchannel. Or only a part of the preamble in the PPDU may be duplicated every 20 MHz subchannel.

The WLAN device would perform a clear channel assessment (CCA) before sending a non-triggered transmission. The CCA is a type of collision avoidance technique. Other types may be referred to as carrier sense, carrier detect, listen-before-talk. CCA is performed by a WLAN device to determine if the wireless communication medium (such as the group of subchannels) is available or busy (by another transmission). If the wireless communication medium is in use, the WLAN device may postpone the transmission until the CCA is performed again and the wireless communication medium is idle by another device.

There may be an incumbent system transmission that occupies part of the second subchannel CH2. Therefore, the wireless channel may be punctured to exclude the second subchannel CH2 from the transmission. Thus, the PPDU is sent only on the first subchannel CH1, the third subchannel CH3 and the fourth subchannel CH4.

The punctured channel information may be indicated in a signal field (for example, HE-SIG-A, U-SIG, or EHT-SIG). The punctured channel information may indicate which channels in the total bandwidth (such as 160 MHz or 320 MHz ) are punctured, as well as the puncturing mode, such that the receiving STA knows which channels to process for information and which channels are punctured and thus not available or otherwise not including information for processing by the STA .

FIG. 7 shows an example of UL MU transmission.

UL MU operation allows an AP to solicit simultaneous immediate response frames from one or more STAs.

The AP may send a trigger frame to one or more STAs (for example, STA1 and STA2). The trigger frame may be sent as MU PPDU (for example, HE MU PPDU or EHT MU PPDU). The STA1 and STA2 may send response PDUs (for example, HE TB PPDU or EHT TB PPDU) in response to the trigger frame. The interframe space between a PPDU that contains a triggering frame and the TB PPDU is a Short Interframe Space (SIFS). The AP sends an Ack or BlockAck frame acknowledging the one ore more TB PPDUs to the response STAs (for example, STA1 and STA2).

The trigger frame allocates resources for and solicits one or more PPDU transmissions. The trigger frame also carries other information required by the responding STA to send a TB PPDU or a non-HT PPDU. The trigger frame may be sent as various types such as a basic trigger frame, MU-RTS frame, MU-BAR, etc.

The trigger frame may include a UL bandwidth field, an CS required field, one or more STA IDs and one or more RU Allocation field. The UL bandwidth field indicates the bandwidth of the response PPDU. The CS required field indicate whether the response STAs are required to use energy detection (ED) to sense the medium and to consider the medium state and the NAV in determining whether or not to respond. The one or more STA IDs identifies the one or more response STAs. The RU Allocation subfield indicates RU allocation for the response PPDU.

Hereinafter, Aggregated-PPDU (A-PPDU) is described.

Using OFDMA, a first WLAN device (such as an AP) may allocate different RUs for second WLAN devices. A transmitting WLAN device can simultaneously transmit various formats of PPDUs to multiple receiving WLAN devices.

FIG. 8 shows an example of DL PPDU transmission.

An AP aggregates two PPDUs of different formats (e.g., HE PPDU and EHT PPDU) in an OFDMA manner and simultaneously transmits to two STAs. Each PPDU is transmitted by using 80 MHz channel width but not limited to. “sub-PPDU” may refer to a PPDU in the aggregated PPDU. In FIG. 8, HE PPDU and EHT PPDU are sub-PPDUs.

L-SIG in the HE PPDU and EHT PPDU includes a LENGTH field to indicate a length of the corresponding PPDU.

The LENGTH field in L-SIG of HE PPDU is set to the value given by the Equation (1).

where TXTIME indicates the time required to transmit the PPDU (in μs), m is 1 for an HE MU PPDU and HE ER SU PPDU and 2 otherwise, SignalExtension is 0 μs or 6 μs.

The LENGTH field in L-SIG of HE PPDU is set to the value given by the Equation (2).

Values of the LENGTH fields in L-SIGs of two PPDUs may be different. In order to align the ending time of two PPDUs, it is proposed that

of two PPDUs are the same.

, where LENGTH1 denotes a value of length field in HE PPDU, and LENGTH2 denotes a value of length field in EHT PPDU.

FIG. 9 shows another example of DL PPDU transmission.

An AP can aggregate two PPDUs of same formats (e.g., HE PPDU or EHT PPDU) in an OFDMA manner and simultaneously transmit to the same STA. Values of the LENGTH fields in L-SIGs of two PPDUs shall be the same.

FIG. 10 shows an example of UL PPDU transmission.

An AP may solicit two PPDUs of different formats (e.g., HE PPDU and EHT PPDU) in an OFDMA manner from two STAs of different types. Two STAs can simultaneously transmits to HE PPDU and EHT PPDU, respectively. Each PPDU is transmitted by using 80 MHz channel width but not limited to.

of two PPDUs are the same.

FIG. 11 shows another example of UL PPDU transmission.

An AP can solicit two PPDUs of same formats (e.g., HE PPDU or EHT PPDU) in an OFDMA manner from a single STA. Values of LENGTH fields in L-SIGs of two PPDUs shall be the same.

The single STA can aggregate two PPDUs of same formats (e.g., HE PPDU or EHT PPDU) in an OFDMA manner and simultaneously transmit to the AP. Values of the LENGTH fields in L-SIGs of two PPDUs shall be the same.

In DL/UL OFDMA transmission, other PHY parameters (e.g., GI duration and LTF size (1x LTF, 2x LTF, 4x LTF), number of LTF symbols) shall be the same in order to align the OFDMA symbol boundary of each of aggregated PPDUs. But, other MAC related information (e.g., TXOP) carried in the preamble of each of aggregated PPDUs can be same or different.

The TXOP value indicate the closest minimum bound on the duration information for network allocation vector (NAV) setting and protection of the TXOP. NAV is an indicator, maintained by each STA, of time periods when transmission onto the wireless medium (WM) is not initiated by the STA regardless of whether the STA’s CCA function senses that the WM is busy.

If the TXOP values of two PPDUs are not the same, the TXOP value carried in the PHY header (i.e. preamble) of the PPDU sent on the Secondary 80MHz (or 160MHz) Frequency Segment shall be less than or equal to the TXOP value carried in the PHY header of the PPDU sent on the Primary 80MHz (or 160MHz) Frequency Segment.

FIG. 12 shows an example of PPDU phase rotation.

When an WLAN device (Ap or STA) aggregates two 160 MHz PPDUs on 320 MHz channel, in order to reduce Peak-to-Average Power Ratio (PAPR), the WLAN device can apply the phase rotation to the preamble of the two PPDUs (called as ‘Inter-PPDU phase rotation’).

In HE PPDU (i.e., HE SU PPDU, HE ER SU PPDU, HE TB PPDU, HE MU PPDU), the pre-HE modulated fields may include at least one of L-STF, L-LTF, L-SIG, RL-SIG, HE-SIG-A, HE-SIG-B. The HE modulated fields in the preamble for all HE PPDU formats includes HE-STF and HE-LTF. The HE modulated fields in HE PPDU may further include data field.

In EHT PPDU, the pre-EHT modulated fields may include at least one of L-STF, L-LTF, L-SIG, RL-SIG, U-SIG, and EHT-SIG field. The EHT modulated fields in the preamble for EHT PPDU may include EHT-STF and EHT-LTF. The EHT modulated fields in EHT PPDU may further include data field.

The pre-HE modulated fields or pre-EHT modulated fields may be called as a first part of the preamble, and the HE modulated fields or EHT modulated fields may be called as a second part of the preamble.

When a plurality of PPDUs are transmitted as an aggregated PPDU, each PPDU may be phase-rotated by multiplying +1 or -1 over its transmission bandwidth. Alternatively, each PPDU may be phase-rotated by multiplying one of +1, -1, +j and -j over its transmission bandwidth. The transmission bandwidth is an entire bandwidth at which a single PPDU is transmitted. In FIG. 11, two PPDUs are transmitted at each 160 MHz transmission bandwidth, one PPDU is phase-rotated by multiplying -1, and the other PPDU is phase-rotated by multiplying +1.

When the WLAN device applies the phase rotation to each PPDU in the OFDMA Aggregated PPDU (Inter-PPDU phase rotation), the phase rotation to the subchannel within the PPDU may also be applied together (called as 'Intra-PPDU phase rotation').

FIG. 13 shows an example of intra-PPDU phase rotation.

An aggregated PPDU includes an EHT PPDU and a HE PPDU. The EHT PPDU's transmission channel has a transmission bandwidth of 160 MHz and the HE PPDU's transmission channel has a transmission bandwidth of 160 MHz. The transmission bandwidth may be 40 MHz, 80 MHz, 160 MHz, 320 MHz, or larger. The transmission channel is divided into a plurality of subchannel. The bandwidth of a subchannel may be 20 MHz, but it is not limited to. Since transmission bandwidth is 160 MHz, the transmission channel is divided into 8 subchannels (CH1, CH2, CH3, CH4, CH5, CH6. CH7, CH8)

According to intra-PPDU phase rotation, each PPDU is phase-rotated by multiplying one of +1, -1, +j and -j to each subchannel of the transmission channel. For example, for 160 MHz transmission, the pre-HE modulated fields and the pre-EHT modulated fields are phase-rotated by multiplying { +1, -1, -1, -1, +1, -1, -1, -1 } to subchannels { CH1, CH2, CH3, CH4, CH5, CH6, CH7, CH8 }, and the HE modulated fields and the EHT modulated fields are phase-rotated by multiplying { +1, +1, +1, +1. +1, +1, +1, +1 } to subchannels { CH1, CH2, CH3, CH4, CH5, CH6. CH7, CH8 }. For 80 MHz transmission, the pre-HE modulated fields and the pre-EHT modulated fields are phase-rotated by multiplying { +1, -1, -1, -1 } to subchannels { CH1, CH2, CH3, CH4 }, and the HE modulated fields and the EHT modulated fields are phase-rotated by multiplying { +1, +1, +1, +1 } to subchannels { CH1, CH2, CH3, CH4 }. For 40 MHz transmission, the pre-HE modulated fields and the pre-EHT modulated fields are phase-rotated by multiplying { +1, +j } to subchannels { CH1, CH2 }, and the HE modulated fields and the EHT modulated fields are phase-rotated by multiplying { +1, +1 } to subchannels { CH1, CH2 }.

FIG. 14 shows an example of intra/inter-PPDU phase rotation.

According to inter-PPDU phase rotation, each PPDU may be phase-rotated by multiplying one of +1, -1, +j and -j to the transmission channel. In the example of FIG. 14, EHT PPDU with intra-PPDU phase rotation is further phase rotated by multiplying -1 to its transmission channel, and HE PPDU with inter-PPDU phase rotation is further phase rotated by multiplying +1 to its transmission channel

There is no limit to the order of phase rotations. Inter-PPDU phase rotation may performed after intra-PPDU phase rotation, or Intra-PPDU phase rotation may performed after inter-PPDU phase rotation, or both Intra-PPDU phase rotation and inter-PPDU phase rotation may performed simultaneously.

According to inter/intra-PPDU phase rotation, each PPDU in the aggregated PPDU may be phase-rotated two times. First, each PPDU is phase-rotated multiplying one of +1, -1, +j and -j (or, one of +1 and -1) to a subchannel. Second, each PPDU is phase-rotated multiplying one of +1, -1, +j and -j (or, one of +1 and -1) to a transmission channel including a plurality of subchannels.

According to inter/intra-PPDU phase rotation, each PPDU in the aggregated PPDU may be phase-rotated over two types of bandwidth. First, each PPDU is phase-rotated multiplying one of +1, -1, +j and -j (or, one of +1 and -1) over a first bandwidth. Second, each PPDU is phase-rotated multiplying one of +1, -1, +j and -j (or, one of +1 and -1) over a second bandwidth wider than the first bandwidth.

Before transmitting an OFDMA Aggregated PPDU, an AP signals STAs to which an OFDMA Aggregated PPDU will be destined. On this purpose, the User Info field in the MU-RTS frame contains the AID of the STA to which a sub-PPDU of an OFDMA Aggregated PPDU will be destined and the sub-PPDU operating channel on which the corresponding sub-PPDU will be allocated.

Then, the corresponding STA switches its operating channel to the sub-PPDU operation channel specified in the User Info field in the multi-user request-to-send (MU-RTS) frame. After switching its operating channel, it replies with a cleasr-to-send (CTS) frame on the switched sub-PPDU operating channel.

During the TXOP, after being determined that the AP will not transmit an OFDMA Aggregated PPDU having a sub-PPDU allocated to the corresponding STA, it switches back to the primary channel.

The NAV on the Secondary 80MHz (or 160MHz) Frequency Segment can be different with the NAV on the Primary 80MHz (or 160MHz) Frequency Segment.

Frames sent from an AP/STA on the different frequency segments may have a different Duration field value.

Hereinafter, sounding using Aggregated PPDU is descibed.

Transmit beamforming and DL MU-MIMO require knowledge of the channel state to compute a steering matrix that is applied to the transmit signal to optimize reception at one or more receivers. STAs use the sounding protocol to determine the channel state information. The sounding protocol provides explicit feedback mechanisms, where the beamformee measures the channel using a training signal (i.e., a sounding Null data PPDU(NDP)) transmitted by the beamformer and sends back a transformed estimate of the channel state. The beamformer uses this estimate to derive the steering matrix.

FIG. 16 show a frame format for NDP Announcement frame.

A Duration field indicates a duration of NDP Announcement (NDPA) frame. The NDPA frame contains at least one STA Info field. A STA info field includes at least one STA ID. If the NDPA frame contains only one STA Info field, then the receiver address (RA) field is set to the address of the STA that can provide feedback. If the NDPA frame contains more than one STA Info field, then the RA field is set to the broadcast address. The transmitter address (TA) field is set to the address of the STA transmitting the NDPA frame.

The Sounding Dialog Token field includes a NDPA type subfield and Sounding Dialog Token Number subfield. The NDPA type subfield indicates the type of the NDPA frame such as VHT, HE or EHT. When the NDPA type subfield indicates HE, the NDPA frame may be called as HE NDAP frame. The Sounding Dialog Token Number subfield contains a value (“dialog token”) selected by the beamformer to identify the NDPA frame.

FIG. 17 shows an example of HE Sounding NDP format.

The HE sounding NDP is a variant of the HE SU PPDU. The HE sounding NDP uses the HE SU PPDU format but without the Data field, and has a PE field that is 4 μs in duration. The transmission bandwidth of the HE Sounding NDP is set to the same value as the transmission bandwidth of the preceding HE NDPA frame.

FIG. 18 shows a example of EHT Sounding NDP format.

The EHT sounding NDP is an EHT MU PPDU with a single EHT-SIG symbol encoded using EHT-MCS 0 and no Data field. The EHT-SIG field only contains a Common field and no User Specific field. The transmission bandwidth of the EHT Sounding NDP is set to the same value as the transmission bandwidth of the preceding EHT NDPA frame

A sounding sequence may be initiated by a beamformer with an individually addressed NDPA frame comprising exactly one STA Info field, followed after SIFS by a sounding NDP. The beamformee responds after SIFS with a Compressed Beamforming/CQI frame.

A sounding sequence may be initiated by a beamformer with a broadcast NDPA frame with two or more STA Info fields, followed after a SIFS by a sounding NDP, followed after a SIFS by a Beamforming Report Poll (BFRP) Trigger frame. The BFRP Trigger frame is a Trigger frame soliciting feedback. Each beamformee responds after a SIFS with a Compressed Beamforming/CQI frame.

A beamformee that receives an NDPA frame as part of a sounding sequence soliciting SU or MU feedback may generate a compressed beamforming/CQI report using the feedback type, codebook size, etc. If the beamformee then receives a BFRP Trigger frame with a matching STA Info field, the beamformee transmits a TB PPDU containing the compressed beamforming/CQI report.

FIG. 19 shows an example of OFDMA Aggregated PPDU Sounding Operation.

An AP sends MU-RTS to EHT STA and HE STA. EHT STA sends a CTS in response to the MU-RTS, and HE STA also sends a CTS in response to the MU-RTS.

As the PPDU formats of HE Sounding NDP and EHT Sounding NDP are not identical, HE Sounding NDP and EHT Sounding NDP cannot be aggregated as an OFDMA Aggregated PPDU.

An AP sends HE Sounding PPDUs (HE NDPA frame and HE Sounding NDP and EHT Sounding PPDUs (EHT NDPA frame and EHT Sounding NDP) sequentially in the same TXOP. There is no limit to order of sounding operation. In order to avoid the misleading of the HE STAs, Sounding PPDUs for the HE STA may be sent last.

Sounding PPDUs (NDPA frame and Sounding NDP) have to always occupy the primary frequency segment. Following Sounding PPDUs, BFRP Trigger frames can be simultaneously sent to solicit two different beamforming feedback from two different STAs.

The Sounding Dialog Token Number field in the compressed beamforming/CQI report shall be set to the same value as the Sounding Dialog Token Number field in the corresponding NDPA frame. However, the Sounding Dialog Token Number field in the first NDPA frame (for example, HE NDPA frame) may be set to different value as the Sounding Dialog Token Number field in the second NDPA frame (for example, EHT NDPA frame).

After receiving compressed beamforming/CQI report, the AP may send DL data to STAs based on the measured steering matrix

FIG. 20 shows another example of OFDMA Aggregated PPDU Sounding Operation. Compared with the example shown in FIG. 19, HE Sounding PPDUs are transmitted after EHT Sounding PPDUs are transmitted.

FIG. 21 show an example for setting dialog token for Sounding PPDUs.

During a TXOP, when more than one Sounding PPDUs are sent, the Sounding Dialog Token Number subfield in the Sounding Dialog Token field in the NDPA frames needs to have a different value.

BFRP Trigger frame may include a Sounding Dialog Token Number subfield to explicitly specify the Sounding PPDU on which the beamforming report is requested. The Sounding Dialog Token Number subfield in the BFRP Trigger frame may indicates the NDPA frame (or Sounding NDP) on which the beamforming report is requested. A STA can send the beamforming report based on a Sounding PPDU indicated by the Sounding Dialog Token Number subfield in the BFRP Trigger frame.

In FIG. 21, A≠B, when A denotes a value of the Sounding Dialog Token Number subfield in the EHT NDPA frame, and B denotes a value of the Sounding Dialog Token Number field in the HE NDPA frame

The BFRP Trigger frame destined to EHT STA includes the Sounding Dialog Token Number subfield which is set to A to indicate that the beamforming report based on EHT NDPA is requested.

FIG. 22 show another example for setting dialog token for Sounding PPDUs. Compared with the example shown in FIG. 21, the BFRP Trigger frame destined to EHT STA includes the Sounding Dialog Token Number subfield which is set to B to indicate that the beamforming report based on HE NDPA is requested.

If the Sounding Dialog Token Number subfield is not specified, the beamforming report of the immediately preceding Sounding PPDU is sent. In FIG. 22, BFRP Trigger frame does not include the Sounding Dialog Token Number subfield for HE STA. HE STA can send the beamforming report based on the immediately preceding Sounding PPDU (for example, HE Sounding NDP).

The BFRP Trigger frame includes a plurality of Sounding Dialog Token Number subfields for a plurality of STAs. For example, the BFRP Trigger frame includes a first Sounding Dialog Token Number subfield for EHT STA and a second Sounding Dialog Token Number subfield for HE STA.

FIG. 23 shows another example of OFDMA Aggregated PPDU Sounding Operation. Compared with the example shown in FIG. 19, an AP may aggregate same Sounding PPDUs (e.g., HE NDPA and HE sounding NDP, EHT NDPA and EHT Sounding NDP) in an OFDMA manner and simultaneously transmit them.

Hereinafter, Ack policy using Aggregated PPDU is descibed.

Before transmitting an OFDMA Aggregated PPDU, an AP signals STAs to which an OFDMA Aggregated PPDU will be destined. On this purpose, the User Info field in the MU-RTS frame contains the AID of the STA to which a sub-PPDU of an OFDMA Aggregated PPDU will be destined and the sub-PPDU operating channel on which the corresponding sub-PPDU will be allocated. Then, the corresponding STA switches its operating channel to the sub-PPDU operation channel specified in the User Info field in the MU-RTS frame. After switching its operating channel, it replies with a CTS frame on the switched sub-PPDU operating channel. During the TXOP, after being determined that the AP will not transmit an OFDMA Aggregated PPDU having a sub-PPDU allocated to the corresponding STA, it switches back to the primary channel.

Conventionally, when a WLAN device (e.g., STA or AP) transmits a data frame to another WLAN device, the transmitting WLAN device may indicate its desired acknowledgement (Ack) policy in the data frame. For example, an ACK Policy subfield in the QoS Control field (e.g., bit 5 and bit 6 of the QoS Control field) of the data frame can be used for this purpose. Following table shows how the ACK Policy subfield may be interpreted by the WLAN device.

Ack Policy	Meaning
Normal Ack	The addressed recipient returns an Ack frame after a SIFS.
No Ack	The addressed recipient takes no action upon receipt of the frame.
HETP Ack	The frame is carried in an HE MU PPDU, HE SU PPDU, or HE ER SU PPDU that contains a frame that solicits a response in an HE TB PPDU. Or the frame is carried in an EHT MU PPDU that contains a frame that solicits a response in an EHT TB PPDU. The addressed recipient returns an Ack, Compressed BlockAck, or Multi-STA BlockAck frame carried in an HE TB PPDU a SIFS after the PPDU, subject to reception of a triggering frame in the PPDU.
Block Ack	The addressed recipient takes no action upon the receipt of the frame except for recording the state. The recipient can expect a BlockAckReq frame or implicit block ack request in the future.

In an OFDMA Aggregated PPDU, the Ack Policy of frames carried in the PPDU that is sent on the Secondary 80MHz (or 160MHz) Frequency Segment is determined by the Ack Policy of frames carried in the PPDU that is sent on the Primary 80MHz (or 160MHz) Frequency Segment.

FIG. 24 shows an example of Ack Policy in DL OFDMA Aggregated PPDU.

When at least one of frame carried in PPDU that is sent on the Primary 80MHz (or 160MHz) Frequency Segment has the Ack Policy equal to HETP Ack, frames carried in PPDU that is sent on the Secondary 80MHz (or 160MHz) Frequency Segment has the Ack Policy equal to HETP Ack, No Ack, or Block Ack.

If at least one of the frames sent on the Secondary 80MHz (or 160MHz) Frequency Segment has the Ack Policy equal to HETP Ack, the

of PPDU sent on Secondary 80MHz (or 160MHz) Frequency Segment shall be same with the

of PPDU sent on Primary 80MHz (or 160MHz) Frequency Segment.

Otherwise, the

of PPDU sent on Secondary 80MHz (or 160MHz) Frequency Segment shall be less than or equal to the

of PPDU sent on Primary 80MHz (or 160MHz) Frequency Segment.

FIG. 25 shows another example of Ack Policy in DL OFDMA Aggregated PPDU.

When at least one of frame carried in PPDU that is sent on the Primary 80MHz (or 160MHz) Frequency Segment has the Ack Policy equal to No Ack or Block Ack, frames carried in PPDU that is sent on the Secondary 80MHz (or 160MHz) Frequency Segment has the Ack Policy equal to No Ack or Block Ack.

The

of PPDU sent on Primary 80MHz (or 160MHz) Frequency Segment.

FIG. 26 shows an example of UL Length in UL OFDMA Aggregated PPDU.

The UL Length subfield of the Common Info field indicates the value of the L-SIG LENGTH field of the solicited HE TB PPDU.

When an AP sends Basic Trigger frames (for example, MU-RTS) to solicit TB PPDUs in an OFDMA manner from STAs of different types (e.g., HE STA and EHT STA), the UL Length subfield of the Common Info field in the Basic Trigger frames is set to as following:

- If the AP does not allow an STA to solicit any immediate response for the MPDUs that the STA aggregates in the TB PPDU sent on the Secondary 80MHz (or 160MHz) Frequency Segment (i.e., the TID Aggregation Limit subfield in the User info fields of the Basic Trigger frame to 0), the UL Length subfield of the Common Info field in the Basic Trigger frame that solicits TB PPDU on the Secondary 80MHz (or 160MHz) Frequency Segment shall be less than or equal to the UL Length subfield of the Common Info field in the Basic Trigger frame that solicits TB PPDU on the Primary 80MHz (or 160MHz) Frequency Segment.

- Otherwise, the UL Length subfield of the Common Info field in the Basic Trigger frame that solicits TB PPDU on the Secondary 80MHz (or 160MHz) Frequency Segment shall be the same as the UL Length subfield of the Common Info field in the Basic Trigger frame that solicits TB PPDU on the Primary 80MHz (or 160MHz) Frequency Segment.

FIG. 27 shows another example of UL Length in UL OFDMA Aggregated PPDU.

The TID Aggregation Limit subfield in the User info fields of the Trigger frame indicates the MPDUs allowed in an A-MPDU carried in the HE TB PPDU and the maximum number of TIDs that can be aggregated by the STA in the A-MPDU. The value in the TID Aggregation Limit subfield in Trigger frame is less than or equal to MT + 1, where MT is the value indicated in the Multi-TID Aggregation Tx Support subfield in the HE MAC Capabilities Information field in the HE Capabilities element transmitted by the non-AP STA that is the intended receiver of the User Info field.

If the AP does not allow an STA to solicit any immediate response for the MPDUs that the STA aggregates in the TB PPDU sent on the Primary 80MHz (or 160MHz) Frequency Segment (i.e., the TID Aggregation Limit subfield in the User info fields of the Basic Trigger frame to 0), the AP also does not allow an STA to solicit any immediate response for the MPDUs that the STA aggregates in the TB PPDU sent on the Secondary 80MHz (or 160MHz) Frequency Segment (i.e., the TID Aggregation Limit subfield in the User info fields of the Basic Trigger frame to 0).

And, the UL Length subfield of the Common Info field in the Basic Trigger frame that solicits TB PPDU on the Secondary 80MHz (or 160MHz) Frequency Segment shall be less than or equal to the UL Length subfield of the Common Info field in the Basic Trigger frame that solicits TB PPDU on the Primary 80MHz (or 160MHz) Frequency Segment.

Hereinatfer, STA-initiated Aggregated PPDU is described.

According to AP initiated OFDMA Aggregated PPDU, an AP obtains a TXOP. Before transmitting an OFDMA Aggregated PPDU, the AP signals STAs to which an OFDMA Aggregated PPDU will be destined. On this purpose, the User Info field in the MU-RTS frame contains the AID of the STA to which a sub-PPDU of an OFDMA Aggregated PPDU will be destined and the sub-PPDU operating channel on which the corresponding sub-PPDU will be allocated.

Then, the corresponding STA switches its operating channel to the sub-PPDU operation channel specified in the User Info field in the MU-RTS frame. After switching its operating channel, it replies with a CTS frame on the switched sub-PPDU operating channel.

FIG. 28 shows an example of STA initiated OFDMA Aggregated PPDU.

A STA obtains a TXOP.

The STA transmits an RTS Trigger frame to an AP. If the STA supports only Primary 80MHz (or 160MHz) Frequency Segment, the STA transmits the RTS Trigger frame on single Frequency Segment. If the STA supports both Primary 80MHz (or 160MHz) Frequency Segment and Secondary 80MHz (or 160MHz) Frequency Segment, the STA transmits the RTS Trigger frame on both Frequency Segments.

After receiving the RTS Trigger frame from the STA, the AP transmits Trigger frame to solicit the TB PPDUs from the STA and other STAs. The STA and other STAs may be different types (e.g., HE STA and EHT STA). In which case, the TB PPDUs may be different types (e.g., HE TB PPDU and EHT TB PPDU).

Before sending the Trigger frame, the AP shall perform the CCA procedure on Primary 80MHz (or 160MHz) Frequency Segment and Secondary 80MHz (or 160MHz) Frequency Segment. If the CCA is idle on only Primary 80MHz (or 160MHz) Frequency Segment, the AP transmits the Trigger frame on single Frequency Segment. If the CCA is idle on both Primary 80MHz (or 160MHz) Frequency Segment and Secondary 80MHz (or 160MHz) Frequency Segment, the AP transmits the Trigger frame on both Frequency Segments. Also, based on the CCA results, the AP can dynamically adjust the TXOP bandwidth.

Based on receiving the RTS frame, the AP may check whether at least one of the first frequency segment (i.e. a primary 160 MHz frequency segment) and a second frequency segment (i.e. a secondary 160 MHz frequency segment) is idle during a predefined time. If both the first frequency segment and the second frequency segment are idle, the AP may transmit one or more trigger frames to one or more STAs. For example, the AP receives a RTS frame from EHT STA over the frist frequency segment. Then, the AP may transmit a trigger frame to EHT STA over the second frequency segment and transmit a trigger frame to HE STA over the first frequency segment. Each trigger frame allows a corresponding STA to transmit the STA's PPDU in the coreesponding frequency segment.

The contents of Trigger frames soliciting the TB PPDU are configured to align the OFDMA symbol boundaries of each of aggregated TB PPDUs. For example, PHY parameters (e.g., GI duration and LTF size (1x LTF, 2x LTF, 4x LTF), number of LTF symbols) shall be the same.

FIG. 29 shows another example of STA initiated OFDMA Aggregated PPDU.

Based on receiving the RTS frame over the first frequency frame, the AP may check whether at least one of the first frequency segment and a second frequency segment is idle during a predefined time. If only the first frequency segment is idle, the AP may transmit a trigger frames to a STA. For example, the AP receives a RTS frame from EHT STA over the frist frequency segment. Then, the AP may transmit a trigger frame to HE STA over the first frequency segment.

FIG. 30 shows still another example of STA initiated OFDMA Aggregated PPDU.

EFT STA sends one or more RTS frames over the first and second frequency segments. Based on receiving the RTS frame, the AP may check whether at least one of the first frequency segment and a second frequency segment is idle during a predefined time. If both the first frequency segment and the second frequency segment are idle, the AP may transmit one or more trigger frames to one or more STAs. For example, the AP receives a RTS frame from EHT STA over the frist frequency segment. Then, the AP may transmit a trigger frame to EHT STA over the second frequency segment and transmit a trigger frame to HE STA over the first frequency segment.

FIG. 31 shows still another example of STA initiated OFDMA Aggregated PPDU.

EFT STA sends one or more RTS frames over the first and second frequency segments. Based on receiving the RTS frame, the AP may check whether at least one of the first frequency segment and a second frequency segment is idle during a predefined time. If only the first frequency segment is idle, the AP may transmit a trigger frames to a STA. For example, the AP receives a RTS frame from EHT STA over the frist and second frequency segments. Then, the AP may transmit a trigger frame to HE STA over the first frequency segment.

FIG. 32 shows still another example of STA initiated OFDMA Aggregated PPDU.

The AP may decrease the TXOP bandwidth based on the CCA results. Based on receiving the RTS frame, the AP may check whether at least one of the first frequency segment and a second frequency segment is idle during a predefined time. If a part of a freqency segment is idle, the AP may utilize the idle part of the frequency segment. If a part of the first frequency segment is idle, the AP may transmit a trigger frame to a over the idle part of the frequency segment.

In order to protect the TXOP, the AP and STA(s) may send the MU-RTS/CTS frame exchange after receiving a RTS Trigger frame from a STA.

In which case, TXVECTOR parameter SCRAMBLER_INITIAL_VALUE of MU-RTS frames sent on Primary 80MHz (or 160MHz) Frequency Segment and Secondary 80MHz (or 160MHz) Frequency Segment are set to the same value.

When a STA obtaining a TXOP wants to initiate a direct link transmission instead of the uplink transmission, the STA can indicate a OFDMA Aggregated PPDU of non-TB PPDU (i.e., SU or MU PPDU) in a RTS Trigger frame sent to an AP.

The contents of Trigger frames soliciting a non-TB PPDU are configured to align the OFDMA symbol boundaries of each of aggregated non-TB PPDUs for Data and Control Response (e.g., Ack/Block Ack). For example. PHY parameters (e.g., GI duration and LTF size (1x LTF, 2x LTF, 4x LTF), number of LTF symbols) shall be the same.

The Trigger1 to be trasmitted to EHT STA2 specifies the TXVECTOR parameters of EHT SU PPDU carrying BA frame in order to align the OFDMA symbol boundaries. The Trigger2 to be trasmitted to EHT STA1 specifies the TXVECTOR parameters of EHT SU PPDUs carrying Data frame and BA frame in order to align the OFDMA symbol boundaries.

To reduce an interference among the solicited non-TB PPDUs, the Trigger frame soliciting a non-TB PPDU can indicate the Allowed Maximum Transmit Power of the solicited non-TB PPDU.

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 item, including single members. For example, “at least one of: a, b, and 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.

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.

Claims

A method for transmitting a physical layer protocol data unit (PPDU) in a wireless local area network, the method comprising:

receiving, by a second station, a request-to-send (RTS) frame from a first station over a first frqeuncy segment,

checking, by the second sation, whether at least one of the first frequency segment and a second frequency segment is idle during a predefined time based on receiving the RTS frame; and

if the second frequency segment is idle, transmitting, by the second sation, a trigger frame to the first staion over the second frequency segment, the trigger frame allowing the first station to transmit the first station's PPDU in the second frequency segment.
The method of claim 1, wherein the trigger frame further allows a third station to transmit the third station's PPDU in the first frequency segment.
The method of claim 2, wherein the first station's PPDU has different format than the third station's PPDU.
The method of claim 1, wherein:

if both the first frequency segment and the second frequency segment are idle, transmitting, by the second sation, a trigger frame to the first staion over the first frequency segment and the second frequency segment, the trigger frame allowing the first station to transmit the first station's PPDU in the first frequency segment and the second frequency segment.
The method of claim 1, wherein the first frequency segment is a primary frequency segment and the second frequency segment is a secodnary frequency segment.
The method of claim 5, wherein the first frequency segment includes a primary 20 MHz channel.
The method of claim 1, wherein the second frequency segment has same bandwidth with the first frequency segment.
The method of claim 7, wherein a bandwidth of the first frequency segment is 80 MHz or 160 MHz.
A device for a wireless local area network (WLAN), the device comprising:

a processor; and

a memory operatively coupled with the processor and configured to store instructions that, when executed by the processor, cause the device to perform functions comprising:

receiving a request-to-send (RTS) frame from a first station over a first frqeuncy segment,

checking whether at least one of the first frequency segment and a second frequency segment is idle during a predefined time based on receiving the RTS frame; and

if the second frequency segment is idle, transmitting a trigger frame to the first staion over the second frequency segment, the trigger frame allowing the first station to transmit the first station's PPDU in the second frequency segment.
The device of claim 9, wherein the trigger frame further allows a third station to transmit the third station's PPDU in the first frequency segment.
The device of claim 10, wherein the first station's PPDU has different format than the third station's PPDU.
The device of claim 9, wherein the functions futher comprise:

if both the first frequency segment and the second frequency segment are idle, transmitting a trigger frame to the first staion over the first frequency segment and the second frequency segment, the trigger frame allowing the first station to transmit the first station's PPDU in the first frequency segment and the second frequency segment.