Device and method for sharing transmission opportunity

Abstract

A sharing access point (AP) obtains a transmission opportunity (TXOP) and transmits a multi-user request-to-send (MU-RTS) trigger frame to a shared AP. The MU-RTS trigger frame initiates a frame exchange between the shared AP and a station associated with the shared AP within the TXOP.

Description

DEVICE AND METHOD FOR SHARING TRANSMISSION OPPORTUNITY

[0001] The present disclosure relates to a wireless local area network (WLAN), and more particularly, to a method for sharing transmission opportunity in the WLAN and a device using the same.

[0002] 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).

[0003] 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.

[0004] 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 resource units (RUs) for STAs. The AP can simultaneously transmit various formats of PPDUs to multiple STAs.

[0005] Transmission opportunity (TXOP) in the WLAN is an interval of time during which a particular STA has the right to initiate frame exchange sequences onto the WM. A TXOP owner which obtains the TXOP only can initiate a transmission during the TXOP duration. Institute of Electrical and Electronics Engineers (IEEE) 802.11be, dubbed Extremely High Throughput (EHT), provides TXOP sharing procedure which allows an AP to allocate a portion of an obtained TXOP to a non-AP STA for transmitting one or more PPDUs.

[0006] There is a need for enhancing TXOP sharing between neighboring APs to improve the reliability of the network in latency and throughput.

[0007] The present disclosure provides a method for sharing a transmission opportunity (TXOP) in a wireless local area network.

[0008] The present disclosure also provides a device for sharing a TXOP in a wireless local area network.

[0009] In an aspect, a method for sharing a transmission opportunity (TXOP) includes obtaining, by an sharing access point (AP), a TXOP, and transmitting, by the sharing AP, a multi-user request-to-send (MU-RTS) trigger frame, If the MU-RTS trigger frame includes a first basic service set identifier (BSSID), the MU-RTS trigger frame initiates a frame exchange between the sharing AP and at least one station associated with the sharing AP within the TXOP. If the MU-RTS trigger frame includes a second BSSID, the MU-RTS trigger frame initiates a frame exchange between a shared AP and at least one station associated with the shared AP within the TXOP.

[0010] In another aspect, a device operating as a sharing access point (AP) to share a transmission opportunity (TXOP) 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 include obtaining a TXOP, and transmitting a multi-user request-to-send (MU-RTS) trigger frame. If the MU-RTS trigger frame includes a first basic service set identifier (BSSID), the MU-RTS trigger frame initiates a frame exchange between the device and at least one station associated with the device within the TXOP. If the MU-RTS trigger frame includes a second BSSID, the MU-RTS trigger frame initiates a frame exchange between a shared AP and at least one station associated with the shared AP within the TXOP.

[0011] As new WLAN communication protocols enable enhanced features, non-primary channel access mechanism is provided to support signaling regarding features and resource allocations.

[0012] FIG. 1 shows a block diagram of an example wireless communication network.

[0013] FIG. 2 shows a block diagram of an example wireless communication device.

[0014] FIG. 3 shows an example of wireless channel that includes multiple subchannels.

[0015] FIG. 4 shows an example of PPDU transmission.

[0016] FIG. 5 shows an example of UL MU transmission.

[0017] FIG. 6 shows an example of sharing TXOP according to an embodiment of the present disclosure.

[0018] FIG. 7 shows an example of a format of a trigger frame according to an embodiment of the present disclosure.

[0019] FIG. 8 shows another example of sharing TXOP according to an embodiment of the present disclosure.

[0020] FIG. 9 shows still another example of sharing TXOP according to an embodiment of the present disclosure.

[0021] FIG. 10 shows still another example of sharing TXOP according to an embodiment of the present disclosure.

[0022] FIG. 11 shows still another example of sharing TXOP according to an embodiment of the present disclosure.

[0023] FIG. 12 shows still another example of sharing TXOP according to an embodiment of the present disclosure.

[0024] FIG. 13 shows still another example of sharing TXOP according to an embodiment of the present disclosure.

[0025] FIG. 14 shows still another example of sharing TXOP according to an embodiment of the present disclosure.

[0026] 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.

[0027] 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).

[0028] 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.

[0029] FIG. 1 shows a block diagram of an example wireless communication network.

[0030] 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.

[0031] 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.

[0032] 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.

[0033] 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.

[0034] 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.

[0035] 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.

[0036] 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).

[0037] 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.

[0038] 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.

[0039] FIG. 2 shows a block diagram of an example wireless communication device.

[0040] 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.

[0041] The wireless communication device 50 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.

[0042] 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.

[0043] 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).

[0044] Very high throughput (VHT) is used to represent IEEE 802.11ac, high efficiency (HE) is used to represent IEEE 802.11ax, extremely high throughput (EHT) is used to represent IEEE 802.11be. EHT STA may be used to represent a STA supporting at least EHT. EHT STA can further support VHT and / or HE.

[0045] Ultra High Reliability (UHR) is used to represent any later (post-EHT) version of a new wireless communication protocol conforming to a future IEEE 802.11 wireless communication protocol standard or other standard, and is for illustration purpose only. 'UHR' may be referred to as other terms, for example, Ultra Low Latency (ULL), High Reliability (HR), etc. The UHR PPDU may support future amendments to the IEEE 802.11 wireless communication standard.

[0046] FIG. 3 shows an example of wireless channel that includes multiple subchannels.

[0047] 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.

[0048] 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. 3, 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.

[0049] The primary channel is the common channel of operation for all STAs that are members of the BSS. The secondary channel is a channel associated with the primary channel used to create a channel wider than the primary channel.

[0050] In 40 MHz BSS, the 20 MHz secondary channel adjacent to the primary 20 MHz channel that together form the 40 MHz channel of the 40 MHz BSS.

[0051] In 80 MHz BSS, the secondary 20 MHz channel adjacent to the primary 20 MHz channel that together form the primary 40 MHz channel of the 80 MHz BSS. The secondary 40 MHz channel adjacent to the primary 40 MHz channel that together form the 80 MHz channel of the 80 MHz VHT BSS.

[0052] In 160 MHz or 80+80 MHz BSS, the secondary 80 MHz channel not including the primary 20 MHz channel, that together with the primary 80 MHz channel including the primary 20 MHz channel form the 160 MHz or 80+80 MHz channel of the 160 MHz or 80+80 MHz BSS.

[0053] In 320 MHz BSS, the secondary 160 MHz channel not including the primary 20 MHz channel, which together with the primary 160 MHz channel including the primary 20 MHz channel form the 320 MHz channel of the 320 MHz BSS.

[0054] FIG. 4 shows an example of PPDU transmission.

[0055] A WLAN device transmits a PPDU by using a four subchannels CH1, CH2, CH3 and CH4 of 80 MHz operating channel. 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.

[0056] 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.

[0057] 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.

[0058] 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.

[0059] FIG. 5 shows an example of UL MU transmission.

[0060] UL MU operation allows an AP to solicit simultaneous immediate response frames from one or more STAs.

[0061] 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 or more TB PPDUs to the response STAs (for example, STA1 and STA2).

[0062] 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, multi-user request to send (MU-RTS) frame, multi-user block ack request (MU-BAR) frame, Beamforming Report Poll (BFRP) Trigger frame, etc.

[0063] The trigger frame may include a UL bandwidth field, an CS required field, one or more STA IDs and one or more resource unit (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 network allocation vector (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.

[0064] A 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 clear channel assessment (CCA) function senses that the WM is busy. Transmission opportunity (TXOP) is an interval of time during which a particular STA has the right to initiate frame exchange sequences onto the WM.

[0065] A TXOP holder or a TXOP owner is a STA that has either been granted a TXOP or successfully contended for a TXOP. A TXOP responder is a STA that transmits a frame in response to a frame received from the TXOP holder during a frame exchange sequence, but that does not acquire a TXOP in the process.

[0066] The TXOP sharing allows an AP to allocate a portion of an obtained TXOP to an associated non-AP STA and / or another AP for transmitting one or more frames (or one or more PPDUs). A sharing AP is an AP that obtains a TXOP and share the TXOP with a peer AP. A shared AP is the peer AP that uses a portion of the TXOP obtained by the sharing AP. The sharing AP and the shared AP may have same or different operating bandwidths. The sharing AP and the shared AP may have same or different primary channels. The sharing AP and the shared AP may have same or different primary 20 MHz channels.

[0067] Hereinafter, AP1 is a shared AP and STA1 is a STA associated with AP1. AP2 is a shared AP and STA2 is a STA associated with AP2.

[0068] FIG. 6 shows an example of sharing TXOP according to an embodiment of the present disclosure.

[0069] AP1 and AP2 has same 160 MHz operating bandwidths and has same primary 80 MHz channels. After performing backoff procedure, AP1 obtains a TXOP.

[0070] First, AP1 can initiate a frame exchange with STA1 associated with AP1 within the TXOP. For example, AP1 sends a MU-RTS trigger frame to STA1. STA1 sends a clear-to-send (CTS) frame as a response to the MU-RTS. AP1 send a data frame to STA1. STA1 sends a BlockAck (BA) to acknowledge the data frame.

[0071] AP1 can share AP1's TXOP with AP2. AP1 may allocate time within the obtained TXOP to AP2 by transmitting an MU-RTS triggered TXOP sharing (TXS) trigger frame. The MU-RTS TXS trigger frame can indicate resources (an allocated time, an allocated bandwidth, and / or an access category) allocated within the TXOP.

[0072] The allocated time to the shared AP within the sharing AP's TXOP can be called as a shared TXOP duration. The time allocation can start from the end of the PPDU that contains the MU-RTS TXS trigger frame. During the shared TXOP duration, the shared AP can initiate a frame exchange with a STA associated with the shared AP.

[0073] AP1 can determine that its transmission of the MU-RTS TXS trigger frame to AP2 is successful when AP1 receives a response frame (for example, CTS frame or CTS-to-self frame) from AP2 in response to the MU-RTS TXS trigger frame. During the shared TXOP duration, AP2 cannot transmit any PPDU occupying subchannels that are not used when sending the response frame in response to the MU-RTS TXS trigger frame.

[0074] If AP1 determines that the transmission of the MU-RTS TXS trigger frame is successful, AP1 may transmit a PPDU within the shared TXOP duration if at least one of the following conditions are satisfied: (i) AP2 sends to AP1 a frame indicating a return of the shared TXOP duration, and (ii) the PPDU carries an immediate response that is solicited by AP2.

[0075] AP1 can transmit a PPDU after Point coordination function Interframe Space (PIFS) after the end of the shared TXOP duration when the WM is determined to be idle by the CS mechanism at the end of the shared TXOP duration.

[0076] AP2 can initiate a frame exchange with STA2 associated with AP2 within the TXOP after sending CTS frame. AP2 can use the shared TXOP duration allocated in the MU-RTS TXS trigger frame, which is addressed to AP2 and that indicates TXOP sharing of AP2, for the transmission of one or more PPDUs to another STA. AP2 can update AP2's access category within the shared TXOP duration according to the resource information in the MU-RTS TXS trigger frame. After sending the CTS solicited by the MU-RTS TXS Trigger frame, AP2 can set the Duration field of its frame(s) to a value that indicates a time no later than the ending time of the PPDU carrying the MU-RTS TXS Trigger frame plus the shared TXOP duration.

[0077] FIG. 7 shows an example of a format of a trigger frame according to an embodiment of the present disclosure. Not all fields are essential and names of fields are exemplary purpose only.

[0078] A receiver address (RA) field is set to a broadcast address when the trigger frame is an MU-RTS frame. A transmitter address (TA) field can be set to the address of the STA transmitting the trigger frame if the trigger frame is addressed to STAs that belong to a single BSS. The TA field can be set to the transmitted BSSID if the trigger frame is addressed to STAs from at least two different BSSs of the multiple BSSID set.

[0079] The BSSID that carries the Multiple BSSID element is called a transmitted BSSID, and the BSSIDs carried by the Multiple BSSID element are known as the nontransmitted BSSIDs. The multiple BSSID set can be included in the Multiple BSSID element. The BSSID carried in the beacon frame that includes the Multiple BSSID element is the transmitted BSSID. The nontransmitted BSSID can be derived from the multiple BSSID set.

[0080] A trigger type subfield in the common info field identifies a type of the trigger frame and can be set to a value indicating MU-RTS.

[0081] A TXS mode subfield can indicate whether to initiate TXOP sharing procedure. For example, the TXS mode subfield can be set to a first value (e.g., 0) to indicate the MU-RTS does not initiate TXOP sharing procedure. The TXS mode subfield can be set to a second value (e.g., 1) to indicate that the MU-RTS initiates TXOP sharing procedure wherein a scheduled STA can only transmit PPDU(s) addressed to its associated AP. The TXS mode subfield can be set to a third value (e.g., 2) to indicate that the MU-RTS initiates TXOP sharing procedure wherein a scheduled STA can transmit PPDU(s) addressed to its associated AP or addressed to another STA. The TXS mode subfield can be set to a fourth value (e.g., 3) to indicate that the MU-RTS initiates TXOP sharing procedure wherein a shared AP can transmit PPDU(s) addressed to its associated STA. An MU-RTS trigger frame that has the TXS Mode subfield not set to the first value can be called an MU-RTS TXS trigger frame.

[0082] An AID subfield of the MU-RTS TXS trigger frame indicates a shared AP or a non-AP STA to share TXOP. The Allocation Duration subfield in the MU-RTS TXS trigger frame can indicate the time allocated to the shared AP or the non-AP STA within the TXOP obtained by the AP. The Access Category subfield in the MU-RTS TXS trigger frame can indicate the access category allocated to the shared AP or the non-AP STA within the TXOP.

[0083] The RU Allocation subfield in the MU-RTS TXS trigger frame can indicate one or more channels on which the CTS frame is transmitted. The RU Allocation subfield in the MU-RTS TXS trigger frame can indicate a TXOP bandwidth on which the CTS frame is transmitted. The RU Allocation subfield in the MU-RTS TXS trigger frame can indicate whether the CTS frame is transmitted on the primary 20 MHz channel, primary 40 MHz channel, primary 80 MHz channel, primary 160 MHz channel, or 80+80 MHz channel or 320 MHz channel.

[0084] For example, B0 of the RU Allocation subfield is set to 0 to indicate a primary 20 MHz channel, primary 40 MHz channel and primary 80 MHz channel. For a primary 160 MHz, and 80+80 MHz, and 320 MHz indication, B0 of the RU Allocation subfield is set to 1. A PS160 subfield is set to 1 to indicate a 320 MHz channel and set to 0 to indicate a primary 20 MHz channel, primary 40 MHz channel, primary 80 MHz channel, and primary 160 MHz channel.

[0085] B7-B1 of the RU Allocation subfield is set to 68 to indicate the primary and secondary 80 MHz channel if the bandwidth of the PPDU that carries the MU-RTS TXS Trigger frame is less than 320 MHz, or to indicate the primary 160 MHz channel if the bandwidth of the PPDU that carries the MU-RTS TXS Trigger frame is 320 MHz. B7-B1 of the RU Allocation subfield is set to 69 to indicate a 320 MHz channel.

[0086] The MU-RTS TXS trigger frame can include a bandwidth subfield indicating a bandwidth of the PPDU carrying the MU-RTS TXS trigger frame.

[0087] When the sharing AP supports multiple BSSIDs, TXOP sharing can be initiated by the type of BSSID. The MU-RTS TXS Trigger frame addressed to the shared AP can be sent by a transmitted BSSID. For example, for sharing AP's frame exchanges sequence, the MU-RTS trigger frame can be sent with the nontransmitted BSSID. However, for shared AP's frame exchanges sequence, the MU-RTS TXS trigger frame is sent with the transmitted BSSID. The TA field of the MU-RTS TXS trigger frame can be set to the transmitted BSSID to indicate TXOP sharing procedure.

[0088] FIG. 8 shows another example of sharing TXOP according to an embodiment of the present disclosure.

[0089] If the MU-RTS TXS Trigger frame is addressed to single shared AP, a bandwidth signaling TA can be used in the MU-RTS TXS trigger frame or a CTS frame which is a response to the MU-RTS TXS Trigger frame. If the CCA of the primary channel is idle during the SIFS period following the receipt of the MU-RTS TXS Trigger frame, the shared AP can send the CTS frame on the one or more idle channels including the idle primary channel. These idle channels can be within the allocated TXOP bandwidth indicated the MU-RTS TXS Trigger frame.

[0090] The TXVECTOR parameter CH_BANDWIDTH_IN_NON_HT of the CTS frame can indicate the available bandwidth, which is less than or equal to the allocated TXOP bandwidth signaled by the RU Allocation subfield in the MU-RTS TXS Trigger frame. The available bandwidth can be equal to the bandwidth in which the CTS frame is transmitted.

[0091] Alternatively, the shared AP can send the CTS frame only when all channels in the allocated TXOP bandwidth signaled by the MU-RTS TXS trigger frame are idle.

[0092] In the example shown in FIG. 8, AP1 sends an MU-RTS TXS trigger frame to AP2 for sharing TXOP. A TXOP bandwidth allocated by the MU-RTS TXS trigger frame is 80 MHz.

[0093] Assume that CCA of the primary 40 MHz channel indicates idle during a specific interval (e.g., SIFS) after receiving MU-RTS TXS trigger frame, but CCA of the secondary 40 MHz channel indicates busy. Although the allocated TXOP bandwidth is not fully idle, AP2 can send the CTS frame on the idle primary 40 MHz channel. The CTS can include available bandwidth information on the idle primary 40 MHz channel. AP2 can initiate a frame exchange within the available bandwidth.

[0094] The shared AP can utilize the TXOP within the part or all of the TXOP bandwidth allocated by the sharing AP.

[0095] FIG. 9 shows still another example of sharing TXOP according to an embodiment of the present disclosure.

[0096] AP1 sends an MU-RTS TXS trigger frame to AP2 for sharing TXOP. A TXOP bandwidth allocated by the MU-RTS TXS trigger frame is 80 MHz. AP2 sends a CTS frame (or a CTS-to-self frame) in response to the MU-RTS TXS trigger frame.

[0097] Assume that CCA of the primary 80 MHz channel indicates idle during a specific interval (e.g., SIFS) after receiving MU-RTS TXS trigger frame, and CCA of the secondary 80 MHz channel also indicated idle during a specific interval (e.g., PIFS) immediately preceding the start of the CTS frame transmission. AP2 can send the CTS frame over 160 MHz channel which is not covered by the TXOP bandwidth. The CTS can include available bandwidth information on the 160 MHz channel. AP2 can initiate a frame exchange within the available bandwidth.

[0098] Depending on the network topology, either a SIFS or a longer sensing interval can be used to check CCA of one or more channels.

[0099] FIG. 10 shows still another example of sharing TXOP according to an embodiment of the present disclosure.

[0100] AP1 sends an MU-RTS TXS trigger frame to AP2 for sharing TXOP. When the sharing AP operates on one or more punctured channels, the MU-RTS TXS Trigger frame addressed to the shared AP can also follow the same channel puncturing pattern of the sharing AP. The CTS frame, which serves as a response to the MU-RTS TXS Trigger frame, can adhere to the same channel puncturing as well.

[0101] The transmit power of the CTS frame can be constrained by the transmit power envelope element information provided by the sharing AP.

[0102] Even if the shared AP can have a different channel puncturing pattern, the CTS frame is solicited by the sharing AP to the same channel puncturing pattern as the sharing AP.

[0103] In the shared AP's frame exchange, the shared AP can use the shared AP's puncturing pattern. Data frame and / or response frame used by AP2 and STA2 can adhere to the channel puncturing pattern of AP2.

[0104] FIG. 11 shows still another example of sharing TXOP according to an embodiment of the present disclosure.

[0105] A sharing AP can initiate spatial reuse with one or more shared APs. The sharing AP sends an MU-RTS TXS trigger frame to one or more shared APs. The MU-RTS TXS trigger frame includes information a spatial reuse for the one or more shared APs.

[0106] Each of the shared APs indicated in the MU-RTS TXS Trigger can send a CTS response in response to the MU-RTS TXS Trigger frame if the CCA indicate idle after receiving the MU-RTS TXS Trigger frame. The bandwidth of each CTS frame can be less than or equal to the allocated TXOP bandwidth signaled by the RU Allocation subfield in the MU-RTS TXS Trigger frame.

[0107] The shared APs can transmit PPDUs SIFS after the CTS response. The shared APs may not set NAV based on the MU-RTS TXS Trigger frame.

[0108] AP1 obtains a TXOP and sends an MU-RTS TXS trigger frame to AP2 and AP3 to share the TXOP using the spatial reuse. For example, if AP1 supports 4 spatial streams, AP1 uses 2 spatial streams and shares remaining 2 spatial streams with AP2 and AP3 within the TXOP.

[0109] AP2 detects that CCA of the primary 80 MHz channel is idle, and sends a CTS frame over the primary 80 MHz channel. AP2 can initiate frame exchange with a STA associated with the AP2 over the primary 80 MHz channel. AP3 detects that CCA of the primary 40 MHz channel is idle but CCA of the secondary 40 MHz channel is busy, and sends a CTS frame over the primary 40 MHz channel. AP3 can initiate frame exchange with a STA associated with the AP3 over the primary 40 MHz channel.

[0110] FIG. 12 shows still another example of sharing TXOP according to an embodiment of the present disclosure.

[0111] A shared AP can utilize a transmission bandwidth wider than the TXOP bandwidth allocated by the MU-RTS TXS trigger frame. The shared AP can send a CTS frame with same TXOP bandwidth. AP1 obtains a TXOP and sends an MU-RTS TXS trigger frame to AP2 and AP3 to share the TXOP using the spatial reuse.

[0112] If CCA on one or more secondary channels (e.g., secondary 40 MHz channel, secondary 80 MHz channel, secondary 160 MHz channel) which are located outside the TXOP bandwidth is idle for a specific interval (e.g., SIFS or PIFS), the shared AP can use the idle secondary channel during the shared TXOP duration.

[0113] FIG. 13 shows still another example of sharing TXOP according to an embodiment of the present disclosure.

[0114] A sharing AP can initiate spatial reuse with one or more shared APs. The sharing AP sends the MU-RTS TXS trigger frame to one or more shared APs. A STA associated with the sharing AP can send a CTS frame in response to the MU-RTS TXS trigger frame. The shared APs indicated in the MU-RTS TXS Trigger do not send any CTS frame.

[0115] The shared AP may obtain a TXOP after completing the back-off procedure. The MU-RTS TXS Trigger frame for spatial reuse can contains the energy detection (ED) threshold of the shared AP, which is used for the back-off procedure during the shared TXOP duration for the sharing AP.

[0116] The shared AP do not set NAV based on the MU-RTS TXS Trigger frame, and may disregard a preamble detection from a PPDU sent by other shared AP.

[0117] FIG. 14 shows still another example of sharing TXOP according to an embodiment of the present disclosure.

[0118] Compared with the example shown in FIG. 13, the shared AP can utilize a transmission bandwidth wider than the TXOP bandwidth allocated by the MU-RTS TXS trigger frame.

[0119] If CCA on one or more secondary channels (e.g., secondary 40 MHz channel, secondary 80 MHz channel, secondary 160 MHz channel) which are located outside the TXOP bandwidth is idle for a specific interval (e.g., SIFS or PIFS), the shared AP can use the idle secondary channel during the shared TXOP duration.

[0120] 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.

[0121] 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.

[0122] 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

1.A method for sharing a transmission opportunity (TXOP) in a wireless local area network, the method comprising:obtaining, by an sharing access point (AP), a TXOP; andtransmitting, by the sharing AP, a multi-user request-to-send (MU-RTS) trigger frame,wherein, if the MU-RTS trigger frame includes a first basic service set identifier (BSSID), the MU-RTS trigger frame initiates a frame exchange between the sharing AP and at least one station associated with the sharing AP within the TXOP, andif the MU-RTS trigger frame includes a second BSSID, the MU-RTS trigger frame initiates a frame exchange between a shared AP and at least one station associated with the shared AP within the TXOP.2.The method of claim 1, wherein the first BSSID is a nontransmitted BSSID which is derived from a multiple BSSID set, and the second BSSID is a transmitted BSSID which is included in a beacon frame transmitted by the sharing AP, the beacon frame carrying the multiple BSSID set.3.The method of claim 1, wherein the MU-RTS trigger frame further includes an allocation duration indicating a time allocated to the shared AP within the TXOP.4.The method of claim 1, wherein the MU-RTS trigger frame further includes a TXOP sharing mode subfield to indicate a TXOP sharing with the shared AP.5.The method of claim 1, further comprising:receiving, from the shared AP, a clear-to-send (CTS) frame as a response to the MU-RTS trigger frame,wherein the CTS frame indicates a channel bandwidth to be used for the frame exchange by the shared AP.6.A device operating as a sharing access point (AP) to share a transmission opportunity (TXOP), the device comprising:a processor; anda memory operatively coupled with the processor and configured to store instructions that, when executed by the processor, cause the device to perform functions comprising:obtaining a TXOP; andtransmitting a multi-user request-to-send (MU-RTS) trigger frame,wherein, if the MU-RTS trigger frame includes a first basic service set identifier (BSSID), the MU-RTS trigger frame initiates a frame exchange between the device and at least one station associated with the device within the TXOP, andif the MU-RTS trigger frame includes a second BSSID, the MU-RTS trigger frame initiates a frame exchange between a shared AP and at least one station associated with the shared AP within the TXOP.7.The device of claim 6, wherein the first BSSID is a nontransmitted BSSID which is derived from a multiple BSSID set, and the second BSSID is a transmitted BSSID which is included in a beacon frame transmitted by the device, the beacon frame carrying the multiple BSSID set.8.The device of claim 6, wherein the MU-RTS trigger frame further includes an allocation duration indicating a time allocated to the shared AP within the TXOP.9.The device of claim 6, wherein the MU-RTS trigger frame further includes a TXOP sharing mode subfield to indicate a TXOP sharing with the shared AP.10.The device of claim 6, wherein the functions further include:receiving, from the shared AP, a clear-to-send (CTS) frame in response to the MU-RTS trigger frame,wherein the CTS frame indicates a channel bandwidth to be used for the frame exchange by the shared AP.

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