Multi-access point up and downlink transmission

Abstract

The present invention offers ways to manage sharing transmissions in multi-AP (or BS) situations. There is provided a method comprising: receiving, by a first access point (AP) from a second AP, a first frame indicating an amount of uplink (UL) traffic for a station (STA) associated with the second AP; and transmitting, by the first AP to the second AP, a second frame indicating an allocated time of a transmission opportunity (TXOP) obtained by the first AP, and a time period, within the allocated time, based on the amount of UL traffic and for an UL transmission from the STA to the second AP.

Description

[0001] MULTI-ACCESS POINT UP AND DOWNLINK TRANSMISSION

[0002] FIELD OF THE INVENTION

[0003] The present invention relates to wireless communication networks, in particular, but not exclusively, to those implementing the IEEE™ 802.11 standard.

[0004] BACKGROUND OF THE INVENTION

[0005] In modem wireless networks, where deployments are dense and demand is high, it is desirable to make as an efficient use of the spectrum as possible. Many networks use a system of ‘protecting’ an upcoming transmission i.e. give a device or group of devices the chance to transmit by requiring other devices from refraining to transmit. Such a mechanism takes various forms - in the case of IEEE802. 11 (“Wi-Fi”), this is known as a transmission opportunity (TXOP) which is obtained by station before it transmits. In order to utilise the spectrum better, TXOP sharing (in the case of Wi-Fi) is employed. Also techniques are employed where a device (a station or “STA”, in the case of Wi-Fi) is served by multiple access points (“AP”) or base-stations (“BS”).

[0006] SUMMARY OF THE INVENTION

[0007] The present invention is defined by the appended claims. The methods, devices and computer program products defined herein allow the two APs (for BSs) to better manage resources when operating in a multi -AP (or BS) mode. This is achieved by sharing, between the APs (or BSs) information relating to upcoming downlink (DL) and uplink (UL) transmissions.

[0008] In an aspect there is provided a method which comprising receiving, by a first access point (AP) from a second AP, a first frame indicating a modulation and coding scheme (MCS) for a downlink (DL) transmission; and transmitting, by the first AP to the second AP, a second frame which indicates an allocated time of a transmission opportunity (TXOP) obtained by the first AP; and a time period, within the allocated time, for the DL transmission, wherein the time period is determined based on the MCS.

[0009] In an aspect, there is provided a method comprising receiving, by a first access point (AP) from a second AP, a first frame indicating a downlink (DL) transmission parameter for a DL transmission; and transmitting, by the first AP to the second AP, a second frame indicating a time period for the DL transmission, wherein the time period is determined based on the DL transmission parameter.

[0010] In an aspect there is provided a method comprising receiving, by a first access point (AP) from a second AP, a first frame indicating a downlink (DL) buffer status report (BSR) for a DL transmission; and transmitting, by the first AP to the second AP, a second frame indicating an allocated time of a transmission opportunity (TXOP) obtained by the first AP, an identifier of the second AP, a time period for the DL transmission; and a DL transmission parameter for the second AP for the DL transmission.

[0011] In an aspect there is provided a method comprising transmitting, by a first access point (AP) to a second AP, a first frame indicating a modulation and coding scheme (MCS) for a DL transmission; and receiving, by the first AP from the second AP, a second frame indicating an allocated time of a transmission opportunity (TXOP) obtained by the second AP; and a time period, within the allocated time, for the DL transmission, wherein the time period is determined based on the MCS.

[0012] In an aspect there is provided a method comprising transmitting, by a first access point (AP) to a second AP, a first frame indicating a downlink (DL) transmission parameter for a DL transmission; and receiving, by the first AP from the second AP, a second frame indicating a time period for the DL transmission, wherein the time period is determined based on the DL transmission parameter.

[0013] In an aspect there is provided a method comprising transmitting, by a first access point (AP) from a second AP, a first frame indicating a downlink (DL) buffer status report (BSR) for a DL transmission; and receiving, by the first AP from the second AP, a second frame indicating: an allocated time of a transmission opportunity (TXOP) obtained by the second AP, an identifier of the first AP, a time period for the DL transmission; and a DL transmission parameter for the first AP for the DL transmission.

[0014] In an aspect, there is a method comprising receiving, by a first access point (AP) from a second AP, a first frame indicating an amount of uplink (UL) traffic for a station (STA) associated with the second AP and transmitting, by the first AP to the second AP, a second frame indicating an allocated time of a transmission opportunity (TXOP) obtained by the first AP and a time period, within the allocated time, based on the amount of UL traffic and for an UL transmission from the STA to the second AP.

[0015] In an aspect, there is a method comprising receiving, by a first access point (AP) from a second AP, a first frame indicating an amount of uplink (UL) traffic for a station (STA) associated with the second AP and transmitting, by the first AP to the second AP, a second frame indicating a time period, based on the amount of UL traffic, for an UL transmission from the STA to the second AP.

[0016] In an aspect, there is a method comprising receiving, by a first access point (AP) from a second AP, a first frame indicating amount of uplink (UL) traffic for a station (STA) associated with the second AP and transmitting, by the first AP to the second AP, a second frame indicating an allocated time of a transmission opportunity (TXOP) obtained by the first AP an identifier of the second AP a duration of an uplink (UL) physical layer protocol data unit (PPDU) for an UL transmission from the STA to the second AP during the allocated time; and a modulation and coding scheme (MCS) for the UL PPDU.

[0017] In an aspect, a method comprising receiving, by a first access point (AP) from a second AP, a first frame indicating uplink (UL) time resource information for an UL transmission from a STA to the second AP and UL frequency resource information for the UL transmission and transmitting, by the first AP to the second AP, a second frame indicating an allocated time of a transmission opportunity (TXOP) obtained by the first AP; an identifier of the second AP, and a duration of an UL physical layer protocol data unit (PPDU) for the UL transmission, determined based on the UL time resource information and the UL frequency resource information.

[0018] In an aspect, there is a method comprising transmitting, by a first access point (AP) to a second AP, a first frame indicating an amount of uplink (UL) traffic for a station (STA) associated with the first AP and receiving, by the first AP from the second AP, a second frame indicating an allocated time of a transmission opportunity (TXOP) obtained by the second AP and a time period, within the allocated time, based on the amount of UL traffic and for an UL transmission from the STA to the first AP.

[0019] In an aspect, there is a method comprising transmitting, by a first access point (AP) to a second AP, a first frame indicating an amount of uplink (UL) traffic for a station (STA) associated with the first AP and receiving, by the first AP from the second AP, a second frame indicating a time period, based on the amount of UL traffic, for an UL transmission from the STA to the first AP.

[0020] In an aspect, there is a method comprising: transmitting, by a first access point (AP) to a second AP, a first frame indicating amount of uplink (UL) traffic for a station (STA) associated with the first AP; and receiving, by the first AP from the second AP, a second frame indicating: an allocated time of a transmission opportunity (TXOP) obtained by the second AP, an identifier of the first AP, a duration of an uplink (UL) physical layer protocol data unit (PPDU) for an UL transmission from the STA to the first AP during the allocated time; and a modulation and coding scheme (MCS) for the UL PPDU.

[0021] In an aspect, there is a method comprising transmitting, by a first access point (AP) to a second AP, a first frame indicating uplink (UL) time resource information for an UL transmission from a STA to the first AP, and UL frequency resource information for the UL transmission, and receiving, by the first AP from the second AP, a second frame indicating an allocated time of a transmission opportunity (TXOP) obtained by the second AP, an identifier of the first AP; and a duration of an UL physical layer protocol data unit (PPDU) for the UL transmission, determined based on the UL time resource information and the UL frequency resource information.

[0022] In an aspect there is provided a computer program product, storable on a computer readable medium and configured, when run on a processor to execute the method of any of methods described herein.

[0023] In an aspect there are provided a device arranged to, when implemented in a an access point, execute the methods described herein. BRIEF DESCRIPTION OF THE DRAWINGS

[0024] The above, as well as additional objects, features and advantages of the disclosed devices, systems and methods, will be better understood through the following illustrative and non-limiting detailed description of embodiments of devices and methods, with reference to the appended drawings, in which:

[0025] FIG. 1 illustrates example wireless communication networks in which embodiments of the present disclosure may be implemented.

[0026] FIG. 2 is a block diagram illustrating example implementations of a station (STA) and an access point (AP).

[0027] FIG. 3 illustrates an example of a Medium Access Control (MAC) frame format.

[0028] FIG. 4 illustrates an example of a Quality of Service (QoS) null frame indicating buffer status information.

[0029] FIG. 5 illustrates an example format of a physical layer (PHY) protocol data unit (PPDU).

[0030] FIG. 6 illustrates an example Multi-User Request-to-Send (MU-RTS) trigger frame which may be used in a triggered Transmit Opportunity (TXOP) sharing (TXS) procedure.

[0031] FIG. 7 illustrates an example of a TXS procedure (Mode =1).

[0032] FIG. 8 illustrates an example of a TXS procedure (Mode =2).

[0033] FIG. 9 illustrates an example multi-AP network.

[0034] FIG. 10 illustrates Coordinated Orthogonal Frequency Division Multiple Access (C- OFDMA).

[0035] FIG. 11 is an example that illustrates an inter- AP TXS procedure.

[0036] FIG. 12 illustrates an example physical layer protocol data unit (PPDU) which may be used for a downlink (DL) PPDU or an uplink (UL) PPDU.

[0037] FIGS. 13a and b illustrate examples of a problem that may arise in the inter- AP TXS procedure illustrated in FIG. 11.

[0038] FIGS. 14a and b illustrate examples of an inter- AP TXS procedure according to an embodiment.

[0039] FIGS. 15a and b illustrate examples of an inter- AP TXS procedure according to another embodiment.

[0040] FIGS. 16a and b illustrate examples of aggregated control (A-Control) fields which may be used in embodiments.

[0041] FIG. 17a and b illustrate example of information elements which may be used in embodiments.

[0042] FIG. 18 illustrates an example process according to an embodiment.

[0043] FIG. 19 illustrates another example process according to an embodiment.

[0044] FIG. 20 illustrates another example process according to an embodiment.

[0045] FIG. 21 illustrates another example process according to an embodiment. FIG. 22 illustrates another example process according to an embodiment.

[0046] FIG. 23 illustrates another example process according to an embodiment.

[0047] DETAILED DESCRIPTION OF EMBODIMENTS

[0048] In the following description, same references designate like or analogous elements.

[0049] In the present disclosure, various embodiments are presented as examples of how the disclosed techniques may be implemented and / or how the disclosed techniques may be practiced in environments and scenarios. It will be apparent to persons skilled in the relevant art that various changes in form and detail can be made therein without departing from the scope. After reading the description, it will be apparent to one skilled in the relevant art how to implement alternative embodiments. The present embodiments may not be limited by any of the described exemplary embodiments. The embodiments of the present disclosure will be described with reference to the accompanying drawings. Limitations, features, and / or elements from the disclosed example embodiments may be combined to create further embodiments within the scope of the disclosure. Any figures which highlight the functionality and advantages are presented for example purposes only. The disclosed architecture is sufficiently flexible and configurable, such that it may be utilized in ways other than those shown. For example, the actions listed in any flowchart may be re-ordered or only optionally used in some embodiments.

[0050] Embodiments may be configured to operate as needed. The disclosed mechanism may be performed when certain criteria are met, for example, in a station, an access point, a radio environment, a network, a combination of the above, and / or the like. Example criteria may be based, at least in part, on for example, wireless device or network node configurations, traffic load, initial system set up, packet sizes, traffic characteristics, a combination of the above, and / or the like. When the one or more criteria are met, various example embodiments may be applied. Therefore, it may be possible to implement example embodiments that selectively implement disclosed protocols.

[0051] In this disclosure, “a” and “an” and similar phrases are to be interpreted as “at least one” and “one or more.” Similarly, any term that ends with the suffix “(s)” is to be interpreted as “at least one” and “one or more.” In this disclosure, the term “may” is to be interpreted as “may, for example.” In other words, the term “may” is indicative that the phrase following the term “may” is an example of one of a multitude of suitable possibilities that may, or may not, be employed by one or more of the various embodiments. The terms “comprises” and “consists of’, as used herein, enumerate one or more components of the element being described. The term “comprises” is interchangeable with “includes” and does not exclude unenumerated components from being included in the element being described. By contrast, “consists of’ provides a complete enumeration of the one or more components of the element being described. The term “based on”, as used herein, may be interpreted as “based at least in part on” rather than, for example, “based solely on”. The term “and / or” as used herein represents any possible combination of enumerated elements. For example, “A, B, and / or C” may represent A; B; C; A and B; A and C; B and C; or A, B, and C. If A and B are sets and every element of A is an element of B, A is called a subset of B. In this specification, only non-empty sets and subsets are considered. For example, possible subsets of B = {STA1, STA2} are: {STA1}, {STA2}, and {STA1, STA2}. The phrase “based on” (or equally “based at least on”) is indicative that the phrase following the term “based on” is an example of one of a multitude of suitable possibilities that may, or may not, be employed to one or more of the various embodiments. The phrase “in response to” (or equally “in response at least to”) is indicative that the phrase following the phrase “in response to” is an example of one of a multitude of suitable possibilities that may, or may not, be employed to one or more of the various embodiments. The phrase “depending on” (or equally “depending at least to”) is indicative that the phrase following the phrase “depending on” is an example of one of a multitude of suitable possibilities that may, or may not, be employed to one or more of the various embodiments. The phrase “employing / using” (or equally “employing / using at least”) is indicative that the phrase following the phrase “employing / using” is an example of one of a multitude of suitable possibilities that may, or may not, be employed to one or more of the various embodiments.

[0052] The term configured may relate to the capacity of a device whether the device is in an operational or non-operational state. Configured may refer to specific settings in a device that effect the operational characteristics of the device whether the device is in an operational or non-operational state. In other words, the hardware, software, firmware, registers, memory values, and / or the like may be “configured” within a device, whether the device is in an operational or non-operational state, to provide the device with specific characteristics. Terms such as “a control message to cause in a device” may mean that a control message has parameters that may be used to configure specific characteristics or may be used to implement certain actions in the device, whether the device is in an operational or non-operational state.

[0053] In this disclosure, parameters (or equally called, fields, or Information elements: IES) may comprise one or more information objects, and an information object may comprise one or more other objects. For example, if parameter (IE) N comprises parameter (IE) M, and parameter (IE) M comprises parameter (IE) K, and parameter (IE) K comprises parameter (information element) J. Then, for example, N comprises K, and N comprises J. In an example embodiment, when one or more messages / frames comprise a plurality of parameters, it implies that a parameter in the plurality of parameters is in at least one of the one or more messages / frames but does not have to be in each of the one or more messages / frames.

[0054] Many features presented are described as being optional through the use of “may” or the use of parentheses. For the sake of brevity and legibility, the present disclosure does not explicitly recite each and every permutation that may be obtained by choosing from the set of optional features. The present disclosure is to be interpreted as explicitly disclosing all such permutations. For example, a system described as having three optional features may be embodied in seven ways, namely with just one of the three possible features, with any two of the three possible features or with three of the three possible features. Many of the elements described in the disclosed embodiments may be implemented as modules. A module is defined here as an element that performs a defined function and has a defined interface to other elements. The modules described in this disclosure may be implemented in hardware, software in combination with hardware, firmware, wetware (e.g., hardware with a biological element) or a combination thereof, which may be behaviorally equivalent. For example, modules may be implemented as a software routine written in a computer language configured to be executed by a hardware machine (such as C, C++, Fortran, Java, Basic, Matlab or the like) or a modeling / simulation program such as Simulink, Stateflow, GNU Octave, or LabVIEWMathScript. It may be possible to implement modules using physical hardware that incorporates discrete or programmable analog, digital and / or quantum hardware. Examples of programmable hardware comprise: computers, microcontrollers, microprocessors, application-specific integrated circuits (ASICs); field programmable gate arrays (FPGAs); and complex programmable logic devices (CPLDs). Computers, microcontrollers, and microprocessors are programmed using languages such as assembly, C, C++, or the like. FPGAs, ASICs and CPLDs are often programmed using hardware description languages (HDL) such as VHSIC hardware description language (VHDL) or Verilog that configure connections between internal hardware modules with lesser functionality on a programmable device. The mentioned technologies are often used in combination to achieve the result of a functional module.

[0055] The inventors have realised that, when TXOP sharing is employed in situation where multiple access points (APs) are used, there are certain problems. For the downlink (DL), there is a buffer status report (BSR) frame which indicates characteristics of buffered traffic. In multi-AP TXOP sharing, a sharing AP needs to know the transmission parameters that a shared AP intends / needs to use for upcoming DL transmissions - the AP can know, for example, the MCS used by a STA for uplink (UL) transmissions but it cannot know the intended MCS for a DL response. Similarly, for a UL case, a sharing AP does not know the intended transmission for UL to the shared AP and may allocate resources inefficiently.

[0056] FIG. 1 illustrates example wireless communication networks in which embodiments of the present disclosure may be implemented.

[0057] As shown in FIG. 1, the example wireless communication networks may include an Institute of Electrical and Electronic Engineers (IEEE) 802.11 (WLAN) infra-structure network 102. WLAN infra-structure network 102 may include one or more basic service sets (BSSs) 110 and 120 and a distribution system (DS) 130.

[0058] BSS 110-1 and 110-2 each includes a set of an access point (AP or AP STA) and at least one station (STA or non-AP STA). For example, BSS 110-1 includes an AP 104-1 and a STA 106-1, and BSS 110-2 includes an AP 104-2 and STAs 106-2 and 106-3. The AP and the at least one STA in a BSS perform an association procedure to communicate with each other. DS 130 may be configured to connect BSS 110-1 and BSS 110-2. As such, DS 130 may enable an extended service set (ESS) 150. Within ESS 150, APs 104-1 and 104-2 are connected via DS 130 and may have the same service set identification (SSID).

[0059] WLAN infra-structure network 102 may be coupled to one or more external networks. For example, as shown in FIG. 1, WLAN infra-structure network 102 may be connected to another network 108 (e.g., 802.X) via a portal 140. Portal 140 may function as a bridge connecting DS 130 of WLAN infra-structure network 102 with the other network 108.

[0060] The example wireless communication networks illustrated in FIG. 1 may further include one or more ad-hoc networks or independent BSSs (IBSSs). An ad-hoc network or IBSS is a network that includes a plurality of STAs that are within communication range of each other. The plurality of STAs are configured so that they may communicate with each other using direct peer-to-peer communication (i.e., not via an AP).

[0061] For example, in FIG. 1, STAs 106-4, 106-5, and 106-6 may be configured to form a first IBSS 112-1. Similarly, STAs 106-7 and 106-8 may be configured to form a second IBSS 112-2. Since an IBSS does not include an AP, it does not include a centralized management entity. Rather, STAs within an IBSS are managed in a distributed manner. STAs forming an IBSS may be fixed or mobile.

[0062] A STA as a predetermined functional medium may include a medium access control (MAC) layer that complies with an IEEE 802. 11 standard. A physical layer interface for a radio medium may be used among the APs and the non-AP stations (STAs). The STA may also be referred to using various other terms, including mobile terminal, wireless device, wireless transmit / receive unit (WTRU), user equipment (UE), mobile station (MS), mobile subscriber unit, or user. For example, the term “user” may be used to denote a STA participating in uplink Multi-user Multiple Input, Multiple Output (MU MIMO) and / or uplink Orthogonal Frequency Division Multiple Access (OFDMA) transmission.

[0063] A physical layer (PHY) protocol data unit (PPDU) may be a composite structure that includes a PHY preamble and a payload in the form of a PHY service data unit (PSDU). For example, the PSDU may include a PHY preamble and header and / or one or more MAC protocol data units (MPDUs). The information provided in the PHY preamble may be used by a receiving device to decode the subsequent data in the PSDU. In instances in which PPDUs are transmitted over a bonded channel (channel formed through channel bonding), the preamble fields may be duplicated and transmitted in each of the multiple component channels. The PHY preamble may include both a legacy portion (or “legacy preamble”) and a non-legacy portion (or “non-legacy preamble”). The legacy preamble may be used for packet detection, automatic gain control and channel estimation, among other uses. The legacy preamble also may generally be used to maintain compatibility with legacy devices. The format of, coding of, and information provided in the non-legacy portion of the preamble is based on the particular IEEE 802.11 protocol to be used to transmit the payload.

[0064] A frequency band may include one or more sub-bands or frequency channels. For example, PPDUs conforming to the IEEE 802.1 In, 802. 1 lac, 802. 1 lax and / or 802. 1 Ibe standard amendments may be transmitted over the 2.4 GHz, 5 GHz, and / or 6 GHz bands, each of which may be divided into multiple 20 MHz channels. The PPDUs may be transmitted over a physical channel having a minimum bandwidth of 20 MHz. Larger channels may be formed through channel bonding. For example, PPDUs may be transmitted over physical channels having bandwidths of 40 MHz, 80 MHz, 160 MHz, or 320 MHz by bonding together multiple 20 MHz channels.

[0065] FIG. 2 is a block diagram illustrating example implementations of a STA 210 and an AP 260. As shown in FIG. 2, STA 210 may include at least one processor 220, a memory 230, and at least one transceiver 240. AP 260 may include at least one processor 270, a memory 280, and at least one transceiver 290. Processor 220 / 270 may be operatively connected to memory 230 / 280 and / or to transceiver 240 / 290.

[0066] Processor 220 / 270 may implement functions of the PHY layer, the MAC layer, and / or the logical link control (LLC) layer of the corresponding device (STA 210 or AP 260). Processor 220 / 270 may include one or more processors and / or one or more controllers. The one or more processors and / or one or more controllers may comprise, for example, a general-purpose processor, a digital signal processor (DSP), a microcontroller, an application specific integrated circuit (ASIC), a field programmable gate array (FPGA), a logic circuit, or a chipset, for example.

[0067] Memory 230 / 280 may include a read-only memory (ROM), a random-access memory (RAM), a flash memory, a memory card, a storage medium, and / or other storage unit. Memory 230 / 280 may comprise one or more non-transitory computer readable mediums. Memory 230 / 280 may store computer program instructions or code that may be executed by processor 220 / 270 to carry out one or more of the operations / embodiments discussed in the present application. Memory 230 / 280 may be implemented (or positioned) within processor 220 / 270 or external to processor 220 / 270. Memory 230 / 280 may be operatively connected to processor 220 / 270 via various means known in the art.

[0068] Transceiver 240 / 290 may be configured to transmit / receive radio signals. In an embodiment, transceiver 240 / 290 may implement a PHY layer of the corresponding device (STA 210 or AP 260). In an embodiment, STA 210 and / or AP 260 may be a multi -link device (MLD), that is a device capable of operating over multiple links as defined by the IEEE 802.11 standard. As such, STA 210 and / or AP 260 may each implement multiple PHY layers. The multiple PHY layers may be implemented using one or more of transceivers 240 / 290.

[0069] Target wake time (TWT), a feature introduced in the IEEE 802.1 lah standard, allows STAs to manage activity in the BSS by scheduling STAs to operate at different times to reduce contention. TWTs may allow STAs to reduce the required amount of time that a STA utilizing a power management mode may be awake. TWTs may be individual TWTs or broadcast TWTs. Individual TWTs follow a negotiated TWT agreement between STAs. Broadcast TWTs are based on a schedule set and provided to STAs by an AP.

[0070] In an individual TWT, a STA that requests a TWT agreement is called a TWT requesting STA. The TWT requesting STA may be a non-AP STA for example. The STA that responds to the request is called a TWT responding STA. The TWT responding STA may be an AP for example. The TWT requesting STA is assigned specific times to wake up and exchange frames with the TWT responding STA. The TWT requesting STA may communicate wake scheduling information to the TWT responding STA. The TWT responding STA may transmit TWT values to the TWT requesting STA when a TWT agreement is established between them.

[0071] When explicit TWT is employed, the TWT requesting STA may wake up and perform a frame exchange. The TWT requesting STA may receive a next TWT information in a response from the TWT responding STA. When implicit TWT is used, the TWT requesting STA may calculate a next TWT by adding a fixed value to the current TWT value.

[0072] The TWT values for implicit TWT may be periodic. The TWT requesting STA operating with an implicit TWT agreement may determine a next TWT service period (TWT SP) start time by adding a value of a TWT wake interval associated with the TWT agreement to the value of the start time of the current TWT SP. The TWT responding STA may include the start time for a series of TWT SPs corresponding to a single TWT flow identifier of an implicit TWT agreement in a target wake time field of a TWT element. The TWT element may contain a value of ‘accept TWT’ in a TWT setup command field. The start time of the TWT SP series may indicate the start time of a first TWT SP in the series. Start times of subsequent TWT SPs may be determined by adding the value of the TWT wake interval to the start time of the current TWT SP. In an example, the TWT requesting STA, awake for an implicit TWT SP, may enter a doze state after the TWT SP has elapsed or after receiving an end of service period (EOSP) field equal to 1 from the TWT responding STA, whichever occurs first.

[0073] A TWT session may be negotiated between an AP and a STA. The TWT session may configure a TWT SP of DL and UL traffic between the AP and the STA. Expected traffic may be limited within the negotiated SP. The TWT SP may start at a specific time. The TWT SP may run for an SP duration. The TWT SP may repeat every SP interval.

[0074] FIG. 3 illustrates an example 300 of a MAC frame format. In operation, a STA may construct a subset of MAC frames for transmission and may decode a subset of received MAC frames upon validation. The particular subsets of frames that a STA may construct and / or decode may be determined by the functions supported by the STA. A STA may validate a received MAC frame using the frame check sequence (FCS) contained in the frame and may interpret certain fields from the MAC headers of all frames.

[0075] As shown in FIG. 3, a MAC frame includes a MAC header, a variable length frame body, and a frame check sequence (FCS).

[0076] The MAC header includes a frame control field, an optional duration / ID field, address fields, an optional sequence control field, an optional QoS control field, and an optional HT control field.

[0077] The frame control fields include the following subfields: protocol version, type, subtype, To DS, From DS, more fragments, retry, power management, more data, protected frame, and +HTC. The protocol version subfield is invariant in size and placement across all revisions of the IEEE 802.11 standard. The value of the protocol version subfield is 0 for MAC frames.

[0078] The type and subtype subfields together identify the function of the MAC frame. There are three frame types: control, data, and management. Each of the frame types has several defined subtypes. Bits within the subtype subfield are used to indicate a specific modification of the basic data frame (subtype 0). For example, in data frames, the most significant bit (MSB) of the subtype subfield, bit 7 (B7) of the frame control field, is defined as the QoS subfield. When the QoS subfield is set to 1, it indicates a QoS subtype data frame, which is a data frame that contains a QoS control field in its MAC header. The second MSB of the subtype field, bit 6 (B6) of the frame control field, when set to 1 in data subtypes, indicates a data frame that contain no frame body field.

[0079] The To DS subfield indicates whether a data frame is destined to the distribution system (DS). The From DS subfield indicates whether a data frame originates from the DS.

[0080] The more fragments subfield is set to 1 in all data or management frames that have another fragment to follow of the MAC service data unit (MSDU) or MAC management protocol data unit (MMPDU) carried by the MAC frame. It is set to 0 in all other frames in which the more fragments subfield is present.

[0081] The retry subfield is set to 1 in any data or management frame that is a retransmission of an earlier frame. It is set to 0 in all other frames in which the retry subfield is present. A receiving STA uses this indication to aid it in the process of eliminating duplicate frames. These rules do not apply for frames sent by a STA under a block agreement.

[0082] The power management subfield is used to indicate the power management mode of a STA.

[0083] The More Data subfield indicates to a STA in power save (PS) mode that bufferable units (BUs) are buffered for that STA at the AP. The more data subfield is valid in individually addressed data or management frames transmitted by an AP to a STA in PS mode. The more data subfield is set to 1 to indicate that at least one additional buffered BU is present for the STA.

[0084] The protected frame subfield is set to 1 if the frame body field contains information that has been processed by a cryptographic encapsulation algorithm.

[0085] The +HTC subfield indicates that the MAC frame contains an HT control field.

[0086] The duration / ID field of the MAC header indicates various contents depending on frame type and subtype and the QoS capabilities of the sending STA. For example, in control frames of the power save poll (PS-Poll) subtype, the duration / ID field carries an association identifier (AID) of the STA that transmitted the frame in the 14 least significant bits (LSB), and the 2 most significant bits (MSB) are both set to 1. In other frames sent by STAs, the duration / ID field contains a duration value (in microseconds) which is used by a recipient to update a network allocation vector (NAV). The NAV is a counter that it indicates to a STA an amount of time during which it must defer from accessing the shared medium. There can be up to four address fields in the MAC frame format. These fields are used to indicate the basic service set identifier (BSSID), source address (SA), destination address (DA), transmitting address (TA), and receiving address (RA). Certain frames might not contain some of the address fields. Certain address field usage may be specified by the relative position of the address field (1-4) within the MAC header, independent of the type of address present in that field. Specifically, the address 1 field always identifies the intended receiver(s) of the frame, and the address 2 field, where present, always identifies the transmitter of the frame.

[0087] The sequence control field includes two subfields, a sequence number subfield, and a fragment number subfield. The sequence number subfield in data frames indicates the sequence number of the MSDU (if not in an Aggregated MSDU (A-MSDU)) or A-MSDU. The sequence number subfield in management frames indicates the sequence number of the frame. The fragment number subfield indicates the number of each fragment of an MSDU or MMPDU. The fragment number is set to 0 in the first or only fragment of an MSDU or MMPDU and is incremented by one for each successive fragment of that MSDU or MMPDU. The fragment number is set to 0 in a MAC protocol data unit (MPDU) containing an A-MSDU, or in an MPDU containing an MSDU or MMPDU that is not fragmented. The fragment number remains constant in all retransmissions of the fragment.

[0088] The QoS control field identifies the traffic category (TC) or traffic stream (TS) to which the MAC frame belongs. The QoS control field may also indicate various other QoS related, A-MSDU related, and mesh-related information about the frame. This information can vary by frame type, frame subtype, and type of transmitting STA. The QoS control field is present in all data frames in which the QoS subfield of the subtype subfield is equal to 1.

[0089] The HT control field is present in QoS data, QoS null, and management frames as determined by the +HTC subfield of the frame control field.

[0090] The frame body field is a variable length field that contains information specific to individual frame types and subtypes. It may include one or more MSDUs or MMPDUs. The minimum length of the frame body is 0 octets.

[0091] The FCS field contains a 32-bit Cyclic Redundancy Check (CRC) code. The FCS field value is calculated over all of the fields of the MAC header and the frame body field.

[0092] FIG. 4 illustrates an example 400 of a Quality of Service (QoS) null frame indicating buffer status information. A QoS null frame refers to a QoS data frame with an empty frame body. A QoS null frame includes a QoS control field and an optional HT control field which may contain a buffer status report (BSR) control subfield. A QoS null frame indicating buffer status information may be transmitted by a STA to an AP.

[0093] The QoS control field may include a traffic identifier (TID) subfield, an ack policy indicator subfield, and a queue size subfield (or a transmission opportunity (TXOP) duration requested subfield). The TID subfield identifies the TC or TS of traffic for which a TXOP is being requested, through the setting of the TXOP duration requested or queue size subfield. The encoding of the TID subfield depends on the access policy (e.g., Allowed value 0 to 7 for enhanced distributed channel access (EDCA) access policy to identify user priority for either TC or TS).

[0094] The ack policy indicator subfield, together with other information, identifies the acknowledgment policy followed upon delivery of the MPDU (e.g., normal ack, implicit block ack request, no ack, block ack, etc.)

[0095] The queue size subfield is an 8-bit field that indicates the amount of buffered traffic for a given TC or TS at the STA for transmission to the AP identified by the receiver address of the frame containing the subfield. The queue size subfield is present in QoS null frames sent by a STA when bit 4 of the QoS control field is set to 1. The AP may use information contained in the queue size subfield to determine t TXOP duration assigned to the STA or to determine the uplink (UL) resources assigned to the STA.

[0096] In a frame sent by or to a non-High Efficiency (non-HE) STA, the following rules may apply to the queue size value:

[0097] The queue size value is the approximate total size, rounded up to the nearest multiple of 256 octets and expressed in units of 256 octets, of all MSDUs and A-MSDUs buffered at the STA (excluding the MSDU or A-MSDU contained in the present QoS Data frame) in the delivery queue used for MSDUs and A-MSDUs with TID values equal to the value indicated in the TID subfield of the QoS Control field.

[0098] A queue size value of 0 is used solely to indicate the absence of any buffered traffic in the queue used for the specified TID.

[0099] A queue size value of 254 is used for all sizes greater than 64 768 octets.

[0100] A queue size value of 255 is used to indicate an unspecified or unknown size.

[0101] In a frame sent by an HE STA to an HE AP, the following rules may apply to the queue size value.

[0102] The queue size value, QS, is the approximate total size in octets, of all MSDUs and A- MSDUs buffered at the STA (including the MSDUs or A-MSDUs contained in the same PSDU as the frame containing the queue size subfield) in the delivery queue used for MSDUs and A-MSDUs with TID values equal to the value indicated in the TID subfield of the QoS control field.

[0103] The queue size subfield includes a scaling factor subfield in bits B14-B15 of the QoS control field and an unsealed value, UV, in bits B8-B13 of the QoS control field. The scaling factor subfield provides the scaling factor, on.

[0104] A STA obtains the queue size, QS, from a received QoS control field, which contains a scaling factor, SF, and an unsealed value, UV, as follows: QS =

[0105] 16 * UV, if SF is equal to 0;

[0106] 1024 + 256 x UV, ifSF is equal to 1;

[0107] 17408 + 2048 x UV, ifSF is equal to 2;

[0108] 148 480 + 32 768 x UV, ifSF is equal to 3 and UV is less than 62;

[0109] > 2 147328, if SF equal to is 3 and UV is equal to 62;

[0110] Unspecified or Unknown, if SF is equal to 3 and UV is equal to 63.

[0111] The TXOP duration requested subfield, which may be included instead of the queue size subfield, indicates the duration, in units of 32 microseconds (us), that the sending STA determines it needs for its next TXOP for the specified TID. The TXOP duration requested subfield is set to 0 to indicate that no TXOP is requested for the specified TID in the current service period (SP). The TXOP duration requested subfield is set to a nonzero value to indicate a requested TXOP duration in the range of 32 us to 8160 us in increments of 32 us.

[0112] The HT control field may include a BSR control subfield which may contain buffer status information used for UL MU operation. The BSR control subfield may be formed from an access category index (ACI) bitmap subfield, a delta TID subfield, an ACI high subfield, a scaling factor subfield, a queue size high subfield, and a queue size all subfield of the HT control field.

[0113] The ACI bitmap subfield indicates the access categories for which buffer status is reported (e.g., BO: best effort (AC BE), Bl: background (AC BK), B2: video (AC VI), B3: voice (AC_VO), etc.). Each bit of the ACI bitmap subfield is set to 1 to indicate that the buffer status of the corresponding AC is included in the queue size all subfield, and set to 0 otherwise, except that if the ACI bitmap subfield is 0 and the delta TID subfield is 3, then the buffer status of all 8 TIDs is included.

[0114] The delta TID subfield, together with the values of the ACI bitmap subfield, indicate the number of TIDs for which the STA is reporting the buffer status.

[0115] The ACI high subfield indicates the ACI of the AC for which the BSR is indicated in the queue size high subfield. The ACI to AC mapping is defined as ACI value 0 mapping to AC BE, ACI value 1 mapping to AC BK, ACI value 2 mapping to AC VI, and ACI value 3 mapping to AC VO.

[0116] The scaling factor subfield indicates the unit SF, in octets, of the queue size high and queue size all subfields.

[0117] The queue size high subfield indicates the amount of buffered traffic, in units of SF octets, for the AC identified by the ACI high subfield, that is intended for the STA identified by the receiver address of the frame containing the BSR control subfield.

[0118] The queue size all subfield indicates the amount of buffered traffic, in units of SF octets, for all Acs identified by the ACI Bitmap subfield, that is intended for the STA identified by the receiver address of the frame containing the BSR control subfield.

[0119] The queue size values in the queue size high and queue size all subfields are the total sizes, rounded up to the nearest multiple of SF octets, of all MSDUs and A-MSDUs buffered at the STA (including the MSDUs or A-MSDUs contained in the same PSDU as the frame containing the BSR control subfield) in delivery queues used for MSDUs and A-MSDUs associated with AC(s) that are specified in the ACI high and ACI bitmap subfields, respectively.

[0120] A queue size value of 254 in the queue size high and queue size all subfields indicates that the amount of buffered traffic is greater than 254 x SF octets. A queue size value of 255 in the queue size high and queue size all subfields indicates that the amount of buffered traffic is an unspecified or unknown size. The queue size value of QoS data frames containing fragments may remain constant even if the amount of queued traffic changes as successive fragments are transmitted.

[0121] MAC service provides peer entities with the ability to exchange MSDUs. To support this service, a local MAC uses the underlying PHY-level service to transport the MSDUs to a peer MAC entity. Such asynchronous MSDU transport is performed on a connectionless basis.

[0122] FIG. 5 illustrates an example format of a PPDU. As shown, the PPDU may include a PHY preamble, a PHY header, a PSDU, and tail and padding bits.

[0123] The PSDU may include one or more MPDUs, such as a QoS data frame, an MMPDU, a MAC control frame, or a QoS null frame. In the case of an MPDU carrying a QoS data frame, the frame body of the MPDU may include a MSDU or an A-MSDU.

[0124] By default, MSDU transport is on a best-effort basis. That is, there is no guarantee that a transmitted MSDU will be delivered successfully. However, the QoS facility uses a traffic identifier (TID) to specify differentiated services on a per-MSDU basis.

[0125] A STA may differentiate MSDU delivery according to designated traffic category (TC) or traffic stream (TS) of individual MSDUs. The MAC sublayer entities determine a user priority (UP) for an MSDU based on a TID value provided with the MSDU. The QoS facility supports eight UP values. The UP values range from 0 to 7 and form an ordered sequence of priorities, with 1 being the lowest value, 7 the highest value, and 0 falling between 2 and 3.

[0126] An MSDU with a particular UP is said to belong to a traffic category with that UP. The UP may be provided with each MSDU at the medium access control service access point (MAC SAP) directly in an UP parameter. An aggregate MPDU (A-MPDU) may include MPDUs with different TID values.

[0127] A STA may deliver buffer status reports (BSRs) to assist an AP in allocating UU MU resources. The STA may either implicitly deliver BSRs in the QoS control field or BSR control subfield of any frame transmitted to the AP (unsolicited BSR) or explicitly deliver BSRs in a frame sent to the AP in response to a BSRP Trigger frame (solicited BSR).

[0128] The buffer status reported in the QoS control field includes a queue size value for a given TID. The buffer status reported in the BSR control field includes an ACI bitmap, delta TID, a high priority AC, and two queue sizes. A STA may report buffer status to the AP, in the QoS control field, of transmitted QoS null frames and QoS data frames and, in the BSR control subfield (if present), of transmitted QoS null frames, QoS data frames, and management frames as defined below.

[0129] The STA may report the queue size for a given TID in the queue size subfield of the QoS control field of transmitted QoS data frames or QoS null frames; the STA may set the queue size subfield to 255 to indicate an unknown / unspecified queue size for that TID. The STA may aggregate multiple QoS data frames or QoS null frames in an A-MPDU to report the queue size for different TIDs.

[0130] The STA may report buffer status in the BSR control subfield of transmitted frames if the AP has indicated its support for receiving the BSR control subfield.

[0131] A High-Efficiency (HE) STA may report the queue size for a preferred AC, indicated by the ACI high subfield, in the queue size high subfield of the BSR control subfield. The STA may set the queue size high subfield to 255 to indicate an unknown / unspecified queue size forthat AC.

[0132] A HE STA may report the queue size for ACs indicated by the ACI bitmap subfield in the queue size all subfield of the BSR control subfield. The STA may set the queue size all subfield to 255 to indicate an unknown / unspecified BSR for those ACs.

[0133] Triggered TXOP sharing (TXS) is a technique introduced in the IEEE 802. 1 Ibe standard amendment. TXS allows an AP to allocate a time duration within an obtained TXOP to a STA for transmitting one or more non-trigger-based (non-TB) PPDUs. For the TXS procedure, the AP may transmit a multi-user request-to-send (MU-RTS) trigger frame with a triggered TXOP sharing mode subfield set to a non-zero value. The MU-RTS trigger frame is a trigger frame for triggering CTS frame(s) from multiple users. An MU-RTS trigger frame with the triggered TXOP sharing mode subfield set to a non-zero value is called an MU-RTS TXS trigger (MRTT) frame.

[0134] In an example, when the triggered TXOP sharing mode subfield is set to 1, the STA may transmit the one or more non-TB PPDUs to the AP during the allocated time duration. In an example, when the triggered TXOP sharing mode subfield is set to 2, the STA may transmit the one or more non- TB PPDUs to the AP or a peer STA during the allocated time duration. The peer STA may be a STA with a connection for peer-to-peer (P2P) communication or direct communication with the STA. In an example, the direct wireless link is established according to the tunneled direct link setup (TDLS) protocol.

[0135] FIG. 6 illustrates an example MRTT frame 600 which may be used in a TXS procedure. As shown in FIG. 6, example MRTT frame 600 may comprise a frame control field, a duration field, a receiver address (RA) field, a transmitter address (TA) field, a common info field, a user info list field, a padding field, and / or frame check sequence (FCS) field.

[0136] In an example, the common info field may be a high-efficiency (HE) variant common info field or an extremely high throughput (EHT) variant common info field. An EHT variant common info field may comprise, as shown in FIG. 6, one or more of the following subfields: trigger type, UL length, more TF, CS required, UL BW, GI and HE / EHT-LTF Type / Triggered TXOP sharing mode, number of HE / EHT-LTF symbols, LDPC extra symbol segment, AP Tx Power, Pre-FEC padding factor, PE disambiguity, UL spatial reuse, HE / EHT Pl 60, special user info field flag, EHT reserved, reserved, or trigger dependent common info.

[0137] The trigger type subfield indicates that frame 600 is an MRTT frame.

[0138] The GI and HE / EHT-LTF Type / Triggered TXOP sharing mode subfield may include a triggered TXOP sharing mode subfield. In an example, the triggered TXOP sharing mode subfield may be set to a non-zero value (e.g., 1 or 2). In an example, the triggered TXOP sharing mode subfield may be set to 1. As such, the triggered TXOP sharing mode subfield may indicate that a STA indicated by an AID 12 subfield of a user info field (of the user info list field) may transmit one or more non-TB PPDUs to the AP during a time indicated in the allocation duration subfield of the user info field. In another example, the triggered TXOP sharing mode subfield may be set to 2. As such, the triggered TXOP sharing mode subfield may indicate that a STA indicated by an AID 12 subfield of a user info field (of the user info list field) may transmit one or more non-TB PPDUs to the AP or to a peer STA during the time indicated by the allocation duration subfield of the user info field. In an example, the peer STA may be a STA with a connection for P2P communication or direct communication with the STA.

[0139] The user info list field may include one or more user info fields. In an example, an EHT variant user info field may comprise, as shown in FIG. 6, one or more of the following subfields: AID 12, RU allocation, allocation duration, reserved, or PS160.

[0140] The AID 12 subfield may indicate an association identifier (AID) of a STA that may use a time indicated by the allocation duration subfield.

[0141] The RU allocation subfield may indicate the location and size of the RU allocated for a STA indicated by the AID 12 subfield.

[0142] The allocation duration subfield may indicate a time allocated by an AP transmitting MRTT frame 600. The allocated time may be a portion a TXOP obtained by the AP. In an example embodiment, the allocation duration subfield may indicate a first time period.

[0143] FIG. 7 illustrates an example 700 of a TXS procedure (Mode =1). As shown in FIG. 7, the TXS procedure may begin by an AP 710 transmitting an MRTT frame 720 to a STA 711. MRTT frame 720 may allocate a portion of a TXOP obtained by AP 710 to STA 711 and may indicate a TXS mode equal to 1. STA 711 receiving MRTT frame 720 may use the allocated time to transmit one or more non-TB PPDUs to AP 710. The one or more non-TB PPDUs may comprise a data frame, a control frame, a management frame, or an action frame.

[0144] In an example, MRTT frame 720 may comprise a triggered TXOP sharing mode subfield that indicates the TXS mode and / or subfield that indicates a first time period corresponding to the allocated time. In an example, the first time period may be set to a value of X microseconds (us).

[0145] STA 711 may respond to MRTT frame 720 by transmitting a CTS frame 721 to AP 710. Subsequently, STA 711 may transmit non-TB PPDUs 722, 724 comprising one or more data frame to AP 710 during the first time period indicated in MRTT frame 720. In an example, AP 710 may transmit one or more Block Ack (BA) frames 723, 725 in response to the one or more data frames contained in non-TB PPDUs 722, 724 received from STA 711.

[0146] FIG. 8 illustrates an example 800 of a TXS procedure (Mode =2). As shown in FIG. 8, the TXS procedure may begin by an AP 810 transmitting an MRTT frame 820 to a STA 811. MRTT frame 820 may allocate a portion of a TXOP obtained by AP 810 to STA 811 and may indicate a TXS mode equal to 2. STA 811 receiving MRTT frame 820 may use the allocated time to transmit one or more non-TB PPDUs to STA 812. The one or more non-TB PPDUs may comprise a data frame, a control frame, a management frame, or an action frame.

[0147] In an example, MRTT frame 820 may comprise a triggered TXOP sharing mode subfield that indicates the TXS mode and / or subfield that indicates a first time period corresponding to the allocated time. In an example, the first time period may be set to a value of X microseconds (us).

[0148] STA 811 may respond to MRTT frame 820 by transmitting a CTS frame 821 to AP 810. Subsequently, STA 811 may transmit non-TB PPDUs 822, 824 comprising one or more data frame to STA 818 during the first time period indicated in MRTT frame 720. In an example, STA 812 may transmit one or more BA frames 823, 825 in response to the one or more data frames contained in non-TB PPDUs 822, 824 received from STA 811.

[0149] FIG. 9 illustrates an example multi-AP network 900. Example multi-AP network 900 may be a multi-AP network in accordance with the Wi-Fi Alliance standard specification for multi-AP networks. As shown in FIG. 9, multi-AP network 900 may include a multi-AP controller 902 and a plurality of multi-AP groups (or multi-AP sets) 904, 906, and 908.

[0150] Multi-AP controller 902 may be a logical entity that implements logic for controlling the APs in multi-AP network 900. Multi-AP controller 902 may receive capability information and measurements from the APs and may trigger AP control commands and operations on the APs. Multi-AP controller 902 may also provide onboarding functionality to onboard and provision APs onto multi-AP network 900.

[0151] Multi-AP groups 904, 906, and 908 may each include a plurality of APs. APs in a multi- AP group are in communication range of each other. However, the APs in a multi-AP group are not required to have the same primary channel. As used herein, the primary channel for an AP refers to a default channel that the AP monitors for management frames and / or uses to transmit beacon frames. For a STA associated with an AP, the primary channel refers to the primary channel of the AP, which is advertised through the AP’s beacon frames.

[0152] In one approach, one of the APs in a multi-AP group may be designated as a master AP. The designation of the master AP may be done by AP controller 902 or by the APs of the multi-AP group. The master AP of a multi-AP group may be fixed or may change over time among the APs of the multi- AP group. An AP that is not the master AP of the multi-AP group is known as a slave AP. In one approach, a master AP may be in communication range of all slave APs of the multi-AP group and vice versa. A slave AP may not be in communication range of another slave AP of the multi-AP group. In one approach, APs in a multi-AP group may coordinate with each other, including coordinating transmissions within the multi-AP group. One aspect of coordination may include coordination to perform multi-AP transmissions within the multi-AP group. As used herein, a multi-AP transmission is a transmission event in which multiple APs (of a multi-AP group or a multi-AP network) transmit simultaneously over a time period. The time period of simultaneous AP transmission may be a continuous period. The multi-AP transmission may use different transmission techniques, such as Coordinated OFDMA, Coordinated Spatial Reuse, Joint Transmission and Reception, Coordinated Beamforming and Coordinated Time Division Multiple Access (TDMA), or a combination of two or more of the aforementioned techniques.

[0153] Multi-AP group coordination may be enabled by the AP controller and / or by the master AP of the multi-AP group. In one approach, the AP controller and / or the master AP may control time and / or frequency sharing in a TXOP. For example, when one of the APs (e.g., the master AP) in the multi-AP group obtains a TXOP, the AP controller and / or the master AP may control how time / frequency resources of the TXOP are to be shared with other APs of the multi-AP group. In an implementation, the AP of the multi-AP group that obtains a TXOP becomes the master AP of the multi-AP group. The master AP may then share a portion of its obtained TXOP (which may be the entire TXOP) with one or more other APs of the multi-AP group.

[0154] OFDMA is a transmission technique introduced in the IEEE 802. 1 lax standard amendment. OFDMA provides a multiple access scheme that allows multiple STAs to transmit frames simultaneously using non-overlapping (orthogonal) frequency subcarriers.

[0155] In coordinated OFDMA (C-OFDMA), it is envisaged that an AP (e.g., master AP) may coordinate a multi-AP transmission by multiple APs (which may or may not include the coordinating AP) by assigning each of the multiple APs a respective frequency resource (e.g., channel / subchannel) of available frequency resources for a transmission time period. The coordinating AP may further indicate transmit parameters (e.g., PPDU format, guard interval, symbol duration, etc.) for the multi-AP transmission. The multiple APs access the assigned frequency resources simultaneously, using OFDMA, during the transmission time period. FIG. 10 illustrates C-OFDMA as a multi-AP channel access, compared with Enhanced Distributed Channel Access (EDCA). As shown in FIG. 10, in EDCA, channel access by multiple APs (e.g., API, AP2) may occur in consecutive time periods (e.g., TXOPs). During a given channel access, the channel (e.g., 80 MHz) in its entirety may be used by a single AP. In contrast, in C-OFDMA, access by multiple APs (multi-AP channel access) may take place in a same time period (e.g., TXOP) over orthogonal frequency resources. For example, as shown in FIG. 10, an 80 MHz channel may be divided into four non-overlapping 20 MHz channels, each assigned to a respective AP of the multiple APs. The multiple APs may transmit, simultaneously in the same time period, to respective associated STAs, for example.

[0156] It is anticipated that future IEEE 802.11 standard drafts extend the existing TXS procedure described above to APs. In such a procedure (hereinafter referred to as an inter-AP TXS procedure), an AP (hereinafter referred to as a sharing AP) may allocate to one or more other APs (hereinafter referred to as shared AP(s)) a portion of time of an obtained TXOP. The shared AP(s) may use the allocated time to communicate with associated STA(s) and / or with the sharing AP without being triggered by the sharing AP. The sharing AP may or may not be part of the APs communicating during the allocated time.

[0157] FIG. 11 is an example 1100 that illustrates an inter- AP TXS procedure. As shown in FIG. 11, example 1100 includes APs 1102, 1104, 1106, and 1108. In an example APs 1102, 1104, 1106, and 1108 may form a multi-AP group as described above in FIG. 9. In an example, AP 1102 may be a master AP of the multi-AP group and APs 1104, 1106, and 1108 may be slave APs of the multi-AP group. However, the inter-AP TXS procedure described herein is not limited to use in a multi-AP group and / or in the presence of a master AP and of slave APs.

[0158] In example 1100, AP 1102 may obtain a TXOP. Subsequently, AP 1102 may initiate an inter-AP TXS operation by transmitting an MRTT frame 1110 to AP 1104. MRTT frame 1110 may have a similar format as MU-RTS trigger frame 600 described above. In an example, MRTT frame 1110 may indicate an identifier of AP 1104 (e.g., in an AID 12 subfield of a user info field of MRTT frame 1110) and an allocated time 1132 (e.g., in an allocation duration subfield of the user info field) of the TXOP. Additionally, MRTT frame 1110 may indicate a TXS mode (e.g., in a triggered TXOP sharing mode subfield of common info field of MRTT frame 1110). The TXS mode may indicate whether AP 1104 shall communicate with AP 1102 only during allocated time 1132 (e.g., when the TXS mode is set to 1) or whether AP 1104 may communicate with AP 1102 or another STA (e.g., an associated non-AP STA or another AP STA) during allocated time 1132.

[0159] AP 1104 may respond to MRTT frame 1110 by transmitting a CTS frame 1112 to AP 1102. Subsequently, e.g., a short interframe space (SIFS) after transmitting CTS frame 1112, AP 1104 may proceed, without trigger from AP 1102, to use allocated time 1132 for communication in accordance with the TXS mode indicated in MRTT frame 1110. In example 1100, the TXS mode may permit AP 1104 to communicate with AP 1102 or with another STA during allocated time 1132. As such, as shown in FIG. 11, AP 1104 may use allocated time 1132 to transmit a (non-TB) downlink (DL) PPDU 1114 to an associated STA (not shown in FIG. 11) and to receive an uplink (UL) PPDU 1116 from an associated STA (not shown in FIG. 11).

[0160] In an example, with time remaining of the TXOP, AP 1102 may initiate another inter-AP TXS operation by transmitting an MRTT frame 1118 to APs 1106 and 1108. MRTT frame 1118 may have a similar format as MU-RTS trigger frame 600 described above. In an example, MRTT frame 1118 may indicate identifiers of APs 1106 and 1108 (e.g., in respective AID12 subfields of respective user info fields of MRTT frame 1118) and an allocated time 1134 (e.g., in respective allocation duration subfields of the user info fields) of the TXOP. Additionally, MRTT frame 1118 may indicate a TXS mode (e.g., in a triggered TXOP sharing mode subfield of common info field of MRTT frame 1118). The TXS mode may indicate whether APs 1106 and 1108 shall communicate with AP 1102 only during allocated time 1134 (e.g., when the TXS mode is set to 1) or whether APs 1106 and 1108 may communicate with AP 1102 or other STAs (e.g., an associated non-AP STA or another AP STA) during allocated time 1134.

[0161] APs 1106 and 1108 may respond to MRTT frame 1118 by transmitting CTS frames 1120 and 1122 respectively to AP 1102. Subsequently, e.g., a SIFS after transmitting respectively CTS frames 1120 and 1122, APs 1106 and 1108 may proceed, without trigger from AP 1102, to use allocated time 1134 for communication in accordance with the TXS mode indicated in MRTT frame 1118. In example 1100, the TXS mode may permit APs 1106 and 1108 to communicate with AP 1102 or with another STA during allocated time 1134. As such, as shown in FIG. 11, AP 1104 may use allocated time 1134 to transmit a (non-TB) DL PPDU 1124 to an associated STA (not shown in FIG. 11) and to receive an UL PPDU 1128 from an associated STA (not shown in FIG. 11). Similarly, AP 1108 may use allocated time 1134 to transmit a (non-TB) DL PPDU 1126 to an associated STA (not shown in FIG. 11) and to receive an UL PPDU 1130 from an associated STA (not shown in FIG. 11).

[0162] In an example, C-OFDMA may be used for the transmission of DL PPDUs 1124 and 1126 and UL PPDUs 1128 and 1130. Specifically, AP 1102 may assign APs 1106 and 1108 respective frequency resources that are orthogonal to each other for allocated time 1134. For example, AP 1102 may divide an 80 MHz channel into two non-overlapping 40 MHz channels, each assigned to a respective one of APs 1106 and 1108. In an example, the frequency resources assigned to an AP are indicated in an RU allocation subfield of a user info field (that indicates the identifier of the AP) of MRTT frame 1118. DL PPDU 1124 and UL PPDU 1128 may thus be transmitted on RUs that are orthogonal to the RUs used for the transmission of DL PPDU 1126 and UL PPDU 1130.

[0163] FIG. 12 illustrates an example PPDU 1200 which may be used for a downlink DL PPDU or an UL PPDU. For example, PPDU 1200 may be an embodiment of DL PPDU 1114, 1124, or 1126 or of UL PPDU 1116, 1128, or 1130 described in FIG. 11. PPDU 1200 may be an Ultra-High Reliability (UHR) PPDU which may be used by devices conforming to the IEEE 802.1 Ibn standard amendment. Such devices may operate in the 2.4, 5, and 6 GHz bands. In an implementation, PPDU 1200 may be transmitted over a bandwidth of up to 320MHz. PPDU 1200 may be used by a device for both single user (SU) and multi-user (MU) transmissions. It is noted that UHR may be called a different name (e.g., Ultra- High Throughput (UHR) or Ultra-High Efficiency (UHE)).

[0164] As shown in FIG. 12, PPDU 1200 includes an non-HT Short Training field (L-STF), a non-HT Long Training field (L-LTF), a non-High-Throughput (non-HT) Signal field (L-SIG), a non-HT Repeated Signal field (RL-SIG), a Universal Signal field (U-SIG), a UHR Signal field (UHR-SIG), a UHR Short Training field (UHR-STF) field, one or more UHR Long Training field (UHR-LTF), a data field, and a Packet Extension (PE) field.

[0165] The L-STF is used by a receiver of PPDU 1200 to synchronize with the carrier frequency and frame timing of a transmitter of PPDU 1200 and to adjust the receiver signal gain. The L-LTF is used by the receiver of PPDU 1200 to estimate channel coefficients in order to equalize the channel response (e.g., amplitude and phase distortion) in both Signal fields (L-SIG, RL-SIG, U-SIG, UHR-SIG) and the data field of PPDU 1200.

[0166] The L-SIG and RL-SIG contain parameters needed to demodulate the data field. The L- SIG may be equalized using the channel coefficients estimated using the L-LTF and demodulated to obtain the demodulation parameters of the data field.

[0167] The U-SIG ensures forward compatibility of PPDU 1200. This means that any future PPDUs that are backward compatible to IEEE 802.1 Ibn will contain the same U-SIG field. Because of this, IEEE 802. 1 Ibn conforming devices will be able to understand at least in part a PPDU developed in a future amendment, provided those amendments contain the U-SIG field as well.

[0168] The UHR-SIG contains indications per STA of resource unit (RU) allocations. A receiving STA may use the indications in the UHR-SIG to locate its payload in the data field of PPDU 1200.

[0169] The L-SIG, RL-SIG, U-SIG, and UHR-SIG fields may be considered as a PHY Header of PPDU 1200.

[0170] The UHR-STF and the one or more UHR-LTFs are used by the receiver of PPDU 1200 to estimate channel coefficients in order to equalize the channel response (e.g., amplitude and phase distortion) in the data field of PPDU 1200.

[0171] The data field contains one or more payloads carried by PPDU 1200. The one or more payloads may comprise MPDUs.

[0172] The PE field is an extension of PPDU 1200 designed to give the receiver of PPDU 1200 sufficient time to respond after receiving PPDU 1200.

[0173] FIGs. 13a and 13b show an example 1300 that illustrates a problem that may arise in the inter-AP TXS procedure illustrated in FIG. 11. As shown in FIGs. 13a and 13b, example 1300 includes APs 1102, 1106, and 1108 described above. As in example 1100, AP 1102 initiates an inter-AP TXS operation by transmitting MRTT frame 1118 to APs 1106 and 1108. MRTT frame 1118 may have a similar format as MU-RTS trigger frame 600 described above. In an example, MRTT frame 1118 may indicate identifiers of APs 1106 and 1108 (e.g., in respective AID12 subfields of respective user info fields of MRTT frame 1118) and allocated time 1134 (e.g., in respective allocation duration subfields of the user info fields) of the TXOP. Additionally, MRTT frame 1118 may indicate a TXS mode (e.g., in a triggered TXOP sharing mode subfield of common info field of MRTT frame 1118). The TXS mode may indicate whether APs 1106 and 1108 shall communicate with AP 1102 only during allocated time 1134 (e.g., when the TXS mode is set to 1) or whether APs 1106 and 1108 may communicate with AP 1102 or other STAs (e.g., an associated non-AP STA or another AP STA) during allocated time 1134.

[0174] APs 1106 and 1108 respond to MRTT frame 1118 by transmitting CTS frames 1120 and 1122 respectively to AP 1102. Subsequently, e.g., a SIFS after transmitting respectively CTS frames 1120 and 1122, APs 1106 and 1108 may proceed, without trigger from AP 1102, to use allocated time 1134 for communication in accordance with the TXS mode indicated in MRTT frame 1118. In example 1300, the TXS mode may permit APs 1106 and 1108 to communicate with AP 1102 or with another STA during allocated time 1134. As such, as shown in FIGs. 13a and 13b, AP 1104 may use allocated time 1134 to transmit a DL PPDU 1302 to an associated STA (not shown in FIG. 13a) and to receive an UL PPDU 1306 from an associated STA (not shown in FIG. 13b). Similarly, AP 1108 may use allocated time 1134 to transmit a DL PPDU 1304 to an associated STA (not shown in FIG. 13a) and to receive an UL PPDU 1308 from an associated STA (not shown in FIG. 13b).

[0175] In an example, C-OFDMA may be used for the transmission of DL PPDUs 1302 and 1304 and UL PPDUs 1128 and 1130. Specifically, AP 1102 may assign APs 1106 and 1108 respective frequency resources that are orthogonal to each other for allocated time 1134. For example, AP 1102 may divide an 80 MHz channel into two non-overlapping 40 MHz channels, each assigned to a respective one of APs 1106 and 1108. In an example, the frequency resources assigned to an AP are indicated in an RU allocation subfield of a user info field (that indicates the identifier of the AP) of MRTT frame 1118. DL PPDU 1302 and UL PPDU 1306 may thus be transmitted on RUs that are orthogonal to the RUs used for the transmission of DL PPDU 1304 and UL PPDU 1308.

[0176] As APs 1106 and 1108 are not triggered by AP 1102 during allocated time 1134, AP 1102 may indicate in MRTT frame 1118 a first time period, within allocated time 1134, for the DL transmission and / or a second time period, within allocated time 1134, for the UL transmission. APs 1106 and 1108 may use the first time period to transmit DL PPDUs 1302 and 1304, respectively. Similarly, APs 1106 and 1108 may use the second time period to receive UL PPDUs 1306 and 1308, respectively. The first and second time periods aid in the time -alignment of DL PPDUs 1302 and 1304 and of UL PPDUs 1306 and 1308, as shown in FIG. 13b, and reduces potential OFDM symbol misalignment at a receiver receiving one of PPDUs 1302, 1304, 1306, or 1308. OFDM symbol misalignment results in the boundaries of OFDM symbols received over a first portion (e.g., a first 40 MHz) of the channel and the boundaries of corresponding OFDM symbols received over a second portion (e.g., a second 40 MHz) of the channel being out of sync. As the receiver typically receives and processes the entire channel (in the absence of a dedicated receive filter per sub-channel), the receiver may be unable to decode a PPDU where the OFDM symbol misalignment occurs.

[0177] The existing inter- AP TXS procedure does not define how AP 1102 may set the first time period and / or the second time period. In an implementation, AP 1102 may set the first time period and / or the second time period equally or according to a pre-defined configuration (e.g., recurring fixed DL and / or UL time periods within allocated time 1134). This, however, may not match the actual DL / UL communication needs or requirements of APs 1106 and 1108 and may result in suboptimal DL / UL resource allocations. For example, in the case of a DL transmission, as shown in FIG. 13a, AP 1102 may set the first time period for the DL transmission in a manner that substantially exceeds the DL transmission needs of APs 1106 and 1108. As such, both APs 1106 and 1108 may have to resort to padding in order to align the transmission periods of DL PPDUs 1302 and 1304 with the first time period. For example, each of DL PDDUs 1302 and 1304 may be composed of a first part (e.g., pre-UHR modulation fields such as L-STF, L-LTF, L-SIG, RL-SIG, U-SIG, and UHR-SIG) and a second part (e.g., UHR modulation fields such as UHR-STF, UHR-LTF, data field, and PE field). For example, in an UL case, as shown in FIG. 13b, AP 1102 may set the second time period for the UL transmission in a manner that substantially exceeds the UL transmission needs of APs 1106 and 1108. As such, the respective STAs (not shown in FIG. 13b) transmitting to APs 1106 and 1108 may have to resort to padding in order to align the transmission periods of UL PPDUs 1306 and 1308 with the second time period. For example, each of UL PDDUs 1306 and 1308 may be composed of a first part (e.g., pre-UHR modulation fields such as L-STF, L-LTF, L-SIG, RL-SIG, U-SIG, and UHR-SIG) and a second part (e.g., UHR modulation fields such as UHR-STF, UHR-LTF, data field, and PE field). APs 1106 and 1108 may insert padding bits into the second parts (e.g., the data field) of DL PPDUs 1302 and 1304, respectively. This may result in a suboptimal utilization of allocated time 1134, and particularly the first time period allocated for DL transmission. In another example for an UL situation, the first part may include a UHR preamble part (e.g., pre-UHR modulation fields (L-STF, L-LTF, L-SIG, RL-SIG, U-SIG, and UHR-SIG) and UHR-STF and UHR-LTF) and the second part may include a data field and a PE field. The respective STAs transmitting to APs 1106 and 1108 may insert padding bits into the second parts (e.g., the data field) of UL PPDUs 1306 and 1308, respectively. This may result in a suboptimal utilization of allocated time 1134, and particularly the second time period allocated for UL transmission.

[0178] Embodiments of the present disclosure, as further described below, address the abovediscussed problem that may arise in inter- AP TXS. In one aspect, a first AP may transmit to a second AP a first frame indicating a DL transmission parameter for a DL transmission. The first AP may be a shared AP and the second AP may be a sharing AP. The DL transmission may be a multi -AP transmission coordinated / initiated by the second AP. The multi-AP transmission may be performed within an allocated time of a TXOP obtained by the second AP. The DL transmission parameter may include a parameter that the second AP may use to determine DL traffic needs of the first AP for the DL transmission. In embodiments, the DL transmission parameter may include / indicate one or more of a modulation and coding scheme (MCS), a bandwidth (BW) size, a resource unit (RU) size, a PPDU type, or a number of spatial streams for the DL transmission. In embodiments, the DL transmission parameter may include / indicate DL time resource allocation information and / or DL frequency resource allocation information for the DL transmission. The DL transmission may comprise a DL PPDU. In another aspect, the first AP may transmit to the second AP a buffer status report (BSR) indicating an amount of DL traffic buffered at the first AP. In an embodiment, the first frame may comprise the BSR. The second AP may transmit to the first AP a second frame indicating a time period for the DL transmission, determined based on the DL transmission parameter. The second AP may transmit a DL PPDU for the DL transmission during the time period.

[0179] In another aspect, a first AP may transmit to a second AP a first frame indicating an amount of UL traffic for a STA associated with the first AP. The amount of UL traffic for the STA may correspond to the amount of traffic buffered at the STA for uplink transmission to the first AP. The first AP may be a shared AP and the second AP may be a sharing AP. The first AP may receive from the second AP a second frame indicating a time period, based on the amount of UL traffic, for an UL transmission from the STA to the first AP. The UL transmission may be a part of a C-OFDMA UL transmission. The C-OFDMA UL transmission may comprise the UL transmission and a further UL transmission. The further UL transmission may be from another STA to the second AP or to a third AP. The C-OFDMA UL transmission may be performed within an allocated time of a TXOP obtained by the second AP. In an embodiment, the first frame may further indicate an amount of UL traffic for a further STA associated with the first AP. In another embodiment, the first frame may further indicate an UL transmission parameter for the UL transmission. The time period may be further based on the UL transmission parameter. The UL transmission parameter may include / indicate one or more of a modulation and coding scheme (MCS), a bandwidth (BW) size, a resource unit (RU) size, a PPDU type, or a number of spatial streams for the UL transmission. In another aspect, the first AP may receive from the second AP a second frame indicating a duration of an UL PPDU for the UL transmission from the STA to the first AP and a transmission parameter for the UL PPDU. In a further aspect, the first AP may transmit to the second AP a first frame indicating UL time resource information for an UL transmission from a STA to the first AP and / or UL frequency resource information for the UL transmission. The first AP receives from the second AP a second frame indicating a duration of an UL PPDU for the UL transmission, determined based on the UL time resource information and / or the UL frequency resource information.

[0180] Further aspects and details of embodiments are presented in the example embodiments described below.

[0181] FIGs. 14a and 14b illustrate examples 1400 of an inter- AP TXS procedure according to an embodiment. As shown in FIG. 14a, example 1400 includes APs 1402, 1404, and 1406. In an example APs 1402, 1404, and 1406 may form a multi-AP group as described above in FIG. 9. In an example, AP 1402 may be a sharing AP (or a master AP) of the multi-AP group and APs 1404 and 1406 may be shared APs (or slave APs) of the multi-AP group. However, the inter-AP TXS procedure described herein is not limited to use in a multi-AP group and / or in the presence of a sharing AP (or a master AP) and of shared AP (or slave APs).

[0182] As shown in FIG. 14a, example 1400 may begin with AP 1404 transmitting a frame 1408 to AP 1402. In an embodiment, frame 1408 may indicate a DL transmission parameter for a DL transmission. The DL transmission may be a multi-AP transmission. The multi-AP transmission may be performed within an allocated time of a TXOP obtained by AP 1402. The multi-AP transmission may be performed in the context of an inter-AP TXS procedure as described above. The multi-AP transmission may or may not comprise AP 1402. The multi-AP transmission may be a coordinated DL PPDU transmission by AP 1402 and one or more of APs 1404 and 1406. Alternatively, as shown in FIG. 14, the multi-AP transmission may be a coordinated DL PPDU transmission by APs 1404 and 1406. The coordinated DL PPDU transmission may comprise a C-OFDMA transmission, a coordinated spatial reuse (C-SR) transmission, a coordinated beamforming (C-BF), or a coordinated joint transmission. Frame 1502 may comprise a buffer status report poll (BSRP) trigger frame, a basic trigger frame, a poll frame, or a soliciting frame. As shown in FIG. 14b, in an embodiment which relates to a UL scenario, frame 1408 may indicate an amount of UL traffic for a first STA (not shown in FIG. 14) associated with AP 1404. The amount of UL traffic for the first STA may correspond to the amount of traffic buffered at the first STA for uplink transmission to AP 1404. In an embodiment, the amount of UL traffic for the first STA may correspond to an uplink queue size at the first STA. The uplink queue size may be for one or more TID. In another embodiment, frame 1408 may further indicate an amount of UL traffic for a further STA (not shown in FIG. 14) associated with AP 140.

[0183] The DL transmission parameter may include a parameter that AP 1402 may use to determine DL traffic needs of AP 1404 for the DL transmission. In an embodiment, the DL transmission parameter may include / indicate one or more of an MCS, a bandwidth (BW) size, an RU size, a PPDU type, or a number of spatial streams (Nss) for the DL transmission. In an embodiment, the DL transmission parameter may include / indicate DL time resource allocation information and / or DL frequency resource allocation information for the DL transmission. In an embodiment relating to UL transmissions, frame 1408 may, alternatively or additionally, indicate an UL transmission parameter for an UL transmission from the first STA to AP 1404. The UL transmission may be a part of a coordinated UL transmission. The coordinated UL transmission may comprise the UL transmission from the first STA to AP 1404 and a further UL transmission. The further UL transmission may be from another STA (not shown in FIG. 14) to AP 1402 or to AP 1406. The coordinated UL transmission may be performed within an allocated time of a TXOP obtained by AP 1402. The coordinated UL transmission may be performed in the context of an inter- AP TXS procedure as described above. The coordinated UL transmission may or may not comprise AP 1402. The coordinated UL PPDU transmission may comprise a C-OFDMA transmission, a coordinated spatial reuse (C-SR) transmission, a coordinated beamforming (C-BF), or a coordinated joint transmission.

[0184] In an embodiment, where the DL (or UL as applicable) transmission parameter includes / indicates an MCS, frame 1408 may include an MCS index. In another embodiment, in addition to the MCS index, frame 1408 may indicate a PPDU type / format (e.g., HT, HE, VHT, EHT, UHR, etc.). In a further embodiment, frame 1408 may further indicate a requested bandwidth (e.g., 20 MHz, 40 MHz, etc.) for the DL / UL transmission. In an embodiment, frame 1408 may indicate a plurality of MCS indices for a plurality of bandwidth values for the DL / UL transmission.

[0185] In an embodiment, where the DL / UL transmission parameter includes / indicates DL time resource allocation information, frame 1408 may include a duration for the DL / UL transmission. The duration may be a requested duration for the DL / UL transmission.

[0186] In an embodiment, where the DL / UL transmission parameter includes / indicates DL / UL frequency resource allocation information, frame 1408 may include an RU size / type (e.g., 26-tone RU, 52-tone RU, etc.) for the DL / UL transmission. The RU size / type may be a requested RU size / type for the DL / UL transmission.

[0187] In an embodiment, the DL / UL transmission parameter may be determined by AP 1404. The DL transmission parameter may be selected by AP 1404 from a plurality of DL / UL transmission parameters. The plurality of DL transmission parameters may be pre -configured in AP 1404. In an example, the DL / UL transmission parameter may be suggested by AP 1404 for the DL / UL transmission. For example, the DL / UL transmission parameter may be a preferred parameter for the DL / UL transmission.

[0188] In an embodiment, frame 1408 may be a QoS data / null frame or an action frame, for example. When frame 1408 is a QoS data / null frame, the QoS data / null frame may comprise an aggregated control (A-Control) field comprising the DL transmission parameter as illustrated in FIG. 16a, for example. When frame 1408 is an action frame, the action frame may comprise an information element (or an information field) comprising the DL transmission parameter. In a UL scenario, as illustrated in Fig. 16b, the aggregated control (A-Control) field comprising the amount of UL traffic and / or the UL transmission parameter and when frame 1408 is an action frame, the action frame may comprise an information element (or an information field) comprising the amount of UL traffic and / or the UL transmission parameter The information element is illustrated in FIG. 17a (DL) and FIG. 17b (UL) for example.

[0189] In an embodiment, frame 1408 may further comprise a DL or an UL buffer status report (BSR). The DL / UL BSR may indicate an amount of traffic buffered for DL transmission at AP 1404 (for the DL case) or for UL at the first STA (for the UL case). The DL BSR may indicate the amount of buffered traffic as described with reference to FIG. 4 above (e.g., in a queue size subfield). In an implementation, the buffered traffic may correspond to all traffic buffered for DL transmission at AP 1404 (DL case) or at the first STA (UL case). In another implementation, the buffered traffic may correspond to the traffic buffered for DL transmission to a particular STA that AP 1404 intends to serve by the DL transmission for a DL case. Additionally, or alternatively, the buffered traffic may correspond to the traffic buffered for DL / UL transmission for a particular access category (AC) or TID.

[0190] In an example, example 1400 may also include AP 1406 transmitting a frame 1410 to AP 1402. Frame 1410 may be transmitted before or after frame 1408. In an embodiment, for a DL case, frame 1410 may indicate a DL transmission parameter for the DL transmission. In an embodiment, for a UL case, frame 1410 may indicate an amount of UL traffic for a second STA (not shown in FIG. 14) associated with AP I406Frame 1410 is similar to frame 1408. The same description herein regarding to frame 1408 applies to frame 1410.

[0191] Subsequently, AP 1402 may obtain a TXOP and may initiate an inter- AP TXS operation by transmitting an MRTT frame 1412 to APs 1404 and 1406. MRTT frame 1412 may have a similar format as MU-RTS trigger frame 600 described above. In an example, MRTT frame 1412 may indicate identifiers of APs 1404 and 1406 (e.g., in respective AID12 subfields of respective user info fields of MRTT frame 1412) and an allocated time 1414 (e.g., in respective allocation duration subfields of the user info fields) of the TXOP. Additionally, MRTT frame 1412 may indicate a TXS mode (e.g., in a triggered TXOP sharing mode subfield of common info field of MRTT frame 1412). The TXS mode may indicate whether APs 1404 and 1406 shall communicate with AP 1402 only during allocated time 1414 (e.g., when the TXS mode is set to 1) or whether APs 1404 and 1406 may communicate with AP 1402 or other STAs (e.g., an associated non-AP STA or another AP STA) during allocated time 1414.

[0192] In an embodiment, for a DL case, MRTT frame 1412 may further indicate a time period 1428, within allocated time 1414, for a DL transmission. The DL transmission may be a multi-AP transmission. The multi-AP transmission may be performed within an allocated time of a TXOP obtained by AP 1402. The multi-AP transmission may be performed in the context of an inter- AP TXS procedure as described above. The multi-AP transmission may or may not comprise AP 1402. The multi-AP transmission may be a coordinated DL PPDU transmission by AP 1402 and one or more of APs 1404 and 1406. Alternatively, as shown in FIG. 14, the multi-AP transmission may be a coordinated DL PPDU transmission by APs 1404 and 1406. The coordinated DL PPDU transmission may comprise a C- OFDMA transmission, a coordinated spatial reuse (C-SR) transmission, a coordinated beamforming (C- BF), or a coordinated joint transmission. Frame 1502 may comprise a buffer status report poll (BSRP) trigger frame, a basic trigger frame, a poll frame, or a soliciting frame. In an embodiment, the DL transmission may be in response to frames 1408 and 1410 from APs 1404 and 1406, respectively, signaling DL transmission parameters for a DL transmission.

[0193] In an embodiment for an UL case, MRTT frame 1412 may further indicate a time period 1428, within allocated time 1414, for an UL transmission. The UL transmission may be a part of a coordinated UL transmission. The coordinated UL transmission may comprise the UL transmission from the first STA to AP 1404 and a further UL transmission. The further UL transmission may be from another STA to AP 1402 or to AP 1406. The coordinated UL transmission may be performed within an allocated time of a TXOP obtained by AP 1402. The coordinated UL transmission may be performed in the context of an inter-AP TXS procedure as described above. The coordinated UL transmission may or may not comprise AP 1402. The coordinated UL PPDU transmission may comprise a C-OFDMA transmission, a coordinated spatial reuse (C-SR) transmission, a coordinated beamforming (C-BF), or a coordinated joint transmission. In an embodiment, the UL transmission may be in response to frames 1408 and 1410 from APs 1404 and 1406, respectively, each signaling an amount of UL traffic and / or an UL transmission parameter for an UL transmission.

[0194] In an embodiment, AP 1402 may determine time period 1428 based on the DL / UL transmission parameter indicated in frame 1408 and / or the DL / UL transmission parameter indicated in frame 1410.

[0195] In an embodiment, AP 1402 may determine a first data rate for the DL / UL transmission for AP 1404 based on the DL / UL transmission parameter indicated in frame 1408. In an embodiment, AP 1402 may further determine a second data rate for the DL transmission for AP 1406 based on the DL / UL transmission parameter indicated in frame 1410. For example, AP 1402 may determine the first / second data rate based on an MCS index, alone or in combination with a PPDU type / format, a bandwidth value, and / or a number of spatial streams, indicated in frame 1408 / 1410. For example, the first / second data rate may be determined using an MCS table provided in the IEEE 802. 11 standard.

[0196] In an embodiment, using the first data rate and the amount of traffic (e.g., indicated in frame 1408), AP 1402 may determine a first duration. In the case of a DL transmission, this may be the amount of traffic buffered for transmission at AP 1404. In an embodiment, using the second data rate and the amount of traffic buffered (for DL transmission at AP 1406) (e.g., indicated in frame 1410), AP 1402 may determine a second duration. In an embodiment, AP 1402 may select the larger of the first duration and the second duration as time period 1428. As such, time period 1428 is guaranteed to be sufficiently long to accommodate the DL / UL traffic requirements of, or indicated by, both APs 1404 and 1406. In another embodiment, time period 1428 may be subject to a maximum PPDU duration. That is, time period 1428 may not exceed the maximum PPDU duration. In another embodiment, an AP (AP 1420 for DL and AP 1402 for UL) may select the shorter of the first duration and the second duration as time period 1428. This ensures that time period 1428 can be fully utilized for DL / UL transmission of data traffic by / to both APs 1404 and 1406. In other words, for DL, neither of APs 1404 and 1406 may need to add padding into its respective DL PPDU to align its transmission period with time period 1428. Similarly, for UL, neither of UL PPDUs 1420 and 1422 may need to include padding bits to align its transmission period with time period 1428.

[0197] In an embodiment, MRTT frame 1412 may comprise a duration of time period 1428. In an embodiment, a start time of time period 1428 may be determined based on MRTT frame 1412. For example, the start time of time period 1428 may be 2 SIFS plus a CTS frame transmission time (plus, optionally, the duration of a time period for DL transmission of allocated time 1414) from the time of receiving MRTT frame 1412. An end time of time period 1428 may be determined based on the start time and the indicated duration.

[0198] In another embodiment, MRTT frame 1412 may comprise a start time and an end time of time period 1428, a start time and a duration of time period 1428, or a duration and an end time of time period 1428. In such an embodiment, the start time of time period 1428 may not be based on MRTT frame 1412.

[0199] In another embodiment, MRTT frame 1412 may indicate time period 1428 as a segment of allocated time 1414. For example, MRTT frame 1412 may indicate that time period 1428 corresponds to a first / last half of allocated time 1414, or a first / last X microseconds of allocated time 1414, etc.

[0200] In another embodiment, MRTT frame 1412 may indicate time period 1428 by indicating a number of OFDM symbols (of a given duration) to be transmitted during time period 1428.

[0201] In other embodiments, AP 1402 may initiate the inter- AP TXS operation by transmitting a frame other than an MRTT frame. For example, AP 1402 may use a multi-AP trigger frame for initiating the inter-AP TXS operation. The multi-AP trigger frame may comprise / indicate the same information described above as comprised / indicated in MRTT frame 1412. APs 1404 and 1406 may or may not respond to or acknowledge the multi-AP trigger frame from AP 1402.

[0202] As shown in FIG. 14a (for DL), APs 1404 and 1406 may respond to MRTT frame 1412 by transmitting CTS frames 1416 and 1418 respectively to AP 1402. Subsequently, e.g., a SIFS after transmitting respectively CTS frames 1416 and 1418, APs 1404 and 1406 may proceed, without trigger from AP 1402, to use allocated time 1414 for communication in accordance with the TXS mode indicated in MRTT frame 1412 and with account for time period 1428. In example 1400, the TXS mode may permit APs 1404 and 1406 to communicate with AP 1402 or with another STA during allocated time 1414. As such, as shown in FIG. 14, AP 1404 may use time period 1428 of allocated time 1414 to transmit a (non-TB) DL PPDU 1420 to an associated STA (not shown in FIG. 14a). AP 1404 may use the DL transmission parameter indicated in frame 1408 in the transmission of DL PPDU 1420. DL PPDU 1420 has a transmission duration equal to time period 1428. Similarly, AP 1406 may use time period 1428 to transmit a (non-TB) DL PPDU 1422 to an associated STA (not shown in FIG. 14a). AP 1404 may use the DL transmission parameter indicated in frame 1410 in the transmission of DL PPDU 1422. DL PPDU 1422 has a transmission duration equal to time period 1428. In example 1400, AP 1406 may insert padding bits into a payload of DL PPDU 1422 to make sure that the transmission duration of PPDU 1422 is equal to time period 1428. However, with the time period 1428 set by AP 1402 as described above, AP 1404 may not need to insert any padding bits into DL PPDU 1420 and may utilize time period 1428 in its entirety for transmission of buffered DL data. Utilization of allocated time 1414, and particularly time period 1428 allocated for DL transmission, is therefore increased.

[0203] As shown in FIG. 14b for UL, APs 1404 and 1406 may respond to MRTT frame 1412 by transmitting CTS frames 1416 and 1418 respectively to AP 1402. Subsequently, e.g., a SIFS after transmitting respectively CTS frames 1416 and 1418, APs 1404 and 1406 may proceed, without trigger from AP 1402, to use allocated time 1414 for communication in accordance with the TXS mode indicated in MRTT frame 1412 and with account for time period 1428. In example 1400, the TXS mode may permit APs 1404 and 1406 to communicate with AP 1402 or with another STA during allocated time 1414. As such, in an example, as shown in FIG. 14, AP 1404 may use a first portion of allocated time 1414 to transmit a (non-TB) DL PPDU 1420 to an associated STA (not shown in FIG. 14b). Similarly, AP 1406 may use the first portion of allocated time 1414 to transmit a (non-TB) DL PPDU 1422 to an associated STA (not shown in FIG. 14). Subsequently, AP 1404 may use first time period 1428 to receive an UL PPDU 1424 from the first STA (not shown in FIG. 14b) associated with AP 1404. Similarly, AP 1406 may use first time period 1428 to receive an UL PPDU 1426 from the second STA (not shown in FIG. 14b) associated with AP 1406. In an example, AP 1404 may transmit a frame to the first STA during the first portion of allocated time 1414 to solicit / trigger UL PPDU 1424. In an example, AP 1406 may transmit a frame to the second STA during the first portion of allocated time 1414 to solicit / trigger UL PPDU 1426. In another example, a start time of first time period 1428 may be aligned with a start time of allocated time 1414. As such, the UL transmission may not be preceded by a DL transmission. The first STA and the second STA may be triggered by MRTT frame 1412, for example, to transmit respectively UL PPDUs 1424 and 1426.

[0204] In an example relating to DL, AP 1404 may use a remaining duration of allocated time 1414, in accordance with any indication in MRTT frame 1412, to receive an UL PPDU 1424 from an associated STA (not shown in FIG. 14). In an example, AP 1406 may use a remaining duration of allocated time 1414, in accordance with any indication in MRTT frame 1412, to receive an UL PPDU 1426 from an associated STA (not shown in FIG. 14).

[0205] In an embodiment relating to UL, the first STA may use the UL transmission parameter indicated in frame 1408 in the transmission of UL PPDU 1424. UL PPDU 1424 has a transmission duration equal to time period 1428. In an embodiment, the second STA may use the UL transmission parameter indicated in frame 1410 in the transmission of UL PPDU 1426. UL PPDU 1426 has a transmission duration equal to time period 1428. In example 1400, the second STA may insert padding bits into a payload of UL PPDU 1426 to make sure that the transmission duration of PPDU 1426 is equal to time period 1428. However, with the time period 1428 set by AP 1402 as described above, the first STA may not need to insert any padding bits into UL PPDU 1424 and may utilize time period 1428 in its entirety for transmission of buffered UL data to AP 1404. Utilization of allocated time 1414, and particularly time period 1428 allocated for UL transmission, is therefore increased.

[0206] In an example, C-OFDMA may be used for the transmission of DL PPDUs 1420 and 1422 and UL PPDUs 1424 and 1426. Specifically, AP 1402 may assign APs 1404 and 1406 respective frequency resources that are orthogonal to each other for allocated time 1414. For example, AP 1402 may divide an 80 MHz channel into two non-overlapping 40 MHz channels, each assigned to a respective one of APs 1404 and 1406. In an example, the frequency resources assigned to an AP are indicated in an RU allocation subfield of a user info field (that indicates the identifier of the AP) of MRTT frame 1412. DL PPDU 1420 and UL PPDU 1424 may thus be transmitted on RUs that are orthogonal to the RUs used for the transmission of DL PPDU 1422 and UL PPDU 1426.

[0207] In another embodiment (not shown in FIG. 14a), AP 1404 may include in frame 1408 the DL BSR but may not include in frame 1408 the DL transmission parameter. Similarly, AP 1406 may include in frame 1410 the DL BSR but may not include in frame 1410 the DL transmission parameter. AP 1402 may determine time period 1428 for the DL transmission based on one or both of the DL BSRs received from APs 1404 and 1406. In an example, AP 1402 may further determine a DL transmission parameter for the DL transmission for one or more of APs 1404 and 1406 based on one or both of the DL BSRs received from APs 1404 and 1406. In embodiments, the DL transmission parameter may include an MCS, DL time resource allocation information, DL frequency resource allocation information, or a number of spatial streams for the DL transmission. AP 1402 may include the determined DL transmission parameter(s) in MRTT frame 1412. By selecting time period 1428 and the DL transmission parameter(s) based on the DL BSR(s), AP 1402 can ensure that at least one of APs 1404 and 1406 fully utilize time period 1428 for DL transmission of data traffic (i.e., without padding). In another embodiment, for UL (not shown in FIG. 14b), AP 1404 may include in frame 1408 the amount of UL traffic for the first STA but may not include in frame 1408 the UL transmission parameter for the UL transmission from the first STA to AP 1404. Similarly, AP 1406 may include in frame 1410 the amount of UL traffic for the second STA but may not include in frame 1410 the UL transmission parameter for the UL transmission from the second STA to AP 1406. AP 1402 may determine time period 1428 based on one or both of the amounts of UL traffic for the first STA and the amount of UL traffic for the second STA. In an example, AP 1402 may further determine an UL transmission parameter for the UL transmission to AP 1404 and / or the UL transmission to AP 1406, based on one or more of the amount of UL traffic for the first STA and the amount of UL traffic for the second STA. In embodiments, the UL transmission parameter may include an MCS, UL time resource allocation information, UL frequency resource allocation information, or a number of spatial streams for the UL transmission. AP 1402 may include the determined UL transmission parameter(s) in MRTT frame 1412. By selecting time period 1428 and the UL transmission parameter(s) based on one or more of the amount of UL traffic for the first STA and the amount of UL traffic for the second STA, AP 1402 can ensure that at least one of the first STA and the second STA fully utilize time period 1428 for UL transmission of data traffic (i.e., without padding).

[0208] FIGs. 15a and 15b illustrate an examples 1500 of an inter-AP TXS procedure according to another embodiment. As shown in FIGs. 15 and 15b, example 1500 also includes APs 1402, 1404, and 1406 described above with reference to FIG. 14. In an example APs 1402, 1404, and 1406 may form a multi -AP group as described above in FIG. 9. In an example, AP 1402 may be a sharing AP (or a master AP) of the multi -AP group and APs 1404 and 1406 may be shared APs (or slave APs) of the multi -AP group. However, the inter-AP TXS procedure described herein is not limited to use in a multi -AP group and / or in the presence of a sharing AP (or master AP) and of shared APs (or slave APs).

[0209] As shown in FIG. 15a, example 1500 (for DL) may begin with AP 1402 transmitting a frame 1502 to AP 1404 and / or AP 1406. In an embodiment, frame 1502 solicits a DL BSR from AP 1404 and / or AP 1406 for a DL transmission. The DL transmission may be a multi-AP transmission. The multi- AP transmission may be performed within an allocated time of a TXOP obtained by AP 1402. The multi- AP transmission may be performed in the context of an inter-AP TXS procedure as described above. The multi-AP transmission may or may not comprise AP 1402. The multi-AP transmission may be a coordinated DL PPDU transmission by AP 1402 and one or more of APs 1404 and 1406. Alternatively, as shown in FIG. 15, the multi-AP transmission may be a coordinated DL PPDU transmission by APs 1404 and 1406. The coordinated DL PPDU transmission may comprise a C-OFDMA transmission, a coordinated spatial reuse (C-SR) transmission, a coordinated beamforming (C-BF), or a coordinated joint transmission. Frame 1502 may comprise a buffer status report poll (BSRP) trigger frame, a basic trigger frame, a poll frame, or a soliciting frame.

[0210] As shown in FIG. 15b, example 1500 (for UL) may begin with AP 1402 transmitting a frame 1502 to AP 1404 and / or AP 1406. In an embodiment, frame 1502 solicits an UL BSR from AP 1404 and / or AP 1406 a coordinated UL transmission. The coordinated UL transmission may comprise an UL transmission from a first STA (not shown in FIG. 15) to AP 1404 and a further UL transmission. The further UL transmission may be from another STA (not shown in FIG. 15) to AP 1402 or to AP 1406. The coordinated UL transmission may be performed within an allocated time of a TXOP obtained by AP 1402. The coordinated UL transmission may be performed in the context of an inter-AP TXS procedure as described above. The coordinated UL transmission may or may not comprise AP 1402. The coordinated UL PPDU transmission may comprise a C-OFDMA transmission, a coordinated spatial reuse (C-SR) transmission, a coordinated beamforming (C-BF), or a coordinated joint transmission. Frame 1502 may comprise a buffer status report poll (BSRP) trigger frame, a basic trigger frame, a poll frame, or a soliciting frame.

[0211] In an embodiment relating to DL, AP 1404 may respond to frame 1502 by transmitting a frame 1504 to AP 1402. In an embodiment, frame 1504 comprises a DL BSR for the DL transmission. The DL BSR may indicate an amount of traffic buffered for DL transmission at AP 1404. The DL BSR may indicate the amount of buffered traffic as described with reference to FIG. 4 above (e.g., in a queue size subfield). In an implementation, the buffered traffic may correspond to all traffic buffered for DL transmission at AP 1404. In another implementation, the buffered traffic may correspond to the traffic buffered for DL transmission to a particular STA that AP 1404 intends to serve by the DL transmission. Additionally, or alternatively, the buffered traffic may correspond to the traffic buffered for DL transmission for a particular access category (AC) or TID.

[0212] In an embodiment relating to DL, frame 1504 may further indicate a DL transmission parameter for the DL transmission. The DL transmission parameter may include a parameter that AP 1402 may use to determine DL traffic needs of AP 1404 for the DL transmission. In an embodiment, the DL transmission parameter may include / indicate one or more of an MCS, a bandwidth (BW) size, an RU size, a PPDU type, or a number of spatial streams (Nss) for the DL transmission. In an embodiment, the DL transmission parameter may include / indicate DL time resource allocation information and / or DL frequency resource allocation information for the DL transmission.

[0213] In an embodiment relating to UL, AP 1404 may respond to frame 1502 by transmitting a frame 1504 to AP 1402. In an embodiment, frame 1504 may indicate an amount of UL traffic for a first STA (not shown in FIG. 15) associated with AP 1404. The amount of UL traffic for the first STA may correspond to the amount of traffic buffered at the first STA for uplink transmission to AP 1404. In an embodiment, the amount of UL traffic for the first STA may correspond to an uplink queue size at the first STA. The uplink queue size may be for one or more TID. In another embodiment, frame 1504 may further indicate an amount of UL traffic for a further STA (not shown in FIG. 15) associated with AP 1404.

[0214] In an embodiment relating to UL, frame 1504 may, alternatively or additionally, indicate an UL transmission parameter for an UL transmission from the first STA to AP 1404. The UL transmission may be a part of the coordinated UL transmission. In an embodiment relating to DL, where the DL transmission parameter includes / indicates an MCS, frame 1504 may include an MCS index. In another embodiment, in addition to the MCS index, frame 1504 may indicate a PPDU type / format (e.g., HT, HE, VHT, EHT, UHR, etc.). In a further embodiment, frame 1504 may further indicate a requested bandwidth (e.g., 20 MHz, 40 MHz, etc.) for the DL transmission. In an embodiment, frame 1504 may indicate a plurality of MCS indices for a plurality of bandwidth values for the DL transmission.

[0215] In an embodiment relating to UL, where the UL transmission parameter includes / indicates an MCS, frame 1504 may include an MCS index. In another embodiment, in addition to the MCS index, frame 1504 may indicate a PPDU type / format (e.g., HT, HE, VHT, EHT, UHR, etc.). In a further embodiment, frame 1504 may further indicate a requested bandwidth (e.g., 20 MHz, 40 MHz, etc.) for the UL transmission. In an embodiment, frame 1408 may indicate a plurality of MCS indices for a plurality of bandwidth values for the UL transmission.

[0216] In an embodiment, where the DL / UL transmission parameter includes / indicates DL / UL time resource allocation information, frame 1504 may include a duration for the DL / UL transmission. The duration may be a requested duration for the DL / UL transmission.

[0217] In an embodiment, where the DL / UL transmission parameter includes / indicates DL frequency resource allocation information, frame 1504 may include an RU size / type (e.g., 26-tone RU, 52-tone RU, etc.) for the DL / UL transmission. The RU size / type may be a requested RU size / type for the DL / UL transmission.

[0218] In an embodiment, the DL / UL transmission parameter may be determined by AP 1404. The DL / UL transmission parameter may be selected by AP 1404 from a plurality of DLUL transmission parameters. The plurality of DL / UL transmission parameters may be pre -configured in AP 1404. In an example, the DL / UL transmission parameter may be suggested by AP 1404 for the DL / UL transmission. Lor example, the DL / UL transmission parameter may be a preferred parameter for the DL / UL transmission.

[0219] In an embodiment, for DL, frame 1504 may be a QoS data / null frame or an action frame, for example. When frame 1504 is a QoS data / null frame, the QoS data / null frame may comprise an aggregated control (A-Control) field comprising the DL transmission parameter as illustrated in PIG. 16a, for example. When frame 1504 is an action frame, the action frame may comprise an information element (or an information field) comprising the DL transmission parameter. The information element is illustrated in FIG. 17a, for example.

[0220] For UL, in an embodiment, frame 1504 may be a QoS data / null frame or an action frame, for example. When frame 1504 is a QoS data / null frame, the QoS data / null frame may comprise an aggregated control (A-Control) field comprising the amount of UL traffic and / or the UL transmission parameter as illustrated in FIG. 16b, for example. When frame 1504 is an action frame, the action frame may comprise an information element (or an information field) comprising the amount of UL traffic and / or the UL transmission parameter. The information element is illustrated in FIG. 17b, for example. In an embodiment relating to UL, frame 1504 may comprise an UL BSR. The UL BSR may indicate the amount of UL traffic for the first STA. The UL BSR may indicate the amount of buffered traffic as described with reference to FIG. 4 above (e.g., in a queue size subfield). In an implementation, the buffered traffic may correspond to all traffic buffered for UL transmission at the first STA. In another implementation, the buffered traffic may correspond to the traffic buffered for UL transmission for a particular access category (AC) or TID.

[0221] In an example, for DL, example 1500 may also include AP 1406 transmitting a frame 1506 to AP 1402. Frame 1506 may be transmitted before or after frame 1504. In an embodiment, frame 1506 may indicate a DL transmission parameter for the DL transmission. Frame 1506 is similar to frame 1504. The same description herein regarding to frame 1504 applies to frame 1506.

[0222] In an example, for UL, example 1500 may also include AP 1406 transmitting a frame 1506 to AP 1402. Frame 1506 may be transmitted before or after frame 1504. In an embodiment, frame 1506 may indicate an amount of UL traffic for a second STA (not shown in FIG. 14) associated with AP 1406. Frame 1506 is similar to frame 1504. The same description herein regarding frame 1506 applies to frame 1504.

[0223] Subsequently, AP 1402 may obtain a TXOP and may initiate an inter- AP TXS operation by transmitting an MRTT frame 1508 to APs 1404 and 1406. MRTT frame 1508 may have a similar format as MU-RTS trigger frame 600 described above. In an example, MRTT frame 1508 may indicate identifiers of APs 1404 and 1406 (e.g., in respective AID12 subfields of respective user info fields of MRTT frame 1508) and an allocated time 1510 (e.g., in respective allocation duration subfields of the user info fields) of the TXOP. Additionally, MRTT frame 1508 may indicate a TXS mode (e.g., in a triggered TXOP sharing mode subfield of common info field of MRTT frame 1508). The TXS mode may indicate whether APs 1404 and 1406 shall communicate with AP 1402 only during allocated time 1510 (e.g., when the TXS mode is set to 1) or whether APs 1404 and 1406 may communicate with AP 1402 or other STAs (e.g., an associated non-AP STA or another AP STA) during allocated time 1510.

[0224] In an embodiment, MRTT frame 1508 may further indicate a time period 1524, within allocated time 1510, for the DL or coordinated UL transmission.

[0225] In an embodiment, AP 1402 may determine time period 1524 based on the DL / UL transmission parameter indicated in frame 1504 and / or the DL / UL transmission parameter indicated in frame 1506.

[0226] In an embodiment, AP 1402 may determine a first data rate for the DL / UL transmission for AP 1404 based on the DL / UL transmission parameter indicated in frame 1504. In an embodiment, AP 1402 may further determine a second data rate for the DL transmission for AP 1406 based on the DL / UL transmission parameter indicated in frame 1506. For example, AP 1402 may determine the first / second data rate based on an MCS index, alone or in combination with a PPDU type / format, a bandwidth value, and / or a number of spatial streams, indicated in frame 1504 / 1506. For example, the first / second data rate may be determined using an MCS table provided in the IEEE 802. 11 standard. In an embodiment for DL, using the first data rate and the amount of traffic buffered for DL transmission at AP 1404 (e.g., indicated in frame 1 04), AP 1402 may determine a first duration for the DL transmission. In an embodiment, using the second data rate and the amount of traffic buffered for DL transmission at AP 1406 (e.g., indicated in frame 1506), AP 1402 may determine a second duration for the DL transmission. In an embodiment, AP 1402 may select the larger of the first duration and the second duration as time period 1524. As such, time period 1524 is guaranteed to be sufficiently long to accommodate the DL traffic requirements of both APs 1404 and 1406. In another embodiment, time period 1524 may be subject to a maximum PPDU duration. That is, time period 1524 may not exceed the maximum PPDU duration. In another embodiment, AP 1402 may select the shorter of the first duration and the second duration as time period 1524. This ensures that time period 1524 can be fully utilized for DL transmission of data traffic by both APs 1404 and 1406. That is, neither of APs 1404 and 1406 may need to add padding into its respective DL PPDU to align its transmission period with time period 1524.

[0227] In an embodiment for UL, using the first data rate and the amount of UL traffic indicated in frame 1504, AP 1402 may determine a first duration. In an embodiment, using the second data rate and the amount of traffic indicated in frame 1506, AP 1402 may determine a second duration. In an embodiment, AP 1402 may select the larger of the first duration and the second duration as time period 1524. As such, time period 1524 is guaranteed to be sufficiently long to accommodate the UL traffic requirements indicated by both APs 1404 and 1406. In another embodiment, time period 1524 may be subject to a maximum PPDU duration. That is, time period 1524 may not exceed the maximum PPDU duration. In another embodiment, AP 1402 may select the shorter of the first duration and the second duration as time period 1524. This ensures that time period 1524 can be fully utilized for UL transmission of data traffic to both APs 1404 and 1406. In other words, neither of UL PPDUs 1520 and 1522 may need to include padding bits to align its transmission period with time period 1524.

[0228] In an embodiment, MRTT frame 1508 may comprise a duration of time period 1524. In an embodiment, a start time of time period 1524 may be determined based on MRTT frame 1508. For example, the start time of time period 1524 may be 2 SIFS plus a CTS frame transmission time (plus, optionally, the duration of a time period for DL transmission of allocated time 1510, in the case of a UL transmission) from the time of receiving MRTT frame 1508. An end time of time period 1524 may be determined based on the start time and the indicated duration.

[0229] In another embodiment, MRTT frame 1508 may comprise a start time and an end time of time period 1524, a start time and a duration of time period 1524, or a duration and an end time of time period 1524. In such an embodiment, the start time of time period 1524 may not be based on MRTT frame 1508.

[0230] In another embodiment, MRTT frame 1508 may indicate time period 1524 as a segment of allocated time 1510. For example, MRTT frame 1508 may indicate that time period 1524 corresponds to a first / last half of allocated time 1510, or a first / last X microseconds of allocated time 1510, etc. In another embodiment, MRTT frame 1508 may indicate time period 1524 by indicating a number of OFDM symbols (of a given duration) to be transmitted during time period 1524.

[0231] In other embodiments, AP 1402 may initiate the inter- AP TXS operation by transmitting a frame other than an MRTT frame. For example, AP 1402 may use a multi-AP trigger frame for initiating the inter-AP TXS operation. The multi-AP trigger frame may comprise / indicate the same information described above as comprised / indicated in MRTT frame 1508. APs 1404 and 1406 may or may not respond to or acknowledge the multi-AP trigger frame from AP 1402.

[0232] As shown in FIG. 15a (for DL), APs 1404 and 1406 may respond to MRTT frame 1508 by transmitting CTS frames 1512 and 1514 respectively to AP 1402. Subsequently, e.g., a SIFS after transmitting respectively CTS frames 1512 and 1514, APs 1404 and 1406 may proceed, without trigger from AP 1402, to use allocated time 1510 for communication in accordance with the TXS mode indicated in MRTT frame 1508 and with account for time period 1524. In example 1500, the TXS mode may permit APs 1404 and 1406 to communicate with AP 1402 or with another STA during allocated time 1510. As such, as shown in FIG. 15a, AP 1404 may use time period 1524 of allocated time 1510 to transmit a (non-TB) DL PPDU 1516 to an associated STA (not shown in FIG. 15a). AP 1404 may use the DL transmission parameter indicated in frame 1504 in the transmission of DL PPDU 1516. DL PPDU 1516 has a transmission duration equal to time period 1524. Similarly, AP 1406 may use time period 1524 to transmit a (non-TB) DL PPDU 1518 to an associated STA (not shown in FIG. 15a). AP 1404 may use the DL transmission parameter indicated in frame 1506 in the transmission of DL PPDU 1518. DL PPDU 1518 has a transmission duration equal to time period 1524. In example 1500, AP 1406 may insert padding bits into a payload of DL PPDU 1518 to make sure that the transmission duration of PPDU 1518 is equal to time period 1524. However, with the time period 1524 set by AP 1402 as described above, AP 1404 may not need to insert any padding bits into DL PPDU 1516 and may utilize time period 1524 in its entirety for transmission of buffered DL data. Utilization of allocated time 1510, and particularly time period 1524 allocated for DL transmission, is therefore increased.

[0233] As shown in FIG. 15b (for UL), APs 1404 and 1406 may respond to MRTT frame 1508 by transmitting CTS frames 1512 and 1514 respectively to AP 1402. Subsequently, e.g., a SIFS after transmitting respectively CTS frames 1512 and 1514, APs 1404 and 1406 may proceed, without trigger from AP 1402, to use allocated time 1510 for communication in accordance with the TXS mode indicated in MRTT frame 1508 and with account for time period 1524. In example 1500, the TXS mode may permit APs 1404 and 1406 to communicate with AP 1402 or with another STA during allocated time 1510. As such, in an example, as shown in FIG. 15b, AP 1404 may use a first portion of allocated time 1510 to transmit a (non-TB) DL PPDU 1516 to an associated STA (not shown in FIG. 15b). Similarly, AP 1406 may use the first portion of allocated time 1510 to transmit a (non-TB) DL PPDU 1518 to an associated STA (not shown in FIG. 15). Subsequently, AP 1404 may use first time period 1524 to receive an UL PPDU 1520 from the first STA (not shown in FIG. 15b) associated with AP 1404. Similarly, AP 1406 may use first time period 1524 to receive an UL PPDU 1522 from the second STA (not shown in FIG. 15b) associated with AP 1406. In an example, AP 1404 may transmit a frame to the first STA during the first portion of allocated time 1510 to solicit / trigger UL PPDU 1520. In an example, AP 1406 may transmit a frame to the second STA during the first portion of allocated time 1510 to solicit / trigger UL PPDU 1522. In another example, a start time of first time period 1524 may be aligned with a start time of allocated time 1510. As such, the UL transmission may not be preceded by a DL transmission. The first STA and the second STA may be triggered by MRTT frame 1508, for example, to transmit respectively UL PPDUs 1520 and 1522.

[0234] In an example relating to DL, AP 1404 may use a remaining duration of allocated time 1510, in accordance with any indication in MRTT frame 1508, to receive an UL PPDU 1520 from an associated STA (not shown in FIG. 15). In an example, AP 1406 may use a remaining duration of allocated time 1510, in accordance with any indication in MRTT frame 1508, to receive an UL PPDU 1522 from an associated STA (not shown in FIG. 15).

[0235] In an embodiment relating to UL, the first STA may use the UL transmission parameter indicated in frame 1504 in the transmission of UL PPDU 1520. UL PPDU 1520 has a transmission duration equal to time period 1524. In an embodiment, the second STA may use the UL transmission parameter indicated in frame 1506 in the transmission of UL PPDU 1522. UL PPDU 1522 has a transmission duration equal to time period 1524. In example 1500, the second STA may insert padding bits into a payload of UL PPDU 1522 to make sure that the transmission duration of PPDU 1522 is equal to time period 1524. However, with the time period 1524 set by AP 1402 as described above, the first STA may not need to insert any padding bits into UL PPDU 1520 and may utilize time period 1524 in its entirety for transmission of buffered UL data to AP 1404. Utilization of allocated time 1510, and particularly time period 1524 allocated for UL transmission, is therefore increased.

[0236] In an example, C-OFDMA may be used for the transmission of DL PPDUs 1516 and 1518 and UL PPDUs 1520 and 1522. Specifically, AP 1402 may assign APs 1404 and 1406 respective frequency resources that are orthogonal to each other for allocated time 1510. For example, AP 1402 may divide an 80 MHz channel into two non-overlapping 40 MHz channels, each assigned to a respective one of APs 1404 and 1406. In an example, the frequency resources assigned to an AP are indicated in an RU allocation subfield of a user info field (that indicates the identifier of the AP) of MRTT frame 1508. DL PPDU 1516 and UL PPDU 1520 may thus be transmitted on RUs that are orthogonal to the RUs used for the transmission of DL PPDU 1518 and UL PPDU 1522.

[0237] In another embodiment relating to DL (not shown in FIG. 15a), AP 1404 may include in frame 1504 the DL BSR but may not include in frame 1504 the DL transmission parameter. Similarly, AP 1406 may include in frame 1506 the DL BSR but may not include in frame 1506 the DL transmission parameter. AP 1402 may determine time period 1524 for the DL transmission based on one or both of the DL BSRs received from APs 1404 and 1406. In an example, AP 1402 may further determine a DL transmission parameter for the DL transmission for one or more of APs 1404 and 1406 based on one or both of the DL BSRs received from APs 1404 and 1406. In embodiments, the DL transmission parameter may include an MCS, DL time resource allocation information, DL frequency resource allocation information, or a number of spatial streams for the DL transmission. AP 1402 may include the determined DL transmission parameters(s) in MRTT frame 1508. By selecting time period 1524 and the DL transmission parameter(s) based on the DL BSR(s), AP 1402 can ensure that at least one of APs 1404 and 1406 fully utilize time period 1524 for DL transmission of data traffic (i.e., without padding).

[0238] In another embodiment relating to UL (not shown in FIG. 15b), AP 1404 may include in frame 1504 the amount of UL traffic for the first STA but may not include in frame 1504 the UL transmission parameter for the UL transmission from the first STA to AP 1404. Similarly, AP 1406 may include in frame 1506 the amount of UL traffic for the second STA but may not include in frame 1506 the UL transmission parameter for the UL transmission from the second STA to AP 1406. AP 1402 may determine time period 1524 based on one or both of the amounts of UL traffic for the first STA and the amount of UL traffic for the second STA. In an example, AP 1402 may further determine an UL transmission parameter for the UL transmission to AP 1404 and / or the UL transmission to AP 1406, based on one or more of the amount of UL traffic for the first STA and the amount of UL traffic for the second STA. In embodiments, the UL transmission parameter may include an MCS, UL time resource allocation information, UL frequency resource allocation information, or a number of spatial streams for the UL transmission. AP 1402 may include the determined UL transmission parameter(s) in MRTT frame 1508. By selecting time period 1524 and the UL transmission parameter(s) based on one or more of the amount of UL traffic for the first STA and the amount of UL traffic for the second STA, AP 1402 can ensure that at least one of the first STA and the second STA fully utilize time period 1524 for UL transmission of data traffic (i.e., without padding).

[0239] FIG. 16a illustrates example A-Control fields 1602 and 1604 which may be used in embodiments. A-Control fields 1602 and 1604 may be used to carry the DL transmission parameter and / or the DL BSR in a QoS data / null frame. As shown in FIG. 16, A-Control fields 1602 and 1604 may include a control ID field that indicates the type of A-Control fields 1602 and 1604. In an example, the control ID field may indicate that A-Control fields 1602 and 1604 comprise a BSR for a DL coordinated transmission (“C-BSR”). In an embodiment, A-Control field 1602 includes a DL Tx parameter field and a queue size field. The DL Tx parameter field indicates the DL transmission parameter as described above. The queue size field comprises the DL BSR. In an embodiment, A-Control field 1604 includes a DL time resource allocation field and a DL frequency resource allocation field. The DL time resource allocation field may include / indicate a duration for the DL coordinated transmission. The DL frequency resource allocation field may include / indicate an RU size / type (e.g., 26-tone RU, 52-tone RU, etc.) for the coordinated DL transmission.

[0240] FIG. 16b illustrates example A-Control fields 1602 and 1604 which may be used in embodiments. A-Control fields 1602 and 1604 may be used to carry the UL transmission parameter and / or the amount of UL traffic for a STA in a QoS data / null frame. As shown in FIG. 16, A-Control fields 1602 and 1604 may include a control ID field that indicates the type of A-Control fields 1602 and 1604. In an example, the control ID field may indicate that A-Control fields 1602 and 1604 comprise a BSR for an UL coordinated transmission (“C-BSR”). In an embodiment, A-Control field 1602 includes an UL Tx parameter field and an amount of UL traffic field. The UL Tx parameter field indicates the UL transmission parameter as described above. The amount of UL traffic field indicates the amount of UL traffic for the STA. In an embodiment, A-Control field 1604 includes an UL time resource allocation field and an UL frequency resource allocation field. The UL time resource allocation field may include / indicate a duration for the UL coordinated transmission. The UL frequency resource allocation field may include / indicate an RU size / type (e.g., 26-tone RU, 52-tone RU, etc.) for the coordinated UL transmission.

[0241] FIGs. 17a and 17b illustrates example information elements 1702 and 1704 which may be used in embodiments. Information elements 1702 and 1704 may be used to carry the DL / UL transmission parameter and / or the DL BSR (or amount of UL traffic for a STA) in an action frame. As shown in FIGs. 17a and 17b, information elements 1702 and 1704 may include an element ID field, a length field, and an element ID extension field. The element ID and the element ID extension fields indicate the type of information elements 1702 and 1704. In an example, the element ID and the element ID extension fields may indicate that information elements 1702 and 1704 comprise a BSR for a DL or UL coordinated transmission (“C-BSR”). In an embodiment, information element 1702 further includes a DL / UL Tx parameter field and a queue size (or amount of UL traffic) field. The DL / UL Tx parameter field indicates the DL / UL transmission parameter as described above. The queue size / amount of UL traffic field indicates the DL BSR or amount of UL traffic for the STA. In an embodiment, information element 1704 further includes a DL / UL time resource allocation field and a DL / UL frequency resource allocation field. The DL / UL time resource allocation field may include / indicate a duration for the DL / UL coordinated transmission. The DL / UL frequency resource allocation field may include / indicate an RU size / type (e.g., 26-tone RU, 52-tone RU, etc.) for the coordinated DL / UL transmission.

[0242] FIG. 18 illustrates an example process 1800 according to an embodiment. Example process 1800 may be performed by a first AP, such as AP 1402 described above. As shown in FIG. 18, process 1800 includes steps 1802 and 1804.

[0243] For a DL case, step 1802 includes receiving, by the first AP from a second AP, a first frame indicating a DL transmission parameter for a DL transmission. In an embodiment, the first AP may be part of a multi-AP group. The multi-AP group may comprise the second AP. The first AP may be a master AP of the multi-AP group and the second AP may be a slave AP of the multi-AP group.

[0244] For an UL case, Step 1802 includes receiving, by the first AP from a second AP, a first frame indicating an amount of UL traffic for a STA associated with the second AP. In an embodiment, the first AP may be part of a multi-AP group. The multi-AP group may comprise the second AP. The first AP may be a master / sharing AP of the multi-AP group and the second AP may be a slave / shared AP of the multi-AP group. The amount of UL traffic for the STA may correspond to the amount of traffic buffered at the STA for uplink transmission to the second AP. In an embodiment, the DL transmission is a multi-AP transmission comprising the second AP. The multi-AP transmission may be coordinated / initiated by the first AP. The multi-AP transmission may or may not comprise the first AP. The multi-AP transmission may comprise a third AP. The multi- AP transmission may be a C-OFDMA transmission, a C-SR transmission, a C-BF, or a coordinated joint transmission.

[0245] In an embodiment, the DL transmission parameter is selected by the second AP from a plurality of DL transmission parameters. In an embodiment, the DL transmission parameter is suggested by the second AP for the DL transmission. In an embodiment, the DL transmission parameter is preferred by the second AP for the DL transmission.

[0246] In an embodiment, the DL transmission parameter may include / indicate one or more of an MCS, a bandwidth (BW) size, an RU size, a PPDU type, or a number of spatial streams (Nss) for the DL transmission. In an embodiment, the DL transmission parameter may include / indicate DL time resource allocation information and / or DL frequency resource allocation information for the DL transmission. The DL time resource allocation information may indicate a duration for the DL transmission. The DL frequency resource allocation information may comprise an RU size for the DL transmission.

[0247] In an embodiment, the first frame comprises an action frame. The action frame may comprise an information element comprising the DL transmission parameter. In another embodiment, the first frame comprises a QoS null or data frame. The QoS null or data frame may comprise an A-Control field comprising the DL transmission parameter.

[0248] Step 1804 includes transmitting, by the first AP to the second AP, a second frame indicating a time period for the DL transmission, determined based on the DL transmission parameter for DL and indicating a time period, based on the amount of UL traffic, for an UL transmission from the STA to the second AP, for UL.

[0249] In an embodiment, the DL transmission is a multi-AP transmission performed in the context of an inter-AP TXS procedure as described above. For example, the DL transmission may be performed within a TXOP obtained by the first AP. As such, the first AP may be a sharing AP and the second AP may be a shared AP. In such an embodiment, the first frame may further indicate an allocated time of the TXOP obtained by the first AP. The first frame may further indicate an identifier of the second AP indicating sharing of the allocated time with the second AP. For UL, in an embodiment, the second frame further indicates an allocated time of a TXOP obtained by the first AP.

[0250] In an embodiment, for DL, the second frame comprises an MRTT frame or a multi-AP trigger frame.

[0251] In an embodiment, for DL, the first frame may further comprise a DL BSR. The DL BSR may indicate an amount of DL traffic buffered at the second AP. In an embodiment, the time period for the DL transmission is further based on the DL BSR. For UL, in an embodiment, the time period is within the allocated time of the TXOP. In an embodiment, the first frame further indicates an UL transmission parameter for the UL transmission. The UL transmission parameter may be selected, suggested, and / or preferred by the second AP for the UL transmission. The UL transmission parameter may comprise one or more of an MCS, a bandwidth size, an RU size, a PPDU type, or a number of spatial streams for the UL transmission.

[0252] In an embodiment, the time period is further based on the UL transmission parameter.

[0253] In an embodiment, the UL transmission comprises an UL PPDU. In an embodiment, the time period comprises a duration of the UL PPDU. The UL PPDU may be a part of a C-OFDMA UL transmission. The C-OFDMA UL transmission may comprise the UL transmission and a further UL transmission. The further UL transmission may be from another STA to the first AP or to a third AP. The C-OFDMA UL transmission may be performed within the allocated time of the TXOP obtained by the first AP.

[0254] In an embodiment relating to DL, process 1800 may further comprise transmitting, by the first AP to the second AP, a third frame soliciting the DL BSR from the second AP for the DL transmission. The third frame may comprise a BSRP trigger frame, a basic trigger frame, a poll frame, or a soliciting frame. In an embodiment, process 1800 may further comprise receiving, by the first AP from the second AP, the first frame in response to the third frame.

[0255] In an embodiment relating to UL, the first frame comprises an UL BSR for the STA, the UL BSR indicating the amount of UL traffic for the STA. In an embodiment, process 1800 may further comprise transmitting, by the first AP to the second AP, a third frame soliciting the UL BSR; and receiving, by the first AP from the second AP, the first frame in response to the third frame. In an embodiment, the third frame comprises a BSRP trigger frame, a basic trigger frame, a poll frame, or a soliciting frame. In an embodiment, the UL BSR is a C-OFDMA BSR.

[0256] In an embodiment relating to UL, the second frame comprises an MRTT frame or a multi -AP trigger frame. In an embodiment, the second frame further indicates an identifier of the second AP.

[0257] In an embodiment relating to UL, the first frame comprises an action frame. The action frame may comprise an information element comprising the amount of UL traffic for the STA. In another embodiment, the first frame comprises a QoS null or data frame. The QoS null or data frame may comprise an A-Control field comprising the amount of UL traffic for the STA.

[0258] FIG. 19 illustrates another example process 1900 according to an embodiment. Example process 1900 may be performed by a first AP, such as AP 1402 described above. As shown in FIG. 19, process 1900 includes steps 1902 and 1904.

[0259] Step 1902 includes receiving, by the first AP from a second AP, a first frame indicating a DL BSR for a DL transmission or an amount of UL traffic for a STA associated with the second AP, for UL. In an embodiment, the first AP may be part of a multi-AP group. The multi-AP group may comprise the second AP. The first AP may be a master / sharing AP of the multi-AP group and the second AP may be a slave / shared AP of the multi -AP group. The DL BSR may indicate an amount of DL traffic buffered at the second AP for DL or, for UL, the amount of UL traffic for the STA may correspond to the amount of traffic buffered at the STA for uplink transmission to the second AP.

[0260] In an embodiment for DL, the DL transmission is a multi-AP transmission comprising the second AP. The multi-AP transmission may be coordinated / initiated by the first AP. The multi-AP transmission may or may not comprise the first AP. The multi-AP transmission may comprise a third AP. The multi-AP transmission may be a C-OFDMA transmission, a C-SR transmission, a C-BF, or a coordinated joint transmission.

[0261] Step 1904 includes transmitting, in the case of DL by the first AP to the second AP, a second frame indicating: a time period for the DL transmission; and a DL transmission parameter for the second AP for the DL transmission. In the case of UL step 1904 includes transmitting, by the first AP to the second AP, a second frame indicating: a duration of an UL PPDU for an UL transmission from the STA to the second AP; and a transmission parameter for the UL PPDU.

[0262] The UL PPDU may be a part of a C-OFDMA UL transmission. The C-OFDMA UL transmission may comprise the UL transmission and a further UL transmission. The further UL transmission may be from another STA to the first AP or to a third AP. In an embodiment, the second frame further indicates an allocated time of a TXOP obtained by the first AP. The C-OFDMA UL transmission may be performed within the allocated time of the TXOP obtained by the first AP.

[0263] In an embodiment, the DL transmission parameter may include / indicate one or more of an MCS, a bandwidth (BW) size, an RU size, a PPDU type, or a number of spatial streams (Nss) for the DL transmission. In an embodiment, the DL transmission parameter may include / indicate DL time resource allocation information and / or DL frequency resource allocation information for the DL transmission. The DL time resource allocation information may indicate a duration for the DL transmission. The DL frequency resource allocation information may comprise an RU size for the DL transmission.

[0264] In an embodiment, at least one of the time period and the DL transmission parameter for the second AP for the DL transmission is determined based on the DL BSR.

[0265] The UL transmission parameter may comprise one or more of an MCS, a bandwidth size, an RU size, a PPDU type, or a number of spatial streams for the UL transmission.

[0266] In an embodiment, the DL transmission is a multi-AP transmission performed in the context of an inter-AP TXS procedure as described above. For example, the DL transmission may be performed within a TXOP obtained by the first AP. As such, the first AP may be a sharing AP and the second AP may be a shared AP. In such an embodiment, the first frame may further indicate an allocated time of the TXOP obtained by the first AP. The first frame may further indicate an identifier of the second AP indicating sharing of the allocated time with the second AP. In an embodiment for UL, the frame comprises an MRTT frame or a multi-AP trigger frame. In an embodiment, the second frame further indicates an identifier of the second AP. In an embodiment, the first frame comprises an UL BSR for the STA, the UL BSR indicating the amount of UL traffic for the STA. In an embodiment, process 1900 may further comprise transmitting, by the first AP to the second AP, a third frame soliciting the UL BSR; and receiving, by the first AP from the second AP, the first frame in response to the third frame. In an embodiment, the third frame comprises a BSRP trigger frame, a basic trigger frame, a poll frame, or a soliciting frame. In an embodiment, the UL BSR is a C-OFDMA BSR.

[0267] FIG. 20 illustrates another example process 2000 according to an embodiment for DL. Example process 200 may be performed by a first AP, such as AP 1404 or 1406 described above. As shown in FIG. 20, process 2000 includes steps 2002 and 2004.

[0268] For DL, step 2002 includes transmitting, by the first AP to a second AP, a first frame indicating a DL transmission parameter for a DL transmission. In an embodiment, the first AP may be part of a multi -AP group. The multi -AP group may comprise the second AP. The first AP may be a slave AP of the multi -AP group and the second AP may be a master AP of the multi -AP group.

[0269] In an embodiment for DL, the DL transmission is a multi-AP transmission comprising the first AP. The multi-AP transmission may be coordinated / initiated by the second AP. The multi-AP transmission may or may not comprise the second AP. The multi-AP transmission may comprise a third AP. The multi-AP transmission may be a C-OFDMA transmission, a C-SR transmission, a C-BF, or a coordinated joint transmission.

[0270] In an embodiment, for DL, the DL transmission parameter is selected by the first AP from a plurality of DL transmission parameters. In an embodiment, the DL transmission parameter is suggested by the first AP for the DL transmission. In an embodiment, the DL transmission parameter is preferred by the first AP for the DL transmission.

[0271] In an embodiment for DL, the DL transmission parameter may include / indicate one or more of an MCS, a bandwidth (BW) size, an RU size, a PPDU type, or a number of spatial streams (Nss) for the DL transmission. In an embodiment, the DL transmission parameter may include / indicate DL time resource allocation information and / or DL frequency resource allocation information for the DL transmission. The DL time resource allocation information may indicate a duration for the DL transmission. The DL frequency resource allocation information may comprise an RU size for the DL transmission.

[0272] In an embodiment for DL, the first frame comprises an action frame. The action frame may comprise an information element comprising the DL transmission parameter. In another embodiment, the first frame comprises a QoS null or data frame. The QoS null or data frame may comprise an A-Control field comprising the DL transmission parameter.

[0273] Step 2004 includes receiving, by the first AP from the second AP, a second frame indicating a time period for the DL transmission, determined based on the DL transmission parameter.

[0274] In an embodiment for DL, the DL transmission is a multi-AP transmission performed in the context of an inter-AP TXS procedure as described above. For example, the DL transmission may be performed within a TXOP obtained by the second AP. As such, the first AP may be a shared AP and the second AP may be a sharing AP. In such an embodiment, the first frame may further indicate an allocated time of the TXOP obtained by the second AP. The first frame may further indicate an identifier of the first AP indicating sharing of the allocated time with the first AP.

[0275] In an embodiment for DL, the second frame comprises an MRTT frame or a multi-AP trigger frame.

[0276] In an embodiment for DL, the first frame may further comprise a DL BSR. The DL BSR may indicate an amount of DL traffic buffered at the first AP. In an embodiment, the time period for the DL transmission is further based on the DL BSR.

[0277] In an embodiment for DL, process 2000 may further comprise receiving, by the first AP from the second AP, a third frame soliciting the DL BSR from the first AP for the DL transmission. The third frame may comprise a BSRP trigger frame, a basic trigger frame, a poll frame, or a soliciting frame. In an embodiment, process 2000 may further comprise transmitting, by the first AP to the second AP, the first frame in response to the third frame.

[0278] In an embodiment for DL, process 2000 may further comprise transmitting, by the first AP, a PPDU using the DL transmission parameter and during the time period for the DL transmission. The PPDU may be transmitted to a STA associated with the first AP, for example.

[0279] FIG. 20 also illustrates another example process 2000 according to an embodiment for UL. Example process 2000 may be performed by a first AP, such as AP 1402 described above. As shown in FIG. 20, process 2000 includes steps 2002 and 2004.

[0280] For UL, step 2002 includes receiving, by the first AP from a second AP, a first frame indicating UL time resource information from an UL transmission from a STA to the second AP and / or UL frequency resource information for the UL transmission. In an embodiment, the first AP may be part of a multi-AP group. The multi-AP group may comprise the second AP. The first AP may be a master / sharing AP of the multi-AP group and the second AP may be a slave / shared AP of the multi-AP group. The STA may be associated with the second AP.

[0281] The UL transmission may be a part of a C-OFDMA UL transmission. The C-OFDMA UL transmission may comprise the UL transmission and a further UL transmission. The further UL transmission may be from another STA to the first AP or to a third AP.

[0282] For UL, step 2004 includes transmitting, by the first AP to the second AP, a second frame indicating a duration of an UL PPDU for the UL transmission, determined based on the UL time resource information and / or the UL frequency resource information.

[0283] In an embodiment for UL, the second frame further indicates an allocated time of a TXOP obtained by the first AP. The C-OFDMA UL transmission may be performed within the allocated time of the TXOP obtained by the first AP. In an embodiment for UL, the UL time resource information is preferred / recommended / selected by the second AP. In an embodiment, the UL time resource information comprises a length of the UL PPDU.

[0284] In an embodiment for UL, UL frequency resource information is preferred / recommended / selected by the second AP. In an embodiment, the UL frequency resource information comprises a size of a frequency RU for the UL transmission.

[0285] In an embodiment for UL, the second frame comprises an MRTT frame or a multi-AP trigger frame. In an embodiment, the second frame further indicates an identifier of the second AP.

[0286] In an embodiment for UL, the first frame comprises an action frame. The action frame may comprise an information element comprising the UL time resource information and / or the UL frequency resource information. In another embodiment, the first frame comprises a QoS null or data frame. The QoS null or data frame may comprise an A-Control field comprising the UL time resource information and / or the UL frequency resource information.

[0287] FIG. 21 illustrates another example process 2100 according to embodiments for DL and for UL. Example process 2100 may be performed by a first AP, such as AP 1404 or 1406 described above. As shown in FIG. 21, process 2100 includes steps 2102 and 2104.

[0288] For DL, step 2102 includes transmitting, by the first AP to a second AP, a first frame indicating a DL BSR for a DL transmission. In an embodiment, the first AP may be part of a multi-AP group. The multi-AP group may comprise the second AP. The first AP may be a slave AP of the multi-AP group and the second AP may be a master AP of the multi-AP group. The DL BSR may indicate an amount of DL traffic buffered at the first AP.

[0289] In an embodiment for DL, the DL transmission is a multi-AP transmission comprising the first AP. The multi-AP transmission may be coordinated / initiated by the second AP. The multi-AP transmission may or may not comprise the second AP. The multi-AP transmission may comprise a third AP. The multi-AP transmission may be a C-OFDMA transmission, a C-SR transmission, a C-BF, or a coordinated joint transmission.

[0290] Step 2104 includes receiving, by the first AP from the second AP, a second frame indicating: a time period for the DL transmission; and a DL transmission parameter for the first AP for the DL transmission.

[0291] In an embodiment for DL, the DL transmission parameter may include / indicate one or more of an MCS, a bandwidth (BW) size, an RU size, a PPDU type, or a number of spatial streams (Nss) for the DL transmission. In an embodiment, the DL transmission parameter may include / indicate DL time resource allocation information and / or DL frequency resource allocation information for the DL transmission. The DL time resource allocation information may indicate a duration for the DL transmission. The DL frequency resource allocation information may comprise an RU size for the DL transmission. In an embodiment for DL, at least one of the time period and the DL transmission parameter for the first AP for the DL transmission is determined based on the DL BSR.

[0292] In an embodiment for DL, the DL transmission is a multi-AP transmission performed in the context of an inter-AP TXS procedure as described above. For example, the DL transmission may be performed within a TXOP obtained by the second AP. As such, the first AP may be a shared AP and the second AP may be a sharing AP. In such an embodiment, the first frame may further indicate an allocated time of the TXOP obtained by the second AP. The first frame may further indicate an identifier of the first AP indicating sharing of the allocated time with the first AP.

[0293] In an embodiment for DL, process 2100 may further comprise transmitting, by the first AP, a PPDU using the DL transmission parameter and during the time period for the DL transmission. The PPDU may be transmitted to a STA associated with the first AP, for example.

[0294] In the case of UL, example process 2100 may be performed by a first AP, such as AP 1404 or 1406 described above. As shown in FIG. 21, process 2100 includes steps 2102 and 2104.

[0295] For UL, step 2102 includes transmitting, by the first AP to a second AP, a first frame indicating an amount of UL traffic for a STA associated with the first AP. In an embodiment, the first AP may be part of a multi-AP group. The multi-AP group may comprise the second AP. The second AP may be a master / sharing AP of the multi-AP group and the first AP may be a slave / shared AP of the multi-AP group. The amount of UL traffic for the STA may correspond to the amount of traffic buffered at the STA for uplink transmission to the first AP.

[0296] For UL, step 2104 includes receiving, by the first AP from the second AP, a second frame indicating a time period, based on the amount of UL traffic, for an UL transmission from the STA to the first AP.

[0297] In an embodiment for UL, the second frame further indicates an allocated time of a TXOP obtained by the second AP. In an embodiment, the time period is within the allocated time of the TXOP.

[0298] In an embodiment, the first frame further indicates an UL transmission parameter for the UL transmission. The UL transmission parameter may be selected, suggested, and / or preferred by the first AP for the UL transmission. The UL transmission parameter may comprise one or more of an MCS, a bandwidth size, an RU size, a PPDU type, or a number of spatial streams for the UL transmission.

[0299] In an embodiment for UL, the time period is further based on the UL transmission parameter.

[0300] In an embodiment for UL, the UL transmission comprises an UL PPDU. In an embodiment, the time period comprises a duration of the UL PPDU. The UL PPDU may be a part of a C- OFDMA UL transmission. The C-OFDMA UL transmission may comprise the UL transmission and a further UL transmission. The further UL transmission may be from another STA to the second AP or to a third AP. The C-OFDMA UL transmission may be performed within the allocated time of the TXOP obtained by the second AP. In an embodiment for UL, the first frame comprises an UL BSR for the STA, the UL BSR indicating the amount of UL traffic for the STA. In an embodiment, process 2100 may further comprise receiving, by the first AP from the second AP, a third frame soliciting the UL BSR; and transmitting, by the first AP to the second AP, the first frame in response to the third frame. In an embodiment, the third frame comprises a BSRP trigger frame, a basic trigger frame, a poll frame, or a soliciting frame. In an embodiment, the UL BSR is a C-OFDMA BSR.

[0301] In an embodiment, the second frame comprises an MRTT frame or a multi-AP trigger frame. In an embodiment, the second frame further indicates an identifier of the first AP.

[0302] In an embodiment for UL, the first frame comprises an action frame. The action frame may comprise an information element comprising the amount of UL traffic for the STA. In another embodiment, the first frame comprises a QoS null or data frame. The QoS null or data frame may comprise an A-Control field comprising the amount of UL traffic for the STA.

[0303] FIG. 22 illustrates another example process 2200 according to an embodiment. Example process 2200 may be performed by a first AP, such as AP 1404 or 1406 described above. As shown in FIG. 22, process 2200 includes steps 2202 and 2204.

[0304] Step 2202 includes transmitting, by the first AP to a second AP, a first frame indicating an amount of UL traffic for a STA associated with the first AP. In an embodiment, the first AP may be part of a multi-AP group. The multi-AP group may comprise the second AP. The second AP may be a master / sharing AP of the multi-AP group and the first AP may be a slave / shared AP of the multi-AP group. The amount of UL traffic for the STA may correspond to the amount of traffic buffered at the STA for uplink transmission to the first AP.

[0305] Step 2204 includes receiving, by the first AP from the second AP, a second frame indicating: a duration of an UL PPDU for an UL transmission from the STA to the first AP; and a transmission parameter for the UL PPDU.

[0306] The UL PPDU may be a part of a C-OFDMA UL transmission. The C-OFDMA UL transmission may comprise the UL transmission and a further UL transmission. The further UL transmission may be from another STA to the second AP or to a third AP. In an embodiment, the second frame further indicates an allocated time of a TXOP obtained by the second AP. The C-OFDMA UL transmission may be performed within the allocated time of the TXOP obtained by the second AP.

[0307] The UL transmission parameter may comprise one or more of an MCS, a bandwidth size, an RU size, a PPDU type, or a number of spatial streams for the UL transmission.

[0308] In an embodiment, the first frame comprises an UL BSR for the STA, the UL BSR indicating the amount of UL traffic for the STA. In an embodiment, process 2200 may further comprise receiving, by the first AP from the second AP, a third frame soliciting the UL BSR; and transmitting, by the first AP to the second AP, the first frame in response to the third frame. In an embodiment, the third frame comprises a BSRP trigger frame, a basic trigger frame, a poll frame, or a soliciting frame. In an embodiment, the UL BSR is a C-OFDMA BSR. In an embodiment, the second frame comprises an MRTT frame or a multi-AP trigger frame. In an embodiment, the second frame further indicates an identifier of the first AP.

[0309] In an embodiment, the first frame comprises an action frame. The action frame may comprise an information element comprising the amount of UL traffic for the STA. In another embodiment, the first frame comprises a QoS null or data frame. The QoS null or data frame may comprise an A-Control field comprising the amount of UL traffic for the STA.

[0310] FIG. 23 illustrates another example process 2300 according to an embodiment. Example process 2300 may be performed by a first AP, such as AP 1404 or 1406 described above. As shown in FIG. 23, process 2300 includes steps 2302 and 2304.

[0311] Step 2302 includes transmitting, by the first AP to a second AP, a first frame indicating UL time resource information from an UL transmission from a STA to the first AP and / or UL frequency resource information for the UL transmission. In an embodiment, the first AP may be part of a multi-AP group. The multi-AP group may comprise the second AP. The second AP may be a master / sharing AP of the multi-AP group and the first AP may be a slave / shared AP of the multi-AP group. The STA may be associated with the first AP.

[0312] The UL transmission may be a part of a C-OFDMA UL transmission. The C-OFDMA UL transmission may comprise the UL transmission and a further UL transmission. The further UL transmission may be from another STA to the second AP or to a third AP.

[0313] Step 2304 includes receiving, by the first AP from the second AP, a second frame indicating a duration of an UL PPDU for the UL transmission, determined based on the UL time resource information and / or the UL frequency resource information.

[0314] In an embodiment, the second frame further indicates an allocated time of a TXOP obtained by the second AP. The C-OFDMA UL transmission may be performed within the allocated time of the TXOP obtained by the second AP.

[0315] In an embodiment, the UL time resource information is preferred / recommended / selected by the first AP. In an embodiment, the UL time resource information comprises a length of the UL PPDU.

[0316] In an embodiment, UL frequency resource information is preferred / recommended / selected by the first AP. In an embodiment, the UL frequency resource information comprises a size of a frequency RU for the UL transmission.

[0317] In an embodiment, the second frame comprises an MRTT frame or a multi-AP trigger frame. In an embodiment, the second frame further indicates an identifier of the first AP.

[0318] In an embodiment, the first frame comprises an action frame. The action frame may comprise an information element comprising the UL time resource information and / or the UL frequency resource information. In another embodiment, the first frame comprises a QoS null or data frame. The QoS null or data frame may comprise an A-Control field comprising the UL time resource information and / or the UL frequency resource information. Thus, in an embodiment there is a method comprising receiving, by a first access point (AP) from a second AP, a first frame indicating a modulation and coding scheme (MCS) for a downlink (DL) transmission and transmitting, by the first AP to the second AP, a second frame indicating an allocated time of a transmission opportunity (TXOP) obtained by the first AP and a time period, within the allocated time, for the DL transmission, wherein the time period is determined based on the MCS.

[0319] Also there is, in an embodiment, a method comprising receiving, by a first access point (AP) from a second AP, a first frame indicating a downlink (DL) transmission parameter for a DL transmission and transmitting, by the first AP to the second AP, a second frame indicating a time period for the DL transmission, wherein the time period is determined based on the DL transmission parameter.

[0320] In an embodiment, the DL transmission parameter is selected by the second AP from a plurality of DL transmission parameters.

[0321] In an embodiment, the DL transmission parameter is suggested by the second AP for the DL transmission.

[0322] In an embodiment, the DL transmission parameter is preferred by the second AP for the DL transmission.

[0323] In an embodiment, the DL transmission parameter comprises one or more of a modulation and coding scheme (MCS), a bandwidth size, a resource unit (RU) size, a physical layer protocol data unit (PPDU) type, or a number of spatial streams for the DL transmission.

[0324] In an embodiment, the second frame further indicates an allocated time of a transmission opportunity (TXOP) obtained by the first AP.

[0325] In an embodiment, the second frame further indicates an identifier of the second AP.

[0326] In an embodiment, the DL transmission is a multi-AP transmission comprising the second AP.

[0327] In an embodiment, the multi-AP transmission is initiated by the first AP.

[0328] In an embodiment, the multi-AP transmission comprises the first AP.

[0329] In an embodiment, the first frame comprises a downlink (DL) buffer status report (BSR).

[0330] In an embodiment, the time period for the DL transmission is further based on the DL BSR.

[0331] In an embodiment, the DL BSR indicates an amount of DL traffic buffered at the second AP.

[0332] In an embodiment, there is transmitting, by the first AP to the second AP, a third frame soliciting a buffer status report (BSR) from the second AP for the DL transmission.

[0333] In an embodiment, there is a method comprising receiving, by a first access point (AP) from a second AP, a first frame indicating a downlink (DL) buffer status report (BSR) for a DL transmission and transmitting, by the first AP to the second AP, a second frame indicating an allocated time of a transmission opportunity (TXOP) obtained by the first AP, an identifier of the second AP, a time period for the DL transmission; and a DL transmission parameter for the second AP for the DL transmission.

[0334] In an embodiment, at least one of the time period and the DL transmission parameter for the second AP for the DL transmission is determined based on the DL BSR.

[0335] In an embodiment, the DL transmission is a multi-AP transmission performed during the allocated time of the TXOP.

[0336] In an embodiment, the multi-AP transmission is a coordinated orthogonal frequency division multiple access (C-OFDMA) transmission.

[0337] In an embodiment, the DL transmission comprises a DL physical protocol data unit (PPDU).

[0338] In an embodiment, the time period of the DL transmission comprises a length of the DL PPDU.

[0339] In an embodiment, the DL transmission parameter comprises one or more of a modulation and coding scheme (MCS), a bandwidth size, a resource unit (RU) size, a physical layer protocol data unit (PPDU) type, or a number of spatial streams for the DL transmission.

[0340] In an embodiment, there is a method comprising transmitting, by a first access point (AP) to a second AP, a first frame indicating a modulation and coding scheme (MCS) for a DL transmission and receiving, by the first AP from the second AP, a second frame indicating an allocated time of a transmission opportunity (TXOP) obtained by the second AP, and a time period, within the allocated time, for the DL transmission, wherein the time period is determined based on the MCS.

[0341] In an embodiment, there is a method comprising transmitting, by a first access point (AP) to a second AP, a first frame indicating a downlink (DL) transmission parameter for a DL transmission; and receiving, by the first AP from the second AP, a second frame indicating a time period for the DL transmission, wherein the time period is determined based on the DL transmission parameter.

[0342] In an embodiment, the DL transmission parameter is selected by the first AP from a plurality of DL transmission parameters.

[0343] In an embodiment, the DL transmission parameter is suggested by the first AP for the DL transmission.

[0344] In an embodiment, the DL transmission parameter is preferred by the first AP for the DL transmission.

[0345] In an embodiment, the DL transmission parameter comprises one or more of a modulation and coding scheme (MCS), a bandwidth size, a resource unit (RU) size, a physical layer protocol data unit (PPDU) type, or a number of spatial streams for the DL transmission.

[0346] In an embodiment, the DL transmission parameter comprises downlink (DL) time resource allocation information or DL frequency resource allocation information for the DL transmission.

[0347] In an embodiment, the DL time resource allocation information indicates a duration of the

[0348] DL transmission. In an embodiment, the DL frequency resource allocation information comprises a resource unit (RU) size for the DL transmission.

[0349] In an embodiment, the time period for the DL transmission is determined based on the DL time resource allocation information or the DL frequency resource allocation information.

[0350] In an embodiment, the second frame further indicates an allocated time of a transmission opportunity (TXOP) obtained by the second AP.

[0351] In an embodiment, the second frame comprises a multi-user request to send triggered TXOP sharing (MU-RTS TXS) trigger frame or a multi-AP trigger frame.

[0352] In an embodiment, the second frame further indicates an identifier of the first AP.

[0353] In an embodiment, the DL transmission is a multi-AP transmission comprising the first AP.

[0354] In an embodiment, the multi-AP transmission is initiated by the second AP.

[0355] In an embodiment, the multi-AP transmission comprises the second AP.

[0356] In an embodiment, the multi-AP transmission is a coordinated orthogonal frequency division multiple access (C-OFDMA) transmission, a coordinated time division multiple access (C- TDMA) transmission, a coordinated spatial reuse (C-SR) transmission, a coordinated beamforming (C- BF), or a coordinated joint transmission.

[0357] In an embodiment, the first frame comprises a downlink (DL) buffer status report (BSR).

[0358] In an embodiment, the time period for the DL transmission is further based on the DL BSR.

[0359] In an embodiment, the DL BSR indicates an amount of DL traffic buffered at the first AP.

[0360] In an embodiment, there is receiving, by the first AP from the second AP, a third frame soliciting a buffer status report (BSR) from the first AP.

[0361] In an embodiment, the BSR is a coordinated orthogonal frequency division multiple access (C-OFDMA) BSR.

[0362] In an embodiment, the third frame comprises a buffer status report poll (BSRP) trigger frame, a basic trigger frame, a poll frame, or a soliciting frame.

[0363] In an embodiment, there is transmitting, by the first AP to the second AP, the first frame in response to the third frame.

[0364] In an embodiment, the first frame comprises an action frame.

[0365] In an embodiment, the action frame comprises an information element comprising the DL transmission parameter.

[0366] In an embodiment, the first frame comprises a quality of service (QoS) null or data frame.

[0367] In an embodiment, the QoS null or data frame comprises an aggregated control (A- Control) field comprising the DL transmission parameter.

[0368] In an embodiment, there is transmitting, by the first AP, a physical layer protocol data unit (PPDU) using the DL transmission parameter and during the time period for the DL transmission. In an embodiment, there is a method comprising transmitting, by a first access point (AP) from a second AP, a first frame indicating a downlink (DL) buffer status report (BSR) for a DL transmission and receiving, by the first AP from the second AP, a second frame indicating an allocated time of a transmission opportunity (TXOP) obtained by the second AP, an identifier of the first AP, a time period for the DL transmission; and a DL transmission parameter for the first AP for the DL transmission.

[0369] In an embodiment, at least one of the time period and the DL transmission parameter for the first AP for the DL transmission is determined based on the BSR.

[0370] In an embodiment, the DL transmission is a multi-AP transmission performed during the allocated time of the TXOP.

[0371] In an embodiment, the multi-AP transmission is a coordinated orthogonal frequency division multiple access (C-OFDMA) transmission.

[0372] In an embodiment, the DL transmission comprises a DL physical protocol data unit (PPDU).

[0373] In an embodiment, the time period of the DL transmission comprises a length of the DL PPDU.

[0374] In an embodiment, the DL transmission parameter comprises one or more of a modulation and coding scheme (MCS), a bandwidth size, a resource unit (RU) size, a physical layer protocol data unit (PPDU) type, or a number of spatial streams for the DL transmission.

[0375] In an embodiment, there is a computer program product, storable on a computer readable medium and configured, when run on a processor to execute the method of any of the preceding claims.

[0376] In an embodiment, there is a device arranged to, when implemented in a first access point, perform operations comprising receiving to from a second AP, a first frame indicating a modulation and coding scheme (MCS) for a downlink (DL) transmission and transmitting to the second AP, a second frame indicating an allocated time of a transmission opportunity (TXOP) obtained by the first AP and a time period, within the allocated time, for the DL transmission, wherein the time period is determined based on the MCS.

[0377] In an embodiment, there is a device arranged to, when implemented in a first access point, perform operations comprising receiving, by a first access point (AP) from a second AP, a first frame indicating a downlink (DL) transmission parameter for a DL transmission; and transmitting to the second AP, a second frame indicating a time period for the DL transmission, wherein the time period is determined based on the DL transmission parameter.

[0378] In an embodiment, there is a device arranged to, when implemented in a first access point perform operations comprising, transmitting to a second AP, a first frame indicating a modulation and coding scheme (MCS) for a DL transmission and receiving from the second AP, a second frame indicating an allocated time of a transmission opportunity (TXOP) obtained by the second AP and a time period, within the allocated time, for the DL transmission, wherein the time period is determined based on the MCS.

[0379] In an embodiment, there is a device arranged to, when implemented in a first access point, to perform operations comprising transmitting to a second AP, a first frame indicating a downlink (DL) transmission parameter for a DL transmission; and receiving from the second AP, a second frame indicating a time period for the DL transmission, wherein the time period is determined based on the DL transmission parameter.

[0380] Thus, in an uplink case, in an embodiment, there is a method comprising receiving, by a first access point (AP) from a second AP, a first frame indicating an amount of uplink (UL) traffic for a station (STA) associated with the second AP and transmitting, by the first AP to the second AP, a second frame indicating an allocated time of a transmission opportunity (TXOP) obtained by the first AP and a time period, within the allocated time, based on the amount of UL traffic and for an UL transmission from the STA to the second AP.

[0381] In an embodiment, there is a method comprising receiving, by a first access point (AP) from a second AP, a first frame indicating an amount of uplink (UL) traffic for a station (STA) associated with the second AP and transmitting, by the first AP to the second AP, a second frame indicating a time period, based on the amount of UL traffic, for an UL transmission from the STA to the second AP.

[0382] In an embodiment, the second frame further indicates an allocated time of a transmission opportunity (TXOP) obtained by the first AP.

[0383] In an embodiment, the first frame further indicates an UL transmission parameter for the UL transmission.

[0384] In an embodiment, the time period is further based on the UL transmission parameter.

[0385] In an embodiment, the UL transmission parameter is selected by the second AP from a plurality of UL transmission parameters.

[0386] In an embodiment, the UL transmission parameter is suggested by the second AP for the UL transmission.

[0387] In an embodiment, the UL transmission parameter is preferred by the second AP for the UL transmission.

[0388] In an embodiment, the UL transmission parameter comprises one or more of a modulation and coding scheme (MCS), a bandwidth size, a resource unit (RU) size, a physical layer protocol data unit (PPDU) type, or a number of spatial streams for the UL transmission.

[0389] In an embodiment, the first frame comprises an UL buffer status report (BSR) for the STA, the UL BSR indicating the amount of UL traffic for the STA.

[0390] In an embodiment, there is transmitting, by the first AP to the second AP, a third frame soliciting the UL BSR; and receiving, by the first AP from the second AP, the first frame in response to the third frame. In an embodiment, the third frame comprises a buffer status report poll (BSRP) trigger frame, a basic trigger frame, a poll frame, or a soliciting frame.

[0391] In an embodiment, the second frame further indicates an identifier of the second AP.

[0392] In an embodiment, there is a method comprising receiving, by a first access point (AP) from a second AP, a first frame indicating amount of uplink (UL) traffic for a station (STA) associated with the second AP and transmitting, by the first AP to the second AP, a second frame indicating an allocated time of a transmission opportunity (TXOP) obtained by the first AP an identifier of the second AP a duration of an uplink (UL) physical layer protocol data unit (PPDU) for an UL transmission from the STA to the second AP during the allocated time; and a modulation and coding scheme (MCS) for the UL PPDU.

[0393] In an embodiment, there is a method comprising receiving, by a first access point (AP) from a second AP, a first frame indicating uplink (UL) time resource information for an UL transmission from a STA to the second AP and UL frequency resource information for the UL transmission and transmitting, by the first AP to the second AP, a second frame indicating an allocated time of a transmission opportunity (TXOP) obtained by the first AP; an identifier of the second AP, and a duration of an UL physical layer protocol data unit (PPDU) for the UL transmission, determined based on the UL time resource information and the UL frequency resource information.

[0394] In an embodiment, the UL time resource information is preferred / recommended / selected by the second AP.

[0395] In an embodiment, the UL time resource information comprises a length of the UL PPDU.

[0396] In an embodiment, the UL frequency resource information is preferred / recommended / selected by the second AP.

[0397] In an embodiment, the UL frequency resource information comprises a size of a frequency resource unit (RU) for the UL transmission.

[0398] In an embodiment, there is a method comprising transmitting, by a first access point (AP) to a second AP, a first frame indicating an amount of uplink (UL) traffic for a station (STA) associated with the first AP and receiving, by the first AP from the second AP, a second frame indicating an allocated time of a transmission opportunity (TXOP) obtained by the second AP and a time period, within the allocated time, based on the amount of UL traffic and for an UL transmission from the STA to the first AP.

[0399] In an embodiment, there is a method comprising transmitting, by a first access point (AP) to a second AP, a first frame indicating an amount of uplink (UL) traffic for a station (STA) associated with the first AP and receiving, by the first AP from the second AP, a second frame indicating a time period, based on the amount of UL traffic, for an UL transmission from the STA to the first AP. In an embodiment, the second frame further indicates an allocated time of a transmission opportunity (TXOP) obtained by the second AP.

[0400] In an embodiment, the time period is within the allocated time of the TXOP.

[0401] In an embodiment, the first frame further indicates an UL transmission parameter for the UL transmission.

[0402] In an embodiment, the time period is further based on the UL transmission parameter.

[0403] In an embodiment, the UL transmission parameter is selected by the first AP from a plurality of UL transmission parameters.

[0404] In an embodiment, the UL transmission parameter is suggested by the first AP for the UL transmission.

[0405] In an embodiment, the UL transmission parameter is preferred by the first AP for the UL transmission.

[0406] In an embodiment, the UL transmission parameter comprises one or more of a modulation and coding scheme (MCS), a bandwidth size, a resource unit (RU) size, a physical layer protocol data unit (PPDU) type, or a number of spatial streams for the UL transmission.

[0407] In an embodiment, the UL transmission comprises an UL physical layer protocol data unit (PPDU).

[0408] In an embodiment, the time period comprises a duration of the UL PPDU.

[0409] In an embodiment, the UL PPDU is a part of a coordinated orthogonal frequency division multiple access (C-OFDMA) UL transmission.

[0410] In an embodiment, the first frame comprises an UL buffer status report (BSR) for the STA, the UL BSR indicating the amount of UL traffic for the STA.

[0411] In an embodiment, there is receiving, by the first AP from the second AP, a third frame soliciting the UL BSR and transmitting, by the first AP to the second AP, the first frame in response to the third frame.

[0412] In an embodiment, rein the third frame comprises a buffer status report poll (BSRP) trigger frame, a basic trigger frame, a poll frame, or a soliciting frame.

[0413] In an embodiment, the UL BSR is a coordinated orthogonal frequency division multiple access (C-OFDMA) BSR.

[0414] In an embodiment, the second frame comprises a multi-user request to send triggered TXOP sharing (MU-RTS TXS) trigger frame or a multi-AP trigger frame.

[0415] In an embodiment, the second frame further indicates an identifier of the first AP.

[0416] In an embodiment, the first frame comprises an action frame.

[0417] In an embodiment, the action frame comprises an information element comprising the amount of UL traffic for the STA.

[0418] In an embodiment, the first frame comprises a quality of service (QoS) null or data frame. In an embodiment, the QoS null or data frame comprises an aggregated control (A- Control) field comprising the amount of UL traffic for the STA.

[0419] In an embodiment, there is transmitting, by the first AP to the STA, a trigger frame, and receiving, by the first AP from the STA and during the time period, the UL transmission in response to the trigger frame.

[0420] In an embodiment, there is a method comprising: transmitting, by a first access point (AP) to a second AP, a first frame indicating amount of uplink (UL) traffic for a station (STA) associated with the first AP; and receiving, by the first AP from the second AP, a second frame indicating: an allocated time of a transmission opportunity (TXOP) obtained by the second AP, an identifier of the first AP, a duration of an uplink (UL) physical layer protocol data unit (PPDU) for an UL transmission from the STA to the first AP during the allocated time; and a modulation and coding scheme (MCS) for the UL PPDU.

[0421] In an embodiment, there is a method comprising transmitting, by a first access point (AP) to a second AP, a first frame indicating uplink (UL) time resource information for an UL transmission from a STA to the first AP, and UL frequency resource information for the UL transmission, and receiving, by the first AP from the second AP, a second frame indicating an allocated time of a transmission opportunity (TXOP) obtained by the second AP, an identifier of the first AP; and a duration of an UL physical layer protocol data unit (PPDU) for the UL transmission, determined based on the UL time resource information and the UL frequency resource information.

[0422] In an embodiment, the UL time resource information is preferred / recommended / selected by the first AP.

[0423] In an embodiment, the UL time resource information comprises a length of the UL PPDU.

[0424] In an embodiment, the UL frequency resource information is preferred / recommended / selected by the first AP.

[0425] In an embodiment, the UL frequency resource information comprises a size of a frequency resource unit (RU) for the UL transmission.

[0426] In an embodiment, there is a computer program product, storable on a computer-readable medium, arranged to, when run on a processor, perform the method of any of claims 1 - 49.

[0427] In an embodiment, there is a device arranged , when implemented in an access point, to perform operations comprising receiving, by a first access point (AP) from a second AP, a first frame indicating an amount of uplink (UL) traffic for a station (STA) associated with the second AP, and transmitting, by the first AP to the second AP, a second frame indicating an allocated time of a transmission opportunity (TXOP) obtained by the first AP; and a time period, within the allocated time, based on the amount of UL traffic and for an UL transmission from the STA to the second AP. In an embodiment, there is a device arranged , when implemented in an access point, to perform operations comprising receiving, by a first access point (AP) from a second AP, a first frame indicating an amount of uplink (UL) traffic for a station (STA) associated with the second AP, and transmitting, by the first AP to the second AP, a second frame indicating a time period, based on the amount of UL traffic, for an UL transmission from the STA to the second AP.

[0428] In an embodiment, there is a device arranged , when implemented in an access point, to perform operations comprising: receiving, by a first access point (AP) from a second AP, a first frame indicating amount of uplink (UL) traffic for a station (STA) associated with the second AP and transmitting, by the first AP to the second AP, a second frame indicating: an allocated time of a transmission opportunity (TXOP) obtained by the first AP, an identifier of the second AP. a duration of an uplink (UL) physical layer protocol data unit (PPDU) for an UL transmission from the STA to the second AP during the allocated time; and a modulation and coding scheme (MCS) for the UL PPDU.

[0429] In an embodiment, there is a device arranged , when implemented in an access point, to perform operations comprising receiving, by a first access point (AP) from a second AP, a first frame indicating uplink (UL) time resource information for an UL transmission from a STA to the second AP, and UL frequency resource information for the UL transmission, and transmitting, by the first AP to the second AP, a second frame indicating: an allocated time of a transmission opportunity (TXOP) obtained by the first AP; an identifier of the second AP, and a duration of an UL physical layer protocol data unit (PPDU) for the UL transmission, determined based on the UL time resource information and the UL frequency resource information.

[0430] In an embodiment, there is a device arranged , when implemented in an access point, to perform operations comprising transmitting, by a first access point (AP) to a second AP, a first frame indicating an amount of uplink (UL) traffic for a station (STA) associated with the first AP and receiving, by the first AP from the second AP, a second frame indicating an allocated time of a transmission opportunity (TXOP) obtained by the second AP and a time period, within the allocated time, based on the amount of UL traffic and for an UL transmission from the STA to the first AP.

[0431] In an embodiment, there is a device arranged , when implemented in an access point, to perform operations comprising transmitting, by a first access point (AP) to a second AP, a first frame indicating an amount of uplink (UL) traffic for a station (STA) associated with the first AP, and receiving, by the first AP from the second AP, a second frame indicating a time period, based on the amount of UL traffic, for an UL transmission from the STA to the first AP.

[0432] Aspects of the embodiments may be implemented in a computer program product, which may be a collection of computer program instructions stored on a computer readable storage device which may be executed by a computer. The instructions may be in any interpretable or executable code mechanism, including but not limited to scripts, interpretable programs, dynamic link libraries (DLLs) or Java classes. The instructions can be provided as complete executable programs, partial executable programs, as modifications to existing programs (e.g. updates) or extensions for existing programs (e.g. plugins). Moreover, parts of the processing of the present invention may be distributed over multiple computers or processors. Storage media suitable for storing computer program instructions include all forms of nonvolatile memory, including but not limited to EPROM, EEPROM and flash memory devices, magnetic disks such as the internal and external hard disk drives, removable disks and CD-ROM disks. The computer program product may be distributed on such a storage medium, or may be offered for download through HTTP, FTP, email or through a server connected to a network such as the Internet.

Claims

CLAIMS:

1. A method comprising : receiving, by a first access point (AP) from a second AP, a first frame indicating an amount of uplink (UL) traffic for a station (STA) associated with the second AP; and transmitting, by the first AP to the second AP, a second frame indicating: an allocated time of a transmission opportunity (TXOP) obtained by the first AP; and a time period, within the allocated time, based on the amount of UL traffic and for an UL transmission from the STA to the second AP.

2. A method comprising: receiving, by a first access point (AP) from a second AP, a first frame indicating an amount of uplink (UL) traffic for a station (STA) associated with the second AP; and transmitting, by the first AP to the second AP, a second frame indicating a time period, based on the amount of UL traffic, for an UL transmission from the STA to the second AP.

3. The method of claim 2, wherein the second frame further indicates an allocated time of a transmission opportunity (TXOP) obtained by the first AP.

4. The method of any of claims 2 or 3, wherein the first frame further indicates an UL transmission parameter for the UL transmission.

5. The method of claim 4, wherein the time period is further based on the UL transmission parameter.

6. The method of claim 5, wherein the UL transmission parameter is selected by the second AP from a plurality of UL transmission parameters.

7. The method of claim 6, wherein the UL transmission parameter is suggested by the second AP for the UL transmission.

8. The method of claim 6, wherein the UL transmission parameter is preferred by the second AP for the UL transmission.

9. The method of any of claims 5 - 8, wherein the UL transmission parameter comprises one or more of a modulation and coding scheme (MCS), a bandwidth size, a resource unit (RU) size, a physical layer protocol data unit (PPDU) type, or a number of spatial streams for the UL transmission.

10. The method of any of claims 2 - 9, wherein the first frame comprises an UL buffer status report (BSR) for the STA, the UL BSR indicating the amount of UL traffic for the STA.

11. The method of claim 10, further comprising: transmitting, by the first AP to the second AP, a third frame soliciting the UL BSR; and receiving, by the first AP from the second AP, the first frame in response to the third frame.

12. The method of claim 11, wherein the third frame comprises a buffer status report poll (BSRP) trigger frame, a basic trigger frame, a poll frame, or a soliciting frame.

13. The method of any of claims 2-12, wherein the second frame further indicates an identifier of the second AP.

14. A method comprising: receiving, by a first access point (AP) from a second AP, a first frame indicating amount of uplink (UL) traffic for a station (STA) associated with the second AP; and transmitting, by the first AP to the second AP, a second frame indicating: an allocated time of a transmission opportunity (TXOP) obtained by the first AP; an identifier of the second AP; a duration of an uplink (UL) physical layer protocol data unit (PPDU) for an UL transmission from the STA to the second AP during the allocated time; and a modulation and coding scheme (MCS) for the UL PPDU.

15. A method comprising : receiving, by a first access point (AP) from a second AP, a first frame indicating: uplink (UL) time resource information for an UL transmission from a STA to the second AP; andUL frequency resource information for the UL transmission; and transmitting, by the first AP to the second AP, a second frame indicating: an allocated time of a transmission opportunity (TXOP) obtained by the first AP; an identifier of the second AP; anda duration of an UL physical layer protocol data unit (PPDU) for the UL transmission, determined based on the UL time resource information and the UL frequency resource information.

16. The method of claim 15, wherein the UL time resource information is preferred / recommended / selected by the second AP.

17. The method of any of claims 15 - 16, wherein the UL time resource information comprises a length of the UL PPDU.

18. The method of any of claims 15 - 17, wherein the UL frequency resource information is preferred / recommended / selected by the second AP.

19. The method of any of claims 15 - 18, wherein the UL frequency resource information comprises a size of a frequency resource unit (RU) for the UL transmission.

20. A method comprising: transmitting, by a first access point (AP) to a second AP, a first frame indicating an amount of uplink (UL) traffic for a station (STA) associated with the first AP; and receiving, by the first AP from the second AP, a second frame indicating: an allocated time of a transmission opportunity (TXOP) obtained by the second AP; and a time period, within the allocated time, based on the amount of UL traffic and for an UL transmission from the STA to the first AP.

21. A method comprising : transmitting, by a first access point (AP) to a second AP, a first frame indicating an amount of uplink (UL) traffic for a station (STA) associated with the first AP; and receiving, by the first AP from the second AP, a second frame indicating a time period, based on the amount of UL traffic, for an UL transmission from the STA to the first AP.

22. The method of claim 21, wherein the second frame further indicates an allocated time of a transmission opportunity (TXOP) obtained by the second AP.

23. The method of any preceding claim wherein the time period is within the allocated time of the TXOP.

24. The method of any of claims 22 - 23, wherein the first frame further indicates an UL transmission parameter for the UL transmission.

25. The method of claim 24, wherein the time period is further based on the UL transmission parameter.

26. The method of claim 25, wherein the UL transmission parameter is selected by the first AP from a plurality of UL transmission parameters.

27. The method of claim 25, wherein the UL transmission parameter is suggested by the first AP for the UL transmission.

28. The method of claim 25, wherein the UL transmission parameter is preferred by the first AP for the UL transmission.

29. The method of any of claims 24 - 28, wherein the UL transmission parameter comprises one or more of a modulation and coding scheme (MCS), a bandwidth size, a resource unit (RU) size, a physical layer protocol data unit (PPDU) type, or a number of spatial streams for the UL transmission.

30. The method of any preceding claim, wherein the UL transmission comprises an UL physical layer protocol data unit (PPDU).

31. The method of any preceding claim, wherein the time period comprises a duration of the UL PPDU.

32. The method of any preceding claim, wherein the UL PPDU is a part of a coordinated orthogonal frequency division multiple access (C-OFDMA) UL transmission.

33. The method of any of claims 24 - 32, wherein the first frame comprises an UL buffer status report (BSR) for the STA, the UL BSR indicating the amount of UL traffic for the STA.

34. The method of claim 33, further comprising: receiving, by the first AP from the second AP, a third frame soliciting the UL BSR; and transmitting, by the first AP to the second AP, the first frame in response to the third frame.

35. The method of claim 34, wherein the third frame comprises a buffer status report poll (BSRP) trigger frame, a basic trigger frame, a poll frame, or a soliciting frame.

36. The method of any preceding claim, wherein the UL BSR is a coordinated orthogonal frequency division multiple access (C-OFDMA) BSR.

37. The method of any preceding claim, wherein the second frame comprises a multi-user request to send triggered TXOP sharing (MU-RTS TXS) trigger frame or a multi -AP trigger frame.

38. The method of any of claims 21 - 37, wherein the second frame further indicates an identifier of the first AP.

39. The method of any preceding claim, wherein the first frame comprises an action frame.

40. The method of any preceding claim, wherein the action frame comprises an information element comprising the amount of UL traffic for the STA.

41. The method of any preceding claim, wherein the first frame comprises a quality of service (QoS) null or data frame.

42. The method of any preceding claim, wherein the QoS null or data frame comprises an aggregated control (A-Control) field comprising the amount of UL traffic for the STA.

43. The method of any of claims 21 - 42, further comprising: transmitting, by the first AP to the STA, a trigger frame; and receiving, by the first AP from the STA and during the time period, the UL transmission in response to the trigger frame.

44. A method comprising: transmitting, by a first access point (AP) to a second AP, a first frame indicating amount of uplink (UL) traffic for a station (STA) associated with the first AP; and receiving, by the first AP from the second AP, a second frame indicating: an allocated time of a transmission opportunity (TXOP) obtained by the second AP; an identifier of the first AP; a duration of an uplink (UL) physical layer protocol data unit (PPDU) for an UL transmission from the STA to the first AP during the allocated time; and a modulation and coding scheme (MCS) for the UL PPDU.

45. A method comprising: transmitting, by a first access point (AP) to a second AP, a first frame indicating:uplink (UL) time resource information for an UL transmission from a STA to the firstAP; andUL frequency resource information for the UL transmission; and receiving, by the first AP from the second AP, a second frame indicating: an allocated time of a transmission opportunity (TXOP) obtained by the second AP; an identifier of the first AP; and a duration of an UL physical layer protocol data unit (PPDU) for the UL transmission, determined based on the UL time resource information and the UL frequency resource information.

46. The method of claim 45, wherein the UL time resource information is preferred / recommended / selected by the first AP.

47. The method of any of claims 45 or 46, wherein the UL time resource information comprises a length of the UL PPDU.

48. The method of any of claims 45 - 47, wherein the UL frequency resource information is preferred / recommended / selected by the first AP.

49. The method of any of claims 45 - 48, wherein the UL frequency resource information comprises a size of a frequency resource unit (RU) for the UL transmission.

50. A computer program product, storable on a computer-readable medium, arranged to, when run on a processor, perform the method of any of claims 1 - 49.

51. A device arranged, when implemented in an access point, to perform operations comprising: receiving, by a first access point (AP) from a second AP, a first frame indicating an amount of uplink (UL) traffic for a station (STA) associated with the second AP; and transmitting, by the first AP to the second AP, a second frame indicating: an allocated time of a transmission opportunity (TXOP) obtained by the first AP; and a time period, within the allocated time, based on the amount of UL traffic and for an UL transmission from the STA to the second AP.

52. A device arranged, when implemented in an access point, to perform operations comprising: receiving, by a first access point (AP) from a second AP, a first frame indicating an amount of uplink (UL) traffic for a station (STA) associated with the second AP; andtransmitting, by the first AP to the second AP, a second frame indicating a time period, based on the amount of UL traffic, for an UL transmission from the STA to the second AP.

53. A device arranged, when implemented in an access point, to perform operations comprising: receiving, by a first access point (AP) from a second AP, a first frame indicating amount of uplink (UL) traffic for a station (STA) associated with the second AP; and transmitting, by the first AP to the second AP, a second frame indicating: an allocated time of a transmission opportunity (TXOP) obtained by the first AP; an identifier of the second AP; a duration of an uplink (UL) physical layer protocol data unit (PPDU) for an UL transmission from the STA to the second AP during the allocated time; and a modulation and coding scheme (MCS) for the UL PPDU.

54. A device arranged, when implemented in an access point, to perform operations comprising: receiving, by a first access point (AP) from a second AP, a first frame indicating: uplink (UL) time resource information for an UL transmission from a STA to the second AP; andUL frequency resource information for the UL transmission; and transmitting, by the first AP to the second AP, a second frame indicating: an allocated time of a transmission opportunity (TXOP) obtained by the first AP; an identifier of the second AP; and a duration of an UL physical layer protocol data unit (PPDU) for the UL transmission, determined based on the UL time resource information and the UL frequency resource information.

55. A device arranged, when implemented in an access point, to perform operations comprising: transmitting, by a first access point (AP) to a second AP, a first frame indicating an amount of uplink (UL) traffic for a station (STA) associated with the first AP; and receiving, by the first AP from the second AP, a second frame indicating: an allocated time of a transmission opportunity (TXOP) obtained by the second AP; and a time period, within the allocated time, based on the amount of UL traffic and for an UL transmission from the STA to the first AP.

56. A device arranged, when implemented in an access point, to perform operations comprising:transmitting, by a first access point (AP) to a second AP, a first frame indicating an amount of uplink (UL) traffic for a station (STA) associated with the first AP; and receiving, by the first AP from the second AP, a second frame indicating a time period, based on the amount of UL traffic, for an UL transmission from the STA to the first AP.

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