WO2025149686A1

WO2025149686A1 - Reverse txop power-saving

Info

Publication number: WO2025149686A1
Application number: PCT/EP2025/050718
Authority: WO
Inventors: Jeongki Kim; Leonardo Alisasis LANANTE; Esmael Hejazi Dinan; Serhat Erkucuk; Tuncer Baykas; Jiayi Zhang; Robert James Davies; Nicholas Smears
Original assignee: Koninklijke Philips NV; Ofinno LLC
Current assignee: Koninklijke Philips NV; Ofinno LLC
Priority date: 2024-01-12
Filing date: 2025-01-13
Publication date: 2025-07-17
Anticipated expiration: 2026-07-12

Abstract

There is provided methods and devices arranged for the controlling media access in a wireless network. The wireless network may comprise a first device and a second device. The first device may obtain a reservation to the wireless medium for a duration and then relinquish the reservation for a part of the duration and be arranged to go into a power-saving state. The first device may receive a power-saving allowed or disallowed indication from another device and enter or not a power-saving state.

Description

REVERSE TXOP POWER-SAVING

FIELD OF THE INVENTION

The present invention relates to wireless networks, in particular local networks such as those using the IEEE 802.11 standard.

BACKGROUND OF THE INVENTION

Wireless networks are frequently very busy with many devices needing to transmit. The heavy occupation of the wireless medium can result in unacceptable delays or latency for some high importance transmissions. Devices in such networks may obtain access to the medium for certain periods in various ways, such as by sensing the medium and starting a transmission. This gives the device a period in which it is allowed to complete its transmission without other devices sending transmissions that collide with those of the device in question. In IEEE 802. 11, the period of freedom to transmit, which is effectively a reservation of the medium, is sometimes referred to a Transmission Opportunity or TXOP. It may occur that while the device having the reservation (the TXOP holder in IEEE 802. 11 terminology), does not need to use all of the reservation period and may also be a device using power-saving mechanisms.

In such a power-saving mechanism, a device may enter a power-saving state. Such states are sometime known as ‘doze’ states. For the present disclosure, these terms are assumed to be synonymous.

SUMMARY OF THE INVENTION

The inventors have realized that where a device attempts to use return part of a reservation (e.g. a TXOP) to another device and enter a power-saving or doze state, problems may arise. For instance, the device may be unavailable to receive urgent transmissions. Therefore, aspects, embodiments and variants of the invention are defined in the appended claims.

In an aspect, there is provided a method of controlling wireless medium access in a wireless network, the network comprising a first device and a second device. The first device may be arranged to enter a power-saving state when it has made a no-data-expected determination, the no-data- expected determination being that it expects to receive no more data, The method may comprise acquiring by the first device, a reservation for access to the wireless medium, the reservation having a first duration, sending, by the first device to the second device, a first message containing an indication that first device is relinquishing (or returning or donating) a first part of the reservation to the second device, receiving, by the first device from the second device, after the first message, a second message containing a power-save disallow indication, the power-save disallow indication instructing the first device to not enter a powersaving state. The method may comprise the first device remaining, in an awake state at least for a second part of the reservation, wherein the second part is contained within the first part.

In an aspect, there is provided a method of controlling wireless medium access in a wireless network, the network comprising a first device and a second device, the first device being arranged to enter a power-saving state when it has made a no-data-expected determination, the no-data- expected determination being that it expects to receive no more data, the first device having sent a request to enter a power-saving state to the second device. The method may comprise acquiring by the first device a reservation for access to the wireless medium, the reservation having a first duration, sending, by the first device to the second device, a first message containing an indication that first device is relinquishing the reservation to the second device, receiving, by the first device from the second device, after the first message, a second message containing a power-saving allowed indication, the power-saving allowed indication indicating that the first device is allowed to enter a power-saving state. The first device may enter a power-saving state based on receiving the power-saving allowed indication.

Thus the first device is arranged to remain awake when instructed not to enter powersaving or to remain awake until allowed to enter power-saving. Because the first device remains available the other (second) device is able to send further urgent data to the first device, even though it had previously indicated that it had (at the time) no further data. This caters for rapidly changing situations - which may be expected when attempt is made to handle urgent (or low-latency) data.

In an embodiment, the first device is arranged to start a No Data Timer after making the no-data-expected determination, and to remain awake at least until the expiry of the No Data Timer or the receipt of one of the power-saving disallow indication or the power-saving allow indication. This had the advantage of limiting how long the first device must remain awake - otherwise it is entirely dependent on instructions from the other device, which may, for various reasons, delay in successfully getting those instructions to the first device.

In an aspect, the first device remains in an awake state at least for a second part of the reservation. The decision to remain in the awake state (and the duration) is based on a characteristic of recent traffic to or from the first device, wherein the first part is contained within the first part. Thus the first device makes the decisions unilaterally, freeing it from dependency on another device whilst still allowing some opportunity to the other device to transmit to it.

In aspects, there are device arranged to act as the first device herein disclosed, as defined in the appended claims.

In an aspect there is provided, a computer program product, storable on a computer- readable medium and arranged, when run a computer to execute the method disclosed herein. BRIEF DESCRIPTION OF THE DRAWINGS

Examples of several of the various embodiments of the present disclosure are described herein with reference to the drawings wherein:

Fig. 1 represents a wireless network.

Fig. 2 represents a frame (i.e. message) exchange in the wireless network of Fig. 1.

Fig. 3 represents various problems that can occur with the frame exchange of Fig. 2.

Fig. 4 represents a frame exchange according to an embodiment.

Fig. 5 represents a frame exchange according to an embodiment.

Fig. 6 represents a frame exchange according to an embodiment.

Fig. 7 represents a frame exchange according to an embodiment.

Fig. 8 is a block diagram illustrating example implementations of a station (STA) and an access point (AP).

Fig. 9 illustrates an example multi-user request to send (MU-RTS) transmission opportunity sharing (TXS) trigger (MRTT) frame which may be used in a TXS procedure.

Fig. 10 illustrates an example of a TXS procedure (Mode =1).

Fig. 11 illustrates an example of a TXS procedure (Mode =2).

Fig. 12 is an example that illustrates a STA enabling or disabling the TXS PS mode in an example implementation.

Fig. 13 is an example that illustrates a STA enabling or disabling the TXS PS mode according to another example implementation.

Fig. 14 is an example that illustrates a STA enabling or disabling the TXS PS mode according to a further example implementation.

Fig. 15 illustrates an example of existing operation whereby a STA may enter a doze state during a target wake time (TWT) service period (SP).

Fig. 16 illustrates an example that illustrates an example TXS procedure.

Fig. 17 illustrates an example of one or more embodiments that may utilize a power saving operation during a TXS procedure.

Fig. 18 illustrates an example of one or more embodiments that may utilize a power saving operation during a TXS procedure.

Fig. 19 illustrates an example of one or more embodiments that may utilize a power saving operation during a TXS procedure.

Fig. 20 illustrates an example of one or more embodiments that may utilize a power saving operation during a TXS procedure.

Fig. 21 illustrates an example of one or more embodiments that may utilize a power saving operation during a TXS procedure.

Fig. 22 illustrates an example of one or more embodiments that may utilize a power saving operation during a TXS procedure Fig. 23 illustrates an example of one or more embodiments that may utilize a power saving operation during a TXS procedure.

Fig. 24 describes different signaling capabilities for one or more embodiments.

Fig. 25 illustrates an example process according to an embodiment.

Fig. 26 illustrates an example process according to an embodiment.

Fig. 27 illustrates an example of one or more embodiments that may utilize a power saving operation during a TXS procedure.

DETAILED DESCRIPTION

In the appended figures, same references designate same elements.

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

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.

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.

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.

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. 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.

It is desirable for wireless networks to handle low latency traffic. IEEE 802.1 Ibn, currently under development, has such a goal. Such traffic can be characterized by the presence of PPDUs that need to be delivered urgently within a short delay bound and which therefore may need to pre-empt or take priority over traffic with longer or no latency bounds. The present disclosure is described in the context, and uses terminology from, the IEEE 802.11 standard. Those skilled in the art will be able to apply the teaching to other types of wireless network.

Fig. 1 represents a wireless network 1 where an AP (AP), and first, second and third STAs (STA1, STA2, STA3) is communicating. In IEEE 802.11, this is known as a Basic Service Set (BSS). Analogous entities exist in other types of wireless network.

FIG. 12 is a block diagram 1200 illustrating example implementations of a STA 1210 and an AP 1260. As shown in FIG. 12, STA 1210 may include at least one processor 1220, a memory 1230, and at least one transceiver 1240. AP 1260 may include at least one processor 1270, a memory 1280, and at least one transceiver 1290. Processor 1220/1270 may be operatively connected to memory 1230/1280 and/or to transceiver 1240/1290.

Processor 1220/1270 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 1220/1270 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.

Memory 1230/1280 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 1230/1280 may comprise one or more non-transitory computer readable mediums. Memory 1230/1280 may store computer program instructions or code that may be executed by processor 1220/1270 to carry out one or more of the operations/embodiments discussed in the present application. Memory 1230/1280 may be implemented (or positioned) within processor 1220/1270 or external to processor 1220/1270. Memory 1230/1280 may be operatively connected to processor 1220/1270 via various means known in the art.

Transceiver 1240/1290 may be configured to transmit/receive radio signals. In an embodiment, transceiver 1240/1290 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 1240/1290.

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.

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.

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.

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.

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 a SP duration. The TWT SP may repeat every SP interval.

In a way of obtaining a reservation for a time period (e.g. a TXOP) in wireless networks, a first device, or STA, (STA1) might issue a Ready-To-Send (RTS) message to indicate to a second device (STA2) the availability and quantity of low latency data. On reception, STA2 responds with a Clear-To-Send (CTS) message indicating that it is ready to receive the low latency data and STA1 may then transmit the low latency PPDU in the agreed time frame. By reservation, it may be understood that other device s/stations will refrain from attempting to transmit during the reservation period. It should be noted that, whilst the present disclosure uses the example of TXOPs acquired via an RTS/CTS frame exchange, other methods of obtaining a TXOP or reservation period exist and that the actual means of obtaining the TXOP is not important.

In IEEE 802.11, RTS (Ready-To-Send) ([1], 9.3. 1.2) and CTS (Clear-To-Send) ([1], 9.3.1.3) frames may be exchanged by STAs as part of a virtual CS (Carrier Sense) mechanism. Each frame comprises a Duration field that indicates the period of time that the medium should be reserved for the transmission of the Data frame and the returning Ack frame. Each frame further comprises a Receiver Address (RA) field, being the MAC address of the intended destination STA and, in the case of the RTS but not the CTS, a Transmitter (i.e. sender) Address (TA) field, being the MAC address of the transmitting STA. The other STAs, upon hearing the RTS use the Duration field to set their NAVs to a value based on the Duration field, STAs that received the RTS do not adjust their NAVs upon receipt of the RTS whereas those that did not receive the RTS update their NAVs according to the data in the CTS (which contains the same duration as was in the RTS frame). Fig. 2 represents a situation where STA1 has sent an RTS frame 201 to the AP and established a reservation or TXOP, the length of the reservation/TXOP being determined by the duration field in the RTS frame 201. The AP has responded with a CTS frame 202. In IEE 802.11, both the AP and STA2 update their NAVs to this reservation length - as shown by the bars 203 under the lines for the AP and STA2. Frame exchange 204 - 205 occurs between STA1 and the AP. It is desirable that any reservation time that will not be used is not wasted. Therefore, it is possible for STA1 to signal that it is ‘returning the unused part of the reservation/TXOP’ to the AP by sending a control frame 206. This might also be expressed by stating that STA1 is relinquishing part of the TXOP - in this case to the AP. This allows the AP to cancel the reservation (as far as it is concerned) by resetting its NAV, effectively deducting the hatched part of the NAV bar 210 for the AP. The AP is then able to initiate frame exchange 207 - 208 with STA1. STA2, however maintains its NAV at the original value and so refrains from trying to transmit.

FIG. 13 illustrates an example MRTT frame 1300 which may be used in a TXS procedure. As shown in FIG. 13, example MRTT frame 300 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.

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. 13, 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.

The trigger type subfield indicates that frame 1300 is an MRTT frame.

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 one (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. 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. 13, one or more of the following subfields: AID12, RU allocation, allocation duration, reserved, or PS160.

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

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

The allocation duration subfield may indicate a time allocated by an AP transmitting MRTT frame 300. 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.

FIG. 14 illustrates an example 1400 of a TXOP Sharing (TXS) procedure (Mode =1). As shown in FIG. 14, the TXS procedure may begin by an API transmitting an MRTT frame 11420 to a STA 1411. MRTT frame 1420 may allocate a portion of a TXOP obtained by API to STA 1411 and may indicate a TXS mode equal to 1. STA 1411 receiving MRTT frame 1420 may use the allocated time to transmit one or more non-TB PPDUs to API . The one or more non-TB PPDUs may comprise a data frame, a control frame, a management frame, or an action frame.

In an example, MRTT frame 1420 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).

STA 1411 may respond to MRTT frame 1420 by transmitting a CTS frame 421 to API . Subsequently, STA 1411 may transmit non-TB PPDUs 1422, 1424 comprising one or more data frame to API during the first time period indicated in MRTT frame 1420. In an example, API may transmit one or more BA frames 1423, 1425 in response to the one or more data frames contained in non-TB PPDUs 1422, 1424 received from STA 1411.

FIG. 15 illustrates an example 1500 of a TXS procedure (Mode =2). As shown in FIG. 15, the TXS procedure may begin by an API transmitting an MRTT frame 1520 to a STA1. MRTT frame 1520 may allocate a portion of a TXOP obtained by APlto STAland may indicate a TXS mode equal to 2. STA1 receiving MRTT frame 1520 may use the allocated time to transmit one or more non-TB PPDUs to STA2. The one or more non-TB PPDUs may comprise a data frame, a control frame, a management frame, or an action frame.

In an example, MRTT frame 1520 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).

STAlmay respond to MRTT frame 1520 by transmitting a CTS frame 1521 to API. Subsequently, STA1 may transmit non-TB PPDUs 1522, 1524 comprising one or more data frame to STA2 during the first time period indicated in MRTT frame 1520. In an example, STA2 may transmit one or more BA frames 1523, 1525 in response to the one or more data frames contained in non-TB PPDUs 1522, 1524 received from STA1.

In an implementation, API and STA1 may exchange indications of support of the TXS Power save (PS) mode prior to the beginning of example 800. For example, STA1 may include an indication of support of the TXS PS mode in an association request frame to API. STA1 may set a TXS PS mode field (or a TXS PS Support field) to 1 in the association request frame to indicate support of the TXS PS mode. The TXS PS mode field (or TXS PS Support field) may be provided in an EHT MAC Capabilities Information field of the association request frame. API may include an indication of support of the TXS PS mode in an association response frame to STA1. STA1 may set a TXS PS mode field (or a TXS PS Support field) to 1 in the association response frame to indicate support of the TXS PS mode. The TXS PS mode field (or TXS PS Support field) may be provided in an EHT MAC Capabilities Information field of the association response frame.

In an implementation, when STA1 indicates support of the TXS PS mode (e.g., TXS PS field set to 1 in the association request frame to API), API may refrain from transmitting to STA1 during the first time period (in which STA1 is not allocated) because STA1 may enter the doze state during the first time period (even if STA1 does not actually enter the doze state during the first time period). API may continue to use this behavior with respect to STA1 for any subsequent TXS time period during which STA1 is not allocated. That is, based on STA1 having indicated support of the TXS PS mode, API may not transmit to STA1 during TXS time periods in which STA1 is not allocated.

STAs may also use power-saving mechanisms, such as the TWT mechanism described previously, and enter a power-saving or ‘doze’ state. In the power-saving (doze) state, the STA powers down some of its circuitry and so has reduced capabilities (particularly in reception) as compared to its awake state. For example, a STA may power-down all but one of its multiple receive chains, making it unable to receive Multi-Input-Multi-Output (MIMO) transmissions. Of particular importance, it will be unable to receive multi-user (MU) PDDUs. If it powers all of its transceiver down, it will be unable to receive anything. It may be the case that the STA will base the moment it enters the power-saving state on whether it has determined that it is still expecting more data or not. It may base this determination on, what is called in IEEE 802.11 a ‘More Data’ indication contained in a preceding transmission from the other device with which it is communicating. When this More Data indication has a value of 0 (in IEEE 802. 11, the receiving device understands that there is no more data for it pending at the other device i.e. it is to expect no more traffic for the time being.

Fig. 3 represents a situation that may arise when STA1 uses a power-save mechanism just after returning a reservation/TXOP to the AP. The data frame 207 from the AP carries a More Data indication equal to zero (indicating that there is no more data to follow). Consequently, STA1 concludes that it is not expecting another transmission and, after sending the ACK frame 208 to the AP, STA1 enters a power-saving state. However, within a short space of time, the AP receives data in its buffer and tries to send DL frame 209 to STA1, which fails to be received because STA1 is already sleeping - the failure is denoted by the dashed box for frame 209. Whilst the AP could use the returned TXOP duration for communication with another station, it nevertheless has not been able to deliver some of its data to STA1.

Furthermore, according to existing behavior, an AP may not use returned remaining time of a time period to transmit to, or to allocate a portion of the remaining time to, a STA that indicated support of the TXS PS mode and that was not allocated in the time period. Indeed, as described above, when a STA indicates support of the TXS PS mode and is not allocated during a time period, the AP may not transmit to the STA during the time period because the STA may enter the doze state during the time period. For example, referring to FIG. 3 assuming that STA2 indicated support of the TXS PS mode to API (e.g., TXS PS field set to 1 in an association request frame to API), API may not transmit to STA2 during the returned time period (in which STA2 is not allocated) even if STA1 were to return the remaining time of the first time period to API after receiving a ACK frame. Similarly, API may not allocate a portion of the returned remaining time to another STA. This may occur even when the STA does not enter the doze state during the first time period.

This behavior may lead to inefficiencies as the AP may be limited in the ways it may use returned remaining time of a TXS time period. For example, the AP may have buffered downlink traffic for a STA that was not allocated in the TXS time period and that has indicated support of the TXS PS mode. Although the STA may be in the awake state during the TXS time period, the AP must wait until the end of the TXS time period before it may transmit the buffered downlink traffic to the STA. In another example, the AP may wish to share a portion of the returned remaining time with the STA. But as the AP may not transmit to the STA during the TXS time period, the AP may not send the time allocation to the STA even though the STA may be in the awake state during the TXS time period.

Fig. 4 represents an exemplary use of an embodiment. Frame exchanges 201 - 206 occur as described in relation to Fig. 3. STA1 has sent an indication to the AP at some point that it is using a power-save operation so the AP is aware that STA1 is intending to go into a power-saving (power-saving) state. In frame 407, the AP includes a ‘Disallow Power-saving’ (DD) indication. This causes STA1 to abandon its transition to the power-saving state and so remain awake to receive the DL frame 209. The AP may decide to include the DD indication in frame 407 on the basis of a characteristic of the data it has recently transmitted or is currently transmitting to STA1. The characteristic may be something like the priority, TID or Access Category. The MAC layer of the AP may also have received an indication from another source such as a higher layer that it should not allow STA1 to transition into power-saving. Even though frame 407 may still contain a More Data = 0 indication, because of the DD indication, STA1 remains awake.

In a variant, the AP starts a No-Data-Timer upon transmission of the frame containing the More Data = 0 indication. If the No-Data-Timer expires before more data arrives, then the DD indication is not sent. The No-Data-Timer may have a fixed value or the AP may select the value based on a characteristic of recent traffic to and/or from STA1. The characteristic may be something like the priority, TID or Access Category.

Fig. 5 represents an exemplary use of an embodiment. Frame exchanges 201 - 206 occur as described in relation to Fig. 3. STA1 has sent an indication to the AP at some point that it is using a power-save operation so the AP is aware that STA1 is intending to go into a power-saving state. The AP sends a frame 207 with a More Data = 0 as with the situation in Fig. 3. Upon the receipt of frame 207 or upon having sent the ACK 208, STA1 may start a ‘No Data’ timer. If nothing else happens to STA1, when the No Data Timer expires, STA1 may enter a power-saving state. A short time after the ACK frame 208 (e.g. a SIFS), the AP sends a frame 501 containing a DD indication. Because STA1 is arranged to remain awake awaiting the expiry of the No Data Timer (i.e. a remain-awake duration), after sending its last frame (the ACK 208), it is still available to receive frames. In a variant on this embodiment, STA1 may be arranged to abandon a transition to the power-saving state upon reception, within the remain- awake duration, of any frame addressed to it. The value to which the No Data Timer is set may be a fixed value or may be based on a characteristic of recent or the last traffic the STA has received. The characteristic may be something such as the priority, TID or Access Category of the data. For example, the higher the priority of the traffic, the longer the STA remains awake. If the traffic was low priority, the STA may set the remain-awake duration to equal an interframe space - it may be convenient to choose an interframe space longer than the SIFS because the AP may be able to send a frame 501 just after a SIFS after the ACK frame 208. In a variant, the STA1 may calculate the remain-awake duration on the basis of the characteristic of the recent/last traffic. In a variant, the AP may send, at some point, a value for the STA to use as a remain-awake duration - for example as an indication contained in frame 207.

In a variant, STA1 transitions to the power-saving state upon the remain -awake duration expiring and nothing having occurrent to the STA1.

In a variant, the DD indication may be included in an earlier frame from the AP.

In a related variant, STA1 may abandon its attempt to transition into a power-saving state if the recent/last traffic had a priority above a threshold.

Alternatively, the AP may send the DD indication frame 501 in a format which even a dozing STA is able to receive - for example, a single-antenna chain mode. An advantage to using such a ‘power-saving-state-receivable’ format is that the remain-awake duration could be reduced or dispensed with. Where the DD frame 501 is in a ‘power-saving-state receivable’ format, STA1 may be arranged to re-awake should it have transitioned to a power-saving state.

Fig. 6 represents an exemplary use of an embodiment. Frame exchanges 201 - 206 occur as described in relation to Fig. 3 - 5. STA 1 has sent an indication to the AP at some point that it is using a power-save operation so the AP is aware that STA1 requests to go into a power-saving state. Frame 207 from the AP may still contain a More Date = 0 indication. STA1 replies with an ACK 208. The AP starts a timer while STA1 remains awake, awaiting permission to enter the power-saving state. If the timer (the No Data Timer) expires with no data for STA1 having arrived in the AP’s buffer, the AP sends a ‘Power- saving Allowed’ (DA) frame 601. STA1 enters a power-saving state at the end of the DA frame 601 (or sometime after) and the AP and other STAs may use the time for something else - such as, by way of example, a DL frame 602 from the AP to STA2.

Similarly to the embodiment of Fig. 5, the No-Data Timer may have a fixed value or may have its value based on a characteristic of recent or the last traffic exchanged with STA1. The characteristic may be the priority, TID or Access Category. For higher the priority/urgency traffic, the timer may be set with a longer expiry time whereas lower priority/urgency traffic may cause the timer to have a shorter expiry time.

Fig. 7 represents a variant or extension of the embodiment of Fig. 6. STA2 has detected the RTS 201 of STA1 and the CTS 202 of the AP. It enters a power-saving state. The DA frame 601 may be sent addressed to STA1 (RA = STA1) and with a format that dozing STAs can detect and decode, for example needing only a single RX chain. Because the RA = STA1, STA2 may deduce the power-saving- allowed instruction does not apply to it and STA2 may be arranged to interpret this as an instruction to wake up, much as it might do with some other frames. The advantage of using the DA frame in this way is that a further wake-up frame for STA2 is not needed.

In a variant on the above embodiment, STA2 enters a power-saving state for a duration equal to that in the RTS frame and automatically wakes at the end of what would be the TXOP for STA1. In a further variant, the RTS frame is modified by the addition of an extra subfield which contains a power-saving duration. This could be used by STAs not concerned by the TXOP to enter a power-saving state and then wake without need for the overhead of a specific waking protocol.

In a further variant, the power-saving duration i.e. the time the STA remains in a powersaving state from receiving the frame indicating a TXOP for another STA and the time it wakes up automatically may be negotiated/set at some earlier time by other messages. These other messages may include an OPS frame or FILS Discovery frame, in the case of IEEE 802.11.

In an embodiment, the AP and STA1 have performed a negotiation to choose which ‘polarity’ of the protocol is to be used i.e. whether the AP will issue DD or DA indications. The advantage of this is that STA1 knows whether or not to set a No-Data-Timer - if STA1 were to set a No- Data-Timer and then go into a power-saving state when the AP was expecting STA1 to remain awake until it had sent a DA indication, this might be less convenient.

In an embodiment, the DD and DA indications are single-bit flags. On possibility for these may be to use one of the reserved bits in the various header portions of difference frame types.

FIG. 16 illustrates a first example 1600, where the frame that indicates enabling or disabling of the TXS PS mode at the STA may be an association request frame or a reassociation request frame. As shown in FIG. 16, example 1600 includes an AP 1602 and STAs 1604, 1606, and 1608. One or more of STAs 1604, 1606, and 1608 may be associated with AP 1602. STAs 1604, 1606, and/or 1608 may support the TXS PS mode as described above. As shown in FIG. 16, example 1600 may begin with STA 1608 transmitting an association (or reassociation) request frame 1610 to AP 1602. In an example, association request frame 1610 may comprise a TXS PS mode field (or a TXS PS Support field). In example 1600, the TXS PS mode field (or TXS PS Support field) may be set to 1 to indicate enabling of the TXS PS mode at STA 1608. The TXS PS mode field (or TXS PS Support field) may be provided in an EHT MAC Capabilities Information field of the association request frame. AP 1602 may respond to association request frame 1610 by transmitting an association response frame 1612 to STA 1608. In an example, association response frame 1612 may comprise a TXS PS mode field (or a TXS PS Support field). In example 1600, the TXS PS mode field (or TXS PS Support field) may be set to 1 to indicate support of the TXS PS mode at AP 1602. The TXS PS mode field (or TXS PS Support field) may be provided in an EHT MAC Capabilities Information field of the association response frame.

Subsequently, AP 1602 may transmit a frame 1614 to allocate a portion of an obtained TXOP to STA 1604. Frame 1614 may comprise a TXOP sharing mode subfield, an AID 12 subfield, and a first time period (e.g., X us). The TXOP sharing mode subfield may indicate a triggered TXOP sharing procedure. For example, the TXOP sharing mode subfield may be set to a non-zero value (e.g., 1, 2, . . .) which indicates the triggered TXOP sharing mode 1 or the triggered TXOP sharing mode 2. The AID 12 subfield may be set to the AID of a STA that may use the first time period for transmitting and receiving one or more frame. For example, the AID 12 subfield field may be set to the AID of STA 1604. The first time period may be specified in units of microseconds or some other unit of time. In an example, frame 1614 may be an MRTT frame.

On receiving frame 1614, STA 1604 may transmit a frame 1616 to AP 1602. In an example, frame 1616 may be a CTS frame. STA 1604 may subsequently transmit a non-TB PPDU comprising a data frame 1618 to STA 1606 during the first time period. STA 1606 may transmit a BA frame 1620 to STA 1604 in response to data frame 1618.

Based on receiving frame 1614 which does not allocate STA 1608 during the first time period, and the TXS PS mode being enabled at STA 1608, STA 1608 may transition to a doze state during the first time period. In accordance with the TX PS mode, STA 1608 may transition to the doze state: after STA 1608 receives frame 1614 and before STA 1608 receives frame 1616 in response to frame 1614; after STA 1608 receives frame 1616 in response to frame 1614; or if STA 1608 does not receive a third frame during a second time period after STA 1608 receives frame 1614. The third frame may be a data frame, a control frame, or a management frame. A value of the second time period may be a fixed value or may be signaled by a fourth frame sent by AP 1602. The fourth frame may be a beacon frame, a probe response frame, or an association response frame.

In an implementation, STA 1608 may maintain the doze state during a portion of the first time period after STA 1608 transitions to the doze state. In an implementation, STA 1608 may return to an awake state at the end of the first time period or at least from the end of the first time period. In an implementation, AP 1602 may not transmit a frame to STA 1608 during the first time period. AP 1602 may transmit a frame to STA 1608 after the first time period. In an example (not shown in FIG. 16), AP 1602 may receive from STA 1604, within the first time period, a frame indicating release or return of a remaining time of the first time period. The frame may comprise a QoS Data frame or a QoS Null frame that includes an HE variant HT Control field with a CAS Control subfield with the RDG/More PPDU subfield equal to 0. Based on the TXS PS mode being enabled at STA 1608, AP 1602 may wait for an end of the remaining time before transmitting a frame to STA 1608. In an example, AP 1602 may use the remaining time to transmit a frame to STA 1604 or STA 1606 (assuming STA 1604 or STA 1606 is in the awake state) or to another STA (not shown in FIG. 16, e.g., a legacy STA that does not support TXS PS mode). In another example, AP 1602 may allocate a portion of the remaining time to STA 1606.

In example 1600, STA 1608 may return to the awake state after the end of the first time period or at least from the end of the first time period. Subsequently, STA 1608 may transmit an association (or reassociation) request frame 1622 to AP 1602. In an example, association request frame 1622 may comprise a TXS PS mode field (or a TXS PS Support field). In example 1600, the TXS PS mode field (or TXS PS Support field) may be set to 0 to indicate disabling of the TXS PS mode at STA 1608. The TXS PS mode field (or TXS PS Support field) may be provided in an EHT MAC Capabilities Information field of association request frame 1622. AP 1602 may respond to association request frame 1622 by transmitting an association response frame 1624 to STA 1608. In an example, association response frame 1624 may comprise a TXS PS mode field (or a TXS PS Support field). In example 1600, the TXS PS mode field (or TXS PS Support field) may be set to 1 to indicate support of the TXS PS mode at AP 1602. The TXS PS mode field (or TXS PS Support field) may be provided in an EHT MAC Capabilities Information field of the association response frame.

Subsequently, AP 1602 may transmit a frame 1626 to allocate a portion of an obtained TXOP to STA 1604. Frame 1626 may comprise a TXOP sharing mode subfield, an AID 12 subfield, and a first time period (e.g., X us). The TXOP sharing mode subfield may indicate a triggered TXOP sharing procedure. For example, the TXOP sharing mode subfield may be set to a non-zero value (e.g., 1, 2, . . .) which indicates the triggered TXOP sharing mode 1 or the triggered TXOP sharing mode 2. The AID 12 subfield may be set to the AID of a STA that may use the first time period for transmitting and receiving one or more frame. For example, the AID 12 subfield field may be set to the AID of STA 1604. The first time period may be specified in units of microseconds or some other unit of time. In an example, frame 1626 may be an MRTT frame.

On receiving frame 1626, STA 1604 may transmit a frame 1628 to AP 1602. In an example, frame 1616 may be a CTS frame. STA 1604 may subsequently transmit a non-TB PPDU comprising a data frame 1630 to STA 1606 during the first time period. STA 1606 may transmit a BA frame 1632 to STA 1604 in response to data frame 1630.

On receiving frame 1626 which does not allocate STA 1608 during the first time period, and based on the TXS PS mode being disabled at STA 1608, STA 1608 may remain in the awake state during the first time period. In an example (not shown in FIG. 16), AP 1602 may receive from STA 1604, within the first time period, a frame indicating release or return of a remaining time of the first time period. The frame may comprise a QoS Data frame or a QoS Null frame that includes an HE variant HT Control field with a CAS Control subfield with the RDG/More PPDU subfield equal to 0. In an example, based on the TXS PS mode being disabled at STA 1608, AP 1602 may transmit a frame to STA 1608 during the remaining time of the first time period. In another example, based on the TXS PS mode being disabled at STA 1608, AP 1602 may allocate a portion of the remaining time to STA 1608. STA 1608 may use the allocated portion of the remaining time to transmit to AP 1602 or to another STA depending on the indicated TXS mode.

An advantage of the first example is that it reuses existing (re)association request/response frames (with minor modification) to enable a STA to signal enabling or disabling of the TXS mode to an AP. However, as (re)association request/response frames may be potentially large in size due to containing information regarding various capabilities supported by the STA/AP, the first example may result in increased signaling overhead. The construction of (re)association request/response frames may also require relatively large processing times at the STA/AP. The signaling by the STA, and the acknowledgment by the AP, of a TXS PS mode state change at the STA may thus require a substantial amount of time, leading to sub-optimal operation.

In another example, the frame that indicates enabling or disabling of the TXS PS mode at the STA may be separate from the frame that signals support of the TXS PS mode at the STA. In embodiments, the frame may be a QoS data frame, a QoS null frame, an action frame, a control frame, or a management frame. The frame may comprise an element or subfield indicating the enabling or disabling of the TXS PS mode at the STA.

FIG. 17 is an example 1700 that illustrates such an embodiment. As shown in FIG. 17, example 1700 includes an AP 1702 and STAs 1704, 1706, and 1708. One or more of STAs 1704, 1706, and 1708 may be associated with AP 1702. STAs 1704, 1706, and/or 1708 may support the TXS PS mode as described above.

FIG. 17 illustrates an example that may begin with STA 1708 transmitting an association (or reassociation) request frame 1710 to AP 1702. In an example, association request frame 1710 may comprise a TXS PS mode field (or a TXS PS Support field). In example 1700, the TXS PS mode field (or TXS PS Support field) may be set to 1 to indicate support of the TXS PS mode by STA 1708. The TXS PS mode field (or TXS PS Support field) may be provided in an EHT MAC Capabilities Information field of association request frame 1710.

In an implementation, support of the TXS PS mode by STA 1708 may include STA 1708 being able to perform a TXS PS mode operation in a defined condition. In an implementation, the TXS PS mode operation may comprise STA 1708 entering a doze state during a time period of a TXOP. The defined condition may comprise STA 1708 not being allocated by AP 1702 during the time period of the TXOP. In an implementation, support of the TXS PS mode by STA 1708 may include STA 1708 being able to transmit to an AP a frame indicating enabling or disabling of the TXS PS mode as described herein. In an embodiment, the frame may include a TXS PS (TPS) Control subfield (further described below) that indicates enabling or disabling of the TXS PS mode at STA 1708. The TPS Control subfield may include a TPS Disabling subfield that carries the indication of enabling or disabling of the TXS PS mode at STA 1708. In an implementation, support of the TXS PS mode by STA 1708 may include STA 1708 being capable of entering the doze state during a TXS time period that is not allocated to STA 1708 (e.g., by an MRTT frame) when STA 1708 sets the TPS Disabling subfield to 0.

AP 1702 may respond to association request frame 1710 by transmitting an association response frame 1712 to STA 1708. In an example, association response frame 1712 may comprise a TXS PS mode field (or a TXS PS Support field). In example 1700, the TXS PS mode field (or TXS PS Support field) may be set to 1 to indicate support of the TXS PS mode by AP 1702. The TXS PS mode field (or TXS PS Support field) may be provided in an EHT MAC Capabilities Information field of association response frame 1712.

In an implementation, support of the TXS PS mode by AP 1702 may include AP 1702 being able to receive from a STA a frame indicating enabling or disabling of the TXS PS mode at the STA as described herein. In an embodiment, the frame may include a TPS Control subfield that indicates enabling or disabling of the TXS PS mode at the STA. The TPS Control subfield may include a TPS Disabling subfield that carries the indication of enabling or disabling of the TXS PS mode at the STA. In an implementation, support of the TXS PS mode by AP 1702 may further include AP 1702 being able to transmit to the STA an acknowledgment of the frame indicating enabling or disabling of the TXS PS mode at the STA. In an implementation, support of the TXS PS mode by AP 1702 may further include AP 1702 being capable of not transmitting (or refraining from transmitting) any frame, during a TXS time period, to a STA that sets the TPS Disabling subfield to 0 when the TXS time period is not allocated to the STA (e.g., by an MRTT frame).

Subsequently, in an example, STA 1708 may transmit a frame 1734 indicating enabling of the TXS PS mode at STA 1708. Frame 1734 may be a QoS data frame, a QoS null frame, an action frame, a control frame, or a management frame. Frame 1734 may comprise an element or subfield that may be used to indicate enabling or disabling of the TXS PS mode at STA 1708.

In an example, frame 1734 may be a QoS data or a QoS null frame. The QoS data or QoS null frame may comprise an A-Control field that carries an indication of enabling or disabling the TXS PS mode at STA 1708. The A-Control field may be carried in an HT Control field of the QoS data frame or QoS null frame. In an embodiment, the A-Control field may comprise a TPS Control subfield. The TPS Control subfield may include a TPS Disabling subfield. The TPS Disabling subfield may be set to 0 to indicate enabling of the TXS PS mode at STA 1708 and may be set to 1 to indicate disabling of the TXS PS mode at STA 1708. The TPS Control subfield may further include Reserved bits.

In another example, frame 1734 may be an action frame. The action frame may comprise an element/field indicating enabling or disabling the TXS PS mode at STA 1708. In an example, the action frame may be an EML Operating Mode Notification frame. In an embodiment, the action frame may comprise a TPS Disabling subfield. The TPS Disabling subfield may be set to 0 to indicate enabling of the TXS PS mode at STA 1708 and may be set to 1 to indicate disabling of the TXS PS mode at STA 1708. The TPS Control subfield may further include Reserved bits.

In an implementation, AP 1702 may acknowledge frame 1734 by transmitting an acknowledgement frame 1736 to STA 1708. Acknowledgment frame 1736 may be an ACK frame or a BA frame.

Subsequently, AP 1702 may transmit a frame 1714 to allocate a portion of an obtained TXOP to STA 1704. Frame 1714 may comprise a TXOP sharing mode subfield, an AID 12 subfield, and a first time period (e.g., X us). The TXOP sharing mode subfield may indicate a triggered TXOP sharing procedure. For example, the TXOP sharing mode subfield may be set to a non-zero value (e.g., 1, 2, . . .) which indicates the triggered TXOP sharing mode 1 or the triggered TXOP sharing mode 2. The AID 12 subfield may be set to the AID of a STA that may use the first time period for transmitting and receiving one or more frame. For example, the AID 12 subfield field may be set to the AID of STA 1704. The first time period may be specified in units of microseconds or some other unit of time. In an example, frame 1714 may be an MRTT frame.

On receiving frame 1714, STA 1704 may transmit a frame 1716 to AP 1702. In an example, frame 1716 may be a CTS frame. STA 1704 may subsequently transmit a non-TB PPDU comprising a data frame 1718 to STA 1706 during the first time period. STA 1706 may transmit a BA frame 1720 to STA 1704 in response to data frame 1718.

Based on receiving frame 1714 which does not allocate STA 1708 during the first time period, and the TXS PS mode being enabled at STA 1708, STA 1708 may transition to a doze state during the first time period. In accordance with the TX PS mode, STA 1708 may transition to the doze state: after STA 1708 receives frame 1714 and before STA 1708 receives frame 1716 in response to frame 1714; after STA 1708 receives frame 1716 in response to frame 1714; or if STA 1708 does not receive a third frame during a second time period after STA 1708 receives frame 1714. The third frame may be a data frame, a control frame, or a management frame. A value of the second time period may be a fixed value or may be signaled by a fourth frame sent by AP 1702. The fourth frame may be a beacon frame, a probe response frame, or an association response frame.

In an implementation, STA 1708 may maintain the doze state during a portion of the first time period after STA 1708 transitions to the doze state. In an implementation, STA 1708 may return to an awake state at the end of the first time period or at least from the end of the first time period. In an implementation, AP 1702 may not transmit a frame to STA 1708 during the first time period. AP 1702 may transmit a frame to STA 1708 after the first time period. In an example (not shown in FIG. 17), AP 1702 may receive from STA 1704, within the first time period, a frame indicating release or return of a remaining time of the first time period. The frame may comprise a QoS Data frame or a QoS Null frame that includes an HE variant HT Control field with a CAS Control subfield with the RDG/More PPDU subfield equal to 0. Based on the TXS PS mode being enabled at STA 1708, AP 1702 may wait for an end of the remaining time before transmitting a frame to STA 1708. In an example, AP 1702 may use the remaining time to transmit a frame to STA 1704 or STA 1706 (assuming STA 1704 or STA 1706 is in the awake state) or to another STA (not shown in FIG. 17, e.g., a legacy STA that does not support TXS PS mode). In another example, AP 1702 may allocate a portion of the remaining time to STA 1706.

In example 1700, STA 1708 may return to the awake state after the end of the first time period or at least from the end of the first time period. Subsequently, STA 1708 may transmit a frame 1738 indicating disabling of the TXS PS mode at STA 1708. Frame 1738 may be a QoS data frame, a QoS null frame, an action frame, a control frame, or a management frame. Frame 1738 may comprise an element or subfield that may be used to indicate enabling or disabling of the TXS PS mode at STA 1708. In an example, frame 1738 may be a QoS data or a QoS null frame. The QoS data or QoS null frame may comprise an A-Control field that carries an indication of enabling or disabling the TXS PS mode at STA 1708. The A-Control field may be carried in an HT Control field of the QoS data frame or QoS null frame. In another example, frame 1738 may be an action frame. The action frame may comprise an element/field indicating enabling or disabling the TXS PS mode at STA 1708. In an example, the action frame may be an EML Operating Mode Notification frame.

In an implementation, AP 1702 may acknowledge frame 1738 by transmitting an acknowledgement frame 1740 to STA 1708. Acknowledgment frame 1740 may be an ACK frame or a BA frame.

Subsequently, AP 1702 may transmit a frame 1726 to allocate a portion of an obtained TXOP to STA 1704. Frame 1726 may comprise a TXOP sharing mode subfield, an AID 12 subfield, and a first time period (e.g., X us). The TXOP sharing mode subfield may indicate a triggered TXOP sharing procedure. For example, the TXOP sharing mode subfield may be set to a non-zero value (e.g., 1, 2, . . .) which indicates the triggered TXOP sharing mode 1 or the triggered TXOP sharing mode 2. The AID 12 subfield may be set to the AID of a STA that may use the first time period for transmitting and receiving one or more frame. For example, the AID 12 subfield field may be set to the AID of STA 1704. The first time period may be specified in units of microseconds or some other unit of time. In an example, frame 1726 may be an MRTT frame.

On receiving frame 1726, STA 1704 may transmit a frame 1728 to AP 1702. In an example, frame 1716 may be a CTS frame. STA 1704 may subsequently transmit a non-TB PPDU comprising a data frame 1730 to STA 1706 during the first time period. STA 1706 may transmit a BA frame 1732 to STA 1704 in response to data frame 1730.

On receiving frame 1726 which does not allocate STA 1708 during the first time period, and based on the TXS PS mode being disabled at STA 1708, STA 1708 may remain in the awake state during the first time period. In an example (not shown in FIG. 17), AP 1702 may receive from STA 1704, within the first time period, a frame indicating release or return of a remaining time of the first time period. The frame may comprise a QoS Data frame or a QoS Null frame that includes an HE variant HT Control field with a CAS Control subfield with the RDG/More PPDU subfield equal to 0. In an example, based on the TXS PS mode being disabled at STA 1708, AP 1702 may transmit a frame to STA 1708 during the remaining time of the first time period. In another example, based on the TXS PS mode being disabled at STA 1708, AP 1702 may allocate a portion of the remaining time to STA 1708. STA 1708 may use the allocated portion of the remaining time to transmit to AP 1702 or to another STA depending on the indicated TXS mode.

Advantages of the other example illustrated in FIG. 17 include decreased signaling overhead and latency for a STA to signal to an AP a TXS PS mode state change at the STA. As described above, the TXS PS mode state change may be carried in various frame types and is not limited to association request frames. For example, the TXS PS mode state change may be carried in a QoS data/null frame or in a short action frame. The AP may respond to the frame from the STA with a short acknowledgement frame instead of a relatively large association response frame.

In yet another example, similar to the previous embodiment, an AP may solicit the TXS PS mode state at a STA. The STA may respond to the solicitation from the AP by transmitting to the AP a frame that indicates enabling or disabling of the TXS PS mode at the STA. In an embodiment, the AP may transmit to the STA a frame soliciting the TXS PS mode state at the STA before initiating a TXS operation.

FIG. 18 is an example 1800 that illustrates such an embodiment. As shown in FIG. 18, example 1800 includes an AP 1802 and STAs 1804, 1806, and 1808. One or more of STAs 1804, 1806, and 1808 may be associated with AP 1802. STAs 1804, 1806, and/or 1808 may support the TXS PS mode as described above.

FIG. 18 illustrates an example 1800 of existing operation whereby a STA may enter a doze state during a time period of a TXOP. As shown in FIG. 18, example 1800 may begin with STA 1808 transmitting an association (or reassociation) request frame 1810 to AP 1802. In an example, association request frame 1810 may comprise a TXS PS mode field (or a TXS PS Support field). In example 1800, the TXS PS mode field (or TXS PS Support field) may be set to one (1) to indicate support of the TXS PS mode by STA 1808. The TXS PS mode field (or TXS PS Support field) may be provided in an EHT (or Ultra High Reliability (UHR)) MAC Capabilities Information field of association request frame 1810.

In an implementation, support of the TXS PS mode by STA 1808 may include STA 1808 being able to perform a TXS PS mode operation in a defined condition. In an implementation, the TXS PS mode operation may comprise STA 1808 entering a doze state during a time period of a TXOP. The defined condition may comprise STA 1808 not being allocated by AP 1802 during the time period of the TXOP. In an implementation, support of the TXS PS mode by STA 1808 may include STA 1808 being able to transmit to an AP a frame indicating enabling or disabling of the TXS PS mode as described herein. In an embodiment, the frame may include a TPS Control subfield that indicates enabling or disabling of the TXS PS mode at STA 1808. The TPS Control subfield may include a TPS Disabling subfield that carries the indication of enabling or disabling of the TXS PS mode at STA 1808. In an implementation, support of the TXS PS mode by STA 1808 may include STA 1808 being capable of entering the doze state during a TXS time period that is not allocated to STA 1808 (e.g., by an MRTT frame) when STA 1808 sets the TPS Disabling subfield to 0.

AP 1802 may respond to association request frame 1810 by transmitting an association response frame 1812 to STA 1808. In an example, association response frame 1812 may comprise a TXS PS mode field (or a TXS PS Support field). In example 1800, the TXS PS mode field (or TXS PS Support field) may be set to one (1) to indicate support of the TXS PS mode by AP 1802. The TXS PS mode field (or TXS PS Support field) may be provided in an EHT (or UHR) MAC Capabilities Information field of association response frame 1812.

In an implementation, support of the TXS PS mode by AP 1802 may include AP 1802 being able to receive from a STA a frame indicating enabling or disabling of the TXS PS mode at the STA as described herein. In an embodiment, the frame may include a TPS Control subfield that indicates enabling or disabling of the TXS PS mode at the STA. The TPS Control subfield may include a TPS Disabling subfield that carries the indication of enabling or disabling of the TXS PS mode at the STA. In an implementation, support of the TXS PS mode by AP 1802 may further include AP 1802 being able to transmit to the STA an acknowledgment of the frame indicating enabling or disabling of the TXS PS mode at the STA. In an implementation, support of the TXS PS mode by AP 1802 may further include AP 1802 being capable of not transmitting (or refraining from transmitting) any frame, during a TXS time period, to a STA that sets the TPS Disabling subfield to 0 when the TXS time period is not allocated to the STA (e.g., by an MRTT frame).

Subsequently, in an example, AP 1802 may transmit to STA 1808 a frame 1838 soliciting the TXS PS mode state at STA 1808. Frame 1838 may be a control frame, a management frame, or an action frame. In an embodiment, AP 1802 may transmit frame 1838 to STA 1808 before initiating a TXS operation. In example 1800, STA 1808 may respond to frame 1838 by transmitting to AP 1802 a frame 1834 indicating enabling of the TXS PS mode at STA 1808. Frame 1834 may be a QoS data frame, a QoS null frame, an action frame, a control frame, or a management frame. Frame 1834 may comprise an element or subfield that may be used to indicate enabling or disabling of the TXS PS mode at STA 1808.

In an example, frame 1834 may be a QoS data or a QoS null frame. The QoS data or QoS null frame may comprise an A-Control field that carries an indication of enabling or disabling the TXS PS mode at STA 1808. The A-Control field may be carried in an HT Control field of the QoS data frame or QoS null frame. In an embodiment, the A-Control field may comprise a TPS Control subfield.

In another example, frame 1834 may be an action frame. The action frame may comprise an element/field indicating enabling or disabling the TXS PS mode at STA 1808. In an example, the action frame may be an EML Operating Mode Notification frame. In an embodiment, the action frame may have a format as illustrated in FIG. 30 described above.

In an implementation, AP 1802 may acknowledge frame 1834 by transmitting an acknowledgement frame 1836 to STA 1808. Acknowledgment frame 1836 may be an ACK frame or a BA frame. In additional or alternative embodiments, STA 1808 may transmit a frame 1834 without receiving frame 1838 from AP 1802, e.g., to indicate enabling of the TXS PS mode at STA 1808. In an example, STA 1808 may enable the TXS PS mode when STA 1808 receives acknowledgment frame 1836 from AP 1802 in response to frame 1834.

Subsequently, AP 1802 may transmit a frame 1814 to allocate a portion of an obtained TXOP to STA 1804. Frame 1814 may comprise a TXOP sharing mode subfield, an AID 12 subfield, and a first time period (e.g., X us). The TXOP sharing mode subfield may indicate a triggered TXOP sharing procedure. For example, the TXOP sharing mode subfield may be set to a non-zero value (e.g., 1, 2, . . .) which indicates the triggered TXOP sharing mode 1 or the triggered TXOP sharing mode 2. The AID 12 subfield may be set to the AID of a STA that may use the first time period for transmitting and receiving one or more frame. For example, the AID 12 subfield field may be set to the AID of STA 1804. The first time period may be specified in units of microseconds or some other unit of time. In an example, frame 1814 may be an MRTT frame.

On receiving frame 1814, STA 1804 may transmit a frame 1816 to AP 1802. In an example, frame 1816 may be a CTS frame. STA 1804 may subsequently transmit a non-TB PPDU comprising a data frame 1818 to STA 1806 during the first time period. STA 1806 may transmit a BA frame 1820 to STA 1804 in response to data frame 1818.

Based on receiving frame 1814 which does not allocate STA 1808 during the first time period, and the TXS PS mode being enabled at STA 1808, STA 1808 may transition to a doze state during the first time period. In accordance with the TX PS mode, STA 1808 may transition to the doze state: after STA 1808 receives frame 1814 and before STA 1808 receives frame 1816 in response to frame 1814; after STA 1808 receives frame 1816 in response to frame 1814; or if STA 1808 does not receive a third frame during a second time period after STA 1808 receives frame 1814. The third frame may be a data frame, a control frame, or a management frame. A value of the second time period may be a fixed value or may be signaled by a fourth frame sent by AP 1802. The fourth frame may be a beacon frame, a probe response frame, or an association response frame.

In an implementation, STA 1808 may maintain the doze state during a portion of the first time period after STA 1808 transitions to the doze state. In an implementation, STA 1808 may return to an awake state at the end of the first time period or at least from the end of the first time period. In an implementation, AP 1802 may not transmit a frame to STA 1808 during the first time period. AP 1802 may transmit a frame to STA 1808 after the first time period. In an example (not shown in FIG. 18), AP 1802 may receive from STA 1804, within the first time period, a frame indicating release or return of a remaining time of the first time period. The frame may comprise a QoS Data frame or a QoS Null frame that includes an HE variant HT Control field with a CAS Control subfield with the RDG/More PPDU subfield equal to 0. Based on the TXS PS mode being enabled at STA 1808, AP 1802 may wait for an end of the remaining time before transmitting a frame to STA 1808. In an example, AP 1802 may use the remaining time to transmit a frame to STA 1804 or STA 1806 (assuming STA 1804 or STA 1806 is in the awake state) or to another STA (not shown in FIG. 18, e.g., a legacy STA that does not support TXS PS mode). In another example, AP 1802 may allocate a portion of the remaining time to STA 1806.

FIG. 19 illustrates an example 1900 of existing operation whereby a STA may enter a doze state during a TWT SP. As shown in FIG. 19, example 1900 includes an AP 1902 and a STA 1906. STA 1906 may be associated with AP 1902. In this example, STA 1906 can negotiate a specific target wake time (e.g., TWT SP 1950) with AP 1902 to wake up and be able to communicate with AP 1902, which may facilitate entry by STA 1906 into a low-power sleep mode (e.g., doze state 1930), thereby conserving battery life.

As shown in FIG. 19, example 1900 may begin during TWT SP 1950, with AP 1902 transmitting a downlink (DL) frame 1910-1 to AP 1906. In example 1900, DL frame 1910-1 may include an indication that the SP has not yet ended, e.g., end of service period (EOSP=0). STA 1906 may transmit BA frame 1920-1 to STA 1902 in response to DL frame 1910-1.

Subsequently, in example 1900, AP 1902 may transmit to STA 1906 another DL frame 1910-2 to AP 1906, and DL frame 1910-2 may include an indication that the SP has ended, e.g., EOSP=1. STA 1906 may transmit BA frame 1920-2 to STA 1902 in response to DL frame 1910-2. In this example of a TWT power saving operation, during TWT SP 1950, TWT scheduled STA 1906 may enter doze state 1930 when there is no indication of additional traffic from AP 1902, e.g., with a frame such as DL frame 1910-1 having the EOSP=1 indication discussed above, and/or an indication that more data is not forthcoming (MD=0). As depicted, in this example, doze state 1930 for STA 1906 lasts until the end of TWT SP 1950.

FIG. 20 illustrates an example 2000 that illustrates an example TXS procedure. As shown in FIG. 20, example 2000 includes AP 2010 and STAs 2011 and 2012 may be associated with AP 2010. As shown in FIG. 20, example 2000 may begin with AP 2010 transmitting an MRTT frame 2015 to allocate a portion of an obtained TXOP 2055 to STA 2011. MRTT frame 2015 specifies a TXOP sharing mode (e.g., TXS sharing mode 2 for communication between STAs 2011 and 2012), and an allocation duration of the portion of the TXOP allocated to STA 2011, e.g., shown in FIG. 20 as allocation duration 2065.

On receiving MRTT frame 2015, STA 2011 may transmit a CTS frame 2040 to AP 2010. STA 2011 may subsequently transmit one or more non-TB PPDUs to STA 2012, e.g., non-TB PPDUs 2060-1 and 2060-2. In this example, STA 2012 may transmit one or more BA frames 2020-1 and 2020-2 to STA 2011, in response to non-TB PPDUs 2060-1 and 2060-2, respectively.

In this example, for STA 2011, after receipt of BA 2020-2, STA has no additional frames to transmit to STA 2012. As depicted in FIG. 20, because STA 2011 is operating in TXS sharing mode 2, and has finished transmitting its buffered traffic during allocation duration 2065, and/or TXOP 2055, STA 2011 may return to the AP any remaining time of allocation duration 2065 allocated to STA 2011. As depicted, one approach to returning remaining allocated time is to transmit an indication to AP 2010 that the time is to be returned. In this example, the indication may be transmitted using a QoS data frame (not shown) or QoS null frame 2070.

In an implementation of the QoS null frame 2070, this frame includes an HE variant HT Control field with a CAS Control subfield, with the RDG/More PPDU subfield equal to 0 to the associated AP, e.g., AP 2010. Discussed in greater detail, the HE variant HT Control field may be a field within the MAC header of QoS null frame 2070 that includes control information specific to High Efficiency (HE) operations, and “HT” refers to High Throughput (as introduced with 802. 1 In). The HE variant HT Control field specifies that the frame structure supports HT features but is extended or variant to support HE capabilities. The HT Control field with a CAS Control subfield refers to a command and status (CAS) control subfield of the HT control field. RDG stands for “Reverse Direction Grant,” which is an operation that specifies that the recipient of the frame may respond without having to contend for the medium again. Because, in this example, RDG/More PPDU subfield is set to zero (0), this indicates that this mechanism is not in use for QoS null frame 2070, and there are no more PPDUs to be sent immediately in the reverse direction after the QoS null frame 2070 is received.

In this example, notwithstanding the indication communicated with QoS null frame 2070 and the acknowledgement frame 2030 from AP 2010, there is no provision for enabling STA 2011 to enter a doze state, e.g., as shown with doze state 1230 described with FIG. 19 above. As such, as depicted in FIG. 20, STA 2011 does not enter a low-power mode for the remainder of TXOP 2055, e.g., STA 2011 remains in awake state 2035 until the end of TXOP 2055.

In this example, because TXS assigned STA 2011 will be in awake state 2035 during the remaining TXS allocation duration 2065 or the remaining TXOP 2055, power consumption of the TXS assigned STA 2011 will be increased, e.g., especially when there is no DL/UL traffic for TXS assigned STA 2011 as depicted in FIG. 20.

Embodiments of the present disclosure, as further described below, address the abovedescribed problem of existing TXS operation. In one aspect, a STA may receive from an AP a first frame indicating a first time period of a TXOP, allocated to the STA and a sharing mode of the first time period. The STA may transmit to the AP, during the first time period, a second frame indicating a return by the STA of the first time period to the AP. After transmitting the second frame, the STA may transition from a first power state to a second power state based on the sharing mode in a power save mode. In another embodiment, after transmitting the second frame, the STA may be unavailable in an active mode, e.g., from a first power state entered based on the sharing mode. In this example context, a STA that is unavailable is not capable of receiving PPDUs. In an embodiment, the first power state corresponds to an awake state for the STA in a power save mode or an active mode, and the second power state corresponds to a doze state for the STA in a power save mode, the second power state corresponds to the STA being unavailable in an active mode, or the second power state corresponds to a listen state for the STA in a power save mode. In an embodiment, the STA may transition from the first power state to the second power state based on the sharing mode being a mode according to which the STA may communicate with a peer STA (e.g., TXS sharing mode 2). The STA may as such avoid unnecessarily and wastefully remaining in an awake state after returning the first time period to the AP.

FIG. 21 illustrates an example 2100 of one or more embodiments that may utilize a power saving operation during a TXS procedure. As shown in FIG. 21, example 2100 includes AP 2110 and STAs 2111 and 2112 associated with AP 2110. Example 2100 may begin with AP 2110 transmitting an MRTT frame 2115 to specify allocation duration 2165 of obtained TXOP 2155 to be allocated to STA 2111. In this example, MRTT frame 2115 specifies a TXOP sharing mode of 2 (e.g., for communication between STAs 2111 and 2112), and a value corresponding to allocation duration 2165.

On receiving MRTT frame 2115, STA 2111 may transmit CTS frame 2140 to AP 2110. In accordance with allocation duration 2165, STA 2111 may subsequently transmit non-TB PPDUs 2160- I and 2160-2 to STA 2112, with STA 2112 transmitting one or more BA frames 2120-1 and 2120-2 to STA 2111, in response to non-TB PPDUs 2160-1 and 2160-2, respectively. In one or more embodiments, to indicate to AP 2110 that no additional data is to be communicated by STA 2111 to STA 2112, QoS null frame 2170 may be communicated to AP 2110 by STA 2111. In response to QoS null frame 2170, AP 2110 may respond with acknowledgement frame 2135.

Continuing this example embodiment, after communication of QoS null frame 2170 to AP 2110, and receipt by STA 2111 of an acknowledgment frame 2135 from AP 2110, STA 2111 may enter a second power state (e.g., a doze state) during a remaining duration of allocation duration 2165 (depicted as doze state 2130-1 in FIG. 21) or of TXOP 2155 (depicted as doze state 2130-2 in FIG. 21). Thus, one or more embodiments may address the above-described problems may be associated with a TXS assigned STA unnecessarily and wastefully remaining in an awake state, e.g., as discussed with FIG. 20 above.

As implemented, one or more embodiments may facilitate entering one of doze states 2130-1 and 2130-2 (hereinafter collectively called “doze states 2130”) based on one or more combinations of conditions, e.g., conditions that promote improved operation of the network. For example, to facilitate use of doze states 2130 by embodiments, STA 2111 is scheduled by MRTT frame 2115 addressed to STA 2111. To further facilitate use of doze states 2130, STA 2111 indicated a retum of the remaining TXS allocation duration to AP 2110, e.g., by communicating QoS null frame 2170 to AP 2110.

In another example embodiment of a STA operating in accordance with the disclosure herein, example 2100 can begin with a STA (e.g., STA 2111) receiving from an AP (e.g., AP 2110), a first frame (e.g., MRTT frame 2115), indicating a first time period of a TXOP allocated to the STA (e.g., allocation duration 2165) and a sharing mode of the first period (e.g., TXS sharing mode 2). Continuing this example, the STA may transmit a second frame during the time period (e.g., QoS null frame 2170) indicating a return by the STA of the first time period to the AP.

In another aspect of this example, after transmitting the second frame, the STA may transition from a first power state (e.g., STA 2111 in an active state) to a second power state (e.g., STA 2111 entering one of doze states 2130), based on the sharing mode (e.g., TXS sharing mode 2). In an implementation, the first power state may correspond to an awake state for the STA in a power save mode or in an active mode, and the second power state may correspond to a doze state of the power save mode.

In an example embodiment of an AP operating in accordance with the disclosure herein, example 2100 can begin with the AP (e.g., AP 2110) transmitting to a STA (e.g., STA 2111), a first frame indicating a first time period, of a TXOP (e.g., allocation duration 2165 of TXOP 2155), allocated to the STA, and a sharing mode of the first time period (e.g., TXS sharing mode 2). Continuing this AP example, example 2100 may include receiving, by the AP from the STA and during the first time period, a second frame (e.g., QoS null frame 2170 or a QoS data frame) indicating a return by the STA of the first time period to the AP. In additional embodiments, QoS null frame 2170 (or the QoS data frame) may include an HE variant HT Control field with a CAS Control subfield with the RDG/More PPDU subfield equal to 0.

Based on the sharing mode (e.g., TXS sharing mode 2) and the second frame, the AP may receive from STA 2111, during the first time period, a third frame comprising a first indication that STA 2111 is transitioning (or has transitioned) from the first power state (e.g., STA 2111 in an active state) to a second power state (e.g., STA 2111 entering one of doze states 2130).

As discussed further with FIGS. 15-119 below, in an implementation, based on the use of doze states 2130 in accordance with one or more embodiments, AP 2110 may be limited in different combinations of operations that may be performed by AP 2110 during the time that STA 2111 is in doze state 2130. For example, in accordance with one or more embodiments, AP 2110 may be restricted from transmitting to STA 2111, any frame during the remaining duration of either allocation duration 2165 (e.g., for doze state 2130-1) or TXOP 2155 (e.g., for doze state 2130-2). Continuing the example embodiment of the AP discussed above, AP 2110 may be restricted from transmitting any frame to STA 2111 during the remaining duration of allocation duration 2165 and/or TXOP 2155. With the end of allocation duration 2165 and/or TXOP 2155, AP 2110 may not be restricted in transmission of any frames to STA 2111.

In an alternative embodiment, after communication of QoS null frame 2170 to AP 2110, and receipt by STA 2111 of acknowledgment frame 2135 from AP 2110, STA 2111 may enter the second power state corresponding to being unavailable during a remaining duration, e.g., the remaining duration of allocation duration 2165 or TXOP 2155. In this context, a STA that is unavailable is not capable of receiving PPDUs.

FIG. 22 illustrates an example 2200 of one or more embodiments that may utilize a power saving operation during a TXS procedure. As shown in FIG. 22, example 2200 includes AP 2210 and STAs 2211 and 2212 may be associated with AP 2210.

Example 2200 may begin with AP 2210 transmitting an MRTT frame 2215 to specify allocation duration 2265 of obtained TXOP 2255 to be allocated to STA 2211. In this example, MRTT frame 2215 specifies a TXOP sharing mode of 2 (e.g., for communication between STAs 2211 and 2212), a value corresponding to allocation duration 2265, and potentially, as discussed below, MRTT frame 2215 may include information corresponding to indication 2217-1 (TXS PS is allowed to be used).

On receiving MRTT frame 2215, STA 2211 may transmit CTS frame 2240 to AP 2210. In accordance with allocation duration 2265, STA 2211 may subsequently transmit non-TB PPDUs 2260- 1 and 2260-2 to STA 2212, with STA 2212 transmitting one or more BA frames 2220-1 and 2220-2 to STA 2211, in response to non-TB PPDUs 2260-1 and 2260-2, respectively. In one or more embodiments, to indicate to AP 2210 that no additional data is to be communicated by STA 2211 to STA 2212, QoS null frame 2270 may be communicated to AP 2210 by STA 2211.

In additional or alternative embodiments, at different points in the sequence of communications between AP 2210 and STA 2211, AP 2210 may analyze different factors associated with whether STA 2211 should be permitted to enter the doze state. Example factors that may be evaluated as favoring permitting STA 2211 to enter the doze state include, but are not limited to, AP 2210 does not have buffered traffic for STA 2211; AP 2210 has non-low latency buffered traffic for STA 2211 and AP 2210 has low-latency buffered traffic for another STA associated with AP 2210; and/or AP 2210 has buffered traffic for STA 2211, but AP 2210 has more urgent traffic than the buffered traffic for another STA associated with AP 2210.

In some implementations, an approach to communicating the determination may utilize a frame communicated from AP 2210 to STA 2211, e.g., one or more of a trigger frame, an immediate response frame (e.g., an Ack frame or BlockAck (BA) frame), a control frame, a management frame, an action frame, a QoS data frame, and/or a QoS null frame. Examples that use MRTT frame 2215 and an immediate response frame (e.g., acknowledgement frame 2235) are described below. In one or more embodiments, when a trigger frame is utilized by embodiments described herein, the trigger frame can be an MRTT Trigger frame.

One example point in the sequence of communications between AP 2210 and STA 2211 includes a point before MRTT frame 2215 is communicated from AP 2210 to STA 2211. In this example, when a determination is made by AP 2210 to allow use of a TXS power saving operation by STA 2211, indication 2217-1 (TXS PS allowed) to STA 2211 may be included with MRTT frame 2215, and this indication may permit STA 2211 to enter a doze state (e.g., doze state 2230-1 or doze state 2230- 2) in accordance with embodiments described herein. Alternatively, when indication 2217-1 corresponds to a determination not to allow use of a doze state by STA 2211, this indication, included with MRTT frame 2215, may instruct STA 2211 to not enter a doze state (e.g., doze 2230-1 or doze state 2230-2) in accordance with embodiments described herein.

An alternative example point in the sequence of communications between AP 2210 and STA 2211 includes a point after QoS null frame 2270 is received by AP 2210 and before acknowledgement frame 2235 is communicated by AP 2210 to STA 2211 in response to QoS null frame 2270. In this example, additional information may be collected and analyzed by AP 2210 to determine whether to allow the use of the doze state 2230. As depicted, when the use of the power saving operations discussed herein is allowed, indication 2217-2 (TXS PS allowed) may be included with acknowledgement frame 2235, and the subsequent operation of STA 2211 is controlled in accordance with the indication.

One approach to including indication 2217-2 in acknowledgement frame 2235 (or a BA, not shown) may utilize the More data (MD) subfield of an Ack or BA frame. When this currently existing subfield is set to zero (0), this may be used to indicate to STA 2211 that no more data is to be provided by AP 2210 to STA 2211, and thus the use of doze state 2230 is permitted. Conversely, in accordance with one or more embodiments, the MD subfield of acknowledgement frame 2235 may be set to one (1) to indicate to STA 2211 that more data is to be provided by AP 2210 to STA 2211, and thus the doze state 2230 is not permitted to be utilized.

Another approach to communicating information associated with the use of a TXS SP procedure to STA 2211 may utilize the Buffered Traffic Indication subfield of an immediate response frame, a control frame, a management frame, an action frame, and/or a QoS null/data frame. Yet another approach to communicating information associated with the use of a TXS SP procedure to STA 2211 may utilize the SIG field (e.g., U-SIG, UHR-SIG, etc.) of preamble of the PPDU carrying the field. These additional approaches are discussed in greater detail with FIG. 27 below.

FIG. 23 illustrates an example 2300 that utilizes a power saving operation during a TXS procedure in accordance with one or more embodiments. As shown in FIG. 23, example 2300 includes AP 2310 and STAs 2311 and 2312 may be associated with AP 2310. Example 2300 may begin with AP 2310 transmitting an MRTT frame 2315 to specify allocation duration 2365 of obtained TXOP 2355 to be allocated to STA 2311. In this example, MRTT frame 2315 specifies a TXOP sharing mode of 2 (e.g., for communication between STAs 2311 and 2312), and a value corresponding to allocation duration 2365.

On receiving MRTT frame 2315, STA 2311 may transmit CTS frame 2340 to AP 2310. In accordance with allocation duration 2365, STA 2311 may subsequently transmit non-TB PPDUs 2360- 1 and 2360-2 to STA 2312, with STA 2312 transmitting one or more BA frames 2320-1 and 2320-2 to STA 2311, in response to non-TB PPDUs 2360-1 and 2360-2, respectively. In one or more embodiments, to indicate to AP 2310 that no additional data is to be communicated by STA 2311 to STA 2312, QoS null frame 2370 may be communicated to AP 2310 by STA 2311.

As noted above with FIG. 21, one or more embodiments may restrict operations of AP

2310 when STA 2311 is utilizing TXS power saving operations. To implement these restrictions, in additional or alternative embodiments depicted in FIG. 23, QoS null frame 2370 may be used by STA

2311 to further indicate to AP 2310 whether STA 2311 is entering a second power state (e.g., doze state 2330-1 or 2330-2 or an unavailable state) from a first power state (e.g., an awake state), during a remaining duration (e.g., of allocation duration 2365 or TXOP 2355). As depicted in FIG. 23, an indication 2371 (TXS PS notification) may be communicated to AP 2310 with QoS null frame 2370, and based on indication 2371, AP 2310 may determine not to transmit to STA 2311 any frame during the remaining duration of allocation duration 2365 or TXOP 2355.

Continuing this example, in response to QoS null frame 2370, AP 2310 may respond with acknowledgement frame 2335. After communication of QoS null frame 2370 to AP 2310, receipt of indication 2371 by AP 2310, and receipt by STA 2311 of acknowledgement frame 2335 from AP 2310, AP 2310 may restrict communication to STA 2311, and STA 2311 may enter a second power state (e.g., doze states 2330-1 or 2330-2 or an unavailable state) during a remaining duration (e.g., of allocation duration 2365 or TXOP 2355).

FIG. 24 illustrates an example 2400 of one or more embodiments that may utilize a power saving operation during a TXS procedure. As shown in FIG. 24, example 2400 includes AP 2410 and STAs 2411 and 2412 associated with AP 2410.

Example 2400 may begin with AP 2410 transmitting an MRTT frame 2415 to specify allocation duration 2465 of obtained TXOP 2455 to be allocated to STA 2411. In this example, MRTT frame 2415 specifies a TXOP sharing mode of 2 (e.g., for communication between STAs 2411 and 2412), a value corresponding to allocation duration 2465, and potentially, as discussed below, MRTT frame 2415 may include information corresponding to indication 2417 (TXS PS is allowed to be used).

On receiving MRTT frame 2415, STA 2411 may transmit CTS frame 2440 to AP 2410. In accordance with allocation duration 2465, STA 2411 may subsequently transmit non-TB PPDUs 2460- 1 and 2460-2 to STA 2412, with STA 2412 transmitting one or more BA frames 2420-1 and 2420-2 to STA 2411, in response to non-TB PPDUs 2460-1 and 2460-2, respectively. In one or more embodiments, to indicate to AP 2410 that no additional data is to be communicated by STA 2411 to STA 2412, QoS null frame 2470 may be communicated to AP 2410 by STA 2411.

As discussed above with FIG. 24, in one or more embodiments, AP 2410 may analyze different factors associated with whether STA 2411 should be permitted to enter doze state 2430. Example factors that may be evaluated as favoring permitting STA 2411 to enter doze state 2430 include, but are not limited to, that AP 2410 does not have buffered traffic for STA 2411, that AP 2410 has nonlow latency buffered traffic for STA 2411, and that AP 2410 has low-latency buffered traffic for another STA associated with AP 2410, and/or that AP 2410 has buffered traffic for STA 2411, but AP 2410 has more urgent traffic than the buffered traffic for another STA associated with AP 2410.

In additional or alternative embodiments, at the time that QoS null frame 2470 is utilized by STA 2411 to indicate to AP 2410 that no additional data is to be communicated by STA 2411 to STA 2412, STA 2411 can utilize an indication 2471 to request to be allowed to utilize TXS power saving operation. At that time, based at least on the example factors described above, AP 2410 can determine whether to permit usage of TXS power saving operation by STA 2411 in response to indication 2471 (TXS PS request) included with QoS null frame 2470.

With respect to communicating determination information corresponding to indication 2417 to STA 2411, one or more embodiments can utilize approaches described with FIG. 22 above, e.g., an approach to communicating the determination may utilize a frame communicated from AP 2410 to STA 1511, including one or more of a trigger frame, an immediate response frame (e.g., an Ack frame or BlockAck (BA) frame), a control frame, a management frame, an action frame, a QoS data frame, and/or a QoS null frame. Examples that use an immediate response frame (e.g., acknowledgement frame 2435) are described with FIG. 22 above, and FIG. 30 below. The immediate response frame (e.g., acknowledgement frame 2435) may comprise indication 2417. In an embodiment, indication 2417 may be comprised in a separate frame with acknowledgement frame 2435. In an additional or alternative embodiment, indication 2471 may be comprised in a separate frame with QoS null frame 2470.

FIG. 25 illustrates an example 2500 of one or more embodiments that may utilize a power saving operation during a TXS procedure. As shown in FIG. 25, example 2500 includes AP 2510 and STAs 2511 and 2512 associated with AP 2510.

In one or more embodiments, a STA (or AP) may negotiate, with an AP (or STA), a capability to support different TXS power saving operations described with embodiments herein, e.g., STA 2511 may or may not have a capability of utilizing TXS power saving operations.

To illustrate this exchange of capability information between AP 2510 and STA 2511, example 2500 begins with STA 2511 transmitting an association (or reassociation) request frame 2525 to AP 2510. Based on association request frame 2525, AP 2510 may respond with an association response frame 2527. In one or more embodiments, the existing capability fields of association request frame 2525 and association response frame 2527 may be used to exchange capability information associated with TXS power saving operations. For example, utilized capability fields may be included in one or more capabilities elements (e.g., HE capabilities element, EHT MAC capabilities element, UHR MAC capabilities element, etc.), in one or more management frames (e.g., beacon frame, probe request frame, probe response frame, association request frame, association response frame, etc.).

Alternative frames that can be utilized to provide the capabilities of STA 2511 include, but are not limited to, a probe request frame, an association request frame, a control frame, a management frame, an action frame, a QoS data frame, and/or a QoS null frame.

Alternative frames that can be utilized to provide capabilities of AP 2510 include, but are not limited to, a probe response frame, an association response frame, a broadcast addressed frame, a control frame, a management frame, an action frame, a QoS data frame, and/or a QoS null frame. In one or more embodiments, the broadcast addressed frame may be a beacon frame, a probe response frame, and/or a fast initial link setup (FILS) discovery frame.

Example 2500 continues with AP 2510 transmitting an MRTT frame 2515 to specify allocation duration 2565 of obtained TXOP 2555 to be allocated to STA 2511. In this example, MRTT frame 2515 specifies a TXOP sharing mode of 2 (e.g., for communication between STAs 2511 and 2512), and a value corresponding to allocation duration 2565.

On receiving MRTT frame 2515, STA 2511 may transmit CTS frame 2540 to AP 2510. In accordance with allocation duration 2565, STA 2511 may subsequently transmit non-TB PPDUs 2560 to STA 2512, and STA 2512 may respond by transmitting BA frame 2520 to STA 2511. In one or more embodiments, to indicate to AP 2510 that no additional data is to be communicated by STA 2511 to STA 2512, QoS null frame 2570 may be communicated to AP 2510 by STA 2511. In response to QoS null frame 2570, AP 2510 may respond with acknowledgement frame 2535.

Continuing this example embodiment, after communication of QoS null frame 2570 to AP 2510, and receipt by STA 2511 of acknowledgement frame 2535 from AP 2510, when STA 2511 is determined to have capabilities that support the TXS power saving operation, STA 2511 may enter the doze state during the remaining duration, and the AP 2510 should not transmit to the STA 2511 any frame during the remaining duration. Conversely, when the STA 2511 is not determined to have sufficient capabilities to support TXS power saving operations, STA 2511 may not enter doze state 2530, and AP 2510 may transmit a frame to STA 2511, during the remaining duration.

FIG. 26 illustrates an example 2600 of one or more embodiments that may utilize a power saving operation during a TXS procedure. As shown in FIG. 26, example 2600 includes AP 2610 and STAs 2611 and 2612 may be associated with AP 2610.

Example 2600 may begin with STA 2611 transmitting association request 2625 to AP 2610. Based on association request 2625, AP 2610 may respond with association response 2625. In one or more embodiments, to facilitate the use of TXS power saving operations by STA 2611, after receipt of association response 2627 by STA 2611, STA 2611 may transmit to the AP 2610, enabling frame 2680 that may include an indication of whether STA 2611 enables (activates) or disables (deactivates) the TXS power saving operation for the current communication session. For TXS power saving operations described herein, STA 2611 may enter doze state 2630 during a remaining TXS allocation duration 2665 (TXOP 2655) based on STA 2611 transmitting enabling frame 2680. Without enablement of TXS power saving operations by enabling frame 2680, STA 2611 may not enter the doze state during the remaining duration.

In TXS power saving operations described with embodiments herein, AP 2610 may transmit a frame to STA 2611 during the remaining time only when AP 2610 receives an indication via enabling frame 2680, that the TXS power saving operation is disabled. Otherwise, when enabling frame 2680 indicates that TXS power saving operations are to be enabled, AP 2610 may not transmit any frame to STA 2611 during the remaining time.

In an additional example, when AP 2610 receives enabling frame 2680, AP 2610 may transmit a response frame (e.g., response management (/action) frame or immediate response frame (e.g., Ack or BA)), e.g., acknowledgement frame 2635-1 depicted in FIG. 26.

Example 2600 continues with AP 2610 transmitting an MRTT frame 2615 to specify allocation duration 2665 of obtained TXOP 2655, to be allocated to STA 2611. In this example, MRTT frame 2615 specifies a TXOP sharing mode of 2 (example, for communication between STAs 2611 and 2612), and a value corresponding to allocation duration 2665. On receiving MRTT frame 2615, STA 2611 may transmit CTS frame 2640 to AP 2610. In accordance with allocation duration 2665, STA 2611 may subsequently transmit non-TB PPDU 2660 to STA 2612, and STA 2612 may respond by transmitting BA frame 2620 to STA 2611. In one or more embodiments, to indicate to AP 2610 that no additional data is to be communicated by STA 2611 to STA 2612, QoS null frame 2670 may be communicated to AP 2610 by STA 2611. In response to QoS null frame 2670, AP 2610 may respond with acknowledgement frame 2635.

Continuing this example embodiment, after communication of QoS null frame 2670 to AP 2610, and receipt by STA 2611 of acknowledgement frame 2635-2 from AP 2610, based on enabling frame 2680 indicating an enablement of TXS power saving operations, STA 2611 may enter a second power state (e.g., doze state 2630-1 or 2630-2) during a remaining duration (e.g., of allocation duration 2665 or TXOP 2655).

FIG. 27 illustrates an example 2700 of one or more embodiments that may utilize a power saving operation during a TXS procedure. As shown in FIG. 27, example 2700 includes AP 2710 and STAs 2711 and 2712 associated with AP 2710.

Example 2700 may begin with AP 2710 transmitting an MRTT frame 2715 to specify allocation duration 2765 of obtained TXOP 2755 to be allocated to STA 2711. In this example, MRTT frame 2715 specifies a TXOP sharing mode of 2 (e.g., for communication between STAs 2711 and 2712), a value corresponding to allocation duration 2765, and potentially, as discussed below, MRTT frame 2715 may include information corresponding to indication 2717 (a TXS power saving operation is allowed to be used).

On receiving MRTT frame 2715, STA 2711 may transmit CTS frame 2740 to AP 2710. In accordance with allocation duration 2765, STA 2711 may subsequently transmit non-TB PPDUs 2760- I and 2760-2 to STA 2712, with STA 2712 transmitting one or more BA frames 2720-1 and 2720-2 to STA 2711, in response to non-TB PPDUs 2760-1 and 2760-2, respectively. In one or more embodiments, to indicate to AP 2710 that no additional data is to be communicated by STA 2711 to STA 2712, QoS null frame 2770 may be communicated to AP 2710 by STA 2711.

As discussed above with FIG. 27, in one or more embodiments, AP 2710 may analyze different factors associated with whether STA 2711 should be permitted to enter doze state 2730. Example factors that may be evaluated as favoring permitting STA 2711 to enter doze state 2730 include, but are not limited to, that AP 2710 does not have buffered traffic for STA 2711, that AP 2710 has nonlow latency buffered traffic for STA 2711, and that AP 2710 has low-latency buffered traffic for another STA associated with AP 2710, and/or that AP 2710 has buffered traffic for STA 2711, but AP 2710 has more urgent traffic than the buffered traffic for another STA associated with AP 2710.

In additional or alternative embodiments, at the time that QoS null frame 2770 is utilized by STA 2711 to indicate to AP 2710 that no additional data is to be communicated by STA 2711 to STA 2712, STA 2711 can utilize an indication 2771 to request to be allowed to utilize TXS power saving operations. At that time, based at least on the example factors described above, AP 2710 can determine whether to permit usage of TXS power saving operation by STA 2711 in response to indication 2771 (TXS PS request) included with QoS null frame 2770.

With respect to communicating determination information corresponding to indication 2717 to STA 2711, one or more embodiments can utilize approaches described with FIG. 15 above, e.g., an approach to communicating the determination may utilize a frame communicated from AP 2710 to STA 1511, including one or more of a trigger frame, an immediate response frame (e.g., an Ack frame or BlockAck (BA) frame), a control frame, a management frame, an action frame, a QoS data frame, and/or a QoS null frame. Examples that use an immediate response frame (e.g., acknowledgement frame 2735) are described with FIG. 15 above, and FIG. 21 below. In an embodiment, indication 2717 may be comprised in a separate frame with acknowledgement frame 2735. In an additional or alternative embodiment, indication 2717 may be comprised in a separate frame with QoS null frame 2770.

In an embodiment, after STA 2711 receives an indication that TXS power saving operations are allowed, STA 2711 may transmit a confirmation indication to AP 2710. For example, as depicted, after receiving indication 2717 with acknowledgement frame 2735, STA 2711 transmits confirmation indication 2775 to AP 2710 to confirm receipt of the indication. In an example, confirmation indication may be a QoS Data frame, a QoS Null frame, or other frame that communicates similar information.

FIG. 28 describes different signaling capabilities for one or more embodiments. In one or more embodiments, a TXS power save mode 2 Support subfield 2815 in an UHR MAC Capabilities element 2810 can be utilized using approaches described below. In an example where the STA supports the TXS power save mode 2, the STA may enter the doze state during a remaining duration within an TXS allocation duration or the current TXOP when one or more of the following conditions are met: when the STA transmits a first frame to return a remaining duration within an allocated duration, when the STA receives a response frame in response to the first frame, when the STA activates (/enables) TXS power saving operation, when the STA transmits a second frame indicating that the STA enters the second power state (doze state) during the remaining duration, when the STA receives a third frame indicating that the STA is allowed to be in doze state (the second power state), and when the STA receives the third frame in response to the second frame. For example, for a non-AP STA, the UHR MAC Capabilities element 2810 may be carried in an association request frame or a probe request frame, and the TXS power save mode 2 Support subfield being set to one (1) indicates that the non-AP STA supports the TXS power save mode 2.

For an AP, the UHR MAC Capabilities element 2810 may be carried in a beacon frame, an association response frame, or a probe response frame. The TXS power save mode 2 Support subfield 2815 being set to one (1) indicates that the AP supports TXS power save mode 2. In that case, the AP should not transmit any frame to a STA that is allowed to enter the doze state during a remaining duration within an TXS allocation duration or the current TXOP when one or more of the following conditions is met: when the AP receives a first frame to return a remaining duration within an allocated duration, when the AP transmits a response frame in response to the first frame, when the AP receives, from the STA, a frame to activate/enable TXS power saving operation, when the AP receives, from the STA, a second frame indicating that the STA enters the second power state (doze state) during the remaining duration, when the AP transmits a third frame indicating that the STA is allowed to be in doze state (the second power state), and when the AP transmits the third frame in response to the second frame.

In one or more embodiments, signaling values that correspond to the enabling and disabling of TXS power saving operations may be performed using different approaches. One option may use A-Control field (e.g., an EHT OM Control subfield 2820). Another option may use an action frame 2830 (e.g., an EML Operating Mode Notification (OMN) frame). In an embodiment, action frame 2830 may comprise an EHT TPS Control element and EHT TPS Control element may comprise TXS power save mode 2 Enabling subfield 2825-2.

In one or more embodiments, signaling values that correspond to TXS power saving entry may be performed by utilizing a TXS power saving entry subfield. For example, a STA may indicate whether the STA transitions (/enters) a second power state (e.g., a doze state) or an unavailable state during the remaining duration (TXS allocation duration or TXOP). The TXS power saving entry subfield may be included in a QoS null/data frame (e.g., CAS control field or new A-Control field) or a control, management, action frame or in the SIG field (e.g., U-SIG, UHR-SIG, etc.) of a preamble of the PPDU carrying the field. In some implementations, when the TXS power saving entry subfield may be set to one (1), and this may indicate that the STA transitions (/enters) a second power state (e.g., doze state) during the remaining duration in a power save mode. Additionally or alternatively, the TXS power saving entry subfield may be set to one (1) when the STA will be unavailable during the remaining duration (allocation or TXOP) in an active mode. In an embodiment, setting the TXS power saving entry subfield to one (1), may occur when one or more of the following conditions is met: if the STA transmitted a first frame comprising the TXS power saving entry subfield set to one (1), if the STA receives a second frame (e.g., immediate response frame (Ack or BA), response management frame, a control frame, a management frame, or an action frame). As used herein,

In some implementations, if the STA receives a second frame (e.g., an immediate response frame (Ack or BA) or response management frame) in response to the first frame comprising the TXS power saving entry subfield, then the second frame indicates that the STA is allowed to be in a second power state (e.g., a doze state in the TXS power save mode (e.g., TXS power save mode 2) during the remaining duration or that the STA is allowed to be unavailable in an active mode during the remaining duration. It should be noted that for one or more approaches to utilizing TXS power saving operations described herein, the STA and/or the AP supports TXS power save mode 2 and/or the STA activates/enables the TXS power save mode 2.

In one or more embodiments, a TXS power saving allowance subfield may be used by an AP to indicate whether a non-AP STA is allowed to enter a second power state (e.g., doze state) in a power save mode (e.g., TXS power save mode 2) during the remaining duration or whether the non-AP STA is allowed to be unavailable in an active mode during the remaining duration (allocation or TXOP). The TXS power saving allowance subfield field may be included in an immediate response frame (e.g., Ack frame or BlockAck (BA) frame), a control frame, a management frame, an action frame, or a QoS null/data frame, or in the SIG field (e.g., U-SIG, UHR-SIG, etc.) of preamble of the PPDU carrying the field. If the STA receives a frame carrying the TXS power saving allowance subfield set to one (1), the non-AP STA may transition(or enter) a second power state (e.g., doze state) in a power save mode (e.g., TXS power save mode 2) during the remaining duration or the non-AP STA may be unavailable in an active mode during a remaining duration (e.g., allocation duration or TXOP), when one or more of the following conditions is met: the STA transmitted a first frame comprising the TXS power saving entry subfield set to one (1) (e.g., before the STA receives the TXS power saving allowance subfield), the STA received a second frame (e.g., immediate response frame (Ack or BA) or a management frame, or a control frame, QoS null/data frame, or an action frame), the STA receives a second frame (e.g., immediate response frame (Ack or BA) or response management frame) in response to the first frame comprising the TXS power saving entry subfield, and the second frame indicates that the STA is allowed to be in a second power state (e.g., doze state) in a power save mode (e.g., TXS power save mode 2) during the remaining duration or that the STA is allowed to be unavailable in an active mode during the remaining duration. The TXS power saving allowance subfield may be set to one (1) when one or more of the following conditions are met: when the AP does not have buffered traffic to be sent to the STA, when the AP has non-low latency traffic for the STA, and when the AP has non-low latency buffered traffic for the STA but the AP has low latency traffic for another STA.

In one or more embodiments, a Buffered Traffic Indication subfield may be used by an AP to indicate whether the AP has buffered traffic (or low latency traffic) to be sent to a STA. In some implementations, the Buffered Traffic Indication subfield field may be included in an immediate response frame (e.g., Ack frame or BlockAck (BA) frame), a control frame, a management frame, an action frame, a QoS null/data frame, and in the SIG field (e.g., U-SIG, UHR-SIG, etc.) of preamble of the PPDU carrying the field. In some implementations, the Buffered Traffic Indication subfield is set to one (1) to indicate that the AP has buffered traffic (or low latency buffered traffic) to be sent to the STA. Otherwise it is set to zero (0).

In some implementations, when the STA receives a frame carrying the subfield set to one (1), the non-AP STA may transition(or enter) a second power state (e.g., doze state) or an unavailable state during a remaining duration (e.g., allocation duration or TXOP), when one or more of the following conditions is met: the STA transmitted a first frame comprising the TXS power saving entry subfield set to one (1) (e.g., before the STA receives the Buffered Traffic Indication subfield), the STA received a second frame (e.g., immediate response frame (Ack or BA) or a management frame, or a control frame, QoS null/data frame, or an action frame), the STA receives a second frame (e.g., immediate response frame (Ack or BA) or response management frame) in response to the first frame comprising the TXS power saving entry subfield, when the second frame indicates that the STA is allowed to be in a second power state (e.g., doze state) in a power save mode (e.g., TXS power save mode 2) during the remaining duration or that the STA is allowed to be unavailable in an active mode during the remaining duration, when the STA and/or the AP supports TXS power save mode 2, and the STA activates/enables the TXS power save mode 2.

FIG. 29 illustrates an example process 2900 according to an embodiment. Example process 2900 may be performed by an AP, such as AP 1410, AP 1510, AP 1610, AP 1710, AP 2510, 2620, or AP 2710 described above. As shown in FIG. 29, process 2900 may include steps 2902 and 2904.

Step 2902 includes transmitting, by the access point (AP) to a station (STA), a first frame indicating a time period, of a transmit opportunity (TXOP), allocated to the STA. The STA may be associated with the AP. The first frame may comprise a trigger frame. The trigger frame may comprise an MRTT frame.

Step 2904 includes receiving, by the AP from the STA and during the time period, a second frame indicating a return by the STA of the time period to the AP. In an embodiment, the second frame comprises a QoS data frame, a QoS null frame, an action frame, a control frame, or a management frame.

In an embodiment, process 2900 may further comprise, receiving, by the AP from the STA and during the first time period, a third frame comprising a first indication of transitioning from the first power state to the second power state. In an embodiment, the second frame comprises the first indication. In an embodiment, the second frame or the third frame is a control frame, a management frame, an action frame, a QoS data frame or a QoS null frame. In an embodiment, process 2900 may further comprise, transmitting, by the AP to the STA and during the first time period, a fourth frame comprising a second indication whether the STA is allowed to be in the second power state. In an embodiment, the AP transmits, to the STA, the fourth frame in response to the second frame.

In an embodiment, the AP transmits, to the STA, the fourth frame in response to the second frame comprising the first indication. In an embodiment, the AP transmits, to the STA, the fourth frame in response to the third frame. In an embodiment, the fourth frame is a Trigger frame, an immediate response frame, a control frame, a management frame, an action frame, a QoS data frame or a QoS null frame. In an embodiment, the trigger frame comprises an MU-RTS TXS Trigger frame or an MU-RTS Trigger frame. In an embodiment, the immediate response frame comprises an acknowledgement (Ack) frame or a BlockAck (BA) frame. In an embodiment, the Ack frame or the BA frame comprises a more data (MD) subfield set to 0 to indicate that the STA is allowed to be in the second power state. In an embodiment, the Ack frame or the BA frame comprises a more data (MD) subfield set to 1 to indicate that the STA is not allowed to be in the second power state. In an embodiment, the second indication that the STA is allowed to be in the second power state comprises that the AP does not have buffered traffic for the STA.

In an embodiment, the second indication that the STA is allowed to be in the second power state comprises that the AP has a non-low latency buffered traffic for the STA and the AP has a low latency buffered traffic for another STA. In an embodiment, the second indication that the STA is allowed to be in the second power state comprises that the AP has buffered traffic for the STA, but the AP has more urgent traffic for other STA. In an embodiment, process 2900 may further comprise, transmitting, by the AP to the STA and during the first time period, the fourth frame comprising a third indication whether the AP has buffered traffic for the STA. In an embodiment, process 2900 may further comprise, transmitting, by the AP to the STA and during the first time period, the fourth frame comprising a third indication whether the AP has a low latency buffered traffic for the STA. In an embodiment, process 2900 may further comprise, receiving, by the AP from the STA and before the first time period, a fifth frame comprising a first capability whether the STA supports the TXS power saving operation, and after receiving the fifth frame, transmitting, by the AP to the STA, a sixth frame comprising a second capability whether the AP supports TXS power saving operation.

In an embodiment, the fifth frame is a probe request frame, an association request frame, a control frame, a management frame, an action frame, a QoS data frame or a QoS null frame. In an embodiment, the sixth frame is a probe response frame, an association response frame, a control frame, a management frame, an action frame, a QoS data frame or a QoS null frame. In an embodiment, a broadcast addressed frame further comprises the second capability. In an embodiment, the broadcast addressed frame is a beacon frame or a probe response frame, or a fast initial link setup (FILS) discovery frame.

FIG. 30 illustrates another example process 3000 according to an embodiment. Example process 3000 may be performed by a first STA, such as STA 1411, STA 1511, STA 1611, STA 1711, STA 2511, 2611, or 2711, described above. As shown in FIG. 30, process 3000 may include steps 3002, 3004, and 3006.

Step 3002 includes receiving, by a station (STA) from an access point (AP), a first frame indicating a time period, of a transmit opportunity (TXOP), allocated to the STA. The first STA may be associated with the AP. The first frame may comprise a trigger frame. The trigger frame may comprise an MRTT frame. Step 3004 includes transmitting, by the STA to the AP and during the time period, a second frame indicating a return by the STA of the time period to the AP. In an embodiment, the second frame comprises a QoS data frame, a QoS null frame, an action frame, a control frame, or a management frame. Step 3006 includes, after transmitting the second frame, transitioning, by the STA, from a first power state (awake) to a second power state (doze).

In an embodiment, the second frame comprises the first indication. In an embodiment, the second frame or the third frame is a control frame, a management frame, an action frame, a QoS data frame or a QoS null frame. In an embodiment, process 3000 may further comprise, receiving, by the STA from the AP and during the first time period, a fourth frame comprising a second indication whether the STA is allowed to be in the second power state, and based on the second indication that the STA is allowed to be in the second power state, transitioning, by the STA, from the first power state to the second power state. In an embodiment, the STA receives, from the AP, the fourth frame in response to the second frame. In an embodiment, the STA receives, from the AP, the fourth frame in response to the second frame comprising the first indication. In an embodiment, the STA receives, from the AP, the fourth frame in response to the third frame. In an embodiment, the fourth frame is a Trigger frame, an immediate response frame, a control frame, a management frame, an action frame, a QoS data frame or a QoS null frame. In an embodiment, the trigger frame comprises an MU-RTS TXS Trigger frame. In an embodiment, the immediate response frame comprises an acknowledgement (Ack) frame or a BlockAck (BA) frame. In an embodiment, the Ack frame or the BA frame comprises a more data (MD) subfield set to 0 to indicate that the STA is allowed to be in the second power state. In an embodiment, the Ack frame or the BA frame comprises a more data (MD) subfield set to 1 to indicate that the STA is not allowed to be in the second power state. In an embodiment, the second indication that the STA is allowed to be in the second power state comprises that the AP does not have buffered traffic for the STA.

In an embodiment, the second indication that the STA is allowed to be in the second power state comprises that the AP has a non-low latency buffered traffic for the STA and the AP has a low latency buffered traffic for another STA. In an embodiment, the second indication that the STA is allowed to be in the second power state comprises that the AP has buffered traffic for the STA, but the AP has more urgent traffic for other STA. In an embodiment, process 3000 may further comprise, receiving, by the STA from the AP and during the first time period, the fourth frame comprising a third indication whether the AP has buffered traffic for the STA, and based on the third indication that the AP does not have buffered traffic for the STA, transitioning, by the STA, from the first power state to the second power state.

In an embodiment, process 3000 may further comprise, receiving, by the STA from the AP and during the first time period, the fourth frame comprising a third indication whether the AP has a low latency buffered traffic for the STA, and based on the third indication that the AP does not have the low latency buffered traffic for the STA, transitioning, by the STA, from the first power state to the second power state. In an embodiment, process 3000 may further comprise, transmitting, by the STA to the AP and before the first time period, a fifth frame comprising a first capability whether the STA supports the TXS power saving operation, after transmitting the fifth frame, receiving, by the STA from the AP, a sixth frame comprising a second capability whether the AP supports TXS power saving operation, and based on the first capability and the second capability supporting the TXS power saving operation, transitioning, by the STA, from the first power state to the second power state.

In an implementation, a second power state may be referred to as a lower power receive state or a listen/listening state. While in the second power state, the STA is capable of receiving PPDUs of a first category. In an implementation, the STA is capable of receiving PPDUs of only the first category during the second power state.

In an implementation, the first category may include PPDUs having a non-HT PPDU format. In another implementation, the first category may include, additionally or alternatively, PPDUs having a data rate that is less than or equal to 24 Mbps, a bandwidth of 27 MHz, and/or a single spatial stream.

FIG. 31 illustrates an example 3100 of one or more embodiments that may utilize a power saving operation during a TXS procedure. As shown in FIG. 31, example 3100 includes AP 3110 and STAs 3111 and 3112 associated with AP 3110.

Example 3100 may begin with AP 3110 transmitting an MRTT frame 3115 to specify allocation duration 3165 of obtained TXOP 3155 to be allocated to STA 3111. In this example, MRTT frame 3115 specifies a TXOP sharing mode of 2 (e.g., for communication between STAs 3111 and 3112), a value corresponding to allocation duration 3165, and potentially, as discussed below, MRTT frame 3115 may include information corresponding to indication 3117 (TXS PS is allowed to be used). The indication 3117 may indicate whether TXS PS is allowed to be used by the STA 3111. The indication 3117 may indicate whether the AP has the buffered traffic for the STA 3111. The indication 3117 may indicate whether the AP has low latency/latency sensitive/urgent buffered traffic for the STA 3111. The indication 3117 may indicate whether the AP will schedule the DE transmission for the STA 3111 faster than other STAs during TXOP 3155 or allocation duration 3165. For example, the indication 3117 may indicate that the AP will schedule the DL transmission for the STA 3111 faster than other STAs during TXOP 3155 or allocation duration 3165 when the AP has low latency/latency sensitive/urgent buffered traffic for the STA 3111. In that case, AP will transmit DL PPDU for the STA 3111 faster than other STAs during TXOP 3155 or allocation duration 3165 and STA 3111 will be in awake state after transmitting QoS null frame 3170 and then receiving an immediate response frame (e.g., acknowledgement frame 3135) in response to QoS null frame 3170. For example, the indication 3117 may indicate that the AP will not schedule the DL transmission for the STA 3111 faster than other STAs during TXOP 3155 or allocation duration 3165 when the AP does not have low latency/latency sensitive/urgent buffered traffic for the STA 3111. If the indication 3117 indicates that the will not schedule the DL transmission for the STA 3111 faster than other STAs during TXOP 3155 or allocation duration 3165, AP may transmit DL PPDU for other STAs faster than STA 3111 during TXOP 3155 or allocation duration 3165 and STA 3111 will transition to the second power state (Listen State) after transmitting QoS null frame 3170 and then receiving an immediate response frame (e.g., acknowledgement frame 3135) in response to QoS null frame 3170. On receiving MRTT frame 3115, STA 3111 may transmit CTS frame 3140 to AP 3110.

In accordance with allocation duration 3165, STA 3111 may subsequently transmit non-TB PPDUs 3160- 1 and 3160-2 to STA 3112, with STA 3112 transmitting one or more BA frames 3120-1 and 3120-2 to STA 3111, in response to non-TB PPDUs 3160-1 and 3160-2, respectively. In one or more embodiments, to indicate to AP 3110 that no additional data is to be communicated by STA 3111 to STA 3112, QoS null frame 3170 may be communicated to AP 3110 by STA 3111.

As discussed above with FIG. 31, in one or more embodiments, AP 3110 may analyze different factors associated with whether STA 3111 should be permitted to enter listen state 3130. Example factors that may be evaluated as favoring permitting STA 3111 to enter listen state 3130 include, but are not limited to, that AP 3110 does not have buffered traffic for STA 3111, that AP 3110 has nonlow latency buffered traffic for STA 3111, and that AP 3110 has low-latency buffered traffic for another STA associated with AP 3110, and/or that AP 3110 has buffered traffic for STA 3111, but AP 3110 has more urgent traffic than the buffered traffic for another STA associated with AP 3110.

In additional or alternative embodiments, at the time that QoS null frame 3170 is utilized by STA 3111 to indicate to AP 3110 that no additional data is to be communicated by STA 3111 to STA 3112, STA 3111 can utilize an indication 3171 to request to be allowed to utilize TXS power saving operation. At that time, based at least on the example factors described above, AP 3110 can determine whether to permit usage of TXS power saving operation by STA 3111 in response to indication 3171 (TXS PS request) included with QoS null frame 3170.

With respect to communicating determination information corresponding to indication 3117 to STA 3111, one or more embodiments can utilize approaches described with FIG. 15 above, e.g., an approach to communicating the determination may utilize a frame communicated from AP 3110 to STA 1511, including one or more of a trigger frame, an immediate response frame (e.g., an Ack frame or BlockAck (BA) frame), a control frame, a management frame, an action frame, a QoS data frame, and/or a QoS null frame. Examples that use an immediate response frame (e.g., acknowledgement frame 3135) are described with FIGS. 15 and 27. The immediate response frame (e.g., acknowledgement frame 3135) may comprise indication 3117. In an embodiment, indication 3117 may be comprised in a separate frame with acknowledgement frame 3135. In an additional or alternative embodiment, indication 3171 may be comprised in a separate frame with QoS null frame 3170. In an embodiment, AP 3110 and STA 3111 operations for indication 3117 will be same as the operations described above.

In an example, while STA 3111 is in listen state 3130, AP 3110 may transmit DL PPDU 3136 to STA 3112 and STA 3112 may transmit BA 3120-3 to AP 3110 in response to DL PPDU 3136. In an example, AP 3110 may transmit an initial control frame (ICF) 3137 to STA 3111. The initial control frame may comprise a RTS frame, an MU-RTS frame, a BSRP frame, a BAR frame, or a new control frame. After receiving ICF 3137, STA 3111 may transition from the second power state (listen state) to the first power state (awake state). In response to ICF 3137, STA 3111 may transmit an initial control response frame (ICR) 3180 to AP 3110. After receiving ICR 3180, AP 3110 may transmit DL PPDU 3136 to STA 3111. In response to DL PPDU 3136, STA 3111 may transmit BA 3185.

Claims

CLAIMS:

1. A method of controlling wireless medium access in a wireless network, the network comprising a first device and a second device, the first device being arranged to enter a power-saving state when it has made a no-data-expected determination, the no-data-expected determination being that it expects to receive no more data, the method comprising:

- acquiring by the first device a reservation for access to the wireless medium, the reservation having a first duration;

- sending, by the first device to the second device, a first message containing an indication that first device is relinquishing a first part of the reservation to the second device;

- receiving, by the first device from the second device, after the first message, a second message containing a power-save disallow indication, the power-save disallow indication instructing the first device to not enter a power-saving state, wherein the first device remains in an awake state at least for a second part of the reservation, wherein the second part is contained within the first part.

2. The method of any preceding claim wherein power-save disallow indication is carried in a data frame.

3. The method of any preceding claim wherein the power-save disallow indication is carried in a control or management frame.

4. A method of controlling wireless medium access in a wireless network, the network comprising a first device and a second device, the first device being arranged to enter a power-saving state when it has made a no-data-expected determination, the no-data-expected determination being that it expects to receive no more data, the first device having sent a request to enter a power-saving state to the second device, the method comprising:

- sending, by the first device to the second device, a first message containing an indication that first device is relinquishing the reservation to the second device;

- receiving, by the first device from the second device, after the first message, a second message containing a power-saving allowed indication, the power-saving allowed indication indicating that the first device is allowed to enter a power-saving state; wherein the first device enters a power-saving state based on receiving the power-saving allowed indication.

5. The method of any preceding claim wherein power-save allow indication is carried in a data frame.

6. The method of any preceding claim wherein the power-save allow indication is carried in a control/management frame.

7. The method of any preceding claim wherein the first device is arranged to start a No Data Timer after making the no-data-expected determination, and to remain awake at least until the expiry of the No Data Timer or the receipt of one of the power-saving disallow indication or the power-saving allow indication.

8. The method of claim 7 wherein the value of the No Data Timer is either a fixed value or is based on a characteristic of recent traffic to or from the first device.

9. The method of claim 7 or 8 wherein the value of the No Data Timer is provided by second device to the first device.

10. A method of controlling wireless medium access in a wireless network, the network comprising a first device and a second device, the first device being arranged to enter a power-saving state when it has made a no-data-expected determination, the no-data-expected determination being that it expects to receive no more data, the method comprising:

- sending, by the first device to the second device, a first message containing an indication that first device is relinquishing a first part of the reservation duration to the second device, wherein the first device remains in an awake state at least for a second part of the reservation, wherein the remaining in the awake state is based on a characteristic of recent traffic to or from the first device, wherein the first part is contained within the first part.

11. A method comprising: receiving, by a station (STA) from an access point (AP), a first frame indicating: a first time period, of a transmit opportunity (TXOP), allocated to the STA; and a sharing mode of the first time period; transmitting, by the STA to the AP and during the first time period, a second frame indicating a return by the STA of the first time period to the AP; and after transmitting the second frame, transitioning, by the STA, from a first power state to a second power state based on the sharing mode.

12. A method comprising: transmitting, by an access point (AP) to a station (STA), a first frame indicating: a first time period of a transmit opportunity (TXOP), allocated to the STA; and a sharing mode of the first time period; and receiving, by the AP from the STA during the first time period, a second frame indicating a return by the STA of the first time period to the AP.

13. A method comprising : transmitting, by an access point (AP) to a station (STA), a first frame indicating a time period, of a transmit opportunity (TXOP), allocated to the STA; and receiving, by the AP from the STA and during the time period, a second frame indicating a return by the STA of the time period to the AP.

14. A method comprising: transmitting, by an access point (AP) to a station (STA), a first frame indicating: a first time period of a transmit opportunity (TXOP), allocated to the STA; and a sharing mode of the first time period; and receiving, by the AP from the STA during the first time period, a second frame comprising a first indication of transitioning from the first power state to the second power state.

15. A method comprising : transmitting, by an access point (AP) to a station (STA), a first frame indicating: a first time period of a transmit opportunity (TXOP), allocated to the STA; and a sharing mode of the first time period; receiving, by the AP from the STA during the first time period, a second frame comprising a first indication of transitioning from the first power state to the second power state; and transmitting, by the AP to the STA during the first time period, a third frame comprising a second indication whether the STA is allowed to be in the second power state.

16. A method comprising: transmitting, by an access point (AP) to a station (STA), a first frame indicating: a first time period of a transmit opportunity (TXOP), allocated to the STA; and a sharing mode of the first time period; receiving, by the AP from the STA during the first time period, a second frame comprising indicating a return by the STA of the first time period to the AP; and transmitting, by the AP to the STA during the first time period, a third frame comprising a second indication whether the STA is allowed to be in the second power state.

17. A device (STA1), arranged to control wireless medium access in a wireless network, the network comprising a first device and a second device, the first device being arranged to enter a powersaving state when it has made a no-data-expected determination, the no-data-expected determination being that it expects to receive no more data, the first device comprising a processor arranged to cause the first device to:

- acquire a reservation for access to the wireless medium, the reservation having a reservation duration;

- send, to the second device, a first message containing an indication that first device is relinquishing a first part of the reservation duration to the second device;

- receive, from the second device, after the first message, a second message containing a power-save disallow indication, the power-save disallow indication instructing the first device to not enter a power-saving state

- remain in an awake state at least for a second part of the reservation duration, wherein the first part is contained within the first part.

18. A device (STA1), arranged to control wireless medium access in a wireless network, the network comprising a first device and a second device, the first device being arranged to enter a powersaving state when it has made a no-data-expected determination, the no-data-expected determination being that it expects to receive no more data, the first device comprising a processor arranged to cause the first device to:

- receive, from the second device, after the first message, a second message containing a power-save allow indication, the power-save allow indication, the power-save allow indication indicating that the first device is allowed enter a power-saving state;

- enter a power-save state for a second part of the reservation duration based on the reception of the power-save allow indication, wherein the second part is contained within the first part.

19. A device (STA1), arranged to control wireless medium access in a wireless network, the network comprising a first device and a second device, the first device being arranged to enter a powersaving state when it has made a no-data-expected determination, the no-data-expected determination being that it expects to receive no more data, the first device comprising a processor arranged to cause the first device to:

- send, to the second device, a first message containing an indication that first device is relinquishing a first part of the reservation duration to the second device; - remain in an awake state at least for a second part of the reservation duration based on a characteristic of recent traffic to and/or from the first device, wherein the second part is contained within the first part.

20. A computer program product, storable on a computer-readable medium and arranged, when run a computer to execute the method of any of claims 1 - 16.