HK40009425B - Method and apparatus for optimizing target wake-up time (twt) operation - Google Patents

Description

Method and apparatus for optimizing target wake time (TWT) operation

Claiming priority under Section 119 of the United States Patent Act

This application claims priority to U.S. application Ser. No. 15/791,080, filed on October 23, 2017, which claims priority to and the benefit of U.S. Provisional Patent Application Serial No. 62/412,266, filed on October 24, 2016, both of which are assigned to the assignee of this application and are expressly incorporated herein by reference.

background

Technical Field

[0011] Generally speaking, certain aspects of the present disclosure relate to wireless communications and, more particularly, to coordinating target wake times (TWTs) for different wireless nodes and indicating which wireless nodes are to be served during TWT service periods.

Background Art

Wireless communication networks are widely deployed to provide various communication services such as voice, video, packet data, messaging, and broadcast. These wireless networks may be multiple-access networks capable of supporting multiple users by sharing available network resources. Examples of such multiple-access networks include code division multiple access (CDMA) networks, time division multiple access (TDMA) networks, frequency division multiple access (FDMA) networks, orthogonal FDMA (OFDMA) networks, and single-carrier FDMA (SC-FDMA) networks.

To address the desire for greater coverage and increased communication range, various techniques are being developed. One such technique is to use a WLAN, such as the Institute of Electrical and Electronics Engineers (IEEE) 802.11ah wireless network, to conduct some communications to the device, and to use a WWAN, such as a Long Term Evolution (LTE) network, to conduct other communications to the device. Having a device monitor for paging messages in one or more WLANs and a WWAN may cause the device to consume more power than it would if it were monitoring only one network for paging messages (e.g., during wake-up time, the receive circuitry remains on longer resulting in more power consumption). Therefore, it is desirable to develop techniques for devices to conserve power while monitoring paging messages in one or more WLANs and a WWAN.

Summary of the Invention

Certain aspects of the present disclosure provide an apparatus for wireless communication. The apparatus generally includes a processing system configured to generate one or more first frames, the one or more first frames collectively including a set of parameters defining at least one broadcast target wake time (TWT) schedule and an assignment of one or more wireless nodes to one or more TWT groups, the one or more TWT groups to be served in different TWT service periods (SPs) associated with the at least one broadcast TWT schedule, and a first interface configured to output the one or more first frames for transmission.

Certain aspects of the present disclosure provide an apparatus for wireless communication. The apparatus generally includes a first interface configured to obtain one or more first frames from a wireless node, the one or more first frames collectively including a set of parameters defining at least one broadcast target wake time (TWT) schedule and assigning apparatuses to at least one TWT group, the at least one TWT group being to be served in a TWT service period (SP) associated with the at least one broadcast TWT schedule, and a processing system configured to cause the apparatus to exit a first state (e.g., a reduced power state/inactive state) before or during the TWT SP based on the broadcast TWT schedule and the assignment.

Aspects of the present disclosure also provide various methods, units, and computer program products corresponding to the above-mentioned means and operations.

BRIEF DESCRIPTION OF THE DRAWINGS

Thus, the manner in which the above-described features of the present disclosure, briefly summarized above, can be understood in detail may be more particularly described by reference to the aspects, some of which are illustrated in the accompanying drawings. It should be noted, however, that the drawings illustrate only certain typical aspects of the disclosure and are therefore not to be considered limiting of its scope, as the description may admit to other equally effective aspects.

1 illustrates a diagram of an example wireless communication network in accordance with certain aspects of the present disclosure.

2 illustrates a block diagram of an example access point (AP) and user terminal (UT), in accordance with certain aspects of the present disclosure.

3 illustrates a block diagram of an example wireless node in accordance with certain aspects of the present disclosure.

4 illustrates example operations for wireless communications via an access point, in accordance with certain aspects of the present disclosure.

FIG. 4A illustrates example components capable of performing the operations illustrated in FIG. 4 .

5 illustrates example operations for wireless communications by a wireless station, in accordance with certain aspects of the present disclosure.

FIG. 5A illustrates example components capable of performing the operations illustrated in FIG. 5 .

6 illustrates an example timing diagram for using beacon frames to indicate wireless nodes to be served in a TWT, in accordance with certain aspects of the present disclosure.

DETAILED DESCRIPTION

A station (STA) operating according to the IEEE 802.11ah wireless networking standard can enter a low-power state (e.g., deep sleep mode) in which the STA shuts down one or more components, including the receiver component, and does not transmit or receive until the STA wakes up. Such a STA can associate with a WLAN access point (AP) and can be configured to periodically wake up to listen for paging messages from the AP and/or send data to the AP. When the STA is preparing to enter a low-power state, the STA and the AP can negotiate a target wake-up time (TWT) when the STA is about to wake up. The TWT may occur periodically. By negotiating the TWT, the STA is configured to periodically wake up and listen for paging messages, and the AP is configured to page the STA if it has data to send to the STA. If data intended for the STA arrives at the AP while the STA is in a low-power state, the AP can buffer the data until the next TWT occurs, and then send a paging message to the STA to notify the STA that the STA can exit the low-power state (e.g., by waking up from a low-power state, an inactive state, or other unavailable state). After the STA has exited the low-power state, the AP can send the buffered data to the STA.

Various aspects of the present disclosure are described more fully below with reference to the accompanying drawings. However, the present disclosure can be embodied in many different forms and should not be interpreted as being limited to any specific structure or function given throughout the present disclosure. On the contrary, these aspects are provided so that the present disclosure will be thorough and complete, and the scope of the present disclosure will be fully conveyed to those skilled in the art. Based on the teachings herein, those skilled in the art should understand that the scope of the present disclosure is intended to cover any aspect of the present disclosure described herein, whether it is implemented independently of any other aspect of the present disclosure or implemented in combination with any other aspect of the present disclosure. For example, any number of aspects set forth herein can be used to implement a device or practice method. In addition, the scope of the present disclosure is intended to cover such a device or method, which is practiced using other structures, functions, or structures and functions in addition to or different from the various aspects of the present disclosure set forth herein. It should be understood that any aspect of the disclosure described herein can be embodied by one or more elements of the claims.

The word “exemplary” is used herein to mean “serving as an example, instance, or illustration.” Any aspect described herein as “exemplary” is not necessarily to be construed as preferred or advantageous over other aspects.

Although specific aspects are described herein, many variations and permutations of these aspects fall within the scope of the present disclosure. Although some benefits and advantages of preferred aspects are mentioned, the scope of the present disclosure is not intended to be limited to a particular benefit, use, or purpose. Rather, various aspects of the present disclosure are intended to be broadly applicable to different wireless technologies, system configurations, networks, and transmission protocols, some of which are illustrated by way of example in the accompanying drawings and in the following description of preferred aspects. The detailed description and drawings are merely illustrative of the present disclosure and are not limiting. The scope of the present disclosure is defined by the appended claims and their equivalents.

Exemplary Wireless Communication Systems

The technology described herein can be used in various broadband wireless communication systems, including communication systems based on orthogonal multiplexing schemes. Examples of such communication systems include space division multiple access (SDMA) systems, time division multiple access (TDMA) systems, orthogonal frequency division multiple access (OFDMA) systems, single carrier frequency division multiple access (SC-FDMA) systems, and the like. SDMA systems can use sufficiently different directions to simultaneously transmit data belonging to multiple user terminals. TDMA systems can allow multiple user terminals to share the same frequency channel by dividing the transmission signal into different time slots, where each time slot is assigned to a different user terminal. OFDMA systems use orthogonal frequency division multiplexing (OFDM), which is a modulation technique that divides the entire system bandwidth into multiple orthogonal subcarriers. These subcarriers can also be called tones, frequency bands, etc. With OFDM, each subcarrier can be independently modulated with data. SC-FDMA systems can use interleaved FDMA (IFDMA) to transmit on subcarriers distributed across the system bandwidth, localized FDMA (LFDMA) to transmit on blocks of adjacent subcarriers, or enhanced FDMA (EFDMA) to transmit on multiple blocks of adjacent subcarriers. Typically, modulation symbols are sent in the frequency domain using OFDM and in the time domain using SC-FDMA.

The teachings herein may be incorporated into (eg, implemented within or performed by) various wired or wireless devices (eg, nodes). In some aspects, a wireless node implemented in accordance with the teachings herein may comprise an access point or an access terminal.

An access point ("AP") may include, be implemented as, or be referred to as, a Node B, a radio network controller ("RNC"), an evolved Node B (eNB), a base station controller ("BSC"), a base transceiver station ("BTS"), a base station ("BS"), a transceiver function ("TF"), a wireless router, a wireless transceiver, a basic service set ("BSS"), an extended service set ("ESS"), a radio base station ("RBS"), or some other terminology.

An access terminal ("AT") may include, be implemented as, or be referred to as, a user station, a subscriber unit, a mobile station (MS), a remote station, a remote terminal, a user terminal (UT), a user agent, a user device, a user equipment (UE), a user station, or some other terminology. In some implementations, an access terminal may include a cellular phone, a cordless phone, a session initiation protocol ("SIP") phone, a wireless local loop ("WLL") station, a personal digital assistant ("PDA"), a handheld device with wireless connection capability, a station ("STA"), or some other suitable processing device connected to a wireless modem. Therefore, one or more aspects of this document's teachings may be incorporated into a phone (e.g., a cellular phone or a smartphone), a computer (e.g., a laptop), a tablet computer, a portable communication device, a portable computing device (e.g., a personal data assistant), an entertainment device (e.g., a music or video device or a satellite radio), a global positioning system (GPS) device, or any other suitable device configured to communicate via a wireless or wired medium. In some aspects, the node is a wireless node. Such a wireless node may provide, for example, connectivity for or to a network (eg, a wide area network such as the Internet or a cellular network) via a wired or wireless communication link.

1 shows a multiple-access multiple-input multiple-output (MIMO) system 100 with access points and user terminals in which aspects of the present disclosure may be practiced. For example, one or more user terminals 120 may signal capabilities (eg, to access point 110) using the techniques provided herein.

For simplicity, only one access point 110 is shown in FIG1 . An access point is typically a fixed station that communicates with user terminals and may also be referred to as a base station or some other terminology. A user terminal may be fixed or mobile and may also be referred to as a mobile station, a wireless device, or some other terminology. An access point 110 may communicate with one or more user terminals 120 on a downlink and an uplink at any given moment. The downlink (i.e., forward link) is the communication link from the access point to the user terminal, while the uplink (i.e., reverse link) is the communication link from the user terminal to the access point. A user terminal may also communicate peer-to-peer with another user terminal. A system controller 130 couples to the access points and provides coordination and control for the access points.

While portions of the following disclosure will describe user terminals 120 capable of communicating via spatial division multiple access (SDMA), for certain aspects, the user terminals 120 may also include some user terminals that do not support SDMA. Thus, for these aspects, the AP 110 may be configured to communicate with both SDMA user terminals and non-SDMA user terminals. This approach can conveniently allow older versions of user terminals ("legacy" stations) to remain deployed in an enterprise to extend their useful life, while allowing newer SDMA user terminals to be introduced when deemed appropriate.

Access point 110 and user terminals 120 use multiple transmit antennas and multiple receive antennas for data transmission on the downlink and uplink. For downlink MIMO transmission, the _Nap antennas of access point 110 represent the multiple-input (MI) portion of MIMO, while the set of K user terminals represents the multiple-output (MO) portion of MIMO. Conversely, for uplink MIMO transmission, the set of K user terminals represents the MI portion, while the _Nap antennas of access point 110 represent the MO portion. For pure SDMA, it is expected that _Nap ≥ K ≥ 1 if the data symbol streams for the K user terminals are not multiplexed in code, frequency, or time in some way. K can be greater than _Nap if the data symbol streams are multiplexed using TDMA techniques, different code channels with CDMA, disjoint sets of subbands with OFDM, etc. Each selected user terminal transmits and/or receives user-specific data to and from the access point. Typically, each selected user terminal may be equipped with one or more antennas (i.e., _Nut ≥ 1). The K selected user terminals may have the same number or different numbers of antennas.

The system 100 can be a time division duplex (TDD) system or a frequency division duplex (FDD) system. For a TDD system, the downlink and uplink share the same frequency band. For an FDD system, the downlink and uplink use different frequency bands. The MIMO system 100 can also use a single carrier or multiple carriers for transmission. Each user terminal can be equipped with a single antenna (e.g., to keep costs down) or multiple antennas (e.g., where the additional cost can be supported). If the user terminals 120 share the same frequency channel by dividing the transmission/reception into different time slots, the system 100 can also be a TDMA system, where each time slot is assigned to a different user terminal 120.

FIG2 shows a block diagram of access point 110 and two user terminals 120m and 120x in MIMO system 100. Access point 110 and two user terminals 120m and 120x may be examples of access point 110 and user terminals 120 described above with reference to FIG1 and may be capable of performing the techniques described herein. The various processors shown in FIG2 may be configured to perform (or direct the devices to perform) the various methods described herein, such as operations 400 and 500 described in conjunction with FIG4 and FIG5.

Access point 110 is equipped with N _t antennas 224a to 224t. User terminal 120m is equipped with N _ut,m antennas 252ma to 252mu, and user terminal 120x is equipped with N _ut,x antennas 252xa to 252xu. Access point 110 is a transmitting entity for the downlink and a receiving entity for the uplink. Each user terminal 120 is a transmitting entity for the uplink and a receiving entity for the downlink. As used herein, a "transmitting entity" is an independently operated device or apparatus capable of transmitting data via a wireless channel, and a "receiving entity" is an independently operated device or apparatus capable of receiving data via a wireless channel. In the subsequent description, the subscript "dn" indicates downlink, and the subscript "up" indicates uplink. For SDMA transmission, N _up user terminals transmit simultaneously on the uplink, while N _dn user terminals are transmitted simultaneously by access point 110 on the downlink. _Nup may or may not be equal to _Ndn , and _Nup and _Ndn may be static values or can change for each scheduling interval.Beam steering or some other spatial processing technique may be used at the access point and user terminal.

On the uplink, at each user terminal 120 selected for uplink transmission, a transmit (TX) data processor 288 receives traffic data from a data source 286 and control data from a controller 280. Controller 280 may be coupled to a memory 282. TX data processor 288 processes (e.g., encodes, interleaves, and modulates) the traffic data for the user terminal based on the coding and modulation scheme associated with the rate selected for the user terminal and provides a data symbol stream. TX spatial processor 290 performs spatial processing on the data symbol stream and provides N _ut,m transmit symbol streams for the N _ut,m antennas. Each transmitter unit (TMTR) 254 receives and processes (e.g., converts to analog, amplifies, filters, and frequency upconverts) a corresponding transmit symbol stream to generate an uplink signal (e.g., the transmitter unit or corresponding circuitry may perform the uplink signal generation). _{The N ut,m} transmitter units 254 provide N _ut,m uplink signals for transmission from the N _ut,m antennas 252 to the access point.

_Nup user terminals may be scheduled for simultaneous transmission on the uplink. Each of these user terminals performs spatial processing on its data symbol stream and transmits its set of transmit symbol streams on the uplink to the access point.

At access point 110, N _ap antennas 224a through 224ap receive uplink signals from all N _up user terminals transmitting on the uplink. Each antenna 224 provides a received signal to a corresponding receiver unit (RCVR) 222. Each receiver unit 222 performs processing complementary to that performed by transmitter unit 254 and provides a received symbol stream. An RX spatial processor 240 performs receiver spatial processing on the N _ap received symbol streams from N _ap receiver units 222 and provides N _up recovered uplink data symbol streams. Receiver spatial processing may be performed based on channel correlation matrix inversion (CCMI), minimum mean square error (MMSE), soft interference cancellation (SIC), or some other technique. Each recovered uplink data symbol stream is an estimate of the data symbol stream sent by the corresponding user terminal. An RX data processor 242 processes (e.g., demodulates, deinterleaves, and decodes) each recovered uplink data symbol stream based on the rate used for that stream to obtain decoded data. The decoded data for each user terminal may be provided to a data sink 244 for storage and/or to a controller 230 for further processing. Controller 230 may be coupled to a memory 232.

On the downlink, at access point 110, a TX data processor 210 receives traffic data from a data source 208 for the _Ndn user terminals scheduled for downlink transmission, control data from a controller 230, and possibly other data from a scheduler 234. The various types of data may be transmitted on different transmission channels. The TX data processor 210 processes (e.g., encodes, interleaves, and modulates) the traffic data for each user terminal based on a rate selected for that user terminal. The TX data processor 210 provides _Ndn downlink data symbol streams for the _Ndn user terminals. A TX spatial processor 220 performs spatial processing (e.g., precoding or beamforming, as described in this disclosure) on the _Ndn downlink data symbol streams and provides _Nap transmit symbol streams for _Nap antennas. Each transmitter unit 222 receives and processes a respective transmit symbol stream to generate a downlink signal. _Nap transmit units 222 provide _Nap downlink signals for transmission from _Nap antennas 224 to the user terminals.

At each user terminal 120, Nut _,m antennas 252 receive _Nap downlink signals from access point 110. Each receiver unit 254 processes the received signal from its associated antenna 252 and provides a received symbol stream. An RX spatial processor 260 performs receiver spatial processing on the _Nut,m received symbol streams from Nut _,m receiver units 254 and provides a recovered downlink data symbol stream for the user terminal. Receiver spatial processing may be performed based on CCMI, MMSE, or some other technique. An RX data processor 270 processes (e.g., demodulates, deinterleaves, and decodes) the recovered downlink data symbol stream to obtain decoded data for the user terminal. The decoded data for each user terminal may be provided to a data sink 272 for storage and/or to a controller 280 for further processing.

At each user terminal 120, a channel estimator 278 estimates the downlink channel response and provides a downlink channel estimate, which may include a channel gain estimate, an SNR estimate, a noise variance, etc. Similarly, at access point 110, a channel estimator 228 estimates the uplink channel response and provides an uplink channel estimate. For each user terminal, a controller 280 typically derives a spatial filter matrix for the user terminal based on the downlink channel response matrix H _dn,m for that user terminal. Controller 230 derives a spatial filter matrix for the access point based on the effective uplink channel response matrix H _up,eff . For each user terminal, controller 280 may send feedback information (e.g., downlink and/or uplink eigenvectors, eigenvalues, SNR estimates, etc.) to the access point. Controllers 230 and 280 also control the operation of various processing units at access point 110 and user terminal 120, respectively.

3 illustrates exemplary components that may be used in AP 110 and/or UT 120 to implement aspects of the present disclosure. For example, transmitter 310, antenna 316, processor 304, and/or DSP 320 may be used to practice aspects of the present disclosure implemented by the AP or UT, such as the operations 400 described below in conjunction with FIG4 . Additionally, receiver 312, antenna 316, processor 304, and/or DSP 320 may be used to practice aspects of the present disclosure implemented by the AP or UT, such as the operations 500 described below in conjunction with FIG5 . A wireless node (e.g., a wireless device) 302 may be an access point 110 or a user terminal 120.

A wireless node (e.g., a wireless device) 302 may include a processor 304 that controls the operation of the wireless node 302. The processor 304 may also be referred to as a central processing unit (CPU). The processor 304 may control the wireless node 302 to perform various methods described herein, such as operations 400 and 500 described in conjunction with Figures 4 and 5. Memory 306, which may include both read-only memory (ROM) and random access memory (RAM), provides instructions and data to the processor 304. A portion of the memory 306 may also include non-volatile random access memory (NVRAM). The processor 304 typically performs logical and arithmetic operations based on program instructions stored in the memory 306. The instructions in the memory 306 may be executable to implement the methods described herein, such as operations 400 and 500 described in conjunction with Figures 4 and 5.

The wireless node 302 may also include a housing 308, which may include a transmitter 310 and a receiver 312 to allow transmission and reception of data between the wireless node 302 and a remote node. The transmitter 310 and the receiver 312 may be combined into a transceiver 314. A single transmit antenna or multiple transmit antennas 316 may be attached to the housing 308 and electrically coupled to the transceiver 314. The wireless node 302 may also include (not shown) multiple transmitters, multiple receivers, and multiple transceivers.

The wireless node 302 may use multiple transmitters, multiple receivers, and/or multiple transceivers to communicate with a WWAN and one or more WLANs. Additionally or alternatively, the wireless node 302 may communicate with the WWAN via a single transmitter 310, a single receiver 312, and/or a single transceiver 314, and re-tune the transmitter 310, receiver 312, and/or transceiver 314 (away from the WWAN) to communicate with one or more WLANs.

The wireless node 302 may also include a signal detector 318 that may be used to attempt to detect and quantify the level of the signal received by the transceiver 314. The signal detector 318 may detect signals such as total energy, energy per subcarrier per symbol, power spectral density, and other signals. The wireless node 302 may also include a digital signal processor (DSP) 320 for processing signals.

The various components of the wireless node 302 may be coupled together via a bus system 322 , which may include, in addition to a data bus, a power bus, a control signal bus, and a status signal bus.

Typically, APs and STAs can perform similar (e.g., symmetrical or complementary) operations. Therefore, for many of the techniques described herein, an AP or STA can perform similar operations. For this reason, the following description will sometimes refer to "AP/STA" to reflect operations that can be performed by either an AP or a STA. However, it should be understood that even if only "AP" or "STA" is used, it does not imply that the corresponding operations or mechanisms are limited to that type of device.

Example Coordination of Receiver Wake-up Times for WWAN and WLAN

As described above, a station (STA) operating in a type of network according to a standard (e.g., the IEEE 802.11ah wireless networking standard) may enter a low-power state (e.g., deep sleep mode). In this state, the STA may shut down one or more components, including a receiver component, and may not transmit or receive until the STA exits the low-power state (wakes up).

In some cases, such a STA may negotiate with another STA (e.g., a non-AP STA may negotiate with an AP) a target wake-up time (TWT) that indicates when the STA will wake up. In some cases, the timing of the (next) TWT may be explicitly indicated (from or to the STA) each time the STA interacts with the other STA. In other cases, TWTs may occur periodically, and the parameters of the TWT schedule (which may be part of the TWT configuration) may be negotiated in advance.

In any case, by negotiating a TWT, the STA is configured to wake up at the scheduled TWT and can listen for paging messages sent by the AP or can send polling frames to the AP. Similarly, the AP can be configured to send one or more paging frames to the STA or be configured to receive polling frames from the STA at those times. This approach allows the STA to remain in a low-power state until those times.

During the frame exchange, communication devices (e.g., STA and AP) can communicate with each other, regardless of whether they have data to send to each other. In some embodiments, the STAs exchange other information, such as requests to switch frequency bands and/or communication technologies. When the AP indicates data availability, if data for the STA arrives at the AP while the STA is in a low power state, the AP can cache the data until the next TWT. During the next TWT, the AP can then send a paging message to the STA to notify the STA that the STA can exit the low power state (e.g., wake up). After the STA has exited the low power state, the AP can send the cached data to the STA. Although this example specifically involves one STA, it will be understood by those skilled in the art that the scheduling process can be negotiated and used by one or more STAs, and/or negotiated and used in conjunction with one or more STAs.

According to various aspects of the present disclosure, a STA may determine whether the STA is within range of a second WLAN (e.g., an IEEE 802.11ac WLAN) based on a signal strength metric. An example of such a metric includes a reference signal strength indicator (RSSI) of a first WLAN (e.g., an IEEE 802.11ah WLAN). Based on such a metric, for example, if the signal strength metric of the first WLAN is equal to or greater than a threshold, the STA may determine to activate a second receiver, transmitter, and/or transceiver to communicate with the second WLAN.

According to aspects of the present disclosure, a STA may receive a paging message from a WLAN via a sub-gigahertz (S1G) beacon. Alternatively or additionally, the STA may receive a paging message via a Null Data Packet (NDP) paging message. The NDP paging message may include an identifier (e.g., a P-ID field including a portion of the STA's Association Identification (AID)) or, if the paging AP determines to page multiple STAs, an identifier assigned to one or more STAs.

According to aspects of the present disclosure, a STA may receive a paging message or a Traffic Indication Map (TIM) including information for multiple STAs from a WLAN. If the paging message is a Delivery Traffic Indication Map (DTIM), which may be indicated by bit 0 of the TIM being 1, the paging message may also indicate whether there is multicast/broadcast traffic buffered at the AP.

Exemplary TWT Scheduling Optimization

As described above, a target wake time (TWT) generally refers to a scheduling mechanism that allows an AP and one or more STAs to establish a time or set of times for the STAs to access the medium. As described above, the use of a TWT is generally negotiated between the AP and the STAs, and the use of a TWT can be used to reduce network energy consumption because the stations can enter a low (reduced) power state (e.g., with one or more receiving and/or transmitting components powered off) until their TWT arrives.

Thus, TWT can provide an effective approach for various situations, such as when a STA has periodic traffic. However, in dense deployment scenarios, a STA may sometimes wait for a long time before being served by the AP. This waiting time may result in poor power savings at the STA due to unnecessary wake-ups and inefficient use of TWT operations.

Generally speaking, an AP typically has a better understanding of the surrounding environment and congestion within its own BSS. Therefore, it may be beneficial for the AP to signal and schedule STAs in an on-demand manner in an attempt to ensure efficient use of TWT SPs and effective power savings at the STAs.

Aspects of the present disclosure provide techniques that can assist in enhanced TWT operation. For example, in some cases, the AP and STA can establish a specific TWT schedule based on TWT groups selected in a specific manner. In some cases, one or more frames can indicate an association identifier (AID) and/or a range of broadcast TWT identifiers that define one or more TWT groups. In other cases, the TWT groups can include different TWT groups to be served in different repetition intervals of the broadcast TWT schedule.

4 illustrates example operations 400 that may be performed by an apparatus, such as an access point (AP), in accordance with aspects of the present disclosure.

Operations 400 begin at 402 by generating one or more first frames that collectively include a set of parameters defining at least one broadcast target wake time (TWT) schedule and assigning one or more wireless nodes to one or more TWT groups to be served in different TWT service periods (SPs) associated with the at least one broadcast TWT schedule. At 404, the AP outputs the one or more first frames for transmission.

5 illustrates example operations 500 that may be performed by a wireless node, such as a STA, according to aspects of the present disclosure. Operations 500 may be considered as STA-side declarations that are complementary to operations 400. In other words, operations 500 may be performed by a STA served by an AP that performs operations 400 described above.

Operations 500 begin at 502 by obtaining one or more first frames from a wireless node, the one or more first frames collectively comprising a set of parameters defining at least one broadcast target wake time (TWT) schedule and assigning devices to at least one TWT group to be served in a TWT service period (SP) associated with the at least one broadcast TWT schedule. At 504, based on the at least one broadcast TWT schedule and the assignment, the device exits a first state (e.g., a reduced power state/inactive state) before or during the TWT SP.

In some cases, during each TWT service period (SP), the AP may indicate which STAs will be served (or will not be served), which may allow the STAs that will not be served to re-enter or return to a low-power (or other unavailable) state or some other state in which the STA is unavailable (e.g., the STA re-enters a low-power state). The techniques described herein generally allow a STA to know whether it is to be served in a TWT SP so that it may know whether to remain in an available state or otherwise return to an unavailable state during the TWT SP. The unavailable state may be a low-power state or some other state that makes the STA effectively unavailable, such as tuning away to participate in some other network. Thus, the term wake-up or wake-up scheduling may generally refer to when a STA becomes available, regardless of the reason.

In certain aspects, the AP may set up one or more broadcast TWT schedules. Such schedules may be considered "unnegotiated" and provide TWT service periods (SPs) that are somewhat independent of TWT requests. In some cases, the broadcast TWT schedules may be limited to STAs that do not have individual TWT negotiations but support the broadcast TWT SP.

Aspects of the present disclosure provide various ways to group stations (into TWT groups) to be served in the same TWT SP. For example, during association, the AP may inform the STA of the TWT group ID to which the STA is assigned. As another example, after the TWT schedule is announced, the AP may inform the STA of the TWT group ID.

In some cases, the AP may learn the STA wake-up (or more generally availability) schedule and assign (or reallocate) the STA to the appropriate group (after learning the schedule). For example, the AP may attempt to align the TWT SP of a given group with the wake-up schedule of the STAs in that group. In some cases, the AP may learn the preferred wake-up schedule, for example, based on the presence of wireless nodes detected during previous TWT SPs.

In some cases, after the AP has announced the broadcast TWT schedule, STAs can select group IDs based on their preferred wake-up schedule. In some cases, the AP announces a single TWT schedule and assigns group IDs corresponding to different repetition intervals of that schedule. For example, if the TWT schedule repeats every 20ms, the first group can have a TWT schedule of 20ms (G1=20ms frequency), while the second group can have a TWT schedule of 40ms (G2 represents 40ms frequency), and the third group can have a TWT schedule of 60ms (e.g., G3 represents 60ms frequency). In some cases, a STA can select one or more groups with TWT schedules that are closely aligned with its wake-up schedule.

In some cases, the AP may obtain a second frame indicating the preferred wake-up schedule of the STA. In this case, the AP may assign the STA to a TWT group based on the preferred wake-up schedule. The second frame may be obtained, for example, after the first frame is output for transmission or during the association process performed with the STA.

In some cases, the AP may obtain a second frame indicating a request from the STA to change the TWT group assignment or a change in the preferred wake-up time for the STA. In this case, the AP may assign the STA to a TWT group based on the request or reassign the STA to another TWT group based on the change in the preferred wake-up schedule.

In some cases, a STA can indicate whether it prefers to select its own group, whether it wants the AP to assign the STA to a specific group, or whether the STA has no preference. In some cases, such a preference (or lack thereof) may be indicated during association. In some cases, the AP may only perform group assignment for STAs that do not support a mechanism for selecting their own group. In some systems, the AP may have a default TWT SP schedule for STAs that do not have a preference for selecting their own group (TWT scheduling).

In some cases, the AP may inform the STA of the group association identifier (AID) and/or broadcast TWT identifier assigned to the STA during association. In some cases, the broadcast TWT may indicate (e.g., via the group AID field) the group of STAs that have been scheduled for the SP indicated by the TWT. As described above, the AP may learn the wake-up schedule of the STA and assign/reallocate the STA to the appropriate group. In some cases, for each TWT parameter set, a TWT information element (IE) or some other element/field may indicate the range of AIDs (e.g., by including start AID and end AID fields in the broadcast TWT IE).

Aspects of the present disclosure also provide various ways for an AP to indicate which stations of a group are to be served during a given TWT SP. Which stations of a TWT group are to be served in a particular TWT SP can be individually indicated by subsequent transmissions (e.g., TIM frames, discovery frames, or trigger frames) during a broadcast TWT that narrow down which STAs of the group are to be served.

For example, at the beginning of each broadcast TWT SP (for a TWT group), the AP may send a Traffic Indication Map (TIM) frame carrying a list of STAs (as a bitmap) that the AP intends to serve during this SP. Such a TIM frame may be the same or similar to the TIM frame defined in the standard. In this case, STAs not listed in the TIM may return to power saving mode during this SP.

In some cases, the beginning of each SP may have a short paging window (PW), during which the AP sends a TIM frame and the listed STAs respond by sending a PS-POLL (or QoS Null) frame to indicate that the STA is present during that SP. STAs that do not reply may be considered absent, and the AP may narrow down the STAs served during that SP to only those that respond.

In some cases, the indication of the station to be served may be provided in a beacon frame or a discovery frame (e.g., a Fast Initial Link Setup or "FILS" discovery frame or an FD frame). In some cases, the indication of the station can be carried in some other type of frame, such as a management frame (e.g., an action frame defined as carrying a TIM element).

As shown in Figure 6, such a discovery frame can provide a mechanism for the AP to send frequent "short" beacons (or mini-beacons) at periodic intervals between two consecutive beacon frames. In the example shown, the beacon frame can be sent with a period of 100ms using 4 FD frames sent between each beacon frame. FD frames generally refer to public action frames that may carry several (optional) elements. The bits in the FD control subfield can indicate which elements are present in the frame. Therefore, FD frames can serve as a mechanism for periodic service/scheduling advertisements.

Such a frame may include a TIM element indicating which STAs will be served in the (upcoming) TWT SP. In some cases, a reserved bit in a field of an FD frame (e.g., the FD Control subfield) indicates the presence of a TIM element. In this way, the additional overhead of sending a new frame to carry the TIM or other scheduling indication fields may not be required. In some cases, a non-AP STA may therefore check the TIM carried in such a beacon frame/FD frame to see if the non-AP STA can return to a low power state (e.g., go to sleep) until the next FD frame/beacon frame.

In this manner, each bit in the TIM (virtual) bitmap may correspond to a STA (eg, within a BSS) that the AP intends to schedule or deliver buffered traffic to when sending a frame carrying the TIM.

In some systems, the use of the TIM bitmap may be reversed. In other words, the STAs listed in the TIM may be STAs that will not be scheduled during a particular or upcoming TWT SP or time period.

In some cases, the FD frame may also carry a TWT information field, for example, to indicate an update to a specific TWT SP (e.g., a TWT SP identified based on a stream identifier). The FD frame may also carry a group ID/group AID to indicate a subset of STAs that will be addressed (served) during the period between the current FD frame and the next FD frame/beacon frame.

Some systems may employ what may be considered a "hybrid technique" involving both TIM broadcasts and FD frames. In this case, depending on the alignment of the TWT SP relative to the FD frame, the AP may send a TIM broadcast at the beginning of the TWT SP (e.g., after deciding which STAs to serve) or the AP may send an FD frame within or before the TWT SP to indicate which STAs the AP plans to serve (or not serve) during the upcoming SP.

At the beginning of the TWT period, the trigger frame may indicate the scheduling for several STAs. In some cases, the STAs to be served in the TWTSP may be signaled in one or more fields used for other purposes. For example, some or all padding fields (added to make the frame format have a certain length or to provide enough time for the triggered STA to prepare its response to the trigger frame in a short (SIFS) time) may be replaced with the AID/broadcast TWT identification (or list of STAs) of the STAs that will not be scheduled during this TWT SP. The STAs indicated in the triggered schedule may remain awake and exchange UL/DL frames with the AP. On the other hand, the STAs listed in the AID/broadcast TWT identification padding may switch to a power saving mode for the rest of the SP.

In some cases, a short paging window (PW) may be defined at the beginning of each TWT SP. In such a case, the AP may send MU QoS null frames to multiple STAs during the PW to indicate which multiple STAs will be served during that SP. In this case, STAs that do not receive QoS null frames during the PW may go to sleep for the remainder of the SP. The AP may use this MU QoS mechanism outside of the TWT SP to poll STAs that do not support or participate in TWT.

In some cases, for example, depending on the type of TWT, a STA may or may not acknowledge (ACK) an AP service announcement (i.e., a plan to serve certain STAs) to inform the AP of the presence of the STA during this SP. In the "announcement" scheme, the STA may send an UL transmission to the AP to indicate the presence of the STA during this SP. In the "no announcement" scheme, the AP may assume that the STA is present and can start serving the STA without waiting for any explicit indication from the STA.

In some cases, the TWT element may include a field (new or modify an existing field) to assign a group identifier to a specific schedule. STAs that prefer to select their schedules may select one or more TWT groups (i.e., schedules) that align with their wake-up schedules. The AP SHOULD assign a group ID to STAs that do not indicate such a preference.

In some systems, each TWT group (schedule) may allow a subset of schedules to be selected. For example, a schedule that repeats every 20ms (e.g., via group ID = 8) may allow allocation such that one STA selects a 20ms wake-up period while another selects a 60ms wake-up period. This may be achieved via a {group, band} tuple. In this case, the tuples may look like (8, 1) and (8, 3) respectively. Such a scheme may reduce the number of schedules that the AP needs to announce (i.e., a single TWT schedule is able to represent several possible wake-up schedules via the group, band tuple).

In some systems, at the beginning of each TWT service period (SP), a trigger response can serve as a mechanism for the AP to notify the group of STAs that will be served during this interval (SP), and those STAs (via their responses) can inform the AP that they are available during this SP. As an example, the AP can send an NDPA to a subset of STAs via a trigger. Only the STAs listed in the trigger can stay awake and respond to the AP. The remaining STAs can enter power saving mode. In some cases, a high efficiency (HE) probe report (i.e., response) from a STA can provide useful information to the AP and at the same time let the AP know that this particular STA is present during this SP. The AP can use this mechanism to request other types of information, such as buffer status reports.

The various operations of the above method can be performed by any appropriate unit that can perform the corresponding function. The unit may include various hardware and/or software components and/or modules, including but not limited to circuits, application specific integrated circuits (ASICs) or processors. Generally speaking, there are operations shown in the accompanying drawings, and these operations can have corresponding corresponding functional module components with similar numbers. For example, the operations 400 and 500 shown in Figures 4 and 5 correspond to the units 400A and 500A shown in Figures 4A and 5A.

For example, means for transmitting (or means for outputting for transmission) may include a transmitter or transceiver (e.g., transmitter unit 222) and/or antenna 224 of access point 110 or transmitter unit 254, and/or antenna 252 of user terminal 120 shown in FIG. Means for receiving (or means for obtaining) may include a receiver or transceiver (e.g., receiver unit 222) and/or antenna 224 of access point 110 or receiver unit 254, or receiver unit 254 and/or antenna 254 of user terminal 120 shown in FIG. The means for processing, the means for obtaining, the means for generating, the means for selecting, the means for decoding, the means for causing, the means for serving, the means for allocating, the means for reallocating, the means for deciding, the means for learning, the means for re-entering, or the means for determining may include a processing system which may include one or more processors, such as the RX data processor 242, the TX data processor 210, the TX spatial processor 220 and/or the controller 230 of the access point 110 or the RX data processor 270, the TX data processor 288, the TX spatial processor 290, and/or the controller 280 of the user terminal 120 shown in FIG. 2 .

In some cases, a device may have an interface (a unit for outputting) that outputs a frame for transmission, rather than actually sending the frame. For example, a processor may output a frame to a radio frequency (RF) front end via a bus interface for transmission. Similarly, a device may have an interface (a unit for obtaining) that obtains a frame received from another device, rather than actually receiving the frame. For example, a processor may obtain (or receive) a frame from an RF front end via a bus interface for reception.

As used herein, the term "determining" encompasses a wide variety of actions. For example, "determining" may include calculating, computing, processing, deriving, investigating, searching (e.g., searching in a table, database, or another data structure), ascertaining, and the like. Furthermore, "determining" may include receiving (e.g., receiving information), accessing (e.g., accessing data in a memory), and the like. Furthermore, "determining" may include resolving, selecting, choosing, establishing, and the like.

As used herein, a phrase referring to "at least one of" a list of items refers to any combination of those items, including single members. As an example, "at least one of a, b, or c" is intended to cover a, b, c, a-b, a-c, b-c, and a-b-c, as well as a multi-member combination (aa, bb, and/or cc) that includes one or more of the items.

The various illustrative logical blocks, modules, and circuits described in conjunction with the present disclosure may be implemented or performed using a general purpose processor, a digital signal processor (DSP), an application specific integrated circuit (ASIC), a field programmable gate array (FPGA) or other programmable logic device (PLD), discrete gate or transistor logic, discrete hardware components, or any combination thereof, designed to perform the functions described herein. A general purpose processor may be a microprocessor, but alternatively, the processor may be any commercially available processor, controller, microcontroller, or state machine. A processor may also be implemented as a combination of computing devices, such as a combination of a DSP and a microprocessor, a plurality of microprocessors, a combination of one or more microprocessors and a DSP core, or any other such configuration.

The steps of the method or algorithm described in conjunction with the present disclosure can be directly embodied as hardware, a software module executed by a processor, or a combination of the two. The software module can reside in any form of storage medium known in the art. Some examples of storage media that can be used include random access memory (RAM), read-only memory (ROM), flash memory, EPROM memory, EEPROM memory, registers, hard disk, removable hard disk, CD-ROM, etc. The software module can include a single instruction or many instructions and can be distributed on several different code segments, between different programs, and across multiple storage media. The storage medium can be coupled to the processor so that the processor can read information from the storage medium and write information to the storage medium. Alternatively, the storage medium can be integrated into the processor.

The methods described herein include one or more steps or actions for implementing the described methods. The method steps and/or actions may be interchangeable with one another without departing from the scope of the claims. In other words, unless a particular order of steps or actions is specified, the order and/or use of specific steps and/or actions may be modified without departing from the scope of the claims.

The described functions can be implemented using hardware, software, firmware, or any combination thereof. If implemented in hardware, an exemplary hardware configuration may include a processing system in a wireless node. The processing system may be implemented using a bus architecture. The bus may include any number of interconnecting buses and bridges, depending on the specific application and overall design constraints of the processing system. The bus may link together various circuits including a processor, machine-readable media, and a bus interface. The bus interface may be used to connect a network adapter, etc., to the processing system via the bus. The network adapter may be used to implement signal processing functions at the PHY layer. In the case of a user terminal 120 (see FIG. 1 ), a user interface (e.g., a keyboard, display, mouse, joystick, etc.) may also be connected to the bus. The bus may also link various other circuits, such as timing sources, peripheral devices, voltage regulators, power management circuits, etc. These circuits are well known in the art and are therefore not described further.

The processor may be responsible for managing the bus and general processing, including executing software stored on a machine-readable medium. The processor may be implemented using one or more general-purpose and/or special-purpose processors. Examples include microprocessors, microcontrollers, DSP processors, and other circuits capable of executing software. Software should be broadly interpreted to mean instructions, data, or any combination thereof, whether referred to as software, firmware, middleware, microcode, hardware description language, or other terms. As examples, a machine-readable medium may include RAM (random access memory), flash memory, ROM (read-only memory), PROM (programmable read-only memory), EPROM (erasable programmable read-only memory), EEPROM (electrically erasable programmable read-only memory), registers, magnetic disks, optical disks, hard drives, or any other suitable storage medium, or any combination thereof. The machine-readable medium may be embodied in a computer program product. The computer program product may include packaging materials.

In a hardware implementation, the machine-readable medium may be part of a processing system separate from the processor. However, as will be readily appreciated by those skilled in the art, the machine-readable medium or any portion thereof may be external to the processing system. For example, the machine-readable medium may include a transmission line, a carrier wave modulated by data, and/or a computer product separate from the wireless node, all of which may be accessed by the processor via a bus interface. Alternatively or additionally, the machine-readable medium or any portion thereof may be integrated into the processor, such as may be the case with a cache and/or general register file.

The processing system can be configured as a general-purpose processing system having one or more microprocessors providing processor functionality and external memory providing at least a portion of the machine-readable medium, all linked together with other support circuits via an external bus architecture. Alternatively, the processing system can be implemented using an ASIC (application-specific integrated circuit) having a processor, a bus interface (a user interface in the case of an access terminal), support circuits, and at least a portion of the machine-readable medium integrated into a single chip, or implemented using one or more FPGAs (field programmable gate arrays), PLDs (programmable logic devices), controllers, state machines, gating logic, discrete hardware components, or any other suitable circuits, or any combination of circuits capable of performing the various functions described throughout this disclosure. Those skilled in the art will recognize that how best to implement the functions described for the processing system depends on the specific application and the overall design constraints imposed on the entire system.

The machine-readable medium may include multiple software modules. The software modules include instructions that, when executed by the processor, cause the processing system to perform various functions. The software modules may include a transmission module and a reception module. Each software module may reside in a single storage device or be distributed across multiple storage devices. For example, when a triggering event occurs, a software module may be loaded from a hard disk into RAM. During execution of a software module, the processor may load some instructions into a cache to increase access speed. One or more cache lines may then be loaded into a general register file for execution by the processor. When referring to the functionality of a software module below, it will be understood that such functionality is implemented by the processor when instructions from that software module are executed.

If implemented with software, function can be stored or sent to a computer-readable medium as one or more instructions or codes. Computer-readable media includes both computer storage media and communication media, and communication media includes any medium that is convenient for transferring a computer program from one place to another. Storage media can be any available medium that can be accessed by a computer. As an example and not limitation, such computer-readable media can include RAM, ROM, EEPROM, CD-ROM or other optical disk storage, disk storage or other magnetic storage device, or can be used for carrying or storing desired program code in the form of an instruction or data structure and any other medium that can be accessed by a computer. Moreover, any connection is suitably referred to as a computer-readable medium. For example, if software is sent from a website, server or other remote source using a coaxial cable, optical fiber cable, twisted pair, digital subscriber line (DSL) or wireless technologies such as infrared (IR), radio and microwave, then coaxial cable, optical fiber cable, twisted pair, DSL or wireless technologies such as infrared, radio and microwave are included in the definition of medium. As used herein, disks and optical disks include compact discs (CDs), laser discs, optical discs, digital versatile discs (DVDs), floppy disks, and disks. Disks typically reproduce data magnetically, while optical discs reproduce data optically using lasers. Thus, in some aspects, computer-readable media may include non-transitory computer-readable media (e.g., tangible media). Additionally, for other aspects, computer-readable media may include transient computer-readable media (e.g., signals). Combinations of the foregoing should also be included within the scope of computer-readable media.

Thus, certain aspects may include a computer program product for performing the operations presented herein. For example, such a computer program product may include a computer-readable medium having stored (and/or encoded) thereon instructions, the instructions being executable by one or more processors to perform the operations described herein. For certain aspects, the computer program product may include packaging materials.

In addition, it should be understood that, where applicable, the modules and/or other suitable units for performing the methods and techniques described herein can be downloaded and/or otherwise obtained by the user terminal and/or base station. For example, such a device can be coupled to a server to facilitate the transmission of the units for performing the methods described herein. Alternatively, the various methods described herein can be provided via a storage unit (e.g., RAM, ROM, a physical storage medium such as a compact disc (CD) or a floppy disk), such that the user terminal and/or base station can obtain the various methods after coupling or providing the storage unit to the device. In addition, any other suitable technology for providing the methods and techniques described herein to the device can be used.

It is to be understood that the claims are not limited to the precise configuration and components shown above, and that various modifications, changes and variations may be made in the arrangement, operation and details of the methods and apparatus described above without departing from the scope of the claims.

Claims (19)

1. An apparatus for wireless communication, comprising: A processing system is configured to generate one or more first frames, the one or more first frames collectively including a set of parameters defining at least one Broadcast Target Wake-up Time (TWT) schedule and assigning one or more radio nodes to one or more TWT groups to be served in different TWT service periods (SPs) associated with the at least one broadcast TWT schedule, wherein the processing system is further configured to generate at least one second frame, for each of the TWT SPs, the at least one second frame including an indication of one or more radio nodes of the TWT group to be served; A first interface is configured to output the one or more first frames for transmission, and the first interface is further configured to output the at least one second frame for transmission; and The second interface is configured to, in response to the at least one second frame, obtain at least a third frame from one of the one or more radio nodes in the TWT group to be served. The processing system is also configured to serve wireless nodes that receive a third frame from the device. 2. The apparatus according to claim 1, wherein, The generation includes assigning the one or more wireless nodes to a TWT group corresponding to the broadcast TWT schedule; and The one or more first frames include one or more identifiers for the TWT group. 3. The apparatus according to claim 1, wherein the generation comprises: Based on one or more preferred wake-up schedules of the one or more wireless nodes, the one or more wireless nodes are assigned to the one or more TWT groups, wherein each wake-up schedule indicates the availability of a corresponding wireless node among the wireless nodes. 4. The apparatus according to claim 3, wherein the processing system is further configured to: Based on the detection of the presence of the one or more wireless nodes during the previous TWT SP, the one or more preferred wake-up schedules of the one or more wireless nodes are learned. 5. The apparatus according to claim 3, further comprising: At least the second interface is configured to receive at least a fourth frame, the fourth frame indicating the preferred wake-up scheduling of at least one of the one or more wireless nodes. 6. The apparatus according to claim 3, further comprising: At least the second interface is configured to receive at least a fourth frame, the fourth frame indicating a request from at least one of the one or more wireless nodes to change at least one of the allocated or preferred wake-up times. The processing system is configured to assign or reassign at least one of the one or more wireless nodes to the TWT group based on the request. 7. The apparatus according to claim 1, further comprising: At least the second interface is configured to receive at least a fourth frame, the fourth frame including an indication of whether the wireless node prefers to select its own TWT group; and The processing system is configured to assign a wireless node to a TWT group based at least in part on the indication that the wireless node prefers to select its own TWT group. 8. The apparatus of claim 1, wherein the at least one second frame comprises at least one of the following: A Service Indication Map (TIM) indicates one or more radio nodes in the TWT group that are to be served or one or more radio nodes that will not be served, or To output a discovery frame for transmission between beacon frames, wherein the discovery frame includes at least one of the following: There exists an element that includes the indication of one or more wireless nodes of the TWT group to be served; Update of the at least one broadcast TWT schedule; or At least one of a broadcast TWT identifier or a group broadcast TWT identifier, the broadcast TWT identifier or group broadcast TWT identifier indicating the one or more radio nodes of the TWT group to be served. 9. The apparatus according to claim 1, wherein: The at least one second frame includes a trigger frame of a first format, which is to be output at the beginning of the TWT service period for transmission; and The indication of which node in the TWT group should be served includes one or more association identifiers (AIDs) included in the location of one or more padding fields used in the trigger frame of the second format. 10. An apparatus for wireless communication, comprising: A processing system configured to generate one or more first frames, the one or more first frames collectively including a set of parameters defining at least one Broadcast Target Wake-up Time (TWT) schedule and assigning one or more radio nodes to one or more TWT groups to be served in different TWT Service Periods (SPs) associated with the at least one broadcast TWT schedule, wherein the processing system is further configured to generate at least one second frame, for each of the TWT SPs, the at least one second frame including an indication of one or more radio nodes of the TWT groups to be served; and A first interface is configured to output the one or more first frames for transmission, and the first interface is also configured to output the at least one second frame for transmission. The processing system is further configured to determine, at least in part, to provide an indication in the discovery frame about which one or more radio nodes in the TWT group should receive service, based on the alignment of the discovery frame with the broadcast TWT service period. 11. An apparatus for wireless communication, comprising: A first interface is configured to receive one or more first frames from a wireless node, the one or more first frames collectively including a set of parameters defining at least one Broadcast Target Wake-up Time (TWT) schedule and allocating the device to at least one TWT group, the at least one TWT group to be served during a TWT service period (SP) associated with the at least one broadcast TWT schedule; and The processing system is configured to, based on the broadcast TWT scheduling and the allocation, cause the device to exit a first state before or during the TWT SP, wherein The first interface is also configured to receive at least a fourth frame after exiting the first state, the fourth frame including an indication of whether the device wants to receive service; When aligned with one of the TWT SPs, each of the at least fourth frames is a discovery frame; and The processing system is also configured to re-enter the first state if the fourth frame indicates that the device will not be served. 12. The apparatus according to claim 11, wherein: The first state includes a reduced power state in which one or more components of the device are de-energized. 13. The apparatus according to claim 11, wherein: The processing system is also configured to generate at least a second frame, the second frame indicating a preferred wake-up schedule for the device used by the wireless node when determining the at least one TWT group; The device further includes at least a second interface configured to output the second frame for transmission to the wireless node; and The processing system is also configured to generate the second frame after the acquisition of the one or more first frames or during an association process performed using the wireless node. 14. The apparatus according to claim 13, wherein: The processing system is also configured to generate at least a third frame indicating a preferred change in wake-up time. 15. The apparatus according to claim 11, wherein: The processing system is also configured to generate at least a second frame, the second frame requesting the wireless node to change the device's allocation or indicating whether the device prefers to select its own TWT group; and The device also includes at least a second interface configured to output the second frame for transmission to the wireless node. 16. The apparatus according to claim 11, wherein: The first interface is also configured to receive one or more frames that reassign the device to different TWT groups; and The processing system is also configured to cause the device to exit the first state before or during a TWT SP corresponding to the different TWT groups. 17. The apparatus according to claim 11, The discovery frame is obtained between beacon frames, and The discovery frame includes at least one of a broadcast TWT identifier or a group broadcast TWT identifier, which indicates which members in the at least one TWT group need to be served. 18. The apparatus of claim 11, wherein the first interface includes a receiver configured to receive the one or more first frames, and the apparatus is configured as a wireless station. 19. A wireless station, comprising: A processing system is configured to generate one or more first frames, the one or more first frames collectively including a set of parameters defining at least one Broadcast Target Wake-up Time (TWT) schedule and assigning one or more radio nodes to one or more TWT groups to be served in different TWT service periods (SPs) associated with the at least one broadcast TWT schedule, wherein the processing system is further configured to generate at least one second frame, for each of the TWT SPs, the at least one second frame including an indication of one or more radio nodes of the TWT group to be served; A transmitter configured to transmit the one or more first frames, the transmitter further configured to output the at least one second frame for transmission; and The receiver is configured to receive at least a third frame from one of the one or more radio nodes of the TWT group to be served in response to the at least one second frame. The processing system is also configured to serve wireless nodes that receive a third frame from the wireless station.