Restricted target wake time service period membership setup for relay operation in wireless networks

Abstract

An embodiment is a method performed by a relay station (STA) to synchronize restricted target wake time (r-TWT) service periods with a STA when the relay STA is to relay traffic between the STA and an access point (AP). The method includes receiving a first target wake time (TWT) setup request frame from the STA and responsive to receiving the first TWT setup request frame from the STA, transmitting a second TWT setup request frame to the AP to schedule a r-TWT service period, wherein the second TWT setup request frame includes a request for the STA and the relay STA to be members of a same r-TWT service period.

Description

SPECIFICATIONRESTRICTED TARGET WAKE TIME SERVICE PERIOD MEMBERSHIP SETUP FOR RELAY OPERATION IN WIRELESS NETWORKSCROSS-REFERENCE TO RELATED APPLICATION

[0001] This application claims the benefit of U.S. Provisional Application No. 63 / 634,855, filed April 16, 2024, titled “Restricted Target Wake Time Service Period Membership Setup for Relay Operation in Wireless LAN Systems”, which is hereby incorporated by reference.TECHNICAL FIELD

[0002] The present disclosure generally relates to wireless communications, and more specifically, relates to synchronizing restricted target wake time (r-TWT) service periods of a station (STA) and a relay STA that is to relay traffic between the STA and an access point (AP).BACKGROUND

[0003] Institute of Electrical and Electronics Engineers (IEEE) 802.11 is a set of standards for implementing wireless local area network communication in various frequencies, including but not limited to the 2.4 gigahertz (GHz), 5 GHz, 6 GHz, and 60 GHz bands. These standards define the protocols that enable Wi-Fi devices to communicate with each other. TheIEEE 802.11 family of standards has evolved over time to accommodate higher data rates, improved security, and better performance in different environments. Some of the most widely used standards include 802.11a, 802.11b, 802 11g, 802.1 In, 802.1 lac, and 802.1 lax (also known as “Wi-Fi 6”). These standards specify the modulation techniques, channel bandwidths, and other technical aspects that facilitate interoperability between devices from various manufacturers. IEEE 802.11 has played an important role in the widespread adoption of wireless networking in homes, offices, and public spaces, enabling users to connect their devices to the internet and each other without the need for wired connections.

[0004] IEEE 802.1 Ibe, also known as “Wi-Fi 7”, is the next generation of the IEEE 802.11 family of standards for wireless local area networks. IEEE 802. 1 Ibe aims to significantly improve upon the capabilities of its predecessor, 802.11 ax / Wi-Fi 6, by offering even higher data rates, lower latency, and increased reliability. The standard is expected to leverage advanced technologies such as multi-link operation (MLO), which allows devices to simultaneously use multiple frequency bands and channels for enhanced performance and reliability.Additionally, 802. 1 Ibe will introduce 4096-QAM (Quadrature Amplitude Modulation), enabling higher data rates by encoding more bits per symbol. The standard will also feature improved medium access control (MAC) efficiency, enhanced power saving capabilities, and better support for high-density environments. With these advancements, IEEE 802. 1 Ibe is expected to deliver theoretical maximum data rates of up to 46 gigabits per second (Gbps), making it suitable for bandwidth-intensive applications such as virtual and augmented reality, 8K video streaming, and high-performance gaming.

[0005] The ongoing evolution of wireless networks is driven by ever-increasing user demands for the improvement of various quality of service (QoS) performance metrics such as data rate, delay, jitter, packet loss ratio, energy efficiency, coverage, among others. In particular, realtime applications (RTAs) such as augmented reality (AR), virtual reality (VR), industrial automation, robotics, and real-time gaming require stringent guarantees of latency in the wireless network, typically within a few milliseconds.

[0006] The IEEE 802.1 Ibe wireless networking standard (also referred to as Extremely High Throughput (EHT)) is expected to introduce several innovative features to enhance wireless network performance across various aspects such as nominal throughput, data delivery reliability, spectrum efficiency, and delay guarantees, among others One of the key features being introduced in IEEE 802 1 Ibe is restricted target wake time (r-TWT) r-TWT is a technology that is designed to support delay-sensitive data flows by providing contention-free channel access.

[0007] The r-TWT mechanism builds upon the concept of target wake time (TWT), which was introduced in the IEEE 802.1 lah wireless networking standard and inherited by the IEEE 802. 1 lax wireless networking standard (also referred to as High Efficiency (HE)), to facilitate energy-efficient communication for devices with limited energy resources. TWT technology allows an access point (AP) and stations (STAs) to establish agreements and negotiate service periods (SP) for frame exchange. TWT technology enables STAs to conserve energy by remaining in a sleep state outside of the service periods. In addition to conserving energy, TWT technology can help mitigate channel contention during service periods by efficiently scheduling member STAs to access the medium, enhancing network efficiency. r-TWT technology extends TWT by restricting transmissions within service periods only to members of the TWT agreement, thereby further reducing contention. r-TWT technology enables opportunities for differentiated QoS provisioning in wireless networks. During a r-TWT service period, RTA traffic can be prioritized for transmission without channel contention, providing strong QoS guarantees.

[0008] Furthermore, r-TWT technology provides many advanced features that can help improve network efficiency One of these features is the membership functionality. A r-TWT scheduled STA may establish membership in one or more r-TWTs between the r-TWT scheduling AP and r-TWT scheduled STAs. The r-TWT setup signaling may be similar to the signaling for broadcast TWT but with additional parameter settings.

[0009] Also, the r-TWT scheduling AP may have the capability to terminate a r-TWT service period before its scheduled end time, allowing non-member STAs to immediately contend for the channel. For example, when the r-TWT scheduling AP recognizes that all of the scheduled traffic for the r-TWT service period has been transmitted, the r-TWT scheduling AP may transmit a signal to indicate the termination of the current r-TWT service period.

[0010] The TWT technology proposed in IEEE 802.1 lax should be compatible with new features introduced in newer IEEE 802. 11 wireless networking standards such as IEEE 802.1 Ibe and IEEE 802.1 Ibn (also referred to as Ultra-High Reliability (UHR)). IEEE 802. 1 Ibe introduces a feature known as multi-link operation (MLO). MLO-capable devices may use multiple radio interfaces to transmit and receive traffic over multiple wireless links, enabling the MLO-capable devices to achieve higher throughput rates and lower latency. Techniques have been proposed for applying TWT and r-TWT to MLO. For example, a technique has been proposed to allow an AP multi-link device (MLD) that has established multiple wireless links with a non-AP MLD to schedule a r-TWT SP on one of the wireless links.

[0011] In the emerging IEEE 802.11 wireless networking standards (e g., IEEE 802.1 Ibn), various technologies are being proposed to enhance wireless network coverage and throughput. One such technology is relay technology. With relay technology, a relay STA may relay traffic between a STA and an AP. Relay technology may leverage MLO capability to improve reliability and throughput. Also, MLO-based relay operations can lead to improved energy efficiency.

[0012] It is expected that relay technology can be used with r-TWT technology. When using relay technology and r-TWT technology together, configuring the appropriate r-TWT parameters becomes important for meeting QoS requirements and enhancing energy efficiency while minimizing channel time consumption However, despite advancements in relay technology and r-TWT technology, current wireless network research has yet to explore an approach that seamlessly integrates r-TWT technology and relay technology together.BRIEF DESCRIPTION OF THE DRAWINGS

[0013] The disclosure will be more fully understood from the detailed description provided below and the accompanying drawings that depict various embodiments of the disclosure. However, these drawings should not be interpreted as limiting the disclosure to the specific embodiments shown; they are provided for explanation and understanding only.

[0014] Figure 1 illustrates an example of a wireless local area network (WLAN) with a basic service set (BSS) that includes multiple wireless devices, in accordance with some embodiments of the present disclosure.

[0015] Figure 2 is a schematic diagram of a wireless device, in accordance with some embodiments of the present disclosure.

[0016] Figure 3A illustrates components of a wireless device configured to transmit data, in accordance with some embodiments of the present disclosure.

[0017] Figure 3B illustrates components of a wireless device configured to receive data, in accordance with some embodiments of the present disclosure.

[0018] Figure 4 illustrates interframe space (IF S) relationships, in accordance with some embodiments of the present disclosure.

[0019] Figure 5 illustrates a Carrier Sense Multiple Access with Collision Avoidance (CSMAZCA)-based frame transmission procedure, in accordance with some embodiments of the present disclosure.

[0020] Figure 6 illustrates maximum physical layer (PHY) rates for Institute of Electrical and Electronics Engineers (IEEE) 802. 11 standards, in accordance with some embodiments of the present disclosure.

[0021] Figure 7 provides a detailed description of fields in Extremely High Throughput (EHT) Physical Protocol Data Unit (PPDU) frames, including their purposes and characteristics, in accordance with some embodiments of the present disclosure.

[0022] Figure 8 illustrates an example of multi-user (MU) transmission in Orthogonal Frequency -Division Multiple Access (OFDMA), in accordance with some embodiments of the present disclosure.

[0023] Figure 9 illustrates an example of an access point sending a trigger frame to multiple associated stations and receiving Uplink Orthogonal Frequency -Division Multiple Access Trigger-Based Physical Protocol Data Units (UL OFDMA TB PPDUs) in response, in accordance with some embodiments of the present disclosure.

[0024] Figure 10 is a diagram showing a wireless network environment with an access point (AP), relay stations (STAs), and STAs that are capable of multi-link operation (MLO) in a 2.4 Gigahertz (GHz) band and a 5 GHz band, according to some embodiments

[0025] Figure 11 is a diagram showing a single link operation and a multi-link operation between an AP and a non-AP STA, according to some embodiments.

[0026] Figure 12 is a diagram showing a relay STA multi-link device (MLD) that can relay communications between an AP multi-link device (MLD) and a non-AP STA MLD using MLO, according to some embodiments.

[0027] Figure 13 is a diagram showing a table of MLO relay supportability types, according to some embodiments.

[0028] Figure 14 is a diagram showing a table summarizing the types of communications available for each MLO relay supportability type, according to some embodiments.

[0029] Figure 15 is a diagram showing MLO relay supportability type #1, according to some embodiments.

[0030] Figure 16 is a diagram showing MLO relay supportability type #2, according to some embodiments.

[0031] Figure 17 is a diagram showing MLO relay supportability type #3, according to some embodiments

[0032] Figure 18 is a diagram showing MLO relay supportability type #4, according to some embodiments.

[0033] Figure 19 is a diagram showing a wireless network that can implement r-TWT technology and relay technology, according to some embodiments.

[0034] Figure 20 is a diagram showing a r-TWT service period membership setup procedure, according to some embodiments.

[0035] Figure 21 is a diagram showing a situation that can occur when a wireless network implements r-TWT technology and relay technology, according to some embodiments.

[0036] Figure 22 is a diagram showing a roaming scenario for a STA MLD in a relay-enabled environment, according to some embodiments.

[0037] Figure 23 is a diagram showing a r-TWT service period membership synchronization procedure, according to some embodiments

[0038] Figure 24 is a flow diagram showing a method for synchronizing r-TWT service periods of a STA and a relay STA, according to some embodiments

[0039] Figure 25 is a diagram showing a r-TWT service period membership update procedure, according to some embodiments.

[0040] Figure 26 is a flow diagram of a method for updating a r-TWT service period membership, according to some embodiments.

[0041] Figure 27 is a flow diagram of a method for synchronizing the r-TWT service periods of a STA and a relay STA, according to some embodiments.

[0042] Figure 28 is a flow diagram of a method for updating a membership of a r-TWT service period, according to some embodiments.

[0043] Figure 29 is a flow diagram of a method for requesting membership of a r-TWT service period, according to some embodiments.

[0044] Figure 30 is a flow diagram of a method for scheduling a r-TWT service period and updating membership of the r-TWT service period, according to some embodiments.DETAILED DESCRIPTION

[0045] The present disclosure generally relates to wireless communications, and more specifically, relates to synchronizing restricted target wake time (r-TWT) service periods of a station (STA) and a relay STA (rSTA) that is to relay traffic between the STA and an access point (AP).

[0046] The present disclosure introduces a way to integrate r-TWT technology and relay technology in a wireless network to improve wireless network performance and efficiency.

[0047] With relay technology, a relay STA may relay traffic on behalf of one or more non-AP STAs that are said to be associated with the relay STA. An important consideration when integrating r-TWT technology and relay technology in a wireless network is to ensure that the relay STA remains awake when there is traffic (e.g., high-priority stream classification service (SCS) traffic) to relay from its associated STAs To ensure this, it is important for the relay STA and its associated STAs to synchronize their r-TWT service periods such that the relay STA is awake (not in a sleep state) whenever its associated STAs have traffic to transmit / receive.

[0048] The present disclosure introduces techniques for synchronizing r-TWT service periods of a relay STA and its associated STAs.

[0049] According to some embodiments, after a (non-AP) STA establishes a relay link with a relay STA, the STA may transmit a first TWT setup request frame to the relay STA over the relay link to schedule a r-TWT service period with an AP. Responsive to receiving the first TWT setup request frame from the STA, the relay STA may transmit a second TWT setup request frame to the AP to schedule a r-TWT service period with the AP, wherein the second TWT setup request frame includes a request for the STA and the relay STA to be members of asame r-TWT service period. Responsive to receiving the second TWT setup request frame from the relay STA, the AP may schedule the r-TWT service period with both the STA and the relay STA being members of the same r-TWT service period. The AP may then transmit a first TWT setup response frame to the relay STA indicating that the scheduling of the r-TWT service period was successful. The STA may determine that the scheduling of the r-TWT service period was successful based on receiving the first TWT setup response frame from the AP. The relay STA may transmit a second TWT setup response frame to the STA (e g., over the relay link) indicating that the scheduling of the r-TWT service period was successful. The STA may determine that the scheduling of the r-TWT service period was successful based on receiving the second TWT setup response frame from the relay STA. Responsive to determining that the scheduling of the r-TWT service period was successful, the STA may wake up immediately before the r-TWT service period and transmit traffic to the AP and / or receive traffic from the AP via the relay STA during the r-TWT service period. Also, responsive to determining that the scheduling of the r-TWT service period was successful, the relay STA may wake up immediately before the r-TWT service period and relay traffic between the STA and the AP during the r-TWT service period.

[0050] For purposes of illustration, various embodiments are described herein in the context of wireless networks that are based on IEEE 802 11 standards and using terminology and concepts thereof. Those skilled in the art will appreciate that the embodiments disclosed herein can be modified / adapted for use in other types of wireless networks.

[0051] In the following detailed description, only certain embodiments of the present invention have been shown and described, simply by way of illustration. As those skilled in the art would realize, the described embodiments may be modified in different ways, all without departing from the spirit or scope of the present invention. Accordingly, the drawings and description are to be regarded as illustrative in nature and not restrictive. Like reference numerals designate like elements throughout the specification.

[0052] Figure 1 shows a wireless local area network (WLAN) 100 with a basic service set (BSS) 102 that includes a plurality of wireless devices 104 (sometimes referred to as WLAN devices 104). Each of the wireless devices 104 may include a medium access control (MAC) layer and a physical (PHY) layer according to an IEEE (Institute of Electrical and Electronics Engineers) standard 802.11, including one or more of the amendments(e.g., 802.1 la / b / g / n / p / ac / ax / bd / be). In one embodiment, the MAC layer of a wireless device 104 may initiate transmission of a frame to another wireless device 104 by passing a PHY- TXSTART. request (TXVECTOR) to the PHY layer. The TXVECTOR provides parameters forgenerating and / or transmitting a corresponding frame. Similarly, a PHY layer of a receiving wireless device may generate an RXVECTOR, which includes parameters of a received frame and is passed to a MAC layer for processing.

[0053] The plurality of wireless devices 104 may include a wireless device 104A that is an access point (sometimes referred to as an AP station or AP STA) and the other wireless devices 104B1-104B4 that are non-AP stations (sometimes referred to as non-AP STAs) Alternatively, all the plurality of wireless devices 104 may be non-AP STAs in an ad-hoc networking environment. In general, the AP STA (e.g., wireless device 104 A) and the non-AP STAs (e g , wireless devices 104B1-104B4) may be collectively referred to as STAs However, for ease of description, only the non-AP STAs may be referred to as STAs unless the context indicates otherwise. Although shown with four non-AP STAs (e.g , the wireless devices 104B1- 104B4), the WLAN 100 may include any number of non-AP STAs (e.g., one or more wireless devices 104B).

[0054] Figure 2 illustrates a schematic block diagram of a wireless device 104, according to an embodiment. The wireless device 104 may be the wireless device 104A (i.e., the AP of the WLAN 100) or any of the wireless devices 104B1-104B4 in Figure 1 . The wireless device 104 includes a baseband processor 210, a radio frequency (RF) transceiver 240, an antenna unit 250, a storage device (e g , memory device) 232, one or more input interfaces 234, and one or more output interfaces 236. The baseband processor 210, the storage device 232, the input interfaces 234, the output interfaces 236, and the RF transceiver 240 may communicate with each other via a bus 260.

[0055] The baseband processor 210 performs baseband signal processing and includes a MAC processor 212 and a PHY processor 222. The baseband processor 210 may utilize the memory 232, which may include a non-transitory computer / machine readable medium having software (e.g., computer / machine programing instructions) and data stored therein.

[0056] In an embodiment, the MAC processor 212 includes a MAC software processing unit 214 and a MAC hardware processing unit 216 The MAC software processing unit 214 may implement a first plurality of functions of the MAC layer by executing MAC software, which may be included in the software stored in the storage device 232. The MAC hardware processing unit 216 may implement a second plurality of functions of the MAC layer in specialpurpose hardware. However, the MAC processor 212 is not limited thereto. For example, the MAC processor 212 may be configured to perform the first and second plurality of functions entirely in software or entirely in hardware according to an implementation.

[0057] The PHY processor 222 includes a transmitting (TX) signal processing unit (SPU) 224 and a receiving (RX) SPU 226. The PHY processor 222 implements a plurality of functions of the PHY layer. These functions may be performed in software, hardware, or a combination thereof according to an implementation.

[0058] Functions performed by the transmitting SPU 224 may include one or more of Forward Error Correction (FEC) encoding, stream parsing into one or more spatial streams, diversity encoding of the spatial streams into a plurality of space-time streams, spatial mapping of the space-time streams to transmit chains, inverse Fourier Transform (iFT) computation, Cyclic Prefix (CP) insertion to create a Guard Interval (GI), and the like Functions performed by the receiving SPU 226 may include inverses of the functions performed by the transmitting SPU 224, such as GI removal, Fourier Transform computation, and the like.

[0059] The RF transceiver 240 includes an RF transmitter 242 and an RF receiver 244. The RF transceiver 240 is configured to transmit first information received from the baseband processor 210 to the WLAN 100 (e.g., to another WLAN device 104 of the WLAN 100) and provide second information received from the WLAN 100 (e.g., from another WLAN device 104 of the WLAN 100) to the baseband processor 210.

[0060] The antenna unit 250 includes one or more antennas. When Multiple-Input Multiple- Output (MIMO) or Multi-User MIMO (MU-MIMO) is used, the antenna unit 250 may include a plurality of antennas. In an embodiment, the antennas in the antenna unit 250 may operate as a beam-formed antenna array. In an embodiment, the antennas in the antenna unit 250 may be directional antennas, which may be fixed or steerable.

[0061] The input interfaces 234 receive information from a user, and the output interfaces 236 output information to the user. The input interfaces 234 may include one or more of a keyboard, keypad, mouse, touchscreen, microphone, and the like. The output interfaces 236 may include one or more of a display device, touch screen, speaker, and the like.

[0062] As described herein, many functions of the WLAN device 104 may be implemented in either hardware or software. Which functions are implemented in software and which functions are implemented in hardware will vary according to constraints imposed on a design. The constraints may include one or more of design cost, manufacturing cost, time to market, power consumption, available semiconductor technology, etc.

[0063] As described herein, a wide variety of electronic devices, circuits, firmware, software, and combinations thereof may be used to implement the functions of the components of the WLAN device 104. Furthermore, the WLAN device 104 may include other components, suchas application processors, storage interfaces, clock generator circuits, power supply circuits, and the like, which have been omitted in the interest of brevity.

[0064] Figure 3A illustrates components of a WLAN device 104 configured to transmit data according to an embodiment, including a transmitting (Tx) SPU (TxSP) 324, an RF transmitter 342, and an antenna 352. In an embodiment, the TxSP 324, the RF transmitter 342, and the antenna 352 correspond to the transmitting SPU 224, the RF transmitter 242, and an antenna of the antenna unit 250 of Figure 2, respectively.

[0065] The TxSP 324 includes an encoder 300, an interleaver 302, a mapper 304, an inverse Fourier transformer (IFT) 306, and a guard interval (GI) inserter 308

[0066] The encoder 300 receives and encodes input data. In an embodiment, the encoder 300 includes a forward error correction (FEC) encoder. The FEC encoder may include a binary convolution code (BCC) encoder followed by a puncturing device. The FEC encoder may include a low-density parity-check (LDPC) encoder.

[0067] The TxSP 324 may further include a scrambler for scrambling the input data before the encoding is performed by the encoder 300 to reduce the probability of long sequences of 0s or Is. When the encoder 300 performs the BCC encoding, the TxSP 324 may further include an encoder parser for demultiplexing the scrambled bits among a plurality of BCC encoders. If LDPC encoding is used in the encoder, the TxSP 324 may not use the encoder parser

[0068] The interleaver 302 interleaves the bits of each stream output from the encoder 300 to change an order of bits therein. The interleaver 302 may apply the interleaving only when the encoder 300 performs BCC encoding and otherwise may output the stream output from the encoder 300 without changing the order of the bits therein.

[0069] The mapper 304 maps the sequence of bits output from the interleaver 302 to constellation points. If the encoder 300 performed LDPC encoding, the mapper 304 may also perform LDPC tone mapping in addition to constellation mapping.

[0070] When the TxSP 324 performs a MIMO or MU-MIMO transmission, the TxSP 324 may include a plurality of interleavers 302 and a plurality of mappers 304 according to a number of spatial streams (NSS) of the transmission. The TxSP 324 may further include a stream parser for dividing the output of the encoder 300 into blocks and may respectively send the blocks to different interleavers 302 or mappers 304. The TxSP 324 may further include a space-time block code (STBC) encoder for spreading the constellation points from the spatial streams into a number of space-time streams (NSTS) and a spatial mapper for mapping the space-time streams to transmit chains. The spatial mapper may use direct mapping, spatial expansion, or beamforming.

[0071] The IFT 306 converts a block of the constellation points output from the mapper 304 (or, when MIMO or MU-MIMO is performed, the spatial mapper) to a time domain block (i.e., a symbol) by using an inverse discrete Fourier transform (IDFT) or an inverse fast Fourier transform (IFFT). If the STBC encoder and the spatial mapper are used, the IFT 306 may be provided for each transmit chain.

[0072] When the TxSP 324 performs a MIMO or MU-MIMO transmission, the TxSP 324 may insert cyclic shift diversities (CSDs) to prevent unintentional beamforming. The TxSP 324 may perform the insertion of the CSD before or after the IFT 306. The CSD may be specified per transmit chain or may be specified per space-time stream Alternatively, the CSD may be applied as a part of the spatial mapper.

[0073] When the TxSP 324 performs a MIMO or MU-MIMO transmission, some blocks before the spatial mapper may be provided for each user.

[0074] The GI inserter 308 prepends a GI to each symbol produced by the IFT 306. Each GI may include a Cyclic Prefix (CP) corresponding to a repeated portion of the end of the symbol that the GI precedes. The TxSP 324 may optionally perform windowing to smooth edges of each symbol after inserting the GI.

[0075] The RF transmitter 342 converts the symbols into an RF signal and transmits the RF signal via the antenna 352 When the TxSP 324 performs a MIMO or MU-MIMO transmission, the GI inserter 308 and the RF transmitter 342 may be provided for each transmit chain.

[0076] Figure 3B illustrates components of a WLAN device 104 configured to receive data according to an embodiment, including a Receiver (Rx) SPU (RxSP) 326, an RF receiver 344, and an antenna 354. In an embodiment, the RxSP 326, RF receiver 344, and antenna 354 may correspond to the receiving SPU 226, the RF receiver 244, and an antenna of the antenna unit 250 of Figure 2, respectively.

[0077] The RxSP 326 includes a GI remover 318, a Fourier transformer (FT) 316, a demapper 314, a deinterleaver 312, and a decoder 310.

[0078] The RF receiver 344 receives an RF signal via the antenna 354 and converts the RF signal into symbols. The GI remover 318 removes the GI from each of the symbols. When the received transmission is a MIMO or MU-MIMO transmission, the RF receiver 344 and the GI remover 318 may be provided for each receive chain.

[0079] The FT 316 converts each symbol (that is, each time domain block) into a frequency domain block of constellation points by using a discrete Fourier transform (DFT) or a fast Fourier transform (FFT). The FT 316 may be provided for each receive chain.

[0080] When the received transmission is the MIMO or MU-MIMO transmission, the RxSP 326 may include a spatial demapper for converting the respective outputs of the FTs 316 of the receiver chains to constellation points of a plurality of space-time streams, and an STBC decoder for despreading the constellation points from the space-time streams into one or more spatial streams.

[0081] The demapper 314 demaps the constellation points output from the FT 316 or the STBC decoder to bit streams. If the received transmission was encoded using LDPC encoding, the demapper 314 may further perform LDPC tone demapping before performing the constellation demapping

[0082] The deinterleaver 312 deinterleaves the bits of each stream output from the demapper 314. The deinterleaver 312 may perform the deinterleaving only when the received transmission was encoded using BCC encoding, and otherwise may output the stream output by the demapper 314 without performing deinterleaving.

[0083] When the received transmission is the MIMO or MU-MIMO transmission, the RxSP 326 may use a plurality of demappers 314 and a plurality of deinterleavers 312 corresponding to the number of spatial streams of the transmission. In this case, the RxSP 326 may further include a stream deparser for combining the streams output from the deinterleavers 312

[0084] The decoder 310 decodes the streams output from the deinterleaver 312 or the stream deparser. In an embodiment, the decoder 310 includes an FEC decoder. The FEC decoder may include a BCC decoder or an LDPC decoder.

[0085] The RxSP 326 may further include a descrambler for descrambling the decoded data. When the decoder 310 performs BCC decoding, the RxSP 326 may further include an encoder deparser for multiplexing the data decoded by a plurality of BCC decoders. When the decoder 310 performs the LDPC decoding, the RxSP 326 may not use the encoder deparser.

[0086] Before making a transmission, wireless devices such as wireless device 104 will assess the availability of the wireless medium using Clear Channel Assessment (CCA). If the medium is occupied, CCA may determine that it is busy, while if the medium is available, CCA determines that it is idle.

[0087] The PHY entity for IEEE 802.11 is based on Orthogonal Frequency Division Multiplexing (OFDM) or Orthogonal Frequency Division Multiple Access (OFDMA). In either OFDM or OFDMA Physical (PHY) layers, a STA (e.g., a wireless device 104) is capable of transmitting and receiving Physical Layer (PHY) Protocol Data Units (PPDUs) (also referred to as PLCP (Physical Layer Convergence Procedure) Protocol Data Units) that are compliant withthe mandatory PHY specifications. A PHY specification defines a set of Modulation and Coding Schemes (MCS) and a maximum number of spatial streams. Some PHY entities define downlink (DL) and uplink (UL) Multi-User (MU) transmissions having a maximum number of space-time streams (STS) per user and employing up to a predetermined total number of STSs. A PHY entity may provide support for 10 Megahertz (MHz), 20 MHz, 40 MHz, 80 MHz, 160 MHz, 240 MHz, and 320 MHz contiguous channel widths and support for an 80+80, 80+160 MHz, and 160+160 MHz non-contiguous channel width. Each channel includes a plurality of subcarriers, which may also be referred to as tones. A PHY entity may define signaling fields denoted as Legacy Signal (L-SIG), Signal A (SIG- A), and Signal B (SIG-B), and the like within a PPDU by which some necessary information about PHY Service Data Unit (PSDU) attributes are communicated. The descriptions below, for sake of completeness and brevity, refer to OFDM-based 802.11 technology. Unless otherwise indicated, a station refers to a non-AP STA.

[0088] Figure 4 illustrates Inter-Frame Space (IFS) relationships. In particular, Figure 4 illustrates a Short IFS (SIFS), a Point Coordination Function (PCF) IFS (PIFS), a Distributed Coordination Function (DCF) IFS (DIFS), and an Arbitration IFSs corresponding to an Access Category (AC) ‘i’ (AIFS[i]). Figure 4 also illustrates a slot time and a data frame is used for transmission of data forwarded to a higher layer. As shown, a WLAN device 104 transmits the data frame after performing backoff if a DIFS has elapsed during which the medium has been idle.

[0089] A management frame may be used for exchanging management information, which is not forwarded to the higher layer. Subtype frames of the management frame include a beacon frame, an association request / response frame, a probe request / response frame, and an authentication request / response frame.

[0090] A control frame may be used for controlling access to the medium. Subtype frames of the control frame include a request to send (RTS) frame, a clear to send (CTS) frame, and an acknowledgement (ACK) frame.

[0091] When the control frame is not a response frame of another frame, the WLAN device 104 transmits the control frame after performing backoff if a DIFS has elapsed during which the medium has been idle. When the control frame is the response frame of another frame, the WLAN device 104 transmits the control frame after a SIFS has elapsed without performing backoff or checking whether the medium is idle.

[0092] A WLAN device 104 that supports Quality of Service (QoS) functionality (that is, a QoS STA) may transmit the frame after performing backoff if an AIFS for an associated access category (AC) (i.e., AIFS [AC]) has elapsed. When transmitted by the QoS STA, any of the dataframe, the management frame, and the control frame, which is not the response frame, may use the AIFS[AC] of the AC of the transmitted frame.

[0093] A WLAN device 104 may perform a backoff procedure when the WLAN device 104 that is ready to transfer a frame finds the medium busy. The backoff procedure includes determining a random backoff time composed of N backoff slots, where each backoff slot has a duration equal to a slot time and N being an integer number greater than or equal to zero. The backoff time may be determined according to a length of a Contention Window (CW). In an embodiment, the backoff time may be determined according to an AC of the frame. All backoff slots occur following a DIFS or Extended IFS (EIFS) period during which the medium is determined to be idle for the duration of the period.

[0094] When the WLAN device 104 detects no medium activity for the duration of a particular backoff slot, the backoff procedure shall decrement the backoff time by the slot time. When the WLAN device 104 determines that the medium is busy during a backoff slot, the backoff procedure is suspended until the medium is again determined to be idle for the duration of a DIFS or EIFS period. The WLAN device 104 may perform transmission or retransmission of the frame when the backoff timer reaches zero.

[0095] The backoff procedure operates so that when multiple WLAN devices 104 are deferring and execute the backoff procedure, each WLAN device 104 may select a backoff time using a random function and the WLAN device 104 that selects the smallest backoff time may win the contention, reducing the probability of a collision.

[0096] Figure 5 illustrates a Carrier Sense Multiple Access / Collision Avoidance (CSMA / CA) based frame transmission procedure for avoiding collision between frames in a channel according to an embodiment. Figure 5 shows a first station STA1 transmitting data, a second station STA2 receiving the data, and a third station STA3 that may be located in an area where a frame transmitted from the STA1 can be received, a frame transmitted from the second station STA2 can be received, or both can be received The stations STA1, STA2, and STA3 may be WLAN devices 104 of Figure 1.

[0097] The station STA1 may determine whether the channel is busy by carrier sensing. The station STA1 may determine channel occupation / status based on an energy level in the channel or an autocorrelation of signals in the channel, or may determine the channel occupation by using a network allocation vector (NAV) timer.

[0098] After determining that the channel is not used by other devices (that is, that the channel is IDLE) during a DIFS (and performing backoff if required), the station STA1 may transmit a Request-To-Send (RTS) frame to the station STA2. Upon receiving the RTS frame, after a SIFSthe station STA2 may transmit a Clear-To-Send (CTS) frame as a response to the RTS frame. If Dual-CTS is enabled and the station STA2 is an AP, the AP may send two CTS frames in response to the RTS frame (e g., a first CTS frame in a non-High Throughput format and a second CTS frame in the HT format).

[0099] When the station ST A3 receives the RTS frame, it may set a NAV timer of the station STA3 for a transmission duration of subsequently transmitted frames (for example, a duration of SIFS + CTS frame duration + SIFS + data frame duration + SIFS + ACK frame duration) using duration information included in the RTS frame. When the station STA3 receives the CTS frame, it may set the NAV timer of the station ST A3 for a transmission duration of subsequently transmitted frames using duration information included in the CTS frame. Upon receiving a new frame before the NAV timer expires, the station STA3 may update the NAV timer of the station STA3 by using duration information included in the new frame. The station STA3 does not attempt to access the channel until the NAV timer expires.

[0100] When the station STA1 receives the CTS frame from the station STA2, it may transmit a data frame to the station STA2 after a SIFS period elapses from a time when the CTS frame has been completely received. Upon successfully receiving the data frame, the station STA2 may transmit an ACK frame as a response to the data frame after a SIFS period elapses.

[0101] When the NAV timer expires, the third station STA3 may determine whether the channel is busy using the carrier sensing. Upon determining that the channel is not used by other devices during a DIFS period after the NAV timer has expired, the station STA3 may attempt to access the channel after a contention window elapses according to a backoff process.

[0102] When Dual-CTS is enabled, a station that has obtained a transmission opportunity (TXOP) and that has no data to transmit may transmit a CF-End frame to cut short the TXOP. An AP receiving a CF-End frame having a Basic Service Set Identifier (BSSID) of the AP as a destination address may respond by transmitting two more CF-End frames: a first CF-End frame using Space Time Block Coding (STBC) and a second CF-End frame using non-STBC. A station receiving a CF-End frame resets its NAV timer to 0 at the end of the PPDU containing the CF-End frame. Figure 5 shows the station STA2 transmitting an ACK frame to acknowledge the successful reception of a frame by the recipient.

[0103] The IEEE 802 1 Ibn (Ultra High Reliability, UHR) working group has been established to address the growing demand for higher peak throughput and reliability in Wi-Fi. As shown in Figure 6, the peak PHY rate has significantly increased from IEEE 802.1 lb to IEEE 802. 1 Ibe (Wi-Fi 7), with the latter focusing on further improving peak throughput. The UHR study group aims to enhance the tail of the latency distribution and jitter to supportapplications that require low latency, such as video-over- WLAN, gaming, AR, and VR. It is noted that various characteristics of UHR (e.g., max PHY rate, PHY rate enhancement, bandwidth / number of spatial streams, and operating bands) are still to be determined

[0104] The focus of IEEE 802.1 Ibe is primarily on WLAN indoor and outdoor operation with stationary and pedestrian speeds in the 2.4, 5, and 6 GHz frequency bands. In addition to peak PHY rate, different candidate features are under discussion. These candidate features include (1) a 320MHz bandwidth and a more efficient utilization of a non-contiguous spectrum, (2) multi-band / multi-channel aggregation and operation, (3) 16 spatial streams and Multiple Input Multiple Output (MIMO) protocol enhancements, (4) multi-Access Point (AP) Coordination (e g., coordinated and joint transmission), (5) an enhanced link adaptation and retransmission protocol (e.g., Hybrid Automatic Repeat Request (HARQ)), and (6) adaptation to regulatory rules specific to a 6 GHz spectrum.

[0105] The focus of IEEE 802.1 Ibn (UHR) is still under discussion, with candidate features including MLO enhancements (e.g., in terms of increased throughput / reliability and decreased latency), latency and reliability improvements (e.g., multi-AP coordination to support low latency traffic), bandwidth expansion (e.g., to 240, 480, 640 MHz), aggregated PPDU (A- PPDU), enhanced multi-link single-radio (eMLSR) extensions to AP, roaming improvements, and power-saving schemes for prolonging battery life

[0106] Some features, such as increasing the bandwidth and the number of spatial streams, are solutions that have been proven to be effective in previous projects focused on increasing link throughput and on which feasibility demonstration is achievable.

[0107] With respect to operational bands (e.g., 2.475 / 6 GHz) for IEEE 802. 1 Ibe, more than 1 GHz of additional unlicensed spectrum is likely to be available because the 6 GHz band (5.925- 7.125 GHz) is being considered for unlicensed use. This would allow / VPs and STAs to become tri -band devices. Larger than 160MHz data transmissions (e.g., 320 MHz or 640 MHz) could be considered to increase the maximum PHY rate. For example, 320 MHz or 160+160MHz data could be transmitted in the 6 GHz band. For example, 160+160 MHz data could be transmitted across the 5 and 6 GHz bands.

[0108] In the process of wireless communication, a transmitting station (STA) creates a Physical Layer Protocol Data Unit (PPDU) frame and sends it to a receiving STA. The receiving STA then receives, detects, and processes the PPDU.

[0109] The Extremely High Throughput (EHT) PPDU frame encompasses several components. It includes a legacy part, which comprises fields such as the Legacy Short Training Field (L-STF), Legacy Long Training Field (L-LTF), Legacy Signal Field (L-SIG), andRepeated Legacy Signal Field (RL-SIG). These fields are used to maintain compatibility with older Wi-Fi standards.

[0110] In addition to the legacy part, the EHT PPDU frame also contains the Universal Signal Field (U-SIG), EHT Signal Field (EHT-SIG), EHT Short Training Field (EHT-STF), and EHT Long Training Field (EHT-LTF). These fields are specific to the EHT standard and are used for various purposes, such as signaling, synchronization, and channel estimation.

[0111] Figure 7 provides a more detailed description of each field in the EHT PPDU frame, including their purposes and characteristics.

[0112] Regarding the Ultra High Reliability (UHR) PPDU, its frame structure is currently undefined and will be determined through further discussions within the relevant working group or study group. This indicates that the specifics of the UHR PPDU are still under development and will be finalized based on the outcomes of future deliberations

[0113] The distributed nature of channel access networks, such as IEEE 802. 11 WLANs, makes the carrier sense mechanism useful for ensuring collision-free operation. Each station (STA) uses its physical carrier sense to detect transmissions from other STAs. However, in certain situations, it may not be possible for a STA to detect every transmission. For instance, when one STA is located far away from another STA, it might perceive the medium as idle and start transmitting a frame, leading to collisions To mitigate this hidden node problem, the network allocation vector (NAV) has been introduced.

[0114] As the IEEE 802.11 standard continues to evolve, it now includes scenarios where multiple users can simultaneously transmit or receive data within a basic service set (BSS), such as uplink (UL) and downlink (DL) multi-user (MU) transmissions in a cascaded manner. In these cases, the existing carrier sense and NAV mechanisms may not be sufficient, and modifications or newly defined mechanisms may be required to facilitate efficient and collision- free operation.

[0115] For the purpose of this disclosure, MU transmission refers to situations where multiple frames are transmitted to or from multiple STAs simultaneously using different resources. Examples of these resources include different frequency resources in Orthogonal Frequency Division Multiple Access (OFDMA) transmission and different spatial streams in Multi-User Multiple Input Multiple Output (MU-MIMO) transmission. Consequently, downlink OFDMA (DL-OFDMA), downlink MU-MIMO (DL-MU-MIMO), uplink OFDMA (UL- OFDMA), uplink MU-MIMO (UL-MU-MIMO), and OFDMA with MU-MIMO are all considered examples of MU transmission.

[0116] Figure 8 illustrates an example of multi-user (MU) transmission in Orthogonal Frequency -Division Multiple Access (OFDMA), in accordance with some embodiments of the present disclosure.

[0117] In the IEEE 802.11 ax and 802. 1 Ibe specifications, the trigger frame plays a useful role in facilitating uplink multi-user (MU) transmissions. The purpose of the trigger frame is to allocate resources and solicit one or more Trigger-based (TB) Physical Layer Protocol Data Unit (PPDU) transmissions from the associated stations (STAs).

[0118] The trigger frame contains information required by the responding STAs to send their Uplink TB PPDUs This information includes the Trigger type, which specifies the type of TB PPDU expected, and the Uplink Length (UL Length), which indicates the duration of the uplink transmission.

[0119] Figure 9 illustrates an example scenario where an access point (AP) operating in an 80MHz bandwidth environment sends a Trigger frame to multiple associated STAs. Upon receiving the Trigger frame, the STAs respond by sending their respective Uplink Orthogonal Frequency Division Multiple Access (UL OFDMA) TB PPDUs, utilizing the allocated resources within the specified 80 MHz bandwidth.

[0120] After successfully receiving the UL OFDMA TB PPDUs, the AP acknowledges the STAs by sending an acknowledgement frame This acknowledgement can be in the form of an 80MHz width multi-STA Block Acknowledgement (Block Ack) or a Block Acknowledgement with a Direct Feedback (DF) OFDMA method. The multi-STA Block Ack allows the AP to acknowledge multiple STAs simultaneously, while the Block Ack with DF OFDMA enables the AP to provide feedback to the STAs using the same OFDMA technique employed in the uplink transmission.

[0121] The trigger frame is a useful component in enabling efficient uplink MU transmissions in IEEE 802.1 lax and 802. 1 Ibe networks, by allocating resources and coordinating the uplink transmissions from multiple STAs within the same bandwidth.

[0122] Wireless network systems can rely on retransmission of media access control (MAC) protocol data units (MPDUs) when the transmitter (TX) does not receive an acknowledgement from the receiver (RX) or MPDUs are not successfully decoded by the receiver. Using an automatic repeat request (ARQ) approach, the receiver discards the last failed MPDU before receiving the newly retransmitted MPDU. With requirements of enhanced reliability and reduced latency, the wireless network system can evolve toward a hybrid ARQ (HARQ) approach.

[0123] There are two methods of HARQ processing. In a first type of HARQ scheme, also referred to as chase combining (CC) HARQ (CC-HARQ) scheme, signals to be retransmitted are the same as the signals that previously failed because all subpackets to be retransmitted use the same puncturing pattern. The puncturing is needed to remove some of the parity bits after encoding using an error-correction code. The reason why the same puncturing pattern is used with CC-HARQ is to generate a coded data sequence with forward error correction (FEC) and to make the receiver use a maximum-ratio combining (MRC) to combine the received, retransmitted bits with the same bits from the previous transmission. For example, information sequences are transmitted in packets with a fixed length At a receiver, error correction and detection are carried out over the whole packet However, the ARQ scheme may be inefficient in the presence of burst errors. To solve this more efficiently, subpackets are used. In subpacket transmissions, only those subpackets that include errors need to be retransmitted.

[0124] Since the receiver uses both the current and the previously received subpackets for decoding data, the error probability in decoding decreases as the number of used subpackets increases. The decoding process passes a cyclic redundancy check (CRC) and ends when the entire packet is decoded without error or the maximum number of subpackets is reached. In particular, this scheme operates on a stop-and-wait protocol such that if the receiver can decode the packet, it sends an acknowledgement (ACK) to the transmitter When the transmitter receives an ACK successfully, it terminates the HARQ transmission of the packet. If the receiver cannot decode the packet, it sends a negative acknowledgement (NAK) to the transmitter and the transmitter performs the retransmission process.

[0125] In a second type of HARQ scheme, also referred to as an incremental redundancy (IR) HARQ (IR-HARQ) scheme, different puncturing patterns are used for each subpacket such that the signal changes for each retransmitted subpacket in comparison to the originally transmitted subpacket. IR-HARQ alternatively uses two puncturing patterns for odd numbered and even numbered transmissions, respectively. The redundancy scheme of IR-HARQ improves the log likelihood ratio (LLR) of parity bit(s) in order to combine information sent across different transmissions due to requests and lowers the code rate as the additional subpacket is used. This results in a lower error rate of the subpacket in comparison to CC-HARQ. The puncturing pattern used in IR-HARQ is indicated by a subpacket identity (SPID) indication. The SPID of the first subpacket may always be set to 0 and all the systematic bits and the punctured parity bits are transmitted in the first subpacket. Self-decoding is possible when the receiving signal- to-noise ratio (SNR) environment is good (i.e., a high SNR). In some embodiments, subpacketswith corresponding SPIDs to be transmitted are in increasing order of SPID but can be exchanged / switched except for the first SPID.

[0126] AP coordination has been considered as a potential technology to improve WLAN system throughput in the IEEE 802.1 Ibe standard and is still being discussed in the IEEE 802.1 Ibn (UHR) standard. To support various AP coordination schemes, such as coordinated beamforming, OFDMA, TDMA, spatial reuse, and joint transmission, a predefined mechanism for APs is necessary.

[0127] In the context of coordinated TDMA (C-TDMA), the AP that obtains a transmit opportunity (TXOP) is referred to as the sharing AP This AP initiates the AP coordination schemes to determine the AP candidate set by sending a frame, such as a Beacon frame or probe response frame, which includes information about the AP coordination scheme capabilities. The AP that participates in the AP coordination schemes after receiving the frame from the sharing AP is called the shared AP The sharing AP is also known as the master AP or coordinating AP, while the shared AP is referred to as the slave AP or coordinated AP.

[0128] The operation of various AP coordination schemes has been discussed in theIEEE 802.1 Ibe and UHR standards:

[0129] Coordinated Beamforming (C-BF): Multiple APs transmit on the same frequency resource by coordinating and forming spatial nulls, allowing for simultaneous transmission from multiple APs.

[0130] Coordinated OFDMA (C-OFDMA): APs transmit on orthogonal frequency resources by coordinating and splitting the spectrum, enabling more efficient spectrum utilization.

[0131] Joint Transmission (JTX): Multiple APs transmit jointly to a given user simultaneously by sharing data between the APs.

[0132] Coordinated Spatial Reuse (C-SR): Multiple APs or STAs adjust their transmit power to reduce interference between APs.

[0133] By implementing these AP coordination schemes, WLAN systems can improve their overall throughput and efficiency by leveraging the cooperation between multiple APs.

[0134] Figure 10 is a diagram showing a wireless network environment with an AP, relay STAs, and STAs that are capable of MLO in a 2.4 GHz band and a 5 GHz band, according to some embodiments.

[0135] As shown in the diagram, the wireless network environment may include an AP 1010, two relay STAs (relay STA 1020-1 and relay STA 1020-2), and five non-AP non-relay STAs (STA 1030-1, STA 1030-2, STA 1030-3, STA 1030-4, and STA 1030-5). The AP 1010, relay STAs, and STAs may be multi -link devices (MLDs) that are capable of MLO. Unliketraditional non-MLD APs and non-MLD STAs, MLD APs and STAs may have multiple wireless interfaces and may be capable of MLO in multiple channel s / bands. In this example, it is assumed that the AP 1010, relay STAs, and non-relay STAs may be capable of MLO in a first channel in the 2.4 GHz band and a second channel in the 5 GHz band. It is noted that MLDs having multiple wireless interfaces may still have a unique MAC instance at the upper layers, without losing the independent parameters of each wireless interface.

[0136] The AP 1010 may operate a basic service set (BSS) in the 2.4 GHz band and the 5 GHz band (using two wireless interfaces). In the example shown in the diagram, the AP’s 1010 coverage in the 2 4 GHz band may extend further than the AP’s 1010 coverage in the 5 GHz band (due to the 2.4 GHz band being a lower frequency band).

[0137] Various embodiments will be described herein in the context of the wireless network environment shown in Figure 10. It should be appreciated, however, that the techniques described herein may be applicable to other wireless network environments having different configurations.

[0138] Figure 11 is a diagram showing a single link operation and a multi-link operation between an AP and a non-AP STA, according to some embodiments.

[0139] As shown in the diagram, with a single link operation, an AP 1110 and a non-AP STA 1130 may communicate with each other over a single link In contrast, with a multi-link operation, an AP MLD 1150 and a non-AP STA MLD 1170 may communicate with each other over multiple links. For example, as shown in the diagram, the AP MLD 1150 may have a first instance (“API”) and a second instance (“AP2”). Similarly, the non-AP STA MLD 1170 may also have a first instance (“STA1”) and a second instance (“STA2”). The AP MLD 1150 may communicate with the non-AP STA MLD 1170 over a first link (“Linkl”) between API and STA1 and a second link (“Link2”) between AP2 and STA2.

[0140] A relay STA (rSTA) may be a non-AP STA that can relay communications between an AP and a non-AP STA. Relay operations may extend the possible communication range and provide improved QoS (e g., reliability and throughput) in a wireless network. For example, relay STA 1020-1 shown in Figure 10 may relay communications between the AP 1010 and STA 1030-2 and / or STA 1030-5. Also, relay STA 1020-2 shown in Figure 10 may relay communications between the AP 1010 and STA 1030-3 and / or STA 1030-4.

[0141] Figure 12 is a diagram showing a relay STA MLD that can relay communications between an AP MLD and a non-AP STA MLD using MLO, according to some embodiments.

[0142] When MLO is supported in a wireless network, the relay operations can also use MLO. For example, as shown in the diagram, an AP MLD 1210 may have a first instance(“API”) and a second instance (“AP2”), a relay STA MLD 1220 may have a first instance (“rSTAl”) and a second instance (“rSTA2”), and the non-AP STA MLD 1230 may have a first instance (“STA1”) and a second instance (“STA2”). API and rSTAl may communicate with each other over a link (“Linkl-1”) that operates in a first channel (e.g., a channel in the 2.4 GHz band) rSTAl and STA1 may communicate with each other over a link (“Linkl-2”) that operates in the first channel. AP2 and rSTA2 may communicate with each other over a link (“Link2-1”) that operates in a second channel (e.g., a channel in the 5 GHz band) that is different from the first channel. rSTA2 and STA2 may communicate with each other over a link (“Link2-2”) that operates in the second channel API and ST Al may communicate with each other in the first channel via rSTAl. For example, downlink traffic going from API to STA1 may be transmitted in the first channel over Linkl-1 and Linkl-2 (in that order) and uplink traffic going from STA1 to API may be transmitted in the first channel over Linkl-2 and Linkl- 1 (in that order). Similarly, AP2 and STA2 may communicate with each other in the second channel via rSTA2. For example, downlink traffic going from AP2 to STA2 may be transmitted in the second channel over Link2-1 and Link2-2 (in that order) and uplink traffic going from STA2 to AP2 may be transmitted in the second channel over Link2-2 and Link2-1 (in that order). In this way, the AP MLD 1210 may be able to communicate with the non-AP STA MLD 1230 via the relay STA MLD 1220 (using relay operations) in two different channels over two different sets of links.

[0143] The types of relay operation that are supported for a STA MLD may vary depending on the particular situation, configuration, and / or environment. The types of relay operation that are supported may be classified into MLO relay supportability types.

[0144] Figure 13 is a diagram showing a table of MLO relay supportability types, according to some embodiments.

[0145] As shown in the table, MLO relay supportability may be classified into five MLO relay supportability types: MLO relay supportability type #0, MLO relay supportability type #1, MLO relay supportability type #2, MLO relay supportability type #3, and MLO relay supportability type #4. The MLO relay supportability type for a STA may depend on the link status of the links between the STA and an AP. In an embodiment, three bits are used to indicate the MLO relay supportability type. For example, MLO relay supportability type #0 may correspond to binary “000,” MLO relay supportability type #1 may correspond to binary “001,” MLO relay supportability type #2 may correspond to binary “010,” MLO relay supportability type #3 may correspond to binary “011,” and MLO relay supportability type #4 may correspond to binary “100.”

[0146] As shown in the table, with MLO relay supportability type #0, the non-AP STA and the AP are within one-hop communication range and relay operations are disabled. The non-AP STA and the AP may communicate with each other directly and relay operations may be disabled. For example, in the wireless network environment shown in Figure 10, STA 1030-1 and the AP 1010 may communicate with each other directly (without using relay operations). As used herein, “direct” communication or similar language refers to communication that does not involve relay operations.

[0147] With MLO relay supportability type #1, the non-AP STA and the AP are within one- hop communication range and a relay STA can relay traffic between the non-AP STA and the AP (e g., to boost end-to-end throughput). The non-AP STA and the AP may communicate with each other directly and / or communicate with each other using relay operations. For example, in the wireless network environment shown in Figure 10, STA 1030-2 and the AP 1010 may communicate with each other directly (without using relay operations) and also communicate with each other via relay STA 1020-1 (using relay operations).

[0148] With MLO relay supportability type #2, the non-AP STA is able to receive beacon and downlink traffic from the AP (so the non-AP STA is shown as being “connected” to the AP) but the non-AP STA is not able to deliver uplink traffic to the AP due to a downlink / uplink power asymmetry (e g , because the AP has higher transmit power than the non-AP STA) or other reason. A relay STA may be able to relay uplink traffic from the non-AP STA to the AP to address the asymmetry. For example, in the wireless network environment shown in Figure 10, the AP 1010 may communicate to STA 1030-3 directly (in the downlink direction) and STA 1030-3 may communicate to the AP 1010 (in the uplink direction) via relay STA 1020- 2 (using relay operations).

[0149] With MLO relay supportability type #3, the non-AP STA and the AP are within one- hop communication range in one band (e.g., 2.4 GHz band) but are not within one-hop communication range in another band (e g., 5 GHz band). The non-AP STA and the AP may communicate with each other directly in one band (e g., 2.4 GHz band) and communicate with each other in the other band (e.g., 5 GHz band) using relay operations. For example, in the wireless network environment shown in Figure 10, the AP 1010 and STA 1030-4 may communicate with each other directly (without using relay operations) in the 2.4 GHz band and communicate with each other via relay STA 1020-2 in the 5 GHz band.

[0150] With MLO relay supportability type #4, the non-AP STA and the AP are not within one-hop communication range but a relay STA can relay traffic between the non-AP STA and the AP to extend coverage and enable communication. The non-AP STA and the AP may not beable to communicate with each other directly but may be able to communicate with each other using relay operations. For example, in the wireless network environment shown in Figure 10, STA 1030-5 and the AP 1010 may communicate with each other via relay STA 1020-1 in both the 2.4 GHz band and the 5 GHz band.

[0151] Figure 14 is a diagram showing a table summarizing the types of communications available for each MLO relay supportability type, according to some embodiments

[0152] As shown in the table, for MLO relay supportability type #0 (“000”), direct downlink communication is available, relayed downlink communication is unavailable, direct uplink communication is available, and relayed uplink communication is unavailable For MLO relay supportability type #1 (“001”), direct downlink communication is available, relayed downlink communication is available, direct uplink communication is available, and relayed uplink communication is available. For MLO relay supportability type #2 (“010”), direct downlink communication is available, relayed downlink communication is available, direct uplink communication is unavailable (at least in one channel / band), and relayed uplink communication is available. For MLO relay supportability type #3 (“011”), direct downlink communication is available in one channel / band but not available in another channel / band, relayed downlink communication is available, direct uplink communication is available in one channel / band but not available in another channel / band, and relayed uplink communication is available For MLO relay supportability type #4 (“100”), direct downlink communication is unavailable, relayed downlink communication is available, direct uplink communication is unavailable, and relayed uplink communication is available.

[0153] The various MLO relay supportability types will now be described in additional detail herein.

[0154] Figure 15 is a diagram showing MLO relay supportability type #1 (“001”), according to some embodiments.

[0155] As shown in the diagram, an AP 1510, a relay STA 1520, and a non-AP STA 1530 may be MLDs that each have two instances. For example, the AP 1510 may have instances “API” and “AP2,” the relay STA 1520 may have instances “rSTAl” and “rSTA2,” and the non- AP STA 1530 may have instances “STA1” and “STA2.” API and STA1 may communicate with each other directly in a first channel over link “Linkl.” Also, API and STA1 may communicate with each other in the first channel via rSTAl over link “Linkl-1” and link “Linkl-2.” AP2 and STA2 may communicate with each other directly in a second channel over link “Link2.” Also, AP2 and STA2 may communicate with each other in the second channel via rSTA2 over link “Link2-1” and link “Link2-2.”

[0156] Thus, the non-AP STA 1530 has the option to communicate directly with the AP 1510 (over Linkl and / or Link2) and / or communicate with the AP 1510 via the relay STA 1520 (over Linkl-1 and Linkl-2 or over Link2-1 and Link2-2). The decision of whether to communicate directly or communicate via the relay STA 1520 may be made depending on the channel conditions. For example, if the link quality of the direct links (e.g., Linkl and Link2) is sufficiently high, then the use of direct communications may be prioritized. However, if the link quality of the relay links (e.g., Linkl-1, Linkl-2, Link2-1, and Link2-2) is higher than the link quality of the direct links (e.g., the channel gain achieved through the use of relay links is above a predefined threshold), then the use of relayed communication may be prioritized Link quality may be measured using various metrics such as bit error rate (BER), signal -to-noise ratio (SNR), or the like. When the link quality of the direct links is low, the use of relay operations over the relay links may provide enhanced link quality and channel conditions, enabling the use of higher order modulation coding scheme (MCS) for transmission, which may result in improved performance. This improvement in performance may be attributed to the benefits derived from Multiple-Input Multiple-Output (MIMO) antenna gain and increased number of MIMO streams.

[0157] Figure 16 is a diagram showing MLO relay supportability type #2 (“010”), according to some embodiments.

[0158] As shown in the diagram, an AP 1610, a relay STA 1620, and a non-AP STA 1630 may be MLDs that each have two instances. For example, the AP 1610 may have instances “API” and “AP2,” the relay STA 1620 may have instances “rSTAl” and “rSTA2,” and the non- AP STA 1630 may have instances “STA1” and “STA2.” API and STA1 may communicate with each other directly in a first channel over link “Linkl.” Also, API and STA1 may communicate with each other in the first channel via rSTAl over link “Linkl-1” and link “Linkl-2.” AP2 may communicate to STA2 directly in a second channel (e.g., AP2 may deliver beacon and downlink traffic to STA2) but STA2 may not be able to communicate to AP2 directly in the second channel. Stated differently, the communications between AP2 and STA2 in the second channel may be asymmetric (e g., due to a downlink / uplink power asymmetry). However, AP2 and STA2 may communicate with each other in the second channel via rSTA2 over link “Link2-1” and link “Link2-2” to address the asymmetry, allowing bidirectional communication between the AP 1610 and the non-AP STA 1630 in the second channel.

[0159] Figure 17 is a diagram showing MLO relay supportability type #3 (“011”), according to some embodiments.

[0160] As shown in the diagram, an AP 1710, a relay STA 1720, and a non-AP STA 1730 may be MLDs that each have two instances. For example, the AP 1710 may have instances“API” and “AP2,” the relay STA 1720 may have instances “rSTAl” and “rSTA2,” and the non- AP STA 1730 may have instances “STA1” and “STA2.” API and STA1 may communicate with each other directly in a first channel over link “Linkl ” Also, API and STA1 may communicate with each other in the first channel via rSTAl over link “Linkl-1” and link “Linkl-2.” AP2 and STA2 may not be able to communicate with each other directly in a second channel (link “Link2” is unavailable). However, AP2 and STA2 may be able to communicate with each other in the second channel via rSTA2 over link “Link2-1” and link “Link2-2 ” Stated differently, the AP 1710 and the non-AP STA 1730 may be able to communicate with each other directly in the first channel (over Linkl) but may not be able to communicate with each other directly in the second channel. However, the AP 1710 and the non-AP STA 1730 may be able to communicate with each other in the second channel via relay STA 1720. Thus, relay operations can be used to extend the coverage in the second channel to allow the AP 1710 and the non-AP STA 1730 to communicate with each other.

[0161] Figure 18 is a diagram showing MLO relay supportability type #4 (“100”), according to some embodiments.

[0162] As shown in the diagram, an AP 1810, a relay STA 1820, and a non-AP STA 1830 may be MLDs that each have two instances. For example, the AP 1810 may have instances “API” and “AP2,” the relay STA 1820 may have instances “rSTAl” and “rSTA2,” and the non- AP STA 1830 may have instances “STA1” and “STA2.” API and STA1 may not be able to communicate with each other directly in a first channel (link “Linkl” is unavailable). However, API and STA1 may be able to communicate with each other in the first channel via rSTAl over link “Linkl-1” and link “Linkl-2.” Also, AP2 and STA2 may not be able to communicate with each other directly in a second channel (link “Link2” is unavailable). However, AP2 and STA2 may be able to communicate with each other in the second channel via rSTA2 over link “Link2- 1” and link “Link2-2.” Stated differently, the AP 1810 and the non-AP STA 1830 may not be able to communicate with each other directly in the first channel (over Linkl) or the second channel (over Link2) but may be able to communicate with each other in the first channel and the second channel via the relay STA 1820. Thus, relay operations can be used to extend the coverage in the first channel and the second channel to allow the AP 1810 and the non-AP STA 1830 to communicate with each other.

[0163] A MLO relay supportability type may support any communications that can be supported by the links that are available for that MLO relay supportability type. For example, MLO relay supportability type #1 may support the relay operations supported by MLO relay supportability types #2, #3, and #4. Similarly, MLO relay supportability type #2 may supportthe relay operations supported by MLO relay supportability types #3 and #4. Similarly, MLO relay supportability type #3 may support the relay operations supported by MLO relay supportability type #4. The MLO relay supportability types #l-#4 may thus be considered as having a subset relationship in terms of the communications that can be supported (with MLO relay supportability type #1 supporting the most types of communications and MLO relay supportability type #4 supporting the least types of communications)

[0164] Figure 19 is a diagram showing a wireless network that can implement r-TWT technology and relay technology, according to some embodiments.

[0165] As shown in the diagram, the wireless network includes an AP MLD 1910, a relay STA MLD 1920, STA MLD 1930-1, STA MLD 1930-2, and STA MLD 1930-3. The AP MLD 1910 may include two AP instances operating in different channel s / bands. For example, AP MLD 1910 may include instance API operating in a first hand (e.g., 2.4 GHz band) and instance AP2 operating in a second band (e.g., 5 GHz band). Also, the relay STA MLD 1920 may include two relay STA instances operating in different channels / bands. For example, the relay STA MLD 1920 may include instance rSTAl operating in the first hand and instance rSTA2 operating in the second band. Also, each (non-AP) STA 1930 may include two STA instances operating in different channels / bands. For example, STA MLD 1930-1 may include instance STA1 operating in the first band and instance STA2 operating in the second band, STA MLD 1930-2 may include instance STA3 operating in the first band and instance STA4 operating in the second band, and STA MLD 1930-3 may include instance STA5 operating in the first band and STA6 operating in the second band.

[0166] STA MLD 1930-1 may be connected to API through multiple links. For example, STA1 of STA MLD 1930-1 may be connected to API of the AP MLD 1910 through a link operating in the first band (“Linkl”) and STA2 of STA MLD 1930-1 may be connected to AP2 of the AP MLD 1910 through a link operating in the second band (“Link2”). As used herein, Linkl may refer to a wireless link operating in the first channel / band and Link2 may refer to a wireless link operating in the second channel / band (where the second channel / band is different from the first channel / band). STA MLD 1930-2 may be directly connected to the AP MLD 1910 in the first band but connected to the AP MLD 1910 via the relay STA MLD 1920 in the second band. For example, STA3 of STA MLD 1930-2 may be connected to API of the AP MLD 1910 through Linkl and STA4 of STA MLD 1930-2 may be connected to rSTA2 of the relay STA MLD 1920 through Link2. STA MLD 1930-3 may be connected to the AP MLD 1910 through the relay STA MLD 1920 and not have a direct connection to the AP MLD 1910. For example, STA6 of STA MLD 1930-3 may be connected to rSTA2 of relay STA MLD 1920through Link2. In this example, STA MLD 1930-3 is connected to the relay STA MLD 1 20 through a single link. The relay STA MLD 1920 may be connected to the AP MLD 1910 through multiple links. For example, rSTAl of the relay STA MLD 1920 may be connected to API of the AP MLD 1 10 through Linkl and rSTA2 of the relay STA MLD 1 20 may be connected to AP2 of the AP MLD 1910 through Link2.

[0167] In the example shown in the diagram, STA MLD 1930-1 may be connected to the AP MLD 1910 over two direct links (Linkl and Link2). STA MLD 1930-1 may receive downlink (DL) traffic directly (without using relay operations) from the AP MLD 1910 over either link and may transmit uplink (UL) traffic directly to AP MLD 1910 over either link

[0168] In the example shown in the diagram, STA MLD 1930-2 may be a MLO relay supportability type #2 (010) device in that STA MLD 1930-2 may be able to receive beacon frames and / or other DL traffic from the AP MLD 1910 (over Linkl), but it may be unable to transmit uplink (UL) traffic directly to the AP MLD 1910 due to a DL / UL power asymmetry. The relay STA MLD 1920 may help resolve this DL / UL power asymmetry by relaying uplink traffic from STA MLD 1930-2 to the AP MLD 1910 (over Link2). Thus, STA MLD 1930-2 may receive DL traffic directly from API (over Linkl) and transmit UL traffic to the AP MLD 1910 via the relay STA MLD 1920 (over Link2).

[0169] In the example shown in the diagram, STA MLD 1930-3 may be a relay supportability type #4 (100) device in that all links of STA MLD 1 30-3 are beyond the one-hop range of the AP MLD 1910 (e.g., out of beacon frame transmission range), but the relay STA MLD 1920 may assist in extending the coverage of the AP MLD 1910 using MLO. For example, STA MLD 1930-3 may receive DL traffic from the AP MLD 1910 via the relay STA MLD 1920 (over Link2) and transmit UL traffic to the AP MLD 1910 via the relay STA MLD 1920 over a single link (Link2).

[0170] According to the LEEE 802. 1 Ibe wireless networking standard, a r-TWT scheduling AP is an AP that supports r-TWT operation and sets the restricted TWT support subfield in the transmitted EHT Capabilities elements to “1”. A r-TWT scheduled STA is a non-AP STA that supports r-TWT operations and sets the restricted TWT support subfield in the transmitted EHT Capabilities elements to “1”.

[0171] In the example shown in the diagram, AP MLD 1910 may be a r-TWT scheduling AP and STA MLD 1930-1, STA MLD 1930-2, STA MLD 1930-3, and relay STA MLD 1930 may be r-TWT scheduled STAs.

[0172] A r-TWT scheduled STA may establish membership in one or more r-TWT service periods scheduled by the r-TWT scheduling AP The r-TWT setup signaling (negotiation) mayfollow the same or similar procedure as broadcast TWT, but incorporate additional parameter settings for the membership negotiation of a r-TWT service period between the r-TWT scheduled STA and the r-TWT scheduling AP.

[0173] Once a r-TWT scheduled STA establishes membership in a r-TWT service period scheduled by the r-TWT scheduling AP, the r-TWT scheduled STA may be allowed to exchange frames with the r-TWT scheduling AP during the r-TWT service period with higher priority Conversely, a r-TWT scheduled STA that is not a member of the r-TWT service period may not be allowed to exchange frames with the r-TWT scheduling AP during the r-TWT service period or may be allowed to exchange frames with the r-TWT scheduling AP during the r-TWT service period but with lower priority. Also, the r-TWT scheduling AP and member STAs of a r-TWT service period may negotiate which traffic is scheduled to be transmitted during the r-TWT service period.

[0174] Figure 20 is a diagram showing a r-TWT service period membership setup procedure, according to some embodiments. The procedure shown in the diagram follows the approach defined in IEEE 802.1 lax / be. The procedure may involve a (non-AP) STA 2030 and an AP 2010. The STA 2030 may be a r-TWT scheduled STA. The AP 2010 may be a r-TWT scheduling AP. The STA 2030 may include a station management entity (SME) and a MAC layer management entity (MLME) The SME may be an entity that manages the establishment, maintenance, and / or termination of wireless connectivity. It may operate independently of the MAC and PHY layers, collecting layer-specific status information from the MLME and physical layer management entity (PLME), and set various management parameters of those layers. The MLME may be an entity that resides within the MAC sublayer and may handle higher MAC functions such as synchronization, power management, and connection management, which may include association and authentication, and roaming operations. The AP 2010 may also include a SME and MLME.

[0175] As shown in the diagram, the STA 2030 may transmit a TWT setup request frame (e g., a r-TWT membership request frame) to the AP 2010 to request membership of a r-TWT service period. The AP 2010 may respond by transmitting a TWT setup response frame (e g., r- TWT membership response frame) to the STA 2030 to indicate the result of the request. The TWT setup request frame and / or the TWT setup response frame may include information regarding stream classification service (SCS) traffic streams to facilitate the setting up of the r- TWT service period membership.

[0176] More specifically, the STA’ s 2030 SME may send a MLME-TWT SETUP. request message to the STA’s 2030 MLME containing TWT setup information. When the STA’s 2030MLME receives the MLME-TWT SETUP, request message, it may collect the information included in the MLME-TWTSETUP. request message. Then, the STA’s 2030 MLME may transmit a TWT setup request frame (e.g., that includes SCS traffic information) to the AP’s 2010 MLME to request membership of a r-TWT service period. Responsive to receiving the TWT setup request frame, the AP’s 2010 MLME may generate a MLME- TWTSETUP indication message and send it to the AP’s 2010 SME which processes the request. Responsive to receiving the MLME-TWT SETUP. indication message, the AP’s 2010 SME may process the r-TWT service period membership setup request (e.g., set up the r-TWT service period for the STA 2030) and send a MLME-TWTSETUP response message to the AP’s 2010 MLME containing the r-TWT setup result. Responsive to receiving the MLME- TWTSETUP. response message, the AP’s 2010 MLME may transmit a TWT setup response frame (e.g., that includes the SCS traffic information) to the STA's 2030 MLME to indicate the r-TWT setup result (e.g., whether the STA 2030 has successfully established membership in the r-TWT service period). Finally, responsive to receiving the TWT setup response frame, the STA's 2030 MLME may send a MLME-TWTSETUP. confirm message to the STA’s 2030 SME to confirm that the setting up of the r-TWT service period membership was successful (assuming the r-TWT setup was successful). A MLME-TWTSETUP. confirm message is a MAC layer management primitive used by the MLME to report the result of a TWT setup procedure to the SME. It may include status information or parameters related to the established r-TWT agreement.

[0177] The AP 2010 and member STAs 2030 of the r-TWT service period may negotiate which traffic is scheduled to be transmitted during the r-TWT service period. The scheduled traffic may receive transmission priority during the r-TWT service period.

[0178] Figure 21 is a diagram showing a situation that can occur when a wireless network implements r-TWT technology and relay technology, according to some embodiments.

[0179] As shown in the diagram, a first (non-AP) STA (“STA1”) may be a member of a first service period (“r-TWT SP1”) and only wake up during the first r-TWT service period to exchange frames with the AP and remain in a sleep state at other times. A relay STA (“STA2” or “rSTA”) may be a member of a second service period (“r-TWT SP2”) and only wake up during the second r-TWT service period to exchange frames with the AP and remain in a sleep state at other times. A third (non-AP) STA (“STA3”) may be associated with rSTA and rely on rSTA to relay frames to / from the AP. ST A3 may be a member of a third r-TWT service period (“r-TWT SP3”) scheduled by the AP. STA3 may remain in a sleep state during the service periods of other STAs (e g., during r-TWT SP1 and r-TWT SP2) to save energy (but STA3 maydecide to be in an awake state during TWT SP2 if needed). STA3 may wake up during its scheduled r-TWT service period (r-TWT SP3) to exchange frames with the AP.

[0180] An important consideration when implementing r-TWT technology and relay technology in a wireless network is to ensure that the relay STA (e.g., rSTA2) remains awake when it is needed to relay traffic on behalf of its associated (non-AP) STAs (e.g., STA3). For example, rSTA2 should remain awake during the r-TWT service period of STA3 (e g., r-TWT SP3) to provide relay functionality and ensure seamless connectivity. That is, the r-TWT service periods of STA3 and rSTA2 should be synchronized.

[0181] A synchronization technique is described herein to synchronize the r-TWT service periods of the relay STA and the STAs that are associated with the relay STA (e.g., the STAs that rely on the relay STA to communicate with an AP). The synchronization technique may allow the relay STA to be awake whenever an associated STA is expected to be awake so that the relay STA can be available to relay traffic between the associated STA and an AP As will be described in additional herein, the synchronization technique may synchronize the r-TWT service periods of the relay STA and the associated STAs by setting up the r-TWT service period membership whenever a STA associates with the relay STA for relaying (e.g., when a relay link is established between a STA and the relay STA). Also, when the STA disassociates from the relay STA (e g , when the relay link between a STA and the relay STA is disconnected), the synchronization technique may update the r-TWT service period membership to remove the STA from being a member of the r-TWT service period.

[0182] Figure 22 is a diagram showing a roaming scenario for a STA MLD in a relay-enabled environment, according to some embodiments.

[0183] As shown in the diagram, a (non-AP) STA MLD 2230 may initially be connected to API of AP MLD1 2210-1 through a first link operating in a 2.4 GHz band (Linkl) and connected to AP2 of AP MLD1 2210-1 through a second link operating in a 5 GHz band (Link2). As the STA 2230 moves away from AP MLD1 2210-1, it may reach the boundary of AP MLDl ’s 2210-1 5 GHz coverage area, experiencing weak link condition. In such a situation, the STA 2230 may decide to connect its 5 GHz link (Link2) to a relay STA MLD 2220 to extend coverage and ensure seamless connectivity even in areas with weak signal conditions beyond AP MLDl’s 2210-1 5GHz coverage area. For example, as shown in the diagram, the STA 2230 may connect Link2 to rSTA2 of relay STA MLD 2220 to achieve coverage extension in the 5 GHz band via the relay STA MLD 2220, while still maintaining Linkl with API of AP MLD1 2210-1. The relay STA MLD 2220 may relay traffic between the STA 2230 and APMLD1 2210-1 over Link2. Thus, in this example, Link2 between the STA 2230 and rSTA2 may be a relay link. As used herein, a relay link is a link that is used for relaying traffic.

[0184] The STA 2230 may periodically assess the link quality of its MLD links (e g., based on management frames transmitted by AP MLD1 2210-1) and may decide to roam to a neighboring AP MLD2 2210-2 if the STA 2230 is within the coverage area of AP MLD2 2210-2 and the MLD links with AP MLD1 2210-1 have poor link quality As shown in the diagram, if the STA 2230 decides to roam to AP MLD2 2210-2, it may disconnect Linkl from API of AP MLD1 2210-1 and establish a new link with AP3 of AP MLD2 2210-2 in the same band. The STA 2230 may maintain Link2 with rSTA2 of the relay STA MLD 2220 until the new link with AP3 of AP MLD2 2210-2 is established. The STA 2230 may be connected to AP MLD2 2210- 2 through Linkl and connected to AP MLD1 2210-1 through Link2 with the relay STA MLD 2220 for a period of time. During this period of time, the STA 2230 is said to be in a roaming transition state. After the new link (Linkl) with AP3 of AP MLD2 2210-2 is established, the STA 2230 may disconnect Link2 from rSTA2 of the relay STA MLD 2220 and establish a new link with AP4 of the neighboring AP MLD2 2210-2 in the same band, which completes the roaming procedure. As a result, the STA 2230 is connected to AP MLD2 2210-2 through two MLD links (Linkl and Link2). A central controller upper service access point (U-SAP) 2250 may be connected to AP MLD1 2210-1 and AP MLD 2 2210-2 and help manage / oversee the roaming procedure.

[0185] In a scenario where a new relay link is established between the STA 2230 and the relay STA MLD 2220 (e g., the scenario shown in the upper-right portion of the diagram), it is necessary to synchronize the r-TWT service periods of the STA 2230 and the relay STA MLD 2220 (e.g., the STA 2230 should be a member of the same r-TWT service period as the relay STA MLD 2220) to ensure that traffic can be relayed. In this scenario, as will be described in additional detail herein, the STA 2230 may initiate a r-TWT service period membership synchronization procedure upon the relay link being established.

[0186] In a scenario where a relay link between the STA 2230 and the relay STA MLD 2220 is disconnected (e.g., the scenario shown in the lower-right portion of the diagram), it is necessary to remove the STA 2230 from being a member of the r-TWT service period of the relay STA MLD 2220 (since the r-TWT service periods of the STA 2230 and the relay STA MLD 2220 no longer need to be synchronized). In this scenario, as will be described in additional detail herein, the relay STA MLD 2220 may initiate a r-TWT service period membership update procedure to remove the STA 2230 from being a member of the r-TWT service period.

[0187] Figure 23 is a diagram showing a r-TWT service period membership synchronization procedure, according to some embodiments

[0188] The procedure may involve a (non-AP) STA 2330, a relay STA 2320, and an AP 2310. The STA 2330, the relay STA 2320 and the AP 2310 may each include a SME and a MLME.

[0189] As shown in the diagram, at operation 1, the STA 2330 may detect that a relay link is newly established between the STA 2330 and the relay STA 2320. The establishment of the new relay link may be detected by a relay management module of the non-AP STA 2330. Responsive to detecting that the new relay link has been established, the STA 2330 may initiate a r-TWT service period membership setup procedure. For example, the STA’s 2330 SME may send a MLME-TWTSETUP. request message to the STA’s 2330 MLME containing TWT setup information. Responsive to receiving the MLME-TWTSETUP.request message, the STA’s 2330 MLME may transmit a TWT setup request frame to the relay STA’s 2320 MLME to request membership of a r-TWT service period.

[0190] Responsive to receiving the TWT setup request frame, the relay STA’ s 2320 MLME may send a MLME-TWTSETUP.request message to the relay STA’s 2320 SME. At operation 2, responsive to receiving the MLME-TWTSETUP.request message, the relay STA’s 2320 SME may process the r-TWT service period membership setup request In particular, the relay STA’s 2320 SME may determine whether a r-TWT service period has already been scheduled between the relay STA 2320 and the AP 2310. If a r-TWT service period has already been scheduled between the relay STA 2320 and the AP 2310, the relay STA’s 2320 SME may align the STA’s 2330 r-TWT service period schedule and the relay STA’s 2320 r-TWT service period schedule such that the relay STA 2320 is awake whenever the STA 2320 is awake. Otherwise, if a r- TWT service period has not already been scheduled between the relay STA 2320 and the AP 2310, the relay STA’s 2320 SME may generate a new r-TWT service period schedule for the STA 2330 and the relay STA 2320 such that relay STA 2320 is awake whenever the STA 2330 is awake. The relay STA’s 2320 SME may then send a MLME-TWTSETUP.request message to the relay STA’s 2320 MLME. Responsive to receiving the MLME-TWTSETUP.request message, the relay STA’s 2320 MLME may transmit a TWT setup request frame to the AP’s 2310 MLME to request membership of a r-TWT service period. This TWT setup request frame may include a request for the STA 2330 and the relay STA 2320 to be members of the same r- TWT service period (and may include additional information such as the desired r-TWT service period schedule, the STA’s 2330 SCS information, etc.).

[0191] Responsive to receiving the TWT setup request frame, the AP’s 2310 MLME may send a MLME-TWTSETUP. indication message to the AP’s 2310 SME. At operation 3, responsive to receiving the MLME-TWTSETUP indication message, the AP’s 2310 SME may process the r-TWT service period membership setup request (e.g., by adding the STA 2330 as a member of an existing r-TWT service period of the relay STA 2320 or scheduling a new r-TWT service period with the STA 2330 and the relay STA 2320 being members of the new r-TWT service period) and send a MLME-TWTSETUP.response message to the AP’s 2310 MLME containing the r-TWT setup result (it is assumed that the setting up of the r-TWT service period was successful in this example) Responsive to receiving the MLME-TWTSETUP response message, the AP’ s 2310 MLME may transmit a TWT setup response frame to the relay STA's 2320 MLME to indicate that the setting up of the r-TWT service period membership was successful.

[0192] Responsive to receiving the TWT setup response frame, the relay STA's 2320 MLME may send a MLME-TWTSETUP. confirm message to the relay STA’s 2320 SME to confirm that the setting up of the r-TWT service period membership was successful. At operation 4, responsive to receiving the MLME-TWTSETUP. confirm message, the relay STA’s 2320 SME may process the r-TWT service period membership setup response and send a MLME- TWTSETUP confirm message to the relay STA’s 2320 MLME to confirm that the setting up of the r-TWT service period membership was successful. Responsive to receiving the MLME- TWTSETUP. confirm message, the relay STA’s 2320 MLME may transmit a TWT setup response frame to the STA’s 2330 MLME to indicate that the setting up of the r-TWT service period membership was successful.

[0193] Responsive to receiving the TWT setup response frame, the STA’s 2330 MLME may send a MLME-TWTSETUP. confirm message to the STA’s 2330 SME to confirm that the setting up of the r-TWT service period membership was successful. At operation 5, responsive to receiving the MLME-TWTSETUP. confirm message, the STA’s 2330 SME may process the r-TWT service period membership setup response.

[0194] As a result of carrying out the procedure shown in the diagram, both the STA 2330 and the relay STA 2320 may be members of the same r-TWT service period. As such, the relay STA 2320 will be able to relay traffic on behalf of the STA 2320 during the r-TWT service period.

[0195] Figure 24 is a flow diagram showing a method for synchronizing r-TWT service periods of a STA and a relay STA, according to some embodiments The method may be performed by a relay STA.

[0196] At operation 2405, the relay STA may detect that a relay link has been newly established between the relay STA and a (non-AP) STA.

[0197] At operation 2410, the relay STA may receive a TWT setup request frame from the STA over the relay link.

[0198] At operation 2415, the relay STA may determine whether a r-TWT service period (SP) has already been scheduled between the relay STA and the AP If a r-TWT service period has already been scheduled between the relay STA and the AP, the method may move to operation 2420. At operation 2420, the relay STA may align the STA’ s r-TWT service period schedule with the relay STA’s r-TWT service period schedule The method may then proceed to operation 2435.

[0199] Otherwise, if a r-TWT service period has not already been scheduled between the relay STA and the AP, the method may move to operation 2425. At operation 2425, the relay STA may generate a new r-TWT service period schedule for relay communication. At operation 2430, the relay STA registers a new r-TWT service period with the AP according to the generated r-TWT service period schedule. The method may then proceed to operation 2435.

[0200] At operation 2435, a procedure is performed to schedule a r-TWT service period with the AP such that both the STA and the relay STA are members of the same r-TWT service period

[0201] As shown in Figure 22 and mentioned above, the relay link between the relay STA and one of its associated (non-AP) STAs may become disconnected. In such case, the r-TWT service period membership should be updated. A procedure for updating the r-TWT service period membership is described below.

[0202] Figure 25 is a diagram showing a r-TWT service period membership update procedure, according to some embodiments The procedure may involve a relay STA 2520 and an AP 2510. The relay STA 2520 and the AP 2510 may each include a SME and a MLME.

[0203] At operation 1, the relay STA 2520 may detect that a relay link between the relay STA 2520 and one of its associated STAs has been disconnected The disconnection of the relay link may be detected by a relay management module of the relay STA 2520. Responsive to detecting that the relay link has been disconnected, the relay STA 2520 may initiate a r-TWT service period membership setup procedure. For example, the relay STA’s 2520 SME may send a MLME-TWT SETUP. request message to the relay STA’s 2520 MLME. Responsive to receiving the MLME-TWTSETUP.request message, the relay STA’s 2520 MLME may determine whether there is a r-TWT service period scheduled for the STA. If there is no r-TWT service period scheduled for the STA, the procedure may end. If there is a r-TWT service periodscheduled for the STA (which is assumed in this example), the relay STA’s 2520 MLME may transmit a TWT setup request frame to the AP’s 2510 MLME to remove the associated STA from being a member of the r-TWT service period.

[0204] Responsive to receiving the TWT setup request frame, the AP’s 2510 MLME may send a MLME-TWTSETUP. indication message to the AP’s 2510 SME. Responsive to receiving the MLME-TWTSETUP.indication message, the AP’s 2510 SME may process the r- TWT service period membership setup request (e.g., by removing the STA from being a member of the r-TWT service period) and send a MLME-TWTSETUP. response message to the AP’s 2510 MLME Responsive to receiving the MLME-TWTSETUP response message, the AP’s 2510 MLME may transmit a TWT setup response frame to the relay STA’s 2520 MLME to indicate that the updating of the r-TWT service period membership was successful.

[0205] Responsive to receiving the TWT setup response frame, the relay STA’s 2520 MLME may send a MLME-TWTSETUP. confirm message to the relay STA’s 2520 SME to confirm the updating of the r-TWT service period membership was successful. At operation 2, responsive to receiving the MLME-TWTSETUP. confirm message, the relay STA’s 2520 SME may process the r-TWT service period membership setup response. For example, the relay STA’s 2520 SME may recognize that the r-TWT service period membership update was successful based on information included in the MLME-TWTSETUP confirm message

[0206] Figure 26 is a flow diagram of a method for updating a r-TWT service period membership, according to some embodiments. The method may be performed by a relay STA.

[0207] At operation 2605, the relay STA may detect that a relay link between the relay STA and an associated STA has been disconnected.

[0208] At operation 2610, the relay STA may determine whether there is a r-TWT service period scheduled for the STA with the AP. If there is no r-TWT service period scheduled for the STA with the AP, the method may end. Otherwise, if there is a r-TWT service period scheduled for the STA with the AP, the method may proceed to operation 2615. At operation 2615, the relay STA may perform a procedure to update the membership of the r-TWT service period to remove the STA from being a member of the r-TWT service period.

[0209] An important consideration when implementing r-TWT technology and relay technology in a wireless network is to ensure that the relay STA remains awake when its associated STAs are awake. That is, the r-TWT service periods of the relay STA and the associated STAs should be synchronized. The synchronization technique described herein can synchronize the r-TWT service periods of the relay STA and its associated STAs through a r- TWT service period membership setup process. Also, the synchronization technique mayupdate the membership of a r-TWT service period to remove a STA from being a member of the r-TWT service period when a relay link between the relay STA and the STA is disconnected (since synchronization of the r-TWT service periods is no longer needed in that case).

[0210] Turning now to Figure 27, a method 2700 will be described for synchronizing the r- TWT service periods of a STA and a relay STA, in accordance with an example embodiment. The method 2700 may be performed by a relay STA that is to relay traffic between the STA and an AP. The relay STA may be implemented by a wireless device (e.g., wireless device 104).

[0211] Additionally, although shown in a particular order, in some embodiments the operations of the method 2700 (and the other methods shown in the other figures) may be performed in a different order. For example, although the operations of the method 2700 are shown in a sequential order, some of the operations may be performed in partially or entirely overlapping time periods.

[0212] At operation 2705, the relay STA receives a first TWT setup request frame from the STA.

[0213] At operation 2710, responsive to receiving the first TWT setup request frame from the STA, the relay STA transmits a second TWT setup request frame to the AP to schedule a r-TWT service period (to request membership of the r-TWT service period) , wherein the second TWT setup request frame includes a request for the STA and the relay STA to be members of a same r-TWT service period. The request for the STA and the relay STA to be members of the same r- TWT service period may be made explicitly (e.g., by explicitly indicating that the STA and the relay STA should be members of the same r-TWT service period) or implicitly (e.g, in a way that the AP can infer that the STA and the relay STA should be members of the same r-TWT service period). In an embodiment, the first TWT setup request frame includes SCS information of traffic to be transmitted by the STA during the r-TWT service period, wherein the SCS information is also included in the second TWT setup request frame. In an embodiment, the first TWT setup request frame is transmitted by the STA in response to establishing a relay link with the relay STA. In an embodiment, the relay link operates in a first channel, wherein the STA also has a direct link established with the AP, wherein the direct link operates in a second channel that is different from the first channel (e.g., when the STA is capable of MLO).

[0214] In an embodiment, as shown in block 2715, if the relay STA has an existing r-TWT service period scheduled with the AP, the request includes an indication that the STA is to be member of the existing r-TWT service period. In an embodiment, as shown in block 2720, if the relay STA does not have an existing r-TWT service period scheduled with the AP, the requestincludes an indication that a new r-TWT service period is to be scheduled with the STA and the relay STA being members of the new r-TWT service period.

[0215] In an embodiment, at operation 2725, the relay STA receives a first TWT setup response frame from the AP indicating whether scheduling of the r-TWT service period was successful.

[0216] In an embodiment, at operation 2730, responsive to receiving the first TWT setup response frame from the AP, the relay STA transmits a second TWT setup response frame to the STA indicating whether scheduling of the r-TWT service period was successful.

[0217] In an embodiment, at operation 2735, responsive to determining that the scheduling of the r-TWT service period was successful, the relay STA wakes up immediately before the r- TWT service period and relays traffic between the STA and the AP during the r-TWT service period.

[0218] Turning now to Figure 28, a method 2800 will be described for updating a membership of a r-TWT service period, in accordance with an example embodiment. The method 2800 may be performed by a relay STA. The relay STA may be implemented by a wireless device (e.g., wireless device 104).

[0219] At operation 2805, the relay STA determines whether a relay link between the relay STA and the STA has been disconnected If the relay link has not been disconnected, the method may return to operation 2805. However, if the relay link has been disconnected, the method may move to operation 2810.

[0220] At operation 2805, the relay STA determines whether the STA has an existing r-TWT service period scheduled with the AP. If the STA does not have an existing r-TWT service period scheduled with the AP, the method may end. However, if the STA has an existing r- TWT service period scheduled with the AP, the method may move to operation 2815.

[0221] At operation 2815, the relay STA transmits a TWT setup request frame to the AP to update a membership of the existing r-TWT service period, wherein the TWT setup request frame includes a request for the STA to be removed from being a member of the existing r-TWT service period.

[0222] In an embodiment, at operation 2820, the relay STA receives a TWT setup response frame from the AP indicating whether updating of the membership of the existing r-TWT service period was successful.

[0223] Turning now to Figure 29, a method 2900 will be described for requesting membership of a r-TWT service period, in accordance with an example embodiment. The method 2900 may be performed by a relayed STA (a STA that relies on a relay STA forcommunication). The relayed STA may be implemented by a wireless device (e g., wireless device 104).

[0224] At operation 2905, the STA establishes a relay link with a relay STA

[0225] At operation 2910, the STA transmits a r-TWT setup request frame to the relay STA over the relay link to schedule a r-TWT service period with an AP.

[0226] At operation 2915, the STA receives a TWT setup response frame from the relay STA indicating that scheduling of the r-TWT service period was successful, wherein the STA and the relay STA are both members of the r-TWT service period.

[0227] At operation 2920, responsive to determining that the scheduling of the r-TWT service period was successful, the STA wakes up immediately before the r-TWT service period and transmits traffic intended for the AP over the relay link during the r-TWT service period.

[0228] Turning now to Figure 30, a method 3000 will be described for scheduling a r-TWT service period and updating membership of the r-TWT service period, in accordance with an example embodiment. The method 3000 may be performed by an AP. The AP may be implemented by a wireless device (e.g., wireless device 104).

[0229] At operation 3005, the AP receives a first TWT setup request frame from a relay STA, wherein the first TWT setup request frame includes a request for a STA and a relay STA to be members of a same r-TWT service period

[0230] At operation 3010, responsive to receiving the first TWT setup frame, the AP schedules the r-TWT service period with the STA and relay STA being members of the r-TWT service period.

[0231] At operation 3015, the AP transmits a first TWT setup response frame to the relay STA indicating that scheduling of the r-TWT service period was successful.

[0232] At operation 3020, the AP receives a second TWT setup request frame from the relay STA, wherein the second TWT setup request frame includes a request for the STA to be removed from being a member of the r-TWT service period.

[0233] At operation 3025, responsive to receiving the second TWT setup request frame, the AP updates the membership of the r-TWT service period to remove the STA from being a member of the r-TWT service period.

[0234] At operation 3030, the AP transmits a second TWT setup response frame to the relay STA indicating that updating of the membership of the r-TWT service period was successful.

[0235] Although many of the solutions and techniques provided herein have been described with reference to a WLAN system, it should be understood that these solutions and techniques are also applicable to other network environments, such as cellular telecommunication networks,wired networks, etc. In some embodiments, the solutions and techniques provided herein may be or may be embodied in an article of manufacture in which a non-transitory machine-readable medium (such as microelectronic memory) has stored thereon instructions which program one or more data processing components (generically referred to here as a “processor” or “processing unit”) to perform the operations described herein. In other embodiments, some of these operations might be performed by specific hardware components that contain hardwired logic (e.g., dedicated digital filter blocks and state machines). Those operations might alternatively be performed by any combination of programmed data processing components and fixed hardwired circuit components

[0236] In some cases, an embodiment may be an apparatus (e g., an AP STA, a non-AP STA, or another network or computing device) that includes one or more hardware and software logic structures for performing one or more of the operations described herein. For example, as described herein, an apparatus may include a memory unit, which stores instructions that may be executed by a hardware processor installed in the apparatus. The apparatus may also include one or more other hardware or software elements, including a network interface, a display device, etc.

[0237] Some portions of the preceding detailed descriptions have been presented in terms of algorithms and symbolic representations of operations on data bits within a computer memory These algorithmic descriptions and representations are the ways used by those skilled in the data processing arts to most effectively convey the substance of their work to others skilled in the art. An algorithm is here, and generally, conceived to be a self-consistent sequence of operations leading to a desired result The operations are those requiring physical manipulations of physical quantities. Usually, though not necessarily, these quantities take the form of electrical or magnetic signals capable of being stored, combined, compared, and otherwise manipulated. It has proven convenient at times, principally for reasons of common usage, to refer to these signals as bits, values, elements, symbols, characters, terms, numbers, or the like.

[0238] It should be bome in mind, however, that all of these and similar terms are to be associated with the appropriate physical quantities and are merely convenient labels applied to these quantities. The present disclosure can refer to the action and processes of a computer system, or similar electronic computing device, that manipulates and transforms data represented as physical (electronic) quantities within the computer system's registers and memories into other data similarly represented as physical quantities within the computer system memories or registers or other such information storage systems.

[0239] The present disclosure also relates to an apparatus for performing the operations herein. This apparatus can be specially constructed for the intended purposes, or it can include a general -purpose computer selectively activated or reconfigured by a computer program stored in the computer. For example, a computer system or other data processing system may carry out the computer-implemented methods described herein in response to its processor executing a computer program (e.g., a sequence of instructions) contained in a memory or other non- transitory machine-readable storage medium. Such a computer program can be stored in a computer readable storage medium, such as, but not limited to, any type of disk including floppy disks, optical disks, CD-ROMs, and magnetic-optical disks, read-only memories (ROMs), random access memories (RAMs), EPROMs, EEPROMs, magnetic or optical cards, or any type of media suitable for storing electronic instructions, each coupled to a computer system bus.

[0240] The algorithms and displays presented herein are not inherently related to any particular computer or other apparatus. Various general-purpose systems can be used with programs in accordance with the teachings herein, or it can prove convenient to construct a more specialized apparatus to perform the method. The structure for a variety of these systems will appear as set forth in the description below. In addition, the present disclosure is not described with reference to any particular programming language. It will be appreciated that a variety of programming languages can be used to implement the teachings of the disclosure as described herein.

[0241] The present disclosure can be provided as a computer program product, or software, that can include a machine-readable medium having stored thereon instructions, which can be used to program a computer system (or other electronic devices) to perform a process according to the present disclosure. A machine-readable medium includes any mechanism for storing information in a form readable by a machine (e.g., a computer). In some embodiments, a machine-readable (e.g., computer-readable) medium includes a machine (e.g., a computer) readable storage medium such as a read only memory (“ROM”), random access memory (“RAM”), magnetic disk storage media, optical storage media, flash memory components, etc.

[0242] In the foregoing specification, embodiments of the disclosure have been described with reference to specific example embodiments thereof. It will be evident that various modifications can be made thereto without departing from the broader spirit and scope of embodiments of the disclosure as set forth in the following claims. The specification and drawings are, accordingly, to be regarded in an illustrative sense rather than a restrictive sense.

Claims

CLAIMSWhat is claimed is:

1. A method performed by a relay station (STA) to synchronize restricted target wake time (r-TWT) service periods with a STA when the relay STA is to relay traffic between the STA and an access point (AP), the method comprising: receiving a first TWT setup request frame from the STA; and responsive to receiving the first target wake time (TWT) setup request frame from the STA, transmitting a second TWT setup request frame to the AP to schedule a r- TWT service period, wherein the second TWT setup request frame includes a request for the STA and the relay STA to be members of a same r-TWT service period.

2. The method of claim 1, further comprising: receiving a first TWT setup response frame from the AP indicating whether scheduling of the r-TWT service period was successful; and responsive to receiving the first TWT setup response frame from the AP, transmitting a second TWT setup response frame to the STA indicating whether scheduling of the r-TWT service period was successful.

3. The method of claim 2, further comprising: responsive to determining that the scheduling of the r-TWT service period was successful, waking up immediately before the r-TWT service period and relaying traffic between the STA and the AP during the r-TWT service period.

4. The method of claim 1, further comprising: responsive to receiving the first TWT setup request frame from the STA, determining whether the relay STA has an existing r-TWT service period scheduled with the AP, wherein if the relay STA has the existing r-TWT service period scheduled with the AP, the request includes an indication that the STA is to be a member of the existing r-TWT service period.

5. The method of claim 1, further comprising:responsive to receiving the first TWT setup request frame from the STA, determining whether the relay STA has an existing r-TWT service period scheduled with the AP, wherein if the relay STA does not have an existing r-TWT service period scheduled with the AP, the request includes an indication that a new r-TWT service period is to be scheduled with the STA and the relay STA being members of the new r-TWT service period.

6. The method of claim 1, further comprising: responsive to determining that a relay link between the relay STA and the STA has been disconnected, determining whether the STA has an existing r-TWT service period scheduled with the AP; and responsive to determining that the STA has the existing r-TWT service period scheduled with the AP, transmitting a third TWT setup request frame to the AP to update a membership of the existing r-TWT service period, wherein the third TWT setup request frame includes a request for the STA to be removed from being a member of the existing r-TWT service period.7 The method of claim 6, further comprising: receiving a third TWT setup response frame from the AP indicating whether updating of the membership of the existing r-TWT service period was successful.

8. The method of claim 1, wherein the first TWT setup request frame includes stream classification service (SCS) information of traffic to be transmitted by the STA during the r- TWT service period, wherein the SCS information is also included in the second TWT setup request frame.

9. The method of claim 1, wherein the first TWT setup request frame is transmitted by the STA in response to establishing a relay link with the relay STA.

10. The method of claim 9, wherein the relay link operates in a first channel, wherein the STA also has a direct link established with the AP, wherein the direct link operates in a second channel that is different from the first channel.

11. A wireless device to implement a relay station (STA), the wireless device comprising:a radio frequency transceiver; a memory device storing a set of instructions; and a processor coupled to the memory device, wherein the set of instructions, when executed by the processor, causes the relay STA to perform the method of any one of claims 1-10.

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