EP4699379A2 - Enhanced restricted target wake time (e-rtwt) scheme for a multiple basic service set (bss) environment - Google Patents

Abstract

Disclosed herein is a method performed by am access point (AP) of a basic service set (BSS) to schedule a restricted target wake time (rTWT) service period (SP). The method includes transmitting a frame that includes restricted target wake time service period scheduling information for scheduling a restricted target wake time service period that includes a first section during which one or more members of the BSS are allowed to transmit data and a second section during which one or more members of an overlapping BSS (OBSS) that overlaps the BSS, but not members of the BSS, are allowed to transmit data.

Description

SPECIFICATION

ENHANCED RESTRICTED TARGET WAKE TIME (E-RTWT) SCHEME FORA MULTIPLE BASIC SERVICE SET (BSS) ENVIRONMENT

CROSS-REFERENCE TO RELATED APPLICATION

[0001] This application claims the benefit of U.S. Provisional Application No. 63/509,265, filed June 20, 2023, titled, “Multi-AP resource management by using Enhanced Restricted Target Wake Time (e-rTWT) parameter set in OBSS network conditions in beyond IEEE 802.1 Ibe,” which is hereby incorporated by reference.

TECHNICAL FIELD

[0002] The present disclosure generally relates to wireless communications, and more specifically, relates to an enhanced restricted target wake time scheme for a multiple basic service set (BSS) environment.

BACKGROUND

[0003] Institute of Electrical and Electronics Engineers (IEEE) 802.11 is a set of physical and Media Access Control (MAC) specifications for implementing Wireless Local Area Network (WLAN) communications. These specifications provide the basis for wireless network products using the Wi-Fi brand managed and defined by the Wi-Fi Alliance. The specifications define the use of the 2.400-2.500 Gigahertz (GHz) as well as the 4.915-5.825 GHz bands. These spectrum bands are commonly referred to as the 2.4GHz and 5GHz bands. Each spectrum is subdivided into channels with a center frequency and bandwidth. The 2.4 GHz band is divided into 14 channels spaced 5 Megahertz (MHz) apart, though some countries regulate the availability of these channels. The 5GHz band is more heavily regulated than the 2.4 GHz band and the spacing of channels varies across the spectrum with a minimum of a 5 MHz spacing dependent on the regulations of the respective country or territory.

[0004] WLAN devices are currently being deployed in diverse environments. These environments are characterized by the existence of many Access Points (APs) and non-AP stations (STAs) in geographically limited areas. Increased interference from neighboring devices gives rise to performance degradation. Additionally, WLAN devices are increasingly required to support a variety of applications such as video, cloud access, and offloading. Video traffic, in particular, is expected to be the dominant type of traffic in WLAN deployments. With the real-time requirements of some of these applications, WLAN users demand improved performance.

[0005] Restricted target wake time (rTWT) is a feature in a wireless network that allows an AP to provide enhanced medium access protection and resource reservation in order to achieve more predictable latency, reduced worst-case latency, and/or higher reliability for latency sensitive traffic. Conventional rTWT schemes are designed for a single basic service set (BSS) environment. In a dense network environment, overlapping BSS (OBSS) interference may cause transmissions during a rTWT service period (SP) of a BSS to fail.

BRIEF DESCRIPTION OF THE DRAWINGS

[0006] The disclosure will be understood more fully from the detailed description given below and from the accompanying drawings of various embodiments of the disclosure. The drawings, however, should not be taken to limit the disclosure to the specific embodiments, but are for explanation and understanding only.

[0007] Figure 1 illustrates an example wireless local area network (WLAN) with a basic service set (BSS) that includes a plurality of wireless devices, in accordance with some embodiments of the present disclosure.

[0008] Figure 2 is a schematic diagram of a wireless device, in accordance with some embodiments of the present disclosure.

[0009] Figure 3 A illustrates components of a wireless device configured to transmit data, in accordance with some embodiments of the present disclosure.

[0010] Figure 3B illustrates components of a wireless device configured to receive data, in accordance with some embodiments of the present disclosure.

[0011] Figure 4 illustrates Inter-Frame Space (IFS) relationships, in accordance with some embodiments of the present disclosure.

[0012] Figure 5 illustrates a Carrier Sense Multiple Access/Collision Avoidance (CSMA/CA) based frame transmission procedure, in accordance with some embodiments of the present disclosure.

[0013] Figure 6 shows a table comparing various iterations of Institute of Electrical and Electronics Engineers (IEEE) 802.11 standard, in accordance with some embodiments of the present disclosure.

[0014] Figure 7 shows a table, which describes fields of an Extreme High Throughput (EHT) frame format, in accordance with some embodiments of the present disclosure.

[0015] Figure 8 is a diagram showing the limitation of a conventional rTWT scheme. [0016] Figure 9 is a diagram showing an enhanced rTWT parameter set being announced by a single AP, according to some embodiments.

[0017] Figure 10 is a diagram showing both the AP of the BSS and the AP of the OBSS announcing an enhanced rTWT parameter set, according to some embodiments.

[0018] Figure 11 is a diagram showing a frame exchange sequence for the first type of rTWT SP, according to some embodiments.

[0019] Figure 12 is a diagram showing a frame exchange sequence for the second type of rTWT SP, according to some embodiments.

[0020] Figure 13 is a diagram showing a frame exchange sequence for the third type of rTWT SP, according to some embodiments.

[0021] Figure 14 is a diagram showing a channel division, according to some embodiments.

[0022] Figures 15 is a flow diagram showing another method for scheduling a rTWT SP, according to some embodiments.

[0023] Figures 16 is a flow diagram showing another method for transmitting data during a first type of rTWT SP, according to some embodiments.

[0024] Figures 17 is a flow diagram showing another method for transmitting data during a second type of rTWT SP, according to some embodiments.

[0025] Figures 18 is a flow diagram showing another method for transmitting data during a third type of rTWT SP, according to some embodiments.

DETAILED DESCRIPTION

[0026] One aspect of the present disclosure generally relates to wireless communications, and more specifically, relates to an enhanced restricted target wake time scheme for a multiple basic service set (BSS) scenario.

[0027] As mentioned above, conventional rTWT schemes are designed for a single basic service set (BSS) environment. In a dense network environment, overlapping BSS (OBSS) interference may cause transmissions during a rTWT service period (SP) of a BSS to fail. [0028] An enhanced restricted target wake time (rTWT) scheme is introduced herein that is suitable for use in a multi-BSS environment. The enhanced rTWT scheme may schedule a rTWT SP during which members of a BSS and members of an OBSS that overlaps the BSS are allowed to transmit data without collision. Three types of rTWT SPs are described herein: 1) the first type of rTWT SP allows a member of the OBSS to transmit data during the rTWT SP if the member of the OBSS has low latency data to transmit; 2) the second type of rTWT SP allows a member of the OBSS to contend for the channel during the rTWT SP if certain conditions are met (e.g., if the channel is idle for a predefined period of time); 3) the third type of rTWT SP allows a member of the BSS and a member of the OBSS to concurrently transmit during the rTWT SP by having the member of the BSS transmit data using a primary channel and having the member of the OBSS transmit data using a secondary channel.

[0029] With the enhanced rTWT scheme disclosed herein, members of an OBSS may be allowed to transmit low latency data during a rTWT SP of a BSS, thereby reducing the latency of the OBSS’s low latency data . Moreover, the enhanced rTWT scheme ensures there are no collisions between BSS transmissions and OBSS transmissions during the rTWT SP, thereby protecting the rTWT SP. The enhanced rTWT scheme may be used in next generation wireless standards (e.g., beyond IEEE 802.1 Ibe) to protect rTWT SPs in a multiple BSS environment. [0030] To protect the rTWT SP in a multiple BSS environment, one or more APs may announce rTWT SP scheduling information for scheduling a rTWT SP to members of the BSS and members of one or more OBSSs so that members of both the BSS and OBSS can become aware of the scheduled rTWT SP. The rTWT SP scheduling information may include information regarding the scheduled rTWT SP such as the start time and duration (or end time) of the rTWT SP. STAs that receive the rTWT SP scheduling information may end any transmissions before the rTWT SP begins to protect the rTWT SP. In an embodiment, the rTWT SP scheduling information takes the form of an enhanced rTWT parameter set. The enhanced rTWT parameter set may include one or more parameters of a conventional rTWT parameter set and one or more additional parameters for supporting the enhanced rTWT scheme (e.g., parameters for supporting one or more of the three types of rTWT SPs mentioned above). [0031] According to some embodiments, an AP of a BSS transmits a frame that includes restricted target wake time service period scheduling information for scheduling a restricted target wake time service period that includes a first section during which one or more members of the BSS are allowed to transmit data and a second section during which one or more members of an OBSS that overlaps the BSS, but not the members of the BSS, are allowed to transmit data. An AP or STA that receives the frame may determine when the first section of the restricted target wake time service period occurs and when the second section of the restricted target wake time service period occurs based on the restricted target wake time service period scheduling information included in the frame. A member of the BSS may transmit data during the first section of the restricted target wake time service period, but the member of the BSS may refrain from transmitting any data during the second section of the restricted target wake time service period. Similarly, a member of the OBSS may refrain from transmitting any data during the first section of the restricted target wake time service period, but the member of the OBSS may transmit a data frame during the second section of the restricted target wake time service period. In this way, members of the BSS and OBSS may have a chance to transmit data during the rTWT SP without collision, which helps reduce the latency of low latency data.

[0032] 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.

[0033] 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 various 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.

[0034] 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 for generating 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.

[0035] 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 104A) 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. 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). [0036] 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.

[0037] 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.

[0038] 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.

[0039] 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.

[0040] 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.

[0041] 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.

[0042] 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.

[0043] 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.

[0044] 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.

[0045] 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, such as application processors, storage interfaces, clock generator circuits, power supply circuits, and the like, which have been omitted in the interest of brevity.

[0046] Figure 3 A 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.

[0047] 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.

[0048] 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.

[0049] 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.

[0050] 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.

[0051] 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.

[0052] 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.

[0053] 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.

[0054] 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.

[0055] When the TxSP 324 performs a MIMO or MU-MIMO transmission, some blocks before the spatial mapper may be provided for each user.

[0056] 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.

[0057] 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.

[0058] 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.

[0059] The RxSP 326 includes a GI remover 318, a Fourier transformer (FT) 316, a demapper 314, a deinterleaver 312, and a decoder 310.

[0060] 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.

[0061] 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.

[0062] 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.

[0063] 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.

[0064] 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.

[0065] 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.

[0066] 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.

[0067] 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. [0068] 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.

[0069] 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) that are compliant with the 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.

[0070] 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.

[0071] 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.

[0072] 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.

[0073] 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.

[0074] 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 data frame, 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.

[0075] 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.

[0076] 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.

[0077] 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.

[0078] 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 ST A3 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.

[0079] 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.

[0080] 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 SIFS the station STA2 may transmit a Clear-To-Send (CTS) frame as a response to the RTS frame. If DuaLCTS 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).

[0081] 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. [0082] 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.

[0083] When the NAV timer expires, the third station ST A3 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 ST A3 may attempt to access the channel after a contention window elapses according to a backoff process. [0084] 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.

[0085] With clear demand for higher peak throughput/capacity in a WLAN, a new working group has been assembled to generate an amendment to IEEE 802.11. This amendment is called IEEE 802.1 Ibe (i.e., Extreme High Throughput (EHT)) and was created to support an increase to the peak PHY rate of a corresponding WLAN. Considering IEEE 802.1 lb through 802.1 lac, the peak PHY rate has been increased by 5x to 1 lx as shown in Figure 6, which presents a table 600 comparing various iterations of IEEE 802.11. In case of IEEE 802.1 lax, the 802.1 lax working group focused on improving efficiency, not peak PHY rate in dense environments. The maximum PHY rate (A Gbps) and PHY rate enhancement (Bx) for IEEE 802.1 Ibe could rely on the highest MCS (e.g., 4,096 QAM and its code rate).

[0086] 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. [0087] 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.

[0088] With respect to operational bands (e.g., 2.4/5/6 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 APs and STAs to become tri-band devices. Larger than 160MHz data transmissions (e.g., 320MHz) could be considered to increase the maximum PHY rate. For example, 320MHz or 160+160MHz data could be transmitted in the 6 GHz band. For example, 160+160MHz data could be transmitted across the 5 and 6 GHz bands.

[0089] In some embodiments, a transmitting STA generates a PPDU frame and transmits it to a receiving STA. The receiving STA receives, detects, and processes the PPDU. The PPDU can be an EHT PPDU that includes a legacy part (e.g., a legacy short training field (L-STF), a legacy long training field (L-LTF), and a legacy signal (L-SIG) field), an EHT signal A field (EHT-SIG-A), an EHT signal B field (EHT-SIG-B), an EHT hybrid automatic repeat request field (EHT-HARQ), an EHT short training field (EHT-STF), an EHT long training field (EHT- LTF), and an EHT-DATA field. Figure 7 includes a table 700, which describes fields of an EHT frame format. In particular, table 700 describes various fields that may be within the PHY preamble, data field, and midamble of an EHT frame format. For example, table 700 includes definitions 702, durations 704, Discrete Fourier transform (DFTs) periods 706, guard intervals (GIs) 708, and subcarrier spacings 710 for one or more of a legacy short training field (L- STF) 712, legacy long training field (L-LTF) 714, legacy signal field (L-SIG) 716, repeated L- SIG (RL-SIG) 718, universal signal field (U-SIG) 720, EHT signal field (EHT-SIG) 722, EHT hybrid automatic repeat request field (EHT-HARQ) 724, EHT short training field (EHT- STF) 726, EHT long training field (EHT-LTF) 728, EHT data field 730, and EHT midamble field (EHT-MA) 732.

[0090] The distributed nature of a channel access network, such as in IEEE 802.11 wireless networks, makes carrier sensing mechanisms important for collision free operation. The physical carrier sensing mechanism of one STA is responsible for detecting the transmissions of other STAs. However, it may be impossible to detect every single case in some circumstances. For example, one STA which may be a long distance away from another STA may see the medium as idle and begin transmitting a frame while the other STA is also transmitting. To overcome this hidden node, a network allocation vector (NAV) may be used. However, as wireless networks evolve to include simultaneous transmission/reception to/from multiple users within a single basic service set (BSS), such as uplink(UL)/downlink(DL) multi-user (MU) transmissions in a cascading manner, a mechanism may be needed to allow for such a situation. As used herein, a multi-user (MU) transmission refers to cases that multiple frames are transmitted to or from multiple STAs simultaneously using different resources. Examples of different resources are different frequency resources in OFDMA transmissions and different spatial streams in MU-MIMO transmissions. Therefore, DL-OFDMA, DL-MU-MIMO, UL- OFDMA, and UL-MU-MIMO are examples of MU transmissions.

[0091] 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.

[0092] 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.

[0093] 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.

[0094] 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, subpackets with corresponding SPIDs to be transmitted are in increasing order of SPID but can be exchanged/switched except for the first SPID.

[0095] To improve WLAN systems, AP cooperation has been discussed as a possible technology to be adopted in IEEE 802.1 Ibe, where there is high level classification depending on various AP cooperation schemes. For example, there is a first type of cooperation scheme in which data for a user is sent from a single AP (sometimes referred to as “coordinated”) and there is a second type of cooperation scheme in which data for a user is sent from multiple APs (sometimes referred to as “joint”).

[0096] For the coordinated scheme, multiple APs are 1) transmitting on the same frequency resource based on coordination and forming spatial nulls to allow for simultaneous transmission from multiple APs or 2) transmitting on orthogonal frequency resources by coordinating and splitting the spectrum to use the spectrum more efficiently. For the joint scheme, multiple APs are transmitting jointly to a given user.

[0097] rTWT is one of the main features proposed in IEEE 802.1 Ibe for supporting low latency transmission for various use cases such as augmented reality (AR), virtual reality (VR), etc. A limitation of the conventional rTWT scheme proposed in IEEE 802.1 Ibe is that the scheduling information for the rTWT SP is only shared by the AP with its associated ST As. That is, the conventional rTWT scheme announces rTWT SP scheduling information only within a single BSS. Thus, members of an OBSS that overlaps the BSS may not be aware of the rTWT SP of the BSS and thus may end up transmitting signals during the rTWT SP that interfere with the signals transmitted by the members of the BSS, which results in the rTWT SP not being fully protected. Thus, a member of the BSS may fail to take advantage of the channel access opportunity during the rTWT SP due to interference caused by OBSS signals. This may result in the transmission of low latency data within the BSS being further delayed.

[0098] Figure 8 is a diagram showing the limitation of a conventional rTWT scheme.

[0099] The diagram shows a multi-BSS environment that includes API that is associated with STA11 and STA12. API, STA11, and STA12 may belong to BSS1. The environment further includes AP2 that is associated with STA21. AP2 and STA21 may belong to BSS2. BSS1 and BSS2 may overlap in the sense that one or more members of BSS 1 may be able to hear signals of BSS2 and vice versa. In this situation, BSS2 may be considered to be an OBSS from the perspective of BSS 1. Similarly, BSS1 may be considered to be an OBSS from the perspective ofBSS2.

[00100] API of BSS 1 may transmit rTWT SP scheduling information to schedule a rTWT SP for the BSS during which one or more members of BSS 1 are allowed to transmit low latency data. However, with the conventional rTWT scheme, there is no rTWT SP scheduling information exchanged between API and AP2 so AP2 (and other members of BSS2) might be unaware of the scheduled rTWT SP of BSS1 and thus end up transmitting data to STA21 during the rTWT SP of BSS 1. In this case, STA12, which is a member of the rTWT SP of BSS 1 and within the transmission range of AP2, may not be able to receive low latency data during the rTWT SP of BSS 1 due to interference from AP2’s signal. Thus, STA12 is considered to be a “victim” of OBSS interference in this example. In the example shown in the diagram, STA21 and AP2 are located toward the edge of the coverage area of BSS 1 so they might not be able to hear some signals of BSS 1 and thus incorrectly identify the channel as being idle when it is not. This may result in STA21 or AP2 transmitting data during the rTWT SP of BSS 1, thereby causing interference. The problem may be worsened if STA21 or AP2 are outside of the coverage area of BSS 1.

[00101] The present disclosure introduces an enhanced rTWT scheme that can help with avoiding OBSS interference during a rTWT SP of a BSS in a dense multi-BSS scenario. The enhanced rTWT scheme may schedule a new type of rTWT SP during which members of a BSS and members of an OBSS are allowed to transmit data without collision. Three types of rTWT SPs are described herein: 1) the first type of rTWT SP allows a member of the OBSS to transmit data during the rTWT SP of the BSS if the member of the OBSS has low latency data to transmit; 2) the second type of rTWT SP allows a member of the OBSS to contend for the channel during the rTWT SP of the BSS after certain conditions are met (e.g., the channel is idle for a predefined period of time); 3) the third type of rTWT SP allows a member of the BSS and a member of the OBSS to concurrently transmit during the rTWT SP by having the member of the BSS transmit data using a primary channel and having the member of the OBSS transmit data using a secondary channel.

[00102] To implement the enhanced rTWT scheme, a new rTWT parameter set may be defined. The new rTWT parameter set may be referred to as an enhanced rTWT parameter set (or e-rTWT parameter set). The e-rTWT parameter set may include one or more parameters of a conventional rTWT parameter set (e.g., the rTWT parameter set proposed in IEEE 802.1 Ibe) and also one or more new parameters for supporting one or more of the new types of rTWT SPs mentioned above.

[00103] Figure 9 is a diagram showing an enhanced rTWT parameter set being announced by a single AP, according to some embodiments.

[00104] In the example shown in the diagram, API may transmit beacon frame 900 that includes an e-rTWT parameter set for scheduling a rTWT SP for BSS1. BSS1 is considered to be the rTWT holder in this scenario. The e-rTWT parameter set may include parameters describing the rTWT SP being scheduled. For example, the e-rTWT parameters may include one or more parameters of a conventional rTWT parameter set (e.g., Target Wake Time, Nominal Minimum TWT Wake Duration, TWT Wake Interval Mantissa, TWT Wake Interval Exponent, and/or Broadcast TWT Persistence defined in IEEE 802.11 wireless networking standards) and also one or more new parameters for supporting the enhanced rTWTscheme. The rTWT holder BSS is the main BSS that controls rTWT operations (e.g., the BSS of the AP that obtains TXOP before performing rTWT operations and/or the BSS of the AP that initiates negotiation/exchange of e-RTWT parameter set with an OBSS AP). All members of BSS 1 and BSS2 that receive the beacon frame 900 are restricted by the e-rTWT parameter set, meaning that they should respect the rTWT SP described by the e-rTWT parameter set (e.g., STAs shall end any transmissions before the rTWT SP begins and STAs should only transmit data during the rTWT SP if they are authorized to do so). While the conventional rTWT parameter set only restricts members of a single BSS, the e-rTWT parameter set may restrict members of more than one BSS. In this example, AP2 and STA21 of BSS2 are within the coverage area of API so they receive beacon frame 900 (including the e-rTWT parameter set contained therein) and thus are restricted by the e-rTWT parameter set. While the diagram shows the e-rTWT parameter set being included in a beacon frame, it should be appreciated that the e-rTWT parameter set can be included in other types of frames. For example, the e-RTWT parameter set may be included in a probe response frame or a management frame. [00105] Since all APs and STAs shown in the diagram are restricted by the e-rTWT parameter set, all of them may end any transmissions before the rTWT SP begins. During the rTWT SP, API may transmit trigger frame 905 that solicits an uplink transmission from STA12. Responsive to receiving trigger frame 905, STA12 may transmit data frame 910 to API. Responsive to receiving data frame 910, API may transmit acknowledgement (ACK) frame 915 to STA12. In this example, the members of BSS2 do not transmit data during the rTWT SP, thereby protecting the BSS1 transmission.

[00106] By announcing the e-rTWT parameter set to members of both BSS1 and BSS2 and those members being restricted by the e-rTWT parameter set, the rTWT SP of BSS1 can be protected from interference from BSS2 signals.

[00107] Figure 10 is a diagram showing both the AP of the BSS and the AP of the OBSS announcing an enhanced rTWT parameter set, according to some embodiments.

[00108] In the example shown in the diagram, API may transmit beacon frame 1000 that includes an e-rTWT parameter set. Also, AP2 may transmit beacon frame 1005 that includes the same e-rTWT parameter set. The e-rTWT parameter set may include parameters for describing the rTWT SP being scheduled, as described above with reference to Figure 9. BSS1 is considered to be the rTWT holder in this scenario. In the example shown in the diagram, API and AP2 transmit their beacon frames consecutively (one after another), but in other embodiments API and AP2 may transmit their beacon frame simultaneously. All members of BSS1 that receive beacon frame 1000 may be restricted by the e-rTWT parameter set included in beacon frame 1000. Also, all members of BSS2 that receive beacon frame 1005 may be restricted by the e-rTWT parameter set included in beacon frame 1005. Since the e-rTWT parameter set included in beacon frame 1000 and beacon frame 1005 are the same in this example, all members of BSS 1 and BSS2 are restricted by the same e-rTWT parameter set. In an embodiment, API and AP2 negotiate the e-rTWT parameter set (e.g., by communicating directly with each other or through an intermediary) or otherwise agree upon the same e-rTWT parameter set before transmitting the beacon frames (so that they both announce the same e- rTWT parameter set).

[00109] Since all members of BSS 1 and BSS2 are restricted by the e-rTWT parameter set, all of them may end any transmissions before the rTWT SP begins. During the rTWT SP, API may transmit trigger frame 1015 that solicits an uplink transmission from STA12. Responsive to receiving trigger frame 1015, STA12 may transmit data frame 1020 to API. Responsive to receiving data frame 1020, API may transmit ACK frame 1025 to STA12. In this example, the members of BSS2 do not transmit data during the rTWT SP, thereby protecting the BSS1 transmission.

[00110] By announcing the same e-rTWT parameter set to members of both BSS1 and BSS2 those members being restricted by the e-rTWT parameter set, the rTWT SP of BSS1 can be protected from interference from BSS2 signals.

[00111] Thus, an e-rTWT parameter set may restrict members of multiple BSSs. The e-rTWT parameter set may be announced by a single AP (e.g., as shown in Figure 9) or by multiple APs (e.g., as shown in Figure 10). In general, having multiple APs announce the e-rTWT parameter set may allow more STAs to be restricted by the e-rTWT parameter set, thereby better protecting the rTWT SP. For sake of simplicity, examples are described where there is a single OBSS. However, it should be appreciated that the techniques and concepts described herein can be extended to situations where there is more than one OBSS.

[00112] An e-rTWT parameter set may be used for scheduling a rTWT SP for a BSS during which members of an OBSS that overlaps the BSS are given an opportunity to transmit data. Three types of such rTWT SP are described herein. The parameters included in the e-rTWT parameter set may differ depending on the type of rTWT SP that is being scheduled.

[00113] Figure 11 is a diagram showing a frame exchange sequence for the first type of rTWT SP, according to some embodiments.

[00114] The first type of rTWT SP may allow a member of the OBSS to transmit data during the rTWT SP of the BSS if the member of the OBSS has low latency data to transmit.

[00115] As shown in the diagram, API of BSS 1 may transmit beacon frame 1100 that includes an e-rTWT parameter set for scheduling a rTWT SP. The e-rTWT parameter set may include parameters for allowing a member of BSS2 to transmit low latency data during the rTWT SP of BSS1. For example, the e-rTWT parameter set may include information regarding a section of the rTWT SP of BSS 1 during which members of BSS 1 are allowed to transmit data and information regarding a different section of the rTWT SP of BSS 1 during which members of BSS2 are allowed to transmit data. BSS1 is considered to be the rTWT holder in this scenario and the rTWT SP is for BSS1. Thus, BSS2 is considered to be an OBSS in this scenario. In the example shown in the diagram and some of the following diagrams, the e-rTWT parameter set is announced by a single AP (API). It should be appreciated that in other embodiments the e- rTWT parameter set can be announced by multiple APs (e.g., by API and AP2), as described above.

[00116] In an embodiment, the e-rTWT parameter set further includes parameters for providing information regarding one or more of: an identifier of the restricted target wake time service period, an operating bandwidth for the first section of the restricted target wake time service period, an operating bandwidth for the second section of the restricted target wake time service period, a received signal strength indicator (RS SI) for the AP of the BSS, a RSSI for an AP of the OBSS (e.g., the RSSI may be used for coordinated spatial reuse purposes), a traffic identifier (TID) of traffic that is allowed to be transmitted during the first section of the restricted target wake time service period, a TID of traffic that is allowed to be transmitted during the second section of the restricted target wake time service period, a stream classification service identifier of a stream that is allowed to be transmitted during the first section of the restricted target wake time service period, a stream classification service identifier of a stream that is allowed to be transmitted during the second section of the restricted target wake time service period.

[00117] All members of BSS1 and BSS2 that receive beacon frame 1100 may end any TXOPs or transmissions before the rTWT SP begins.

[00118] During the rTWT SP, API may transmit trigger frame 1105 that solicits an uplink transmission from STA12 of BSS1. Responsive to receiving trigger frame 1105, STA12 may transmit data frame 1010 to API. Responsive to receiving data frame 1010, API may transmit ACK frame 1115 to STA12.

[00119] In this example, it is assumed that shortly after ACK frame 1115 is transmitted, STA21 of BSS2 determines that it has low latency data to transmit to AP2. STA21 may transmit a low latency data frame 1120 (that includes the low latency data) to AP2 during the rTWT SP of BSS1 (e.g., during a particular section of the rTWT SP that is allocated for OBSS transmissions, as indicated by the e-rTWT parameter set announced in beacon frame 1100). Responsive to receiving low latency data frame 1120, AP2 may transmit ACK frame 1125 to STA21. In an embodiment, if API determines that BSS2 does not have low latency data to transmit during the determined period, API may restart its frame exchanges earlier than trigger frame 1130.

[00120] Subsequently, API may transmit another trigger frame 1130 that solicits an uplink transmission from STA12. Responsive to receiving trigger frame 1130, STA12 may transmit data frame 1135 to API. Responsive to receiving data frame 1135, API may transmit ACK frame 1140 to STA12.

[00121] It is assumed in this example that there is a protocol that allows low latency data of BSS2 to be transmitted during the rTWT SP without collision with data of BSS1.

[00122] In an embodiment, API and AP2 negotiate the e-rTWT parameter set prior to e-rTWT parameter set being announced. API and AP2 may negotiate the e-rTWT parameter set such that the rTWT SP can be shared by BSS1 and BSS2. In an embodiment, the rTWT SP is configured such that it includes a first section during which one or more members of BSS1, but not members of BSS2, are allowed to transmit data and a second section during which one or more members of BSS2, but not members of BSS1, are allowed to transmit data. Since API and AP2 can coordinate with each other to share the rTWT SP, the rTWT SP may be considered to be a “coordinated rTWT SP.”

[00123] Thus, members of an OBSS (e.g., BSS2) may be allowed to transmit low latency data during the rTWP SP of a BSS (e.g., BSS1), which reduces the delay of the OBSS low latency data. Also, members of the OBSS are restricted by the e-rTWT parameter set (e.g., so they end any transmissions before the rTWT SP of the BSS begins), which avoids collision.

[00124] Figure 12 is a diagram showing a frame exchange sequence for the second type of rTWT SP, according to some embodiments.

[00125] The second type of rTWT SP may allow a STA of the OBSS to contend for the channel during the rTWT SP of the BSS after certain conditions are met (e.g., the channel is idle for a predefined period of time).

[00126] As shown in the diagram, API may transmit beacon frame 1200 that includes an e- rTWT parameter set. The e-rTWT parameter set may include parameters for allowing members of BSS2 to transmit low latency data during the rTWT SP of BSS1 if the channel is idle for a predefined period of time. For example, the e-rTWT parameter set may include information regarding the length of the predefined period of time (although in some embodiments the length of time is hardcoded in the wireless networking standard). BSS1 is considered to be the rTWT holder in this scenario and the rTWT SP is for BSS1. Thus, BSS2 is considered to be an OBSS in this scenario.

[00127] All members of BSS 1 and BSS2 that receive beacon frame 1200 may end any TXOPs or transmissions before the rTWT SP begins.

[00128] During the rTWT SP, API may transmit trigger frame 1205 that solicits an uplink transmission from STA12. Responsive to receiving trigger frame 1205, STA12 may transmit data frame 1210 to API. Responsive to receiving data frame 1210, API may transmit ACK frame 1215 to STA12.

[00129] In this example, it is assumed that STA21 of BSS2 determines during the rTWT SP that it has low latency data to transmit to AP2. STA21 may contend for channel access during the rTWT SP of BSS1 if it determines that the channel is idle (e.g., it does not sense any Wi-Fi signals) for a predefined period of time (e.g., based on performing a clear channel assessment (CCA)). The channel could be idle for several reasons. For example, the channel could be idle due to API’s transmission terminating early due to the channel having good channel quality. In this example, it is assumed that the channel is idle for the predefined period of time and thus STA21 is able to transmit low latency data frame 1220 (that includes the low latency data) following a backoff period. Responsive to receiving low latency data frame 1220, AP2 may transmit ACK frame 1225 to STA21.

[00130] In an embodiment, the length of the predefined period of time is set as follows: Length of predefined period of time = aSIFSTime + AIFS[^4C], where aSIFSTime is the length of a short interframe space (SIFS) and AIFSfdC] is the length of an arbitration interframe space for a particular access category AC. The access category can be an existing access category used in IEEE 802.11 wireless networking standards or a newly defined access category to support low latency traffic. In an embodiment, API and AP2 negotiate the length of the predefined period of time prior to the e-rTWT parameter set being announced.

[00131] Subsequently, API may transmit another trigger frame 1230 during the rTWT SP that solicits an uplink transmission from STA12 (e.g., to solicit the transmission of aperiodic low latency data). STA12 may transmit data frame 1235 to API. Responsive to receiving data frame 1235, API may transmit ACK frame 1240 to ST Al 2.

[00132] Thus, members of an OBSS (e.g., BSS2) may be allowed to contend for the channel to transmit low latency data during the rTWP SP of a BSS (e.g., BSS1) if certain conditions are met (e.g., if the channel is idle for a predefined period of time), which can reduce the delay of the OBSS low latency data. Also, members of the OBSS are restricted by the e-rTWT parameter set (e.g., so they end any transmissions before the rTWT SP of the BSS begins and wait until the channel is idle for a predefined period of time before transmitting data during the rTWT SP), which avoids collision.

[00133] Figure 13 is a diagram showing a frame exchange sequence for the third type of rTWT SP, according to some embodiments.

[00134] The third type of rTWT SP may allow a member of the BSS and a member of the OBSS to concurrently transmit data during the rTWT SP by having the member of the BSS transmit data using a primary channel and having the member of the OBSS transmit data using a secondary channel.

[00135] As shown in the diagram, API may transmit beacon frame 1300 that includes an e- rTWT parameter set. The e-rTWT parameter set may include parameters for allowing members of BSS2 to transmit low latency data during the rTWT SP of BSS1 using a secondary channel. For example, the e-rTWT parameter set may include channel allocation information indicating that BSS2 is to use a secondary/non-primary channel for transmitting data during the rTWT SP. BSS1 is considered to be the rTWT holder in this scenario and the rTWT SP is for BSS1. Thus, BSS2 is considered to be an OBSS in this scenario.

[00136] The channel situation may be different in BSS1 and BSS2. For example, assuming there is a primary 80 MHz channel (denoted as “P80” in the diagram) and a secondary 80 MHz channel (denoted as “S80” in the diagram) available, the secondary 80 MHz channel might be busy in BSS1 but be idle in BSS2. Thus, in an embodiment, BSS1 and BSS2 may divide the channel in the frequency domain such that BSS1 uses the primary 80 MHz channel during the rTWT SP and BSS2 uses the secondary 80 MHz channel during the rTWT SP to avoid interference in a multi-BSS scenario. Information regarding the channel allocation may be included in beacon frame 1300 as part of the e-rTWT parameter set. The channel allocation between BSS1 and BSS2 may be predetermined or negotiated between API and AP2 (e.g., via beacon frame or management frames) prior to the announcement of the e-rTWT parameter set.

[00137] All members of BSS1 and BSS2 that receive beacon frame 1300 may end any TXOPs or transmissions before the rTWT SP begins.

[00138] During the rTWT SP, API may transmit trigger frame 1305 in the primary 80 MHz channel (P80) that solicits an uplink transmission from STA12. Responsive to receiving trigger frame 1305, STA12 may transmit data frame 1310 to API in the primary 80 MHz channel. Responsive to receiving data frame 1310, API may transmit ACK frame 1215 to STA12 in the primary 80 MHz channel.

[00139] Subsequently, API may transmit another trigger frame 1320 in the primary 80 MHz channel that solicits an uplink transmission from STA12. Responsive to receiving trigger frame 1320, STA12 may transmit data frame 1325 to API in the primary 80 MHz channel. In this example it is assumed that before STA12 transmits data frame 1325, STA21 of BSS2 determines that it has low latency data to transmit to AP2. STA21 may transmit low latency data frame 1330 (that include the low latency data) to AP2 in the secondary 80 MHz channel, concurrently with AP12’s transmission of data frame 1325 in the primary 80 MHz channel. Thus, data frame 1325 and low latency data frame 1330 may be concurrently transmitted during the rTWT SP without interference.

[00140] Responsive to receiving data frame 1325, API may transmit ACK frame 1335 in the primary 80 MHz channel. Response to receiving low latency data frame 1330, AP2 may transmit ACK frame 1340 in the secondary 80 MHz channel, concurrently with API’s transmission of ACK frame 1335. Thus, ACK frame 1335 and ACK frame 1340 may also be concurrently transmitted during the rTWT SP without interference. [00141] In an embodiment, API and AP2 are both aware of which channel is the primary channel. The operating bandwidths of API and AP2 may include the primary channel. API may announce an e-rTWT parameter set in the primary channel for scheduling a rTWT SP. AP2 may receive the e-RTWT parameter set and thus be aware of when the rTWT SP will begin and end. Before the rTWT SP begins, AP2 may transmit data using the primary channel. However, after the rTWT SP begins, AP2 may switch to transmitting data outside of API’s operating bandwidth (e.g., using a secondary/non-primary channel) to avoid interference. When the rTWT SP ends, AP2 may switch back to transmitting data using the primary channel.

[00142] Figure 14 is a diagram showing a channel division, according to some embodiments. [00143] As shown in the diagram, the frequency domain may include a primary 20 MHz channel, a secondary 20 MHz channel, and a secondary 40 MHz channel. Prior to the IEEE 802.1 Ibe wireless networking standard, STAs were not allowed to use a secondary channel if the primary channel was busy. However, in newer/future wireless networking standards, it is expected that a secondary channel can be used even if the primary channel is busy, which allows for more efficient usage of the spectrum. Thus, an OBSS STA may use the secondary channel to transmit data during a rTWT SP of a BSS to avoid interference. For example, as shown in the diagram, the operating bandwidth (OPBW) of the rTWT holder may only include the primary 20 MHz channel. In this case, the OBSS may use the secondary 20 MHz channel and/or the secondary 40 MHz channel to transmit data during the rTWT SP of the BSS. As another example, as shown in the diagram, the operating bandwidth of the rTWT holder may only include only the primary 20 MHz channel and the secondary 20 MHz channel (or the primary 40 MHz channel). In this case, the OBSS may use the secondary 40 MHz channel to transmit data during the rTWT SP of the BSS.

[00144] Turning now to Figure 15, a method 1500 will be described for scheduling a rTWT SP, in accordance with an example embodiment. The method 1500 may be performed by an AP of a BSS (e.g., API shown in Figure 8). The AP may be implemented by one or more devices described herein such as wireless device 104.

[00145] Additionally, although shown in a particular order, in some embodiments the operations of the method 1500 (and the other methods shown in the other figures) may be performed in a different order. For example, although the operations of the method 1500 are shown in a sequential order, some of the operations may be performed in partially or entirely overlapping time periods.

[00146] In an embodiment, at operation 1505, the AP negotiates characteristics of a restricted target wake time service period with an AP of an overlapping BSS that overlaps the BSS. [00147] Operation 1510 may be performed to schedule a first type of restricted target wake time service period. At operation 1510, the AP transmits a frame that includes restricted target wake time service period scheduling information for scheduling the restricted target wake time service period, wherein the restricted target wake time service period includes a first section during which one or more members of the BSS are allowed to transmit data and a second section (which does not overlap in time with the first section) during which one or more members of an OBSS that overlaps the BSS, but not members of the BSS, are allowed to transmit data. In an embodiment, the restricted target wake time service period scheduling information includes information regarding when the first section of the restricted target wake time service period occurs and information regarding when the second section of the restricted target wake time service period occurs. In an embodiment, the AP of the OBSS transmits a second frame that includes the same restricted target wake time service period scheduling information included in the frame transmitted by the AP of the BSS. In an embodiment, the frame is a beacon frame. In an embodiment, the frame is a probe response frame or a management frame. In an embodiment, members of the BSS and members of the OBSS that receive the frame are to end any transmissions before the restricted target wake time service period begins.

[00148] Operation 1515 may be performed to schedule a second type of restricted target wake time service period. At operation 1510, the AP transmits a frame that includes restricted target wake time service period scheduling information for scheduling the restricted target wake time service period for the BSS, wherein a members of the OBSS is allowed to transmit data during the restricted target wake time service period of the BSS after the member of the OBSS determines that a channel has been idle for a predefined period of time. In an embodiment, the restricted target wake time service period scheduling information includes information regarding a length of the predefined period of time. In an embodiment, the AP of the OBSS transmits a second frame that includes the same restricted target wake time service period scheduling information included in the frame transmitted by the AP of the BSS. In an embodiment, the frame is a beacon frame. In an embodiment, the frame is a probe response frame or a management frame. In an embodiment, members of the BSS and members of the OBSS that receive the frame are to end any transmissions before the restricted target wake time service period begins.

[00149] Operation 1520 may be performed to schedule a third type of restricted target wake time service period. At operation 1520, the AP transmits a frame that includes restricted target wake time service period scheduling information for scheduling the restricted target wake time service period for the BSS, wherein one or more members of the BSS are allowed to transmit data during the restricted target wake time service period of the BSS using a primary channel, and wherein one or more members of the OBSS are allowed to transmit data during the restricted target wake time service period of the BSS using a secondary channel. The transmission by a member of the BSS and the transmission by a member of the OBSS may be concurrent. In an embodiment, the restricted target wake time service period scheduling information includes channel allocation regarding the primary channel and/or the secondary channel.

[00150] In an embodiment, the restricted target wake time service period scheduling information further includes (in addition to the information mentioned above) information regarding one or more of: an identifier of the restricted target wake time service period, an operating bandwidth for the first section of the restricted target wake time service period, an operating bandwidth for the second section of the restricted target wake time service period, a received signal strength indicator (RSSI) for the AP of the BSS, a RSSI for an AP of the OBSS (e.g., the RSSI may be used for coordinated spatial reuse purposes), a traffic identifier (TID) of traffic that is allowed to be transmitted during the first section of the restricted target wake time service period, a TID of traffic that is allowed to be transmitted during the second section of the restricted target wake time service period, a stream classification service identifier of a stream that is allowed to be transmitted during the first section of the restricted target wake time service period, a stream classification service identifier of a stream that is allowed to be transmitted during the second section of the restricted target wake time service period.

[00151] Turning now to Figure 16, a method 1600 will be described for transmitting data during a first type of rTWT SP, in accordance with an example embodiment. The method 1600 may be performed by an STA of an OBSS that overlaps a BSS (e.g., STA21 shown in Figure 8). The STA may be implemented by one or more devices described herein such as wireless device 104.

[00152] At operation 1605, the STA receives, from an AP, a frame that includes restricted target wake time service period scheduling information for scheduling a restricted target wake time service period, wherein the restricted target wake time service period includes a first section during which one or more members of the BSS are allowed to transmit data and a second section during which one or more members of the OBSS, but not members of the BSS, are allowed to transmit data. In an embodiment, the restricted target wake time service period scheduling information includes information regarding when the first section of the restricted target wake time service period occurs and information regarding when the second section of the restricted target wake time service period occurs. In an embodiment, the AP is an AP of the BSS (the AP belongs to a different BSS from the STA). In an embodiment, the AP is an AP of the OBSS (the AP belongs to the same BSS as the STA).

[00153] In an embodiment, the STA determines when the restricted target wake time service period occurs based on the restricted target wake time service period scheduling information and ends any transmissions before the restricted target wake time service period begins.

[00154] In an embodiment, at operation 1610, the STA determines when the first section of the restricted target wake time service period occurs based on the restricted target wake time service period scheduling information.

[00155] At operation 1615, the STA determines when second section of the restricted target wake time service period occurs based on the restricted target wake time service period scheduling information.

[00156] In an embodiment, at operation 1620, the STA refrains from transmitting during the first section of the restricted target wake time service period.

[00157] At operation 1625, the STA transmits a data frame during the second section of the restricted target wake time service period.

[00158] Turning now to Figure 17, a method 1700 will be described for transmitting data during a second type of rTWT SP, in accordance with an example embodiment. The method 1700 may be performed by a STA of an OBSS that overlaps a BSS (e.g., STA21 shown in Figure 8). The STA may be implemented by one or more devices described herein such as wireless device 104.

[00159] At operation 1705, the STA receives, from an AP, a frame that includes restricted target wake time service period scheduling information for scheduling a restricted target wake time service period for the BSS. In an embodiment, the AP is an AP of the BSS (the AP belongs to a different BSS from the STA). In an embodiment, the AP is an AP of the OBSS (the AP belongs to the same BSS as the STA).

[00160] At operation 1710, the STA performs channel sensing of a channel during the restricted target wake time service period.

[00161] At operation 1715, the STA determines whether the channel has been idle for a predefined period of time. If the channel has not been idle for the predefined period of time, the flow moves to operation 1710, at which the STA continues to perform channel sensing.

Otherwise, if the channel has been idle for the predefined period of time, the flow moves to operation 1720. In an embodiment, the restricted target wake time service period scheduling information includes information regarding the length of the predefined period of time. [00162] At operation 1720, the STA transmits a data frame during the restricted target wake time service period of the BSS.

[00163] Turning now to Figure 18, a method 1800 will be described for transmitting data during a third type of rTWT SP, in accordance with an example embodiment. The method 1800 may be performed by a STA of an OBSS that overlaps a BSS (e.g., STA21 shown in Figure 8). The STA may be implemented by one or more devices described herein such as wireless device 104.

[00164] At operation 1805, the STA receives, from an AP, a frame that includes restricted target wake time service period scheduling information for scheduling a restricted target wake time service period for the BSS. In an embodiment, the AP is an AP of the BSS (the AP belongs to a different BSS from the STA). In an embodiment, the AP is an AP of the OBSS (the AP belongs to the same BSS as the STA).

[00165] At operation 1810, the STA determines, based on the restricted target wake time service period scheduling information, that a secondary channel is to be used for transmission during the restricted target wake time service period of the BSS. In an embodiment, the restricted target wake time service period scheduling information includes channel allocation information regarding an allocation of a primary channel and/or the secondary channel.

[00166] At operation 1815, the STA transmits a data frame during the restricted target wake time service period of the BSS using the secondary channel, wherein one or more STAs of the BSS transmit data during the restricted target wake time service period of the BSS using the primary channel.

[00167] At operation 1820, responsive to determining that the restricted target wake time service period has ended, the STA switches to using the primary channel for transmission. [00168] 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.

[00169] 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.

[00170] 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-consi stent 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.

[00171] It should be borne 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.

[00172] 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. [00173] 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.

[00174] 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. [00175] 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

CLAIMS What is claimed is:

1. A method performed by a wireless device implementing an access point (AP) of a basic service set (BSS) in a wireless network, the method comprising: transmitting a frame that includes restricted target wake time service period scheduling information for scheduling a restricted target wake time service period that includes a first section during which one or more members of the BSS are allowed to transmit data and a second section during which one or more members of an overlapping BSS (OBSS) that overlaps the BSS, but not members of the BSS, are allowed to transmit data.

2. The method of claim 1, wherein the restricted target wake time service period scheduling information includes information regarding when the first section of the restricted target wake time service period occurs and information regarding when the second section of the restricted target wake time service period occurs.

3. The method of claim 2, wherein the restricted target wake time service period scheduling information further includes information regarding one or more of: an identifier of the restricted target wake time service period, an operating bandwidth for the first section of the restricted target wake time service period, an operating bandwidth for the second section of the restricted target wake time service period, a received signal strength indicator (RSSI) for the AP of the BSS, a RSSI for an AP of the OBSS, a traffic identifier (TID) of traffic that is allowed to be transmitted during the first section of the restricted target wake time service period, a TID of traffic that is allowed to be transmitted during the second section of the restricted target wake time service period, a stream classification service identifier of a stream that is allowed to be transmitted during the first section of the restricted target wake time service period, a stream classification service identifier of a stream that is allowed to be transmitted during the second section of the restricted target wake time service period.

4. The method of claim 1, further comprising: negotiating characteristics of the restricted target wake time service period with an AP of the OBSS.

5. The method of claim 4, wherein the AP of the OBSS transmits a second frame that includes the same restricted target wake time service period scheduling information included in the frame transmitted by the AP of the BSS.

6. The method of claim 1, wherein the frame is a beacon frame.

7. The method of claim 1, wherein the frame is a probe response frame or a management frame.

8. The method of claim 1, wherein members of the BSS and members of the OBSS that receive the frame are to end any transmissions before the restricted target wake time service period begins.

9. A method performed by a wireless device implementing a station (STA) of an overlapping basic service set (OBSS) that overlaps a basic service set (BSS) in a wireless network, the method comprising: receiving, from an access point (AP), a frame that includes restricted target wake time service period scheduling information for scheduling a restricted target wake time service period, wherein the restricted target wake time service period includes a first section during which one or more members of the BSS are allowed to transmit data and a second section during which one or more members of the OBSS, but not members of the BSS, are allowed to transmit data; determining when the second section of the restricted target wake time service period occurs based on the restricted target wake time service period scheduling information; and transmitting a data frame during the second section of the restricted target wake time service period.

10. The method of claim 9, further comprising: determining when the first section of the restricted target wake time service period occurs based on the restricted target wake time service period scheduling information; and refraining from transmitting during the first section of the restricted target wake time service period.

11. The method of claim 9, wherein the AP is an AP of the BSS.

12. The method of claim 9, wherein the AP is an AP of the OBSS.

13. The method of claim 9, further comprising: determining when the restricted target wake time service period occurs based on the restricted target wake time service period scheduling information; and ending any transmission before the restricted target wake time service period begins.

14. A wireless device to operate in a wireless network, the first 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 wireless device to perform the method steps of any one of claims 1-8.

15. A wireless device to operate in a wireless network, the first 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 wireless device to perform the method steps of any one of claims 9-13.