Unified connectivity management approach for managing connectivity in a wireless network that has multi-link operation capabilities

Abstract

A method performed by a station (STA) that has multi-link operation (MLO) capability to manage connectivity using a unified connectivity management approach. The method includes determining a link quality of multi-link device (MLD) links between the STA and a relay STA, determining a first expected network performance if the STA were to use MLO relay operations based on the link quality of the MLD links between the STA and the relay STA, determining a link quality of MLD links between the STA and a second AP, determining a second expected network performance if the STA were to seamlessly roam to the second AP based on the link quality of the MLD links between the STA and the second AP, and determining whether to use MLO relay operations or seamlessly roam to the second AP based on comparing the first expected network performance with the second expected network performance.

Description

SPECIFICATIONUNIFIED CONNECTIVITY MANAGEMENT APPROACH FOR MANAGING CONNECTIVITY IN A WIRELESS NETWORK THAT HAS MULTI-LINK OPERATION CAPABILITIESCROSS-REFERENCE TO RELATED APPLICATION

[0001] This application claims the benefit of U.S. Provisional Application No. 63 / 571,980, filed March 29, 2024, titled “Seamless Roaming for Multi-link devices in Relay-enabled 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 a unified connectivity management approach for managing connectivity in a wireless network that has multi-link operation (MLO) capabilities.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. The IEEE 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. Currently under development, 802.1 Ibe aims to significantly improve upon the capabilities of its predecessor, 802.1 lax / 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 tosimultaneously use multiple frequency bands and channels for enhanced performance and reliability. Additionally, 802. l lbe 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, 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] A multi-link device (MLD) is a device that is capable of transmitting and receiving traffic over multiple links in different channels / bands. A MLD may implement multi-link operation (MLO). Multi-link operation (MLO) is a technology that enables devices to transmit and receive traffic over multiple links in different channels / bands.

[0006] Current research trends for future IEEE 802.11 wireless networks (e.g., IEEE 802.1 Ibn Ultra-High Rate (UHR) wireless networks) focus on achieving seamless roaming using MLO technology. The objective is to ensure uninterrupted connectivity for stations (STAs) moving within wireless network environments. In existing IEEE 802.11 wireless networks, the traditional (single link (non-MLO)) roaming scheme for non-access point (non-AP) stations (STAs) involves a time-consuming process that requires 802. IX re-authentication and a 4-way handshake, which may result in packet loss or transmission interruptions when roaming.

[0007] With the introduction of the IEEE 802.1 Ibe Extremely High Throughput (EHT) wireless networking standard and MLO technology, non-AP STA MLDs may communicate with multiple AP MLDs over multiple links concurrently. This advancement can facilitate seamless roaming, ensuring uninterrupted transmission as STAs transition between APs. Recent approaches and solutions focus on extending the existing IEEE 802.11 wireless networking standard to support seamless roaming. Seamless roaming may help enhance wireless network performance and the end user experience.

[0008] Relay technology may help enhance wireless network coverage and throughput. With relay technology, a relay STA that is communicatively situated between an AP and a non-AP STA may relay traffic between the AP and the non-AP STA to improve reliability and throughput for the non-AP STA. Relay technology can be enhanced by leveraging MLO capabilities. For example, consider a scenario where a non-AP STA MLD equipped with two radios, operating in the 2.4 GHz and 5 GHz bands respectively, reaches the boundary of an AP's 5 GHz coverage area, experiencing weak link condition. In such a situation, the non-AP STA MLD may establish a 5 GHz link to the AP via a relay STA MLD that is communicativelysituated between the AP and the non-AP STA, thereby extending the coverage area and ensuring seamless connectivity even in areas with weak signal conditions beyond the AP's 5 GHz coverage area.BRIEF DESCRIPTION OF THE DRAWINGS

[0009] 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.

[0010] 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.

[0011] Figure 2 is a schematic diagram of a wireless device, in accordance with some embodiments of the present disclosure.

[0012] Figure 3A illustrates components of a wireless device configured to transmit data, in accordance with some embodiments of the present disclosure.

[0013] Figure 3B illustrates components of a wireless device configured to receive data, in accordance with some embodiments of the present disclosure.

[0014] Figure 4 illustrates interframe space (IFS) relationships, in accordance with some embodiments of the present disclosure.

[0015] Figure 5 illustrates a Carrier Sense Multiple Access with Collision Avoidance (CSMA / CA)-based frame transmission procedure, in accordance with some embodiments of the present disclosure.

[0016] 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.

[0017] 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.

[0018] 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.

[0019] Figure 9 illustrates an example of an access point sending a trigger frame to multiple associated stations and receiving Uplink Orthogonal Frequency-Division Multiple AccessTrigger-Based Physical Protocol Data Units (UL OFDMA TB PPDUs) in response, in accordance with some embodiments of the present disclosure.

[0020] Figure 10 is a diagram showing a wireless network environment that includes an AP, relay STAs, and STAs that have MLO capability in a 2.4 GHz band and a 5 GHz band, according to some embodiments.

[0021] 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.

[0022] Figure 12 is a diagram showing a relay STA MLD that can relay traffic between an AP MLD and a non-AP STA MLD using MLO relay operations, according to some embodiments.

[0023] Figure 13 is a diagram showing an extended service set (ESS) comprising two BSSs in which MLO seamless roaming may occur, according to some embodiments.

[0024] Figure 14 is a diagram showing the architecture of MLDs that can perform MLO seamless roaming, according to some embodiments.

[0025] Figure 15 is a diagram showing a MLO seamless roaming procedure, according to some embodiments.

[0026] Figure 16 is a diagram showing frame exchange sequence for performing a MLO seamless roaming procedure, according to some embodiments.

[0027] Figure 17 is a diagram showing the possible ways for a non-AP STA MLD to seamlessly maintain connectivity, according to some embodiments.

[0028] Figure 18 is a diagram showing a table of MLO relay supportability types, according to some embodiments.

[0029] Figure 19 is a diagram showing a device that includes a unified connectivity management component, according to some embodiments.

[0030] Figure 20 is a diagram showing a unified connectivity management architecture for seamlessly maintaining connectivity, according to some embodiments.

[0031] Figure 21 is a flow diagram showing a method for making a decision between MLO relay operations and MLO seamless roaming to maintain connectivity, according to some embodiments.

[0032] Figure 22 is a diagram showing a frame exchange sequence for deciding between using MLO relay operations or MLO seamless roaming to maintain seamless connectivity, according to some embodiments.

[0033] Figure 23 is a flow diagram of a method for managing connectivity using a unified connectivity management approach, according to some embodiments.DETAILED DESCRIPTION

[0034] The present disclosure generally relates to wireless communications, and more specifically, relates to a unified connectivity management approach for managing connectivity in a wireless network that has multi-link operation (MLO) capabilities. As will be described in additional detail herein, the unified connectivity management approach may consider multi-link operation (MLO) relay operations and MLO seamless roaming when deciding how to maintain connectivity.

[0035] As mentioned above, MLO technology may help facilitate seamless roaming in a wireless network. Also, relay operations may leverage MLO technology to extend the wireless network coverage area. It is recognized by the present disclosure that a non-access point (non- AP) station (STA) multi-link device (MLD) that is experiencing weak link conditions (poor link quality) may maintain connectivity by using MLO relay operations to continue communicating with the currently associated access point (AP) or by seamlessly roaming to a neighboring AP using a MLO seamless roaming procedure. That is, the non-AP STA MLD has the flexibility to either use MLO relay operations or MLO seamless roaming to maintain connectivity.Therefore, it is important to comprehensively consider both options when deciding how to maintain connectivity. However, current research in the wireless networking field has not yet explored an approach that considers both MLO relay operations and MLO seamless roaming when deciding how to maintain connectivity.

[0036] The present disclosure introduces a unified connectivity management approach that considers MLO relay operations and MLO seamless roaming when deciding how to maintain connectivity. In an embodiment, a non-AP STA MLD includes a link / MAC layer component, referred to herein as a unified connectivity management component, that is responsible for deciding whether to use MLO relay operations or MLO seamless roaming to maintain connectivity. Various methods are disclosed herein to allow a non-AP STA to maintain connectivity.

[0037] According to some embodiments, a non-AP STA MLD that has MLO capability may determine whether a link quality of MLD links between the STA and a first AP (which may be the AP that the STA is currently associated with) is poorer than a link quality threshold. The MLD links between the STA and the first AP may include a link operating in a first channel (e.g., a channel in the 2.4 Gigahertz (GHz) band) and a link operating in a second channel (e.g., a channel in the 5 GHz band). If the STA determines that the link quality of the MLD links between the STA and the first AP is poorer than the link quality threshold (e.g., the link quality of the link operating in the first channel deteriorates), the STA may determine a link quality ofMLD links between the STA and a relay STA (that is capable of relaying traffic between the STA and the first AP). The MLD links between the STA and the relay STA may also include a link operating in the first channel and a link operating in the second channel. The STA may determine a first expected network performance if the STA were to use MLO relay operations (to communicate with the first AP) based on the link quality of the MLD links between the STA and the relay STA. The STA may determine a link quality of MLD links between the STA and a second AP (which may be a neighboring AP). The MLD links between the STA and the second AP may also include a link operating in the first channel and a link operating in the second channel. The STA may determine a second expected network performance if the STA were to seamlessly roam to the second AP based on the link quality of the MLD links between the STA and the second AP. The STA may then determine whether to use MLO relay operations via the relay STA or to seamlessly roam to the second AP based on comparing the first expected network performance with the second expected network performance. For example, the STA may determine to use MLO relay operations if the first expected network performance is better than the second expected network performance, but otherwise determine to seamlessly roam to the second AP. If the STA determines to use MLO relay operations, the STA may start communicating with the first AP using MLO relay operations via the relay STA. Otherwise, if the STA determines to seamlessly roam to the second AP, the STA may perform a MLO seamless roaming procedure to seamlessly roam to the second AP. In this way, the STA may follow a unified connectivity management approach that takes both MLO relay operations and MLO seamless roaming into consideration when deciding how to maintain connectivity. Previous connectivity management approaches do not comprehensively consider MLO relay operations and MLO seamless roaming when deciding how to maintain connectivity. In an embodiment, the STA includes a unified connectivity management component that is responsible for determining whether to use MLO relay operations or roam to a new AP to maintain connectivity, as described herein.

[0038] The unified connectivity management approach described herein may allow a STA that is experiencing weak link conditions to maintain / improve connectivity in a manner that optimizes network performance (e.g., optimize reliability and / or throughput for the STA).

[0039] 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.

[0040] 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.

[0041] 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.

[0042] 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 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).

[0043] 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 inputinterfaces 234, the output interfaces 236, and the RF transceiver 240 may communicate with each other via a bus 260.

[0044] 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.

[0045] 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.

[0046] 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.

[0047] 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.

[0048] 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.

[0049] 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 abeam-formed antenna array. In an embodiment, the antennas in the antenna unit 250 may be directional antennas, which may be fixed or steerable.

[0050] 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.

[0051] 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.

[0052] 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.

[0053] 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.

[0054] 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.

[0055] 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.

[0056] 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.

[0057] 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 theencoder 300 performs BCC encoding and otherwise may output the stream output from the encoder 300 without changing the order of the bits therein.

[0058] 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.

[0059] 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.

[0060] 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.

[0061] 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.

[0062] When the TxSP 324 performs a MIMO or MU-MIMO transmission, some blocks before the spatial mapper may be provided for each user.

[0063] 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.

[0064] 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.

[0065] 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.

[0066] The RxSP 326 includes a GI remover 318, a Fourier transformer (FT) 316, a demapper 314, a deinterleaver 312, and a decoder 310.

[0067] 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.

[0068] 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.

[0069] 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.

[0070] 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.

[0071] 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.

[0072] 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.

[0073] 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.

[0074] 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.

[0075] 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.

[0076] 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 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.

[0077] 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 thedata frame after performing backoff if a DIFS has elapsed during which the medium has been idle.

[0078] 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.

[0079] 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.

[0080] 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.

[0081] 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.

[0082] 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.

[0083] 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.

[0084] 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.

[0085] 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.

[0086] 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.

[0087] 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 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).

[0088] When the station STA3 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 STA3 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.

[0089] 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 framehas 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.

[0090] 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.

[0091] 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.

[0092] 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 support applications 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.

[0093] 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.

[0094] 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 lowlatency 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.

[0095] 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.

[0096] 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., 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.

[0097] 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.

[0098] 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), and Repeated Legacy Signal Field (RL-SIG). These fields are used to maintain compatibility with older Wi-Fi standards.

[0099] 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.

[0100] Figure 7 provides a more detailed description of each field in the EHT PPDU frame, including their purposes and characteristics.

[0101] 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.

[0102] 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, incertain 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.

[0103] 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.

[0104] 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.

[0105] 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.

[0106] In the IEEE 802.1 lax 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).

[0107] 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.

[0108] 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.

[0109] 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.

[0110] 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.

[0111] 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.

[0112] 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.

[0113] 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 decodethe 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.

[0114] 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.

[0115] 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.

[0116] 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.

[0117] The operation of various AP coordination schemes has been discussed in theIEEE 802.1 Ibe and UHR standards:

[0118] 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.

[0119] Coordinated OFDMA (C-OFDMA): APs transmit on orthogonal frequency resources by coordinating and splitting the spectrum, enabling more efficient spectrum utilization.

[0120] Joint Transmission (JTX): Multiple APs transmit jointly to a given user simultaneously by sharing data between the APs.

[0121] Coordinated Spatial Reuse (C-SR): Multiple APs or STAs adjust their transmit power to reduce interference between APs.

[0122] By implementing these AP coordination schemes, WLAN systems can improve their overall throughput and efficiency by leveraging the cooperation between multiple APs.

[0123] The present disclosure introduces a unified connectivity management approach that takes MLO relay operations and MLO seamless roaming into consideration when deciding how to maintain / improve connectivity. With the unified connectivity management approach, a non- AP STA MLD that has MLO capability and that is experiencing weak link conditions may decide to maintain / improve connectivity by communicating with its currently associated AP using MLO relay operations or by seamlessly roaming to another AP using a MLO seamless roaming procedure, depending on which option is expected to lead to better network performance for the non-AP STA MLD.

[0124] The concept of MLO relay operations is now described to provide helpful context.

[0125] Figure 10 is a diagram showing a wireless network environment that includes an AP, relay STAs, and STAs that have MLO capability in a 2.4 GHz band and a 5 GHz band, according to some embodiments.

[0126] 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 1020, and STAs 1030 may be MLDs that are capable of MLO. Unlike traditional non- MLD APs and non-MLD STAs, MLD APs and MLD STAs may have multiple wireless interfaces and may be capable of MLO in multiple channels / bands. In this example, it is assumed that the AP 1010, relay STAs 1020, and non-relay STAs 1030 are 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 thatMLDs having multiple wireless interfaces may still have a unique MAC instance at the upper layers, without losing the independent parameters of each wireless interface.

[0127] 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 area in the 2.4 GHz band may extend further than the AP’s 1010 coverage area in the 5 GHz band (due to the 2.4 GHz band being a lower frequency band).

[0128] A relay STA 1020 may be a special type of non-AP STA that can relay traffic between devices. For example, relay STA 1020-1 may relay traffic between the AP 1010 and STA 1030-2 and also relay traffic between the AP 1010 and STA 1030-5. Also, relaySTA 1020-2 may relay traffic between AP 1010 and STA 1030-3 and also relay traffic between the AP 1010 and STA 1030-4. The use of relay operations may provide improved quality of service (QoS) (e.g., improved range, reliability, and throughput) to STAs 1030 in the BSS.Since the relay STAs 1020 are MLDs having MLO capability in the first channel (in the 2.4 GHz band) and the second channel (in the 5 GHz band), the relay STAs 1020 may relay traffic in the 2.4 GHz band and / or the 5 GHz band depending on the situation / needs. That is, the relay STAs 1020 may be capable of providing MLO relay operations.

[0129] While embodiments will primarily be described herein in a context where there are two MLD links (e.g., one link operating in the 2.4 GHz band and one link operating in the 5 GHz band), it should be appreciated that the techniques described herein may be generalized to environments with more than two MLD links.

[0130] Various concepts and embodiments will be described herein in the context of the wireless network environment shown in Figure 10. It should be appreciated, however, that the approach described herein may be applicable to other wireless network environments having a different configuration.

[0131] 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.

[0132] 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 MLO, 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 andSTA1 and a second link (“Link2”) between AP2 and STA2, where Linkl and Link2 operate in different channels / bands.

[0133] Figure 12 is a diagram showing a relay STA MLD that can relay traffic between an AP MLD and a non-AP STA MLD using MLO relay operations, according to some embodiments.

[0134] 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.

[0135] API and STA1 may communicate with each other via rSTAl in the first channel. 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 via rSTA2 in the second channel. 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.

[0136] The concept of MLO seamless roaming is now described to provide helpful context.

[0137] Figure 13 is a diagram showing an extended service set (ESS) comprising two BSSs in which MLO seamless roaming may occur, according to some embodiments.

[0138] As shown in the diagram, the ESS 1350 may include a first AP MLD 1310-1 (“AP MLD1”) that operates a first BSS and a second AP MLD 1310-2 (“AP MLD2”) that operates a second BSS. The AP MLDs 1310 may operate their respective BSSs in both the 2.4 GHz band and the 5 GHz band (using two wireless interfaces). An AP’s 1030 coverage area in the 2.4 GHz band may extend further than the AP’s 1030 coverage area in the 5 GHz band (due tothe 2.4 GHz band being a lower frequency band). As shown in the diagram, the coverage areas of AP MLD1 1310-1 and AP MLD2 1310-2 may overlap.

[0139] The ESS may also include multiple non-AP STA MLDs (STA 1030-1, STA 1030-2, and STA 1330-3). The ESS may also include a relay STA 1320 that can relay traffic between an AP 1310 and a STA 1030. For example, the relay STA 1320 may relay traffic between AP MLD1 1310-1 and STA 1030-2.

[0140] AP MLD1 1310-1 and AP MLD2 1310-2 may be connected to a centralized distribution system (DS) controller 1360 of the network via a wired and / or wireless backhaul links. The DS controller 1360 may be a logical component that connects multiple APs together and that may distribute traffic across the network.

[0141] A STA 1330 may initially be associated with one of the AP MLDs 1310 in the ESS 1350. As the STA 1330 moves around, the STA 1330 may seamlessly roam to another AP 1310 using a MLO seamless roaming procedure. For example, STA 1330-1 may initially be connected to AP MLD1 1310-1 but may then seamlessly roam to AP MLD2 1310-2 using a MLO seamless roaming procedure when it enters the coverage area of AP MLD2 1310-2. A MLO seamless roaming procedure is shown in Figure 15 and further described herein.

[0142] Figure 14 is a diagram showing the architecture of MLDs that can perform MLO seamless roaming, according to some embodiments.

[0143] As shown in the diagram, a wireless network environment may include a distribution system (DS) controller, two AP MLDs (AP MLD 1410-1 and AP MLD 1410-2) and a non-AP STA MLD 1430.

[0144] Each AP MLD 1410 may include a logical link layer (LLC) component and an upper MAC (U-MAC) component. The LLC component may serve as an interface between the LT- MAC component and the network layer, facilitating protocol multiplexing, flow control, and error control functions. It may enable multiple network protocols to operate over the same wireless link, manage data flow between devices, and / or assist in detecting or correcting transmission errors to enhance communication reliability. While the MAC layer, particularly the U-MAC component, handles many of these tasks in wireless networks, the LLC component may provide additional protocol management and may ensure seamless upper-layer integration. The U-MAC component may perform management and decision-making functionality regarding roaming. The U-MAC component may be connected to N lower MAC (L-MAC) components. The AL-MAC components may be connected to N physical wireless interfaces (“PHY 0” to “PHY A’). The N physical wireless interfaces may implement N wireless links (“Link 0” to “Link A’). The U-MAC component may also be connected to the upper service access point (U-SAP) component 1460 of the DS controller. The U-SAP component 1460 may represent the upper layer service access point with which the non-AP STA MLD 1430 is logically associated with to connect to the network.

[0145] The non-AP STA MLD1 1430 may have similar components as the AP MLDs (e.g., including a LLC component, a U-MAC component, L-MAC components, and physical wireless interfaces). The non-AP STA MLD1 1430 may initially be connected to AP MLD1 1410-1 through multiple links (e.g., Links 0 to A) implemented by the multiple physical wireless interfaces (PHY 0 to PHY N). If the non-AP STA MLD 1430 enters the coverage area of AP MLD2 1410-2, the non-AP STA MLD 1430 may seamlessly roam to AP MLD2 1410-2 using a MLO seamless roaming procedure.

[0146] As another example of MLO seamless roaming, in the scenario depicted in Figure 13, the non-AP STA 1330-1 may initially be connected to AP MLD1 1310-1 through a 2.4 GHz link and a 5 GHz link. As the non-AP STA 1330-1 moves around, it may partially enter the 2.4 GHz coverage area of AP MLD2 1310-2 while still being able to maintain connectivity with AP MLD 1310-1 (e.g., through the 5 GHz link). In this scenario, the non-AP STA 1330-1 may seamlessly roam to AP MLD2 1310-2 using a MLO seamless roaming procedure. An example MLO seamless roaming procedure is now described.

[0147] Figure 15 is a diagram showing a MLO seamless roaming procedure, according to some embodiments.

[0148] As shown in the diagram, a STA 1530-1 may initially be connected to AP MLD1 1510-1 through two MLD links (“LinkO” and “Linkl”). The STA 1530-1 may periodically assess the link quality of the MLD links based on management frames transmitted by AP MLD1 1510-1 and may decide to roam to AP MLD2 1510-2 if the STA 1530-1 is within the coverage area of AP MLD2 1510-2 and the MLD links with AP MLD1 1510-1 have poor link quality. As used herein, LinkO may be a link that operates in a first channel (e.g., a 2.4 GHz channel) and Linkl may be a link that operates in a second channel (e.g., a 5 GHz channel).

[0149] As shown in the diagram, if the non-AP STA MLD 1530-1 decides to roam to AP MLD2 1510-2, it may disconnect LinkO from AP MLD1 1510-1 and establish a new link with AP MLD2 1510-2 in the same channel. The STA 1530-1 may maintain Linkl with AP MLD1 1510-1 until the new link with AP MLD2 1510-2 is established. Thus, the STA 1530 may be connected to AP MLD1 1510-1 through Linkl and connected to AP MLD2 1510-2 through LinkO for a period of time. During this period of time, the STA 1530 is said to be in a roaming transition state. During the roaming transition state, the DS U-SAP 1550 may direct downlink (DL) traffic for the STA 1530-1 to either AP MLD1 1510-1 or AP MLD2 1510-2. APMLD1 1510-1 may transmit DL traffic to STA 1530-1 over Linkl with the STA 1530-1 and AP MLD2 1510-2 may transmit DL traffic to STA 1530-1 over LinkO with the STA 1530-1. After the new link (LinkO) with the AP MLD2 1510-2 is established, the STA 1530-1 may disconnect Linkl from AP MLD1 1510-1 and establish a new link with the neighboring AP MLD2 1510-2 in the same channel, which completes the MLO seamless roaming procedure. As a result, the STA 1530-1 is now connected to AP MLD2 1510-2 through two MLD links (LinkO and Linkl). The transition may be managed by the DS U-SAP 1550, completing the roaming process, including the re-authentication, and re-association. For example, the DS U-SAP 1550 may manage the MLO seamless roaming procedure by dynamically routing downlink traffic and coordinating link transitions. During the roaming transition state, it may direct traffic to either AP MLD1 or AP MLD2, ensuring that STA 1530-1 maintains continuous connectivity. It may also manage the re-authentication and re-association while maintaining at least one active link, preventing disruptions. Once the new link with AP MLD2 is established, the DS U-SAP may finalize the transition by disconnecting the old link, enabling seamless MLO roaming without delays. In this way, the STA 1530-1 may transition from being connected to AP MLD1 1510-1 to being connected to AP MLD2 1510-2 without experiencing delays (e.g., authentication delays) and interruptions that are typical with single-link roaming operations.

[0150] Figure 16 is a diagram showing frame exchange sequence for performing a MLO seamless roaming procedure, according to some embodiments.

[0151] As shown in the diagram, AP MLD1 1610-1 and AP MLD2 1610-2 may be connected to U-SAP 1650 (e.g., via a backhaul link). Also, as shown in the diagram, at step (1), the non- AP STA MLD 1630 may be connected to AP MLD1 1610-1 through LinkO and Linkl. At step (2), the non-AP STA MLD 1630 may periodically assess the link quality of its MLD links (LinkO and Linkl) based on management frames (e.g., beacon frame, power save polling (PS- Poll) frames, etc.) transmitted by AP MLD1 1610-1 and potential candidate AP MLDs (e.g., AP MLD2 1610-2). Various metrics can be used to assess link quality such as channel state information (CSI), received signal strength indicator (RSSI), signal-to-noise ratio (SNR), channel quality indicator (CQI), and the like. The non-AP STA MLD 1630 may consider roaming to AP MLD2 1610-2 if the link quality assessment indicates that the MLD links with AP MLD1 1610-1 have poor link quality. What is considered “poor” link quality may be configurable and depend on the implementation. At step (3), the non-AP STA MLD 1630 may probe the MLD links with a candidate AP MLD, which in this case is AP MLD2 1610-2. For example, the non-AP STA MLD 1630 may transmit a probe request frame to AP MLD2 1610-2 over LinkO. Responsive to receiving the probe request frame from non-AP STA MLD 1630over LinkO, AP MLD2 1610-2 may transmit a probe response frame to the non-AP STA MLD 1630 over Link 0. The non-AP STA MLD 1630 may also transmit a probe request frame to AP MLD2 1610-2 over Linkl. Responsive to receiving the probe request frame from non-AP STA MLD 1630 over Linkl, AP MLD2 1610-2 may transmit a probe response frame to the non- AP STA MLD 1630 over Link 1. At step (4), the non-AP STA MLD 1630 may assess the link quality of the MLD links with AP MLD2 1610-2 based on the probe response frames transmitted by AP MLD2 1610-2. At step (5), based on the results of the link quality assessment, the non-AP STA MLD 1630 may decide whether to roam to AP MLD2 1610-2 (the target AP) or to stay in the current BSS (stay connected to AP MLD1 1610-1). If the non-AP STA MLD 1630 decides to roam to AP MLD2 1610-2, it may perform the MLO seamless roaming procedure shown in Figure 15 or similar procedure to seamlessly roam to AP MLD2 1610-2.

[0152] As mentioned above, MLO relay operations can be used to extend the wireless network coverage area. When a non-AP STA MLD reaches the boundary of its associated AP’s coverage area (and thus experiences weak link conditions), it should have the option to choose between using MLO relay operations to continue communicating with its associated AP or seamlessly roaming to a neighboring AP using a MLO seamless roaming procedure. That is, MLO relay operations and MLO seamless roaming should be considered together. However, as mentioned above, the current research in the wireless networking field has not yet explored an approach that considers both MLO relay operations and MLO seamless roaming when deciding how to maintain / improve connectivity.

[0153] For example, consider the non-AP STA MLD 1330-2 in the scenario shown in Figure 13. This non-AP STA MLD 1330-2 may operate in a 2.4 GHz band and a 5 GHz band. When this non-AP STA MLD 1330-2 reaches the boundary of the AP MLD’s 1310-1 5 GHz coverage area, it may experience a weak link condition in the 5 GHz band. In such a situation, the non-AP STA MLD 1330-2 may stay connected to AP MLD 1310-1 in the 5 GHz band by using relay operations via the relay STA 1320, thereby extending coverage and ensuring seamless connectivity even in areas with weak signal conditions beyond the AP MLD’s 1310-1 5 GHz coverage area. Another option is for the non-AP STA MLD 1330-2 to seamlessly roam to AP MLD2 1310-2 using a MLO seamless roaming procedure to seamlessly maintain connectivity.

[0154] Figure 17 is a diagram showing the possible ways for a non-AP STA MLD to seamlessly maintain connectivity, according to some embodiments.

[0155] As shown in the diagram, a non-AP STA MLD 1730-1 may initially be connected to AP MLD1 1710-1 through two MLD links (“LinkO” and “Linkl”). When the link quality of the MLD links starts to deteriorate, the non-AP STA MLD 1730-1 may have two choices to maintain / improve connectivity. The first choice (choice #1) is to start communicating with the AP MLD1 1710-1 using MLO relay operations via a relay STA MLD 1720. The second choice (choice #2) is to seamlessly roam to a neighboring AP such as AP MLD2 1710-2 using a MLO seamless roaming procedure.

[0156] For example, as shown in the diagram, with choice #1, the non-AP STA MLD 1730-1 may improve the link quality of Linkl by communicating with AP MLD1 1710-1 using relay operations via the relay MLD 1720. Also, as shown in the diagram, with choice #2, the non-AP STA MLD 1730-1 may seamlessly roam to AP MLD2 1710-2 by disconnecting Linkl with AP MLD1 1710-1 and establishing Linkl with AP MLD2 1710-2, while maintaining LinkO with AP MLD1 1710-1. After establishing Linkl with AP MLD2 1710-2, the non-AP STA MLD 1730-1 may disconnect LinkO with AP MLD1 1710-1 and establish LinkO with AP MLD2 1710-2, thereby completing the MLO seamless roaming procedure (it is noted that the diagram shows the roaming transition state, before the MLO seamless roaming procedure is completed).

[0157] In view of the choices available to the non-AP STA MLD 1730-1 mentioned above, it is important for a non-AP STA MLD to consider both MLO relay operations and MLO seamless roaming when deciding how to seamlessly maintain / improve connectivity. For this purpose, a non-AP STA MLD may include a unified connectivity management component that can help determine whether the non-AP STA MLD should use MLO relay operations or seamlessly roam to a new AP to maintain seamless connectivity. In some cases, a non-AP STA MLD may already be communicating with an AP MLD using MLO relay operations via a relay STA. In such case, the non-AP STA MLD may use the techniques described herein to determine whether to keep using MLO relay operations or to seamlessly roam to a neighboring AP.

[0158] MLO relay operations may involve relay operations in multiple channels / bands in the downlink or uplink directions. The relay operations that are supported between an AP MLD and a non-AP STA MLD may depend on the status of the MLD links between the AP MLD and the STA MLD. The relay operations that are supported between an AP MLD and a non-AP STA may be classified into five MLO relay supportability types. As used herein, a MLO relay supportability type represents the relay operations that are possible between an AP MLD and a non-AP STA MLD.

[0159] Figure 18 is a diagram showing a table of MLO relay supportability types, according to some embodiments.

[0160] As shown in the table, relay operations that are supported 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 MLD 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 ” It should be appreciated, however, that other conventions for representing the MLO relay supportability type are possible.

[0161] 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 AP 1010 may communicate with each other directly (without using relay operations) but may not be able to communicate with each other using relay operations. As used herein, “direct” communication or similar language refers to communication that does not involve relay operations.

[0162] 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 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).

[0163] With MLO relay supportability type #2, the non-AP STA is able to receive beacon and other types of 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, AP 1010 may transmit traffic to STA 1030-3 directly (in the downlinkdirection) and STA 1030-3 may transmit traffic to AP 1010 (in the uplink direction) via relay STA 1020-2 (using relay operations).

[0164] 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, 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 (using relay operations) in the 5 GHz band.

[0165] 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 be able 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 AP 1010 may communicate with each other via relay STA 1020-1 (using relay operations) in both the 2.4 GHz band and the 5 GHz band.

[0166] A non-AP STA may determine its relay supportability status (e.g., relay supportability types 1 to 4) using certain methods defined by wireless networking standards or vendor-specific mechanisms based on the MLD link statuses and in cooperation with the AP. In an embodiment, a non-AP STA includes a relay control logic / component that can manage information related to the relay operations that are supported for the non-AP STA.

[0167] A concept, architecture, and method for the unified management of connectivity options such as MLO relay operations and MLO seamless roaming are described herein to enhance network flexibility, service continuity, and coverage optimization in wireless network environments. In an embodiment, a device may include a unified connectivity management component that is responsible for determining whether to use MLO relay operations or seamlessly roam to a new AP to maintain connectivity.

[0168] Figure 19 is a diagram showing a device that includes a unified connectivity management component, according to some embodiments.

[0169] As shown in the diagram, a non-AP STA MLD 1910 may include a unified connectivity management component 1920, a relay control logic / component 1930, a roaming control logic / component 1940, a MLD link status monitoring component 1950, and network interfaces 1960 for multiple MLD links.

[0170] The MLD link status monitoring component 1950 may reactively or passively monitor the link status of multiple MLD links (e.g., using the received signal strengths of transmissions received over the MLD links via the network interfaces 1960). The relay control logic / component 1940 may determine whether using MLO relay operations is possible and appropriate to maintain connectivity based on the monitoring results. The roaming control logic / component 1940 may determine whether seamlessly roaming to another AP is possible and appropriate to maintain connectivity based on the monitoring results.

[0171] The unified connectivity management component 1920 may be a logical component that is responsible for managing the connectivity of the non-AP STA MLD1910. The unified connectivity management component 1920 may be coupled to the MLD link status monitoring component 1950, the relay control logic / component 1930, and the roaming control logic / component 1940. The unified connectivity management component 1920 may interact with these other components to ensure seamless connectivity and to extended coverage across the DS.

[0172] For example, the unified connectivity management component 1920 may interact with the MLD link status monitoring component 1950 to detect when the link quality of MLD links becomes poorer than a link quality threshold. When the unified connectivity management component 1920 detects that the link quality of MLD links is poorer than the link quality threshold, the unified connectivity management component 1920 may interact with the relay control logic / component 1930 to determine whether it is possible to use MLO relay operations to maintain / improve connectivity and determine the expected network performance if the non- AP STA MLD 1910 were to use MLO relay operations. Also, the unified connectivity management component 1920 may interact with the roaming control logic / component 1940 to determine whether it is possible to seamlessly roam to a new AP and determine the expected network performance if the non-AP STA MLD 1910 were to seamlessly roam to the new AP. The unified connectivity management component 1920 may then determine whether it is better to use MLO relay operations or to seamlessly roam to the new AP to maintain connectivity based on comparing the respective expected network performances.

[0173] While the AP is not expected to perform roaming operations, the AP may include similar / corresponding components as the non-AP STA MLD 1910 to support MLO relay operations, facilitate MLO seamless roaming, and assist with implementing the unified connectivity management approach, as described elsewhere herein.

[0174] Figure 20 is a diagram showing a unified connectivity management architecture for seamlessly maintaining connectivity, according to some embodiments.

[0175] As shown in the diagram, a wireless network environment may include two AP MLDs (AP MLD 2010-1 and AP MLD 2010-2), a relay STA MLD 2020, and a non-AP STA MLD 2030.

[0176] Each device may include similar components as the devices shown in Figure 14 such as a LLC component, a U-MAC component, L-MAC components, and physical wireless interfaces. However, the U-MAC component may include a unified connectivity management component to perform management and decision-making functionality regarding how to maintain seamless connectivity, as described above and elsewhere herein.

[0177] The U-SAP component 2050 of the DS controller may include a unified connectivity management component 2055. The unified connectivity management component 2055 may be connected to the U-MAC of the devices in the wireless network environment to manage the connectivity of the non-AP STAs across the wireless network environment. For example, the unified connectivity management component 2055 of the U-SAP 2050 may manage information about all APs and STAs in the distribution system (DS). It may oversee connectivity details across different BSSs (including MLO relay connectivity information) and maintain essential data to enable flexible decision-making during roaming scenarios. By dynamically managing these connectivity parameters, it may ensure seamless roaming with minimal disruptions while maintaining reliable connectivity.

[0178] The non-AP STA MLD 2030 may initially be connected to AP MLD1 2010-1. The non-AP STA MLD 2030 may choose to use MLO relay operations via relay STA MLD 2020 to maintain connectivity with AP MLD1 2010-1 or seamlessly roam to AP MLD2 2010-2 using a MLO seamless roaming procedure to maintain connectivity. The unified connectivity management component of the non-AP STA MLD 2030 may perform operations described elsewhere herein to decide the best approach to seamlessly maintain / improve connectivity.

[0179] Figure 21 is a flow diagram showing a method for making a decision between MLO relay operations and MLO seamless roaming to maintain connectivity, according to some embodiments.

[0180] As shown in the diagram, the MLD link status monitoring component 2105 of a non- AP STA MLD may proactively or reactively monitor the link quality of MLD links with a currently associated AP MLD. The MLD link status monitoring component 2105 may assess the current link quality of the MLD links based on several factors such as traffic load, signal strength, and interference levels. At operation 2110, the MLD link status monitoring component 2105 may detect a change in the link quality (e.g., the signal strength falls below a predefined signal strength threshold) that triggers a relay vs. roaming evaluation procedure. Atoperation 2115, the non-AP STA MLD may determine whether any relay STAs exist in the current BSS. If one or more relay STAs exist in the current BSS, the relay control component 2120 may perform operation 2125 to check the relay status (whether the non-AP STA can use MLO relay operations via the relay STA) and assess the link quality or other performance metrics (e.g., expected throughput) for relaying. This operation may involve protocols that involve the exchange of management frames such as probing request frames, probing response frames, etc. At operation 2130, the non-AP STA may determine whether it is feasible to use MLO relay operations to stay connected to the currently associated AP. At operation 2135, the non-AP STA may assess the link quality or other performance metrics for roaming (to another AP). If the non-AP STA determined at operation 2130 that it is feasible to use MLO relay operations, at operation 2140, the non-AP STA may determine whether to use MLO relay operations or seamlessly roam to a new AP to maintain connectivity (e.g., based on comparing the expected network performance if the non-AP STA were to use MLO relay operations with the expected network performance if the non-AP STA were to seamlessly roam to the new AP). The expected network performance may be expressed / quantified using various metrics such as bit error rate (BER), signal-to-noise ratio (SNR), or the like. If the non-AP STA determines to use MLO relay operations, the flow may move to operation 2145. At operation 2145, the non-AP STA may start using MLO relay operations to communicate with the currently associated AP. If the non-AP STA determines at operation 2130 that it is not feasible to use relay operations or the non-AP STA determines at operation 2140 to use MLO seamless roaming, at operation 2155, the roaming control component 2150 may determine whether to roam to a new AP or not. In particular, the roaming control component 2150 may determine the expected network performance if the non-AP STA were to stay in the current BSS (no roaming) and the expected network performance if the non-AP STA were to seamlessly roam to the new AP. If the expected network performance for roaming exceeds the expected network performance for staying in the current BSS by more than a predefined threshold, the roaming control component 2150 may determine that the non-AP STA should roam to the new AP. If the roaming control component 2150 determines that the non-AP STA should roam to the new AP, at operation 2160, the non-AP STA may perform a MLO seamless roaming procedure to seamlessly roam to the new AP. Otherwise, if the roaming control component 2150 determines that the non-AP STA should not roam to the new AP, at operation 2165, the non-AP STA may stay in the current BSS.

[0181] Figure 22 is a diagram showing a frame exchange sequence for deciding between using MLO relay operations or MLO seamless roaming to maintain seamless connectivity, according to some embodiments.

[0182] As shown in the diagram, at step (1), the non-AP STA MLD 2230 may initially be connected to AP MLD1 2210-1 through two MLD links (LinkO and Linkl). Also, the relay STA MLD 2220 may be connected to AP MLD1 2210-1 through LinkO. At step (2), the non-AP STA MLD 2230 may assess the link quality of the MLD links. In this example, the link quality assessment result indicates that the link quality of the MLD links is deteriorating, which triggers the non-AP STA MLD 2230 to start a relay vs. roaming evaluation procedure. At step (3), the non-AP STA MLD 2230 may probe MLD links for the feasibility of using MLO relay operations. For example, as shown in the diagram, the non-AP STA MLD 2230 may transmit a relay probe request to AP MLD1 2210-1 over LinkO. Responsive to receiving the relay probe request from the non-AP STA MLD 2230 over LinkO, AP MLD1 2210-1 may transmit a PS-Poll frame to a candidate relay STA MLD 2220 over LinkO. The non-AP STA MLD 2230 may be able to overhear the PS-Poll frame transmitted by AP MLD1 2210-1 as depicted by the dashed arrow in the diagram. Responsive to receiving the PS-Poll frame from AP MLD 2210-1 over LinkO, the relay STA MLD 2220 may transmit a null data frame to the non-AP STA MLD 2230 over LinkO. AP MLD1 2210-1 may be able to overhear the null data frame transmitted by the relay STA MLD 2220 as depicted by the dashed arrow in the diagram. Also, responsive to receiving the relay probe request from the non-AP STA MLD 2230 over LinkO, APMLD1 2210-1 may transmit a PS-Poll frame to the relay STA MLD 2220 over Linkl. The non- AP STA MLD 2230 may be able to overhear the PS-Poll frame transmitted by AP MLD1 2210- 1 as depicted by the dashed arrow in the diagram. Responsive to receiving the PS-Poll frame from AP MLD 2210-1 over Linkl, the relay STA MLD 2220 may transmit a null data frame to the non-AP STA MLD 2230 over Linkl. AP MLD1 2210-1 may be able to overhear the null data frame transmitted by the relay STA MLD 2220 as depicted by the dashed arrow in the diagram.

[0183] Thus, the non-AP STA MLD 2230 may be able to receive the PS-Poll frames transmitted by AP MLD1 2210-1 over LinkO and Linkl and also be able to receive the null data frames transmitted by the relay STA MLD 2220 over LinkO and Linkl . Upon receiving these frames, at step (4), the unified connectivity management component of the non-AP STA MLD may determine the link quality of the MLD links (LinkO and Linkl) between the non-AP STA MLD 2230 and AP MLD 2210-1 based on the PS-Poll frames and determine the link quality of the MLD links (LinkO and Linkl) between the non-AP STA MLD 2230 and the relay STAMLD 2220 based on the null data frames. The unified connectivity management component may determine the expected network performance if the non-AP STA MLD 220-1 were to use MLO relay operations to stay connected to AP MLD1 2210-1 based on the link quality assessment results.

[0184] At operation (5), the non-AP STA MLD 2230 may probe the MLD links with a candidate AP MLD, which in this case is AP MLD2 2210-2. For example, the non-AP STA MLD 2230 may transmit a probe request frame to AP MLD2 2210-2 over LinkO. Responsive to receiving the probe request frame from non-AP STA MLD 2230 over LinkO, AP MLD2 2210-2 may transmit a probe response frame to the non-AP STA MLD 2230 over Link 0. The non-AP STA MLD 2230 may also transmit a probe request frame to AP MLD2 2210-2 over Linkl . Responsive to receiving the probe request frame from non-AP STA MLD 2230 over Linkl, AP MLD2 2210-2 may transmit a probe response frame to the non-AP STA MLD 2230 over Link 1. At step (6), the unified connectivity management component of the non-AP STA MLD 1630 may determine the link quality of the MLD links (LinkO and Linkl) with AP MLD2 2210-2. The unified connectivity management component may determine the expected network performance if the non-AP STA MLD 1630 were to seamlessly roam to AP MLD2 2210-2 based on the link quality assessment results. The unified connectivity management component may then decide whether to use MLO relay operations or seamlessly roam to AP MLD2 2210-2 based on comparing the expected network performance if the non-AP STA MLD 2230 were to use MLO relay operations to stay connected to AP MLD1 2210-1 and the expected network performance if the non-AP STA MLD 2230 were to seamlessly roam to AP MLD2 2210-2. If the non-AP STA MLD 2230 decides to use MLO relay operations, it may start communicating with AP MLD1 2210-1 using MLO relay operations via the relay STA MLD 2220. Otherwise, if the non-AP STA MLD 2230 decides to seamlessly roam to AP MLD2 2210-2, it may perform a MLO roaming procedure to seamlessly roam to AP MLD2 2210-2.

[0185] Turning now to Figure 23, a method 2300 will be described for managing connectivity using a unified connectivity management approach, in accordance with an example embodiment. The method 2300 may be performed by a STA. The STA may be implemented by a wireless device (e.g., wireless device 104).

[0186] Additionally, although shown in a particular order, in some embodiments the operations of the method 2300 (and the other methods shown in the other figures) may be performed in a different order. For example, although the operations of the method XX00 are shown in a sequential order, some of the operations may be performed in partially or entirely overlapping time periods.

[0187] At operation 2305, the STA determines a link quality of MLD links between the STA and a first AP. In an embodiment, the link quality of the MLD links between the STA and the first AP is determined based on management frames transmitted by the first AP.

[0188] At operation 2310, the STA determines whether the link quality of the MLD links between the STA and the first AP is poorer than a link quality threshold. If not, the flow may return to operation 2305. However, if the link quality of the MLD links is poorer than the link quality threshold, the flow may move to operation 2315.

[0189] At operation 2315, the STA determines a link quality of MLD links between the STA and a relay STA. In an embodiment, the STA transmits a relay probe request frame to the first AP to cause the first AP to transmit a first PS-Poll frame and a second PS-Poll frame, receives a first null data frame from the relay STA over a first link of the MLD links between the STA and the relay STA, wherein the first link operates in a first channel, wherein the relay STA transmitted the first null data frame in response to receiving the first PS-Poll frame from the first AP, and receives a second null data frame from the relay STA over a second link of the MLD links between the STA and the relay STA, wherein the second link operates in a second channel, wherein the relay STA transmitted the second null data frame in response to receiving the second PS-Poll frame from the first AP, wherein the link quality of the MLD links between the STA and the relay STA is determined based on the first null data frame and the second null data frame. In an embodiment, the first channel is in a 2.4 GHz band and the second channel is in a 5 GHz band.

[0190] At operation 2320, the STA determines a first expected network performance if the STA were to use MLO relay operations based on the link quality of the MLD links between the STA and the relay STA.

[0191] At operation 2325, the STA determines a link quality of MLD links between the STA and a second AP. In an embodiment, the STA transmits a first probe request frame to the second AP over a first link of the MLD links between the STA and the second AP, wherein the first link operates in a first channel, receives a first probe response from the second AP over the first link, transmits a second probe request frame to the second AP over a second link of the MLD links between the STA and the second AP, wherein the second link operates in a second channel, and receives a second probe response from the second AP over the second link, wherein the link quality of the MLD links between the STA and the second AP is determined based on the first probe response frame and the second probe response frame. In an embodiment, the first channel is in a 2.4 GHz band and the second channel is in a 5 GHz band.

[0192] At operation 2330, the STA determines a second expected network performance if the STA were to seamlessly roam to the second AP based on the link quality of the MLD links between the STA and the second AP.

[0193] At operation 2335, the STA determines whether to use MLO relay operations or seamlessly roam to the second AP based on comparing the first expected network performance with the second expected network performance.

[0194] At operation 2340, the STA determines whether to use MLO relay operations or to seamlessly roam to the second AP. If the STA determines to use MLO relay operations, the flow may move to operation 2345, where the STA starts communicating with the first AP using MLO relay operations via the relay STA. In an embodiment, the communicating with the first AP using MLO relay operations via the relay STA comprises any one of: communicating with the first AP using relay operations in a first channel and a second channel, wherein the STA also communicates directly with the AP in the first channel and the second channel (e.g., according to relay supportability type #1), communicating directly with the first AP in the first channel and communicating to the AP using relay operations in the second channel, wherein the AP directly communicates to the STA in the second channel (e.g., according to relay supportability type #2), communicating directly with the first AP in the first channel and communicating with the AP using relay operations in the second channel (e.g., according to relay supportability type #3), and communicating with the first AP using relay operations in the first channel and the second channel, wherein the STA does not communicate directly with the AP in the first channel and the second channel (e.g., according to relay supportability type #4).

[0195] Otherwise, if the STA determines to seamlessly roam to the second AP, the flow may move to operation 2350, where the STA performs a MLO seamless roaming procedure to roam to the second AP. In an embodiment, the performing the MLO roaming procedure comprises: disconnecting a first link of the MLD links between the STA and the first AP while maintaining a second link of the MLD links between the STA and the first AP, wherein the first link operates in a first channel and the second link operates in a second channel, establishing a third link between the STA and the second AP while maintaining the second link to enter a roaming transition state, wherein the third link operates in the first channel, after establishing the third link, disconnecting the second link, and establishing a fourth link between the STA and the second AP, wherein the fourth link operates in the second channel. In an embodiment, when the STA is in the roaming transition state, the STA receives data from the first AP over the second link and receiving data from the second AP over the third link.

[0196] In an embodiment, one or more of the operations mentions above are performed by a unified connectivity management component of the STA (e.g., which may reside at the link / MAC layer of the STA). For example, one or more of operations 2305-2340 may be performed by the unified connectivity management component.

[0197] 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.

[0198] 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.

[0199] 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.

[0200] 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.

[0201] 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.

[0202] 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.

[0203] 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.

[0204] 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 station (STA) that has multi-link operation (MLO) capability to manage connectivity using a unified connectivity management approach, the method comprising: determining whether a link quality of multi-link device (MLD) links between the STA and a first access point (AP) is poorer than a link quality threshold; responsive to determining that the link quality of the MLD links between the STA and the first AP is poorer than the link quality threshold, performing, by a unified connectivity management component, the following: determining a link quality of MLD links between the STA and a relay STA; determining a first expected network performance if the STA were to use MLO relay operations based on the link quality of the MLD links between the STA and the relay STA; determining a link quality of MLD links between the STA and a second AP; determining a second expected network performance if the STA were to seamlessly roam to the second AP based on the link quality of the MLD links between the STA and the second AP; and determining whether to use MLO relay operations or seamlessly roam to the second AP based on comparing the first expected network performance with the second expected network performance.

2. The method of claim 1, further comprising: transmitting a relay probe request frame to the first AP to cause the first AP to transmit a first power save polling (PS-Poll) frame and a second PS-Poll frame; receiving a first null data frame from the relay STA over a first link of the MLD links between the STA and the relay STA, wherein the first link operates in a first channel, wherein the relay STA transmitted the first null data frame in response to receiving the first PS-Poll frame from the first AP; and receiving a second null data frame from the relay STA over a second link of the MLD links between the STA and the relay STA, wherein the second link operates in a second channel, wherein the relay STA transmitted the second null data frame in response to receiving the second PS-Poll frame from the first AP,wherein the link quality of the MLD links between the STA and the relay STA is determined based on the first null data frame and the second null data frame.

3. The method of claim 2, wherein the first channel is in a 2.4 Gigahertz (GHz) band and the second channel is in a 5 GHz band.

4. The method of claim 1, further comprising: responsive to determining to use MLO relay operations, communicating with the first AP using MLO relay operations via the relay STA.

5. The method of claim 4, wherein the communicating with the first AP using MLO relay operations via the relay STA comprises any one of: communicating with the first AP using relay operations in a first channel and a second channel, wherein the STA also communicates directly with the AP in the first channel and the second channel; communicating directly with the first AP in the first channel and communicating to the AP using relay operations in the second channel, wherein the AP directly communicates to the STA in the second channel; communicating directly with the first AP in the first channel and communicating with the AP using relay operations in the second channel; and communicating with the first AP using relay operations in the first channel and the second channel, wherein the STA does not communicate directly with the AP in the first channel and the second channel.

6. The method of claim 1, further comprising: transmitting a first probe request frame to the second AP over a first link of the MLD links between the STA and the second AP, wherein the first link operates in a first channel; receiving a first probe response from the second AP over the first link; transmitting a second probe request frame to the second AP over a second link of the MLD links between the STA and the second AP, wherein the second link operates in a second channel; and receiving a second probe response from the second AP over the second link, wherein the link quality of the MLD links between the STA and the second AP is determined based on the first probe response frame and the second probe response frame.

7. The method of claim 6, wherein the first channel is in a 2.4 Gigahertz (GHz) band and the second channel is in a 5 GHz band.

8. The method of claim 1, further comprising: responsive to determining to seamlessly roam to the second AP, performing a MLO roaming procedure to roam to the second AP.

9. The method of claim 8, wherein the performing the MLO roaming procedure comprises: disconnecting a first link of the MLD links between the STA and the first AP while maintaining a second link of the MLD links between the STA and the first AP, wherein the first link operates in a first channel and the second link operates in a second channel; establishing a third link between the STA and the second AP while maintaining the second link to enter a roaming transition state, wherein the third link operates in the first channel; after establishing the third link, disconnecting the second link; and establishing a fourth link between the STA and the second AP, wherein the fourth link operates in the second channel.

10. The method of claim 9, further comprising: while in the roaming transition state, receiving data from the first AP over the second link and receiving data from the second AP over the third link.

11. The method of claim 1, wherein the link quality of the MLD links between the STA and the first AP is determined based on management frames transmitted by the first AP.

12. A wireless device to implement a 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 STA to perform the method of any one of claims 1-11.

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