COMMUNICATION APPARATUS AND METHOD FOR ENHANCED CLIENT DISCOVERY - Patent application

Abstract

The present disclosure provides a communications device and method for enhanced client discovery, the communications device comprising: circuitry configured, in operation, to generate a first frame; and a transmitter, in operation, to transmit the first frame to a second communications device to request information of a third communications device.

Description

[Technical field]

[0001] TECHNICAL FIELD The present disclosure relates to a communication apparatus and method for client discovery, and more particularly, for enhanced client discovery. [Background technology]

[0002] Wireless local area network (WLAN) sensing is under development by the Institute of Electrical and Electronics Engineers (IEEE) 802.11bf Task Group. The Task Group has proposed Sensing by Proxy (SBP), which allows a client to obtain sensing measurements by using multiple wireless links, but has not yet discussed the details of the protocol / procedure for obtaining information from one or more non-access point (non-AP) stations (STAs). Meanwhile, the IEEE 802.11be Task Group is developing specifications for Multi-Link Operation (MLO) / Multi-Link Device (MLD), which allows multiple stations to join an MLD.

[0003] Currently, Wi-Fi coverage of an entire house / office by multiple APs is very common, but measuring and reporting all possible links in the SBP reporting phase causes a large overhead on the Wi-Fi links used for reporting. Furthermore, the SBP initiator may have little knowledge about potential links for sensing measurements, such as links between an AP (or AP MLD) and other non-AP STAs (other non-AP MLDs), and links between STAs associated with an AP (or non-AP MLDs associated with an AP MLD) and other STAs / APs. Such a problem can be generalized as a client discovery problem.

[0004] Therefore, there is a need for a viable technical solution to address such problems, more specifically, a communication apparatus and method for enhanced client discovery that enables a non-AP STA (or non-AP MLD), e.g., an SBP initiator that needs to obtain information about potential links from an AP (or AP MLD) for a proper SBP procedure, to obtain information about potential links from the AP (or AP MLD).

[0005] Furthermore, other desirable features and characteristics will become apparent from the following detailed description and the appended claims, taken in conjunction with the accompanying drawings and this background of the disclosure. Summary of the Invention [Problem to be solved by the invention]

[0006] The non-limiting illustrative embodiments facilitate providing a communications apparatus and method for enhanced client discovery in wireless networks.

[0007] In a first aspect, the present disclosure provides a first communications device comprising: a circuit configured, in operation, to generate a first frame; and a transmitter, in operation, to transmit the first frame to a second communications device to request information of a third communications device.

[0008] In a second aspect, the present disclosure provides a second communications device comprising: a receiver configured, in operation, to receive a request frame from a first communications device requesting information of a third communications device; circuitry configured, in operation, to process the request frame and generate a response frame including the information; and a transmitter configured, in operation, to transmit the response frame to the first communications device.

[0009] In a third aspect, the present disclosure provides a communication method performed by a first communication device, the method including: generating a first frame; and transmitting the first frame to a second communication device to request information of a third communication device.

[0010] In a fourth aspect, the present disclosure provides a communication method implemented by a second communication device, the communication method including: receiving a request frame from a first communication device requesting information of a third communication device, processing the request frame, generating a response frame including the information, and transmitting the response frame to the first communication device.

[0011] It should be noted that the general or specific embodiments may be implemented as a system, a method, an integrated circuit, a computer program, a storage medium, or any selective combination thereof.

[0012] Further benefits and advantages of the disclosed embodiments will become apparent from the specification and drawings. Benefits and / or advantages may be obtained individually from the various embodiments and features of the specification and drawings, and it is not necessary that all of them are provided to obtain one or more of such benefits and / or advantages.

[0013] Embodiments of the present disclosure will be better understood and readily apparent to those skilled in the art from the following written description, by way of example only, taken in conjunction with the drawings in which: [Brief description of the drawings]

[0014] [Figure 1] 1 is a schematic diagram of single-user (SU) communication between an access point (AP) and a station (STA) in a multiple-input multiple-output (MIMO) wireless network. [Diagram 2] 1 is a schematic diagram of downlink multi-user (MU) communication between an AP and multiple STAs in a MIMO wireless network. [Diagram 3] 1 is a schematic diagram of trigger-based (TB) uplink MU communication between an AP and multiple STAs in a MIMO wireless network. [Figure 4] A schematic diagram showing communication between a STA (client 0) and an AP for a basic SBP procedure. [Diagram 5] FIG. 1 is a schematic diagram showing three wireless links between AP MLD and non-AP MLD. [Figure 6A] shows the format of the Neighbor Report element. [Figure 6B] shows the format of the reduced neighbor report element. [Figure 6C] 6B shows the format of the Neighbor AP Information field. [Figure 7] FIG. 2 is a schematic diagram showing a floor plan and devices arranged therein. [Figure 8] 1 is a schematic diagram of a communication device according to the present disclosure. [Figure 9] 4 illustrates a flowchart of a communication method performed by a first communication device according to various embodiments of the present disclosure. [Figure 10] 1 shows a flowchart illustrating a communication method implemented by a second communication device, such as an SBP responder, according to various embodiments of the present disclosure. [Figure 11] 1 shows a flowchart illustrating an example of an enhanced Level 1 and Level 2 client discovery procedure between a non-AP STA and an AP. [Figure 12] 1 shows a flowchart illustrating an example of an enhanced client discovery procedure at Level 1 and Level 2 between non-AP MLD and AP MLD. [Figure 13] 2 shows a flowchart illustrating an enhanced client discovery procedure between an AP and a non-AP STA according to a first embodiment of the present disclosure. [Figure 14] 1 shows a flowchart illustrating an enhanced client discovery procedure between AP MLD and non-AP MLD according to a first embodiment of the present disclosure; [Figure 15] 13 shows an example visualization of Level 1 and Level 2 enhanced client discovery results. [Figure 16]1 illustrates an example format of a Multi-Link Element (MLE) used for basic discovery according to one embodiment of the present disclosure. [Figure 17] 13 illustrates an example of a format of a multilink load factor used by AP MLD for basic discovery according to one embodiment of the present disclosure. [Figure 18] 1 illustrates an example of a format of a protected client discovery query frame used for a level 1 client discovery query according to an embodiment of the present disclosure. [Figure 19] 1 illustrates an exemplary format of a protected authorization validation request frame according to one embodiment of the present disclosure. [Figure 20] 1 illustrates an exemplary format of a protected authorization validation response frame, according to an embodiment of the present disclosure. [Figure 21] 1 illustrates an example format of a Level 1 client discovery response frame according to one embodiment of the present disclosure. [Figure 22] 13 illustrates another exemplary format of a Level 1 client discovery response frame, according to one embodiment of the present disclosure. [Figure 23] 23 illustrates an exemplary format of the MLD information element field of the protected client discovery response frame illustrated in FIG. 22. [Figure 24] 1 illustrates an example format of a protected client discovery query frame used for a level 2 client discovery query, according to one embodiment of the present disclosure. [Diagram 25] 1 illustrates an example format of a Level 2 client discovery response frame according to one embodiment of the present disclosure. [Figure 26] 13 illustrates another exemplary format of a Level 2 client discovery response frame, according to one embodiment of the present disclosure. [Figure 27] 27 illustrates an exemplary format of the MLD information element field of the protected client discovery response frame illustrated in FIG. 26. [Figure 28]1 is a flowchart illustrating an AP-triggered Level 3 client discovery procedure according to one embodiment of the present disclosure. [Figure 29] 1 is a flowchart illustrating a level 3 client discovery procedure triggered by AP MLD according to one embodiment of the present disclosure. [Diagram 30] FIG. 1 is a schematic diagram illustrating a multi-AP network deployment according to an embodiment of the present disclosure. [Diagram 31] FIG. 13 is a schematic diagram illustrating a tunnel-enhanced client discovery procedure according to a third embodiment of the present disclosure. [Diagram 32] 13 is a flowchart illustrating a tunnel-enhanced client discovery procedure between a non-AP STA1 and a non-AP STA2 according to a third embodiment of the present disclosure; [Figure 33A] 13 illustrates an example of a format of an enhanced client discovery Ethertype 89-0d data frame according to a third embodiment of the present disclosure. [Figure 33B] 3B illustrates an example of the contents of the payload field shown in FIG. 33A according to one embodiment of the present disclosure. [Diagram 34] 1 shows an example of the configuration of a communication device. [Diagram 35] 13 shows another example of the configuration of a communication device. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0015] Those skilled in the art will appreciate that elements in the figures are illustrated for simplicity and clarity and have not necessarily been drawn to scale. For example, the dimensions of some of the elements in the figures, block diagrams, or flow charts may be exaggerated relative to other elements to help facilitate an accurate understanding of embodiments of the present invention.

[0016] Some embodiments of the present disclosure are now described, by way of example only, with reference to the drawings in which like reference numbers and letters indicate similar elements or equivalents, and in which:

[0017] In the following paragraphs, certain exemplary embodiments are described with particular reference to an access point (AP) and a station (STA) for enhanced client discovery in a multiple-input multiple-output (MIMO) wireless network.

[0018] In the context of IEEE 802.11 (Wi-Fi) technology, a station, synonymously called a STA, is a communication device capable of using the 802.11 protocol. Based on the definition of IEEE 802.11-2016, a STA can be any device that includes an IEEE 802.11 compliant media access control (MAC) and physical layer (PHY) interface to the wireless medium (WM).

[0019] For example, an STA may be a laptop, a desktop personal computer (PC), a personal digital assistant (PDA), an access point, or a Wi-Fi phone in a wireless local area network (WLAN) environment. An STA may be fixed or mobile. In a WLAN environment, the terms "STA," "wireless client," "user," "user device," and "node" are often used synonymously.

[0020] Similarly, a wireless access point (AP), which is synonymously referred to in the context of IEEE 802.11 (Wi-Fi) technology, is a communications device that allows STAs in a WLAN to connect to a wired network. APs typically connect to a router (via the wired network) as standalone devices, but can also be integrated into or used within a router.

[0021] As mentioned above, a STA in a WLAN may function as an AP at another time, and vice versa. This is because a communication device in the context of IEEE 802.11 (Wi-Fi) technology may include both STA and AP hardware components. In this way, the communication device may switch between STA and AP modes based on actual WLAN conditions and / or requirements.

[0022] In a MIMO wireless network, "multiple" refers to multiple antennas used simultaneously for transmission and multiple antennas used simultaneously for reception across a wireless channel. In this regard, "multiple-input" refers to multiple transmit antennas that input wireless signals into a channel, and "multiple-output" refers to multiple receive antennas that receive wireless signals from the channel to a receiver. For example, in an N×M MIMO network system, N is the number of transmit antennas and M is the number of receive antennas, where N may or may not be equal to M. For simplicity, the respective numbers of transmit and receive antennas will not be discussed further in this disclosure.

[0023] In a MIMO wireless network, single-user (SU) and multi-user (MU) communications can be deployed for communication between communication devices such as APs and STAs. MIMO wireless networks have advantages such as spatial multiplexing and spatial diversity, which achieve higher data rates and robustness through the use of multiple spatial streams. According to various embodiments, the term "spatial stream" may be used interchangeably with the term "space-time stream" (i.e., STS).

[0024] FIG. 1 shows a schematic diagram of SU communication 100 between an AP 102 and a STA 104 in a MIMO wireless network. As shown, the MIMO wireless network may include one or more STAs (e.g., STA 104, STA 106, etc.). If the SU communication 100 in the channel is performed over the entire channel bandwidth, it is referred to as full-bandwidth SU communication. If the SU communication 100 in the channel is performed over a portion of the channel bandwidth (e.g., one or more 20 MHz subchannels in the channel are punctured), it is referred to as punctured SU communication. In the SU communication 100, the AP 102 transmits multiple space-time streams using multiple antennas (e.g., four antennas shown in FIG. 1), and all the space-time streams are directed to a single communication device, i.e., the STA 104. For simplicity, the multiple space-time streams directed to the STA 104 are shown as a grouped data transmission arrow 108 directed to the STA 104.

[0025] SU communication 100 can be configured for bidirectional transmission. As shown in FIG. 1, in SU communication 100, STA 104 may transmit multiple space-time streams using multiple antennas (e.g., two antennas shown in FIG. 1), with all space-time streams directed to AP 102. For simplicity, the multiple space-time streams directed to AP 102 are shown as grouped data transmission arrows 110 directed to AP 102.

[0026] Thus, the SU communication 100 shown in FIG. 1 enables both uplink and downlink SU transmissions in a MIMO wireless network.

[0027] FIG. 2 shows a schematic diagram of downlink MU (multiple-user) communication 200 between an AP 202 and multiple STAs 204, 206, 208 in a MIMO wireless network. The MIMO wireless network may include one or multiple STAs (e.g., STA 204, STA 206, STA 208, etc.). The MU communication 200 may be OFDMA (orthogonal frequency division multiple access) communication or MU-MIMO communication. For OFDMA communication on a channel, the AP 202 transmits multiple streams simultaneously to the STAs 204, 206, 208 in the network on different resource units (RUs) in the channel bandwidth. For MU-MIMO communication on a channel, the AP 202 uses multiple antennas to transmit multiple streams simultaneously to the STAs 204, 206, 208 on the same RU(s) in the channel bandwidth using spatial mapping or precoding techniques. When the RU(s) in which OFDMA or MU-MIMO communication takes place occupies the entire channel bandwidth, the OFDMA or MU-MIMO communication is referred to as full-bandwidth OFDMA or MU-MIMO communication. When the RU(s) in which OFDMA or MU-MIMO communication takes place occupies a portion of the channel bandwidth (e.g., one or more 20 MHz subchannels in the channel are punctured), the OFDMA or MU-MIMO communication is referred to as punctured OFDMA or MU-MIMO communication. For example, two space-time streams may be directed to the STA 206, another space-time stream may be directed to the STA 204, and yet another space-time stream may be directed to the STA 208. For simplicity, the two space-time streams directed to the STA 206 are shown as grouped data transmission arrow 212, the space-time stream directed to the STA 204 is shown as data transmission arrow 210, and the space-time stream directed to the STA 208 is shown as data transmission arrow 214.

[0028] To enable uplink MU transmissions, trigger-based communication is provided in a MIMO wireless network. In this regard, FIG. 3 shows a schematic diagram of trigger-based (TB) uplink MU communication 300 between an AP 302 and multiple STAs 304, 306, 308 in a MIMO wireless network.

[0029] Since there are multiple STAs 304, 306, 308 participating in trigger-based uplink MU communications, the AP 302 needs to coordinate the simultaneous transmissions of the multiple STAs 304, 306, 308.

[0030] To do so, as shown in Figure 3, the AP 302 simultaneously transmits trigger frames 310, 314, 318 to each of the STAs 304, 306, 308 to indicate user-specific resource allocation information (e.g., number of space-time streams, starting STS number, and assigned RU) that each STA can use. In response to the trigger frames, the STAs 304, 306, 308 may simultaneously transmit their respective space-time streams to the AP 302 according to the user-specific resource allocation information indicated in the trigger frames 310, 314, 318. For example, two space-time streams may be directed from the STA 306 to the AP 302, another space-time stream may be directed from the STA 304 to the AP 302, and yet another space-time stream may be directed from the STA 308 to the AP 302. For simplicity, the two space-time streams directed from STA 306 to AP 302 are shown as grouped data transmission arrow 316, the space-time stream directed from STA 304 to AP 302 is shown as data transmission arrow 312, and the space-time stream directed from STA 308 to AP 302 is shown as data transmission arrow 320.

[0031] Due to the packet / PPDU (physical layer protocol data unit) based transmission and distributed MAC (medium access control) scheme in 802.11 WLAN, time scheduling (e.g., periodic time slot allocation for data transmission similar to TDMA (time division multiple access)) does not exist in 802.11 WLAN. Scheduling of frequency and spatial resources is performed on a packet basis. In other words, resource allocation information is PPDU based.

[0032] According to various embodiments, the WLAN supports non-triggered communication as shown in Fig. 1 and triggered communication as shown in Fig. 2. In non-triggered communication, a communication device transmits a PPDU to one other communication device or two or more other communication devices without an explicit request. In triggered communication, a communication device transmits a PPDU to one other communication device or two or more other communication devices only after receiving a requesting trigger frame.

[0033] In this disclosure, the term "sensing initiator" refers to a device that initiates a sensing session with a STA (hereinafter also referred to as a "client") and requests sensing results from the STA. The term "sensing responder" refers to a STA that responds to the sensing initiator and participates in the sensing session. In the following various embodiments, unless otherwise specified, the initiator and the responder refer to the "sensing initiator" and the "sensing responder", respectively. Typically (e.g., in trigger-based (TB) sensing measurements), the initiator is an AP and the responder is a non-AP STA. However, this is not always the case, and sometimes a non-AP STA can also be the initiator and an AP can be the responder (e.g., in non-TB sensing measurements, or fine timing measurements (FTM) / ranging).

[0034] In contrast to the "sensing initiator" and "sensing responder," the term "sensing by proxy (SBP) initiator" refers to a STA that initiates an SBP procedure and requests a device (AP or sensing initiator) to become a proxy sensing initiator to initiate a sensing session and request sensing results from another STA (e.g., a client of the device) on its behalf. An "SBP responder" refers to a device that responds to the SBP initiator and agrees to be a proxy sensing initiator and participates in the SBP procedure. Note that the SBP initiator can be a sensing responder or one of multiple sensing responders of an SBP responder (sensing initiator).

[0035] As mentioned above, SBP is introduced in IEEE 802.11bf, which allows a client to obtain sensing measurements using multiple wireless links. FIG. 4 is a schematic diagram 400 showing communication between a STA (client 0) and an AP for a basic SBP procedure. According to the basic concept, the procedure of sensing by proxy includes SBP procedure setup, sensing measurement, SBP procedure report, and SBP procedure termination. During the SBP procedure setup, a client (e.g., client 0) requests the AP to obtain sensing measurements. The AP is configured to act as a proxy initiator for the requesting client. In various embodiments shown in this disclosure, such a requesting client is called an SBP requesting STA or SBP initiator, while the AP is called a proxy AP or SBP responder. The proxy is established by exchanging SBP request / response frames 412 between the SBP initiator and the SBP responder. The AP then performs sensing measurements with one or more clients (e.g., clients 1 and 2) by, for example, exchanging measurement setup request / response frames to establish a session and / or measurement report frames 414a, 414b during a measurement instance. In the example of FIG. 4, the SBP initiator is one of the clients, but the AP may also perform sensing measurements with the SBP initiator by exchanging associated frames 414c. During the SBP procedure report, the AP that obtains the measurement reports of the clients then reports them to the SBP initiator, for example, by sending an SBP report frame 414. After the SBP procedure report, the SBP procedure may be terminated at any time by either the SBP initiator or the SBP responder sending an SBP end frame (not shown).

[0036] Also, 802.11be introduces the idea of ​​MLD (Multi-Link Device), which allows multiple stations to be associated with an MLD, enabling seamless communication across multiple wireless links between two MLDs. FIG. 5 shows a schematic diagram 500 illustrating three wireless links between an AP MLD and a non-AP MLD. Specifically, three APs (AP1, AP2, AP3) operating at frequencies of 2.4 GHz, 5 GHz, and 6 GHz, respectively, are associated with the AP MLD, and three non-AP STAs (non-AP STA1, non-AP STA2, non-AP STA3) operating at frequencies of 2.4 GHz, 5 GHz, and 6 GHz, respectively, are associated with the non-AP MLD. AP1 and non-AP STA1 operating at a 2.4 GHz frequency communicate with each other via link 1, AP2 and non-AP STA2 operating at a 5 GHz frequency communicate with each other via link 2, and AP3 and non-AP STA3 operating at a 6 GHz frequency communicate with each other via link 3.

[0037] Also, according to 802.11be_D1.5, an EHT AP should have dot11MultiLinkActivated true, associate with an AP MLD, and the EHT AP and its associated AP MLD should follow the rules specified in 35.3 (Multi-link operation). This means that all EHT APs are associated with an AP MLD, and there are no standalone EHT APs. In other words, in the context of EHT WLAN, MLD is involved in SBP (e.g. as SBP initiator or SBP responder). However, no discussion on this has been done yet in 11bf.

[0038] Regarding obtaining information of APs, apart from an AP advertising its own information, IEEE 802.11 provides a container (e.g., a signal frame) for an AP to advertise information of neighboring APs. For example, an AP may include a Neighbor Report element or a Simplified Neighbor Report element in a beacon, a probe response frame, etc., to advertise information of neighboring APs. Figure 6A shows the format of a Neighbor Report element 600. The Neighbor Report element consists of an element identifier (ID) field, a length field, a Basic Service Set ID (BSSID) information field, an operation class field, a channel number field, a PHY type field, and optional sub-elements, which are 1, 1, 6, 5, 1, 1, 1, and a variable number of octets, respectively.

[0039] FIG 6B shows the format of the reduced neighbor report element 610. The reduced neighbor report element 610 has an element ID field, a length field, and a neighbor AP information field 620, each of which is 1, 1, and a variable number of octets. FIG 6C shows the format of the neighbor AP information field 620 in FIG 6B. Each neighbor AP information field 620 may include a Target Beacon Transmission Time (TBTT) information header field, an operating class field, a channel number field, and a TBTT information set field, each of which is 2, 1, 1, and a variable number of octets. However, these report elements 610, 620 are limited to AP advertisement and discovery.

[0040] As mentioned, there is a problem with client discovery in the SBP procedure. Since the coverage of the entire house / office / building / entity by multi-AP Wi-Fi (e.g., by mesh Wi-Fi or enterprise Wi-Fi network) is very common nowadays, blindly measuring and reporting all possible links in the SBP reporting phase will cause a large overhead in the Wi-Fi links used for reporting. Figure 7 shows a schematic diagram 700 showing a floor plan and the devices placed inside it. In this figure, non-AP MLD-1 is an SBP initiator 702 configured to perform presence discovery or tracking of people in the office premises, e.g., people entering the floor from any entrance such as door 704. As shown by the lines between the devices, there can be 15 links between the devices, but for a people tracking sensing application focused on people presence discovery in the vicinity of the door 704, only five links 706-710 (between STA-5, phone-1, AP MLD1, and non-AP MLD-1) may be of interest.

[0041] Also, the SBP initiator usually has little or no knowledge about potential links for sensing measurements. For example, links between an AP (or AP MLD) and other non-AP STAs (other non-AP MLDs), and links between STAs associated with an AP (or non-AP MLDs associated with an AP MLD) and other STAs / APs. Blindly requesting sensing measurements on all possible links would cause huge overhead in wireless networks. In fact, sensing measurements on many links may be of little or no interest to sensing applications. Here, WLAN sensing is taken as an example where information of other non-AP STAs is useful to other non-AP STAs, but its usefulness is not limited to sensing applications, but is useful for many other applications such as network visualization / troubleshooting, load balancing, etc.

[0042] This disclosure presents an enhanced client discovery that allows a non-AP STA (or a non-AP MLD) to obtain information about potential links from an AP (or an AP MLD). The links may be AP-to-STA links (e.g., Initiator-to-Responder link (I2R) or Responder-to-Initiator link (R2I)), STA-to-STA links (e.g., Responder-to-Responder link (R2R)). This disclosure also aims to propose related signaling and frame formats for enhanced client discovery.

[0043] Please note that the following various embodiments use SBP to describe enhanced client discovery to address client discovery problems and challenges. It is understood that such enhanced client discovery, which allows non-AP STAs (or non-AP MLDs) to access information about other non-AP STAs, can solve many other similar client discovery problems, such as wireless network visibility for administrators for network planning and troubleshooting, SBP setup for Wi-Fi load balancing, etc.

[0044] 8 is a schematic diagram of a communication device 800 according to the present disclosure. The communication device 800 may be implemented as a sensing initiator, a sensing responder, an SBP initiator, or an SBP responder.

[0045] As shown in Fig. 8, the communication device 800 may include a circuit 814, at least one wireless transmitter 802, at least one wireless receiver 804, and at least one antenna 812 (for simplicity, only one antenna is shown in Fig. 8 for illustration purposes). The circuit 814 may include at least one controller 806 for software and hardware assisted execution of tasks that the at least one controller 806 is designed to perform, including control of communications with one or more other communication devices in a MIMO wireless network. The circuit 814 may further include at least one transmit signal generator 808 and at least one receive signal processor 810. At least one control unit 806 may control at least one transmission signal generating unit 808 to generate MAC frames and PPDUs to be transmitted to one or more other communication devices via at least one wireless transmitting unit 802, where the MAC frames may be, for example, client discovery query / request / response frames, polling trigger frames, sounding trigger frames, NFRP trigger frames, and the PPDUs may be, for example, PPDUs used for non-trigger-based communication, PPDUs used for trigger-based sounding procedures, PPDUs used for trigger-based downlink transmissions when the communication device 800 is an AP, and PPDUs used for trigger-based uplink transmissions when the communication device 800 is a STA. At least one control unit 806 controls a receiving signal processing unit 810 for processing MAC frames and PPDUs received via at least one wireless receiving unit 804 from one or more other communication devices under the control of the at least one control unit 806, where the MAC frames may be, for example, client discovery query / request / response frames, polling trigger frames, sounding trigger frames, and NFRP trigger frames, and the PPDUs may be, for example, PPDUs used for non-trigger-based communication, PPDUs used for trigger-based sounding procedures, PPDUs used for trigger-based downlink transmissions when the communication device 800 is an AP, and PPDUs used for trigger-based uplink transmissions when the communication device 800 is a STA.At least one transmission signal generating unit 808 and at least one reception signal processing unit 810 may be standalone modules of the communication device 800 that communicate with at least one control unit 806 for the above-mentioned functions as shown in FIG. 8. Alternatively, at least one transmission signal generating unit 808 and at least one reception signal processing unit 810 may be included in at least one control unit 806. It is obvious to those skilled in the art that the arrangement of these functional modules is flexible and may vary according to actual needs and / or requirements. Data processing, storage, and other related control devices may be provided on a suitable circuit board and / or in a chipset. In various embodiments, in operation, at least one wireless transmitting unit 802, at least one wireless receiving unit 804, and at least one antenna 812 may be controlled by at least one control unit 806.

[0046] In operation, the communication device 800 provides functions required for enhanced client discovery. For example, the communication device 800 may be an SBP initiator, and the circuit 814 (e.g., at least one transmit signal generating unit 808 of the circuit 814) may generate a first frame, and the at least one wireless transmitting unit 802 may then transmit the first frame to an SBP responder to request information from the sensing responder.

[0047] In one embodiment, if one or more potential sensing response units are present, the circuitry 814 may generate a second frame, and the at least one wireless transmitter unit 802 may then transmit the second frame to request information of the particular potential sensing response unit.

[0048] In another embodiment, the at least one wireless receiver 804 may receive a validation request frame requesting validation information indicating that the communication device 800 is authorized to obtain information of the sensing responder. The circuit 814 (e.g., the at least one receive signal processor 810 and the at least one transmit signal generator 808 of the circuit 814) may be configured to process and generate a validation response frame including the validation information. The at least one wireless transmitter 802 may then transmit the validation response frame.

[0049] The communication device 800 may be a sensing SBP responder, and the at least one wireless receiver 804 receives a request frame from one non-AP STA, e.g., an SBP initiator, requesting information of another non-AP STA, e.g., a sensing responder. The circuit 814 (e.g., the at least one receiving signal processor 810 and the at least one transmitting signal generator 808 of the circuit 814) processes the request frame and generates a response frame including the information. The at least one wireless transmitter 802 may then transmit the response frame to the SBP initiator.

[0050] In one embodiment, the circuitry 814 (e.g., the at least one transmit signal generating unit 808 of the circuitry 814) may be further configured to generate a validation request frame to request validation information indicating that the requesting non-AP STA (e.g., the SBP initiator) is authorized to obtain information of the target non-AP STA (e.g., the sensing responder). The at least one wireless receiver 804 then receives a validation response frame including the validation information from the SBP initiator.

[0051] 9 shows a flowchart 900 illustrating a communication method implemented by a first communication device, such as an SBP initiator, according to various embodiments of the present disclosure. In step 902, a step of generating a first frame is performed. In step 904, a step of transmitting the first frame generated in step 902 to a second communication device, such as an SBP responder, to request information of a third communication, such as a sensing responder, is performed.

[0052] 10 shows a flowchart 1000 illustrating a communication method implemented by a second communication device, such as an SBP responder, according to various embodiments of the present disclosure. In step 1002, a step is performed of receiving a request for information of a third communication device, such as a sensing responder, from a first communication device, such as an SBP initiator. In step 1004, a step is performed of processing the request frame received in step 1002 and generating a response frame including the information. In step 1006, a step is performed of transmitting the response frame generated in step 1004 to the first communication device.

[0053] According to various embodiments of the present disclosure, the enhanced client discovery procedure consists of a client discovery query procedure and a client discovery response procedure, and there may be many levels of the enhanced client discovery procedure. A non-AP STA, e.g., an SBP initiator, may perform any one or more levels of client discovery.

[0054] For a Level 1 client discovery query, a non-AP STA requests the AP to provide a list of non-AP STAs (associated non-AP STAs and optionally associated non-AP STAs). In the request, the non-AP STA may also optionally specify discovery criteria such as (i) the STA's capabilities (PHY version (11ax, 11be, etc.), supported features (11bf, SBP, etc.), (ii) link metrics (minimum downlink / uplink received channel power indicator (RCPI) / received signal strength indicator (RSSI), maximum data rate, etc.), etc. It should be noted that a STA requesting enhanced client discovery does not have to be associated with an AP.

[0055] In a Level 1 Client Discovery Response, in response to a Level 1 Client Discovery Query, the AP provides information of a list of all associated non-AP STAs (e.g., MAC addresses or Association Identifiers (AIDs)) and, optionally, information of unassociated non-AP STAs that the AP has (e.g., Unassociated Identifiers (UIDs)). If Discovery criteria are provided in the query, the AP may provide a list of non-AP STAs that meet the Discovery criteria.

[0056] For a Level 2 client discovery query, a non-AP STA may request detailed information of a particular non-AP STA by indicating its ID (e.g., MAC address, or association identifier (AID) or unassociated identifier (UID)) in the query. Such ID may be obtained through the Level 1 client discovery query and response steps. In the request, the requesting non-AP STA may indicate whether it requests information about other devices that are within wireless range of the particular non-AP STA indicated. Note that a non-AP STA requesting enhanced client discovery does not need to be associated with an AP.

[0057] In a Level 2 Client Discovery Response, in response to a Level 2 Client Discovery Query, the AP provides detailed information about the indicated non-AP STA, such as (i) the STA's capabilities (PHY version (11ax, 11be, etc.), supported features (11bf, SBP, etc.), (ii) link metrics (minimum downlink / uplink RCPI / RSSI, maximum data rate, etc.), and (iii) if requested in the query, a list of other non-AP STAs and APs within wireless range of the indicated non-AP STA.

[0058] There is also Level 3 client discovery. More information about Level 3 client discovery queries and responses is described in detail below.

[0059] Essentially, the enhanced client discovery procedure described in this disclosure is different from the existing neighbor AP discovery procedure described above and in Figures 6A-6C, which is aimed at advertising and discovering APs, regardless of their level. The primary objective of the enhanced client discovery described in this disclosure is for discovering non-AP STAs.

[0060] FIG. 11 shows a flow chart 1100 illustrating an example of a level 1 and level 2 enhanced client discovery procedure between a non-AP STA and an AP. A non-AP STA may first perform level 1 enhanced client discovery by sending a client discovery query frame to the AP, which specifies the discovery criteria. No target clients (i.e., non-AP STAs or sensing responders) are identified. The AP then sends a client discovery response frame containing a list of the AP's clients that meet the discovery criteria. With this AP's client information, the non-AP STA may then perform level 2 enhanced client discovery by sending another client discovery query frame specifying the client's ID. A field (in this case, the neighbor field) is set to 1, indicating that information about the specified client's neighboring clients / neighboring devices (APs or non-APs) is also requested, i.e., information about clients / devices located within the wireless range of the specified client. The AP then sends another client discovery response frame containing the specified client's detailed information and other clients' detailed information within the wireless range of the specified client. Optionally, neighboring device / client discovery criteria, such as (i) STA capabilities (PHY version (11ax, 11be, etc.), supported features (11bf, SBP, etc.), and (ii) link metrics (minimum downlink / uplink RCPI / RSSI, maximum data rate, etc.), may be included in the client discovery query frame such that the AP will only transmit details of the specified client and details of other clients that are within wireless range of the specified client and meet the discovery criteria.

[0061] 12 shows a flowchart 1200 illustrating an example of enhanced client discovery procedures at levels 1 and 2 between a non-AP MLD and an AP MLD. For the enhanced client discovery procedures between MLDs, a client discovery query may indicate one or more affiliated APs of the AP MLB (B provided by the AP MLD) and may be addressed to any one affiliated AP of the AP MLD via any one link of the AP MLD.

[0062] The client discovery query frame may indicate a list of MLD associated APs in addition to discovery criteria to perform an enhanced client discovery procedure. In this case, STA1 associated with a non-AP MLD may perform level 1 enhanced client discovery by sending a client discovery query frame to AP2 associated with an AP MLD. The client discovery query frame may specify discovery criteria and may indicate a list of associated APs (e.g., AP1, AP2). The AP then transmits a client discovery response frame including a list of the indicated AP's non-MLD clients (e.g., AP1's clients, AP2's clients) as well as non-AP MLDs associated with the AP MLD and that meet the discovery criteria.

[0063] With the information of the AP's client, the non-AP STA may perform Level 2 enhanced client discovery by again sending another client discovery query frame to the AP MLD (via AP2) specifying the client's ID. A particular non-AP STA or non-AP MLD may be associated with other APs (e.g., clients of AP1) in the AP MLD. A field (in this case, the Neighbor field) is set to 1 to indicate that information about the specified client's neighboring clients / devices (APs or non-APs) located within the wireless range of the specified client is also requested. The AP MLD (via the associated AP) then sends another client discovery response frame containing detailed information of the specified client and other clients within the wireless range of the specified client.

[0064] In the following paragraphs, a first embodiment of the present disclosure illustrating an enhanced client discovery procedure between an AP and a non-AP STA (or an AP MLD and a non-AP MLD) is described.

[0065] FIG. 13 shows a flowchart 1300 illustrating an enhanced client discovery procedure between an AP and a non-AP STA according to a first embodiment of the present disclosure. The AP uses a beacon frame to advertise its capability for supporting enhanced client discovery and basic information of associated non-AP STAs (e.g., number / number of associated STAs, etc.). The non-AP STA may perform basic discovery to discover the AP's support of enhanced client discovery and the number of STAs associated with the AP. The non-AP STA may then associate and create a security association (SA) (or pre-association security negotiation) with the AP.

[0066] The non-AP STA then transmits a protected client discovery query frame to request basic information of other non-AP STAs associated with the AP. The protected client discovery query frame includes discovery criteria with the level field set to 1 to indicate a level 1 enhanced client discovery query. The AP may perform additional authorization verification by transmitting an authorization verification request frame to the non-AP STA to request verification information or authorization proof indicating that the non-AP STA is authorized to obtain information of other non-AP STAs. The non-AP STA then transmits in response an authorization verification response frame including verification information or authorization proof (e.g., a password) proving that the non-AP STA is authorized to obtain information of other non-AP STAs for enhanced client discovery.

[0067] If the authorization verification is successful, the steps shown in block 1302 are executed; otherwise, the steps shown in block 1304 are executed. In particular, if the authorization verification is successful, the AP sends a protected client discovery response frame to the non-AP STA, including information of a list of clients of the AP that meet the discovery criteria. Furthermore, the non-AP STA may send a second protected client discovery query frame to request detailed information of a specific non-AP STA (client) associated with the AP. This second protected client discovery query frame has a level field set to 2 to indicate a level 2 enhanced client discovery query, a client ID to identify the non-AP STA (client), and a neighbor field set to 1 to indicate information of neighboring devices / clients located within the range of the client.

[0068] Although not shown in the figure, upon receiving the Level 2 Client Discovery Query frame, the AP may trigger a neighboring client discovery request to each associated non-AP STA to discover information of neighboring STAs and APs. The AP then sends a protected client discovery response frame to the non-AP STAs, including detailed information of the indicated client and detailed information of the indicated client's neighboring STAs and APs.

[0069] If the authorization verification fails, the AP does not provide information about its associated non-AP STAs, but instead transmits a protected client discovery response frame with a status field indicating that the authorization verification failed.

[0070] In one example, if the AP has other means to verify the authorization of the non-AP STA to obtain information of other non-AP STAs, the exchange of authorization verification request / response frames may be skipped. For example, the AP may maintain a list of authorized devices, or may reference the list of authorized devices from a database such as a server.

[0071] FIG. 14 shows a flowchart 1400 illustrating an enhanced client discovery procedure between an AP MLD and a non-AP MLD according to the first embodiment of the present disclosure. The AP MLD uses a beacon frame to advertise the AP MLD's capability to support enhanced client discovery and basic information about associated non-AP MLDs and non-AP STAs (e.g., number / count of associated STAs, etc.). The non-AP MLD may perform basic discovery to discover the AP MLD's support of enhanced client discovery and the number of MLDs / STAs associated with the AP MLD. The non-AP MLD may then associate with the AP MLD and establish a security association (SA) (or pre-association security negotiation) with it.

[0072] The non-AP MLD (e.g., via STA1) then sends a protected client discovery query frame to the AP MLD (e.g., via AP2) to request basic information of other non-AP MLDs / STAs associated with the AP MLD or any of the affiliated APs. The protected client discovery query frame has the level field set to 1 to indicate a level 1 enhanced client discovery query, and includes discovery criteria and a list of affiliated APs (one or more associated APs) by any of the affiliated APs. The AP MLD may perform additional authorization verification to request verification information or authorization proof (e.g., a shared password) that it is authorized to obtain basic information of other non-AP MLDs / STAs by sending an authorization verification request frame to the non-AP MLD. The non-AP MLD then sends an authorization verification response frame including verification information or authorization proof (e.g., a password) in response to prove that the non-AP MLD is allowed to obtain information of other non-AP MLDs / STAs for enhanced client discovery.

[0073] If the authorization verification is successful, the steps shown in block 1402 are executed, otherwise, the steps shown in block 1404 are executed. In particular, if the authorization verification is successful, the AP MLD sends a protected client discovery response frame to the non-AP MLD, including information of a list of clients of the AP MLD that meet the discovery criteria. In addition, the non-AP MLD may further send a second protected client discovery query frame to the AP MLD to request detailed information of the STA (client) associated with the specific non-AP MLD / AP MLD or any affiliated AP. This second protected client discovery query frame has a level field set to 2 to indicate a level 2 enhanced client discovery query, a client ID to identify the non-AP MLD / STA (client), and a neighbor field set to 1 to indicate information of neighboring devices / clients located within the range of the client.

[0074] Although not shown in the figure, upon receiving the Level 2 Client Discovery Query frame, the AP MLD triggers a Neighbor Client Discovery Request to each of its associated non-AP MLDs / STAs to discover the information of neighboring STAs and APs. The AP MLD then sends a protected Client Discovery Response frame to the non-AP STAs, including the detailed information of the indicated client, as well as the detailed information of the indicated client's neighboring STAs and APs.

[0075] If the authorization verification fails, the AP MLD does not provide information about the associated non-AP MLD / STAs, but instead sends a protected client discovery response frame with a status field indicating that the authorization verification failed.

[0076] This procedure is also applicable when a non-AP STA is MLD aware (i.e., understands MLO-related signaling, e.g., multilink elements) and requests association information between the non-AP MLD and non-AP STAs associated with the associated AP from the AP MLD.

[0077] FIG. 15 shows an example of visualization of enhanced client discovery results for Level 1 and Level 2. Such visualization may be displayed on the screen of a laptop, a smartphone, or any electronic device. Note that in this example, an SBP initiator (not shown) may perform Level 1 client discovery and display only a list of AP / AP MLDs (in this case, four different APs (AP MLD1, AP MLD2, AP4, AP3)). Then, each AP sends its discovery result including a list of STAs (and / or MLDs) associated with the AP along with its basic information to the SBP initiator. They may be sorted in descending order according to link quality. Optionally, a list of non-associated STAs (and / or MLDs) known to the AP is also provided by the AP. In this example, AP MLD1 provides information of non-AP MLD1, STA5, and Phone1, AP MLD2 provides information of non-AP MLD2 and STA1, AP4 provides information of STA4 and STA6, and AP3 provides information of STA2 and STA3. The SBP initiator may additionally or alternatively perform level 2 client discovery. This level 2 client discovery may be triggered upon selection in a particular STA or non-AP MLD. In this example, non-AP MLD1 may be selected, and the SBP initiator performs level 2 client discovery in non-AP MLD1. A client discovery query frame including the ID of non-AP MLD1 is sent to AP MLD1. Thus, AP MLD1 provides information of neighboring APs, AP MLDs, STAs, non-AP MLDs (in this case STA5, Phone1, STA1, AP4, AP MLD2, and STA4) located within the wireless range of non-AP MLD1 and affiliated STAs of non-AP MLD1, as shown in block 1502.

[0078] FIG. 16 illustrates an example of a format of a Multilink Element (MLE) 1600 used for basic discovery according to one embodiment of the present disclosure. The MLE 1600 includes an Element ID field, a Length field, an Element ID Extension field, a Multilink Control field, a Common Information field, and a Link Information field. The Multilink Control field includes a Type subfield set to "Basic", and a Presence Bitmap subfield. The Common Information field may include an MLD Capability field and, in the case of an AP MLD, a Number of Associated Non-AP MLDs subfield. The Number of Associated Non-AP MLDs subfield is used to signal the total number of non-AP MLDs associated with the AP MLD. The MLD Capability subfield includes an AP Assistance Request (AAR) Support subfield and an Enhanced Client Discovery subfield. The AP MLD signals support for enhanced client discovery in the Enhanced Client Discovery subfield within the MLD Capability subfield.

[0079] The Link Information field has one or more Per-STA Profile Subelement subfields corresponding to one or more links (corresponding to associated STAs / APs), each of which has a Subelement ID field, a Length field, a STA Control field, a STA Information field, and a STA Profile field. The STA Control field includes a Link ID subfield. The STA Profile field has an Extended Capability Element subfield and, in the case of AP MLD, a BSS Load Element subfield. The BSS Load Element subfield has an Element ID field, a Length field, and a Number of Stations field. The Number of Stations field is used to signal the total number of STAs (non-MLD) associated with affiliated APs operating on the link. The Extended Capability Element subfield includes an Element ID field, a Length field, and an Extended Capability including an Enhanced Client Discovery subfield. An MLD STA or affiliated STA / AP signals support for enhanced client discovery in the Enhanced Client Discovery subfield in the Extended Capability field of the Extended Capability Element subfield.

[0080] For a STA / AP that is not an MLD, or an AP associated with an AP MLD that is a reporting STA / AP (i.e., the STA / AP that sends a frame carrying a basic Multi-Link element (MLE), the Extended Capability Element subfield and the BSS Load Element subfield are transmitted in the frame body (not in the basic MLE). For a non-AP MLD or an associated STA / AP of an AP MLD that is not a reporting AP (i.e., the STA / AP is a reported STA / AP), the Extended Capability Element subfield and the BSS Load Element subfield are transmitted in the Link Information field of the basic MLE. For an AP / AP MLD, the elements are transmitted in beacons, probe responses, (re)association response frames, etc. For a non-AP STA / MLD, the elements are transmitted in probe requests, (re)association request frames, etc.

[0081] FIG. 17 illustrates an example of a format of a multilink load element 1700 used by an AP MLD for basic discovery, according to one embodiment of the present disclosure. Instead of using MLE for basic discovery, an AP MLD can use a multilink load element 1700 transmitted in a beacon, probe response, (re)association response frame, etc., to signal the number of associated non-AP MLDs, as well as the number of non-MLD STAs associated with each of its associated APs. The multilink load element has an element ID field, a length field, an element ID extension field, an associated non-AP MLD count field, a link ID bitmap field, and one or more link load fields. The associated non-AP MLD count field is used to signal the total number of associated non-AP MLDs. Each link load field comprises a total STA count subfield, a channel utilization subfield, an effective STA count subfield, and a BSS utilization subfield. The total STA count subfield is used to signal the number of STAs (non-MLDs) associated with affiliated APs operating on the link.

[0082] FIG. 18 illustrates an example format of a protected client discovery query frame 1800 used for a level 1 client discovery query, according to one embodiment of the present disclosure. The protected client discovery query frame 1800 includes a MAC header (Frame Control field, Duration field, Recipient Address (RA) field, Transmitter Address (TA) field), a category field set to "Protected Discovery", an action field set to "Protected Client Discovery Query", a dialog token field, a client discovery mode field, a client discovery request element field, and a Frame Checking Sequence (FCS) field. Note that client discovery may be set to 0, 1, or 2, representing levels 1, 2, and 3 client discovery, respectively. In this case, the client discovery mode field is set to 0 since the protected client discovery query frame 1800 is used for a level 1 client discovery query.

[0083] The client discovery request element field includes an element ID field, a length field, an element ID extension field, a discovery criteria bitmap field, a PHY version bitmap field, a supported features bitmap field, a link metrics field, an operating channel width field, an MLD information field, and a BSSID list field. The discovery criteria bitmap field has a target STA information present subfield, a PHY version present subfield, a supported features present subfield, a link metrics present subfield, an operating channel width present subfield, an MLD information present subfield, and a BSSID list present subfield, and indicates the presence of additional fields used as criteria for selecting a STA / non-AP MLD. The target STA information present subfield is set to 0 in Level 1 client discovery. The PHY version bitmap field has a high throughput (HT) subfield, a very high throughput (VHT) subfield, a high efficiency (HE) subfield, and an extremely high efficiency (EHT) subfield, and indicates the PHY version supported by the STA / non-AP MLD. The Supported Features Bitmap indicates features supported by the target non-AP STA and includes a Tunnelled Direct Link Setup (TDLS) Support subfield, a WLAN Sensing subfield, and an SBP subfield, etc., and indicates features supported by the STA / non-AP MLD. The Link Metrics field has a Min RSSI / RCPI subfield and a Min Data Rate subfield, and indicates link metrics supported by the STA / non-AP MLD. The link metrics are measured between the STA and the associated AP. The Operating Channel Width field indicates the operating channel width of the discovered STA. The MLD Information field is present only if the frame is addressed to an AP affiliated with an AP MLD, and includes an MLD ID subfield carrying the MLD ID of the AP MLD, as well as a Link ID Bitmap subfield carrying the link for which information is requested.

[0084] If the BSSID List field is present, information of non-AP STAs associated with all BSSIDs is requested. If the BSSID List field is not present, by default a non-MLD AP will only provide information about non-AP STAs associated with itself, while an AP MLD will provide information about non-AP STAs associated with all associated APs in addition to information about associated non-AP MLDs.

[0085] Additionally, the discovery criteria bitmap field may include a "device location" bit (not shown) that, if set, indicates that device location elements (defined in IEEE 802.11-2020) and coverage area information (e.g., signal strength radius) are included in the client discovery query frame to indicate the target geographic location (e.g., within an RSSI / RCPI radius of -62 dBm) where the non-AP STA or non-AP MLD is expected to be located. The discovery criteria bitmap field may also include a "include associated STA / MLDs only" bit (not shown) to indicate that, if the bit is set to 1, information about non-AP STA / MLDs that are not associated with the AP / AP MLD is not requested, or, if the bit is set to 0, in the client discovery response, the AP / AP MLD may include information about non-AP STA / MLDs that are not associated with the AP / AP MLD.

[0086] 19 illustrates an example format of a protected authorization validation request frame 1900 according to one embodiment of the present disclosure. The protected authorization validation request frame 1900 comprises a MAC header (Frame Control, Duration, RA, and TA fields), a Category field set to "Protected Discovery", an Action field set to "Protected Authorization Validation Request Frame", a Dialog Token field, a Verification Mode field, and an FCS field. The Verification Mode field may be set to 0 to indicate a plaintext password or 1 to indicate a hashed password.

[0087] FIG. 20 illustrates an exemplary format of a protected authorization validation response frame 2000 according to one embodiment of the present disclosure. The protected authorization validation response frame 2000 includes a MAC header (frame control, duration, RA, and TA fields), a category field set to "protected discovery", an action field set to "protected authorization validation response frame", a dialog token field, a verification mode field, a verification information field, and an FCS field. The verification information field includes a PN / TSF field, a length field, and a verification text field. The PN / TSF field transmits a packet number or a time synchronization function used as a random data (salt) added during hashing to prevent replay attacks. The length field indicates the length of the verification text transmitted in the verification text field, which transmits a plain text password or a hashed password based on the verification mode field.

[0088] As described above, if the AP has other means for verifying whether a non-AP STA other than the AP has the authority to obtain information about other non-AP STAs, the authorization verification request / response may be omitted. For example, the AP may hold a list of authorized devices, or the AP may refer to the list of authorized devices from a database such as a server.

[0089] For example, the hashed password may be HA-256(Key, PN / TSF || "plaintext password"), where Key is a common private secret key known to both parties, e.g., the PTK generated during security association, or it may be a separate application-specific secret key (e.g., passed by a higher layer application) intended only for use with enhanced client discovery. Here, "||" is the concatenation operation, and PN / TSF is the value of the PN / TSF field, and the sender should ensure that the same value is not used twice to prevent replay attacks. For example, it may be a monotonically increasing number or may contain the current value of the sender's time synchronization function (TSF).

[0090] FIG. 21 illustrates an example format of a Level 1 client discovery response frame 2100 according to one embodiment of the present disclosure. The client discovery response frame 2100 is transmitted between a non-MLD SBP initiator and a responder. The client discovery response frame 2100 comprises a MAC header (Frame Control, Duration, RA, and TA fields), a Category field set to "Protected Discovery", an Action field set to "Protected Client Discovery Response", a Dialog Token field, a Client Discovery Mode field set to 0 to indicate Level 1 client discovery, a Status Code field, a Client Information Element field, and an FCS field. The Client Information Element field has an Element ID field, a Length field, an Element ID Extension field, a STA Information Control field, and a STA Information List field. The STA Information Control field comprises a Number of STAs subfield, a Neighbor STAs bit, and a Presence Bitmap subfield. The Number of STAs subfield indicates the number of STA information fields present in the STA Information List field (one for each non-AP STA). The Neighbor STA bit is set to 0 to indicate that the STA Information List carries information of associated STAs (and optionally non-associated AP STAs within range of the AP). The Presence Bitmap subfield indicates which fields are present in the STA Information field, and includes a MAC Address Present subfield, an Internet Protocol (IP) Address Present subfield, an Operating Channel Width Present subfield, a UL RSSI / RCPI Present subfield, a Data Rate Present subfield, and a BSSID Present subfield. The STA Information List field comprises one or more STA Information fields.Each STA Information field carries information of each associated non-AP STA that meets the discovery criteria indicated in the client discovery query frame, and has a MAC Address subfield that carries the MAC address of the non-AP STA, an Internet Protocol (IP) Address subfield, an Operating Channel Width subfield, a UL RSSI / RCPI subfield, and a BSSID subfield that carries the BSSID of the associated AP.

[0091] In addition, the STA information field may also include the STA's (e.g., Basic, HT, VHT, HE, EHT, WLAN sensing capability element, HT, VHT, HE, EHT operation element, etc.) capability and operation parameters (not shown). The STA information may also include a device type field (e.g., laptop, PC, smartphone, smart appliance, etc.) and a device location element (defined in IEEE 802.11-2020), which indicates the geographic location (e.g., within a 10 m radius) where the non-AP STA or non-AP MLD is located. If the STA information conveys information of a DMG (Directional Multi-Gigabit or 802.11ad) STA or an EDMG (Enhanced Directional Multi-Gigabit or 802.11ay) STA, the STA information field may also carry a sector selection subfield (not shown), which may include the value of the Sector ID subfield of the SSW field in the frame received with the best quality in the previous sector sweep. The Sector ID subfield is set to indicate the sector number in which the frame containing this SSW field is transmitted.

[0092] If the discovery criteria bitmap in the query frame further includes a "include only associated STAs" bit, then information of non-AP STAs not associated with the AP in the client discovery response frame is not included if the bit is set to 1, and the AP may include information of non-AP STAs not associated with the AP in the client discovery response frame if the bit is set to 0. Note that the AP may maintain a list of non-associated non-AP STAs that have previously engaged in a frame exchange (e.g., probe request / response) or attempted to associate with the AP, or have been disassociated from the AP within a certain time window (e.g., 30 minutes, etc.).

[0093] FIG. 22 illustrates another exemplary format of a Level 1 client discovery response frame 2200 according to one embodiment of the present disclosure. The client discovery response frame 2200 is transmitted between an MLD SBP initiator (e.g., a non-AP MLD) and an AP MLD. The client discovery response frame 2200 comprises a MAC header (Frame Control, Duration, RA, and TA fields), a Category field set to "Protected Discovery", an Action field set to "Protected Client Discovery Response", a Dialog Token field, a Client Discovery Mode field set to 0 to indicate Level 1 client discovery, a Status Code field, an MLD information element field 2202, a Client Information Element field, a Client Information ML Element field, and an FCS field. The MLD information element field 2202 carries information of associated non-AP MLDs for which at least one affiliated STA meets the discovery criteria. The Client Information Element field carries information of non-AP STAs provided by the affiliated AP that transmits the response frame 2200. The Client Information ML element field is a new “Client Information” ML element variant that carries information of non-AP STAs provided by affiliated APs other than the AP sending the response frame 2200 .

[0094] FIG. 23 illustrates an example format of the MLD information element field 2202 of the protected client discovery response frame 2200 shown in FIG. 22. The MLD information element field 2202 has an element ID field, a length field, an element ID extension field, an MLD information control field, and an MLD information list field. The MLD information control field comprises a number of MLDs subfield, a neighbor MLD bit, and a presence bitmap subfield. The number of MLDs subfield indicates the number of MLD information fields present in the STA information list field (one per non-AP MLD). The neighbor MLD bit is set to 0 to indicate that the MLD information list conveys information for the associated MLD (as opposed to a neighboring MLD). The presence bitmap subfield includes an MLD MAC address present subfield, an MLD ID present subfield, an IP address present subfield, a MAC address present subfield, an operating channel width present subfield, an UL RSSI / RCPI present subfield, a data rate present subfield, and a BSSID present subfield. The MLD MAC Address Present subfield, MLD ID Present subfield, and IP Address Present subfield indicate the presence of corresponding fields in the common information subfield of each MLD information field, and the MAC Address Present subfield, Operating Channel Width Present subfield, UL RSSI / RCPI Present subfield, Data Rate Present subfield, and BSSID Present subfield indicate the presence of corresponding fields in the link information subfield of each MLD information field.

[0095] The MLD information list field comprises one or more MLD information fields. Each MLD information field carries information of a non-AP MLD having at least one affiliated STA that satisfies the discovery criteria indicated in the client discovery query frame, and comprises a common information subfield, a link ID bitmap subfield, and one or more link information subfields. The common information subfield comprises an AP MLD bit, an MLD MAC address subfield, an MLD ID subfield, and an IP address subfield. The AP MLD bit indicates the type of MLD. The AP MLD bit may be set to 0 to indicate a non-AP MLD, and may be set to 1 to indicate an AP MLD. In this case, the AP MLD bit is set to 0 to indicate a non-AP MLD. The MLD MAC address subfield carries the MAC address of the non-AP MLD. The MLD ID carries the MLD ID of the associated AP MLD.

[0096] The Link ID Bitmap subfield indicates the link of the MLD whose information is transmitted in the Link Information subfield. Each Link Information field transmits information of each non-AP STA that satisfies the discovery criteria provided by the associated AP operating on that link and indicated in the Client Discovery Query frame, and each Link Information field has a MAC Address subfield that transmits the MAC address of the associated non-AP STA, an Operating Channel Width subfield, a UL RSSI / RCPI subfield, a Data Rate subfield, and a BSSID subfield that transmits the BSSID of the associated AP.

[0097] The Link Information subfield of the MLD Information field may include the STA's capability and operation parameters (e.g., Basic, HT, VHT, HE, EHT, WLAN sensing capability element, HT, VHT, HE, EHT operation element, etc.). The Common Information subfield of the MLD Information may further include an MLD capability element, a device type (e.g., laptop, PC, smartphone, smart appliance, etc.), and a device location element (defined in IEEE 802.11-2020), which indicates the geographic location where the non-AP STA or non-AP MLD is located (e.g., within an RSSI / RCIP radius of -62 dBm, etc.).

[0098] In addition, if the discovery criteria bitmap in the query includes a "include associated STAs only" bit, then if the bit is set to 1, then information about non-AP STAs / MLDs that are not associated with the affiliated AP / AP MLD will not be included in the client discovery response. However, if the bit is set to 0, then the AP MLD may include information about non-AP STAs / MLDs that are not associated with the affiliated AP / AP MLD in the client discovery response. Note that the AP MLD may maintain a list of non-associated non-AP STAs and / or non-AP MLDs that have ever engaged in frame exchanges (e.g., probe requests / responses) with the AP MLD, or have attempted to associate with the AP MLD or affiliated AP, or have been disassociated from the AP MLD or affiliated AP within a certain time window (e.g., 30 minutes, etc.).

[0099] Returning to Figure 22, the Client Info ML element field has an Element ID field, a Length field, an Element ID Extension field, a Multilink Control field, a Common Information field, and a Link Information field. The Multilink Control field comprises a Type subfield set to "Client Info" and a Presence Bitmap subfield.

[0100] Table 1 shows the variations of the various multilink elements corresponding to the values ​​of the Type subfield.

[0101] [Table 1]

[0102] The common information field comprises an MLD MAC address subfield that carries the MLD MAC address of the AP MLD. The link information field comprises one or more per-STA profile subelement subfields corresponding to one or more links, each of which comprises a subelement ID field, a length field, a STA control field, a STA information field, and a STA profile field. The STA control field includes a link ID subfield that corresponds to an affiliated AP operating on the link. The STA profile field carries information of non-AP STAs associated with an affiliated AP operating on the link.

[0103] Additionally, the STA information field may also include the supported capabilities, PHY version channel width, and location (e.g., basic, HT, VHT, HE, EHT, WLAN sensing capability element, HT, VHT, HE, EHT operation element, etc.) of the affiliated AP. The location information may be obtained by GP (in outdoor case) or fine time measurement and / or ranging (in indoor case), etc. If the STA information field in the client discovery response frame carries information of a DMG (directional multi-gigabit, i.e., 802.11ad) STA or an EDMG (enhanced directional multi-gigabit, i.e., 802.11ay) STA, the STA information field may also carry a sector selection subfield containing the value of the sector ID subfield of the SSW field in the frame received with the best quality in the previous sector sweep. The sector ID subfield indicates the sector number from which the frame containing this SSW field is transmitted. The AP may take the sector number information into consideration when selecting a sensing responder STA from among the DMG / EDMG STAs. The STA Profile field carries a Client Information Element that carries information of a non-AP STA associated with an affiliated AP operating on the link.

[0104] If the discovery criteria bitmap in the query frame further includes a "include only associated STAs" bit, then when the bit is set to 1, the AP may not include information about non-AP STAs that are not associated with the AP in the client discovery response frame, and when the bit is set to 0, the AP may include information about non-AP STAs that are not associated with the AP in the client discovery response frame. Note that the AP may maintain a list of non-associated non-AP STAs that have previously engaged in a frame exchange (e.g., probe request / response) or attempted to associate with the AP, or have been disassociated from the AP within a certain time window (e.g., 30 minutes, etc.).

[0105] 24 illustrates an example format of a protected client discovery query frame 2400 used for a level 2 client discovery query, according to one embodiment of the present disclosure. The protected client discovery query frame 2400 has a MAC Header (Frame Control, Duration, RA, and TA) field, a Category field set to "Protected Discovery", an Action field set to "Protected Client Discovery Query", a Dialog Token field, a Client Discovery Mode field, a Client Discovery Request Elements field, and an FCS field. Client discovery is set to 1 to indicate a level 2 client discovery query.

[0106] The client discovery request element field comprises an element ID field, a length field, an element ID extension field, a discovery criteria bitmap field, a target STA information field, a minimum RSSI / RCPI field, and a BSSID field.

[0107] PHY Version Bitmap, Supported Features Bitmap, Link Metrics, Operating Channel Width, MLD Information, and BSSID List fields. The Discovery Criteria Bitmap field has a Target STA Information Present subfield, a PHY Version Present subfield, a Supported Features Present subfield, a Link Metrics Present subfield, an Operating Channel Width Present subfield, an MLD Information Present subfield, and a BSSID List Present subfield. The subfields are set to 1 to indicate the presence of the added field used as criteria for selecting non-AP STAs or associated STAs for the requested non-AP MLD. The Target STA Information Present subfield is set to 1 in Level 2 client discovery.

[0108] The PHY Version Bitmap field has HT, VHT, HE, and EHT subfields to indicate the PHY versions supported by the STA / non-AP MLD. The Supported Features Bitmap indicates features supported by the target non-AP STA and includes a Tunneled Direct Link Setup (TDLS) Support subfield, a WLAN Sensing subfield, and an SBP subfield to indicate features supported by the STA / non-AP MLD. The Link Metrics field has a Minimum RSSI / RCPI subfield and a Minimum Data Rate subfield to indicate link metrics supported by the STA / non-AP MLD. The link metrics are measured between the STA and the associated AP. The Operating Channel Width field indicates the operating channel width of the discovered STA. The MLD Information field is present only if the frame is addressed to an AP affiliated with an AP MLD and includes an MLD ID subfield carrying the MLD ID of the AP MLD and a Link ID Bitmap subfield carrying the link for which information is requested.

[0109] If the BSSID List field is present, information of non-AP STAs associated with all BSSIDs is requested. If the BSSID List field is not present, by default a non-MLD AP will only provide information about non-AP STAs associated with itself, and an AP MLD will provide information about non-AP STAs associated with all its affiliated APs in addition to information about associated non-AP MLDs.

[0110] The Target STA Information field carries information of the requested / indicated non-AP STA or non-AP MLD (i.e., the STA or MLD of interest) and comprises a Target MAC Address subfield, a Neighbor Information Request subfield, and a Minimum RSSI / RCPI Presence subfield. The Target MAC Address subfield carries the MAC address of the requested non-AP STA or the MLD MAC address of the requested non-AP MLD. Alternatively, an AID or UID may be provided instead of the MAC address. If information about neighboring devices is also requested, the Neighbor Information Request subfield is set to 1.

[0111] The Min RSSI / RCPI field indicates the link metric supported by the link with the neighboring device. The link metric between the target STA and the neighboring STAs located within the radio range of the target STA is measured. If a BSSID list is present, the neighboring STAs are limited to STAs associated with the APs corresponding to the BSSIDs in the list.

[0112] Additionally, the discovery criteria bitmap may include an "AP Exclude" bit to indicate that if the bit is set to 1, information regarding AP / AP MLD is not requested, and if the bit is set to 0, non-AP STAs / non-AP MLDs may also include AP / AP MLD information in the client discovery response.

[0113] FIG. 25 illustrates an example of a format of a level 2 client discovery response frame 2500 according to one embodiment of the present disclosure. The client discovery response frame 2500 is sent between a non-MLD SBP initiator and an SBP responder. The client discovery response frame 2500 includes a MAC header (Frame Control, Duration, RA, and TA fields), a category field set to "protected discovery", an action field set to "protected client discovery response", a dialog token field, a client discovery mode field set to 1 to indicate level 2 client discovery, a status code field, a client information element field, and an FCS field. The client information element field includes an element ID field, a length field, an element ID extension field, a STA information control field, and a STA information list field. The STA information control field includes a STA count subfield, a neighboring STA bit, and a presence bitmap subfield. The STA count subfield indicates the number of STA information fields present in the STA information list field (one for each neighboring non-AP STA). The neighboring STA bit is set to 1 to indicate that the STA information list carries information of the neighboring STAs. The Presence Bitmap subfield comprises a MAC Address Present subfield (set to 0), an Internet Protocol (IP) Address Present subfield (set to 0), an Operating Channel Width Present subfield (set to 0), a UL RSSI / RCPI Present subfield, a Data Rate Present subfield (set to 0), and a BSSID Present subfield.

[0114] The STA Information List field comprises one or more STA Information fields. Each STA Information field carries information of each neighboring non-AP STA that meets the discovery criteria indicated in the Client Discovery Query frame, and has a MAC Address subfield carrying the MAC address of the neighboring non-AP STA, a UL RSSI / RCPI subfield, and a BSSID subfield carrying the BSSID of the B with which the neighboring non-AP STA is associated or the BSSID of the AP itself. If the MAC Address and BSSID fields are the same, it indicates an AP. The UL RSSI / RCPI field indicates the RSSI / RCPI observed on the direct link between the non-AP STA and its neighboring non-AP STA, or the RSSI / RCPI observed on the link between the non-AP STA and its neighboring AP.

[0115] In addition, the STA information field may include the supported capabilities, PHY version, channel width, and location of the STA. The location information may be obtained by GP (in outdoor case) or fine time measurement and / or ranging (in indoor case), etc. If the STA information field in the client discovery response frame carries information of a DMG (Directional Multi-Gigabit, i.e., 802.11ad) STA or an EDMG (Enhanced Directional Multi-Gigabit, i.e., 802.11ay) STA, the STA information field may also carry a sector selection subfield containing the value of the Sector ID subfield of the SSW field in the frame received with the best quality in the previous sector sweep. The Sector ID subfield indicates the sector number from which the frame containing this SSW field is transmitted. The AP may consider and use the sector number information when selecting a sensing response STA from among the DMG / EDMG STAs.

[0116] If the discovery criteria bitmap in the query includes an "Exclude AP" bit, if the bit is set to 1, information about APs is not included in the client discovery response, and if the bit is set to 0, non-AP STAs / non-AP MLDs may also include information about APs in the client discovery response.

[0117] 26 illustrates another example format of a Level 2 client discovery response frame 2600, according to one embodiment of the present disclosure. The client discovery response frame 2600 is transmitted between an MLD SBP initiator (e.g., non-AP MLD) and a responder (AP MLD). The client discovery response frame 2600 comprises a MAC header (Frame Control, Duration, RA, and TA fields), a Category field set to "Protected Discovery", an Action field set to "Protected Client Discovery Response", a Dialog Token field, a Client Discovery Mode field set to 1 to indicate Level 2 client discovery, a Status Code field, an MLD Information Element field, a Client Information Element (Neighboring STAs) field, an MLD Information Element (Neighboring MLD) field, a Client Information ML Element field, and an FCS field. The MLD information element field carries information of the requested non-AP MLD (i.e., when the Neighbor MLD bit is set to 0, the response frame 2600 carries only a single MLD information element field without an MLD information element (Neighbor MLD) field. The Client information element (Neighbor STAs) field conveys information of STAs and APs that are neighboring STAs and APs of the associated STA sending the response frame 2600 and that meet the link metric criteria indicated in the client discovery query frame. The MLD information element (Neighbor MLD) field carries information of neighboring MLDs (i.e., when the Neighbor MLD bit is set to 1).

[0118] FIG. 27 illustrates an example format of the MLD information element field of the protected client discovery response frame 2600 illustrated in FIG. 26. The MLD information element field comprises an element ID field, a length field, an element ID extension field, an MLD information control field, and an MLD information list field. The MLD information control field comprises a number of MLDs subfield, a neighbor MLD bit, and a presence bitmap subfield. The number of MLDs subfield indicates the number of MLD information fields present in the STA information list field (one per non-AP MLD). The neighbor MLD bit is set to 1 to indicate that the MLD information list carries information of a neighboring MLD. The current presence bitmap subfield includes an MLD MAC address present subfield, an MLD ID present subfield, an IP address present subfield, a MAC address present subfield, an operating channel width present subfield, an UL RSSI / RCPI present subfield, a data rate present subfield, and a BSSID present subfield. The MLD MAC Address Present subfield, MLD ID Present subfield, and IP Address Present subfield indicate the presence of the corresponding fields in the common information subfield of each MLD information field. All bits except the MLD MAC Address Present bit are set to 0. The MAC Address Present subfield, Operating Channel Width Present subfield, UL RSSI / RCPI Present subfield, Data Rate Present subfield, and BSSID Present subfield indicate the presence of the corresponding fields in the link information subfield of each MLD information field. All bits except the UL RSSI / RCPI Present bit are set to 0.

[0119] The MLD Information List field comprises one or more MLD Information fields. Each MLD Information field carries information of neighboring MLDs for which at least one affiliated STA satisfies the discovery criteria indicated in the Client Discovery Query frame, and comprises a Common Information subfield, a Link ID Bitmap subfield, and one or more Link Information subfields. The Common Information subfield includes an AP MLD bit, an MLD MAC Address subfield, an MLD ID subfield, and an IP Address subfield. The AP MLD bit indicates the type of MLD. The AP MLD bit may be set to 0 to indicate non-AP MLD and may be set to 1 to indicate AP MLD. The MLD MAC Address subfield carries the MAC address of the MLD.

[0120] The Link ID Bitmap subfield indicates the link whose information is transmitted in the Link Information subfield. Each Link Information subfield transmits information of STAs associated with a neighboring MLD, and includes a MAC Address subfield that transmits the MAC address of the STA associated with the neighboring MLD, a UL RSSI / RCPI subfield, and a BSSID subfield that transmits the associated BSSID of the associated non-AP STA for the non-AP MLD. The BSSID subfield does not exist in the AP MLD.

[0121] Additionally, the Link Information subfield may include the STA's capabilities and operational parameters (e.g., Basic, HT, VHT, HE, EHT, WLAN sensing capability element, HT, VHT, HE, EHT operational element, etc.). If the Link Information subfield carries information for a DMG (Directional Multi-Gigabit, i.e., 802.11ad) STA or an EDMG (Enhanced Directional Multi-Gigabit, i.e., 802.11ay) STA, the STA Information field may also include a Sector Selection subfield that contains the value of the Sector ID subfield of the SSW field in the frame that was received with the best quality in the previous sector sweep. The Sector ID subfield is set to indicate the sector number to which the frame containing this SSW field is transmitted.

[0122] The common information subfield of the MLD information field may further include an MLD capability element, and a device location element (defined in IEEE 802.11-2020) is included in the client discovery request element to indicate the geographic location where the MLD is located (e.g., within a 10 m radius, or within an RSSI / RCPI radius of -62 dBm, etc.).

[0123] Returning to Figure 26, the Client Information ML element carries information of neighbor STAs and APs of affiliated non-AP STAs other than the STA sending the response frame, and includes an Element ID field, a Length field, an Element ID Extension field, a Multilink Control field, a Common Information field, and a Link Information field. The Multilink Control field has a Type subfield, set to, for example, "Client Information" according to Table 1, and a Presence Bitmap subfield.

[0124] The common information field has an MLD MAC Address subfield that carries the MLD MAC address of the requested non-AP MLD. The link information field comprises one or more per-STA profile subelement subfields corresponding to one or more links, each of the per-STA profile subelement fields comprising a subelement ID field, a length field, a STA control field, a STA information field, and a STA profile field. The STA control field includes a link ID subfield. The STA profile field has the neighbor STA bit set to 1, carries a client information element, and carries neighbor non-AP STA and AP information for affiliated non-AP STAs operating on the link.

[0125] Additionally, the discovery criteria bitmap may include a bit for "Exclude AP", which when set to 1 indicates that information regarding AP / AP MLD is not included in the client discovery response frame 2600, and when the bit is set to 0, non-AP STAs / non-AP MLDs may also include information regarding AP / AP MLD in the client discovery response.

[0126] In one embodiment of the present disclosure, for example, upon receiving a level 2 client discovery query from an associated non-AP STA, a level 3 client discovery procedure may be triggered by the AP to discover neighboring non-AP STAs of the associated non-AP STA. FIG. 28 illustrates a flowchart 2800 illustrating a level 3 client discovery procedure triggered by an AP, according to one embodiment of the present disclosure. Non-AP STA1 is an SBP initiator that initiates a level 2 client discovery query and requests detailed information of a particular non-AP STA (in this case, non-AP STA2) associated with the AP by sending a protected client discovery query frame to the AP. The protected client discovery query frame includes a level field set to 2 (or a client discovery mode field set to 1) to indicate level 2 client discovery, a target client's ID (i.e., a tree MAC address field) set as the ID (MAC address) of non-AP STA2, and a neighbor information request field set to 1 to indicate that information of neighboring clients (i.e., STAs and APs located within wireless range) of the indicated STA is also requested. Then, upon receiving the level 2 client discovery query, the AP initiates a level 3 client discovery query with the indicated non-AP STA (non-AP STA2) by sending a protected client discovery query frame to the indicated non-AP STA (non-AP STA2). The protected client discovery query frame comprises a level field set to 3 (or a client discovery mode field set to 2) to indicate level 3 client discovery, a target STA information field set to 1, and a neighbor information request field set to 1. The discovery criteria included in the level 2 client discovery query frame sent by non-AP STA1 are also included in the level 3 client discovery query frame.

[0127] When the non-AP STA2 receives the level 3 client discovery query frame, it collects information of neighboring STAs and APs based on the provided discovery criteria, and then sends a protected client discovery response frame to the AP to provide detailed information of the non-AP STA2 and information of neighboring clients (e.g., non-AP STAs and APs).The AP then forwards the information received from the indicated non-AP STA2 to the non-AP STA1.

[0128] The format and contents of the protected client discovery query frame and protected client discovery response frame for level 3 client discovery are identical to those used for client discovery of client 2 as shown in Figures 24-27, except that for level 3, the client discovery mode field is set to 2 (instead of 1) and the frames are sent in the reverse direction (i.e., queries from the AP to non-AP STAs and responses from non-AP STAs to the AP).

[0129] A non-AP STA may collect information about neighboring non-AP STAs and APs in a variety of ways. One method is to passively listen to the frame transmissions of neighboring non-AP STAs and APs and record their details (such as MAC addresses from the TA field, observed RSSI / RCPI, BSSID from the BSSID field, etc.). Alternatively, a non-AP STA may actively attempt to publish frames with neighboring non-AP STAs and APs in the following ways: (i) by sending a TDLS discovery request frame to neighboring non-AP STAs and APs (via the associated AP) and recording details from the TDLS discovery response frame received on the direct link (e.g., MAC address from the TA field, observed RSSI / RCPI, associated AP from the BSSID field); (ii) by exchanging ANQP request / response frames (Group Address GA request / response frames) with neighboring non-AP STAs over the direct path and recording their details (e.g., MAC address from the TA field, observed RSSI / RCPI, BSSID from the BSSID field); or (iii) by exchanging probe request / response frames with neighboring APs and recording their details (e.g., MAC address from the TA field, observed RSSI / RCPI, BSSID from the BSSID field).

[0130] Such level 3 client discovery can also be triggered by AP MLD. Similar to that for non-MLD, except that the requested non-AP MLD collects neighboring STAs, AP information, as well as neighbor non-AP MLD and AP MLD information for all affiliated STAs associated with the APs listed in the BSSID list field of the client discovery request element. For neighbor MLD, non-AP MLD also collects MLD related information (e.g., MLD MAC address).

[0131] FIG. 29 illustrates a flow chart 2900 illustrating a level 3 client discovery procedure triggered by an AP MLD according to one embodiment of the present disclosure. A non-AP MLD or affiliated STA is an SBP initiator that initiates a level 2 client discovery query, requesting detailed information of a particular non-AP STA associated with an AP (in this case, a non-AP STA affiliated with non-AP MLD2) by sending a protected client discovery query frame to the AP MLD. The protected client discovery query frame comprises a level field set to 2 (or a client discovery mode field set to 1) to indicate level 2 client discovery, a client ID set to the ID of the non-AP MLD2, and a neighbor information request field set to 1 to indicate that information of neighbor clients of the indicated STA is also requested. Upon receiving the level 2 client discovery query, the AP MLD initiates a level 3 client discovery query with the indicated non-AP MLD (non-AP MLD2) by sending a protected client discovery query frame to the indicated non-AP MLD2. The protected client discovery query frame comprises a level field set to 3 (or a client discovery mode field set to 2) to indicate level 3 client discovery, a target STA information field set to 1, and a neighbor information request field set to 1. The discovery criteria included in the level 2 client discovery query frame transmitted by the non-AP MLD1 are also included in the level 3 client discovery query frame.

[0132] When the non-AP MLD2 receives the level 3 client discovery query frame, it collects information about the neighboring STAs and APs of the associated non-AP STAs and information about the neighboring MLDs based on the provided discovery criteria, and then sends a protected client discovery response frame to the AP MLD, providing detailed information about the non-AP STA2 and information about the neighboring clients (e.g., MLDs, non-AP STAs, and APs).The AP MLD then forwards the information received from the indicated non-AP MLD2 to the non-AP MLD1.

[0133] The following paragraphs describe a second embodiment of the present disclosure in which an enhanced client discovery procedure is performed when an AP or AP MLD is part of a multi-AP network.

[0134] 30 shows a schematic diagram 3000 illustrating a multi-AP network deployment according to a second embodiment of the present disclosure. If an AP or AP MLD is part of a multi-AP network (e.g., EasyMesh), a non-AP STA or non-AP MLD may request information of non-AP STAs associated with other APs in the multi-AP network (standalone or affiliated with an AP MLD) as well as information of unassociated non-AP STAs known to the AP.

[0135] The formats and contents of the protected client discovery query frame and the protected client discovery response frame are the same as those in the first embodiment and those shown in Fig. 18 and Fig. 21 to Fig. 27. The list of requested APs is provided in the BSSID list field. When an AP or AP MLD in the multi-AP network receives a client discovery query frame, the AP or AP MLD can provide information of non-AP STAs and non-AP MLDs associated with other APs or AP MLDs in the multi-AP network.

[0136] In the following paragraphs, a third embodiment of the present disclosure is described in which an enhanced client discovery procedure is performed using data frames.

[0137] There may be cases where an AP does not support enhanced client discovery. In such cases, a non-AP STA (or non-AP MLD) may directly solicit information from a target non-AP STA (or non-AP MLD) similar to Level 2 client discovery by exchanging client discovery frames and authorization verification frames, encapsulating them in Ethertype 89-0d data frames, and having the common associated AP forward the encapsulated frames to the target non-AP STA. By encapsulating the discovery frames and authorization verification frames in data frames, the AP does not need to decode the messages. The decoding of the frames is performed by the target non-AP STA (or non-AP MLD). This process is sometimes called tunnel discovery, or tunnel-enhanced client discovery.

[0138] FIG. 31 shows a schematic diagram 3100 illustrating a tunnel-enhanced client discovery procedure according to a third embodiment of the present disclosure. FIG. 32 shows a flowchart 3200 illustrating a tunnel-enhanced client discovery procedure between non-AP STA1 and non-AP STA2 according to a third embodiment of the present disclosure. Non-AP STA1 may first send a protected client discovery query frame to request information of other non-AP STAs (e.g., non-AP STA2) via the AP. The protected client discovery query frame has a level field set to 2 (or a client discovery mode field set to 1) to indicate a level 2 discovery query, a client ID set to the ID of non-AP STA2, and a neighbor information request field set to 1 to indicate that information of neighboring clients (i.e., STAs and APs located within wireless range) of the indicated STA is also requested. According to this third embodiment, the client discovery query frame is encapsulated in a data frame. The AP that receives the data frame addressed to non-AP STA2 directly forwards the data frame including the client discovery query frame to non-AP STA2.

[0139] In one example, the additional authorization verification may be triggered by the non-AP STA2. The non-AP STA2 may then send an authorization verification request frame to the non-AP STA1 via the AP to request verification information or authorization credentials (e.g., a shared password, etc.). The non-AP STA1 responds by sending an authorization verification response frame to the non-AP STA2 via the AP to provide verification information or authorization credentials (e.g., a password) indicating that it is authorized to perform enhanced client discovery. Similarly, the authorization verification frame is encapsulated in a data frame and forwarded to the destination by the AP that receives the data frame, thereby prompting an exchange of verification frames.

[0140] If the authorization verification is successful, the steps shown in block 3202 are executed, and if the authorization verification is unsuccessful, the steps shown in block 3204 are executed. In particular, if the authorization verification is successful, the non-AP STA2 then collects information of its neighboring STAs and APs based on the discovery criteria provided in the client discovery query frame, generates a protected client discovery response frame, and sends the protected client discovery response frame including detailed information of the non-AP STA2 and its neighboring STAs and APs to the non-AP STA1 via the AP.

[0141] If the authorization verification fails, the non-AP STA2 does not provide information about itself and its neighboring devices, but instead sends a protected client discovery response frame with a status field indicating that the authorization verification failed to the non-AP STA1 via the AP.

[0142] A similar frame exchange sequence may be performed between two non-AP MLDs, and a similar enhanced client discovery procedure may be performed, except that the associated AP-MLD may forward frames to the equivalent non-AP MLD on any available link (other than the original link used by the sending non-AP MLD).

[0143] A new Ethertype 89-0d payload type is defined to encapsulate enhanced client discovery frames. Figure 33A illustrates an example format of an enhanced client discovery Ethertype 89-0d data frame 3300 according to a third embodiment of the present disclosure. The enhanced client discovery Ethertype 89-0d data frame includes a frame control field, a duration field, three address fields (address field 1, address field 2, address field 3), a sequence control field, an address 4 field, a quality of service (QoS) control field, a HT control field, a frame body, and an FCS field. The frame control field, the duration field, the three address fields (address field 1, address field 2, address field 3), the sequence control field, the address field 4, the quality of service (QoS) control field, and the HT control field may be grouped as a MAC header. The address 3 (A3) field is set according to the 802.11 source address (SA) and destination (DA). More specifically, if the data frame 3300 is transmitted by a non-AP STA, the A3 field is set as DA (the MAC address of the target non-AP STA), and if the data frame 3300 is transmitted by an AP, the A3 field is set as SA (the MAC address of the source non-AP STA).

[0144] The frame body has a Logical Link Control (LLC) field, a NAP field set to "Ethertype of 89-0d type", a payload type field, and a payload field 3202. The payload type field is set to "Enhanced Client Discovery" according to Table 2, for example, with the value of the payload type field set to 5.

[0145] Table 2 shows the various protocols that correspond to the values ​​of the payload type field.

[0146] [Table 2]

[0147] When a client discovery frame is encapsulated in an enhanced client discovery Ethertype 89-0d data frame, the frame bodies of the protected client discovery and authorization verification frames are carried in the payload field of the Ethertype 89-0d data frame.

[0148] Figure 33B illustrates example contents of payload field 3302 shown in Figure 33A according to an embodiment. The payload field of the frame body includes a protected client discovery query frame, a protected discovery response frame, an authorization validation request frame, and / or an authorization validation response frame.

[0149] In the following paragraphs, a fourth embodiment of the present disclosure is described in which an enhanced client discovery procedure is performed using higher layer protocols.

[0150] Instead of using Ethertype 89-0d data frames, enhanced client discovery can be performed using higher layer protocols such as 1905 Topology Query / Response messages, such as the multi-AP deployment shown in Figure 30, e.g., EasyMesh, as a non-limiting example.

[0151] In a typical EasyMesh multi-AP deployment, an AP (especially an AP that is part of a multi-AP controller) may already have access to information for all non-AP STAs that are associated with any of the APs that are part of the multi-AP network, as well as information for some non-AP STAs that are not associated with any AP.

[0152] To perform enhanced client discovery, a non-AP STA (associated or not associated with any) or an AP sends a 1905 Topology Query message carrying a Client Discovery Query Type-Length-Value (TLV) to any AP or other non-AP STA that is part of the multi-AP network, requesting information about the non-AP STA. An exemplary format of the Client Discovery Query TLV is shown in Table 3.

[0153] Upon receiving the Client Discovery Query TLV, the AP (or non-AP STA) provides the inquired information about the non-AP STA in a 1905 Topology Response message carrying a Client Discovery Response TLV. An exemplary format of the Client Discovery Response TLV is shown in Table 4.

[0154] The AP may also send a 1905 Topology Query message carrying an Authorization Verification Request TLV to a non-AP STA to request authorization information to verify whether the requesting non-AP STA is authorized to obtain information about other non-AP STAs. An exemplary format of the Authorization Verification Request TLV is shown in Table 4.

[0155] Upon receiving an Authorization Verification Request TLV from an associated AP or AP MLD, a non-AP STA may send a 1905 Topology Query message carrying an Authorization Verification Response TLV carrying verification information (e.g., a shared password) in a format required by the AP. An exemplary format of the Authorization Verification Response TLV is shown in Table 5.

[0156] FIG. 34 illustrates a configuration example of a communication device 3400. The communication device 3400 is implemented as a non-AP STA for enhanced client discovery according to various embodiments of the present disclosure. The communication device 3400 includes a power supply 3402, a memory 3404, a central processing unit (CPU) 3406 including at least one processing, a secondary storage device 3408, a wired I / F (interface) 3410, and a wireless I / F 3412. The memory 3404 may be a non-transitory computer-readable storage medium that records therein data representing instructions executed by at least one processor of the CPU 3406 to communicate with the wireless I / F 3412 to perform an enhanced client discovery procedure according to various embodiments described in the present disclosure. The wireless I / F 3412 includes a MAC layer 3414 and a PHY layer 3416. The PHY layer 3416 is connected to a wireless receiver (not shown), a wireless transmitter, and an antenna 3422 used to transmit / receive signals to / from other communication devices (e.g., STAs). Alternatively, the communication device 3400 may transmit / receive signals to / from other communication devices (e.g., STAs, etc.) via the wired I / F 3410. The secondary storage device 3408 may be configured to store the AIDs of the associated communication devices.

[0157] The MAC layer 3414 further includes an enhanced client discovery module 3418 that stores information of neighboring non-AP STAs 3420. The communication device 3400 may be a non-AP STA, and the enhanced client discovery module 3418 may be configured to generate and process frames (e.g., client discovery query / response frames, authorization validation request / response frames) to perform an enhanced client discovery procedure according to various embodiments described above. The communication device 3400 may be a sensing responder, and the enhanced client discovery module 3418 may be configured to generate and process frames (e.g., client discovery query / response frames, authorization validation request / response frames) and provide information of neighboring non-AP STAs 3420 in response to receiving frames from other communication devices.

[0158] FIG. 35 illustrates another example of the configuration of a communication device 3500. The communication device 3500 is implemented as an AP for enhanced client discovery according to the present disclosure. The communication device 3500 includes a power supply 3502, a memory 3504, a central processing unit (CPU) 3506 including at least one processor, a secondary storage device 3508, a wired I / F 3510, and a wireless I / F 3512. The memory 3504 may be a non-transitory computer-readable storage medium having stored therein data representing instructions executed by at least one processor of the CPU 3506 to communicate with the wireless I / F 3512 to perform multi-generation random access according to various embodiments of the present disclosure. The wireless I / F 3512 includes a MAC layer 3514 and a PHY layer 3516. The PHY layer 3516 connects to a wireless receiver (not shown), a wireless transmitter (not shown), and an antenna 3522 used to transmit / receive signals to other (base) communication devices. Alternatively, the communication device 3500 may transmit / receive signals to / from other communication devices via the wired I / F 3510.

[0159] The MAC layer 3514 further includes an enhanced client discovery module 3518 that stores information of associated non-AP STAs 3520. The enhanced client discovery module 3518 may be configured to utilize the information of associated non-AP STAs 3520 to generate and process frames (e.g., client discovery query / response frames, authorization validation request / response frames) and perform enhanced client discovery procedures according to various embodiments described above.

[0160] As described above, the embodiments of the present disclosure provide an advanced communication system, communication method and communication device for enhanced client discovery procedures in MIMO WLAN networks.

[0161] The present disclosure can be realized by software, hardware, or software in cooperation with hardware. Each functional block used in the description of each embodiment above can be partially or completely realized by an LSI such as an integrated circuit, and each process described in each embodiment can be partially or completely controlled by the same LSI or a combination of LSIs. The LSI can be formed individually as a chip, or one chip can be formed to include some or all of the functional blocks. The LSI can include data inputs and outputs coupled thereto. Depending on the degree of integration, the LSI can be called an IC, a system LSI, a super LSI, or an ultra LSI. However, the technology for implementing the integrated circuit is not limited to the LSI, and can be realized using a dedicated circuit, a general-purpose processor, or a dedicated processor. Also, a field programmable gate array (FPGA) that can be programmed after the LSI is manufactured, or a reconfigurable processor that can reconfigure the connections and settings of the circuit cells arranged in the LSI can be used. The present disclosure can be realized as digital processing or analog processing. If future integrated circuit technology replaces LSI as a result of advances in semiconductor technology or other derived technologies, the functional blocks can be integrated using the future integrated circuit technology. Biotechnology can also be applied.

[0162] The present disclosure may be implemented by any type of apparatus, device or system having communication capabilities, referred to as a communications apparatus.

[0163] Some non-limiting examples of such communication devices include phones (e.g., cellular (cell) phones, smartphones), tablets, personal computers (PCs) (e.g., laptops, desktops, netbooks), cameras (e.g., digital still / video cameras), digital players (digital audio / video players), wearable devices (e.g., wearable cameras, smart watches, tracking devices), game consoles, digital book readers, telehealth / telemedicine (remote health and medicine) devices, and vehicles (e.g., cars, airplanes, ships) that provide communication capabilities, and various combinations thereof.

[0164] Communications devices are not limited to being portable or mobile, but may also include any type of non-portable or fixed equipment, device, or system, such as smart home devices (e.g., appliances, lights, smart meters, control panels), vending machines, and any other "things" in the network of the "Internet of Things" (IoT).

[0165] Communications may include, for example, data exchange via cellular systems, wireless LAN systems, satellite systems, and the like, as well as various combinations thereof.

[0166] A communications apparatus may include devices such as a controller or a sensor coupled to a communications device to perform the communications functions described in this disclosure. For example, a communications apparatus may include a controller or a sensor that generates control or data signals used by the communications device to perform the communications functions of the communications apparatus.

[0167] Communications equipment may also include infrastructure facilities such as base stations, access points, and any other equipment, device, or system that communicates with or controls equipment such as those in the non-limiting examples above.

[0168] Although certain features of the various embodiments have been described with reference to devices, it will be understood that corresponding features also apply to the methods of the various embodiments, and vice versa.

[0169] It will be appreciated by those skilled in the art that numerous variations and / or modifications may be made to the present disclosure as illustrated in the specific embodiments without departing from the spirit or scope of the disclosure as broadly described. The present embodiments are therefore to be considered in all respects as illustrative and not restrictive.

[0170] Table 3 shows an example format of a client discovery query TLV used for enhanced client discovery according to the fourth embodiment of the present disclosure.

[0171] [Table 3]

[0172] Table 4 shows an example format of a client discovery response TLV used for enhanced client discovery according to the fourth embodiment of the present disclosure.

[0173] [Table 4]

[0174] Table 5 shows an example format of an authorization verification request TLV used for enhanced client discovery according to the fourth embodiment of the present disclosure.

[0175] [Table 5]

[0176] Table 6 shows an example format of an authorization validation response TLV used for enhanced client discovery according to the fourth embodiment of the present disclosure.

[0177]

Table 6

Claims

1. a circuit configured, in operation, to generate a first frame; a transmitter that, during operation, transmits the first frame to a second communication device to request information of a third communication device; A first communication device comprising:

2. The first communication device of claim 1 , wherein the information includes information of one or more neighboring communication devices of the third communication device.

3. 2. The first communication device of claim 1, wherein the information includes at least one of a Media Access Control (MAC) address, an Associated Identifier (AID), an associated Access Point (AP) identifier, supported capabilities, a Physical (PHY) version, an operating channel width, and a location of either or both of the third communication device and neighboring communication devices of the third communication device.

4. 2. The first communication device of claim 1, wherein the first frame has a field indicating criteria for selecting the third communication device, the criteria being at least one of supported capabilities, PHY version, operating channel width, link quality indicator, and associated AP of the third communication device.

5. 2. The first communication device of claim 1, wherein the third communication device is one of a plurality of third communication devices, and the circuitry is further configured to generate a second frame, and the transmitter transmits the second frame to request information from the plurality of third communication devices.

6. The first communication device of claim 5 , wherein the request in the first frame and / or the request in the second frame are encapsulated in a data frame.

7. The first communication device of claim 6, wherein the data frame comprises an Ethertype 89-0d data frame.

8. a receiving unit configured to receive, in operation, a verification request frame for requesting verification information indicating that the first communication device is authorized to obtain information of the third communication device; the circuit is configured to process the verification request frame and generate a verification response frame including the verification information, and the transmitter transmits the verification request frame. The first communication device according to claim 1 .

9. The first communication device of claim 1 , wherein the first communication device and the third communication device are non-access point (non-AP) stations, and the second communication device is an access point.

10. The first communication device of claim 9 , wherein the first communication device and the third communication device are not associated with the second communication device.

11. The first communication device of claim 9 , wherein the first communication device is associated with a non-AP multi-link device (MLD) and the second communication device is associated with an AP MLD.

12. a receiver that, during operation, receives a request frame from a first communication device requesting information of a third communication device; circuitry configured, in operation, to process the request frame and generate a response frame including the information; a transmitter that, in operation, transmits the response frame to the first communication device; A second communication device comprising:

13. The second communication device of claim 12 , wherein the information includes information of one or more neighboring communication devices of the third communication device.

14. 14. The second communication device of claim 13, wherein the request frame further requests the third communication device to collect and report information of the one or more neighboring communication devices, and the circuitry generates the response frame including the information of the one or more neighboring communication devices collected and reported by the third communication device.

15. 13. The second communication device of claim 12, wherein the circuit generates a verification request frame to request verification information indicating that the first communication device is authorized to obtain information of the third communication device, and the receiver further receives a verification response frame including the verification information from the first communication device.

16. The second communication device of claim 12 , wherein the first communication device and the third communication device are non-access point (non-AP) stations, and the second communication device is an access point.

17. The second communication device of claim 16 , wherein the first communication device and the third communication device are not associated with the second communication device.

18. The second communication device of claim 16 , wherein the first communication device is affiliated with a non-AP MLD and the second communication device is affiliated with an AP MLD.

19. 1. A communication method performed by a first communication device, comprising: generating a first frame; transmitting the first frame to a second communication device to request information of a third communication device; A communication method, including:

20. A communication method performed by a second communication device, comprising: receiving a request frame from a first communication device requesting information of a third communication device; processing the request frame; generating a response frame including said information; transmitting the response frame to the first communication device; A communication method, including:

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