COMMUNICATION APPARATUS AND METHOD FOR CHANNEL SOUNDING, AND INTEGRATED CIRCUIT - Patent application

Abstract

To provide apparatuses and methods for multi-AP based channel sounding.SOLUTION: In a radio communications system, a communication apparatus 300 may be a peer AP (for example, a shared AP), and a radio receiver 304 receives, in operation, a first frame (for example, a Sounding Setup Request frame) from one other communication apparatus (e.g. a sharing AP) comprising a first field which indicates an intended usage of a sounding procedure. Circuitry 314 (for example, at least one receive signal processor 310 of the circuitry 314) processes, in operation, the first frame. A radio transmitter 302 transmits, in operation, a second frame (for example, a Sounding Setup Response frame) to the one other communication apparatus, the second frame comprising a first field which indicates one or more recommended types of the sounding procedure.SELECTED DRAWING: Figure 3A

Description

[Technical Field]

[0001] The present disclosure relates to a communication apparatus and method for channel sounding, and more particularly to a communication apparatus and method for channel sounding in an extremely high throughput wireless local area network (EHT WLAN). [Background technology]

[0002] In standardizing the next generation of wireless local area networks (WLANs), the IEEE 802.11 Working Group considered a new radio access technology that would necessarily be backward compatible with IEEE 802.11a / b / g / n / ac / ax technologies, and named it IEEE 802.11be Very High Throughput (EHT) WLAN.

[0003] For 802.11be EHT WLANs, it has been proposed to enable multi-AP coordination in multiple access point (multiple AP) systems to provide significant peak throughput and capacity increases over 802.11ax high efficiency (HE) WLANs, especially for cell-edge STAs.

[0004] However, there has been little discussion about communication devices and methods for channel sounding, and in particular efficient procedures for multi-AP based sounding.

[0005] Therefore, there is a need for a communication apparatus and method that provides a viable technical solution for channel sounding in the context of EHT WLANs. 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 the background technology of this disclosure. Summary of the Invention [Means for solving the problem]

[0006] The non-limiting exemplary embodiments facilitate providing a communications apparatus and method for channel sounding in the context of an EHT WLAN.

[0007] In a first aspect, the present disclosure provides a communications device including: a receiver that receives a first frame from another communications device, the first frame including a first field indicating a target use of a sounding procedure; and circuitry that processes the first frame.

[0008] In a second aspect, the present disclosure provides a communication method that receives a first frame including a first field indicating an intended use of a sounding procedure from another communication device, and processes the first frame.

[0009] In a third aspect, the present disclosure provides an integrated circuit for controlling a process for receiving a first frame including a first field indicating a target use of a sounding procedure from another communication device, and a process for processing the first frame.

[0010] It should be noted that the general or specific embodiments may be realized as a system, a method, an integrated circuit, a computer program, a storage medium, or any selective combination thereof.

[0011] Additional benefits and advantages of the disclosed embodiments will become apparent from the specification and drawings, and these benefits and / or advantages may be obtained individually through the various embodiments and features of the specification and drawings, and it is not necessary for all of the embodiments and features to be provided in order to obtain one or more of such benefits and / or advantages.

[0012] Embodiments of the present disclosure will be better understood and readily apparent to those skilled in the art from the following description and drawings, which are given by way of example only. [Brief explanation of the drawings]

[0013] [Figure 1A] 1 is a schematic diagram illustrating uplink and downlink single-user (SU) MIMO communication between an access point (AP) and a station (STA) in a multiple input multiple output (MIMO) wireless network. [Figure 1B] 1 is a schematic diagram illustrating downlink multi-user (MU) communication between an AP and multiple STAs in a MIMO wireless network. [Figure 1C] 1 is a schematic diagram illustrating trigger-based uplink MU communication between an AP and multiple STAs in a MIMO wireless network. [Figure 1D] 1 is a schematic diagram illustrating trigger-based downlink multi-AP communication between multiple APs and STAs in a MIMO wireless network. [Figure 2A] A diagram showing a single AP-based sounding procedure between two STAs in an 11ax HE WLAN. [Figure 2B] A diagram showing a single AP-based sounding procedure between an AP and multiple STAs in an 11ax HE WLAN. [Figure 3A]1 illustrates a schematic example of a communication device, which may be implemented as an AP or a STA, and may be configured for channel sounding according to the present disclosure, in accordance with various embodiments. [Figure 3B] 1 is a flow diagram illustrating a communication method according to the present disclosure. [Figure 4] 1 is a flowchart illustrating a sounding setup procedure according to an embodiment. [Figure 5A] FIG. 10 is a diagram illustrating an example of the format of an EHT action frame. [Figure 5B] A diagram showing an example of the format of the sounding setup element field of the EHT action frame. [Figure 5C] A figure showing another example of the format of the sounding setup element field of the EHT action frame. [Figure 6A] 1 is a flowchart illustrating a single-AP-based explicit sounding procedure between two STAs in an 11be EHT WLAN, according to an embodiment. [Figure 6B] 11 is a flowchart illustrating a single-AP-based explicit sounding procedure between an AP and multiple STAs in an 11be EHT WLAN according to another embodiment. [Figure 7A] 1 is a flowchart illustrating a single AP-based implicit sequential sounding procedure according to an embodiment. [Figure 7B] 10 is a flowchart illustrating a single AP-based implicit sequential sounding procedure according to another embodiment. [Figure 8] 1 is a flowchart illustrating a single-AP based implicit joint sounding procedure according to an embodiment. [Figure 9] 1 is a flowchart illustrating a multi-AP based explicit sequential sounding procedure according to an embodiment. [Figure 10]10 is a flowchart illustrating a multi-AP based explicit joint sounding procedure according to an embodiment. [Figure 11A] 1 is a flowchart illustrating a multi-AP based implicit sequential sounding procedure according to an embodiment. [Figure 11B] 10 is a flowchart illustrating a multi-AP based implicit sequential sounding procedure according to another embodiment. [Figure 12] 1 is a flowchart illustrating a multi-AP based implicit joint sounding procedure according to an embodiment. [Figure 13A] 1 is a flowchart illustrating a multi-AP based hybrid sequential sounding procedure according to an embodiment. [Figure 13B] 10 is a flowchart illustrating a multi-AP based hybrid sequential sounding procedure according to another embodiment. [Figure 14A] 1 is a flowchart illustrating a multi-AP based hybrid joint sounding procedure, according to an embodiment. [Figure 14B] 10 is a flowchart illustrating a multi-AP based hybrid joint sounding procedure according to another embodiment. [Figure 15] FIG. 10 is a diagram illustrating an example of the format of an EHT Null Data Packet (NDP) announcement frame. [Figure 16A] 10 is a diagram illustrating an example of the format of the STA feedback information field when the sounding type field indicates single AP-based explicit sounding. [Figure 16B] 10 is a diagram illustrating an example of the format of the STA sounding information field when the sounding type field indicates single AP-based implicit sounding. [Figure 16C] 10 is a diagram illustrating an example of the format of the AP-STA Explicit Sounding Information field when the Sounding Type field indicates multi-AP-based explicit sounding. [Figure 17] 1 illustrates a configuration of a communication device, such as an AP, according to the present disclosure. [Figure 18] 1 illustrates a configuration of a communication device, such as a STA, according to the present disclosure. DETAILED DESCRIPTION OF THE INVENTION

[0014] Those skilled in the art will appreciate that components in the figures are illustrated for simplicity and clarity and have not necessarily been drawn to scale. For example, the dimensions of some components in the figures, block diagrams, or flowcharts may be exaggerated relative to other components to facilitate an accurate understanding of the present embodiments.

[0015] Some embodiments of the present disclosure will now be described, by way of example only, with reference to the drawings in which like reference numbers and letters indicate similar or equivalent elements, and in which:

[0016] In the following paragraphs, certain exemplary embodiments are described with particular reference to an access point (AP) and a station (STA) for uplink or downlink channel sounding in a multiple-input multiple-output (MIMO) wireless network.

[0017] In the context of IEEE 802.11 (Wi-Fi) technology, a station, also called a STA, is a communication device capable of using the 802.11 protocol. Based on the definition in 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 a wireless medium (WM).

[0018] For example, a STA may be a laptop, desktop personal computer (PC), personal digital assistant (PDA), access point, or Wi-Fi phone in a wireless local area network (WLAN) environment. A STA may be fixed or mobile. In a WLAN environment, the terms "STA," "wireless client," "user," "user device," and "node" are often used interchangeably.

[0019] Similarly, an AP, sometimes called a wireless access point (WAP) 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. Typically, an AP connects to a router (through the wired network) as a standalone device, but it is also possible for an AP to be integrated with or used within a router.

[0020] As mentioned above, a STA in a WLAN may act as an AP in different cases, and vice versa, because a communication device in the context of IEEE 802.11 (Wi-Fi) technology may include both STA and AP hardware components. In this manner, the communication device may switch between STA mode and AP mode based on actual WLAN conditions and / or requirements.

[0021] In a MIMO wireless network, "multiple" refers to multiple antennas used simultaneously for transmission and multiple antennas used simultaneously for reception on a wireless channel. In this regard, "multiple input" refers to multiple transmitter antennas that input wireless signals into the channel, and "multiple output" refers to multiple receiver antennas that receive wireless signals from the channel into the receiver. For example, in an N×M MIMO network system, N is the number of transmitter antennas and M is the number of receiver antennas, and N may or may not be equal to M. For brevity, this disclosure will not further discuss the respective numbers of transmitter antennas and receiver antennas.

[0022] In a MIMO wireless network, single-user (SU) and multi-user (MU) communications can be deployed for communications between communication devices, such as APs and STAs. MIMO wireless networks offer benefits such as spatial multiplexing and spatial diversity, which enable higher data rates and robustness by using multiple spatial streams. According to various embodiments, the term "spatial stream" may be used interchangeably with the term "space-time stream" (or STS).

[0023] 1A 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.). When SU ​​communication 100 in a channel is performed across the entire channel bandwidth, it is referred to as full-bandwidth SU communication. When SU ​​communication 100 in a channel is performed across 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 SU communication 100, the AP 102 transmits multiple space-time streams using multiple antennas (e.g., four antennas shown in FIG. 1A), and all 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 depicted as a grouped data transmission arrow 108 directed to the STA 104.

[0024] SU communication 100 may be configured for bidirectional transmission. As shown in FIG. 1A, in SU communication 100, STA 104 may transmit multiple space-time streams using multiple antennas (e.g., two antennas shown in FIG. 1A), with all space-time streams directed to AP 102. For simplicity, the multiple space-time streams directed to AP 102 are shown as a grouped data transmission arrow 110 directed to AP 102.

[0025] Thus, the SU communication 100 shown in FIG. 1A enables both uplink and downlink SU transmissions in a MIMO wireless network.

[0026] 1B shows a schematic diagram of downlink MU communication 112 between an AP 114 and multiple STAs 116, 118, and 120 in a MIMO wireless network. The MIMO wireless network may include one or more STAs (e.g., STA 116, STA 118, STA 120, etc.). The MU communication 112 may be OFDMA (orthogonal frequency division multiple access) communication or MU-MIMO communication. For OFDMA communication in a channel, the AP 114 simultaneously transmits multiple streams to the STAs 116, 118, and 120 in the network at different resource units (RUs) within the channel bandwidth. For MU-MIMO communication in a channel, the AP 114 simultaneously transmits multiple streams to the STAs 116, 118, and 120 at the same RU(s) within the channel bandwidth using multiple antennas via spatial mapping or precoding techniques. When the RU(s) in which OFDMA or MU-MIMO communication occurs occupy 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 occurs occupy 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 STA 118, another space-time stream may be directed to STA 116, and yet another space-time stream may be directed to STA 120. For simplicity, the two space-time streams directed to STA 118 are shown as grouped data transmission arrow 124, the space-time stream directed to STA 116 is shown as data transmission arrow 122, and the space-time stream directed to STA 120 is shown as data transmission arrow 126.

[0027] To enable uplink MU transmissions, trigger-based communication is provided in a MIMO wireless network. In this regard, Figure 1C shows a schematic diagram of trigger-based uplink MU communication 128 between an AP 130 and multiple STAs 132, 134, 136 in a MIMO wireless network.

[0028] Because multiple STAs 132, 134, 136 participate in trigger-based uplink MU communications, the AP 130 must coordinate the simultaneous transmissions of the multiple STAs 132, 134, 136.

[0029] 1C , the AP 130 simultaneously transmits trigger frames 139, 141, and 143 to the STAs 132, 134, and 136 to indicate user-specific resource allocation information (e.g., the number of space-time streams, the number of starting STSs, and the assigned RUs) available to each STA. In response to the trigger frames, the STAs 132, 134, and 136 may then simultaneously transmit their respective space-time streams to the AP 130 according to the user-specific resource allocation information indicated in the trigger frames 139, 141, and 143. For example, two space-time streams may be directed from the STA 134 to the AP 130, another space-time stream may be directed from the STA 132 to the AP 130, and yet another space-time stream may be directed from the STA 136 to the AP 130. For simplicity, the two space-time streams directed from STA 134 to AP 130 are shown as grouped data transmission arrow 140, the space-time stream directed from STA 132 to AP 130 is shown as data transmission arrow 138, and the space-time stream directed from STA 136 to AP 130 is shown as data transmission arrow 142.

[0030] Trigger-based communication is also provided in MIMO wireless networks to enable downlink multi-AP communication. In this regard, Figure 1D shows a schematic diagram of downlink multi-AP communication 144 between a STA 150 and multiple APs 146, 148 in a MIMO wireless network.

[0031] Since multiple APs 146, 148 participate in this trigger-based downlink multi-AP MIMO communication, the master AP 146 needs to coordinate the simultaneous transmissions of the multiple APs 146, 148.

[0032] 1D , the master AP 146 simultaneously transmits trigger frames 147, 153 to the AP 148 and the STA 150 to indicate AP-specific resource allocation information (e.g., the number of space-time streams, the number of starting STS streams, and the assigned RUs) that each AP can use. In response to the trigger frames, the multiple APs 146, 148 may then transmit their respective space-time streams to the STA 150 according to the AP-specific resource allocation information indicated in the trigger frame 147. The STA 150 may then receive all the space-time streams according to the AP-specific resource allocation information indicated in the trigger frame 153. For example, two space-time streams may be directed from the AP 146 to the STA 150, and two other space-time streams may be directed from the AP 148 to the STA 150. For simplicity, the two space-time streams directed from AP 146 to STA 150 are shown as grouped data transmission arrow 152, and the two space-time streams directed from AP 148 to STA 150 are shown as grouped data transmission arrow 154.

[0033] Due to the packet / PPDU (physical layer protocol data unit) based transmission and distributed MAC (medium access control) scheme in 802.11 WLAN, there is no time scheduling (e.g., periodic time slot allocation for data transmission similar to TDMA (time division multiple access)) in 802.11 WLAN. Frequency and spatial resource scheduling is done on a packet basis. In other words, resource allocation information is PPDU-based.

[0034] According to various embodiments, the EHT WLAN supports non-trigger-based communication as shown in Figures 1A and 1B and trigger-based communication as shown in Figures 1C and 1D. In non-trigger-based communication, a communication device spontaneously transmits a PPDU to one other communication device or two or more other communication devices. In trigger-based communication, a communication device transmits a PPDU to one other communication device or two or more other communication devices only after receiving a soliciting trigger frame.

[0035] 2A illustrates a single-AP-based sounding procedure 200 between two STAs 202, 204 in an 11ax HE WLAN. The single-AP-based sounding procedure 200 may be initiated when STA1 202, e.g., an AP, generates an HE NDP (Null Data Packet) announcement frame 206 for a target STA, e.g., STA2 204. The HE NDP announcement frame 206 includes per-STA requested sounding feedback parameters, such as feedback bandwidth, feedback type, subcarrier grouping, quantization resolution, and the number of columns of a compressed beamforming feedback matrix. The feedback type is one of SU feedback, MU feedback, and CQI (channel quality indicator) feedback. When the feedback type is SU feedback or MU feedback, the requested sounding feedback information includes compressed beamforming feedback information for each subcarrier or subcarrier group. When the feedback type is CQI feedback, the requested sounding feedback information includes CQI information for each subcarrier or subcarrier group. In IEEE 802.11 networks, short interframe spacing (SIFS) is the time interval before a STA transmits an acknowledgment. Upon transmission of the HE NDP announcement frame 206, SIFS 207 may be enabled, and STA1 202 may transmit an HE sounding NDP 210 to STA2 204 at 208. The HE sounding NDP 210 may include an HE Long Training Field (HE-LTF) for CSI (channel state information) estimation.

[0036] After the last symbol of the HE sounding NDP 210 is transmitted, SIFS 211 may be enabled, and at 212, STA2 204 may transmit an HE compressed beamforming / CQI frame 214 including sounding feedback information to STA1 202. In one embodiment, the sounding feedback information may be derived by STA2 204 from CSI, which is estimated from the HE-LTF field of the HE sounding NDP 210, and tailored according to its requested sounding feedback parameters indicated in the HE NDP announcement frame 206. Based on the sounding feedback information received from STA2 204, STA1 202 may be able to determine steering matrices and / or allocate appropriate resource units (RUs) for subsequent transmissions to STA2 204.

[0037] 2B illustrates a single-AP-based sounding procedure 220 between an AP 222 and multiple STAs 224, 226 in an 11ax HE WLAN. The single-AP-based sounding procedure 220 may be initiated when the AP 222 generates an HE NDP announcement frame 228 for target STAs, such as STA1 224 and STA2 226. The HE NDP announcement frame 228 includes requested sounding feedback parameters for each STA, such as feedback bandwidth, feedback type, subcarrier grouping, quantization resolution, and the number of columns of the compressed beamforming feedback matrix. The feedback type is one of SU feedback, MU feedback, and CQI feedback. When the feedback type is SU feedback or MU feedback, the requested sounding feedback information includes compressed beamforming feedback information for each subcarrier or subcarrier group. When the feedback type is CQI feedback, the requested sounding feedback information includes CQI information for each subcarrier or subcarrier group. Upon transmission of the HE NDP announcement frame 228, SIFS 229 may be enabled and at 230, the AP 222 may transmit an HE sounding NDP 232 to STA1 224 and STA2 226.

[0038] After the HE sounding NDP 232 is transmitted, the SIFS 233 may be enabled, and at 234, the AP 222 may transmit a Beamforming Report Poll (BFRP) trigger frame 236 to solicit simultaneous transmission of sounding feedback information from STA1 224 and STA2 226.

[0039] After the last symbol of the BFRP trigger frame 236 is transmitted, SIFS 237 may be enabled, and at 238, STA1 224 and STA2 226 may simultaneously transmit respective HE compressed beamforming / CQI frames 240, 242 containing respective sounding feedback information to the AP 222. In one embodiment, the sounding feedback information may be derived by STA1 224 and STA2 226 from their respective CSI, which is estimated from the HE-LTF field of the HE sounding NDP 232 and prepared according to respective sounding feedback parameters indicated in the HE NDP announcement frame 228. Based on the sounding feedback information received from STA1 224 and STA2 226, the AP 222 may be able to determine steering matrices and / or allocate appropriate RUs to each of STA1 224 and STA2 226 for subsequent transmissions for STA1 224 and / or STA2 226.

[0040] It should be noted that in an 11ax HE WLAN, the AP and STA(s) engaged in a single-AP-based sounding procedure belong to a single BSS (basic service set). Therefore, in order to improve throughput in an 11be EHT WLAN compared to an 11ax HE WLAN, it is an object of the present disclosure to substantially overcome the existing challenges to provide a communication apparatus and method for channel sounding that enables multi-AP coordination in a multi-AP system.

[0041] According to the present disclosure, a multi-AP coordination setup procedure is performed among APs to form a multi-AP coordination candidate set. The multi-AP coordination candidate set includes a sharing AP and one or more shared APs. During multi-AP coordination setup, an AP set identifier (ID) is assigned to the multi-AP coordination candidate set, where each AP in the multi-AP coordination candidate set may be assigned an AP ID, which, together with the AP set ID, uniquely identifies a specific AP in the multi-AP coordination candidate set. In some embodiments, during multi-AP coordination setup, capability negotiation may be performed among the APs in the multi-AP coordination candidate set. Alternatively, capability negotiation may be performed among the APs in the multi-AP coordination candidate set before the multi-AP coordination setup procedure, for example, using a backhaul. In some embodiments, during multi-AP coordination setup, a target STA may indicate a preferred AP in the multi-AP coordination candidate set for multi-AP coordination operation.

[0042] After the multi-AP coordination setup procedure is completed, each AP in the multi-AP coordination candidate set may indicate multi-AP coordination-related information, such as multi-AP coordination candidate set information, the AP's capabilities including AP sounding capability and multi-AP coordination capability, etc., in a beacon frame, etc.

[0043] In various embodiments, before initiating a sounding procedure for multi-AP operation, the source AP of the multi-AP coordination candidate set may initiate a sounding setup procedure with each destination AP(s) of the multi-AP coordination candidate set to make the necessary preparations for the sounding procedure.

[0044] 3A shows a partially segmented schematic diagram of a communication device 300 according to the present disclosure. The communication device 300 may also be implemented as an AP or a STA.

[0045] 3A, the communications device 300 may include circuitry 314, at least one wireless transmitter 302, at least one wireless receiver 304, and at least one antenna 312 (for simplicity, only one antenna is shown in FIG. 3A for illustrative purposes). The circuitry 314 may include at least one controller 306, which is used with the assistance of software and hardware to perform the tasks the at least one controller 306 is designed to perform, including controlling communications with one or more other communications devices in a MIMO wireless network. The circuitry 314 may further include at least one transmit signal generator 308 and at least one receive signal processor 310. The at least one controller 306 may control at least one transmit signal generator 308 to generate and transmit MAC frames (e.g., EHT action frames, etc.) and PPDUs (e.g., PPDUs used for non-triggered communication or PPDUs used for triggered-based multi-AP joint transmission when, for example, the communication device 300 is an AP, and PPDUs used for non-triggered communication or PPDUs used for triggered-based uplink transmission when, for example, the communication device 300 is an STA) to one or more other communication devices via the at least one wireless transmitter 302, and may control the at least one receive signal processor 310 to process MAC frames (e.g., EHT action frames) and PPDUs (e.g., PPDUs used for non-triggered communication or PPDUs used for triggered-based uplink transmission when, for example, the communication device 300 is an AP, and PPDUs used for non-triggered communication or PPDUs used for triggered-based multi-AP joint transmission when, for example, the communication device 300 is an STA) received from one or more other communication devices via the at least one wireless receiver 304 under the control of the at least one controller 306.As shown in FIG. 3A , the at least one transmit signal generator 308 and the at least one receive signal processor 310 may be standalone modules of the communication device 300 that communicate with the at least one controller 306 for the above-described functions. Alternatively, the at least one transmit signal generator 308 and the at least one receive signal processor 310 may be included in the at least one controller 306. Those skilled in the art will recognize that the arrangement of these functional modules is flexible and may vary depending on actual needs and / or requirements. Data processing, storage, and other related control devices may be provided on an appropriate circuit board and / or within a chipset. In various embodiments, during operation, the at least one wireless transmitter 302, the at least one wireless receiver 304, and the at least one antenna 312 may be controlled by the at least one controller 306.

[0046] During operation, the communications device 300 provides the functionality necessary for single-AP or multi-AP-based channel sounding. For example, the communications device 300 may be an AP (e.g., a sharing AP), and the circuit 314 (e.g., at least one transmit signal generator 308 of the circuit 314) may, during operation, generate a first frame (e.g., a sounding setup request frame) including a first field indicating a target use of the sounding procedure. During operation, the wireless transmitter 302 may transmit the first frame to each of one or more peer communications devices (e.g., a sharing AP). In one embodiment, the wireless receiver 304 may, during operation, receive a second frame (e.g., a sounding setup response frame) from each of the one or more peer communications devices, the second frame including a first field indicating one or more recommended types of sounding procedures. In another embodiment, the circuitry 314 (e.g., the at least one transmit signal generator 308 of the circuitry 314) may further generate, during operation, a third frame (e.g., an EHT NDP announcement frame) that initiates the sounding procedure.

[0047] The communications device 300 may be a peer AP (e.g., a sharing AP), and the wireless receiver 304 may, during operation, receive a first frame (e.g., a sounding setup request frame) from one other communications device (e.g., a sharing AP) that includes a first field indicating a target use of the sounding procedure. The circuit 314 (e.g., at least one receive signal processor 310 of the circuit 314) may, during operation, process the first frame. In one embodiment, the wireless transmitter 302 may, during operation, transmit a second frame (e.g., a sounding setup response frame) to the one other communications device, the second frame including a first field indicating one or more recommended types of sounding procedures.

[0048] 3B shows a flow chart illustrating a communication method according to the present disclosure. In step 318, a step of generating a first frame for a sounding procedure is performed. In step 320, a step of transmitting the first frame to each of one or more peer communication devices is performed, where the first frame includes a first field indicating an intended use of the sounding procedure.

[0049] In one embodiment, the first frame may include a second field indicating a target type of the sounding procedure, hi another embodiment, the first frame may include a third field indicating one or more target communication devices (e.g., STAs) that will be engaged in the sounding procedure.

[0050] FIG. 4 shows a flowchart illustrating a sounding setup procedure 400 between two APs, specifically, a sharing AP 402 and a sharing AP 404, in accordance with the present disclosure. A contention-based channel access procedure, such as an enhanced distributed channel access (EDCA) procedure, is indicated by blocks 405 and 413, and additionally includes SIFSs ​​409 and 417. The sounding setup procedure includes sounding setup request and response frames exchanged between the sharing AP and each sharing AP(s) in the multi-AP coordination candidate set. The sounding setup request or response frame is an EHT action frame. In particular, the sharing AP 402 may generate a first frame 408, such as an EHT action frame (hereinafter referred to as a “sounding setup request frame”) containing a sounding setup request, to initiate the sounding setup procedure 400. A radio transmitter of the sharing AP 402 may transmit the sounding setup request frame 408 to the sharing AP 404.

[0051] Upon receipt of the sounding setup request frame 408, the SIFS 409 may be enabled, and at 410, the sharer AP 404 may send an acknowledgement (Ack) frame 412 to the source AP 402 to indicate successful receipt of the sounding setup request frame 408.

[0052] After the last symbol of the Ack frame 412 is transmitted, the shared AP 404 may generate a second frame 416, such as an EHT action frame (hereinafter referred to as a "sounding setup request frame") that includes a sounding setup response to the sounding setup request frame 408 to indicate whether the shared AP 404 is ready for further sounding procedures.

[0053] Upon receipt of the sounding setup response frame 416, SIFS 417 may be enabled and at 418 the source AP 402 may send an Ack frame 420 to the destination AP 404 to indicate successful receipt of the sounding setup response frame 416.

[0054] 5A shows an example of the format of an EHT action frame 500 that can be used as the sounding setup request frame 408 or the sounding setup response frame 416 shown in FIG. 4. The EHT action frame 500 may include (or consist of) a frame control field, a duration field, three address fields (addresses 1, 2, and 3, respectively), a sequence control field, a high throughput (HT) control field, a frame body field 502, and a frame check sequence (FCS) field. The frame control field, duration field, three address fields (addresses 1, 2, and 3, respectively), sequence control field, and HT control field may be grouped as a MAC header. The frame body field 502 may further include a category field, an EHT action field, a dialog token field, a sounding setup element field 504, and other elements or fields.

[0055] 5B shows an example of the format of the sounding setup element field 504 of the EHT action frame 500 when the action type field 506 indicates “request,” indicating a sounding setup request frame. The sounding setup element field 504 may include (or consist of) an element ID field, a length field, an extended element ID field, an action type field 506, and an AP set ID field 508. When the action type field 506 indicates “request,” the sounding setup element field 502 may further include a target sounding usage field 510, a target sounding type field 512, and a target STA field 514. The AP set ID field 508 identifies a multi-AP coordination candidate set including the sharing AP and at least one shared AP. The target STA field 514 indicates one or more STAs belonging to the sharing AP's BSS and / or the BSS of at least one shared AP that are considered to engage in the subsequent sounding procedure. It should be noted that in an 11be EHT WLAN, the AP(s) and STA(s) engaged in a single-AP or multi-AP based sounding procedure may belong to different BSSs. In an 11be EHT WLAN, a STA may be identified by the BSSID (BSS identifier) ​​of the AP with which it is associated and its own STA ID. Alternatively, a STA may be identified by the AP ID of the AP with which it is associated, the AP set ID of a multi-AP coordination candidate set that includes that AP, and its own STA ID. Further details of the target sounding usage field 510 and the target sounding type field 512 are detailed below.

[0056] 5C shows another example of the format of the sounding setup element field 504 for an EHT action frame 500 when the action type field 506 indicates "response," indicating a sounding setup response frame. Similarly, the sounding setup element field 504 may include (or consist of) an element ID field, a length field, an extended element ID field, an action type field 506, and an AP set ID field 508. When the action type field indicates "response," the sounding setup element field 504 may further include a recommended sounding type field 514 to indicate one or more recommended types of sounding procedures. Further details of the recommended sounding type field 514 are detailed below.

[0057] The sharing AP 402 may determine the target sounding parameters, such as the target sounding application and the target sounding type, based on capability negotiations between APs in the multi-AP coordination candidate set that occur before the sounding setup procedure.

[0058] The target sounding usage field 510 indicates the target usage of the sounding procedure following the sounding setup procedure (i.e., the target scheme for multi-AP coordination using the results of the sounding procedure). The target scheme for multi-AP coordination is one of the following: Coordinated spatial reuse Coordinated Orthogonal Frequency Division Multiple Access (OFDMA) Coordinated beamforming, and Joint beamforming (also known as joint transmission).

[0059] The subject sounding type field 512 indicates the subject type of the sounding procedure that follows the sounding setup procedure, which is one of the following: Single AP-based explicit sounding, Single AP-based implicit sequential sounding, Single AP-based implicit joint sounding, Multi-AP based explicit sequential sounding, Multi-AP based explicit joint sounding, Multi-AP based implicit sequential sounding, Multi-AP based implicit joint sounding, Multi-AP based hybrid sequential sounding, and Multi-AP based hybrid joint sounding.

[0060] Additionally, in the sounding setup response frame 416, the preferred sounding type field 514 indicates one or more preferred types of sounding procedures to follow the sounding setup procedure, which may be one of the following: Single AP-based explicit sounding, Single AP-based implicit sequential sounding, Single AP-based implicit joint sounding, Multi-AP based explicit sequential sounding, Multi-AP based explicit joint sounding, Multi-AP based implicit sequential sounding, Multi-AP based implicit joint sounding, and · An exemption from multi-AP based sounding is requested.

[0061] Note that when the shared AP 404 makes any recommendation of a sounding type in the recommended sounding type field 514, the shared AP 404 should take into account the target scheme of multi-AP coordination. As an example, the results of multi-AP based sequential sounding cannot be used for joint beamforming. As another example, the results of single-AP based sounding can be used for coordinated spatial reuse and coordinated OFDMA, but cannot be used for coordinated beamforming and joint beamforming.

[0062] After receiving the sounding setup request frame 408 from the sharing AP 402, the sharing AP 404 may determine whether it needs to reconfigure its transmit and receive (TX / RX) chains for the subsequent sounding procedure according to the information about the target STA(s) indicated in the sounding setup request frame 408.

[0063] According to an embodiment of the present disclosure, when the shared AP 404 is not prepared for the target sounding type indicated in the sounding setup request frame 408, the shared AP 404 may recommend one or more different sounding types in the sounding setup response frame 416 or may request to be exempted from subsequent sounding procedures.

[0064] According to another embodiment of the present disclosure, when the shared AP 404 supports single-AP-based implicit sounding or multi-AP-based implicit sounding and its TX / RX chains are being reconfigured for a subsequent sounding procedure, a calibration procedure may be initiated by the shared AP 404 to recalibrate its TX / RX chains before sending a sounding setup response frame 416 to the sharing AP 402. However, if the calibration procedure is not successfully completed, the shared AP 404 may not recommend any single-AP-based or multi-AP-based implicit sounding procedures.

[0065] After the sounding setup procedure between the source AP and each target AP(s) in the multi-AP coordination candidate set is completed, the sounding procedure may be initiated by transmitting an EHT NDP announcement frame indicating one of the following sounding procedure types: Single AP-based explicit sounding, Single AP-based implicit sequential sounding, Single AP-based implicit joint sounding, Multi-AP based explicit sequential sounding, Multi-AP based explicit joint sounding, Multi-AP based implicit sequential sounding, Multi-AP based implicit joint sounding, Multi-AP based hybrid sequential sounding, and Multi-AP based hybrid joint sounding.

[0066] An EHT NDP announcement frame that initiates the multi-AP based sounding procedure may be transmitted by the sharing AP.

[0067] 6A shows a flowchart illustrating a single-AP-based explicit sounding procedure 600 between two STAs 602, 604 in an 11be EHT WLAN according to an embodiment. The single-AP-based explicit sounding procedure 600 may be initiated when STA1 602, for example, an AP, transmits an EHT NDP announcement frame 606 to a target STA, for example, STA2 604. The EHT NDP announcement frame 606 includes per-STA requested sounding feedback parameters, such as feedback bandwidth, feedback type, subcarrier grouping, quantization resolution, and the number of columns of the compressed beamforming feedback matrix. The feedback type is one of SU feedback, MU feedback, CQI feedback, and calibration feedback. When the feedback type is SU feedback or MU feedback, the requested sounding feedback information includes compressed beamforming feedback information for each subcarrier or subcarrier group. When the feedback type is CQI feedback, the requested sounding feedback information includes CQI information for each subcarrier or subcarrier group. When the feedback type is calibration feedback, the required sounding feedback information includes compressed CSI per subcarrier or subcarrier group. Upon reception of the EHT NDP announcement frame 606, SIFS 607 may be enabled, and STA1 602 may send an EHT sounding NDP 610 to STA2 604 at 608. The EHT sounding NDP 610 may include an EHT-LTF field for CSI estimation.

[0068] After the last symbol of the EHT sounding NDP 610 is transmitted, SIFS 611 may be enabled, and at 612, STA2 604 may transmit an EHT compressed beamforming / CQI frame 614 containing sounding feedback information to STA1 602. In one embodiment, the sounding feedback information may be derived by STA2 604 from CSI, which is estimated from the EHT-LTF field of the EHT sounding NDP 610 and adjusted according to its sounding feedback parameters indicated in the EHT NDP announcement frame 606. Based on the sounding feedback information received from STA2 604, STA1 602 may be able to determine steering matrices and / or allocate appropriate RUs for subsequent transmissions to STA2 604.

[0069] 6B shows a flowchart illustrating a single-AP-based explicit sounding procedure 620 between an AP 622 and multiple STAs 624, 626 in an 11be EHT WLAN according to another embodiment. The single-AP-based explicit sounding procedure 620 may be initiated when the AP 622 transmits an EHT NDP announcement frame 628 to target STAs, such as STA1 624 and STA2 626. Similarly, the EHT NDP announcement frame 628 may include requested sounding feedback parameters for each STA, such as feedback bandwidth, feedback type, subcarrier grouping, quantization resolution, and the number of columns of the compressed beamforming feedback matrix. The feedback type is one of SU feedback, MU feedback, CQI feedback, and calibration feedback. When the feedback type is SU feedback or MU feedback, the requested sounding feedback information includes compressed beamforming feedback information for each subcarrier or subcarrier group. When the feedback type is CQI feedback, the requested sounding feedback information includes CQI information per subcarrier or subcarrier group. When the feedback type is calibration feedback, the requested sounding feedback information includes compressed CSI per subcarrier or subcarrier group. Upon transmitting the EHT NDP announcement frame 628, SIFS 629 may be enabled, and at 630, the AP 622 may transmit an EHT sounding NDP 632 to STA1 624 and STA2 626.

[0070] After the EHT sounding NDP 632 is transmitted, SIFS 633 may be enabled, and at 634, the AP 622 may transmit an EHT BFRP trigger frame 636 to request simultaneous transmission of sounding feedback information from STA1 624 and STA2 626. After the last symbol of the EHT BFRP trigger frame 636 is transmitted, SIFS 637 may be enabled, and at 638, STA1 624 and STA2 626 may simultaneously transmit respective EHT compressed beamforming / CQI frames 640, 642 containing sounding feedback information to the AP 622. In an embodiment, the sounding feedback information may be derived by STA1 624 and STA2 626 from their respective CSI, which is estimated from the EHT-LTF field of the EHT sounding NDP 632 and prepared according to the respective sounding feedback parameters indicated in the EHT NDP announcement frame 628. Based on the sounding feedback information received from STA1 624 and STA2 626, the AP 622 can determine steering matrices and / or allocate appropriate RUs to each of STA1 624 and STA2 626 for subsequent transmissions to STA1 624 and / or STA2 626.

[0071] According to the present disclosure, when the sounding type indicated in the EHT NDP announcement frames 606, 628 is single-AP-based explicit sounding and the feedback type indicated in the EHT NDP announcement frames 606, 628 is SU, MU, or CQI feedback, the procedures 600, 620 are normal single-AP-based explicit sounding procedures. On the other hand, when the sounding type indicated in the EHT NDP announcement frames 606, 628 is single-AP-based explicit sounding and the feedback type indicated in the EHT NDP announcement frames 606, 628 is calibration feedback, the procedures 600, 620 are single-AP-based calibration procedures. In other words, the single-AP-based calibration procedure is a variation of the single-AP-based explicit sounding procedure shown in Figures 6A and 6B. Advantageously, according to the present disclosure, a single procedure 600, 620 can be used for both calibration and explicit sounding purposes.

[0072] In various embodiments, when the procedure 620 is a single-AP-based calibration procedure, the EHT NDP announcement frame 628 may indicate a calibration RU assignment and a calibration spatial stream (SS) assignment for each of STA1 624 and STA2 626. In particular, the data RU assignment and data SS assignment for each of STA1 624 and STA2 626 are indicated in the corresponding EHT BFRP trigger frame 636. The calibration SS assigned to a STA may include the data SS assigned to that STA. In other words, the number of calibration SSs may be equal to or greater than the number of data SSs. In addition, the calibration RU assigned to a STA may be the same as the data RU assigned to that STA.

[0073] In various embodiments, when the procedure 600, 620 is a single-AP-based calibration procedure, the EHT compressed beamforming / CQI frames 614, 640, 642 may include DL compressed CSI information instead of DL compressed beamforming feedback information. Furthermore, each STA, e.g., STA2 604, STA1 624, STA2 626, transmits multiple SSs on the EHT-LTF field of the EHT PPDU that includes the EHT compressed beamforming / CQI frames 614, 640, 642, which is used for UL CSI estimation for data demodulation and calibration. In this manner, the APs 602, 622 may be able to determine calibration coefficients for each of their TX antennas according to the DL compressed CSI information included in the EHT compressed beamforming / CQI frames 614, 640, 642 and the UL CSI estimation.

[0074] 7A shows a flowchart illustrating a single-AP-based implicit sequential sounding procedure 700 between an AP 702 and multiple STAs 704, 706 in an 11be EHT WLAN according to one embodiment (Option 1). The single-AP-based implicit sequential sounding procedure 700 may begin when the AP 702 transmits a first EHT NDP announcement frame 708 to target STAs, such as STA1 704 and STA2 706. The first EHT NDP announcement frame 708 may indicate an STA ordering, and the target STAs, such as STA1 704-STA2 706, may transmit EHT sounding NDPs to the AP 702 in this STA ordering. Additionally, the first EHT NDP announcement frame 708 may indicate a sounding RU assignment and a sounding SS assignment for the first STA in the STA ordering. After receiving the EHT NDP announcement frame 708, STA(s) other than the first STA in the STA ordering, e.g., STA2 706, may switch from an awake state to a doze state for power saving. At 711 after SIFS 709, the first STA in the STA ordering, e.g., STA1 704, may prepare a first EHT sounding NDP 712 based on its sounding RU assignment and sounding SS assignment and send it to the AP 702. The AP 702 may then determine the DL CSI corresponding to STA1 704 by estimating the first UL CSI from the received first EHT sounding NDP 712 and compensating the first UL CSI according to calibration parameters obtained from the calibration procedure.

[0075] After the last symbol of the first EHT sounding NDP 712 is transmitted at 713, STA1 704 may switch from the awake state to the doze state to save power. During SIFS 714, the next STA in the STA ordering, e.g., STA2 706, may switch from the doze state back to the awake state at 715. After SIFS 714, the AP 702 may transmit a second EHT NDP announcement frame 718 at 716, which may indicate the sounding RU and SS assignments for the next STA in the STA ordering. Upon transmission of the second EHT NDP announcement frame 718, SIFS 719 may become effective, and at 720, STA2 706 may prepare a second EHT sounding NDP 722 based on its sounding RU and SS assignments and transmit it to the AP 702. The AP 702 may then determine the DL CSI corresponding to STA2 706 by estimating the second UL CSI from the received second EHT sounding NDP 722 and compensating the second UL CSI according to the calibration parameters obtained from the calibration procedure. Further, based on the DL CSI for STA1 704 and STA2 706, the AP 702 may be able to determine steering matrices and / or allocate appropriate RUs to each of STA1 704 and STA2 706 for subsequent transmissions to STA1 704 and / or STA2 706. Advantageously, the single-AP-based implicit sequential sounding procedure shown in FIG. 7A may require less sounding overhead than the single-AP-based explicit sounding procedure shown in FIG. 6B because it does not require transmission of sounding feedback information.

[0076] 7B shows a flowchart illustrating a single-AP-based implicit sequential sounding procedure 730 between an AP 732 and multiple STAs 734, 736 in an 11be EHT WLAN according to another embodiment (Option 2). Similarly, the single-AP-based implicit sequential sounding procedure 730 may be initiated when the AP 732 transmits an EHT NDP announcement frame 738 to target STAs, e.g., STA1 734 and STA2 736. The EHT NDP announcement frame 738 may indicate a STA ordering, and the target STAs, e.g., STA1 734-STA2 736, may transmit EHT sounding NDPs to the AP 732 in this STA ordering. The EHT NDP announcement frame 738 may indicate a sounding RU assignment and a sounding SS assignment for each of the target STAs. Thus, from the sounding SS assignments for the STAs, the duration of the EHT-LTF field of the EHT sounding NDP transmitted by each STA (equivalent to the transmission time of the EHT sounding NDP) can be determined. Based on the transmission time of the EHT sounding NDP of each STA, a first EHT sounding NDP from a first STA in the STA ordering can be followed by a second EHT sounding NDP from a second STA in the STA ordering.

[0077] For example, upon transmission of EHT NDP announcement frame 738, SIFS 739 may be enabled, and during SIFS 739, a STA other than the first STA in the STA ordering, e.g., STA2 706, may be switched from an awake state to a doze state for power savings at 740, and after SIFS 741, the first STA in the STA ordering, e.g., STA1 734, may transmit a first EHT sounding NDP 742 to the AP 732. The AP 732 may then determine the DL CSI corresponding to STA1 734 by estimating a first UL CSI from the received first EHT sounding NDP 742 and compensating the first UL CSI according to calibration parameters obtained from the calibration procedure. After the last symbol of the first EHT sounding NDP 742 is transmitted at 743, STA1 734 may switch from an awake state to a doze state for power savings. A SIFS 744 may be enabled, during which STA2 736 may switch from a doze state to an awake state at 745, and after SIFS 744, STA2 736 may transmit a second EHT sounding NDP 748 to the AP 732 at 746. The AP 732 may then determine DL CSI corresponding to STA2 736 by estimating second UL CSI from the received EHT sounding NDP 748 and compensating the second UL CSI according to calibration parameters obtained from the calibration procedure. Further, based on the DL CSI for STA1 734 and STA2 736, the AP 732 may be able to determine steering matrices and / or allocate appropriate RUs to each of STA1 734 and STA2 736 for subsequent transmissions for STA1 734 and / or STA2 736. Advantageously, the single AP-based implicit sequential sounding option 2 shown in FIG. 7B further reduces the sounding overhead than the single AP-based implicit sequential sounding option 1 shown in FIG. 7A.

[0078] 8 shows a flowchart illustrating a single-AP-based implicit joint sounding procedure 800 between an AP 802 and multiple STAs 804, 806 in an 11be EHT WLAN, according to an embodiment. The single-AP-based implicit joint sounding procedure 800 may be initiated when the AP 802 transmits an EHT NDP announcement frame 808 to target STAs, such as STA1 804 and STA2 806. The EHT NDP announcement frame 808 may indicate sounding RU and sounding SS assignments for each of the target STAs. Upon transmission of the EHT NDP announcement frame 808, a SIFS 809 may be enabled, and at 810, STA1 804 and STA2 806 may transmit respective EHT sounding NDPs 812, 814 to the AP 808 according to their respective sounding RU and sounding SS assignments. The AP 802 may then determine DL CSI corresponding to each of STA1 804 and STA2 806 by estimating the first UL CSI from the received EHT sounding NDP 812 and the second UL CSI from the received EHT sounding NDP 814, and compensating the first UL CSI and the second UL CSI according to the calibration parameters obtained from the calibration procedure. Further, based on the DL CSI for STA1 804 and STA2 806, the AP 802 may be able to determine steering matrices and / or allocate appropriate RUs to each of STA1 804 and STA2 806 for subsequent transmissions for STA1 804 and / or STA2 806. Advantageously, the single-AP-based implicit joint sounding shown in FIG. 8 may have lower sounding overhead than the single-AP-based implicit sequential sounding shown in FIG. 7A and 7B.

[0079] 9 shows a flowchart illustrating a multi-AP-based explicit sequential sounding procedure 900 between multiple APs 902, 904 and multiple STAs 906, 908 in an 11be EHT WLAN, according to an embodiment. The multi-AP-based explicit sequential sounding procedure 900 may be initiated when a sharing AP 902 transmits a first EHT NDP announcement frame 910 to a sharing AP(s) participating in the sounding procedure 1000 and to target STAs, e.g., STA1 906 and STA2 908. The first EHT NDP announcement frame 910 may indicate a sharing AP ordering, and the sharing AP(s) engaged in the sounding procedure 900 may transmit the EHT NDP announcement frame and the EHT sounding NDP to the target STAs, e.g., STA1 906 and STA2 908, in this sharing AP ordering. The first EHT NDP announcement frame 910 may indicate sounding RU allocations and sounding SS allocations for each shared AP(s) engaged in the sounding procedure 900. Each EHT NDP announcement frame may indicate requested sounding feedback parameters for each STA, such as feedback bandwidth, feedback type, subcarrier grouping, quantization resolution, and the number of columns of the compressed beamforming feedback matrix. The feedback type is one of SU feedback, MU feedback, CQI feedback, and calibration feedback. When the feedback type is SU feedback or MU feedback, the requested sounding feedback information includes compressed beamforming feedback information for each subcarrier or subcarrier group. When the feedback type is CQI feedback, the requested sounding feedback information includes CQI information for each subcarrier or subcarrier group. When the feedback type is calibration feedback, the requested sounding feedback information includes compressed CSI for each subcarrier or subcarrier group.

[0080] Upon transmission of the first EHT NDP announcement frame 910, SIFS 911 may be enabled, and at 912, the sharing AP 902 may transmit a first EHT sounding NDP 914 to STA1 906 and STA2 908. After transmitting the first EHT sounding NDP 914, SIFS 915 may be enabled, and at 916, the sharing AP 902 may transmit an EHT BFRP trigger frame 918 to request simultaneous transmission of sounding feedback information from STA1 906 and STA2 908. After the last symbol of the EHT BFRP trigger frame 918 is transmitted, SIFS 919 may be enabled, and at 920, STA1 906 and STA2 908 may simultaneously transmit their respective first EHT compressed-beamforming / CQI frames 922, 924 containing sounding feedback information to the sharing AP 902. Based on the sounding feedback information received from STA1 906 and STA2 908, the sharing AP 902 may be able to determine steering matrices and / or allocate appropriate RUs to each of STA1 906 and STA2 908 for subsequent transmissions to STA1 906 and / or STA2 908.

[0081] Upon transmission of the first EHT compressed beamforming / CQI frames 922, 924, SIFS 925 may be enabled, and at 926, the next AP in the AP ordering, e.g., shared AP 904, may transmit a second EHT NDP announcement frame 928 to STA1 906 and STA2 908. Upon transmission of the second EHT NDP announcement frame 928, SIFS 929 may be enabled, and at 930, shared AP 904 may transmit a second EHT sounding NDP 932 to STA1 906 and STA2 908. Similarly, after the second EHT sounding NDP 932 is transmitted, SIFS 933 may be enabled, and at 934, shared AP 904 may transmit an EHT BFRP trigger frame 918 to request simultaneous transmission of sounding feedback information from STA1 906 and STA2 908. After the last symbol of the EHT BFRP trigger frame 936 is transmitted, SIFS 937 may be enabled, and at 938, STA1 906 and STA2 908 may simultaneously transmit their respective second EHT compressed beamforming / CQI frames 940, 942 containing sounding feedback information to the shared AP 904. Based on the sounding feedback information received from STA1 906 and STA2 908, the shared AP 904 may be able to determine steering matrices and / or allocate appropriate RUs to each of STA1 906 and STA2 908 for subsequent transmissions to STA1 906 and / or STA2 908.

[0082] According to the present disclosure, when the sounding type indicated in the EHT NDP announcement frame 910, 1010 is multi-AP-based explicit sounding and the feedback type indicated in the EHT NDP announcement frame 910, 1010 is SU, MU, or CQI feedback, the procedure 900, 1000 is a normal multi-AP-based explicit sounding procedure. On the other hand, when the sounding type indicated in the EHT NDP announcement frame 910, 1010 is multi-AP-based explicit sounding and the feedback type indicated in the EHT NDP announcement frame 910, 1010 is calibration feedback, the procedure 900, 1000 is a multi-AP-based calibration procedure. In other words, the multi-AP-based calibration procedure is a variation of the multi-AP-based explicit sounding procedure shown in Figures 9 and 10. Advantageously, according to the present disclosure, a single procedure 900, 1000 can be used for both calibration and explicit sounding purposes.

[0083] In various embodiments, when the procedure 900, 1000 is a multi-AP-based calibration procedure, the EHT NDP announcement frames 910, 928, 1010 may indicate a calibration RU assignment and a calibration SS assignment for each STA, e.g., STA1 906, STA2 908, STA1 1006, STA2 1008. In particular, the data RU assignment and data SS assignment for each STA are indicated in the corresponding EHT BFRP trigger frame 918, 936, 1020. The calibration SS assigned to a STA may include the data SS assigned to that STA. In other words, the number of calibration SSs may be equal to or greater than the number of data SSs. The calibration RU assigned to a STA may be the same as the data RU assigned to that STA.

[0084] In various embodiments, when the procedure 900, 1000 is a multi-AP-based calibration procedure, the EHT compressed beamforming / CQI frames 922, 924, 940, 942, 1024, 1026 may include DL compressed CSI instead of DL compressed beamforming feedback information. Furthermore, each STA, e.g., STA1 906, STA2 908, STA1 1006, STA2 1008, transmits multiple SSs on the EHT-LTF field of the EHT PPDU that includes the EHT compressed beamforming / CQI frames 922, 924, 940, 942, 1024, 1026, where the EHT-LTF field is used for UL CSI estimation for data demodulation and calibration. In this manner, the APs 902, 904, 1002, 1004 may be able to determine calibration factors for each of their TX antennas according to the DL compressed CSI included in the EHT compressed beamforming / CQI frames 922, 924, 940, 942, 1024, 1026 and the UL CSI estimates.

[0085] In various embodiments, there are two options for a STA to transmit EHT-compressed beamforming / CQI frames in a multi-AP based sequential calibration procedure: i) the STA may transmit the same SS on the EHT-LTF field of multiple EHT PPDUs containing EHT-compressed beamforming / CQI frames, or ii) the STA may transmit different SS on the EHT-LTF field of multiple EHT PPDUs containing EHT-compressed beamforming / CQI frames, which may advantageously result in a reduction in EHT-LTF overhead. For example, assuming that STA1 906 or STA2 908 has four TX antennas and transmits two EHT-compressed beamforming / CQI frames, in option 1, STA1 904 and STA2 908 transmit the same SS on the EHT-LTF field of multiple EHT PPDUs containing EHT-compressed beamforming / CQI frames. 8x8 In option 2, STA1 906 and STA2 908 may transmit four SSs over eight EHT-LTF symbols of an EHT PPDU containing EHT compressed beamformed / CQI frames 922, 924, 940, 942 using the matrix, while ... 4x4The two SSs may transmit on the four EHT-LTF symbols of the EHT PPDU containing the first EHT compressed beamforming / CQI frame 922, 924 using the matrix, and STA1 906 and STA2 908 use P 4x4 The matrix may be used to transmit two other SSs over the four EHT-LTF symbols of the EHT PPDU containing the second EHT compressed beamformed / CQI frame 940, 942.

[0086] 10 shows a flowchart illustrating a multi-AP-based explicit joint sounding procedure 1000 between multiple APs 1002, 1004 and multiple STAs 1006, 1008 in an 11be EHT WLAN, according to an embodiment. The multi-AP-based explicit joint sounding procedure 1000 may be initiated when the sharing AP 1002 transmits an EHT NDP announcement frame 1010 to the sharing AP(s) participating in the sounding procedure 1000 and to the target STAs, e.g., STA1 1006 and STA2 1008. The EHT NDP announcement frame 1010 may indicate a sounding RU assignment and a sounding SS assignment for each sharing AP engaged in the sounding procedure 1000. The EHT NDP announcement frame 1010 may indicate required sounding feedback parameters for each STA-AP pair among the sharing AP 1002, the sharing AP 1004, and the target STAs 1006, 1008. The required sounding feedback parameters for each AP-STA pair may include AP-dependent sounding feedback parameters, such as feedback bandwidth and the number of columns in the compressed beamforming feedback matrix, and AP-independent sounding feedback parameters, such as feedback type, subcarrier grouping, and quantization resolution, where, in terms of the sounding results used for joint beamforming, for the STA, each AP-independent sounding feedback parameter may be set to the same value for all AP-STA pairs in the EHT NDP announcement frame 1010, while each AP-dependent sounding feedback parameter may be set to a different value for each AP-STA pair in the EHT NDP announcement frame 1010.

[0087] Upon transmission of the EHT NDP announcement frame 1010, SIFS 1011 may be enabled, and at 1012, all APs engaged in the sounding procedure 1000, e.g., the sharing AP 1002 and the sharing AP 1004, may simultaneously transmit their respective EHT sounding NDPs 1014, 1016 to all target STAs, e.g., STA1 1006 and STA2 1008. After the EHT sounding NDPs 1014, 1016 are transmitted, SIFS 1017 may be enabled, and at 1018, AP 1002 may transmit an EHT BFRP trigger frame 1020 to request simultaneous transmission of sounding feedback information from STA1 1006 and STA2 1008. After the last symbol of the EHT BFRP trigger frame 1020 is transmitted, SIFS 1021 may be enabled, and at 1022, STA1 1006 and STA2 1008 may simultaneously transmit their respective EHT compressed beamformed / CQI frames 1024, 1026 containing the required sounding feedback information to the APs 1002, 1004. Based on the sounding feedback information received from STA1 1006 and STA2 1008, the APs 1002, 1004 may be able to determine steering matrices and / or allocate appropriate RUs to each of STA1 1006 and STA2 1008 for subsequent transmissions to STA1 1006 and / or STA2 1008. Alternatively, the sharing AP 1002 may be able to determine steering matrices and / or allocate appropriate RUs to each AP-STA pair. The sharer AP 1002 may then inform the sharer AP 1004 of the corresponding steering matrices and / or RU allocations for STA1 1006 and STA2 1008 for subsequent transmissions to STA1 1006 and / or STA2 1008. Advantageously, the multi-AP based explicit joint sounding shown in FIG. 10 has less sounding overhead than the multi-AP based explicit sequential sounding shown in FIG.

[0088] 11A shows a flowchart illustrating a multi-AP-based implicit sequential sounding procedure 1100 between multiple APs 1102, 1104 and multiple STAs 1106, 1108 in an 11be EHT WLAN according to one embodiment (Option 1). The multi-AP-based implicit sequential sounding procedure 1100 may be initiated when a sharing AP 1102 sends a first EHT NDP announcement frame 1110 to the sharing AP(s) participating in the sounding procedure 1100 and to target STAs, e.g., STA1 1106 and STA2 1108. The first EHT NDP announcement frame 1110 may indicate the sharing AP(s) participating in the sounding procedure 1100, e.g., sharing AP 1104. The first EHT NDP announcement frame 1110 may also indicate an STA ordering in which target STAs, e.g., STA1 1106-STA2 1108, may transmit EHT sounding NDPs to the sharing AP 1102 and all sharing APs participating in the sounding procedure 1100. Each EHT NDP announcement frame 1110, 1120 may indicate a sounding RU allocation and a sounding SS allocation for the corresponding STA. SIFS 1111 may be enabled upon transmission of the first EHT NDP announcement frame 1110. At 1112 during SIFS 1111, a STA or STAs other than the first STA in the STA ordering, for example, STA2 1108, may be switched from an awake state to a doze state for power saving, and at 1113 after the SIFS, the first STA in the STA ordering, for example, STA1 1106, may transmit a first EHT sounding NDP 1114 to the sharing AP 1102 and the sharing AP 1104. The sharing AP 1102 and the sharing AP 1104 may then determine the DL CSI for STA1 1106 by estimating the UL CSI from the received first EHT sounding NDP 1114 and compensating the UL CSI according to calibration parameters obtained from the calibration procedure.Furthermore, based on the DL CSI for STA1 1106, the sharer AP 1102 and the sharer AP 1104 may be able to determine steering matrices and / or allocate appropriate RUs to STA1 1106 for subsequent transmissions to STA1 1106.

[0089] After the last symbol of the first EHT sounding NDP 1114 is transmitted at 1115, STA1 1106 may switch from an awake state to a doze state to save power. SIFS 1116 may be enabled, and during SIFS 1116, the next STA in the STA ordering, e.g., STA2 1108, may switch from a doze state to an awake state at 1117, and after SIFS 1116, at 1118, the AP 1102 may transmit a second EHT NDP announcement frame 1120. Upon transmission of the second EHT NDP announcement frame 1120, SIFS 1121 may be enabled, and at 1122, STA2 1108 may transmit a second EHT sounding NDP 1124 to the sharing AP 1102 and the sharing AP 1104. The sharer AP 1102 and the sharer AP 1104 then determine the DL CSI for STA2 1108 by estimating the UL CSI from the received second EHT sounding NDP 1124 and compensating the UL CSI according to the calibration parameters obtained from the calibration procedure. Further, based on the DL CSI for STA2 1108, the sharer AP 1102 and the sharer AP 1104 may be able to determine a steering matrix and / or allocate an appropriate RU to STA2 1108 for subsequent transmissions to STA2 1108. Advantageously, the multi-AP-based implicit sequential sounding procedure shown in FIG. 11A may require less sounding overhead than the multi-AP-based explicit sounding procedure shown in FIG. 9 or 10 because sounding feedback information does not need to be transmitted.

[0090] 11B shows a flowchart illustrating a multi-AP-based implicit sequential sounding procedure 1130 between multiple APs 1132, 1134 and multiple STAs 1136, 1138 in an 11be EHT WLAN according to another embodiment (Option 2). Similarly, the multi-AP-based implicit sequential sounding procedure 1130 may be initiated when the AP 1132 sends an EHT NDP announcement frame 1140 to the shared AP(s) participating in the sounding procedure 1130 and to the target STAs, e.g., STA1 1136 and STA2 1138. The EHT NDP announcement frame 1140 indicates the shared AP(s) participating in the sounding procedure 1130, e.g., shared AP 1134. The EHT NDP announcement frame 1140 may indicate an STA ordering in which target STAs, such as STA1 1136-STA2 1138, may transmit EHT sounding NDPs to the AP 1132 and to the shared AP(s) participating in the sounding procedure 1130. The EHT NDP announcement frame 1140 may further indicate a sounding RU assignment and a sounding SS assignment for each STA. In this manner, the EHT-LTF field duration (equivalent to the transmission time of the EHT sounding NDP) of the EHT sounding NDP transmitted by each STA can be determined from the SS assignment for that STA. Based on the transmission time of each STA's EHT sounding NDP, the first EHT sounding NDP from the first STA in the STA ordering can be followed by the second EHT sounding NDP from the second STA in the STA ordering.

[0091] For example, upon transmission of the EHT NDP announcement frame 1140, a SIFS 1141 may be enabled, and at 1142 during the SIFS 1141, a STA other than the first STA in the STA ordering, e.g., STA2 1138, may switch from an awake state to a doze state for power saving, and at 1143 after the SIFS, the first STA in the STA ordering, e.g., STA1 1136, may transmit a first EHT sounding NDP 1144 to the sharing AP 1132 and the sharing AP 1134. The sharing AP 1132 and the sharing AP 1134 may then determine the DL CSI for STA1 1136 by estimating the UL CSI from the received first EHT sounding NDP 1144 and compensating the UL CSI according to calibration parameters obtained from a calibration procedure. At 1145, after transmitting the last symbol of the first EHT sounding NDP 1144, STA1 1136 may switch from an awake state to a doze state to save power. SIFS 1148 may be enabled, and during SIFS 1148, STA2 1138 may switch from the doze state back to the awake state at 1147. After SIFS 1146, STA2 1138 may transmit a second EHT sounding NDP 1150 to the sharing AP 1132 and the sharing AP 1134 at 1148. The sharing AP 1132 and the sharing AP 1134 may then determine the DL CSI for STA2 1138 by estimating the UL CSI from the received second EHT sounding NDP 1150 and compensating the UL CSI according to calibration parameters obtained from the calibration procedure. Further, based on the DL CSI for STA1 1136 and STA2 1138, the source AP 1132 and the destination AP 1134 may be able to determine steering matrices and / or assign appropriate RUs to each of STA1 1136 and STA2 1138 for subsequent transmissions to STA1 1136 and / or STA2 1138.Advantageously, the multi-AP based implicit sequential sounding option 2 shown in FIG. 11B further reduces the sounding overhead than the multi-AP based implicit sequential sounding option 1 shown in FIG. 11A.

[0092] 12 shows a flowchart illustrating a multi-AP-based implicit joint sounding procedure 1200 between multiple APs 1202, 1204 and multiple STAs 1206, 1208 in an 11be EHT WLAN, according to one embodiment. The multi-AP-based implicit joint sounding procedure 1200 may be initiated when the sharing AP 1202 transmits an EHT NDP announcement frame 1210 to the sharing AP(s) participating in the sounding procedure 1200, e.g., the sharing AP 1204, and to the target STAs, e.g., STA1 1206 and STA2 1208. The EHT NDP announcement frame 1210 may indicate the sharing AP(s) participating in the sounding procedure 1200 and may additionally indicate a sounding RU assignment and a sounding SS assignment for each STA. Upon transmitting the EHT NDP announcement frame 1210, SIFS 1211 may be enabled, and at 1212, STA1 1206 and STA2 1208 may transmit their respective EHT sounding NDPs 1214, 1216 to the sharing AP 1202 and the sharing AP 1204. The sharing AP 1202 and the sharing AP 1204 may then determine the DL CSI for STA1 1206 by estimating the first UL CSI from the received EHT sounding NDP 1214 and compensating the first UL CSI according to the calibration parameters obtained from the calibration procedure. Similarly, the sharing AP 1202 and the sharing AP 1204 may determine the DL CSI for STA2 1208 by estimating the second UL CSI from the received EHT sounding NDP 1216 and compensating the second UL CSI according to the calibration parameters obtained from the calibration procedure. Furthermore, based on the DL CSI for STA1 1206 and STA2 1208, the source AP 1202 and the destination AP 1204 may be able to determine steering matrices and / or allocate appropriate RUs to each of STA1 1206 and STA2 1208 for subsequent transmissions to STA1 1206 and / or STA2 1208.Advantageously, the multi-AP based implicit joint sounding shown in FIG. 12 may require less sounding overhead than the multi-AP based implicit sequential sounding shown in FIGS. 11A and 11B.

[0093] According to the present disclosure, the source AP and destination AP(s) engaged in the multi-AP-based hybrid sounding procedure are divided into two groups, with group 1 APs including the AP(s) participating in the explicit sounding portion of the multi-AP-based hybrid sounding procedure, and group 2 APs including the AP(s) participating in the implicit sounding portion of the multi-AP-based hybrid sounding procedure.

[0094] 13A shows a flowchart illustrating a multi-AP-based hybrid sequential sounding procedure 1300 between multiple sharing APs 1302, 1304, 1306 and a STA 1308 in an 11be EHT WLAN, according to an embodiment. In this embodiment, the sharing AP 1302 and sharing AP1 1304 are APs of Group 1, while sharing AP2 1306 is an AP of Group 2. The multi-AP-based hybrid sequential sounding procedure 1300 may begin when the sharing AP 1302 transmits a first EHT NDP announcement frame 1310 to all sharing AP(s) (e.g., sharing APs 1304, 1306) participating in the sounding procedure 1300 and to the target STA 1308. The first EHT NDP announcement frame 1310 may indicate the APs in Group 2 and the ordering of the APs in Group 1, and each of the APs in Group 1 may transmit an EHT NDP announcement frame and an EHT sounding NDP to the target STA in this ordering. The first EHT NDP announcement frame 1310 may indicate sounding RU assignments and sounding SS assignments for each of the APs in Group 1. Each EHT NDP announcement frame may indicate the sounding RU assignments and sounding SS assignments for the target STA 1308. Each EHT NDP announcement frame may indicate requested sounding feedback parameters for the target STA 1308, such as feedback bandwidth, feedback type, subcarrier grouping, quantization resolution, and the number of columns of the compressed beamforming feedback matrix. The feedback type is one of SU feedback, MU feedback, and CQI feedback. Upon transmission of the first EHT NDP announcement frame 1310, SIFS 1311 may be enabled, and at 1312, the sharing AP 1302 may transmit a first EHT sounding NDP 1314 to the STA 1308.After the last symbol of the first EHT sounding NDP 1314 is transmitted, SIFS 1315 may be enabled, and at 1316, the STA 1308 transmits a first EHT compressed beamforming / CQI frame 1318 containing sounding feedback information to the sharing AP 1302. Note that the EHT-LTF field of the EHT PPDU containing the first EHT compressed beamforming / CQI frame 1318 may also be used for CSI estimation for implicit sounding by the AP(s) in Group 2, such as sharer AP2 1306. Based on the sounding feedback information received from the STA 1308, the sharing AP 1302 may be able to determine a steering matrix and / or allocate an appropriate RU to the STA 1308 for subsequent transmissions to the STA 1308.

[0095] Upon transmission of the first EHT compressed-beamforming / CQI frame 1318, SIFS 1319 may be enabled, and at 1320, the next AP in the ordering of APs in group 1, e.g., sharer AP1 1304, may transmit a second EHT NDP announcement frame 1322 to the STA 1308. Upon transmission of the second EHT NDP announcement frame 1322, SIFS 1323 may be enabled, and at 1324, sharer AP1 1304 may transmit a second EHT sounding NDP 1326 to the STA 1308. Similarly, after the second EHT sounding NDP 1326 is transmitted, SIFS 1327 may be enabled, and at 1328, the STA 1308 may transmit a second EHT compressed-beamforming / CQI frame 1330 including sounding feedback information to sharer AP1 1304. Note that the EHT-LTF field of the EHT PPDU containing the second EHT compressed beamforming / CQI frame 1330 may also be used for implicit sounding by the AP(s) in Group 2, such as sharer AP2 1306. Based on the sounding feedback information received from the STA 1308, the sharer AP 1304 may be able to determine a steering matrix and / or allocate an appropriate RU to the STA 1308 for subsequent transmissions to the STA 1308. Furthermore, the shared AP2 1306 may be able to determine the DL CSI corresponding to the STA 1308 by estimating the UL CSI from the EHT-LTF field of the EHT PPDU including the first and second EHT compressed beamforming / CQI frames 1318, 1330 and compensating the UL CSI according to calibration parameters obtained from the calibration procedure, and the shared AP 1306 may then be able to determine a steering matrix and / or allocate an appropriate RU to the STA 1308 based on the DL CSI for subsequent transmissions to the STA 1308.

[0096] 13B shows a flowchart illustrating a multi-AP-based hybrid sequential sounding procedure 1340 between multiple sharing APs 1342, 1344, 1346 and multiple STAs 1348, 1350 in an 11be EHT WLAN, according to an embodiment. In this embodiment, the sharing AP 1342 and sharing AP1 1344 are APs of Group 1, while sharing AP2 1346 is an AP of Group 2. The multi-AP-based hybrid sequential sounding procedure 1340 may be initiated when the sharing AP 1342 transmits a first EHT NDP announcement frame 1352 to all sharing AP(s) (e.g., sharing APs 1344, 1346) and target STAs 1348, 1350 participating in the sounding procedure 1340. The first EHT NDP announcement frame 1352 may indicate the APs in Group 2 and the ordering of the APs in Group 1, and each AP in Group 1 may transmit an EHT NDP announcement frame and an EHT sounding NDP to the target STA in this ordering. The first EHT NDP announcement frame 1352 may indicate a sounding RU assignment and a sounding SS assignment for each AP in Group 1. Each EHT NDP announcement frame may indicate a sounding RU assignment and a sounding SS assignment for each of STA1 1348 and STA2 1350. In particular, the data RU assignment and the data SS assignment for each of STA1 1348 and STA2 1350 are indicated in the corresponding EHT BFRP trigger frame. The sounding SS may include a data SS. In other words, the number of sounding SSs may be equal to or greater than the number of data SSs. The data RU assignment may be the same as the sounding RU assignment for each STA. Each EHT NDP announcement frame may indicate the required sounding feedback parameters for each of the target STAs 1348, 1350, such as feedback bandwidth, feedback type, subcarrier grouping, quantization resolution, and number of columns of the compressed beamforming feedback matrix.The feedback type is one of SU feedback, MU feedback, and CQI feedback. Upon transmission of the first EHT NDP announcement frame 1352, SIFS 1353 may be enabled, and at 1354, the sharing AP 1342 may transmit a first EHT sounding NDP 1356 to STA1 1348 and STA2 1350. After the last symbol of the first EHT sounding NDP 1356 is transmitted, SIFS 1357 may be enabled, and at 1358, the sharing AP 1342 may transmit an EHT BFRP trigger frame 1360 to request simultaneous transmission of sounding feedback information from STA1 1348 and STA2 1350. Upon receiving the EHT BFRP trigger frame 1360, SIFS 1361 may be enabled, and at 1362, STA1 1348 and STA2 1350 simultaneously transmit their respective first EHT compressed beamforming / CQI frames 1364, 1366 containing sounding feedback information to the sharing AP 1342. Note that the EHT-LTF field of the EHT PPDU containing the first EHT compressed beamforming / CQI frames 1364, 1366 may also be used for CSI estimation for implicit sounding by the AP(s) in Group 2, e.g., sharing AP2 1346. Based on the sounding feedback information received from STA1 1348 and STA2 1350, the sharing AP 1342 may be able to determine a steering matrix and / or allocate appropriate RUs to each of STA1 1348 and STA2 1350 for subsequent transmissions to STA1 1348 and / or STA2 1350.

[0097] Upon transmission of the first EHT compressed beamforming / CQI frames 1364, 1366, SIFS 1367 may be enabled, and at 1368, the next AP in the ordering of APs in Group 1, e.g., sharer AP1 1344, may transmit a second EHT NDP announcement frame 1370 to STA1 1348 and STA2 1350. Upon transmission of the second EHT NDP announcement frame 1370, SIFS 1371 may be enabled, and at 1372, sharer AP1 1344 may transmit a second EHT sounding NDP 1374 to STA1 1348 and STA2 1350. Similarly, after the second EHT sounding NDP 1374 is transmitted, SIFS 1375 may be enabled, and at 1376, the sharing AP 1342 may transmit an EHT BFRP trigger frame 1378 to request simultaneous transmission of sounding feedback information from STA1 1348 and STA2 1350. Upon receipt of the EHT BFRP trigger frame 1378, SIFS 1379 may be enabled, and at 1380, STA1 1348 and STA2 1350 simultaneously transmit their respective second EHT compressed-beamformed / CQI frames 1382, 1384 containing sounding feedback information to the sharing AP 1344. Note that the EHT-LTF field of the EHT PPDU containing the second EHT compressed beamforming / CQI frame 1382, 1384 may also be used for CSI estimation for implicit sounding by the AP(s) in Group 2, such as, for example, Shared AP2 1346. Based on the sounding feedback information received from STA1 1348 and STA2 1350, Shared AP1 1344 may be able to determine steering matrices and / or allocate appropriate RUs to each of STA1 1348 and STA2 1350 for subsequent transmissions to STA1 1348 and / or STA2 1350.Furthermore, shared AP2 1346 may be able to determine DL CSI for STA1 1348 by estimating UL CSI from the EHT-LTF field of the EHT PPDU including the first and second EHT compressed beamforming / CQI frames 1364, 1382 and compensating the UL CSI according to calibration parameters obtained from the calibration procedure, and shared AP2 1346 may then be able to determine a steering matrix and / or allocate an appropriate RU to STA1 1348 based on the DL CSI for subsequent transmissions to STA1 1348. Similarly, shared AP2 1346 may be able to determine DL CSI for STA2 1350 by estimating the UL CSI from the EHT-LTF field of the EHT PPDU including the first and second EHT compressed beamforming / CQI frames 1366, 1384 and compensating the UL CSI according to calibration parameters obtained from the calibration procedure, and shared AP2 1346 may then be able to determine a steering matrix and / or allocate an appropriate RU to STA2 1350 based on the DL CSI for subsequent transmissions to STA2 1350.

[0098] 14A shows a flowchart illustrating a multi-AP-based hybrid joint sounding procedure 1400 between multiple sharing APs 1402, 1404, 1406 and a STA 1408 in an 11be EHT WLAN, according to one embodiment. In this embodiment, the sharing AP 1402 and sharing AP1 1404 are APs of Group 1, while sharing AP2 1406 is an AP of Group 2. The multi-AP-based hybrid sequential sounding procedure 1400 may be initiated when the sharing AP 1402 transmits an EHT NDP announcement frame 1410 to all sharing AP(s) (e.g., sharing APs 1404, 1406) participating in the sounding procedure 1400 and to the target STA 1408. The EHT NDP announcement frame 1410 may indicate the APs in Group 2 and the ordering of the APs in Group 1, where each AP in Group 1 may transmit an EHT sounding NDP to the target STA. The EHT NDP announcement frame 1410 may indicate sounding RU assignments and sounding SS assignments for each AP in Group 1. The EHT NDP announcement frame may indicate the sounding RU assignments and sounding SS assignments for the target STA 1408. The EHT NDP announcement frame may indicate requested sounding feedback parameters, such as feedback bandwidth, feedback type, subcarrier grouping, quantization resolution, and the number of columns of the compressed beamforming feedback matrix, for each pair of the target STA 1408 and the AP in Group 1. The feedback type is one of SU feedback, MU feedback, and CQI feedback. Upon transmission of the EHT NDP announcement frame 1410, SIFS 1411 may be enabled, and at 1412, the sharer AP 1402 and sharer AP 1404 may simultaneously transmit their respective EHT sounding NDPs 1414, 1416 to the STA 1408.After the last symbol of the EHT sounding NDPs 1414, 1416 is transmitted, the SIFS 1417 may be enabled, and at 1418, the STA 1408 transmits an EHT compressed beamforming / CQI frame 1419 containing sounding feedback information to the sharer AP 1402 and sharer AP1 1404. Note that the EHT-LTF field of the EHT PPDU containing the EHT compressed beamforming / CQI frame 1419 may also be used for CSI estimation for implicit sounding by the AP(s) in Group 2, such as sharer AP2 1406. Based on the sounding feedback information received from the STA 1408, the sharer AP 1402 and sharer AP1 1404 may be able to determine steering matrices and / or allocate appropriate RUs to the STA 1408 for subsequent transmissions to the STA 1408. Furthermore, shared AP2 1406 may be able to determine DL CSI for STA 1408 by estimating UL CSI from the EHT-LTF field of the EHT PPDU including the EHT compressed beamforming / CQI frame 1419 and compensating the UL CSI according to calibration parameters obtained from the calibration procedure, and shared AP2 1406 may then be able to determine a steering matrix and / or allocate an appropriate RU to STA 1408 based on the DL CSI for subsequent transmissions to STA 1408.

[0099] 14B shows a flowchart illustrating a multi-AP-based hybrid joint sounding procedure 1420 between multiple sharing APs 1422, 1424, 1426 and multiple STAs 1428, 1430 in an 11be EHT WLAN, according to an embodiment. In this embodiment, the sharing AP 1422 and sharing AP1 1424 are APs of Group 1, while sharing AP2 1426 is an AP of Group 2. The multi-AP-based hybrid joint sounding procedure 1420 may be initiated when the sharing AP 1422 transmits an EHT NDP announcement frame 1432 to all sharing AP(s) (e.g., sharing APs 1424, 1426) and target STAs 1428, 1430 participating in the sounding procedure 1420. The EHT NDP announcement frame 1432 may indicate the APs in Group 2 and the ordering of the APs in Group 1, where each AP in Group 1 may transmit an EHT sounding NDP to target STA1 1428 and STA2 1430. The EHT NDP announcement frame 1432 may indicate the sounding RU assignment and sounding SS assignment for each AP in Group 1. The EHT NDP announcement frame 1432 may indicate the sounding RU assignment and sounding SS assignment for each of STA1 1428 and STA2 1430. In particular, the data RU assignment and data SS assignment for each of STA1 1428 and STA2 1430 are indicated in the corresponding EHT BFRP trigger frame 1442. The sounding SS may include a data SS. In other words, the number of sounding SSs may be equal to or greater than the number of data SSs. The data RU assignment may be the same as the sounding RU assignment for each STA. The EHT NDP announcement frame 1432 may indicate the required sounding feedback parameters for each of the target STAs 1428, 1430, such as feedback bandwidth, feedback type, subcarrier grouping, quantization resolution, and number of columns of the compressed beamforming feedback matrix.The feedback type is one of SU feedback, MU feedback, and CQI feedback. Upon transmission of the EHT NDP announcement frame 1432, SIFS 1433 may be enabled, and at 1434, the sharer AP 1422 and the sharer AP1 1424 may transmit their respective EHT sounding NDPs 1436, 1438 to STA1 1428 and STA2 1430. After the last symbols of the EHT sounding NDPs 1436, 1438 are transmitted, SIFS 1439 may be enabled, and at 1440, the sharer AP 1422 may transmit an EHT BFRP trigger frame 1442 to request simultaneous transmission of sounding feedback information from STA1 1428 and STA2 1430. Upon receiving the EHT BFRP trigger frame 1442, SIFS 1443 may be enabled, and at 1444, STA1 1428 and STA2 1430 simultaneously transmit their respective EHT compressed beamforming / CQI frames 1446, 1448 containing sounding feedback information to the sharer AP 1422 and sharer AP1 1424. Note that the EHT-LTF field of the EHT PPDU containing the EHT compressed beamforming / CQI frames 1446, 1448 may also be used for CSI estimation for implicit sounding by the AP(s) in Group 2, e.g., sharer AP2 1426. Based on the sounding feedback information received from STA1 1428 and STA2 1430, the sharing AP 1422 and the sharing AP 1424 may be able to determine steering matrices and / or allocate appropriate RUs to each of STA1 1428 and STA2 1430 for subsequent transmissions to STA1 1428 and / or STA2 1430.Furthermore, shared AP2 1426 may be able to determine DL CSI for STA1 1428 by estimating the UL CSI from the EHT-LTF field of the EHT PPDU including the EHT compressed beamforming / CQI frame 1446 and compensating the UL CSI according to calibration parameters obtained from the calibration procedure, and shared AP2 1426 may then be able to determine a steering matrix and / or allocate an appropriate RU to STA1 1428 based on the DL CSI for subsequent transmissions to STA1 1428. Similarly, shared AP2 1426 may be able to determine DL CSI for STA 1430 by estimating UL CSI from the EHT-LTF field of the EHT PPDU including the EHT compressed beamforming / CQI frame 1448 and compensating the UL CSI according to calibration parameters obtained from the calibration procedure, and shared AP2 1426 may then be able to determine a steering matrix and / or allocate an appropriate RU to STA 1430 based on the DL CSI for subsequent transmissions to STA 1430.

[0100] 15 shows an example of the format of an EHT NDP announcement frame 1500. The EHT NDP announcement frame 1500 may include (or consist of) a Frame Control field, a Duration field, an RA (recipient STA address) field, a TA (transmitting STA address) field, a Sounding Dialogue Token field, a Sounding Type field 1502, an AP-STA Information field 1504, and an FCS field. The Frame Control field, Duration field, RA field, and TA field may be grouped as a MAC header.

[0101] When the sounding type field 1502 indicates single-AP-based explicit sounding, the AP-STA information field 1504 for single-AP-based explicit sounding may include one or more STA feedback information fields 1602 as shown in Figure 16A. The STA feedback information field 1602 may include (or consist of) a target STA field, a feedback bandwidth field, a feedback type field, a subcarrier grouping field, a quantization resolution field, and a number of columns of compressed beamforming feedback matrix field. In one embodiment, the STA feedback information field is used to indicate sounding feedback parameters requested for the STA indicated in the target STA field.

[0102] When the sounding type field 1502 indicates single-AP-based implicit sounding, the AP-STA information field 1504 for single-AP-based implicit sounding may include one or more STA sounding information fields 1604 as shown in Figure 16B. The STA sounding information field 1604 may include (or consist of) a target STA field, a STA sounding RU assignment field, and a STA sounding SS assignment field. In one embodiment, the STA sounding information field is used to indicate the sounding RU assignment and the sounding SS assignment for the STA indicated in the target STA field.

[0103] When the sounding type field 1502 indicates multi-AP-based explicit sounding, the AP-STA information field 1504 for multi-AP-based explicit sounding may include one or more AP-STA explicit sounding information fields 1606 as shown in FIG. 16C. The AP-STA explicit sounding information field 1606 may include (or consist of) an AP sounding information field 1608 and one or more STA feedback information fields 1602 as shown in FIG. 16A. The AP sounding information field 1608 may further include a target AP field, an AP sounding RU assignment field, and an AP sounding SS assignment field. In one embodiment, the AP-STA explicit sounding information field is used to indicate the sounding RU assignment and sounding SS assignment for the AP indicated in the target AP field and the corresponding sounding feedback parameters for each STA.

[0104] When the sounding type field 1502 indicates multi-AP-based implicit sounding, the AP-STA information field 1504 for the multi-AP-based implicit sounding may include one or more target AP fields and one or more STA sounding information fields 1604 as shown in Figure 16B. In one embodiment, the one or more target AP fields are used to indicate the shared AP(s) participating in the multi-AP-based implicit sounding, and the one or more STA sounding information fields are used to indicate the sounding RU assignment and sounding SS assignment for each target STA.

[0105] Furthermore, when the sounding type field 1502 indicates multi-AP-based hybrid sounding, the AP-STA information field 1504 may include one or more AP-STA explicit sounding information fields 1606 as shown in FIG. 16C indicating information required for the explicit sounding portion of the multi-AP-based hybrid sounding, one or more target AP fields indicating information required for the implicit sounding portion of the multi-AP-based hybrid sounding, and one or more STA sounding information fields 1604 as shown in FIG. 16B.

[0106] FIG. 17 illustrates a configuration of a communications device, such as an AP, according to the present disclosure. Similar to the schematic example of communications device 300 shown in FIG. 3A, communications device 1700 includes circuitry 1702, at least one wireless transmitter 1710, at least one wireless receiver 1712, and at least one antenna 1714 (for simplicity, only one antenna is shown in FIG. 17). Circuitry 1702 may include at least one controller 1708, which is used for software- and hardware-assisted execution of tasks designed to perform communications for channel sounding. Circuitry 1702 may further include a transmit signal generator 1704 and a receive signal processor 1706. At least one controller 1708 may control transmit signal generator 1704 and receive signal processor 1706. Transmit signal generator 1704 may include a frame generator 1722, a control signaling generator 1724, and a PPDU generator 1726. The frame generator 1722 may generate a MAC frame, such as an EHT NDP announcement frame, an EHT action frame, or an EHT BFRP trigger frame. The control signaling generator 1724 may generate a control signaling field of the PPDU to be generated (e.g., the EHT-SIG field of the EHT sounding NDP, or the EHT-SIG field of the EHT PPDU including the EHT NDP announcement frame, the EHT action frame, or the EHT BFRP trigger frame). The PPDU generator 1726 may generate a PPDU (e.g., the EHT sounding NDP, or the EHT PPDU including the EHT NDP announcement frame, the EHT action frame, or the EHT BFRP trigger frame).

[0107] The receive signal processor 1706 may include a data demodulator and decoder 1734, which may demodulate and decode the data portion of the received signal (e.g., the data field of an EHT PPDU containing an EHT NDP announcement frame, an EHT action frame, or an EHT BFRP trigger frame). The receive signal processor 1706 may further include a control demodulator and decoder 1734, which may demodulate and decode the control signaling portion of the received signal (e.g., the EHT-SIG field of an EHT sounding NDP or the EHT-SIG field of an EHT PPDU containing an EHT compressed beamforming / CQI frame). The at least one controller 1708 may include a control signal parser 1742 and a scheduler 1744. The scheduler 1744 may determine RU information and user-specific assignment information for assignment of downlink SU or MU transmissions and trigger information for assignment of uplink MU transmissions. The control signal parser 1742 may parse the control signaling portion of the received signal and the trigger information for allocation of uplink MU transmissions shared by the scheduler 1744 to assist the data demodulator and decoder 1732 in demodulating and decoding the data portion of the received signal (e.g., the data field of the EHT PPDU containing the EHT compressed beamforming / CQI frame).

[0108] FIG. 18 illustrates a configuration of a communications device, such as a STA, according to the present disclosure. Similar to the schematic example of communications apparatus 300 shown in FIG. 3A, communications apparatus 1800 includes circuitry 1802, at least one wireless transmitter 1810, at least one wireless receiver 1812, and at least one antenna 1814 (for simplicity, only one antenna is shown in FIG. 18). Circuitry 1802 may include at least one controller 1808, which is used for software- and hardware-assisted execution of tasks designed to perform communications for channel sounding. Circuitry 1802 may further include a receive signal processor 1806 and a transmit signal generator 1804. The at least one controller 1808 may control receive signal processor 1806 and transmit signal generator 1804. Receive signal processor 1806 may include a data demodulator and decoder 1832 and a control demodulator and decoder 1834. The control demodulator and decoder 1834 may demodulate and decode the control signaling portion of the received signal (e.g., the EHT-SIG field of the EHT sounding NDP, or the EHT-SIG field of the EHT PPDU containing the EHT NDP announcement frame or the EHT BFRP trigger frame). The data demodulator and decoder 1032 may demodulate and decode the data portion of the received signal (e.g., the data field of the EHT PPDU containing the EHT NDP announcement frame or the EHT BFRP trigger frame) according to the RU information and the user-specific allocation information of its allocation.

[0109] The at least one controller 1808 may include a control signal parser 1842, a scheduler 1844, and a trigger information parser 1846. The control signal parser 1842 may parse the control signaling portion of the received signal (e.g., the EHT-SIG field of the EHT sounding NDP or the EHT-SIG field of the EHT PPDU containing the EHT NDP announcement frame or the EHT BFRP trigger frame) to assist the data demodulator and decoder 1832 in demodulating and decoding the data portion of the received signal (e.g., the data field of the EHT PPDU containing the EHT NDP announcement frame or the EHT BFRP trigger frame). The trigger information parser 1848 may parse trigger information for its uplink allocation from the received trigger frame included in the data portion of the received signal. The transmit signal generator 1804 may include a control signaling generator 1824, which may generate a control signaling field of the PPDU to be generated (e.g., an EHT-SIG field of an EHT sounding NDP or an EHT-SIG field of an EHT PPDU including an EHT compressed beamforming / CQI frame). The transmit signal generator 1804 may further include a PPDU generator 1826, which generates a PPDU (e.g., an EHT sounding NDP or an EHT PPDU including an EHT compressed beamforming / CQI frame). The transmit signal generator 1804 may further include a frame generator 1822, which may generate a MAC frame, such as an EHT compressed beamforming / CQI frame.

[0110] As described above, embodiments of the present disclosure provide an advanced communication system, communication method, and communication device for channel sounding in a MIMO WLAN network to improve spectral efficiency in the MIMO WLAN network.

[0111] The present disclosure may be realized by software, hardware, or software cooperating with hardware. Each functional block used in the description of each embodiment above may be partially or entirely realized by an LSI, such as an integrated circuit, and each process described in each embodiment may be partially or entirely controlled by the same LSI or a combination of LSIs. The LSI may be formed as an individual chip, or a single chip may be formed to include some or all of the functional blocks. The LSI may include a data input and an output coupled to the data input. In this specification, the LSI may be referred to as an IC, a system LSI, a super LSI, or an ultra LSI depending on the degree of integration. However, the technology for realizing an integrated circuit is not limited to an LSI, and may be realized using a dedicated circuit, a general-purpose processor, or a special-purpose processor. In addition, 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 circuit cells arranged inside the LSI, may be used. The present disclosure may be realized as digital processing or analog processing. In future integrated circuit technologies, when LSIs become obsolete as a result of advances in semiconductor technology or other derivative technologies, functional blocks may be integrated using future integrated circuit technologies. Biotechnology may also be applied.

[0112] The present disclosure may be implemented by any type of apparatus, device, or system capable of communication, referred to as a communications apparatus.

[0113] The communication device may include a transceiver and processing / control circuitry. The transceiver may include and / or function as a receiver and a transmitter. As a transmitter and a receiver, the transceiver may include an RF (radio frequency) module including an amplifier and an RF modulator / demodulator, etc., and one or more antennas.

[0114] 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, telemedicine / telehealth (remote medical care and treatment) devices, and vehicles (e.g., automobiles, aircraft, ships) that provide communication capabilities, and various combinations thereof.

[0115] Communication 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 "thing" in an "Internet of Things" (IoT) network.

[0116] Communications may include, for example, exchanging data over cellular systems, wireless LAN systems, satellite systems, the like, and various combinations thereof.

[0117] A communications apparatus may include a device, such as a controller or a sensor, coupled to a communications device that performs 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.

[0118] Additionally, communications equipment may include infrastructure facilities such as base stations, access points, and any other equipment, devices, or systems that communicate with or control equipment such as those in the above non-limiting examples.

[0119] Although some 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.

[0120] Those skilled in the art will recognize that numerous changes and / or modifications may be made to the present disclosure as set forth in the specific embodiments without departing from the spirit or scope of the disclosure as broadly described, and the present embodiments are therefore to be considered in all respects as illustrative and not restrictive.

Claims

1. a receiver for receiving a first frame from another communication device, the first frame including a first field indicating a target use of the sounding procedure; a circuit for processing the first frame; A communication device comprising:

2. the first frame includes a second field indicating a target type of the sounding procedure; The communication device according to claim 1 .

3. the first frame includes a third field indicating one or more target communication devices that will be engaged in the sounding procedure; The communication device according to claim 1 .

4. a transmitter for transmitting a second frame including a first field indicating one or more recommended types of the sounding procedure; The communication device according to claim 1 .

5. the first field of the second frame indicating that the communication device should be excluded from the sounding procedure; The communication device according to claim 4.

6. the receiver further receives a third frame that initiates the sounding procedure. The communication device according to claim 1 .

7. the third frame includes a first field indicating a type of the sounding procedure; a second field indicating a type of sounding feedback; The communication device according to claim 6.

8. When the type of the sounding procedure indicates an explicit sounding procedure and the type of the sounding feedback indicates a calibration feedback, the sounding procedure includes a calibration procedure. The communication device according to claim 7.

9. the other communication device transmits the first frame to one or more communication devices including the communication device, and when the sounding procedure is a hybrid sounding procedure including an explicit sounding portion and an implicit sounding portion, at least one communication device among the one or more communication devices and the other communication devices is configured to engage in the explicit sounding portion of the sounding procedure, and the remaining communication devices among the one or more communication devices and the other communication devices other than the at least one communication device are configured to engage in the implicit sounding portion of the sounding procedure. The communication device according to claim 1 .

10. the third frame is a Null Data Packet (NDP) announcement frame; The communication device according to claim 6.

11. receiving a first frame from another communication device, the first frame including a first field indicating a target use of the sounding procedure; processing the first frame; Communication method.

12. receiving a first frame from another communication device, the first frame including a first field indicating a target use of the sounding procedure; processing the first frame; and controlling the processing. Integrated circuit.

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