Communication device and communication method for channel sounding

Abstract

This invention provides an apparatus and method for establishing preparation procedures for efficiently and reliably initiating channel sounding in a multi-AP environment. [Solution] This disclosure relates to a communication device and communication method for channel sounding in the context of an EHT WLAN, wherein the communication device comprises a circuit that generates a first frame indicating the target application of a sounding procedure; a transmitter that transmits the first frame to a second communication device; and a receiver that receives a second frame from the second communication device in response to the first frame, wherein the transmitter transmits a third frame relating to a Null Data Packet (NDP) announcement.

Description

Technical Field

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

Background Art

[0002] In the standardization of next-generation wireless local area networks (WLANs), the IEEE 802.11 Working Group has considered a new wireless access technology that necessarily has backward compatibility with IEEE 802.11a / b / g / n / ac / ax technologies, and named it IEEE 802.11be extremely high throughput (EHT) WLAN.

[0003] In 802.11be EHT WLAN, in order to provide a significant increase in peak throughput and capacity beyond 802.11ax high efficiency (HE) WLAN, especially for cell-edge STAs, it has been proposed to enable multi-AP coordination in a multi-access point (multi-AP) system.

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

[0005] Therefore, there is a need for communication apparatus and methods that provide a feasible technical solution for channel sounding in EHT WLAN situations. Furthermore, other desirable features and characteristics will become apparent by obtaining the following detailed description and the attached claims together with the attached drawings and the background art of this disclosure. [Overview of the project] [Means for solving the problem]

[0006] Non-limiting and exemplary embodiments facilitate the provision of communication devices and communication methods for channel sounding in EHT WLAN settings.

[0007] In a first embodiment, the Disclosure provides a communication device including a receiver that receives a first frame from another communication device, which includes a first field indicating an intended use for a sounding procedure, and a circuit that processes the first frame.

[0008] In a second embodiment, the Disclosure provides a communication method for receiving a first frame from another communication device, which includes a first field indicating an intended use for a sounding procedure, and for processing the first frame.

[0009] In a third embodiment, the Disclosure provides an integrated circuit for receiving a first frame from another communication device, which includes a first field indicating an intended use for a sounding procedure, and for controlling a process for processing the first frame.

[0010] It should be noted that general or specific embodiments may be implemented as systems, methods, integrated circuits, computer programs, storage media, or any selective combination thereof.

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

[0012] Embodiments of the present disclosure will be well understood and readily apparent to those skilled in the art from the following description and drawings, which are merely illustrative examples. [Brief explanation of the drawing]

[0013] [Figure 1A] This is a schematic diagram illustrating single-user (SU) MIMO communication between an access point (AP) and a station (STA) in a multiple input multiple output (MIMO) wireless network, covering both uplink and downlink. [Figure 1B] This is a schematic diagram illustrating downlink multi-user (MU) communication between an access point (AP) and multiple service stations (STAs) in a MIMO wireless network. [Figure 1C] This is a schematic diagram illustrating trigger-based uplink MU communication between an AP and multiple STAs in a MIMO wireless network. [Figure 1D] This is a schematic diagram illustrating trigger-based downlink multi-AP communication between multiple APs and STAs in a MIMO wireless network. [Figure 2A] This diagram shows a single AP-based sounding procedure between two STAs in an 11ax HE WLAN. [Figure 2B] This diagram shows a single AP-based sounding procedure between an AP and multiple STAs in an 11ax HE WLAN. [Figure 3A]This figure shows schematic examples of communication devices according to various embodiments. These communication devices may be implemented as APs or STAs and may be configured for channel sounding according to the present disclosure. [Figure 3B] This flowchart illustrates the communication method described herein. [Figure 4] This is a flowchart showing the sounding setup procedure according to one embodiment. [Figure 5A] This figure shows an example of the EHT action frame format. [Figure 5B] This figure shows an example of the format of the Sounding Setup Element Field in the EHT Action Frame. [Figure 5C] This figure shows another example of the format of the Sounding Setup Element Field in the EHT Action Frame. [Figure 6A] This is a flowchart illustrating a single AP-based explicit sounding procedure between two STAs in an 11be EHT WLAN according to one embodiment. [Figure 6B] This flowchart shows a single AP-based explicit sounding procedure between an AP and multiple STAs in an 11be EHT WLAN according to another embodiment. [Figure 7A] This is a flowchart illustrating a single AP-based implicit sequential sounding procedure according to one embodiment. [Figure 7B] A flowchart illustrating a single AP-based implicit sequential sounding procedure according to another embodiment is shown below. [Figure 8] A flowchart illustrating a single AP-based implicit joint sounding procedure according to one embodiment is shown below. [Figure 9] This flowchart shows a multi-AP-based explicit sequential sounding procedure according to one embodiment. [Figure 10]A flowchart showing a multi-AP-based explicit joint sounding procedure according to an embodiment. [Figure 11A] A flowchart showing a multi-AP-based implicit sequential sounding procedure according to an embodiment. [Figure 11B] A flowchart showing a multi-AP-based implicit sequential sounding procedure according to another embodiment. [Figure 12] A flowchart showing a multi-AP-based implicit joint sounding procedure according to an embodiment. [Figure 13A] A flowchart showing a multi-AP-based hybrid sequential sounding procedure according to an embodiment. [Figure 13B] A flowchart showing a multi-AP-based hybrid sequential sounding procedure according to another embodiment. [Figure 14A] A flowchart showing a multi-AP-based hybrid joint sounding procedure according to an embodiment. [Figure 14B] A flowchart showing a multi-AP-based hybrid joint sounding procedure according to another embodiment. [Figure 15] A diagram showing an example of the format of an EHT null data packet (NDP: Null Data Packet) announcement frame. [Figure 16A] A diagram showing an example of the format of the STA feedback information field when the sounding type field indicates single-AP-based explicit sounding. [Figure 16B] A diagram showing an example of the format of the STA sounding information field when the sounding type field indicates single-AP-based implicit sounding. [Figure 16C] A diagram showing 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] This figure shows the configuration of a communication device, such as an AP, according to this disclosure. [Figure 18] This figure shows the configuration of a communication device, such as an STA, according to this disclosure. [Modes for carrying out the invention]

[0014] Those skilled in the art will recognize that components in drawings are shown for brevity and clarity and are not necessarily shown to scale. For example, to aid in the accurate understanding of this embodiment, the dimensions of some components in drawings, block diagrams, or flowcharts may be exaggerated relative to other components.

[0015] Some embodiments of this disclosure will be described merely as examples with reference to the drawings. Similar reference numerals and letters in the drawings indicate similar components or equivalents.

[0016] In the following paragraphs, specific exemplary embodiments will be described with particular reference to access points (APs) and stations (STAs) for uplink or downlink channel sounding in multiple-input multiple-output (MIMO) wireless networks.

[0017] In the context of IEEE 802.11 (Wi-Fi) technology, a station, also known as an STA, is a communication device capable of using the 802.11 protocol. Based on the IEEE 802.11-2016 definition, an STA can be any device that includes IEEE 802.11-compliant media access control (MAC) and physical layer (PHY) interfaces for a wireless medium (WM).

[0018] For example, an 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. An STA may be stationary or mobile. In a WLAN environment, the terms "STA," "wireless client," "user," "user device," and "node" are often used interchangeably.

[0019] Similarly, in the context of IEEE 802.11 (Wi-Fi) technology, an AP, sometimes called a wireless access point (WAP), is a communication device that enables STAs within a WLAN to connect to a wired network. Typically, an AP connects to a router (via a wired network) as a standalone device, but it is also possible for an AP to be integrated with a router or used within a router.

[0020] As mentioned above, an STA in a WLAN may function as an AP if different conditions exist, and vice versa. This is because communication devices 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 the 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 radio channel. In this context, "multiple inputs" refers to multiple transmitter antennas that input radio signals to the channel, and "multiple outputs" refers to multiple receiver antennas that receive radio signals from the channel and input them to the receivers. 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, the number of transmitter antennas and receiver antennas will not be further discussed in this disclosure.

[0022] In MIMO wireless networks, single-user (SU) and multi-user (MU) communications can be deployed for communication between communication devices such as APs and STAs. MIMO wireless networks benefit from enabling higher data rates and robustness by using multiple spatial streams, including spatial multiplexing and spatial diversity. Depending on the embodiment, the term “spatial stream” may be used interchangeably with the term “space-time stream” (or STS).

[0023] Figure 1A shows a schematic diagram of SU communication 100 between AP102 and STA104 in a MIMO wireless network. As shown, the MIMO wireless network may include one or more STAs (e.g., STA104, STA106, etc.). When SU ​​communication 100 on a channel is performed over the entire channel bandwidth, it is called full-bandwidth SU communication. When SU ​​communication 100 on a channel is performed over a portion of the channel bandwidth (e.g., one or more 20MHz subchannels in the channel are punctured), it is called punctured SU communication. In SU communication 100, AP102 transmits multiple space-time streams using multiple antennas (e.g., the four antennas shown in Figure 1A), and all space-time streams are directed to a single communication device, namely STA104. For simplicity, the multiple space-time streams directed to STA104 are shown as grouped data transmission arrows 108 directed to STA104.

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

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

[0026] Figure 1B shows a schematic diagram of downlink MU communication 112 between AP114 and multiple STA116, 118, 120 in a MIMO wireless network. The MIMO wireless network may include one or more STAs (e.g., STA116, STA118, STA120, etc.). MU communication 112 can be OFDMA (orthogonal frequency division multiple access) communication or MU-MIMO communication. For OFDMA communication on a channel, AP114 simultaneously transmits multiple streams to STA116, 118, 120 in the network using different resource units (RUs) within the channel bandwidth. For MU-MIMO communication on a channel, AP114 simultaneously transmits multiple streams to STA116, 118, 120 using the same RU(s) within the channel bandwidth via spatial mapping or precoding techniques using multiple antennas. When the RU(s) in which OFDMA or MU-MIMO communication occurs occupy the entire channel bandwidth, the OFDMA or MU-MIMO communication is called 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 20MHz subchannels within a channel are punctured), the OFDMA or MU-MIMO communication is called punctured OFDMA or MU-MIMO communication. For example, two space-time streams may be directed to STA118, another space-time stream may be directed to STA116, and yet another space-time stream may be directed to STA120. For brevity, the two space-time streams directed to STA118 are shown as a grouped data transmission arrow 124, the space-time stream directed to STA116 is shown as a data transmission arrow 122, and the space-time stream directed to STA120 is shown as a data transmission arrow 126.

[0027] To enable uplink MU transmission, trigger-based communication is provided to the MIMO wireless network. In this regard, Figure 1C shows a schematic diagram of trigger-based uplink MU communication 128 between AP130 and several STA132, 134, 136 in the MIMO wireless network.

[0028] Since multiple STA132, 134, and 136 devices are participating in trigger-based uplink MU communication, AP130 needs to coordinate the simultaneous transmission of multiple STA132, 134, and 136 devices.

[0029] To perform this adjustment, as shown in Figure 1C, AP130 simultaneously sends trigger frames 139, 141, and 143 to STA132, 134, and 136, indicating user-specific resource allocation information available to each STA (e.g., the number of space-time streams, the number of departure STSs, and the allocated RUs). In response to the trigger frames, STA132, 134, and 136 may then simultaneously send their respective space-time streams to AP130 according to the user-specific resource allocation information shown in trigger frames 139, 141, and 143. For example, two space-time streams may be directed from STA134 to AP130, another space-time stream from STA132 to AP130, and yet another space-time stream from STA136 to AP130. For simplicity, the two spatial-time streams from STA134 to AP130 are shown as a grouped data transmission arrow 140, the spatial-time stream from STA132 to AP130 is shown as data transmission arrow 138, and the spatial-time stream from STA136 to AP130 is shown as data transmission arrow 142.

[0030] To enable downlink multi-AP communication, trigger-based communication is provided to the MIMO wireless network. In this regard, Figure 1D shows a schematic diagram of downlink multi-AP communication 144 between STA150 and multiple APs 146, 148 in a MIMO wireless network.

[0031] Because multiple AP146 and AP148 devices participate in this trigger-based downlink multi-AP MIMO communication, the master AP146 needs to coordinate the simultaneous transmission of multiple AP146 and AP148 devices.

[0032] To perform this adjustment, as shown in Figure 1D, the master AP 146 simultaneously sends trigger frames 147 and 153 to AP 148 and STA 150, indicating AP-specific resource allocation information available to each AP (e.g., the number of space-time streams, the number of departure STS streams, and the allocated RUs). In response to the trigger frames, several APs 146 and 148 may then send their respective space-time streams to STA 150 according to the AP-specific resource allocation information shown in trigger frame 147. STA 150 may then receive all space-time streams according to the AP-specific resource allocation information shown in trigger frame 153. For example, two space-time streams may be directed from AP 146 to STA 150, or two other space-time streams may be directed from AP 148 to STA 150. For simplicity, the two spatial-temporal streams directed from AP146 to STA150 are shown as a grouped data transmission arrow 152, and the two spatial-temporal streams directed from AP148 to STA150 are shown as a 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 WLANs, there is no time scheduling (e.g., periodic time slot allocation for data transmission similar to TDMA (Time Division Multiple Access)). Frequency and spatial resource scheduling is performed 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, the communication device spontaneously transmits the PPDU to one or more other communication devices. In trigger-based communication, the communication device transmits the PPDU to one or more other communication devices only after receiving a soliciting trigger frame.

[0035] Figure 2A shows a single AP-based sounding procedure 200 between two STAs 202 and 204 in an 11ax HE WLAN. The single AP-based sounding procedure 200 may be initiated when STA1 202, such as AP, generates an HE NDP (Null Data Packet) announcement frame 206 for a target STA, such as STA2 204. The HE NDP announcement frame 206 includes the requested sounding feedback parameters for each STA, such as feedback bandwidth, feedback type, subcarrier grouping, quantization resolution, and the number of columns in the 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 per subcarrier or subcarrier group. When the feedback type is CQI feedback, the requested sounding feedback information includes CQI information per subcarrier or subcarrier group. In an IEEE 802.11 network, short interframe spacing (SIFS) refers to the time interval before the acknowledgment is sent by the STA. When the HE NDP announcement frame 206 is sent, SIFS 207 may be enabled, and in 208, STA1 202 may send HE sounding NDP 210 to STA2 204. HE sounding NDP 210 may include 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 in 212, STA2 204 may transmit an HE compressed beamforming / CQI frame 214 containing sounding feedback information to STA1 202. In one embodiment, the sounding feedback information may be derived by STA2 204 from the CSI, estimated from the HE-LTF field of the HE sounding NDP 210, and prepared according to its own requested sounding feedback parameters as shown in the HE NDP announcement frame 206. Based on the sounding feedback information received from STA2 204, STA1 202 may determine the steering matrix and / or allocate appropriate resource units (RUs) for subsequent transmissions to STA2 204.

[0037] Figure 2B shows a single AP-based sounding procedure 220 between AP222 and several STA224, 226 in an 11ax HE WLAN. The single AP-based sounding procedure 220 may be initiated when AP222 generates an HE NDP announcement frame 228 for target STAs, such as STA1 224 and STA2 226. The HE NDP announcement frame 228 includes the requested sounding feedback parameters for each STA, such as feedback bandwidth, feedback type, subcarrier grouping, quantization resolution, and number of columns in 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 per 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 transmitting the HE NDP announcement frame 228, SIFS229 may be enabled, and in 230, AP222 may transmit the HE sounding NDP232 to STA1 224 and STA2 226.

[0038] After the HE sounding NDP232 is transmitted, SIFS233 may be enabled, and in 234, AP222 may transmit a beamforming report pole (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, the SIFS 237 may be enabled, and in 238, STA1 224 and STA2 226 may simultaneously transmit their respective HE Compression Beamforming / CQI frames 240, 242 containing their respective sounding feedback information to AP222. In one embodiment, the sounding feedback information may be derived by STA1 224 and STA2 226 from their respective CSIs, estimated from the HE-LTF field of the HE Sounding NDP 232, and prepared according to their respective sounding feedback parameters shown in the HE NDP announcement frame 228. Based on the sounding feedback information received from STA1 224 and STA2 226, AP222 may determine a steering matrix and / or assign appropriate RUs to each of STA1 224 and STA2 226 for subsequent transmissions to STA1 224 and / or STA2 226.

[0040] In 11ax HE WLAN, APs and STAs (one or more) engaged in a single AP-based sounding procedure belong to a single BSS (basic service set). Therefore, in order to improve throughput in 11be EHT WLAN compared to 11ax HE WLAN, the object of this disclosure is to substantially overcome existing challenges in providing communication equipment and methods for channel sounding that enable multi-AP coordination in a multi-AP system.

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

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

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

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

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

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

[0047] The communication device 300 may be a peer AP (e.g., a shared AP), and the radio receiver 304 may, while operating, receive a first frame (e.g., a sounding setup request frame) from one other communication device (e.g., a sharing AP) that includes a first field indicating the intended use of the sounding procedure. The circuit 314 (e.g., at least one receive signal processor 310 of the circuit 314) may, while operating, process the first frame. In one embodiment, the radio transmitter 302 may, while operating, transmit a second frame (e.g., a sounding setup response frame) to one of its other communication devices, the second frame which includes a first field indicating one or more recommended types of sounding procedures.

[0048] Figure 3B shows a flowchart illustrating the communication method according to the present disclosure. In step 318, a step is performed to generate a first frame for a sounding procedure. In step 320, a step is performed to transmit the first frame to each of one or more peer communication devices, the first frame including a first field indicating the intended use of the sounding procedure.

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

[0050] Figure 4 shows a flowchart illustrating the sounding setup procedure 400 between two APs, specifically between source AP 402 and destination AP 404, according to this disclosure. Contention-based channel access procedures, such as the enhanced distributed channel access (EDCA) procedure, are shown in blocks 405 and 413, in addition to SIFS 409 and 417. The sounding setup procedure includes sounding setup request and response frames exchanged between the source AP and each destination AP(s) of the multi-AP coordination candidate set. The sounding setup request or response frame is an EHT action frame. In particular, source AP 402 may generate a first frame 408, such as an EHT action frame (hereinafter referred to as the "sounding setup request frame") containing a sounding setup request, for example, to initiate the sounding setup procedure 400. The radio transmitter of source AP 402 may send the sounding setup request frame 408 to destination AP 404.

[0051] When the sounding setup request frame 408 is received, SIFS 409 may be enabled, and in 410, the shared AP 404 may send an acknowledgment (Ack) frame 412 to the shared AP 402 to indicate that the sounding setup request frame 408 was successfully received.

[0052] After the last symbol of Ack frame 412 is sent, the sharing AP 404 may generate a second frame 416, which may be, for example, an EHT action frame (hereinafter referred to as the "sounding setup request frame") containing a sounding setup response indicating whether the sharing AP 404 is ready for the subsequent sounding procedure in response to the sounding setup request frame 408.

[0053] When the sounding setup response frame 416 is received, SIFS 417 may be enabled, and in 418, the source AP 402 may send an Ack frame 420 to the destination AP 404 to indicate that the sounding setup response frame 416 has been successfully received.

[0054] Figure 5A shows an example of the format of an EHT action frame 500 that can be used as a sounding setup request frame 408 or a sounding setup response frame 416 as shown in Figure 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, an HT (high throughput) control field, a frame body field 502, and an FCS (frame check sequence) 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] Figure 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,” which indicates 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, the Action Type Field 506, and the 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 Application 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, which includes a source AP and at least one destination AP. The Target STA Field 514 indicates one or more STAs that belong to the BSS of the source AP and / or the BSS of at least one destination AP and are expected to engage in the subsequent sounding procedure. In 11be EHT WLAN, APs (one or more) and STAs (one or more) engaged in single-AP or multi-AP-based sounding procedures may belong to different BSSs. In 11be EHT WLAN, an STA may be identified by the BSSID (BSS identifier) ​​of the AP to which it is associated and its own STA ID. Alternatively, an STA may be identified by the AP ID of the AP to which it is associated, the AP set ID of the multi-AP coordination candidate set containing that AP, and the STA ID of that STA. Further details of the target sounding application field 510 and the target sounding type field 512 are described below.

[0056] Figure 5C shows another example of the format of the Sounding Setup Element Field 504 for the EHT Action Frame 500 when the Action Type Field 506 indicates “Response,” indicating a Sound 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, the Action Type Field 506, and the 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 described below.

[0057] The sharing source AP402 may determine the target sounding parameters, such as the target sounding application and target sounding type, based on capability negotiations between APs in the multi-AP adjustment candidate set that take place before the sounding setup procedure.

[0058] The target sounding application field 510 indicates the target application of the sounding procedure following the sounding setup procedure (i.e., the target scheme for multi-AP adjustment that uses the results of the sounding procedure). The target scheme for multi-AP adjustment is one of the following: • Adjusted space reuse • Adjusted orthogonal frequency division multiplexing (OFDMA) • Adjusted beamforming, and • Joint beam formation (also known as joint transmission).

[0059] The target sounding type field 512 indicates the target type of the sounding procedure that follows the sounding setup procedure, and it is one of the following: • Explicit sounding based on a single AP, • Implicit sequential sounding based on a single AP, • Implicit joint sounding based on a single AP, • Explicit sequential sounding based on multi-AP, • Explicit joint sounding based on multi-AP, • 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] Furthermore, in the sounding setup response frame 416, the recommended sounding type field 514 indicates one or more recommended types of sounding procedures following the sounding setup procedure, which are one of the following: • Explicit sounding based on a single AP, • Implicit sequential sounding based on a single AP, • Implicit joint sounding based on a single AP, • Explicit sequential sounding based on multi-AP, • Explicit joint sounding based on multi-AP, • Multi-AP based implicit sequential sounding • Multi-AP based implicit joint sounding, and • Exemption from multi-AP-based sounding is required.

[0061] Furthermore, when the shared AP404 makes an arbitrary recommendation for a sounding type in the recommended sounding type field 514, the shared AP404 should consider the target scheme for multi-AP adjustment. For example, the results of multi-AP based sequential sounding cannot be used for joint beamforming. For another example, the results of single-AP based sounding can be used for adjusted space reuse and adjusted OFDMA, but not for adjusted beamforming and joint beamforming.

[0062] After receiving a sounding setup request frame 408 from the sharing AP402, the sharing AP404 may determine whether it needs to reconfigure its transmit and receive (TX / RX) chain for the subsequent sounding procedure, based on the information about the target STA(s) indicated in the sounding setup request frame 408.

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

[0064] According to another embodiment of the present disclosure, if the shared AP404 supports single-AP-based implicit sounding or multi-AP-based implicit sounding, and its own TX / RX chain is being reconfigured for a subsequent sounding procedure, the shared AP404 may initiate a calibration procedure to recalibrate its own TX / RX chain before sending a sounding setup response frame 416 to the shared AP402. However, if the calibration procedure does not complete successfully, the shared AP404 does not have to recommend any single-AP-based or multi-AP-based implicit sounding procedure.

[0065] The sounding procedure may be initiated after the sounding setup procedure is completed between the source AP and each of the destination APs (one or more) in the multi-AP coordination candidate set. The sounding procedure may be initiated by sending an EHT NDP announcement frame indicating one of the following types of sounding procedure: • Explicit sounding based on a single AP, • Implicit sequential sounding based on a single AP, • Implicit joint sounding based on a single AP, • Explicit sequential sounding based on multi-APs, • Explicit joint sounding based on multi-AP, • 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] The EHT NDP announcement frame that initiates the multi-AP-based sounding procedure may be sent by the sharing AP.

[0067] Figure 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 one embodiment. The single AP-based explicit sounding procedure 600 may be initiated when, for example, AP STA1 602 transmits an EHT NDP announcement frame 606 to a target STA, such as STA2 604. The EHT NDP announcement frame 606 includes the requested sounding feedback parameters for each STA, such as the feedback bandwidth, feedback type, subcarrier grouping, quantization resolution, and number of columns in 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 per 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 for each subcarrier or subcarrier group. Upon receiving the EHT NDP announcement frame 606, SIFS 607 may be enabled, and in 608, STA1 602 may transmit EHT sounding NDP 610 to STA2 604. 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 in 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 the CSI, estimated from the EHT-LTF field of the EHT sounding NDP 610, and prepared according to its own sounding feedback parameters shown in the EHT NDP announcement frame 606. Based on the sounding feedback information received from STA2 604, STA1 602 may determine the steering matrix and / or assign appropriate RUs for subsequent transmissions to STA2 604.

[0069] Figure 6B shows a flowchart illustrating a single-AP-based explicit sounding procedure 620 between AP622 and several STA624, 626 in an 11be EHT WLAN according to another embodiment. The single-AP-based explicit sounding procedure 620 may be initiated when AP622 transmits an EHT NDP announcement frame 628 to the target STA, such as STA1 624 and STA2 626. Similarly, the EHT NDP announcement frame 628 may include the requested sounding feedback parameters for each STA, such as the feedback bandwidth, feedback type, subcarrier grouping, quantization resolution, and number of columns in 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 per 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. SIFS629 may be enabled when transmitting the EHT NDP announcement frame 628, and in 630, AP622 may transmit the EHT sounding NDP632 to STA1 624 and STA2 626.

[0070] After the EHT sounding NDP 632 is transmitted, SIFS 633 may be enabled, and in 634, 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 in 638, STA1 624 and STA2 626 may simultaneously transmit to AP 622 their respective EHT compression beamforming / CQI frames 640, 642 containing sounding feedback information. In one embodiment, the sounding feedback information may be derived by STA1 624 and STA2 626 from their respective CSIs, estimated from the EHT-LTF field of the EHT sounding NDP 632, and prepared according to the respective sounding feedback parameters shown in the EHT NDP announcement frame 628. Based on the sounding feedback information received from STA1 624 and STA2 626, AP622 can determine the steering matrix and / or assign appropriate RUs to each of STA1 624 and STA2 626 for subsequent transmissions to STA1 624 and / or STA2 626.

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

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

[0073] In various embodiments, when steps 600, 620 are single AP-based calibration steps, 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, such as STA2 604, STA1 624, STA2 626, transmits multiple SSs on the EHT-LTF field of the EHT PPDU containing the EHT compressed beamforming / CQI frames 614, 640, 642, and this EHT-LTF field is used for UL CSI estimation for data demodulation and calibration. In this way, APs 602, 622 may determine calibration coefficients for each of their TX antennas according to the DL compressed CSI information contained in the EHT compressed beamforming / CQI frames 614, 640, 642 and the UL CSI estimation.

[0074] Figure 7A shows a flowchart illustrating a single-AP-based implicit sequential sounding procedure 700 between AP702 and multiple STA704, 706 in an 11be EHT WLAN according to one embodiment (Option 1). The single-AP-based implicit sequential sounding procedure 700 may be initiated when AP702 sends 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 STA ordering, and target STAs such as STA1 704 to STA2 706 may send EHT sounding NDPs to AP702 in this STA ordering. In addition, the first EHT NDP announcement frame 708 may indicate sounding RU assignments and sounding SS assignments to the first STA in the STA ordering. After receiving the EHT NDP announcement frame 708, any STA(s) other than the first STA in the STA ordering, e.g., STA2 706, may be switched from the awake state to the dose state for power saving. In 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 own sounding RU assignment and sounding SS assignment and transmit it to AP 702. AP 702 may then estimate a first UL CSI from the received first EHT sounding NDP 712 and determine the DL CSI corresponding to STA1 704 by compensating the first UL CSI according to calibration parameters obtained from the calibration procedure.

[0075] At 713, after the last symbol of the first EHT sounding NDP 712 has been transmitted, STA1 704 may switch from the awake state to the dosed state for power saving. At 715 during SIFS 714, the next STA in the STA ordering, for example STA2 706, may switch back from the dosed state to the awake state. At 716 after SIFS 714, AP 702 may transmit a second EHT NDP announcement frame 718, which may indicate the sounding RU assignment and sounding SS assignment for the next STA in the STA ordering. When transmitting the second EHT NDP announcement frame 718, SIFS 719 may be enabled, and at 720, STA2 706 may prepare a second EHT sounding NDP 722 based on its own sounding RU assignment and sounding SS assignment and transmit it to AP 702. AP702 may then estimate a second UL CSI from the received second EHT sounding NDP722 and determine the DL CSI corresponding to STA2 706 by compensating the second UL CSI according to the calibration parameters obtained from the calibration procedure. Furthermore, based on the DL CSIs for STA1 704 and STA2 706, AP702 may determine the steering matrix and / or assign 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 Figure 7A does not require the transmission of sounding feedback information and therefore may require less sounding overhead than the single AP-based explicit sounding procedure shown in Figure 6B.

[0076] Figure 7B shows a flowchart illustrating a single-AP-based implicit sequential sounding procedure 730 between AP732 and several STA734, 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 AP732 sends an EHT NDP announcement frame 738 to target STAs, such as STA1 734 and STA2 736. The EHT NDP announcement frame 738 may indicate an STA ordering, and target STAs such as STA1 734 to STA2 736 may send an EHT sounding NDP to AP732 in this STA ordering. The EHT NDP announcement frame 738 may indicate sounding RU assignments and sounding SS assignments for each of the target STAs. Thus, from the sounding SS assignment to the STA, 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 each STA's EHT sounding NDP, a second EHT sounding NDP from a second STA in the STA ordering may follow the first EHT sounding NDP from the first STA in the STA ordering.

[0077] For example, SIFS739 may be enabled when transmitting the EHT NDP announcement frame 738, and during SIFS739, at 740, STAs other than the first STA in the STA ordering, such as STA2 706, may be switched from the awake state to the dosed state for power saving, and at 741 after SIFS, the first STA in the STA ordering, such as STA1 734, may transmit the first EHT sounding NDP742 to AP732. AP732 may then determine the DL CSI corresponding to STA1 734 by estimating the first UL CSI from the received first EHT sounding NDP742 and compensating the first UL CSI according to the calibration parameters obtained from the calibration procedure. At 743, after the last symbol of the first EHT sounding NDP742 has been transmitted, STA1 734 may be switched from the awake state to the dosed state for power saving. SIFS744 may be enabled, and at 745 during SIFS744, STA2 736 may switch from a dozed state to an awake state, and at 746 after SIFS744, STA2 736 may transmit a second EHT sounding NDP748 to AP732. AP732 may then determine the DL CSI corresponding to STA2 736 by estimating a second UL CSI from the received EHT sounding NDP748 and compensating the second UL CSI according to the calibration parameters obtained from the calibration procedure. Furthermore, based on the DL CSI for STA1 734 and STA2 736, AP732 may determine a steering matrix and / or assign appropriate RUs to each of STA1 734 and STA2 736 for subsequent transmissions to STA1 734 and / or STA2 736. Advantageously, the single AP-based implicit sequential sounding option 2 shown in Figure 7B reduces sounding overhead even further than the single AP-based implicit sequential sounding option 1 shown in Figure 7A.

[0078] Figure 8 shows a flowchart illustrating a single-AP-based implicit joint sounding procedure 800 between AP802 and several STA804, 806 in an 11be EHT WLAN according to one embodiment. The single-AP-based implicit joint sounding procedure 800 may be initiated when AP802 sends an EHT NDP announcement frame 808 to target STAs, such as STA1 804 and STA2 806. The EHT NDP announcement frame 808 may indicate the sounding RU assignment and sounding SS assignment for each of the target STAs. When the EHT NDP announcement frame 808 is sent, SIFS 809 may be enabled, and in 810, STA1 804 and STA2 806 may send their respective EHT sounding NDPs 812, 814 to AP808 according to their respective sounding RU assignments and sounding SS assignments. AP802 may then estimate a first UL CSI from the received EHT sounding NDP812 and a second UL CSI from the received EHT sounding NDP814, and determine the DL CSI corresponding to STA1 804 and STA2 806 respectively by compensating the first and second UL CSIs according to the calibration parameters obtained from the calibration procedure. Furthermore, based on the DL CSIs for STA1 804 and STA2 806, AP802 may determine a steering matrix and / or assign appropriate RUs to each of STA1 804 and STA2 806 for subsequent transmissions to STA1 804 and / or STA2 806. Advantageously, the single AP-based implicit joint sounding shown in Figure 8 may have lower sounding overhead than the single AP-based implicit sequential sounding shown in Figures 7A and 7B.

[0079] Figure 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 one embodiment. The multi-AP-based explicit sequential sounding procedure 900 may be initiated when a source AP 902 sends a first EHT NDP announcement frame 910 to the destination APs (one or more) participating in the sounding procedure 1000 and to target STAs such as STA1 906 and STA2 908. The first EHT NDP announcement frame 910 may indicate destination AP ordering, and the destination APs (one or more) engaged in the sounding procedure 900 may send EHT NDP announcement frames and EHT sounding NDPs to target STAs such as STA1 906 and STA2 908 in this destination AP ordering. The first EHT NDP announcement frame 910 may indicate the sounding RU allocation and sounding SS allocation for each shared AP(s)(s)(s) engaged in the sounding procedure 900. Each EHT NDP announcement frame may indicate the required sounding feedback parameters for each STA, such as the feedback bandwidth, feedback type, subcarrier grouping, quantization resolution, and number of columns in 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 required sounding feedback information includes compressed beamforming feedback information per subcarrier or subcarrier group. When the feedback type is CQI feedback, the required sounding feedback information includes CQI information per subcarrier or subcarrier group. When the feedback type is calibration feedback, the required sounding feedback information includes compressed CSI per subcarrier or subcarrier group.

[0080] When the first EHT NDP announcement frame 910 is transmitted, SIFS 911 may be enabled, and in 912, source AP 902 may transmit the 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 in 916, source 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 in 920, STA1 906 and STA2 908 may simultaneously transmit their respective first EHT compressed beamforming / CQI frames 922 and 924 containing sounding feedback information to source AP 902. Based on the sounding feedback information received from STA1 906 and STA2 908, the sharing AP902 may determine the steering matrix and / or assign appropriate RUs to each of STA1 906 and STA2 908 for subsequent transmissions to STA1 906 and / or STA2 908.

[0081] When the first EHT Compression Beamforming / CQI frames 922, 924 are transmitted, SIFS 925 may be enabled, and in 926, the next AP in the AP ordering, for example, shared AP 904, may transmit the second EHT NDP announcement frame 928 to STA1 906 and STA2 908. When the second EHT NDP announcement frame 928 is transmitted, SIFS 929 may be enabled, and in 930, shared AP 904 may transmit the second EHT Sounding NDP 932 to STA1 906 and STA2 908. Similarly, after the second EHT Sounding NDP 932 has been transmitted, SIFS 933 may be enabled, and in 934, shared AP 904 may transmit the 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 has been transmitted, SIFS 937 may be enabled, and in 938, STA1 906 and STA2 908 may simultaneously transmit their respective second EHT Compression 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 determine the steering matrix and / or assign appropriate RUs to each of STA1 906 and STA2 908 for subsequent transmissions to STA1 906 and / or STA2 908.

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

[0083] In various embodiments, when procedures 900, 1000 are multi-AP-based calibration procedures, EHT NDP announcement frames 910, 928, 1010 may indicate calibration RU assignments and calibration SS assignments for each STA, such as STA1 906, STA2 908, STA1 1006, STA2 1008, etc. In particular, data RU assignments and data SS assignments for each STA are shown in the corresponding EHT BFRP trigger frames 918, 936, 1020. Calibration SS assigned to an STA may include data SS assigned to that STA. In other words, the number of calibration SS may be greater than or equal to the number of data SS. Calibration RU assigned to an STA may be the same as the data RU assigned to that STA.

[0084] In various embodiments, when steps 900, 1000 are multi-AP-based calibration steps, 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, such as STA1 906, STA2 908, STA1 1006, STA2 1008, transmits multiple SSs on the EHT-LTF field of the EHT PPDU containing 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, AP902, 904, 1002, and 1004 may determine the calibration coefficients for each of their TX antennas according to the DL-compressed CSI and UL CSI estimation contained in EHT-compressed beamforming / CQI frames 922, 924, 940, 942, 1024, and 1026.

[0085] In various embodiments, there are two options for the 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 SSs on the EHT-LTF field of multiple EHT PPDUs containing EHT compressed beamforming / CQI frames, which may result in a favorable reduction of 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 are P 8x8 Alternatively, using a matrix, four SSs may be transmitted on eight EHT-LTF symbols of the EHT PPDU, including EHT compressed beamforming / CQI frames 922, 924, 940, and 942, while in option 2, STA1 906 and STA2 908 are P 4x4The matrix may be used to transmit two SSs on four EHT-LTF symbols of the EHT PPDU, including the first EHT compressed beamforming / CQI frames 922, 924, and STA1 906 and STA2 908 are P 4x4 Using a matrix, two additional SSs may be transmitted on the four EHT-LTF symbols of the EHT PPDU, including the second EHT compressed beamforming / CQI frames 940 and 942.

[0086] Figure 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 one embodiment. The multi-AP-based explicit joint sounding procedure 1000 may be initiated when a sharing AP 1002 sends an EHT NDP announcement frame 1010 to the sharing APs(s) participating in the sounding procedure 1000 and target STAs such as STA1 1006 and STA2 1008. The EHT NDP announcement frame 1010 may indicate sounding RU assignments and sounding SS assignments for each sharing AP engaged in the sounding procedure 1000. The EHT NDP announcement frame 1010 may indicate the required sounding feedback parameters for each pair of STAs and APs among the source AP 1002, destination AP 1004, and target STAs 1006 and 1008. The required sounding feedback parameters for each AP-STA pair may include AP-dependent sounding feedback parameters, such as the feedback bandwidth and the number of columns in the compressed beamforming feedback matrix, and AP-independent sounding feedback parameters, such as the feedback type, subcarrier grouping, and quantization resolution. With respect to the sounding results used for joint beamforming, the AP-independent sounding feedback parameters for each STA may be set to the same value for all AP-STA pairs in the EHT NDP announcement frame 1010, while the AP-dependent sounding feedback parameters may be set to different values ​​for each AP-STA pair in the EHT NDP announcement frame 1010.

[0087] When the EHT NDP announcement frame 1010 is transmitted, SIFS 1011 may be enabled, and in 1012, all APs engaged in the sounding procedure 1000, such as the source AP 1002 and the destination AP 1004, may simultaneously transmit their respective EHT sounding NDPs 1014 and 1016 to all target STAs, such as STA1 1006 and STA2 1008. After the EHT sounding NDPs 1014 and 1016 have been transmitted, SIFS 1017 may be enabled, and in 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 has been transmitted, SIFS 1021 may be enabled, and in 1022, STA1 1006 and STA2 1008 may simultaneously transmit their respective EHT Compression Beamforming / CQI frames 1024 and 1026 containing the requested sounding feedback information to AP 1002 and 1004. Based on the sounding feedback information received from STA1 1006 and STA2 1008, AP 1002 and 1004 may determine the steering matrix and / or assign appropriate RUs to each of STA1 1006 and STA2 1008 for subsequent transmissions to STA1 1006 and / or STA2 1008. Alternatively, the source AP 1002 may determine the steering matrix and / or assign appropriate RUs to each AP-STA pair. Next, source AP1002 may notify destination AP1004 of the corresponding steering matrix, and / or the RU allocation for STA1 1006 and / or STA2 1008 for subsequent transmissions to STA1 1006 and / or STA2 1008. Advantageously, the multi-AP based explicit joint sounding shown in Figure 10 has less sounding overhead than the multi-AP based explicit sequential sounding shown in Figure 9.

[0088] Figure 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 source AP 1102 sends a first EHT NDP announcement frame 1110 to the destination AP(s) participating in the sounding procedure 1100 and target STAs such as STA1 1106 and STA2 1108. The first EHT NDP announcement frame 1110 may indicate a destination AP(s) participating in the sounding procedure 1100, such as destination AP 1104. The first EHT NDP announcement frame 1110 may also indicate STA ordering, for example, target STAs such as STA1 1106 to STA2 1108 may send EHT sounding NDP to the source AP 1102 and all shared APs participating in the sounding procedure 1100 in this STA ordering. Each EHT NDP announcement frame 1110, 1120 may indicate sounding RU assignments and sounding SS assignments for the corresponding STAs. SIFS 1111 may be enabled when the first EHT NDP announcement frame 1110 is sent. During SIFS1111, at 1112, one or more STAs other than the first STA in the STA ordering, for example STA2 1108, may be switched from the awake state to the dosed state for power saving, and at 1113 after SIFS, the first STA in the STA ordering, for example STA1 1106, may transmit the first EHT sounding NDP1114 to the source AP1102 and the destination AP1104. The source AP1102 and the destination AP1104 may then estimate the UL CSI from the received first EHT sounding NDP1114 and determine the DL CSI for STA1 1106 by compensating the UL CSI according to the calibration parameters obtained from the calibration procedure.Furthermore, based on the DL CSI for STA1 1106, the source AP1102 and the destination AP1104 may determine the steering matrix and / or allocate an appropriate RU to STA1 1106 for subsequent transmissions to STA1 1106.

[0089] At 1115, after the last symbol of the first EHT sounding NDP 1114 has been transmitted, STA1 1106 may switch from the awake state to the dosed state for power saving. SIFS 1116 may be enabled, and at 1117 during SIFS 1116, the next STA in the STA ordering, for example STA2 1108, may switch from the dosed state to the awake state, and at 1118 after SIFS 1116, AP1102 may transmit the second EHT NDP announcement frame 1120. When transmitting the second EHT NDP announcement frame 1120, SIFS 1121 may be enabled, and at 1122, STA2 1108 may transmit the second EHT sounding NDP 1124 to the sharing source AP1102 and the sharing destination AP1104. Next, source AP1102 and destination AP1104 determine the DL CSI for STA2 1108 by estimating the UL CSI from the received second EHT sounding NDP1124 and compensating the UL CSI according to the calibration parameters obtained from the calibration procedure. Furthermore, based on the DL CSI for STA2 1108, source AP1102 and destination AP1104 may determine the steering matrix and / or allocate appropriate RUs to STA2 1108 for subsequent transmissions to STA2 1108. Advantageously, the multi-AP-based implicit sequential sounding procedure shown in Figure 11A may require less sounding overhead than the multi-AP-based explicit sounding procedure shown in Figure 9 or 10 because it does not require the transmission of sounding feedback information.

[0090] Figure 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 AP 1132 sends an EHT NDP announcement frame 1140 to the sharing AP(s) participating in the sounding procedure 1130 and the target STAs, such as STA1 1136 and STA2 1138. The EHT NDP announcement frame 1140 indicates the sharing AP(s) participating in the sounding procedure 1130, such as sharing AP 1134. The EHT NDP announcement frame 1140 may also indicate an STA ordering, where, for example, target STAs such as STA1 1136 to STA2 1138 may send an EHT sounding NDP to AP 1132 and to the shared AP(s) participating in the sounding procedure 1130. The EHT NDP announcement frame 1140 may further indicate sounding RU assignments and sounding SS assignments for each STA. Thus, the EHT-LTF field duration (equivalent to the transmission time of the EHT sounding NDP) of the EHT sounding NDP sent 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, a second EHT sounding NDP from a second STA in the STA ordering may follow the first EHT sounding NDP from a first STA in the STA ordering.

[0091] For example, SIFS1141 may be enabled when transmitting the EHT NDP announcement frame 1140, and during SIFS1141, in 1142, an STA other than the first STA in the STA ordering, such as STA2 1138, may be switched from the awake state to the dose state for power saving, and in 1143 after SIFS, the first STA in the STA ordering, such as STA1 1136, may transmit the first EHT sounding NDP1144 to the source AP1132 and the destination AP1134. The source AP1132 and the destination AP1134 may then estimate the UL CSI from the received first EHT sounding NDP1144 and determine the DL CSI for STA1 1136 by compensating the UL CSI according to the calibration parameters obtained from the calibration procedure. At 1145, after transmitting the last symbol of the first EHT sounding NDP 1144, STA1 1136 may switch from the awake state to the dosed state for power saving. SIFS 1148 may be enabled, and at 1147 during SIFS 1148, STA2 1138 may switch back from the dosed state to the awake state, and at 1148 after SIFS 1146, STA2 1138 may transmit the second EHT sounding NDP 1150 to the source AP 1132 and the destination AP 1134. The source AP 1132 and the destination 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 the calibration parameters obtained from the calibration procedure. Furthermore, based on the DL CSI for STA1 1136 and STA2 1138, source AP1132 and destination AP1134 may determine the steering matrix 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 Figure 11B further reduces sounding overhead compared to the multi-AP-based implicit sequential sounding option 1 shown in Figure 11A.

[0092] Figure 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 a source AP 1202 sends an EHT NDP announcement frame 1210 to the sharing destination AP(s) participating in the sounding procedure 1200, such as sharing destination AP 1204, and to the target STAs, such as STA1 1206 and STA2 1208. The EHT NDP announcement frame 1210 may indicate the sharing destination AP(s) participating in the sounding procedure 1200, and may also indicate the sounding RU assignment and sounding SS assignment for each STA. When transmitting the EHT NDP announcement frame 1210, SIFS 1211 may be enabled, and in 1212, STA1 1206 and STA2 1208 may transmit their respective EHT sounding NDPs 1214 and 1216 to source AP 1202 and destination AP 1204. Then, source AP 1202 and destination AP 1204 may determine the DL CSI for STA1 1206 by estimating a 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, source AP 1202 and destination AP 1204 may determine the DL CSI for STA2 1208 by estimating a 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, source AP1202 and destination AP1204 may determine the steering matrix and / or assign 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 Figure 12 may require less sounding overhead than the multi-AP-based implicit sequential sounding shown in Figures 11A and 11B.

[0093] According to this disclosure, the source APs and destination APs (one or more) engaged in a multi-AP-based hybrid sounding procedure are divided into two groups: Group 1 APs include APs (one or more) that participate in the explicit sounding portion of the multi-AP-based hybrid sounding procedure, and Group 2 APs include APs (one or more) that participate in the implicit sounding portion of the multi-AP-based hybrid sounding procedure.

[0094] Figure 13A shows a flowchart illustrating a multi-AP-based hybrid sequential sounding procedure 1300 between multiple shared APs 1302, 1304, and 1306 and an STA 1308 in an 11be EHT WLAN according to one embodiment. In this embodiment, source AP 1302 and shared AP1 1304 are APs of Group 1, while shared AP2 1306 is an AP of Group 2. The multi-AP-based hybrid sequential sounding procedure 1300 may be initiated when source AP 1302 sends a first EHT NDP announcement frame 1310 to all shared APs (one or more) participating in the sounding procedure 1300 (e.g., shared APs 1304, 1306) and the target STA 1308. The first EHT NDP announcement frame 1310 may indicate the APs of Group 2 and the ordering of the APs of Group 1, where each AP of Group 1 may send 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 the sounding RU assignment and sounding SS assignment for each AP of Group 1. Each EHT NDP announcement frame may indicate the sounding RU assignment and sounding SS assignment for the target STA 1308. Each EHT NDP announcement frame may indicate the requested sounding feedback parameters for the target STA 1308, such as the feedback bandwidth, feedback type, subcarrier grouping, quantization resolution, and number of columns in the compressed beamforming feedback matrix. The feedback type is one of SU feedback, MU feedback, and CQI feedback. When the first EHT NDP announcement frame 1310 is transmitted, SIFS 1311 may be enabled, and in 1312, the sharing source AP 1302 may transmit the first EHT sounding NDP 1314 to STA 1308.After the last symbol of the first EHT sounding NDP 1314 is transmitted, SIFS 1315 may be enabled, and in 1316, STA 1308 transmits the first EHT compressed beamforming / CQI frame 1318 containing sounding feedback information to source AP 1302. 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 group 2 APs (one or more), such as destination AP 2 1306. Based on the sounding feedback information received from STA 1308, source AP 1302 may determine the steering matrix and / or assign appropriate RUs to STA 1308 for subsequent transmissions to STA 1308.

[0095] When the first EHT Compression Beamforming / CQI frame 1318 is transmitted, SIFS 1319 may be enabled, and in 1320, the next AP in the AP ordering of group 1, for example, shared AP1 1304, may transmit a second EHT NDP announcement frame 1322 to STA1308. When the second EHT NDP announcement frame 1322 is transmitted, SIFS 1323 may be enabled, and in 1324, shared AP1 1304 may transmit a second EHT Sounding NDP 1326 to STA1308. Similarly, after the second EHT Sounding NDP 1326 has been transmitted, SIFS 1327 may be enabled, and in 1328, STA1308 may transmit a second EHT Compression Beamforming / CQI frame 1330 containing sounding feedback information to shared AP1 1304. Furthermore, the EHT-LTF field of the EHT PPDU, including the second EHT compression beamforming / CQI frame 1330, may also be used for implicit sounding by AP(s) of Group 2, such as shared AP2 1306. Based on the sounding feedback information received from STA1308, shared AP1304 may determine the steering matrix and / or assign an appropriate RU to STA1308 for subsequent transmissions to STA1308. Furthermore, shared AP2 1306 may determine the DL CSI corresponding to STA1308 by estimating the UL CSI from the EHT-LTF field of the EHT PPDU, which includes the first and second EHT compressed beamforming / CQI frames 1318, 1330, and compensating the UL CSI according to the calibration parameters obtained from the calibration procedure. Shared AP1306 may then determine the steering matrix and / or assign appropriate RUs to STA1308 based on the DL CSI for subsequent transmissions to STA1308.

[0096] Figure 13B shows a flowchart illustrating a multi-AP-based hybrid sequential sounding procedure 1340 between multiple shared APs 1342, 1344, and 1346 and multiple STAs 1348 and 1350 in an 11be EHT WLAN according to one embodiment. In this embodiment, source AP 1342 and shared AP1 1344 are APs of Group 1, while shared AP2 1346 is an AP of Group 2. The multi-AP-based hybrid sequential sounding procedure 1340 may be initiated when source AP 1342 sends a first EHT NDP announcement frame 1352 to all shared APs (one or more) participating in the sounding procedure 1340 (e.g., shared APs 1344 and 1346) and target STAs 1348 and 1350. The first EHT NDP announcement frame 1352 may indicate the APs of Group 2 and the ordering of the APs of Group 1, where each AP of Group 1 may send 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 sounding RU assignments and sounding SS assignments for each AP of Group 1. Each EHT NDP announcement frame may indicate sounding RU assignments and sounding SS assignments for each of STA1 1348 and STA2 1350. In particular, the data RU assignments and data SS assignments for each of STA1 1348 and STA2 1350 are shown in the corresponding EHT BFRP trigger frame. Sounding SS may include data SS. In other words, the number of sounding SS may be greater than or equal to the number of data SS. 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 STA1348 and 1350, such as feedback bandwidth, feedback type, subcarrier grouping, quantization resolution, and the number of columns in the compressed beamforming feedback matrix.The feedback type is one of SU feedback, MU feedback, and CQI feedback. SIFS 1353 may be enabled when the first EHT NDP announcement frame 1352 is transmitted, and in 1354, source AP 1342 may transmit the 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 in 1358, source 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 in 1362, STA1 1348 and STA2 1350 simultaneously transmit their respective first EHT compressed beamforming / CQI frames 1364 and 1366, containing sounding feedback information, to the source AP 1342. The EHT-LTF field of the EHT PPDU containing the first EHT compressed beamforming / CQI frames 1364 and 1366 may also be used for CSI estimation for implicit sounding by group 2 APs (one or more), such as the shared AP2 1346. Based on the sounding feedback information received from STA1 1348 and STA2 1350, the sharing AP1342 may determine the 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] When transmitting the first EHT Compression Beamforming / CQI frames 1364 and 1366, SIFS 1367 may be enabled, and in 1368, the next AP in the AP ordering of group 1, for example, shared AP1 1344, may transmit the second EHT NDP announcement frame 1370 to STA1 1348 and STA2 1350. When transmitting the second EHT NDP announcement frame 1370, SIFS 1371 may be enabled, and in 1372, shared AP1 1344 may transmit the 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, source 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 beamforming / CQI frames 1382 and 1384, containing sounding feedback information, to source AP 1344. Furthermore, the EHT-LTF field of the EHT PPDU, including the second EHT compressed beamforming / CQI frames 1382, 1384, may also be used for CSI estimation for implicit sounding by group 2 APs (one or more), such as shared AP2 1346. Based on the sounding feedback information received from STA1 1348 and STA2 1350, shared AP1 1344 may determine the steering matrix and / or assign 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 determine the DL CSI for STA1 1348 by estimating the UL CSI from the EHT-LTF field of the EHT PPDU, which includes the first and second EHT compressed beamforming / CQI frames 1364 and 1382, and compensating for the UL CSI according to the calibration parameters obtained from the calibration procedure, and then shared AP2 1346 may determine the steering matrix and / or assign an appropriate RU to STA1 1348 based on the DL CSI for subsequent transmissions to STA1 1348. Similarly, shared AP2 1346 may determine the DL CSI for STA2 1350 by estimating the UL CSI from the EHT-LTF field of the EHT PPDU containing the first and second EHT compressed beamforming / CQI frames 1366, 1384, and compensating for the UL CSI according to the calibration parameters obtained from the calibration procedure, and then shared AP2 1346 may determine the steering matrix and / or assign an appropriate RU to STA2 1350 based on the DL CSI for subsequent transmissions to STA2 1350.

[0098] Figure 14A shows a flowchart illustrating a multi-AP-based hybrid joint sounding procedure 1400 between multiple shared APs 1402, 1404, and 1406 and an STA 1408 in an 11be EHT WLAN, according to one embodiment. In this embodiment, source AP 1402 and shared AP1 1404 are APs of Group 1, while shared AP2 1406 is an AP of Group 2. The multi-AP-based hybrid sequential sounding procedure 1400 may be initiated when source AP 1402 sends an EHT NDP announcement frame 1410 to all shared APs (one or more) participating in the sounding procedure 1400 (e.g., shared APs 1404, 1406) and the target STA 1408. The EHT NDP announcement frame 1410 may indicate the ordering of APs in Group 2 and APs in Group 1, where each AP in Group 1 may send an EHT sounding NDP to the target STA. The EHT NDP announcement frame 1410 may indicate the sounding RU assignment and sounding SS assignment for each AP in Group 1. The EHT NDP announcement frame may indicate the sounding RU assignment and sounding SS assignment for the target STA 1408. The EHT NDP announcement frame may indicate the requested sounding feedback parameters for each pair of target STA 1408 and APs in Group 1, such as feedback bandwidth, feedback type, subcarrier grouping, quantization resolution, and number of columns in the compressed beamforming feedback matrix. The feedback type is one of SU feedback, MU feedback, and CQI feedback. When sending the EHT NDP announcement frame 1410, SIFS 1411 may be enabled, and in 1412, the source AP 1402 and the destination AP 1404 may simultaneously send their respective EHT sounding NDP 1414 and 1416 to STA 1408.After the last symbol of the EHT sounding NDP 1414, 1416 is transmitted, SIFS 1417 may be enabled, and in 1418, STA 1408 transmits the EHT Compressed Beamforming / CQI frame 1419 containing sounding feedback information to source AP 1402 and destination AP 1 1404. 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 group 2 APs (one or more), such as destination AP 2 1406. Based on the sounding feedback information received from STA 1408, source AP 1402 and destination AP 1 1404 may determine the steering matrix and / or assign an appropriate RU to STA 1408 for subsequent transmissions to STA 1408. Furthermore, shared AP2 1406 may determine the DL CSI for STA1408 by estimating the UL CSI from the EHT-LTF field of the EHT PPDU containing the EHT compressed beamforming / CQI frame 1419 and compensating for the UL CSI according to the calibration parameters obtained from the calibration procedure, and then shared AP2 1406 may determine the steering matrix and / or allocate an appropriate RU to STA1408 based on the DL CSI for subsequent transmissions to STA1408.

[0099] Figure 14B shows a flowchart illustrating a multi-AP-based hybrid joint sounding procedure 1420 between multiple shared APs 1422, 1424, and 1426 and multiple STAs 1428 and 1430 in an 11be EHT WLAN, according to one embodiment. In this embodiment, source AP 1422 and shared AP1 1424 are APs of Group 1, while shared AP2 1426 is an AP of Group 2. The multi-AP-based hybrid joint sounding procedure 1420 may be initiated when source AP 1422 sends an EHT NDP announcement frame 1432 to all shared APs (one or more) participating in the sounding procedure 1420 (e.g., shared APs 1424 and 1426) and target STAs 1428 and 1430. The EHT NDP announcement frame 1432 may indicate the APs of Group 2 and the ordering of APs of Group 1, where each AP of Group 1 may send an EHT sounding NDP to target STA1 1428 and STA2 1430. The EHT NDP announcement frame 1432 may indicate the sounding RU assignments and sounding SS assignments for each AP of Group 1. The EHT NDP announcement frame 1432 may indicate the sounding RU assignments and sounding SS assignments for each of STA1 1428 and STA2 1430. In particular, the data RU assignments and data SS assignments for each of STA1 1428 and STA2 1430 are indicated in the corresponding EHT BFRP trigger frame 1442. The sounding SS may include data SS. In other words, the number of sounding SS may be greater than or equal to the number of data SS. 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 target STA 1428 and 1430, respectively, such as the feedback bandwidth, feedback type, subcarrier grouping, quantization resolution, and the number of columns in the compressed beamforming feedback matrix.The feedback type is one of SU feedback, MU feedback, and CQI feedback. SIFS1433 may be enabled when the EHT NDP announcement frame 1432 is transmitted, and in 1434, source AP1422 and destination AP1 1424 may transmit their respective EHT sounding NDPs 1436 and 1438 to STA1 1428 and STA2 1430. After the last symbol of the EHT sounding NDPs 1436 and 1438 is transmitted, SIFS1439 may be enabled, and in 1440, source AP1422 may transmit the EHT BFRP trigger frame 1442 to request simultaneous transmission of sounding feedback information from STA1 1428 and STA2 1430. When the EHT BFRP trigger frame 1442 is received, SIFS 1443 may be enabled, and in 1444, STA1 1428 and STA2 1430 simultaneously transmit their respective EHT compressed beamforming / CQI frames 1446 and 1448, which contain sounding feedback information, to source AP 1422 and destination AP1 1424. The EHT-LTF field of the EHT PPDU, which includes the EHT compressed beamforming / CQI frames 1446 and 1448, can also be used for CSI estimation for implicit sounding by AP(s) of Group 2, such as destination AP2 1426. Based on the sounding feedback information received from STA1 1428 and STA2 1430, source AP1422 and destination AP1 1424 may determine the steering matrix 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 determine the DL CSI for STA1 1428 by estimating the UL CSI from the EHT-LTF field of the EHT PPDU containing the EHT compressed beamforming / CQI frame 1446 and compensating for the UL CSI according to the calibration parameters obtained from the calibration procedure, and then shared AP2 1426 may determine the steering matrix and / or assign an appropriate RU to STA1 1428 based on the DL CSI for subsequent transmissions to STA1 1428. Similarly, shared AP2 1426 may determine the DL CSI for STA1430 by estimating the UL CSI from the EHT-LTF field of the EHT PPDU containing the EHT compressed beamforming / CQI frame 1448 and compensating for the UL CSI according to the calibration parameters obtained from the calibration procedure, and then shared AP2 1426 may determine the steering matrix and / or assign an appropriate RU to STA1430 based on the DL CSI for subsequent transmissions to STA1430.

[0100] Figure 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 dialog 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 together as a MAC header.

[0101] When the sounding type field 1502 indicates a single AP-based explicit sounding, the AP-STA information field 1504 for the 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 column number field for the compressed beamforming feedback matrix. In one embodiment, the STA feedback information field is used to indicate the required sounding feedback parameters for the STA indicated in the target STA field.

[0102] When the sounding type field 1502 indicates a single AP-based implicit sounding, the AP-STA information field 1504 for the 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, an STA sounding RU assignment field, and an STA sounding SS assignment field. In one embodiment, the STA sounding information field is used to indicate sounding RU assignments and sounding SS assignments for the STA indicated in the target STA field.

[0103] When the sounding type field 1502 indicates a multi-AP-based explicit sounding, the AP-STA information field 1504 for the multi-AP-based explicit sounding may include one or more AP-STA explicit sounding information fields 1606 as shown in Figure 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 Figure 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 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, one or more target AP fields are used to indicate the shared AP(s) participating in the multi-AP-based implicit sounding, and 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 Figure 16C, which indicate the information necessary for the explicit sounding portion of the multi-AP based hybrid sounding, one or more target AP fields, and one or more STA sounding information fields 1604, as shown in Figure 16B, which indicate the information necessary for the implicit sounding portion of the multi-AP based hybrid sounding.

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

[0107] The receiving 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 including an EHT NDP announcement frame, an EHT action frame, or an EHT BFRP trigger frame). The receiving 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 including an EHT compressed beamforming / CQI frame). 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 assigning downlink SU or MU transmissions, and trigger information for assigning uplink MU transmissions. The control signal parser 1742 may analyze the control signaling portion of the received signal and the trigger information for assigning uplink MU transmissions, which is 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, including the EHT compressed beamforming / CQI frame).

[0108] Figure 18 shows the configuration of a communication device, such as an STA, according to the present disclosure. Similar to the schematic example of the communication device 300 shown in Figure 3A, the communication device 1800 includes a circuit 1802, at least one radio transmitter 1810, at least one radio receiver 1812, and at least one antenna 1814 (for simplicity, only one antenna is shown in Figure 18). The circuit 1802 may also include at least one controller 1808, which is used for software and hardware-assisted execution of the task for which it is designed to perform communication for channel sounding. The circuit 1802 may further include a receive signal processor 1806 and a transmit signal generator 1804. At least one controller 1808 may control the receive signal processor 1806 and the transmit signal generator 1804. The 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 an EHT sounding NDP, or the EHT-SIG field of an EHT PPDU containing an EHT NDP announcement frame or an 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 an EHT PPDU containing an EHT NDP announcement frame or an EHT BFRP trigger frame) according to the RU information and the user-specific assignment information of its own assignment.

[0109] 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 analyze 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 NDP announcement frame or an 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 an EHT PPDU containing an EHT NDP announcement frame or an EHT BFRP trigger frame). The trigger information parser 1848 may analyze trigger information for its uplink assignment from the received trigger frame contained in the data portion of the received signal. The transmit signal generator 1804 may also include a control signaling generator 1824, which may generate the control signaling field of the PPDU to be generated (e.g., the EHT-SIG field of an EHT sounding NDP, or the EHT-SIG field of an EHT PPDU containing an EHT compression beamforming / CQI frame). The transmit signal generator 1804 may further include a PPDU generator 1826, which may generate a PPDU (e.g., an EHT sounding NDP or an EHT PPDU containing an EHT compression 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 compression beamforming / CQI frame.

[0110] As described above, embodiments of the present disclosure provide advanced communication systems, communication methods, and communication devices for channel sounding in MIMO WLAN networks to improve spectral efficiency in MIMO WLAN networks.

[0111] This disclosure can be implemented by software, hardware, or software working in conjunction with hardware. Each functional block used in the description of each embodiment above can be implemented partially or entirely by an LSI, such as an integrated circuit, and each process described in each embodiment may be controlled partially or entirely by the same LSI or combination of LSIs. The LSI may be formed as individual chips, or one chip may be formed to include part or all of the functional blocks. The LSI may include data inputs and outputs coupled to the data inputs. In this specification, LSIs may be referred to as ICs, system LSIs, super LSIs, or ultra LSIs depending on the degree of integration. However, the technology for implementing integrated circuits is not limited to LSIs and may also be implemented using dedicated circuits, general-purpose processors, or purpose-specific processors. In addition, FPGAs (Field Programmable Gate Arrays) that can be programmed after the LSI is manufactured, or reconfigurable processors that can reconfigure the connections and settings of circuit cells located inside the LSI, may be used. This disclosure can be implemented as digital or analog processing. In future integrated circuit technology, 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 technology. Biotechnology may also be applied.

[0112] This disclosure can be implemented by any type of device, apparatus, or system having communication capabilities, which is referred to as a communication apparatus.

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

[0114] Some non-exclusive examples of such communication devices include telephones (e.g., cellular 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, smartwatches, tracking devices), game consoles, digital book readers, telemedicine / telemedicine (remote medical and therapeutic) devices, and vehicles that provide communication capabilities (e.g., automobiles, aircraft, ships), as well as various combinations thereof.

[0115] Communication devices are not limited to portable or mobile devices, but may include any type of non-portable or fixed device, device, or system, such as smart home devices (e.g., appliances, lighting, smart meters, control panels), vending machines, and any other “things” in the “Internet of Things (IoT)” network.

[0116] Communication may include exchanging data through, for example, cellular systems, wireless LAN systems, satellite systems, and various combinations thereof.

[0117] The communication device may include devices such as controllers or sensors that are coupled to a communication device that performs the communication functions described in this disclosure. For example, the communication device may include controllers or sensors that generate control signals or data signals used by the communication device that performs the communication functions of the communication device.

[0118] In addition, the communication 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 non-limiting examples above.

[0119] While we have described some characteristics of various embodiments by referring to the device, it will be understood that the corresponding characteristics also apply to the methods of various embodiments, and vice versa.

[0120] Those skilled in the art will recognize that numerous changes and / or modifications may be made to the disclosure shown in particular embodiments without departing from the spirit or scope of the broadly described disclosure. Therefore, these embodiments should be considered illustrative and not restrictive in all respects.

Claims

1. A circuit that generates a first frame indicating the target application of the sounding procedure, A transmitter that transmits the first frame to a second communication device, The system comprises a receiver that receives a second frame in response to the first frame from the second communication device, The transmitter transmits a third frame relating to a Null Data Packet (NDP) announcement. Communication device.

2. The first communication device transmits the third frame after receiving the second frame. The communication device according to claim 1.

3. The first communication device is a first access point, and the second communication device is a second access point. The communication device according to claim 1.

4. The third frame indicates the start of the sounding procedure. The communication device according to claim 1.

5. The first frame indicates one or more target communication devices that will engage in the sounding procedure. The communication device according to claim 1.

6. Includes a receiver that receives the second frame indicating one or more recommended types of the sounding procedure, The communication device according to claim 1.

7. The second frame indicates that the communication device should be excluded from the sounding procedure. The communication device according to claim 1.

8. The third frame includes a field indicating the type of the sounding procedure, Includes a field indicating the type of sounding feedback, The communication device according to claim 1.

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

10. When the sounding procedure is a hybrid sounding procedure including an explicit sounding portion and an implicit sounding portion, at least one of the first and second communication devices is configured to engage in the explicit sounding portion of the sounding procedure, and the remaining communication device is configured to engage in the implicit sounding portion of the sounding procedure. The communication device according to claim 1.

11. A first frame is generated that indicates the target application of the sounding procedure. The first frame is transmitted to the second communication device. A second frame in response to the first frame is received from the second communication device. Send a third frame regarding the Null Data Packet (NDP) announcement. Communication method.

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