Wireless communication control device and wireless communications control method

Abstract

To make it possible to reduce a processing time.SOLUTION: A wireless communication device causes a wireless transmission unit to transmit a reference signal in a known pattern addressed to a wireless communication terminal in coordination with one or more other wireless communication devices, generates a request signal for requesting a second measurement result simpler than a first measurement result of the reference signal to the wireless communication terminal, and causes the wireless transmission unit to transmit the request signal. The present technology can be applied to a communication system.SELECTED DRAWING: Figure 9

Description

[Technical field]

[0001] The present technology relates to a wireless communication device, and more particularly to a wireless communication device that is capable of reducing processing time. [Background technology]

[0002] In IEEE802.11, which formulates standards for wireless LAN, the MIMO (Multiple Input Multiple Output) technology standardized in 802.11n enables both the base station (AP) and the terminal (STA) to transmit multiple pieces of data using multiple wireless modules and antennas.

[0003] By the way, in order to determine the transmission weight for MIMO communication, the channel condition of each communication link (how the signal transmitted by itself is received by the STA) is required. One method is Explicit Beamforming, which determines the transmission weight using a sounding process. The sounding process is a process in which the AP transmits a reference signal (known signal) of a known pattern and the STA transmits transmission weight information as a feedback signal (see Patent Document 1). [Prior art documents] [Patent documents]

[0004] [Patent Document 1] International Publication No. 2010 / 125635 Summary of the Invention [Problem to be solved by the invention]

[0005] In the above-mentioned sounding process, in order for the STA to transmit the transmission weight information to the AP side as a feedback signal, it must transmit a very large amount of information. Furthermore, when the AP obtains the transmission weight information from multiple STAs, the communication resources that can be allocated to the feedback signal of each STA are limited, so that the transmission time of the feedback signal increases significantly.

[0006] The present technology has been made in consideration of such circumstances, and is intended to make it possible to shorten the processing time. [Means for solving the problem]

[0007] A wireless communication device according to one aspect of the present technology includes a wireless transmission unit, and a communication control unit that causes the wireless transmission unit to cooperatively transmit a reference signal of a known pattern addressed to a wireless communication terminal with one or more other wireless communication devices, generates a request signal for the wireless communication terminal requesting a second measurement result of the reference signal that is simpler than a first measurement result, and causes the wireless transmission unit to transmit the request signal.

[0008] In one aspect of the present technology, a reference signal of a known pattern addressed to a wireless communication terminal is transmitted to the wireless transmission unit in cooperation with one or more other wireless communication devices. Then, a request signal is generated and transmitted to the wireless communication terminal, requesting a second measurement result of the reference signal that is simpler than a first measurement result. [Brief description of the drawings]

[0009] [Figure 1] FIG. 1 is a diagram illustrating an example of DL MU-MIMO technology. [Diagram 2] FIG. 1 is a diagram illustrating an example of an inter-AP coordination technique. [Diagram 3] FIG. 11 is a diagram illustrating an example of a sounding process. [Figure 4] 1 is a diagram illustrating a configuration example of a communication system according to an embodiment of the present technology. [Diagram 5] FIG. 2 is a block diagram showing a configuration example of a communication device. [Figure 6]FIG. 2 is a block diagram showing a configuration example of a communication terminal. [Figure 7] FIG. 11 is a diagram showing a sequence for explaining the overall processing of the communication system. [Figure 8] FIG. 13 is a diagram illustrating an example of the configuration of a Capability Exchange Frame. [Figure 9] A figure showing an example of the configuration of a STA List Exchange Frame. [Figure 10] FIG. 2 is a diagram showing an example of an EHT Sounding sequence according to the first embodiment of the present technology. [Figure 11] FIG. 1 is a diagram illustrating an example of a conventional communication resource usage situation. [Figure 12] FIG. 1 is a diagram illustrating an example of a usage status of communication resources according to the present technology. [Figure 13] FIG. 1 is a diagram illustrating an example of the format of an EHT NDP-A Frame. [Figure 14] FIG. 13 is a diagram illustrating an example of the format of a Short Feedback Request Frame. [Figure 15] FIG. 13 is a diagram illustrating an example of the format of a Short Feedback Response Frame. [Figure 16] FIG. 13 is a diagram illustrating an example of the format of an EHT BFRP Trigger Frame. [Figure 17] 13 is a flowchart illustrating EHT Sounding processing by the AP1. [Figure 18] 13 is a flowchart illustrating EHT Sounding processing by the AP2. [Figure 19] 11 is a flowchart illustrating an EHT Sounding process of a STA. [Figure 20] FIG. 11 is a diagram showing an example of an EHT Sounding sequence according to the second embodiment of the present technology. [Figure 21] FIG. 1 is a diagram illustrating an example of a usage status of communication resources according to the present technology. [Figure 22] 1 is a diagram showing features of first to fourth embodiments of the present technology; [Figure 23] FIG. 2 is a diagram conceptually illustrating Joint Tx and Coordinated Tx. [Figure 24] FIG. 13 is a diagram illustrating an example of an EHT Sounding sequence according to a third embodiment of the present technology. [Diagram 25] FIG. 13 is a diagram illustrating an example of an EHT Sounding sequence according to a fourth embodiment of the present technology. [Figure 26] FIG. 27 is a diagram showing an example of a sequence following FIG. 25 of EHT Sounding according to the fourth embodiment of the present technology. [Figure 27] A diagram showing an example format of a BFRP Trigger Request Frame. [Figure 28] FIG. 13 is a diagram illustrating an example of the format of a Feedback Request Frame. [Figure 29] 13 is a flowchart illustrating EHT Sounding processing by the AP1. [Diagram 30] FIG. 2 is a block diagram showing an example of the configuration of a computer. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0010] Hereinafter, an embodiment of the present technology will be described in the following order. 1. Background 2. System configuration and device configuration 3. First embodiment 4. Second embodiment 5. Third embodiment 6. Fourth embodiment 7.Other

[0011] <1. Background explanation> In IEEE802.11, which formulates the standard for wireless LAN, the MIMO (Multi-Input Multi-Output) technology standardized in 802.11n enables both the base station AP (Access Point) and the terminal STA (Station) to transmit multiple data using multiple wireless modules and antennas, thereby improving throughput and reliability.

[0012] MIMO technology has evolved with each new standard. For example, 802.11ac has developed DL (Down Link) MU-MIMO technology, in which an AP assigns multiple data to multiple STAs to perform multi-user communication. Also, 802.11ax has developed UL (Up Link) MU-MIMO technology, in which multiple STAs perform multi-user communication with an AP.

[0013] <dl mu-mimo技術> Figure 1 is a diagram showing an example of DL MU-MIMO technology.

[0014] In Figure 1, AP1, STA1, and STA2 are connected by wireless communication.

[0015] In the case of DL MU-MIMO, one AP1 transmits data to a plurality of STA1 and STA2. At this time, AP1 performs transmission weight processing so that signals addressed to other STAs do not reach each STA. As a result, STA1 and STA2 can extract and receive only the data addressed to themselves.

[0016] In IEEE802.11, the standard formulation of 802.11be, which is a successor standard to 802.11ax, has started since May 2019. One of the candidate technologies for 802.11be is the AP cooperation technology.

[0017] <AP cooperation technology> Figure 2 is a diagram showing an example of the AP cooperation technology.

[0018] In Figure 2, AP1, AP2, STA1, and STA2 are connected by wireless communication.

[0019] A plurality of AP1 and AP2 transmit data to a plurality of STA1 and STA2. As shown in Figure 2, basically, STA1 is more likely to receive data from AP1, which is closer to it than AP2, and STA2 is more likely to receive data from AP2, which is closer to it than AP1.

[0020] In the AP - to - AP cooperation technology shown in FIG. 2, the transmit weight processing described above with reference to FIG. 1 is performed by a plurality of APs, namely AP1 and AP2, in cooperation. For example, when AP1 sends data to STA1, AP1 controls the beam so that STA2 is not interfered with. Similarly, when AP2 sends data to STA2, AP2 controls the beam so that STA1 is not interfered with. As a result, AP1 and AP2 can transmit data simultaneously without interfering with each other, and throughput improvement can be achieved. Also, compared with FIG. 1, an advantage is expected in that the number of antennas per AP can be reduced.

[0021] Note that, for example, by a plurality of APs cooperating to perform data transmission to the same STA, it is also possible with the AP - to - AP cooperation technology to improve the reception quality of the STA.

[0022] By the way, in order to perform MIMO communication, an AP transmits a signal by performing appropriate signal processing (multiplication of transmit weights) on the signals emitted from each antenna. To determine this transmit weight, the channel status of each communication link (how the signal transmitted by itself is received at the STA) is required. As one method, there is Explicit Beamforming that determines the transmit weight using Sounding processing. Sounding processing is a process in which an AP transmits a reference signal (known signal) with a known pattern and the STA transmits the transmit weight information as a feedback signal.

[0023] <Sounding processing> FIG. 3 is a diagram showing an example of Sounding processing.

[0024] In FIG. 3, the Sounding processing in Explicit Beamforming defined in IEEE802.11ax is shown.

[0025] At time t1, AP1 transmits an NDP Announcement (hereinafter, NDP-A) frame to notify STA1 and STA2 that it will transmit an NDP (Null Data Packet) frame, which is a reference signal of a known pattern. At time t2, AP1 transmits the NDP frame.

[0026] Also, at time t3, when AP1 receives feedback signals from multiple STAs 1 and 2 at the same time, AP1 transmits a BFRP (Beamforming Report Poll) Trigger Frame for STA1 or STA2 to UL multiplex and transmit the feedback signals. The BFRP Trigger Frame specifies communication resources for each of STAs 1 and 2.

[0027] When the received NDP-A Frame contains information identifying itself, STA1 and STA2 estimate the channel state based on the reception state of the NDP Frame and calculate the transmission weight. There are several methods for calculating the transmission weight, but it is common to perform singular value decomposition of the channel matrix obtained from the reception state of the NDP Frame and use the obtained singular vector as the transmission weight.

[0028] At time t4, STA1 and STA2 use the communication resources specified in the BFRP Trigger Frame to compress the amount of information in the calculated transmission weights. STA1 and STA2 transmit the compressed information (hereinafter, transmission weight information) to the AP as a feedback signal. The AP that receives the feedback signal can obtain the transmission weight information calculated by the STA from the acquired feedback signal.

[0029] As described above, in order to feed back the transmission weight to the AP side, the STA needs to transmit a very large amount of information. In addition, when the AP obtains the transmission weight information from multiple STAs, the communication resources that can be allocated to the feedback signal of each STA are limited, so that the transmission time of the feedback signal increases significantly.

[0030] This reduction in sounding processing time is also essential for communication from one AP to multiple STAs. In particular, when considering a multi-AP environment or cooperation between APs, the number of transmitting antennas and the number of STAs tend to increase, and measures to reduce sounding processing time are more urgently needed.

[0031] Therefore, in this technology, after the AP transmits an NDP Frame of a known pattern, it first requests and obtains from the STA the second measurement result, which is simpler information than the transmission weight information (hereinafter also referred to as the first measurement result) measured from the reception status of the NDP Frame, and is measured from the reception status of the NDP Frame.

[0032] By acquiring the second measurement result, the AP can optimally determine information about the feedback signal, which includes the first measurement result and is acquired from the STA thereafter. The information about the feedback signal is, for example, the STA requesting the feedback signal, the amount of information in the feedback signal, and the communication resource of the feedback signal. As a result, according to the present technology, the time required for transmitting and receiving the feedback signal can be shortened.

[0033] <2. System configuration and device configuration> <Example of communication system configuration> FIG. 4 is a diagram illustrating a configuration example of a communication system according to an embodiment of the present technology.

[0034] In FIG. 4, solid arrows indicate that devices are connected to each other, and dashed arrows indicate that power is exchanged between the devices.

[0035] The communication system in Fig. 4 is configured by AP1 and AP2 being connected by wired communication or wireless communication. The communication system is also configured by STA1 and STA2 being connected to AP1 by wireless communication, and STA3 and STA4 being connected to AP2 by wireless communication. STA1 and STA2 connected to AP1 by wireless communication are referred to as STAs subordinate to AP1. STA3 and STA4 connected to AP2 by wireless communication are referred to as STAs subordinate to AP2.

[0036] Since STA2 and STA3 are close to APs other than the one they are connected to, it is expected that they will receive stronger received power from APs other than the one they are connected to than STA1 and STA4, which are farther away from APs other than the one they are connected to.

[0037] The system configuration is not limited to the example in Fig. 4, and may be any configuration as long as there are multiple APs with established connections and STAs are connected to each AP as surrounding terminals. Also, the positional relationship is not important as long as the above-mentioned positional relationship is satisfied.

[0038] <Example of communication device configuration> FIG. 5 is a block diagram illustrating an example of the configuration of a communication device.

[0039] A communication device 11 shown in FIG. 5 is a device that operates as an AP.

[0040] The communication device 11 includes a radio signal processing unit 21, radio communication units 22-1 and 22-2, and an inter-base station communication unit .

[0041] The wireless signal processing unit 21 controls communication with the AP and communication with the STA.

[0042] The radio signal processing unit 21 is made up of a communication control unit 31 , a radio interface unit 32 , and a data processing unit 33 .

[0043] The communication control unit 31 is composed of a CPU (Central Processing Unit), a ROM (Read Only Memory), a RAM (Random Access Memory), etc. The communication control unit 31 executes programs stored in the ROM or the like, and controls the overall operation of the communication device 11. The communication control unit 31 controls the wireless communication units 22-1 and 22-2 via the wireless interface unit 32, and sets communication resources, etc. The communication control unit 31 also performs a process of passing control information to be notified to other STAs to the data processing unit 33.

[0044] For example, after transmitting the NDP, the communication control unit 31 transmits a Short Feedback Request Frame, which is a request signal for requesting a Short Feedback Response Frame including the second measurement result of the NDP, to obtain the Short Feedback Response Frame from the STA.

[0045] Based on the acquired Short Feedback Response Frame, the communication control unit 31 determines the request destination of the feedback signal including the first measurement result, the amount of information of the feedback signal, and the communication resource of the feedback signal.

[0046] The wireless interface unit 32 performs analog conversion on the transmission signal generated by the data processing unit 33, converting the transmission signal from a digital signal to an analog signal. The wireless interface unit 32 also performs digital conversion on the reception signals acquired by the wireless communication units 22-1 and 22-2, converting the reception signals from an analog signal to a digital signal.

[0047] The data processing unit 33 generates a transmission signal based on the transmission data and the control information received from the communication control unit 31 , and outputs the generated transmission signal to the wireless interface unit 32 .

[0048] The data processing unit 33 demodulates the received signal converted by the wireless interface unit 32 and extracts the received data and control information. The data processing unit 33 outputs the extracted control information to the communication control unit 31, and outputs the extracted received data to a higher layer (not shown).

[0049] In addition, the data processing unit 33 receives control information and data supplied from the inter-base station communication unit 23 , and outputs them to the communication control unit 31 .

[0050] The wireless communication units 22-1 and 22-2 are equipped with antennas, and perform wireless communication with the STA based on communication resources set by the communication control unit 31. The wireless communication units 22-1 and 22-2 are referred to as the wireless communication unit 22 unless there is a particular need to distinguish between them. Note that the wireless communication unit 22 is not limited to two, and may include multiple (n>1) wireless communication units 22-1 to 22-n.

[0051] The wireless communication unit 22 comprises a wireless receiving unit 41 and a wireless transmitting unit .

[0052] The wireless receiving unit 41 performs RF processing on the wireless signal supplied from the antenna to generate a received signal, and outputs the received signal to the wireless interface unit 32.

[0053] The wireless transmitting unit 42 generates a wireless signal by performing RF processing on the transmission signal supplied from the wireless interface unit 32. The wireless transmitting unit 42 outputs the generated wireless signal to an antenna.

[0054] The electromagnetic waves received by the antenna are output as radio signals to the radio receiving unit 41. The antenna also emits the radio signals generated by the radio transmitting unit 42 as electromagnetic waves.

[0055] The inter-base station communication unit 23 performs notification processing or acquisition processing of control information and data necessary for cooperation between APs. The inter-base station communication unit 23 includes an antenna, and communication between APs may be wired or wireless. When communication between APs is wireless, the wireless communication unit 22 may be configured to perform the function of the inter-base station communication unit 23.

[0056] 5 shows an example in which the wireless signal processing unit 21 is configured as one IC, the IC configuration of the present technology is not limited to this. For example, the wireless interface unit may be mounted as a separate IC.

[0057] <Example of communication terminal configuration> FIG. 6 is a block diagram illustrating an example of the configuration of a communication terminal.

[0058] A communication terminal 51 shown in FIG. 6 is a device that operates as a STA.

[0059] The communication terminal 51 is made up of a radio signal processing unit 61, and radio communication units 62-1 and 62-2.

[0060] The wireless signal processing unit 61 controls communication with the AP and communication with the STA.

[0061] The wireless signal processing unit 61 is made up of a communication control unit 71 , a wireless interface unit 72 , and a data processing unit 73 .

[0062] The communication control unit 71 is composed of a CPU, a ROM, a RAM, etc. The communication control unit 71 executes a program stored in the ROM or the like, and controls the overall operation of the communication terminal 51. The communication control unit 71 controls the wireless communication units 62-1 and 62-2 via the wireless interface unit 72, and sets communication resources, etc. The communication control unit 71 also performs a process of passing control information to be notified to the AP and other STAs to the data processing unit 73.

[0063] For example, in response to a Short Feedback Request acquired from an AP, the communication control unit 71 measures the NDP to generate a Short Feedback Response including a second measurement result of the NDP, and passes the response to the data processing unit 73. The communication control unit 71 measures the NDP to generate transmission weight information, which is a first measurement result of the NDP, and passes the response to the data processing unit 73.

[0064] The wireless interface unit 72 performs analog conversion on the transmission signal generated by the data processing unit 33, converting the transmission signal from a digital signal to an analog signal. The wireless interface unit 72 also performs digital conversion on the reception signal acquired by the wireless communication units 62-1 and 62-2, converting the reception signal from an analog signal to a digital signal.

[0065] The data processing unit 73 generates a transmission signal based on the transmission data and control information received from the communication control unit 31 , and outputs the generated transmission signal to the wireless interface unit 72 .

[0066] The data processing unit 73 demodulates the received signal received from the wireless interface unit 72 and extracts the received data and control information. The data processing unit 73 outputs the extracted control information to the communication control unit 71 and outputs the extracted received data to a higher layer (not shown).

[0067] The wireless communication units 62-1 and 62-2 are equipped with antennas, and perform wireless communication with the AP based on communication resources set by the communication control unit 71. The wireless communication units 62-1 and 62-2 are referred to as the wireless communication unit 62 unless there is a particular need to distinguish between them. Note that the wireless communication unit 62 is not limited to two, and may include multiple (n>1) wireless communication units 62-1 to 62-n.

[0068] The wireless communication unit 62 is made up of a wireless receiving unit 81 and a wireless transmitting unit 82 .

[0069] The wireless receiving unit 81 performs RF processing and digital conversion on the wireless signal supplied from the antenna to generate a received signal. The wireless receiving unit 81 outputs the generated received signal to the data processing unit 73 via the wireless interface unit 72.

[0070] The wireless transmitting unit 82 generates a wireless signal by performing analog conversion and RF processing on the transmission signal made up of the packets generated by the data processing unit 73. The wireless transmitting unit 82 outputs the generated wireless signal to an antenna.

[0071] The electromagnetic waves received by the antenna are output as radio signals to the radio receiving unit 81. The antenna also emits the radio signals generated by the radio transmitting unit 82 as electromagnetic waves.

[0072] 6 shows an example in which the wireless signal processing unit 61 is configured as one IC, the IC configuration of the present technology is not limited to this. For example, the wireless interface unit may be mounted as a separate IC.

[0073] <3. First embodiment (example in which all transmission weight information of AP1 / AP2 is transmitted to AP1)> First, as a first embodiment, an example will be described in which AP1 / AP2 simultaneously transmit NDP-A Frames and NDP Frames, and transmit all of the transmission weight information of AP1 / AP2 to AP1.

[0074] <Overall processing sequence example> FIG. 7 is a diagram showing a sequence for explaining the overall processing of the communication system.

[0075] Step S1 is the APs Association Phase. In step S1, AP1 and AP2 establish a connection between cooperating APs as an APs Association. This establishes a connection relationship between AP1 and AP2. The connection may be established by wire or wireless. For example, in the case of wireless, the Association Process standardized by IEEE802.11 may be used as is. Note that capability information related to cooperative operation between APs may also be exchanged in this phase.

[0076] Step S2 is the Capability Exchange Phase. In step S2, AP1 and AP2 exchange capability information between AP and STA as a capability exchange. Here, AP1 and AP2 exchange capability information, which is information indicating functions and capabilities, with the subordinate STAs. In the case of this technology, information indicating whether or not it is possible to exchange information on short feedback is included in the capability information.

[0077] Step S3 is the STA List Exchange Phase. In step S3, AP1 and AP2 exchange information (such as addresses and AID information) about the subordinate STAs (connected to themselves) as the STA List Exchange. This allows, for example, AP1 to specify STA3 and STA4 other than the connection destination in the NDP-A Frame and start the next Sounding Phase. In the case of this technology, the information about the STAs includes information indicating whether or not it is possible to exchange information about Short Feedback in the Capability information.

[0078] Step S4 is an EHT (Enhanced High Throughput) Sounding Phase. In step S4, AP1, AP2, and multiple STAs perform a Sounding process assuming a multiple AP environment as EHT Sounding. In step S4, transmission weights are calculated by the multiple STAs, and transmission weight information indicating the transmission weights is transmitted to AP1. Details of the EHT Sounding Phase will be described later.

[0079] Step S5 is a Tx Weight Exchange Phase. In step S5, AP1 and AP2 exchange feedback signals acquired from each STA as a Tx Weight Exchange. That is, the transmission weight information acquired in step S4 is exchanged by AP1 and AP2. For example, in the first embodiment, since each STA feeds back the transmission weight information to AP1, in step S5, AP1 needs to notify AP2 of the transmission weight information of AP2.

[0080] Step S6 is a coordinated transmission phase. In step S6, AP1 and AP2 perform coordinated transmission of data to multiple STAs based on the transmission weight information, and receive ACKs, which are receipt confirmations, transmitted from the multiple STAs. In step S6, coordinated transmission may be performed to multiple STAs in order to reduce interference experienced by other STAs, or coordinated transmission may be performed to one STA in order to improve reception quality.

[0081] The order of each phase does not have to be as shown in Fig. 7. For example, the APs Association Phase may be performed after the Capability Exchange Phase. Also, each phase does not necessarily have to be separated. For example, the APs Association Phase and the STA List Exchange Phase may be performed simultaneously.

[0082] Also, the frequency of each phase is not particularly limited. For example, the STA List Exchange Phase may be executed periodically, or may be performed when there is a change (new connection or disconnection) in the STAs under each AP.

[0083] <Configuration Example of Capability Exchange Frame> FIG. 8 is a diagram showing a configuration example of a Capability Exchange Frame.

[0084] The Capability Exchange Frame in FIG. 8 is exchanged in the Capability Exchange Phase. The Capability Exchange Frame includes fields such as Frame Control, Duration, and Short Feedback Capability. Note that the hatching in FIG. 8 indicates that the field contains information according to this technology. The same applies to the subsequent figures.

[0085] The Frame Control field contains information indicating that this frame is a frame containing Capability information exchanged between APs.

[0086] The Duration field contains information regarding the length of this frame.

[0087] The Short Feedback Capability field contains Short Feedback Capability information. The Short Feedback Capability information is information indicating whether the AP and STA can send and receive Short Feedback Request Frames and Short Feedback Response Frames.

[0088] For a STA with the "Short Feedback Capability" field being "No", the Short Feedback Request Frame is not transmitted, and optimization such as communication resources for the feedback signal is not performed. Note that this Capability information may include information indicating whether the Short Feedback Request Frame and the Short Feedback Response Frame can be transmitted and received for each of the specified measurement conditions (e.g., received power and channel correlation value) described later.

[0089] <Configuration Example of STA List Exchange Frame> Figure 9 is a diagram showing a configuration example of the STA List Exchange Frame.

[0090] The STA List Exchange Frame in Figure 9 is exchanged in the STA List Exchange Phase. The STA List Exchange Frame includes fields such as Frame Control, Duration, and STA n Info.

[0091] The Frame Control field includes information indicating that this frame is a frame containing Capability information exchanged between APs.

[0092] The Duration field includes information regarding the length of this frame.

[0093] The STA n Info field includes various information regarding the STA connected to itself. The STA n Info field includes, for example, AID information and Short Feedback Capability information.

[0094] The AID information is information indicating the destination of the STA. Note that the information indicating the destination is not limited to the AID information, and may be the STA's ID information, the MAC address, or a special identification number defined only between the AP and the STA.

[0095] The Short Feedback Capability information indicates the Short Feedback Capability information of each STA collected in the Capability Exchange Phase.

[0096] Note that the filed of STA n Info. may contain other information about the STA, for example, the number of transmission antennas and information about the available transmission bandwidth.

[0097] <Example of the sequence of the EHT Sounding Phase> FIG. 10 is a diagram showing an example of the sequence of the EHT Sounding Phase of the present technology.

[0098] In FIG. 10, an example is shown in which after AP1 and AP2 simultaneously transmit NDP Frames, AP1 transmits Short Feedback Request Frames (Short Req. in FIG. 10) to all of STA1 to STA4.

[0099] At time T01, AP1 transmits a MAP Trigger, which is a cooperation request signal for requesting cooperation transmission to AP2. The MAP Trigger describes information for instructing AP2 on a determination method and a determination threshold for obtaining measurement result information regarding the measurement results of the NDP included in the Short Feedback Request Frame.

[0100] AP2 generates an EHT NDP-A Frame and an NDP Frame based on the content described in the MAP Trigger. The EHT NDP-A Frame is a pre-notification signal for pre-notifying the transmission of the NDP-Frame.

[0101] At time T02, AP1 and AP2 each transmit an EHT NDP-A frame. By transmitting the same NDP-A frame simultaneously from AP1 and AP2, each STA receives it.

[0102] At time T03, AP1 and AP2 each transmit an NDP frame of a known pattern. The NDP frame has a different coding pattern of the LTF in the preamble for each transmitting antenna of AP1 / AP2. This allows each STA to separate the signals transmitted by each transmitting antenna of each AP and estimate the channel conditions. The coding pattern of the LTF may be one defined by an existing standard (e.g., HE-LTF) or one that is newly defined (e.g., EHT-LTF).

[0103] At time T04, AP1 transmits a Short Feedback Request Frame to STA1 to STA4.

[0104] At time T05, STA1 to STA4 receive a Short Feedback Request Frame from AP1, and then transmit a Short Feedback Response Frame (Short Resp. in FIG. 10) including a second measurement result based on the reception status of the NDP Frame transmitted from AP1 and AP2. The second measurement result requires less information and calculations than the transmission weight information, which is the first measurement result.

[0105] AP1 optimizes the amount of information and communication resources of the feedback signal, as information about the feedback signal, based on information about the second measurement result of the Short Feedback Response Frame acquired from STA1 to STA4.

[0106] For example, AP1 requests STA1 to STA4 for a second measurement result indicating whether or not the difference in the received power of the NDP Frame between the AP connected to itself and the other APs is less than a threshold by transmitting a Short Feedback Request Frame. AP1 obtains the requested second measurement result in a Short Feedback Response Frame transmitted from STA1 to STA4.

[0107] In this case, AP1 determines that cooperative communication between AP1 and AP2 can be effective because STA2 and STA3 are close to both APs and there is no difference in received power as shown in Fig. 4. On the other hand, STA1 and STA4 are far from APs other than the one they are connected to and there is a large difference in received power, so AP1 determines that cooperative transmission between AP1 and AP2 cannot be effective.

[0108] At time T06, AP1 generates an EHT BFRP Trigger Frame based on the above-mentioned determination result and transmits it to STA1 to STA4. AP1 induces the transmission of a feedback signal by transmitting the EHT BFRP Trigger Frame to STA1 to STA4. The EHT BFRP Trigger Frame is an inducement signal that induces STA1 to STA4 to transmit a feedback signal including transmission weight information, which is the first measurement result.

[0109] At this time, in the EHT BFRP Trigger Frame, AP1 specifies more communication resources for STA2 and STA3, which feed back transmission weight information to both APs, than communication resources for STA1 and STA4, which feed back only transmission weight information to the connected AP.

[0110] At time T07, STA1 transmits a feedback signal including transmission weight information for AP1 based on the EHT BFRP Trigger Frame. STA2 and STA3 transmit feedback signals including transmission weight information for AP1 and transmission weight information for AP2 based on the EHT BFRP Trigger Frame. STA4 transmits a feedback signal including transmission weight information for AP2 based on the EHT BFRP Trigger Frame.

[0111] As described above, AP1 is able to grasp the reception status of each STA in advance and determine whether or not cooperative communication can be effective, thereby controlling the amount of information in the feedback signal of each STA and the communication resources of the feedback signal by transmitting an EHT BFRP Trigger Frame.

[0112] <Advantages of the First Embodiment> Fig. 11 is a diagram showing an example of a usage state of a conventional communication resource for comparison with the usage state of a communication resource of the present technology. Fig. 12 is a diagram showing an example of a usage state of a communication resource of the present technology.

[0113] 11 and 12 show communication resources for each STA in the frequency band used.

[0114] In a conventional communication system, as shown in Fig. 11, STA1 to STA4 equally use communication resources of a frequency band, for example, each of the bandwidths a. In contrast, in the communication system of the present technology, STA1 and STA4, which are far from APs other than the connection destination, only transmit transmission weight information to the connection destination AP.

[0115] Therefore, as shown in FIG. 12, the communication resources in the frequency bands used by STA1 and STA4 only send transmission weight information for AP1 or AP2, and thus are specified as a bandwidth b (b < a) that is narrower than the bandwidth a in FIG. 11. On the other hand, as shown in FIG. 12, the communication resources in the frequency bands used by STA2 and STA3 send transmission weight information for AP1 and transmission weight information for AP2, and thus are specified as a bandwidth c (a < c) that is wider than the bandwidth a in FIG. 11.

[0116] From this, the time taken to transmit the feedback signal can be shortened as a whole.

[0117] <Example format of EHT NDP-A Frame> FIG. 13 is a diagram showing an example format of an EHT NDP-A Frame.

[0118] The EHT NDP-A Frame consists of fields of Frame Control, Duration, RA, TA, Sounding Dialog Token, Multi-AP NDP Info, AP Info 1 to AP Info n, STA Info 1 to STA Info n, and FCS.

[0119] The field of Frame Control contains information indicating that this frame is an EHT NDP-A Frame.

[0120] The field of Duration contains information regarding the length of this frame.

[0121] The field of RA contains destination address information. The field of TA contains source address information.

[0122] The field of Sounding Dialog Token contains NDP information and an identification number for a series of processes.

[0123] The Multi-AP NDP Info field includes information such as the NDP transmission method when multiple APs transmit NDP in cooperation and perform channel estimation, information about short feedback, and the method of transmitting a feedback signal.

[0124] Specifically, the Multi-AP NDP Info field includes information such as Num.Of AP, NDP Tx Info, Short Feedback Enabler, Short Feedback Condition, Short Feedback Threshold, and Feedback Type.

[0125] The Num.Of AP is information indicating the number of cooperating APs.

[0126] The NDP Tx Info is information such as the NDP transmission method (simultaneous or separate), the transmission stream ID, and the transmission time.

[0127] The Short Feedback Enabler is information indicating whether or not to notify short feedback.

[0128] The short feedback condition is information indicating the measurement conditions that serve as a reference when performing short feedback, such as the difference in received power between APs and the cross-correlation value of the estimated channel.

[0129] The Short Feedback Threshold is information indicating a reference value for determining whether or not to return 1 in the Short Feedback for the condition specified in the Short Feedback Condition. As the reference value, an absolute threshold and a value relative to the NDP transmitted from itself are specified. In addition, the threshold itself does not have to be specified in this field, and a calculation method of the threshold may be specified, for example, by calculating the threshold of the NDP reception power value transmitted from other APs based on the NDP reception power value transmitted from itself. Note that the Short Feedback Threshold is information that may not be necessary depending on the configuration of the Response Frame.

[0130] The Feedback Type includes information indicating whether the STA returns all measurement result information to the same AP (first embodiment) or returns each measurement result information to each AP (second embodiment). Note that the Feedback Type, the above-mentioned Num.Of AP, Short Feedback Condition, etc. are unnecessary information when they are uniquely determined by the standard.

[0131] AP Info includes information about the AP cooperating in transmitting the NDP Frame (AP identifier, measurement bandwidth, amount of feedback information, etc.). It is also possible that information about the AP itself transmitting the Frame of this technology is included here. The number of AP Infos is specified by the Num. Of AP mentioned above.

[0132] The STA Info includes information about the STA that receives the NDP Frame and is to be measured (such as the STA identifier, measurement bandwidth, and amount of feedback information).

[0133] The FCS includes an error correcting code.

[0134] In order for this frame to be transmitted simultaneously between APs, AP1 must notify AP2 of the contents of this frame in advance, or the necessary information must be included in the MAP Trigger before it is transmitted.

[0135] Note that Short Feedback Enabler / Short Feedback Condition / Short Feedback Threshold may be included in the AP Info. Also, for example, the MAP Trigger Frame transmitted by AP1 may include these three pieces of information and be directly transmitted to each STA as the EHT NDP-A Frame of AP2.

[0136] <Example format of Short Feedback Request Frame> FIG. 14 is a diagram showing an example format of the Short Feedback Request Frame. Note that descriptions of the same fields and configurations as those of the other frames described above are omitted. The same applies to the subsequent figures.

[0137] The Short Feedback Request Frame consists of fields of Frame Control, Duration, RA, TA, Common Info, User Info, Padding, and FCS.

[0138] The field of Frame Control contains information indicating that this frame is a Short Feedback Request Frame.

[0139] The field of Common Info contains information common to all STAs that transmit this frame. In this technology, it is characterized in that the Trigger Type in the Common Info indicates that this frame is a Short Feedback Request Frame (if the same specification can be made in the Frame Control, this information may not be necessary).

[0140] The User Info includes the identifier (STA ID) of the STA that requests the Response, the communication resource (Resource Info) of the Short Feedback Response Frame, and the information necessary for transmitting other Short Feedback Response Frames.

[0141] <Example format of Short Feedback Response Frame> Figure 15 is a diagram showing an example format of the Short Feedback Response Frame.

[0142] The Short Feedback Response Frame consists of fields of Frame Control, Duration, RA, TA, Short Feedback Result Info., and FCS.

[0143] The field of Frame Control contains information indicating that this frame is a Short Feedback Response Frame.

[0144] The field of Short Feedback Result Info. contains information on whether the measurement result specified in the "Short Feedback Condition" within the NDP-A Frame exceeds the value of the "Short Feedback Threshold" (Result), and the measured value (Value). Note that both Result and Value may be included, or only one of them may be included.

[0145] <Example format of EHT BFRP Trigger Frame> Figure 16 is a diagram showing an example format of the EHT BFRP Trigger Frame.

[0146] The EHT BFRP Trigger Frame consists of the following fields: Frame Control, Duration, RA, TA, Common Info, User Info, Padding, and FCS.

[0147] The Frame Control field contains information indicating that this frame is an EHT BFRP Trigger Frame.

[0148] The Common Info field contains information common to all STAs that transmit this frame. This technology is characterized in that the Trigger Type in Common Info indicates that this frame is an EHT BFRP Trigger Frame (if a similar designation is possible in Frame Control, this information is not necessary).

[0149] The User Info includes an identifier (STA ID) of the STA requesting a response, a communication resource for the feedback signal (Resource Info), the content of the feedback (Feedback Content ID), and other information required for transmitting the feedback signal.

[0150] The feedback content here means information indicating whether the measurement results to be fed back are only the results of the connected AP or also include results from other APs.

[0151] <Device Operation> FIG. 17 is a flowchart illustrating the EHT Sounding process of the wireless communication device 11-1 operating as the AP1.

[0152] In step S51, the communication control unit 31 of the wireless communication device 11-1 determines whether or not to transmit the NDP in cooperation with the AP 2. If it is determined in step S51 that the NDP is not to be transmitted in cooperation with the AP 2, the process proceeds to step S52.

[0153] In step S52, the communication control unit 31 generates an existing NDP-A Frame transmission or an EHT NDP-A Frame (FIG. 13) with Num Of AP=1, and causes the wireless transmission unit 41 to transmit it.

[0154] In step S53, the communication control unit 31 generates an NDP Frame and causes the wireless transmission unit 41 to transmit it.

[0155] In step S54, the communication control unit 31 generates a BFRP Trigger Frame and transmits it to the wireless transmission unit 41. Note that if there is only one STA, it is not necessary to transmit the BFRP Trigger Frame.

[0156] The STA that has received the BFRP Trigger Frame and determined that it is necessary to send a feedback signal based on the BFRP Trigger Frame transmits the feedback signal. In step S55, the wireless receiving unit 42 receives the feedback signal.

[0157] On the other hand, if it is determined in step S51 that the NDP Frame is to be transmitted in cooperation with the AP2, the process proceeds to step S56.

[0158] In step S56, the communication control unit 31 generates a MAP Trigger Frame addressed to the AP2 and transmits it to the inter-base station communication unit 23. This starts the EHT Sounding process. Note that the determination of the AP1 that starts the EHT Sounding process is not particularly limited in the present technology, and may be, for example, a fixed AP or an AP that has acquired the transmission right.

[0159] In step S57, the communication control unit 31 generates an EHT NDP-A Frame (FIG. 13) and causes the wireless transmission unit 41 to transmit it. The EHT NDP-A Frame may include not only information about the subordinate STAs of the own unit, but also information about the subordinate STAs of AP2. It is assumed that information about the subordinate STAs of each AP has been exchanged in advance in the STA List Exchange Frame of FIG. 9.

[0160] In step S58, the communication control unit 31 generates an NDP Frame and causes the wireless transmission unit 41 to transmit it.

[0161] In step S59, the communication control unit 31 determines whether or not to request short feedback. If it is determined in step S59 that short feedback is requested, the process proceeds to step S60.

[0162] In step S60, the communication control unit 31 generates a Short Feedback Request Frame (FIG. 14) addressed to all the STAs that have transmitted the NDP Frame, and causes the wireless transmission unit 41 to transmit the Short Feedback Request Frame (FIG. 14).

[0163] The STA that receives the Short Feedback Request Frame transmits a Short Feedback Response Frame (FIG. 15) (step S156 in FIG. 19, which will be described later). At this time, by using the configuration of the Trigger Frame defined in 802.11ax, the STA can transmit the Short Feedback Response Frame using UL MU-MIMO technology (UL OFDMA, etc.).

[0164] The Short Feedback Response Frame according to the UL MU-MIMO technology may be received from all STAs in multiple batches. In this case, the AP transmits the Short Feedback Request Frame for each batch.

[0165] In step S61, the wireless receiving unit 42 receives a Short Feedback Response Frame. Upon receiving the Short Feedback Response Frame, the process proceeds to step S62.

[0166] If it is determined in step S59 that short feedback is not requested, the process proceeds to step S62.

[0167] In step S62, the communication control unit 31 determines the STA requesting feedback, the amount of information in the feedback signal, and communication resources based on information obtainable from the short feedback response frame.

[0168] In step S63, the communication control unit 31 generates an EHT BFRP Trigger Frame including the information determined in step S62, and causes the wireless transmission unit 41 to transmit the generated EHT BFRP Trigger Frame (FIG. 16).

[0169] The STA that receives the EHT BFRP Trigger Frame and determines that it is necessary to send a feedback signal based on the EHT BFRP Trigger Frame transmits the feedback signal (step S159 in FIG. 19, which will be described later). In step S64, the wireless receiving unit 42 receives the feedback signal.

[0170] If a feedback signal is received in step S55 or S64, the EHT Sounding process of the AP1 ends.

[0171] In the first embodiment, it is assumed that the communication resources of each STA are determined based on the acquired Short Feedback Response Frame, but it is also possible for the AP1 to receive feedback signals from the STAs in multiple times by transmitting the EHT BFRP Trigger Frame multiple times. The combination of STAs in each time and the information to be specified can also be calculated and obtained by the AP1 from the Short Feedback Response Frame.

[0172] FIG. 18 is a flowchart illustrating the EHT Sounding process of the wireless communication device 11-2 operating as the AP2.

[0173] In step S101, the inter-base station communication unit 23 of the wireless communication device 11-2 receives a MAP Trigger Frame transmitted from the AP1.

[0174] In step S102, the communication control unit 31 waits for a specified time period written in the MAP Trigger Frame.

[0175] In step S103, the communication control unit 31 generates an EHT NDP-A Frame (FIG. 13) and causes the wireless transmission unit 41 to transmit it.

[0176] In step S104, the communication control unit 31 generates an NDP Frame and causes the wireless transmission unit 41 to transmit it.

[0177] In step S105, the communication control unit 31 determines whether or not there is a short feedback instruction in the MAP Trigger Frame from the AP 1. If it is determined in step S105 that there is a short feedback instruction, the process proceeds to step S106.

[0178] In step S106, the communication control unit 31 generates a Short Feedback Request Frame (FIG. 14), and after waiting for a designated time, causes the wireless transmission unit 41 to transmit the Short Feedback Request Frame (FIG. 14).

[0179] The STA that has received the Short Feedback Request Frame transmits a Short Feedback Response Frame (FIG. 15) (step S156 in FIG. 19, which will be described later). In step S107, the wireless receiving unit 42 receives the Short Feedback Response Frame. After receiving the Short Feedback Response Frame, the process proceeds to step S108.

[0180] If it is determined in step S105 that there is no instruction for short feedback, the process proceeds to step S108.

[0181] In step S108, the communication control unit 31 determines whether or not there is a feedback instruction in the MAP Trigger Frame from the AP 1. If it is determined that there is a feedback instruction, the process proceeds to step S109.

[0182] In step S109, the communication control unit 31 determines the STA requesting feedback, the amount of information in the feedback signal, and communication resources.

[0183] In step S110, the communication control unit 31 generates an EHT BFRP Trigger Frame based on the information determined in step S109, and causes the wireless transmission unit 41 to transmit the generated EHT BFRP Trigger Frame (FIG. 16). Note that the AP2 may start transmitting the EHT BFRP Trigger Frame after waiting a fixed time (such as SIFS) after completion of reception of the feedback signal from the AP2. However, if the end time of reception of the feedback signal from AP1 fluctuates and is unknown, the UE may receive a MAP Trigger Frame or a similar frame from AP1 again and start transmitting an EHT BFRP Trigger Frame.

[0184] The STA that receives the EHT BFRP Trigger Frame and determines that it is necessary to send a feedback signal based on the EHT BFRP Trigger Frame transmits the feedback signal (step S159 in FIG. 19, which will be described later). In step S111, the wireless receiving unit 42 receives the feedback signal.

[0185] If a feedback signal is received in step S111, the EHT Sounding process of the AP1 ends.

[0186] The difference between the processing of AP2 in FIG. 18 and the processing of AP1 in FIG. 17 is that AP2 decides whether to send a Short Feedback Request Frame or an EHT BFRP Trigger Frame based on the information (NDP Tx Info., Feedback Type, etc.) included in the MAP Trigger sent from AP1.

[0187] Note that the process in Figure 18 is merely an example in which AP1 initiates cooperative operation by first acquiring the transmission right, and so if AP2 is in a situation in which it can initiate cooperative operation, AP2 will perform the process in Figure 17.

[0188] Furthermore, when there are three or more APs in the communication system, for example, AP3, AP4, etc., the processing of AP3 and AP4 is the same as that of AP2 described above with reference to FIG.

[0189] FIG. 19 is a flowchart illustrating the EHT Sounding process of the wireless communication device 12 operating as any one of the STAs STA1 to STA4.

[0190] In steps S52 and S57 in FIG. 17 and step S103 in FIG. 18, AP1 and AP2 transmit EHT NDP-A Frames (FIG. 13).

[0191] In step S151, the wireless receiving unit 81 of the STA receives the EHT NDP-A Frame.

[0192] In step S152, the communication control unit 71 determines whether or not its own ID is specified in the STA Info of the EHT NDP-A Frame. If it is determined in step S152 that its own ID is specified in the STA Info of the EHT NDP-A Frame, the process proceeds to step S153.

[0193] In steps S53 and S58 in Fig. 17 and step S104 in Fig. 18, AP1 and AP2 transmit NDP Frames. In step S153, the communication control unit 71 receives the NDP Frame, estimates the channel state based on the reception state of the NDP Frame, and calculates the transmission weight.

[0194] If necessary, in step S60 in FIG. 17 and step S106 in FIG. 18, AP1 and AP2 transmit a Short Feedback Request Frame (FIG. 14).

[0195] In step S154, the communication control unit 71 determines whether or not a Short Feedback Request Frame has been received. If it is determined in step S154 that a Short Feedback Request Frame has been received, the process proceeds to step S155.

[0196] In step S155, the communication control unit 71 determines whether or not its own ID is specified in the User Info of the Short Feedback Request Frame. If it is determined in step S155 that its own ID is specified in the User Info of the Short Feedback Request Frame, the process proceeds to step S156.

[0197] In step S156, the communication control unit 71 generates a Short Feedback Response Frame (FIG. 15) using the communication resource specified in the User Info of the Short Feedback Request Frame, and causes the wireless transmission unit 82 to transmit it. Note that the information and the determination method to be included in the Short Feedback Response Frame are preferably included in the EHT NDP-A Frame received in step S151. However, they may be included in the Short Feedback Request Frame.

[0198] After transmitting the Short Feedback Response Frame, the process proceeds to step S157.

[0199] Similarly, if it is determined in step S154 that a Short Feedback Request Frame has not been received, the process proceeds to step S157. Also, if it is determined in step S155 that the user ID of the Short Feedback Request Frame is not specified in the User Info, the process proceeds to step S157.

[0200] In step S63 in FIG. 17, AP1 transmits an EHT BFRP Trigger Frame (FIG. 16).

[0201] In step S157, the communication control unit 71 judges whether or not an EHT BFRP Trigger Frame has been received. If it is judged in step S157 that an EHT BFRP Trigger Frame has been received, the process proceeds to step S158.

[0202] In step S158, the communication control unit 71 judges whether or not its own ID is specified in the User Info of the EHT BFRP Trigger Frame. If it is judged in step S158 that its own ID is specified in the User Info of the EHT BFRP Trigger Frame, the process proceeds to step S159.

[0203] In step S159, the communication control unit 71 generates a feedback signal including the specified information by using the communication resource specified in the User Info of the EHT BFRP Trigger Frame, and causes the wireless transmission unit 82 to transmit the generated feedback signal. The specified information here refers to the information specified in the "Feedback Content ID" shown in Fig. 16, and in the first embodiment, this means whether or not to include transmission weight information of either or both of AP1 and AP2 in the feedback signal.

[0204] If it is determined in step S157 that the EHT BFRP Trigger Frame has not been received, or if it is determined in step S158 that the STA's own ID is not specified in the User Info of the EHT BFRP Trigger Frame, the EHT Sounding process of the STA ends.

[0205] Also, if it is determined in step S152 that the STA's own ID is not specified in the STA Info of the EHT NDP-A frame, the EHT Sounding process of the STA also ends.

[0206] Note that since the EHT BFRP Trigger Frame may be transmitted multiple times, it is desirable for the STA to store the calculated and acquired transmission weight information for a certain period of time.

[0207] Also, regarding whether the Short Feedback Request Frame is transmitted, the information to be responded to in the Short Feedback Response Frame, whether multiple APs transmit the NDP Frame simultaneously, etc., as shown in FIG. 13, they are all included in the EHT NDP-A Frame. Therefore, when the STA receives the EHT NDP-A Frame, it can perform preparations for the EHT sounding process in advance.

[0208] <4. Second Embodiment (Example of Transmitting the Transmission Weight Information of AP1 to AP1 and the Transmission Weight Information of AP2 to AP2)> Next, as a second embodiment, an example in which AP1 / AP2 simultaneously transmits the NDP-A Frame and the NDP Frame, and transmits the transmission weight information of AP1 to AP1 and the transmission weight information of AP2 to AP2 will be described.

[0209] Note that since the overall sequence in the second embodiment is basically the same as the overall sequence in the first embodiment, the description thereof will be omitted.

[0210] <Example of EHT Sounding Sequence> FIG. 20 is a diagram showing an example of the EHT Sounding sequence of the present technology.

[0211] In FIG. 20, an example is shown in which after AP1 and AP2 simultaneously transmit the NDP Frame, AP1 and AP2 each transmit the Short Feedback Request Frame to all STAs 1 to STA4. Note that the details of the process are basically the same as those in FIG. 10 and will be omitted as appropriate.

[0212] At time A01, AP1 transmits a MAP Trigger to AP2.

[0213] AP2 generates an EHT NDP-A Frame and an NDP-Frame based on the contents described in the MAP Trigger.

[0214] At time A02, AP1 and AP2 each transmit an NDP-A frame. By transmitting the same NDP-A frame simultaneously from AP1 and AP2, each STA receives it.

[0215] At time A03, AP1 and AP2 each transmit an NDP Frame of a known pattern. The NDP Frame has a different coding pattern of HE-LTF in the preamble for each transmitting antenna of AP1 / AP2. This allows each STA to separate the signals transmitted by each transmitting antenna of each AP and estimate the channel conditions. The coding pattern of the LTF may be one defined by an existing standard (e.g., HE-LTF) or one newly defined (e.g., EHT-LTF).

[0216] At time A04, AP1 transmits a Short Feedback Request Frame (FIG. 15) to STA1 to STA4.

[0217] At time A05, after receiving the Short Feedback Request Frame from the AP1, the STA1 to STA4 generate a Short Feedback Response Frame (FIG. 14) based on the reception status of the NDP Frame transmitted from the AP1, and transmit the Short Feedback Response Frame to the AP1.

[0218] At time A06, AP2 transmits a Short Feedback Request Frame to STA1 to STA4.

[0219] At time A07, after receiving the Short Feedback Request Frame from the AP2, the STA1 to STA4 generate a Short Feedback Response Frame based on the reception status of the NDP Frame transmitted from the AP2, and transmit the Short Feedback Response Frame to the AP2.

[0220] At time A08, the AP1 optimizes the amount of information in the feedback signal and communication resources based on the information in the Short Feedback Response Frame acquired from the STA1 to STA4. The AP1 induces the transmission of the feedback signal by transmitting an EHT BFRP Trigger Frame to the STA1 to STA3.

[0221] At time A09, STA1 to STA3 transmit feedback signals including transmission weight information for AP1 to AP1 based on the EHT BFRP Trigger Frame.

[0222] At time A10, AP2 optimizes the amount of information in the feedback signal and communication resources based on the information in the Short Feedback Response Frame acquired from STA1 to STA4. AP2 induces the transmission of a feedback signal by transmitting an EHT BFRP Trigger Frame to STA2 to STA4. Note that AP2 may start transmitting an EHT BFRP Trigger Frame after waiting a fixed time (such as SIFS) after completion of reception of the feedback signal from AP1. However, if the end time of reception of the feedback signal from AP1 fluctuates and is unknown, AP2 may receive a MAP Trigger Frame or a similar frame from AP1 again and start transmitting an EHT BFRP Trigger Frame.

[0223] At time A11, STA2 to STA4 transmit feedback signals including transmission weight information for AP2 to AP2 based on the EHT BFRP Trigger Frame.

[0224] Note that all of the frame configurations of the second embodiment can be corresponded to the frame configurations described in the first embodiment. For example, the operation of the second embodiment can be specified by "Feedback Type" in FIG. 13.

[0225] <Effect of the Second Embodiment> FIG. 21 is a diagram showing an example of the usage status of communication resources of the present technology.

[0226] In FIG. 21, the communication resources for each STA in the frequency band to be used are shown.

[0227] In the conventional communication system, as described above with reference to FIG. 11, STA1 to STA4 equally used the communication resources in the frequency band, for example, by bandwidth a each. In contrast, in the communication system of the present technology, STA4 that is far from AP1 does not send the transmission weight information to AP1.

[0228] Therefore, the communication resources in the frequency band used by STA1 to STA3 are specified as a bandwidth d (a < d) wider than the bandwidth a in FIG. 11, as shown in FIG. 21.

[0229] Also, STA1 that is far from AP2 does not send the transmission weight information to AP2.

[0230] Therefore, the communication resources in the frequency band used by STA2 to STA4 are specified as a bandwidth d (a < d) wider than the bandwidth a in FIG. 11, similar to the example in FIG. 21.

[0231] From this, the time taken for transmitting the feedback signal can be shortened as a whole.

[0232] As described above, in this technology, between the transmission of an NDP Frame of a known pattern and the reception of a feedback signal which is the first measurement result, information is exchanged between a Short Feedback Request which is a request signal for a second measurement result and a Short Feedback Response which is the second measurement result.

[0233] In this way, it becomes possible to optimally allocate subsequent feedback signal request destinations and feedback signal communication resources.

[0234] FIG. 22 is a diagram showing the features of the first and second embodiments described above, and the third and fourth embodiments which will be described below.

[0235] 22, "AP1+AP2 transmission weight information" refers to transmission weight information calculated by regarding the NDP Frames transmitted from AP1 and AP2 as signals transmitted from the same AP. Also, "AP1 transmission weight information" refers to transmission weight information calculated only from the NDP Frame transmitted from AP1.

[0236] As shown in Fig. 22, the content of the feedback signal in the first embodiment is the transmission weight information of AP1+AP2 or the transmission weight information of the connected AP. Which is transmitted is determined based on the exchange of Short Feedback Request / Short Feedback Response (hereinafter also referred to as Short Req. / Resp.).

[0237] Moreover, the transmission destination of the feedback signal in the first embodiment is one of the APs.

[0238] The content of the feedback signal in the second embodiment is transmission weight information of AP1+AP2 or transmission weight information of the connected AP. Which is transmitted is determined based on the exchange of Short Req. / Resp.

[0239] Moreover, the destination of the feedback signal in the second embodiment is the connected AP.

[0240] The content of the feedback signal in the third embodiment is transmission weight information of AP1+AP2 or transmission weight information of AP1+transmission weight information of AP2. Which one is transmitted is determined based on the exchange of Short Req. / Resp.

[0241] Moreover, the transmission destination of the feedback signal in the third embodiment is one of the APs.

[0242] The content of the feedback signal in the fourth embodiment is transmission weight information of AP1+AP2.

[0243] In the fourth embodiment, the destination of the feedback signal is the connected AP or another AP, and which AP the signal is sent to is determined based on an exchange of Short Req. / Resp.

[0244] <5. Third embodiment (Example of transmitting transmission weight information based on a cooperative method)> In the first embodiment, as described above with reference to FIG. 22, an example has been described in which a feedback signal (transmission weight information of AP1+AP2 or transmission weight information of a connected AP) is transmitted.

[0245] Next, in the third embodiment, an example in which a feedback signal (either transmission weight information of AP1+AP2 or transmission weight information of AP1+transmission weight information of AP2) is transmitted will be described.

[0246] Whether the content of the feedback signal is transmission weight information of AP1+AP2 or transmission weight information of AP1+transmission weight information of AP2 is determined according to the cooperation method used by AP1 and AP2.

[0247] FIG. 23 is a conceptual diagram showing two types of cooperation methods, Joint Tx and Coordinated Tx.

[0248] In Fig. 23, Joint Tx (hereinafter also referred to as JTX) is shown on the left, and Coordinated Tx (hereinafter also referred to as CTX) is shown on the right. Also, in Fig. 23, hatched ellipses represent the state of beamforming in each cooperative method.

[0249] Joint Tx is a cooperative method in which multiple APs share a transmitting antenna and perform beamforming to suppress interference with other terminals, as shown by the dashed line. JTX has the problem that it requires highly accurate frequency and time synchronization between APs and data sharing between APs, and that it may not be possible to transmit at the maximum transmission power between APs because the transmission weight is determined within the range of power that each AP can transmit. However, JTX can use more transmitting antennas by coordinating, so the channel gain is higher than when JTX is not performed.

[0250] In order to perform JTX between APs, the APs need to simultaneously transmit NDP Frames and receive feedback of AP1+AP2 transmission weight information (AP1 Info.+AP2 Info.) from the STAs, as in the first embodiment. For example, if AP1 / AP2 have four transmission antennas and the STA has two reception antennas, the STA will feed back transmission weight information consisting of an 8×2 matrix.

[0251] CTX is a cooperative method in which a single AP performs beamforming to reduce interference with other terminals. CTX is also called Coordinated BF, Coordinated Nulling, Nulling, Non-Coherent Joint Transmission, etc.

[0252] CTX is relatively easy to implement compared to JTX because it does not require data sharing between APs or highly accurate frequency and time synchronization. However, there is less freedom in beamforming due to the constraints on the number of transmitting antennas per AP, which means that channel gain tends to be limited.

[0253] To perform CTX between APs, the same transmission weight information fed back from the STA as when performing JTX between APs may be used, but the transmission weight information of AP1 / AP2 (AP1 Info., AP2 Info., respectively) can also be used. In this case, the AP transmits an NDP Frame simultaneously or separately, and the STA feeds back the transmission weight information of AP1 (AP1 Info.) and the transmission weight information of AP2 (AP2 Info.), respectively. For example, if AP1 / AP2 have four transmitting antennas and the STA has two receiving antennas, the STA will feed back two pieces of transmission weight information consisting of a 4×2 matrix.

[0254] According to the feedback signal format defined in IEEE802.11ax / Compressed Beamforming, even if the number of columns and rows of the matrix of the weight information to be fed back is the same, the feedback signal for CTX generally has less information than the feedback signal for JTX. Therefore, from the viewpoint of minimizing the amount of information in the feedback signal, the optimal format of the feedback signal from the STA differs depending on the AP cooperation method.

[0255] Therefore, in the third embodiment, the AP determines to transmit in a cooperation method that is not JTX to a STA that is determined to be able to obtain sufficient characteristics even with CTX based on the Short Req. / Resp exchange, or a STA for which it is determined that it is difficult to implement JTX, and requests a feedback signal in a format that is even necessary for implementing CTX (hereinafter, a feedback signal for CTX). By thus determining an appropriate cooperation method for each STA and requesting an appropriate format of the feedback signal based on the Short Req. / Resp exchange, it is possible to reduce the transmission required time of the feedback signal.

[0256] Hereinafter, the third embodiment will be described.

[0257] Note that since the overall sequence in the third embodiment is basically the same as the overall sequence in the first embodiment, the description thereof is omitted.

[0258] <Example of EHT Sounding Sequence> FIG. 24 is a diagram showing an example of the EHT Sounding sequence of the present technology.

[0259] The sequences from time B01 to time B08 in FIG. 24 are the same as the sequences from time T01 to time T08 in FIG. 10. However, in FIG. 24, the difference from FIG. 10 is that at time B06, AP1 uses the EHT BFRP Trigger to request the transmission weight information of AP1+AP2 (feedback signal for JTX), or requests the transmission weight information of AP1 and the transmission weight information of AP2 (feedback signal for CTX) from the STA. The details of the processing are basically the same as those in FIG. 10 and will be omitted as appropriate.

[0260] At time B01, AP1 transmits a MAP Trigger to AP2. AP2 generates an EHT NDP-A Frame and an NDP Frame based on the content described in the MAP Trigger.

[0261] At time B02, AP1 and AP2 each transmit an EHT NDP-A Frame.

[0262] At time B03, AP1 and AP2 each transmit an NDP Frame.

[0263] At time B04, AP1 transmits a Short Feedback Request Frame to STA1 to STA4.

[0264] At time B05, after receiving the Short Feedback Request Frame from AP1, STA1 to STA4 transmit a Short Feedback Response Frame including a second measurement result based on the reception status of the NDP Frame transmitted from AP1 and AP2.

[0265] As described above, for STAs that are likely to be able to obtain sufficient performance with CTX or for which it is likely to have difficulty implementing JTX (STA1 and STA4 in the case of Figure 24), AP1 determines the cooperation method for each STA based on the exchange of Short Req. / Resp. so as to receive a feedback signal for CTX.

[0266] At time B06, AP1 generates an EHT BFRP Trigger Frame based on the above-mentioned determination result, and transmits it to STA1 to STA4.

[0267] At this time, the AP1 assigns more communication resources to STA2 and STA3, which have a larger amount of information to transmit in the EHT BFRP Trigger Frame, than to STA1 and STA4. This makes it possible to reduce the overall feedback time.

[0268] At time B07, STA1 and STA4 transmit a feedback signal including the transmission weight information of AP1 (AP1 Info.) based on the EHT BFRP Trigger Frame, and then transmit a feedback signal including the transmission weight information of AP2 (AP2 Info.). STA2 and STA3 transmit a feedback signal including the transmission weight information of AP1+AP2 (AP1 Info.+AP2 Info.) based on the EHT BFRP Trigger Frame.

[0269] At time B08, AP1 completes receiving the feedback signals transmitted from STA1 to STA4.

[0270] Note that not limited to the example of FIG. 24, AP1 may, for example, first receive a feedback signal for JTX from STA2 and STA3, and then receive a feedback signal for CTX from STA1 and STA4. Similar to the first embodiment, AP1 may request the transmission weight information of only one of the APs.

[0271] <Example format of EHT NDP-A Frame> The EHT NDP-A Frame in the third embodiment is configured in the same manner as the example of FIG. 13 described above in the first embodiment.

[0272] In the case of the third embodiment, at least one of the received SNR, received RSSI difference, channel correlation value, received time difference, and transmission weight power difference is specified for the Short Feedback Condition.

[0273] For example, the reception time difference means the difference in the arrival times of the NDP Frames transmitted from AP1 / AP2. Depending on the magnitude of this reception time difference, the STA can determine whether it can correctly receive the feedback signal for JTX. Also, if the reception RSSI difference of the NDP Frames transmitted from AP1 / AP2 or the power difference between AP1 / AP2 when calculating the transmission weight for JTX is large, the STA can determine that sufficient gain can be obtained with CTX instead of JTX.

[0274] <Example format of Short Feedback Request Frame> The Short Feedback Request Frame in the third embodiment is configured in the same manner as the example in FIG. 14 described above in the first embodiment.

[0275] <Example format of Short Feedback Response Frame> The Short Feedback Response Frame in the third embodiment is configured in the same manner as the example in FIG. 15 described above in the first embodiment.

[0276] In the case of the third embodiment, in the field of Short Feedback Result Info., for example, the cooperation method to be used may be represented by 2-bit information as one of "both JTX / CTX possible", "JTX only possible", "CTX only possible", and "both not possible".

[0277] <Example format of EHT BFRP Trigger Frame> The EHT BFRP Trigger Frame in the third embodiment is configured in the same manner as the example in FIG. 16 described above in the first embodiment.

[0278] In the third embodiment, the Feedback Content ID specifies whether the feedback content is a feedback signal for JTX (transmission weight information of AP1+AP2), a feedback signal for CTX (transmission weight information of AP1+transmission weight information of AP2), or a feedback signal of transmission weight information of one of the APs.

[0279] In addition, if the number of APs is three or more, the AP must notify other APs of the combination of APs that will feed back transmission weight information for JTX and the identification number of the AP that will feed back transmission weight information for CTX.

[0280] <6. Fourth embodiment (Example of transmitting transmission wait information to a destination based on Short Req. / Resp exchange)> In the first embodiment, as described above with reference to FIG. 22, an example has been described in which feedback signals that are transmission weight information of AP1+AP2 are all transmitted to AP1 (one of the APs).

[0281] Here, when performing cooperative operation, particularly JTX, there is a high possibility that the method of generating transmission weights differs depending on the device, so even if APs are able to retain the same feedback signal information, the transmission weights generated by each AP are not necessarily the same.

[0282] Therefore, when performing JTX, it is desirable that one of the APs (AP1 in the first embodiment) calculates the optimal transmission weight based on the information it receives (collects) and shares it with the other AP (AP2 in the first embodiment). Therefore, it is assumed that the STA transmits a feedback signal to AP1.

[0283] However, in this case, not all STAs are necessarily able to transmit feedback signals to the AP 1. For a STA that is far from the AP 1 (e.g., STA4 in FIG. 4), there is a risk that the feedback signal will not reach the AP 1 depending on the transmission power value of the STA.

[0284] Even if AP1 can barely receive it, for example, the data rate of the feedback signal may be low, and the transmission time of the feedback signal may become long. For such a STA, it is desirable that the connected AP (AP2 in the case of the example in FIG. 25 described later) receive the feedback signal from the STA once and then transmit it to AP1.

[0285] Next, in the fourth embodiment, an example in which the destination of the feedback signal is determined based on the Short Req. / Resp exchange in the first embodiment will be described.

[0286] Note that since the overall sequence in the fourth embodiment is basically the same as the overall sequence in the first embodiment, the description thereof is omitted.

[0287] <Example of EHT Sounding Sequence> FIGS. 25 and 26 are diagrams showing examples of the EHT Sounding sequence of the present technology.

[0288] The sequence from time C01 to time C04 in FIG. 25 is the same as the sequence from time T01 to time T04 in FIG. 10. The same processing as in FIG. 10 is omitted as appropriate. The details of the processing are omitted as appropriate for the parts that are the same as in FIG. 10.

[0289] At time C01, AP1 transmits a MAP Trigger to AP2. AP2 generates an EHT NDP-A Frame and an NDP Frame based on the content described in the MAP Trigger.

[0290] At time C02, AP1 and AP2 each transmit an EHT NDP-A Frame.

[0291] At time C03, AP1 and AP2 each transmit an NDP Frame.

[0292] At time C04, AP1 transmits a Short Feedback Request Frame to STA1 to STA4.

[0293] At time C05, after receiving the Short Feedback Request Frame from AP1, STA1 to STA3 transmit a Short Feedback Response Frame including a second measurement result based on the reception status of the NDP Frame transmitted from AP1 and AP2.

[0294] Here, STA4 determines whether or not to transmit a Short Feedback Response Frame based on the Feedback Condition and Threshold information described in the EHT NDP-A Frame transmitted from AP1. In the case of Fig. 25, STA4 does not transmit a Short Feedback Response Frame.

[0295] Based on the Short Req. / Resp exchange, AP1 determines not to receive (collect) a feedback signal from STA4.

[0296] At time C06, AP1 generates an EHT BFRP Trigger Frame based on the above-mentioned determination result, and transmits it to STA1 to STA3. Even if STA4 returns a Short Feedback Response Frame, AP1 may determine not to directly receive a feedback signal from STA4 based on the contents of the Short Feedback Response Frame.

[0297] At time C07, STA1 to STA3 transmit feedback signals based on the EHT BFRP Trigger Frame.

[0298] At time C08, AP1 completes receiving the feedback signals transmitted from STA1 to STA3.

[0299] At time C09 in FIG. 26, AP1 generates a BFRP Trigger Request Frame for requesting STA4 to transmit an EHT BFRP Trigger Frame, and transmits the BFRP Trigger Request Frame to AP2.

[0300] At time C10, the AP2 receives the BFRP Trigger Request Frame, generates an EHT BFRP Trigger Frame based on the received BFRP Trigger Request Frame, and transmits the EHT BFRP Trigger Frame to the STA4.

[0301] At time C11, STA4 transmits a feedback signal to AP2 based on the received EHT BFRP Trigger Frame.

[0302] At time C12, AP1 generates a Feedback Request Frame for requesting a feedback signal from STA4 and transmits it to AP2.

[0303] At time C13, AP2 receives the Feedback Request Frame and transmits a feedback signal of STA4 to AP1 based on the received Feedback Request Frame.

[0304] At time C14, AP1 completes reception of the feedback signal of STA4 transmitted from AP2.

[0305] In the fourth embodiment, the feedback signal may be any of the JTX and CTX signals described above in the third embodiment, regardless of the amount and type of information to be fed back. In addition, when AP1 determines that STA4 is far from AP1 and interference from AP1 is not a problem, it may not transmit a Feedback Request to AP2 and may not receive the feedback signal from STA4.

[0306] <Format Example of EHT NDP-A Frame> The EHT NDP-A Frame in the fourth embodiment is configured in the same manner as the example of FIG. 13 described above in the first embodiment.

[0307] <Format Example of Short Feedback Request Frame> The Short Feedback Request Frame in the fourth embodiment is configured in the same manner as the example of FIG. 14 described above in the first embodiment.

[0308] Note that the Short Feedback Request Frame includes the transmission power information of the AP and the target RSSI value. The STA can determine whether to transmit a feedback signal based on those pieces of information.

[0309] <Format Example of Short Feedback Response Frame> The Short Feedback Response Frame in the fourth embodiment is configured in the same manner as the example of FIG. 15 described above in the first embodiment.

[0310] In the case of the fourth embodiment, the STA may notify the AP by including, for example, flags such as "Direct feedback response to AP1 OK" and "NG" in the content of the field of Short Feedback Result Info. Also, the STA may notify the AP by including an identifier indicating which AP is capable of a feedback response in the content of this field.

[0311] <Format Example of EHT BFRP Trigger Frame> The EHT BFRP Trigger Frame in the fourth embodiment is configured in the same manner as the example of FIG. 16 described above in the first embodiment.

[0312] <Format Example of BFRP Trigger Request Frame> Figure 27 is a diagram showing a format example of the BFRP Trigger Request Frame.

[0313] The BFRP Trigger Request Frame is a frame that requests another AP to have the specified STA send an EHT BFRP Trigger Frame.

[0314] The BFRP Trigger Request Frame consists of fields for Frame Control, Duration, RA, TA, Common Info, AP Info, Padding, and FCS.

[0315] The Frame Control field contains information indicating that this frame is a BFRP Trigger Request Frame.

[0316] The Common Info field contains information common to all STAs that transmit this frame. In this technology, it is characterized in that the Trigger Type within the Common Info represents that this frame is a BFRP Trigger Request Frame.

[0317] The AP Info includes the AP identifier (AP ID), the transmission timing information (Tx Time) of the EHT BFRP Trigger Frame, the number of STAs from which feedback signals are received (Num.of STA), and information regarding the identifiers and resource information of each AP (User Info.).

[0318] <Format Example of Feedback Request Frame> Figure 28 is a diagram showing a format example of the Feedback Request Frame.

[0319] The Feedback Request Frame is a frame that requests a feedback signal of the STA specified by this frame from another AP.

[0320] The Feedback Frame consists of the following fields: Frame Control, Duration, RA, TA, Common Info, AP Info, Padding, and FCS.

[0321] The Frame Control field contains information indicating that this frame is a Feedback Request Frame.

[0322] The Common Info field contains information common to all STAs that transmit this frame. This technology is characterized in that the Trigger Type in the Common Info field indicates that this frame is a Feedback Request Frame.

[0323] The AP Info includes an AP identifier (AP ID), an identifier of the STA that receives the feedback signal (STA ID), and information on the resource information of each AP (Resource Info.).

[0324] <Device Operation> FIG. 29 is a flowchart illustrating the EHT Sounding process of the wireless communication device 11-1 operating as the AP1.

[0325] It should be noted that steps S201 to S206 in FIG. 29 are basically the same processes as steps S56 to S61 in FIG. 17, and therefore the description thereof will be omitted.

[0326] In step S207, the communication control unit 31 determines, based on information obtainable from the Short Feedback Response Frame, the STAs that will receive the feedback signal directly and the STAs that will receive the feedback signal via another AP.

[0327] In step S208, the communication control unit 31 determines whether or not there is a STA that directly receives the feedback signal. If it is determined in step S208 that there is a STA that directly receives the feedback signal, the process proceeds to step S209.

[0328] In step S209, the communication control unit 31 generates an EHT BFRP Trigger Frame (FIG. 16) for the STA that directly receives the feedback signal, and causes the wireless transmission unit 41 to transmit it.

[0329] The STA that receives the EHT BFRP Trigger Frame and determines that it is necessary to send a feedback signal based on the EHT BFRP Trigger Frame transmits the feedback signal. In step S209, the wireless receiving unit 42 receives the feedback signal. When the feedback signal is received, the process proceeds to step S211.

[0330] On the other hand, if it is determined in step S208 that there is no STA that will directly receive the feedback, the processes in steps S209 and S210 are skipped and the process proceeds to step S211.

[0331] In step S211, the communication control unit 31 determines whether or not there is a STA that receives a feedback signal via another AP. If it is determined in step S211 that there is a STA that receives a feedback signal via another AP, the process proceeds to step S212.

[0332] In step S212, the communication control unit 31 generates a BFRP Trigger Request Frame (FIG. 27) for the other AP, and causes the wireless transmission unit 41 to transmit it.

[0333] Another AP (eg, AP2) that receives the BFRP Trigger Request Frame transmits an EHT BFRP Trigger Frame to the target STA and receives a feedback signal from the target STA.

[0334] In step S213, the communication control unit 31 generates a Feedback Request Frame (FIG. 28) for the other APs, and causes the wireless transmission unit 41 to transmit it.

[0335] Another AP (eg, AP2) that receives the Feedback Request Frame transmits a feedback signal from the target STA to AP1.

[0336] In step S214, the wireless receiving unit 42 receives the feedback signal. When the feedback signal is received, the EHT Sounding process ends.

[0337] If it is determined in step S211 that there is no STA that receives a feedback signal via another AP, the processes in steps S212 to S214 are skipped and the EHT Sounding process ends.

[0338] <7.Other> <Effects of this technology> As described above, in this technology, between the transmission of an NDP Frame of a known pattern and the reception of a feedback signal which is the first measurement result, information is exchanged between a Short Feedback Request which is a request signal for a second measurement result and a Response which is the second measurement result.

[0339] This enables the AP to optimally allocate feedback signal request destinations and feedback signal communication resources.

[0340] In the first embodiment, the amount of information to be acquired from the STA is determined in advance, so that communication resources can be distributed according to the amount of information.

[0341] Furthermore, in the second embodiment, by limiting the STAs that request a feedback signal, it is possible to allocate communication resources for STAs that do not request a feedback signal to STAs that do request a feedback signal.

[0342] Considering only the communication system of this embodiment, when the conventional method is applied to multiple APs, each of the four STAs transmits feedback signals for two APs. In contrast, in the case of this technology, two STAs transmit feedback signals for two APs, and the other two STAs transmit feedback signals for one AP, so the amount of information in the transmitted feedback signals is reduced by 25%, and the transmission time is shortened by a maximum of about 2 ms.

[0343] This technology is expected to have a greater effect as the number of streams or the number of STAs increases. On the other hand, even if the amount of information in the feedback signal cannot be reduced due to the positional relationship between the AP and STA, the transmission time for Short Feedback Request / Response exchange will increase by at most 0.2 ms.

[0344] Furthermore, in the third embodiment, the cooperation method is determined based on the exchange of Short Feedback Request / Response, thereby making it possible to reduce the transmission time of the feedback signal.

[0345] For example, by obtaining feedback signals for JTX from four STAs and feedback signals for CTX from two of the four STAs, the amount of information received can be reduced by nearly 20% to 40% (depending on the number of transmit antennas and receive antennas).

[0346] Furthermore, in the fourth embodiment, by determining the method and route for receiving the feedback signal based on the Short Feedback Request / Response, it is possible to, for example, increase the data rate of the feedback signal, thereby shortening the transmission time of the feedback signal.

[0347] <Computer configuration example> The above-mentioned series of processes can be executed by hardware or software. When the series of processes is executed by software, the program constituting the software is installed from a program recording medium into a computer incorporated in dedicated hardware, or into a general-purpose personal computer, etc.

[0348] FIG. 30 is a block diagram showing an example of the hardware configuration of a computer that executes the above-mentioned series of processes by a program.

[0349] A central processing unit (CPU) 301, a read only memory (ROM) 302, and a random access memory (RAM) 303 are interconnected via a bus 304.

[0350] An input / output interface 305 is further connected to the bus 304. An input unit 306 including a keyboard, a mouse, etc., and an output unit 307 including a display, a speaker, etc. are connected to the input / output interface 305. In addition, a storage unit 308 including a hard disk, a non-volatile memory, etc., a communication unit 309 including a network interface, etc., and a drive 310 that drives a removable medium 311 are connected to the input / output interface 305.

[0351] In the computer configured as above, the CPU 301 loads a program stored in the storage unit 308 into the RAM 303 via the input / output interface 305 and the bus 304 and executes the program, thereby performing the above-mentioned series of processes.

[0352] The programs executed by the CPU 301 are installed in the storage unit 308 by being recorded on a removable medium 311, or provided via a wired or wireless transmission medium such as a local area network, the Internet, or digital broadcasting.

[0353] In addition, the program executed by the computer may be a program in which processing is performed chronologically in the order described in this specification, or it may be a program in which processing is performed in parallel or at the required timing, such as when called.

[0354] In this specification, a system refers to a collection of multiple components (devices, modules (parts), etc.), regardless of whether all the components are in the same housing. Therefore, multiple devices housed in separate housings and connected via a network, and a single device in which multiple modules are housed in a single housing, are both systems.

[0355] Furthermore, the effects described in this specification are merely examples and are not limiting, and other effects may also be present.

[0356] The embodiments of the present technology are not limited to the above-described embodiments, and various modifications are possible without departing from the gist of the present technology.

[0357] For example, the present technology can be configured as cloud computing, in which a single function is shared and processed collaboratively by multiple devices via a network.

[0358] Furthermore, each step described in the above flow chart can be executed by one device, or can be shared and executed by a plurality of devices.

[0359] Furthermore, when a single step includes multiple processes, the multiple processes included in the single step can be executed by a single device, or can be shared and executed by multiple devices.

[0360] <Examples of configuration combinations> The present technology can also be configured as follows. (1) A wireless transmitter; a communication control unit that causes the wireless transmission unit to transmit a reference signal of a known pattern addressed to a wireless communication terminal in cooperation with one or more other wireless communication devices, generates a request signal for the wireless communication terminal to request a second measurement result of the reference signal that is simpler than a first measurement result, and causes the wireless transmission unit to transmit the request signal; A wireless communication device comprising: (2) The communication control unit determines feedback information regarding a feedback signal including the measurement result, which is requested from the wireless communication terminal, based on the measurement result information acquired from the wireless communication terminal that has received the request signal. The wireless communication device according to (1). (3) The communication control unit determines, as information related to the feedback signal, at least one of a request destination of the feedback signal, an amount of information of the feedback signal, a communication resource of the feedback signal, and whether the feedback signal is received directly or via the other wireless communication device. The wireless communication device according to (2). (4) the communication control unit generates an inducement signal including instruction information instructing the wireless communication terminal requesting the feedback signal on a communication resource of the feedback signal and on the content of the first measurement result to be included in the feedback signal, The wireless transmission unit transmits the induction signal. The wireless communication device according to (2) or (3). (5) The communication control unit instructs, in the instruction information, to transmit, as content of the first measurement result, only the first measurement result regarding itself, or the first measurement result regarding the other wireless communication device in addition to the first measurement result regarding itself. The wireless communication device according to (4). (6) The communication control unit instructs whether to transmit the first measurement result regarding the other wireless communication device separately from the first measurement result regarding the wireless communication device itself, or to transmit the first measurement result regarding the other wireless communication device in a combined form with the first measurement result regarding the wireless communication device itself. The wireless communication device according to (5). (7) the communication control unit generates a request signal to request the other wireless communication device that is requested to receive the feedback signal to transmit an inducement signal including instruction information that indicates content of the first measurement result to be included in the feedback signal; The wireless transmission unit transmits the request signal. The wireless communication device according to (2). (8) the communication control unit, when requested by the other wireless communication device to receive the feedback signal, generates an inducement signal including information regarding a communication resource of the feedback signal and instruction information indicating content of the first measurement result to be included in the feedback signal; The wireless transmission unit transmits the induced signal to the wireless communication terminal. The wireless communication device according to (7). (9) the communication control unit generates a prior notification signal including instruction information indicating at least one of information regarding a determination method for obtaining the second measurement result and information regarding a determination threshold; The wireless transmission unit transmits the advance notification signal. The wireless communication device according to (1). (10) The communication control unit generates the advance notification signal including the instruction information indicating at least one of a correlation value between a received power value and an estimated channel, a signal arrival time difference, and a transmission weight power difference, as the determination method. The wireless communication device according to (9). (11) The communication control unit generates the advance notification signal including, as the determination threshold, an absolute threshold and a relative value with respect to the reference signal transmitted from the communication control unit itself, or the instruction information instructing a calculation method thereof. The wireless communication device according to (9). (12) the communication control unit generates a cooperation request signal including instruction information indicating at least one of information on a determination method for obtaining the second measurement result and information on a determination threshold; The wireless transmission unit transmits the cooperation request signal to the other wireless communication device. A wireless communication device according to any one of (1) to (11). (13) The communication control unit collects measurement result correspondence information indicating whether the second measurement result can be handled from the wireless communication terminal under control. A wireless communication device according to any one of (1) to (12). (14) The communication control unit causes the measurement result correspondence information to be shared with the other wireless communication device. The wireless communication device according to (13). (15) A wireless communication device, A reference signal of a known pattern addressed to a wireless communication terminal is transmitted in cooperation with one or more other wireless communication devices, and a request signal is generated and transmitted to the wireless communication terminal, the request signal requesting a second measurement result of the reference signal that is simpler than a first measurement result. A wireless communication method. (16) a communication control unit that generates a second measurement result based on a reference signal of a known pattern cooperatively transmitted from a plurality of wireless communication devices, the second measurement result being simpler than a first measurement result of the reference signal; a wireless transmission unit that transmits a response signal including the second measurement result to the wireless communication device that is a request destination in response to a request signal requesting the second measurement result; A wireless communication terminal comprising: (17) The communication control unit generates the second measurement result based on information on a determination method and information on a determination threshold in a pre-notification signal transmitted from the wireless communication device. The wireless communication terminal according to (16). (18) the communication control unit generates the feedback signal including the measurement result based on a feedback signal resource included in the trigger signal and a type of the measurement result to be included in the feedback signal; The wireless transmission unit transmits the feedback signal. The wireless communication terminal according to (16) or (17). (19) The communication control unit includes, in the feedback signal, only the first measurement result of the reference signal transmitted from the wireless communication device that is a transmission source of the induced signal, as content of the first measurement result. The wireless communication terminal according to (18). (20) The communication control unit includes the first measurement results of all of the received reference signals in the feedback signal as the contents of the first measurement results. The wireless communication terminal according to (18). (twenty one) A wireless communication terminal, generating a second measurement result based on a reference signal of a known pattern cooperatively transmitted from a plurality of wireless communication devices, the second measurement result being simpler than a first measurement result of the reference signal; In response to a request signal requesting the second measurement result, a response signal including the second measurement result is transmitted to the wireless communication device that is the request destination. A wireless communication method. [Explanation of symbols]

[0361] 11 communication device, 21 radio signal processing unit, 22-1, 22-2 wireless communication unit, 31 communication control unit, 33 data processing unit, 51 communication terminal, 61 radio signal processing unit, 62-1, 62-2 wireless communication unit, 71 communication control unit, 73 data processing unit

Claims

[Claim 1] A wireless transmitter; a communication control unit that causes the wireless transmission unit to transmit a reference signal of a known pattern addressed to a wireless communication terminal in cooperation with one or more other wireless communication devices, generates a request signal for requesting a second measurement result of the reference signal, which is simpler than a first measurement result, from the wireless communication terminal, and causes the wireless transmission unit to transmit the request signal; A wireless communication device comprising:

Images