Station device, access point device, and wireless communication method

Abstract

To provide a station device, an access point device (AP), and a wireless communication method that set up inter-AP cooperation by a probe request frame transmitted by a station device (STA).SOLUTION: In a communication method between a STA constituting a multi-link device in a wireless communication system and two or more APs, the inter-AP cooperation is mainly constituted by the STA, and inter-AP cooperation is set up between an M-AP (master AP) and an S-AP (slave AP) by a probe request frame sent by the STA.SELECTED DRAWING: Figure 7

Description

[Technical field]

[0001] The present invention relates to a station device, an access point device, and a wireless communication method. [Background technology]

[0002] In the field of wireless communication systems, the Institute of Electrical and Electronics Engineers Inc. (IEEE) continues to update the specifications of IEEE802.11, the wireless LAN standard, to realize faster wireless LAN (Local Area Network) communication and more efficient frequency utilization. Wireless LAN can perform wireless communication using unlicensed bands that can be used without permission (license) from countries and regions. For personal use such as at home, Internet access from within the home has been made wireless by including a wireless LAN access point function in a line termination device for connecting to a WAN (Wide Area Network) line to the Internet, or by connecting a wireless LAN access point device to a line termination device. In other words, wireless LAN station devices such as smartphones and PCs can access the Internet by connecting to a wireless LAN access point device. Currently, with the rapid spread of wireless LAN devices, standardization activities for IEEE802.11be, the successor standard to IEEE802.11ax (also called HT), have begun, and further improvement of throughput per user in an environment where wireless LAN devices are densely placed is being considered.

[0003] In Europe, ETSI (European Telecommunications Standards Institute) and in the United States, FCC (Federal Communications Commission) are considering allowing the use of the 6 GHz band (5.935 to 7.125 GHz) as an unlicensed band, and similar considerations are underway in other countries around the world. This means that it is expected that wireless LAN will be able to use the 6 GHz band in addition to the 2.4 GHz and 5 GHz bands. In order to accommodate the expansion of applicable frequencies, the Wi-Fi Alliance has formulated Wi-Fi6E (registered trademark), an extension of Wi-Fi6, which will use the 6 GHz band.

[0004] Following the approval of the Project Authorization Request (PAR) and Criteria for Standards Development (CSD) of the Ultra-High Reliability (UHR) Study Group (SG), the successor standard to IEEE802.11be (also known as EHT), the launch of IEEE802.11bn, a task group for the next-generation wireless LAN standard, is planned. In IEEE802.11bn, discussions on new wireless communication methods aimed at improving throughput and reliability are scheduled to be considered in the future, and it is expected that the throughput will be improved according to the SNR (Signal to Noise Ratio), latency will be reduced, and the reliability of wireless LAN connections will be improved. The wireless communication method includes multi-AP coordination, which coordinates multiple APs, such as coordinated orthogonal frequency division multiple access (c-OFDMA), coordinated time division multiple access (c-TDMA), coordinated beamforming (c-BF), coordinated joint transmission (C-JT or J-TX), coordinated spatial reuse (c-SR), and roaming using the concept of multi-link. To realize effective multi-AP coordination (hereinafter also referred to as multi-AP), it is important to reduce the overhead required for connection processing from grasping candidates for cooperating APs to following the objectives of improving throughput and reliability while taking into account the propagation path conditions. On the other hand, it is expected that the existing mmWave (millimeter wave) will be redesigned and introduced into wireless LANs by the new SG, Integrated mmWave (ImmW), so the method of using multiple frequency bands simultaneously will also be an important technical issue in improving throughput in the future.

[0005] A wireless communication system such as a wireless LAN may include an access point device (AP, also called a wireless communication device or a base station device) and multiple station devices (STA, also called a terminal or a terminal device). The access point device and the station device may each include multiple access point devices and station devices. A communication system / network configured between the access point device and the station devices is called a basic service set (BSS, management range).

[0006] In IEEE802.11bn, by connecting access point devices with each other, it is possible to configure a communication system / network that can manage a wider range of BSS. In AP-to-AP cooperation, a communication system / network is configured that is made up of multiple access point devices. In this AP-to-AP cooperation, an AP called a Master AP (M-AP) takes the lead in controlling the AP-to-AP cooperation method with the AP that is to cooperate with it. An AP that constitutes AP-to-AP cooperation with the M-AP is distinguished from the M-AP as a slave AP (S-AP).

[0007] An example of the procedure of the inter-AP cooperation method is shown in FIG. 10. First, M-AP#1 sets candidates for APs to cooperate with and the cooperation method between the APs by collecting information elements (Neighbor report element / Reduced Neighbor report element, etc.) (hereinafter, also referred to as AP information and Affiliated AP information) including the capability of the AP to be the S-AP and information on the surrounding APs. Next, M-AP#1 broadcasts a frame requesting inter-AP cooperation to candidates for APs to cooperate with, including the surrounding APs to be the S-AP. Then, among the APs that receive the frame requesting inter-AP cooperation, the APs that can implement the inter-AP cooperation specified by M-AP#1 are set as S-AP#1-#2 in FIG. 10 and transmit a response frame regarding whether or not to implement inter-AP cooperation to M-AP#1. When S-AP#1-#2 that receive the frame requesting inter-AP cooperation satisfy the request of M-AP#1, they each transmit a response frame indicating that inter-AP cooperation is possible, and implement inter-AP cooperation. On the other hand, if the AP cooperation specified by M-AP#1 becomes difficult, S-AP#1-#2 can request AP cooperation different from the request from M-AP#1 by sending a frame to M-AP#1 requesting a change to the AP cooperation settings.

[0008] An example of a sounding procedure in inter-AP cooperation will be described. The sounding process is composed of an NDP sounding phase (see FIG. 11) and a CSI feedback phase (see FIG. 12). First, M-AP#1 transmits a trigger frame to S-AP#1-#2. Then, S-AP#1-#2 transmit NDPA / NDP frames (Null Data Packet Announcement frames) to STAs belonging to the S-AP. After S-AP#1 transmits the NDPA frame and the NDP frame, M-AP#1 transmits a Poll frame to S-AP#2, and S-AP#2 starts transmitting the NDPA frame and the NDP frame. Meanwhile, in the CSI feedback phase after the NDP sounding phase, M-AP#1 transmits a trigger frame to S-AP#1-#2. After that, S-AP#1 and S-AP#2 send Beamforming report polls (BRP) to the STAs (STA#1-#2) belonging to each S-AP to obtain Compressed Beamforming (CB). Then, M-AP#1 receives channel state information (CSI) feedback from S-AP#1-#2 by sending trigger frames to S-AP#1-#2 to obtain sounding results from the STAs belonging to each S-AP.

[0009] On the other hand, in inter-AP cooperation mainly configured by the M-AP, the overhead associated with beacon frames for the purpose of configuring and reconfiguring inter-AP cooperation between the M-AP and S-AP, the exchange of frames required for configuring inter-AP cooperation between the M-AP and S-AP, and sounding between the S-AP and STA, are problems that reduce system throughput. [Prior art documents] [Non-patent literature]

[0010] [Non-Patent Document 1] IEEE 802.11-23 / 0046-02-0uhr, Mar. 2023 [Non-Patent Document 2] IEEE 802.11-23 / 0854-00-0uhr, May. 2023 Summary of the Invention [Problem to be solved by the invention]

[0011] In multi-AP coordination mainly configured by APs, exchange of beacon frames for the purpose of setting and re-setting multi-AP coordination between M-AP and S-AP, or frames required for setting multi-AP coordination between M-AP and S-AP, is performed every time communication becomes impossible due to fluctuations in the propagation path environment for each frequency band, interference, movement of STA, etc. Thus, the overhead associated with the exchange of frames is an issue that reduces the transmission efficiency of the entire wireless communication system. [Means for solving the problem]

[0012] The station device and the wireless communication method for solving the above-mentioned problems are as follows.

[0013] (1) That is, a station device according to one embodiment of the present invention is a station device having a transmitting unit and a control unit, wherein the control unit generates a probe request frame, the probe request frame includes a field related to an inter-AP cooperation method, the field includes information indicating two or more frequency band candidates and information indicating inter-AP cooperation method candidates corresponding to the candidates, a broadcast address is specified in an address field of a MAC header of the probe request frame, and the transmitting unit transmits the probe request frame.

[0014] (2) The station device described in (1) above, wherein the control unit generates a trigger frame, the trigger frame includes a field regarding the timing of starting communication, the field including information indicating an inter-AP coordination method and information indicating the timing of starting communication with an access point device using the coordination method, the address indicated in the address field of the MAC header of the trigger frame is an address indicating two or more specified access point devices, or an address indicating each of the two or more specified access point devices, and the transmission unit transmits the trigger frame.

[0015] (3) The station device described in (1) above, further comprising a receiving unit that receives a probe response frame, the probe response frame including a field regarding whether inter-AP cooperation is possible, the field including information indicating two or more frequency band candidates and information indicating whether a candidate inter-AP cooperation method corresponding to the candidates is possible, and the address of the station device is specified in an address field of a MAC header of the probe response frame.

[0016] (4) An access point device that communicates with a station device, comprising a transmitter, a receiver, and a control unit, wherein the receiver receives a probe request frame including a field regarding an AP-to-AP cooperation method and a trigger frame indicating a communication start timing, the control unit generates a probe response frame including a field regarding whether or not AP-to-AP cooperation is possible, and the transmitter transmits the probe response frame including the field regarding whether or not AP-to-AP cooperation is possible.

[0017] (5) A wireless communication method comprising the steps of: transmitting a frame; and generating a probe request frame, wherein the probe request frame includes a field relating to an inter-AP cooperation method, the field including information indicating two or more frequency band candidates and information indicating inter-AP cooperation method candidates corresponding to the candidates, and wherein a broadcast address is specified in an address field of a MAC header of the probe request frame. Effect of the Invention

[0018] The effect of the present invention is that it is possible to reduce overhead associated with the exchange of beacon frames for the purpose of setting up and reconfiguring AP cooperation between an M-AP and an S-AP in an AP cooperation method mainly configured with an access point device, or frames required for setting up AP cooperation between an M-AP and an S-AP, thereby improving the transmission efficiency of the entire wireless communication system. [Brief description of the drawings]

[0019] [Figure 1] 1 is a schematic diagram illustrating an example of a wireless communication system according to an embodiment of the present invention. [Diagram 2] 1 is a block diagram showing an example of a configuration of a wireless communication device according to an aspect of the present invention. [Diagram 3] 1 is a block diagram showing an example of a configuration of a wireless communication device according to an aspect of the present invention. [Figure 4] 1 is a block diagram showing an example of a configuration of a wireless communication device according to an aspect of the present invention. [Diagram 5] FIG. 2 is a diagram illustrating an example of a frame configuration according to an embodiment of the present invention. [Figure 6] FIG. 2 is a diagram illustrating an example of a frame configuration according to an embodiment of the present invention. [Figure 7] 1 is a block diagram illustrating an example of a wireless communication method according to an aspect of the present invention. [Figure 8] 1 is a schematic diagram illustrating an example of a wireless communication system according to an embodiment of the present invention. [Figure 9]1 is a block diagram illustrating an example of a wireless communication method according to an aspect of the present invention. [Figure 10] FIG. 1 is a diagram illustrating the prior art, and is a schematic diagram showing an example of a wireless communication method. [Figure 11] FIG. 1 is a diagram illustrating the prior art, and is a schematic diagram showing an example of a wireless communication method. [Figure 12] FIG. 1 is a diagram illustrating the prior art, and is a schematic diagram showing an example of a wireless communication method. [Figure 13] FIG. 1 is a diagram illustrating the prior art, and is a schematic diagram showing an example of a wireless communication method. [Figure 14] FIG. 1 is a diagram for explaining a conventional technique, showing an example of a frame configuration. [Figure 15] FIG. 1 is a diagram illustrating the prior art, and is a schematic diagram showing an example of a wireless communication method. [Figure 16] FIG. 1 is a diagram for explaining a conventional technique, and is a schematic diagram showing an example of radio resources. [Figure 17] FIG. 1 is a diagram for explaining the prior art, and is a schematic diagram showing an example of a frame configuration. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0020] The wireless communication system in this embodiment includes an access point device (hereinafter, also referred to as AP, wireless communication device, or base station device) and one or more station devices (hereinafter, also referred to as STA, terminal, or terminal device). A communication system or network configured with the access point device and the station device is called a basic service set (BSS, management range). The access point device according to this embodiment can configure a communication system / network that can manage a wider range of BSS by cooperating with one or more access point devices. The communication system / network made up of a plurality of access point devices is implemented by inter-AP cooperation, and the access point device participating in the inter-AP cooperation can include one or more station devices. The station device according to this embodiment can have the functions of the access point device. Similarly, the access point device according to this embodiment can have the functions of the station device.

[0021] The base station device and the terminal device in the BSS can communicate based on CSMA / CA (Carrier sense multiple access with collision avoidance). In this embodiment, in addition to the case where the base station device communicates with another base station device, the present invention is directed to an infrastructure mode where the base station device communicates with multiple terminal devices, but is not limited thereto.

[0022] In a wireless communication system, in an example of an IEEE 802.11 system, each wireless communication device can transmit frames of multiple frame types having a common frame format. The frames (communication frames) are defined in the physical (PHY) layer, the medium access control (MAC) layer, and the logical link control (LLC) layer.

[0023] The frame of the PHY layer is called a physical protocol data unit (PPDU, physical layer frame). The PPDU frame is composed of a physical layer header (PHY header) that contains header information for signal processing in the physical layer, and a physical service data unit (PSDU, MAC layer frame), which is a data unit processed in the physical layer. The PSDU can be composed of an aggregated MPDU (A-MPDU) that aggregates multiple MAC protocol data units (MPDUs), which are the retransmission units in the wireless section.

[0024] For example, the PHY header includes reference signals such as a short training field (STF) used for signal detection and synchronization, a long training field (LTF) used for acquiring channel information for data demodulation, and control signals such as a signal (SIG) including control information for data demodulation. In addition, STFs are classified into Legacy-STF (L-STF), High throughput-STF (HT-STF), Very high throughput-STF (VHT-STF), High efficiency-STF (HE-STF), Extremely High Throughput-STF (EHT-STF), etc. according to the corresponding standard, and LTFs and SIGs are similarly classified into L-LTF, HT-LTF, VHT-LTF, HE-LTF, L-SIG, HT-SIG, VHT-SIG, HE-SIG, and EHT-SIG. VHT-SIG is further classified into VHT-SIG-A1, VHT-SIG-A2, and VHT-SIG-B. Similarly, HE-SIG is classified into HE-SIG-A1 to HE-SIG-A4 and HE-SIG-B. In addition, it can include a Universal SIGNAL (U-SIG) field that contains additional control information in anticipation of technical updates in the same standard.

[0025] Furthermore, the PHY header can include information for identifying the BSS that is the source of the frame (hereinafter, also referred to as BSS identification information). The information for identifying the BSS can be, for example, the SSID (Service Set Identifier) ​​of the BSS or the MAC address of the base station device of the BSS. In addition, the information for identifying the BSS can be, for example, a value unique to the BSS other than the SSID or MAC address (such as BSS Color), TxBSSID (Transmitted BSSID) or NonTxBSSID (NonTransmitted BSSID), BSSID Index / Multiple BSSID Index.

[0026] The PPDU frame is modulated according to a corresponding standard, for example, in the case of the IEEE 802.11n standard, it is modulated into an Orthogonal frequency division multiplexing (OFDM) signal.

[0027] MPDU is composed of a MAC header that contains header information for signal processing at the MAC layer, a MAC service data unit (MSDU) or frame body that is a data unit processed at the MAC layer, and a frame check sequence (FCS) that checks for errors. Multiple MSDUs can also be aggregated as an Aggregated MSDU (A-MSDU).

[0028] The frame types of the MAC layer are roughly classified into three types: management frames that manage the connection state between devices, control frames that manage the communication state between devices, and data frames that contain actual transmission data. Each type is further classified into several subframe types. The control frames include acknowledgement (ACK or Ack) frames, request to send (RTS) frames, and clear to send (CTS) frames. The management frames include beacon frames, probe request frames, probe response frames, authentication frames, association request frames, and association response frames. The data frames include data frames and polling (CF-poll) frames. Each device can read the contents of the frame control field included in the MAC header and know the type and subframe type of the received MAC frame. The MAC layer frames can also be used in a wireless communication method (Multi-Link Operation: MLO) using a Multi-Link Device (MLD). An MLD consisting of two or more APs / STAs is called AP-MLD / Non AP-MLD, but the APs that make up the MLD may also be called Affiliated APs or sub-access point devices, and the STAs that make up the MLD may also be called Non-AP STAs, Affiliated STAs, or substation devices. For example, in AP-MLD and Non AP-MLD, information on multiple links may be bundled into one link and transmitted at once as a Multi-Link (ML) probe request frame. The beacon frame may also be reported for each Affiliated AP.

[0029] Note that the Ack may include a Block ACK, which is capable of notifying completion of reception of multiple MPDUs.

[0030] A beacon frame includes a field that describes the period (beacon interval) at which the beacon is transmitted and the SSID. An AP can periodically broadcast a beacon frame within a BSS, and a STA can identify APs around the STA by receiving the beacon frame. Meanwhile, a STA can search for an AP by broadcasting a probe request frame within a BSS. An AP can transmit a probe response frame in response to the probe request frame, and the contents of the probe response frame are the same as those of a beacon frame.

[0031] First, an example of a procedure for identifying an AP using a probe request / response frame will be described. A STA broadcasts a probe request frame to identify surrounding APs. In order to identify candidates for a connection destination AP, the STA uses the probe request frame to request an information element (such as a Neighbor report element / Reduced Neighbor report element) including the AP's capability and information on surrounding APs. An AP that receives the probe request frame can transmit a probe response frame to the STA. The probe response frame includes information on the AP requested by the STA. The procedure for identifying an AP using the probe request frame is called active scanning.

[0032] Next, an example of a procedure for identifying an AP using a beacon frame will be described. It is also possible to use a beacon frame to notify an STA in a BSS of an information element equivalent to a probe response frame. The STA can identify surrounding APs by receiving a beacon frame that is periodically notified in the BSS. This procedure is called passive scanning. The STA can request an information element that was not notified in the beacon frame from the AP using a probe request frame or the like.

[0033] Based on the above, FIG. 13 shows an example of authentication / connection processing with an AP from the recognition of a neighboring AP. The device configuration of the wireless communication device 1-1 and the wireless communication device 2-1 is the same as the device configuration example of FIG. 2 described below unless otherwise specified. A beacon frame 10-1 in FIG. 13 is transmitted from the wireless communication device 1-1 (also called the base station device 1-1 or AP1-1) to the wireless communication device 2-1 (also called the terminal device 2-1 or STA2-1), and the beacon frame 10-1 includes information elements including the capability of the AP and information on the neighboring APs (Neighbor report element / Reduced Neighbor report element). A probe request frame 10-2 in FIG. 13 is transmitted from the STA2-1 to the AP1-1, and the probe request frame 10-2 can also include information similar to that of the beacon frame 10-1. In FIG. 13, the AP1-1 that receives the probe request frame 10-2 transmits a probe response frame 10-3 to the STA2-1. The probe response frame 10-3 can include an information element requested by the STA2-1.

[0034] After identifying the AP, the STA performs a connection process to the AP. The connection process by the STA is classified into a procedure using an authentication frame and a procedure using an association frame. In the procedure using an authentication frame, the STA transmits an authentication request frame to the AP to which it wishes to connect. The AP that receives the authentication request frame transmits an authentication response frame including a status code indicating whether or not the authentication was successful to the STA. The STA that receives the authentication response frame can determine whether or not the authentication has been approved by the AP by reading the status code written in the authentication frame. Note that the AP and the STA can exchange authentication frames multiple times. In the procedure using an association frame, the STA transmits an association request frame to the AP. The AP that receives the association request frame determines whether or not the connection with the STA is approved, and transmits an association response frame to notify the STA of the decision. The connection response frame contains a status code indicating whether the connection process is possible or not, and an association identifier (AID) for identifying the STA. The AP can manage connections with multiple STAs by setting different AIDs for each STA that it has granted connection permission to.

[0035] FIG. 13 shows an example of authentication / connection processing with an AP. An authentication request frame 10-4 in FIG. 13 is an authentication request frame 10-4 that STA2-1 transmits to AP1-1 to which it wishes to connect. AP1-1, which receives the authentication request frame 10-4, transmits an authentication response frame 10-5 to STA2-1, including a status code indicating whether authentication was successful or not. Then, AP1-1 transmits a connection request frame 10-6 to AP1-1, which is the connection destination for which STA2-1 has been authenticated. At this time, AP1-1, which receives the connection request frame 10-6, transmits a connection response frame 10-7 to STA2-1, including a status code indicating whether connection processing is successful or not, and an AID for identifying the STA. AP1-1 can manage the connection with STA2-1 by setting different AIDs to the STA2-1 to which it has issued connection permission.

[0036] An example of grasping surrounding APs and connection processing with APs in the case of a multi-link having two or more links is shown. APs belonging to AP-MLD can set multiple BSSIDs. An Affiliated AP using TxBSSID (Transmitted BSSID) which is a BSSID that transmits data frames (hereinafter, also simply referred to as TxBSSID Affiliated AP) is an AP that transmits data frames, and can broadcast information on BSSIDs other than TxBSSID in a Multiple BSSID Element in a beacon frame. On the other hand, an Affiliated AP using NonTxBSSID (Nontransmitted BSSID) which is a BSSID other than TxBSSID (hereinafter, also simply referred to as NonTxBSSID Affiliated AP) broadcasts without including the Multiple BSSID Element in a beacon frame. Note that NonTxBSSID Affiliated APs can connect to legacy terminals (legacy STAs) such as non-HE.

[0037] Information on Non-AP STAs (also called Affiliated Non-AP STAs) and Affiliated APs that constitute MLD can be sent together using a Multi-Link Element (MLE). The MLE can set purposes such as grasping surrounding Affiliated APs, probe request, reconfiguration of multilink settings, TDLS (Tunneled Direct Link Setup), and Priority Access according to the value of the Type subfield of the Multi-Link Control field, and can be equipped with information elements required for each purpose. In addition, the MLE can include information (Common Info) on the MLD's capabilities (Capability) and operation mode, and information for each link (Per-STA Profile), and the Per-STA Profile can include the same information elements as those included in the probe request / response frame. By using the MLE, an Identifier (AP-MLD ID) that distinguishes multiple AP-MLDs can be specified, and a frame can be sent to an Affiliated AP that is an AP that belongs to the AP-MLD. The information about the Affiliated AP is one or more information elements including the AP's capabilities and information about surrounding APs.

[0038] The capabilities of the MLD include, for example, channel information (frequency, bandwidth, etc.) that the AP-MLD can use, whether STR (Simultaneously Transmission and Reception) is possible, whether frame synchronization is possible, whether multilink switching is possible, etc. The multilink operation mode information includes, but is not limited to, channel information (frequency, bandwidth, etc.) of each link that constitutes the multilink, multilink aggregation, multilink switching, frame synchronization, frame asynchronous, STR, non-STR, etc. As will be described in detail later, in EHT, there are multilink (Multi-Link: ML) probe request / multilink (Multi-Link: ML) probe response frames that are extensions of probe request / response frames for multilink use, and each can include information elements (MLE, etc.) that can accommodate information on multiple links.

[0039] An example of how a Non-AP STA knows an Affiliated AP in MLO will be described. Before setting up a multi-link (ML) between a Non-AP-MLD and an AP-MLD, the Non-AP STA can broadcast a probe request frame / ML probe request frame to know surrounding Affiliated APs. There is a method using passive scanning / active scanning, which is the same as in the case of a single link in FIG. 13, and a probe request frame can be transmitted for each Non-AP STA (Affiliated STA) belonging to the Non-AP-MLD. The Non-AP STA can broadcast a ML probe request frame that summarizes information on Non-AP STAs other than its own terminal that belong to the Non-AP-MLD. Using the ML probe request frame, the Non-AP STA can request information elements (Neighbor report element / Reduced Neighbor report element, etc.) that include the AP's capabilities and information on surrounding APs. The Affiliated AP that receives the ML probe request frame can transmit an ML probe response frame to the Non-AP STA. The ML probe response frame can include information about the Affiliated AP requested by the Non-AP STA (information elements including AP capabilities, information about surrounding APs, etc.).

[0040] For example, when an affiliated AP of TxBSSID receives a probe request frame / ML probe request frame, it can transmit a probe response frame / ML probe response frame together with a Multiple BSSID Element and an information element associated with each affiliated AP. That is, a non-AP STA can grasp affiliated APs belonging to the AP-MLD at once by the ML probe request frame and the ML probe response frame. On the other hand, when an affiliated AP of NonTxBSSID receives a probe request frame / ML probe request frame, the probe response frame / ML probe response frame is transmitted from the affiliated AP of TxBSSID, but information on the affiliated APs of NonTxBSSID and TxBSSID (information elements including AP capabilities and information on surrounding APs) is stored in different information elements (Basic Multi-link Element (BMLE) as an example) in the probe response frame and transmitted.

[0041] FIG. 14(a) shows an example of a Multi-Link (ML) probe request frame that a Non-AP STA transmits to an Affiliated AP of TxBSSID. A Non-AP STA can transmit information of each link to an Affiliated AP by including a Probe Request Multi-Link Element in an ML probe request frame. For example, as shown in FIG. 14(a), information on the MLD capability and operation mode in Non-AP-MLD can be included in the Common Info of the Probe Request Multi-Link Element, and information on Non-AP STAs belonging to Non-AP-MLD can be included in the Per-STA Profile of the Link Info, and then transmitted to an Affiliated AP. A Non-AP STA can also notify an information element that it wishes to obtain from an Affiliated AP in an ML probe request frame. In the example of the ML probe request frame in FIG. 14(a), information on a link corresponding to a Link ID or other information elements that can identify wireless links can be stored in the Link Info of the Probe Request Multi-Link Element. For example, if a Non-AP MLD is composed of three Non-AP STAs, and the Link IDs of the three Non-AP STAs are set to 0 to 2, the Per-STA Profile corresponding to the three Non-AP STAs is stored in the Link Info of the Probe Request Multi-Link Element of the ML probe request frame. Note that the ML probe request frame in FIG. 14(a) can include one or more other information elements, etc.

[0042] FIG. 14(b) shows an example of an ML probe response frame transmitted by an Affiliated AP of TxBSSID to a Non-AP STA. In FIG. 14(b), since the Affiliated AP uses TxBSSID, the ML probe response frame can include information about NonTxBSSID in Multiple BSSID Element. Furthermore, the information about NonTxBSSID can be included in NonTxBSSID Profile and associated with each BSSID Index. Furthermore, the ML probe response frame transmitted by an Affiliated AP of TxBSSID to a Non-AP STA can include information about the Affiliated AP (such as AP Capability) and a Reduced Neighbor Report Element including information elements indicating information about surrounding APs. In the Reduced Neighbor Report Element, the information about the Affiliated AP can be associated with each AP-MLD ID and each Link ID. For example, if the AP #N in the Reduced Neighbor Report Element in FIG. 14(b) is set with an AP-MLD ID of 0 and a Link ID of 0, the information included in the AP #N belongs to the AP-MLD with an AP-MLD ID of 0 and is for an AP with a Link ID of 0. On the other hand, the information requested by the Non-AP STA to the Affiliated AP can be included in the Per-STA Profile of the Basic Multi-link Element in FIG. 14(b). The Per-STA Profile of the Basic Multi-link Element can be associated with each Link ID. For example, the Per-STA Profile of the Non-AP STA with a Link ID of 0 to 2 can be aggregated and transmitted in the Basic Multi-link Element. Note that the ML probe response frame in FIG. 14(b) can include various Elements, etc., like other Elements. Hereinafter, the description of the same Elements as in FIG. 14 will be omitted.

[0043] The authentication to connection process of the Affiliated AP will be described below. By using a frame with the same structure as that in FIG. 14, it is possible to exchange information on multiple links at once. After identifying the Affiliated AP, the Non-AP STA performs connection processing to the Affiliated AP. The connection processing by the Non-AP STA can be based on the same procedure as that in the case of a single link shown in FIG. 13, and is classified into a procedure using an authentication frame (authentication request / authentication response frame) and a procedure using a connection frame (connection request / connection response frame). In the procedure using an authentication frame, the Non-AP STA transmits an authentication request frame to the Affiliated AP to which it wishes to connect. The Affiliated AP that receives the authentication request frame transmits an authentication response frame including a status code indicating whether or not the authentication was successful to the Non-AP STA. The Non-AP STA that receives the authentication response frame can determine whether or not the Affiliated AP has permitted authentication by reading the status code written in the authentication frame. Note that the authentication frame includes an MLE, so that multiple links can be authenticated with one authentication frame. In addition, in the procedure using a connection frame, a Non-AP MLD transmits a connection request frame to an AP-MLD to which it wishes to connect, so that, for example, a Non-AP STA belonging to the Non-AP MLD can transmit a connection request frame to an Affiliated AP belonging to the AP-MLD. The Affiliated AP that receives the connection request frame judges whether or not to permit a connection with the Non-AP STA, and transmits a connection response frame to notify the result. In addition to a status code indicating whether or not the connection process is possible, the connection response frame contains an AID for identifying the Non-AP STA if the connection is permitted. The Affiliated AP can manage connections with multiple Non-AP STAs by setting different AP-MLD IDs, Link IDs, or AIDs for each Non-AP STA that it has issued a connection permission to.In other words, by including an MLE in a connection frame, it becomes possible to connect to multiple links with a single connection frame.

[0044] First, FIG. 15 shows an example of grasping surrounding Affiliated APs in the case of multi-link. In FIG. 15, as an example of wireless communication devices corresponding to MLD, MLD wireless communication device 4-1 (also called MLD terminal device 4-1 or Non AP-MLD 4-1) and MLD wireless communication device 3-1 (also called MLD base station device or AP-MLD 3-1) are shown, but this is not limited thereto, and the number of links formed between Non AP-MLD 4-1 and AP-MLD 3-1 in MLO can be any number of two or more. The carrier frequency of the link can be set to 2.4 GHz band, 5 GHz band, 6 GHz band, 60 GHz band, etc., respectively, but it changes according to the laws and regulations of each country. The process of grasping surrounding Affiliated APs will be described. Beacon frames 11-1 to 11-3 transmitted by AP-MLD to Non AP-MLD indicate passive scanning notified for each link. The beacon frames 11-1 to 11-3 may include information elements having information on the capabilities of the surrounding Affiliated APs and AP-MLDs, and on the surrounding Affiliated APs and AP-MLDs. In the case of an AP that does not support multi-link, the AP may exchange information for identifying the surrounding Affiliated APs with other APs using one link in the same procedure as when using a beacon frame.

[0045] In the example of the communication method shown in FIG. 15, an example is shown in which a frame is transmitted in a form in which information on the substation apparatus other than the own apparatus and the sub-access point apparatus is aggregated on one link between the substation apparatus 20000-6 (Affiliated STA#1) and the sub-access point apparatus 20000-2 (Affiliated AP#1). The ML probe request frame 11-4 is transmitted from the Non-AP STA to the Affiliated AP, and indicates active scanning. The ML probe request frame 11-4 can include information similar to that of the beacon frames 11-1 to 11-3. The Affiliated AP transmits an ML probe response frame 11-5 in response to the ML probe request frame 11-4 transmitted from the Non-AP STA. Although not shown in FIG. 15, the probe request frame may be transmitted multiple times for each link between the Non-AP-MLD4-1 and the AP-MLD3-1, as in the case of the beacon frame, and the ML probe request frame 11-4 may be used in another implementation.

[0046] Also, Fig. 15 shows authentication processing and connection processing with surrounding Affiliated APs in the case of multi-link, and assumes that information of multiple links is bundled into one link between AP-MLD and Non-AP-MLD and transmitted at once. For example, Fig. 15 shows an example in which Affiliated STA#1 transmits an authentication request frame 11-6 to Affiliated AP#1 to which it wishes to connect, and the authentication request frame 11-6 also includes information on Affiliated STA#2-#3. Affiliated AP#1 that receives the authentication request frame transmits an authentication response frame 11-7 to Affiliated STA#1 that includes a status code indicating whether authentication is possible or not. Thereafter, in order to move to connection processing between Non-AP MLD and AP-MLD, Affiliated STA#1 can transmit a connection request frame 11-8 to Affiliated AP#1, which is the authenticated connection destination, which has been authenticated. Affiliated AP#1, which has received the connection request frame 11-8, sets information for identifying the Non-AP STA, such as a Link ID or AID, in addition to a status code indicating whether or not the connection process is possible, and transmits a connection response frame 11-9 to Affiliated STA#1. In this manner, the connection process between Non-AP MLD and AP-MLD is performed. Note that AP-MLD3-1 can manage connections with a plurality of Affiliated STA#1-3 by setting different Link IDs or AIDs to Affiliated STA#1-3 to which it has issued connection permission. After the multi-link setup, Non-AP-MLD4-1 and AP-MLD3-1 can change or release the multi-link, and can transmit a multi-link (Multi-Link: ML) change request frame 11-10 and a multi-link (Multi-Link: ML) change response frame 11-11 using an information element such as a Reconfiguration Multi-Link element, for example.The ML change request frame 11-10 and the ML change response frame 11-11 in FIG. 15 show an example of changing / removing settings related to the multilink.

[0047] After the connection process is completed, the AP and STA perform actual data transmission. In the IEEE802.11 system, a distributed coordination function (DCF), a point coordination function (PCF), and their extended mechanisms (enhanced distributed channel access (EDCA) and hybrid coordination function (HCF), etc.) are defined. In the following, an example is explained in which the AP transmits a signal to the STA using DCF, but the same applies to AP-MLD and Non AP-MLD, M-AP and S-AP in inter-AP coordination, and between S-APs, and is not limited to a specific communication method or connection form.

[0048] In DCF, the AP and STA perform carrier sense (CS) to check the usage status of the wireless channel around the AP before communication. For example, when the AP, which is a transmitting station, receives a signal higher than a predetermined clear channel assessment level (CCA level) on the wireless channel, it postpones the transmission of a transmission frame on the wireless channel. In the following, a state in which a signal of CCA level or higher is detected on the wireless channel is called a busy state, and a state in which a signal of CCA level or higher is not detected is called an idle state. In this way, the CS performed by each device based on the power of the signal actually received (received power level) is called a physical carrier sense (physical CS). The CCA level is also called a carrier sense level (CS level) or a CCA threshold (CCA threshold: CCAT). When the AP and STA detect a signal of CCA level or higher, they start to demodulate at least the signal of the PHY layer.

[0049] The AP performs carrier sensing for an inter frame space (IFS) that corresponds to the type of frame to be transmitted, and determines whether the wireless channel is busy or idle. The period during which the AP performs carrier sensing varies depending on the frame type and subframe type of the frame the AP is about to transmit. In the IEEE802.11 system, multiple IFS with different periods are defined, including the short IFS (SIFS) used for frames with the highest priority, the polling interframe space (PCF IFS: PIFS) used for frames with relatively high priority, and the distributed control IFS (DCF IFS: DIFS) used for frames with the lowest priority. When the AP transmits a data frame using DCF, the AP uses DIFS.

[0050] After waiting for the DIFS, the AP waits for a random backoff time to prevent frame collision. In the IEEE802.11 system, a random backoff time called a contention window (CW) is used. In CSMA / CA, it is assumed that a frame transmitted by a certain transmitting station is received by a receiving station without interference from other transmitting stations. Therefore, if transmitting stations transmit frames at the same timing, the frames collide with each other and the receiving station cannot receive them correctly. Therefore, frame collision is avoided by having each transmitting station wait for a randomly set time before starting transmission. When the AP determines that the wireless channel is idle by carrier sense, it starts counting down the CW, and only when the CW reaches 0 can it acquire the right to transmit and transmit a frame to the STA. Note that if the AP determines that the wireless channel is busy by carrier sense during the CW countdown, it stops the CW countdown. Then, when the wireless channel becomes idle, the AP resumes the countdown of the remaining CW following the previous IFS.

[0051] Next, the details of PPDU frame reception will be described. The STA, which is a receiving station, receives the PPDU frame, reads the PHY header of the PPDU frame, and demodulates the received frame. The STA can then determine whether the PPDU frame is addressed to the STA by reading the MAC header of the demodulated signal. The STA can also determine the destination of the PPDU frame based on information written in the PHY header (for example, a group identification number (Group identifier: GID, Group ID) written in VHT-SIG-A).

[0052] When a STA judges that the received PPDU frame is addressed to itself and demodulates the PPDU frame without error, it must transmit an ACK frame to the AP, which is the transmitting station, indicating that the PPDU frame has been correctly received. The ACK frame is one of the highest priority frames that is transmitted only by waiting for the SIFS period (no random backoff time is taken). The AP ends a series of communications by receiving the ACK frame transmitted from the STA. If the STA does not correctly receive the PPDU frame, the STA does not transmit the ACK frame. Therefore, if the AP does not receive an ACK frame from the receiving station for a certain period (SIFS + ACK frame length) after transmitting a PPDU frame, it terminates the communication as it has failed. In this way, the end of one communication (also called a burst) in the IEEE802.11 system is always determined by the presence or absence of the reception of an ACK frame, except in special cases such as the transmission of a notification signal such as a beacon frame or the use of fragmentation to divide transmission data.

[0053] When the STA determines that the received PPDU frame is not addressed to the STA, the STA sets a network allocation vector (NAV) based on the length of the PPDU frame described in the PHY header or the like. The STA does not attempt communication during the period set in the NAV. In other words, the STA performs the same operation as when the STA determines that the wireless channel is busy by the physical CS during the period set in the NAV, so communication control by the NAV is also called virtual carrier sense (virtual CS). In addition to being set based on the information described in the PHY header, the NAV is also set by an RTS frame, which is a request to send introduced to solve the hidden terminal problem, and a CTS frame, which indicates that the device is ready to receive.

[0054] A wireless medium used by a wireless communication system can be divided into a plurality of resource units (RUs). FIG. 16 is a schematic diagram showing an example of a division state of a wireless medium. For example, in resource division example 1, a wireless communication device can divide a frequency resource (subcarrier) which is a wireless medium into nine RUs. Similarly, in resource division example 2, a wireless communication device can divide a subcarrier which is a wireless medium into five RUs. Of course, the resource division example shown in FIG. 16 is merely an example, and for example, a plurality of RUs can be configured with different numbers of subcarriers. In addition, the wireless medium divided into RUs can include not only frequency resources but also spatial resources. A wireless communication device, for example, an AP, can transmit PPDU frames to a plurality of STAs (for example, a plurality of STAs) simultaneously by placing PPDU frames addressed to different STAs in each RU. The AP can write information (resource allocation information) indicating the division state of the wireless medium in the PHY header of a PPDU frame transmitted by the device itself as common control information. Furthermore, the AP can write information indicating the RU in which the PPDU frame addressed to each STA is placed (resource unit assignment information) as unique control information in the PHY header of the PPDU frame transmitted by the AP itself.

[0055] Furthermore, multiple wireless communication devices, for example multiple STAs, can transmit PPDU frames simultaneously by placing frames in the assigned RUs and transmitting them. After receiving a frame (Trigger frame: TF) containing trigger information transmitted from an AP, multiple STAs can transmit the PPDU frame after waiting for a predetermined period of time. Each STA can grasp the RU assigned to itself based on the information written in the TF. Furthermore, each STA can acquire an RU by random access based on the TF.

[0056] A wireless communication device, for example, an AP, can simultaneously allocate multiple RUs to one STA. The multiple RUs can be configured with consecutive subcarriers or non-consecutive subcarriers. The AP can transmit one PPDU frame using the multiple RUs allocated to one STA, and can allocate multiple PPDU frames to different RUs for transmission. At least one of the multiple PPDU frames can be a PPDU frame including common control information for multiple STAs that transmit resource allocation information.

[0057] A single wireless communication device, for example, a STA, can be assigned multiple RUs by an AP. The STA can transmit one PPDU frame using the assigned multiple RUs. The STA can also transmit multiple PPDU frames by assigning each PPDU frame to a different RU using the assigned multiple RUs. The multiple PPDU frames can be PPDU frames of different frame types.

[0058] An AP can assign multiple AIDs to one STA. An AP can assign RUs to the multiple AIDs assigned to one STA. An AP can transmit different PPDU frames to the multiple AIDs assigned to one STA using the assigned RUs. The different PPDU frames can be PPDU frames of different frame types.

[0059] One STA can be assigned multiple AIDs by the AP. One STA can be assigned RUs for each of the multiple assigned AIDs. One STA recognizes all RUs assigned to the multiple AIDs assigned to the own device as RUs assigned to the own device, and can transmit one PPDU frame using the multiple assigned RUs. Also, one STA can transmit multiple PPDU frames using the multiple assigned RUs. At this time, the multiple PPDU frames can be transmitted with information indicating the AIDs associated with the assigned RUs written therein.

[0060] In the case of multi-link, TID-to-Link Mapping can be implemented to assign a TID to each link. Note that multiple TIDs can be assigned to the link. By using the TID-to-Link Mapping, the Affiliated AP can transmit a PPDU frame on a link to which the same TID as that of the PPDU frame including the TID is assigned. For DL ​​in inter-AP cooperation, when transmitting a data frame from an M-AP to a STA, the TID-to-Link Mapping can be used to specify which S-AP the data frame should be transmitted through. On the other hand, for UL, when a STA has multiple links, the TID-to-Link Mapping can be used to specify which S-AP the data frame should be transmitted through. Similarly, the TID-to-Link Mapping can also be used to specify which S-AP the STA should transmit a data frame through to the M-AP.

[0061] The wireless communication device has either or both of a function to transmit and a function to receive a PPDU frame. An example of a PPDU frame structure transmitted by a wireless communication device, for example, an AP, is shown in FIG. 17, but is not limited thereto. A PPDU frame conforming to the IEEE802.11a / b / g standard includes an L-STF, an L-LTF, an L-SIG, and a Data frame (MAC Frame, MAC frame, payload, data section, data, information bits, etc.). A PPDU frame conforming to the IEEE802.11n standard includes an L-STF, an L-LTF, an L-SIG, an HT-SIG, an HT-STF, an HT-LTF, and a Data frame. A PPDU frame conforming to the IEEE802.11ac standard includes an L-STF, an L-LTF, an L-SIG, a VHT-SIG-A, a VHT-STF, a VHT-LTF, a VHT-SIG-B, and a part or all of a MAC frame. The PPDU frame of the IEEE802.11ax standard is configured to include some or all of the following: L-STF, L-LTF, L-SIG, RL-SIG in which L-SIG is repeated over time, HE-SIG-A, HE-STF, HE-LTF, HE-SIG-B, and Data frames. The PPDU frame considered in the IEEE802.11be standard is configured to include some or all of the following: L-STF, L-LTF, L-SIG, RL-SIG, U-SIG, EHT-SIG, EHT-STF, HET-LTF, and Data frames.

[0062] The L-STF, L-LTF, and L-SIG enclosed by dotted lines in Fig. 17 are configurations commonly used in the IEEE 802.11 standard (hereinafter, the L-STF, L-LTF, and L-SIG are also collectively referred to as the L-header). For example, a wireless communication device compatible with the IEEE 802.11a / b / g standard can properly receive the L-header in a PPDU frame compatible with the IEEE 802.11n / ac standard. A wireless communication device compatible with the IEEE 802.11a / b / g standard can receive a PPDU frame compatible with the IEEE 802.11n / ac standard by regarding it as a PPDU frame compatible with the IEEE 802.11a / b / g standard. However, wireless communication devices that comply with the IEEE 802.11a / b / g standards cannot demodulate the PPDU frame that complies with the IEEE 802.11n / ac standards, which follows the L-header, and therefore cannot demodulate information related to the transmitter address (TA: Transmitter Address), receiver address (RA: Receiver Address), or the Duration / ID field used to set the NAV.

[0063] Even during a receiving operation of a PPDU frame, the wireless communication device can receive a part of the PPDU frame other than the PPDU frame, such as a preamble, L-STF, L-LTF, PLCP header, etc., which are defined by IEEE 802.11. When the wireless communication device detects a part of a PPDU frame other than the PPDU frame during a receiving operation of the PPDU frame, the wireless communication device can update a part or all of the information related to the destination address, the source address, the PPDU frame, etc. [First embodiment]

[0064] In the description of the present embodiment regarding the cooperation between APs mainly configured by STAs, the frame is defined as a PPDU frame having a management frame unless otherwise limited, but it can also be applied to a data frame or a control frame by including a field similar to that of the management frame. FIG. 1 shows an example of a wireless communication system according to the present embodiment, but is not limited thereto. For example, although wireless communication systems 3-1, 3-2, and 3-3 are each a BSS, they show a BSS network formed by cooperation between APs. Hereinafter, wireless communication devices 1-1, 1-2, and 1-3 can be an access point device, a base station device, an AP-MLD, etc. Wireless communication devices 2-1, 2-2, and 2-3 can be a station device, a terminal device, a Non AP-MLD, etc.

[0065] In FIG. 1, a wireless communication system 3-1 includes wireless communication devices 1-1 to 1-3 and wireless communication devices 2-2 to 2-3. A wireless communication system 3-2 includes a wireless communication device 1-2 and wireless communication devices 2-1 to 2. A wireless communication system 3-3 includes a wireless communication device 1-3 and wireless communication devices 2-1 and 2-3. The wireless communication systems 3-1 to 3 form different BSSs, but this does not necessarily mean that the ESSs (Extended Service Sets) are different. An ESS indicates a service set that forms a LAN (Local Area Network). In other words, wireless communication devices that belong to the same ESS can be considered to belong to the same network from a higher layer. In addition, the BSSs are coupled via a DS (Distribution System) to form an ESS. Each of the wireless communication systems 3-1, 3-2, and 3-3 can further include a plurality of wireless communication devices. The wireless communication system according to this embodiment can be provided with wireless communication systems 3-2 and 3-3 in addition to the wireless communication system 3-1 by using multi-AP coordination, and communication with wireless communication devices 2-1 to 3 can be performed using any one or more of the wireless communication devices 1-1 to 3 by using the multi-AP coordination.

[0066] An example of a wireless communication device and a wireless communication method assumed for explaining the present embodiment is shown. Fig. 2 and Fig. 3 are examples of a wireless communication device and a wireless communication method for setting cooperation between APs configured mainly by STAs. Fig. 2 shows an example of a wireless communication device 10000-1, and Fig. 3 shows an example of an autonomous distributed control unit 10002-1. The wireless communication device includes an upper layer unit 10001-1, a MAC layer unit 10001a-1, an autonomous distributed control unit 10002-1, a transmitting unit 10003-1, a physical layer frame generating unit 10003a-1, a wireless transmitting unit 10003b-1, a receiving unit 10004-1, a wireless receiving unit 10004a-1, a signal demodulating unit 10004b-1, and an antenna unit 10005-1. The autonomous distributed control unit 10002-1 includes a CCA unit 10002a-1, a backoff unit 10002b-1, and a transmission determining unit 10002c-1 shown in Fig. 3.

[0067] The receiving unit 10004-1 of the wireless communication device receives a radio frequency signal by an antenna unit 10005-1, and generates a physical layer signal from the radio frequency signal by a wireless receiving unit 10004a-1. The wireless receiving unit 10004a-1 notifies the CCA unit 10002a-1 of the autonomous distributed control unit 10002-1 of the demodulation result of the preamble, and notifies the transmission decision unit 10002c-1 of the reception of the physical layer signal. The signal demodulation unit 10004b-1 performs error correction decoding and the like, and demodulates the PPDU frame from the physical layer signal to extract any or all of the physical layer header, MAC header, and data portion, and transmits them to the upper layer unit 10001-1.

[0068] When the receiving unit 10004-1 receives an information element (such as a Neighbor report element or a Reduced Neighbor report element) including information on the capability of an AP or information on surrounding APs, the receiving unit 10004-1 transmits the information to the upper layer unit 10001-1. Based on the information, the upper layer unit 10001-1 can set information related to an inter-AP cooperation method (a field related to the inter-AP cooperation method, information indicating two or more frequency band candidates to be included in the field, information indicating candidates for the inter-AP cooperation method corresponding to the candidates, etc.).

[0069] The upper layer unit 10001-1 of the wireless communication device 10000-1 transfers the generated packets to the MAC layer and generates an MPDU or an A-MPDU (Aggregated MAC Protocol Data Unit) that aggregates MPDUs. The MAC layer unit 10001a-1 transfers the MPDU to a physical layer frame generation unit 10003a-1 of the transmission unit 10003-1.

[0070] The CCA unit 10002a-1 of the autonomous distributed control unit 10002-1 performs carrier sense, judges the channel state (idle / busy), and notifies the backoff unit 10002b-1 of the result. When the transmission decision unit 10002c-1 receives a physical layer signal, it waits for a frame interval (Inter frame space: IFS). The transmission decision unit 10002c-1 can use DIFS as a frame interval, and when it is notified that a PPDU frame transmission is to be started, it requests the backoff unit 10002b-1 to start counting down the backoff counter after the DIFS has elapsed. Note that the backoff unit 10002b-1 can start counting down the backoff counter when the channel state is idle and the transmission decision unit 10002c-1 is requested to start counting down the backoff counter. On the other hand, when the channel state is busy, it can suspend counting down the backoff counter. The backoff unit 10002b-1 notifies the transmission decision unit 10002c-1 of the value of the backoff counter. When the value of the backoff counter is 0, the transmission decision unit 10002c-1 generates a PPDU frame from the physical layer signal in a physical layer frame generation unit 10003a-1 of the transmission unit 10003-1. The PPDU frame is modulated and coded and transmitted to the wireless transmission unit 10003b-1. The wireless transmission unit 10003b-1 converts the PPDU frame into a signal in a radio frequency band, generates a physical layer signal, and transmits the physical layer signal via an antenna unit.

[0071] The transmitting unit 10003-1 can include information on the inter-AP coordination method transmitted from the upper layer unit 10001-1 in a PPDU frame in the physical layer frame generating unit 10003a-1. The PPDU frame is modulated and coded and transmitted to the wireless transmitting unit 10003b-1. The wireless transmitting unit 10003b-1 converts the PPDU frame into a signal in a wireless frequency band, generates a physical layer signal, and transmits the physical layer signal via an antenna unit.

[0072] The wireless communication device and wireless communication method for setting up AP cooperation mainly composed of STAs in this embodiment are intended for communication between each STA (hereinafter also referred to as affiliated STA) constituting a multilink device and an AP in an AP cooperation state, unless otherwise limited, but can also be applied to communication between APs not in an AP cooperation state. FIG. 4 shows an example of a wireless communication device 10000-2 according to this embodiment in which FIG. 2 and FIG. 3 are made compatible with multilink. Hereinafter, description of the same parts as those in the block diagrams shown in FIG. 2 and FIG. 3 will be omitted. The wireless communication device 10000-2 is an example having two or more wireless frequency bands (wireless frequency bands A to Z), each of which is composed of an independent transmitting unit and receiving unit. In the following embodiments, description will be given assuming that FIG. 4 is applied, but is also valid for FIG. 2 and FIG. 3. The MAC layer unit 10001a-1 in the upper layer unit 10001-1 in FIG. 4 is also referred to as a control unit for setting up AP cooperation. The control unit of the STA can generate a probe request frame, a probe response frame, and a trigger frame, which will be described later. In this embodiment, the probe request frame is also called a Multi-AP Coordination request frame, the probe response frame is also called a Multi-AP Coordination response frame, and the trigger frame is also called a Multi-AP Coordination trigger frame.

[0073] An outline of an example of an embodiment according to the present invention will be described. The first embodiment relates to a Non-AP STA (hereinafter, STA) constituting a multilink device that transmits and receives frames for setting inter-AP cooperation. The STA includes a transmitting unit, a receiving unit, and a control unit. The following describes an outline of the operation of the transmitting side of the STA in this embodiment, the operation of the receiving side, and the operation of the transmitting side with respect to the operation of the receiving side. First, in the operation of the transmitting side, the control unit of the STA generates a probe request frame including a field related to an inter-AP cooperation method, and includes two or more frequency band candidates and inter-AP cooperation method candidates corresponding to the candidates in the field. Thereafter, in order to search for an AP capable of implementing the inter-AP cooperation desired by the STA, the transmitting unit of the STA broadcasts a probe request frame including a field related to the inter-AP cooperation method.

[0074] Next, in the operation of the receiving side, the receiving unit of the STA receives a probe response frame in response to the probe request frame including a field related to the inter-AP cooperation method, and by receiving the probe response frames from two or more APs, the receiving unit of the STA can grasp the APs capable of implementing the inter-AP cooperation desired by the own device. The APs capable of implementing the inter-AP cooperation are determined based on a field related to the possibility of inter-AP cooperation included in the probe response frame. The field related to the possibility of inter-AP cooperation includes information indicating two or more frequency band candidates and information related to the possibility of the inter-AP cooperation method corresponding to the candidates. For example, if the information related to the possibility indicates the possibility, it means that the AP is capable of implementing the inter-AP cooperation method desired by the STA.

[0075] Finally, in the operation of the transmitting side after receiving the probe response frame, the STA selects two or more APs that satisfy the inter-AP cooperation method desired by the own device based on a field regarding the possibility of inter-AP cooperation included in the probe response frame. The control unit of the STA generates a probe request frame for the two or more APs, and includes a field regarding the timing of starting communication in the probe request frame. Furthermore, the field includes information indicating the inter-AP cooperation method and information indicating the timing of starting communication with the AP by the cooperation method. The transmitting unit of the STA transmits the probe request frame to two or more APs that satisfy the inter-AP cooperation method desired by the own device by group cast / multicast. In this way, the STA can start communication with two or more APs based on the timing of starting communication. Note that the names of the field regarding the inter-AP cooperation method, the field regarding the possibility of inter-AP cooperation, and the field regarding the timing of starting communication are not limited to these as long as they are the same as the information included in each of the fields. The information included in the field regarding the possibility of inter-AP cooperation / the field regarding the timing of starting communication and the field regarding the possibility of inter-AP cooperation may be included in the probe request frame and the probe response frame, respectively, as information elements.

[0076] Also, the control unit of the STA may generate a trigger frame instead of a probe request frame including a field related to the timing of starting communication. However, the control unit of the STA may include a field related to the timing of starting communication in the trigger frame, and include information indicating an inter-AP cooperation method and information indicating the timing of starting communication with the AP by the cooperation method in the field. In another implementation form, the field related to the timing of starting communication may be omitted, and the AP may start communication after a predetermined IFS from the end of the trigger frame. The transmission unit of the STA transmits the trigger frame to two or more APs that satisfy the inter-AP cooperation method desired by the STA. In this way, the STA can start communication with two or more APs based on the timing of starting communication or the end of reception of the trigger frame.

[0077] In this embodiment, the STA knows two or more APs that enable inter-AP cooperation by broadcasting a probe request frame including a field related to the inter-AP cooperation method, but the probe request frame may be transmitted by group cast / multicast. As an example of knowing two or more APs that enable inter-AP cooperation by group cast / multicast, first, the control unit of the STA designates two or more APs as the destination of group cast / multicast to an address indicated in the address field of the MAC header of the probe request frame including a field related to the inter-AP cooperation method. For example, the control unit of the STA can designate an address indicating two or more APs, or designate an address indicating each AP in the two or more APs, to an address indicated in the address field of the MAC header. Next, the transmission unit of the STA group casts / multicasts a probe request frame including a field related to the inter-AP cooperation method to two or more APs. Then, if the receiving unit of the STA cannot receive a probe response frame from the two or more APs, or if the field related to the possibility of inter-AP cooperation included in the probe response frame received from the two or more APs indicates no, the STA knows that inter-AP cooperation is not possible. In this way, the STA can find out whether or not inter-AP cooperation is possible with the AP by transmitting the probe request frame, which is normally transmitted by broadcast, by groupcast / multicast.

[0078] In AP cooperation mainly configured by APs, exchange of beacon frames for setting and resetting AP cooperation between M-AP and S-AP, or exchange of frames necessary for setting AP cooperation between M-AP and S-AP, etc. must be performed every time communication between APs or with STAs connected to AP cooperation becomes impossible. The overhead related to the exchange of frames is a problem that reduces the transmission efficiency of the entire wireless communication system. On the other hand, in AP cooperation mainly configured by STAs disclosed in this embodiment, it is possible for STAs to set an AP cooperation method while suppressing overhead such as exchange of frames necessary for setting AP cooperation between M-AP and S-AP, and an improvement in the transmission efficiency of the entire wireless communication system can be expected. In the first embodiment, a form of setting and communication method of AP cooperation using a probe request frame, a probe response frame, and a trigger frame for AP cooperation mainly configured by STAs is described.

[0079] A STA constituting a multi-link device (hereinafter also referred to as an Affiliated STA or a Non-AP STA) broadcasts a probe request frame including a field related to an inter-AP cooperation method in order to grasp two or more APs (hereinafter also referred to as an Affiliated AP or an AP-MLD) that enable inter-AP cooperation. FIG. 5(a) shows an example of a probe request frame transmitted by broadcast, which is an ML probe request frame of FIG. 14(a) including a field related to an inter-AP cooperation method. The field related to the inter-AP cooperation method includes information indicating two or more frequency band candidates and information indicating candidates of an inter-AP cooperation method corresponding to the candidates. For example, the two or more frequency band candidates can include frequency bands such as 2.4 GHz, 5 GHz, and 60 GHz, and each of the frequency bands can be associated with a Link ID. In addition, since an inter-AP cooperation method corresponding to each of the frequency bands can be set for the candidates of inter-AP cooperation, they can be associated with each Link ID. For example, as shown in the example of FIG. 5(a), when Joint Transmission (J-TX) or the like is set as a candidate for AP coordination method for 2.4 GHz in the field related to AP coordination method, the combination is linked to one Link ID. The Link ID is also linked to the Per-STA Profile of the Probe Request Multi-Link Element. Meanwhile, a broadcast address can be specified in the address field of the MAC header in FIG. 5(a). The probe request frame in FIG. 5(a) can include various elements. The frame in FIG. 5 can also include an element related to operation / capability according to the standard of the wireless communication device.

[0080] FIG. 5(b) is an example of a probe response frame including a field regarding the possibility of inter-AP cooperation, and is obtained by including a field regarding the possibility of inter-AP cooperation in the ML probe response frame of FIG. 14(b). The receiver of the STA receives the probe response frame from two or more APs, and can recognize two or more APs that enable inter-AP cooperation based on the field regarding the possibility of inter-AP cooperation. The field regarding the possibility of inter-AP cooperation includes information indicating two or more frequency band candidates and information indicating the possibility of inter-AP cooperation method candidates corresponding to the candidates. The field regarding the possibility of inter-AP cooperation can include frequency bands such as 2.4 GHz, 5 GHz, and 60 GHz as two or more frequency band candidates, as shown in FIG. 5(b), and each of the frequency bands can be associated with each link by a Link ID. As an example of grasping two or more APs that can perform inter-AP cooperation, if the STA sets the candidate inter-AP cooperation method for 2.4 GHz as J-TX in the probe request frame of FIG. 5(a) transmitted by broadcast, the field regarding the inter-AP cooperation in the probe response frame of FIG. 5(b) contains information indicating whether J-TX is possible at 2.4 GHz. In this way, the STA can grasp two or more APs that indicate that inter-AP cooperation is possible. The address field of the MAC header of FIG. 5(b) can specify the address of the STA that is the sender of the probe request frame of FIG. 5(a). The address of the STA can be specified by a Link ID, an AID, or the like. Note that, when the STA configures an MLD, information regarding each link in the MLD is described in the Per-STA Profile of the Basic Multi-Link Element and can be managed by the Link ID. Note that the probe response frame of FIG. 5(b) can include various Elements, etc.

[0081] After identifying two or more APs that can perform inter-AP cooperation based on the probe response frame of FIG. 5(b), the STA can transmit the trigger frame of FIG. 6(a) or the probe request frame of FIG. 6(b) by groupcast / multicast in order to start communication with two or more APs that can perform inter-AP cooperation desired by the STA. FIG. 6 shows an example of a trigger frame and a probe request frame including a field related to the timing of starting communication. The trigger frame of FIG. 6(a) is a frame that can be transmitted instead of the probe request frame shown in FIG. 6(b) and can include information similar to that of the probe request frame. However, the trigger frame does not need to include a Probe Request Multi-Link Element. The control unit of the STA generates a probe request frame including a field related to the timing of starting communication, or a trigger frame including a field related to the timing of starting communication. The field related to the timing of starting communication included in the probe request frame or the trigger frame includes information indicating an inter-AP cooperation method and the timing of starting communication with the AP using the cooperation method. The address indicated in the address field of the MAC header of the probe request frame or the trigger frame can be an address indicating two or more APs desired by the STA, or an address indicating each AP in the two or more APs desired by the STA. The transmitter of the STA can transmit the probe request frame or the trigger frame. When the STA configures an MLD, information regarding each link in the MLD is described in the Per-STA Profile of the Probe Request Multi-Link Element and can be managed by the Link ID.

[0082] An example of a communication method between a STA constituting a multi-link device and two or more APs in this embodiment is shown in Fig. 7. The MLD wireless communication device 5-1 (30000-1) is also called Non-AP MLD 5-1. The Non-AP MLD 5-1 is an MLD composed of Affiliated STA#1-#3 (30000-2 to 4) which are substation devices. In the example of Fig. 7, 13-1 and 13-2 represent that in the upper layer of the Non-AP MLD 5-1, Affiliated STA#1-Affiliated STA#2 and Affiliated STA#2-Affiliated STA#3, links capable of exchanging control information in the upper layer are connected, but this is not limited thereto. For example, a link connected by Affiliated STA#1-Affiliated STA#3, etc. can also be considered. In addition, in the example of FIG. 7, in the access point device AP#1-AP#3 (300000-5 to 7), AP#1-AP#2 and AP#2-AP#3 are in an AP-to-AP cooperation state as indicated by 13-3 and 13-4, but this is not limited thereto, and for example, it is also possible to consider that AP#1-AP#3 are in an AP-to-AP cooperation state. The access point device and the Non-AP MLD 5-1 can also have a plurality of frequency bands. The Non-AP MLD 5-1 can have frequency bands of 2.4 GHz, 5 GHz, and 60 GHz for Affiliated STA#1-#3, respectively, but is not limited to this combination.

[0083] FIG. 7 shows an example of a communication method in which a STA recognizes two or more APs capable of performing inter-AP cooperation and starts communication with two or more APs that realize the inter-AP cooperation desired by the STA. In the example of FIG. 7, a probe request frame 13-8 (inter-AP cooperation request frame) shows a probe request frame including a field related to an inter-AP cooperation method corresponding to FIG. 5(a). A probe response frame 13-9 (inter-AP cooperation response frame) shows a probe response frame including a field related to whether inter-AP cooperation is possible corresponding to FIG. 5(b). Also, a probe request frame 13-10 (inter-AP cooperation setting frame) shows a probe request frame including a field related to the timing of starting communication corresponding to FIG. 6(b). Note that, instead of the probe request frame 13-10, a trigger frame 13-11 (inter-AP cooperation trigger frame) including a field related to the timing of starting communication shown in FIG. 6(a) can also be used. As shown above, a trigger frame that omits the field related to the timing of starting communication may be used as the timing of starting communication (also referred to as communication start timing) based on a predetermined IFS from the end of the trigger frame. In addition, 13-12 represents a data frame. In this embodiment, the STA collects information about the APs (information elements including AP capabilities and information about surrounding APs, etc.) by receiving beacon frames 13-5, 13-6, and 13-7 from each AP, and may set information elements indicating candidates for inter-AP cooperation methods in the probe request frame 13-8, information specifying multiple APs requesting inter-AP cooperation, etc.

[0084] Based on the information element including the capability of the AP and the information of the surrounding APs included in the beacon frame, the STA can determine information indicating two or more frequency band candidates and information indicating the inter-AP cooperation method candidates corresponding to the candidates in the field of the inter-AP cooperation method of the probe request frame 13-8. However, in the unlikely event that the beacon frames 13-5, 13-6, and 13-7 do not include information on the AP desired by the STA, the STA can request the AP to include the missing information (information field or information element, etc.) in the beacon frame. If all the information on the AP desired by the STA is included in the beacon frame, the control unit of the STA can select two or more APs that can implement the inter-AP cooperation desired by the STA and generate the probe request frame 13-10. The probe request frame 13-10 may be a trigger frame 13-11. On the other hand, the control unit of the STA may generate the probe request frame 13-8, 13-10, or the trigger frame 13-11 without collecting information on the AP from the beacon frame. The AP may include, as part of the capability information related to inter-AP cooperation, an information element indicating a multicast (groupcast) address used for setting up inter-AP cooperation. Multiple multicast addresses for use in setting up inter-AP cooperation may be set. As one of the multicast addresses, a multicast address used by the STA to transmit a probe request frame to the AP in order to obtain information related to inter-AP cooperation may be set. In addition, as part of the multicast address, a multicast address used when transmitting a probe request frame or a trigger frame transmitted in relation to the timing of starting communication may be set. As part of other capability information, information indicating a combination of multiple APs indicated by the multicast address used when transmitting a probe request frame or a trigger frame transmitted in relation to the timing of starting communication may be included.

[0085] As an example of this embodiment shown in FIG. 7, when the STA identifies two or more APs that enable inter-AP cooperation, the STA may transmit the probe request frame 13-8 by groupcast / multicast instead of broadcasting. The control unit of the STA can set the destination of the groupcast / multicast by designating an address indicating two or more APs or designating an address indicating each AP in the two or more APs to an address indicated in the address field of the MAC header of the probe request frame 13-8. In this way, the transmission unit of the STA groupcasts / multicasts the probe request frame 13-8 to two or more APs. If the reception unit of the STA cannot receive the probe response frame 13-9 from the two or more APs, or if the field regarding whether inter-AP cooperation is possible or not included in the probe response frame 13-9 received from the two or more APs indicates no, the STA can know that inter-AP cooperation is impossible. In this way, the STA can know two or more APs that enable inter-AP cooperation even if the probe request frame 13-8 is transmitted by groupcast / multicast instead of broadcasting.

[0086] Also, in FIG. 7, the control unit of the AP that received the probe request frame 13-8 generates a probe response frame 13-9 including a field regarding whether or not inter-AP cooperation is possible, and can set the destination of the frame to the STA that is the sender of the probe request frame (for example, specified by AID or Link ID). The receiving unit of the STA receives the probe response frame including a field regarding whether or not inter-AP cooperation is possible. The control unit of the STA selects two or more APs that indicate that inter-AP cooperation is possible. The receiving unit of the STA may discard a probe response frame that does not include a field regarding whether or not inter-AP cooperation is possible, or an information element / information field that the STA has requested from the AP. The control unit of the STA generates a probe request frame 13-10 including a field regarding the timing of starting communication, and can set information indicating an inter-AP cooperation method and the timing of starting communication with the AP by the cooperation method in the field. The address indicated in the address field of the MAC header of the probe request frame 13-10 can be an address indicating two or more APs desired by the STA, or an address indicating each AP in the two or more APs desired by the STA. The transmitter of the STA transmits the probe request frame 13-10 by groupcast / multicast. In this way, the STA can start transmitting and receiving the data frame 13-12 with two or more APs in the inter-AP cooperation method desired by the STA after the timing to start communication specified by the probe request frame 13-10. Note that the trigger frame 13-11 may be used instead of the probe request frame 13-10.

[0087] In the first embodiment, the probe request frames 13-8, 13-10, the probe response frame 13-9, and the data frame 13-12 may be transmitted for each link or may be aggregated and transmitted in one link. Instead of the probe request frame 13-10, the trigger frame 13-11 may be used, and the trigger frame 13-11 may be transmitted for each link or may be aggregated and transmitted in one link. When the Non-AP MLD is an MLD consisting of two or more STAs (also called substation devices) and an AP is in a linked state with two or more APs, information on STAs other than the own STA and APs other than the own AP can be aggregated in one link. For example, in a Non-AP MLD consisting of two or more STAs, information on the two or more STAs and information requested by each of the STAs to the AP can be aggregated and transmitted in one probe request frame 13-8, 13-10, or a trigger frame 13-11 or a data frame 13-12. Even in the case of AP-MLD consisting of two or more APs, or AP-to-AP cooperation in which two or more APs cooperate with each other, information about the two or more APs can be aggregated and transmitted in a single probe response frame 13-9 or data frame 13-12.

[0088] In this embodiment, the STA transmits a probe request frame to obtain information on AP cooperation, and receives information on AP cooperation included in a probe response transmitted from the AP. The embodiment has been described in which the STA transmits a probe request or a trigger frame to indicate the timing of starting communication by AP cooperation, but the present invention is not limited to this embodiment. As an example, the STA may prepare an AP cooperation setting request frame, which is a control frame other than the probe request frame, to obtain information on AP cooperation, and the STA may transmit the AP cooperation setting request frame to one or more APs, and obtain information on AP cooperation from information included in an AP cooperation setting response frame transmitted from the one or more APs to the STA. When transmitting the AP cooperation setting request frame, the STA may transmit the frame by broadcasting with a BSSID or TxBSSID specified, or may transmit the frame by specifying a multicast address used for setting AP cooperation. The AP may transmit the AP cooperation setting response frame including an information field regarding the feasibility of AP cooperation. The AP may transmit the AP cooperation setting response frame when AP cooperation is possible, or may transmit the AP cooperation setting response frame including information indicating that AP cooperation is not possible when AP cooperation is not possible. The AP that sent the AP-to-AP cooperation setting response frame may then cooperate with other APs to transmit data to the STA after receiving a probe request frame or a trigger frame from the STA to which the AP-to-AP cooperation setting response frame was sent, indicating the timing to start communication through AP cooperation.

[0089] This embodiment can be applied even to an STA or AP having only one frequency band. For example, the control unit of the STA generates a probe request frame including a field related to an inter-AP cooperation method, and the field can include information indicating candidates for the inter-AP cooperation method after omitting information indicating two or more candidates for the frequency band. The control unit of the STA may include information indicating one frequency band and information indicating candidates for the inter-AP cooperation method in the field. Thereafter, in order to search for an AP capable of implementing the inter-AP cooperation desired by the STA, the transmission unit of the STA transmits the probe request frame by broadcast. Next, the reception unit of the STA receives a probe response frame in response to the probe request frame including a field related to the inter-AP cooperation method, and can grasp an AP capable of implementing the inter-AP cooperation desired by the device itself by receiving the probe response frame from two or more APs. The AP capable of implementing the inter-AP cooperation is determined based on a field related to the possibility of inter-AP cooperation included in the probe response frame. The field related to the possibility of inter-AP cooperation may omit information indicating two or more candidates for the frequency band, and may include information regarding the possibility of the inter-AP cooperation method. The field regarding the possibility of inter-AP cooperation may include information indicating one frequency band and information regarding the possibility of inter-AP cooperation method candidates. After that, the STA selects two or more APs that satisfy the inter-AP cooperation method desired by the own device based on the field regarding the possibility of inter-AP cooperation included in the probe response frame. The control unit of the STA generates a probe request frame for the two or more APs, and includes a field regarding the timing of starting communication in the probe request frame. Furthermore, the field includes information indicating the inter-AP cooperation method and information indicating the timing of starting communication with the AP by the cooperation method. The transmission unit of the STA transmits the probe request frame to two or more APs that satisfy the inter-AP cooperation method desired by the own device by group cast / multicast. In this way, even if the STA and the AP have only one frequency band, it is possible to start communication with two or more APs based on the timing of starting communication.

[0090] In addition, in the present embodiment, it is assumed that two or more APs communicating with a STA are in inter-AP cooperation, but the implementation of the present invention is not limited to this. In order to obtain information regarding inter-AP cooperation, the STA broadcasts a probe request frame including a field regarding the inter-AP cooperation method. An AP that receives a probe request frame including a field regarding the inter-AP cooperation method can transmit a frame requesting inter-AP cooperation to a neighboring AP before transmitting a probe response frame including a field regarding whether inter-AP cooperation is possible to the STA, and can set inter-AP cooperation. The frame requesting inter-AP cooperation can include a field similar to the field regarding the inter-AP cooperation method. A neighboring AP that receives a frame requesting inter-AP cooperation can transmit a response frame regarding inter-AP cooperation to the AP. The response frame regarding inter-AP cooperation can include a field similar to the field regarding whether inter-AP cooperation is possible. An AP that receives a response frame regarding inter-AP cooperation from a neighboring AP can select a specific AP from among the neighboring APs and transmit a frame for starting inter-AP cooperation. The frame for starting inter-AP cooperation can include a field similar to the field regarding the timing for starting communication. In this way, an AP that receives a probe request frame including a field related to an AP-to-AP cooperation method can start cooperation with a neighboring AP after the timing set in the frame for starting AP-to-AP cooperation, and can transmit a probe response frame including a field related to whether or not AP-to-AP cooperation is possible to a STA. Even if the STA and AP have one frequency band, the same procedure can be implemented. For example, in the control units of the STA and AP, information on two or more frequency band candidates may be omitted in the field related to the AP-to-AP cooperation method and the field related to whether or not AP-to-AP cooperation is possible, or information on one frequency band may be included instead.

[0091] This embodiment is an example of a method for configuring AP-to-AP cooperation by a STA, and contributes to improving the transmission efficiency of the entire wireless communication system by reducing overhead associated with beacon frames intended for configuring and reconfiguring AP-to-AP cooperation between an M-AP and an S-AP in AP-to-AP cooperation configured mainly around an AP, or the exchange of frames required for configuring AP-to-AP cooperation between an M-AP and an S-AP. [Second embodiment]

[0092] When a high frequency band is used to communicate between a STA connected to a BSS made up of a plurality of APs and the plurality of APs, it is necessary to adjust the beam direction appropriately by beam search before transmitting and receiving a data frame. For example, when considering transmitting and receiving frames in the millimeter wave or terahertz wave band as the high frequency band, the beam search needs to be performed again every time the wireless communication device moves, communication is interrupted due to radio wave shielding, or the SNR decreases due to a change in the propagation path environment. In this way, in communication using a high frequency band, not only is the spatial propagation loss larger than that of a non-high frequency band, for example, a microwave band, but the directionality of the radio wave is also stronger, so that it is necessary to appropriately adjust the antenna direction, etc. Since the beam width of millimeter waves and terahertz waves is finer than that of microwaves, the spatial resolution of the beam search must be improved, and as a result, the time required to search for a direction in which the quality of the beam is good for each sector becomes a problem. As an example of beam search in IEEE802.11, there is a case where sounding is performed before transmitting a data frame from an AP to a STA. The AP transmits an NDPA frame and an NDP frame as sounding frames to the STA. The AP can use a beacon frame to report its own AP's beamforming capabilities (number of antennas, number of spatial multiplexing, etc.) before the sounding. Meanwhile, the receiver of the STA judges the channel conditions based on the NDP frame and feeds back the results to the AP. The AP adjusts the beam to an appropriate sector direction based on the fed back information. In addition, Sector Level Sweep (SLS) and Beam Refinement Process (BRP) are examples of beam search in IEEE802.11ad, and there is a technique for narrowing down the beam direction in SLS and adjusting it to the optimal beam direction in BRP. In this way, in beam search, it is necessary to search for the optimal beam direction from both the AP and the STA.

[0093] The second embodiment of the present invention reduces overhead related to beam search in communication between two or more APs and a STA, and improves communication efficiency in wireless communication using a high frequency band (terahertz wave band). For example, in communication between a STA connected to a BSS consisting of two or more APs and the two or more APs, when the two or more APs and the STA have a high frequency band (terahertz wave band) and a non-high frequency band (microwave band), an AP that transmits a data frame to the STA in the high frequency band among the two or more APs may perform a beam search in advance. Following the beam search of the AP, the STA that receives the data frame may also perform a beam search. Furthermore, if the STA transmits a response frame to the AP in the same high frequency band after receiving the data frame in the high frequency band, a beam search may be performed. In other words, the present invention contributes to reducing overhead associated with beam search by having a STA transmit a response frame to an AP (hereinafter also referred to as the first AP) that transmits a data frame using a high frequency band, not in the same high frequency band, but in a non-high frequency band to an AP that is not the first AP (hereinafter also referred to as the second AP).

[0094] In the second embodiment of the present invention, the STA refers to an STA having two or more frequency bands, and the AP refers to two or more APs. Hereinafter, the STA may constitute one MLD having a high frequency band and a non-high frequency band. The two or more APs may include an AP using a high frequency band and an AP using a non-high frequency band.

[0095] An example of a wireless communication system assumed in the second embodiment is as shown in FIG. 8. Wireless communication systems 6-1 and 6-2 are separate BSSs, and each BSS indicates a network formed by an access point device 7-1 and an access point device 7-2. The access point devices 7-1 and 7-2 can also be applied to a base station device, an AP-MLD, and the like. Wireless communication devices 8-1 to 8-3 are connected to the access point devices 7-1 and 7-2, and each of the wireless communication devices can also be applied to a station device, a terminal device, a Non-AP-MLD, and the like. It is also possible for one of the access point devices 7-1 and 7-2 to be a master AP and the other to be a slave AP under the master AP, and it is also possible to communicate with the wireless communication devices 8-1 to 8-3 using inter-AP cooperation.

[0096] In the second embodiment, the STA can be provided with two or more frequency bands by a multi-link configuration as shown in Fig. 4, and can include a transmitter and a receiver corresponding to each of the frequency bands. For example, the STA can be provided with two or more radio frequency bands (radio frequency bands A to Z) like the wireless communication device 10000-2, and each of the bands can be configured with an independent transmitter and receiver. As an example, the AP can be configured as shown in Fig. 2, and the two APs can be provided with different frequency bands (high frequency band, non-high frequency band).

[0097] In addition, in the second embodiment, the MAC layer section in the upper layer section of Figures 2 and 4 can set a high frequency band (hereinafter also referred to as a first frequency band) and a non-high frequency band (hereinafter also referred to as a second frequency band) as the high frequency band for transmitting a data frame and the non-high frequency band for receiving a response frame to the data frame (hereinafter, the MAC layer section will also be referred to as a control section).

[0098] An example of a communication method in the second embodiment is shown. The STA is an STA that transmits and receives frames to and from the AP in a high frequency band and a non-high frequency band, and the AP indicates two APs. In the example of FIG. 9, the station device 40000-1 (STA#1) indicates an MLD having two frequency bands, a high frequency band 40000-3 and a non-high frequency band 40000-2. On the other hand, the access point devices 40000-4 and 40000-6 (AP#1 and AP#2) indicate APs having a non-high frequency band 40000-5 and a high frequency band 40000-7. The data frame 14-1 in FIG. 9 indicates that the data frame is transmitted from the AP#2 to the STA#1 using the high frequency band. Also, the response frame 14-2 indicates that the response frame is transmitted from the STA#1 to the AP#1 using the non-high frequency band. Note that the AP#1 and AP#2 may be AP-MLDs having a high frequency band and a non-high frequency band.

[0099] In the example of Figure 9, of the two APs, AP#2 is an AP (i.e., the first AP) that transmits a data frame 14-1 to STA#1 using a first frequency band, which is a high frequency band, and AP#1 is an AP (i.e., the second AP) that receives a response frame 14-2 to the data frame in a second frequency band, which is a non-high frequency band.

[0100] In the second embodiment, the STA includes a receiving unit, a transmitting unit, and a control unit, which are described below. The transmitting unit of the first AP transmits a data frame to the STA using a first frequency band. The receiving unit of the STA receives the data frame transmitted from the first AP using the first frequency band. The control unit of the STA generates a response frame to the data frame, and specifies an address other than the first AP that transmitted the data frame, i.e., the address of the second AP, in the address field of the MAC header of the response frame. The transmitting unit of the STA transmits the response frame to the second AP using the second frequency band.

[0101] In this embodiment, the second embodiment can be used to implement a part of the first embodiment. For example, in the STA of the first embodiment, when the STA starts communication with two APs capable of implementing the inter-AP cooperation method desired by the STA, the receiving unit of the STA can receive a data frame or the like from the first AP in a first frequency band. Furthermore, the transmitting unit of the STA can transmit a response frame to the data frame or the like to the second AP using a second frequency band.

[0102] The autonomous distributed control unit of the wireless communication device according to the present invention may perform uplink using a centralized control mechanism (Point Coordination Function: PCF) and its extended mechanisms (Enhanced distributed channel access: EDCA, Hybrid coordination function: HCF, etc.). For example, when performing PCF, the wireless communication device becomes a control station called a Point coordinator (PC) and periodically transmits a polling frame, and a terminal that receives the polling frame starts transmitting a PPDU frame.

[0103] The wireless communication device according to the present invention can communicate in a frequency band (frequency spectrum) called an unlicensed band, which does not require permission to use from a country or region, but the available frequency band is not limited to this. The wireless communication device according to the present invention can also be effective in a frequency band called a white band (for example, a frequency band allocated for television broadcasting but unused in some regions) that is not actually used for the purpose of preventing interference between frequencies even though permission to use the band for a specific service is given by a country or region, and in a shared spectrum (shared frequency band) that is expected to be shared by multiple operators.

[0104] The program that operates in the wireless communication device according to the present invention is a program that controls the CPU, etc. (a program that makes a computer function) so as to realize the functions of the above-mentioned embodiments of the present invention. Information handled by these devices is temporarily stored in the RAM during processing, and then stored in various ROMs or HDDs, and is read, modified, and written by the CPU as necessary. The recording medium that stores the program may be any of semiconductor media (e.g., ROM, non-volatile memory card, etc.), optical recording media (e.g., DVD, MO, MD, CD, BD, etc.), magnetic recording media (e.g., magnetic tape, flexible disk, etc.), etc. In addition, not only the functions of the above-mentioned embodiments are realized by executing the loaded program, but also the functions of the present invention may be realized by processing in cooperation with an operating system or other application programs, etc. based on instructions from the program.

[0105] In addition, when distributing the program on the market, the program can be stored in a portable recording medium and distributed, or transferred to a server computer connected via a network such as the Internet. In this case, the storage device of the server computer is also included in the present invention. In addition, a part or all of the communication device in the above-mentioned embodiment may be realized as an LSI, which is typically an integrated circuit. Each functional block of the communication device may be individually formed into a chip, or a part or all of the functional blocks may be integrated into a chip. When each functional block is formed into an integrated circuit, an integrated circuit control unit that controls them is added.

[0106] In addition, the method of integration is not limited to LSI, but may be a dedicated circuit or a general-purpose processor. In addition, if an integrated circuit technology that can replace LSI appears due to the advancement of semiconductor technology, it is also possible to use an integrated circuit based on that technology.

[0107] The present invention is not limited to the above-mentioned embodiment. The wireless communication device of the present invention is not limited to application to a mobile station device, but can be applied to stationary or non-movable electronic devices installed indoors or outdoors, such as AV equipment, kitchen equipment, cleaning and washing machines, air conditioners, office equipment, vending machines, and other household appliances.

[0108] Although an embodiment of the present invention has been described in detail above with reference to the drawings, the specific configuration is not limited to this embodiment, and designs and the like that do not deviate from the gist of the present invention are also included in the scope of the claims. [Industrial Applicability]

[0109] The present invention is suitable for use in a station device, an access point device, and a wireless communication method. [Explanation of symbols]

[0110] 1-1~1-3, 7-1, 7-2, 30000-5~30000-7, 40000-4, 40000-6 Access point device 2-1~2-3, 40000-1 Station equipment 3-1~3-3, 6-1~6-2 Wireless communication system 8-1~8-3, 10000-1, 10000-2 Wireless communication equipment 10-1, 11-1~11-3, 13-5~13-7 Beacon Frame 10-2 Probe request frame 10-3 Probe response frame 10-4, 11-6 Authentication request frame 10-5, 11-7 Authentication response frame 10-6, 11-8 Connection request frame 10-7, 11-9 Connection response frame 11-4 ML probe request frame 11-5 ML Probe Response Frame 11-10 ML Change Request Frame 11-11 ML change response frame 12-1~12-4, 13-1, 13-2 Link 10001-1 Upper layer section 10001a-1 MAC layer section 10002-1 Autonomous distributed control unit 10002a-1 CCA Department 10002b-1 Backoff section 10002c-1 Transmission decision unit 10003-1 Transmitter 10003a-1, 10003c-1 Physical layer frame generator 10003b-1, 10003d-1 Radio transmitter 10004-1 Receiver 10004a-1, 10004c-1 Wireless receiver 10004b-1, 10004d-1 Signal demodulation section 10005-1 Antenna section 40000-3, 40000-7 high frequency band 40000-2, 40000-5 Non-high frequency band 20000-1, 20000-5, 30000-1 MLD wireless communication device 20000-2~20000-4 Sub-access point device 20000-6~20000-8, 30000-2~30000-4 Substation equipment 13-3, 13-4 AP cooperation 13-8 Probe request frame (AP coordination request frame) 13-9 Probe response frame (AP-to-AP coordination response frame) 13-10 Probe request frame (AP-to-AP coordination setting frame) 13-11 Trigger frame (AP-to-AP coordination trigger frame) 13-12, 14-1 Data Frame 14-2 Response Frame

Claims

1. A station device comprising a transmitting unit and a control unit, The transmitting unit transmits a probe request frame, The control unit includes a field in the probe request frame regarding the method of inter-AP communication, The aforementioned field is characterized by indicating the capability of the inter-AP communication method.

2. The station device according to claim 1, characterized in that the transmitting unit transmits the probe request frame by broadcast.

3. An access point device comprising a transmitting unit and a receiving unit, The station device receives a probe request frame containing a field regarding the inter-AP communication method, An access point device characterized by transmitting a probe response frame containing information indicating capability regarding inter-AP communication methods.

4. A wireless communication method, The steps of sending a frame, The steps include broadcasting a probe request frame, The aforementioned probe request frame includes a field regarding the method of inter-AP communication, The aforementioned field is characterized by indicating a capability regarding the method of inter-AP communication.

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