Access point, control method, and program

Abstract

To properly execute settings for a plurality of access points to transmit data to a terminal in parallel.SOLUTION: A communication device for establishing a first basic service set (BSS) determines, based on negotiation with a first other communication device for transmitting wireless frames to a second other communication device in cooperation with the first other communication device, whether a BSS color in the first BSS should be a first BSS color corresponding to the first BSS or a second BSS color corresponding to a second BSS established by the first other communication device, and sets the BSS color in the first BSS based on the determination.SELECTED DRAWING: Figure 7

Description

Technical Field

[0001] The present invention relates to communication control technology in a wireless LAN.

Background Art

[0002] As a communication standard for a wireless LAN (Wireless Local Area Network), the IEEE (Institute of Electrical and Electronics Engineers) 802.11 standard is known. In the IEEE 802.11ax standard, which is the latest standard in the IEEE 802.11 standard series, by using OFDMA (Orthogonal Frequency Division Multiple Access), in addition to high peak throughput, an improvement in communication speed under congested conditions is achieved (see Patent Document 1).

[0003] Currently, in order to further improve throughput, as a successor standard to IEEE 802.11ax, a Study Group called IEEE 802.11EHT (Extremely High Throughput) has been formed. In EHT, in order to achieve throughput improvement, a Multi-AP Coordination configuration in which a plurality of spatially distributed access points (APs) cooperate to transmit data to a single STA (Station) is being considered.

Prior Art Documents

Patent Documents

[0004]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0005] In the IEEE 802.11ax standard, it is stipulated to use identification information called BSS (Basic Service Set) color. When a communication device receives a wireless frame with the same BSS color as the BSS color of the AP to which the device is connected, the communication device treats the wireless frame as an Intra-BSS frame. On the other hand, in IEEE 802.11EHT, although it is being considered to use the Multi-AP Coordination configuration as described above, it is not clear how to set the BSS color in this case.

[0006] The present invention provides a method for appropriately executing settings for a plurality of access points to transmit data to a terminal in parallel.

Means for Solving the Problem

[0007] A communication device according to an aspect of the present invention includes a construction means for constructing a first Basic Service Set (BSS), and based on negotiation with the first other communication device for transmitting a wireless frame to a second other communication device in cooperation with the first other communication device, a determination means for determining whether to set the BSS color in the first BSS to a first BSS color corresponding to the first BSS or a second BSS color corresponding to a second BSS constructed by the first other communication device, and a setting means for setting the BSS color in the first BSS based on the determination by the determination means.

Effect of the Invention

[0008] According to the present invention, it is possible to appropriately execute settings for a plurality of access points to transmit data to a terminal in parallel.

Brief Description of the Drawings

[0009]

Figure 1

Figure 2

Figure 3

Figure 4

Figure 5

Figure 6

Figure 7

Figure 8

Mode for Carrying Out the Invention

[0010] Hereinafter, embodiments will be described in detail with reference to the accompanying drawings. Note that the following embodiments do not limit the invention according to the claims. Although a plurality of features are described in the embodiments, not all of these plurality of features are essential to the invention, and the plurality of features may be arbitrarily combined. Further, in the accompanying drawings, the same or similar configurations are given the same reference numerals, and duplicate descriptions are omitted.

[0011] (Network Configuration) Fig. 1 shows a configuration example of the wireless communication network according to this embodiment. This wireless communication network is configured to include access points (AP102, AP104, AP106) compliant with IEEE802.11EHT (Extremely High Throughput) and terminals (STA103, STA105). Hereinafter, when not referring to a specific device, the access point may be referred to as "AP" and the terminal (station) may be referred to as "STA" without reference numbers. Note that Fig. 1 shows a wireless communication network including three APs and two STAs as an example, but the number of these communication devices may naturally be different from the number shown. Also, EHT may be understood as an abbreviation for Extreme High Throughput.

[0012] In Fig. 1, the communicable range of the network formed by AP102, AP104, and AP106 is indicated by circle 101. Note that this communicable range may cover a wider range or only a narrower range. Also, in Fig. 1, an STA compliant with the IEEE802.11EHT standard is illustrated, but there may be an STA that supports only the previous generation standard (legacy standard) before the IEEE802.11EHT standard.

[0013] In this example, it is assumed that AP102 and AP104, and AP102 and AP106 can receive signals transmitted by the other AP. Note that the connection form is not particularly limited, and AP102 and AP104 may be connected by wire or wirelessly. Also, AP104 and AP106 may or may not be able to communicate with each other. AP102 and AP104 or AP106 support the Multi-AP Coordination configuration of IEEE802.11EHT and are assumed to be able to transmit data to one STA in parallel in cooperation with each other. For example, STA105 can transmit and receive wireless frames in parallel between AP102 and AP104 that operate in cooperation. STA105 can be configured to have, for example, a plurality of wireless LAN control units and be able to transmit and receive wireless frames using different wireless channels between a plurality of APs. Note that STA105 may have a physically single control unit capable of processing a plurality of frames received in parallel via a plurality of wireless channels. That is, STA105 has a configuration that can logically process a plurality of wireless communications in parallel using one or a plurality of physical control devices.

[0014] (Device Configuration) Figure 2 shows the hardware configuration of APs (AP102, AP104, AP106) and STAs (STA103, STA105). As an example of their hardware configuration, these communication devices have a storage unit 201, a control unit 202, a functional unit 203, an input unit 204, an output unit 205, a communication unit 206, and an antenna 207.

[0015] The storage unit 201 is composed of both a ROM and a RAM, or either one of them, and stores programs for performing various operations described later and various information such as communication parameters for wireless communication. Note that as the storage unit 201, in addition to memories such as ROM and RAM, storage media such as flexible disks, hard disks, optical disks, magneto-optical disks, CD-ROMs, CD-Rs, magnetic tapes, non-volatile memory cards, and DVDs may be used.

[0016] The control unit 202 is composed of, for example, a processor such as a CPU or MPU, an ASIC (Application Specific Integrated Circuit), a DSP (Digital Signal Processor), an FPGA (Field Programmable Gate Array), etc. Here, CPU is the acronym for Central Processing Unit, and MPU is the acronym for Micro Processing Unit. The control unit 202 controls the entire device by executing the program stored in the storage unit 201. Note that the control unit 202 may control the entire device in cooperation with the program stored in the storage unit 201 and the OS (Operating System).

[0017] Also, the control unit 202 controls the functional unit 203 to execute predetermined processes such as imaging, printing, and projection. The functional unit 203 is the hardware for the device to execute predetermined processes. For example, when the device is a camera, the functional unit 203 is an imaging unit and performs imaging processing. Also, for example, when the device is a printer, the functional unit 203 is a printing unit and performs printing processing. Also, for example, when the device is a projector, the functional unit 203 is a projection unit and performs projection processing. The data processed by the functional unit 203 may be the data stored in the storage unit 201 or the data communicated with other APs or STAs via the communication unit 206 described later.

[0018] The input unit 204 receives various operations from the user. The output unit 205 performs various outputs to the user. Here, the output by the output unit 205 includes, for example, at least one of display on the screen, audio output by the speaker, vibration output, etc. Note that both the input unit 204 and the output unit 205 may be realized by one module such as a touch panel.

[0019] The communication unit 206 controls wireless communication compliant with the IEEE 802.11 standard series and controls IP communication. In this embodiment, the communication unit 206 can execute at least processes compliant with the IEEE 802.11 EHT standard. Further, the communication unit 206 controls the antenna 207 to transmit and receive wireless signals for wireless communication. The device communicates contents such as image data, document data, and video data with other communication devices via the communication unit 206. The antenna 207 is, for example, an antenna capable of transmitting and receiving at least any one of the sub-GHz band, 2.4 GHz band, 5 GHz band, and 6 GHz band. Note that the frequency bands (and combinations thereof) supported by the antenna 207 are not particularly limited. The antenna 207 may be a single antenna or a set of two or more antennas for performing MIMO (Multi-Input and Multi-Output) transmission and reception. Also, in FIG. 2, a single antenna 207 is shown, but it may include two or more (two sets or more) antennas each capable of corresponding to different frequency bands, for example. The antenna 207 is configured to be capable of corresponding to the communication of Distributed Coordinaiton of the IEEE 802.11 EHT standard. For example, the AP has a configuration such that D-MIMO (Distributed MIMO) transmission for JTX (Joint Transmission) is possible.

[0020] Note that JTX is an element for realizing the Multi-AP Coordination function newly introduced from IEEE802.11EHT, which refers to the situation where multiple APs cooperate to transmit data to one STA in parallel. The Multi-AP Coordination function is a function in which multiple APs cooperate to improve the throughput and signal strength of transmission and reception on the STA side. As the wireless technology at this time, D-MIMO can be used. D-MIMO is a technology in which multiple APs communicate with one STA at the same time and on the same frequency channel (for example, the same RU (Resource Unit) of OFDMA (Orthogonal Frequency Division Multiple Access)). According to D-MIMO, high-speed communication can be realized by improving the spatial utilization efficiency. The minimum configuration of D-MIMO consists of an M-AP (Master AP), an S-AP (Slave AP), and an STA. In this case, under the control of the M-AP, two APs, the M-AP and the S-AP, cooperate to transmit wireless frames to one STA in parallel (simultaneously).

[0021] Fig. 3 shows a functional configuration example of the APs (AP102, AP104, AP106). As an example, the AP has a wireless LAN control unit 301, a frame generation unit 302, a BSS color setting unit 303, a UI control unit 304, a storage unit 305, a role determination unit 306, and an antenna 307.

[0022] The wireless LAN control unit 301 includes a circuit for transmitting and receiving wireless signals to and from other wireless LAN devices (e.g., other APs and STAs) and a program for controlling them. The wireless LAN control unit 301 executes wireless LAN communication control, such as transmitting the frames generated by the frame generation unit 302 and receiving wireless frames from other wireless LAN devices, in accordance with the IEEE802.11 standard series. The frame generation unit 302 generates a wireless frame to be transmitted by the wireless LAN control unit 301 based on, for example, data received from another AP and to be transmitted to the STA. Further, the frame generation unit 302 generates, for example, a wireless frame including data to be transmitted to the STA by another AP or a trigger frame (JTX TF) instructing the timing at which the wireless frame including the data should be transmitted to the STA.

[0023] The BSS color setting unit 303 sets the BSS color of the wireless frame. The BSS color setting unit 303 sets the BSS color to be used in the BSS when the own device (AP102, AP104, or AP106) constructs a BSS (Basic Service Set), for example. Note that the BSS color setting unit 303 can set different BSS colors depending on whether to transmit data to the STA in cooperation with other APs. For example, when not performing cooperative transmission with other APs, the BSS color setting unit 303 uses a BSS color that is default-set in the own device or different from the BSS color set in other surrounding BSSs. In the present embodiment and the appended claims, the BSS color related to the BSS constructed by the AP when the AP does not perform cooperative transmission in this way is called the BSS color corresponding to the BSS. That is, the BSS color set regardless of the relationship with the BSS constructed by other APs in a certain BSS is the BSS color corresponding to the BSS. On the other hand, when performing cooperative transmission with other APs, the BSS color setting unit 303 sets the BSS color according to the determination of the role determination unit 306 described later. That is, when cooperative transmission is performed, the APs performing cooperative transmission should transmit wireless frames with the same BSS color set. Therefore, when cooperative transmission is performed, the BSS color is set in consideration of the relationship with other APs. When the BSS color is set by the BSS color setting unit 303, the frame generation unit 302 generates a wireless frame with the set BSS color. This wireless frame includes, for example, not only frames for data transmission to the STA but also Beacon frames and the like. That is, the AP is in a state of constructing a BSS using the set BSS color. According to this, since the APs transmitting wireless frames by cooperative transmission construct a BSS with a common BSS color, a common BSS color is set in a plurality of wireless frames transmitted in cooperation and received at the STA.Here, since any one of the APs performing coordinated transmission and the STA are in a connected state, the wireless frame received by the STA will have the BSS color of the BSS to which the STA belongs set. Therefore, the STA can handle all of the multiple wireless frames received from multiple APs as Intra-BSS frames.

[0024] On the one hand, when the BSS color setting unit 303 is in a state where it does not perform coordinated transmission with other APs, the BSS color can be set to the default BSS color value. That is, when the BSS color setting unit 303 changes the BSS color of its own device to the BSS color of the BSS constructed by other APs for coordinated transmission, it restores the set value of the BSS color to its original value. Also, when the BSS color setting unit 303 has not changed the BSS color of its own device, it continues to use that BSS color even after the end of coordinated transmission. In this case, other APs may restore the set value of the BSS color. However, when multiple BSSs constructed by multiple APs performing coordinated transmission originally used the same BSS color, the BSS color may not need to be changed even after the end of coordinated transmission. Note that in multiple BSSs having adjacent communicable ranges, using different BSS colors may improve the frequency utilization efficiency in some cases. For example, the STA can execute different controls depending on whether the received wireless frame is an Intra-BSS frame with the BSS color of the BSS to which the own device belongs set or an Inter-BSS frame with a different BSS color set. The STA can transmit a wireless frame when the received power of the wireless frame does not exceed a predetermined value, and the predetermined value for the Inter-BSS frame can be set higher than the predetermined value for the Intra-BSS frame. According to this, even when the wireless frame is received with power exceeding the predetermined value for the Intra-BSS frame, if the wireless frame is an Inter-BSS wireless frame, the STA may be able to obtain a transmission opportunity. Therefore, by having the AP use a different BSS color from other APs, the communication opportunities of the STA can be increased, and the frequency utilization efficiency of the entire system can be improved. Thus, when multiple BSSs constructed by multiple APs performing coordinated transmission originally used the same BSS color, at least one of the multiple APs may change the BSS color.

[0025] The UI control unit 304 is configured to include hardware such as a touch panel or buttons, etc., which are user interfaces (UI) for receiving operations on the AP by a user (not shown in the figure) of the AP, and programs for controlling them. Note that the UI control unit 304 also has functions for presenting information to the user, such as displaying images or outputting sounds, etc. The storage unit 305 is configured to include storage devices such as a ROM (Read Only Memory) and a RAM (Random Access Memory) for storing programs and various data executed by the AP.

[0026] When the role determination unit 306 transmits a wireless frame to a common STA in cooperation with other APs, it executes negotiation with the other APs. Then, based on this negotiation, the role determination unit 306 determines whether to operate as an M-AP, which is a role for controlling cooperative transmission, or as an S-AP controlled by the M-AP. Note that the above-mentioned BSS color setting unit 303 does not change the BSS color (for example, uses the default value) when the own device operates as an M-AP. In this case, the BSS color of the BSS constructed by other APs operating as S-APs is set for the BSS color of the own device. On the other hand, when the own device operates as an S-AP, the BSS color setting unit 303 sets the BSS color of the BSS constructed by the own device to match the BSS color of the BSS constructed by the M-AP.

[0027] Note that the STA has functions as a general STA. However, the STA may have a function of receiving wireless frames transmitted in a Multi-AP Coordination configuration.

[0028] (Frame Structure) Using FIGS. 4 to 6, an example of the structure of a PPDU (Physical layer (PHY) Protocol Data Unit) compliant with the IEEE 802.11 EHT standard will be described. FIG. 4 shows an example of an EHT SU (Single User) PPDU, which is a PPDU for single-user communication, FIG. 5 shows an example of an EHT MU (Multi User) PPDU for multi-user communication, and FIG. 6 shows an example of an EHT ER (Extended Range) PPDU for long-distance transmission. The EHT ER PPDU is used when the communication range needs to be extended in the communication between an AP and a single STA. Note that each field of the PPDU does not necessarily have to be arranged in the order shown in FIGS. 4 to 6, and may include new fields not shown in FIGS. 4 to 6.

[0029] The PPDU includes fields such as STF (Short Training Field), LTF (Long Training Field), and SIG (Signal Field). As shown in Figure 4, at the head of the PPDU, there are L (Legacy)-STF401, L-LTF402, and L-SIG403 for ensuring backward compatibility with the IEEE802.11a / b / g / n / ax standards. In the frame formats of Figures 5 and 6 as well, L-STF (L-STF501 and L-STF601), L-LTF (L-LTF502 and L-LTF602), and L-SIG (L-SIG503 and L-SIG603) are included. Note that L-LTF is arranged immediately after L-STF, and L-SIG is arranged immediately after L-LTF. In the configurations of Figures 4 to 6, further, RL-SIG (Repeated L-SIG, RL-SIG404, RL-SIG504, RL-SIG604) arranged immediately after L-SIG is included. In the RL-SIG field, the content of L-SIG is repeatedly transmitted. RL-SIG enables the receiver to recognize that the PPDU complies with standards after the IEEE802.11ax standard, and in some cases, it may be omitted in IEEE802.11EHT. Also, instead of RL-SIG, a field for enabling the receiver to recognize that the PPDU is an IEEE802.11EHT PPDU may be provided.

[0030] L-STF401 is used for detecting physical layer (PHY) frame signals, automatic gain control (AGC), and timing detection, etc. L-LTF402 is used for high-precision synchronization of frequency and time, obtaining propagation channel information (CSI: Channel State Information), etc. L-SIG403 is used for transmitting control information including data transmission rate and PHY frame length information. Legacy devices compliant with the IEEE802.11a / b / g / n / ax standards can decode the above various legacy fields.

[0031] Each PPDU further includes an EHT-SIG (EHT-SIG-A405, EHT-SIG-A505, EHT-SIG-B506, EHT-SIG-A605) for transmitting control information for EHT, which is arranged immediately after the RL-SIG. Also, each PPDU has an EHT-STF (EHT-STF406, 507, 606) and an EHT-LTF (EHT-LTF407, 508, 607) for EHT. Each PPDU has data fields 408, 509, 608 and Packet extention fields 409, 710, 609 after these control fields. The fields from the L-STF to the EHT-LTF of each PPDU are called the PHY preamble.

[0032] Note that FIGS. 4 to 6 show, as an example, PPDUs that can ensure backward compatibility. However, when backward compatibility does not need to be ensured, for example, legacy fields may be omitted. In this case, for example, for establishing synchronization, instead of the L-STF and L-LTF, the EHT-STF or EHT-LTF may be used. And in this case, one of the EHT-STF or a plurality of EHT-LTFs after the EHT-SIG field may be omitted.

[0033] The EHT-SIG-A405 and 605 included in the EHT SU PPDU and the EHT ER PPDU include the EHT-SIG-A1 and EHT-SIG-A2 necessary for receiving the PPDU, as shown in Tables 1 and 2 below. The EHT-SIG-A1 includes a 6-bit "BSS color" subfield. Also, the EHT-SIG-A505 of the EHT MU PPDU in FIG. 5 also includes the EHT-SIG-A1 and EHT-SIG-A2 necessary for receiving the PPDU, as shown in Tables 3 and 4 below. And in this PPDU as well, the EHT-SIG-A1 includes a 6-bit "BSS color" subfield. Note that the configurations of Tables 1 to 4 are only examples, and information other than the information shown in these tables may be included in the EHT-SIG field, or some of the information shown in these tables may be excluded from the EHT-SIG field.

[0034]

Table 1

[0035]

Table 2

[0036]

Table 3

[0037]

Table 4

[0038] (Process flow) Subsequently, an example of the process flow executed by the AP as described above and the process flow executed in the wireless communication network will be described with reference to FIGS. 7 and 8. FIG. 7 shows an example of the process flow in the wireless communication network, and FIG. 8 shows an example of the process flow executed by each AP. In this example, it is assumed that AP102 constructs the first BSS (BSS1) (F701), and AP104 constructs the second BSS (BSS2) (F702). Here, in the present embodiment, it is assumed that in BSS1, a setting using BSS color1 is performed, and in BSS2, a setting using BSS color2 different from BSS color1 is performed. Each AP notifies the IEEE802.11 Beacon at a fixed period and accepts a connection request from the STA, thereby mediating communication between the STA and another STA or between the STA and the DS (Distribution System).

[0039] Thereafter, it is assumed that AP102 and AP104 have decided to cooperate to perform data transmission to a common STA in parallel. For example, when AP104 detects that there is a large amount of data to be transmitted to STA105, it may decide to cooperate with AP102, which is another AP existing in the vicinity, and transmit data to STA105 in parallel. Also, even if there is no plan for large-capacity data communication to a specific STA, for example, AP102 or AP104 may decide to make preparations for cooperative transmission with other APs in case large-capacity data communication occurs in the future. When it is decided that cooperative transmission by a plurality of APs will be performed or preparations therefor will be made, AP102 and AP104 perform negotiation for JTX (Joint Transmission) (F703, S801). Note that hereinafter, the negotiation for JTX may be simply referred to as "negotiation". In the negotiation, the AP that executes the negotiation can determine whether it will operate in either the role of M-AP or S-AP. Here, it is assumed that it is decided that AP102 will operate as M-AP (YES in F704, S802), and it is decided that AP104 will operate as S-AP (NO in F705, S802). Also, in this negotiation, it may be decided which AP will associate with the STA that is the target of JTX.

[0040] In response to the roles of each AP being determined through negotiation, the BSS color is set. That is, the S-AP sets the BSS color of the BSS configured by itself to the same value as the BSS color of the M-AP. In this example, AP104 changes the BSS color of BSS2 configured by itself from BSS color2 to BSS color1 (F706, S811). Note that the S-AP can obtain the information of the BSS color of the M-AP during negotiation. However, it is not limited to this. For example, the S-AP can operate as a STA to receive a wireless frame from the M-AP and analyze the PHY preamble (or MAC (Media Access Control) header) of the wireless frame to obtain the information of the BSS color. The wireless frame here can be, for example, a Beacon or a Probe response frame. For example, AP104 transmits a Probe request frame, and AP102 can transmit a Probe response including an operation information element containing the BSS color in response to this. This operation information element can be, for example, an EHT Operation element and can be configured with content compatible with the HE Operation element of IEEE802.11ax. Also, after the negotiation ends, the S-AP may obtain the information of the BSS color to be set by the M-AP transmitting a wireless frame notifying the BSS color to the S-AP. Also, the S-AP may obtain the information of the BSS color of the BSS constructed by the M-AP by other methods than these. Here, if there is a STA (not shown) belonging to BSS2 constructed by AP104, AP104 notifies the STA that the BSS color has been changed. Note that since AP102 operates as an M-AP, it maintains the BSS color1 corresponding to BSS1 without change. Note that in this example, the case where negotiation is performed with AP104 having constructed BSS2 using BSS color2 has been described. However, it is not limited to this. For example, negotiation may be started with AP104 not having constructed BSS2.In this case, the AP determined to operate in S-AP through negotiation sets the BSS color used in the BSS constructed by the M-AP as the BSS color to be used in the newly constructed BSS. As a result, the BSS colors used in the BSSs constructed in the M-AP and the S-AP respectively are made common.

[0041] Thereafter, it is assumed that the AP 104 executes a connection procedure with the STA 105 and transitions to a connected state (F707). In this connection procedure, similar to the case of IEEE802.11ax, operation state information is notified from the AP to the STA. This operation state information includes the value of the BSS color. As described above, the BSS color is 6-bit information for identifying the BSS included in the preamble of the physical layer (PHY). Based on the value of the BSS color, the STA can determine whether the received wireless frame is a frame of the BSS (intra-BSS) to which it belongs or a frame of a BSS (inter-BSS) to which it does not belong.

[0042] In response to establishing a connection with the STA 105, the AP 104 notifies the information of the STA 105 to the AP 102 (F708, S803, S812). Here, the STA information may include information such as the MAC address information of the STA. Note that the S-AP may notify the information of the STA connected at the time of negotiation to the M-AP at the time of negotiation. Also, at other timings, the information of the STA connected to the S-AP may be notified from the S-AP to the M-AP. Also, the AP 102 may notify the information of the STA connected to its own device to the AP 104. Furthermore, when the AP 102 and the AP 104 perform JTX to transmit data to a specific STA, the information of the STA may be notified from the AP connected to the STA to the other AP. However, since the M-AP can specify the STA for which data is to be transmitted in the transmission of the data to be transmitted and the JTX trigger frame etc. described later, it may not be necessary to provide information from the M-AP to the S-AP at this point.

[0043] Thereafter, AP102 notifies the start of the JTX mode to AP104 operating as an S-AP (F709, S804, S813). In the above description, AP104 changes the BSS color after the negotiation and before the start notification of this JTX mode. However, for example, the BSS color may be changed in response to receiving the start notification of the JTX mode. According to this, when the time from after the negotiation until the operation in the JTX mode starts is long, it is possible to prevent the BSS color from being unnecessarily unified between APs, and improve the frequency utilization efficiency of the entire system. On the other hand, by sharing the BSS color immediately after the negotiation, since there is no need to perform the process of changing the BSS color after the start of the JTX mode, as soon as data is generated for the STA, the data can be immediately transmitted to the STA in JTX.

[0044] After AP102 and AP104 start operating in the JTX mode, when data to be transmitted to STA105 is generated (YES in S805), the data to be transmitted is sent from AP102 to AP104 (F710, S806, S814). Since AP104 is operating in the JTX mode, instead of immediately transmitting the received data to STA105, the received data is temporarily held.

[0045] After the transmission and reception of the data to be transmitted, in order to transmit a wireless frame including this data to be transmitted, AP102 transmits a JTX trigger frame (TF) to AP104 (F711, S807, S815). AP102 can instruct AP104 to transmit a wireless frame to STA105 by the JTX TF and specify the timing of the transmission. Then, AP102 and AP104 transmit data to STA105 in parallel at the timing specified by, for example, the JTX TF (YES in S808, YES in S816) (F712, F713, S809, S817). Note that the transmission timing can be after a predetermined time (SIFS, Short Inter Frame Space) has elapsed since the transmission and reception of the JTX TF. In this case, the transmission timing is indicated by the transmission and reception of the JTX TF itself. In this case, the JTX TF can be transmitted at a timing corresponding to the timing at which AP102 and AP104 should transmit a wireless frame to STA105. Also, information specifying the transmission timing may be included in the frame of the JTX TF. In this case, AP102 and AP104 can determine when to transmit a wireless frame using the specified transmission timing and a timer or clock in their own devices. In this way, AP102 and AP104 can transmit wireless frames synchronously using the JTX TF. Note that this wireless frame is a PPDU shown in any of FIGS. 4 to 6, and a value indicating BSS color1 set in each BSS as described above is stored in the BSS color subfield. As shown in the table above, the BSS color subfield is bits 9 to 14 (B8 to B13) of EHT-SIG-A1 in the case of an EHT SU PPDU or an EHT ER PPDU. Also, the BSS color subfield is bits 6 to 11 (B5 to B10) of EHT-SIG-A1 in the case of an EHT MU PPDU.

[0046] After that, for example, based on the fact that there is no data to be transmitted to STA105, when AP102 decides to end the JTX mode, it sends a notification of the end of the JTX mode to AP104 (F714, S810, S818). Note that AP102 and AP104 can decide to end the JTX mode in various cases, such as when there is no STA to which a large amount of data is to be transmitted, or when the number of connected STAs exceeds a predetermined number and there is a shortage of radio resources for JTX.

[0047] When AP104 receives this notification of the end of the JTX mode, it returns the BSS color to the value of the BSS color before the change (BSS color2) (F715, S819). At this time, since AP104 has changed the setting of the BSS color, it notifies STA105, which is currently connected, that the BSS color has been changed (F716). As a result, STA105 will handle the wireless frame of BSS color2 as an Intra-BSS frame. After that, when AP104 sends data to STA105, a wireless frame with BSS color2 set is transmitted (F717).

[0048] After that, for example, assume that AP102 and AP106 have determined to perform JTX. In this case, these APs execute JTX negotiation in the same manner as in the above case, and the AP that has been determined to operate as an S-AP makes the BSS color of its own device match the BSS color of the M-AP (F718~F722). Then, for example, assume that STA103 executes a connection process with AP106 and transitions to a connected state (F723). In response, by executing the processes of F708~F713 between AP102 and AP106, a wireless frame with the BSS color set to BSS color1 is transmitted from AP102 and AP106 to STA103 by JTX. Note that, as described above, a BSS color2 different from BSS color1 transmitted from AP102 and AP106 is set in the wireless frame transmitted and received between AP104 and STA105. Therefore, compared with the case where these BSS colors are common, for example, the transmission opportunity of the wireless frame to STA105 can be increased.

[0049] As described above, when multiple APs cooperate to transmit wireless frames to a common STA, by making the BSS colors common, the STA can handle the received wireless frames as Intra-BSS frames. Also, based on the termination of the cooperative transmission, when the BSS color of the S-AP (and in some cases, the M-AP) is changed, in the case where the cooperative transmission is not performed, the wireless frames in the adjacent BSS are handled as Inter-BSS frames. As a result, since the probability that the STA can obtain a transmission opportunity increases, it becomes possible to improve the frequency utilization efficiency of the entire system.

[0050] The present invention can also be realized by supplying a program that realizes one or more functions of the above-described embodiment to a system or device via a network or a storage medium, and having one or more processors in the computer of the system or device read and execute the program. It can also be realized by a circuit (for example, ASIC) that realizes one or more functions.

[0051] The invention is not limited to the above embodiments, and various changes and modifications can be made without departing from the spirit and scope of the invention. Therefore, the claims are appended to disclose the scope of the invention.

Description of Reference Numerals

[0052] 102, 104, 106: AP, 103, 105: STA, 301: Wireless LAN control unit, 302: Frame generation unit, 303: BSS color setting unit, 304: UI control unit, 305: Storage unit, 306: Role determination unit

Claims

1. Construction means for constructing a first Basic Service Set (BSS); Based on negotiation with the first other communication device for transmitting a wireless frame to a second other communication device in cooperation with the first other communication device, determining whether to set the BSS color in the first BSS to the first BSS color corresponding to the first BSS or the second BSS color corresponding to a second BSS constructed by the first other communication device; Setting means for setting the BSS color in the first BSS based on the determination by the determining means; A communication device, characterized by comprising the above.

2. In the negotiation, it is determined which of the communication device and the first other communication device operates in a role of controlling another device to cooperatively transmit a wireless frame to the second other communication device; The communication device according to claim 1, wherein when it is determined by the negotiation that the first other communication device operates in the role, the determining means determines to set the BSS color in the first BSS to the second BSS color.

3. When it is determined by the negotiation that the communication device operates in the role; The determining means determines to set the BSS color in the first BSS to the first BSS color; The first other communication device sets the BSS color in the second BSS to the first BSS color. The communication device according to claim 2, characterized by the above.

4. The communication device according to any one of claims 1 to 3, wherein after the setting means sets the BSS color of the first BSS to the second BSS color, in response to the termination of the operation in a mode of cooperatively transmitting a wireless frame to the second other communication device, the setting means performs a setting to change the BSS color of the first BSS to the first BSS color.

5. When the setting means determines that the BSS color of the first BSS is to be the second BSS color while the first BSS color is being used in the first BSS, before starting the operation in the mode, the setting means performs a setting to change the BSS color in the first BSS to the second BSS color. The communication device according to claim 4, wherein:

6. When the setting means determines that the BSS color of the first BSS is to be the second BSS color while the first BSS color is being used in the first BSS, based on starting the operation in the mode, the setting means performs a setting to change the BSS color in the first BSS to the second BSS color. The communication device according to claim 4, wherein:

7. The determining means makes the determination before the constructing means constructs the first BSS. The constructing means constructs the first BSS set to use the BSS color based on the determination by the determining means. The communication device according to any one of claims 1 to 6, wherein:

8. When the BSS color of the first BSS is changed, the communication device further includes a notifying means for notifying other communication devices belonging to the first BSS that the BSS color has been changed. The communication device according to any one of claims 1 to 7, wherein:

9. The communication device obtains information on the second BSS color by the negotiation. The communication device according to any one of claims 1 to 8, wherein:

10. The communication device operates as a terminal capable of communicating with the first other communication device, and obtains information on the second BSS color by receiving a wireless frame from the first other communication device. The communication device according to any one of claims 1 to 8, wherein:

11. The wireless frame is a wireless frame having a preamble and a data field in a physical layer (PHY). The preamble is a Legacy Short Training Field (L-STF), and a Legacy Long Training Field (L-LTF) arranged immediately after the L-STF in the wireless frame. A Legacy Signal Field (L-SIG) arranged immediately after the L-LTF in the wireless frame, An Extremely High Throughput (EHT) Signal Field (EHT-SIG-A) arranged after the L-SIG in the wireless frame, An EHT Short Training Field (EHT-STF) arranged after the EHT-SIG-A in the wireless frame, An EHT Long Training Field (EHT-LTF) arranged immediately after the EHT-STF in the wireless frame, comprising, the EHT-SIG-A includes a subfield for setting a BSS color, the communication device transmits the wireless frame including a value specifying the BSS color set by the setting means in the subfield, The communication device according to any one of claims 1 to 10, characterized in that.

12. The communication device and the first other communication device are access points compliant with IEEE802.11EHT, and the second other communication device is a station compliant with IEEE802.11EHT. The communication device according to any one of claims 1 to 11, characterized in that.

13. A control method executed by a communication device that constructs a first Basic Service Set (BSS), Based on the negotiation with the first other communication device for transmitting a wireless frame to the second other communication device in cooperation with the first other communication device, the BSS color in the first BSS is determined as the first BSS color corresponding to the first BSS or the second BSS color corresponding to the second BSS constructed by the first other communication device. Deciding whether to do so, Setting the BSS color in the first BSS based on the determination, A control method characterized by including.

14. A program for causing a computer to function as each means of the communication device according to any one of claims 1 to 12.

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