Station device, communication method, and program

Abstract

To appropriately execute settings for a plurality of access points to transmit data in parallel to a terminal.SOLUTION: A station device receives a radio frame from a first access point device building a first Basic Service Set (BSS), and receives a radio frame from a second access point device building a second BSS. When the station device receives a radio frame transmitted in cooperation by the first access point device and the second access point device, the value of a BSS color in the first BSS and the value of a BSS color in the second BSS are set to the same value.SELECTED DRAWING: Figure 7

Description

[Technical field]

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

[0002] The Institute of Electrical and Electronics Engineers (IEEE) 802.11 standard is known as a communication standard for wireless local area networks (wireless LANs). The IEEE 802.11ax standard, which is the latest standard in the IEEE 802.11 series, uses orthogonal frequency division multiple access (OFDMA) to achieve high peak throughput as well as improved communication speeds under congested conditions (see Patent Document 1).

[0003] Currently, in order to further improve throughput, a study group called IEEE802.11EHT (Extremely High Throughput) has been formed as a successor standard to IEEE802.11ax. In EHT, a Multi-AP Coordination configuration is being considered in order to achieve improved throughput, in which multiple spatially distributed access points (APs) cooperate to transmit data to a single STA (Station). [Prior art documents] [Patent documents]

[0004] [Patent Document 1] JP 2018-050133 A Summary of the Invention [Problem to be solved by the invention]

[0005] The IEEE802.11ax standard specifies the use of 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 the IEEE802.11EHT, the use of a Multi-AP Coordination configuration as described above is being considered, but it is not clear how the BSS color should be set in this case.

[0006] The present invention provides a method for appropriately executing settings for multiple access points to transmit data in parallel to a terminal. [Means for solving the problem]

[0007] A station device according to one embodiment of the present invention has a first receiving means for receiving wireless frames from a first access point device that establishes a first Basic Service Set (BSS) and a second receiving means for receiving wireless frames from a second access point device that establishes a second BSS, and when receiving a wireless frame transmitted in cooperation between the first access point device and the second access point device, the value of the BSS color in the first BSS and the value of the BSS color in the second BSS are set to the same value. 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] FIG. 1 illustrates an example of a network configuration. [Diagram 2] FIG. 2 is a diagram illustrating an example of the hardware configuration of an AP and a STA. [Diagram 3]FIG. 2 is a diagram illustrating an example of the functional configuration of an AP and a STA. [Figure 4] A figure showing an example of a PHY frame structure of an EHT SU PPDU. [Diagram 5] A diagram showing an example of a PHY frame structure of an EHT ER PPDU. [Figure 6] FIG. 2 is a diagram illustrating an example of a PHY frame structure of an EHT MU PPDU. [Figure 7] FIG. 1 is a diagram illustrating an example of a flow of processing executed in a network. [Figure 8] FIG. 11 is a diagram illustrating an example of a flow of processing executed in an AP. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0010] Hereinafter, the embodiments will be described in detail with reference to the attached drawings. Note that the following embodiments do not limit the invention according to the claims. Although the embodiments describe a number of features, not all of these features are essential to the invention, and the features may be combined in any manner. Furthermore, in the attached drawings, the same reference numbers are used for the same or similar configurations, and duplicated descriptions are omitted.

[0011] (Network Configuration) FIG. 1 shows an example of the configuration of a wireless communication network according to the present embodiment. This wireless communication network includes access points (AP102, AP104, AP106) and terminals (STA103, STA105) that comply with IEEE802.11 EHT (Extremely High Throughput). In the following, when a specific device is not being referred to, the access point may be called an "AP" and the terminal (station) may be called an "STA" without a reference number. 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 interpreted as an abbreviation for Extreme High Throughput.

[0012] 1, the communication range of the network formed by AP 102, AP 104, and AP 106 is indicated by a circle 101. This communication range may cover a wider range or may cover only a narrower range. Also, in FIG. 1, STAs conforming to the IEEE802.11EHT standard are illustrated, but there may be STAs that support only a standard of a generation earlier than the IEEE802.11EHT standard (legacy standard).

[0013] In this example, the AP102 and the AP104, and the AP102 and the AP106 are assumed to be capable of receiving signals transmitted from each other AP. The connection form is not particularly limited, and the AP102 and the AP104 may be connected by wire or wirelessly. The AP104 and the AP106 may or may not be capable of communicating with each other. The AP102 and the AP104 or the AP106 are assumed to support the Multi-AP Coordination configuration of IEEE802.11EHT and to be capable of transmitting data to one STA in parallel in cooperation with each other. For example, the STA105 can transmit and receive wireless frames in parallel with the AP102 and the AP104 which operate in cooperation with each other. The STA105 may be configured to have, for example, multiple wireless LAN control units and to transmit and receive wireless frames with multiple APs using different wireless channels. The STA105 may have one physical control unit capable of processing multiple frames received in parallel via multiple wireless channels. That is, the STA 105 has a configuration that physically uses one or more control devices and logically processes multiple wireless communications in parallel.

[0014] (Device configuration) 2 shows the hardware configuration of an AP (AP102, AP104, AP106) and a STA (STA103, STA105). These communication devices include a storage unit 201, a control unit 202, a function unit 203, an input unit 204, an output unit 205, a communication unit 206, and an antenna 207 as an example of the hardware configuration.

[0015] The storage unit 201 is configured with a ROM and / or a RAM, and stores various information such as programs for performing various operations described below and communication parameters for wireless communication. Note that, in addition to memories such as ROM and RAM, the storage unit 201 may be a storage medium such as a flexible disk, a hard disk, an optical disk, a magneto-optical disk, a CD-ROM, a CD-R, a magnetic tape, a non-volatile memory card, or a DVD.

[0016] The control unit 202 is configured with, 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 an acronym for Central Processing Unit, and MPU is an acronym for Micro Processing Unit. The control unit 202 controls the entire device by executing a 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 an OS (Operating System).

[0017] Furthermore, the control unit 202 controls the functional unit 203 to execute predetermined processes such as imaging, printing, and projection. The functional unit 203 is hardware for the device to execute predetermined processes. For example, if the device is a camera, the functional unit 203 is an imaging unit and executes imaging processing. For example, if the device is a printer, the functional unit 203 is a printing unit and executes printing processing. For example, if the device is a projector, the functional unit 203 is a projection unit and executes projection processing. Data processed by the functional unit 203 may be data stored in the storage unit 201, or may be 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 outputs various types of information to the user. Here, the output by the output unit 205 includes at least one of, for example, display on a screen, audio output by a speaker, vibration output, and the like. 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 conforming to the IEEE802.11 standard series and IP communication. In this embodiment, the communication unit 206 can execute processing conforming to at least the IEEE802.11EHT standard. The communication unit 206 also controls the antenna 207 to transmit and receive wireless signals for wireless communication. The device communicates content such as image data, document data, and video data with other communication devices via the communication unit 206. The antenna 207 is an antenna capable of transmitting and receiving at least one of the sub-GHz band, the 2.4 GHz band, the 5 GHz band, and the 6 GHz band. Note that there is no particular limitation on the frequency bands (and their combinations) that can be supported by the antenna 207. The antenna 207 may be a single antenna, or may be a set of two or more antennas for performing MIMO (Multi-Input and Multi-Output) transmission and reception. Also, although one antenna 207 is shown in FIG. 2, the device may include, for example, two or more antennas (two or more sets) that can support different frequency bands. The antenna 207 is configured to be compatible with communication of Distributed Coordination of the IEEE 802.11 EHT standard. For example, the AP has a configuration that enables transmission of Distributed MIMO (D-MIMO) for Joint Transmission (JTX).

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

[0021] 3 shows an example of the functional configuration of an AP (AP 102, AP 104, AP 106). The AP includes, as an example, 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 is configured to include circuits for transmitting and receiving wireless signals to and from other wireless LAN devices (e.g., other APs and STAs) and programs for controlling them. The wireless LAN control unit 301 executes wireless LAN communication control, such as transmitting 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 wireless frames to be transmitted by the wireless LAN control unit 301 based on data to be transmitted to the STA, for example, received from another AP. The frame generation unit 302 also generates, for example, wireless frames including data to be transmitted to the STA by the other AP, and trigger frames (JTX TF) that instruct the timing at which the wireless frames including the data should be transmitted to the STA.

[0023] The BSS color setting unit 303 sets the BSS color of the wireless frame. For example, when the local device (AP 102, AP 104, or AP 106) establishes a BSS (Basic Service Set), the BSS color setting unit 303 sets the BSS color to be used in the BSS. The BSS color setting unit 303 may set a different BSS color depending on whether or not data is transmitted to a STA in cooperation with other APs. For example, when cooperative transmission with other APs is not performed, the BSS color setting unit 303 uses a BSS color that is different from the default BSS color set in the local device and the BSS color set in other surrounding BSSs. In this embodiment and the appended claims, the BSS color related to the BSS established by the AP when the AP does not perform cooperative transmission is called the BSS color corresponding to the BSS. In other words, the BSS color set in a certain BSS regardless of the relationship with the BSS established by the other AP is the BSS color corresponding to the BSS. On the other hand, when cooperative transmission with other APs is performed, the BSS color setting unit 303 sets the BSS color according to the decision of the role determination unit 306 described later. That is, when cooperative transmission is performed, the AP 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 setting unit 303 sets the BSS color, the frame generation unit 302 generates wireless frames with the BSS color set. These wireless frames include, for example, not only frames for data transmission to STAs, but also beacon frames and the like. That is, the AP is in a state of establishing a BSS using the set BSS color. According to this, the APs transmitting wireless frames by cooperative transmission establish a BSS with a common BSS color, so that a common BSS color is set for multiple cooperatively transmitted wireless frames received by the STA.In this case, since the STA is connected to one of the APs performing coordinated transmission, the wireless frame received by the STA is set to the BSS color of the BSS to which the STA belongs. Therefore, the STA can treat all wireless frames received from multiple APs as Intra-BSS frames.

[0024] On the other hand, when the BSS color setting unit 303 is in a state where cooperative transmission with other APs is not performed, the BSS color setting unit 303 may set the BSS color to the default BSS color value. That is, when the BSS color setting unit 303 has changed the BSS color of the own device to the BSS color of the BSS established by another AP for cooperative transmission, the BSS color setting unit 303 returns the set value of the BSS color to the original value. Also, when the BSS color of the own device has not been changed, the BSS color setting unit 303 continues to use the BSS color even after the cooperative transmission ends. In this case, the other AP may return the set value of the BSS color to the original value. However, when multiple BSSs established by multiple APs performing cooperative transmission originally used the same BSS color, the BSS color may not be changed even after the cooperative transmission ends. In some cases, it is possible to improve frequency utilization efficiency by using different BSS colors in multiple BSSs having adjacent communication ranges. For example, the STA may execute different control depending on whether the received wireless frame is an Intra-BSS frame in which the BSS color of the BSS to which the own device belongs is set, or an Inter-BSS frame in which a different BSS color is set. A STA may transmit a wireless frame when the received power of the wireless frame does not exceed a predetermined value, but the predetermined value for the Inter-BSS frame may be set to a value higher than the predetermined value for the Intra-BSS frame. In this way, even if a 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. For this reason, by making an AP use a BSS color different from other APs, communication opportunities for the STA can be increased, and frequency utilization efficiency of the entire system can be improved. Therefore, 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 includes hardware related to a user interface (UI) such as a touch panel or buttons for accepting operations on the AP by a user (not shown) of the AP, and a program for controlling them. The UI control unit 304 also has a function for presenting information to the user, such as displaying images or outputting audio. The storage unit 305 includes a storage device such as a ROM (Read Only Memory) or a RAM (Random Access Memory) for storing programs executed by the AP and various data.

[0026] When transmitting a wireless frame to a common STA in cooperation with another AP, the role determination unit 306 executes negotiation with the other AP. Then, the role determination unit 306 determines through this negotiation whether to operate as an M-AP, which is a role that controls 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 when the own device operates as an M-AP (for example, uses a default value). In this case, the BSS color of the BSS established by the other AP operating as an S-AP is set as 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 established by the own device so that it matches the BSS color of the BSS established by the M-AP.

[0027] The STA has the functions of a general STA, but may also have the function of receiving wireless frames transmitted in a Multi-AP Coordination configuration.

[0028] (Frame structure) An example of the structure of a PPDU (Physical layer (PHY) Protocol Data Unit) conforming to the IEEE802.11 EHT standard will be described with reference to Figs. 4 to 6. Fig. 4 shows an example of an EHT SU (Single User) PPDU, which is a PPDU for single user communication, and Fig. 5 shows an example of an EHT MU (Multi User) PPDU for multi-user communication. 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 communication between an AP and a single STA. Note that the fields of the PPDU do not necessarily need 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 the fields of a Short Training Field (STF), a Long Training Field (LTF), and a Signal Field (SIG). As shown in Fig. 4, the head of the PPDU includes an L (Legacy)-STF 401, an L-LTF 402, and an L-SIG 403 for ensuring backward compatibility with the IEEE802.11a / b / g / n / ax standard. The frame formats in Figs. 5 and 6 also include an L-STF (L-STF 501 and L-STF 601), an L-LTF (L-LTF 502 and L-LTF 602), and an L-SIG (L-SIG 503 and L-SIG 603). The L-LTF is placed immediately after the L-STF, and the L-SIG is placed immediately after the L-LTF. In addition, the configurations of Figs. 4 to 6 further include an RL-SIG (Repeated L-SIG, RL-SIG404, RL-SIG504, RL-SIG604) arranged immediately after the L-SIG. In the RL-SIG field, the contents of the L-SIG are repeatedly transmitted. The RL-SIG enables the receiver to recognize that the PPDU is compliant with the IEEE802.11ax standard or later, and may be omitted in the IEEE802.11EHT in some cases. Also, instead of the RL-SIG, a field may be provided to enable the receiver to recognize that the PPDU is an IEEE802.11EHT PPDU.

[0030] L-STF401 is used for detecting physical layer (PHY) frame signals, automatic gain control (AGC) and timing detection. L-LTF402 is used for highly accurate frequency and time synchronization and for acquiring propagation channel information (CSI). L-SIG403 is used to transmit control information including data transmission rate and PHY frame length information. Legacy devices that comply with the IEEE802.11a / b / g / n / ax standards can decode the various legacy fields listed above.

[0031] Each PPDU further includes an EHT-SIG (EHT-SIG-A 405, EHT-SIG-A 505, EHT-SIG-B 506, EHT-SIG-A 605) for transmitting control information for EHT, which is placed immediately after the RL-SIG. Each PPDU also has an STF for EHT (EHT-STF 406, 507, 606) and an LTF for EHT (EHT-LTF 407, 508, 607). Each PPDU has a data field 408, 509, 608 and a packet extension field 409, 710, 609 after these control fields. The fields from the L-STF to the EHT-LTF of each PPDU are called a PHY preamble.

[0032] 4 to 6 show, as an example, a PPDU that can ensure backward compatibility, but when it is not necessary to ensure backward compatibility, for example, the legacy field may be omitted. In this case, for example, EHT-STF and EHT-LTF are used instead of L-STF and L-LTF to establish synchronization. In this case, the EHT-STF after the EHT-SIG field or one of the multiple EHT-LTFs may be omitted.

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

[0034] [Table 1]

[0035] [Table 2]

[0036] [Table 3]

[0037] [Table 4]

[0038] (Processing flow) Next, an example of the flow of the process executed by the AP and the flow of the process executed in the wireless communication network will be described with reference to Figs. 7 and 8. Fig. 7 shows an example of the flow of the process in the wireless communication network, and Fig. 8 shows an example of the flow of the process executed by each AP. In this example, it is assumed that the AP 102 establishes a first BSS (BSS1) (F701), and the AP 104 establishes a second BSS (BSS2) (F702). Here, in this embodiment, it is assumed that the BSS1 is set to use the BSS color1, and the BSS2 is set to use the BSS color2 different from the BSS color1. Each AP broadcasts the IEEE802.11 Beacon at a constant period and accepts a connection request from the STA, thereby mediating communication between the STA and another STA, or between the STA and a Distribution System (DS).

[0039] After that, it is assumed that AP102 and AP104 decide to cooperate and transmit data to a common STA in parallel. For example, when AP104 detects that there is a large amount of data to be transmitted to STA105, AP104 may decide to cooperate with AP102, which is another AP present in the vicinity, and transmit data to STA105 in parallel. In addition, even if AP102 or AP104 does not have a plan for large-volume data communication to a specific STA, AP102 or AP104 may decide to prepare for cooperative transmission with other APs in preparation for the occurrence of large-volume data communication in the future. When it is decided that cooperative transmission by multiple APs will be performed or that preparations will be made, AP102 and AP104 negotiate for JTX (Joint Transmission) (F703, S801). In the following, negotiation for JTX may be simply referred to as "negotiation". In the negotiation, APs performing the negotiation may determine whether they will operate as M-AP or S-AP. Here, it is assumed that AP 102 has decided to operate as M-AP (YES in F704 and S802), and AP 104 has decided to operate as S-AP (NO in F705 and S802). In addition, in this negotiation, it may be determined which AP will associate with the STA that is the target of JTX.

[0040] The BSS color is set according to the role of each AP determined by the negotiation. That is, the S-AP sets the BSS color of the BSS configured by the own device to the same value as the BSS color of the M-AP. In this example, the AP 104 changes the BSS color of the BSS2 configured by the own device from BSS color 2 to BSS color 1 (F706, S811). The S-AP may obtain the BSS color information of the M-AP during the negotiation. However, this is not limited to this, and for example, the S-AP may operate as a STA to receive a wireless frame from the M-AP and obtain the BSS color information by analyzing the PHY preamble (or MAC (Medium Access Control) header) of the wireless frame. The wireless frame here may be, for example, a beacon or a probe response frame. For example, the AP 104 may transmit a probe request frame, and the AP 102 may respond to this by transmitting a probe response including an operation information element including the BSS color. This operation information element is, for example, an EHT Operation element, and may be configured as a content compatible with the HE Operation element of IEEE802.11ax. After the negotiation is completed, the M-AP may transmit a wireless frame notifying the S-AP of the BSS color, thereby obtaining information on the BSS color to be set by the S-AP. The S-AP may obtain information on the BSS color of the BSS constructed by the M-AP by other methods. If there is a STA (not shown) that belongs to the BSS2 constructed by the AP104, the AP104 notifies the STA that the BSS color has been changed. Since the AP102 operates as the M-AP, the BSS color1 corresponding to the BSS1 is maintained without being changed. In this example, the case where the negotiation is performed in a state where the AP104 has constructed the BSS2 using the BSS color2 has been described. However, the present invention is not limited to this, and the negotiation may be started in a state where the AP104 has not constructed the BSS2.In this case, the AP that has been determined to operate as the S-AP through negotiation sets the BSS color used in the BSS established by the M-AP as the BSS color to be used in the newly established BSS. This allows the BSS color used in the BSSs established by the M-AP and the S-AP to be the same.

[0041] Thereafter, 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, the AP notifies the STA of operation status information. This operation status information includes the value of the BSS color. As described above, the BSS color is 6-bit information that identifies the BSS included in the preamble of the physical layer (PHY). The BSS color value enables the STA to determine whether the received wireless frame is a frame of the BSS to which the STA belongs (intra-BSS) or a frame of the BSS to which the STA does not belong (inter-BSS).

[0042] In response to establishing a connection with the STA105, the AP104 notifies the AP102 of the information of the STA105 (F708, S803, S812). Here, the information of the STA may include information of the MAC address of the STA. For a STA connected at the time of negotiation, the S-AP may notify the M-AP of the information of the STA at the time of negotiation. Also, at another timing, the S-AP may notify the M-AP of the information of the STA connected to the S-AP. Also, the AP102 may notify the AP104 of the information of the STA connected to the own device. Furthermore, when the AP102 and the AP104 perform JTX to transmit data to a specific STA, the AP connected to the STA may notify the other AP of the information of the STA. However, since the M-AP can specify the STA to which data is to be transmitted in the transmission of data to be transmitted or in a JTX trigger frame, which will be described later, the information may not be provided from the M-AP to the S-AP at this point.

[0043] Thereafter, AP 102 notifies AP 104, operating as an S-AP, of the start of the JTX mode (F709, S804, S813). In the above description, AP 104 changes the BSS color after negotiation and before the start of the JTX mode. However, for example, the BSS color may be changed in response to receiving the start of the JTX mode. This prevents the BSS color from being unnecessarily unified between APs when it takes a long time for the operation in the JTX mode to start after the negotiation, and improves the frequency utilization efficiency of the entire system. On the other hand, by unifying the BSS color immediately after the negotiation, there is no need to change the BSS color after the start of the JTX mode. Therefore, when data for the STA is generated, the data can be immediately transmitted to the STA by JTX.

[0044] After AP102 and AP104 start operating in the JTX mode, when data to be transmitted to STA105 occurs (YES in S805), the data to be transmitted is transmitted from AP102 to AP104 (F710, S806, S814). Since AP104 is operating in the JTX mode, it does not immediately transmit the received data to STA105, but temporarily holds the received data.

[0045] After transmitting and receiving the data to be transmitted, the AP102 transmits a JTX trigger frame (TF) to the AP104 to transmit a wireless frame including the data to be transmitted (F711, S807, S815). The AP102 can use the JTX TF to instruct the AP104 to transmit a wireless frame to the STA105 and specify the timing of the transmission. Then, the AP102 and the AP104 transmit data to the STA105 in parallel (F712, F713, S809, S817) at the timing specified by the JTX TF (YES in S808, YES in S816). The transmission timing can be a predetermined time (SIFS, Short Inter Frame Space) after the transmission and reception of the JTX TF. In this case, the transmission timing is specified by the transmission and reception of the JTX TF itself. In this case, the JTX TF may be transmitted at a timing corresponding to the timing when the AP 102 and the AP 104 should transmit the wireless frame to the STA 105. The JTX TF frame may include information specifying the transmission timing. In this case, the AP 102 and the AP 104 may determine when to transmit the wireless frame using the specified transmission timing and a timer or a clock in the own device. In this way, the AP 102 and the AP 104 can transmit the wireless frame in synchronization using the JTX TF. Note that this wireless frame is a PPDU shown in any one of Figs. 4 to 6, and the BSS color subfield stores a value indicating the BSS color1 set in each BSS as described above. As shown in the above table, the BSS color subfield is the 9th to 14th bits (B8 to B13) of the EHT-SIG-A1 in the case of the EHT SU PPDU or the EHT ER PPDU. In addition, in the case of the EHT MU PPDU, the BSS color subfield is the 6th to 11th bits (B5 to B10) of the EHT-SIG-A1.

[0046] Thereafter, when the AP 102 decides to end the JTX mode based on, for example, that there is no more data to be transmitted to the STA 105, it transmits a notification of the end of the JTX mode to the AP 104 (F714, S810, S818). Note that the AP 102 and the AP 104 may decide to end the JTX mode in various cases, such as when there are no more STAs to which a large amount of data is to be transmitted, or when the number of connected STAs exceeds a predetermined number and radio resources for performing JTX are insufficient.

[0047] When the AP 104 receives this notification of the end of JTX mode, it resets the BSS color to the value before the change (BSS color 2) (F715, S819). At this time, because the AP 104 has changed the BSS color setting, it notifies the connected STA 105 that the BSS color has been changed (F716). As a result, the STA 105 begins to treat wireless frames with BSS color 2 as Intra-BSS frames. Thereafter, when the AP 104 transmits data to the STA 105, it transmits wireless frames with BSS color 2 set (F717).

[0048] Then, for example, AP102 and AP106 decide to perform JTX. In this case, these APs execute JTX negotiation in the same manner as described above, and the AP that has been determined to operate as the S-AP matches its own BSS color with the BSS color of the M-AP (F718 to F722). Then, for example, STA103 executes connection processing with AP106 and transitions to a connected state (F723). In response to this, the processing of F708 to F713 is executed between AP102 and AP106, and wireless frames with the BSS color set to BSS color1 are transmitted to STA103 by JTX from AP102 and AP106. Note that, as described above, the wireless frames transmitted and received between AP104 and STA105 are set to BSS color2, which is different from the BSS color1 transmitted from AP102 and AP106. Therefore, compared to when these BSS colors are common, it is possible to increase the opportunities for transmitting wireless frames to, for example, the STA 105.

[0049] In this way, when multiple APs transmit wireless frames to a common STA in a coordinated manner, the STA can treat the received wireless frame as an Intra-BSS frame by sharing the same BSS color. Furthermore, when coordinated transmission is not performed, the BSS color of the S-AP (or the M-AP in some cases) is changed, so that wireless frames in adjacent BSSs are treated as Inter-BSS frames. As a result, the probability that the STA can obtain a transmission opportunity increases, which makes it possible to improve the frequency utilization efficiency of the entire system.

[0050] The present invention can also be realized by a process in which a program for implementing one or more of the functions of the above-described embodiments is supplied to a system or device via a network or a storage medium, and one or more processors in a computer of the system or device read and execute the program. The present invention can also be realized by a circuit (e.g., ASIC) that implements one or more of the functions.

[0051] The invention is not limited to the above-described embodiments, and various modifications and variations are possible without departing from the spirit and scope of the invention. Accordingly, the following claims are appended to apprise the public of the scope of the invention. [Explanation of symbols]

[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. A station device, a first receiving means for receiving a wireless frame from a first access point device that establishes a first Basic Service Set (BSS); a second receiving means for receiving a wireless frame from a second access point device that establishes a second BSS; having A station device characterized in that when receiving a wireless frame transmitted in cooperation between the first access point device and the second access point device, the value of a BSS color in the first BSS and the value of a BSS color in the second BSS are set to the same value.

2. The station device according to claim 1, characterized in that when receiving a wireless frame transmitted in cooperation between the first access point device and the second access point device, the value of a BSS color in the first BSS is set to the value of a BSS color in the second BSS.

3. the radio frame is a radio frame having a physical layer (PHY) preamble and a data field; The preamble includes a Legacy Short Training Field (L-STF), a Legacy Long Training Field (L-LTF), a Legacy Signal Field (L-SIG), and a Signal Field arranged after the L-SIG, In the preamble, the Signal Field includes a field for setting a BSS color, The station device receives the radio frame in which the BSS color field includes the set BSS color value.

2. The station device according to claim 1 .

4. a third receiving means for receiving, after receiving a wireless frame transmitted in cooperation between the first access point device and the second access point device, a notification frame notifying a change in a value of a BSS color in the first BSS from the first access point device; 2. The station device according to claim 1, further comprising:

5. A communication method for a station device, comprising: a first receiving step of receiving a wireless frame from a first access point device that establishes a first Basic Service Set (BSS); a second receiving step of receiving a wireless frame from a second access point device that establishes a second BSS; having A communication method characterized in that, when receiving a wireless frame transmitted in cooperation between the first access point device and the second access point device, a BSS color value in the first BSS and a BSS color value in the second BSS are set to the same value.

6. 6. The communication method according to claim 5, wherein when receiving a wireless frame transmitted in cooperation between the first access point device and the second access point device, a value of a BSS color in the first BSS is set to a value of a BSS color in the second BSS.

7. the radio frame is a radio frame having a physical layer (PHY) preamble and a data field; The preamble includes a Legacy Short Training Field (L-STF), a Legacy Long Training Field (L-LTF), a Legacy Signal Field (L-SIG), and a Signal Field arranged after the L-SIG, and in the preamble, the Signal Field includes a field for setting a BSS color, The station device receives the radio frame in which the BSS color field includes the set BSS color value.

6. The communication method according to claim 5.

8. a third receiving step of receiving, after receiving a wireless frame transmitted in cooperation between the first access point device and the second access point device, a notification frame notifying a change in a value of a BSS color in the first BSS from the first access point device; 6. The method of claim 5, further comprising:

9. A station device, a receiving means for receiving a wireless frame from an access point device, the wireless frame includes a field for setting a value of a Basic Service Set (BSS) color, and the BSS color field is set with a value of the BSS color set in the access point device depending on whether the access point device and another access point device communicate in a coordinated manner; A station device comprising:

10. A program for causing a computer to function as each of the means included in the station device according to any one of claims 1 to 4.

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