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, for further throughput improvement, 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] The IEEE 802.11ax 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 AP to which it is connected, it treats that wireless frame as an Intra-BSS frame. On the other hand, while the use of a Multi-AP Coordination configuration is being considered in IEEE 802.11EHT as described above, it is not yet clear how the BSS color should be set in this case.

[0006] This invention provides a method for appropriately configuring multiple access points to transmit data to a terminal in parallel. [Means for solving the problem]

[0007] An access point according to one aspect of the present invention is a different access point Receives a trigger frame from and communicates with the other access point. A control means that performs cooperative operation in accordance with the IEEE 802.11 standard, P Having a rambil and a data field For the aforementioned coordinated operation It has a transmitting means for wirelessly transmitting frames, and the transmitting means The frame transmitted by The preamble includes information on the Basic Service Set (BSS) color set for the other access point. nothing, It is characterized by the following: [Effects of the Invention]

[0008] According to the present invention, it is possible to properly configure multiple access points to transmit data to a terminal in parallel. [Brief explanation of the drawing]

[0009] [Figure 1] This figure shows an example of a network configuration. [Figure 2] This figure shows an example of the hardware configuration for AP and STA. [Figure 3] This figure shows an example of the functional configuration of AP and STA. [Figure 4] This figure shows an example of the PHY frame structure for EHT SU PPDU. [Figure 5] This figure shows an example of the PHY frame structure of EHT ER PPDU. [Figure 6] This figure shows an example of the PHY frame structure for EHT MU PPDU. [Figure 7] This figure shows an example of the processing flow executed in a network. [Figure 8] This diagram shows an example of the processing flow executed in AP. [Modes for carrying out the invention]

[0010] The embodiments will be described in detail below with reference to the attached drawings. Note that the following embodiments do not limit the invention as defined in the claims. While the embodiments describe multiple features, not all of these features are essential to the invention, and the features may be combined in any way. Furthermore, in the attached drawings, identical or similar configurations are given the same reference numerals, and redundant descriptions are omitted.

[0011] (Network configuration) Figure 1 shows an example of the configuration of the wireless communication network of this embodiment. This wireless communication network consists of access points (AP102, AP104, AP106) and terminals (STA103, STA105) that comply with IEEE802.11EHT (Extremely High Throughput). Hereafter, when not referring to a specific device, access points may be referred to as "AP" and terminals (stations) as "STA" without using reference numbers. Note that Figure 1 shows a wireless communication network including three APs and two STAs as an example, but the number of these communication devices may naturally differ from the number shown. Also, EHT may be understood as an abbreviation for Extreme High Throughput.

[0012] In Figure 1, the communication range of the network formed by AP102, AP104, and AP106 is indicated by circle 101. Note that this communication range may cover a wider area or only a narrower area. Furthermore, while Figure 1 illustrates an STA compliant with the IEEE 802.11EHT standard, there may also be STAs that support only older standards (legacy standards) prior to the IEEE 802.11EHT standard.

[0013] In this example, AP102 and AP104, and AP102 and AP106, are assumed to be able to receive signals transmitted by the other AP. The connection configuration is not particularly limited; AP102 and AP104 may be connected by wire or wirelessly. AP104 and AP106 may or may not be able to communicate with each other. AP102 and AP104 or AP106 support the IEEE 802.11EHT Multi-AP Coordination configuration and are assumed to be able to cooperate to transmit data in parallel to a single STA. For example, STA105 can send and receive wireless frames in parallel with AP102 and AP104, which are operating in cooperation. STA105 may have, for example, multiple wireless LAN control units and be configured to send and receive wireless frames with multiple APs using different wireless channels. STA105 may have a single physically controlled unit capable of processing multiple frames received in parallel via multiple wireless channels. In other words, the STA105 has a configuration that allows it to logically process multiple wireless communications in parallel using one or more physical control devices.

[0014] (Device configuration) Figure 2 shows the hardware configurations of APs (AP102, AP104, AP106) and STAs (STA103, STA105). As an example of their hardware configurations, these communication devices include 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 either or both of a ROM and a RAM, 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 initialism of Central Processing Unit, and MPU is the initialism of Micro Processing Unit. The control unit 202 controls the entire device by executing the programs stored in the storage unit 201. Note that the control unit 202 may control the entire device in cooperation with the programs stored in the storage unit 201 and the OS (Operating System).

[0017] Further, 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, when the device is a camera, the functional unit 203 is an imaging unit and performs an imaging process. Also, for example, when the device is a printer, the functional unit 203 is a printing unit and performs a printing process. Also, for example, when the device is a projector, the functional unit 203 is a projection unit and performs a projection process. The 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 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 IP communication. In this embodiment, the communication unit 206 can perform processing compliant with at least the IEEE 802.11 EHT 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, for example, an antenna capable of transmitting and receiving at least one of the sub-GHz band, 2.4GHz band, 5GHz band, and 6GHz band. The frequency bands (and their combinations) that the antenna 207 can handle are not particularly limited. The antenna 207 may be a single antenna or a set of two or more antennas for MIMO (Multi-Input and Multi-Output) transmission and reception. Although Figure 2 shows a single antenna 207, it may include, for example, two or more antennas (two or more sets) each capable of handling different frequency bands. Antenna 207 is configured to support Distributed Coordination communication according to the IEEE 802.11EHT standard. For example, the AP is configured to enable D-MIMO (Distributed MIMO) transmission for JTX (Joint Transmission).

[0020] JTX is one element for realizing the Multi-AP Coordination function, which is scheduled to be newly introduced in IEEE 802.11EHT. It refers to multiple APs cooperating to transmit data to a single STA in parallel. The Multi-AP Coordination function is a function in which multiple APs work together to improve the transmit / receive throughput and signal strength on the STA side. D-MIMO can be used as the wireless technology in this case. D-MIMO is a technology in which multiple APs communicate with a single STA at the same time and on the same frequency channel (for example, the same RU (Resource Unit) in OFDMA (Orthogonal Frequency Division Multiple Access)). With D-MIMO, high-speed communication can be achieved by improving the efficiency of space utilization. The minimum configuration of D-MIMO is an M-AP (master AP), an S-AP (slave AP), and an STA. In this case, under the control of the M-AP, the two APs, the M-AP and the S-AP, cooperate to transmit wireless frames to a single STA in parallel (simultaneously).

[0021] Figure 3 shows an example of the functional configuration of APs (AP102, AP104, AP106). As an example, an AP includes 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 sending and receiving wireless signals with other wireless LAN devices (e.g., other APs and STAs) and programs for controlling them. The wireless LAN control unit 301 performs 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 IEEE 802.11 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 wireless frames containing data to be transmitted to the STA by other APs, and trigger frames (JTX TF) that indicate the timing at which the wireless frames containing that 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 device (AP102, AP104, or AP106) constructs a BSS (Basic Service Set), the BSS color setting unit 303 sets the BSS color to be used in that BSS. The BSS color setting unit 303 may set different BSS colors depending on whether or not it transmits data to the STA in cooperation with other APs. For example, if the BSS color setting unit 303 does not perform cooperative transmission with other APs, it uses a BSS color that is different from the default BSS color set in the device or the BSS color set in other BSSs in the vicinity. In this embodiment and the attached claims, the BSS color relating to a BSS constructed by an AP when the AP does not perform cooperative transmission is called the BSS color corresponding to that BSS. That is, the BSS color set in a given BSS, regardless of its relationship with BSSs constructed by other APs, is the BSS color corresponding to that BSS. On the other hand, when performing coordinated transmission with other APs, the BSS color setting unit 303 sets the BSS color according to the decision of the role determination unit 306, which will be described later. That is, when coordinated transmission is performed, APs performing coordinated transmission should transmit wireless frames with the same BSS color set. For this reason, when coordinated transmission is performed, the BSS color is set considering the relationship with other APs. Once the BSS color is set by the BSS color setting unit 303, the frame generation unit 302 generates wireless frames with that BSS color set. These wireless frames include, for example, not only frames for data transmission to the STA, but also Beacon frames, etc. In other words, the AP is in a state of constructing a BSS using the set BSS color. As a result, APs that transmit wireless frames through coordinated transmission will construct a BSS with a common BSS color, and therefore, multiple wireless frames transmitted in coordination and received at the STA will have a common BSS color set.In this case, since one of the APs performing coordinated transmission is connected to the STA, the wireless frames received by the STA will have the BSS color of the BSS to which the STA belongs set. Therefore, the STA can treat all wireless frames received from multiple APs as Intra-BSS frames.

[0024] On the other hand, if the BSS color setting unit 303 is not performing coordinated transmission with other APs, it may revert the BSS color to the default value. That is, if the BSS color setting unit 303 had changed its own device's BSS color to the BSS color of a BSS constructed by another AP for coordinated transmission, it will revert the BSS color setting to its original value. Also, if the BSS color setting unit 303 has not changed its own device's BSS color, it will continue to use that BSS color even after the end of coordinated transmission. In this case, other APs may revert the BSS color setting to its original value. However, if multiple BSSs constructed by multiple APs performing coordinated transmission originally used the same BSS color, the BSS color does not need to be changed after the end of coordinated transmission. Furthermore, in some cases, frequency utilization efficiency can be improved by using different BSS colors in multiple BSSs with adjacent communication ranges. For example, an STA may perform different controls depending on whether the received wireless frame is an Intra-BSS frame with the BSS color of the BSS to which the device belongs set, or an Inter-BSS frame with a different BSS color set. An STA may transmit a wireless frame if the received power of the wireless frame does not exceed a predetermined value, but the predetermined value for Inter-BSS frames may be higher than the predetermined value for Intra-BSS frames. As a result, even if a wireless frame is received with power exceeding the predetermined value for Intra-BSS frames, if that wireless frame is an Inter-BSS wireless frame, the STA may still have an opportunity to transmit. Therefore, by having an AP use a different BSS color than other APs, the STA's opportunities for communication can be increased, and the overall frequency utilization efficiency of the system can be improved. Accordingly, if multiple BSSs constructed by multiple APs performing coordinated transmission originally used the same BSS color, at least one of those APs may change its BSS color.

[0025] The UI control unit 304 includes hardware related to a user interface (UI), such as a touch panel or buttons, for receiving operations on the AP by a user (not shown) of the AP, and a program to control them. The UI control unit 304 also has functions for presenting information to the user, such as displaying images or outputting sound. The storage unit 305 includes storage devices such as ROM (Read Only Memory) and RAM (Random Access Memory) for storing programs executed by the AP and various data.

[0026] The role determination unit 306 negotiates with other APs when coordinating with them to transmit wireless frames to a common STA. Through this negotiation, the role determination unit 306 determines whether to operate as an M-AP, which controls the coordinated transmission, or as an S-AP controlled by the M-AP. The BSS color setting unit 303 does not change the BSS color (for example, uses the default value) when the device operates as an M-AP. In this case, the BSS color of the device is set to the BSS color of the BSS constructed by the other AP operating as an S-AP. On the other hand, when the device operates as an S-AP, the BSS color setting unit 303 sets the BSS color of the BSS constructed by the device to match the BSS color of the BSS constructed by the M-AP.

[0027] Furthermore, the STA has the functionality of a general STA. However, the STA may also have the functionality to receive wireless frames transmitted in a Multi-AP Coordination configuration.

[0028] (Frame structure) Figures 4 to 6 illustrate examples of PPDU (Physical Layer (PHY) Protocol Data Unit) structures compliant with the IEEE 802.11 EHT standard. Figure 4 shows an example of an EHT SU (Single User) PPDU for single-user communication, and Figure 5 shows an example of an EHT MU (Multi User) PPDU for multi-user communication. Figure 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 have to be in the order shown in Figures 4 to 6, and it may include new fields not shown in Figures 4 to 6.

[0029] The PPDU includes the fields STF (Short Training Field), LTF (Long Training Field), and SIG (Signal Field). As shown in Figure 4, the beginning of the PPDU has L(Legacy)-STF401, L-LTF402, and L-SIG403 to ensure backward compatibility with the IEEE 802.11a / b / g / n / ax standards. The frame formats in Figures 5 and 6 also include L-STF (L-STF501 and L-STF601), L-LTF (L-LTF502 and L-LTF602), and L-SIG (L-SIG503 and L-SIG603). Note that L-LTF is placed immediately after L-STF, and L-SIG is placed immediately after L-LTF. Furthermore, in the configurations shown in Figures 4 to 6, an RL-SIG (Repeated L-SIG, RL-SIG404, RL-SIG504, RL-SIG604) is included immediately after the L-SIG. The RL-SIG field transmits the content of the L-SIG repeatedly. The RL-SIG allows the receiver to recognize that the PPDU conforms to standards later than IEEE 802.11ax, and may be omitted in IEEE 802.11EHT in some cases. Alternatively, a field may be provided to allow the receiver to recognize that the PPDU conforms to IEEE 802.11EHT instead of the RL-SIG.

[0030] L-STF401 is used for detecting physical layer (PHY) frame signals, automatic gain control (AGC), and timing detection. L-LTF402 is used for high-precision synchronization of frequency and time, and acquisition of channel state information (CSI). L-SIG403 is used to transmit control information including data transmission rate and PHY frame length information. Legacy equipment conforming to IEEE 802.11a / b / g / n / ax standards can decode the above-mentioned 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 the EHT, located immediately after the RL-SIG. Each PPDU also has an STF (EHT-STF406, 507, 606) and an LTF (EHT-LTF407, 508, 607) for the EHT. Following these control fields, each PPDU has data fields 408, 509, 608 and Packet extension fields 409, 710, 609. The fields from L-STF to EHT-LTF in each PPDU are called the PHY preamble.

[0032] Figures 4 to 6 show an example of a PPDU that ensures backward compatibility. However, if backward compatibility is not required, legacy fields may be omitted, for example. In this case, EHT-STF or EHT-LTF may be used instead of L-STF and L-LTF to establish synchronization. In this case, one of the EHT-STF or EHT-LTF fields following the EHT-SIG field may be omitted.

[0033] The EHT-SIG-A405 and EHT-ER PPDU, respectively, contain EHT-SIG-A405 and EHT-SIG-A605, which are necessary for receiving the PPDU, as shown in Tables 1 and 2 below. EHT-SIG-A1 includes a 6-bit "BSS color" subfield. Similarly, the EHT-SIG-A505 of the EHT MU PPDU in Figure 5 also contains EHT-SIG-A1 and EHT-SIG-A2, which are necessary for receiving the PPDU, as shown in Tables 3 and 4 below. In this PPDU as well, EHT-SIG-A1 includes a 6-bit "BSS color" subfield. Note that the configurations in Tables 1 to 4 are merely examples, and other information may be included in the EHT-SIG field, or some of the information shown in these tables may be omitted from the EHT-SIG field.

[0034] [Table 1]

[0035] [Table 2]

[0036] [Table 3]

[0037] [Table 4]

[0038] (Process flow) Next, we will explain the processing flow performed by the AP as described above, and an example of the processing flow performed in the wireless communication network, using Figures 7 and 8. Figure 7 shows an example of the processing flow in the wireless communication network, and Figure 8 shows an example of the processing flow performed by each AP. In this example, AP102 constructs the first BSS (BSS1) (F701), and AP104 constructs the second BSS (BSS2) (F702). Here, in this embodiment, BSS1 is set to use BSS color1, and BSS2 is set to use BSS color2, which is different from BSS color1. Each AP broadcasts an IEEE802.11 Beacon at regular intervals and accepts connection requests from STAs, thereby mediating communication between STAs or between STAs and DS (Distribution System).

[0039] Subsequently, AP102 and AP104 decide to cooperate and transmit data to a common STA in parallel. For example, if AP104 detects that there is a large amount of data to be sent to STA105, it may decide to cooperate with another AP nearby, such as AP102, to transmit the data to STA105 in parallel. Also, AP102 or AP104 may decide to prepare for cooperative transmission with other APs in anticipation of future large-volume data communications, even if there are no plans for large-volume data communications to a specific STA. If it is decided that cooperative transmission by multiple APs will be performed or that preparations for such transmission will be made, AP102 and AP104 will negotiate for JTX (Joint Transmission) (F703, S801). In the following, the negotiation for JTX may be simply referred to as "negotiation". During the negotiation, the AP performing the negotiation may decide whether to operate as an M-AP or an S-AP. Here, it is decided that AP102 will operate as an M-AP (YES in F704 and S802), and AP104 will operate as an S-AP (NO in F705 and S802). Furthermore, during this negotiation, it may be decided which AP will associate with which STA that will perform JTX.

[0040] Following the negotiation to determine the roles of each AP, the BSS color is set accordingly. Specifically, the S-AP sets the BSS color of its configured BSS to the same value as the M-AP's BSS color. In this example, AP104 changes the BSS color of its configured BSS2 from BSS color2 to BSS color1 (F706, S811). Note that the S-AP may obtain the M-AP's BSS color information during negotiation. However, it is not limited to this; for example, the S-AP may operate as an STA, receive a wireless frame from the M-AP, and obtain the BSS color information by analyzing the PHY preamble (or MAC (Media Access Control) header) of that wireless frame. The wireless frame here could be, for example, a Beacon or a Probe response frame. For example, AP104 may send a Probe request frame, and AP102 may respond by sending a Probe response containing operational information elements including the BSS color. This operational information element is, for example, an EHT Operation element and can be configured to be compatible with the HE Operation element of IEEE 802.11ax. Alternatively, after the negotiation is complete, the M-AP may send a wireless frame notifying the BSS color to the S-AP, thereby obtaining the information on the BSS color that the S-AP should set. The S-AP may also obtain the BSS color information of the BSS constructed by the M-AP by other means. If there is an STA (not shown) belonging to BSS2 constructed by AP104, AP104 will notify that STA that the BSS color has been changed. AP102 operates as an M-AP and therefore maintains BSS color1, which corresponds to BSS1, without changing it. 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, and for example, negotiation may start even if AP104 has not constructed BSS2.In this case, the AP that is determined to operate with S-AP through negotiation sets the BSS color used in the BSS constructed by M-AP as the BSS color to be used in the newly constructed BSS. This unifies the BSS color used in the BSS constructed in both M-AP and S-AP.

[0041] Subsequently, AP104 performs a connection procedure with STA105 and transitions to a connected state (F707). In this connection procedure, as in the case of IEEE802.11ax, operational status information is notified from AP to STA. This operational status information includes the BSS color value. As mentioned above, the BSS color is 6 bits of information that identifies the BSS included in the physical layer (PHY) preamble. The BSS color value allows STA to determine whether the received wireless frame is a frame of its own BSS (intra-BSS) or a frame of a BSS not to which it belongs (inter-BSS).

[0042] Upon establishing a connection with STA105, AP104 notifies AP102 of STA105's information (F708, S803, S812). Here, STA information may include the STA's MAC address, etc. Note that S-AP may notify M-AP of the STA's information at the time of negotiation if it is connected to an STA at that time. Alternatively, S-AP may notify M-AP of the STA connected to S-AP at another time. AP102 may also notify AP104 of the STA connected to its own device. Furthermore, if AP102 and AP104 perform JTX to send data to a specific STA, the AP connected to that STA may notify the other AP of the STA's information. However, since M-AP can specify the STA to be transmitted in the transmission of the data to be sent or in the JTX trigger frame, etc., as described later, it is not necessary for M-AP to provide information to S-AP at this point.

[0043] Subsequently, AP102 notifies AP104, which is operating as an S-AP, of the start of JTX mode (F709, S804, S813). In the above explanation, AP104 changes the BSS color after negotiation but before this JTX mode start notification. However, it is also possible to change the BSS color in response to receiving the JTX mode start notification. This prevents unnecessary unification of BSS colors between APs when there is a long time between negotiation and the start of operation in JTX mode, thereby improving the overall frequency utilization efficiency of the system. On the other hand, by unifying the BSS color immediately after negotiation, there is no need to change the BSS color after the start of JTX mode, so when data to STA is generated, that data can be sent to STA via JTX immediately.

[0044] After AP102 and AP104 begin operating in JTX mode, when data to be transmitted to STA105 is generated (YES in S805), AP102 transmits that data to AP104 (F710, S806, S814). Since AP104 is operating in 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, AP102 sends a JTX trigger frame (TF) to AP104 to cause AP104 to transmit a wireless frame containing this data (F711, S807, S815). AP102 can use the JTX TF to instruct AP104 to transmit the wireless frame to STA105 and to specify the timing of that transmission. Then, AP102 and AP104 simultaneously transmit data to STA105 at the timing specified by the JTX TF (YES in S808, YES in S816) (F712, F713, S809, S817). The transmission timing may 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 may be transmitted at a timing corresponding to when AP102 and AP104 should transmit a wireless frame to STA105. The JTX TF frame may also contain information specifying the transmission timing. In this case, AP102 and AP104 can determine when to transmit the wireless frame using the specified transmission timing and their own internal timers or clocks. Thus, using the JTX TF, AP102 and AP104 can transmit wireless frames synchronously. This wireless frame is a PPDU as shown in one of Figures 4 to 6, and the BSS color subfield stores a value indicating BSS color1, as set for each BSS as described above. As shown in the table above, in the case of EHT SU PPDU and EHT ER PPDU, the BSS color subfield is the 9th to 14th bits (B8 to B13) of EHT-SIG-A1. Furthermore, the BSS color subfield, in the case of EHT MU PPDU, is the 6th to 11th bits (B5 to B10) of EHT-SIG-A1.

[0046] Subsequently, if AP102 decides to terminate JTX mode, for example, based on the fact that there is no more data to transmit to STA105, it sends a JTX mode termination notification to AP104 (F714, S810, S818). AP102 and AP104 may decide to terminate JTX mode in various cases, such as when there are no more STAs to transmit large amounts of data to, or when the number of connected STAs exceeds a predetermined number and there are insufficient wireless resources to perform JTX.

[0047] When AP104 receives the notification that this JTX mode has ended, it reverts the BSS color to its previous value (BSS color2) (F715, S819). At this time, AP104 notifies the connected STA105 that the BSS color setting has been changed (F716). As a result, STA105 will treat wireless frames with BSS color2 as Intra-BSS frames. Subsequently, when AP104 sends data to STA105, wireless frames with BSS color2 set are sent (F717).

[0048] Subsequently, let's assume that AP102 and AP106 decide to perform JTX. In this case, these APs perform JTX negotiation in the same manner as described above, and the AP that is determined to operate as an S-AP matches its own BSS color with the M-AP's BSS color (F718~F722). Subsequently, let's assume that STA103 performs connection processing with AP106 and transitions to a connected state (F723). Accordingly, processing F708~F713 is executed between AP102 and AP106, and a wireless frame with BSS color set to BSS color1 is transmitted from AP102 and AP106 to STA103 via JTX. As described above, the wireless frame transmitted and received between AP104 and STA105 will have BSS color2 set, which is different from BSS color1 transmitted from AP102 and AP106. Therefore, compared to the case where these BSS colors are common, it is possible to increase the opportunities to transmit wireless frames to, for example, STA105.

[0049] As described above, when multiple APs coordinately transmit wireless frames to a common STA, standardizing the BSS color allows the STA to treat received wireless frames as Intra-BSS frames. Furthermore, when coordinated transmission ends, the BSS color of the S-AP (and possibly the M-AP) is changed, so that if coordinated transmission does not occur, wireless frames in adjacent BSSs are treated as Inter-BSS frames. As a result, the probability of the STA obtaining a transmission opportunity increases, making it possible to improve the overall frequency utilization efficiency of the system.

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

[0051] The invention is not limited to the embodiments described above, and various modifications and variations are possible without departing from the spirit and scope of the invention. Accordingly, claims are attached to disclose 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: Memory unit, 306: Role determination unit

Claims

1. It is an access point, A control means that receives trigger frames from other access points and performs cooperative operation with those other access points in accordance with the IEEE 802.11 standard, It includes a transmitting means for wirelessly transmitting a frame for the cooperative operation having a preamble and a data field, An access point characterized in that the frame transmitted by the transmission means includes information on the Basic Service Set (BSS) color set on the other access point in the preamble.

2. The access point according to claim 1, characterized in that the aforementioned cooperative operation in accordance with the IEEE 802.11 standard is a cooperative operation relating to Multi-AP Coordination as defined in the IEEE 802.11 standard.

3. The access point according to claim 1 or 2, characterized in that the transmitting means wirelessly transmits the frame using at least one of the frequency bands of the sub-GHz band, 2.4GHz band, 5GHz band, and 6GHz band.

4. The access point according to any one of claims 1 to 3, characterized in that the transmitting means transmits the frame wirelessly by MIMO (Multi-Input and Multi-Output) communication using a plurality of antennas.

5. The access point according to any one of claims 1 to 4, further comprising a receiving means for wirelessly receiving BSS color information set on the other access point from the other access point.

6. The access point according to claim 5, characterized in that the receiving means receives BSS color information set on the other access point using at least one of the frequency bands of the sub-GHz band, 2.4GHz band, 5GHz band, and 6GHz band.

7. The access point according to claim 5 or 6, characterized in that the receiving means wirelessly receives information on the BSS color set on the other access point by MIMO (Multi-Input and Multi-Output) communication using multiple antennas.

8. The access point according to any one of claims 1 to 7, further comprising negotiation means for negotiating with other access points for determining roles related to cooperative operation.

9. The aforementioned preamble is, L-Short Training Field (L-STF) and, In the frame, the L-Long Training Field (L-LTF) is positioned immediately after the L-STF, In the aforementioned frame, an L-Signal Field (L-SIG) is positioned immediately after the L-LTF, In the frame, a Repeated L-Signal Field (RL-SIG) is positioned immediately after the L-SIG, In the frame, a first Signal Field is positioned after the RL-SIG, In the frame, a first Short Training Field is positioned after the first Signal Field, In the frame, a first Long Training Field is positioned immediately after the first Short Training Field, Includes, The first Signal Field includes a subfield for setting information related to the BSS color, The access point according to any one of claims 1 to 8, characterized in that the access point transmits the frame, which includes information about the BSS color set on the other access point in the subfield.

10. The access point according to claim 9, characterized in that the number of bits in the subfield is 6 bits.

11. The access point according to any one of claims 1 to 10, characterized in that the BSS color information set on the other access point is different from the BSS color information set on the access point.

12. The access point according to any one of claims 1 to 11, characterized in that the trigger frame includes information specifying the timing at which the access point should transmit the frame.

13. The access point according to any one of claims 1 to 12, characterized in that the trigger frame includes information for synchronizing the transmission timing of the frame by the access point with the transmission timing of the frame for the cooperative operation by the other access points.

14. The access point according to any one of claims 1 to 13, wherein the trigger frame includes information identifying the station to which the access point should transmit the frame.

15. A method for controlling an access point, A control process that receives a trigger frame from another access point and performs cooperative operation with that other access point in accordance with the IEEE 802.11 standard, The system includes a transmission step of wirelessly transmitting a frame for the cooperative operation having a preamble and a data field, A method for controlling an access point, characterized in that the frame transmitted in the transmission step includes information on the Basic Service Set (BSS) color set for the other access point in the preamble.

16. A program for causing a computer to function as each of the means of an access point according to any one of claims 1 to 14.

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