Communication device, communication method, and computer-readable storage medium

Abstract

A communication device, a communication method, and a computer-readable storage medium are provided. A communication device includes a transmission unit configured to transmit a radio frame including a preamble and a data field of a physical layer, wherein 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, wherein the signal field includes a field in which a basic service set (BSS) color is set, and in a case where the communication device and a first other communication device are to cooperatively transmit the radio frame to a second other communication device, a first value in a first BSS color field included in a first radio frame transmitted by the communication device is set to be the same as a second value set in a second BSS color field included in a second radio frame transmitted by the first other communication device.

Description

[0001] This application is a divisional application of the invention patent application filed on February 5, 2020, with application number 202080017271.1 (international application number PCT / JP2020 / 004259) and entitled "Communication Equipment, Communication Method and Computer-Readable Storage Medium". Technical Field

[0002] This invention relates to communication equipment, communication methods, and computer-readable storage media, and more particularly to communication control technology in wireless LANs. Background Technology

[0003] As a communication standard related to wireless LANs (Wireless Local Area Networks), 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 family, OFDMA (Orthogonal Frequency Division Multiple Access) is used to not only achieve high peak throughput, but also improve communication speed under congested conditions (see PTL 1).

[0004] Currently, to further improve throughput, a research group called IEEE 802.11EHT (Extremely High Throughput) has been formed as the successor standard to IEEE 802.11ax. In EHT, to achieve increased throughput, a multi-AP coordinated architecture has been tested, in which multiple access points (APs) arranged in a spatially distributed manner cooperate to send data to a single STA (station).

[0005] Reference List

[0006] Patent documents

[0007] PTL 1: Japanese Patent Application Publication No. 2018-050133 Summary of the Invention

[0008] Technical issues

[0009] The IEEE 802.11ax standard defines the use of identification information called BSS (Basic Service Set) colors. If a communication device receives a radio frame with the same BSS color as the AP connected to it, that radio frame is treated as a frame within the BSS. On the other hand, in IEEE 802.11EHT, as mentioned above, the use of multi-AP coordination structures has been verified. How the BSS color is set in this case is unclear.

[0010] Technical solutions to the problem

[0011] The present invention provides the following technique: appropriately implementing settings for enabling multiple access points to send data to a terminal simultaneously.

[0012] According to one aspect of the present invention, a communication device is provided, comprising: a forming unit for forming a first basic service set (BSS); and a transmitting unit for transmitting a radio frame, the radio frame including a physical layer (PHY) preamble and a data field, characterized in that the preamble includes: a conventional short training field (L-STF); a conventional long training field (L-LTF) arranged immediately after the L-STF in the frame; a conventional signal field (L-SIG) arranged immediately after the L-LTF in the frame; and an extremely high throughput (ETH) signal field arranged after the L-SIG in the frame. (EHT-SIG-A); an ETH short training field (EHT-STF) arranged in the frame after the EHT-SIG-A; and an EHT long training field (EHT-LTF) arranged in the frame immediately after the EHT-STF, wherein the EHT-SIG-A includes a subfield for setting the BSS color, and if the communication device and the first other communication device are to cooperate in transmitting the radio frame to the second other communication device, the value of the subfield is set based on the BSS color of the second BSS to which the second other communication device belongs, without changing the BSS color used in the first BSS.

[0013] Advantages of the present invention

[0014] According to the present invention, settings for enabling multiple access points to simultaneously send data to a terminal can be appropriately implemented.

[0015] Other features and advantages of the invention will become clearer from the following description taken in conjunction with the accompanying drawings. Note that throughout the drawings, the same reference numerals denote the same or similar parts. Attached Figure Description

[0016] The accompanying drawings, which are incorporated in and form part of this specification, illustrate embodiments of the invention and, together with the textual description, serve to explain the principles of the invention.

[0017] Figure 1 This is a diagram illustrating an example of network construction;

[0018] Figure 2 This is a block diagram illustrating an example of the hardware configuration of an AP or STA;

[0019] Figure 3 This is a block diagram illustrating an example of the functional structure of an AP or STA;

[0020] Figure 4This is a diagram illustrating an example of the PHY frame structure of an EHT SU PPDU;

[0021] Figure 5 This is a diagram illustrating an example of the PHY frame structure of an EHT ER PPDU;

[0022] Figure 6 This is a diagram illustrating an example of the PHY frame structure of an EHT MU PPDU;

[0023] Figure 7 This is a sequence diagram illustrating an example of a processing procedure performed in a network; and

[0024] Figure 8 This is a flowchart illustrating an example of a processing procedure performed in the AP. Detailed Implementation

[0025] The embodiments will be described in detail below with reference to the accompanying drawings. Note that the following embodiments are not intended to limit the scope of the invention. Several features are described in the embodiments, but this does not limit the invention to requiring all of these features; rather, multiple such features can be appropriately combined. Furthermore, in the drawings, the same or similar constructions are given the same reference numerals, and redundant descriptions thereof are omitted.

[0026] (Network Construction)

[0027] Figure 1 An example of the construction of a wireless communication network according to this embodiment is shown. The wireless communication network is constructed to include access points (AP102 and AP104) and terminals (STA103 and STA105) as IEEE 802.11 EHT (Extremely High Throughput) devices. In the following description, unless a specific device is mentioned, the access point may be referred to as "AP" and the station may be referred to as "STA" without reference numerals. Note that in... Figure 1 The example shown includes a wireless communication network with two access points (APs) and two STAs, but the number of communication devices can be, for example, three or more. Figure 1 In the diagram, the communicable area of ​​the network formed by AP 102 and AP 104 is represented by circle 101. Note that this communicable area can cover a larger area or only a smaller area. Additionally, although... Figure 1 The diagram shows a STA compliant with the IEEE 802.11 EHT standard, but STAs that only support the previous generation of standards (legacy standards) prior to IEEE 802.11 EHT may also exist. Note that EHT is an abbreviation for Extreme High Throughput.

[0028] Note that in this example, each of AP 102 and AP 104 can receive signals transmitted from other APs. Note that the connection method is not particularly limited, and AP 102 and AP 104 can be connected via wired or wireless connections. AP 102 and AP 104 support a multi-AP coordination configuration supporting IEEE 802.11 EHT and can cooperatively transmit data to a single STA simultaneously. For example, STA 105 can simultaneously transmit / receive radio frames to / from the cooperating APs 102 and AP 104. STA 105 can be configured, for example, to include multiple wireless LAN control units and use different radio channels to transmit / receive radio frames to / from multiple APs. Note that STA 105 may include a physical control unit capable of processing multiple frames received simultaneously via multiple radio channels. That is, STA 105 has a configuration capable of physically using one or more control devices to logically handle multiple wireless communications simultaneously.

[0029] (Equipment Structure)

[0030] Figure 2 The hardware configurations of each of the APs (AP 102 and AP 104) and STAs (STA 103 and STA 105) are shown. As an example of its hardware configuration, the communication device includes 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.

[0031] Storage unit 201 is composed of either ROM or RAM, and stores programs for performing various operations described later, as well as various information such as communication parameters for wireless communication. Note that in addition to memories such as ROM and RAM, storage media such as floppy disks, hard disks, optical disks, magneto-optical disks, CD-ROMs, CD-Rs, magnetic tapes, non-volatile memory cards, or DVDs can be used as storage unit 201.

[0032] 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), or an FPGA (Field-Programmable Gate Array). Here, CPU is an abbreviation for Central Processing Unit, and MPU is an abbreviation for Micro Processing Unit. The control unit 202 executes the program stored in the storage unit 201, thereby controlling the entire device. Note that the control unit 202 can control the entire device through cooperation between the program stored in the storage unit 201 and the OS (Operating System).

[0033] Additionally, control unit 202 controls functional unit 203 to perform predetermined processes such as imaging, printing, or projection. Functional unit 203 is the hardware used by the device to perform the predetermined processes. For example, if the device is a camera, functional unit 203 is an imaging unit and performs imaging processing. For example, if the device is a printer, functional unit 203 is a printing unit and performs printing processing. For example, if the device is a projector, functional unit 203 is a projection unit and performs projection processing. The data to be processed by functional unit 203 may be data stored in storage unit 201, or data communicated with other APs or STAs via communication unit 206 (described later).

[0034] Input unit 204 receives various operations from the user. Output unit 205 provides various outputs to the user. Here, the outputs of output unit 205 may include at least one of the following: display on a screen, audio output from a speaker, vibration output, etc. Note that input unit 204 and output unit 205 can both be implemented as a single module, such as a touch panel.

[0035] Communication unit 206 controls wireless communication conforming to the IEEE 802.11 EHT standard family, or controls IP communication. In this embodiment, communication unit 206 can perform processing that conforms to at least the IEEE 802.11 EHT standard. Additionally, communication unit 206 controls antenna 207 to transmit and receive radio signals for wireless communication. The device communicates with other communication devices via communication unit 206 regarding content such as image data, document data, and video data. Antenna 207 is an antenna capable of transmitting and receiving signals in at least one of the following bands: sub-GHz band, 2.4GHz band, 5GHz band, and 6GHz band. Note that there are no particular limitations on the frequency bands (and combinations of frequency bands) to which antenna 207 is applicable. Antenna 207 can be a single antenna, or a group of two or more antennas for MIMO (Multiple-Input Multiple-Output) transmission / reception. Figure 2 An antenna 207 is shown, but the antenna may include two or more antennas (two or more sets of antennas) suitable for different frequency bands. Antenna 207 is configured for distributed coordinated communication suitable for the IEEE 802.11 EHT standard. For example, the AP has a configuration capable of transmitting D-MIMO (Distributed MIMO) for JTX (Joint Transmission).

[0036] Note that JTX is a component used to implement the multi-AP coordination function expected to be introduced from IEEE 802.11 EHT, and represents multiple APs cooperating to simultaneously transmit data to a STA. Multi-AP coordination is a function that enables multiple APs to operate cooperatively to improve transmit / receive throughput or signal strength on the STA side. As a wireless technology at this time, D-MIMO can be used. D-MIMO is a technique that allows multiple APs to communicate with a STA at the same time and on the same frequency channel (e.g., in the same RU (Resource Unit) of OFDMA (Orthogonal Frequency-Division Multiple Access). According to D-MIMO, high-speed communication can be achieved due to improved space utilization efficiency. The minimum configuration of D-MIMO includes an M-AP (Master AP), an S-AP (Slave AP), and a STA. In this case, under the control of the M-AP, two APs (i.e., the M-AP and the S-AP) cooperate to simultaneously (synchronously) transmit radio frames to a STA.

[0037] Figure 3 Examples of the functional configurations of the various communication devices (AP 102 and AP 104) are shown. As an example, the 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, and an antenna 306.

[0038] The wireless LAN control unit 301 is configured to include circuitry for transmitting / receiving radio signals to / from other wireless LAN devices (e.g., other APs or STAs), and a program configured to control these circuits. The wireless LAN control unit 301 performs wireless LAN communication control according to the IEEE 802.11 standard family, such as transmitting frames generated by the frame generation unit 302 and receiving radio frames from other wireless LAN devices. The frame generation unit 302 generates radio frames to be transmitted by the wireless LAN control unit 301 based on, for example, data received from other APs and intended to be transmitted to the STA. Additionally, the frame generation unit 302 generates, for example, radio frames including data that other APs should transmit to the STA, or timing trigger frames (JTX TF) for instructing the transmission of data-included radio frames to the STA.

[0039] The BSS color setting unit 303 sets the BSS color of radio frames. For example, when its own device (AP 102 or AP 104) forms 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 sets the BSS color value for radio frames to be sent to STAs connected to its own device. On the other hand, when transmitting data to a STA connected to another AP via JTX, the BSS color setting unit 303 sets the BSS color used in the BSS formed by the other AP for the radio frames to be sent to the STA. That is, when transmitting radio frames via JTX to a STA connected to an AP other than its own device, the BSS color setting unit 303 does not use the BSS color used in the BSS formed by its own device, but uses the BSS color of the other AP. Accordingly, multiple radio frames received by the STA can be processed as radio frames with the BSS color set in the BSS connected to the STA. For this purpose, the STA can process all multiple radio frames received from multiple APs as frames within the BSS. On the other hand, since the BSS color setting unit 303 sets the BSS color of the BSS formed by its own device for radio frames other than JTX, STAs connected to other APs can treat the radio frames as inter-BSS frames. Note that STAs can perform different control processes depending on whether the received radio frame is an intra-BSS frame or an inter-BSS frame. For example, if the received power of the radio frame does not exceed a predetermined value, the STA can transmit the radio frame. The predetermined value related to inter-BSS frames can be set to a value higher than the predetermined value related to intra-BSS frames. Accordingly, even if the radio frame is received with a power greater than the predetermined value related to intra-BSS frames, the STA will still have a transmission opportunity if the radio frame is an inter-BSS radio frame. Therefore, when an AP uses a different BSS color than other APs at times other than JTX, the communication opportunities for STAs connected to other APs can be increased, and the frequency utilization efficiency of the entire system can be improved.

[0040] The UI control unit 304 is configured to include hardware related to the user interface (UI) (such as touch panels and buttons configured to accept operations of the AP by a user (not shown) on the AP), and a program configured to control this hardware. Note that the UI control unit 304 also has functions such as presenting information to the user, such as displaying images or audio output. The storage unit 305 is configured to include a storage device, such as ROM (Read-Only Memory) or RAM (Random Access Memory), configured to store programs to be executed by the communication device.

[0041] Note that a STA has the functions of a typical STA. A STA can also receive radio frames transmitted in a coordinated manner by multiple APs.

[0042] (Frame Structure)

[0043] Reference Figures 4 to 6 Describe a structural example of a PPDU (Physical Layer (PHY) Protocol Data Unit) conforming to the IEEE 802.11 EHT standard. Figure 4 An example of an EHT SU (single-user) PPDU as a PPDU for single-user communication is shown. Figure 5 An example of an EHT MU (Multi-User) PPDU for multi-user communication is shown. Figure 6 An example of an EHT ER (Extended Range) PPDU for long-distance transmission is shown. EHT ER PPDUs are used when the communication area should be extended in communication between an AP and a single STA. Note that the fields of the PPDU do not always need to be specified in order. Figures 4 to 6 The arrangement shown may include the following sequence: Figures 4 to 6 New field not shown.

[0044] PPDU includes fields such as STF (Short Training Field), LTF (Long Training Field), and SIG (Signal Field). For example... Figure 4 As shown, the PPDU header includes L-STF 401, L-LTF 402, and L-SIG 403 to ensure backward compatibility with the IEEE 802.11a / b / g / n / ax standards. Note that... Figure 5 and Figure 6 The various frame formats shown include L-STF (L-STF 501 or L-STF 601), L-LTF (L-LTF 502 or L-LTF 602), and L-SIG (L-SIG 503 or RL-SIG 603). Note that L-LTF is placed immediately after L-STF, and L-SIG is placed immediately after L-LTF. Figures 4 to 6 The various structures shown also include an RL-SIG (a repeated L-SIG, RL-SIG 404, RL-SIG 504, or RL-SIG 604) immediately following the L-SIG. The contents of the L-SIG are repeated in the RL-SIG field. The RL-SIG is used to enable the receiver to identify that the PPDU conforms to a standard following IEEE 802.11ax, and in some cases, it can be omitted in IEEE 802.11EHT. Alternatively, instead of the RL-SIG, a field can be set to enable the receiver to identify that the PPDU conforms to IEEE 802.11EHT.

[0045] L-STF 401 is used for detecting physical layer (PHY) frames, AGC (Automatic Gain Control), timing detection, etc. L-LTF 402 is used for high-precision frequency / time synchronization, obtaining propagation channel information (CSI: Channel State Information), etc. L-SIG 403 is used for transmitting control information, including information such as data transmission rate and PHY frame length. Conventional devices conforming to IEEE 802.11a / b / g / n / ax standards can decode these conventional fields.

[0046] Each PPDU also includes multiple EHT-SIGs (EHT-SIG-A 405, EHT-SIG-A 505, EHT-SIG-B 506, or EHT-SIG-A 605) immediately following the RL-SIG and used to transmit EHT control information. Each PPDU also includes the EHT STF (EHT-STF 406, 507, or 606) and the EHT LTF (EHT-LTF 407, 508, or 607). Each PPDU includes a data field 408, 509, or 608 and a packet extension field 409, 710, or 609 following these control fields. The portion including the fields from the L-STF to the EHT-LTF of each PPDU is called the PHY preamble.

[0047] Notice, Figures 4 to 6 The examples shown in the table illustrate PPDUs that ensure backward compatibility. However, if backward compatibility is not required, the traditional fields can be omitted, for example. In this case, EHT-STF and EHT-LTF can be used instead of L-STF and L-LTF to establish synchronization. In this case, one of the multiple EHT-LTF fields following the EHT-SIG field and the EHT-STF can be omitted.

[0048] The EHT-SIG-A 405 and 605 included in the EHT SU PPDU and EHT ER PPDU respectively include EHT-SIG-A1 and EHT-SIG-A2 required for receiving the PPDU, as shown in Tables 1 and 2 below. EHT-SIG-A1 includes a 6-bit "BSS Color" subfield. Furthermore, Figure 5 The EHT-SIG-A 505 of the EHT MU PPDU shown includes EHT-SIG-A1 and EHT-SIG-A2 required for receiving the PPDU, as shown in Tables 3 and 4 below. The PPDU also includes a 6-bit "BSS Color" subfield in EHT-SIG-A1. Note that the construction of Tables 1 through 4 is merely illustrative; information beyond that shown in these tables may be included in the EHT-SIG fields, and some information shown in these tables may be excluded from the EHT-SIG fields.

[0049] Table 1

[0050]

[0051]

[0052] Table 2

[0053]

[0054] Table 3

[0055]

[0056] Table 4

[0057]

[0058] (Processing procedure)

[0059] The following will refer to Figure 7 and Figure 8 Examples of the processes performed by the AP and the processes performed by the wireless communication network, as described above. Figure 7 An example of processing in a wireless communication network is shown. Figure 8 An example of the processing procedure performed by AP 102 and AP 104 is shown.

[0060] First, AP 102 forms a first BSS (BSS1) (F701, step S801). Note that in this embodiment, BSS1 is configured to use BSS color 1. Furthermore, AP 104 forms a second BSS (BSS2) (F702, step S801). Here, in this embodiment, BSS2 is configured to use BSS color 2, which is different from BSS color 1. Each AP notifies the IEEE 802.11 beacon at predetermined intervals and accepts connection requests from STAs, thereby setting up a state that enables the AP to coordinate communication between STAs and other STAs or between STAs and DS (Distributed System).

[0061] AP 102 performs a connection procedure with STA 103 and transitions to a connected state (F703). Similarly, AP 104 performs a connection procedure with STA 105 and transitions to a connected state (F704). Through this connection procedure, the AP notifies the STA of its operational status information, as in IEEE 802.11ax. The operational status information includes the BSS color value. As mentioned above, the BSS color is a 6-bit information used to identify the BSS included in the preamble of the physical layer (PHY). Based on the BSS color value, the STA can determine whether the received radio frame is a frame from its own BSS (within the BSS) or a frame from a BSS not belonging to the STA (between BSSs).

[0062] AP 102 can send a radio frame (F705) to STA 103. This radio frame is... Figures 4 to 6 The PPDU shown in the image indicates that the value of BSS color 1 used in BSS1 is stored in the BSS color subfield. Similarly, AP104 can send a radio frame (F706) to STA 105. This radio frame is... Figures 4 to 6 The PPDU shown above indicates that the value of BSS color 2 used in BSS2 is stored in the BSS color subfield. In the case of EHT SU PPDU or EHT ERPPDU, the BSS color subfield is formed by bits 9 to 14 (B8 to B13) of EHT-SIG-A1, as shown in the table above. In the case of EHT MU PPDU, the BSS color subfield is formed by bits 6 to 11 (B5 to B10) of EHT-SIG-A1.

[0063] Subsequently, AP 102 and AP 104 decide to cooperate in simultaneously transmitting data to a common STA. For example, if a large amount of data to be sent to STA 105 is detected, AP 104 may decide to cooperate with AP 102, another AP present in the periphery, to send data to STA 105. Furthermore, even if there is no plan for massive data communication with a specific STA, AP 102 or AP 104 may decide to prepare for cooperative transmission with other APs in preparation for future massive data communication. If it is decided that multiple APs will cooperate in transmission or prepare for it, AP 102 and AP 104 negotiate for JTX (Joint Transmission) (F707, step S802). Note that in the following text, the negotiation for JTX is sometimes 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, AP 102 decides to operate as an M-AP (F708, "Yes" in step S803), and AP 104 decides to operate as an S-AP (F709, "No" in step S803). Additionally, in this negotiation, it can be determined which AP should be associated with the STA that is the object of the JTX.

[0064] After negotiation, AP 104, acting as the S-AP, informs AP 102, acting as the M-AP, of information about STA 105 connected to its own device and information about BSS color 2 used in BSS2 formed by its own device (F710, steps S804 and S811). Here, the STA information may include information such as the STA's MAC (Media Access Control) address. Note that this information can be notified to the M-AP from the S-AP at other times, allowing information to be exchanged between APs, for example, during negotiation. Furthermore, AP 102 can notify AP 104 of information about STA 103 connected to its own device and information about BSS color 1 used in BSS1 formed by its own device. Additionally, if AP 102 and AP 104 perform JTX to send data to a specific STA, the AP connected to the STA can notify other APs of the STA's information and BSS color information. However, since the M-AP can specify the STA and BSS color as the data transmission target in the transmission of the data to be sent or the JTX trigger frame, as described later, it is not always necessary for the M-AP to provide information to the S-AP.

[0065] Subsequently, AP 102 notifies AP 104 of the start of JTX mode as part of S-AP operation (F711, steps S805 and S812). Then, when transmit target data is generated for STA 105 ("Yes" in step S806), the transmit target data is sent from AP 102 to AP 104 (F712, steps S807 and S813). Instead of immediately sending the received data to STA 105, AP 104 temporarily holds the received data because it is operating in JTX mode.

[0066] Note that when sending data from M-AP to S-AP, the M-AP can notify the S-AP of the BSS color to be used. In this embodiment, since the data is sent to STA 105 via JTX, the BSS color 2 used in AP 104 connected to STA 105 can be notified as the BSS color to be used. Note that if the BSS color to be used matches the BSS color used in S-AP, or if the BSS color to be used by JTX is known in advance, it is not necessary to notify the S-AP of the BSS color information from M-AP. That is, if data is sent to a STA connected to S-AP via JTX, or if BSS color information is exchanged with a STA that is the data recipient of JTX, M-AP does not need to notify the S-AP of the BSS color information. Note that, for example, when sending data to STA 103 via JTX, AP 102 can notify AP 104 of the BSS color 1 as the BSS color to be used. Note that if data is transmitted via the PPDU described above, the PPDU includes a PHY preamble for informing the BSS color, thus indicating the BSS color to be used. In this case, the S-AP receives a radio frame that sets a BSS color different from the one used by its own device. However, since the S-AP operates in JTX mode, the data in the radio frame is not discarded.

[0067] After transmitting / receiving the target data, AP 102 sends a JTX trigger frame (TF) to AP 104 to cause AP 104 to transmit a radio frame including the target data (F713, steps S808 and S814). Through the JTX TF, AP 102 can instruct AP 104 to transmit a radio frame to STA 105 and specify the timing of the transmission. For example, at the timing specified by the JTX TF ("Yes" in step S809), AP 102 and AP 104 simultaneously transmit data to STA 105 (F714, F715, step S810). Note that the transmission timing can be a timing that occurs after a predetermined time (SIFS, Short Inter Frame Space) elapsed from the transmission / reception of the JTX TF. In this case, the transmission timing is indicated by the transmission / reception of the JTX TF itself. In this case, the JTX TF can be transmitted at a timing that corresponds to the timing at which AP 102 and AP 104 should transmit a radio frame to STA 105. Alternatively, information specifying the transmission timing can be included in the JTX TF frame. In this case, AP 102 and AP 104 can use the specified transmission timing and their own timers or clocks to determine when to transmit the radio frame. As described above, AP 102 and AP 104 can transmit radio frames synchronously using the JTX TF.

[0068] Note that in this data transmission, the BSS color used by the BSS (AP connected to the STA) to which the data is being transmitted is set in the PHY preamble of the radio frame. Figure 7In the example shown, BSS color 2 used in BSS2 of STA 105, the target of data transmission, is set in the radio frame. That is, AP 104 directly transmits radio frames using BSS color 2 used in its own equipment, while AP 102 transmits radio frames using BSS color 2, which is different from BSS color 1 used in its own equipment. The BSS color of BSS1 formed by AP 102 is not changed from BSS color 1. That is, AP 102 does not change the BSS color of the BSS formed by its own equipment. However, in order to transmit data via JTX, AP 102 sets the BSS color used in the BSS of the STA to which the data is destined in the radio frame and transmits the data. At this time, even if AP 102 is operating in JTX mode, AP 102 can transmit data to the STA (STA 103) connected to its own equipment. In this case, AP 102 can set the BSS color 1 used in BSS1 formed by its own equipment in the radio frame and transmit the data. That is, during operation in JTX mode, AP 102 sets the BSS color of the BSS to which the STA belongs in the radio frame and transmits data. This also applies to AP 104. In other words, AP 104 uses BSS color 2 in its own BSS2. However, for example, if AP 102 instructs to transmit data to STA 103 via JTX, AP 104 can send a radio frame to STA 103 with BSS color 1 set. Note that in this case, AP 104 does not change the BSS color of BSS2.

[0069] Since each AP does not change the BSS color in its own BSS, it never instructs connected STAs to change their BSS color. Therefore, the STA's settings are never unnecessarily changed, thus suppressing, for example, an increase in the STA's power consumption. On the other hand, in JTX, since the BSS color in the PHY preamble of the radio frame is set according to the BSS to which the STA belongs, the STA can receive radio frames without changing its BSS color settings.

[0070] This invention can be implemented by providing a program for implementing one or more functions of the above embodiments to a system or device via a network or storage medium, and causing one or more processors in the computer of the system or device to read and execute the program. This invention can also be implemented by a circuit (e.g., an ASIC) for implementing one or more functions.

[0071] This invention is not limited to the embodiments described above, and various changes and modifications can be made within the spirit and scope of this invention. Therefore, claims are made to disclose the scope of this invention.

Claims

1. A communication device comprising: The transmitting unit is used to transmit radio frames, which include a physical layer preamble and a data field. The preamble includes: Traditional short training field (L-STF); Traditional Long Training Field (L-LTF); Traditional signal field (L-SIG); and The signal field arranged after the conventional signal field (L-SIG), The signal field includes a field for setting the Basic Service Set (BSS) color, and when the communication device and the first other communication device are to cooperate in transmitting the radio frame, the first value in the first BSS color field included in the first radio frame transmitted by the communication device is set to the same as the second value set in the second BSS color field included in the second radio frame transmitted by the first other communication device.

2. The communication device according to claim 1, wherein, When the communication device and the first other communication device do not cooperate in transmitting the radio frame, the first value in the first basic service set color field included in the first radio frame is set to be different from the second value set in the second basic service set color field included in the second radio frame transmitted by the first other communication device.

3. A communication method performed by a communication device, comprising: The transmission step involves transmitting a radio frame, which includes a physical layer preamble and a data field. The preamble includes: Traditional short training field (L-STF); Traditional Long Training Field (L-LTF); Traditional signal field (L-SIG); and The signal field arranged after the conventional signal field (L-SIG), The signal field includes a field for setting the Basic Service Set (BSS) color, and when the communication device and the first other communication device are to cooperate in transmitting the radio frame, the first value in the first BSS color field included in the first radio frame transmitted by the communication device is set to the same as the second value set in the second BSS color field included in the second radio frame transmitted by the first other communication device.

4. The communication method according to claim 3, wherein, When the communication device and the first other communication device do not cooperate in transmitting the radio frame, the first value in the first basic service set color field included in the first radio frame is set to be different from the second value set in the second basic service set color field included in the second radio frame transmitted by the first other communication device.

5. A computer-readable storage medium storing a program configured to cause a computer to perform the communication method according to claim 3.

Images