Access point device, communication device, communication method, and program

Abstract

An access point device for performing communication conforming to the IEEE 802.11 standard series communicates with another communication device belonging to a first network constructed by the access point device using either a first channel access method that uses at least a predetermined Primary channel in one link or a second channel access method that uses a Non-Primary channel different from the Primary channel among a plurality of channels included in the link without using the Primary channel. If a radio frame related to the occupancy of one or more channels including the Primary channel is received from another access point device constructing a second network different from the first network and the one or more channels including the Primary channel are occupied in the second network, the access point device transmits, to the other communication device, a notification indicating that the second channel access method should be used or the transmission of the radio frame is prohibited.

Description

Access point device, communication device, communication method, and program

[0001] The present invention relates to a communication technique in a communication device capable of communicating using a communication link made up of a plurality of channels.

[0002] In recent years, with the increase in the amount of data being communicated, development of communication technologies such as wireless LANs (Local Area Networks) has been progressing. The Institute of Electrical and Electronic Engineers (IEEE) 802.11 standard series is known as a major communication standard for wireless LANs. The IEEE 802.11 standard series includes IEEE 802.11a / b / g / n / ac / ax / be standards, etc. In order to further improve communication reliability, development of the IEEE 802.11bn standard is underway as a successor to the IEEE 802.11be standard. In the IEEE 802.11 Working Group (WG), which formulates the IEEE 802.11bn standard, the UHR SG will determine the goals and scope of the standard, and the TGbn will specify the detailed technical content to be included in the standard. UHR SG is an abbreviation for Ultra High Reliability Study Group. TGbn is an abbreviation for Task Group bn.

[0003] As one of the candidate technologies to be included in the IEEE 802.11bn standard, a technology for efficiently utilizing frequency resources in a communication method using a communication link configured with multiple channels is being considered. For example, Patent Document 1 describes a technology for performing communication using another channel when a primary channel used to acquire a transmission right cannot be used.

[0004] U.S. Pat. No. 1,169,6353

[0005] The present invention provides a technique for more efficiently utilizing frequency resources in a communication system that uses a communication link consisting of multiple channels.

[0006] A communication device according to one aspect of the present invention is an access point device that communicates in accordance with the IEEE 802.11 standard series, and has communication means for communicating with other communication devices that belong to a first network constructed by the access point device using either a first channel access method that uses at least a specified primary channel in one link, or a second channel access method that does not use the primary channel and uses a non-primary channel different from the primary channel among multiple channels included in the link, and the communication means receives a wireless frame regarding the occupancy of one or more channels including the primary channel from another access point device that constructs a second network different from the first network, and when one or more channels including the primary channel are occupied in the second network, transmits a notification to the other communication device instructing it to use the second channel access method or instructing it to prohibit the transmission of wireless frames.

[0007] According to the present invention, it is possible to more efficiently utilize frequency resources in a communication system that uses a communication link made up of multiple channels.

[0008] Other features and advantages of the present invention will become apparent from the following description taken in conjunction with the accompanying drawings, in which the same or similar elements are designated by the same reference numerals.

[0009] The accompanying drawings are incorporated into and constitute a part of the specification, illustrate embodiments of the present invention, and together with the description, are used to explain the principles of the present invention. FIG. 1 is a diagram illustrating an example of the configuration of a wireless communication system. FIG. 2A is a schematic diagram illustrating an example of a time chart when a communication device transmits data. FIG. 2A is a schematic diagram illustrating an example of a time chart when a communication device transmits data. FIG. 3 is a diagram illustrating an example of the hardware configuration of a communication device. FIG. 4 is a diagram illustrating an example of the functional configuration of a communication device. FIG. 5 is a diagram illustrating an example of the flow of communication in a wireless communication system. FIG. 6A is a diagram illustrating an example of the flow of processing performed by an AP. FIG. 6B is a diagram illustrating an example of the flow of processing performed by an AP. FIG. 7A is a diagram illustrating an example of the flow of processing performed by an AP. FIG. 7B is a diagram illustrating an example of the flow of processing performed by an AP. FIG. 8A is a diagram illustrating an example of the flow of processing performed by an AP. FIG. 8B is a diagram illustrating an example of the flow of processing performed by an AP. FIG. 9 is a diagram illustrating an example of the flow of processing performed by an AP. FIG. 10A is a diagram illustrating an example of the flow of processing performed by an STA. FIG. 10B is a diagram illustrating an example of the flow of processing performed by an STA. FIG. 10C is a diagram illustrating an example of the flow of processing performed by an STA. FIG. 11 is a diagram showing an example of the flow of processing performed by a STA. FIG. 12 is a diagram showing an example of the flow of processing performed by a STA. FIG. 13 is a diagram showing an example of the flow of processing performed by a STA. FIG. 14 is a diagram showing another example of the flow of communication in a wireless communication system. FIG. 15A is a diagram showing a modified example of the flow of processing performed by an AP. FIG. 15B is a diagram showing a modified example of the flow of processing performed by an AP. FIG. 16A is a diagram showing a modified example of the flow of processing performed by an AP. FIG. 16B is a diagram showing a modified example of the flow of processing performed by an AP. FIG. 17A is a diagram showing a modified example of the flow of processing performed by an AP. FIG. 17B is a diagram showing a modified example of the flow of processing performed by an AP. FIG. 18 is a diagram showing a modified example of the flow of processing performed by an AP. FIG. 19A is a diagram showing a modified example of the flow of processing performed by a STA. FIG. 19B is a diagram showing a modified example of the flow of processing performed by a STA.Fig. 19C is a diagram showing a modified example of the flow of processing executed by the STA. Fig. 20 is a diagram showing a modified example of the flow of processing executed by the STA. Fig. 21 is a diagram showing a modified example of the flow of processing executed by the STA.

[0010] Hereinafter, embodiments will be described in detail with reference to the accompanying drawings. Note that the following embodiments do not limit the scope of the invention claimed. Although multiple features are described in the embodiments, not all of these multiple features are necessarily essential to the invention, and multiple features may be combined arbitrarily. Furthermore, in the accompanying drawings, the same reference numerals are used to designate the same or similar components, and redundant explanations will be omitted.

[0011] (System Configuration) FIG. 1 shows an example configuration of a wireless communication system according to this embodiment. The wireless communication system includes, for example, an access point (AP 101) and a station (STA 102). The AP 101 and the STA 102 are communication devices capable of performing wireless communication in accordance with the IEEE 802.11 standard series. In this embodiment, when there is no need to distinguish between the AP 101 and the STA 102, they may be collectively referred to as communication devices. IEEE stands for Institute of Electrical and Electronics Engineers. FIG. 1 shows a configuration in which the STA 102 participates in a network 103 established by the AP 101. The network 103 may also be called a Basic Service Set (BSS). FIG. 1 illustrates a state in which a network 113 composed of AP 111 and STA 112 exists near a network 103 composed of AP 101 and STA 102. Like AP 101 and STA 102, AP 111 and STA 112 are communication devices capable of performing wireless communication compliant with the IEEE 802.11 standard series. For AP 101 and STA 102, network 103 is a BSS to which they connect and may be referred to as their own BSS. Meanwhile, for AP 101 and STA 102, network 113 is a network that may cause interference with their own BSS and may be referred to as an overlapping BSS (OBSS). While FIG. 1 illustrates an example in which one AP and one STA exist in each of the two networks, multiple APs and multiple STAs may exist within a single network. Furthermore, multiple STAs may be connected to one AP, and one STA may be connected to multiple APs. Although the following description focuses on the AP 101 and the STA 102, the AP 111 and the STA 112 can also have similar functions.

[0012] In this embodiment, the AP 101 and the STA 102 are configured to be able to execute a communication method conforming to the IEEE 802.11bn standard. The IEEE 802.11bn standard is a successor to the IEEE 802.11be standard, which targets a maximum transmission speed of 46.08 Gbps (Giga bit per second). The IEEE 802.11bn standard is expected to include, as its main features, functions for realizing highly reliable communication, low latency communication, and improved throughput when communication traffic is congested. A wireless frame used in a communication method conforming to this standard may be called a UHR (Ultra High Reliability) PPDU. PPDU stands for PLCP Protocol Data Unit, and PLCP stands for Physical Layer Convergence Protocol. It should be noted that names such as UHR and IEEE 802.11bn may be changed to other names once the standards are fully established. It should also be noted that this specification and the claims appended hereto are applicable to communication devices using all successor standards to IEEE 802.11be. Furthermore, the communication device may be compatible with at least one legacy standard that predates the IEEE 802.11bn standard. Examples of legacy standards include the IEEE 802.11a / b / g / n / ac / ax / be standards. The communication device may also be compatible with other communication standards such as Bluetooth (registered trademark), NFC, UWB, ZigBee, MBOA, etc. UWB stands for Ultra Wide Band, and MBOA stands for Multi Band OFDM Alliance. NFC stands for Near Field Communication. UWB includes wireless USB, wireless 1394, WiNET, etc. The communication device may also be compatible with communication standards such as wired LAN. The AP 101 may be, for example, a wireless LAN router or a personal computer (PC), but is not limited to these. The AP 101 may be an information processing device such as a wireless chip capable of performing wireless communication compatible with the IEEE 802.11bn standard, etc.The STA 102 may be, for example, but is not limited to, a camera, a tablet, a smartphone, a PC, a mobile phone, a video camera, a headset, etc. The STA 102 may be an information processing device such as a wireless chip capable of performing wireless communication compatible with the IEEE 802.11bn standard or the like.

[0013] A communication device may transmit and receive wireless signals using frequency bands such as the 2.4 GHz band, 3.6 GHz band, 5 GHz band, and 6 GHz band, as well as the 45 GHz band and 60 GHz band known as millimeter waves. The frequency bands used by the communication device are not limited to these bands and may include, for example, the Sub-1 GHz band. Furthermore, the communication device may communicate using bandwidths of 20 MHz, 40 MHz, 80 MHz, 160 MHz, 320 MHz, 540 MHz, 640 MHz, 1080 MHz, and 2160 MHz. The bandwidths used by the communication device are not limited to these bands and may include, for example, bandwidths of 240 MHz and 4 MHz. The IEEE 802.11 standard series specifies a frequency channel using a 20 MHz bandwidth as the basic channel in frequency bands such as the 2.4 GHz, 5 GHz, and 6 GHz bands. This standard also defines multiple available channels in the 2.4 GHz, 5 GHz, and 6 GHz frequency bands. This standard allows communication devices to use a channel in combination with an adjacent channel. This use of a channel in combination with an adjacent channel may be referred to as channel bonding. A channel bundle formed by one or two or more adjacent channels may be referred to as a communication link. For example, a link formed by two channels with a bandwidth of 20 MHz may use a bandwidth of 40 MHz. The IEEE 802.11be standard is expected to specify 320 MHz as the maximum bandwidth available for a single link. Signals transmitted in this bandwidth may be continuous or discontinuous on the frequency axis. The AP 101 and the STA 102 may be an AP MLD (Multi-Link Device) and a STA MLD, respectively, that support Multi-Link, which simultaneously establishes multiple links for communication.

[0014] When transmitting a signal using a link established with another communication device, a communication device performs carrier sensing to determine whether transmission is possible. Carrier sensing is an operation in which a communication device determines the presence or absence of a signal on a channel that the communication device intends to use for transmission. For example, the communication device measures the strength of a signal received on a channel (received signal strength) and determines that a signal is present when the received signal strength exceeds a predetermined threshold (physical carrier sense). The received signal strength may also be referred to as a Received Signal Strength Indicator (RSSI). Furthermore, the communication device may determine the presence or absence of a signal based on information such as a Duration field included in the signal received on the channel (virtual carrier sense). For example, the communication device stores the period indicated by the Duration field included in the received signal as a Network Allocation Vector (NAV) within the communication device. The communication device may treat the stored NAV as a period during which transmission of wireless frames from the communication device is prohibited. In this embodiment, the operation of a communication device to set a period during which the device will not transmit based on information such as the Duration field of a received signal is referred to as setting a NAV. That is, until the NAV set for a channel expires, the communication device determines that a signal is present on the channel. In this way, the communication device determines whether a signal is present on the channel based on the results of performing physical carrier sensing and virtual carrier sensing. If the communication device determines that a signal is present on the channel, it may determine that transmission is not possible. The channel state in this case may be referred to as a busy state. On the other hand, a state in which no signal is detected on the channel during carrier sensing and no NAV is set may be referred to as an idle state. If the channel is in an idle state, the communication device may determine that transmission is possible.

[0015] For example, when communicating using a link with a bandwidth of 160 MHz, a communication device may determine whether or not to transmit using only a first channel with a bandwidth of 20 MHz included in the link. This first channel may be called a Primary Channel (PCH). For example, the IEEE 802.11 series of standards describes that a communication device can start transmission if it determines that transmission is possible as a result of performing carrier sensing on the PCH for a predetermined period of time. The predetermined period is determined by an Interframe Space (IFS) defined for each access category that classifies the type of communication traffic, and a random number (backoff counter) randomly determined from a predetermined range. In other words, if the communication device determines that the PCH is idle for this predetermined period of time, it acquires the right to transmit using that link. At this time, if a second channel other than the PCH is idle during the PIFS period immediately before the start of transmission, the communication device may perform transmission using channel bonding using the idle channel and the PCH. PIFS is an abbreviation for Priority Interframe Space. Furthermore, if a communication device determines that transmission is not possible as a result of carrier sensing on a PCH, the communication device may postpone transmission even if other channels included in the same link are idle. Each second channel other than the PCH that constitutes a link may also be called a secondary channel (SCH) or a non-primary channel (NPCH).

[0016] In a communication device, when a signal is received on a certain channel, if a signal is transmitted on another channel (e.g., an adjacent channel) located at a frequency close to the received channel, the received signal may not be received properly. For example, a communication device may be capable of simultaneously performing transmission and reception processes using different channels. When a communication device is receiving on a certain channel and then transmitting on an adjacent channel, the power of the transmitted signal may leak into the channel of the received signal, causing interference with the received signal. Generally, the power of such leakage of the transmitted signal is much greater than the received power of the received signal, making it impossible to properly receive the received signal. To avoid this situation, the IEEE 802.11 standard series provides a mechanism to prevent other communication devices from transmitting signals to a communication device using a channel adjacent to the PCH while the communication device is transmitting a signal. That is, the PCH is provided as a channel commonly used between communication devices to determine whether or not to transmit, and it is specified that while one communication device is transmitting on the PCH, the other communication device shall not transmit, even if the other channel is idle. As a result, while a communication device is transmitting a signal and a PCH is in use, other communication devices will not transmit signals using a channel adjacent to the PCH, preventing the communication device from receiving a signal on that adjacent channel, thereby eliminating the problem of interference caused by power leakage between channels.

[0017] However, not using other idle channels (NPCHs) based on the PCH being busy can hinder efficient use of frequency resources across the link. Figure 2A shows an example of a time chart when the STA 102 transmits data to the AP 101. In Figure 2A, the STA 102 performs carrier sensing on the PCH, confirms that the PCH is idle, and then transmits data using the PCH with a 20 MHz bandwidth. In this case, even if, for example, seven NPCHs other than the PCH are idle, other communication devices are not permitted to communicate using the NPCHs. Figure 2B also shows another example of a time chart when the STA 102 transmits data to the AP 101. In Figure 2B, while the STA 102 is performing carrier sensing on the PCH, the PCH is being used by another network (e.g., network 113 in Figure 1) located geographically near the STA 102. In this case, the PCH is determined to be busy by the carrier sense performed by STA 102, and therefore, even if the seven NPCHs other than the PCH are idle, STA 102 is not permitted to communicate with AP 101 using the NPCH. However, because AP 101 is not transmitting at this time, even if STA 102 transmits to AP 101 using the NPCH, AP 101 can properly receive the signal transmitted by STA 102. In this way, if the PCH with a bandwidth of, for example, 20 MHz is used by another network, the remaining 140 MHz of idle NPCHs are not utilized, resulting in inefficient use of frequency resources.

[0018] In view of such circumstances, this embodiment provides a function for performing communication between communication devices using NPCHs included in the same link as the PCH, without using the PCH, when the PCH is being used by another communication device. As an example, when the PCH is busy, the communication device sets a Secondary Primary Channel (SPCH) to be used to acquire a transmission right for transmission using the NPCH. The SPCH is one or more channels among the NPCHs included in the same link as the PCH. If the communication device determines that the PCH is being used by another communication device, it then determines whether transmission is possible on the SPCH. That is, the communication device performs the above-mentioned carrier sense on the SPCH and determines that communication using the NPCH is possible based on confirming that the SPCH is in an idle state. Then, if the communication device determines that transmission is possible on the SPCH, it performs transmission using one or more NPCHs including the SPCH. In this embodiment, a communication method in which transmission is performed using one or more channels including an SPCH without using a PCH is called NPCH access (Non-Primary Channel Access). Note that this communication method may be called by other names. For example, this communication method may be called SCA (Secondary Channel Access). When a PCH is available, a communication device performs communication using a first communication method in which communication is performed in one communication link using a PCH and one or more NPCHs. On the other hand, the communication device is configured to be able to perform communication using a second communication method (NPCH access) when a certain further condition (e.g., an NPCH is not being used) is satisfied, provided that a PCH is not available.

[0019] As shown in FIG. 2A , the AP 101 and the STA 102 may perform NPCH access if they confirm that the PCH is not idle (is being used by the OBSS). On the other hand, as shown in FIG. 1 , for example, the STA 102 may be located in a position where it cannot receive signals transmitted from the AP 111 or the STA 112 with sufficient power. If the STA 102 is located in such a position, it may not be able to detect the PCH being used by the OBSS. Therefore, the STA 102 may determine that the PCH is not being used and attempt to transmit a signal using the PCH. Meanwhile, the AP 101 may determine to use NPCH access by detecting signals from the AP 111 or the STA 112. In other words, it is possible that the AP 101 and the STA 102 may make inconsistent decisions regarding whether to perform NPCH access.

[0020] In this embodiment, in consideration of such circumstances, for example, AP 111 transmits a wireless frame to a communication device in an OBSS (network 103) different from the BSS (network 113) established by AP 111, requesting occupancy of a channel set as the PCH in that OBSS. This wireless frame requests that network 113 established by AP 111 occupy one or more channels, including the channel used as the PCH of network 103. Hereinafter, this wireless frame will be referred to as an occupancy request frame. Then, upon receiving this occupancy request frame, AP 101 determines whether to permit occupancy of one or more channels, including the PCH, and transmits a wireless frame including the result of this determination. This wireless frame is a response to the occupancy request frame and will be referred to as an occupancy response frame below. The occupancy response frame does not necessarily have to be received by AP 111, but is transmitted at least in response to the reception of the occupancy request frame. This occupancy response frame is received by a STA (e.g., STA 102) in the BSS (e.g., network 103) to which occupancy of the PCH has been requested. As a result, in the BSS for which PCH occupancy has been requested, it is shared that NPCH access should be used when communication is performed during a period in which the channel used as the PCH in that BSS is occupied by the OBSS (the BSS that requested occupancy). In one example, assume that AP 101 is located in a position where it can receive an occupancy request frame from AP 111, and STA 102 is unable to receive this occupancy request frame. When AP 101 receives this occupancy request frame, it transmits an occupancy response frame to its surroundings. This occupancy response frame allows STA 102 to recognize that the PCH is occupied by the OBSS (here, network 113), and to recognize that communication should be performed using NPCH access.

[0021] The configuration of a communication device that performs such processing and an example of the processing flow will be described in detail below.

[0022] (Device Configuration) Fig. 3 shows an example of the hardware configuration of communication devices (AP 101, AP 111, STA 102, and STA 112). The communication devices have a storage unit 301, a control unit 302, a function unit 303, an input unit 304, an output unit 305, a communication unit 306, and an antenna 307. Note that these are just examples, and the communication devices may have further components not shown in Fig. 3, or some or all of the components shown in Fig. 3 may be replaced with other components having similar functions.

[0023] The storage unit 301 includes one or more memories such as a ROM or a RAM. The storage unit 301 stores various information such as computer programs for performing various operations described below and communication parameters for wireless communication. ROM stands for Read Only Memory, and RAM stands for Random Access Memory. The storage unit 301 may include storage media 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, and a DVD, in addition to memories such as a ROM or a RAM. The storage unit 301 may also include storage media such as a plurality of memories.

[0024] The control unit 302 includes one or more processors, such as a CPU or an MPU. The CPU stands for Central Processing Unit, and the MPU stands for Micro Processing Unit. The control unit 302 controls the entire communication device by executing a computer program stored in the storage unit 301. The control unit 302 may control the entire device through cooperation between the computer program stored in the storage unit 301 and an operating system. The control unit 302 also generates data and signals (radio frames) to be transmitted in communication with other communication devices. The control unit 302 may also include multiple processors, such as a multi-core processor, and the entire communication device may be controlled by the multiple processors.

[0025] The control unit 302 also controls the functional unit 303 to perform predetermined processes such as wireless communication, image capture, printing, and projection. The functional unit 303 is configured to include hardware that enables the communication device to perform predetermined processes. If the communication device is a printer, the functional unit 303 is a printing device that prints image data acquired via the communication unit 306, for example. If the communication device is a scanner, the functional unit 303 is a reading device that outputs image data generated by scanning to the outside, for example, via the communication unit 306. If the communication device is a camera, the functional unit 303 is configured to include an image sensor and a lens, and outputs image data captured by the camera to the outside, for example, via the communication unit 306.

[0026] The input unit 304 includes, for example, a touch panel, hard keys, buttons, etc., and accepts various operations from the user. The output unit 305 includes, for example, a display, a speaker, etc., and provides various outputs to the user. Here, the output by the output unit 305 may be a screen display output on a display or an audio output from a speaker. The output unit 305 may also include a vibrator and may output information by vibration output. Note that both the input unit 304 and the output unit 305 may be implemented by a single module, such as a touch panel display. The input unit 304 and the output unit 305 may be built into the communication device or may be implemented by an external input / output device. In this case, the communication device has an input / output interface for connecting to the input / output device.

[0027] The communication unit 306 executes control for wireless communication compliant with the IEEE 802.11bn standard. Furthermore, the communication unit 306 may control wireless communication compliant with other IEEE 802.11 standard series in addition to the IEEE 802.11bn standard, and may also control wired communication such as a wired LAN. The communication unit 306 controls the antenna 307 to transmit and receive signals for wireless communication generated by the control unit 302. For example, the communication device communicates data such as image data, document data, and video data with a partner device via the communication unit 306. Note that if the communication device supports the NFC standard or Bluetooth standard in addition to the IEEE 802.11bn standard, the communication unit 306 may also control wireless communication compliant with these communication standards. Furthermore, if the communication device is capable of wireless communication compliant with multiple communication standards, separate communication units and antennas corresponding to those communication standards may be provided.

[0028] The antenna 307 is, for example, an antenna capable of detecting and emitting radio waves in the 2.4 GHz band, the 5 GHz band, and the 6 GHz band. The antenna 307 may be configured to be capable of communication in the same frequency band. In this case, the antenna 307 may be, for example, a multi-band antenna capable of communication in multiple frequency bands. While FIG. 3 illustrates an example in which the communication device has two antennas, one antenna or three or more antennas may be used. If the communication device has multiple antennas, it may have a communication unit 306 corresponding to each antenna. The antenna 307 may be provided separately from the communication unit 306, or may be configured together with the communication unit 306 as a single module.

[0029] FIG. 4 is a block diagram showing an example of the functional configuration of a communication device (AP 101, AP 111, STA 102, and STA 112). The communication device includes, for example, a PCH communication control unit 401, an NPCH communication control unit 402, and a communication control unit 403. These functions may be implemented, for example, by the control unit 302 executing a program stored in the storage unit 301 of the communication device. However, this is just an example, and dedicated hardware may be provided to implement each function. The configuration shown in FIG. 4 is just an example, and the communication device may include configurations other than these. Furthermore, two or more functional blocks in FIG. 4 may be implemented as a single functional block, or one functional block may be divided into two or more functional blocks.

[0030] The PCH communication control unit 401 establishes a single link with the STA that collectively uses one or more channels, including the PCH, to communicate. For example, the PCH communication control unit 401 receives wireless frames from a partner device connected to its own device that has acquired a transmission right on the PCH, or acquires a transmission right on the PCH and transmits wireless frames to the partner device. The NPCH communication control unit 402 communicates using NPCH access when the PCH is being used by another device and cannot be used. That is, the NPCH communication control unit 402 communicates using NPCH access when, for example, it detects that the PCH is being used by an OBSS or when it determines that NPCH access should be performed based on an occupation request frame or occupation response frame (described below). For example, the NPCH communication control unit 402 confirms that the SPCH is idle, acquires a transmission right on the NPCH, and transmits wireless frames using one or more NPCHs, including the SPCH, without using the PCH. In addition, the NPCH communication control unit 402 receives radio frames transmitted by the remote device connected to the host device via NPCH access. The communication control unit 403, for example, controls whether to use the PCH communication control unit 401 or the NPCH communication control unit 402 for communication. The communication control unit 403 determines whether the PCH is occupied by the OBSS, for example, based on an occupancy request frame or an occupancy response frame, and controls communication to be performed using the PCH communication control unit 401 if the PCH is not occupied. In addition, the communication control unit 403, for example, controls communication to be performed using the NPCH communication control unit 402 during a period when the PCH is occupied by the OBSS.

[0031] (Flow of communication processing) Next, an example of the flow of communication processing executed in a wireless communication system will be described with reference to Fig. 5. Note that Fig. 5 assumes that, as in Fig. 1, AP 101 is located in a position where it can receive and decode wireless frames from AP 111, while STA 102 is located in a position where it cannot receive and decode those wireless frames. Also, in Fig. 5, it is assumed that AP 101 and STA 102 use a first channel (CH1) as a PCH, and AP 111 and STA 112 can use CH1 as either a PCH or an NPCH.

[0032] In FIG. 5, it is assumed that AP 101, STA 102, AP 111, and STA 112 are not using CH1 (F501 to F504). Since the PCH is not being used or occupied by the OBSS, AP 101 and STA 102 do not use NPCH access, and when they need to transmit a wireless frame, they acquire access rights on the PCH. When AP 101 and STA 102 acquire access rights on the PCH, they can use the second channel (CH2), which is the NPCH, when that channel is not being used. In FIG. 5, AP 101 and STA 102 are shown to be able to use CH2 in addition to CH1 at the time points F501 and F502.

[0033] In this state, for example, when data to be transmitted by occupying a channel occurs in the STA 112, the STA 112 transmits an occupation request frame (F505). The occupation request frame includes, for example, information identifying one or more channels to be occupied and information indicating the length of time for occupying the channels. Note that the information indicating the length of time for occupying the channels may be information for causing surrounding APs or STAs to set a NAV, similar to conventional Request To Send (RTS) frames or Clear To Send (CTS) frames. Furthermore, the occupation request frame may include a Duration field, similar to RTS frames and CTS frames, and the length of time for occupying the channel may be indicated in the Duration field. Unless otherwise specified, the information indicating the length of time for occupying the channel in the occupation request frame in the following description may also be information for setting a NAV, and the length of time may be indicated by a Duration field in the frame. By transmitting an occupancy request frame on that channel, information identifying the channel to be occupied may be implicitly communicated, or the channel to be occupied may not be explicitly indicated. For example, an occupancy request frame may be transmitted on all channels requesting occupancy, in which case information indicating the channel to be occupied may not be included in the frame. Also, if an occupancy request frame is configured to always be transmitted on a portion of the channels to be occupied, and if there are multiple channels to be occupied, channels excluding the channel on which the frame is transmitted may be indicated as the channels to be occupied. For example, when requesting occupancy of the PCH of an OBSS, an occupancy request frame may be transmitted on the PCH of the OBSS, and the frame may include information indicating information on channels other than the PCH for which occupancy is requested. Also, the frame may include information indicating a list of channels for which occupancy is requested, including the channel on which the occupancy request frame is transmitted.5, STA 112 requests the occupation of CH1 and transmits an occupation request frame on CH1. The occupation request frame does not need to include information about CH1 as information about the channel to be occupied. The channel to be occupied may be indicated by a list of channel numbers or by other information such as a frequency bandwidth.

[0034] Upon receiving this occupancy request frame, AP 111 transmits an occupancy request frame to a communication device (here, AP 101) of the OBSS (here, network 103) as seen from AP 111 (F506). This occupancy request frame may contain the same information as the occupancy target channel and period indicated in the occupancy request frame transmitted by STA 112. Note that this is merely an example; the occupancy request frames F505 and F506 may contain different information on the occupancy target channel and period, such as increasing the occupancy target channel or period if data to be transmitted exists at AP 111. Furthermore, if there is data to be transmitted by occupying a channel, AP 111 may transmit an occupancy request frame spontaneously without receiving an occupancy request frame from STA 112. In this case, the occupancy request frame includes information identifying one or more channels to be occupied, determined based on the size of the data to be transmitted, and information indicating the length of the period for occupying the channel. In addition, AP 111 may transmit an occupancy request frame only when requesting occupancy (use) of a PCH in OBSS (network 103), for example, or may transmit an occupancy request frame regardless of the channel for which occupancy is requested.

[0035] Note that while AP 111 is transmitting an occupancy request frame, CH1 is busy, and AP 101 is therefore unable to use CH1 and CH2. On the other hand, if AP 101 does not detect a signal from STA 112 with sufficient power, it will be able to use CH1 (and CH2) while the occupancy request frame from STA 112 is being transmitted. Also, STA 102 does not detect wireless frames from AP 111 and STA 112 with sufficient power, and will be able to use CH1 (and CH2) while AP 111 and STA 112 are transmitting occupancy request frames.

[0036] When AP 101 receives an occupancy request frame from AP 111 of the OBSS, it determines whether to permit occupancy of CH1 on which the frame was received or the channel specified in the frame. AP 101 then transmits an occupancy response frame including the result of the determination (F507). This occupancy response frame may, for example, be a frame indicating to AP 111 that occupancy of the channel specified in the occupancy request frame has been permitted. Furthermore, the occupancy response frame may be a frame instructing a STA (here, STA 102) belonging to the network 103 established by AP 101 to perform NPCH access. In other words, by receiving the occupancy response frame, AP 111 determines that occupancy of the channel has been permitted, and STA 102 may interpret the same occupancy response frame as an instruction to use NPCH access. The occupancy response frame may, for example, include information indicating the channel for which occupancy is permitted and information indicating the period for which occupancy is permitted. Here, the information indicating the period during which channel occupation is permitted may be information indicating a period during which surrounding APs and STAs are to set a NAV, similar to conventional RTS and CTS frames. Furthermore, the occupation response frame may include a Duration field, similar to RTS and CTS frames, and the Duration field may indicate the length of the period during which channel occupation is permitted. Unless otherwise specified, the information indicating the length of the period during which channel occupation is permitted in the occupation response frame in the following description may also be information for setting a NAV, and the period length may be indicated by the Duration field in the frame. This allows the AP 111 to recognize that it can occupy the specified channel and perform communication within the specified period. Furthermore, the STA 102 can recognize that it should perform NPCH access on an unoccupied channel within the specified period. The AP 101 may also transmit a frame indicating that NPCH access should be used to the STA 102, separate from the occupation response frame to the AP 111.The occupancy response frame may also be a multicast frame that includes a portion storing data for the AP 111 and a portion storing data for the connected STA (here, STA 102). When control is performed using separate wireless frames, detailed information can be provided individually to the STA 102 and the OBSS AP 111. On the other hand, when control is performed using a single wireless frame, the number of control wireless frames transmitted and received can be reduced, thereby improving communication efficiency.

[0037] The information notified from the AP 101 to the STA in the BSS (STA 102 in this case) may include, for example, information indicating the SPCH. However, if the SPCH has been determined in advance between the AP 101 and the STA 102 and that channel is not occupied, the information indicating the SPCH need not be included. This information may also instruct the STA to prohibit transmission of radio frames on any channel. For example, if the channels to be occupied by the OBSS include all channels available in the BSS 103, the prohibition of radio frame transmission may be instructed. Furthermore, the information notified from the AP 101 to the STA in the BSS (STA 102 in this case) may include information indicating the length of the period during which NPCH access should be performed or the length of the period during which radio frame transmission is prohibited. By specifying this period, it is not necessary to transmit a notification for terminating NPCH access or lifting the prohibition of radio frame transmission, thereby suppressing a decrease in communication efficiency due to an increase in control communication. The period length specified here may be, for example, equal to the period length for which the OBSS AP requested channel occupancy in F506, but is not limited to this. For example, the STA may be notified of a period length obtained by adding the period length for which an occupancy response frame is transmitted from the AP 111 to the STA 112, as described below, and a certain period length such as a SIFS (Short IFS). Furthermore, the period length for which occupancy is permitted notified to the OBSS AP and the period length for which NPCH access should be performed or wireless frame transmission is prohibited notified to the STA in the BSS may be the same or different. For example, different periods of different lengths may be set taking into account propagation delay, processing time, etc.

[0038] When STA 102 receives this frame from AP 101, it performs control to transition to a state in which it does not transmit wireless frames on the PCH but performs NPCH access to transmit wireless frames using the NPCH (F508, F509). After transitioning to this state, if, for example, the SPCH is designated as CH2, STA 102 confirms that CH2 is idle and can transmit data using one or more NPCHs including CH2. After that, when the period designated in the exclusive use response frame of F507 has elapsed, STA 102 performs control to return to a state in which it communicates using the PCH (F510). Similarly, after transmitting the exclusive use response frame (F507), AP 101 also performs control to transition to a state in which it does not transmit wireless frames on the PCH but performs NPCH access to transmit wireless frames using the NPCH (F511, F512). Then, after the period specified in the occupancy response frame of F507 has elapsed, the AP 101 performs control so as to return to a state in which communication is performed using the PCH again (F513).

[0039] Meanwhile, when the AP 111 receives the permission for occupancy of CH1 in the occupancy response frame transmitted from the AP 101 in F507, the AP 111 transmits an occupancy response frame indicating that occupancy of CH1 has been permitted to the STA 112 (F514). This places CH1 in an occupied state in the network 113, and the AP 111 and the STA 112 use CH1 to perform data communication during the period in which CH1 is occupied (F515, F516). After the occupancy period of CH1 has elapsed, the AP 111 and the STA 112 transition to a state in which CH1 is not occupied. In this state, the AP 111 and the STA 112 do not occupy CH1, but can transmit wireless frames when CH1 is idle (F517, F518). As an example, an RTS frame may be used as the occupancy request frame transmitted from the STA 112 to the AP 111 in F505. For example, the STA 112 transmits RTS frames on all of the channels for which occupancy is requested. The AP 111 may then identify the channel on which the RTS frame was received from the STA 112, include information indicating the identified channel in an occupancy request frame as information indicating the channel for which occupancy is requested, and transmit the frame to the AP 101. Then, in response to permission for occupancy of the channel, the AP 111 transmits a CTS frame on each of the channels for which occupancy is permitted. This allows the STA 112 to adjust the channels in use between BSSs while maintaining the conventional configuration. Note that the RTS frame may include a list of channels for which occupancy is requested, and the CTS frame may include a list of channels for which occupancy is permitted, so that these frames are transmitted and received on a single channel.

[0040] (Flow of Processing Executed by AP) Next, the operation of the AP (AP 101 and AP 111) will be described with reference to FIGS. 6A, 6B, 7A, 7B, 8A, 8B, and 9. This processing may be implemented, for example, by the control unit 302 executing a program stored in the storage unit 301, or may be implemented as a processing function within the communication unit 306. The AP may start this processing in response to the activation of the wireless LAN function, such as by turning on the power. The AP first sets the operating channels (PCH and one or more NPCHs) (S601). This setting may be performed, for example, by user input, or may be performed automatically in response to information such as the congestion status of multiple channels available to the AP. After this, communication will be performed on the set PCH and one or more NPCHs in the network established by the AP.

[0041] The AP waits to receive a wireless frame on one or more channels including the PCH (S602). Here, if the AP is not using NPCH access, when it receives a signal from a STA in its own BSS, it will always receive a wireless frame using a channel including the PCH. On the other hand, in an OBSS, a channel other than the PCH set in S601 can be used as the PCH. Therefore, the wireless frame received by the AP on a channel not including the PCH will be a wireless frame from the OBSS. In this case, if an occupancy request frame is transmitted in parallel on all channels requested for occupancy, and if the frame is received on a channel not including the PCH, even if the channel is occupied, it will be a channel other than the PCH. In other words, if the occupancy request frame is transmitted on all channels eligible for occupancy, the AP can determine that the wireless frame received on a channel not including the PCH is not addressed to the AP and that the PCH will not be occupied. Therefore, if the AP receives a wireless frame on a channel not including the PCH (NO in S602), it does not perform any reception-related processing and proceeds to S608. In addition, when an occupancy request frame requesting occupancy of multiple channels is transmitted on one channel, the AP may decode the frame taking into consideration cases in which occupancy of the PCH is requested on a channel other than the PCH. If the AP determines that occupancy of the PCH is not requested in the frame, it may operate to proceed to S608. For example, even if the PCH in the own BSS (network 113) is CH2, if the PCH in the OBSS (network 103) is CH1 and occupancy of CH1 is requested, the AP 111 may transmit the occupancy request frame on CH1. In other words, the occupancy request frame may be transmitted on the PCH of the network receiving the occupancy request. In this case, when occupancy of the PCH is requested, the AP 101 will always receive the occupancy request frame on the PCH.Therefore, during periods when the AP is not accessing the NPCH, the AP can ignore radio frames received on channels that do not include the PCH, since these frames do not request PCH occupancy.

[0042] When the AP receives a wireless frame on one or more channels including the PCH (YES in S602), it determines whether the frame is an exclusive use request frame from a STA in its own BSS (S603). When the AP receives an exclusive use request frame from a STA in its own BSS (YES in S603), it proceeds to S604. The process of S604 is, for example, the process performed when the AP 111 receives an exclusive use request frame at F505 in FIG. 5 . Details of this process will be described later. When the received frame is not an exclusive use request frame from a STA in its own BSS (NO in S603), the AP determines whether the frame is an exclusive use request frame from an AP in the OBSS (S604). When the AP receives an exclusive use request frame from an AP in the OBSS (YES in S604), it proceeds to S606. The process of S606 is, for example, the process performed when the AP 101 receives an exclusive use request frame from the AP 111 at F506 in FIG. Details of this process will also be described later. If the received frame is not an occupancy request frame from an AP of the OBSS (NO in S604), the AP executes processing according to the frame (S607). This processing is processing for frames related to conventional communications, such as normal data or control frames, and is not related to this embodiment, so it will not be described in detail.

[0043] The processing of S604 will now be described with reference to FIGS. 7A and 7B. When an AP receives an occupancy request frame from a STA of its own BSS (YES in S603), it determines whether to permit channel occupancy (S701). For example, the AP may determine whether to permit channel occupancy based on the congestion status of its own BSS and characteristics such as the allowable delay and throughput of the traffic to be transmitted. When the AP determines not to permit channel occupancy (NO in S701), it transmits an occupancy response frame indicating a denial of channel occupancy to the STA that transmitted the occupancy request frame (S709), and terminates the processing. Note that the AP does not need to respond if it determines not to permit channel occupancy. In this case, if the STA does not receive a response within a predetermined period, it may determine that occupancy has not been permitted. On the other hand, when the AP determines to permit channel occupancy (YES in S701), it determines whether the channel requested for occupancy includes the PCH of the OBSS (S702). If the channels for which occupancy is requested include the PCH of the OBSS (YES in S702), the AP transmits an occupancy request frame to the AP of the OBSS (S703). For example, the AP may transmit the occupancy request frame on all channels for which occupancy is requested, or may transmit the occupancy request frame only on the PCH of the OBSS. In one example, the AP may identify the PCH of the OBSS by decoding a wireless frame (e.g., a beacon frame) from the AP of the OBSS. Alternatively, the AP may obtain information about the PCH of the OBSS by communicating with the AP of the OBSS in advance (wired or wirelessly). Note that if the AP of the OBSS is configured to decode wireless frames on channels other than the PCH of the OBSS, the AP may transmit the occupancy request frame on at least one of the channels available in the OBSS.

[0044] After transmitting the channel occupancy request, the AP waits to receive an occupancy response frame from an AP in the OBSS (S704). If the AP receives an occupancy response frame indicating a denial of channel occupancy, or if the AP does not receive a channel occupancy response frame within a predetermined period (NO in S704), the AP determines that channel occupancy is not permitted. The AP then transmits an occupancy response frame indicating a denial of channel occupancy to the STA that transmitted the occupancy request frame received in S603 (S709), and terminates processing. On the other hand, if the AP receives an occupancy response frame indicating a permission for channel occupancy (YES in S704), the AP transmits an occupancy response frame indicating a permission for channel occupancy to the STA that transmitted the occupancy request frame received in S603 (S705). The AP then waits to receive a frame from the STA using the channel for which occupancy has been permitted (S706), and if a frame is received (YES in S706), it executes processing according to the frame (S707). The AP continues frame reception processing (S706, S707) until the channel occupation period expires (NO in S708), and ends the processing when the occupation period expires (YES in S708). After the processing in Figures 7A and 7B is completed, the processing proceeds to S608 in Figure 6B.

[0045] Next, the processing of S606 will be described with reference to Figures 8A and 8B. When an AP receives an occupation request frame from an AP of an OBSS (YES in S605), the AP determines whether to permit channel occupation (S801). For example, the AP may determine whether to permit channel occupation based on the congestion status of its own BSS and characteristics such as the allowable delay and throughput of the traffic to be transmitted. When the AP determines not to permit channel occupation (NO in S801), it transmits an occupation response frame indicating a denial of channel occupation to the AP of the OBSS that transmitted the occupation request frame (S810), and terminates the processing. In this case, the AP may transmit a notification to the STA of its own BSS indicating that NPCH access should not be used or that wireless frame transmission is not prohibited, separate from the occupation response frame, but it may not transmit such a notification. In other words, if the STA interprets the occupation response frame as an instruction to use NPCH access or as an instruction to prohibit wireless frame transmission regardless of its content, such a separate notification may be transmitted from the AP to the STA. On the other hand, if the STA checks the content of the exclusive use response frame and decides to perform control, such a notification does not need to be transmitted. Also, if it is determined that NPCH access should be used or that transmission of radio frames is prohibited and the determination result is notified to the STA separately from the exclusive use response frame, the absence of such notification may result in the STA being notified that NPCH access should be used.

[0046] If the AP determines to permit channel occupation (YES in S801), it determines whether the channels requested for occupation include all channels available in the own BSS (S802). That is, the AP determines whether there are any channels that can be used without being occupied. If there are any channels that are not requested for occupation, the AP transmits a radio frame to the STAs in the own BSS instructing them to transition to a state in which NPCH access should be performed (S803). The AP also transmits an occupation response frame indicating that channel occupation is permitted to the AP of the OBSS that transmitted the occupation request frame (S803). Note that information instructing the STAs in the own BSS to transition to a state in which NPCH access should be performed can be included in the occupation response frame, but this information may also be transmitted in a separate radio frame. Note that the information instructing the STAs in the own BSS to transition to a state in which NPCH access should be performed includes information indicating an SPCH selected from unoccupied channels. This information also includes information indicating the duration of the state in which NPCH access should be performed. This duration corresponds to the time that the OBSS occupies the PCH of its own BSS, but may be set to a time longer or shorter than that occupancy time.

[0047] Thereafter, communication using NPCH access is performed until the channel occupation period of the OBSS expires (NO in S809). That is, the AP waits for a frame on the NPCH including the SPCH (S804). Then, when the AP receives a frame on the NPCH including the SPCH (YES in S804), it executes processing according to the received frame (S805) and proceeds to S806. If the AP does not receive a frame on the NPCH including the SPCH (NO in S804), it skips the processing of S805 and proceeds to S806. In S806, the AP determines whether a frame to be transmitted has occurred. Then, when a frame to be transmitted has occurred (YES in S806), the AP detects that the SPCH is in an idle state (YES in S807) and then transmits the frame to be transmitted on the NPCH including the SPCH (S808). On the other hand, if there is no frame to be transmitted (NO in S806) or the SPCH is not in an idle state (NO in S807), the process of S808 is not performed, and if the OBSS channel occupation period has not yet expired (NO in S809), the process returns to S804. Note that although Figures 8A and 8B show an example in which the transmission process is performed after the reception process, the order may be reversed. If the OBSS channel occupation period then expires (YES in S809), the processes of Figures 8A and 8B end.

[0048] Returning to S802, if there is no channel for which occupancy has not been requested (NO in S802), the AP transmits an occupancy response frame to the AP of the OBSS indicating permission to occupy the channel (S811). The AP also transmits information to the STAs of its own BSS instructing them to prohibit wireless frame transmission (S811). Note that the information instructing the STAs of its own BSS to prohibit wireless frame transmission may be included in the occupancy response frame, but the information may also be transmitted in a separate wireless frame. The AP then waits without communicating until the channel occupancy period of the OBSS expires (S812), and terminates the process upon expiration of the occupancy period (YES in S812). After the processes of FIGS. 8A and 8B are completed, the process proceeds to S608 of FIG. 6B.

[0049] 6A and 6B , the AP determines whether a frame to be transmitted (apart from a frame to be transmitted generated during processing due to a wireless frame transmitted from a STA in its own BSS or an AP in the OBSS) has occurred (S608). If no such frame to be transmitted exists (NO in S608), the AP returns to S602 and repeats the processes in FIGS. 6A and 6B unless the wireless LAN function is disabled (NO in S613). On the other hand, if a frame to be transmitted exists (YES in S608), the AP determines whether a channel should be occupied to transmit the frame (S609). The AP makes this determination based on, for example, the allowable delay and required throughput of the frame to be transmitted. In one example, the AP determines that channel occupation is necessary if the allowable delay is equal to or less than a predetermined time or if the required throughput exceeds a predetermined value. If the AP determines that channel occupancy is not necessary (NO in S609), it confirms that the PCH is idle (YES in S611) and transmits the frame to be transmitted using an idle channel including the PCH (S612). On the other hand, if the AP cannot confirm that the PCH is idle (NO in S611), it does not transmit the frame to be transmitted. Then, unless the wireless LAN function is disabled (NO in S613), the AP returns to S602 and repeats the processes of Figures 6A and 6B. If the AP determines that channel occupancy is necessary (YES in S609), it subsequently executes the process of S610.

[0050] The process of S610 will now be described with reference to FIG. 9 . This process corresponds to, for example, the process in FIG. 5 when the AP 111 determines that a transmission target frame has occurred in its own device and transmits an occupancy request frame F506 without receiving an occupancy request frame F505 from the STA 112. The AP transmits an occupancy request frame to the AP of the OBSS to occupy the channel (S901). Note that if the AP does not request occupancy of the PCH of the OBSS, it may occupy the channel using the RTS / CTS mechanism instead of transmitting an occupancy request frame. After transmitting the occupancy request frame, the AP determines whether it has received an occupancy response frame indicating permission to occupy the channel from the AP of the OBSS (S902). If the AP receives an occupancy response frame indicating a denial of channel occupancy, or if it does not receive an occupancy response frame within a predetermined period (NO in S902), it determines that the channel cannot be occupied and terminates the process without transmitting a wireless frame. On the other hand, if the AP receives an occupation response frame from the AP of the OBSS indicating permission to occupy the channel (YES in S902), it transmits the occupation response frame indicating permission to occupy the channel to the STA of its own BSS (S903). Note that the occupation response frame of S903 may be a frame in a format other than an occupation response frame, as long as it contains information indicating that the channel is occupied by the AP to transmit wireless frames and that the STA is prohibited from transmitting wireless frames during the occupation period. After transmitting the occupation response frame, the AP transmits the wireless frame to be transmitted on the channel whose occupation has been permitted until the channel occupation period expires (while NO in S905) (S904). After the channel occupation period expires (YES in S905), the AP returns the process to S613 of FIG. 6B.

[0051] (Flow of Processing Executed by STA) Next, the operation of the STA (STA102 and STA112) will be described with reference to FIGS. 10A , 10B , 10C , 11 , 12 , and 13 . This processing may be implemented, for example, by the control unit 302 executing a program stored in the storage unit 301, or may be implemented as a processing function within the communication unit 306. The STA may start this processing in response to the activation of the wireless LAN function, such as by being powered on. The STA first sets an operating channel (PCH and one or more NPCHs) (S1001). This setting may be determined, for example, based on the results of an AP search. This setting may also be performed by user input. In one example, the STA searches for APs, and the user selects which AP to connect to from the APs discovered by the search, thereby determining to use the operating channel set by the AP. Alternatively, the STA may notify the AP of the operating channel designated by the user selection accepted by the STA, and the AP may configure the STA to use the operating channel. After this, the STA will communicate in the participating network on the configured PCH and one or more NPCHs.

[0052] The STA waits to receive a wireless frame on one or more channels including the PCH (S1002). If the STA does not receive a wireless frame on a channel including the PCH (NO in S1002), the STA proceeds to S1010. Note that the STA may also proceed to S1010 if it receives a wireless frame from an AP or STA of the OBSS on a channel including the PCH. On the other hand, if the STA receives a wireless frame (from the AP of its own BSS) on a channel including the PCH (YES in S1002), it switches the processing to be performed depending on the type of the frame. That is, if the STA determines that the received frame is an occupancy response frame indicating permission to occupy the channel from the AP of its own BSS (YES in S1003), the STA performs the processing of S1004. The processing of S1004 will be described later. On the other hand, if the STA determines that the received frame is an exclusive response frame instructing a transition to a state in which NPCH access from the AP of the own BSS should be performed (NO in S1003, YES in S1005), it executes the process of S1006. The process of S1006 will also be described later. Furthermore, if the STA determines that the received frame is an exclusive response frame indicating prohibition of transmission from the AP of the own BSS (NO in S1003, NO in S1005, YES in S1007), it waits until the channel occupation period of the OBSS expires (S1008). Then, when the channel occupation period of the OBSS expires (YES in S1008), the STA proceeds to S1010. Furthermore, if the STA determines that the received frame is another type of frame (NO in S1003, NO in S1005, NO in S1007), it executes processing according to the frame (S1009) and proceeds to S1010. This processing is processing for frames related to conventional communications, such as normal data and control frames, and is not related to this embodiment, so it will not be described in detail.

[0053] The processing of S1004 will now be described with reference to FIG. 11. This processing corresponds to the processing performed when the STA 112 in FIG. 5 receives an occupancy response frame F514 without transmitting an occupancy request frame F505. That is, the processing of FIG. 11 is performed when a frame to be transmitted exists in the AP of the own BSS and the AP is granted channel occupancy to transmit that frame. When the STA receives an occupancy response frame indicating permission for channel occupancy from the AP of the own BSS (YES in S1003), the STA waits for a frame from the AP of the own BSS to arrive on the occupied channel (S1101). When the STA receives the frame (YES in S1101), the STA executes processing according to the received frame (S1102). The STA repeats the processing of S1101 and S1102 until the channel occupancy period expires (S1103). The STA, rather than the AP, may transmit an acknowledgment (ACK), data, or the like during the channel occupancy period. When the channel occupation period expires (YES in S1103), the STA ends the processing in FIG. 11 and proceeds to S1010 in FIGS. 10A to 10C.

[0054] Next, the processing of S1006 will be described with reference to FIG. 12. This processing corresponds to the processing performed when STA 102 in FIG. 5 receives the occupancy response frame F507. The STA waits for a frame to arrive on one or more NPCHs, including the SPCH (S1201). When the STA receives a frame (YES in S1201), it executes processing corresponding to the frame (S1202). The STA also determines whether a frame to be transmitted exists (S1203). If a frame to be transmitted exists (YES in S1203), the STA confirms that the SPCH is in an idle state (YES in S1204) and transmits the frame on one or more NPCHs, including the SPCH (S1205). While FIG. 12 illustrates an example in which the transmission processing is performed after the reception processing, this order may be reversed. That is, the STA may perform the processes in any order as long as it performs the reception processes of S1201 and S1202 when a frame is received, and performs the transmission processes of S1203 to S1205 when a frame to be transmitted exists. The STA repeats the above-described reception and transmission processes until the channel occupation period of the OBSS indicated in the occupancy response frame expires (while NO is returned in S1206). Then, when the channel occupation period of the OBSS expires (YES in S1206), the STA ends the process of FIG. 12 and proceeds to S1010 in FIG. 10C.

[0055] Returning to FIGS. 10A to 10C, in S1010, the STA determines whether there is a frame to be transmitted. If there is no frame to be transmitted (NO in S1010), the STA returns to S1002 and repeats the processes of FIGS. 10A to 10C unless the wireless LAN function is disabled (NO in S1015). On the other hand, if there is a frame to be transmitted (YES in S1010), the STA determines whether a channel should be occupied to transmit the frame (S1011). The STA makes this determination based on, for example, the allowable delay and required throughput of the frame to be transmitted. For example, the STA determines that channel occupation is necessary if the allowable delay is equal to or less than a predetermined time or if the required throughput exceeds a predetermined value. If the STA determines that channel occupation is not necessary (NO in S1011), the STA confirms that the PCH is idle (YES in S1013) and transmits the frame to be transmitted using an idle channel including the PCH (S1014). On the other hand, if the STA cannot confirm that the PCH is in an idle state (NO in S1013), it does not transmit the frame to be transmitted. The STA then returns to S1002 and repeats the processes of Figures 10A to 10C unless the wireless LAN function is disabled (NO in S1015). If the STA determines that channel occupation is necessary (YES in S1011), it then executes the process of S1012.

[0056] The process of S1012 will now be described with reference to FIG. 13. This process corresponds to the process in FIG. 5 when, for example, the STA 112 determines that a frame to be transmitted has occurred in its own device and transmits an exclusive use request frame F505. When a frame to be transmitted that requires channel occupancy occurs, the STA transmits the exclusive use request frame to the AP of its own BSS (S1301). Then, when the STA receives an exclusive use response frame indicating permission to occupy the channel from the AP of its own BSS (YES in S1302), it transmits a wireless frame using the occupied channel (S1303). This wireless frame transmission is performed during the exclusive use period indicated by the exclusive use response frame (NO in S1304). Note that the AP may transmit data or an ACK during this exclusive use period. After the exclusive use period expires (YES in S1304), the STA returns to S1015 of FIG. 10C.

[0057] In this embodiment, APs each forming a separate BSS transmit and receive frames requesting channel occupancy and granting or denying the request, and each AP forwards the contents of the frame to its subordinate STAs. This allows APs and STAs belonging to multiple BSSs to recognize whether the PCH is occupied due to communication by another BSS. As a result, each BSS can share a common understanding of whether the PCH can be used and whether NPCH access should be used, enabling efficient communication. Furthermore, negotiations regarding channel occupancy between BSSs allow appropriate adjustments for channel occupancy according to the situation in each BSS.

[0058] In the above-described embodiment, an example in which permission or denial of channel occupation is indicated has been described. However, when occupancy of multiple channels is requested, some of the channels may be permitted and the remaining channels may be denied. For example, when an occupancy request frame is transmitted for each of multiple channels for which occupancy is requested, an occupancy response frame indicating permission or denial of occupancy may be transmitted for each of the channels, thereby permitting occupancy of only some of the channels. Furthermore, when an occupancy request frame is transmitted for only some of the channels for which occupancy is requested (e.g., the PCH of an OBSS), information indicating at least one of the channels for which occupancy is permitted and the channels for which occupancy is denied may be included in the occupancy response frame and transmitted. Note that the occupancy request frame may also indicate information indicating the minimum number of channels (or bandwidth). In this case, if occupancy of the minimum number of channels (or bandwidth) is not permitted, occupancy may be denied for all channels. Note that when occupancy of a channel is denied, the AP and STA may operate so as not to communicate on that channel, or may perform contention-based channel access on that channel. That is, if the AP and STA are denied channel occupancy, they may not occupy the channel, but may access the channel by conventional Carrier Sense Multiple Access (CSMA) to communicate.

[0059] (Variation) In the above embodiment, an AP requests channel occupancy and can occupy the channel if the AP in the OBSS grants permission to do so. However, this is not limiting. For example, an AP may "declare" channel occupancy using an occupancy request frame and occupy the channel to perform communication without receiving a response from the AP in the OBSS. An example of the communication flow in this case is shown in FIG. 14. Note that the term "occupancy request frame" is used in the following description, but it may also be interpreted as "occupancy declaration frame." For example, when the AP 111 receives an occupancy request frame from the STA 112 (F505), the AP 111 transmits an occupancy response frame (F1401). Furthermore, the AP 111 transmits an occupancy request frame when a frame to be transmitted is generated in the AP 111 (F1401). Hereinafter, the occupancy request frame and the occupancy response frame may be collectively referred to as an "occupancy request / response frame." This occupancy request / response frame is received not only by the AP 101 in the OBSS but also by the STA 112 in its own BSS. This occupancy request / response frame declares that the designated channel will be occupied after a predetermined time has elapsed since its transmission. This predetermined time may correspond, for example, to the time it waits for a frame for occupying a channel in a BSS to be transmitted and received in an OBSS. That is, it may be the time it waits for the AP 101 to instruct the STA 102 to use NPCH access or to prohibit frame transmission. The predetermined time may be, for example, the length of the wireless frame in which the AP 101 transmits the instruction to the STA 102 plus a predetermined IFS. After a predetermined time has elapsed since the transmission or reception of the occupancy request / response frame, the AP 111 and the STA 112 perform data communication using the declared occupancy channel (F1403, F1404). Note that the AP 101 does not have to respond when receiving this occupancy request / response frame, but may instead transmit an occupancy response frame (F1402), as in the case of FIG. 5 . The occupancy response frame here can be transmitted to instruct the STA 102 to use NPCH access or to prohibit transmission. Since it is sufficient for the AP 101 to be able to issue this instruction, the AP 101 may transmit this instruction in a format other than a "response."On the other hand, when the AP 111 and the STA 112 receive this occupancy response frame, they can occupy the channel and perform communication immediately after receiving the frame.

[0060] An example of the processing flow of the AP in this case will be described using Figures 15A, 15B, 16A, 16B, 17A, 17B, and 18. Note that in Figures 15A, 15B, 16A, 16B, 17A, 17B, and 18, the same processes as those in Figures 6A, 6B, 7A, 7B, 8A, 8B, and 9 are designated with the same reference numerals, and detailed descriptions thereof will be omitted. The processing in Figures 15A and 15B differs from the processing in Figures 6A and 6B in the processing when an exclusive use request frame is received from a STA in the own BSS (S1501), the processing when an exclusive use request / response frame is received from an AP in the OBSS (S1503), and the processing for channel occupancy (S1504). Note that there is also a formal difference (S1502) due to the fact that not only an exclusive use request frame but also an exclusive use response frame is received from the AP in the OBSS.

[0061] 16A and 16B show the processing flow of S1501. When an AP receives an occupation request frame from a STA in its own BSS requesting occupation of the PCH of the OBSS (YES in S702), it transmits an occupation response frame to the STA in its own BSS and the AP in the OBSS (S1601). This occupation response frame contains information similar to the occupation request frame transmitted by the AP 111 in the above example, except that it is a declaration of channel occupation rather than a request for channel occupation. That is, information indicating the channel to be occupied and the period of occupation is included in the occupation response frame. Note that a frame in the form of an occupation request frame may be transmitted instead of an occupation response frame. Thereafter, when the AP receives a response frame from the AP in the OBSS or when a predetermined time has elapsed (YES in S1602), it recognizes that the channel is occupied and uses that channel to receive wireless frames from the STA in its own BSS. The other processing is the same as in FIGS. 7A and 7B.

[0062] 17A and 17B show the flow of the process of S1503. In this modification, when an AP receives an occupancy request frame from an AP in the OBSS, the AP does not reject the frame. Therefore, steps S801 and S810 of the process of FIGS. 8A and 8B are omitted. The other processes are the same as those of FIGS. 8A and 8B.

[0063] FIG. 18 shows the processing flow of S1504. When an AP transmits data generated in its own device while the PCH is available, it transmits an exclusive use request frame not only to APs in the OBSS but also to STAs in its own BSS (S1801). Note that the AP may transmit an exclusive use response frame if, for example, an exclusive use request frame is received from a STA in its own BSS when transmitting data generated in its own device in S1801 due to the occurrence of data to be transmitted. Then, when a predetermined time has elapsed since transmitting the exclusive use request frame (YES in S1802), the AP transmits a wireless frame on the channel for which it has declared exclusive use. Furthermore, when the AP receives an exclusive use response frame from an AP in the OBSS, it may transmit a wireless frame even before the predetermined time has elapsed. Note that in this modification, the AP may transmit a wireless frame assuming that the channel is occupied, regardless of the content of the exclusive use response frame. Other processing is the same as in FIG. 9.

[0064] Next, an example of the processing flow of an STA will be described using Figures 19A, 19B, 19C, 20, and 21. The processing of Figures 19A to 19C is similar to the processing of Figures 10A to 10C, except for the processing when an AP transmits a wireless frame requiring channel occupancy (S1902) and the processing when a STA generates transmission data requiring channel occupancy (S1903). Note that there is a formal difference (S1901) in that an occupancy request frame is received instead of an occupancy response frame when transmission data exists at an AP in a BSS. Figure 20 shows an example of the processing flow of S1902. When an STA receives an occupancy request frame for transmitting a wireless frame requiring channel occupancy at the AP (YES in S1901), the STA waits for a predetermined time from the reception of the occupancy request frame (S2001). After the predetermined time has elapsed (YES in S2001), the STA performs wireless frame reception processing in the same manner as in Figure 11. Note that, if a STA receives an exclusive use response frame from an AP of the OBSS, it may execute wireless frame reception processing in the same manner as in FIG. 11 even before the predetermined time has elapsed. FIG. 21 shows an example of the processing flow of S1903. When transmission data requiring channel occupancy occurs, the STA transmits an exclusive use request frame to the AP of its own BSS (S1301) and waits for an exclusive use response frame (S2101). If the STA does not receive an exclusive use response frame (NO in S2101), it determines that it cannot occupy the channel and terminates the processing without transmitting the transmission target frame (returning to the processing in FIGS. 19A to 19C and repeating the series of processes). On the other hand, if the STA receives an exclusive use response frame from the AP of its own BSS (YES in S2101), it waits for the reception of an exclusive use response frame from the AP of the OBSS or for the predetermined time to elapse (S2102). Then, upon receiving an occupancy response frame from the AP of the OBSS, or upon the passage of a predetermined time (YES in S2102), the STA executes a process of transmitting the frame to be transmitted using the channel declared as occupied by the AP.

[0065] In this way, when a frame declaring occupancy is used, for example, after an AP transmits an occupancy request frame, it is not necessary to receive permission from the AP of the OBSS and then notify the STA of the permission. This reduces the time during which data cannot be transmitted or received between the AP and the STA, and enables communication using frequency resources more efficiently.

[0066] Note that the above-mentioned occupancy request frame and occupancy response frame are terms used to describe the properties of the frames, and the names of the frames may naturally be changed. Furthermore, in the above-mentioned embodiment, an example was described in which the roles of the AP and the STA were clearly distinguished, but this distinction between these devices does not necessarily have to be made. That is, the processing described as being performed by the AP may be performed by the STA, and the processing described as being performed by the STA may be performed by the AP. Furthermore, the above-mentioned embodiments may be used in any combination, and some processing may not be performed as long as it does not deviate from the spirit of the invention.

[0067] The present invention can also be realized by supplying a program that realizes one or more of the functions of the above-described embodiments to a system or device via a network or a storage medium, and having one or more processors in the computer of the system or device read and execute the program.The present invention can also be realized by a circuit (e.g., an ASIC) that realizes one or more of the functions.

[0068] The invention is not limited to the above-described embodiments, and various changes and modifications can be made 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.

[0069] This application claims priority based on Japanese Patent Application No. 2023-185794, filed on October 30, 2023, the entire contents of which are incorporated herein by reference.

Claims

1. An access point device that performs communication in accordance with the IEEE 802.11 standard series, comprising: a communication means for communicating with other communication devices that belong to a first network established by the access point device, using either a first channel access method that uses at least a specified primary channel in one link, or a second channel access method that does not use the primary channel and uses a non-primary channel different from the primary channel among multiple channels included in the link; wherein the communication means receives wireless frames regarding the occupancy of one or more channels including the primary channel from other access point devices that establish a second network different from the first network, and when one or more channels including the primary channel are occupied in the second network, transmits a notification to the other communication devices instructing them to use the second channel access method or to prohibit transmission of wireless frames.

2. The access point device of claim 1, wherein the first channel access method is a primary channel access method for accessing the access point device based on a result of carrier sense for the primary channel, and the second channel access method is a non-primary channel access method for accessing the access point device based on a result of carrier sense for the non-primary channel.

3. The access point device according to claim 1, wherein the primary channel is a primary channel defined based on one standard in the IEEE 802.11 series of standards, and the non-primary channel is a non-primary channel defined based on at least one standard in the IEEE 802.11 series of standards.

4. An access point device as claimed in any one of claims 1 to 3, wherein the wireless frame relating to the occupancy of one or more channels including the Primary channel is a wireless frame requesting the occupancy of one or more channels including the Primary channel, and the access point device further has a determination means for determining whether or not to permit the occupancy of one or more channels including the Primary channel when the wireless frame requesting the occupancy of one or more channels including the Primary channel is received from the other access point device, and the communication means transmits a response to the other access point device indicating that the request is permitted when the occupancy of one or more channels including the Primary channel is permitted, and transmits a notification to the other communication device instructing that the second channel access method should be used or instructing the prohibition of transmission of wireless frames.

5. The access point device according to claim 4, wherein the notification is included in the response.

6. The access point device according to claim 4 or 5, wherein the response includes information indicating a period during which occupation of one or more channels including the primary channel is permitted.

7. An access point device as claimed in any one of claims 4 to 6, wherein the communication means transmits a response to the other access point device indicating rejection of the request when occupancy of one or more channels including the primary channel is not permitted, and does not transmit the notification to the other communication device.

8. The access point device of claim 1, wherein the radio frame regarding occupancy of one or more channels including the primary channel is a radio frame that declares occupancy of one or more channels including the primary channel, and when the radio frame is transmitted from the other access point device, one or more channels including the primary channel are occupied in the second network.

9. An access point device as claimed in any one of claims 1 to 8, wherein the communication means transmits the notification to the other communication device instructing it to prohibit transmission of wireless frames when all of the channels available for communication between the access point device and the other communication device are occupied by the other access point device.

10. An access point device according to any one of claims 1 to 9, wherein the notification includes information indicating a period during which the second channel access method should be used or a period during which transmission of the wireless frames is prohibited.

11. An access point device as described in any one of claims 1 to 10, wherein the notification includes information specifying a channel among the non-primary channels to be used to acquire transmission rights in the second channel access method when instructing the other communication device to use the second channel access method.

12. A communications device that performs communications in accordance with the IEEE 802.11 standard series, comprising: a communications means for communicating with a first access point device in a first network using either a first channel access method that uses at least a specified primary channel in one link, or a second channel access method that does not use the primary channel and uses a non-primary channel different from the primary channel among multiple channels included in the link; wherein the communications means uses the second channel access method when it receives information instructing the use of the second channel access method in a response transmitted by the first access point device in response to a wireless frame regarding the occupancy of one or more channels including the primary channel transmitted by a second access point device that constructs a second network different from the first network, or does not transmit a wireless frame when it receives information instructing the prohibition of transmission of a wireless frame in the response.

13. The communication device according to claim 12, wherein the response includes information indicating a period during which the second channel access method should be used or a period during which transmission of the radio frames is prohibited.

14. An access point device that performs communication in accordance with the IEEE 802.11 standard series, comprising a communication means for constructing a first network and communicating with a first other communication device participating in the first network, the communication means transmitting a wireless frame regarding the occupancy of one or more channels including the primary channel to another access point device that constructs a second network in which communication is performed using either a first channel access method using a predetermined primary channel in one link or a second channel access method not using the primary channel and using a non-primary channel different from the primary channel among a plurality of channels included in the link, the communication means communicating with the first other communication device using one or more channels including the primary channel based on the transmission of the wireless frame, The wireless frame is a wireless frame that, when the other access point device receives the wireless frame and one or more channels including the primary channel are occupied in the first network, causes the other access point device to transmit an instruction to a second other communication device participating in the second network to use the second channel access method or an instruction to prohibit transmission of a wireless frame.

15. The access point device according to claim 14, wherein the radio frame regarding occupancy of one or more channels including the Primary channel is a radio frame requesting occupancy of one or more channels including the Primary channel, and when the communication means receives a response from the other access point device indicating permission for occupancy of one or more channels including the Primary channel, the communication means communicates with the first other communication device using one or more channels including the Primary channel.

16. The access point device according to claim 15, wherein the response includes information indicating a period during which occupation of one or more channels including the primary channel is permitted.

17. An access point device as described in claim 15 or 16, wherein when the communication means receives a response from the other access point device indicating that occupation of one or more channels including the primary channel is permitted, the communication means transmits information indicating that occupation of one or more channels including the primary channel is permitted to the first other communication device.

18. An access point device as described in any one of claims 15 to 17, wherein the communication means does not communicate with the first other communication device using one or more channels including the primary channel when it receives a response from the other access point device indicating that occupancy of one or more channels including the primary channel is not permitted.

19. An access point device according to any one of claims 15 to 17, wherein the communication means performs contention-based channel access with the first other communication device on one or more channels including the primary channel when a response indicating that occupation of one or more channels including the primary channel is not permitted is received from the other access point device.

20. The access point device of claim 14, wherein the radio frame regarding occupancy of one or more channels including the Primary channel is a radio frame declaring occupancy of one or more channels including the Primary channel, and the communication means communicates with the first other communication device using one or more channels including the Primary channel after a predetermined time has elapsed even if no response is received from the other access point device.

21. The access point device according to claim 20, wherein a radio frame declaring occupation of one or more channels including the primary channel is also transmitted to the first other communication device.

22. An access point device as described in claim 20 or 21, wherein the specified time is determined based on a period during which the other access point device transmits to the second other communication device an instruction to use the second channel access method or an instruction to prohibit transmission of wireless frames, and a specified Interframe Space (IFS).

23. An access point device according to any one of claims 14 to 22, wherein the communication means transmits a radio frame regarding the occupancy of one or more channels including the primary channel to the first other communication device when a request is received from the other access point device.

24. A communications device that performs communications in accordance with the IEEE 802.11 standard series, comprising a communications means that participates in a first network established by a first access point device and communicates with the first access point device, the communications means transmitting a request for occupancy of one or more channels including a predetermined primary channel in one link to the first access point device, and transmitting a wireless frame regarding occupancy of one or more channels including the primary channel from the first access point device to a second access point device that establishes a second network in which communications are performed using either a first channel access method that uses at least the primary channel or a second channel access method that does not use the primary channel and uses a non-primary channel different from the primary channel among a plurality of channels included in the link, whereby the first access point device communicates with the first access point device using one or more channels including the primary channel when the one or more channels including the primary channel are occupied.

25. A communications device as described in claim 24, wherein the communications means communicates with the first access point device using one or more channels including the primary channel when the communications means receives a notification from the first access point device that the first access point device has been permitted to occupy one or more channels including the primary channel.

26. The communication device according to claim 24, wherein a radio frame regarding occupancy of one or more channels including the Primary channel transmitted from the first access point device to the second access point device is a radio frame declaring occupancy of one or more channels including the Primary channel, and the communication means communicates with the first access point device using one or more channels including the Primary channel after a predetermined time has elapsed since the transmission of the radio frame.

27. The communications device according to claim 26, wherein the specified time is determined based on a period during which the second access point device transmits to other communications devices participating in the second network an instruction to use the second channel access method or an instruction to prohibit transmission of wireless frames, and a specified Interframe Space (IFS).

28. A communication method executed by an access point device that communicates in accordance with the IEEE 802.11 standard series with other communication devices belonging to a first network established by the access point device, using either a first channel access method that uses at least a specified primary channel in one link, or a second channel access method that does not use the primary channel and uses a non-primary channel different from the primary channel among multiple channels included in the link, the control method including: receiving a wireless frame regarding the occupancy of one or more channels including the primary channel from another access point device that establishes a second network different from the first network, and when one or more channels including the primary channel are occupied in the second network, transmitting a notification to the other communication devices instructing them to use the second channel access method or to prohibit transmission of wireless frames.

29. A communications method executed by a communications device that communicates with a first access point device in a first network in accordance with the IEEE 802.11 standard series using either a first channel access method that uses at least a specified primary channel in one link, or a second channel access method that does not use the primary channel and uses a non-primary channel different from the primary channel among multiple channels included in the link, the communications method including: using the second channel access method when information instructing the use of the second channel access method is received in a response transmitted by the first access point device to a wireless frame regarding the occupancy of one or more channels including the primary channel transmitted by a second access point device constructing a second network different from the first network, or not transmitting a wireless frame when information instructing the prohibition of transmission of a wireless frame is received in the response.

30. A communication method executed by an access point device that establishes a first network and communicates with a first other communication device participating in the first network in accordance with the IEEE 802.11 standard series, comprising: transmitting a wireless frame regarding the occupancy of one or more channels including the primary channel to another access point device that establishes a second network in which communication is performed using either a first channel access method using a predetermined primary channel in one link or a second channel access method that does not use the primary channel and uses a non-primary channel different from the primary channel among multiple channels included in the link; and communicating with the first other communication device using one or more channels including the primary channel based on the transmission of the wireless frame, A communication method in which the wireless frame is a wireless frame that, when the other access point device receives the wireless frame and one or more channels including the primary channel are occupied in the first network, causes the other access point device to transmit an instruction to a second other communication device participating in the second network to use the second channel access method or an instruction to prohibit transmission of the wireless frame.

31. A communications method executed by a communications device that participates in a first network established by a first access point device and communicates with the first access point device in accordance with the IEEE 802.11 series of standards, the communications method comprising: transmitting to the first access point device a request for occupancy of one or more channels, including a predetermined primary channel in one link; and transmitting a wireless frame regarding occupancy of one or more channels, including the primary channel, from the first access point device to a second access point device that establishes a second network in which communication is performed using either a first channel access method that uses at least the primary channel or a second channel access method that does not use the primary channel and uses a non-primary channel different from the primary channel among a plurality of channels included in the link, thereby communicating with the first access point device using one or more channels, including the primary channel, when the one or more channels including the primary channel are occupied.

32. A program for causing a computer to function as each of the means possessed by the access point device according to any one of claims 1 to 11 or 14 to 23.

33. A program for causing a computer to function as each of the means possessed by the communication device according to any one of claims 12, 13, or 24 to 27.

Images