Communication device, control method, and program

Abstract

To more efficiently use a frequency resource in a communication system that uses a communication link comprising a plurality of channels.SOLUTION: In one communication link comprising a first channel used for acquiring a transmission right, and a second channel different from the first channel, a communication device performs communication with another communication device belonging to a first network, by using one of a first communication method using one or more channels including the first channel, and a second communication method using the second channel on condition that a period is set during which transmission of a radio frame using the first channel is not performed due to communication in a second network different from the first network. The communication device notifies the other communication device of information indicating a threshold that is related to the length of the period, and that permits using the second communication method when the length of the period set in the other communication device exceeds the threshold.SELECTED DRAWING: Figure 6

Description

[Technical field]

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

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

[0003] As one of the candidate technologies to be included in the IEEE802.11bn standard, a technology for efficiently using frequency resources in a communication method using a communication link consisting of multiple channels is being considered. For example, Patent Document 1 describes a technology for performing communication using other channels when the Primary Channel used to acquire the transmission right cannot be used. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] U.S. Pat. No. 1,169,6353 Summary of the Invention [Problem to be solved by the invention]

[0005] The present invention provides a technique for enabling more efficient utilization of frequency resources in a communication system using a communication link consisting of multiple channels. [Means for solving the problem]

[0006] A communication device according to one aspect of this embodiment is a communication device that communicates in accordance with the IEEE 802.11 standard series, and has a communication means for communicating with other communication devices belonging to the first network using either a first communication method using one or more channels including the first channel in a single communication link consisting of a first channel used to construct a first network and acquire transmission rights and one or more second channels different from the first channel, or a second communication method using one or more of the second channels, on the condition that a period is set during which no wireless frames are transmitted using the first channel due to communication in a second network different from the first network, and a notification means for notifying the other communication devices of information indicating a threshold related to the length of the period, at which it is permitted to use the second communication method when the length of the period set in the other communication devices exceeds the threshold. Effect of the Invention

[0007] According to the present invention, frequency resources can be utilized more efficiently in a communication system using a communication link consisting of multiple channels. [Brief description of the drawings]

[0008] [Figure 1] FIG. 1 is a diagram illustrating an example of the configuration of a wireless communication system. [Diagram 2]1 is a schematic diagram illustrating an example of a time chart when a communication device transmits data. [Diagram 3] FIG. 2 illustrates an example of a hardware configuration of a communication device. [Figure 4] FIG. 2 is a diagram illustrating an example of a functional configuration of an AP. [Diagram 5] FIG. 2 is a diagram illustrating an example of the functional configuration of an STA. [Figure 6] FIG. 11 is a diagram illustrating an example of a flow of processing executed by a communication device. [Figure 7] 11 is a diagram showing an example of information elements notified from an AP to a STA. [Figure 8] FIG. 4 is a diagram showing an outline of control to be executed. [Figure 9] FIG. 4 is a diagram showing an outline of control to be executed. [Figure 10] FIG. 13 is a diagram illustrating a method for setting a threshold value. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0009] Hereinafter, the embodiments will be described in detail with reference to the attached drawings. Note that the following embodiments do not limit the invention according to the claims. Although the embodiments describe a number of features, not all of these features are essential to the invention, and the features may be combined in any manner. Furthermore, in the attached drawings, the same reference numbers are used for the same or similar configurations, and duplicated descriptions are omitted.

[0010] (System Configuration) FIG. 1 shows an example of the configuration of a wireless communication system according to this embodiment. The wireless communication system includes, for example, an access point (AP101) and a station (STA102). The AP101 and the STA102 are communication devices capable of performing wireless communication conforming to the IEEE802.11 standard series. In this embodiment, when there is no need to distinguish between the AP101 and the STA102, they may be collectively referred to as communication devices. IEEE is an abbreviation for the Institute of Electrical and Electronics Engineers. FIG. 1 shows a configuration in which the STA102 participates in a network 103 constructed by the AP101. The network 103 may also be called a Basic Service Set (BSS). Note that FIG. 1 shows a state in which a network 113 composed of the AP111 and the STA112 exists in the vicinity of the network 103 composed of the AP101 and the STA102. The AP111 and the STA112 are communication devices capable of performing wireless communication conforming to the IEEE802.11 standard series, like the AP101 and the STA102. For AP101 and STA102, network 103 is a BSS to which the own device is connected, and may be called own BSS. On the other hand, for AP101 and STA102, network 113 is a network that may cause interference to the own BSS, and may be called overlapping BSS (OBSS). Note that, although an example in which one AP and one STA exist in each of the two networks is shown in FIG. 1, a plurality of APs and STAs may exist in one network. In addition, at that time, a plurality of STAs may be connected to one AP, and a single STA may be connected to a plurality of APs. Note that, in the following, the description will be focused on AP101 and STA102, but AP111 and STA112 may have the same functions.

[0011] 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 standard to the IEEE 802.11be standard that targets a maximum transmission speed of 46.08 Gbps (Giga bit per second). The IEEE 802.11bn standard is scheduled to be implemented with functions that realize high reliability communication, low latency communication, and improved throughput when communication traffic is congested, as main features. A wireless frame used in a communication method conforming to this standard may be called an UHR (Ultra High Reliability) PPDU. PPDU is an abbreviation for PLCP Protocol Data Unit, and PLCP is an abbreviation for Physical Layer Convergence Protocol. Note that the names of UHR, IEEE 802.11bn, etc. may be changed to other names when the formulation of the standard is completed. It should be noted that this specification and the claims attached hereto are applicable to communication devices using all successor standards to the IEEE802.11be. The communication device may be compatible with at least one of the legacy standards that are standards prior to the IEEE802.11bn standard. The legacy standards are, for example, the IEEE802.11a / 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 is, for example, a wireless LAN router or a personal computer (PC), but is not limited thereto. The AP 101 may be an information processing device such as a wireless chip capable of performing wireless communication conforming to the IEEE802.11bn standard or the like.The STA 102 is, for example, but 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 IEEE802.11bn standard or the like.

[0012] A communication device may transmit and receive radio signals using frequency bands such as 2.4 GHz, 3.6 GHz, 5 GHz, and 6 GHz, as well as 45 GHz and 60 GHz bands, which are called 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. 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 use, for example, bandwidths of 240 MHz and 4 MHz. In the IEEE 802.11 standard series, a frequency channel using a bandwidth of 20 MHz is specified as a basic channel in frequency bands such as 2.4 GHz, 5 GHz, and 6 GHz. In this standard, multiple available channels are defined in each of the 2.4 GHz, 5 GHz, and 6 GHz frequency bands. In this standard, a communication device may use a certain channel in combination with another adjacent channel. Such use of a channel in combination with another adjacent channel may be called channel bonding. A bundle of channels formed by one or two or more adjacent channels may be called a communication link. That is, one link formed by two channels with a bandwidth of 20 MHz may use a bandwidth of 40 MHz. In the IEEE802.11be standard, 320 MHz is expected to be specified as the maximum bandwidth available for one link. Furthermore, signals transmitted in this bandwidth may be continuous or discontinuous on the frequency axis. The AP 101 and the STA 102 may be AP MLD (Multi-Link Device) and STA MLD, respectively, that support Multi-Link, which establishes multiple links simultaneously to communicate.

[0013] When a communication device transmits a signal using a link established with another communication device, the communication device performs carrier sense to determine whether or not the signal can be transmitted. Carrier sense is an operation in which the communication device determines whether or not a signal exists 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 exists when the received signal strength exceeds a predetermined threshold (physical carrier sense). The received signal strength may also be called a Received Signal Strength Indicator (RSSI). The communication device may also determine whether or not a signal exists based on information such as a Duration field included in a signal received on a channel (virtual carrier sense). For example, the communication device stores a period indicated by a Duration field included in a received signal as a Network Allocation Vector (NAV) in the communication device. The communication device may handle the stored NAV as a period during which the communication device prohibits transmission of wireless frames from the communication device. In this embodiment, the operation in which the communication device sets a period during which the communication device does not transmit based on information such as a Duration field of a received signal is called setting a NAV. That is, until the NAV set for the channel expires, the communication device determines that a signal is present on the channel. In this way, the communication device determines whether or not a signal is present on the channel based on the results of performing physical carrier sense and virtual carrier sense. If the communication device determines that a signal is present on the channel, it may determine that transmission is not possible. In this case, the state of the channel may be called a busy state. On the other hand, a state in which no signal is detected on the channel in carrier sense and no NAV is set may be called an idle state. If the channel is in an idle state, the communication device may determine that transmission is possible.

[0014] For example, when a communication device communicates using a link with a bandwidth of 160 MHz, the communication device may determine whether or not transmission is possible 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 standard series describes that a communication device may start transmission if it determines that transmission is possible as a result of performing carrier sense on the PCH for a predetermined period of time. The predetermined period is determined by an Interframe Space (IFS) determined for each access category that classifies the type of communication traffic, and a random number (backoff counter) that is randomly determined from a predetermined range. That is, when the communication device determines that the PCH is in an idle state for this predetermined period of time, it acquires a transmission right to transmit using the link. At this time, if a second channel other than the PCH is in an idle state during a PIFS period immediately before the start of transmission, the communication device may perform transmission by channel bonding using the idle channel and the PCH. PIFS is an abbreviation for Priority Interframe Space. Furthermore, when a communication device determines that transmission is not possible as a result of performing carrier sensing on a PCH, the communication device may postpone transmission even if other channels included in the same link are in an idle state. Each second channel other than the PCH constituting one link may also be called a secondary channel (SCH) or a non-primary channel (NPCH).

[0015] 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) arranged at a frequency close to the channel, the received signal may not be properly received. For example, it is assumed that a communication device can simultaneously perform a transmission process and a reception process using different channels. When a communication device receives using a certain channel and transmits on an adjacent channel, the power of the transmission signal leaks into the channel of the received signal, causing interference with the received signal. In general, the power of such a leakage of the transmission signal is much greater than the received power of the received signal, so it is expected that the received signal cannot be properly received. In order to avoid such a situation, the IEEE802.11 standard series provides a mechanism for preventing another communication device from transmitting a signal to the 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 transmission is possible, and it is stipulated that while one communication device is transmitting using the PCH, the other communication device will not transmit even if the other channel is in an idle state. As a result, while a communication device is transmitting a signal and the PCH is in use, other communication devices do not transmit signals using channels adjacent to the PCH, so that the communication device does not receive a signal on the adjacent channel. Therefore, the above-mentioned problem of interference caused by power leakage between channels can be solved.

[0016] However, not using other channels (NPCH) that are in an idle state based on the PCH being busy may hinder efficient use of frequency resources of the entire link. FIG. 2(A) shows an example of a time chart when STA102 transmits data to AP101. In FIG. 2(A), STA102 performs carrier sense on PCH, confirms that it is in an idle state, and then transmits data using PCH with a bandwidth of 20 MHz. In this case, for example, even if seven NPCHs other than PCH are in an idle state, other communication devices are not allowed to communicate using NPCH. Also, FIG. 2(B) shows another example of a time chart when STA102 transmits data to AP101. In FIG. 2(B), while STA102 is performing carrier sense on PCH, PCH is used by another network (for example, network 113 in FIG. 1) that exists in the geographical vicinity of STA102. In this case, since the PCH is determined to be busy in the carrier sense by the STA 102, even if the seven NPCHs other than the PCH are idle, the STA 102 is not permitted to communicate with the AP 101 using the NPCH. However, since the AP 101 is not transmitting at this time, even if the STA 102 transmits to the AP 101 using the NPCH, the AP 101 can properly receive the signal transmitted by the STA 102. In this way, if the PCH with a bandwidth of, for example, 20 MHz is used by another network, and the remaining NPCH with an idle bandwidth of 140 MHz is not used, the frequency resources cannot be used efficiently.

[0017] In this embodiment, in view of such circumstances, when a PCH is being used by another communication device, a function is provided for communication between communication devices using an NPCH included in the same link as the PCH without using the PCH. As an example, when the PCH is busy, the communication device sets a Secondary Primary Channel (SPCH) used to acquire a transmission right for transmission using the NPCH. The SPCH is one or more channels among the NPCH included in the same link as the PCH. When the communication device determines that the PCH is being used by another communication device, it subsequently determines whether transmission is possible in the SPCH. That is, the communication device performs the above-mentioned carrier sense in the SPCH, and determines that communication using the NPCH can be performed based on confirmation that the SPCH is in an idle state. Then, when the communication device determines that transmission is possible in 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 the SPCH without using the 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 the PCH is available, the communication device performs communication in a first communication method in which communication is performed in one communication link using the PCH and one or more NPCHs. On the other hand, the communication device is configured to be able to perform communication in a second communication method (NPCH access) when a certain further condition (e.g., the NPCH is not used) is satisfied, provided that the PCH is not available.

[0018] Here, for example, as shown in FIG. 2B, when the NAV is set in the PCH by using the OBSS, the communication device can use the NPCH access to communicate when the SPCH is available. However, if the NAV period is not long enough, the NAV period in the PCH may expire during communication by the NPCH access, and the NPCH access may continue even though the PCH is in an idle state. For this reason, it is important that the NPCH access ends before the completion of the NAV. For this reason, the communication device of this embodiment may not execute the NPCH access when the NAV period (by the communication of the OBSS) in the PCH is not sufficiently left. On the other hand, the criteria for determining that the NAV period is "sufficiently left" are not necessarily clear. And, if each communication device independently sets the NAV period length that is determined to be "sufficiently left", it may not be possible to guarantee the fairness of the channel access opportunity in those communication devices.

[0019] For this reason, in this embodiment, for example, the AP 101 notifies a connected STA such as the STA 102 of information indicating a threshold value of the length of the NAV period in the PCH for determining whether or not to perform NPCH access. Then, based on the notification, when the NAV in the PCH is set by the OBSS communication, the STA performs NPCH access if the remaining length of the NAV is equal to or greater than the notified threshold. If the remaining length of the NAV is less than the notified threshold, the STA does not perform NPCH access. Note that the AP 101 may notify the connected STA of the threshold information individually, or may notify a plurality of STAs of the threshold information simultaneously by multicast or broadcast. This allows the STAs connected to the AP 101 to fairly acquire the transmission right by NPCH access.

[0020] (Device configuration) 3 shows an example of the hardware configuration of a communication device (AP101, AP111, STA102, and STA112). The communication device has 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 only examples, and the communication device may have further configurations not shown in FIG. 3, and some or all of the configurations shown in FIG. 3 may be replaced with other configurations having similar functions.

[0021] The storage unit 301 includes one or more memories such as a ROM and 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 and a RAM. The storage unit 301 may include storage media such as a plurality of memories.

[0022] 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 executes a computer program stored in the storage unit 301 to control the entire communication device. The control unit 302 may control the entire device in cooperation with the computer program stored in the storage unit 301 and an operating system. The control unit 302 generates data and signals (radio frames) to be transmitted in communication with other communication devices. The control unit 302 may include multiple processors, such as a multi-core processor, and the multiple processors may control the entire communication device.

[0023] Furthermore, the control unit 302 controls the functional unit 303 to execute predetermined processes such as wireless communication, image capture, printing, and projection. The functional unit 303 is configured to include hardware for the communication device to execute predetermined processes. When the communication device is a printer, the functional unit 303 is a printing device, and prints image data acquired via the communication unit 306, for example. When the communication device is a scanner, the functional unit 303 is a reading device, and outputs image data generated by scanning to the outside, for example, via the communication unit 306. When 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.

[0024] 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 a display, a speaker, etc., and performs various outputs to the user. Here, the output by the output unit 305 may be a screen display output on a display, or a voice output by a speaker. The output unit 305 may also include a vibrator, and may perform information output by vibration output. Note that both the input unit 304 and the output unit 305 may be implemented by one module, such as a touch panel display. Also, 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.

[0025] The communication unit 306 executes control for performing wireless communication conforming to the IEEE802.11bn standard. In addition to the IEEE802.11bn standard, the communication unit 306 may also control wireless communication conforming to other IEEE802.11 standard series and wired communication such as 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, Bluetooth standard, and the like in addition to the IEEE802.11bn standard, the communication unit 306 may control wireless communication conforming to these communication standards. In addition, if the communication device is capable of performing wireless communication conforming to a plurality of communication standards, a communication unit and an antenna corresponding to each of these communication standards may be provided separately.

[0026] 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. Although FIG. 3 shows an example in which the communication device has two antennas, one antenna may be used, or three or more antennas may be used. In addition, when the communication device has multiple antennas, it may have a communication unit 306 corresponding to each antenna. In addition, the antenna 307 may be prepared separately from the communication unit 306, or may be configured as one module together with the communication unit 306.

[0027] FIG. 4 is a block diagram showing an example of the functional configuration of an AP (AP101 and AP111). The AP includes, for example, a PCH communication control unit 401, an NPCH communication control unit 402, and a threshold notification unit 403. These functions can be implemented by, for example, executing a program stored in a storage unit 301 of the AP by a control unit 302. However, this is just an example, and dedicated hardware for implementing each function may be prepared. The configuration shown in FIG. 4 is just an example, and the AP may include configurations other than these configurations. Furthermore, two or more functional blocks in FIG. 4 may be implemented as one functional block, or one functional block may be divided into two or more functional blocks.

[0028] The PCH communication control unit 401 establishes one link with the STA, which uses one or more channels including the PCH, and performs communication. For example, the PCH communication control unit 401 receives a wireless frame from a STA connected to the own device that has acquired a transmission right in the PCH, or the PCH communication control unit 401 acquires a transmission right in the PCH and transmits a wireless frame to the STA. The NPCH communication control unit 402 performs communication using the NPCH access when the PCH is used by another device and the AP cannot use the PCH. For example, when the NAV is set in the PCH (for example, due to use by the OBSS), the NPCH communication control unit 402 confirms that the SPCH is in an idle state and acquires a transmission right in the NPCH. Then, when the NPCH communication control unit 402 acquires a transmission right in the NPCH, it transmits a wireless frame using one or more NPCHs including the SPCH without using the PCH. The NPCH communication control unit 402 also receives a wireless frame transmitted by a STA connected to the own device through the NPCH access. The threshold notification unit 403 notifies the STA connected to the own device of a threshold related to the NAV length used when determining whether or not to execute NPCH access. The NPCH communication control unit 402 compares the threshold notified to the STA by the threshold notification unit 403 with the NAV length set in the PCH to determine whether or not to execute NPCH access.

[0029] FIG. 5 is a block diagram showing an example of the functional configuration of the STA (STA102 and STA112). The STA includes, for example, a PCH communication control unit 501, a threshold receiving unit 502, and an NPCH communication control unit 503. These functions can be implemented by, for example, executing a program stored in a storage unit 301 of the STA by the control unit 302. However, this is only an example, and dedicated hardware for implementing each function may be prepared. The configuration shown in FIG. 5 is only an example, and the STA may include configurations other than these configurations. Furthermore, two or more functional blocks in FIG. 5 may be implemented as one functional block, or one functional block may be divided into two or more functional blocks.

[0030] The PCH communication control unit 501 performs the same control as the PCH communication control unit 401 of the AP. That is, the PCH communication control unit 501 establishes one link with the AP that uses one or more channels including the PCH together to perform communication. For example, the PCH communication control unit 501 receives a wireless frame from the AP connected to the own device that has acquired a transmission right in the PCH, or transmits a wireless frame to the AP by acquiring a transmission right in the PCH. The threshold receiving unit 502 receives a threshold related to the length of the NAV from the AP, which is used when determining whether or not to perform NPCH access. The NPCH communication control unit 503 compares the threshold received by the threshold receiving unit 502 with the length of the NAV set in the PCH to determine whether or not to perform NPCH access.

[0031] (Processing flow) Next, an example of the flow of the process executed by the communication device (AP and STA) will be outlined with reference to Fig. 6. First, the AP and STA share a threshold value related to the length of the NAV used when determining whether or not to execute NPCH access (S601). That is, the AP notifies the STA of information on the threshold value.

[0032] The AP transmits a radio frame including an information element as shown in FIG. 7A to the STA. The information element in FIG. 7A may be an information element used to notify a parameter for NPCH access. Here, this information element is referred to as a Non Primary Channel Access (NPCA) Parameter Set element, but similar information elements with other names may be used as standardization progresses. In this information element, a value indicating that this information element is an NPCA Parameter Set element is stored in Element ID 701. A value indicating the length of this information element is stored in Length 702. Then, the above-mentioned threshold information is stored in NAV Threshold 703. Note that this information element may include other information. Also, in FIG. 7A, NAV Threshold 703 is placed immediately after Length 702, but other information may be included between Length 702 and NAV Threshold 703. Note that, although an example in which a threshold is notified as a part of a parameter for NPCH access is shown, threshold information may be included in other information elements. The information element in Fig. 7(A) may be included in a Beacon frame, for example, and may be periodically sent by the AP. The information element in Fig. 7(A) may also be included in a Probe Response frame, which is a probe response to a probe request (Probe Request frame) from the STA. This information may also be included in a frame (such as an Association Response frame) transmitted and received in the connection process, or in an Action frame after connection.

[0033] Thereafter, when data to be transmitted occurs (YES in S602), the AP and STA judge whether or not the NAV resulting from the OBSS communication is set in the PCH (S603). If the NAV resulting from the OBSS communication is not set in the PCH (NO in S603), the AP and STA communicate using the PCH (S606). That is, the AP and STA execute carrier sense and acquire the transmission right in the PCH (and NPCH) based on the confirmation that the PCH is in an idle state. Then, the AP and STA transmit data and receive an acknowledgement (ACK) during the period during which the transmission right is acquired. On the other hand, if the NAV resulting from the OBSS communication is set in the PCH (YES in S603), the AP and STA judge whether or not the remaining time exceeds the threshold shared in S601 (S604). Then, if the remaining time does not exceed the threshold (NO in S604), the AP and STA wait until the timer of the NAV in the PCH expires (NO in S603), and transmits a wireless frame using the PCH (S606). On the other hand, if the remaining time exceeds the threshold (YES in S604), the AP and STA communicate using the NPCH access (S605). That is, when the AP and STA execute carrier sense in the SPCH and acquire the transmission right in the NPCH, they transmit data and receive ACKs using the NPCH during the period in which the transmission right is acquired. Note that, if the AP and STA cannot acquire the transmission right in the NPCH and the remaining period of the NAV in the PCH falls below the threshold, they may not communicate using the NPCH access. That is, the AP and STA may continue to execute the determination in S604 during the process of S605. Note that the communication using the NPCH access may be executed during the period until the NAV in the PCH expires. That is, the AP and the STA can execute communication control so that communication via NPCH access is terminated at the timing when the PCH becomes available for use.

[0034] Next, an example of communication control according to the present embodiment will be described with reference to Fig. 8(A) and Fig. 8(B). In Fig. 8(A), the AP 111 or the STA 112 confirms that the PCH is in an idle state for a predetermined period 801, and transmits, for example, a Request To Send (RTS) or a Clear To Send (CTS). Then, the AP 101 or the STA 102 sets the NAV 802 so as not to transmit signals for the period specified by the RTS or CTS. That is, the AP 101 or the STA 102 sets the NAV for the PCH due to communication in the OBSS, and performs control so as not to transmit wireless frames using the PCH until the NAV period expires. Then, when the AP 101 or the STA 102 has data to be transmitted, the NAV is set in the PCH, so that the AP 101 or the STA 102 determines whether or not to perform NPCH access. At this time, the threshold value 803 of the length of the NAV shared by the AP 101 and the STA 102 is compared with the length of the remaining time of the NAV in the PCH. Then, when the AP 101 and the STA 102 confirm that the remaining time of the NAV in the PCH is longer than a threshold value 803, they decide to perform NPCH access. Then, the AP 101 and the STA 102 transmit data 805 in the NPCH after confirming that the SPCH is in an idle state for a predetermined period 804, for example. After the data 805 is transmitted and a SIFS (Short IFS) 806 has elapsed, an acknowledgement (Block Ack (BA)) 807 follows, and similarly, data communications 808 to 811 may be repeated until the expiration of the NAV 802. Note that the AP 101 and the STA 102 may communicate as if the communication by the NPCH access had been completed at the time of the expiration of the NAV 802. Also, the AP 101 or the STA 102 may secure a transmission opportunity (TXOP) for a period required for the AP 101 or the STA 102 to transmit data, and may terminate the data communication in response to the expiration of the TXOP. That is, the AP 101 and the STA 102 can transmit and receive wireless frames so that data communication is completed before the expiration of the NAV 802 or the TXOP.

[0035] In FIG. 8B, AP111 or STA112 confirms that PCH is idle for a predetermined period 821 and transmits, for example, RTS or CTS. AP101 or STA102 sets NAV822 accordingly. When data to be transmitted occurs, AP101 and STA102 compare the remaining time of NAV at that time with threshold 823 because NAV is set in PCH, and determine whether to perform NPCH access. In the example of FIG. 8B, since the remaining time of NAV is shorter than threshold 823, AP101 and STA102 make decision 824 not to perform NPCH access. Therefore, AP101 and STA102 wait until NAV822 expires, and then transmit data 826 using PCH in response to the fact that PCH has been idle for a predetermined period 825. Note that AP101 and STA102 can transmit data 827 using NPCH in parallel if NPCH is not used at this time. That is, the AP 101 and the STA 102 can communicate using a PCH and one or more NPCHs in one link.

[0036] In this way, the AP notifies the STA of the threshold of the remaining time of the NAV in the PCH for determining whether or not to perform NPCH access, thereby preventing NPCH access from being attempted even when there is not enough remaining time. Also, by using a common threshold for many STAs, it becomes possible for the many STAs to fairly acquire the right to transmit by NPCH access.

[0037] In the above description, an example in which one threshold is notified has been shown, but multiple thresholds may be used. For example, a first threshold for transmitting data requiring low latency (hereinafter referred to as "LL") and a second threshold for transmitting data not requiring LL may be notified. In this case, for example, the first threshold is set smaller than the second threshold, so that for data requiring LL, communication by NPCH access can be preferentially performed in a situation in which NAV by OBSS is set in PCH. In this case, for example, an information element in which the information element in FIG. 7(A) is extended, as shown in FIG. 7(B), is transmitted from the AP to the STA. The information element in FIG. 7(B) includes LL NAV Threshold 711 indicating the first threshold for data requiring LL and Non-LL NAV Threshold 712 indicating the second threshold for data not requiring LL. Here, the first threshold may be set shorter than the second threshold. By receiving this information element, the STA may attempt NPCH access when the NAV of the OBSS with the remaining time of the data that requires LL is set to PCH, which is equal to or greater than the first threshold. On the other hand, for data that does not require LL, even if the NAV of the OBSS with the remaining time of the data that does not require LL is set to PCH, the STA does not perform NPCH access if the remaining time of the NAV is below the second threshold. Also, for data that does not require LL, the STA performs NPCH access when the NAV of the OBSS with the remaining time of the data that does not require LL is set to PCH, which is equal to or greater than the second threshold.

[0038] An example of communication control in the case where a plurality of thresholds are used in this way will be described with reference to Figs. 9(A) and 9(B). In the examples of Figs. 9(A) and 9(B), it is assumed that the NAV for OBSS communication is set in the PCH, as in the examples of Figs. 8(A) and 8(B). Fig. 9(A) shows an example in the case where the AP and STA detect the generation of data to be transmitted that requires an LL. In this case, the AP and STA compare the first threshold 901 of the NAV to be used when transmitting data that requires an LL with the remaining time of the NAV. Then, when the remaining time of the NAV is longer than the first threshold 901, the AP and STA execute NPCH access to transmit data that requires an LL, and when the transmission right is acquired in the SPCH, transmit data 902 that requires an LL. Fig. 9(B) shows an example in the case where the AP and STA detect the generation of data to be transmitted that does not require an LL. It is assumed that the length of the NAV for OBSS communication set in the PCH at this time is the same as that in Fig. 9(A). Here, the second threshold 911 for data not requiring LL is greater than the first threshold 901 for data requiring LL. The AP and STA compare the second threshold 911 with the remaining time of the NAV. Here, the example of FIG. 9B shows a case where the second threshold 911 is greater than the remaining time of the NAV. In this case, the AP and STA do not perform NPCH access, and wait until the NAV in the PCH expires. Then, when the AP and STA acquire a transmission right in the PCH after the NAV expires, they transmit data 912 (and 913) in the PCH and, if necessary, in the NPCH.

[0039] According to such a procedure, for data that has strict latency requirements and should be transmitted as soon as possible, the probability of NPCH access being performed is increased, and the time from data generation to transmission can be shortened. On the other hand, for data that does not have strict latency requirements, since it is not necessary to transmit immediately, a threshold value is set to be larger than that for data that has strict latency requirements, thereby realizing fair channel access between STAs. Note that, for example, whether or not the latency requirements are strict may be determined based on the access category (AC) of the data. For example, data with ACs of voice (AC_VO) and video (AC_VI) may be determined as data that requires LL, and data with ACs of background (AC_BK) or best effort (AC_BE) may be determined as data that does not require LL. Also, only AC_VO may be treated as data that requires LL, and other data may be treated as data that does not require LL. Also, whether or not LL is required may be associated in advance with each Traffic Identifier (TID) corresponding to data to be transmitted. For example, the AP and the STA use information associating a predefined AC or TID with a value indicating whether or not an LL is required to determine whether or not the data to be transmitted requires an LL. Then, when transmitting the data, the AP and the STA can use a threshold value according to the determination result to determine whether or not to perform NPCH access.

[0040] In addition, multiple thresholds may be set according to the latency requirement level. For example, the first threshold for the first data with the strictest latency requirement (minimum required delay) is set to the smallest value, and the second threshold for the second data with the next strictest latency requirement is set to the next smallest value. Also, the third threshold for the third data with the next strictest latency requirement after the second data is set to a value larger than the second threshold, and the threshold for the data with the least strict latency requirement (e.g., no latency requirement) may be set to the maximum. That is, multiple thresholds may be set so that the shorter the required delay, the smaller the threshold value. Also, NPCH access may not be permitted for specific data (e.g., data with no latency requirement) as necessary.

[0041] Also, multiple thresholds may be set according to the access category. That is, separate thresholds may be set for each of AC_VO, AC_VI, AC_BK, and AC_BE. In this case, for example, information elements as shown in FIG. 7(C) may be transmitted from the AP to the STA. Note that, instead of the threshold for each access category, the threshold for each TID may be notified. Also, the threshold may be determined according to the expected data length for each category or TID, regardless of the required latency. That is, regardless of the required latency, the threshold may be determined so that the NPCH access is performed when it is expected that the communication by the NPCH access will be completed before the NAV expires in the PCH. Also, the NPCH access may not be permitted for data of some access categories or TIDs. Note that, when the NPCH access is not permitted regardless of the remaining time of the NAV, the threshold notified in FIG. 7(A) to FIG. 7(C) may be set to a predetermined value such as, for example, "0" or a maximum value that can be expressed.

[0042] The threshold value may be set based on the time required for transmitting and receiving data. For example, as shown in FIG. 10, when data is transmitted after RTS and CTS are transmitted, and a BA for the data is transmitted, a threshold value 1001 according to the time length of these frames may be set. Here, the time length obtained by adding the data time length to the sum of the total time length of the time length 1002 from the transmission of the RTS to the start of data transmission and the time length 1003 from the end of data transmission to the end of BA transmission is the time length required for data communication. Here, since the data time length is variable, the threshold value may be set to a value that exceeds at least the sum of the time length 1002 and the time length 1003. That is, as the threshold value, a value that exceeds the value obtained by adding the time length of the RTS, the time length of the CTS, the time length of the BA (ACK), and three times the time length of the SIFS is set. Here, the threshold value may be set as a value obtained by adding the time length corresponding to the data length to this minimum value. Here, the time length corresponding to the data length may be set based on, for example, a standard data amount obtained statistically. This prevents the threshold from being set below the minimum required time, and prevents NPCH access from continuing after the NAV expires in the PCH. Also, it is possible to at least shorten the time during which NPCH access is performed after the NAV expires in the PCH.

[0043] Also, for example, an AP can acquire the right to transmit by transmitting CTS-self without transmitting RTS. For this reason, a value exceeding the sum of the time length of CTS, the time length of BA (ACK), and twice the time length of SIFS may be used as the threshold. That is, different thresholds may be used for the AP and the STA. In some cases, when communication is performed without using RTS or CTS, or when it is necessary to transmit other additional wireless frames, the minimum threshold may be determined based on the number of SIFS between wireless frames to be actually transmitted. Note that, in any communication, when communication is performed with the configuration as shown in FIG. 10, the threshold notified from the AP to the STA may be specified as "0", which is the sum of the time length of RTS, the time length of CTS, the time length of BA (ACK), and three times the time length of SIFS. In addition, when wireless frames are transmitted in various formats, such as when RTS / CTS is not transmitted or when additional frames are used, the minimum time length required for each of those formats may be different. In this case, the minimum value of multiple minimum time lengths corresponding to each of the multiple formats may be notified as a threshold value indicating the minimum required time length as a reference value. That is, when the threshold value is X and the value indicating the minimum required time length is Y, "XY" may be notified from the AP to the STA as information indicating the threshold value.

[0044] The role of the AP in the above description may be performed by a STA. For example, a STA may set the above threshold when communicating with another STA.

[0045] With the above configuration, it is possible to prevent NPCH access from being unnecessarily continued after the NAV caused by OBSS communication in PCH expires, and it is possible to use frequency resources more efficiently. Also, by providing a common threshold value to STAs under the AP, it is possible to ensure fairness in channel access when NPCH access is performed. Furthermore, by using multiple threshold values, it is possible to perform control to make NPCH access easier to perform depending on the type of data, etc.

[0046] The present invention can also be realized by a process in which a program for implementing one or more of the functions of the above-described embodiments is supplied to a system or device via a network or a storage medium, and one or more processors in a computer of the system or device read and execute the program. The present invention can also be realized by a circuit (e.g., ASIC) that implements one or more of the functions.

[0047] (Summary of the embodiment) At least some of the above-described embodiments can be summarized as follows. (Item 1) A communication device that performs communication in accordance with the IEEE 802.11 standard series, a communication means for establishing a first network and communicating with another communication device belonging to the first network by using either a first communication method using one or more channels including the first channel in one communication link composed of a first channel used for acquiring a transmission right and one or more second channels different from the first channel, or a second communication method using one or more of the second channels on condition that a period during which no wireless frame is transmitted using the first channel is set due to communication in a second network different from the first network; a notification means for notifying the other communication device of information indicating a threshold related to the length of the period, the threshold being a threshold at which use of the second communication method is permitted when the length of the period set in the other communication device exceeds the threshold; A communication device comprising: (Item 2) The communication device described in item 1, characterized in that the notification means notifies the other communication device of information indicating the threshold, the information indicating a first threshold for determining whether transmission of data requiring low latency is acceptable, and a second threshold for determining whether transmission of data not requiring low latency is acceptable. (Item 3) The communication device described in item 1, characterized in that the notification means notifies the other communication device of information indicating a threshold for determining whether transmission of data of the access category is permitted for each access category as the information indicating the threshold. (Item 4) The communication device described in item 1, characterized in that the notification means notifies the other communication device of information indicating a threshold for determining whether transmission of data assigned to a Traffic Identifier (TID) is permitted for each TID as the information indicating the threshold. (Item 5) The communication device according to any one of items 1 to 4, characterized in that the threshold is set to a value greater than the sum of the time lengths of Request To Send (RTS), Clear To Send (CTS), the time length of the acknowledgement response, and three times the time length of a Short Interframe Space (SIFS). (Item 6) The communication device according to any one of items 1 to 5, characterized in that a predetermined value is notified as the threshold value, thereby indicating that use of the second communication method is not permitted regardless of the length of the period. (Item 7) 7. The communication device according to any one of items 1 to 6, wherein the notification means transmits the information indicating the threshold value in a Beacon frame. (Item 8) 7. The communication device according to any one of items 1 to 6, wherein the notification unit transmits the information indicating the threshold value in a Probe Response frame. (Item 9) A communication device that performs communication in accordance with the IEEE 802.11 standard series, a communication means for communicating with the other communication device by using either a first communication method using one or more channels including a first channel, the first channel being used to participate in a first network established by the other communication device and obtain a transmission right, and one or more second channels different from the first channel, on condition that a period during which no wireless frame is transmitted using the first channel is set due to communication in a second network different from the first network; a receiving means for receiving information indicating a threshold value related to the length of the period from the other communication device; a determination means for determining whether or not a remaining time of a period during which no wireless frame is transmitted using the first channel due to communication in the second network is set, the remaining time of the period exceeding the threshold; a control means for performing control so as to communicate with the other communication device using the second communication method based on the determination that the length of the remaining time of the period exceeds the threshold value; A communication device comprising: (Item 10) The communication device described in item 9, characterized in that the receiving means receives from the other communication device, as the information indicating the threshold, information indicating a first threshold for determining whether transmission of data requiring low latency is permitted and a second threshold for determining whether transmission of data not requiring low latency is permitted. (Item 11) The communication device described in item 9, characterized in that the receiving means receives from the other communication device, as the information indicating the threshold, information indicating a threshold for determining whether transmission of data of the access category is permitted for each access category. (Item 12) The communication device described in item 9, characterized in that the receiving means receives from the other communication device, as the information indicating the threshold, information indicating a threshold for determining whether transmission of data assigned to a Traffic Identifier (TID) is permitted for each TID. (Item 13) The communication device according to any one of items 9 to 12, characterized in that the threshold is set to a value greater than the sum of the time lengths of Request To Send (RTS), Clear To Send (CTS), the time length of the acknowledgement response, and three times the time length of a Short Interframe Space (SIFS). (Item 14) 14. The communication device according to any one of items 9 to 13, characterized in that a predetermined value is notified as the threshold value, thereby indicating that the second communication method is not permitted to be used regardless of the length of the period. (Item 15) 15. The communication device according to any one of items 9 to 14, wherein the receiving means receives the information indicating the threshold value in a Beacon frame received from the other communication device. (Item 16) 15. The communication device according to any one of items 9 to 14, wherein the receiving means receives the information indicating the threshold value in a Probe Response frame received from the other communication device. (Item 17) A control method is executed by a communication device that establishes a first network and communicates in accordance with the IEEE 802.11 standard series with another communication device that belongs to the first network, using either a first communication method using one or more channels including the first channel, or a second communication method using one or more of the second channels on condition that a period during which no wireless frame is transmitted using the first channel is set due to communication in a second network different from the first network, in one communication link composed of the first channel and one or more second channels different from the first channel, the method comprising: A control method comprising: notifying the other communication device of information indicating a threshold related to the length of the period, the threshold being such that use of the second communication method is permitted when the length of the period set in the other communication device exceeds the threshold. (Item 18) A control method is executed by a communication device that performs communication in compliance with the IEEE 802.11 standard series with another communication device, using either a first communication method using one or more channels including the first channel, the first channel being used to participate in a first network established by another communication device and obtain a transmission right, and one or more second channels different from the first channel, on condition that a period during which no wireless frame is transmitted using the first channel is set due to communication in a second network different from the first network, the control method comprising: receiving information indicating a threshold value relating to a length of the period from the other communication device; determining whether or not a remaining time of the period during which no wireless frame is transmitted using the first channel due to communication in the second network exceeds the threshold value when the period is set; based on the determination that the length of the remaining time of the period exceeds the threshold, performing control so as to communicate with the other communication device using the second communication method; A control method comprising the steps of: (Item 19) A program for causing a computer to function as each of the means possessed by the communication device according to any one of items 1 to 16.

[0048] The invention is not limited to the above-described embodiments, and various modifications and variations are possible without departing from the spirit and scope of the invention. Accordingly, the following claims are appended to apprise the public of the scope of the invention. [Explanation of symbols]

[0049] 101: AP, 102: STA, 103: network (BSS), 111: AP, 112: STA, 113: network (OBSS), 403: threshold notification unit, 502: threshold reception unit, 503: NPCH communication control unit

Claims

1. A communication device that performs communication in accordance with the IEEE 802.11 standard series, a communication means for communicating with another communication device belonging to the first network, using either a first communication method using one or more channels including the first channel in one communication link composed of a first channel used for constructing a first network and acquiring a transmission right and one or more second channels different from the first channel, or a second communication method using one or more of the second channels on condition that a period during which no wireless frame is transmitted using the first channel is set due to communication in a second network different from the first network; a notification means for notifying the other communication device of information indicating a threshold related to the length of the period, the threshold being a threshold at which use of the second communication method is permitted when the length of the period set in the other communication device exceeds the threshold; A communication device comprising:

2. The communication device according to claim 1, characterized in that the notification means notifies the other communication device of information indicating the threshold, the information indicating a first threshold for determining whether transmission of data requiring low latency is permitted and a second threshold for determining whether transmission of data not requiring low latency is permitted.

3. The communication device according to claim 1, characterized in that the notification means notifies the other communication device of information indicating a threshold for determining whether transmission of data of the access category is permitted for each access category as the information indicating the threshold.

4. 2. The communication device according to claim 1, wherein the notification means notifies the other communication device of information indicating a threshold for determining whether transmission of data assigned to a Traffic Identifier (TID) is permitted for each TID, as the information indicating the threshold.

5. 2. The communication device according to claim 1, wherein the threshold value is set to a value greater than a sum of a time length of a Request To Send (RTS), a Clear To Send (CTS), a time length of an acknowledgment response, and a time length three times a Short Interframe Space (SIFS).

6. The communication device according to claim 1 , wherein a predetermined value is notified as the threshold value, thereby indicating that use of the second communication method is not permitted regardless of the length of the period.

7. The communication device according to claim 1 , wherein the notification unit transmits the information indicating the threshold value in a Beacon frame.

8. The communication device according to claim 1 , wherein the notification unit transmits the information indicating the threshold value in a Probe Response frame.

9. A communication device that performs communication in accordance with the IEEE 802.11 standard series, a communication means for communicating with the other communication device using either a first communication method using one or more channels including a first channel, the first channel being used to participate in a first network established by the other communication device and obtain a transmission right, and one or more second channels different from the first channel, on condition that a period during which no wireless frame is transmitted using the first channel is set due to communication in a second network different from the first network; a receiving means for receiving information indicating a threshold value related to the length of the period from the other communication device; a determination means for determining whether or not a remaining time of a period during which no wireless frame is transmitted using the first channel due to communication in the second network exceeds the threshold value when the period is set; a control means for performing control so as to communicate with the other communication device using the second communication method based on the determination that the length of the remaining time of the period exceeds the threshold value; A communication device comprising:

10. The communication device according to claim 9, characterized in that the receiving means receives from the other communication device, as the information indicating the threshold, information indicating a first threshold for determining whether transmission of data requiring low latency is permitted, and a second threshold for determining whether transmission of data not requiring low latency is permitted.

11. The communication device according to claim 9, characterized in that the receiving means receives from the other communication device, as the information indicating the threshold, information indicating a threshold for determining whether transmission of data of the access category is permitted for each access category.

12. 10. The communication device according to claim 9, wherein the receiving means receives, as the information indicating the threshold, information indicating a threshold for determining whether transmission of data assigned to a Traffic Identifier (TID) is permitted for each TID from the other communication device.

13. 10. The communication device according to claim 9, wherein the threshold value is set to a value greater than a sum of a time length of a Request To Send (RTS), a Clear To Send (CTS), a time length of an acknowledgment response, and a time length three times a Short Interframe Space (SIFS).

14. 10. The communication device according to claim 9, wherein a predetermined value is notified as the threshold value, thereby indicating that use of the second communication method is not permitted regardless of the length of the remaining time of the period.

15. 10. The communication device according to claim 9, wherein the receiving means receives the information indicating the threshold value in a Beacon frame received from the other communication device.

16. 10. The communication device according to claim 9, wherein the receiving means receives the information indicating the threshold value in a Probe Response frame received from the other communication device.

17. A control method is executed by a communication device that performs communication in accordance with the IEEE 802.11 standard series with another communication device belonging to a first network, using either a first communication method using one or more channels including the first channel, or a second communication method using one or more of the second channels on condition that a period during which no wireless frame is transmitted using the first channel is set due to communication in a second network different from the first network, in one communication link composed of a first channel used to construct a first network and acquire a transmission right, and one or more second channels different from the first channel, the control method comprising: A control method comprising: notifying the other communication device of information indicating a threshold related to the length of the period, the threshold being such that use of the second communication method is permitted when the length of the period set in the other communication device exceeds the threshold.

18. A control method is executed by a communication device that performs communication in compliance with the IEEE 802.11 standard series with another communication device, using either a first communication method using one or more channels including the first channel, the first channel being used to participate in a first network established by another communication device and obtain a transmission right, and one or more second channels different from the first channel, on condition that a period during which no wireless frame is transmitted using the first channel is set due to communication in a second network different from the first network, the control method comprising: receiving information indicating a threshold value related to a length of the period from the other communication device; determining whether or not a remaining time of the period during which no wireless frame is transmitted using the first channel due to communication in the second network exceeds the threshold value when the period is set; based on the determination that the length of the remaining time of the period exceeds the threshold, performing control so as to communicate with the other communication device using the second communication method; A control method comprising the steps of:

19. A program for causing a computer to function as each of the means included in the communication device according to any one of claims 1 to 16.

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