COMMUNICATION EQUIPMENT AND CONTROL METHODS

Abstract

The invention relates to a communication device which establishes a first network, and performs, with other communication devices of the first network, communication in accordance with the IEEE 802 family of standards.11. By dynamically switching the channel access scheme between the first channel access scheme, in which at least the primary channel is predetermined in the channel bundle created by the multi-channel link used, and the second channel access scheme, in which, in the case where the primary channel is occupied due to communication in the second network being different from the first network and the remaining duration during which other communication devices do not transmit radio frames using the primary channel due to communication in the second network being established, the primary channel is not used and one or more non-primary channels other than the primary channel among the many channels included in the channel bundle are used, notification is given to other communication devices, indicating the threshold information related to the remaining duration, and other communication devices are allowed to use the second channel access scheme in the case where the length of the remaining duration established in other communication devices exceeds the threshold.

Description

Communication device, control method, and program

[0001] The present disclosure relates to a data communication technique in a communication device capable of communication using a communication link configured by 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 disclosure provides techniques that enable more efficient utilization of frequency resources in a communication system that uses a communication link consisting of multiple channels.

[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: communication means for constructing a first network and communicating with other communication devices belonging to the 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 when a period is set in which other communication devices do not transmit wireless frames using the primary channel due to communication in a second network different from the first network, and uses one or more non-primary channels different from the primary channel among multiple channels included in the link; and notification means for notifying the other communication devices of information indicating a threshold value related to the length of the period, at which the other communication devices are allowed to use the second channel access method when the length of the period set in the other communication devices exceeds the threshold value.

[0007] According to the present disclosure, frequency resources can be utilized more efficiently in a communication system that uses a communication link consisting 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 an AP. FIG. 5 is a diagram illustrating an example of the functional configuration of an STA. FIG. 6 is a diagram illustrating an example of the flow of processing executed by a communication device. FIG. 7A is a diagram illustrating an example of information elements notified from an AP to an STA. FIG. 7B is a diagram illustrating an example of information elements notified from an AP to an STA. FIG. 7C is a diagram illustrating an example of information elements notified from an AP to an STA. FIG. 8A is a diagram illustrating an outline of control to be executed. FIG. 8B is a diagram illustrating an outline of control to be executed. FIG. 9A is a diagram illustrating an outline of control to be executed. FIG. 9B is a diagram illustrating an outline of control to be executed. FIG. 10 is a diagram illustrating a method of setting a threshold value.

[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] Here, for example, as shown in FIG. 2B , when a NAV is set in the PCH due to the use of the PCH by the OBSS, the communication device can communicate using the NPCH access when the SPCH is available. However, if the NAV period is not sufficiently long, the NAV period in the PCH may expire during communication via 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 NAV is completed. For this reason, the communication device of this embodiment may not perform NPCH access if there is not enough NAV period (due to OBSS communication) remaining in the PCH. However, the criteria for determining that the NAV period is "sufficiently remaining" are not necessarily clear. Furthermore, if each communication device independently sets the NAV period length that determines that there is "sufficient remaining," it may not be possible to ensure fairness in channel access opportunities among those communication devices.

[0020] For this reason, in this embodiment, for example, AP 101 notifies connected STAs, such as STA 102, of information indicating a threshold value for the length of the NAV period in the PCH for determining whether to perform NPCH access. Based on this notification, when a NAV is set in the PCH via 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 AP 101 may, for example, notify connected STAs of the threshold value information individually, or may notify multiple STAs of the threshold value simultaneously via multicast or broadcast. This allows STAs connected to AP 101 to fairly acquire the right to transmit via NPCH access.

[0021] (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.

[0022] 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.

[0023] 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.

[0024] 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.

[0025] 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.

[0026] 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.

[0027] 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.

[0028] FIG. 4 is a block diagram showing an example of the functional configuration of an AP (AP 101 and AP 111). 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, for example, by the control unit 302 executing a program stored in the storage unit 301 of the AP. However, this is just an example, and dedicated hardware for implementing each function may be provided. The configuration shown in FIG. 4 is just an example, and the AP may include other configurations. 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.

[0029] The PCH communication control unit 401 establishes a single link with a 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 STA connected to the device that has acquired a transmission right on the PCH, or it acquires a transmission right on the PCH and transmits wireless frames to the STA. The NPCH communication control unit 402 communicates using NPCH access when the PCH is being used by another device and the AP cannot use that PCH. For example, when NAV is set on the PCH (e.g., due to use by an OBSS), the NPCH communication control unit 402 confirms that the SPCH is in an idle state and acquires a transmission right on the NPCH. Then, when the NPCH communication control unit 402 acquires a transmission right on the NPCH, it transmits wireless frames using one or more NPCHs, including the SPCH, without using the PCH. The NPCH communication control unit 402 also receives wireless frames transmitted by a STA connected to the device via NPCH access. The threshold notification unit 403 notifies the STA connected to the device of a threshold related to the length of the NAV used when determining whether or not to perform 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 perform NPCH access.

[0030] 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 may be implemented, for example, by the control unit 302 executing a program stored in the storage unit 301 of the STA. However, this is just an example, and dedicated hardware may be provided to implement each function. The configuration shown in FIG. 5 is just an example, and the STA may include configurations other than these. Furthermore, two or more functional blocks in FIG. 5 may be implemented as a single functional block, or one functional block may be divided into two or more functional blocks.

[0031] The PCH communication control unit 501 performs control similar to that of the PCH communication control unit 401 of the AP. That is, the PCH communication control unit 501 establishes a single link with the AP that collectively uses one or more channels including the PCH, and performs communication. For example, the PCH communication control unit 501 receives wireless frames from an AP connected to the device that has acquired a transmission right on the PCH, or it acquires a transmission right on the PCH and transmits wireless frames to the AP. The threshold receiving unit 502 receives from the AP a threshold related to the length of the NAV used to determine whether to perform NPCH access. The NPCH communication control unit 503 compares the threshold received by the threshold receiving unit 502 with the NAV length set in the PCH, and determines whether to perform NPCH access.

[0032] (Processing Flow) Next, an example of the processing flow executed by the communication devices (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 to execute NPCH access (S601). That is, the AP notifies the STA of information about the threshold value.

[0033] For example, 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, for example, an information element used to notify parameters for NPCH access. Here, this information element is referred to as a Non Primary Channel Access (NPCA) Parameter Set element; however, similar information elements with other names may be used as standardization progresses. In this information element, Element ID 701 stores a value indicating that this information element is an NPCA Parameter Set element. Length 702 stores a value indicating the length of this information element. Furthermore, NAV Threshold 703 stores information on the above-mentioned threshold. Note that this information element may also include other information. 7A, NAV Threshold 703 is located immediately after Length 702, but other information may be included between Length 702 and NAV Threshold 703. Although an example is shown in which the threshold is notified as part of the parameters for NPCH access, threshold information may be included in other information elements. The information elements of FIG. 7A may be included in, for example, a Beacon frame, which the AP may periodically transmit. The information elements of FIG. 7A 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 be included in a frame (e.g., an Association Response frame) transmitted and received during connection processing, or in an Action frame after connection is established.

[0034] Thereafter, when data to be transmitted occurs (YES in S602), the AP and STA determine whether a NAV due to OBSS communication is set on the PCH (S603). If a NAV due to OBSS communication is not set on the PCH (NO in S603), the AP and STA communicate using the PCH (S606). That is, the AP and STA perform carrier sense and acquire the right to transmit on the PCH (and NPCH) based on confirming that the PCH is in an idle state. Then, the AP and STA transmit data and receive acknowledgments (ACKs) during the period during which the right to transmit is acquired. On the other hand, if a NAV due to OBSS communication is set on the PCH (YES in S603), the AP and STA determine whether the remaining time exceeds the threshold shared in S601 (S604). If the remaining time does not exceed the threshold (NO in S604), the AP and STA wait until the NAV timer 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 NPCH access (S605). That is, if the AP and STA perform carrier sense on the SPCH and acquire a transmission right on 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 are unable to acquire a transmission right on the NPCH and the remaining NAV period on the PCH falls below the threshold, they may refrain from communicating using NPCH access. That is, the AP and STA may continue to perform the determination in S604 during the processing of S605. Note that communication using NPCH access may be performed 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.

[0035] Next, an example of communication control according to this embodiment will be described with reference to Figures 8A and 8B. In Figure 8A, the AP 111 or 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). The AP 101 or STA 102 then sets a NAV 802 to prevent signal transmission for the period specified by the RTS or CTS. That is, the AP 101 or STA 102 sets a 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 STA 102 has data to be transmitted, it determines whether to perform NPCH access because a NAV has been set in the PCH. At this time, the AP 101 and the STA 102 compare a threshold value 803 for the length of the NAV shared by the AP 101 and the STA 102 with the remaining time of the NAV in the PCH. If the AP 101 and the STA 102 confirm that the remaining time of the NAV in the PCH is longer than the threshold value 803, they decide to perform NPCH access. The AP 101 and the STA 102 then transmit data 805 on the NPCH after, for example, confirming that the SPCH is idle for a predetermined period 804. An SIFS (Short IFS) 806 follows the transmission of the data 805, followed by an acknowledgement (Block Ack (BA)) 807. Similarly, data communications 808 to 811 can be repeated until the expiration of the NAV 802. The AP 101 and the STA 102 can communicate as if the communication via the NPCH access had been completed when the NAV 802 expires. Furthermore, 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 upon expiration of the TXOP. That is, the AP 101 and the STA 102 may transmit and receive wireless frames so that the data communication is completed before the expiration of the NAV 802 or the TXOP.

[0036] In FIG. 8B , AP 111 or STA 112 confirms that the PCH is idle for a predetermined period 821 and transmits, for example, an RTS or CTS. AP 101 or STA 102 then sets NAV 822 accordingly. When data to be transmitted occurs, AP 101 and STA 102 compare the remaining time of the NAV at that time with a threshold 823, since the NAV is set in the PCH. This determines whether or not to perform NPCH access. In the example of FIG. 8B , because the remaining time of the NAV is shorter than threshold 823, AP 101 and STA 102 make a decision 824 not to perform NPCH access. Therefore, AP 101 and STA 102 wait until NAV 822 expires, and then transmit data 826 using the PCH in response to the PCH being idle for a predetermined period 825. If the NPCH is not in use at this time, the AP 101 and the STA 102 can use the NPCH in parallel to transmit data 827. That is, the AP 101 and the STA 102 can communicate using the PCH and one or more NPCHs in one link.

[0037] In this way, the AP notifies the STA of the threshold value of the remaining time of the NAV in the PCH, which is used to determine whether to perform NPCH access, thereby preventing NPCH access attempts even when there is not enough remaining time. Also, by using a common threshold value for multiple STAs, it becomes possible for the multiple STAs to fairly acquire the right to transmit via NPCH access.

[0038] Although the above description illustrates an example in which one threshold is notified, 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, by setting the first threshold lower than the second threshold, data requiring LL can be preferentially communicated via NPCH access when an OBSS-based NAV is set on the PCH. In this case, an information element, such as that shown in FIG. 7B, which is an extension of the information element shown in FIG. 7A, is transmitted from the AP to the STA. The information element in FIG. 7B includes an LL NAV Threshold 711 indicating a first threshold for data requiring LL and a Non-LL NAV Threshold 712 indicating a 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 a remaining time equal to or greater than the first threshold is set to PCH for data requiring LL. On the other hand, for data not requiring LL, even if the NAV of the OBSS with a remaining time equal to or greater than the first threshold 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 not requiring LL, the STA performs NPCH access when the NAV of the OBSS with a remaining time equal to or greater than the second threshold is set to PCH.

[0039] An example of communication control when multiple thresholds are used in this manner will be described using Figures 9A and 9B. Note that in the examples of Figures 9A and 9B, it is assumed that a NAV for OBSS communication is set in the PCH, as in the examples of Figures 8A and 8B. Figure 9A shows an example in which an AP and a STA detect the generation of data to be transmitted that requests an LL. In this case, the AP and the STA compare a first NAV threshold 901 to be used when transmitting data that requests an LL with the remaining NAV time. If the remaining NAV time is longer than the first threshold 901, the AP and the STA perform NPCH access to transmit data that requests an LL, and if they acquire a transmission right on the SPCH, they transmit data 902 that requests an LL. Figure 9B shows an example in which the AP and the STA detect the generation of data to be transmitted that does not request 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 in Figure 9A. Here, the second threshold 911 for data not requiring an LL is greater than the first threshold 901 for data requiring an 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 on the PCH expires. Then, when the AP and STA acquire a transmission right on the PCH after the NAV expires, they transmit data 912 (and 913) on the PCH and, if necessary, on the NPCH.

[0040] According to this 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, thereby shortening the time from data generation to transmission. On the other hand, for data that does not have strict latency requirements, since it does not need to be transmitted immediately, fair channel access among STAs can be achieved by setting a higher threshold value for data that does not have strict latency requirements compared to data that has strict latency requirements. Note that whether or not the latency requirement is strict may be determined based on, for example, the access category (AC) of the data. For example, data with ACs of voice (AC_VO) and video (AC_VI) may be determined to require LL, while data with ACs of background (AC_BK) or best effort (AC_BE) may be determined to not require LL. Alternatively, only AC_VO may be treated as data that requires LL, and other data may be treated as data that does not require LL. Furthermore, 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 determine whether the data to be transmitted requires LL by using information that associates a predefined AC or TID with a value indicating whether LL is required. Then, when transmitting the data, the AP and the STA can determine whether to perform NPCH access by using a threshold value according to the determination result.

[0041] Note that multiple threshold levels may be set according to the latency requirement level. For example, the first threshold for first data having the strictest latency requirement (minimum required delay) is set to the smallest value, and the second threshold for second data having the next strictest latency requirement is set to the next smallest value. Furthermore, the third threshold for third data having the next strictest latency requirement after the second data may be set to a value greater than the second threshold, and the threshold for data having the least strict latency requirement (e.g., no latency requirement) may be set to the largest value. That is, multiple threshold levels may be set so that the shorter the required delay, the smaller the threshold value. Furthermore, NPCH access may not be permitted for specific data (e.g., data having no latency requirement) as necessary.

[0042] Furthermore, multiple threshold levels may be set according to the access category. That is, separate thresholds may be set for AC_VO, AC_VI, AC_BK, and AC_BE. In this case, information elements such as those shown in FIG. 7C may be transmitted from the AP to the STA. Note that, instead of a threshold for each access category, a threshold for each TID may be notified. Furthermore, the threshold may be determined according to the expected data length for each category or TID, regardless of the required latency. That is, the threshold may be determined so that NPCH access is performed when communication via NPCH access is expected to be completed before the NAV expires in the PCH, regardless of the required latency. Furthermore, NPCH access may not be permitted for data of some access categories or TIDs. Note that, if NPCH access is not permitted regardless of the remaining time in the NAV, the thresholds notified in FIGS. 7A to 7C may be set to a predetermined value, such as "0" or the maximum representable value.

[0043] The threshold value may be set based on the time required to transmit and receive data. For example, as shown in FIG. 10 , when data is transmitted after an RTS and a CTS are transmitted, and a BA for that data is then transmitted, a threshold value 1001 may be set according to the time lengths of these frames. Here, the time length required for data communication is calculated by adding the sum 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. Here, since the time length of data is variable, the threshold value may be set to a value that exceeds at least the sum of the time lengths 1002 and 1003. That is, the threshold value is set to a value that exceeds the sum of 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. The threshold value may be set to a value obtained by adding a time length equivalent to the data length to this minimum value. Here, the time length corresponding to the data length can be set based on, for example, a statistically obtained standard amount of data. This prevents a threshold value that is shorter than the minimum required time from being set, thereby preventing NPCH access from continuing after the NAV expires in the PCH. Furthermore, it is possible to at least shorten the time during which NPCH access is performed after the NAV expires in the PCH.

[0044] Furthermore, for example, an AP can acquire the right to transmit by transmitting a CTS-self without transmitting an RTS. Therefore, a value exceeding the sum of the time length of the CTS, the time length of the BA (ACK), and twice the time length of the 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 an RTS or a CTS, or when transmission of other additional wireless frames is required, a minimum threshold may be determined based on the number of SIFS between the wireless frames to be actually transmitted. Note that, in any communication performed using the configuration 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 the RTS, the time length of the CTS, the time length of the BA (ACK), and three times the time length of the SIFS. Furthermore, when wireless frames are transmitted in various formats, such as when RTS / CTS is not transmitted or when additional frames are used, the minimum required time length may differ for each of those formats. In this case, the minimum value among the minimum time lengths corresponding to the plurality of formats may be notified as a threshold value as a reference value indicating the minimum required time length. That is, if the threshold value is X and the value indicating the minimum required time length is Y, "X-Y" may be notified from the AP to the STA as information indicating the threshold value.

[0045] 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.

[0046] With the above configuration, it is possible to prevent unnecessary continuation of NPCH access after the NAV due to OBSS communication in the PCH expires, and it is possible to use frequency resources more efficiently. Also, by providing a common threshold to STAs under the AP, it is possible to ensure fairness of channel access when NPCH access is performed. Furthermore, by using multiple thresholds, it is possible to perform control such as making NPCH access easier depending on the type of data, etc.

[0047] 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.

[0048] 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.

[0049] This application claims priority based on Japanese Patent Application No. 2023-179769, filed on October 18, 2023, the entire contents of which are incorporated herein by reference.

Claims

1. A communication device that performs communication in accordance with the IEEE 802.11 standard series, comprising: communication means for constructing a first network and communicating with other communication devices belonging to the first network 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 does not use the Primary channel when a period is set during which other communication devices do not transmit wireless frames using the Primary channel due to communication in a second network different from the first network, and uses one or more Non-Primary channels different from the Primary channel among multiple channels included in the link; and notification means for notifying the other communication devices of information indicating a threshold value related to the length of the period, at which the other communication devices are allowed to use the second channel access method when the length of the period set in the other communication devices exceeds the threshold value.

2. The communication device of claim 1, wherein 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.

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

4. 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. The communication device according to any one of claims 1 to 4, wherein the threshold value 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 an acknowledgment response, and three times the time length of a Short Interframe Space (SIFS).

6. A communication device as claimed in any one of claims 1 to 5, wherein a predetermined value is notified as the threshold value, thereby indicating that use of the second channel access method is not permitted regardless of the length of the period.

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

8. The communication device according to any one of claims 1 to 7, characterized in that the notification means 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, comprising: communication means that participates in a first network constructed by another communication device, and communicates with the other communication 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 does not use the primary channel when a period is set during which the communication device does not transmit wireless frames using the primary channel due to communication in a second network different from the first network, and that uses one or more non-primary channels different from the primary channel among multiple channels included in the link; receiving means that receives information indicating a threshold value related to the length of the period from the other communication device; and determining whether or not the remaining length of the period exceeds the threshold value when the period is set during which the communication device does not transmit wireless frames using the primary channel due to communication in the second network. and a control means for controlling communication with the other communication device using the second channel access method based on the determination that the remaining time of the period exceeds the threshold.

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. 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 assigned to a Traffic Identifier (TID) is permitted for each TID.

13. The communication device according to any one of claims 9 to 12, characterized in that the threshold value 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 an acknowledgment response, and three times the time length of a Short Interframe Space (SIFS).

14. A communication device as claimed in any one of claims 9 to 13, characterized in that a predetermined value is notified as the threshold, indicating that use of the second channel access method is not permitted regardless of the length of the remaining time of the period.

15. A communication device according to any one of claims 9 to 14, characterized in that the receiving means receives the information indicating the threshold value in a Beacon frame received from the other communication device.

16. The communication device according to any one of claims 9 to 14, wherein said receiving means receives said information indicating said threshold value in a Probe Response frame received from said other communication device.

17. A control method 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 belonging to the first network 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 does not use the primary channel when a period during which another communication device does not transmit wireless frames using the primary channel is set due to communication in a second network different from the first network, and that uses one or more non-primary channels different from the primary channel among multiple channels included in the link, the control method comprising notifying the other communication device of information indicating a threshold value related to the length of the period, the threshold value being a threshold value at which the other communication device is allowed to use the second channel access method when the length of the period set in the other communication device exceeds the threshold value.

18. A control method executed by a communication device that participates in a first network established by another communication device and communicates with the other communication device in accordance with the IEEE 802.11 standard series using either a first channel access method using at least a predetermined primary channel in one link, or a second channel access method not using the primary channel when a period during which the communication device does not transmit wireless frames using the primary channel due to communication in a second network different from the first network is set, and using one or more non-primary channels different from the primary channel among multiple channels included in the link, comprising: receiving information indicating a threshold value related to the length of the period from the other communication device; and, when the period during which the communication device does not transmit wireless frames using the primary channel due to communication in the second network is set, determining whether the remaining length of the period exceeds the threshold value; and 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 channel access method.

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

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