Communication device, communication device control method, and program

Abstract

This communication device sets an NAV in a primary channel when another communication device acquires a transmission opportunity in the primary channel. The communication device determines a backoff parameter of a secondary channel on the basis of at least a backoff counter which corresponds to a waiting time in the primary channel, attempts to acquire a transmission opportunity in the secondary channel by using the determined backoff parameter, and attempts to transmit data. When a waiting time corresponding to an AIFS period is included in a backoff parameter of the primary channel, the communication device determines a backoff parameter of the secondary channel on the basis also of the waiting time corresponding to the AIFS period.

Description

COMMUNICATION DEVICE, COMMUNICATION DEVICE CONTROL METHOD, AND PROGRAM

[0001] The present invention relates to a communication device that performs wireless communication, a control method for the communication device, and a program.

[0002] The Institute of Electrical and Electronics Engineers (IEEE) 802.11 standard is known as a communication standard for wireless local area networks (LANs). The IEEE 802.11be standard and its successor, the IEEE 802.11bn standard, are being considered to reduce communication latency and improve channel utilization efficiency.

[0003] As a candidate technology, a technology for improving channel utilization efficiency in a case where communication is performed using a communication link consisting of 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 is unavailable.

[0004] U.S. Patent Application Publication No. 11,696,353

[0005] An object of the present invention is to provide a technique for improving channel utilization efficiency in a communication system that uses a communication link made up of a plurality of channels. Means for resolving the issue

[0006] In order to achieve the above object, one aspect of the present invention provides a communication device, the communication device comprising: transmission control means for, when another communication device acquires a transmission opportunity on the primary channel through which data is to be transmitted, setting a NAV (Network Allocation Vector) corresponding to the transmission opportunity on the primary channel, determining back-off parameters for a secondary channel based at least on the back-off counter, which is the waiting time until starting data transmission on the primary channel, and which includes at least a back-off counter, which is a waiting time on the primary channel, and attempting to acquire a transmission opportunity on the secondary channel and transmit the data using the determined back-off parameters; and, when the back-off parameters for the primary channel include a waiting time equivalent to an Arbitration Inter Frame Space (AIFS) period, determining the back-off parameters for the secondary channel based also on the waiting time equivalent to the AIFS period.

[0007] According to one aspect of the present invention, it is possible to improve the channel utilization efficiency in a communication system that uses a communication link made up of a plurality of channels.

[0008] FIG. 1 is a diagram illustrating a configuration of a network system. FIG. 2 is a diagram illustrating a hardware configuration of a communication device. FIG. 3 is a schematic diagram illustrating an example of a channel access procedure. FIG. 4 is a schematic diagram illustrating an example of a functional module for channel access. FIG. 5 is a flowchart illustrating an example of channel access control in an STA. FIG. 6 is a flowchart illustrating an example of channel access control in an STA. FIG. 7 is a diagram illustrating an example of parameter update control when re-transitioning to the primary channel. FIG. 8 is a diagram illustrating an example of parameter update control when re-transitioning to the primary channel. FIG. 9 is a flowchart illustrating an example of shared control of secondary channel-related parameters in a second embodiment. FIG. 10 is a flowchart illustrating an example of shared control of secondary channel-related parameters in a third embodiment. FIG. 11 is a flowchart illustrating an example of shared control of secondary channel-related parameters in a third embodiment. FIG. 12 is a schematic diagram illustrating an example of a channel access procedure taking legacy STAs into consideration. FIG. 13 is a schematic diagram illustrating a modified example of a functional module.

[0009] 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.

[0010] 1 shows an example of the configuration of a network system according to this embodiment. The network system according to this embodiment includes one access point device (hereinafter simply referred to as an AP, AP STA, or access point) and two station devices (hereinafter simply referred to as STAs, Non-AP STAs, or stations).

[0011] The AP 101 and the STAs 102 and 103 are configured to be able to communicate wireless frames conforming to the IEEE802.11bn standard, which is the successor to the IEEE802.11be standard and targets a maximum transmission speed of 46.08 Gbps.

[0012] IEEE stands for Institute of Electrical and Electronics Engineers. IEEE 802.11bn, the successor standard to IEEE 802.11be, has high reliability, low latency, and improved throughput during congestion as its main features. Wireless frames communicated under this successor standard are also called UHR (Ultra High Reliability) PPDUs. PPDU stands for Physical Layer Protocol Data Unit.

[0013] The name UHR was chosen for convenience in light of the goals and key features of the successor standard, and may be a different name once the standard is fully developed. Similarly, the name IEEE 802.11bn may be a different name once the standard is fully developed. However, it should be noted that this specification and the appended claims are essentially applicable to all successor standards to the 802.11be standard.

[0014] 1 , the AP 101 is an access point that supports a multi-band function that provides networks using a plurality of different frequency channels. In this embodiment, the AP 101 is a dual-band access point that provides a 2.4 GHz band network and a 5 GHz band network, for example.

[0015] Furthermore, the AP 101 and the STA 102 of this embodiment can establish multiple communication links between the devices and perform multi-link communication. Hereinafter, the communication link will also be referred to simply as a link. The AP 101 that performs multi-link communication will also be referred to as an AP multi-link device (AP MLD) 101, and the STA 102 that performs multi-link communication will also be referred to as a non-AP MLD 102.

[0016] For example, AP 101 can establish a link in a 2.4 GHz band network with STA 102 and communicate with them. In parallel with this, AP 101 and STA 102 can also establish a link in the 5 GHz band and communicate with them. In this case, STA 102 performs multi-link communication, which communicates via multiple links.

[0017] 1 shows a network system consisting of one AP 101, STAs 102, and 103 as an example, but the number of STAs constituting the network system may be greater than that shown. Furthermore, while AP 101 and STAs 102-103 are described as supporting UHR PPDU communication (transmission and reception), they may also be configured to support PPDU communication of legacy standards that predate the UHR standard. Specifically, AP 101 and STA 102 may be configured to support PPDU transmission and reception of IEEE 802.11a / b / g / n / ac / ax / be standards, etc.

[0018] Furthermore, the frequency bands used by the AP 101 and the STAs 102-103 are not limited to the 2.4 GHz band and 5 GHz band described above. For example, different frequency bands such as the 6 GHz band, the Sub 1 GHz band, or the millimeter wave band may be used. Furthermore, the AP 101 and the STAs 102 can communicate using bandwidths such as 20 MHz, 40 MHz, 80 MHz, 160 MHz, 320 MHz, 540 MHz, and 640 MHz. The bandwidths used by each communication device are not limited to these.

[0019] The IEEE 802.11 series standard specifies a frequency channel using a bandwidth of 20 MHz as the minimum channel in frequency bands such as 2.4 GHz, 5 GHz, and 6 GHz. This standard also defines multiple available channels in each of the 2.4 GHz, 5 GHz, and 6 GHz frequency bands. This standard also specifies that a channel can be used in combination with adjacent channels.

[0020] In this embodiment, the use of a channel in combination with another adjacent channel may be referred to as channel bonding. Also, a bundle of channels formed by one or two or more adjacent channels may be referred to as a link. For example, one link formed by two channels with a bandwidth of 20 MHz uses a bandwidth of 40 MHz.

[0021] AP 101 establishes one or more links between devices to communicate data with STAs 102 and 103. For example, STA 102 executes a connection procedure with AP 101 to establish a link with AP 101. When the connection procedure between STA 102 and AP 101 is completed, a link is established between the devices. Establishing a link enables a communication device, such as an AP or STA, to access a wireless medium and communicate data, etc., with a partner communication device. For example, if a link using a 160 MHz bandwidth is established between devices, AP 101 and STA 102 communicate using all or some of the channels that make up that link. A link using a 160 MHz bandwidth can be configured by bundling eight channels with a 20 MHz bandwidth.

[0022] Before transmitting data, STAs such as AP 101 and STAs 102-103 perform carrier sensing to determine whether transmission is possible. For example, a communication device measures the strength of a signal received on a channel that the device intends to use for transmission (received signal strength), and if the received signal strength exceeds a predetermined threshold, determines that a signal is present on that channel. Furthermore, the communication device determines the transmission period during which the signal is to be transmitted based on information such as a Duration field included in the signal received on the channel. For example, the communication device stores the period indicated by the Duration field included in the received signal as a NAV (Network Allocation Vector) within the device. The communication device may treat the stored NAV as a period during which the device will not transmit. The operation of the communication device to set a period during which the device will not transmit based on information such as the Duration field of the received signal is also referred to as setting a NAV. If the communication device determines that a signal is present on the channel through carrier sensing, or if the set NAV period has not expired, the communication device may determine that transmission is not possible. In this case, the channel state 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. A communication device may determine that transmission is possible when the channel is idle. Note that, for example, when communicating using a 160 MHz bandwidth link, the communication device may determine whether transmission is possible using only the Primary Channel (PCH). The PCH is one of eight 20 MHz bandwidth channels that make up the 160 MHz bandwidth link, and may be notified to STA 102, for example, by a beacon frame periodically broadcast by AP 101. For example, if AP 101 or STAs 102 to 103 determine that transmission is possible as a result of performing carrier sensing on the PCH over a predetermined period, they may perform transmission using channel bonding using other channels included in the same link. For example, they may transmit a 160 MHz-wide PPDU.Furthermore, if a communication device determines that transmission is not possible as a result of carrier sensing on the PCH, the communication device may postpone transmission even if other channels included in the same link are idle. Note that each channel other than the PCH that constitutes a single link may be called a secondary channel (SCH). A secondary channel may also be called a non-primary channel (NPCH).

[0023] As described above, when a communication device such as the AP 101 or the STAs 102 and 103 receives a signal on a certain channel, the other device may transmit a signal on another channel (e.g., an adjacent channel) that is located at a frequency close to the received channel. In this case, the received signal may not be properly received. For example, assume that a communication device can simultaneously perform transmission and reception processes using different channels. When a communication device receives a signal on a certain channel and transmits on an adjacent channel, the power of the transmitted signal leaks into the channel of the received signal, causing interference with the received signal. Generally, the power of such a transmitted signal leak is much greater than the received power of the received signal, so the received signal is not properly received. To avoid this situation, the IEEE 802.11 series standards provide a PCH as a channel commonly used between communication devices to determine whether or not to transmit. In other words, while one communication device is transmitting on the PCH, the other communication device will not transmit, even if the other channel is idle. This can solve the above-mentioned problem of interference caused by power leakage between channels. However, when the PCH is busy, not using other idle channels (SCHs) reduces frequency utilization efficiency. For example, consider a case where another communication device (e.g., a STA or AP belonging to a different wireless network) transmits a frame using a 20 MHz-wide channel corresponding to the PCH of AP 101, STAs 102, and 103. In this case, even if the other seven SCHs are idle, AP 101 and STAs 102-103 determine that the channels are busy and are therefore unable to transmit using those SCHs. In this situation, even if STA 102 transmits to AP 101 using a specific idle SCH, AP 101 may be able to properly receive the signal transmitted by STA 102. Thus, for example, configuring a 20 MHz PCH to be used by another network so that the remaining 140 MHz of idle SCHs are not utilized impairs the efficient utilization of frequency resources.In this embodiment, when a PCH is being used by another communication device, a function is provided for performing communication between communication devices using an SCH (or NPCH) included in the same link as the PCH without using the PCH. As an example, when the AP 101 or the STAs 102 and 103 determine that the PCH is busy, they transition to a Secondary Primary Channel (SPCH) for determining whether or not transmission using the SCH (or NPCH) is possible.

[0024] If the AP 101 or the STAs 102 and 103 determine that the PCH is being used by another communication device, they subsequently determine whether transmission is possible on the SPCH, and if they determine that transmission is possible, they transmit using one or more SCHs including the SPCH. This channel access for transmitting using one or more channels including the SPCH without using the PCH can be called NPCH access (Non-Primary Channel Access). In NPCH access, the transmitting communication device attempts channel access on the SPCH channel and transmits a signal to the other communication device using one or more SCHs including the SPCH channel. Meanwhile, the receiving communication device waits for a signal transmitted from the other communication device using one or more SCHs including the SPCH channel and performs a reception process to receive it as needed. To perform NPCH access, the AP 101 and the STAs 102 to 103 share information regarding NPCH access (such as information identifying the SPCH) with the other communication device in advance. The information specifying the SPCH can be included in, for example, a Secondary Primary Channel Announcement Element of the Beacon frame. This Element can be configured with information indicating the Operating Class of the SPCH and information indicating the Channel. The Operating Class is an identifier that can uniquely identify a frequency band determined by the country or region in which the AP 101 is used. Furthermore, the Channel is an identifier that can uniquely identify each channel included in the frequency band specified by the Operating Class. Note that the AP 101 may indicate the position of the SPCH by storing in this Element the relative position of the SPCH on the frequency axis with respect to the PCH. For example, suppose that communication device 100 uses a link with a bandwidth of 160 MHz in the 6 GHz band and sets channel 1 in that band as the PCH (20 MHz bandwidth). Also, suppose that the SCHs (20 MHz bandwidth) are channels 5, 9, 13, 17, 21, 25, and 29, respectively. When communication device 100 sets channel 21 as the SPCH, it sets 20 as the information identifying the SPCH.That is, 20, which is the relative distance on the frequency axis from 1ch, which is the PCH, to 21ch, which is the SPCH, can be set as information for specifying the SPCH.

[0025] An example of the channel access operation in this embodiment will be specifically described below.

[0026] The AP 101 and the STAs 102 and 103 may also be configured to support wireless communication based on other communication standards, such as Bluetooth (registered trademark), NFC, or Bluetooth (registered trademark) Low Energy (LE). NFC stands for Near Field Communication. The AP 101 and the STAs 102 and 103 may also be configured to support wired communication using an Ethernet cable or wired communication using optical fiber. Specific examples of the AP 101 include, but are not limited to, a wireless LAN router or a personal computer (PC). The AP 101 and the STAs 102 and 103 may also be information processing devices, such as wireless chips that support the transmission and reception of UHR PPDUs. In this case, various controls may be performed by hardware circuits within the wireless chip. Various processes may also be performed by cooperation between a processor, memory, and hardware circuits, such as an ASIP, within the wireless chip. ASIP stands for Application-specific instruction set processor.

[0027] Specific examples of the STA 102 include, but are not limited to, cameras, tablets, smartphones, PCs, mobile phones, video cameras, and wearable devices such as smart glasses.

[0028] 2 shows an example of the hardware configuration of the communication device (AP 101, STAs 102 and 103). As an example of the hardware configuration, the communication device has a storage unit 201, a control unit 202, a function unit 203, an input unit 204, an output unit 205, a communication unit 206, and antennas 207 and 208.

[0029] The storage unit 201 is configured with ROM and / or RAM, and stores various information such as programs for performing various operations described below and communication parameters for wireless communication. RAM stands for Random Access Memory, and ROM stands for Read Only Memory. Note that the storage unit 201 may be a storage medium such as a non-volatile storage device, such as a hard disk or SSD (Solid State Drive), in addition to memories such as ROM and RAM.

[0030] The control unit 202 is configured with, for example, a processor such as a CPU or MPU, an ASIC (application-specific integrated circuit), a DSP (digital signal processor), an FPGA (field programmable gate array), etc. Here, CPU stands for Central Processing Unit, and MPU stands for Micro Processing Unit. The control unit 202 executes programs stored in the storage unit 201 and controls the entire device by operating hardware circuits such as the ASIC. Note that the control unit 202 may control the entire device in cooperation with the programs stored in the storage unit 201 and an OS (operating system).

[0031] The control unit 202 also controls the functional unit 203 to perform predetermined processes such as capturing images, printing, and projection. The functional unit 203 is hardware that enables the device to perform predetermined processes. For example, if the communication device is a camera such as a digital still camera or a smartphone equipped with a camera, the functional unit 203 is an imaging unit that captures images of the surroundings via a camera unit (not shown) included in the communication device. For example, if the communication device is a printer, the functional unit 203 is a printing unit that performs printing on a sheet such as paper based on print data obtained from the outside via wireless communication. For example, if the communication device is a projector or smart glasses, the functional unit 203 is a projection unit that performs projection of image data or video data obtained from the outside via wireless communication. In the case of smart glasses, the projection surface is the end user's retina, for example. The data processed by the functional unit 203 may be data stored in the storage unit 201 or data communicated with another AP or STA via the communication unit 206 (described later). Furthermore, a communication device such as AP 101 can also provide a network storage function such as NAS (Network Attached Storage). This function is provided to other communication devices as a web service such as a network storage service. For example, a communication device such as an STA connects to a network storage service provided by AP 101 using a protocol such as SMB, FTP, or WebDAV. The communication device such as an STA then uploads files to the storage service and downloads files from the storage. This upload and download data communication is also realized by communicating UHR PPDU between devices.

[0032] The input unit 204 receives various operations from the user. The output unit 205 outputs various types of information to the user. Here, the output by the output unit 205 includes, for example, at least one of display on a screen, audio output by a speaker, and vibration output. Note that both the input unit 204 and the output unit 205 may be implemented by a single module, such as a touch panel. The output unit 205 functions as a display means for presenting information to the user. The input unit also functions as a reception means for receiving user operations.

[0033] The communication unit 206 controls wireless communications conforming to the IEEE 802.11 series of standards and IP communications. In this embodiment, the communication unit 206 cooperates with the antennas 207 and 208 to execute communication control for transmitting and receiving UHR PPDUs, which are wireless frames conforming to the 802.11bn standard, and PPDUs conforming to earlier standards. The antennas 207 and 208 are antennas capable of transmitting and receiving signals in at least one of the frequency bands, for example, the sub-GHz band, the 2.4 GHz band, the 5 GHz band, the 6 GHz band, and the millimeter wave band. Note that, while a communication device equipped with two antennas is illustrated as an example in this embodiment, the present invention is not limited to this. The number of antennas may be three or more.

[0034] In addition, if the communication device is compatible with the aforementioned NFC standard, Bluetooth (registered trademark) standard, wired communication standard, etc., the communication unit 206 may be configured to control wireless communication or wired communication in accordance with these communication standards.

[0035] <Channel Access> Next, an example of a channel access procedure in this embodiment will be described with reference to Fig. 3. Fig. 3 is a schematic diagram showing an example of a channel access procedure in this embodiment.

[0036] At a timing before reference numeral 300, STA 102 and STA 103 attempt channel access on the PCH to transmit data. At this time, while the PCH is idle, STA 102 and STA 103 decrease their transmission wait times, including the AIFS and backoff counter determined based on a backoff algorithm. When the PCH idle transmission wait time reaches zero, STA 102 or STA 103 can begin data transmission. However, if a communication device in the OBSS wins channel access to the idle PCH first, the PCH becomes busy. This situation means that another communication device wins the transmission opportunity on the PCH where STA 102 or STA 103 plans to transmit data. Figure 3 illustrates a case where a communication device in the OBSS starts data transmission on the PCH first. More specifically, the dashed line indicated by reference numeral 300 represents the timing when a communication device in the OBSS starts data transmission on the PCH first. OBSS stands for Overlapping Basic Service Sets.

[0037] At the timing indicated by the reference numeral 300, the AP 101 and the STAs 102 to 103 switch the channel to be monitored for channel access to the SPCH described above and attempt to acquire a transmission opportunity on the secondary channel. At this time, the terminals within the BSS provided by the AP 101, such as the AP 101 and the STAs 102 to 103 of this embodiment, attempt channel access on the SPCH by utilizing the backoff parameters used on the PCH in the SPCH as well. Note that in this embodiment, in order to achieve data communication on the SPCH with a simple implementation, a restriction is imposed so that data communication on the SPCH is permitted only during periods when the PCH is busy. BSS stands for Basic Service Sets.

[0038] Reference numerals 301 and 302 indicate that the backoff parameters are also used for channel access on the SPCH, and illustrate a case where the transmission waiting time of STA 102 is shorter than the transmission waiting time of STA 103. Fig. 3 illustrates a case where STA 102, which has a shorter transmission waiting time, wins a transmission opportunity on the SPCH and transmits data.

[0039] The STA 102 that wins the transmission opportunity transmits a frame on one or more SCHs including the SPCH to the AP 101. Meanwhile, the STA 103 reduces the transmission waiting time while the SPCH is idle.

[0040] The dashed line indicated by the symbol 304 indicates the timing when the PCH transmission opportunity expires for the communication device in the OBSS. At this timing, the AP 101 and STAs 102 to 103 switch the channel monitored for channel access to the PCH. That is, the AP 101 and STAs 102 to 103 re-transition to the normal state where they perform channel access on the PCH. At this time, the communication device that was waiting to transmit on the SPCH attempts channel access on the PCH by utilizing the backoff counter used on the SPCH in the PCH as well. Symbol 303 illustrates the state of the backoff counter decremented by the STA 103 on the SPCH, and symbol 305 illustrates an example of utilizing that backoff counter on the PCH. FIG. 3 illustrates a case where STA 103, which did not win a transmission opportunity at the timing indicated by 300 and therefore did not win a transmission opportunity on the SPCH, successfully decrements its backoff counter and wins a transmission opportunity after the timing indicated by 304. The STA 103 that wins a transmission opportunity by channel access on the PCH transmits a frame to the AP 101 on one or more channels including the PCH.

[0041] Next, the functional configuration of the AP 101 and the STAs 102-103 will be described using Fig. 4. Fig. 4 is a schematic diagram illustrating an example of functional modules for channel access provided in the AP 101 and the STAs 102-103. Fig. 4 shows excerpts of functional modules that realize functions related to channel access. The data categorization unit 401 classifies data received from a higher layer into traffic categories that comply with the EDCA mechanism defined in the IEEE 802.11e standard. EDCA stands for Enhanced Distributed Channel Access.

[0042] The EDCA mechanism prioritizes data transmission by class so that certain types of traffic are given priority. Specifically, the categorization unit 401 classifies data into one of four access categories (ACs) defined by the EDCA mechanism. Typically, the four ACs are "AC_VO" for voice, "AC_VI" for video, "AC_BE" for best effort, and "AC_BG" for background data.

[0043] Next, the categorization unit 401 stores the categorized data (MAC frame) in a queue 402 corresponding to the categorized AC. The queue 402 is also called a traffic buffer. MAC frame is an abbreviation for Medium Access Control frame.

[0044] The channel access control unit 405 includes a CSMA / CA execution unit 403 and a backoff and collision control unit 404. The CSMA / CA execution unit 403 performs channel access control based on CSMA / CA for data held in the corresponding queue. CSMA / CA stands for Carrier Sense Multiple Access with Collision Avoidance.

[0045] When the CSMA / CA execution unit 403 detects that data has been stored in a corresponding queue, it reads out the EDCA parameters associated with the corresponding queue stored in the control unit 404. Based on the read-out EDCA parameters, the execution unit 403 then determines a transmission waiting time consisting of an AIFS and a backoff counter. Hereinafter, the transmission waiting time including the AIFS and the backoff counter is also simply referred to as the backoff parameter. The EDCA parameters are assigned in the order of VO, VI, VE, and BK so that wireless signal transmission is given a relative priority. Each EDCA parameter includes CWmin, CWmax, AIFS, and TXOPLimit. CWmin is the minimum value of the contention window (CW), which is the transmission waiting time, and CWmax is the maximum value of the CW. The shorter CWmin and CWmax are, the easier it is to obtain a transmission opportunity. AIFS (Arbitration Inter Frame Space) is the transmission interval of a radio signal. The smaller the AIFS, the easier it is to obtain a transmission opportunity. TXOPLimit is the upper limit of TXOP, which is the channel occupancy time. The larger the TXOPLimit, the more data can be transmitted in one obtained transmission opportunity.

[0046] Next, the execution unit 403 decrements the set backoff parameter while a condition, such as the channel state notified by the control unit 404 being an idle state, is satisfied, and waits for transmission until the waiting time reaches zero. The execution unit 403 stops decrementing the backoff parameter while a condition, such as the channel state notified by the control unit 404 being a busy state, is satisfied. Then, when the execution unit 403 determines that the waiting time has reached zero, it determines that a transmission opportunity has been won. Having determined that a transmission opportunity has been won, the execution unit 403 retrieves data (MAC frames) from the queue and, in cooperation with the control unit 404, the communication unit 206, and the antenna 207, transmits a UHR PPDU including the retrieved MAC frame to another communication device. When a communication device attempts to acquire a transmission opportunity on the PCH and acquires a transmission opportunity, it transmits the UHR PPDU on one or more channels including the PCH. Furthermore, when a communication device attempts to acquire a transmission opportunity on the SPCH and acquires a transmission opportunity, it transmits the UHR PPDU on one or more channels including the SPCH.

[0047] The control unit 404 also performs arbitration when there is an internal collision between the execution units 403 when acquiring a transmission opportunity. When execution units 403 corresponding to different ACs simultaneously win a transmission opportunity and request transmission, the control unit 404 performs control to prioritize data stored in a queue with a higher priority. For example, when an execution unit corresponding to a VO queue and an execution unit corresponding to a BK queue simultaneously acquire a transmission opportunity, the control unit 404 transmits the data stored in the VO queue with priority. In this case, the control unit 404 notifies the execution unit corresponding to the BK queue that a collision has occurred, and increases the CW managed by the execution unit corresponding to the BK queue.

[0048] The control unit 404 controls notifying the execution unit 403 of changes in channel conditions, and controls transition notifications indicating that the channel for which channel access is attempted has transitioned to the SPCH and re-transition notifications indicating that the channel has re-transitioned to the PCH. Upon receiving the transition notification or re-transition notification, the execution unit 403 updates the back-off parameters as necessary. The back-off parameter update process will be described later.

[0049] <Communication Control> Next, communication control using the channel access procedure of this embodiment will be described with reference to the flowcharts of Figures 5 and 6 and the tables of Figures 7A and 7B. The tables of Figures 7A and 7B are diagrams for explaining parameter setting control during re-transition.

[0050] Each process shown in the flowcharts of Figures 5 and 6 is performed by the processor of the control unit 202 of STA102-STA103 executing a computer program stored in the storage unit 201. Note that some processes, such as transmission and modulation, are realized by the processor of the control unit 202 in cooperation with the various processors, ASICs, DSPs, FPGAs, etc. that make up the communication unit 206, as well as the ASICs, DSPs, FPGAs, etc. that make up the antenna and control unit 202. Note that this is not limited to this, and it is of course also possible to configure the control unit, such as an ASIC or processor, inside the communication unit 206 to cooperate with the antenna to perform each process shown in the flowchart. Note that when it is desired to clearly indicate the subject of the process, the functional unit described in Figure 4 will be used as the subject in the description.

[0051] 5 and 6 are flowcharts showing an excerpt of the control of data transmission that is closely related to this embodiment.

[0052] In S501, the execution unit 403 determines whether transmission data (MAC frame) has been stored in the corresponding transmission queue. If it is determined that transmission data has been stored, the process proceeds to S502. If it is determined that transmission data has not been stored, the process waits for the transmission data to be stored. Note that the storage of data in the transmission queue is performed appropriately by an upper layer (not shown). For example, when a video distribution application or the like starts video distribution, data corresponding to video data obtained from a camera provided in an STA such as STA102 or STA103 is categorized as VI by the categorization unit 401 and stored in the VI queue. Furthermore, when audio data is transmitted using a VoIP (Voice over Internet Protocol) application or the like, the data corresponding to the audio data is categorized as VO by the categorization unit 401 and stored in the VO queue. The determination process of S501 is performed in parallel by the execution units 403 corresponding to each queue.

[0053] In S502, the execution unit 403, which has determined in S501 that transmission data has been stored, acquires EDCA parameters corresponding to the access category of the queue associated with the execution unit from the control unit 404. Subsequently, the execution unit 403 determines backoff parameters consisting of the AIFS and a backoff value indicated by the backoff counter based on the acquired EDCA parameters, and sets the determined backoff parameters. Once the setting is complete, the process proceeds to S503. The backoff counter is determined so as to have randomness within the range of the current contention window size (CWsize) and aCWmin corresponding to the access category. aCWmin stands for adaptive contention window minimum. The initial value of CWsize (i.e., the CWsize used when no collision occurs) is aCWmin. The CWsize is doubled each time a collision occurs. In other words, in an environment where collisions frequently occur, the range of candidates for random backoff is widened, and the occurrence of collisions is suppressed. That is, the execution unit 403 calculates a backoff counter to be used by calculating a random number within the range of aCWmin corresponding to the access category, which is a set of EDCA parameters, and the current contention window size (CWsize).

[0054] In S503, execution unit 403 executes a wait process for a transmission waiting time corresponding to an AIFS or a decrement process of the back-off counter, on condition that the channel state notified from control unit 404 is an idle state. First, a wait process for a transmission waiting time corresponding to an AIFS is executed, and when the transmission waiting time corresponding to an AIFS becomes zero, a decrement process of the back-off counter is executed.

[0055] In S504, the execution unit 403 determines whether the backoff counter has reached 0. If it is determined that the backoff counter has reached 0, the process proceeds to S508, and if it is not determined that the backoff counter has reached 0 (i.e., if the backoff counter is 1 or greater), the process proceeds to S505.

[0056] In S505, the control unit 404 determines whether another terminal (another communication device) has acquired a transmission opportunity. The control unit 404, in cooperation with each unit, performs carrier sense on the PCH. When the PCH changes from an idle state to a busy state, the control unit 404 analyzes the signal received on the PCH and attempts to analyze the PPDU preamble. If the control unit 404 analyzes the preamble and determines that another communication device has acquired a transmission opportunity, it proceeds to S506. On the other hand, if the PCH is still in an idle state and it is determined that another communication device has not acquired a transmission opportunity, it proceeds to S503. Note that, although not shown in FIG. 5, if the control unit 202 of STA102 or STA103 analyzes the preamble and determines that the received PPDU is a PPDU addressed to itself, it appropriately controls the reception of the PPDU.

[0057] In S506, the control unit 404 sets PCH_NAV, which indicates a period during which the device itself will not transmit on the PCH, based on information such as the Duration field of the PPDU received in S505. Subsequently, the control unit 404 notifies the execution unit 403 of a transition notification indicating transition to the SPCH. Having received the transition notification, the execution unit 403 temporarily stores the current back-off parameters, which indicate the transmission waiting time managed to acquire a transmission opportunity on the PCH, as back-off parameters before the SPCH transition. The back-off parameters before the transition are used as appropriate when controlling re-transition, which will be described later.

[0058] In S507, the control unit 202 executes transmission control in the SPCH, which will be described later with reference to FIG.

[0059] When the execution unit 403 determines that the backoff counter has reached zero, it requests the control unit 404 to transmit the data stored in the corresponding queue in S508. Upon receiving the request, the control unit 404 cooperates with the other units to transmit data in UHR PPDU format on one or more channels including at least the PCH.

[0060] In S509, the control unit 404 determines whether a collision has occurred due to the execution of data transmission. If it is determined that a collision has occurred due to the execution of data transmission, the process proceeds to S511. If it is determined that a collision has not occurred, the process proceeds to S510.

[0061] In S511, the control unit 404 notifies the execution unit 403, which requested the transmission of the data that was the subject of the collision, of the occurrence of a collision. Upon receiving the notification of the occurrence of a collision, the execution unit 403 increases the CWsize. Specifically, the execution unit 403 changes the CWsize to twice the current size.

[0062] In S510, the control unit 404 notifies the execution unit that requested the data transmission of the success of the data transmission. Upon receiving the notification of the success of the data transmission, the execution unit 403 initializes CWsize to aCWmin.

[0063] In S512, the control unit 202 determines whether to turn off the power. If it determines that a user operation to turn off the power has been received, a shutdown process (not shown) is performed, and the series of transmission control operations is terminated. If it determines that a user operation to turn off the power has not been received, the process proceeds to S501, and further control of data transmission is attempted.

[0064] Next, transmission control in the SPCH will be described with reference to Fig. 6. The process in Fig. 6 is executed when the execution unit 403 receives a transition notification indicating transition to the SPCH.

[0065] In S601, the execution unit 403 determines the backoff parameters to be used in the SPCH. These parameters can be set based on the backoff parameters used in the PCH temporarily stored in S506 and a specific waiting time. The specific waiting time can be, for example, a Short Inter Frame Space (SIFS) period or an AIFS period equivalent to one slot. Specifically, the backoff parameters to be used in the SPCH can be determined by adding a specific waiting time to the backoff parameters used in the PCH. If the backoff parameters used in the primary channel exceed a predetermined waiting time, the specific waiting time may not be added. If a STA, such as STA102 or STA103, that has transitioned to the SPCH transmits one frame and then attempts to transmit another frame on the SPCH, the backoff parameters can be determined using the determination method described in S502. That is, when attempting to acquire a second or subsequent transmission opportunity on the SPCH, the backoff parameters are determined based on the EDCA parameters used on the PCH.

[0066] In S602, the execution unit 403 executes a wait process for a transmission waiting time corresponding to AIFS, SIFS, etc. or a decrement process of a back-off counter, on the condition that the channel state of the SPCH notified from the control unit 404 is an idle state. First, the execution unit 403 executes a wait process for a transmission waiting time corresponding to a predetermined waiting time such as AFIS, SIFS, etc., among the back-off parameters. When the transmission waiting time corresponding to the predetermined waiting time such as AFIS, SIFS, etc., becomes zero, the execution unit 403 executes a decrement process of the back-off counter among the back-off parameters.

[0067] In S603, the execution unit 403 determines whether the backoff counter has reached 0. If it is determined that the backoff counter has reached 0, the process proceeds to S606, and if it is not determined that the backoff counter has reached 0 (i.e., if the backoff counter is 1 or greater), the process proceeds to S604.

[0068] In S604, the control unit 404 determines whether another terminal (another communication device) has acquired a transmission opportunity on the SPCH. The control unit 404, in cooperation with each unit, performs carrier sense on the SPCH. When the SPCH changes from an idle state to a busy state, the control unit 404 analyzes the signal received on the SPCH and attempts to analyze the PPDU preamble. If the control unit 404 analyzes the preamble and determines that another communication device has acquired a transmission opportunity, the process proceeds to S605. On the other hand, if the SPCH is still in the idle state and it is determined that another communication device has not acquired a transmission opportunity, the process proceeds to S602. Note that, although not shown in FIG. 6 , if the control unit 202 of STA 102 or STA 103 analyzes the preamble and determines that the received PPDU is a PPDU addressed to itself, it appropriately controls the reception of the PPDU.

[0069] In S605, the control unit 404 sets SPCH_NAV, which indicates a period during which the device itself will not transmit on the SPCH, based on information such as the Duration field of the PPDU received in S604. The control unit 404 then notifies the execution unit 403 that the channel state of the SPCH is Busy. The execution unit 403 suspends the process of decrementing the back-off parameter for the SPCH while the notified channel state of the SPCH is Busy.

[0070] Next, the execution unit 403, which has determined that the backoff counter has reached zero, requests the control unit 404 to transmit the data stored in the corresponding queue in S506. The control unit 404, which has received the request, cooperates with the other units to transmit data in UHR PPDU format on at least one channel that does not include the PCH but does include the SPCH.

[0071] In S507, the control unit 404 determines whether a collision has occurred due to the execution of data transmission. If it is determined that a collision has occurred due to the execution of data transmission, the process proceeds to S609. If it is determined that a collision has not occurred, the process proceeds to S608.

[0072] In S609, the control unit 404 notifies the execution unit 403, which requested transmission of the data that was the subject of the collision, of the occurrence of a collision. Upon receiving the notification of the occurrence of a collision, the execution unit 403 increases the CWsize. Specifically, the execution unit 403 changes the CWsize to twice the current size.

[0073] On the other hand, in S608, the control unit 404 notifies the execution unit that requested the data transmission of the success of the data transmission. Upon receiving the notification of the success of the data transmission, the execution unit 403 initializes CWsize to aCWmin.

[0074] In S610, the control unit 404 determines whether to continue transmission control in the SPCH. Specifically, if the control unit 404 determines that the PCH_NAV period set in S506 has expired, it determines not to continue transmission control in the SPCH and proceeds to S611. On the other hand, if the control unit 404 determines that the PCH_NAV period set in S507 has not expired, it determines not to continue transmission control in the SPCH and proceeds to S601.

[0075] In S611, the control unit 404 notifies the execution unit 403 of re-transition to the PCH. Upon receiving the re-transition notification, the execution unit 403 performs selection control of back-off parameters including an AIFS and a back-off counter to be used when re-transition to the PCH. The back-off parameters including the selected AIFS and back-off counter are used for channel access after re-transition to the PCH. Upon completion of the selection control, the control unit 404 proceeds to S503. Note that if the execution unit 403 has not performed a back-off procedure (i.e., if data to be transmitted is not stored), the selection control is omitted. If the selection control is omitted, the execution unit 403 transitions to the standby control for transmission data described in S501.

[0076] The processes of S610 and S611 can be said to be a control for terminating the control for attempting to acquire a transmission opportunity on the secondary channel before the NAV period set on the primary channel elapses.

[0077] A specific example of selection control will be described with reference to Figures 7A and 7B. Figure 7A is a table for explaining parameter setting control when re-transitioning to the PCH in this embodiment.

[0078] The control unit 404 and the execution unit 403 perform different parameter setting control depending on whether or not a STA has successfully transmitted data at least once on the SPCH. If the STA has successfully transmitted data at least once on the SPCH, the control unit 404 transitions to a mode that uses unfavorable contention parameters for a certain period of time. A STA that transitions to this mode can be configured to determine backoff parameters indicating a transmission waiting time based on the notified MU EDCA parameters during the MU_EDCA Timer period notified by the AP 101. The MU_EDCA Timer and MU EDCA parameters are parameters defined by the IEEE 802.11ax standard and are included in beacon frames, etc., transmitted by the AP 101. These parameters are provided to force terminals that have successfully transmitted data in uplink MU transmissions to use unfavorable contention parameters for a certain period of time. In this embodiment, STAs that have successfully transmitted data on the SPCH also use these parameters to determine backoff parameters. This control makes it possible to maintain fairness with other communication terminals that were not successful in transmission.

[0079] On the other hand, if the terminal itself does not succeed in transmitting data on the SPCH, the execution unit 403 compares the backoff parameters used on the PCH before the SPCH transition stored in S406 with the backoff parameters used when resuming from the SPCH to the PCH. The execution unit 403 then selects the backoff parameter with the shorter waiting time as the backoff parameter to be used after re-transitioning to the PCH. That is, if the backoff parameters can be decremented smoothly on the SPCH, the backoff parameters can be carried over to the PCH. On the other hand, if the backoff parameters on the SPCH are set to a large value, such as when a collision occurs on the SPCH, the value is not carried over, and channel access on the PCH can be resumed using the backoff parameters used previously on the PCH. This control increases the likelihood of a transmission opportunity being provided to a terminal that is unable to obtain a transmission opportunity on the PCH and, furthermore, unable to obtain a transmission opportunity on the SPCH and re-transitioning to the PCH.

[0080] Second Embodiment In the first embodiment, a case was illustrated in which, when a STA that has successfully transmitted on an SPCH attempts to acquire a new transmission opportunity, backoff parameters are determined based on an EDCA parameter set for the PCH. In the second embodiment, in addition to the information that identifies the SPCH shared in the first embodiment, EDCA parameters for the SPCH are newly shared between the AP and the STA, and a case in which these parameters are used will be described with reference to Figures 8A and 8B.

[0081] FIG. 8A shows parameter notification control performed by the AP 101, and FIG. 8B shows parameter update control performed by the STAs 102-103. Each process shown in the flowchart of FIG. 8A is performed by the processor of the control unit 202 of the AP 101 executing a computer program stored in the storage unit 201. Each process shown in the flowchart of FIG. 8B is performed by the processor of the control unit 202 of the STAs 102-103 executing a computer program stored in the storage unit 201. In either communication device, some of the processing, such as transmission and modulation, is realized by the processor of the control unit 202 in cooperation with various processors, ASICs, DSPs, FPGAs, and antennas constituting the communication unit 206. Some of the processing may also be realized in cooperation with the ASICs, DSPs, FPGAs, etc. constituting the control unit 202. However, without being limited to this, it is of course also possible for each communication device to be configured so that the control unit, such as an ASIC or processor within the communication unit 206, cooperates with the antenna to execute each of the processing shown in the flowchart. When it is desired to clearly indicate the subject of processing, the functional units described with reference to FIG. 4 will be used as the subject.

[0082] 8A and 8B are flowcharts illustrating the parameter communication control in this embodiment. In step S801, the control unit 202 of the AP 101 cooperates with the other units to periodically transmit a beacon including an SPCH EDCA Parameter Set Element containing EDCA parameters to be used in the SPCH. The control unit 202 also includes a Secondary Primary Channel Announcement Element, which identifies the SPCH, in the periodically transmitted beacon. The AP 101 can select any of the parameters it desires to use as appropriate. For example, the AP 101 can appropriately reselect the SPCH or the parameters to be used in the SPCH based on the congestion level, etc. Furthermore, the AP 101 may provide a detailed operation setting screen to the user and store the settings made via the operation setting screen as operation settings. In this case, the AP 101 selects the channel number to be used for the SPCH and the parameters to be used for the SPCH based on the operation settings changed by the user via the operation setting screen. The operation setting screen can be configured to allow the channel number of the SPCH and parameters such as CWmin, CWmax, AIFS, and TXOPLimit to be set for each AC.

[0083] Meanwhile, in S811, the control unit 202 of each of the STAs 102 and 103 cooperates with each other to acquire the values ​​of the above elements based on the Beacon frame received from the AP 101. Then, based on the acquired values, the control unit 202 sets the SPCH to which the STA should transition and the EDCA parameter set to be used for the SPCH.

[0084] In addition, STAs such as STA102 and STA103 may attempt to transmit another frame on the SPCH after transmitting a frame at one transmission opportunity in S602. In this case, the STA may modify the process so that it determines the backoff parameters using the EDCA parameters for the SPCH updated in S811.

[0085] <Third Embodiment> In the first and second embodiments, control when all STAs connected to the AP 101 support data transmission via the SPCH is exemplified. In the third embodiment, control when the STAs connected to the AP 101 include legacy STAs that do not support data transmission via the SPCH will be described with reference to Figures 7B to 10. In this embodiment, a legacy STA refers to an STA that supports one or more of the IEEE 802.11a / b / g / n / ac / ax / be standards but does not support the IEEE 802.11bn standard.

[0086] The AP 101 determines parameters to be adjusted so that terminals that have transitioned to the SPCH do not have too much of an advantage, based on the number of legacy STAs, and notifies the STAs of the determined parameters. STAs that support data transmission via the SPCH use the notified parameters to select and control backoff parameters when re-transitioning to the PCH.

[0087] Specific explanations will be given using Figures 9A and 9B. Each process shown in the flowchart of Figure 9A is executed by the processor of the control unit 202 of the AP 101 executing a computer program stored in the storage unit 201. Also, each process shown in the flowchart of Figure 9B is executed by the processor of the control unit 202 of the STAs 102-103 executing a computer program stored in the storage unit 201. In either communication device, some processes such as transmission and modulation are realized by the processor of the control unit 202 in cooperation with the various processors, ASICs, DSPs, FPGAs, and antennas constituting the communication unit 206. Some processes may also be realized in cooperation with the ASICs, DSPs, FPGAs, etc. constituting the control unit 202. Of course, this is not limited to this, and each communication device can also be configured so that the control unit, such as an ASIC or processor within the communication unit 206, cooperates with the antenna to execute each process shown in the flowchart. When it is desired to clearly indicate the subject of a process, the functional unit described in Figure 4 will be used as the subject.

[0088] In S901, the control unit 202 of the AP 101 determines whether a legacy STA is connected to the AP 101. If it is determined that the legacy STA is connected, the process proceeds to S902, and if it is determined that the legacy STA is not connected, the process proceeds to S904.

[0089] In S904, the control unit 202 performs the same notification control as that described in S802.

[0090] Meanwhile, in S902, the control unit 202 determines a value to be included in the PCH contention access resume parameter set element based on at least the number of legacy STAs. This value indicates an additional waiting time to be added to the backoff parameter when a STA that has transitioned to the SPCH re-transitions to the PCH.

[0091] In S903, the control unit 202 transmits a Beacon including a PCH contention access resume parameter set element that stores the value determined in S903 in addition to the element described in S801.

[0092] Meanwhile, in S911, the control unit 202 of the STAs 102-103 cooperates with each other to acquire the values ​​of the above elements based on the Beacon frame received from the AP 101. Then, the control unit 404 sets the SPCH to which the STA should transition and the EDCA parameter set to be used for the SPCH based on the values ​​acquired by the control unit 202. Furthermore, if the received Beacon frame includes a PCH contention access resume Parameter set Element, the control unit 202 also acquires the value of that element. Then, the control unit 404 stores or updates the parameters to be used when resuming PCH contention access based on the acquired values.

[0093] In this embodiment, the STAs such as STAs 102 to 102 perform the selection control shown in FIG. 7B instead of the selection control in S511 described with reference to FIG. 7A.

[0094] The selection control of STAs that have successfully transmitted on the SPCH is performed in the same manner as in the case described with reference to Fig. 7A. In this embodiment, STAs that have never successfully transmitted on the SPCH are controlled to select transmission parameters to which a delay that takes legacy STAs into consideration has been added. This delay is derived based on the value of the PCH contention access resume parameter set element in the beacon frame described above.

[0095] Control when data transmission on the SPCH is unsuccessful will be specifically described. In this case, the execution unit 403 compares the backoff parameters used in the PCH before the SPCH transition stored in S406 with the parameters obtained by converting the delay into the backoff parameters when resuming from the SPCH to the PCH. The backoff parameters with the shorter waiting time are then selected as the backoff parameters to be used after re-transition to the PCH. That is, in cases where the backoff parameters were successfully decremented on the SPCH and the transmission waiting time is shorter than before the transition even when a delay taking legacy STAs into consideration is added, the parameters with the delay added can be carried over to the PCH.

[0096] This control allows for some preferential treatment of STAs that attempted to transmit by transitioning the SPCH but were unable to do so, while preventing legacy STAs from being put at an excessive disadvantage. Figure 10 is a schematic diagram of transmission control in the third embodiment. The following description focuses on STA 103. As an example, a case is illustrated in which a delay of 3 slots is specified as the value of the SPCH contention access resume parameter set element.

[0097] At timing 300, STA 103, which has a transmission wait time of 9 slots, attempts transmission on the SPCH. As a result, the wait time can be decremented to the remaining transmission wait time of 3 slots. Then, at timing 1005 when STA 103 transitions back to the PCH, a delay of 3 slots is added, and channel access on the PCH is resumed after a transmission wait time of 6 slots.

[0098] In this case, the legacy STA that has been setting its NAV on the PCH with five slots of transmission waiting time remaining at the timing indicated by reference numeral 300 will resume channel access on the PCH after the five slots of transmission waiting time. In this way, by AP 101 appropriately setting adjustment parameters and having terminals that support the SPCH use those adjustment parameters, even legacy STAs can obtain transmission opportunities fairly to a certain extent.

[0099] <Modification> In the above-described embodiment, it is assumed that the SPCH is one channel. However, the present technology is not limited to this, and it is also possible to define a plurality of SPCHs and perform channel access substantially in parallel using the plurality of SPCHs.

[0100] A functional module for realizing this modified example will be described with reference to Fig. 11. Fig. 11 shows a modified functional module. The difference from the functional module of the first embodiment described in Fig. 4 is that it includes a plurality of channel access control units. In this embodiment, one PCH access control unit 701 for the PCH and a plurality of SPCH access control units 711 for the SPCHs are provided. Fig. 11 illustrates a case where a communication device such as an STA or an AP includes N SPCH access control units 711, 711-1 to 711-n.

[0101] The PCH access control unit 701 has a PCH control unit 704 that controls collisions and backoff control in the PCH and communication, and a plurality of CSMA / CA execution units 703 connected to the queue. The SPCH access control unit 711 has an SPCH control unit 714 that controls collisions and backoff control in the SCH and communication, and a plurality of CSMA / CA execution units 713 connected to the queue.

[0102] The PCH control unit 704 and each SPCH control unit 714 are connected to each other so that they can communicate with each other, and perform a back-off parameter sharing process when transitioning to an SPCH or when re-transitioning to a PCH.

[0103] First, the PCH control unit 704 of the STA that has determined to transition from the PCH to the SPCH acquires the back-off parameters used by the execution unit 703 to secure a transmission opportunity on the PCH and transmits the back-off parameters and a transition notification to the SPCH control unit. Each SPCH control unit 714 that receives the back-off parameters and the transition notification transmits the back-off parameters and the transition notification to its own CSMA / CA execution unit 713. Each execution unit 713 that receives the transition notification determines back-off parameters for the SPCH based on the received back-off parameters and attempts channel access on its own CH. Since the control of channel access on each SCH after the determination is the same as in the above-described embodiment, a description thereof will be omitted. When the back-off counter of each execution unit 713 reaches zero and a transmission opportunity is successfully secured, the execution unit 713 cooperates with the connected control unit 714 to execute transmission processing for the UHR PPDU containing the data stored in the corresponding queue. The SPCH control unit 714 also notifies the other SPCH control units 714 and the PCH control unit 704 that a transmission opportunity has been secured. Upon receiving this notification, the other SPCH control units 714 request the execution units 713 connected to the queue corresponding to the access category currently being transmitted to stop the backoff procedure. Upon receiving this notification, the execution units 713 stop the backoff procedure. Note that the execution units 713 provided for access categories different from the data of the access category currently being transmitted continue channel access.

[0104] Next, the control when re-transitioning to the PCH will be described. When the PCH control unit 704 determines to perform re-transition, it transmits a re-transition notification to each SPCH control unit 714. Each SPCH control unit 714 that has received the re-transition notification transmits to the PCH control unit 704 the back-off parameters (current back-off parameters) to be used when resuming from the SPCH to the PCH. The PCH control unit 704 compares the multiple back-off parameters received from each SPCH control unit 714 with the back-off parameters for the PCH that it stores, and selects the one with the shortest transmission waiting time. At this time, a delay may be added that takes into account the legacy STA described in the third embodiment.

[0105] <Other Embodiment 1> In the above-described embodiment, it is assumed that the backoff parameters used in the SPCH are carried over to the PCH when resuming from the SPCH to the PCH, but this is not limited to this. To simplify the process, when resuming from the SPCH to the PCH, the contention parameters may be recalculated based on the EDCA parameters of the PCH, and the recalculated contention parameters may be used for channel access of the PCH. Furthermore, in the above-described embodiment, the channel for determining whether or not to transmit using the SCH (or NPCH) when it is determined that the PCH is busy is called the SPCH, but this is not limited to this. It may also be called a Primary Secondary Channel (PSCH) to mean the second or subsequent channel among the primary channels.

[0106] In the above embodiment, the STA 102, STA 103, etc. attempt to transmit data to the AP using the SPCH access procedure, but the present invention is not limited to this. It is also possible for the AP 101 to perform the above-mentioned SPCH access procedure and attempt to transmit data to the STA.

[0107] Other Embodiment 2 The disclosure of this embodiment also includes the following configuration.

[0108] (Configuration 1) A communication device includes transmission control means for, when another communication device acquires a transmission opportunity on the primary channel that is scheduled to transmit data, while a back-off parameter of the primary channel, which includes at least a back-off counter and which is a waiting time until starting data transmission on the primary channel, is not zero, setting a NAV (Network Allocation Vector) corresponding to the transmission opportunity on the primary channel, determining back-off parameters of a secondary channel based at least on the back-off counter, which is the waiting time on the primary channel, and attempting to acquire a transmission opportunity on the secondary channel and transmit the data using the determined back-off parameters, wherein, when a waiting time equivalent to an Arbitration Inter Frame Space (AIFS) period is included in the back-off parameters of the primary channel, the communication device is characterized in that the transmission control means determines the back-off parameters of the secondary channel also based on the waiting time equivalent to the AIFS period.

[0109] (Configuration 2) The communication device according to Configuration 1, wherein the communication device is a station device and further comprises: a storage means for storing an EDCA (Enhanced distributed channel access) parameter set used for data transmission; and a calculation means for calculating a back-off counter, which is a waiting time until starting data transmission, based at least on the EDCA parameter set.

[0110] (Configuration 3) The communication device according to Configuration 2, further comprising: a receiving means for receiving an EDCA parameter set from an access point device; and an updating means for updating the EDCA parameter set stored in the storage means based on the EDCA parameter set received by the receiving means.

[0111] (Configuration 4) The communication device according to any one of configurations 1 and 2, wherein the communication device is an access point device, the transmission control means periodically attempts to transmit a beacon frame on the primary channel, and the beacon frame transmitted by the access point device includes at least information specifying a secondary channel and / or an EDCA parameter set.

[0112] (Configuration 5) The communication device according to any one of Configurations 1 to 4, wherein the transmission control means terminates control of attempting to acquire a transmission opportunity on the secondary channel before the period of the NAV set for the primary channel elapses, and performs control of attempting to acquire a transmission opportunity on the primary channel.

[0113] (Configuration 6) The communication device according to Configuration 5, wherein when control of attempting to acquire a transmission opportunity in the secondary channel is terminated and control of attempting to acquire a transmission opportunity in the primary channel by re-transitioning to the primary channel is performed, the transmission control means sets the contention parameter of the secondary channel as the contention parameter to be used after re-transitioning to the primary channel.

[0114] (Configuration 7) The communication device according to Configuration 6, wherein the transmission control means sets the back-off parameters of the secondary channel as back-off parameters to be used after re-transitioning to the primary channel when the waiting time corresponding to the contention parameters of the secondary channel is shorter than the waiting time corresponding to the back-off parameters of the primary channel at the timing of setting the NAV on the primary channel, and when the waiting time corresponding to the back-off parameters of the primary channel is longer than the waiting time corresponding to the back-off parameters of the primary channel at the timing of setting the NAV on the primary channel, sets the back-off parameters of the primary channel at the timing of setting the NAV on the primary channel as back-off parameters to be used after re-transitioning to the primary channel.

[0115] (Configuration 8) The communication device according to any one of configurations 1 to 7, wherein the transmission control means manages back-off parameters for the primary channel and back-off parameters for the secondary channel separately, and when the other communication device acquires a transmission opportunity in the primary channel through which the data is scheduled to be transmitted, determines a back-off parameter for the secondary channel based at least on the back-off parameter, which is a waiting time in the primary channel, and attempts to acquire a transmission opportunity in the secondary channel using the determined back-off parameter.

[0116] (Configuration 9) A communication device according to any one of configurations 1 to 8, characterized in that the backoff parameters of the secondary channel are determined to include at least a backoff counter of the primary channel and a specific waiting time, and in control of attempting to acquire a transmission opportunity on the secondary channel, the transmission control means determines that the transmission opportunity has been acquired when a waiting time including the specific waiting time and the backoff counter has elapsed while the secondary channel is idle.

[0117] (Configuration 10) A control method for a communication device, comprising: when another communication device acquires a transmission opportunity on the primary channel on which data is scheduled to be transmitted, and a back-off parameter of the primary channel, which includes at least a back-off counter and is a waiting time until data transmission on the primary channel is started, is not zero, the control method includes a transmission control step of: setting a NAV corresponding to the transmission opportunity on the primary channel; determining a back-off parameter of a secondary channel based at least on the back-off counter, which is the waiting time on the primary channel; and attempting to acquire a transmission opportunity on the secondary channel and transmit the data using the determined back-off parameter; wherein in the transmission control step, if the back-off parameter of the primary channel includes a waiting time equivalent to an AIFS period, the back-off parameter of the secondary channel is determined based also on the waiting time equivalent to the AIFS period.

[0118] (Configuration 11) A program for causing a computer to execute the communication device control method according to Configuration 10.

[0119] The present invention can also be realized by a process in which a program that realizes 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., an ASIC) that realizes one or more of the functions.

[0120] 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.

[0121] This application claims priority based on Japanese Patent Application No. 2023-182153, filed on October 23, 2023, the entire contents of which are incorporated herein by reference.

[0122] 101 AP 102 STA 103 STA 202 Control unit

Claims

1. A communications device comprising: a transmission control means for, when a back-off parameter of the primary channel, which includes at least a back-off counter and is a waiting time until data transmission is started on a primary channel, being non-zero, and another communications device acquires a transmission opportunity on the primary channel that is scheduled to transmit the data, setting a NAV (Network Allocation Vector) corresponding to the transmission opportunity on the primary channel, determining a back-off parameter of a secondary channel based at least on the back-off counter, which is the waiting time on the primary channel, and attempting to acquire a transmission opportunity on the secondary channel and transmit the data using the determined back-off parameter, wherein, when a waiting time equivalent to an Arbitration Inter Frame Space (AIFS) period is included in the back-off parameter of the primary channel, the transmission control means determines the back-off parameter of the secondary channel also based on the waiting time equivalent to the AIFS period.

2. The communication device according to claim 1, further comprising: a storage means for storing an EDCA (Enhanced distributed channel access) parameter set used for data transmission; and a calculation means for calculating a back-off counter, which is a waiting time until starting data transmission, based at least on the EDCA parameter set.

3. The communication device according to claim 2, further comprising: a receiving means for receiving an EDCA parameter set from an access point device; and an updating means for updating the EDCA parameter set stored in the storage means based on the EDCA parameter set received by the receiving means.

4. The communication device according to any one of claims 1 or 2, characterized in that the communication device is an access point device, the transmission control means periodically attempts to transmit a beacon frame on the primary channel, and the beacon frame transmitted by the access point device includes at least information identifying a secondary channel and an EDCA parameter set.

5. A communication device as described in any one of claims 1 to 4, characterized in that the transmission control means terminates control of attempting to acquire a transmission opportunity in the secondary channel before the period of the NAV set for the primary channel elapses, and performs control of attempting to acquire a transmission opportunity in the primary channel.

6. A communication device as described in claim 5, characterized in that when control attempting to acquire a transmission opportunity in the secondary channel is terminated and control is performed to attempt to acquire a transmission opportunity in the primary channel by re-transitioning to the primary channel, the transmission control means sets the contention parameters of the secondary channel as the contention parameters to be used after re-transitioning to the primary channel.

7. The communication device described in claim 6, characterized in that the transmission control means sets the back-off parameter of the secondary channel as the back-off parameter to be used after re-transitioning to the primary channel when the waiting time corresponding to the contention parameter of the secondary channel is shorter than the waiting time corresponding to the back-off parameter of the primary channel at the timing of setting the NAV on the primary channel, while setting the back-off parameter of the primary channel at the timing of setting the NAV on the primary channel as the back-off parameter to be used after re-transitioning to the primary channel when the waiting time corresponding to the contention parameter of the secondary channel is longer than the waiting time corresponding to the back-off parameter of the primary channel at the timing of setting the NAV on the primary channel.

8. A communication device as described in any one of claims 1 to 7, characterized in that the transmission control means manages back-off parameters in the primary channel and back-off parameters in the secondary channel separately, and when the other communication device acquires a transmission opportunity in the primary channel through which the data is scheduled to be transmitted, determines a back-off parameter for the secondary channel based at least on the back-off parameter, which is a waiting time in the primary channel, and attempts to acquire a transmission opportunity in the secondary channel using the determined back-off parameter.

9. A communication device as described in any one of claims 1 to 8, characterized in that the backoff parameters of the secondary channel are determined to include at least a backoff counter of the primary channel and a specific waiting time, and in control of attempting to acquire a transmission opportunity in the secondary channel, the transmission control means determines that the transmission opportunity has been acquired when the secondary channel is idle and a waiting time including the specific waiting time and the backoff counter has elapsed.

10. A control method for a communication device, comprising: a transmission control step of, when another communication device acquires a transmission opportunity on the primary channel that is scheduled to transmit data, in a state in which a back-off parameter of the primary channel that includes at least a back-off counter is not zero, which is a waiting time until starting data transmission on the primary channel, setting a NAV (Network Allocation Vector) corresponding to the transmission opportunity on the primary channel, determining a back-off parameter of a secondary channel based at least on the back-off counter, which is the waiting time on the primary channel, and attempting to acquire a transmission opportunity on the secondary channel and transmit the data using the determined back-off parameter, wherein in the transmission control step, if the back-off parameter of the primary channel includes a waiting time equivalent to an AIFS (Arbitration Inter Frame Space) period, the back-off parameter of the secondary channel is also determined based on the waiting time equivalent to the AIFS period.

11. A program for causing a computer to execute the method for controlling a communication device according to claim 10.

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