Communication device, control method for communication device, and program

Abstract

To provide a technique for improving channel utilization efficiency in a communication system using a communication link constituted by a plurality of channels, as one of objects.SOLUTION: When another communication device acquires a transmission opportunity on a primary channel, a communication device sets a NAV on the primary channel. The communication device then determines back-off parameters for a secondary channel based at least on a back-off counter that is a waiting time on the primary channel, and attempts to acquire a transmission opportunity on the secondary channel and to transmit the data using the determined back-off parameters. When back-off parameters for the primary channel include a waiting time equivalent to an AIFS period, the communication device determines the back-off parameters for the secondary channel, based also on the waiting time equivalent to the AIFS period.SELECTED DRAWING: Figure 4

Description

[Technical field]

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

[0002] The Institute of Electrical and Electronics Engineers (IEEE) 802.11 standard is known as a communication standard for wireless local area networks (WLANs). The IEEE 802.11be standard and its successor, the IEEE 802.11bn standard, aim 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 other channels when the Primary Channel used to acquire the transmission right is unavailable. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] US Patent Publication No. 11696353 Summary of the Invention [Problem to be solved by the invention]

[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 constituted by a plurality of channels. [Means for solving the problem]

[0006] In order to achieve the above object, one aspect of the present invention provides a communication device, which, when a back-off parameter of the primary channel, which includes at least a back-off counter and is a waiting time until starting to transmit data on a primary channel, is not zero and another communication device acquires a transmission opportunity on the primary channel through which the data is to be transmitted, has a transmission control means for 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, and is characterized in that, when a waiting time equivalent to an AIFS (Arbitration Inter Frame Space) 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 based also on the waiting time equivalent to the AIFS period. Effect of the Invention

[0007] According to one aspect of the present invention, it becomes possible to improve the channel utilization efficiency in a communication system that uses a communication link constituted by a plurality of channels. [Brief description of the drawings]

[0008] [Figure 1] FIG. 1 illustrates a configuration of a network system. [Diagram 2] FIG. 2 is a diagram illustrating a hardware configuration of a communication device. [Diagram 3] FIG. 11 is a schematic diagram illustrating an example of a channel access procedure. [Figure 4] FIG. 2 is a schematic diagram illustrating an example of a functional module for channel access. [Diagram 5] 11 is a flowchart illustrating an example of channel access control in a STA. [Figure 6] 11 is a flowchart illustrating an example of channel access control in a STA. [Figure 7] 11A and 11B are diagrams illustrating an example of parameter update control when re-transitioning to a primary channel. [Figure 8] 10 is a flowchart illustrating an example of shared control of secondary channel-related parameters in the second embodiment. [Figure 9] 13 is a flowchart illustrating an example of shared control of secondary channel-related parameters in the third embodiment. [Figure 10] 1 is a schematic diagram illustrating an example of a channel access procedure taking into account legacy STAs. [Figure 11] FIG. 13 is a schematic diagram for explaining a modified example of the functional module. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

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

[0010] <First embodiment> An example of the configuration of a network system according to this embodiment is shown in Fig. 1. The network system according to this embodiment includes one access point device (hereinafter, also simply referred to as AP, AP STA, or access point) and two station devices (hereinafter, also simply referred to as STA, Non-AP STA, or stations).

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

[0012] IEEE is an abbreviation for the Institute of Electrical and Electronics Engineers. The main features of IEEE802.11bn, the successor standard to IEEE802.11be, are highly reliable communication, low latency communication, and improved throughput during congestion. Wireless frames communicated under this successor standard are also called UHR (Ultra High Reliability) PPDU. PPDU is an abbreviation for Physical Layer Protocol Data Unit.

[0013] The name UHR is a name given for convenience in consideration of the goals and features of the successor standard, and may be a different name when the standard is completed. Similarly, the name IEEE802.11bn may be a different name when the standard is completed. However, it should be noted that this specification and the appended claims are essentially applicable to all successor standards that are successors to the 802.11be standard.

[0014] Returning to the description of Fig. 1, the AP 101 is an access point that supports a multi-band function that provides a network 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 for communication. Hereinafter, the communication link is also simply called a link. The AP 101 that performs Multi-Link communication is also called an AP Multi-Link Device (AP MLD) 101, and the STA 102 that performs Multi-Link communication is also called a non-AP MLD 102.

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

[0017] 1 shows a network system consisting of one AP 101, STA 102, and STA 103 as an example, but the number of STAs constituting the network system may be greater than that shown in the figure. In addition, the AP 101 and STAs 102 to 103 are described as supporting UHR PPDU communication (transmission and reception), but in addition to this, they can also be configured to support PPDU communication of a legacy standard that is a standard that precedes the UHR standard. Specifically, the AP 101 and STA 102 can also be configured to support PPDU transmission and reception of the IEEE802.11a / b / g / n / ac / ax / be standard, etc.

[0018] Moreover, the frequency bands used by the AP 101 and the STAs 102 to 103 are not limited to the 2.4 GHz band and the 5 GHz band described above. For example, different frequency bands such as the 6 GHz band, the Sub 1 GHz band, and 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] In the IEEE802.11 series of standards, a frequency channel using a bandwidth of 20 MHz is specified as the minimum channel in the 2.4 GHz, 5 GHz, and 6 GHz frequency bands. This standard also defines multiple available channels in each of the 2.4 GHz, 5 GHz, and 6 GHz frequency bands. This standard also allows a channel to be used in combination with other 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. That is, one link formed by two channels with a bandwidth of 20 MHz uses a bandwidth of 40 MHz.

[0021] The AP 101 establishes one or more links between devices in order to communicate data with the STAs 102 and 103. For example, the STA 102 executes a connection procedure with the AP 101 in order to establish a link with the AP 101. When the connection procedure between the STA 102 and the AP 101 is completed, a link is established between the devices. By establishing a link, a communication device such as an AP or a STA can access a wireless medium and communicate data, etc. with a communication device of the other party. For example, when one link using a bandwidth of 160 MHz is established between devices, the AP 101 and the STA 102 communicate using all or a part of the channels that constitute the link. A link using a bandwidth of 160 MHz can be configured by bundling eight channels with a bandwidth of 20 MHz.

[0022] Before transmitting data, the AP 101 and STAs 102 to 103 perform carrier sense to determine whether transmission is possible. For example, the communication device measures the strength of a signal received on a channel that the device intends to use for transmission (received signal strength), and when the received signal strength exceeds a predetermined threshold, determines that a signal exists on the channel. The communication device also determines a transmission period during which a signal is 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) in the device. The communication device may handle the stored NAV as a period during which the device does not transmit. The operation of the communication device to set a period during which the device does not transmit based on information such as the Duration field of the received signal is also called setting a NAV. When the communication device determines that a signal exists on the channel by carrier sense, or when the period of the set NAV has not expired, the communication device may determine that transmission is not possible. In this case, the state of the channel may be called a busy state. On the other hand, a state in which no signal is detected on a channel in carrier sense and no NAV is set may be called an idle state. When a channel is in an idle state, the communication device may determine that transmission is possible. Note that, for example, when communicating using a link with a bandwidth of 160 MHz, the communication device may determine whether transmission is possible using only the Primary Channel (PCH). The PCH is one of eight channels with a bandwidth of 20 MHz that constitute the link with a bandwidth of 160 MHz, and may be notified to the STA 102 by a Beacon frame that is periodically broadcast by the AP 101. For example, when the AP 101 or the STAs 102 to 103 determine that transmission is possible as a result of performing carrier sense on the PCH for a predetermined period of time, they may perform transmission by channel bonding using other channels included in the same link. For example, they may transmit a PPDU with a width of 160 MHz.In addition, when the communication device determines that transmission is not possible as a result of performing carrier sensing on the PCH, the communication device may postpone the transmission even if other channels included in the same link are in an idle state. Each channel other than the PCH that constitutes one link may be called a secondary channel (SCH). The secondary channel may also be called a non-primary channel (NPCH).

[0023] In this way, in a communication device such as the AP 101 or the STAs 102 and 103, when a signal is received on a certain channel, there is a case where a signal is transmitted on another channel (for example, an adjacent channel) arranged at a frequency close to the channel. In this case, the received signal may not be properly received. For example, it is assumed that the communication device can simultaneously perform transmission processing and reception processing using different channels. When the communication device receives using a certain channel and transmits on an adjacent channel, the power of the transmission signal leaks into the channel of the received signal, causing interference with the received signal. Generally, the power due to such leakage of the transmission signal is much greater than the received power of the received signal, so the received signal is not properly received. In order to avoid such a situation, the IEEE802.11 series standard provides a PCH as a channel commonly used between communication devices to determine whether transmission is possible. That is, while one communication device is transmitting using the PCH, the other communication device does not transmit even if the other channel is in an idle state. This can solve the problem of interference caused by power leakage between the above-mentioned channels. However, when the PCH is busy, not using other idle channels (SCHs) reduces the efficiency of frequency usage. For example, consider a case where another communication device (e.g., STA or AP belonging to a different wireless network) transmits a frame using a 20 MHz wide channel corresponding to the PCH in the AP101, STA102, and 103. In this case, even if the other seven SCHs are idle, the AP101 and STA102 to 103 cannot transmit using those SCHs because they determine that the channel is busy. In this situation, even if the STA102 transmits to the AP101 using a specific SCH channel that is idle, the AP101 may be able to properly receive the signal transmitted by the STA102. In this way, for example, configuring the remaining 140 MHz idle SCHs not to be used because the 20 MHz PCH is used by another network impairs the efficient use 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] Then, when the AP 101 and 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 when it is determined that transmission is possible, they perform transmission using one or more SCHs including the SPCH. In this way, channel access for performing transmission 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 the signal as necessary. In order to perform NPCH access, the AP 101 and the STAs 102 to 103 share information about NPCH access (information identifying the SPCH, etc.) in advance with the other communication device. The information identifying the SPCH can be included in the Secondary Primary Channel Announcement Element of the Beacon frame, for example. The Element may be configured with information indicating the Operating Class of the SPCH and information indicating the Channel. The Operating Class is an identifier capable of uniquely identifying a frequency band determined by the country or region in which the AP 101 is used. The Channel is an identifier capable of uniquely identifying each channel included in the frequency band identified by the Operating Class. The AP 101 may indicate the position of the SPCH by storing in the Element a relative position on the frequency axis of the SPCH based on the PCH. For example, it is assumed that the communication device 100 uses a link with a bandwidth of 160 MHz in the 6 GHz band and sets 1ch in that band as a PCH (20 MHz bandwidth). It is also assumed that the SCHs (20 MHz bandwidth) are 5ch, 9ch, 13ch, 17ch, 21ch, 25ch, and 29ch, respectively. When the communication device 100 sets 21ch as the SPCH, it sets 20 as information for 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 identifying 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 can also be configured to support wireless communication based on other communication standards such as Bluetooth (registered trademark), NFC, and Bluetooth (registered trademark) LE (Low Energy). NFC stands for Near Field Communication. The AP 101 and the STAs 102 and 103 can 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 and 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, the AP 101 and the STAs 102 and 103 can be configured to execute various controls using hardware circuits inside the wireless chip. The AP 101 and the STAs 102 and 103 can also be configured to execute various processes by cooperation between a processor, memory, and hardware circuits such as an ASIP inside 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] <Hardware configuration of communication device> 2 shows an example of a hardware configuration of a communication device (AP 101, STAs 102-103). The communication device includes 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 207-208 as an example of the hardware configuration.

[0029] The storage unit 201 is configured with both or either one of a ROM and a 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, as the storage unit 201, in addition to memories such as ROM and RAM, storage media such as non-volatile storage devices such as hard disks and SSDs (Solid State Drives) may be used.

[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 the programs stored in the storage unit 201 and controls the entire device by operating hardware circuits such as the ASIC. 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 controls the functional unit 203 to perform predetermined processing such as imaging, printing, and projection. The functional unit 203 is hardware for the device to perform predetermined processing. For example, when the communication device is a camera such as a digital still camera or a smartphone having a camera, the functional unit 203 is an imaging unit that performs imaging processing of surrounding images via a camera unit (not shown) of the communication device. For example, when the communication device is a printer, the functional unit 203 is a printing unit that performs printing processing on a sheet such as paper based on print data obtained from the outside through wireless communication. For example, when the communication device is a projector or smart glasses, the functional unit 203 is a projection unit that performs projection processing of image data or video data obtained from the outside through wireless communication. In the case of smart glasses, the projection surface is the retina of an end user. The data processed by the functional unit 203 may be data stored in the storage unit 201, or may be data communicated with other APs or STAs via the communication unit 206 described later. Furthermore, a communication device such as the AP 101 can provide a network storage function such as a 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 an AP 101 or the like 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. The data communication for uploading and downloading is also realized by communicating UHR PPDU between devices.

[0032] The input unit 204 receives various operations from the user. The output unit 205 performs various outputs 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 realized by one module, such as a touch panel. The output unit 205 functions as a display unit that presents information to the user. The input unit also functions as a receiving unit that receives user operations.

[0033] The communication unit 206 controls wireless communication conforming to the IEEE802.11 series standards and IP communication. In this embodiment, the communication unit 206 can execute communication control for transmitting and receiving UHR PPDU, which is a wireless frame of the 802.11bn standard, and PPDU corresponding to the previous standard in cooperation with the antennas 207-208. The antennas 207-208 are antennas capable of transmitting and receiving signals in at least one of the frequency bands of the sub-GHz band, the 2.4 GHz band, the 5 GHz band, the 6 GHz band, and the millimeter wave band, for example. Note that, in this embodiment, a communication device having two antennas is illustrated as an example, but is not limited to this. The number of antennas may be three or more.

[0034] When the communication device is compatible with the above-mentioned NFC standard, Bluetooth standard, wired communication standard, or the like, the communication unit 206 may be configured to control wireless communication or wired communication that complies 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 the reference numeral 300, the STA102 and the STA103 are attempting channel access in the PCH to transmit data. At this time, the STA102 and the STA103 decrease the transmission waiting time including the AIFS and the backoff counter determined based on the backoff algorithm while the PCH is idle. When the transmission waiting time in the idle state of the PCH becomes zero, the STA102 or the STA103 can start transmitting data. However, if a communication device in the OBSS wins the channel access of the idle PCH first, the PCH becomes busy. This situation means that another communication device wins the transmission opportunity in the PCH where the STA102 or the STA103 plans to transmit data. FIG. 3 illustrates a case where the communication device in the OBSS starts data transmission in the PCH first. More specifically, the dashed line shown in the reference numeral 300 indicates the timing when the communication device in the OBSS starts data transmission in the PCH first. OBSS is an abbreviation of 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 above-mentioned SPCH, and attempt to acquire a transmission opportunity in the secondary channel. At this time, the terminals in the BSS provided by the AP 101, such as the AP 101 and the STAs 102 to 103 of this embodiment, attempt channel access in the SPCH by utilizing the back-off parameters used in the PCH in the SPCH as well. In this embodiment, in order to realize data communication in the SPCH with a simple implementation, a restriction is set so that data communication in the SPCH is permitted only during the period when the PCH is busy. BSS is an abbreviation for Basic Service Sets.

[0038] Reference numerals 301 and 302 indicate the state in which the back-off parameters are also used for channel access in the SPCH, and illustrate a case in which the transmission waiting time of STA 102 is shorter than the transmission waiting time of STA 103. In addition, Fig. 3 illustrates a case in which STA 102, which has a shorter transmission waiting time, wins a transmission opportunity in 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. On the other hand, the STA 103 reduces the transmission waiting time while the SPCH is idle.

[0040] The dashed line indicated by reference numeral 304 indicates the timing when the transmission opportunity of the PCH by the communication device of the OBSS expires. At this timing, the AP101 and the STA102 to STA103 switch the channel to be monitored for channel access to the PCH. That is, the AP101 and the STA102 to STA103 re-transition to the normal state where the channel access is performed in the PCH. At this time, the communication device that was waiting for transmission in the SPCH attempts to access the channel in the PCH by using the back-off counter used in the SPCH in the PCH as well. Reference numeral 303 illustrates the state of the back-off counter that the STA103 has reduced in the SPCH, and reference numeral 305 illustrates an example of using the back-off counter in the PCH. FIG. 3 illustrates a case where the STA103, which did not win the transmission opportunity even at the timing indicated by 300 and did not win the transmission opportunity in the SPCH either, successfully reduces the back-off counter and wins the 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 to 103 will be described with reference to Fig. 4. Fig. 4 is a schematic diagram for explaining an example of functional modules for channel access provided in the AP 101 and the STAs 102 to 103. Fig. 4 shows an excerpt of functional modules that realize functions related to channel access. The data categorization unit 401 classifies data received from an upper layer into traffic categories that comply with the EDCA mechanism defined in the IEEE802.11e standard. EDCA is an abbreviation for Enhanced distributed channel access.

[0042] In the EDCA mechanism, data transmission is prioritized by class so that some specific types of traffic are given priority. Specifically, the categorizer 401 classifies data into one of four access categories (AC) defined in 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. The MAC frame is an abbreviation for a 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 is an abbreviation for Carrier Sense Multiple Access with Collision Avoidance.

[0045] When the CSMA / CA execution unit 403 detects that data has been stored in the corresponding queue, it reads out the EDCA parameters associated with the corresponding queue stored in the control unit 404. Then, the execution unit 403 determines a transmission waiting time consisting of an AIFS and a back-off counter based on the read out EDCA parameters. Hereinafter, the transmission waiting time including the AIFS and the back-off counter is also simply called a back-off parameter. It is assumed that the EDCA parameters are assigned in the order of VO, VI, VE, and BK so that the transmission of wireless signals is relatively prioritized. Each EDCA parameter includes CWmin, CWmax, AIFS, and TXOPLimit. CWmin is the minimum value of CW (Contention Window), which is the transmission waiting time, and CWmax is the maximum value of 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 wireless signals. The smaller AIFS is, the easier it is to obtain a transmission opportunity. TXOPLimit is the upper limit value of TXOP, which is the channel occupancy time. The larger the TXOPLimit, the more data is permitted to be transmitted during one acquired transmission opportunity.

[0046] Next, the execution unit 403 decrements the set back-off parameter while the channel state notified by the control unit 404 satisfies a condition such as an idle state, and waits for transmission until the waiting time becomes zero. The execution unit 403 stops the decrement process of the back-off parameter while the channel state notified by the control unit 404 satisfies a condition such as a busy state. Then, when the execution unit 403 determines that the waiting time becomes zero, it determines that it has won the transmission opportunity. The execution unit 403, which has determined that it has won the transmission opportunity, takes out data (MAC frame) from the queue, and transmits the UHR PPDU including the taken out MAC frame to another communication device in cooperation with the control unit 404, the communication unit 206, and the antenna 207. When the communication device attempts to acquire a transmission opportunity in the PCH and acquires the transmission opportunity, it transmits the UHR PPDU in one or more channels including the PCH. Also, when the communication device attempts to acquire a transmission opportunity in the SPCH and acquires the transmission opportunity, it transmits the UHR PPDU in 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 in obtaining a transmission opportunity. When execution units 403 corresponding to different ACs simultaneously win a transmission opportunity and request transmission, control is performed to give priority to 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 obtain a transmission opportunity, the data stored in the VO queue is transmitted with priority. At this time, the execution unit corresponding to the BK queue is notified that a collision has occurred, and the CW managed by the execution unit corresponding to the BK queue is increased.

[0048] The control unit 404 controls notifying the execution unit 403 of changes in channel conditions, and controls transition notification indicating that the channel for which channel access is attempted has transitioned to SPCH and re-transition notification indicating that the channel has re-transitioned to PCH. The execution unit 403 that receives the transition notification or re-transition notification 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 table of Figure 7. The table of Figure 7 is a diagram for explaining parameter setting control at the time of re-transition.

[0050] Each process shown in the flowcharts of Fig. 5 and Fig. 6 is executed by the processor of the control unit 202 of STA102-STA103 executing a computer program stored in the storage unit 201. Some processes such as transmission and modulation are realized by the processor of the control unit 202 and various processors, ASIC, DSP, FPGA, antenna, and ASIC, DSP, FPGA, etc. constituting the communication unit 206 in cooperation with each other. It is of course possible to configure the control unit such as ASIC and processor inside the communication unit 206 and the antenna to cooperate to execute each process shown in the flowchart. When it is desired to clearly indicate the subject of the process, the functional unit described in Fig. 4 is used as the subject.

[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 judges whether or not transmission data (MAC frame) is stored in the corresponding transmission queue. If it is judged that the transmission data is stored, the process proceeds to S502, and if it is judged that the transmission data is not stored, the process waits for the transmission data to be stored. The storage of data in the transmission queue is appropriately executed 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. In addition, when voice data is transmitted using a VoIP (Voice over Internet Protocol) application or the like, data corresponding to the voice data is categorized as VO by the categorization unit 401 and stored in the VO queue. The judgment process in S501 is executed in parallel by the execution units 403 corresponding to each queue.

[0053] In S502, the execution unit 403, which has determined that the transmission data has been stored in S501, acquires EDCA parameters corresponding to the access category of the queue associated with the execution unit from the control unit 404. Next, the execution unit 403 determines back-off parameters consisting of AIFS and a back-off value indicated by the back-off counter based on the acquired EDCA parameters, and sets the determined back-off parameters. When the setting is completed, the process proceeds to S503. The back-off 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 is an abbreviation for adaptive contention window minimum. The initial value of CWsize (i.e., the CWsize used when no collision occurs) is aCWmin. The CWsize is changed to twice the size every time a collision occurs. That is, in an environment where collisions occur frequently, the range of candidates for random back-off becomes larger, and the occurrence of collisions is suppressed. That is, the execution unit 403 calculates aCWmin corresponding to the access category, which is a set of EDCA parameters, and a random number within the range of the current contention window size (CWsize), thereby calculating a back-off counter to be used.

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

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

[0056] In S505, the control unit 404 judges whether another terminal (another communication device) has acquired a transmission opportunity. The control unit 404 cooperates with each unit to execute 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 preamble of the PPDU. If it is determined that the other communication device has acquired a transmission opportunity by analyzing the preamble, the process proceeds to S506. On the other hand, if it is determined that the PCH is still in the idle state and that the other communication device has not acquired a transmission opportunity, the process proceeds to S503. Although omitted in FIG. 5, the control unit 202 of the STA102 or STA103 performs control to receive the PPDU as appropriate when it determines that the received PPDU is addressed to itself as a result of analyzing the preamble.

[0057] In S506, the control unit 404 sets PCH_NAV, which indicates a period during which the device itself does not transmit in the PCH, based on information such as the Duration field of the PPDU received in S505. Next, the control unit 404 notifies the execution unit 403 of a transition notification indicating transition to the SPCH. The execution unit 403, which has received the transition notification, temporarily stores the current back-off parameter, which indicates a transmission waiting time managed to acquire a transmission opportunity in the PCH, as the back-off parameter before the SPCH transition. The back-off parameter before the transition is appropriately utilized 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 back-off 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 through 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, and 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 has requested transmission of the data that is the subject of the collision, of the occurrence of the collision. The execution unit 403, which has received the notification of the occurrence of the collision, 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 is determined that a user operation to turn off the power has been received, a shutdown process (not shown) is performed, and a series of transmission control operations is terminated. If it is determined 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 execution unit 403 receives a transition notification indicating a transition to the SPCH.

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

[0066] In S602, the execution unit 403 executes a waiting 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 waiting 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, execution unit 403 determines whether the backoff counter has reached zero. If it is determined that the backoff counter has reached zero, the process proceeds to S606, and if it is not determined that the backoff counter has reached zero (i.e., the backoff counter is 1 or greater), the process proceeds to S604.

[0068] In S604, the control unit 404 judges whether another terminal (another communication device) has acquired a transmission opportunity on the SPCH. The control unit 404 executes carrier sense on the SPCH in cooperation with each unit. 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 preamble of the PPDU. If it is determined that the other communication device has acquired a transmission opportunity by analyzing the preamble, the process proceeds to S605. On the other hand, if it is determined that the SPCH is still in the idle state and that the other communication device has not acquired a transmission opportunity, the process proceeds to S602. Although omitted in FIG. 6, the control unit 202 of the STA102 or STA103 performs control to receive the PPDU as appropriate when it determines that the received PPDU is addressed to itself as a result of analyzing the preamble.

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

[0070] Next, the execution unit 403, which has determined that the back-off 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 in at least one channel not including a PCH and including an SPCH.

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

[0072] In S609, the control unit 404 notifies the execution unit 403, which has requested transmission of the data that is the subject of the collision, of the occurrence of the collision. Upon receiving the notification of the occurrence of the 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 period of the PCH_NAV set in S506 has ended, 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 period of the PCH_NAV set in S507 has not ended, 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 notification of the re-transition, the execution unit 403 performs selection control of back-off parameters including an AIFS and a back-off counter to be used when re-transitioning to the PCH. The back-off parameters including the selected AIFS and back-off counter are used for channel access after re-transitioning to the PCH. When the selection control is completed, the control unit 404 advances the process 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. When the selection control is omitted, the execution unit 403 transitions to the waiting control for transmission data described in S501.

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

[0077] A specific example of the selection control will be described with reference to Fig. 7. Fig. 7(a) 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 the STA has succeeded in data transmission at least once on the SPCH or not. If the STA has succeeded in data transmission at least once on the SPCH, the control unit 404 transitions to a mode in which unfavorable contention parameters are used for a certain period of time. The STA that transitions to this mode can be configured to determine a back-off parameter indicating a transmission waiting time based on the notified MU EDCA parameter during the period of the MU_EDCA Timer notified from the AP 101. The MU_EDCA Timer and the MU EDCA parameter are parameters defined by the IEEE 802.11ax standard and are parameters included in the Beacon frame transmitted by the AP 101. These parameters are provided to force a terminal that has succeeded in data transmission in uplink MU transmission to use unfavorable contention parameters for a certain period of time. In this embodiment, the STA that has succeeded in transmission on the SPCH also uses this parameter to determine the back-off parameter. This control makes it possible to maintain fairness with other communication terminals that have not succeeded in transmission.

[0079] On the other hand, if the data transmission in the SPCH is not successful, the execution unit 403 compares the back-off parameters used in the PCH before the SPCH transition stored in S406 with the back-off parameters when resuming from the SPCH to the PCH. Then, the back-off parameters with the shorter waiting time are selected as the back-off parameters to be used after re-transitioning to the PCH. That is, if the back-off parameters can be decremented smoothly in the SPCH, the back-off parameters can be handed over to the PCH. On the other hand, if the back-off parameters in the SPCH are large, such as when a collision occurs in the SPCH, the value is not handed over and channel access in the PCH can be resumed with the back-off parameters used in the previous PCH. This control can increase the possibility of giving a transmission opportunity to a terminal that cannot acquire a transmission opportunity in the PCH and further cannot acquire a transmission opportunity in the SPCH and re-transitions to the PCH.

[0080] <Second embodiment> In the first embodiment, a case where a STA that has successfully transmitted in the SPCH is about to acquire a new transmission opportunity is exemplified, in which a back-off parameter is determined based on an EDCA parameter set of the PCH. In the second embodiment, in addition to the information that identifies the SPCH shared in the first embodiment, an EDCA parameter for the SPCH is newly shared between the AP and the STA, and the case where the parameter is used will be described with reference to FIG.

[0081] FIG. 8(a) shows parameter notification control executed by AP101, and FIG. 8(b) shows parameter update control executed by STA102-103. Each process shown in the flowchart of FIG. 8(a) is executed by the processor of the control unit 202 of AP101 executing a computer program stored in the storage unit 201. Also, each process shown in the flowchart of FIG. 8(b) is executed by the processor of the control unit 202 of STA102-103 executing a computer program stored in the storage unit 201. Note that in any communication device, some processes such as transmission and modulation are realized in cooperation with the processor of the control unit 202 and various processors, ASIC, DSP, FPGA, and antenna constituting the communication unit 206. Note that some processes may be realized in cooperation with the ASIC, DSP, FPGA, and the like constituting the control unit 202. Note that this is not limited to this, and it is naturally possible to configure each communication device to execute each process shown in the flowchart in cooperation with the control unit such as the ASIC and processor inside the communication unit 206 and the antenna. When it is desired to clearly indicate the subject of processing, the functional unit described in FIG. 4 will be used as the subject.

[0082] FIG. 8 is a flowchart of the communication control of parameters in this embodiment. In S801, the control unit 202 of the AP 101 cooperates with each unit to periodically transmit a beacon including an SPCH EDCA Parameter Set Element including EDCA parameters to be used in the SPCH. The control unit 202 also includes a Secondary Primary Channel Announcement Element for identifying the above-mentioned SPCH in the periodically transmitted beacon. It is assumed that the AP 101 can select any parameter that it wants 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 degree or the like. In addition, the AP 101 may provide a detailed operation setting screen to the user, and store the settings made via the operation setting screen as the operation setting. In this case, the AP 101 selects the channel number to be used in the SPCH and the parameters to be used in the SPCH based on the operation setting changed by the user via the operation setting screen. The operation setting screen can be configured so that the channel number of the SPCH and parameters such as CWmin, CWmax, AIFS, TXOPLimit, etc. can be set for each AC.

[0083] Meanwhile, in S811, the control unit 202 of the STAs 102 to 103 cooperates with each unit 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 STAs themselves should transition and the EDCA parameter set to be used in the SPCH.

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

[0085] <Third embodiment> In the first and second embodiments, control is exemplified when all STAs connected to the AP 101 support data transmission via SPCH. In the third embodiment, control is described with reference to Fig. 7(b) to Fig. 10 when the STAs connected to the AP 101 include legacy STAs that do not support data transmission via SPCH. In this embodiment, a legacy STA means an STA that supports one or more of the IEEE802.11a / b / g / n / ac / ax / be standards but does not support the IEEE802.11bn 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, etc., and notifies the STAs. 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] A specific description will be given with reference to FIG. 9. Each process shown in the flowchart of FIG. 9(a) 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 FIG. 9(b) 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 any communication device, some processes such as transmission and modulation are realized by the processor of the control unit 202 in cooperation with various processors, ASIC, DSP, FPGA, and antennas constituting the communication unit 206. Some processes may be realized in cooperation with the ASIC, DSP, FPGA, and the like constituting the control unit 202. Of course, it is possible to configure each communication device to execute each process shown in the flowchart by cooperation between the control unit such as the ASIC and the processor inside the communication unit 206 and the antenna. In order to clearly indicate the subject of the process, the functional unit described in FIG. 4 is used as the subject.

[0088] In S901, the control unit 202 of the AP 101 determines whether or not 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] On the other hand, 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 storing the value determined in S903, in addition to the Element described in S801.

[0092] On the other hand, in S911, the control unit 202 of the STAs 102-103 cooperates with each unit 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 in 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 newly stores or updates the parameters to be used when resuming the contention access of the PCH based on the acquired values.

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

[0094] The selection control of STAs that have successfully transmitted on the SPCH is performed in the same manner as described in Fig. 7(a). In this embodiment, STAs that have never successfully transmitted on the SPCH are controlled to select transmission parameters to which a delay that takes into account legacy STAs 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] The control when data transmission in the SPCH is not successful will be specifically described. In this case, the execution unit 403 compares the back-off parameter used in the PCH before the SPCH transition stored in S406 with the parameter obtained by converting the delay into the back-off parameter when resuming from the SPCH to the PCH. Then, the back-off parameter with the shorter waiting time is selected as the back-off parameter to be used after re-transitioning to the PCH. That is, in the case where the back-off parameter can be smoothly decremented in the SPCH and the transmission waiting time is shorter than before the transition even if the delay considering the legacy STA is added, it is possible to take over the parameter with the delay added 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 transmit, while preventing legacy STAs from being disadvantaged too much. Fig. 10 is a schematic diagram of transmission control in the third embodiment. The following description focuses on STA 103. Here, as an example, a case is illustrated in which a delay of three slots is specified as the value of the PCH contention access resume parameter set element.

[0097] At the timing of reference number 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 the timing of reference number 1005 when the transition is made again to the PCH, a delay of 3 slots is added, and channel access on the PCH is resumed with a transmission wait time of 6 slots.

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

[0099] <Modification> In the above 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 SPCH are provided. Fig. 11 illustrates a case where a communication device such as a 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 sharing process of the back-off parameters when transitioning to the SPCH or when re-transitioning to the 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 that the execution unit 703 has used to acquire 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 has received 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 has received the transition notification determines the back-off parameters for the SPCH based on the received back-off parameters and attempts channel access on its own CH. At this time, the control of channel access in each SCH after the determination is the same as in the above embodiment, so the description will be omitted. When the back-off counter reaches zero and the transmission opportunity is successfully secured, each execution unit 713 cooperates with the connected control unit 714 to execute the transmission process of the UHR PPDU that stores the data stored in the corresponding queue. In addition, the SPCH control unit 714 notifies the other SPCH control units 714 and the PCH control unit 704 that the transmission opportunity has been secured. The other SPCH control units 714 that have received the notification request the execution units 713 connected to the queues corresponding to the access category being transmitted to stop the back-off procedure. The execution units 713 that have received the notification stop the back-off procedure. Note that the execution units 713 provided for access categories different from the data of the access category 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 notification of re-transition to each SPCH control unit 714. Each SPCH control unit 714 that receives the notification of re-transition transmits a back-off parameter (current back-off parameter) when resuming from the SPCH to the PCH to the PCH control unit 704. The PCH control unit 704 compares the multiple back-off parameters received from each SPCH control unit 714 with the back-off parameters in the PCH that it stores, and selects the one with the shortest transmission waiting time. At this time, it may be configured to add a Delay that takes into account the legacy STA described in the third embodiment.

[0105] <Other embodiment 1> In the above embodiment, when resuming from SPCH to PCH, it is assumed that the back-off parameters used in SPCH are handed over to PCH, but this is not limited thereto. In order to simplify the process, when resuming from SPCH to PCH, the contention parameters may be recalculated based on the EDCA parameters of PCH, and the recalculated contention parameters may be used for channel access of PCH. In addition, in the above embodiment, the channel for determining whether or not transmission using SCH (or NPCH) is possible when it is determined that PCH is busy is called SPCH, but this is not limited thereto. It may also be called 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) 1. A communication device, comprising: a transmission control means for, when another communication device acquires a transmission opportunity on the primary channel through which the data is to be transmitted, setting a NAV (Network Allocation Vector) corresponding to the transmission opportunity on the primary channel, and determining a back-off parameter of a secondary channel based at least on the back-off counter, which is a waiting time until data transmission is started 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, when a back-off parameter of the primary channel including at least a back-off counter is not zero, the waiting time on the primary channel, The communication device is characterized in that, when the backoff parameters of the primary channel include a waiting time equivalent to an AIFS (Arbitration Inter Frame Space) period, the transmission control means determines the backoff parameters of the secondary channel based on the waiting time equivalent to the AIFS period.

[0109] (Configuration 2) the communication device is a station device, A storage means for storing an EDCA (Enhanced distributed channel access) parameter set used for data transmission; 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; 2. The communication device according to claim 1, further comprising:

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

[0111] (Configuration 4) the communication device is an access point device, the transmission control means periodically attempts to transmit a Beacon frame on the primary channel; 3. The communication device according to claim 1, wherein the Beacon frame transmitted by the access point device includes at least information for identifying 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 in the secondary channel before the period of the NAV set in the primary channel elapses, and performs control of attempting to acquire a transmission opportunity in the primary channel.

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

[0114] (Configuration 7) The communication device according to configuration 6, characterized in that 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, 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, while 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, the transmission control means sets 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.

[0115] (Configuration 8) The communication device described in any one of configurations 1 to 7, characterized in that the transmission control means manages a back-off parameter in the primary channel and a back-off parameter 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.

[0116] (Configuration 9) 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; A communication device described in any one of configurations 1 to 8, characterized in that in the 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 in an idle state and a waiting time including the specific waiting time and the back-off counter has elapsed.

[0117] (Configuration 10) A method for controlling a communication device, comprising: a transmission control step of, when another communication device acquires a transmission opportunity on the primary channel through which the data is to be transmitted, in a state in which a back-off parameter of the primary channel including at least a back-off counter is not zero, 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 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 parameter; A control method characterized in that, in the transmission control step, when the backoff parameters of the primary channel include a waiting time equivalent to an AIFS period, the backoff parameters of the secondary channel are 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] <Other embodiment 3> The present invention can also be realized by a process in which a program for implementing one or more of the functions of the above-described embodiments is supplied to a system or device via a network or a storage medium, and one or more processors in a computer of the system or device read and execute the program. The present invention can also be realized by a circuit (e.g., ASIC) that implements one or more of the functions.

[0120] The invention is not limited to the above-described embodiments, and various modifications and variations are possible without departing from the spirit and scope of the invention. Accordingly, the following claims are appended to apprise the public of the scope of the invention. [Explanation of symbols]

[0121] 101 AP 102 STA 103 STA 202 Control section

Claims

1. A communication device, comprising: a transmission control means for, when another communication device acquires a transmission opportunity on the primary channel through which the data is to be transmitted, setting a NAV (Network Allocation Vector) corresponding to the transmission opportunity on the primary channel, and determining a back-off parameter of a secondary channel based at least on the back-off counter, which is a waiting time until data transmission is started on the primary channel, and determining the back-off parameter of a secondary channel using the determined back-off parameter, when a back-off parameter of the primary channel including at least a back-off counter is not zero, and attempting to acquire a transmission opportunity on the secondary channel and transmit the data; The communication device, characterized in that, when the backoff parameters of the primary channel include a waiting time equivalent to an AIFS (Arbitration Inter Frame Space) period, the transmission control means determines the backoff parameters of the secondary channel based on the waiting time equivalent to the AIFS period.

2. the communication device is a station device, A storage means for storing an enhanced distributed channel access (EDCA) parameter set used for data transmission; 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; 2. The communication device of claim 1, further comprising:

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

4. the communication device is an access point device, the transmission control means periodically attempts to transmit a Beacon frame on the primary channel; 3. The communication device according to claim 1, wherein a beacon frame transmitted by the access point device includes at least information for identifying a secondary channel and an EDCA parameter set.

5. The communication device according to 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 in the primary channel elapses, and performs control of attempting to acquire a transmission opportunity in the primary channel.

6. The communication device according to claim 5, characterized in that 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 a contention parameter of the secondary channel as a contention parameter to be used after re-transitioning to the primary channel.

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

8. The communication device 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. 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; A communication device as claimed in any one of claims 1 to 8, characterized in that 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 back-off counter has elapsed.

10. A method for controlling a communication device, comprising: a transmission control step of: when another communication device acquires a transmission opportunity on the primary channel, which is a waiting time until data transmission is started on the primary channel, and a back-off parameter of the primary channel including at least a back-off counter is not zero, 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 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 parameter; In the transmission control step, when the backoff parameters of the primary channel include a waiting time equivalent to an AIFS (Arbitration Inter Frame Space) period, the backoff parameters of the secondary channel are 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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