Communication device, control method, and program

Abstract

To realize communication having high reliability and low delay.SOLUTION: A communication apparatus that transmits or receives a radio frame conforming to IEEE802.11 standard series to other communication apparatus or from the other communication apparatus is provided. In a MAC (Media Access Control) frame of the radio frame, information indicating whether or not a communication function performing communication in a communication period where a first communication period for data, in which transmission in low delay is requested, and a second communication period for other data are scheduled not to compete with each other, is supported, is included, and the communication apparatus controls such that the other communication apparatus which does not support the communication function does not transmit data in the first communication period.SELECTED DRAWING: Figure 4

Description

Technical Field

[0001] The present invention relates to an information sharing technology for a scheduling function in wireless communication.

Background Art

[0002] As a communication standard for wireless LAN (Local Area Network) formulated by IEEE (Institute of Electrical and Electronics Engineers), the IEEE802.11 standard series is known. The IEEE802.11 standard series includes IEEE802.11a / b / g / n / ac / ax standards, etc., and continuously, new standards are being studied to improve peak throughput and frequency utilization efficiency compared to conventional standards. For example, in the IEEE802.11ax standard, high peak throughput can be obtained by using OFDMA (Orthogonal Frequency Division Multiple Access), etc. (see Patent Document 1).

Prior Art Documents

Patent Documents

[0003]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0004] In recent years, as a new standard, the formulation of the IEEE802.11be standard is in progress aiming at further improving throughput and frequency utilization efficiency. One of the targets in this standardization work is to realize high-reliability and low-latency (Reliable Low-Latency: RLL) communication.

[0005] The present invention provides a communication control technology for realizing such high-reliability and low-latency communication.

Means for Solving the Problems

[0006] A communication device according to an aspect of the present invention A communication device operating as an access point, IEEE802.11 be standard has communication means for sending a wireless frame compliant with to another communication device believe . transmitted The MAC (Media Access Control) frame of the wireless frame includes The communication device executes communication with low latency by restricting competition for channel access in a preset period based on time information indicating whether it supports to . element The above The wireless frame including the MAC frame including the information element indicating whether the communication device supports the communication method is at least one of a Beacon frame, a Probe Response frame, an Association Response frame, and a Reassociation Response frame .

Advantages of the Invention

[0007] According to the present invention, highly reliable and low-latency communication can be realized.

Brief Description of the Drawings

[0008] [[Figure 1]] It is a diagram showing a configuration example of a network in this embodiment. [[Figure 2]] It is a diagram showing a hardware configuration example of a communication device. [[Figure 3]] It is a diagram showing a functional configuration example of a communication device. [[Figure 4]] It is a diagram showing an example of the flow of processing executed by an AP when a STA connects. [[Figure 5]] It is a diagram showing an example of the flow of data reception processing. [[Figure 6]] It is a diagram showing an example of the flow of data transmission processing. [[Figure 7]] It is a diagram showing an example of the flow of messages transmitted and received between an AP and a STA during DL communication. [[Figure 8]] It is a diagram showing an example of the flow of messages transmitted and received between an AP and a STA during UL communication. [[Figure 9]] It is a diagram showing a configuration example of TAS capability information. [[Figure 10]] It is a diagram showing a configuration example of TAS capability information. [[Figure 11]] It is a diagram for explaining the set value of TAS capability information. [[Figure 12]]This is a diagram for explaining the set value of TAS capability information. [[Figure 13]] This is a diagram showing an example of the processing flow when TAS capability information is notified by a Beacon frame. [[Figure 14]] This is a diagram for explaining an example of a primary channel in the 5 GHz band. [[Figure 15]] This is a diagram for explaining TAS traffic processing. [[Figure 16]] This is a diagram for explaining TAS traffic processing.

Embodiments for Carrying Out the Invention

[0009] Hereinafter, embodiments will be described in detail with reference to the accompanying drawings. Note that the following embodiments do not limit the invention according to the claims. Although a plurality of features are described in the embodiments, not all of these plurality of features are essential for the invention, and the plurality of features may be arbitrarily combined. Further, in the accompanying drawings, the same or similar configurations are given the same reference numerals, and redundant explanations are omitted.

[0010] (Network Configuration) FIG. 1 shows a configuration example of the network according to the present embodiment. As part of the network in FIG. 1, it includes a wireless communication network (BSS101) that provides a wireless communication service by AP102, and a wireless communication network (BSS111) that provides a wireless communication service by AP112. Note that AP is an acronym for access point, and BSS is an acronym for Basic Service Set. The wireless terminal (STA) can connect to an AP whose communication range is the location where the own device exists, and participate in the BSS provided by that AP. The STA can transmit and receive wireless frames within the participated network. In the example of FIG. 1, since STA103 exists within the communication ranges of both AP102 and AP112, it can connect to any of these APs and participate in either BSS101 or BSS111. Note that an environment in which the communication ranges of such a plurality of APs overlap is sometimes referred to as an OBSS environment. That is, in the present embodiment, STA103 exists in the OBSS environment. Here, it is assumed that STA103 is connected to AP102, and the signal from AP112 can be an interference signal at STA103. Also, since STA113 exists within the communication range of AP112, it can connect to AP112 and participate in BSS111.

[0011] Also, AP102 and AP112 are connected by bridge 104. Between an AP and a bridge, and between a bridge and another bridge, they can be connected by, for example, a wired line. However, a wireless line may be used in at least a part of the section where AP102 and AP112 are connected. With these configurations, one network can be formed in which the wireless network formed by AP102 and AP112 and the wired network composed of bridge 104 and the like are fused.

[0012] The sensor device 107 is a sensor connected to the network via the bridge 104, and is configured to output, for example, environmental data collected by the sensor function to other devices. In the present embodiment, it is assumed that the sensor device 107 transmits the collected data to the STA 103 at regular intervals. The remote device 108 is a device that is connected to the network via the bridge 104 and operates according to a remote operation instruction from another device. The remote device 108 is an end device that requires low-latency data communication by an RTA (Real Time Application), such as an industrial robot or a medical surgical robot, for example. In the present embodiment, it is assumed that the remote device 108 operates according to a remote operation instruction from the STA 103.

[0013] In such a network system, for example, it is important to ensure that STA103 can reliably receive data from the sensor device 107 at a fixed period, and that the remote operation instruction signal from STA103 reaches the remote device 108 with low latency. However, in a conventional wireless LAN, since the device transmitting data checks that no wireless resources are being used in the vicinity and transmits a signal during a period when no wireless resources are being used, communication cannot be established if wireless resources are being used by other devices. Therefore, in order to ensure the transmission and reception of signals at a fixed period and to enable low-latency communication, it is necessary to introduce some communication control function. On the other hand, introducing the Time-Aware Schedule (TAS) method defined in the IEEE802.1Qbv standard can be one solution for appropriately executing the transmission and reception of predetermined data such as data with strict delay requirements. The TAS method is a time-corresponding scheduling method in which signal transmission and reception are performed at a fixed time based on time. In this embodiment, in the network, by performing communication using this TAS method, communication at a fixed period and low-latency communication are appropriately executed. For this purpose, it is assumed that each device such as AP102, STA103, STA113, and bridge 104 supports the TAS method. However, it is assumed that AP112 does not support this TAS method. In addition, it is assumed that devices other than AP112 further support a standard specification (IEEE802.1AS) that synchronizes with the same reference clock in the network.

[0014] Hereinafter, the predetermined data that is scheduled, transmitted, and received in the TAS method is referred to as TAS traffic data. Here, the TAS traffic data is packet data that is transmitted and received in consideration of delay control between end devices. For such transmission and reception control, the network further includes a network management device 105 and a schedule management device 106. The network management device 105 executes delay control regarding the TAS traffic data. The schedule management device 106 performs schedule management regarding the TAS traffic of end devices in the network that use the TAS traffic data. The AP 102 transmits and receives data to and from the network management device 105 via the bridge 104. Further, the AP 102 executes an exchange of TAS information with the schedule management device 106 that performs schedule management for the entire network.

[0015] The network management device 105 collects requirements regarding a time-corresponding schedule (TAS) from end devices such as the AP 103, the sensor device 107, and the remote device 108. Based on this requirement, for example, it is specified which devices transmit and receive TAS traffic data, at what time interval the data is transmitted, and the magnitude of the allowable delay. The network management device 105 detects the network topology of the network to be controlled by the device itself. Here, the network topology can be the relationship of which devices each device in the network is connected to. Note that "connected" here may indicate a physically directly connected state, or may indicate a state in which a logical link is established regardless of the physical connection configuration. The network management device 105 calculates the end-to-end path between end devices for each transmission and reception of the TAS traffic data to be executed based on the collected requirements. Then, based on the calculation result, the network management device 105 determines at what timing each device should transmit a signal, performs scheduling, and notifies the schedule management device 106 of the schedule result.

[0016] The schedule management device 106 transmits messages including TAS information to the bridge 104 and the AP 102 to set the transmission / reception schedule. Further, the schedule management device 106 notifies the end devices (STA 103, sensor device 107, remote device 108) of the TAS information. At this time, the end devices (STA 103, sensor device 107, remote device 108) operate as a talker (data transmission side) or a listener (data reception side) according to the transmission schedule in the network regarding the TAS traffic, respectively. For example, in the combination of end devices considering the RTA traffic between the STA 103 and the sensor device 107, the STA 103 operates as a listener and the sensor device 107 operates as a talker. Details of the message sequence in this case will be described later with reference to FIG. 7 as an example of the downlink (DL) communication flow of data communication supporting TAS in the BSS 101. Also, in the combination of end devices considering the RTA traffic between the STA 103 and the remote device 108, the remote device 108 operates as a listener and the STA 103 operates as a talker. Details of the message sequence in this case will be described later with reference to FIG. 8 as an example of the uplink (UL) communication flow of data communication supporting TAS in the BSS 101.

[0017] Note that the above network configuration is an example and is not limited to the configuration of FIG. 1. For example, the following discussion is applicable to a network (BSS) including a large number of wireless communication devices in a wider area and various positional relationships of the wireless communication devices. Also, for example, although the schedule management device 106 sets the transmission / reception schedule, the function of this schedule management device 106 may be included in network nodes such as the AP 102 or, in some cases, the STA 103. That is, the AP 102 or the STA 103 may determine the transmission / reception schedule of the data frame.

[0018] Among devices supporting the TAS method, as will be described later with reference to FIGS. 15 and 16, TAS traffic data can be transmitted and received at strict timing. Therefore, by setting appropriate communication timing, communication can be performed in an environment with low latency and, in some cases, high reliability without interference from other devices. On the other hand, it is naturally assumed that communication devices that do not support the TAS method may exist within the network range. Even if the scheduling management device 106 transmits a control message of the TAS method to such a communication device that does not support the TAS method, the communication device cannot interpret the message. For this reason, inconveniences such as unexpected operations may occur.

[0019] In this embodiment, based on such an assumption, in order to enable each communication device to confirm whether it supports the TAS method, a method for notifying the capability information of each communication device is provided. Specifically, an information element is added to the MAC (Media Access Control) header of the wireless frame transmitted by each communication device to notify the information. Also, by selecting whether to use scheduling by the TAS method based on this information, appropriate scheduling can be performed between the transmitting device and the receiving device. Hereinafter, the configuration and processing flow of the devices that transmit and receive such notifications, and an example of the configuration of a specific frame will be described.

[0020] (Device Configuration) FIG. 2 shows the hardware configuration of the communication devices (AP, STA, and other end devices) according to this embodiment. As an example of its hardware configuration, the communication device includes a storage unit 201, a control unit 202, a functional unit 203, an input unit 204, an output unit 205, a communication unit 206, and an antenna 207.

[0021] The memory unit 201 is constituted by, for example, both a ROM (Read Only Memory) and a RAM (Random Access Memory), or either one of them. The memory unit 201 stores, for example, programs for performing various operations described later and various information such as communication parameters for wireless communication. Note that, as the memory unit 201, in addition to memories such as ROM and RAM, storage media such as flexible disks, hard disks, optical disks, magneto-optical disks, CD-ROMs, CD-Rs, magnetic tapes, non-volatile memory cards, and DVDs may be used.

[0022] The control unit 202 is constituted by, for example, one or more processors such as a CPU (Central Processing Unit), an MPU (Micro Processing Unit), an ASIC (Application Specific Integrated Circuit), a DSP (Digital Signal Processor), an FPGA (Field Programmable Gate Array), etc. Here, CPU is the initials of Central Processing Unit, and MPU is the initials of Micro Processing Unit. The control unit 202 controls the entire communication device by executing the program stored in the memory unit 201. Note that the control unit 202 may control the entire communication device in cooperation with the program stored in the memory unit 201 and an OS (Operating System).

[0023] The control unit 202 controls the functional unit 203 to execute predetermined processes such as imaging, printing, and projection. The functional unit 203 is hardware for the communication device to execute predetermined processes. For example, when the communication device is a camera, the functional unit 203 is an imaging unit and performs imaging processing. Also, for example, when the communication device is a printer, the functional unit 203 is a printing unit and performs printing processing. Also, for example, when the communication device is a projector, the functional unit 203 is a projection unit and performs projection processing. The data processed by the functional unit 203 may be data stored in the memory unit 201, or may be data communicated with other communication devices via the communication unit 206 described later.

[0024] 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 at least one of display on the screen, audio output by the speaker, vibration output, etc. Note that both the input unit 204 and the output unit 205 may be realized by one module such as a touch panel. The communication unit 206 controls wireless communication compliant with the IEEE802.11 standard series and controls IP communication. In this embodiment, the communication unit 206 can execute at least processing compliant with the IEEE802.11be standard. Also, the communication unit 206 controls the antenna 207 to transmit and receive radio signals for wireless communication. The communication device communicates contents such as image data, document data, video data, etc. with other communication devices via the communication unit 206. The wireless antennas 207 are antennas that can receive any of the sub-GHz band, 2.4GHz band, 5GHz band, and 6GHz band. The wireless antennas 207 may be physically composed of one or more antennas to realize MIMO (Multi-Input and Multi-Output) transmission and reception.

[0025] FIG. 3 shows an example of the functional configuration related to the communication of the TAS of the communication device. The communication device has, for example, a TAS capability information generation unit 301, a TAS method determination unit 302, a connection processing unit 303, a MAC frame generation unit 304, and a data transmission / reception unit 305. Note that these functional units can be realized, for example, when the control unit 202 executes a program stored in the storage unit 201. However, it is not limited to this, and for example, dedicated hardware corresponding to the functional blocks shown in FIG. 3 may be used.

[0026] The TAS capability information generation unit 301 generates information on the capabilities of the TAS of the communication device (TAS capability information) and stores it in the storage unit 201. Further, the TAS capability information generation unit 301 can reconfigure the TAS capability information stored in the storage unit 201 or update the content of the TAS capability information based on the information on the TAS received from the schedule management device 106. The TAS capability information includes a support ID indicating the scheduling method of the TAS of the communication device. The support ID is an identifier corresponding to each of a plurality of methods and is used to indicate which of the plurality of methods can be used. The capability information of the TAS will be described later with reference to FIGS. 9 to 12. Note that at least one of notifying the capability information of its own device to other communication devices and receiving the capability information of that device from other communication devices can be executed by the communication device. That is, the communication device may only receive the capability information of other communication devices and not notify the capability information of its own device to other communication devices.

[0027] The TAS mode determination unit 302 determines the TAS mode to be used for communication with the peer device according to the TAS capability information of the peer device for communication. Generally, there are two types of TAS modes: the "shaper" mode and the "policing" mode. Since these modes have different characteristics from each other, a mode corresponding to the usage (application) is used based on the difference in their characteristics. The "policing" mode is a method of reducing the delay due to queuing by dropping packets exceeding the limit rate or changing the priority of the packets. Also, in the "shaper" mode, since packets exceeding the limit rate are buffered in the I / F queue, a delay may occur. Therefore, for example, in the case of traffic using the TCP / UDP port number, a mode selection may be made such that the "shaper" mode is used for TCP and the "policing" mode is used for UDP. For example, if the available TAS mode of the STA is only "shaper", "shaper" can be adopted, and if the available TAS mode of the STA is only "policing", "policing" can be adopted. Also, when the available TAS modes of the STA are both "shaper" and "policing", either TAS mode can be determined according to the application characteristics of the data transmitted and received with the STA. For example, for the transmission and reception of data such as sensor data that is periodic but has no or not strict delay constraints, the shaper mode can be selected. Also, when an application that requires real-time operation such as a game or an industrial robot and has a constraint on the data arrival time is used, the policing mode can be selected so that the transmission and reception of periodic data considering delay control are performed. Note that the shaper mode and the policing mode are just examples, and even another mode may be used. In this case, the TAS mode determination unit 302 can select the mode to be used from among the plurality of available modes including the other mode.

[0028] The TAS capability information can include information on the TAS method according to the application characteristics of the data to be transmitted and received. For example, it is notified from a communication device to a peer device during connection or communication using management frames of the IEEE802.11 standard. Information notification using management frames will be described later with reference to FIG. 7. Also, when the number of users (end devices) accommodated in one BSS is large, the overhead can increase for the exchange of information for low-latency communication. Therefore, the type of TAS method may be changed when the number of STAs accommodated by the AP is equal to or more than a specified number. Note that the communication device may or may not notify the TAS method determined by the TAS method determination unit 302 to the peer device of the communication.

[0029] The connection processing unit 303 performs processing for establishing a connection between the STA and the AP. For example, the connection processing unit 303 of the STA transmits an Association Request frame to the AP. Also, the connection processing unit 303 of the AP transmits an Association Response frame as a response to the Association Request frame. The MAC frame generation unit 304 generates a MAC frame in which the TAS capability information generated by the TAS capability information generation unit 301 is stored as necessary. The MAC frame here is, for example, a MAC frame in wireless frames such as Beacon frames, Probe Request / Response frames, Association Request / Response frames. Also, the MAC frame may be a MAC frame of a Reassociation Request / Response frame. Note that the TAS capability information can be stored, for example, in the MAC header portion. Also, the TAS capability information and information on the TAS method are transmitted using the Capability element, which will be described later with reference to FIGS. 9 and 11. The data transmission / reception unit 305 transmits and receives TAS traffic data frames that occur periodically at strict timing according to the TAS method determined by the TAS method determination unit 302. The transmission processing of the TAS traffic data in the data transmission / reception unit 305 will be described in detail later with reference to FIGS. 15 and 16.

[0030] (Processing flow) Using FIG. 4, an example of the processing flow executed by AP102 when STA103 is connected to AP102 will be described. Note that similar processing can be executed in other combinations of STAs and APs. This processing can be started, for example, in response to the power of STA103 being turned on. Also, this processing may be started in response to an instruction to start data communication for which the TAS method should be used being given from a user or an application in STA103. Note that this processing is realized, for example, by the control unit 202 of AP102 executing a program stored in the storage unit 201.

[0031] In this process, first, the AP 102 acquires the TAS capability information of the STA 103 (S401). For example, the TAS capability information shown in FIG. 9 or FIG. 10 described later is included in the Probe Request frame transmitted by the STA 103 before connection or the Association Request frame transmitted at the time of connection. The AP 102 can acquire the TAS capability information of the STA 103 by receiving these frames and analyzing the contents. Subsequently, the TAS determination unit 302 of the AP 102 determines the TAS method to be used for delay control based on the TAS capability information of the STA 103 acquired in S401 (S402). Then, the AP 102 determines whether it can use the TAS method determined in S402 (S403). If the AP 102 determines that it cannot use the TAS method determined in S402 (NO in S403), it notifies the STA 103 that delay control cannot be executed. In this case, the AP 102 notifies the STA 103 of a management frame including the TAS capability information in which information (for example, an ID) indicating that delay control cannot be executed is set (S406). On the other hand, if the AP 102 determines that it can use the TAS method determined in S402 (YES in S403), the TAS capability information generation unit 301 of the AP 102 notifies the STA 103 of the TAS method determined in S402. In this case, the AP 102 notifies the STA 103 of a management frame including the TAS capability information in which the value indicating the TAS method determined in S402 is set (S404). Note that this value can be, for example, the TAS support ID corresponding to the TAS method. Then, the AP 102 stores the TAS capability information notified to the STA 103 in the management frame in S404 or S406 in the storage unit 201 (S405). As described above, the TAS capability information is exchanged between the AP and the STA.

[0032] Next, with reference to FIG. 5, an example of the data reception process flow executed by STA103 during communication on the downlink (DL), which is the link through which signals are transmitted from AP102 to STA103, will be described. Here, the handling of TAS traffic data (such as sensor data) will be described when a device such as the sensor device 107 serves as the talker (transmission side) and STA103 serves as the listener (reception side). For example, the TAS traffic data periodically transmitted from the sensor device 107 reaches STA103 via the bridge 104 and AP102. Note that this process is also applicable to the uplink (UL), which is the link through which signals are transmitted from STA103 to AP102. For example, the same process can be executed when AP102 receives data from STA103. In this case, STA103 in the following description is replaced with AP102.

[0033] When receiving data from AP102 (YES in S501), STA103 determines whether its own device is operating in a TAS reception mode such as policing or shaping. The determination of whether it is operating in the TAS reception mode can be made, for example, by checking the TAS support ID stored in the storage unit 201 in response to STA103 receiving a management frame from AP102. If STA103 is not operating in a TAS reception mode such as policing or shaping (NO in S502), it executes normal data reception processing (S503). On the other hand, when STA103 is operating in the TAS reception mode (YES in S502), after the data reception processing, it sets and activates the reception timer for TAS traffic data at a time interval shorter than the reception timing of the next TAS traffic data (S504).

[0034] Then, STA103 checks the reception timer for TAS traffic data to determine whether it is the reception timing of the TAS traffic data (S505). If the current time is not the reception timing of the next TAS traffic data (NO in S505), STA103 checks whether a predetermined time, such as the timing immediately before reception, has been reached (S508). If the predetermined time has not been reached (NO in S508), STA103 returns the process to S505 to check the reception timing of the TAS traffic data. On the other hand, if the predetermined time has been reached (YES in S508), STA103 executes carrier sense or the like to check the usage status of the reception channel for the corresponding TAS traffic data (S509). Here, if STA103 determines that the reception channel is busy (NO in S509), it executes collision processing for channel access (S510) to make the channel available and returns the process to S505. Also, if the reception channel is not busy and available (YES in S509), since the current time is immediately before the reception timing, STA103 reserves the reception channel for the TAS traffic data by, for example, transmitting a null packet (S511). Then, STA103 returns the process to S505.

[0035] If STA103 checks the reception timer for the TAS traffic data and determines that it is the reception timing of the TAS traffic data (YES in S505), it executes the reception process for the TAS traffic data (S506). Then, STA103 determines whether the data communication has ended (S507). If the data communication continues (NO in S507), it returns the process to S501. If the data communication has ended (YES in S507), it ends the data reception process. As described above, STA103 can receive TAS traffic data from AP102 at a predetermined reception timing (time) in the wireless communication of BSS101.

[0036] Using FIG. 6, an example of the flow of data reception processing executed by STA103 during communication in the uplink (UL) will be described. Here, the handling of TAS traffic data (such as remote control data) when STA103 becomes the talker (transmitting side) and a device such as remote device 108 becomes the listener (receiving side) will be described. For example, TAS traffic data periodically transmitted from STA103 reaches remote device 108 via AP102 and bridge 104. Note that this processing is also applicable in the downlink (DL). For example, when AP102 transmits data to STA103, the same processing can be executed. In this case, STA103 in the following description is read as AP102.

[0037] STA103 continuously monitors whether transmission data has been generated, for example, by receiving a data transmission request from a control application of remote device 108 installed in its own device (S601). Then, when STA103 detects the generation of transmission data (YES in S601), it determines whether its own device is operating in a TAS transmission mode such as policing or shaping. The determination of whether it is operating in a TAS transmission mode can be made, for example, by checking the TAS support ID stored in storage unit 201 in response to STA103 receiving a management frame from AP102. If STA103 is not operating in a TAS transmission mode such as policing or shaping (NO in S602), it executes normal data transmission processing (S603). On the other hand, when STA103 is operating in a TAS transmission mode (YES in S602), after the data transmission processing, it sets and starts a transmission timer for TAS traffic data at a time interval shorter than the transmission timing of the next TAS traffic data (S604).

[0038] Then, STA103 checks the transmission timer for TAS traffic data to determine whether it is the transmission timing of TAS traffic data (S605). If the current time is not the transmission timing of the next TAS traffic data (NO in S605), STA103 checks whether a predetermined time, such as the timing immediately before transmission, has been reached (S608). If the predetermined time has not been reached (NO in S608), STA103 returns the process to S605 and checks the transmission timing of TAS traffic data. On the other hand, if the predetermined time has been reached (YES in S608), STA103 executes carrier sense, etc., and checks the usage status of the transmission channel for the corresponding TAS traffic data (S609). Here, if STA103 determines that the transmission channel is in a busy state (NO in S609), it executes channel access conflict processing (S610) to make the channel available and returns the process to S605. Also, if the transmission channel is not busy and available (YES in S609), since the current time is immediately before the transmission timing, STA103 reserves the transmission channel for the TAS traffic data by, for example, transmitting a null packet (S511). Then, STA103 returns the process to S605.

[0039] If STA103 checks the transmission timer for TAS traffic data and determines that it is the transmission timing of TAS traffic data (YES in S605), it executes the transmission process for TAS traffic data (S606). The TAS traffic data transmission process will be described later with reference to FIGS. 15 and 16. After that, STA103 determines whether the data communication has ended (S607). If the data communication continues (NO in S607), it returns the process to S601. If the data communication has ended (YES in S607), it ends the data transmission process. As described above, STA103 can transmit TAS traffic data to AP102 at a predetermined transmission timing (time) in the wireless communication of BSS101.

[0040] In the above manner, STA103 can transmit TAS traffic data to AP102 at a predetermined transmission timing. By executing the processes of FIGS. 5 and 6 between the STA and the AP, the TAS traffic data is periodically transmitted at a preset time. By operating so that communication is performed at an appropriately preset time based on the network topology, unnecessary waiting time is reduced, and thus low-latency communication can be performed.

[0041] Next, with reference to FIG. 7, an example of the message flow between the AP 102 and the STA 103 during downlink (DL) communication will be described. This process is executed, for example, when TAS traffic data from a device such as the sensor device 107 operating as a talker is received by the listener STA 103 via the bridge 104 and the AP 102. First, the STA 103 executes a scan process to acquire the network information of the AP 102. For example, the AP 102 notifies devices within the range of the BSS 101 of a Beacon frame (M701) including network information. Here, the AP 102 may notify a Beacon frame including the TAS method capability information described later with reference to FIG. 9 or FIG. 10. The STA 103 may transmit a Probe Request frame (M702) to inquire about the network information of the AP 102 and acquire information from the AP 102. In response to the Probe Request frame (M702), the AP 102 transmits a Probe Resoponse frame (M703). The STA 103 can receive, for example, the Beacon frame (M701) transmitted by the AP 102 and acquire the network information of the AP 102 from the Beacon frame. Also, the STA 103 may actively transmit a Probe Request frame (M702) and receive a Probe Response frame (M703) from the AP 102 to acquire the network information of the AP 102. At this time, the Beacon frame (M701) and the Probe Response frame (M703) include information indicating whether the AP 102 supports the TAS method as TAS capability information. Also, when supporting the TAS method, the TAS capability information included in the frame can indicate whether only the policing method is supported, only the shaper method is supported, or both methods are supported. Also, the STA 103 may include the TAS capability information of the STA 103 in the Probe Request frame (M702). Through these processes, the STA 103 and the AP 102 can exchange TAS capability information.However, at this point, the TAS capability information is not exchanged, and the TAS capability information may be exchanged in another message such as the Association Request / Response frame described later.

[0042] After the scanning process, STA103 sends an Association Request frame (M704) to AP102 to connect to BSS101. In response to the Association Request frame (M704), AP102 sends an Association Response frame (M705) indicating the connection result of STA103 to STA103. The TAS capability information may be included in the Association Request frame and the Association Response frame. Also, STA103 may determine the TAS capability information to be included in the Association Request frame based on the TAS capability information of AP102 obtained in the scanning process, etc. In one example, when STA103 can use both the shaper method and the polishing method, depending on the application of communication by the TAS method, STA103 may select the method to be used and notify AP102 of information indicating that only the selected method can be used. For example, when the talker is the sensor device 107, STA103, which can use both methods, may send an Association Request frame (M704) including TAS capability information indicating that the device itself can only use the shaper method to AP102. Also, when the listener is the remote device 108, STA103, which can use both methods, may send an Association Request frame (M704) including TAS capability information indicating that the device itself can only use the polishing method to AP102. Similarly, AP102 may also determine the TAS capability information to be included in the Association Response frame based on the TAS capability information of STA103 included in the Association Request frame, etc. In this way, the TAS capability information is exchanged before the connection between AP102 and STA103 is established.

[0043] After that, after confirming that TAS communication is possible, AP102 transmits a management frame (M706) to STA103. This management frame includes information indicating, for example, that the shaper method should be used for TAS capability information during DL data communication. Further, this management frame may include information indicating, for example, a schedule for data to be transmitted and received in the TAS method. After that, the listener STA103 periodically receives TAS traffic data (M707) from the sensor device 107, which is a talker, via AP102. STA103 executes, for example, the data reception process described with reference to FIG. 5 to receive the TAS traffic data (M707). Also, AP102 executes, for example, the data transmission process described with reference to FIG. 6 to transmit the TAS traffic data (M707).

[0044] Next, with reference to FIG. 8, an example of the message flow between AP102 and STA103 during UL communication will be described. This process is executed when the STA103, which is a talker, transmits TAS traffic data received by a device such as the remote device 108 operating as a listener via the AP102 and the bridge 104. Here, the messages related to the scan processes of M701 to M703, the messages related to the STA connection processes of M704 to M705, and the management frame of M706 are the same as those in the case of FIG. 7. Here, since the listener is the remote device 108, the STA103 capable of supporting both methods can include in the Association Request frame the TAS capability information indicating that the own device can use only the policing method and transmit it to the AP102. The management frame (M706) includes information indicating, for example, that the policing method should be used in the TAS capability information during UL data communication. Also, this management frame can include information indicating, for example, the schedule for data to be transmitted and received in the TAS method. Thereafter, the talker STA103 periodically transmits mTAS traffic data (M801) to the remote device 108, which is a listener, via the AP102. The STA103 executes, for example, the data transmission process described with reference to FIG. 6 to transmit the TAS traffic data (M801). Also, the AP102 executes, for example, the data reception process described with reference to FIG. 5 to receive the TAS traffic data (M801).

[0045] In this way, the AP102 and the STA103 can exchange the TAS capability information of their own devices and determine whether to perform communication in the TAS method in subsequent communication and which of the shaper method and the policing method to use. As a result, by executing processes such as those described later with reference to FIGS. 15 and 16, wireless communication can be performed by scheduling according to time, and low-latency communication can be achieved.

[0046] Next, a first example of TAS capability information will be described with reference to FIG. 9. In the present embodiment, the name of this TAS capability information is referred to as "TAS capability element", but it is not limited thereto. For example, other names such as "TAS Element" may be used. The TAS capability element has the same configuration as other Information Elements defined in the IEEE802.11 standard. That is, the TAS capability element is composed of an Element ID field 901 that identifies the Element, a Length field 902 that indicates the data length of the Element, and information unique to the Element. The TAS capability element includes a TAS capability Info field 903 as information unique to the Element. The TAS capability element is included in MAC frames such as, for example, Beacon frames, Probe Request / Response frames, and Association Request / Response frames. Note that the TAS capability element may be included in the MAC frame of the Reassociation Request / Response frame. The TAS capability Info field 903 includes information indicating whether the sender of this TAS capability element can use the TAS method and the TAS method that can be used. This information is represented by, for example, 2 bits. An example of the information represented by 2 bits will be described later with reference to FIG. 11. Here, it is described that the TAS capability Info field 903 has a size of 1 octet (8 bits), but it is not limited thereto. The name of the field, the position and size of the bits are not limited to the example of FIG. 9, and the same information may be stored with different field names, different orders, and different sizes.

[0047] Using FIG. 10, a second example of TAS capability information will be described. Also in this TAS capability element, similar to the example of FIG. 9, it includes an Element ID field 901 and a Length field 902. Further, this information can be included in the MAC frame of each of the above-described wireless frames instead of the information of FIG. 9. The TAS capability element of FIG. 10 can be the same as the TAS capability element of FIG. 9 except for the TAS capability Info field 1001. However, note that since the size of the TAS capability Info field is different, the value stored in the Length field 902 is different between FIG. 9 and FIG. 10. In the example of FIG. 10, the TAS capability Info field 1001 is composed of information indicating the availability of each TAS method for the primary channel in addition to the availability of using the TAS method. The primary channel is a main channel for supporting a multi-link technology that uses a plurality of wireless channels simultaneously, and is used for the capability information of other wireless links and the transmission / reception control of messages related to connection and disconnection. Note that the relationship between the TAS method capability information and the primary channel will be described later with reference to FIG. 14. Note that hereinafter, the primary channel may be referred to as "PCH".

[0048] The TAS support field 1002 contains information indicating whether the sender of this TAS capability element can use the TAS method and which TAS methods are available. This information is represented by, for example, 2 bits. An example of the information represented by 2 bits will be described later with reference to FIG. 11. The PCH1 availability field 1003 to the PCH9 availability field 1011 are fields indicating the availability of the TAS method for each of the primary channels 1 to 9. The value stored in this field and what it indicates will be described later with reference to FIG. 12. The Reserve field 1012 is a 5-bit unused area for future expansion. Here, an example is shown where the TAS capability Info field 1001 is 2 octets (16 bits), but it is not limited to this. For example, similar information may be indicated by different field names, different bit positions, and different field sizes. Note that in this embodiment, the name of the element in FIG. 10 is the TAS capability element, but it is not limited to this, and other names such as the TAS Multi-Link Element may be used, for example.

[0049] Using FIG. 11, an example of information indicating whether the sender of the TAS capability information in FIG. 9 or FIG. 10 can use the TAS method and the TAS method that can be used will be described. Note that whether the TAS method can be used and the TAS method that can be used may be collectively referred to as the TAS support status. In FIG. 11, the D-bit value 1101 indicates the 2-bit data bit (D-bit) value stored in the TAS capability Info field 903 of FIG. 9 or the TAS support field 1002 of FIG. 10. Note that the bit string indicated by this D-bit may be a TAS support ID. The content 1102 of the TAS support indicates the content corresponding to each TAS support ID. For example, the bit value "00" of the D-bit value 1101 indicates that it does not correspond to the TAS method (not available). Also, the bit value "01" of the D-bit value 1101 indicates that it corresponds to the TAS method, but only the shaper method can be used. Also, the bit value "10" of the D-bit value 1001 indicates that it corresponds to the TAS method, but only the polishing method can be used. The bit value "11" of the D-bit value 1001 indicates that it corresponds to the TAS method and both the polishing method and the shaper method can be used. Note that the set values for each information element are not limited to this example, and similar information may be indicated by different field names and different values.

[0050] FIG. 12 shows an example of values stored in each of the PCH1 availability fields 1003 to PCH9 availability fields 1011 in FIG. 10 and the corresponding content. In the PCH1 availability fields 1003 to PCH9 availability fields 1011, E bits 1201 are stored, which are configured such that the indicated content 1202 varies depending on the combination with the value indicated in the TAS support field 1002. For example, when the 2 bits stored in the TAS support field 1102 indicate a polishing method (D-bit value "10") or a shaper method (D-bit value "01"), respectively, the E bit represents the availability of each TAS method. For example, when the E bit is set to "1", it indicates that the TAS method indicated by the D-bit value can be used, and when the E bit is set to "0", it may indicate that the TAS method indicated by the D-bit value cannot be used. Note that this is just an example, and when the E bit is set to "0", it may indicate that the TAS method indicated by the D-bit value can be used, and when the E bit is set to "1", it may indicate that the TAS method indicated by the D-bit value cannot be used. Further, when the 2 bits stored in the TAS support field 1102 indicate that both the polishing method and the shaper method can be used (when the D-bit value is "11"), either method can be specified by one bit of the E bit. For example, when the E bit is set to "1", the polishing method is specified, and when the E bit is set to "0", the shaper method is specified. Also, it may be such that when the E bit is set to "0", the polishing method is specified, and when the E bit is set to "1", the shaper method is specified.

[0051] Here, with reference to FIG. 13, an example of the processing flow executed by AP102 when notifying the TAS capability information in FIG. 10 by a Beacon frame will be described. This processing starts, for example, when the power of AP102 is turned on or when the data collection process in the TAS method is started in AP102. Note that this processing can be realized, for example, when the control unit 202 of AP102 executes a program stored in the storage unit 201.

[0052] First, AP102 determines whether it is set to a mode in which multi-channel TAS information as shown in FIG. 10 is included in the Beacon frame (S1301). If AP102 determines that the setting of the mode in which multi-channel TAS information is included in the Beacon frame has not been performed (NO in S1301), it executes the setting process of the conventional Beacon frame (S1302). Then, AP102 notifies the Beacon frame obtained by the setting process in S1302 within BSS1 (S1306). Note that in this case, AP102 may transmit a Beacon frame including TAS information as shown in FIG. 9, for example.

[0053] When the setting of the mode for including multi-channel TAS information in the Beacon frame is performed in AP102 (NO in S1301), based on the TAS method capability information stored in S405 of FIG. 4, it determines whether each of a plurality of PCHs can be used (S1303). For this purpose, AP102 transmits an RTS (Request To Send) message. Then, when STA103 receives the RTS on each PCH, it performs carrier sense on that PCH. When the PCH is not in a busy state, after the elapse of the SIFS (Short Inter Frame Space) period, STA103 transmits a CTS (Clear To Send) message to AP102. AP102 checks whether CTS is received for each of the PCHs to which it has transmitted the RTS, and recognizes the PCH for which reception has been confirmed as an available PCH. At this time, the TAS capability information generation unit 301 of AP102 recognizes that TAS communication cannot be used for the PCH for which CTS reception could not be confirmed.

[0054] Then, the TAS capability information generation unit 301 updates the information on whether the TAS method can be used for each of the PCHs in the TAS capability information. When AP102 completes the process of S1303 for all of the plurality of available PCHs (YES in S1304), it stores the confirmed TAS capability information in the storage unit 201 and sets the TAS capability information in the Beacon frame (S1305). Then, AP102 notifies the BSS101 of the Beacon frame including the TAS capability information (S1306). Note that the Beacon frame including the TAS capability information shown in FIG. 9 or FIG. 10 may be notified to a plurality of PCHs.

[0055] As described above, AP102 can transmit by including information of a plurality of PCHs in a Beacon frame. Thereby, for example, STA103 can select and use a PCH that enables communication considering delay control based on TAS capability information. Also, for example, among the PCHs with TAS capability information, a PCH having a signal bandwidth greater than or equal to a predetermined width may be selected, or a PCH with a larger signal bandwidth may be preferentially selected. Further, among the PCHs with TAS capability information, a PCH having a received electric field strength or a signal-to-noise ratio (SNR) greater than or equal to a predetermined value may be selected, or a PCH with good values of these may be preferentially selected. Also, among the PCHs with TAS capability information, a PCH having a channel transmission capacity calculated from the bandwidth and SNR greater than or equal to a predetermined value may be selected, or a PCH with a larger capacity may be preferentially selected. Also, among the PCHs with TAS capability information, the PCH to be used may be selected based on free channel information inferred from the channel usage status for a certain period. Also, conditions other than these PCH selection conditions may be used. Further, one or more of the above-described selection conditions may be combined and used.

[0056] Subsequently, PCH1 to PCH9 will be described with reference to FIG. 14. PCH1 to PCH9 each indicate a plurality of PCHs that can be used in the 5 GHz band. For example, PCH1 to PCH9 are each frequency channels with a bandwidth of 20 MHz and channel numbers 36, 44, 52, 60, 100, 108, 116, 124, and 132. Here, the 5 GHz frequency band has been described, but the same discussion can be applied to the 2.4 GHz band or the 6 GHz band. Also, the above discussion is not limited to PCHs and may be applied to any other frequency channels.

[0057] Using FIG. 15, the traffic data transmission process of Time-Aware Schedule (TAS) in the AP and STA according to this embodiment will be described. As an example, the AP 102 and the STA 101 have a configuration as shown in FIG. 15 for the TAS traffic data transmission process. In the configuration of FIG. 15, the application 1501 receives the TAS method information determined by the above-described TAS method determination unit 302 until it reaches the state during the communication of the TAS traffic data. Then, in order to execute the transmission process according to this TAS method information, the application 1501 prepares for the data transmission request from the MAC frame generation unit 304. The traffic classification function 1503 receives the traffic data with priority information added from the MAC frame generation unit 304 and maps the traffic data with time constraints to the TAS queue (Q0) 1504. Also, the traffic classification function 1503 maps the best-effort traffic data other than the TAS traffic data to each of the BE queues (Q1-Q4) 1505. The TAS time gate control function 1502 temporarily stops / resumes each of the TAS time gate (G0) 1506 and the various BE time gates (G1-G4) 1507 to execute the output control of the traffic data accumulated in each queue. The TAS time gate control function 1502 executes control to protect the TAS traffic data while avoiding competition for channel access, for example, as described later.

[0058] Using FIG. 16, the transmission process of TAS traffic data using a plurality of time gates (G0 to G4) will be described. Curve 1601 shows the OPEN / CLOSE state of the time gate (G0) 1506 for TAS, and curves 1602 to 1605 show the OPEN / CLOSE states for each of the various BE time gates (G1 - G4) 1507. In these curves, "1" indicates OPEN and "0" indicates CLOSE. When a time gate is opened, the data in the queue corresponding to that time gate can be output through that time gate. Guard time 1606 indicates the time Tg that blocks the transmission of all gates. This guard time 1606 can prevent various BE traffic data from colliding with TAS traffic data. Timing 1607 indicates the timing To at which the time gate (G0) 1506 for TAS is periodically opened. Timing To occurs every period 1608. This period 1608 is defined by the interval Tp at which data is transmitted at a strict and periodic timing specified by the transmission request of TAS traffic data. Period 1609 is the time interval Tc during which the time gate (G0) 1506 of the TAS queue (Q0) 1504 is opened, indicating the period during which TAS traffic data is transmitted at a strict and periodic timing.

[0059] The TAS time-gate control function 1502 performs gate control according to the transmission / reception schedule of TAS traffic data that is periodically repeated. The TAS time-gate control function 1502 can close or open each time-gate, for example, by inputting bit 0 or 1 for each time-gate. The TAS time-gate control function 1502 can indicate the OPEN / CLOSE of, for example, five time-gates G0 to G4 by a 5-bit bit string. And each time-gate can extract the bit corresponding to itself from this bit string and perform CLOSE / OPEN control. Also, the TAS time-gate control function 1502 may output 1-bit information indicating whether to close or open each time-gate for each time-gate. Here, the state of each time-gate for each bit string will be described. Note that the bit string here indicates the OPEN / CLOSE of each time-gate in the order of "G0·G1·G2·G3·G4". The bit string "00000" indicates the data block state. This state corresponds to the guard time 1606, and all time-gates (G0 - G4) are closed. The bit string "10000" indicates the state where only the TAS time-gate (G0) 1506 is open, and this state corresponds to the period 1609. Also, the bit string "01111" is the state where various BE time-gates (G1 - G4) 1507 are open, and corresponds to, for example, the period excluding the period 1609 and the guard time 1606 in the cycle 1608. Thus, the TAS time-gate control function 1502 can control the CLOSE / OPEN of each time-gate by a 1-bit indicator.

[0060] In this way, by using the time-gates (G0 to G4), at the transmission timing of the TAS traffic data to be transmitted at strict timing, the TAS traffic data can be processed smoothly while blocking the data that should not be transmitted.

[0061] The present invention can also be realized by supplying a program that realizes one or more functions of the above-described embodiment to a system or apparatus via a network or a storage medium and causing one or more processors in a computer of the system or apparatus to read and execute the program. Further, it can also be realized by a circuit (for example, ASIC) that realizes one or more functions.

[0062] The invention is not limited to the above-described embodiment, and various changes and modifications are possible without departing from the spirit and scope of the invention. Therefore, the claims are attached to disclose the scope of the invention.

Description of Reference Numerals

[0063] 101 and 111: BSS, 102 and 112: AP, 103 and 113: STA, 104: Bridge, 105: Network control device, 106: Scheduling device, 107: Sensor device, 108: Remote device

Claims

Claim 1. A communication device operating as an access point, comprising: communication means for transmitting a wireless frame compliant with the IEEE 802.11be standard to another communication device; the MAC (Media Access Control) frame of the wireless frame to be transmitted includes an information element indicating whether the communication device supports a communication method that restricts competition for channel access based on time during a preset period and performs communication with low latency; the wireless frame including the MAC frame including the information element indicating whether the communication device supports the communication method is at least one of a Beacon frame, a Probe Response frame, an Association Response frame, and a Reassociation Response frame; A communication device characterized by the above.

2. The communication device according to claim 1, wherein the information element includes information indicating which of a plurality of methods included in the communication method can be used by the communication device that transmitted the wireless frame.

3. The communication device according to claim 1, wherein the information element includes one ID subfield and a plurality of fields indicating whether the communication method can be used for each of a plurality of frequency channels.

4. The MAC frame includes a first value indicating which of a plurality of methods of the communication method can be used by the communication device that transmitted the wireless frame, and a second value for each of the plurality of frequency channels. The communication device according to claim 3, wherein the combination of the first value and the second value indicates whether the communication method can be used, and which of the plurality of methods can be used when the communication method can be used.

5. The communication device according to claim 1, wherein the MAC frame includes an information element including one ID subfield and a plurality of subfields related to communication using the communication method.

6. The communication device according to claim 1, wherein the information element indicating whether the communication device supports the communication method is transmitted to the other communication device before a connection with the other communication device is established.

7. The communication device according to claim 1, characterized in that it has printing means.

8. The communication device according to claim 1, characterized in that it has imaging means for performing imaging processing.

9. The information element indicating whether the communication device supports the communication method is transmitted to the other communication device or received from the other communication device before the connection with the other communication device is established, The communication device according to claim 1, characterized in that

10. The information element indicating whether the communication device supports the communication method includes information indicating a schedule for transmitting or receiving a data frame to the other communication device, The communication device according to claim 1, characterized in that

11. The information element indicating whether the communication device supports the communication method is used for transmitting or receiving the data frame, which is set based on the method that the other communication device can use and the method that the communication device can use. The communication device according to claim 10, characterized in that it includes information on the method.

12. When the communication device cannot use the communication method, the information element includes information indicating that the communication method cannot be used, The communication device according to claim 1, characterized in that

13. The communication method is a Time-Aware Schedule (TAS) method defined by the IEEE 802.1Qbv standard, The communication device according to claim 1, characterized in that

14. A control method executed by a communication device operating as an access point, including transmitting a wireless frame compliant with the IEEE 802.11be standard to another communication device, The MAC (Media Access Control) frame of the wireless frame to be transmitted includes an information element indicating whether the communication device supports a communication method that restricts competition for channel access based on time during a preset period and performs communication with low latency. The wireless frame including the MAC frame including the information element indicating whether the communication device supports the communication method is at least one of a Beacon frame, a Probe Response frame, an Association Response frame, and a Reassociation Response frame. A control method characterized by the following.

15. A program for causing a computer to function as the communication device according to any one of Claims 1 to 13.

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