Communication device, control method, and program

Abstract

To realize highly reliable and low-latency communication.SOLUTION: A communication device transmits or receives a wireless frame that complies with the IEEE 802.11 standard series to another communication device or from another communication device. Here, a Media Access Control (MAC) frame of a wireless frame includes information regarding time-based scheduling of a data frame for a device that has transmitted the wireless frame.SELECTED DRAWING: Figure 4

Description

[Technical Field]

[0001] The present invention relates to information sharing techniques for scheduling functions in wireless communications. [Background technology]

[0002] The IEEE 802.11 standard series is known as a wireless LAN (Local Area Network) communication standard formulated by the Institute of Electrical and Electronics Engineers (IEEE). The IEEE 802.11 standard series includes IEEE 802.11a / b / g / n / ac / ax standards, and new standards are continuously being studied that will improve peak throughput and frequency utilization efficiency compared to previous standards. For example, the IEEE 802.11ax standard can achieve high peak throughput by using OFDMA (Orthogonal Frequency Division Multiple Access) and the like (see Patent Document 1). [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Japanese Patent Application Publication No. 2018-050133 Summary of the Invention [Problem to be solved by the invention]

[0004] In recent years, the IEEE802.11be standard has been developed as a new standard aiming to further improve throughput and frequency utilization efficiency. One of the targets of this development work is to achieve highly reliable and low-latency (RLL) communications.

[0005] The present invention provides a communication control technology for realizing such highly reliable and low-latency communication. [Means for solving the problem]

[0006] A communication device according to one aspect of the present invention has a communication means for transmitting or receiving wireless frames conforming to the IEEE802.11 standard series to or from other communication devices, and is characterized in that the MAC (Media Access Control) frame of the wireless frame contains information regarding time-based scheduling of data frames by the device that transmitted the wireless frame. [Effects of the Invention]

[0007] According to the present invention, highly reliable and low-delay communication can be achieved. [Brief explanation of the drawings]

[0008] [Figure 1] FIG. 1 is a diagram illustrating an example of a network configuration according to an embodiment of the present invention. [Figure 2] FIG. 2 illustrates an example of a hardware configuration of a communication device. [Figure 3] FIG. 2 illustrates an example of a functional configuration of a communication device. [Figure 4] FIG. 10 is a diagram illustrating an example of the flow of processing executed by an AP when a STA is connected. [Figure 5] FIG. 10 is a diagram illustrating an example of the flow of a data reception process. [Figure 6] FIG. 10 is a diagram illustrating an example of the flow of a data transmission process. [Figure 7] 10 is a diagram illustrating an example of the flow of messages transmitted and received between an AP and a STA during DL communication. FIG. [Figure 8] 10 is a diagram showing an example of the flow of messages transmitted and received between an AP and a STA during UL communication. FIG. [Figure 9] FIG. 10 is a diagram illustrating an example of the configuration of TAS capability information. [Figure 10] FIG. 10 is a diagram illustrating an example of the configuration of TAS capability information. [Figure 11] FIG. 10 is a diagram illustrating setting values ​​of TAS capability information. [Figure 12] FIG. 10 is a diagram illustrating setting values ​​of TAS capability information. [Figure 13]10 is a diagram illustrating an example of a processing flow when TAS capability information is broadcast using a Beacon frame. [Figure 14] FIG. 1 is a diagram illustrating an example of a primary channel in the 5 GHz band. [Figure 15] FIG. 10 is a diagram illustrating TAS traffic processing. [Figure 16] FIG. 10 is a diagram illustrating TAS traffic processing. DETAILED DESCRIPTION OF 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 scope of the invention claimed. Although multiple features are described in the embodiments, not all of these multiple features are necessarily essential to the invention, and multiple features may be combined arbitrarily. Furthermore, in the accompanying drawings, the same reference numerals are used to designate the same or similar components, and redundant explanations will be omitted.

[0010] (Network configuration) FIG. 1 shows an example of a network configuration according to this embodiment. Parts of the network in FIG. 1 include a wireless communication network (BSS 101) in which wireless communication services are provided by AP 102 and a wireless communication network (BSS 111) in which wireless communication services are provided by AP 112. AP is an acronym for access point, and BSS is an acronym for basic service set. A wireless station (STA) can connect to an AP whose coverage area covers the location of the station and participate in the BSS provided by that AP. The STA can transmit and receive wireless frames within the network in which it participates. In the example of FIG. 1, the STA 103 is located within the coverage area of ​​both AP 102 and AP 112, and can therefore connect to either of these APs and participate in either BSS 101 or BSS 111. Such an environment in which the coverage areas of multiple APs overlap may be referred to as an OBSS environment. That is, in this embodiment, the STA 103 is located in an OBSS environment. It is assumed here that STA 103 is connected to AP 102, and that a signal from AP 112 may be an interfering signal for STA 103. Furthermore, since STA 113 is within the communication range of AP 112, it can connect to AP 112 and participate in BSS 111.

[0011] Furthermore, AP 102 and AP 112 are connected by a bridge 104. The AP and the bridge, and the bridge and another bridge, may be connected by, for example, a wired line. However, a wireless line may be used in at least a part of the section where AP 102 and AP 112 are connected. With this configuration, a single network may be formed in which the wireless network formed by AP 102 and AP 112 and the wired network formed by the bridge 104 and the like are integrated.

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

[0013] In such a network system, it is essential that, for example, the STA 103 can reliably receive data from the sensor device 107 at regular intervals and that a remote operation instruction signal from the STA 103 can reach the remote device 108 with low latency. However, in a conventional wireless LAN, a device transmitting data checks whether wireless resources are in use in the vicinity and transmits a signal during the period when the wireless resources are not in use. Therefore, communication is not possible if the wireless resources are being used by another device. Therefore, some kind of communication control function must be introduced to ensure regular transmission and reception of signals and enable low-latency communication. One solution to this problem is to introduce the Time-Aware Schedule (TAS) method defined in the IEEE802.1Qbv standard, which enables appropriate transmission and reception of specific data, such as data with strict latency requirements. The TAS method is a time-aware scheduling method that transmits and receives signals at regular times based on the time of day. In this embodiment, communication using the TAS method is performed in a network to appropriately perform regular-period communication and low-latency communication. For this reason, it is assumed that the AP 102, STA 103, STA 113, bridge 104, and other devices support the TAS method. However, it is assumed that the AP 112 does not support this TAS method. It is also assumed that devices other than the AP 112 support the standard (IEEE802.1AS) that synchronizes with the same reference clock within the network.

[0014] Hereinafter, the predetermined data that is scheduled and transmitted and received using the TAS method will be referred to as TAS traffic data. Here, TAS traffic data is packet data that is transmitted and received while taking into consideration delay control between end devices. To control such transmission and reception, the network further includes a network management device 105 and a schedule management device 106. The network management device 105 performs delay control for the TAS traffic data. The schedule management device 106 performs schedule management for 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. The AP 102 also exchanges TAS information with the schedule management device 106, which manages the schedule for the entire network.

[0015] The network management device 105 collects requirements for time-based scheduling (TAS) from end devices such as the AP 103, the sensor device 107, and the remote device 108. These requirements specify, for example, which devices transmit and receive TAS traffic data, the time interval at which data is transmitted, and the allowable delay. The network management device 105 detects the network topology of the network under its control. Here, the network topology may refer to the relationship between which devices in the network are connected. Note that "connected" here may refer to a state in which devices are physically connected directly, or to a state in which a logical link is established regardless of the physical connection configuration. Based on the collected requirements, the network management device 105 calculates end-to-end paths between end devices for each TAS traffic data transmission and reception to be performed. Based on the calculation results, the network management device 105 determines the timing at which each device should transmit a signal, performs scheduling, and notifies the schedule management device 106 of the schedule results.

[0016] The schedule management device 106 transmits a message including the TAS information to the bridge 104 and the AP 102 to set a transmission / reception schedule. The schedule management device 106 also notifies the end devices (STA 103, sensor device 107, and remote device 108) of the TAS information. At this time, the end devices (STA 103, sensor device 107, and remote device 108) each operate as a talker (data transmitter) or a listener (data receiver) depending on the transmission schedule for TAS traffic within the network. For example, in a combination of end devices taking into account the RTA traffic of 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 using FIG. 7 as an example of the flow of downlink (DL) communication for data communication supporting TAS in the BSS 101. In addition, in a combination of end devices taking into account the RTA traffic of STA 103 and remote device 108, remote device 108 operates as a listener and 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 flow of uplink (UL) data communication for supporting TAS in BSS 101.

[0017] Note that the above-described network configuration is an example and is not limited to the configuration in FIG. 1. For example, the following discussion can be applied to a network (BSS) that includes a large number of wireless communication devices over a wider area, and to the positional relationships of various wireless communication devices. Also, for example, schedule management device 106 sets the transmission and reception schedule, but the function of this schedule management device 106 may be included in a network node such as AP 102, or in some cases, in STA 103. In other words, AP 102 or STA 103 may determine the transmission and reception schedule for data frames.

[0018] Between devices that support the TAS method, TAS traffic data can be transmitted and received with strict timing, as will be described later with reference to Figures 15 and 16. Therefore, by setting appropriate communication timing, communication can be performed in a low-latency, and in some cases, highly reliable environment free from 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 range of the network. Even if the schedule management device 106 transmits a TAS-based control message to such a communication device that does not support the TAS method, the communication device will not be able to interpret the message. This can lead to inconveniences such as unexpected operations being performed.

[0019] Based on this assumption, this embodiment provides a method for notifying capability information of each communication device to enable confirmation of whether or not each communication device supports the TAS method. Specifically, information is notified by adding an information element to the MAC (Media Access Control) header of the wireless frame transmitted by each communication device. Furthermore, by selecting whether or not to use scheduling based on the TAS method based on this information, appropriate scheduling can be performed between the transmitting device and the receiving device. Below, the configuration and processing flow of the device that transmits and receives such notification, as well as a specific example of a frame configuration, are described.

[0020] (Device configuration) 2 shows the hardware configuration of a communication device (AP, STA, and other end devices) according to this embodiment. The communication device includes, as an example of its hardware configuration, 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 an antenna 207.

[0021] The storage unit 201 is configured with, for example, a ROM (Read Only Memory) and / or a RAM (Random Access Memory). The storage unit 201 stores, for example, programs for performing various operations described below and various information such as communication parameters for wireless communication. Note that, in addition to memories such as ROM and RAM, the storage unit 201 may also use storage media such as a flexible disk, a hard disk, an optical disk, a magneto-optical disk, a CD-ROM, a CD-R, a magnetic tape, a non-volatile memory card, or a DVD.

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

[0023] The control unit 202 controls the functional unit 203 to perform predetermined processing such as capturing images, printing, and projection. The functional unit 203 is hardware that enables the communication device to perform predetermined processing. For example, if the communication device is a camera, the functional unit 203 is an imaging unit that performs imaging processing. Also, for example, if the communication device is a printer, the functional unit 203 is a printing unit that performs printing processing. Also, for example, if the communication device is a projector, the functional unit 203 is a projection unit that performs projection processing. The data processed by the functional unit 203 may be data stored in the storage unit 201, or may be data communicated with another communication device via the communication unit 206, which will be described later.

[0024] The input unit 204 accepts various operations from the user. The output unit 205 outputs various types of data to the user. Here, output by the output unit 205 includes at least one of display on a screen, audio output by a speaker, vibration output, and the like. Note that both the input unit 204 and the output unit 205 may be implemented in a single module, such as a touch panel. The communication unit 206 controls wireless communication compliant with the IEEE 802.11 standard series and IP communication. In this embodiment, the communication unit 206 can execute processing compliant with at least the IEEE 802.11be standard. The communication unit 206 also controls the antenna 207 to transmit and receive wireless signals for wireless communication. The communication device communicates content such as image data, document data, and video data with other communication devices via the communication unit 206. The wireless antenna 207 is an antenna capable of receiving signals in the sub-GHz band, 2.4 GHz band, 5 GHz band, or 6 GHz band. The radio antenna 207 may be physically configured with one or more antennas to realize MIMO (Multi-Input and Multi-Output) transmission and reception.

[0025] 3 shows an example of a functional configuration related to TAS communication of a 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, by the control unit 202 executing a program stored in the storage unit 201. However, this is not limiting, 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 capabilities related to the TAS of the communication device (TAS capability information) and stores it in the storage unit 201. Furthermore, the TAS capability information generation unit 301 may reconfigure the TAS capability information stored in the storage unit 201 or update the content of the TAS capability information based on information related to the TAS received from the schedule management device 106. The TAS capability information includes a support ID indicating a TAS scheduling method of the communication device. The support ID is an identification corresponding to each of a plurality of methods and is used to indicate which of the plurality of methods is usable. The TAS capability information will be described later with reference to FIGS. 9 to 12. A communication device may at least either notify another communication device of its own capability information or receive the capability information of the communication device from the other communication device. In other words, a communication device may only receive the capability information of another communication device without notifying the other communication device of its own capability information.

[0027] The TAS method determination unit 302 determines the TAS method to be used for communication with the remote device based on the TAS capability information of the remote device. There are generally two types of TAS methods: "shaper" and "policing." Because these methods have different characteristics, a method appropriate for the intended use (application) is used based on these differences. The "policing" method reduces queuing delays by dropping packets that exceed a limited rate or by changing the priority of packets. The "shaper" method buffers packets that exceed a limited rate in an I / F queue, which can cause delays. Therefore, for traffic using TCP / UDP port numbers, for example, the "shaper" method may be used for TCP and the "policing" method may be used for UDP. For example, if the only TAS method available to the STA is "shaper," then "shaper" may be used; and if the only TAS method available to the STA is "policing," then "policing" may be used. Furthermore, when both "shaper" and "policing" TAS methods are available to an STA, one of the TAS methods may be determined depending on the application characteristics of the data transmitted to and received from the STA. For example, the shaper method may be selected for transmitting and receiving data that is periodic but has no or strict latency constraints, such as sensor data. Furthermore, when an application requiring real-time operation and therefore having constraints on data arrival time is used, such as a game or industrial robot, the policing method may be selected so that periodic data is transmitted and received while taking delay control into consideration. Note that the shaper method and the policing method are merely examples, and other methods may also be available. In this case, the TAS method determination unit 302 may select the method to be used from among multiple available methods, including the other method.

[0028] The TAS capability information may include information about a TAS method according to the application characteristics of the data to be transmitted and received, and is notified from the communication device to the other device at the time of connection or during communication using a management frame of the IEEE 802.11 standard, for example. Information notification using a management frame will be described later with reference to FIG. 7. Furthermore, when a large number of users (end devices) are accommodated in one BSS, the overhead caused by the exchange of information for low-latency communication may become large. For this reason, the type of TAS method may be changed when the number of STAs accommodated by the AP is equal to or exceeds a specified number. The communication device may or may not notify the other device of the TAS method determined by the TAS method determination unit 302.

[0029] The connection processing unit 303 performs processing for establishing a connection between a STA and an AP. For example, the connection processing unit 303 of the STA transmits an Association Request frame to the AP. Furthermore, the connection processing unit 303 of the AP transmits an Association Response frame in 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 a wireless frame such as a Beacon frame, a Probe Request / Response frame, or an Association Request / Response frame. The MAC frame may also be a MAC frame of a Reassociation Request / Response frame. Note that the TAS capability information may be stored in, for example, a MAC header. Furthermore, the TAS capability information and TAS method information are transmitted using a 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, which are generated periodically at strict timing, in accordance with the TAS method determined by the TAS method determination unit 302. The TAS traffic data transmission process in the data transmitter / receiver 305 will be described in detail later with reference to FIGS.

[0030] (Processing flow) 4, an example of the flow of processing executed by AP 102 when STA 103 connects to AP 102 will be described. Note that similar processing can also be executed for other combinations of STA and AP. This processing can be started, for example, when STA 103 is powered on. Alternatively, this processing can be started when a user or application in STA 103 issues an instruction to start data communication in which the TAS method should be used. Note that this processing is realized, for example, by the control unit 202 of AP 102 executing a program stored in the storage unit 201.

[0031] In this process, first, the AP 102 acquires 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 a Probe Request frame that the STA 103 transmits before connection or an Association Request frame that the STA 103 transmits upon connection. The AP 102 can acquire the TAS capability information of the STA 103 by receiving these frames and analyzing their contents. Next, the TAS determination unit 302 of the AP 102 determines a TAS method to be used for delay control based on the TAS capability information of the STA 103 acquired in S401 (S402). The AP 102 then determines whether or not the TAS method determined in S402 can be used (S403). If the AP 102 determines that the TAS method determined in S402 cannot be used (NO in S403), it notifies the STA 103 that delay control cannot be performed. In this case, the AP 102 notifies the STA 103 of a management frame including TAS capability information in which information (e.g., an ID) indicating that delay control cannot be performed is set (S406). On the other hand, if the AP 102 determines that the TAS method determined in S402 can be used (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 TAS capability information in which a value indicating the TAS method determined in S402 is set (S404). Note that this value may be, for example, a TAS support ID corresponding to the TAS method. The AP 102 then stores the TAS capability information notified to the STA 103 in the management frame in S404 or S406 in the storage unit 201 (S405). In this manner, TAS capability information is exchanged between the AP and the STA.

[0032] Next, an example of the flow of data reception processing executed by the STA 103 during communication on the downlink (DL), which is a link through which a signal is transmitted from the AP 102 to the STA 103, will be described with reference to FIG. 5. Here, handling of TAS traffic data (sensor data, etc.) when a device such as the sensor device 107 serves as a talker (transmitter) and the STA 103 serves as a listener (receiver) will be described. For example, TAS traffic data periodically transmitted from the sensor device 107 reaches the STA 103 via the bridge 104 and the AP 102. Note that this processing can also be applied to the uplink (UL), which is a link through which a signal is transmitted from the STA 103 to the AP 102; for example, similar processing can be executed when the AP 102 receives data from the STA 103. In this case, the STA 103 in the following description will be replaced with the AP 102.

[0033] When receiving data from the AP 102 (YES in S501), the STA 103 determines whether the device is operating in a TAS reception mode such as policing or shaping. The determination of whether the device 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 the STA 103 receiving a management frame from the AP 102. If the STA 103 is not operating in a TAS reception mode such as policing or shaping (NO in S502), the STA 103 executes normal data reception processing (S503). On the other hand, if the STA 103 is operating in the TAS reception mode (YES in S502), the STA 103 sets and starts a TAS traffic data reception timer with a time interval shorter than the timing of receiving the next TAS traffic data after the data reception processing (S504).

[0034] The STA 103 then checks the TAS traffic data reception timer to determine whether it is time to receive the TAS traffic data (S505). If the current time is not the next time to receive the TAS traffic data (NO in S505), the STA 103 checks whether a predetermined time, such as the time immediately before reception, has arrived (S508). If the predetermined time has not arrived (NO in S508), the STA 103 returns to S505 and checks the reception timing of the TAS traffic data. On the other hand, if the predetermined time has arrived (YES in S508), the STA 103 performs carrier sensing or the like to check the usage status of the reception channel for the corresponding TAS traffic data (S509). Here, if the STA 103 determines that the reception channel is busy (NO in S509), it performs channel access contention processing (S510) to make the channel available, and returns to S505. If the receiving channel is not busy and available (YES in S509), the STA 103 reserves the receiving channel for the TAS traffic data by transmitting a null packet, for example, since the current time is immediately before the receiving timing (S511).Then, the STA 103 returns the process to S505.

[0035] The STA 103 checks the reception timer for the TAS traffic data, and if it determines that it is time to receive the TAS traffic data (YES in S505), it executes a reception process for the TAS traffic data (S506). The STA 103 then determines whether the data communication is to end (S507), and if the data communication continues (NO in S507), it returns the process to S501, and if the data communication has ended (YES in S507), it ends the data reception process. As described above, the STA 103 can receive the TAS traffic data from the AP 102 at a predetermined reception timing (time) in the wireless communication of the BSS 101.

[0036] 6, an example of the flow of data reception processing executed by STA 103 during communication on the uplink (UL) will be described. Here, handling of TAS traffic data (remote control data, etc.) when STA 103 is the talker (transmitter) and a device such as remote device 108 is the listener (receiver) will be described. For example, TAS traffic data periodically transmitted from STA 103 reaches remote device 108 via AP 102 and bridge 104. Note that this processing can also be applied to downlink (DL), and similar processing can be executed when AP 102 transmits data to STA 103, for example. In this case, STA 103 in the following description will be replaced with AP 102.

[0037] The STA 103 continuously monitors whether transmission data has been generated, for example, by receiving a data transmission request from a control application of the remote device 108 implemented in the STA 103 (S601). When the STA 103 detects the generation of transmission data (YES in S601), the STA 103 determines whether the STA 103 is operating in a TAS transmission mode such as policing or shaping. The determination of whether the STA 103 is operating in the TAS transmission mode can be made, for example, by checking the TAS support ID stored in the storage unit 201 in response to the STA 103 receiving a management frame from the AP 102. If the STA 103 is not operating in a TAS transmission mode such as policing or shaping (NO in S602), the STA 103 executes normal data transmission processing (S603). On the other hand, if the STA 103 is operating in the TAS transmission mode (YES in S602), the STA 103 sets and starts a TAS traffic data transmission timer with a time interval shorter than the timing of the next TAS traffic data transmission after the data transmission processing (S604).

[0038] The STA 103 then checks the TAS traffic data transmission timer to determine whether it is time to transmit the TAS traffic data (S605). If the current time is not the next time to transmit the TAS traffic data (NO in S605), the STA 103 checks whether a predetermined time, such as the time immediately before transmission, has arrived (S608). If the predetermined time has not arrived (NO in S608), the STA 103 returns to S605 and checks the timing of transmitting the TAS traffic data. On the other hand, if the predetermined time has arrived (YES in S608), the STA 103 performs carrier sensing or the like to check the usage status of the transmission channel for the corresponding TAS traffic data (S609). Here, if the STA 103 determines that the transmission channel is busy (NO in S609), it performs channel access contention processing (S610) to make the channel available, and returns to S605. If the transmission channel is not busy and available (YES in S609), the STA 103 reserves the transmission channel for the TAS traffic data by transmitting, for example, a null packet, since the current time is immediately before the transmission timing (S511).Then, the STA 103 returns the process to S605.

[0039] The STA 103 checks the transmission timer for the TAS traffic data, and if it determines that it is time to transmit the TAS traffic data (YES in S605), it executes a process for transmitting the TAS traffic data (S606). The TAS traffic data transmission process will be described later with reference to FIGS. 15 and 16. Thereafter, the STA 103 determines whether the data communication will end (S607), and if the data communication continues (NO in S607), it returns the process to S601, and if the data communication has ended (YES in S607), it ends the data transmission process. As described above, the STA 103 can transmit the TAS traffic data to the AP 102 at a predetermined transmission timing (time) in the wireless communication of the BSS 101.

[0040] In this way, the STA 103 can transmit TAS traffic data to the AP 102 at a predetermined transmission timing. By executing the processes of Figures 5 and 6 between the STA and the AP, the TAS traffic data is transmitted periodically at a preset time. By operating so that communication is performed at an appropriate preset time based on the network topology, unnecessary waiting time is reduced, thereby enabling communication with low latency.

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

[0042] After the scanning process, the STA 103 transmits an Association Request frame (M704) to the AP 102 to connect to the BSS 101. In response to the Association Request frame (M704), the AP 102 transmits an Association Response frame (M705) indicating the connection result of the STA 103 to the STA 103. TAS capability information may be included in the Association Request frame and the Association Response frame. Furthermore, the STA 103 may determine the TAS capability information to be included in the Association Request frame based on the TAS capability information of the AP 102 acquired in the scanning process, etc. In one example, when both the shaper method and the policing method are available, the STA 103 may select the method to be used depending on the purpose of communication using the TAS method, and notify the AP 102 of information indicating that only the selected method is available. For example, when the talker is the sensor device 107, the STA 103 that can use both methods may transmit to the AP 102 an Association Request frame (M704) including TAS capability information indicating that the local device can use only the shaper method. Also, when the listener is the remote device 108, the STA 103 that can use both methods may transmit to the AP 102 an Association Request frame (M704) including TAS capability information indicating that the local device can use only the policing method. Similarly, the AP 102 may determine the TAS capability information to be included in the Association Response frame based on the TAS capability information of the STA 103 included in the Association Request frame, etc. In this way, the TAS capability information is exchanged before the connection between the AP 102 and the STA 103 is established.

[0043] Thereafter, the AP 102 confirms that TAS communication is possible, and then transmits a management frame (M706) to the STA 103. This management frame includes information indicating that, for example, the shaper method should be used as TAS capability information during DL data communication. This management frame may also include, for example, information indicating a schedule for transmitting and receiving data using the TAS method. Thereafter, the STA 103, which is the listener, periodically receives TAS traffic data (M707) from the sensor device 107, which is the talker, via the AP 102. The STA 103 receives the TAS traffic data (M707) by, for example, performing the data reception process described with reference to FIG. 5. The AP 102 also transmits the TAS traffic data (M707) by, for example, performing the data transmission process described with reference to FIG. 6.

[0044] Next, an example of the flow of messages transmitted and received between AP 102 and STA 103 during UL communication will be described with reference to FIG. 8. This process is executed when STA 103, which is a talker, transmits TAS traffic data received by a device such as remote device 108 operating as a listener via AP 102 and bridge 104. Here, messages M701 to M703 related to scanning processing, messages M704 to M705 related to STA connection processing, and the management frame M706 are the same as those in FIG. 7. Note that, since the listener here is remote device 108, STA 103, which is compatible with both methods, can transmit to AP 102 TAS capability information indicating that it can use only the policing method in an Association Request frame. Note that the management frame (M706) includes information indicating that the policing method should be used as the TAS capability information during UL data communication. This management frame can also include information indicating a schedule for transmitting and receiving data using the TAS method. Thereafter, STA 103, which is the talker, periodically transmits mTAS traffic data (M801) to remote device 108, which is the listener, via AP 102. STA 103 transmits the TAS traffic data (M801) by, for example, executing the data transmission process described with reference to Fig. 6. AP 102 receives the TAS traffic data (M801) by, for example, executing the data reception process described with reference to Fig. 5.

[0045] In this way, the AP 102 and the STA 103 exchange their own TAS capability information and can determine whether to use the TAS method for subsequent communications and whether to use the shaper method or the policing method. As a result, by executing the processing described below with reference to Figures 15 and 16, for example, wireless communications can be performed with time-based scheduling, enabling low-latency communications.

[0046] Next, a first example of TAS capability information will be described with reference to FIG. 9 . Note that in this embodiment, the name of this TAS capability information is “TAS capability element,” but this is not limiting. 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 IEEE 802.11 standard. That is, the TAS capability element includes an Element ID field 901 that identifies the element, a Length field 902 that indicates the data length of the element, and information specific to the element. The TAS capability element includes a TAS capability Info field 903 as information specific to the element. The TAS capability element is included in MAC frames such as Beacon frames, Probe Request / Response frames, and Association Request / Response frames. Note that the TAS capability element may also be included in the MAC frame of a Reassociation Request / Response frame. The TAS capability Info field 903 includes information indicating whether the sender of this TAS capability element can use a TAS method and the usable TAS method. This information is expressed, for example, in two bits. An example of information represented by two bits will be described later with reference to Fig. 11. Note that, although the TAS capability info field 903 is described here as having a size of one octet (8 bits), this is not limited to this. The field names and bit positions and sizes are not limited to the example in Fig. 9, and similar information may be stored with different field names, in different orders, and in different sizes.

[0047] A second example of the TAS capability information will be described with reference to FIG. 10 . This TAS capability element also includes an Element ID field 901 and a Length field 902, similar to the example of FIG. 9 . This information may be included in the MAC frame of each radio frame described above, instead of the information of FIG. 9 . The TAS capability element of FIG. 10 may be similar to the TAS capability element of FIG. 9 except for the TAS capability Info field 1001. Note, however, that the value stored in the Length field 902 differs between FIG. 9 and FIG. 10 due to the different sizes of the TAS capability Info field. In the example of FIG. 10 , the TAS capability Info field 1001 includes information indicating whether or not the TAS method is available, as well as whether or not each TAS method is available for the primary channel. The primary channel is a main channel for supporting multilink technology that simultaneously uses multiple wireless channels, and is used to control the transmission and reception of capability information of other wireless links and messages related to connection, disconnection, etc. The relationship between TAS method capability information and the primary channel will be described later with reference to FIG. 14 . In the following, the primary channel may be referred to as "PCH."

[0048] The TAS Support field 1002 includes information indicating whether the sender of this TAS capability element can use a TAS method and which TAS methods are available. This information is expressed, for example, by two bits. An example of information expressed by two bits will be described later with reference to FIG. 11. The PCH1 Availability fields 1003 to PCH9 Availability fields 1011 are fields indicating whether the TAS method can be used in each of primary channels 1 to 9. The values ​​stored in these fields and the contents indicated by these values ​​will be described later with reference to FIG. 12. The Reserve field 1012 is a 5-bit unused area for future expansion. While an example in which the TAS capability info field 1001 is 2 octets (16 bits) is shown here, this is not limiting. For example, similar information may be represented by different field names, different bit positions, or different field sizes. In this embodiment, the element in FIG. 10 is named "TAS capability element," but this is not limiting and other names, such as "TAS Multi-Link Element," may also be used.

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

[0050] 12 shows examples of values ​​stored in the PCH1 usability field 1003 to PCH9 usability field 1011 of FIG. 10 and their corresponding contents. The PCH1 usability field 1003 to PCH9 usability field 1011 store an E bit 1201 whose indicated content 1202 varies depending on the combination with the value indicated in the TAS support field 1002. For example, if the two bits stored in the TAS support field 1102 respectively indicate a policing method (D bit value "10") or a shaper method (D bit value "01"), the E bit indicates whether or not the respective TAS method is usable. For example, setting the E bit to "1" indicates that the TAS method indicated by the D bit value can be used, and setting the E bit to "0" indicates that the TAS method indicated by the D bit value cannot be used. Note that this is just one example, and setting the E bit to "0" may indicate that the TAS method indicated by the D bit value can be used, and setting the E bit to "1" may indicate that the TAS method indicated by the D bit value cannot be used. Furthermore, when the two bits stored in the TAS support field 1102 indicate that both the policing method and the shaping method can be used (when the D bit value is "11"), one of the E bits can specify either method. For example, setting the E bit to "1" specifies the policing method, and setting the E bit to "0" specifies the shaping method. Alternatively, setting the E bit to "0" may specify the policing method, and setting the E bit to "1" may specify the shaping method.

[0051] Here, an example of the flow of processing executed by the AP 102 when the TAS capability information of Fig. 10 is reported by a Beacon frame will be described with reference to Fig. 13. This processing is started, for example, when the power of the AP 102 is turned on or when a TAS-based data collection process is started in the AP 102. Note that this processing can be realized, for example, by the control unit 202 of the AP 102 executing a program stored in the storage unit 201.

[0052] First, the AP 102 determines whether a mode in which multi-channel TAS information is included in a Beacon frame as shown in Fig. 10 is set (S1301). If the AP 102 determines that a mode in which multi-channel TAS information is included in a Beacon frame is not set (NO in S1301), the AP 102 executes a conventional Beacon frame setting process (S1302). Then, the AP 102 broadcasts the Beacon frame obtained by the setting process of S1302 within BSS1 (S1306). In this case, the AP 102 may transmit a Beacon frame including TAS information as shown in Fig. 9, for example.

[0053] If the mode in which multi-channel TAS information is included in a Beacon frame is set (NO in S1301), the AP 102 determines whether each of multiple PCHs can be used based on the TAS capability information stored in S405 of FIG. 4 (S1303). For this purpose, the AP 102 transmits a Request To Send (RTS) message. Then, when the STA 103 receives an RTS on each PCH, it performs carrier sensing on that PCH. If that PCH is not busy, the STA 103 transmits a Clear To Send (CTS) message to the AP 102 after a Short Inter Frame Space (SIFS) period has elapsed. The AP 102 checks whether a CTS has been received on each PCH for which the RTS has been transmitted, and recognizes the PCHs for which reception has been confirmed as usable PCHs. At this time, the TAS capability information generation unit 301 of the AP 102 recognizes that TAS communication cannot be used for PCHs for which reception of a CTS has not been confirmed.

[0054] Then, TAS capability information generation unit 301 updates information on whether the TAS method for each PCH in the TAS capability information is available. When AP 102 completes the process of S1303 for all of the available PCHs (YES in S1304), AP 102 stores the confirmed TAS capability information in storage unit 201 and sets the TAS capability information in a Beacon frame (S1305). Then, AP 102 broadcasts a Beacon frame including the TAS capability information in BSS 101 (S1306). Note that the Beacon frame including the TAS capability information shown in FIG. 9 or 10 may be broadcast on multiple PCHs.

[0055] In this manner, the AP 102 can transmit a Beacon frame including information on multiple PCHs. This allows the STA 103 to select and use a PCH that allows communication taking into account delay control based on the TAS capability information. Furthermore, for example, among the PCHs for which TAS capability information is available, a PCH having a signal bandwidth equal to or larger than a predetermined width may be selected, or a PCH having a larger signal bandwidth may be preferentially selected. Furthermore, among the PCHs for which TAS capability information is available, a PCH having a received field strength or a signal-to-noise ratio (SNR) equal to or larger than a predetermined value may be selected, or a PCH having a better value may be preferentially selected. Furthermore, among the PCHs for which TAS capability information is available, a PCH having a channel transmission capacity calculated from the bandwidth and SNR equal to or larger than a predetermined value may be selected, or a PCH having a larger capacity may be preferentially selected. Furthermore, among the PCHs for which TAS capability information is available, a PCH to be used may be selected based on available channel information estimated from channel usage status over a certain period of time. Furthermore, conditions other than these PCH selection conditions may be used. Furthermore, one or more of the above selection conditions may be used in combination.

[0056] Next, PCH1 to PCH9 will be described with reference to Fig. 14. PCH1 to PCH9 respectively represent a plurality of PCHs that can be used in the 5 GHz band. For example, PCH1 to PCH9 are frequency channels with channel numbers 36, 44, 52, 60, 100, 108, 116, 124, and 132, each with a bandwidth of 20 MHz. Note that although the 5 GHz frequency band has been described here, the same discussion can also be applied to the 2.4 GHz and 6 GHz frequency bands. Furthermore, the above discussion may be applied to any other frequency channel, not just PCHs.

[0057] Using FIG. 15, a description will be given of a traffic data transmission process of a Time-Aware Schedule (TAS) in an AP and a STA according to this embodiment. As an example, the AP 102 and the STA 101 have the configuration shown in FIG. 15 for TAS traffic data transmission. In the configuration shown in FIG. 15, an application 1501 receives TAS method information determined by the TAS method determination unit 302 before the TAS traffic data is transmitted. The application 1501 then prepares for a data transmission request from the MAC frame generation unit 304 to execute transmission processing according to the TAS method information. A traffic classification function 1503 receives traffic data with priority information added from the MAC frame generation unit 304 and maps time-constrained traffic data to a TAS queue (Q0) 1504. The traffic classification function 1503 also maps best-effort traffic data other than TAS traffic data to each of the BE queues (Q1-Q4) 1505. The TAS time gate control function 1502 controls the output of traffic data stored in each queue by temporarily suspending / resuming the TAS time gate (G0) 1506 and the various BE time gates (G1-G4) 1507. The TAS time gate control function 1502 performs control to protect TAS traffic data while avoiding channel access conflicts, as described below.

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

[0059] The TAS time gate control function 1502 performs gate control according to the periodically repeated TAS traffic data transmission and reception schedule. For example, the TAS time gate control function 1502 can close or open each time gate by inputting a bit 0 or 1 to each time gate. The TAS time gate control function 1502 can indicate the OPEN / CLOSE status of five time gates G0 to G4 using a 5-bit bit string. Each time gate can then extract its corresponding bit from this bit string and control the CLOSE / OPEN status. The TAS time gate control function 1502 can also output 1 bit of information for each time gate, indicating whether that time gate is CLOSE or OPEN. The state of each time gate for each bit string is explained below. The bit string here indicates the OPEN / CLOSE status of each time gate in the order "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 a state in which only the TAS time gate (G0) 1506 is open, and this state corresponds to the period 1609. The bit string "01111" indicates a state in which the various BE time gates (G1-G4) 1507 are open, and corresponds to, for example, the period 1608 excluding the period 1609 and the guard time 1606. In this way, the TAS time gate control function 1502 can control the close / open status of each time gate using a one-bit indicator.

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

[0061] The present invention can also be realized by supplying a program that realizes one or more functions of the above-described embodiments to a system or device via a network or a storage medium, and having one or more processors in the computer of the system or device read and execute the program. It can also be realized by a circuit (e.g., ASIC) that realizes one or more functions.

[0062] The invention is not limited to the above-described embodiments, and various changes and modifications can be made without departing from the spirit and scope of the invention. Accordingly, the following claims are appended to apprise the public of the scope of the invention. [Explanation of symbols]

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

Claims

1. A communication device operating as an access point, a transmitting means for transmitting a wireless frame conforming to the IEEE 802.11be standard; a MAC (Media Access Control) frame of the wireless frame includes an information element indicating whether the communication device supports an operation of protecting access to wireless resources and reserving the wireless resources for transmission of traffic requiring low latency; the operation is an operation in which the other communication device transmits the traffic requiring low latency with priority during a period based on the schedule notified by the communication device. A communication device comprising:

2. The communication device described in Claim 1, characterized in that the schedule includes information indicating the start time of the period.

3. A communication device as described in claim 1, characterized in that the period is scheduled periodically.

4. The communication device according to claim 1, wherein the information element includes an Element ID field indicating identification information of the information element and a field indicating whether the operation is supported.

5. 2. The communication device according to claim 1, wherein the wireless frame including the MAC frame is any one of a Beacon frame, a Probe Response frame, an Association Response frame, and a Reassociation Response frame.

6. A control method executed by a communication device operating as an access point, comprising: a transmitting step of transmitting a wireless frame conforming to the IEEE 802.11be standard; a MAC (Media Access Control) frame of the wireless frame includes an information element indicating whether the communication device supports an operation of protecting access to wireless resources and reserving the wireless resources for transmission of traffic requiring low latency; the operation is an operation in which the other communication device transmits the traffic requiring low latency with priority during a period based on a schedule notified by the communication device. A control method comprising:

7. A program for causing a computer provided in a communication device operating as an access point to execute a transmission procedure for transmitting a wireless frame conforming to the IEEE 802.11be standard, a MAC (Media Access Control) frame of the wireless frame includes an information element indicating whether the communication device supports an operation of protecting access to wireless resources and reserving the wireless resources for transmission of traffic requiring low latency; the operation is an operation in which the other communication device transmits the traffic requiring low latency with priority during a period based on a schedule notified by the communication device. A program characterized by:

8. A communication device, a receiving means for receiving a wireless frame conforming to the IEEE 802.11be standard from an access point; a MAC (Media Access Control) frame of the wireless frame includes an information element indicating whether the access point supports an operation of protecting access to wireless resources and reserving the wireless resources for transmission of traffic requiring low latency; the operation is an operation in which the communication device transmits the traffic requiring low latency with priority during a period based on a schedule notified by the access point. A communication device comprising:

9. The communication device described in Claim 8, characterized in that the schedule includes information indicating the start time of the period.

10. The communication device described in Claim 8, characterized in that the period during which the communication device preferentially transmits traffic requiring low latency is scheduled periodically.

11. The communication device according to claim 8, wherein the information element includes an Element ID field indicating identification information of the information element and a field indicating whether the operation is supported.

12. The communication device according to claim 8, wherein the wireless frame including the MAC frame is one of a Beacon frame, a Probe Response frame, an Association Response frame, and a Reassociation Response frame.

13. A control method executed by a communication device, comprising: a receiving step of receiving a wireless frame conforming to the IEEE 802.11be standard from an access point; a MAC (Media Access Control) frame of the wireless frame includes an information element indicating whether the access point supports an operation of protecting access to wireless resources and reserving the wireless resources for transmission of traffic requiring low latency; the operation is an operation in which the communication device transmits the traffic requiring low latency with priority during a period based on a schedule notified by the access point. A control method comprising:

14. A program for causing a computer provided in a communication device to execute a receiving procedure for receiving a wireless frame conforming to the IEEE 802.11be standard from an access point, comprising: a MAC (Media Access Control) frame of the wireless frame includes an information element indicating whether the access point supports an operation of protecting access to wireless resources and reserving the wireless resources for transmission of traffic requiring low latency; the operation is an operation in which the communication device transmits the traffic requiring low latency with priority during a period based on a schedule notified by the access point. A program characterized by:

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