Communication apparatus, control method, and storage medium

Abstract

The invention discloses a communication apparatus, a control method, and a storage medium. The communication device transmits a radio frame conforming to the IEEE802.11 standard series to another communication device, or receives a radio frame from another communication device. Here, a MAC (Media Access Control) frame of a radio frame includes information on a schedule of a transmission opportunity in which contention is suppressed on a time basis.

Description

[0001] This application is a divisional application of the invention patent application filed on March 10, 2021, with application number 202180019870.1 (international application number PCT / JP2021 / 009591) and entitled "Communication device, control method and storage medium". Technical Field

[0002] This invention relates to a communication device, a control method, and a storage medium, and more specifically, to an information sharing technology for scheduling functions in wireless communication. Background Technology

[0003] The IEEE 802.11 standard series is known as the wireless LAN (Local Area Network) communication standard defined by the IEEE (Institute of Electrical and Electronics Engineers). The IEEE 802.11 standard series includes IEEE 802.11a / b / g / n / ac / ax standards, and a new standard has been researched to improve peak throughput and frequency utilization efficiency compared to traditional standards. For example, in the IEEE 802.11ax standard, high peak throughput can be achieved using OFDMA (Orthogonal Frequency Division Multiple Access) (see Patent Document 1).

[0004] Citation table Patent documents Patent document 1: Japanese Patent Application Publication No. 2018-050133. Summary of the Invention

[0005] Technical issues In recent years, the IEEE 802.11be standard has been defined as a new standard in order to further improve throughput and frequency utilization efficiency. One goal of this work is to achieve reliable low-latency (RLL) communication.

[0006] This invention provides a communication control technique for achieving such reliable low-latency communication.

[0007] Solution to the problem A communication apparatus according to one aspect of the invention is a communication apparatus comprising a communication unit for transmitting radio frames conforming to the IEEE 802.11 standard series to another communication apparatus or receiving radio frames from another communication apparatus, wherein the MAC (Media Access Control) frame of the radio frame includes information regarding the scheduling of transmission opportunities based on time-constrained contention.

[0008] Advantages of the present invention According to the present invention, reliable low-latency communication can be achieved.

[0009] Other features and advantages of the invention will become apparent from the following description taken in conjunction with the accompanying drawings. Note that the same reference numerals in the drawings denote the same or similar components. Attached Figure Description

[0010] The accompanying drawings, which are incorporated in and constitute a part of this specification, illustrate embodiments of the invention and, together with the specification, serve to explain the principles of the invention.

[0011] Figure 1 This is a view illustrating an example of a network configuration according to an embodiment; Figure 2 This is a block diagram illustrating an example of the hardware layout of a communication device; Figure 3 This is a block diagram illustrating an example of the functional arrangement of a communication device; Figure 4 This is a flowchart illustrating an example of the processing procedures performed by the AP when a STA is connected; Figure 5 This is a flowchart illustrating an example of the data reception and processing procedure; Figure 6 This is a flowchart illustrating an example of the data transmission and processing procedure; Figure 7 This is a sequence diagram illustrating an example of message flow sent / received between the AP and STA during DL communication; Figure 8 This is a sequence diagram illustrating an example of message flow sent / received between the AP and STA during UL communication; Figure 9 This is a view showing an example of the structure of TAS capability information; Figure 10 This is a view showing an example of the structure of TAS capability information; Figure 11 This is a table used to describe the setting values ​​for TAS capability information; Figure 12 This is a table used to describe the setting values ​​for TAS capability information; Figure 13 This is a flowchart illustrating an example of the processing procedure when TAS capability information is broadcast via a beacon frame; Figure 14 This is a view used to illustrate an example of the main channel in the 5GHz band; Figure 15 This is a view used to illustrate TAS traffic processing; and Figure 16 This is a timing diagram used to illustrate TAS traffic processing. Detailed Implementation

[0012] The embodiments will be described in detail below with reference to the accompanying drawings. Note that the following embodiments are not intended to limit the scope of the claimed invention. Multiple features are described in the embodiments, but the invention is not limited to requiring all of these features, and multiple such features can be appropriately combined. Furthermore, in the drawings, the same reference numerals are given for the same or similar configurations, and redundant descriptions thereof are omitted.

[0013] (Network configuration) Figure 1 An example of a network configuration according to an embodiment is shown. Figure 1 The network comprises two parts: a wireless communication network (BSS 101) where AP 102 provides wireless communication services and a wireless communication network (BSS 111) where AP 112 provides wireless communication services. Note that AP is an abbreviation for Access Point, and BSS is an abbreviation for Basic Service Set. A wireless terminal (STA) can connect to an AP that provides a communicable area including the location of its device, thereby joining the BSS provided by the AP. The STA can then perform the transmission / reception of radio frames within the joined network. Figure 1 In the example shown, since STA 103 exists within the communicable area of ​​both APs 102 and 112, it can connect to one of the APs to join one of BSSs 101 and 111. Note that in the following text, an environment where the communicable areas of multiple APs overlap is sometimes referred to as an OBSS environment. That is, in this embodiment, STA 103 exists within an OBSS environment. Note that STA 103 is connected to AP 102, and signals from AP 112 can be interference signals for STA 103. Furthermore, since STA 113 exists within the communicable area of ​​AP 112, it can connect to AP 112 to join BSS 111.

[0014] APs 102 and 112 are connected via bridge 104. The APs and bridges, or bridges and other bridges, can be connected via, for example, wired connections. However, at least a portion of the connection between APs 102 and 112 can be wireless. This arrangement can form a network by combining the wireless network formed by APs 102 and 112 with the wired network formed by bridge 104, etc.

[0015] Sensor device 107 is a sensor connected to the network via bridge 104, configured to output environmental data collected by the sensor function to another device, for example. In this embodiment, sensor device 107 sends the collected data to STA 103 at predetermined intervals. Remote device 108 is a device connected to the network via bridge 104 and operated according to remote operation commands from another device. Remote device 108 is a terminal device, such as an industrial robot or a medical operating robot, that requires low-latency data communication via RTA (Real-Time Application). This embodiment assumes that remote device 108 operates according to remote operation commands from STA 103.

[0016] For example, in this network system, it is crucial that STA 103 reliably receives data from sensor device 107 at predetermined intervals, and that remote operation command signals from STA 103 reach remote device 108 with low latency. However, in conventional wireless LANs, because the device used to transmit data confirms that no radio resources are in use nearby and transmits signals during periods when no radio resources are used, the device cannot perform communication when another device is using radio resources. Therefore, to ensure that signals are transmitted / received at predetermined intervals and to enable low-latency communication, it is necessary to introduce some communication control functions. As a solution to this, a Time-Aware Scheduling (TAS) scheme defined by the IEEE 802.1Qbv standard can be introduced to enable the appropriate transmission / reception of predetermined data (e.g., data with strict latency requirements). The TAS scheme is a time-aware scheduling scheme used to transmit / receive signals at predetermined times with reference to time. In this embodiment, communication using the TAS scheme is performed in the network to appropriately perform communication at predetermined intervals or low-latency communication. Therefore, it is assumed that devices such as AP 102, STA 103 and 113, and bridge 104 support the TAS scheme. However, it is assumed that AP 112 does not support the TAS scheme. Note that devices other than AP 112 also support the standard (IEEE 802.1AS) for synchronization with the same reference clock in the network.

[0017] The scheduled data sent / received using the TAS scheme is referred to hereinafter as TAS traffic data. In this example, TAS traffic data is packet data sent / received taking into account latency control between terminal devices. To control this sending / receiving, the network includes a network management unit 105 and a scheduling management unit 106. The network management unit 105 performs latency control regarding TAS traffic data. The scheduling management unit 106 performs scheduling management related to the TAS traffic of terminal devices in the network using TAS traffic data. AP 102 sends / receives data to / from the network management unit 105 via bridge 104. In addition, AP 102 exchanges TAS information with the scheduling management unit 106, which performs scheduling management for the entire network.

[0018] Network management device 105 collects time-aware scheduling (TAS) related requirements from terminal devices (e.g., STA 103, sensor device 107, and remote device 108). Based on these requirements, for example, the specific devices for sending / receiving TAS traffic data, the data transmission time interval, and the allowable delay are specified. Network management device 105 detects the network topology of the network to be controlled by the devices. The network topology can be an indication of the relationships between each device in the network and specific devices. Note that "connection" means a state in which devices are physically and directly connected or a state in which a logical link is established regardless of the physical connection arrangement. Based on the collected requirements, network management device 105 calculates the end-to-end path between terminal devices for each of the transmission and reception of TAS traffic data to be performed. Then, network management device 105 performs scheduling by determining the timing of each device's signal transmission based on the calculation results, thereby notifying scheduling management device 106 of the scheduling results.

[0019] The scheduling management device 106 sends a message including TAS information to the bridge 104 and the AP 102, thereby setting up a send / receive schedule. The scheduling management device 106 also notifies the terminal devices (STA 103, sensor device 107, and remote device 108) of the TAS information. At this time, each terminal device (STA 103, sensor device 107, and remote device 108) operates as a publisher (data sender) or a subscriber (data receiver) according to the send schedule related to the TAS traffic in the network. For example, in a combination of terminal devices considering the RTA traffic of STA 103 and sensor device 107, STA 103 operates as a subscriber, while sensor device 107 operates as a publisher. See below for further details. Figure 7This describes the details of the message sequence in this scenario, as an example of downlink (DL) communication flow in data communication supporting TAS in BSS 101. In the combination of terminal devices considering the RTA traffic of STA 103 and remote device 108, remote device 108 operates as a subscriber, while STA 103 operates as a publisher. References will follow later. Figure 8 This describes the details of the message sequence in this situation as an example of uplink (UL) communication flow for data communication supporting TAS in BSS 101.

[0020] Note that the network configuration described above is merely an example, and the invention is not limited to this. Figure 1 The configuration shown is illustrated. For example, the following discussion applies to, for instance, a network (BSS) comprising many wireless communication devices over a wider area, or the locational relationships between various wireless communication devices. Furthermore, for example, the scheduling management device 106 sets up transmit / receive scheduling. However, the functionality of the scheduling management device 106 can be included in a network node such as AP 102, or in some cases, in STA 103. That is, AP 102 and STA 103 can determine the transmit / receive scheduling of data frames.

[0021] The following text will refer to Figure 15 and Figure 16 The device supporting the TAS scheme can send / receive TAS traffic data at strict timings. Therefore, by setting appropriate communication timings, communication can be performed reliably in a low-latency environment under certain circumstances, without interference from other devices. On the other hand, it is also assumed that there are communication devices in the network area that do not support the TAS scheme. Even if the scheduling management device 106 sends a TAS scheme control message to a communication device that does not support the TAS scheme, the communication device cannot parse the message. This may cause inconvenience, for example, performing unexpected operations.

[0022] Based on this assumption, this embodiment provides a method for notifying each communication device of its capability information, enabling confirmation of whether each communication device supports the TAS scheme. More specifically, this information is notified by adding information elements to the MAC (Media Access Control) header of the radio frames to be transmitted by each communication device. By scheduling the selection of whether to use the TAS scheme based on this information, appropriate scheduling can be performed between the transmitting and receiving devices. The arrangement of the devices for sending / receiving such notifications, the processing procedure, and the actual frame structure will be illustrated below.

[0023] (Equipment layout) Figure 2The hardware arrangement of a communication device (AP, STA, and other terminal devices) according to this embodiment is shown. As an example of 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.

[0024] Storage unit 201 is composed of either ROM (Read-Only Memory) or RAM (Random Access Memory). Storage unit 201 stores, for example, programs for performing various operations (described later) and various information (e.g., communication parameters for wireless communication). Note that in addition to memories such as ROM and RAM, storage media such as floppy disks, hard disks, optical disks, magneto-optical disks, CD-ROMs, CD-Rs, magnetic tapes, non-volatile memory cards, or DVDs can be used as storage unit 201.

[0025] The control unit 202 consists of one or more processors, such as a CPU or MPU, an ASIC (Application-Specific Integrated Circuit), a DSP (Digital Signal Processor), or a FPGA (Field-Programmable Gate Array). CPU is an abbreviation for Central Processing Unit, and MPU is an abbreviation for Microprocessor Unit. The control unit 202 controls the entire communication device by executing programs stored in the storage unit 201. Note that the control unit 202 can cooperate with programs stored in the storage unit 201 and the OS (Operating System) to control the entire communication device.

[0026] Control unit 202 controls functional unit 203 to perform predetermined processes, such as image capture, printing, or projection. Functional unit 203 is hardware used by the communication device to perform the predetermined processes. For example, if the communication device is a camera, functional unit 203 is an image capture unit and performs image capture processing. For example, if the communication device is a printer, functional unit 203 is a printing unit and performs printing processing. For example, if the communication device is a projector, functional unit 203 is a projection unit and performs projection processing. The data to be processed by functional unit 203 may be data stored in storage unit 201, or data communicated with another communication device via communication unit 206 (described later).

[0027] Input unit 204 receives various operations from the user. Output unit 205 performs various outputs to the user. In this example, the output of output unit 205 includes at least one of the following: display on a screen, audio output from a speaker, vibration output, etc. Both input unit 204 and output unit 205 can be implemented by a single module, such as a touch panel. Communication unit 206 controls wireless communication or control IP communication conforming to the IEEE 802.11 standard family. In this embodiment, communication unit 206 can perform processing conforming to at least the IEEE 802.11be standard. Furthermore, communication unit 206 controls antenna 207 to transmit / receive radio signals for wireless communication. The communication device communicates with another communication device via communication unit 206, such as image data, document data, or video data. Antenna 207 is an antenna capable of receiving signals from one of the sub-GHz band, 2.4 GHz band, 5 GHz band, and 6 GHz band. Radio antenna 207 can physically consist of one or more antennas to enable MIMO (Multiple-Input Multiple-Output) transmission / reception.

[0028] Figure 3 An example of a functional arrangement associated with TAS communication of a communication device is shown. The communication device includes, for example, a TAS capability information generation unit 301, a TAS scheme 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 implemented when, for example, the control unit 202 executes a program stored in the storage unit 201. However, the invention is not limited thereto; for example, it can use... Figure 3 The dedicated hardware components corresponding to the function blocks shown.

[0029] The TAS capability information generation unit 301 generates TAS capability information (TAS capability information) for the communication device and stores it in the storage unit 201. Based on the TAS information received from the scheduling management device 106, the TAS capability information generation unit 301 can reconstruct the TAS capability data stored in the storage unit 201 or update the content of the TAS capability information. The TAS capability information includes a support ID indicating the TAS scheduling scheme of the communication device. The support ID is an identifier corresponding to each of multiple schemes, used to indicate which scheme can be used. The TAS capability information will be referenced later. Figures 9 to 12 The following description is provided. Note that the communication device performs at least one of notifying another communication device of its own capability information and receiving capability information from that other communication device. That is, the communication device may simply receive capability information from the other communication device without needing to notify the other communication device of its own capability information.

[0030] The TAS scheme determination unit 302 determines the TAS scheme to be used for communication with the partner device based on the TAS capability information of the communication partner device. Generally, there are two TAS schemes: "shaping" and "policing." Since these schemes have different characteristics, the scheme corresponding to the application (application) is used based on the differences between these characteristics. The "policing" scheme reduces latency caused by queuing by dropping packets exceeding the rate limit or changing the priority of packets. The "shaping" scheme buffers packets exceeding the rate limit in the I / F queue, thus causing latency. For example, in the case of traffic using TCP / UDP port numbers, the "shaping" scheme can be selected for TCP, while the "policing" scheme is used for UDP. For example, if the only available TAS scheme for the STA is "shaping," then "shaping" can be used; if the only available TAS scheme for the STA is "policing," then "policing" can be used. If the STA can use both "shaping" and "policing" TAS schemes simultaneously, one of the TAS schemes is determined based on the application characteristics of the data sent to / received from the STA. For example, a shaping scheme can be selected to send / receive data such as sensor data that is periodic but not limited by latency or is not strictly limited by latency. Alternatively, if the application is subject to data arrival time constraints due to the need for real-time operation (such as gaming or industrial robots), a control scheme can be selected to send / receive periodic data with latency control in mind. Note that the shaping and control schemes are merely examples, and other schemes can be used. In this case, the TAS scheme determination unit 302 can select the scheme to use from a plurality of available schemes, including other schemes.

[0031] TAS capability information may include information about the TAS scheme corresponding to the application characteristics of the data to be sent / received, and the communication device uses, for example, management frames defined by the IEEE 802.11 standard to notify the partner device of the TAS capability information during connection or communication. See later. Figure 7 This describes the information notification in the management frame. If a BSS accommodates a large number of users (terminal devices), the overhead may increase due to the information exchange in low-latency communication. To address this, when the number of STAs accommodated by the AP is equal to or greater than a predetermined number, the type of TAS scheme can be changed. Note that the communication device may or may not notify the communication partner device of the TAS scheme determined by the TAS scheme determination unit 302.

[0032] Connection processing unit 303 performs processing for establishing a connection between the STA and AP. For example, the STA's connection processing unit 303 sends an association request frame to the AP. The AP's connection processing unit 303 sends an association response frame in response to the association request frame. MAC frame generation unit 304 generates, as needed, a MAC frame storing TAS capability information generated by TA capability information generation unit 301. In this example, the MAC frame is, for example, a MAC frame within a radio frame (e.g., a beacon frame, probe request / response frame, or association request / response frame). Alternatively, the MAC frame can be a MAC frame of a re-association request / response frame. Note that the TAS capability information can be stored, for example, in a portion of the MAC header. (See below for further details.) Figure 9 or Figure 11 The described capability elements are used to send TAS capability information or TAS scheme information. Based on the TAS scheme determined by the TAS scheme determination unit 302, the data transmission / reception unit 305 transmits / receives periodically generated TAS traffic data frames at strict timings. The TAS traffic data transmission processing in the data transmission / reception unit 305 will be discussed later. Figure 15 and Figure 16 Provide a detailed description.

[0033] (Processing procedure) Reference Figure 4 This describes an example of the processing performed by AP 102 when STA 103 is connected to AP 102. Note that the same processing can be performed even for another combination of STA and AP. This processing can begin, for example, when STA 103 is powered on. Alternatively, this processing can begin when a user or application instructs STA 103 to begin data communication using the TAS scheme. Note that this processing is implemented, for example, when the control unit 202 of AP 102 executes a program stored in storage unit 201.

[0034] In this process, AP 102 obtains the TAS capability information of STA 103 (step S401). For example, Figure 9 or Figure 10The TAS capability information shown (described later) is included in the probe request frame to be sent before connecting to STA 103 or the association request frame to be sent upon connection. AP 102 can obtain the TAS capability information of STA 103 by receiving the frame and analyzing its content. Subsequently, AP 102's TAS scheme determination unit 302 determines the TAS scheme to be used for delay control based on the TAS capability information of STA 103 obtained in step S401 (step S402). Then, AP 102 determines whether the TAS scheme determined in step S402 can be used (step S403). If it is determined that the TAS scheme determined in step S402 cannot be used ("No" in step S403), AP 102 notifies STA 103 that delay control cannot be performed. In this case, AP 102 notifies STA 103, for example, a management frame including TAS capability information, which sets information indicating that delay control cannot be performed (e.g., ID) (step S406). On the other hand, if it is determined that the TAS scheme determined in step S402 can be used ("Yes" in step S403), the TAS capability information generation unit 301 of AP 102 notifies STA 103 of the TAS scheme determined in step S402. In this case, AP 102 notifies STA 103 of, for example, a management frame including TAS capability information, in which a value indicating the TAS scheme determined in step S402 is set (step S404). Note that this value can be, for example, the TAS support ID corresponding to the TAS scheme. Then, AP 102 stores the TAS capability information included in the management frame and notified to STA 103 in step S404 or S406 in storage unit 201 (step S405). In this way, TAS capability information is exchanged between AP and STA.

[0035] Then, refer to Figure 5 This section describes an example of the data reception processing performed by STA 103 when communicating in the downlink (DL) of a link used to transmit signals from AP 102 to STA 103. In this example, the processing of TAS traffic data (sensor data, etc.) will be explained when a device such as sensor device 107 acts as the publisher (transmitter) and STA 103 acts as the subscriber (receiver). For example, TAS traffic data periodically transmitted from sensor device 107 arrives at STA 103 via bridge 104 and AP 102. Note that this processing also applies to the uplink (UL) of a link used to transmit signals from STA 103 to AP 102. The same processing can also be performed when AP 102 receives data from STA 103. In this case, STA 103 can be replaced by AP 102 in the following description.

[0036] When receiving data from AP 102 (Yes in step S501), STA 103 determines whether the self-device is operating in a TAS receiving mode such as control or shaping. For example, when STA 103 receives a management frame from AP 102, it can perform the process of determining whether the self-device is operating in a TAS receiving mode by checking the TAS support ID stored in storage unit 201. If the self-device is not operating in a TAS receiving mode such as control or shaping (No in step S502), STA 103 performs normal data receiving processing (step S503). On the other hand, if the self-device is operating in a TAS receiving mode (Yes in step S502), STA 103 sets a TAS traffic data receiving timer such that the time interval is shorter than the next TAS traffic data receiving timer after the data receiving processing, and starts the timer (step S504).

[0037] To determine whether the current time is the timing for receiving TAS traffic data, STA 103 checks the TAS traffic information reception timer (step S505). If the current time is not the next timing for receiving TAS traffic data (No in step S505), STA 103 checks whether a predetermined time, such as the timing immediately preceding reception, has been reached (step S508). If the predetermined time has not been reached (No in step S508), STA 103 returns to step S505 and checks the TAS traffic data reception timing. On the other hand, if the predetermined time has been reached (Yes in step S508), STA 103 performs carrier sensing to confirm the usage status of the corresponding TAS traffic data reception channel (step S509). If it is determined that the reception channel is busy (No in step S509), STA 103 performs channel access contention processing (step S510) to set the channel to an available state and returns to step S505. If the receive channel is not busy but available ("Yes" in step S509), the current time immediately precedes the receive timing, so STA 103 reserves the TAS traffic data receive channel by, for example, sending an empty packet (step S511). Then, STA 103 returns to step S505.

[0038] If STA 103 checks the TAS traffic data reception timer and determines that the current time is the TAS traffic signal reception timing ("Yes" in step S505), then STA 103 performs TAS traffic data reception processing (step S506). Then, STA 103 determines whether data communication has ended (step S507). If data communication continues ("No" in step S507), then STA 103 returns to step S501. If data communication ends ("Yes" in step S507), then STA 103 ends the data reception processing. As described above, STA 103 can receive TAS traffic data from AP 102 at a predetermined reception timing (time) in the wireless communication of BSS 101.

[0039] Reference Figure 6 This section describes an example of the data reception processing performed by STA 103 during uplink (UL) communication. In this example, the processing of TAS traffic data (remote control data, etc.) will be illustrated when STA 103 acts as a publisher (sender) and a device such as remote device 108 acts as a subscriber (receiver). For example, TAS traffic data periodically sent from STA 103 reaches remote device 108 via AP 102 and bridge 104. Note that this processing also applies to the downlink (DL). For example, the same processing can be performed when AP 102 sends data from STA 103. In this case, STA 103 can be replaced by AP 102 in the following description.

[0040] By receiving a data transmission request, for example, from a control application of a remote device 108 implemented in the self-device, STA 103 continuously monitors whether transmission data is generated (step S601). Then, if the generation of transmission data is detected (yes in step S601), STA 103 determines whether the self-device is operating in a TAS receive mode such as control or shaping. For example, the process of determining whether the self-device is operating in a TAS transmission mode can be performed by, for example, confirming the TAS support ID stored in storage unit 201 when STA 103 receives a management frame from AP 102. If the self-device is not operating in a TAS transmission mode such as control or shaping (no in step S602), STA 103 performs normal data transmission processing (step S603). On the other hand, if the self-device is operating in a TAS transmission mode (yes in step S602), STA 103 sets the TAS traffic data transmission timer to a time interval shorter than the next TAS traffic data transmission timer after the data transmission processing and starts the timer (step S604).

[0041] To determine whether the current time is the timing for TAS traffic data transmission, STA 103 checks the TAS traffic data transmission timer (step S605). If the current time is not the next TAS traffic data transmission timing ("No" in step S605), STA 103 checks, for example, whether a predetermined time, such as the timing immediately preceding transmission, has been reached (step S608). If the predetermined time has not been reached ("No" in step S608), STA 103 returns to step S605 and checks the TAS traffic data transmission timing. On the other hand, if the predetermined time has been reached ("Yes" in step S608), STA 103 performs carrier sensing to confirm the usage status of the corresponding TAS traffic data transmission channel (step S609). If it is determined that the transmission channel is busy ("No" in step S609), STA 103 performs channel access contention processing (step S610) to set the channel to an available state and returns to step S605. If the transmission channel is not busy but available ("Yes" in step S609), the current time immediately precedes the transmission timing, so STA 103 reserves the TAS traffic data transmission channel by, for example, sending an empty packet (step S611). Then, STA 103 returns to step S605.

[0042] If STA 103 checks the TAS traffic data transmission timer and determines that the current time is the TAS traffic data transmission timing ("Yes" in step S605), then STA 103 executes the TAS traffic data transmission process (step S606). See later for further details. Figure 15 and Figure 16 The TAS traffic data transmission process is described. Afterwards, STA 103 determines whether data communication has ended (step S607). If data communication continues (No in step S607), STA 103 returns to step S601. If data communication ends (Yes in step S607), STA 103 ends the data transmission process. As described above, STA 103 can send TAS traffic data to AP 102 at a predetermined transmission timing (time) in the wireless communication of BSS 101.

[0043] As described above, STA 103 can send TAS traffic data to AP 102 at a pre-scheduled time. This is achieved through operations performed between the STA and AP. Figure 5 and Figure 6 The process shown periodically sends TAS traffic data at preset intervals. By performing operations to execute communication at appropriately preset times based on the network topology, unnecessary standby time is reduced, thereby enabling low-latency communication.

[0044] Then, refer to Figure 7This describes an example of message flow sent / received between AP 102 and STA 103 during downlink (DL) communication. This process is performed when STA 103, as a subscriber, receives TAS traffic data from a device such as sensor device 107 operating as a publisher via bridge 104 and AP 102. First, STA 103 performs a scanning process to obtain network information from AP 102. For example, AP 102 broadcasts a beacon frame (M701) including network information to devices within the BSS 101 area. At this time, AP 102 may broadcast information that will be referenced later. Figure 9 or Figure 10 A beacon frame describing TAS scheme capability information. STA 103 can send a probe request frame (M702) to query the network information of AP 102 and obtain information from AP 102. In response to the probe request frame (“M702”), AP 102 sends a probe response frame (M703). For example, STA 103 can receive a beacon frame (M701) sent by AP 102 and obtain the network information of AP 102 from the beacon frame. Alternatively, STA 103 can actively send a probe request frame (M702) and receive a probe response frame (M703) from AP 102, thereby obtaining the network information of AP 102. In this case, the beacon frame (M701) and the probe response frame (M703) include information indicating whether AP 102 supports the TAS scheme, as TAS capability information. If the TAS scheme is supported, the TAS capability information contained in the frame can indicate whether only the control scheme, only the shaping scheme, or both schemes are supported. STA 103 can include and send its TAS capability information in a probe request frame (M702). Through these processes, STA 103 and AP 102 can exchange TAS capability information. However, TAS capability information can be exchanged through other messages such as association request / response frames (described later) without needing to exchange TAS capability information at this time.

[0045] After the scan process, STA 103 sends an association request frame (M704) to AP 102 to connect to BSS 101. In response to the association request frame (M704), AP 102 sends an association response frame (M705) to STA 103 indicating the connection result of STA 103. The association request frame and the association response frame may include TAS capability information. STA 103 may determine the TAS capability information to be included in the association request frame based on the TAS capability information of AP 102 obtained through the scan process. In one example, when both the shaping scheme and the control scheme are available, STA 103 may select the scheme to use based on the communication application of the TAS scheme and notify AP 102 of information indicating that only the selected scheme can be used. For example, if sensor device 107 acts as a publisher, STA 103, which can use both schemes, may send an association request frame (M704) to AP 102, which includes TAS capability information indicating that the device can only use the shaping scheme. Alternatively, if remote device 108 acts as a subscriber, STA 103, which can use either of these schemes, can send an association request frame (M704) to AP 102. This association request frame includes TAS capability information indicating that the STA can only use the control scheme. Similarly, AP 102 can determine the TAS capability information to include in the association response frame based on the TAS capability information of STA 103 included in the association request frame. In this way, TAS capability information is exchanged before a connection is established between AP 102 and STA 103.

[0046] Subsequently, after confirming that TAS communication is possible, AP 102 sends a management frame (M706) to STA 103. For example, information indicating the use of a shaping scheme is included in the TAS capability information during DL data communication in this management frame. The management frame may include, for example, information instructing the TAS scheme to follow its data transmission / reception schedule. Thereafter, STA 103, acting as a subscriber, periodically receives TAS traffic data (M707) from sensor device 107, acting as a publisher, via AP 102. For example, STA 103 performs reference... Figure 5 The described data reception processing is used to receive TAS traffic data (M707). For example, AP 102 performs the reference... Figure 6 The described data transmission process sends TAS traffic data (M707).

[0047] Then, refer to Figure 8This describes an example of message flow sent / received between AP 102 and STA 103 during UL communication. This process is performed when STA 103, acting as the publisher, sends TAS traffic data received by a device such as remote device 108 via AP 102 and bridge 104. In this example, messages M701 to M703 related to scan processing, information M704 to M705 related to STA connection processing, and management frame M706 are included. Figure 7 The same applies in the above. Note that since remote device 108 acts as a subscriber, STA 103, which can support both schemes, can include TAS capability information in the association request frame indicating that the device can only use the regulated scheme, and send the association request frame to AP 102. Note that in the management frame (M706), for example, information indicating the use of the regulated scheme is included in the TAS capability message during UL data communication. This management frame may include, for example, information indicating the TAS scheme according to its data transmission / reception schedule. Thereafter, STA 103, acting as a publisher, periodically sends TAS traffic data (M801) to remote device 108, acting as a subscriber, via AP 102. For example, STA 103 performs reference... Figure 6 The described data transmission process sends TAS traffic data (M801). For example, AP 102 performs the reference... Figure 5 The described data receiving and processing method is used to receive TAS traffic data (M801).

[0048] As described above, AP 102 and STA 103 can exchange TAS capability information from the device and determine whether to execute TAS protocol communication in subsequent communications, and which of the shaping and control protocols to use. Therefore, by executing [the protocol], which will be referred to later... Figure 15 and Figure 16 The described process can achieve low-latency communication by scheduling wireless communication based on time.

[0049] Next, we will refer to Figure 9The first example describing TAS capability information. Note that in this embodiment, the TAS capability information is named "TAS capability element," but the invention is not limited thereto. For example, other names, such as "TAS element," can be used. The TAS capability element has the same structure as another information element defined by the IEEE 802.11 standard. That is, the TAS capability element is formed by including an element ID field 901 for identifying the element, a length field 902 indicating the data length of the element, and element-specific information. The TAS capability element includes a TAS capability information field 903 as element-specific information. The TAS capability element is included, for example, in a MAC frame, such as a beacon frame, a probe request / response frame, or an association request / response frame. Note that the TAS capability element can be included in the MAC frame of a reassociation request / response frame. The TAS capability information field 903 includes information indicating whether the sender of the TAS capability element can use a TAS scheme and the available TAS schemes. This information is represented by, for example, 2 bits. Reference will be made later. Figure 11 An example describing information represented by 2 bits is provided. Note that in this example, the TAS capability information field 903 is 1 octet (8 bits) in size, but the invention is not limited thereto. The field name, as well as the position and size of the bits, are not limited to this. Figure 9 The example shown illustrates that similar information can be stored in different orders and with different sizes and field names.

[0050] Reference Figure 10 A second example describing TAS capability information. (Compared to...) Figure 9 The example shown is similar; the TAS capability element includes an element ID field (901) and a length field (902). This information can be replaced with... Figure 9 The information shown is included in the MAC frame of each of the aforementioned radio frames. In addition to the TAS capability information field 1001, Figure 10 The TAS capability element shown can be used with Figure 9 The same as shown. However, due to the different size of the TAS capability information field, the value stored in the length field 902 is different. Figure 9 and Figure 10 They are different. In Figure 10 In the example shown, the TAS capability information field 1001 is formed by information indicating the availability of TAS schemes, etc., and the availability of TAS schemes in each primary channel. A primary channel is a multi-link technology used to support the simultaneous use of multiple wireless channels, and is used to control the capability information of another wireless link and the transmission / reception of messages associated with connection and disconnection. Note that the relationship between primary channel and TAS scheme capability information will be referenced later. Figure 14 The following description will be provided. Note that in the following text, the primary channel is sometimes referred to as the "PCH".

[0051] TAS support field 1002 includes information indicating whether the sender of the TAS capability element can use a TAS scheme and the available TAS schemes. In one example, this information is represented by 2 bits. See later. Figure 11 Example of information represented by 2 bits. PCH 1 availability field 1003, PCH 2 availability field 1004, PCH 3 availability field 1005, PCH 4 availability field 1006, PCH 5 availability field 1007, PCH 6 availability field 1008, PCH 7 availability field 1009, PCH 8 availability field 1010, and PCH 9 availability field 1011 are fields that respectively indicate the availability of the TAS scheme in each of the main channels 1 through 9. The value stored in each of these fields, and what that value indicates, will be referenced later. Figure 12 The description continues. Reserved field 1012 is a 5-bit unused area for future expansion. An example is shown where the TAS capability information field 1001 has a size of 2 octets (16 bits), but the invention is not limited thereto. For example, similar information could be indicated by different field names at different bit positions of different field sizes. Note that in this embodiment, Figure 10 The element shown is named TAS Capability Element. However, the invention is not limited thereto; for example, other names may be used, such as TAS Multi-Link Element.

[0052] Reference Figure 11 describe Figure 9 or Figure 10 The TAS capability information shown indicates whether the sender can use the TAS scheme and provides examples of available TAS schemes. Note that the information indicating whether a TAS scheme can be used and the available TAS schemes is sometimes referred to as the TAS support status below. Reference Figure 11 The D-bit value 1101 indicates that it is stored in Figure 9 The TAS capability information field 903 shown is... Figure 10 The TAS support field 1002 shows a 2-bit data bit (D-bit) value. Note that the bit string represented by the D-bit value can be a TAS support ID. TAS support content 1102 represents the content corresponding to each TAS support ID. For example, a bit value "00" in D-bit value 1101 indicates that the TAS scheme is not supported (unavailable). A bit value "01" in D-bit value 1101 indicates that the TAS scheme is supported, but only the integer scheme can be used. A bit value "10" in D-bit value 1101 indicates that the TAS scheme is supported, but only the controlled scheme can be used. A bit value "11" in D-bit value 1101 indicates that the TAS scheme is supported, and both the controlled and integer schemes can be used. Note that the settings for each information element are not limited to this example; similar information can be represented by different field names or different values.

[0053] Figure 12 It shows the storage Figure 10 The values ​​for each of the following fields are shown: PCH 1 Availability Field 1003, PCH 2 Availability Field 1004, PCH 3 Availability Field 1005, PCH 4 Availability Field 1006, PCH 5 Availability Field 1007, PCH 6 Availability Field 1008, PCH 7 Availability Field 1009, PCH 8 Availability Field 1010, and PCH 9 Availability Field 1011, along with examples of the content corresponding to those values. In each of the PCH 1 availability field 1003, PCH 2 availability field 1004, PCH 3 availability field 1005, PCH 4 availability field 1006, PCH 5 availability field 1007, PCH 6 availability field 1008, PCH 7 availability field 1009, PCH 8 availability field 1010, and PCH 9 availability field 1011, an E bit 1201 is stored, which is configured such that the content 1202 differs depending on the combination with the value in the TAS support field 1002. For example, if two bits stored in the TAS support field 1002 indicate a control scheme (D bit value "10") or an integer scheme (D bit value "01"), then the E bit represents the availability of each TAS scheme. For example, setting the E bit to "1" can indicate that the TAS scheme represented by the D bit value can be used. Setting the E bit to "0" can indicate that the TAS scheme represented by the D bit value cannot be used. Note that this is merely an example to indicate that setting a "0" in the E bit enables the use of the TAS scheme represented by the D bit value, and setting a "1" in the E bit disables the use of the TAS scheme represented by the D bit value. Furthermore, if the two bits stored in the TAS support field 1002 indicate the use of a control scheme and an integer scheme (if the D bit value is "11"), one of the schemes can be specified by a single bit in the E bit. For example, a control scheme can be specified by setting a "1" in the E bit, and an integer scheme by setting a "0" in the E bit. Alternatively, a control scheme can be specified by setting a "0" in the E bit, and an integer scheme can be specified by setting a "1" in the E bit.

[0054] Reference Figure 13 Description of broadcasting via beacon frames Figure 10 The TAS capability information shown is an example of the processing procedure performed by AP 102. This processing begins, for example, when AP 102 is powered on or when the data collection process of the TAS scheme is initiated in AP 102. Note that this processing can be implemented, for example, when the control unit 202 of AP 102 executes a program stored in storage unit 201.

[0055] AP 102 determines whether it is set to... Figure 10 The multi-channel TAS information shown is included in the beacon frame in the mode (step S1301). If it is determined that the mode of including multi-channel TAS information in the beacon frame is not set ("No" in step S1301), then AP 102 performs the normal beacon frame setting process (step S1302). Then, AP 102 broadcasts the beacon frame obtained through the setting process in step S1302 in BSS 101 (step S1306). Note that in this case, AP 102 may send, for example, beacon frames including... Figure 9 The beacon frame showing the TAS information.

[0056] If the mode for including multi-channel TAS information in the beacon frame is set ("Yes" in step S1301), then AP102 is based on Figure 4 In step S405, the TAS scheme capability information stored determines the availability of each PCH among multiple PCHs (step S1303). To this end, AP 102 sends an RTS (Transmission Request) message. Then, after receiving an RTS message in each PCH, STA 103 performs carrier sensing in the PCH. If the PCH is not busy, after the SIFS (Short Interframe Space) period, STA 103 sends a CTS (Clear Transmission) message to AP 102. AP 102 confirms whether a CTS message has been received in each PCH that has received an RTS message, and identifies the PCH that has confirmed receiving the CTS message as an unavailable PCH. At this time, for PCHs that cannot confirm receiving the CTS message, AP 102's TAS capability information generation unit 301 identifies that TAS communication cannot be used.

[0057] Then, the TAS capability information generation unit 301 updates the availability information of the TAS scheme for each PCH in the TAS capability data. When the processing in step S1303 is completed for all available PCHs ("Yes" in step S1304), AP 102 stores the confirmed TAS capability information in storage unit 201 and sets the TAS capability information in the beacon frame (step S1305). AP 102 broadcasts a beacon frame including the TAS capability information in BSS 101 (step S1306). Note that including Figure 9 or Figure 10 The beacon frames showing TAS capability information can be broadcast across multiple PCHs.

[0058] As described above, AP 102 can include and transmit information for multiple PCHs in the beacon frame. This allows, for example, STA 103 to select and use a PCH in which communication can be performed, taking into account delay control based on TAS capability information. Among the PCHs with TAS capability information, a PCH with a signal bandwidth equal to or greater than a predetermined width can be selected, or a PCH with a large signal bandwidth can be preferentially selected. Among the PCHs in the TAS capability information, a PCH with a received field strength or signal-to-noise ratio (SNR) higher than a predetermined value can be selected, or a PCH with satisfactory values ​​can be preferentially selected. Among the PCHs in the TAS capability information, a PCH in which the channel transmission capacity calculated based on bandwidth and SNR is equal to or greater than a predetermined value can be selected, or a PCH with a large capacity can be preferentially selected. Among the PCHs in the TAS capability information, the PCH to be used can be selected based on idle channel information estimated from channel usage status during a predetermined time period. Conditions other than those PCH selection criteria can be used. Furthermore, one or more of the above selection criteria can be used in combination.

[0059] Reference Figure 14 Description of PCHs 1 through 9. PCHs 1 through 9 represent multiple PCHs available in the 5 GHz band. For example, PCHs 1 through 9 are channels with channel numbers 36, 44, 52, 60, 100, 108, 116, 124, and 132, each with a bandwidth of 20 MHz. Note that the 5 GHz band has been explained, but the same discussion applies to the 2.4 or 6 GHz bands. The above discussion applies not only to PCHs but also to any other channels.

[0060] Reference Figure 15 This description covers time-aware scheduling (TAS) traffic data transmission processing in the AP and STA according to this embodiment. As an example, AP 102 and STA 103 have... Figure 15 The diagram shows the arrangement used for TAS traffic data transmission. In Figure 15In the illustrated arrangement, before the state of ongoing communication of TAS traffic data is set, application 1501 receives TAS scheme information determined by the aforementioned TAS scheme determination unit 302. To perform transmission processing based on the TAS scheme information, application 1501 prepares for a data transmission request from MAC frame generation unit 304. Traffic classification function 1503 receives traffic data with added priority information from MAC frame generation unit 304 and maps temporarily restricted traffic data in TAS queue (Q0) 1504. Traffic classification function 1503 maps best-effort traffic data other than TAS traffic data in each of the BE queues (Q1 to Q4) 1505. TAS time gate control function 1502 temporarily stops / resumes each of TAS time gate control (G0) 1506 and various BE time gates (G1 to G4) 1507, thereby performing output control of the accumulated traffic data in each queue. For example, as described below, TAS time gate control function 1502 performs control to protect TAS traffic data while avoiding channel access contention.

[0061] Reference Figure 16 This describes the TAS traffic data transmission processing using multiple time gates (G0 to G4). Curve 1601 represents the open / closed state of TAS time gate (G0) 1506, and curves 1602 to 1605 represent the open / closed states of various BE time gates (G1 to G4) 1507, respectively. In these curves, "1" indicates an open state, and "0" indicates a closed state. If a time gate is open, data in the queue corresponding to that time gate can be output through the time gate. The guard time 1606 represents the time Tg during which transmission of all gates is blocked. This guard time 1606 prevents various BE traffic data from conflicting with TAS traffic data. Timing 1607 indicates the timing for periodically opening TAS time gate (G0) 1506. Timing To is generated for each period 1608. Period 1608 is defined by an interval Tp, in which data is transmitted at a strictly and periodically timed interval specified by the TAS traffic data transmission request. Time period 1609 represents the time interval Tc of opening TAS time gate (G0) 1506 of TAS queue (Q0) 1504, and represents the time period in which TAS traffic data is sent at strict and periodic intervals.

[0062] The TAS time gate control function 1502 performs gate control corresponding to the sending / receiving schedule of periodically repeating TAS traffic data. The TAS time gate control function 1502 can turn each time gate on or off by, for example, inputting a 0 or 1 bit to each time gate. The TAS time gate control function 1502 can indicate the open / closed state of the five time gates G0 to G4 via a 5-bit string. Each time gate can then extract its corresponding bit from the bit string and perform control over its open / closed state. The TAS time gate control function 1502 can output a 1-bit information indicating whether the time gate is closed or open to each time gate. The state of each time gate in the bit string will now be described. Note that the bit string represents the open / closed state of the time gates in the order of "G0·G1·G2·G3·G4". The bit string "00000" indicates a data blocking state. This state corresponds to a protection time of 1606, and all time gates (G0 to G4) are closed. The bit string "10000" indicates that only the TAS time gate (G0) 1506 is open, corresponding to time period 1609. The bit string "01111" indicates that the various BE time gates (G1 to G4) 1507 are open, and this state corresponds to a time period obtained, for example, by excluding time period 1609 and guard time 1606 from period 1608. Thus, the TAS time gate control function 1502 can control the closed / open state of each time gate through a 1-bit indicator.

[0063] As described above, when TAS traffic data is to be sent at a strictly timed interval, time gates (G0 to G4) can be used to process the TA traffic data without delay, while blocking data that should not be sent.

[0064] This invention can be implemented by providing a program for implementing one or more functions of the above embodiments to a system or device via a network or storage medium, and causing one or more processors in the computer of the system or device to read and execute the program. This invention can also be implemented by a circuit (e.g., an ASIC) for implementing one or more functions.

[0065] This invention is not limited to the embodiments described above, and various modifications and variations can be made within the spirit and scope of this invention. Therefore, in order to inform the public of the scope of this invention, the following claims are made.

Claims

1. A communication device, comprising: A communication unit for transmitting radio frames conforming to the IEEE 802.11 standard series to another communication device or receiving radio frames from another communication device. The Media Access Control (MAC) frame of a radio frame includes information about the scheduling of transmission opportunities based on time-constrained contention.

2. The communication device according to claim 1, wherein, Information regarding the scheduling of time-constrained contention-based transmission opportunities includes information indicating whether a device that has transmitted a radio frame can utilize the scheduling of time-constrained contention-based transmission opportunities.

3. The communication device according to claim 1 or 2, wherein, Information regarding the scheduling of time-constrained contention-based transmission opportunities includes information indicating which of the multiple scheduling schemes for time-constrained contention-based transmission opportunities can be used by the device that has transmitted the radio frame.

4. The communication device according to claim 1, wherein, MAC frames include information about the scheduling of transmission opportunities based on time-limit competition for each of multiple channels.

5. The communication device according to claim 4, wherein The MAC frame includes a first value indicating which of a plurality of schemes for scheduling transmission opportunities based on time-constrained contention can be used by the means that has transmitted the radio frame, and a second value for each of the plurality of channels, and, The combination of the first and second values ​​indicates whether scheduling based on time-limited contention for transmission opportunities can be used in each of the multiple channels, and indicates the availability of scheduling schemes under the condition of limited scheduling based on time-limited contention for transmission opportunities.

6. The communication device according to claim 1, wherein, When a radio frame containing information about the scheduling of transmission opportunities based on time-limited contention is transmitted, the communication unit sets the information about the scheduling of transmission opportunities based on time-limited contention based on the application performing the communication.

7. The communication device according to claim 1, wherein, Before a connection with another communication device is established, information about the scheduling of transmission opportunities based on time-constrained competition is sent to / received from / from that other communication device.

8. The communication device according to claim 1, wherein, A radio frame that includes a MAC frame is one of a beacon frame, probe request frame, probe response frame, association request frame, association response frame, reassociation request frame, and reassociation response frame.

9. The communication device according to claim 1, wherein, Information regarding the scheduling of time-constrained contention-based transmission opportunities indicates the scheduling for sending / receiving data frames to / from another communication device.

10. The communication apparatus of claim 9, wherein the information regarding the scheduling of time-constrained transmission opportunities includes a scheme for transmitting or receiving data frames, which is configured based on a scheme for scheduling time-constrained transmission opportunities that can be used by another communication apparatus and a scheme for scheduling time-constrained transmission opportunities that can be used by the communication apparatus.

11. The communication device according to claim 1, wherein, If a communication device cannot use a scheduling scheme based on time-limited contention for transmission opportunities that can be used by another communication device, then the information about time-based scheduling includes information indicating that a scheduling scheme based on time-limited contention for transmission opportunities cannot be used.

12. The communication device according to any one of claims 1 to 8, wherein, The other communication device is an access point device, and Upon receiving a schedule determined by the access point device, the communication unit transmits a data frame based on the received schedule after sending a radio frame containing information related to the schedule of transmission opportunities based on time constraints to the access point device.

13. A computer-readable storage medium storing a program for enabling a computer to function as a communication device according to any one of claims 1 to 11.

14. A control method executed by a communication device, comprising: Sending radio frames conforming to the IEEE 802.11 standard series to another communication device or receiving radio frames from another communication device. Among them, the MAC (Media Access Control) frame of the radio frame includes information about the scheduling of transmission opportunities based on time-limited contention.

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