Access point device, control method, and program

Abstract

To provide a mechanism for acquiring information for determining a TXOP to be assigned to each access point device when a plurality of access point devices performs cooperative communication, as one of objects.SOLUTION: An access point device transmits a request frame requesting a status of a transmission buffer to one or more other access point devices that perform cooperative communication, and receives a response frame including the status of the transmission buffer from other access point devices.SELECTED DRAWING: Figure 4

Description

[Technical field]

[0001] The present invention relates to an access point device for communicating information. [Background technology]

[0002] The Institute of Electrical and Electronics Engineers (IEEE) 802.11 standard is known as a communication standard related to wireless local area networks (LANs). The IEEE 802.11 standard series includes standards such as IEEE 802.11a / b / g / n / ac / ax / be (Patent Document 1). The IEEE 802.11be standard and its successors consider improving communication efficiency and throughput by having multiple access point devices (hereinafter simply referred to as APs) operate in cooperation with each other. A communication technology in which multiple APs operate in cooperation with each other is called multi-AP communication, and APs are classified into one Coordinator AP that manages all APs, and Coordinated APs that operate under the management of the Coordinator. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] JP 2018-050133 A Summary of the Invention [Problem to be solved by the invention]

[0004] As an example of multi-AP communication, a technology called Coordinated TDMA (Time Division Multiple Access) is being considered for improving efficiency, in which a portion of the TXOP (Transmission Opportunity) secured by one AP is shared and assigned to other APs, and multiple APs communicate cooperatively in a time-division manner.

[0005] However, the current wireless LAN standard does not define a mechanism for acquiring information to determine the TXOP to be assigned to each AP when multiple APs are performing cooperative communication.

[0006] The present invention has been made in consideration of the above-mentioned problems. One aspect of the present invention aims to provide a mechanism for acquiring information for determining a TXOP to be assigned to each AP when multiple APs perform cooperative communication. [Means for solving the problem]

[0007] An access point device according to one aspect of the present invention is an access point device that cooperates with one or more other access point devices to perform wireless communication compliant with the IEEE 802.11 standard, and is characterized by having a transmitting means for transmitting a request frame to the other access point devices to request the status of a transmission buffer, and a receiving means for receiving a response frame including the status of the transmission buffer from the other access point devices. Effect of the Invention

[0008] According to one aspect of the present invention, it is possible to provide a mechanism for acquiring information for determining a TXOP to be assigned to each AP when a plurality of APs perform cooperative communication. [Brief description of the drawings]

[0009] [Figure 1] FIG. 1 illustrates an example of the configuration of a communication system. [Diagram 2] FIG. 2 is a diagram illustrating a hardware configuration of an access point device. [Diagram 3] FIG. 2 is a diagram illustrating a software configuration of the access point device. [Figure 4] FIG. 11 is a sequence diagram illustrating a process when communication between APs 101 and 102 is DL (Down Link). [Diagram 5]FIG. 11 is a sequence diagram for explaining a process when communication between APs 101 and 102 is UL (Up Link). [Figure 6] FIG. 11 is a sequence diagram for explaining a process when the AP 102 is communicating in both DL and UL. [Figure 7] FIG. 2 is a diagram showing an example of a Trigger frame of the present invention. [Figure 8] FIG. 2 is a diagram showing a first example of a frame responding to a Trigger frame of the present invention. [Figure 9] FIG. 13 is a diagram showing a second example of a frame responding to a Trigger frame of the present invention. [Figure 10] FIG. 13 is a diagram showing a third example of a frame responding to a Trigger frame of the present invention. [Figure 11] This is an example of the control executed by the AP 100. [Figure 12] This is an example of the control executed by AP101 to AP102. [Figure 13] FIG. 13 is a diagram showing a fourth example of a frame responding to a Trigger frame of the present invention. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0010] Hereinafter, the embodiments will be described in detail with reference to the attached drawings. Note that the following embodiments do not limit the invention according to the claims. Although the embodiments describe a plurality of features, not all of these features are essential to the invention, and the plurality of features may be combined in any manner. Furthermore, in the attached drawings, the same reference numbers are used for the same or similar configurations, and duplicated descriptions are omitted.

[0011] <Communication system configuration> 1 shows an example of the configuration of a wireless communication system according to the present embodiment. This wireless communication system includes three access point devices (hereinafter simply referred to as AP, AP STA, or access point) and four station devices (hereinafter simply referred to as STA, Non-AP STA, or station). Hereinafter, APs 100-102 and STAs 120-123 are collectively referred to as communication devices.

[0012] The APs 100 to 102 are configured to be capable of communicating wireless frames that comply with the successor standard to the IEEE 802.11be standard, which has a maximum transmission speed of 46.08 Gbps and a maximum transmission speed of 90 Gbps to 100 Gbps. The STAs 120 to 122 are also configured to be capable of communicating wireless frames that comply with the successor standard.

[0013] Incidentally, IEEE is an abbreviation of Institute of Electrical and Electronics Engineers. The successor standard to 802.11be has the main features of supporting highly reliable communication and low latency communication, and AP cooperation. In light of the above, in this embodiment, the successor standard to IEEE802.11be, which aims for a maximum transmission speed of 90Gbps-100Gbps or more, is also called UHR (Ultra High Reliability) or IEEE802.11bn. In addition, a wireless frame communicated under the successor standard is also called UHR PPDU. PPDU is an abbreviation of PLCP Protocol Data Unit, and PLCP is an abbreviation of Physical Layer Convergence Protocol.

[0014] The names IEEE802.11bn and UHR standard are given for convenience in consideration of the goals to be achieved by the successor standard and the features that are the main features of the standard, and may be different names when the standard is completed. On the other hand, please note that this specification and the appended claims are essentially applicable to all successor standards that are successors to the 802.11be standard and can support the function of Coordinated TDMA communication in which multiple APs communicate cooperatively in a time-division manner.

[0015] 1 shows a wireless communication network including three APs and four STAs as an example, but the number of APs may be more or less than that shown in the figure. Although the APs 100 to 102 and the STAs 120 to 123 are described as supporting UHR PPDU communication (transmission and reception), they can also be configured to support PPDU communication of a legacy standard that is a standard that precedes the UHR standard. Specifically, the APs 100 to 102 and the STAs 120 to 123 can also be configured to support PPDU transmission and reception of the IEEE802.11a / b / g / n / ac / ax / be standard, etc.

[0016] AP100 to AP102 are APs that perform cooperative operations, and AP100 is an AP that performs overall control for the cooperation. In this embodiment, an AP such as AP100 that performs overall control is also called a Coordinator AP. Moreover, AP101 to AP102 are APs that function as controlled devices controlled by the Coordinator AP. In this embodiment, APs such as AP101 to AP102 that are controlled by the Coordinator AP are also called Coordinated APs. The roles of the Coordinator AP and the Coordinated AP may change dynamically. AP100 provides a network 110, AP101 provides a network 111, and AP102 provides a network 112. STA120 to STA123 are STAs that participate in a network provided by an access point.

[0017] In FIG. 1, STA120 to STA121 participate in a network 111 provided by AP101, and STA122 to STA123 participate in a network 112 provided by AP102. AP100 to 102 can perform MU (Multi User) communication, which uses OFDMA technology to communicate with multiple STAs simultaneously. In MU communication using OFDMA technology, one channel is divided into multiple sub-channels called RUs (Resource Units). Then, by treating each divided RU as a resource for communicating with a different STA (which may be a group of STAs consisting of multiple STAs), it is possible for the AP and multiple STAs to communicate simultaneously on one channel. In this case, an MU (Multi User) PPDU in which data is modulated by OFDMA is transmitted from the AP to one or more STAs. If all devices are compatible with the UHR standard, a UHR MU PPDU, which is an MU PPDU conforming to the UHR standard, is transmitted to one or more STAs.

[0018] The APs 100 to 102 and the STAs 120 to 123 may also be configured to support wireless communication based on other communication standards, such as Bluetooth (registered trademark), NFC, and Bluetooth (registered trademark) LE (Low Energy). NFC is an abbreviation for Near Field Communication. The APs 100 to 102 may also be configured to support wired communication using an Ethernet (registered trademark) cable or wired communication using optical fiber. Specific examples of the APs 100 to 102 and the STAs 120 to 123 include, but are not limited to, a wireless LAN router and a personal computer (PC). The APs 100 to 102 and the STAs 120 to 123 may also be information processing devices, such as wireless chips, that support the transmission and reception of UHR PPDU. Specific examples of the STAs 120 to 123 include, but are not limited to, a camera, a tablet, a smartphone, a PC, a mobile phone, a video camera, and a wearable device such as smart glasses.

[0019] In this embodiment, when the APs 100 to 102 provide a network, the BSSID of each network is different. Note that BSSID is an abbreviation for Basic Service Set Identifier, and is an identifier for identifying an access point.

[0020] Furthermore, each of the communication devices such as the APs 100 to 102 and the STAs 120 to 123 can communicate using bandwidths of 20 MHz, 40 MHz, 80 MHz, 160 MHz, 320 MHz, 480 MHz, and 640 MHz.

[0021] Next, a cooperative operation in which a plurality of APs consisting of APs 100 to 102 operate in cooperation will be described. APs 100 to 102 can perform cooperative operation. Specifically, AP 100 can perform a coordinated TDMA communication function in which a part of the secured TXOP (Transmission Opportunity) is shared and assigned to another AP, and a plurality of APs including AP 101 communicate at different timings. Each AP can perform DL (Down Link) communication and UL (Up Link) communication with a STA connected to itself using the TXOP assigned to itself. In this embodiment, AP 100 is a Coordinator AP that shares and assigns TXOP, but another AP that first secured TXOP may be the Coordinator AP, and the roles of Coordinator AP and Coordinator AP may be dynamically changed.

[0022] Hereinafter, a mechanism for performing the Coordinated TDMA communication function will be specifically described. In order to effectively describe the Coordinated TDMA function, in the wireless communication system of this embodiment, the APs 100 to 102 are described as providing a network in which STAs can participate, using the same operating frequency band and the same bandwidth.

[0023] (Device Configuration) 2 shows an example of the hardware configuration of an AP. The AP includes a storage unit 201, a control unit 202, a function unit 203, an input unit 204, an output unit 205, a communication unit 206, and antennas 207-209 as an example of the hardware configuration.

[0024] The storage unit 201 is configured with both or either one of a ROM and a RAM, and stores various information such as programs for performing various operations described below and communication parameters for wireless communication. RAM stands for Random Access Memory, and ROM stands for Read Only Memory. Note that, as the storage unit 201, in addition to memories such as ROM and RAM, storage media such as non-volatile storage devices such as hard disks and SSDs (Solid State Drives) may be used.

[0025] The control unit 202 is configured with, for example, a processor such as a CPU or MPU, an ASIC (Application Specific Integrated Circuit), a DSP (Digital Signal Processor), an FPGA (Field Programmable Gate Array), etc. Here, CPU is an acronym for Central Processing Unit, and MPU is an acronym for Micro Processing Unit. The control unit 202 executes the programs stored in the storage unit 201 and controls the entire device by operating hardware circuits such as ASIC. The control unit 202 may control the entire device in cooperation with the programs stored in the storage unit 201 and an OS (Operating System).

[0026] The control unit 202 controls the functional unit 203 to perform predetermined processing such as imaging, printing, and projection. The functional unit 203 is hardware for the device to perform predetermined processing. For example, when the communication device is a camera such as a digital still camera or a smartphone having a camera, the functional unit 203 is an imaging unit that performs imaging processing of surrounding images via a camera unit (not shown) of the communication device. For example, when the communication device is a printer, the functional unit 203 is a printing unit that performs printing processing on a sheet such as paper based on print data obtained from the outside through wireless communication. For example, when the communication device is a projector or smart glasses, the functional unit 203 is a projection unit that performs projection processing of image data or video data obtained from the outside through wireless communication. In the case of smart glasses, the projection surface is the retina of an end user. The data processed by the functional unit 203 may be data stored in the storage unit 201, or may be data communicated with other APs or STAs via the communication unit 206 described later. Furthermore, a communication device such as the AP 101 can provide a network storage function such as a NAS (Network Attached Storage). This function is provided to other communication devices as a Web service such as a network storage service. For example, a communication device such as an STA connects to a network storage service provided by the APs 101 to 103 using a protocol such as SMB, FTP, or WebDAV. The communication device such as an STA then uploads files to the storage service and downloads files from the storage. The data communication for uploading and downloading is also realized by communicating UHR PPDU between devices.

[0027] The input unit 204 receives various operations from the user. The output unit 205 outputs various types of information to the user. Here, the output by the output unit 205 includes 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 realized by a single module, such as a touch panel.

[0028] The communication unit 206 controls wireless communication conforming to the IEEE802.11 standard series and IP communication. In this embodiment, the communication unit 206 can transmit and receive UHR PPDU, which is a wireless frame of the UHR standard, and PPDU corresponding to the previous standard in cooperation with the antennas 207 to 209. The antennas 207 to 209 are antennas capable of transmitting and receiving signals in at least one of the frequency bands of the sub-GHz band, the 2.4 GHz band, the 5 GHz band, the 6 GHz band, the 7 GHz band, and the 60 GHz band, for example. In this embodiment, three antennas are provided, but one antenna may be provided, or a different antenna may be provided for each frequency band. In addition, when a plurality of antennas are provided, the communication unit 206 corresponding to each antenna may be provided.

[0029] If the communication device is compatible with the above-mentioned NFC standard, Bluetooth standard, or the like, the communication unit 206 may be configured to control wireless communication in compliance with these communication standards.

[0030] Next, the functional configuration of the APs 100 to 102 will be described with reference to Fig. 3. Note that Fig. 3 shows only the functional configuration required for explaining the TXOP allocation function. The AP has a frame processing unit 301, a TXOP allocation processing unit 302, and a frame transmission / reception unit 303.

[0031] Each function will be described. The frame processing unit 301 works with the antennas 207 to 209 to interpret various wireless frames received from the outside and notify the functions of a higher layer (not shown), and performs control processing of wireless communication based on the information obtained by interpretation. If the frame processing unit itself is a data transmission source communication device, it generates a data frame. The frame processing unit 301 is a block that generates a Multi-AP BSRP (Buffer Status Report Poll) Trigger frame to be transmitted to the APs 101 to 102 in order to acquire information for determining a TXOP in the case of the AP 100, acquires information for determining a TXOP from an AP BSR (Buffer Status Report) frame received from the APs 101 to 102, and generates a Trigger frame for allocating the determined TXOP to the APs 101 to 102. In addition, the frame processing unit 301 is a block that processes the Multi-AP BSRP Trigger frame received from AP100 in the case of AP101 to AP102, generates an AP BSR frame containing information for determining a TXOP, and processes the Trigger frame for assigning a TXOP received from AP100.

[0032] The TXOP allocation processing unit 302 determines the TXOP to be allocated to AP101 to AP102 based on the information for determining the TXOP included in the AP BSR frame acquired from AP101 to AP102 in the case of AP100. Also, the TXOP allocation processing unit 302 determines the TXOP allocated to itself according to the contents of the Trigger frame for allocating the TXOP in the case of AP101 to AP102, and communicates with the STA connected to itself.

[0033] The frame transmission / reception unit 303 cooperates with the antennas 207 to 209 to transmit wireless frames such as UHR PPDUs generated by the frame processing unit 301 to external APs and STAs. Specific formats of the Multi-AP BSRP Trigger frame and AP BSR frame will be described later.

[0034] Next, the procedure for acquiring information for determining the TXOP to be assigned to the Coordinated AP will be explained using the sequence diagrams in Figures 4 and 5. Figure 4 is a sequence diagram showing an example of wireless frame exchange when a Coordinated AP wants to perform DL communication with a STA connected to the Coordinated AP. DL communication refers to data communication from the AP to the STA.

[0035] The AP100, which is the Coordinator AP, transmits a Multi-AP BSRP Trigger frame 401, which is a request frame requesting information for determining a TXOP to be assigned to the Coordinated APs performing the cooperative operation. The APs 101 and 102 that receive the Multi-AP BSRP Trigger frame 401 transmit AP BSR frames 402 and 403, which include the transmission buffer state required for DL ​​communication with each STA connected to the AP100, as response frames to the AP100. In this embodiment, the Multi-AP BSRP Trigger frame 401 includes RU allocation information when each AP transmits an AP BSR frame, so that the APs 101 and 102 transmit the AP BSR frames 402 and 403 simultaneously using the RUs allocated by OFDMA communication. The transmission of the AP BSR frame is not limited to OFDMA communication, and the AP BSR may be transmitted in a time-division manner by TDMA communication according to the transmission order of the APs specified in the Multi-AP BSRP Trigger frame, for example.

[0036] The AP 100 that has received the AP BSR frames 402 to 403 can check the state of the transmission buffer required for DL ​​communication of each AP and determine the TXOP to be allocated.

[0037] The AP 100 that has determined the TXOP to be allocated notifies each of the APs 101 to 102 of the allocation information of the TXOP. The notification method is assumed to be, for example, transmission of MU-RTS TXS Trigger frames 404 and 406, but is not limited to this as long as the information of the TXOP to be allocated can be notified. The MU-RTS TXS Trigger frame is a frame used in the IEEE802.11be and later standards. The APs 101 to 102 that have received the notification execute DL communication processing with the STAs connected to them during the period of the assigned TXOP 405 and TXOP 406, respectively. In this embodiment, the MU-RTS TXS Trigger frame is transmitted to each of the APs 101 to 102 to notify the TXOP to be allocated, but a single frame may be used to indicate the TXOP information to be assigned to each of the APs 101 to 102 and the allocation order of the TXOP.

[0038] 5 is a sequence diagram showing an example of wireless frame exchange when a Coordinated AP wants to perform UL communication with a STA connected thereto. Note that UL communication refers to data communication from a STA to an AP.

[0039] The AP 100, which is a Coordinator AP, transmits a Multi-AP BSRP Trigger frame 501 requesting information for determining a TXOP to be assigned to the Coordinated APs performing the cooperative operation. The APs 101 to 102 that receive the Multi-AP BSRP Trigger frame 501 check the transmission buffer status of each STA in order to perform UL communication with the connected STAs 120 to 123. The Multi-AP BSRP Trigger frame 501 can include order information in which each AP transmits a BSRP Trigger frame, timing information in which each AP transmits an AP BSR frame, and RU allocation information when each AP transmits an AP BSR frame. In this embodiment, the order in which the BSRP Trigger frame is transmitted is AP 101, followed by AP 102. Therefore, the AP 101 first transmits the BSRP Trigger frame 502, and then receives notifications from the STAs by BSR frames 503 to 504, thereby acquiring the buffer status of each STA. The BSRP Trigger frame and the BSR frame are frames used in the IEEE802.11ax and later standards. Next, AP 102 transmits BSRP Trigger frame 505 and acquires the transmission buffer status of each STA by receiving notifications from the STAs via BSR frames 506-507. Next, AP 101 and AP 102 simultaneously transmit AP BSR frames 508-509 in RUs assigned by OFDMA communication according to timing information specified in Multi-AP BSRP Trigger frame 501. Transmission of AP BSR frames is not limited to OFDMA communication, and for example, AP BSRs may be transmitted in a time-division manner by TDMA communication according to the AP transmission order specified in the Multi-AP BSRP Trigger frame.In addition, if an AP that receives a Multi-AP BSRP Trigger frame is already aware of the transmission buffer status of the STAs connected to it, for example by sending a BSRP Trigger frame before receiving the Multi-AP BSRP Trigger frame, the AP may directly send an AP BSR frame without sending a BSRP Trigger frame again.

[0040] The AP 100 that has received the AP BSR frames 508 to 509 can check the state of the transmission buffer required for UL communication of each AP and determine the TXOP to be allocated.

[0041] After determining the TXOP to be allocated, AP100 notifies each of AP101 to AP102 of the allocation information of the TXOP using MU-RTS TXS Trigger frames 510 and 512, as in the case of Fig. 4. Upon receiving the notification, AP101 to AP102 execute UL communication processing with the STAs connected to themselves during the period of the allocated TXOP 511 and TXOP 513, respectively.

[0042] As described above with reference to FIGS. 4 and 5, the AP 100 that has transmitted the Multi-AP BSRP Trigger frame can obtain information for determining the TXOP to be assigned to the Coordinated AP.

[0043] 4 and 5, the DL communication and the UL communication have been explained separately, but Fig. 6 is a sequence diagram showing an example of wireless frame exchange when a Coordinated AP wants to perform both DL communication and UL communication. It is assumed that AP101 wants to perform only DL communication, and AP102 wants to perform both DL communication and UL communication.

[0044] The AP 100, which is the Coordinator AP, transmits a Multi-AP BSRP Trigger frame 601 to the Coordinated APs with which it is coordinating, requesting information for determining the TXOP to be assigned.

[0045] AP101, which has received the Multi-AP BSRP Trigger frame 601, responds to AP100 with an AP BSR frame 605 including the transmission buffer state required for DL ​​communication with each STA connected to itself at a predetermined timing as described in Fig. 5. Also, AP102, which has received the Multi-AP BSRP Trigger frame 601, transmits a BSRP Trigger frame 602 for checking the transmission buffer state of each STA as described in Fig. 5 when performing not only DL communication but also UL communication. AP102, which has received BSR frames 603-604 from STA122-123, notifies AP100 of the information including the transmission buffer state of each STA and the transmission buffer state required for itself to perform DL communication by including it in an AP BSR frame 606. AP100, which has determined the TXOP to be allocated, notifies each of AP101-AP102 of the allocation information of the TXOP using MU-RTS TXS Trigger frames 607-609 as in the case of Fig. 4. Upon receiving this notification, AP101 performs DL communication processing with the STA connected to itself during the period of the assigned TXOP608, and AP102 performs DL and UL communication processing with the STA connected to itself during the period of the assigned TXOP610.

[0046] As described above with reference to FIG. 6, even if the Coordinated AP wishes to perform both DL communication and UL communication, the AP 100 can obtain information for determining the TXOP to be assigned.

[0047] (Frame composition) Next, the structure of a frame communicated in this embodiment will be described with reference to FIG. 7 and FIG.

[0048] 7 is a diagram showing an example of a Multi-AP BSRP Trigger frame format transmitted by AP 100. The Frame Control field 701 is a field in which a value indicating that the frame is a Trigger frame used in, for example, IEEE802.11ax or later standards is entered. The Common Info field 702 indicates information common to multiple APs that are the destinations of this Trigger frame. The Trigger Type field 703 contains information for identifying the Trigger frame as shown in Table 1. The Trigger Dependent Common Info field 704 contains information that is dependent on each Trigger frame.

[0049] [Table 1]

[0050] The Trigger frame shown in Fig. 7 is called, for example, a Multi-AP BSRP Trigger frame. In that case, the Trigger Type field 703 is set to "8." Alternatively, for example, a new Trigger Type for the Multi-AP BSRP Trigger frame may be defined and used from the values ​​marked as Reserved in Table 1.

[0051] Also, a new Trigger Type may be defined and used to distinguish whether the information on the transmission buffer status to be responded is for DL ​​communication or UL communication. A Coordinated AP that receives a Trigger frame for DL ​​communication responds with information on the transmission buffer status required for DL ​​communication. This Trigger frame for DL ​​communication is called, for example, a Multi-AP-BSRP DL Trigger frame, and the Trigger Type is defined as "9". On the other hand, a Coordinated AP that receives a Trigger frame for UL communication responds with information on the transmission buffer status required for UL communication. This Trigger frame for UL communication is called, for example, a Multi-AP-BSRP UL Trigger frame, and the Trigger Type is defined as "10". A new Trigger Type may be defined and used to indicate that the Trigger frame is for both UL communication and DL communication. It may be defined from the values ​​marked as Reserved, or the Multi-AP BSRP Trigger frame defined as "8" may be used.

[0052] Also, instead of using Trigger Type as identification information for distinguishing between DL communication and UL communication, other information may be used for the distinction. For example, a field for setting information for distinguishing between them may be prepared in the Trigger Dependent Common Info field 704. For example, a Direction field 705 may be prepared, and a value of "0" in this field indicates DL communication, a value of "1" indicates UL communication, and a value of "2" indicates both DL and UL communication. A Coordinated AP that receives a Trigger frame with a Trigger Type of "8" can check this subfield to distinguish between DL communication and UL communication.

[0053] The Trigger Dependent Common Info field 704 may include a BSRP required field 706 indicating whether or not the AP that received the Multi-AP BSRP Trigger frame should transmit the BSRP Trigger frame to the STA connected to the AP. For example, if the BSRP required field 706 is set to "0", the transmission of the BSRP Trigger frame is not required, and if the BSRP required field 706 is set to "1", the transmission of the BSRP Trigger frame is required. If the BSRP required field is set to "0" or if the AP already knows the transmission buffer state of the STA connected to the AP, the AP BSR frame may be transmitted without transmitting a BSRP Trigger frame again. The BSRP order field 707 is information indicating the transmission order when each AP is made to transmit a BSRP Trigger frame. For example, a list of BSSIDs indicating the transmission order of the APs may be included, or a list of BSS colors may be included. The Feedback Timing field 708 includes information indicating the timing at which each AP transmits an AP BSR frame. For example, the time until the AP BSR is transmitted based on the reception time of the Multi-AP BSRP Trigger frame may be indicated in microseconds or milliseconds. In addition to requesting the AP for the transmission buffer status, a TX Parameter Required field 712 may be included to indicate a request for the AP's transmission parameters for DL ​​communication or the STA's transmission parameters for UL communication. The transmission parameters include, for example, in the case of DL communication, information on the MCS (Modulation and Coding Scheme) and transmission power to be applied to the PPDU transmitted by the AP when the AP performs DL communication with the STA connected thereto. The transmission parameters also include, for example, in the case of UL communication, information on the MCS and transmission power to be applied to the PPDU transmitted by the STA when the AP performs UL communication with the STA connected thereto.For example, if the TX Parmeter Required field 712 is set to "0", it is not necessary to include a transmission parameter in the AP BSR frame, and if the TX Parmeter Required field 712 is set to "1", it is necessary to include a transmission parameter in the AP BSR frame. The Coordinator AP can more accurately determine the TXOP to be assigned to the Coordinator AP by acquiring the transmission parameters for DL ​​communication or UL communication in addition to the transmission buffer capacity for DL ​​communication or UL communication of the Coordinator AP. In the example of FIG. 7, the TX Parmeter Required field 712 is a field indicating that the transmission parameters of the AP for DL ​​communication and the transmission parameters of the STA for UL communication are requested, but the field may be divided into those for DL ​​communication and those for UL communication.

[0054] The User Info field 709 stores information specific to each AP. The AP ID field 710 stores information for identifying the AP, such as the BSSID and BSS color. The RU Allocation field 711 is information indicating the OFDMA RUs allocated to the AP specified in the AP ID field 710. Each AP can simultaneously transmit AP BSR frames by OFDMA communication using the allocated RUs.

[0055] Furthermore, the Frame Control field 701 includes a Type subfield and a Subtype subfield that indicate the frame type. In this embodiment, a frame in which "01" is set in the Type subfield and "0010" is set in the Subtype subfield is defined as a Multi-AP-BSRP Trigger frame. Note that the Type subfield and the Subtype subfield may have different values ​​as long as the Multi-AP-BSRP Trigger frame can be identified. For example, as shown in Table 2, a frame in which "11", indicating Extension, is set in the Type subfield and "0011" or the like is set in the Subtype subfield can be defined as a Multi-AP-BSRP Trigger frame.

[0056] [Table 2]

[0057] Note that the Multi-AP BSRP Trigger frame is an example of a name of a frame for requesting information for determining a TXOP to be assigned to an access point, and may have a different name.

[0058] FIG. 8 shows an example of the configuration of an AP BSR frame used by AP101-AP102 when notifying AP100. Information indicating the transmission buffer status for DL ​​communication is included in a DL Buffer Status field 801. The DL Buffer Status field 801 includes queue sizes of TIDs (Traffic Identifiers) #0-#15, and for example, 803 indicates a total queue size obtained by aggregating the transmission buffer status of data of TID#0 addressed to all STAs. Information indicating the transmission buffer status for UL communication is included in a UL Buffer Status field 802. The UL Buffer Status field 802 includes queue sizes of TIDs #0-#15, and for example, 804 indicates a total queue size obtained by aggregating the transmission buffer status of all STAs having data of TID#0. The queue size may indicate the number of octets indicating the data size, or may indicate the number of data blocks of a predetermined number of octets. Also, the queue size of TIDs #0-#15 may be indicated for each STA.

[0059] Fig. 9 shows another example of the configuration of an AP BSR frame. In the example of Fig. 8, all the queue sizes of TID#0 to #15 are included in one DL Buffer Status field, but in Fig. 9, one DL Buffer Status field includes a TID field 903 for identifying the TID and a Queue size field 904 for indicating the transmission buffer status. 904 indicates the total queue size obtained by aggregating the transmission buffer status of all STA data of the TID specified in the TID field 903. Similarly, the UL Buffer Status field 902 also includes a TID field 905 for identifying the TID and a Queue size field 906 for indicating the UL transmission buffer status of the TID specified in the TID field 905. When data of multiple TIDs is buffered, the AP BSR frame can include multiple DL Buffer Status fields or UL Buffer Status fields.

[0060] Figure 10 shows another example of the configuration of an AP BSR frame. In Figures 8 and 9, the fields showing the transmission buffer status are shown separately for DL ​​communication and UL communication, but in Figure 10, a single field is used that aggregates the transmission buffer status for DL ​​communication and UL communication. The Aggregated Buffer Status field 1001 contains the total Queue size that is an aggregate of the transmission buffer status for DL ​​communication and the transmission buffer status for UL communication.

[0061] Although the queue size for each TID is shown in FIG. 8 and FIG. 9, the queue size may be the total queue size for all TIDs.

[0062] 13 shows another example in which the Queue size for each STA is indicated in the DL Buffer Status field and the UL Buffer Status field in the AP BSR frame. Information indicating the transmission buffer status for DL ​​communication is included in the DL Buffer Status field 1300. The DL Buffer Status field 1300 includes a STAID (Station Identifier) ​​field 1301, which includes information for identifying the STA connected to the Coordinated AP. The STAID field 1301 includes, for example, the MAC address of the STA and AID (Association Identifier) ​​information. The Queue Size field 1302 includes information indicating the size of the transmission buffer for data addressed to the STA identified in the STAID field 1301. The TX Parameter field 1303 stores transmission parameters that are applied when the Coordinated AP transmits data addressed to the STA identified in the STAID field 1301. The transmission parameters include, for example, an MCS field 1304 and a TX Power field 1305. The MCS field 1304 includes information on a modulation method, such as QPSK (Quadrature Phase Shift Keying) or 16QAM (Quadrature Amplitude Modulation), and information on a coding rate. The TX Power field 1305 indicates a transmission power value when the MCS specified in the MCS field 1304 is applied to the PPDU to be transmitted. When the Coordinated AP receives a Multi-AP BSRP Trigger frame with the TX Parameter Required field set to 1 from the Coordinator AP, the Coordinated AP may include the TX Parameter field 1303 in the AP BSR frame.The Coordinator AP that has acquired this information can calculate the communication time required to transmit data of the size specified in the Queue Size field 1302 with the transmission parameters specified in the TX Parameter field 1303, and can more accurately estimate the TXOP to be assigned to the Coordinated AP. In the example of Fig. 13, the AP BSR frame includes DL Buffer Status information for one STA, but the AP BSR frame may include information for multiple STAs.

[0063] Information indicating the state of the transmission buffer for UL communication is included in a UL Buffer Status field 1310. The UL Buffer Status field 1310 includes a STAID (Station Identifier) ​​field 1311, which includes information for identifying a STA connected to the Coordinated AP. The Queue Size field 1312 includes information indicating the size of a transmission buffer for data addressed to the Coordinated AP by a STA identified in the STAID field 1301. The TX Parameter field 1313 stores transmission parameters that are applied when a STA connected to the Coordinated AP identified in the STAID field 1311 transmits data addressed to the Coordinated AP. The transmission parameters include, for example, an MCS field 1314 and a TX Power field 1315. The Coordinator AP that acquires this information can calculate the communication time required to transmit data of the size specified in the Queue Size field 1312 with the transmission parameters specified in the TX Parameter field 1313, and can more accurately estimate the TXOP to be assigned to the Coordinated AP. In the example of FIG. 13, the AP BSR frame includes UL Buffer Status information for one STA, but the AP BSR frame may include information for a plurality of STAs.

[0064] The AP BSR frame in this embodiment is an example of a name of a frame for notifying information for determining a TXOP to be assigned to an access point, and may have a different name.

[0065] (Processing flow) The control of the TXOP determination process executed in the Coordinator AP of the present invention will be described with reference to the flowchart in Fig. 11. The AP 100 starts this process in response to determining that a part of the TXOP reserved by itself is to be allocated to the Coordinator AP.

[0066] First, AP100 generates a Multi-AP BSRP Trigger frame requesting information for determining the TXOP to be assigned (S1101). For example, when using the Multi-AP BSRP Trigger frame in FIG. 7, "8" indicating Multi-AP BSRP Trigger is set in the Trigger Type field 703. In addition, various fields included in the Trigger Dependent Common Info field 704 and a User Info field that is information specific to each AP are set. Next, AP100 transmits the Multi-AP BSRP Trigger frame (S1102). This frame is broadcast to the surroundings including AP101 and AP102.

[0067] Then, the AP 100 receives the AP BSR frame transmitted by the APs 101 and 102 as a response to the Multi-AP BSRP Trigger frame (S1103), and acquires information included in the AP BSR frame (S1104). Then, based on the information on the transmission buffer state included in the AP BSR frame, the AP 100 determines the TXOP to be assigned to each Coordinated AP (S1105). In addition, the method of determining the TXOP may determine the ratio of the TXOP to be assigned to each AP according to the ratio of the buffer amount indicated in each AP BSR frame. In addition, the communication time required to transmit the buffer amount of data indicated in each AP BSR frame may be calculated, and the TXOP to be assigned may be determined, or the TXOP to be assigned to each AP may be determined based on the buffer amount of a TID with a high priority. The transmission parameter information acquired from the Coordinated AP may be used to calculate the communication time required to transmit the data. For example, when the transmission parameter information includes MCS, it is possible to determine the data rate of the physical layer, and therefore the communication time may be determined based on the data rate and the buffer amount. Also, when the transmission parameters include information on transmission power, the communication time may be calculated when the transmission power of the Coordinated AP or the STA connected to the Coordinated AP is changed. For example, when the transmission power is increased to a level higher than the transmission power notified in the AP BSR frame, it may be possible to increase the data rate of the physical layer and shorten the communication time by applying an MCS with a higher data rate than the MCS notified in the AP BSR frame. When the transmission power is changed, the Coordinator AP may instruct the Coordinated AP or the STA connected to the Coordinated AP to change the transmission power by including information on the changed transmission power in the MU-RTS TXS Trigger frame for allocating a TXOP.

[0068] As described above, the Coordinator AP can obtain information on the transmission buffer status by transmitting a Trigger frame requesting information for determining the TXOP to be assigned to the Coordinated AP. The AP 100 that has obtained the information on the transmission buffer status from the Coordinated AP can determine the TXOP to be assigned to the Coordinated AP.

[0069] Next, the control executed in the Coordinated AP of the present invention will be described with reference to the flowchart in Fig. 12. AP101 and AP102 start this process in response to determining that they have received a Multi-AP BSRP Trigger frame requesting information for determining the TXOP to be assigned by the Coordinator AP. The following description will be given with AP101 as the subject, but AP102 also performs the same process.

[0070] First, the AP 101 judges whether or not a TXOP is required for DL ​​communication (S1201). For example, when using the Multi-AP BSRP Trigger frame of FIG. 7, the AP 101 may judge whether or not DL communication is required based on the Direction field 705, or the AP 101 itself may judge whether or not DL communication is required regardless of the contents of the Multi-AP BSRP Trigger frame. When the AP 101 judges in S1201 that a TXOP is required for DL ​​communication, the AP 101 acquires the transmission buffer status required for DL ​​communication (S1202). Next, the AP 101 judges whether or not a TXOP is required for UL communication (S1203). If a TXOP is required only for DL ​​communication, the AP 101 transmits an AP BSR frame including information indicating the required transmission buffer status to the Coordinator AP (S1204). For example, when using the AP BSRP frame of FIG. 8, the AP 101 transmits information indicating the required transmission buffer status by setting it in the DL Buffer Status field.

[0071] On the other hand, if it is determined in S1201 that the TXOP is not necessary for DL ​​communication, or if it is determined in S1203 that the TXOP is necessary for UL communication, the AP 101 transmits a BSRP Trigger frame to notify the transmission buffer status of the STA connected to the AP 101 (S1205). If the AP 101 already knows the transmission buffer status of the connected STA, the processes of S1205 and S1206 may be skipped. Next, the AP 101 that transmitted the BSRP Trigger frame in S1205 receives a BSR frame including the transmission buffer status from the STA (S1206) and acquires the transmission buffer status included in the received BSR frame (S1207). Then, the AP 101 transmits a response including the information on the transmission buffer status indicated by the AP BSR frame to the Coordinator AP (S1204). For example, when the AP BSRP frame in FIG. 8 is used, the information indicating the required transmission buffer status is set in the UL Buffer Status field and transmitted. When the transmission buffer status of each STA is not included in the UL Buffer Status field as in Fig. 8, the transmission buffer status obtained by aggregating the transmission buffer status included in the BSR frame of each STA for each TID is stored in that field. Also, when using an AP BSR frame in which the transmission buffer status for DL ​​and the transmission buffer status for UL are aggregated in one field as in Fig. 10, the transmission buffer status obtained by aggregating the transmission buffer status included in the BSR frame of each STA and the transmission buffer status of the AP is stored in that one field.

[0072] In this way, the Coordinated AP can respond to a Multi-AP BSRP Trigger frame requesting information to determine the TXOP to be allocated.

[0073] (Other variations) In the above-mentioned embodiments, the Coordinated AP responds with information on the transmission buffer status in response to the Trigger frame transmitted by the Coordinator AP, but the present invention is not limited to this. Any information necessary for the Coordinator AP to determine the TXOP to be assigned may be used, and instead of the information on the transmission buffer status, the Coordinator AP may respond with information on the communication time to be assigned by the Coordinator AP. For example, the communication time may be specified in units of microseconds or milliseconds, or in multiples of a predetermined time unit.

[0074] (Other embodiments) The present invention can also be realized by a process in which a program for implementing one or more of the functions of the above-described embodiments is supplied to a system or device via a network or a storage medium, and one or more processors in a computer of the system or device read and execute the program. The present invention can also be realized by a circuit (e.g., ASIC) that implements one or more of the functions.

[0075] The invention is not limited to the above-described embodiments, and various modifications and variations are possible without departing from the spirit and scope of the invention. Accordingly, the following claims are appended to apprise the public of the scope of the invention.

[0076] (Summary of the embodiment) At least some of the above-described embodiments can be summarized as follows.

[0077] (Item 1) An access point device that cooperates with one or more other access point devices and performs wireless communication conforming to the IEEE 802.11 standard, a transmission means for transmitting a request frame to the other access point device to request a status of a transmission buffer; a receiving means for receiving a response frame including a state of a transmission buffer from the other access point device; An access point device comprising:

[0078] (Item 2) The request frame: The information includes information indicating a request for a state of a transmission buffer of the other access point device in DL (Down Link) communication of the other access point device. 2. The access point device according to item 1,

[0079] (Item 3) The request frame: The information includes information indicating a request for a status of a transmission buffer of one or more stations connected to the other access point device in the UL (Up Link) communication of the other access point device. 3. The access point device according to item 1 or 2,

[0080] (Item 4) The request frame: The information includes information requesting acquisition of a transmission parameter of the other access point device in the DL communication. 4. The access point device according to any one of items 1 to 3,

[0081] (Item 5) The request frame: The information includes information requesting acquisition of transmission parameters of one or more stations connected to the other access point device in the UL communication. 5. The access point device according to any one of items 1 to 4,

[0082] (Item 6) The request frame: and information regarding an order for acquiring the status of a transmission buffer of one or more stations connected to the other access point device in the UL communication. 6. The access point device according to any one of items 1 to 5,

[0083] (Item 7) The request frame: including information regarding the timing of transmitting the response frame; 7. The access point device according to any one of items 1 to 6,

[0084] (Item 8) The response frame comprises: The state of the transmission buffer of the other access point device in the DL communication is included. 8. The access point device according to any one of items 1 to 7,

[0085] (Item 9) The response frame comprises: The status of a transmission buffer of one or more station devices connected to the other access point devices in the UL communication is included. 9. The access point device according to any one of items 1 to 8,

[0086] (Item 10) The response frame comprises: Including transmission parameters of the other access point devices in the DL communication, 10. The access point device according to any one of items 1 to 9,

[0087] (Item 11) The response frame comprises: including transmission parameters of one or more stations connected to the other access point device in the UL communication; 11. The access point device according to any one of items 1 to 10,

[0088] (Item 12) The response frame comprises: The information includes information summarizing the states of the transmission buffers of one or more station devices connected to the other access point devices. 12. The access point device according to any one of items 1 to 11,

[0089] (Item 13) The response frame comprises: The information includes information summarizing the state of the transmission buffer of the other access point device and the state of the transmission buffer of one or more station devices connected to the other access point device. 13. The access point device according to any one of items 1 to 12,

[0090] (Item 14) An access point device that cooperates with one or more other access point devices and performs wireless communication conforming to the IEEE 802.11 standard, a transmission means for transmitting a request frame requesting communication time to the other access point device; a receiving means for receiving a response frame including a communication time from the other access point device; An access point device comprising:

[0091] (Item 15) The request frame: The information includes information indicating that the other access point device requests communication time for DL ​​(Down Link) communication of the other access point device. Item 15. The access point device according to item 14,

[0092] (Item 16) The request frame: The information includes information indicating that one or more stations connected to the other access point device are requesting communication time in the UL (Up Link) communication of the other access point device. 16. The access point device according to item 14 or 15,

[0093] (Item 17) The request frame: information regarding an order in which the communication time of one or more stations connected to the other access point device is acquired; 17. The access point device according to any one of items 14 to 16,

[0094] (Item 18) The response frame includes a communication time of the other access point device in the DL communication. 18. The access point device according to any one of items 14 to 17,

[0095] (Item 19) The response frame comprises: The communication time of one or more station devices connected to the other access point device in the UL communication is included. 19. An access point device according to any one of items 14 to 18,

[0096] (Item 20) The response frame comprises: The information includes information summarizing communication times of one or more station devices connected to the other access point devices. 20. An access point device according to any one of items 14 to 19, characterized in that

[0097] (Item 21) The response frame comprises: The information includes information summarizing the communication time of the other access point device and the communication time of one or more station devices connected to the other access point device. 21. The access point device according to any one of items 14 to 20,

[0098] (Item 22) A method for controlling an access point device that cooperates with one or more other access point devices and performs wireless communication conforming to the IEEE 802.11 standard, comprising the steps of: a transmission step of transmitting a request frame to the other access point device to request a status of a transmission buffer; a receiving step of receiving a response frame including a status of a transmission buffer from the other access point device; A control method comprising:

[0099] (Item 23) A method for controlling an access point device that cooperates with one or more other access point devices and performs wireless communication conforming to the IEEE 802.11 standard, comprising the steps of: a transmission step of transmitting a request frame to request communication time to the other access point device; a receiving step of receiving a response frame including a communication time from the other access point device; A control method comprising:

[0100] (Item 24) 24. A program for causing a computer to execute the method for controlling an access point device according to claim 22 or 23.

[0101] The invention is not limited to the above-described embodiments, and various modifications and variations are possible without departing from the spirit and scope of the invention. Accordingly, the following claims are appended to apprise the public of the scope of the invention. [Explanation of symbols]

[0102] 100 AP 101 AP 102 AP 110 Network 111 Network 112 Network 120 STA 121STA 122 STA 123 STA

Claims

1. An access point device that cooperates with one or more other access point devices to perform wireless communication conforming to the IEEE 802.11 standard, a transmission means for transmitting a request frame to the other access point device to request a status of a transmission buffer; a receiving means for receiving a response frame including a state of a transmission buffer from the other access point device; An access point device comprising:

2. The request frame: The information includes information indicating a request for a state of a transmission buffer of the other access point device in DL (Down Link) communication of the other access point device.

2. The access point device according to claim 1,

3. The request frame: The information includes information indicating a request for a state of a transmission buffer of one or more stations connected to the other access point device in an UL (Up Link) communication of the other access point device.

2. The access point device according to claim 1,

4. The request frame: The DL communication includes information requesting acquisition of a transmission parameter of the other access point device.

3. The access point device according to claim 2,

5. The request frame: and information requesting acquisition of transmission parameters of one or more stations connected to the other access point device in the UL communication.

4. The access point device according to claim 3.

6. The request frame: and information regarding an order for acquiring the status of a transmission buffer of one or more stations connected to the other access point device in the UL communication.

4. The access point device according to claim 3.

7. The request frame: including information regarding the timing of transmitting the response frame; 2. The access point device according to claim 1,

8. The response frame comprises: The state of the transmission buffer of the other access point device in the DL communication is included.

2. The access point device according to claim 1,

9. The response frame comprises: The status of a transmission buffer of one or more station devices connected to the other access point device in the UL communication is included.

2. The access point device according to claim 1,

10. The response frame comprises: including a transmission parameter of the other access point device in the DL communication, 9. The access point device according to claim 8,

11. The response frame comprises: and including transmission parameters of one or more stations connected to the other access point device in the UL communication.

10. The access point device according to claim 9,

12. The response frame comprises: The information includes information summarizing the states of the transmission buffers of one or more station devices connected to the other access point devices.

2. The access point device according to claim 1,

13. The response frame comprises: The information includes information summarizing the state of the transmission buffer of the other access point device and the state of the transmission buffer of one or more station devices connected to the other access point device.

2. The access point device according to claim 1,

14. An access point device that cooperates with one or more other access point devices to perform wireless communication conforming to the IEEE 802.11 standard, a transmission means for transmitting a request frame requesting communication time to the other access point device; a receiving means for receiving a response frame including a communication time from the other access point device; An access point device comprising:

15. The request frame: The information includes information indicating that communication time of the other access point device is requested in DL (Down Link) communication of the other access point device.

15. The access point device according to claim 14,

16. The request frame: The information includes information indicating that one or more stations connected to the other access point device request communication time in UL (Up Link) communication of the other access point device.

15. The access point device according to claim 14,

17. The request frame: information regarding an order in which the communication time of one or more stations connected to the other access point device is acquired; 17. The access point device according to claim 16,

18. The response frame comprises: The communication time of the other access point device in the DL communication is included.

15. The access point device according to claim 14,

19. The response frame comprises: The communication time of one or more station devices connected to the other access point device in the UL communication is included.

15. The access point device according to claim 14,

20. The response frame comprises: The information includes information summarizing communication times of one or more station devices connected to the other access point devices in the UL communication.

15. The access point device according to claim 14,

21. The response frame comprises: The information includes information summarizing the communication time of the other access point device and the communication time of one or more station devices connected to the other access point device.

15. The access point device according to claim 14,

22. A method for controlling an access point device that cooperates with one or more other access point devices to perform wireless communication conforming to the IEEE 802.11 standard, comprising the steps of: a transmission step of transmitting a request frame to the other access point device to request a status of a transmission buffer; a receiving step of receiving a response frame including a status of a transmission buffer from the other access point device; A control method comprising:

23. A method for controlling an access point device that cooperates with one or more other access point devices to perform wireless communication conforming to the IEEE 802.11 standard, comprising the steps of: a transmission step of transmitting a request frame to request communication time to the other access point device; a receiving step of receiving a response frame including a communication time from the other access point device; A control method comprising:

24. A program for causing a computer to execute the method for controlling an access point device according to claim 22 or 23.

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