Communication device, communication method, and program

Abstract

This communication device, which functions as an access point of the IEEE 802.11 standard, generates, on the basis of a timing at which a Beacon frame is transmitted by the communication device, a prescribed frame including information indicating a scheduled period of cooperative operation with another communication device, which functions as an access point, and transmits a frame including the information to the other access point, and thereby performs communication in cooperation with the other access point during the period.

Description

Communication device, communication method, and program

[0001] The present invention relates to a cooperative communication technique using multiple access points.

[0002] The Institute of Electrical and Electronics Engineers (IEEE) 802.11 series of standards is known as a communication standard for wireless LANs (Local Area Networks). The IEEE 802.11 series of standards includes standards such as IEEE 802.11a / b / g / n / ac / ax / be / bn. For the IEEE 802.11be standard and its successor standards, the introduction of technology that improves communication efficiency and throughput by cooperatively operating multiple access points (hereinafter sometimes referred to as "APs") is being considered (see Non-Patent Document 1).

[0003] IEEE802.11-23 / 1461r1, Considerations on Multi-AP Operation

[0004] When a plurality of APs cooperate to communicate, it is necessary for the plurality of APs to share information about the period during which they will cooperate.

[0005] The present invention provides a technique for appropriately sharing information about a period during which a plurality of access points operate cooperatively.

[0006] A communication device according to one aspect of the present invention functions as an access point of the IEEE 802.11 standard, and includes: a generating means for generating a predetermined frame containing information representing a planned period of cooperative operation with other communication devices functioning as access points, based on the timing at which a beacon frame is transmitted by the communication device; and a communication means for transmitting the predetermined frame containing the information to the other access points, thereby communicating in cooperation with the other access points during the period.

[0007] According to the present invention, information on the period during which cooperative operation is performed can be appropriately shared among a plurality of access points.

[0008] Other features and advantages of the present invention will become apparent from the following description taken in conjunction with the accompanying drawings, in which the same or similar elements are designated by the same reference numerals.

[0009] The accompanying drawings are incorporated into and constitute a part of the specification, illustrate embodiments of the present invention, and together with the description are used to explain the principles of the present invention. FIG. 1 is a diagram showing an example of the configuration of a wireless communication system. FIG. 2 is a diagram showing an example of the hardware configuration of an AP. FIG. 3 is a diagram showing an example of the functional configuration of an AP. FIG. 4 is a diagram showing an example of cooperative operation by multiple APs. FIG. 5 is a diagram showing an example of operation in a cooperative operation request phase. FIG. 6 is a diagram showing an example of an information element indicating a period during which multiple APs will cooperate. FIG. 7 is a diagram showing an example of operation in a cooperative operation phase. FIG. 8 is a diagram showing an example of the flow of processing performed by an AP. FIG. 9 is a diagram showing an example of the flow of processing performed by a Sharing AP. FIG. 10 is a diagram showing an example of the flow of processing performed by a Shared AP. FIG. 11 is a diagram showing an example of the flow of processing performed by a STA.

[0010] Hereinafter, embodiments will be described in detail with reference to the accompanying drawings. Note that the following embodiments do not limit the scope of the invention claimed. Although multiple features are described in the embodiments, not all of these multiple features are necessarily essential to the invention, and multiple features may be combined arbitrarily. Furthermore, in the accompanying drawings, the same reference numerals are used to designate the same or similar components, and redundant explanations will be omitted.

[0011] (Configuration of Wireless Communication System) FIG. 1 shows an example of the configuration of a wireless communication system according to this embodiment. In one example, the wireless communication system is configured to perform wireless communication using a wireless local area network (wireless LAN) conforming to the IEEE 802.11bn standard. IEEE stands for Institute of Electrical and Electronics Engineers. The following description will be given assuming a wireless LAN conforming to the IEEE 802.11bn standard, but this is not limiting. The method described below may also be applied to communication conforming to other wireless communication standards. For example, the method described below may be applied to communication conforming to one of the successor standards to the IEEE 802.11be standard. The following method may also be applied to communication standards other than wireless LAN. In the example of FIG. 1 , two access points (AP 101 and AP 102) and two stations (STA 111 and STA 112) are shown as communication devices performing wireless communication. Hereinafter, the access points are referred to as APs, and the stations are referred to as STAs. The example of FIG. 1 is merely an example, and the wireless communication system is configured so that at least two APs share a transmission opportunity (TXOP) to perform communication (cooperative communication). That is, the number of APs may be three or more. The number of STAs may be one or three or more. The APs 101 and 102 and the STAs 111 and 112 are configured to be able to perform communication compliant with the IEEE 802.11 series standards other than the IEEE 802.11bn standard. Hereinafter, the roles of the APs 101 and 102 will be described separately, but the roles of the APs 101 and 102 may be interchangeable. The AP 101 and the AP 102 can function both as the AP 101 and as the AP 102, which will be described later.

[0012] AP 101 and AP 102 each form and manage a network called a Basic Service Set (BSS). STA 111 and STA 112 can communicate with the AP forming the BSS by joining a BSS managed by either AP. In one example, STA 111 may join the BSS managed by AP 101, and STA 112 may join the BSS managed by AP 102. STA 111 and STA 112 may also join both the BSS managed by AP 101 and the BSS managed by AP 102.

[0013] The APs 101 to 102 and the STAs 111 to 112 may also be configured to support wireless communication based on other communication standards, such as Bluetooth (registered trademark), NFC, or Bluetooth (registered trademark) Low Energy (LE). Here, NFC stands for Near Field Communication. The APs 101 to 102 may also be configured to support wired communication using an Ethernet (registered trademark) cable or wired communication using optical fiber. The APs 101 to 102 may be, for example, but are not limited to, wireless LAN routers or personal computers (PCs). The STAs 111 to 112 may also be, for example, but are not limited to, cameras, tablets, smartphones, PCs, mobile phones, video cameras, wearable devices such as smart glasses, etc. The APs 101 and 102 and the STAs 111 and 112 may be information processing devices such as wireless chips that support at least one of transmission and reception of wireless frames conforming to the IEEE 802.11 series standard.

[0014] In the wireless communication system according to this embodiment, communication involving cooperative operation between APs is performed in order to improve the utilization efficiency of the wireless medium, reduce transmission delays, extend communication distances, etc. In other words, AP 101 and AP 102 cooperate to communicate with STA 111 and STA 112. Hereinafter, this communication will be referred to as AP cooperative communication.

[0015] AP cooperative communication includes, for example, coordinated spatial reuse (CSR). In CSR, multiple APs cooperate to perform communication using the spatial reuse function in the IEEE 802.11 series standards after the IEEE 802.11ax standard. Note that in CSR, multiple APs can cooperate to communicate using the spatial reuse function, for example, only for a predetermined period of time. AP cooperative communication also includes coordinated orthogonal frequency multiple access (OFDMA) / time division multiple access (TDMA). In coordinated OFDMA / TDMA, for example, multiple APs share multiple resource units (RUs) and transmission opportunities (TXOPs) included in one OFDM symbol. AP cooperative communication also includes coordinated beamforming (CBF). In CBF, multiple APs cooperate to spatially multiplex, for example, communications between one AP and a STA and communications between another AP and a STA. AP cooperative communication also includes joint transmission / reception (JT / JR) OFDMA / TDMA. In JT / JR OFDMA / TDMA, multiple APs cooperate to transmit and receive the same signal to and from one STA, for example, while performing multiple access using OFDMA / TDMA. These cooperative operations are performed for a predetermined period determined by one of the APs.

[0016] In AP cooperative communication, an AP operates in either the role of a sharing AP that leads the cooperative communication, or a shared AP controlled by the sharing AP. The period during which the above-described cooperative operation is performed can be determined, for example, by the sharing AP. Here, in order to perform AP cooperative communication, the sharing AP needs to notify the shared AP of information about the period. Meanwhile, each AP has its own timer, and these timers operate independently. Therefore, there is no common time between the sharing AP and the shared AP. Therefore, time information or the like cannot be used by the sharing AP to notify the shared AP of the period during which cooperative operation will be performed. For this reason, in this embodiment, information such as the time difference (offset) from the transmission timing of a beacon frame periodically transmitted by the AP to the timing at which cooperative communication starts, and information about the period during which cooperative communication will be performed, are shared. For example, the sharing AP notifies the shared AP of information indicating the time period after the sharing AP transmits a beacon frame at which cooperative communication will be performed and the length of the period during which the cooperative communication will be performed.The shared AP can then determine the period during which cooperative communication will be performed based on the information and the time period when the shared AP receives the beacon frame from the sharing AP.

[0017] The following describes an example of the configuration of an AP that performs such processing and the flow of processing executed by the AP.

[0018] (Device Configuration) An example configuration of a communication device (AP101 to AP102) functioning as an AP according to this embodiment will be described using Fig. 2. Fig. 2 shows an example hardware configuration of an AP. As shown in Fig. 2, the AP includes, as its hardware configuration, a storage unit 201, a control unit 202, a function unit 203, an input unit 204, an output unit 205, a communication unit 206, and an antenna 207, for example.

[0019] The storage unit 201 includes one or more memories, such as a ROM or a RAM, and stores various information, such as computer programs for performing various operations described below and communication parameters for wireless communication. Note that ROM stands for Read Only Memory, and RAM stands for Random Access Memory. The storage unit 201 may include storage media such as a flexible disk, a hard disk, an optical disk, a magneto-optical disk, a CD-ROM, a CD-R, a magnetic tape, a non-volatile memory card, or a DVD, in addition to or instead of memories such as a ROM or a RAM. The storage unit 201 may also include a solid state drive (SSD). The storage unit 201 may also include multiple memories.

[0020] The control unit 202 is configured with one or more processors, such as a CPU or MPU, and controls the entire AP by executing a computer program stored in the storage unit 201, for example. The CPU stands for Central Processing Unit, and the MPU stands for Micro Processing Unit. The control unit 202 may be configured to perform processes such as generating data and signals to be transmitted in communications with other communication devices (other APs or STAs) in addition to overall control of the AP. The control unit 202 may be configured to execute processes such as overall control of the AP in cooperation with a computer program stored in the storage unit 201 and an OS (Operating System). The control unit 202 may also include multiple processors, such as a multi-core processor, and execute processes such as overall control of the AP using the multiple processors. The control unit 202 may also be configured with an ASIC (Application Specific Integrated Circuit), a DSP (Digital Signal Processor), an FPGA (Field Programmable Gate Array), or the like.

[0021] The control unit 202 also controls the functional unit 203 to perform predetermined processes such as capturing images, printing, and projection. The functional unit 203 is hardware that enables the AP to perform predetermined processes. For example, if the AP is a camera such as a digital still camera or a smartphone equipped with a camera, the functional unit 203 is an imaging unit that performs imaging processing of surrounding images. For example, if the AP 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 stored in the storage unit 201 or acquired from an external device via wireless communication or the like. For example, if the AP is a projector or smart glasses, the functional unit 203 is a projection unit that performs projection processing of image data or video data stored in the storage unit 201 or acquired from an external device via wireless communication or the like. In the case of smart glasses, the projection surface is the end user's retina, for example. The data processed by the functional unit 203 may be data stored in the storage unit 201 or data communicated with another AP or STA via the communication unit 206, which will be described later. Furthermore, the AP can also provide a network storage function such as NAS (Network Attached Storage). This function is provided to other communication devices as a web service such as a network storage service. For example, another communication device such as an STA connects to a network storage service provided by the APs 101 and 102 using a protocol such as SMB, FTP, or WebDAV. The other communication device such as an STA can then upload files to the storage service or download files from the storage. Data communication for this upload or download can be performed using a wireless communication function that complies with, for example, the IEEE 802.11 series standard.

[0022] 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, for example, at least one of a display on a screen, an audio output from a speaker, and a vibration output. Note that both the input unit 204 and the output unit 205 may be implemented by a single module, such as a touch panel. Furthermore, the input unit 204 and the output unit 205 may each be built into the AP, or may be configured as an external device connected to the AP.

[0023] The communication unit 206 controls wireless communication compliant with the IEEE 802.11 series standards and Internet Protocol (IP) communication. The communication unit 206 cooperates with, for example, the antenna 207 to transmit and receive wireless frames compliant with the IEEE 802.11 standard. The antenna 207 is an antenna capable of transmitting and receiving signals in at least one frequency band, such as the sub-GHz band, 2.4 GHz band, 5 GHz band, 6 GHz band, 7 GHz band, and 60 GHz band. While one antenna 207 is illustrated in this embodiment, multiple antennas may be provided. In one example, a different antenna may be provided for each frequency band. Furthermore, if the AP has multiple antennas, it may have multiple communication units 206 corresponding to the multiple antennas, respectively. Note that if the AP supports standards such as the NFC standard or Bluetooth (registered trademark), a communication unit 206 configured to control wireless communication compliant with these communication standards may be provided.

[0024] FIG. 3 shows an example of the functional configuration of an AP. The AP has a communication control unit 301, a sharing AP function unit 302, and a shared AP function unit 303 as its functional configuration. These functions can be realized, for example, by the control unit 202 executing a program stored in the storage unit 201, or by a processing function unit in the communication unit 206. Note that FIG. 3 is a diagram illustrating the main functions of this embodiment, and other functions are omitted. Therefore, the AP can naturally have, for example, a control function for establishing a connection with an STA as a normal AP and for communication, as well as functions generally possessed by a communication device. Furthermore, multiple functional blocks in FIG. 3 may be integrated into a single functional block, or a single functional block may be divided into multiple functional blocks.

[0025] The communication control unit 301 executes communication control for wireless communication compliant with the IEEE 802.11 series standards, such as the IEEE 802.11bn standard. For example, the communication control unit 301 executes control for generating and transmitting control frames such as beacon frames and wireless frames such as data frames to be transmitted to communication partner devices, and for receiving and decoding wireless frames transmitted from other APs. The communication control unit 301 controls connection and communication with STAs, as well as AP-to-AP communication with other APs. The sharing AP function unit 302 executes communication control as a sharing AP. For example, the sharing AP function unit 302 determines a period during which AP cooperative communication is performed. The sharing AP function unit 302 then generates information expressing the specified period based on the transmission timing of the beacon frame, and transmits the information to other APs operating as shared APs in AP cooperative communication via the communication control unit 301. The Sharing AP functional unit 302 also performs various controls related to AP cooperative communication, such as transmitting a trigger frame for data transmission through cooperative communication to other APs operating as shared APs. The Shared AP functional unit 303 performs communication control as a shared AP. For example, the Shared AP functional unit 303 acquires information indicating a period during which cooperative communication is to be performed based on the transmission timing of a beacon frame from another AP functioning as a sharing AP in AP cooperative communication, and identifies that period. Then, during that period, the Shared AP functional unit 303 communicates in cooperation with another AP functioning as a sharing AP. For example, the Shared AP functional unit 303 may receive a trigger frame transmitted from the sharing AP and transmit a data frame to the STA using the information in the trigger frame.

[0026] The STA has the same hardware and functional configuration as a normal STA, the details of which will not be described here.

[0027] (Communication Flow) The flow of AP cooperative communication according to this embodiment will be described. Fig. 4 shows an example of the flow of communication processing when AP 101 and AP 102 in Fig. 1 cooperate to transmit data frames to STA 111 and STA 112. When three or more APs communicate cooperatively, one AP functions as a sharing AP, and the other (two or more) APs function as shared APs. Then, similar to the processing described below, the shared AP identifies a period for cooperative communication based on information from the sharing AP, and performs AP cooperative communication within that period.

[0028] The AP 101 and the AP 102 each start transmitting a beacon frame in response to the wireless LAN wireless communication function being enabled. The AP 101 and the AP 102 each periodically transmit a beacon frame at a timing called a Target Beacon Transmission Time (TBTT). Note that the beacon frame transmission period (Beacon Interval (BI)) for each AP can be set individually. After transmitting a beacon frame 401, the AP 101 transmits the next beacon frame 402 after the BI has elapsed. Similarly, a beacon frame 403 is transmitted after the BI has elapsed since the transmission of the beacon frame 402, and a beacon frame 404 is transmitted after the BI has elapsed since the transmission of the beacon frame 403. In addition, in one example, the AP 102 transmits a beacon frame at a timing (TBTT) and BI different from those of the AP 101. The AP 102 transmits a beacon frame 406 after the BI has elapsed since the transmission of the beacon frame 405, and transmits a beacon frame 407 after the BI has elapsed since the transmission of the beacon frame 406.

[0029] Here, if the AP 101 decides to perform AP cooperative communication with the AP 102, it initiates a cooperative operation request phase 411. An example of the processing flow of the cooperative operation request phase 411 will be described with reference to FIG. 5 . In the cooperative operation request phase 411, the AP 101 transmits a cooperative operation request frame 501 to the AP 102. The cooperative operation request frame 501 includes information indicating a request to the AP 102 to perform cooperative operation with the AP 101, the type of cooperative operation, and a period during which the cooperative operation is scheduled to be performed. FIG. 6 shows an example of the configuration of an information element indicating the period during which the cooperative operation is scheduled to be performed. As shown in FIG. 6 , this information element can be written in the format of an Information Element (IE) defined in the IEEE 802.11 standard. Note that this is just an example, and an information element for specifying the period during which the cooperative operation is scheduled to be performed may be written in another format. In the example of FIG. 6 , this information element includes an Element ID 601 and a Length 602. This information element also includes a Multi-AP Count 603 , a Multi-AP Period 604 , a Multi-AP Duration 605 , and a Multi-AP Offset 606 .

[0030] Element ID 601 is a field indicating the identifier of this IE. Length 602 is a field indicating the length of this IE. Multi-AP Count 603 is a field indicating the number of TBTTs of AP 101 that exist from the transmission of the collaboration request frame 501 until the start of the period in which collaboration is scheduled to be performed. In other words, Multi-AP Count 603 is information indicating the number of times a beacon frame is transmitted from the transmission of the collaboration request frame 501 until the start of the period in which the first collaboration is performed. In the example of FIG. 4 , beacon frames 402 and 403 are transmitted between the collaboration request phase 411 in which the collaboration request frame 501 is transmitted and the first collaboration phase 441 in which collaboration is actually performed. In other words, the number of beacon frame transmissions between the transmission of the cooperative operation request frame 501 and the period in which cooperative operation is performed (cooperative operation phase 441) is two (there are two TBTTs). Therefore, in this case, the value "2" is stored in the Multi-AP Count 603. Note that this is just an example, and for example, the value "n-1" may indicate that the number of beacon frame transmissions between the transmission of the cooperative operation request frame and the period in which cooperative operation is performed is "n times." This is because if no beacon frame is transmitted after the transmission of the cooperative operation request frame, it is not possible to specify the period of cooperative operation based on the timing of the beacon frame, and therefore there is no need to represent "0 times." The Multi-AP Period 604 is a field that indicates whether the period in which cooperative operation is scheduled to be performed is repeated periodically and the number of periods to be set. For example, if the value "0" is stored in this field, it indicates that the period during which cooperative operation is scheduled to be performed is set only once after the cooperative operation request frame 501 is transmitted. For example, in the example of Figure 4, if only the cooperative operation phase 441 is set and the cooperative operation phase 442 is not set, the value "0" is stored in the Multi-AP Period 604. If a non-zero value is stored in this field, the value specifies the number of times the period during which cooperative operation is scheduled to be performed is set.The period during which the cooperative operation is scheduled is set in a time interval (BI) between two Beacon frames. Therefore, the number of times the period during which the cooperative operation is scheduled is set can be specified by the number of BIs from the transmission of the cooperative operation request frame 501 until the completion of the cooperative operation. In the example of FIG. 4 , two periods, the cooperative operation phase 441 and the cooperative operation phase 442, are set in two BIs, so "1" is stored in the Multi-AP Period 604. Furthermore, storing a non-zero value in this field indicates that the period during which the cooperative operation is performed occurs periodically, and the non-zero value may indicate the period. Here, the period may be expressed in units of the length of the BI. For example, if a period during which the cooperative operation is performed exists in all BIs, the period is one BI long, so the value "1" may be stored. Furthermore, if a period during which the cooperative operation is performed exists every other BI, the period is two BI long, so the value "2" may be stored. Furthermore, when a non-zero value is stored in this field, the value may indicate both the number of times the period during which cooperative operation is scheduled to be performed and its period. In this case, this field may be composed of two or more subfields, including a subfield indicating the number of times the period during which cooperative operation is scheduled to be performed and a subfield indicating its period. Multi-AP Duration 605 is a field indicating the length of the period during which cooperative operation is scheduled to be performed. Multi-AP Offset 606 is a field indicating the time difference (offset) between the timing at which the period during which cooperative operation is scheduled to be performed starts and the TBTT of the AP 101 immediately before that period. That is, in the example of FIG. 4 , the time difference between the timing at which the period during which cooperative operation is scheduled to be performed starts (TBTT) and the transmission timing of the beacon frame 403 immediately before the cooperative operation phase 441 is stored in Multi-AP Offset 606. Similarly, the cooperative operation phase 442 starts at the timing when the offset stored in the Multi-AP Offset 606 has elapsed from the Beacon frame 404. In other words, if a non-zero value is stored in the Multi-AP Period 604, the period during which cooperative operation is performed can be set to the same period as the transmission period of the Beacon frame or a period that is an integral multiple of that period.This is just an example, and the cycle in which multiple periods are set may be set separately from the cycle of the beacon frame.

[0031] Returning to FIG. 5 , upon receiving the collaboration request frame 501, the AP 102 transmits a collaboration response frame 502 to the AP 101 in response to the frame. This collaboration response frame 502 includes information indicating whether or not to accept the collaboration indicated in the collaboration request frame 501. Similarly to the collaboration request frame 501, the collaboration response frame 502 may also include information proposing the type and period of collaboration. In this case, the collaboration response frame 502 may include information explicitly indicating that the type and period of collaboration are being proposed. The collaboration response frame 502 may also include information rejecting the request made by the collaboration request frame 501. In other words, the type and period of collaboration need not be accepted or proposed. The collaboration response frame 502 indicating acceptance of collaboration may be a frame indicating the same type and period of collaboration as those indicated in the collaboration request frame 501. In this case, the collaboration response frame 502 containing information different from the information contained in the collaboration request frame 501 can be treated as a frame proposing a type and period of collaboration based on that information. That is, the collaboration response frame 502 does not need to contain explicit information indicating a proposal for a type and period of collaboration. In this case, the collaboration response frame 502 may indicate that the request for collaboration is rejected by including predetermined values ​​for the type and period of collaboration.

[0032] When the AP 101 receives a collaboration response frame 502 that does not indicate that the collaboration is rejected, the AP 101 transmits a collaboration confirmation frame 503 to the AP 102. The collaboration confirmation frame 503 may include, for example, information indicating that the collaboration response frame 502 was successfully received and that the collaboration will be performed. Furthermore, if the collaboration response frame 502 includes a proposal for collaboration, the collaboration confirmation frame 503 may include information indicating whether the proposal is accepted. Here, a collaboration confirmation frame 503 including information indicating that the proposal is not accepted may implicitly indicate that collaboration will not be performed. Furthermore, if the proposal is accepted, the collaboration confirmation frame 503 may include information explicitly indicating acceptance of the proposal, or alternatively or in addition to this, the collaboration confirmation frame 503 may include the same information as the type and duration of the collaboration proposed in the collaboration response frame 502. In addition, if a cooperative operation response frame 502 indicating acceptance of the cooperative operation has been received, information indicating acceptance of the cooperative operation may be included in the cooperative operation confirmation frame 503 to indicate that cooperative communication will be performed based on the contents of the cooperative operation request frame 501.

[0033] When AP 102 receives the cooperative operation confirmation frame 503 indicating acceptance of the cooperative operation, AP 101 and AP 102 agree to cooperate. Note that AP 101 may acknowledge that AP 102 has received the cooperative operation confirmation frame 503 by receiving an acknowledgment (ACK) frame (not shown) transmitted by AP 102.

[0034] 5, in a cooperation request phase 411, AP 101 requests cooperation from AP 102 and negotiates with AP 102. This cooperation request phase 411 ends when AP 101 and AP 102 agree to cooperation through the transmission and reception of the frames described above, or when either AP refuses cooperation without agreeing to cooperation. In this embodiment, the AP (AP 101) that initiates the cooperation request phase 411 is called a sharing AP, and the AP (AP 102) that responds to the request from the sharing AP is called a shared AP.

[0035] Returning to FIG. 4 , when AP 101 and AP 102 agree to cooperative operation, they transition to a sounding phase 421. In the sounding phase 421, a sounding procedure is executed between the communication devices as required depending on the type of cooperative operation. As a result, a transfer function related to radio wave propagation between the communication devices as required for the cooperative operation is identified. For example, AP 101 and AP 102 may identify a transfer function related to radio wave propagation between STA 111 and STA 112. Note that sounding phase 421 may be executed only when a sounding procedure is required depending on the type of cooperative operation.

[0036] When the sounding phase 421 ends, a transition is made to an inter-AP data sharing phase 431. In the inter-AP data sharing phase 431, when a cooperative operation that requires data sharing is performed between AP 101 and AP 102, data sharing is performed between the APs. For example, AP 101 and AP 102 share data when performing joint transmission / reception (JT / JR) OFDMA / TDMA. Note that the inter-AP data sharing phase 431 can be executed only when data sharing is required, depending on the type of cooperative operation.

[0037] When the inter-AP data sharing phase 431 ends, a collaboration phase 441 starts for the period agreed upon in the collaboration request phase 411. The collaboration phase may be repeated periodically. Fig. 4 shows an example in which a collaboration phase 442 is set as the second collaboration phase following the collaboration phase 441. In the collaboration phase, collaboration is performed according to the details agreed upon in the collaboration request phase 411.

[0038] Here, an example of the flow of processing executed in the collaboration phase 441 and the collaboration phase 442 will be described with reference to FIG. 7 . When the collaboration phase starts, AP 101 transmits a trigger frame 701 to AP 102. Thereafter, AP 101 transmits a data frame 702 to at least one of STA 111 and STA 112. When AP 102 receives the trigger frame 701 from AP 101, it transmits a data frame 703 to at least one of STA 111 and STA 112. The transmission of the data frame 702 and the data frame 703 is performed using the type of collaboration agreed upon in the collaboration request phase 411. When STA 111 receives the data frame 702, it transmits an ACK frame 704 (a Block ACK frame in FIG. 5 ) to AP 101. Furthermore, when STA 111 receives the data frame 703, it transmits an ACK frame 705 to AP 102. Similarly, when the STA 112 receives at least one of the data frame 702 and the data frame 703, it transmits an ACK frame 705 (Block ACK frame in FIG. 5) to the AP that transmitted the data frame.

[0039] 5 and 7 do not illustrate ACK frames indicating that a frame has been received, except for ACK frame 704 and ACK frame 705. However, when any communication device receives any frame, it may subsequently transmit an ACK frame to the communication device that sent that frame.

[0040] (Operation of AP) Fig. 8 is a diagram showing an example of the flow of processing executed by communication devices (AP 101, AP 102) functioning as APs. The processing in Fig. 8 is started when the wireless LAN function of the communication device is started (enabled), for example, when the communication device is powered on or when a user inputs information to the communication device via the input unit 204. Note that the order of the processing steps described below may be changed, or multiple processing steps may be executed in parallel. Furthermore, some processing steps may be omitted or replaced with different processing steps having the same purpose.

[0041] The AP starts transmitting beacon frames (S801). Here, the transmission period of the beacon frames is determined based on information input by the user to the input unit 204, information previously stored in the storage unit 201, and the like. The AP then determines whether any wireless frames have been received (S802). If the AP has received any wireless frames (YES in S802), the process proceeds to S803; if the AP has not received any wireless frames (NO in S802), the process proceeds to S806.

[0042] In S803, the AP determines whether the received wireless frame is a collaboration request frame. If the AP receives a collaboration request frame (YES in S803), it executes shared AP processing, which will be described later with reference to FIG. 10 (S804). On the other hand, if the AP receives a wireless frame that is not a collaboration request frame (NO in S803), it executes processing according to the received wireless frame (S805). After executing the processing in S804 or S805, the AP proceeds to S806.

[0043] In S806, the AP determines whether there is a wireless frame scheduled to be transmitted. For example, the AP checks whether there is a wireless frame scheduled to be transmitted in any of the storage unit 201, control unit 202, function unit 203, input unit 204, and communication unit 206. If the AP determines that there is a wireless frame scheduled to be transmitted (YES in S806), the process proceeds to S807. If the AP determines that there is no such wireless frame (NO in S806), the process proceeds to S810. In S807, the AP determines whether to transmit the wireless frame using cooperative operation with other APs. If the AP determines that the wireless frame will be transmitted using cooperative operation (YES in S807), the AP executes a sharing AP process (S808), which will be described later with reference to FIG. 9 . On the other hand, if the AP determines that the wireless frame will be transmitted without cooperative operation (NO in S807), the AP transmits the wireless frame independently without coordinating with other APs (S809). After executing the process of S808 or S809, the AP proceeds to S810. In S807, the AP may determine whether to use AP cooperative communication to transmit the wireless frame based on, for example, the congestion state of the wireless medium, the attributes of the data to be transmitted, the distance to the STA to which the frame is to be transmitted, etc. For example, the AP may determine to transmit the wireless frame using AP cooperative communication if performing AP cooperative communication would be advantageous in terms of wireless medium utilization efficiency, transmission delay, communication distance, etc.

[0044] In S810, the AP determines whether the wireless LAN function has been stopped (disabled), for example, by a user inputting information to the input unit 204. If the AP determines that the wireless LAN function has been disabled (YES in S810), it stops transmitting Beacon frames (S811) and ends the process. On the other hand, if the AP determines that the wireless LAN function has not been disabled (NO in S810), the process returns to S802.

[0045] Next, an example of the flow of the sharing AP process executed in S808 will be described with reference to FIG.

[0046] When an AP starts operating as a sharing AP, it transmits a collaboration request frame to another AP that is to function as a shared AP (S901). This collaboration request frame includes information such as the type of collaboration and the planned period for the collaboration. The AP determines whether it has received a collaboration response frame from the shared AP that includes information indicating acceptance of the type and period of collaboration specified in the collaboration request frame, or that includes a proposal for the type and period of collaboration (S902). If the AP does not receive a collaboration response frame or receives a collaboration response frame that does not include an acceptance or proposal for the type and period of collaboration (NO in S902), the AP terminates the process without performing collaboration. Note that if the AP terminates the process without performing collaboration, it may proceed to S809 in FIG. 8 and transmit a wireless frame independently. Alternatively, if the AP does not receive a collaboration response frame that includes an acceptance or proposal for the type and period of collaboration, it may return to S901 and repeatedly transmit a collaboration request frame.

[0047] When the AP receives a collaboration response frame that includes an acceptance or proposal of the type and duration of collaboration (YES in S902), the AP determines whether to accept the collaboration with the content indicated in the collaboration response frame (S903). For example, when the AP receives a collaboration response frame indicating that the type and duration of collaboration proposed in the collaboration request frame are accepted, the AP determines to accept the collaboration with the content. Furthermore, when the AP receives a collaboration response frame that includes a proposal of the type and duration of collaboration, the AP determines whether to accept the proposal. The AP may determine whether to accept the proposal based on, for example, the congestion status of the wireless medium, the attributes of the data to be transmitted, the distance to the STA to which the frame is to be transmitted, and the like. For example, the AP may determine to accept the proposal if it determines that accepting the proposal will result in advantageous effects such as improved wireless medium utilization efficiency, reduced transmission delay, and shorter communication distance. In addition, for example, if the content of the proposal allows the AP to meet the requirements required when transmitting data (e.g., required wireless quality, required delay, etc.), the AP may decide to accept the proposal even if communication is possible under more favorable conditions than the proposal.

[0048] If the AP determines not to accept the contents of the collaboration response frame (NO in S903), it transmits a collaboration confirmation frame indicating that it does not accept the contents indicated in the collaboration response frame to the shared AP (S910), and terminates the process without performing collaboration. If the AP terminates the process without performing collaboration, it may proceed to S809 in FIG. 8 and transmit a wireless frame independently. If the AP does not receive a collaboration response frame that includes an acceptance or proposal for the type or period of collaboration, the AP may return to S901 and repeatedly transmit a collaboration request frame.

[0049] If the AP determines that it accepts the contents of the collaboration response frame (YES in S903), it transmits a collaboration confirmation frame indicating that it accepts the contents indicated in the collaboration response frame to the shared AP (S904). Then, if it determines that this is necessary depending on the type of collaborative communication, the AP executes the sounding phase process and the inter-AP data sharing phase process (S905). The AP then waits for the collaboration period to begin (YES in S906) and, after the period begins, transmits a trigger frame to the shared AP to cause it to transmit a data frame (S907). The AP then transmits the data frame in collaboration with the shared AP (S908). While the collaboration period continues (NO in S909), the AP repeatedly executes the processes of S907 and S908 to transmit the data to be transmitted in collaboration with the shared AP. When the collaboration period ends (YES in S909), the AP terminates the process of FIG. 9.

[0050] Next, an example of the flow of the shared AP processing executed in S804 will be described with reference to FIG.

[0051] First, the AP operating as a shared AP checks the information, such as the type and duration of the cooperative operation, contained in the cooperative operation request frame determined to have been received in S802 and S803 of FIG. 8 . The AP then determines whether to accept the type and duration of the cooperative operation or to propose a different type and duration of the cooperative operation (S1001). If the AP does not accept the type and duration of the cooperative operation or does not propose a different type and duration of the cooperative operation (NO in S1001), it transmits a cooperative operation response frame rejecting the cooperative operation (S1009) and terminates processing. On the other hand, if the AP accepts or proposes the type and duration of the cooperative operation (YES in S1001), it proceeds to S1002. In S1002, the AP transmits a cooperative operation response frame containing information indicating that it accepts the type and duration of the cooperative operation, etc., indicated in the cooperative operation request frame, or a proposal for a different content from that indicated in the cooperative operation request frame. The AP may decide whether to accept the type and duration of cooperative operation indicated in the cooperative operation request frame or propose alternative options based on factors such as the congestion status of the wireless medium, the attributes of the data to be transmitted, and the distance to the STA to which the frame is to be transmitted. For example, if the AP determines that sufficiently good communication can be achieved with the options indicated in the cooperative operation request frame, it may decide to accept cooperative communication with those options. Furthermore, if the AP can propose an alternative type and duration of cooperative operation that enables communication under better conditions than the options indicated in the cooperative operation request frame, it may decide to propose that option to the sharing AP. Furthermore, if the AP determines that communication cannot be achieved with sufficient quality with the options indicated in the cooperative operation request frame and is unable to propose an alternative type and duration of cooperative operation, it may decide to reject the request for cooperative operation.

[0052] After transmitting a collaborative operation response frame containing information indicating acceptance of the collaborative operation type, period, and other details contained in the collaborative operation request frame, or a proposal for other details, the AP waits for a collaborative operation confirmation frame from the sharing AP (S1003). If the AP does not receive a collaborative operation confirmation frame indicating acceptance of the collaborative operation based on the contents of the collaborative operation response frame from the sharing AP (NO in S1003), it terminates the process. On the other hand, if the AP receives a collaborative operation confirmation frame indicating acceptance of the collaborative operation based on the contents of the collaborative operation response frame from the sharing AP (YES in S1003), it proceeds to S1004. In S1004, the AP executes the sounding phase process and the inter-AP data sharing phase process, for example, if it is determined that these are necessary depending on the type of collaborative communication. The AP then waits for the collaborative operation period to begin (YES in S1005), and after the period begins, it waits for a trigger frame to be received from the sharing AP (S1006). When the AP receives the trigger frame (YES in S1006), it transmits a data frame in cooperation with the sharing AP (S1007). While the cooperative operation period continues (NO in S1008), the AP transmits the data to be transmitted in cooperation with the sharing AP in response to the trigger frame from the sharing AP. When the cooperative operation period ends (YES in S1008), the AP ends the processing of FIG. 10.

[0053] (Operation of STA) Fig. 11 is a diagram showing an example of the flow of processing executed by a communication device (STA111, STA112) functioning as an STA. The processing in Fig. 11 is started, for example, when the communication device functioning as an STA is powered on or the user inputs information to the communication device via the input unit 204, and the wireless LAN function of the communication device is started (enabled) and connected to an AP. Note that the order of the processing steps described below may be changed, or multiple processing steps may be executed in parallel. Furthermore, some processing steps may be omitted or replaced with different processing steps having the same purpose.

[0054] When the STA receives a frame (YES in S1101), it executes processing according to the frame (S1102). The STA also determines whether a frame to be transmitted exists (S1103). The STA determines whether a frame scheduled for transmission exists in, for example, the storage unit 201, the control unit 202, the function unit 203, the input unit 204, or the communication unit 206. If a frame to be transmitted exists, the STA transmits the frame (S1104). The STA then determines whether the wireless LAN function has been stopped (disabled), for example, by a user inputting information into the input unit 204 (S1105). When the STA determines that the wireless LAN function has been disabled (YES in S1105), it terminates the processing. On the other hand, as long as the wireless LAN function is not disabled (NO in S1105), the STA returns the processing to S1101.

[0055] According to this embodiment, in an environment in which multiple APs cooperate, one of the APs generates information about a period of cooperative operation based on the timing of transmitting a beacon frame and transmits it to the other APs. This allows the APs operating cooperatively to receive beacon frames from each other even if they do not share common time information with the other APs. Therefore, the period during which cooperative operation is scheduled can be determined based on the frame. The information transmitted from one AP to the other APs may include, for example, the number of TBTTs that exist before the period begins, the time difference (offset) from the transmission timing (TBTT) of the beacon frame, and the length of the period. This information may also include information on whether the period repeats periodically, the number of beacon intervals (BIs) that include the period, the period, and so on. This allows the period during which cooperative operation is scheduled to occur to be flexibly expressed, enabling the period during which cooperative operation is scheduled to occur to be flexibly set. In the above example, only one period during which cooperative operation is scheduled to be performed is set for one BI. However, this is not limiting. For example, multiple periods during which cooperative operation is scheduled may be set for one BI. In this case, an offset from the previous TBTT and a time length may be specified for each of the multiple periods. In this case, for example, the cooperative operation request frame may include multiple IEs, such as those shown in FIG. 6, or information regarding multiple periods may be included in a single IE. In the above example, a period during which cooperative operation is scheduled to be performed is set for each of multiple consecutive BIs. However, for example, a period during which cooperative operation is scheduled may be set for every predetermined number of BIs. In this case, for example, the number of TBTTs that will occur between two periods during which cooperative operation is scheduled may be notified. For example, if cooperative operation is scheduled for every other BI, two TBTTs will occur between the two periods during which cooperative operation is scheduled, and information indicating "two" may be notified.These are merely examples, and information specifying the period during which cooperative operation is scheduled to be performed may be expressed in other formats based on the timing of the Beacon frame.

[0056] In the above example, the process of determining the type and period of cooperative communication between multiple APs performing AP cooperative communication through negotiation using a cooperative operation request frame and a cooperative operation response frame has been described. However, this is not limiting. For example, the sharing AP may notify the shared AP of information about the determined period, and the shared AP may always comply with this determination. In the above example, the AP that sends the cooperative operation request frame is described as the sharing AP. However, the roles of the sharing AP and the shared AP may be determined in advance through negotiation. Furthermore, when determining the roles, information about the period during which cooperative operation is scheduled to be performed may be shared as described above.

[0057] In the above example, the period during which the cooperative operation is performed is expressed based on the transmission timing of a beacon frame. However, this is not limited to this. For example, the start timing of the period may be specified by a time difference (offset) from the end of the cooperative operation request frame or the cooperative operation confirmation frame. In this case, information indicating the length of the period may be notified in the same manner as in the method using a beacon frame as the reference. Note that when cooperative operations are repeatedly and periodically performed, information indicating the period may be expressed using a beacon frame, and when only one cooperative operation is performed, information indicating the period may be expressed based on the transmission timing of a cooperative operation request frame or the like. In this case, for example, the cooperative operation request frame may include information indicating which frame's transmission timing is to be used as the reference.

[0058] The present invention can also be realized by supplying a program that realizes one or more of the functions of the above-described embodiments to a system or device via a network or a storage medium, and having one or more processors in the computer of the system or device read and execute the program.The present invention can also be realized by a circuit (e.g., an ASIC) that realizes one or more of the functions.

[0059] The invention is not limited to the above-described embodiments, and various changes and modifications can be made without departing from the spirit and scope of the invention. Accordingly, the following claims are appended to apprise the public of the scope of the invention.

[0060] This application claims priority based on Japanese Patent Application No. 2024-004116, filed January 15, 2024, the entire contents of which are incorporated herein by reference.

Claims

1. A communication device that functions as an access point according to the IEEE 802.11 standard, comprising: generation means for generating a predetermined frame including information indicating a period during which the communication device is scheduled to cooperate with other communication devices functioning as access points, based on the timing at which the Beacon frame is transmitted by the communication device; and communication means for transmitting the predetermined frame including the information to the other communication devices and communicating in cooperation with the other communication devices during the period.

2. The communication device according to claim 1, wherein the predetermined frame is a first frame that requests a cooperation operation with the other communication devices from the other communication devices.

3. The communication means of the communication device according to claim 2: receives from the other communication devices a second frame that responds to the first frame and includes information indicating a period proposed by the other communication devices as a period during which the communication device and the other communication devices are scheduled to perform cooperative communication based on the timing at which the Beacon frame is transmitted by the communication device; and communicates in cooperation with the other communication devices during the period when it accepts the period indicated by the information included in the second frame.

4. The communication means of the communication device according to claim 2: communicates in cooperation with the other communication devices during the period when it receives from the other communication devices a second frame that responds to the first frame and indicates acceptance of cooperative communication with the communication device during the period indicated in the first frame.

5. A communication device that functions as an access point according to the IEEE 802.11 standard, comprising: receiving means for receiving from other communication devices functioning as access points a predetermined frame including information indicating a period during which the communication device is scheduled to cooperate, based on the timing at which the Beacon frame is transmitted by the other communication devices; specifying means for specifying the period based on the information; and communication means for communicating in cooperation with the other communication devices during the period when it accepts the cooperation operation with the other communication devices during the period.

6. The communication device according to claim 5, wherein the predetermined frame is a first frame that requests a cooperative operation between the other communication device and the communication device from the other communication device.

7. The communication means is a second frame that responds to the first frame, and includes information indicating a period proposed as a period during which the communication device and the other communication device are scheduled to perform cooperative communication based on the timing at which the Beacon frame is transmitted by the other communication device. The second frame including the information is transmitted to the other communication device, and when the period indicated by the information included in the second frame is accepted by the other communication device, communication is performed in cooperation with the other communication device during the period. The communication device according to claim 6.

8. The communication means is a second frame that responds to the first frame, and when the second frame indicating acceptance of cooperative communication with the other communication device during the period indicated in the first frame is transmitted to the other communication device, communication is performed in cooperation with the other communication device during the period. The communication device according to claim 6.

9. The communication device according to any one of claims 1 to 8, wherein the information includes information indicating the number of times the Beacon frame is transmitted from when the predetermined frame is transmitted until the first period starts.

10. The communication device according to any one of claims 1 to 9, wherein the information includes information on the time difference from the Target Beacon Transmission Time (TBTT) of the Beacon frame immediately before the period starts to the timing when the period starts.

11. The communication device according to any one of claims 1 to 10, wherein the information includes information indicating the length of the period.

12. The communication device according to any one of claims 1 to 11, wherein the information includes information indicating whether the period is periodically and repeatedly set.

13. The communication device according to claim 12, further including information indicating the number of times the period is set when the period is repeatedly set.

14. The communication device according to claim 12 or 13, further including information indicating the period in which the period is set when the period is repeatedly set.

15. A communication method executed by a communication device functioning as an access point according to the IEEE 802.11 standard, comprising: generating a predetermined frame including information indicating a period during which the communication device is to cooperate with another communication device functioning as an access point, based on the timing at which a Beacon frame is transmitted by the communication device; and transmitting the predetermined frame including the information to the other communication device, thereby communicating in cooperation with the other communication device during the period.

16. A communication method executed by a communication device functioning as an access point according to the IEEE 802.11 standard, comprising: receiving, from another communication device functioning as an access point, a predetermined frame including information indicating a period during which the communication device is to cooperate with the other communication device, based on the timing at which a Beacon frame is transmitted by the other communication device; specifying the period based on the information; and communicating in cooperation with the other communication device during the period when accepting the cooperation operation with the other communication device during the period.

17. A program for causing a computer provided in a communication device functioning as an access point according to the IEEE 802.11 standard to execute the communication method according to claim 15 or 16.

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