Communication device, communication method, and program

Abstract

To provide a technique that allows multiple APs to share periods of cooperative operation and transmit data.SOLUTION: A communication device of the present invention is a communication device 101 that functions as an access point (AP) compliant with the IEEE802.11 series standards, and includes determination means (transmission period control unit 303) that determines a TWT SP (Target Wake Time Service Period) to be set as a period of cooperative operation with other communication devices 102 that function as other APs, notification means (communication control unit 304) that notifies the other communication devices 102 of information about the TWT SP, and transmission means (communication control unit 304) that transmits data in cooperation with the other communication devices 102 in the notified TWT SP.SELECTED DRAWING: Figure 1

Description

[Technical Field]

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

[0002] The Institute of Electrical and Electronics Engineers (IEEE) 802.11 series standards are known as communication standards for wireless local area networks (LANs).

[0003] The IEEE802.11 series of standards includes standards such as IEEE802.11a / b / g / n / ac / ax / be / bn.

[0004] For the IEEE802.11bn standard and its successor standards, the introduction of technology that improves communication efficiency and throughput by having multiple access points (hereinafter sometimes referred to as "APs") operate in cooperation with each other is being considered (see Patent Document 1). [Prior art documents] [Patent documents]

[0005] [Patent Document 1] JP 2024-67903 A Summary of the Invention [Problem to be solved by the invention]

[0006] When multiple APs operate in cooperation, it is necessary to share the period during which they operate in cooperation among the multiple APs so that data can be transmitted.

[0007] The present invention has been made in view of the above-mentioned problems, and has an object to provide a technique that enables a period of cooperative operation between a plurality of APs to be shared and data to be transmitted. [Means for solving the problem]

[0008] A communication device according to one aspect of the present invention comprises: A communication device that functions as an access point (AP) conforming to the IEEE 802.11 series standard, A determination means for determining a TWT SP (Target Wake Time Service Period) to be set as a period for cooperating with other communication devices functioning as other APs; a notification means for notifying the other communication device of information regarding the TWT SP; and a transmitting means for transmitting data in cooperation with the other communication device using the notified TWT SP.

[0009] According to the present invention, a technique is provided that enables a period of cooperative operation between a plurality of APs to be shared and data to be transmitted. [Brief explanation of the drawings]

[0010] [Figure 1] 1 is a diagram illustrating a configuration of a wireless communication system using a communication device according to a first embodiment. [Figure 2] 1 is a diagram illustrating a hardware configuration of a communication device according to a first embodiment. [Figure 3] 2 is a block diagram showing the functional configuration of a communication device functioning as an AP according to the first embodiment. FIG. [Figure 4] FIG. 2 is a diagram showing a flow of AP cooperative communication according to the first embodiment. [Figure 5] FIG. 4 is a diagram showing a processing flow in a collaborative operation phase according to the first embodiment. [Figure 6] 5 is a flowchart showing the flow of processing executed by a communication device functioning as an AP according to the first embodiment. [Figure 7] 3 is a diagram showing an example of an Extended TWT element added to a Beacon frame according to the first embodiment. FIG. DETAILED DESCRIPTION OF THE INVENTION

[0011] DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, a mode for carrying out the present invention (hereinafter referred to as an "embodiment") will be described in detail with reference to the accompanying drawings. However, the following embodiments do not limit the present invention in terms of the scope of the claims, and although the embodiments describe multiple features, not all of these multiple features are necessarily essential to the invention, and multiple features may be combined in any manner. It should be noted that the same elements are denoted by the same numbers or symbols throughout the description of the embodiments, and duplicate descriptions may be omitted.

[0012] <<First Embodiment>> [Wireless communication system configuration] FIG. 1 is a diagram showing the configuration of a wireless communication system using a communication device according to the first embodiment. The wireless communication system shown in FIG. 1 is configured to perform wireless communication via a wireless local area network (wireless LAN) conforming to the IEEE802.11bn standard, for example. IEEE stands for Institute of Electrical and Electronics Engineers.

[0013] The following description is based on the assumption that the wireless LAN complies with the IEEE802.11bn standard, but the present invention is not limited to this and the method described below may be applied to communications that comply with other wireless communication standards.

[0014] For example, the method described below may be applied to communications conforming to one of the successor standards to the IEEE802.11bn standard, as long as the method can be applied.

[0015] As shown in FIG. 1, the wireless communication system of this embodiment includes two communication devices (hereinafter also referred to as AP101 and AP102) that function as access points (hereinafter also referred to as APs) as communication devices that perform wireless communication.

[0016] AP 101 has a communication area 101A, and AP 102 has a communication area 102A.

[0017] In the first embodiment, the description will be given assuming that the AP 101 is a communication device that functions as a Sharing AP, and the AP 102 is a communication device that functions as a Shared AP. Here, the AP 101 that determines the period of cooperative operation is called the Sharing AP, and the AP 102 that shares the information determined by the Sharing AP is called the Shared AP, but other names may be used. For example, the AP 101 may be called a Coordinator AP or a Coordinating AP, and the AP 102 may be called a Coordinated AP. Also, for example, the AP 101 may be called a Master AP, and the AP 102 may be called a Slave AP.

[0018] Therefore, in the following description, unless otherwise specified, it should be understood that AP 101 is a communication device that functions as a Sharing AP, and AP 102 is a communication device that functions as a Shared AP.

[0019] However, although the above-mentioned procedure is used in the description, it should be noted that in reality, there may be cases where the AP 102 functions as a Sharing AP and the AP 101 functions as a Shared AP.

[0020] In addition, the wireless communication system of this embodiment is equipped with two communication devices (hereinafter also referred to as STA111 and STA112) that function as non-AP stations (hereinafter also referred to as STAs) as communication devices that perform wireless communication. Note that a communication device functioning as a non-AP station (hereinafter also referred to as an STA) is also called a counterpart device, since it is the counterpart to which a communication device functioning as an AP transmits data.

[0021] The STA 111 is located in a position where it can perform communication 121 with the AP 101 and communication 123 with the AP 102, and the STA 112 is located in a position where it can perform communication 122 with the AP 101. However, this positional relationship is not constant, and naturally, the STA 112 may be in a position where it can communicate with both the AP 101 and the AP 102.

[0022] In the following description, when there is no need to distinguish between the AP 101 and the AP 102, they may be referred to as APs, and when there is no need to distinguish between the STA 111 and the STA 112, they may be referred to as STAs.

[0023] Furthermore, FIG. 1 is merely an example, and the wireless communication system may be configured so that at least two APs share a transmission opportunity (TXOP) and perform communication (cooperative communication).

[0024] Therefore, the number of APs may be three or more, and the number of STAs may be one or may be three or more.

[0025] The AP 101, AP 102, and STA 111, STA 112 may be configured to be able to communicate in accordance with the IEEE802.11 series standards other than the IEEE802.11bn standard, in addition to the IEEE802.11bn standard.

[0026] In the following description, the roles of the AP 101 and the AP 102 are distinguished from each other, but the roles of the AP 101 and the AP 102 may be interchanged.

[0027] Furthermore, both the AP 101 and the AP 102 may be configured to be able to perform both the role of the AP 101 and the role of the AP 102, which will be described later.

[0028] The AP 101 and the AP 102 each form and manage a network called a Basic Service Set (BSS).

[0029] STA 111 and STA 112 can communicate with the APs that form the BSS by joining the BSS managed by either or both of the APs.

[0030] For example, as shown in FIG. 1, STA 111 may participate in the BSSs managed by AP 101 and AP 102, and STA 112 may participate in the BSS managed by AP 101.

[0031] AP101, AP102, STA111, and STA112 may be configured to support wireless communication based on other communication standards such as Bluetooth (registered trademark), NFC, Bluetooth (registered trademark) LE (Low Energy), etc.

[0032] In addition, the AP 101, the AP 102, the STA 111, and the STA 112 may be configured to support wireless communication based on other communication standards such as UWB, ZigBee, MBOA, and Matter.

[0033] Note that NFC stands for Near Field Communication, UWB stands for Ultra Wide Band, and MBOA stands for Multi Band OFDM Alliance.

[0034] UWB includes wireless USB, wireless 1394, WiNET, etc. The AP 101 and the AP 102 may also be configured to support wired communication using an Ethernet (registered trademark) cable or wired communication using optical fiber.

[0035] The communication devices (AP 101 and AP 102) that function as APs are, for example, wireless LAN routers, personal computers (PCs), etc., but are not limited to these.

[0036] For example, the communication devices (AP 101 and AP 102) that function as APs may be information processing devices such as wireless chips that can perform wireless communication in accordance with the IEEE802.11bn standard or the like.

[0037] On the other hand, communication devices that function as STAs (STA111 and STA112) are, for example, cameras, tablets, smartphones, PCs (personal computers), mobile phones, video cameras, headsets, etc., but are not limited to these.

[0038] For example, the communication devices (STA111 and STA112) functioning as STAs may be information processing devices such as wireless chips capable of performing wireless communication conforming to the IEEE802.11bn standard or the like.

[0039] In the wireless communication system of this embodiment, communication involving cooperative operations between APs is performed in order to improve the utilization efficiency of the wireless medium, reduce transmission delays, extend communication distances, and so on.

[0040] Specifically, communication devices functioning as APs (AP101, AP102) cooperate with each other to communicate with communication devices functioning as STAs (STA111 and STA112), and hereinafter this communication may be referred to as AP cooperative communication. Although not limited to these, examples of communication technologies suitable for use in AP cooperative communication are shown below.

[0041] [Examples of communication technologies suitable for AP cooperative communication] AP cooperative communication may be performed, for example, by utilizing coordinated spatial reuse (CSR). In CSR, multiple APs cooperate to carry out communications using the spatial reuse function in the IEEE802.11 series of standards, including the IEEE802.11ax standard and later. In CSR, for example, multiple APs communicate cooperatively using the spatial reuse function only for a predetermined period of time.

[0042] AP cooperative communication may be performed using, for example, coordinated OFDMA / TDMA. Note that OFDMA stands for coordinated orthogonal frequency division multiple access. Also, TDMA stands for time division multiple access. In coordinated OFDMA, for example, multiple APs share and use multiple resource units (RUs) that are obtained by dividing one channel along the frequency axis. In coordinated TDMA, for example, one channel is divided on the time axis into transmission opportunities (TXOPs), which are then shared and used.

[0043] AP cooperative communication may be performed using, for example, coordinated beamforming (CBF). In CBF, a plurality of APs cooperate with each other to spatially multiplex, for example, communication between one AP and a STA and communication between another AP and a STA.

[0044] AP cooperative communication may be performed using, for example, joint transmission (JT). JT uses distributed MIMO technology, which is based on a technology called MIMO (multi-user multi-output), which uses multiple transmitting and receiving antennas at the same time and on the same channel. In distributed MIMO, in an environment where multiple APs and STAs exist, the APs form groups to share information about the communication status and the status of each AP, and the multiple APs adjust their transmission timing to send data to the STAs in parallel. By having multiple APs transmit cooperatively, the number of spatial streams can be increased compared to a single AP, which is expected to improve throughput and communication quality. These cooperative operations are performed during a predetermined period determined by one of the APs.

[0045] For example, there may be cases where the period of data transmission to a communication device functioning as a STA targeted by AP cooperative communication overlaps with the period of data transmission to a communication device functioning as another STA not targeted by AP cooperative communication.

[0046] However, if the above-described communication technology is used for AP cooperative communication, AP cooperative communication may be possible without any problems even if the data transmission periods overlap as described above.

[0047] [Hardware configuration of communication device] FIG. 2 is a diagram illustrating a hardware configuration of the communication device according to the first embodiment.

[0048] The communication devices of this embodiment, that is, the communication devices (AP101, AP102) functioning as APs and the communication devices (STA111, STA112) functioning as STAs, may all have the same hardware configuration as shown in FIG.

[0049] Therefore, in the following description of the hardware configuration, unless there is a particular need to distinguish between them, the hardware configuration will be simply described as that of a communication device.

[0050] As shown in FIG. 2, the communication device has a memory unit 201, a control unit 202, a function unit 203, an input unit 204, an output unit 205, a communication unit 206, and multiple antennas (antenna 207, antenna 208, antenna 209). There is no particular limit to the number of antennas, and for example, antenna 207 may be the only antenna.

[0051] (Storage section 201) The storage unit 201 is configured with one or more memories such as a ROM and a RAM, and stores computer programs for performing various operations described below, and various information such as communication parameters for wireless communication. Note that ROM stands for Read Only Memory, and RAM stands for Random Access Memory.

[0052] In addition to memories such as ROM and RAM, storage units 201 may also be storage media such as flexible disks, hard disks, optical disks, magneto-optical disks, CD-ROMs, CD-Rs, magnetic tapes, non-volatile memory cards, and DVDs. Furthermore, the storage unit 201 may include a plurality of memories.

[0053] (control unit 202) The control unit 202 is configured with one or more processors such as a CPU or an MPU, and executes computer programs stored in the storage unit 201 to control the entire communication device. Note that CPU stands for Central Processing Unit, and MPU stands for Micro Processing Unit.

[0054] Furthermore, the control unit 202 may be provided with multiple processors such as multi-core processors, and the entire communication device may be controlled by the multiple processors.

[0055] Furthermore, the control unit 202 may control the entire communication device in cooperation with a computer program stored in the storage unit 201 and an OS (Operating System).

[0056] The control unit 202 then generates data and signals (radio frames) for data transmission in communication with other communication devices.

[0057] The control unit 202 also controls the function unit 203 to perform predetermined processes such as wireless communication, imaging, printing, and projection.

[0058] (Functional part 203) The function unit 203 is hardware for executing predetermined processes to realize the intended functions of the communication device depending on the type of the communication device. For example, if the communication device is a camera or the like, the functional unit 203 includes a necessary optical lens unit, an optical system that controls the aperture, zoom, focus, etc., and an image sensor that converts the light (image) introduced through the optical lens unit into an electrical image signal.

[0059] (input unit 204) The input unit 204 is hardware necessary for accepting various operations from the user. For example, there is a power button for turning the power on and off, a touch panel for inputting settings, and the like.

[0060] (output unit 205) The output unit 205 outputs various types of information to the user via a monitor screen and a speaker. Here, the output by the output unit 205 may be a display on a monitor screen, an audio output by a speaker, a vibration output, or the like.

[0061] Note that both the input unit 204 and the output unit 205 may be implemented in one module, such as a touch panel.

[0062] Furthermore, the input unit 204 and the output unit 205 may be integrated with the communication device or may be separate units.

[0063] (Communications Department 206) The communication unit 206 controls wireless communication in accordance with the IEEE802.11bn standard. The communication unit 206 may control wireless communication conforming to other IEEE802.11 series standards in addition to the IEEE802.11bn standard, and may control wired communication such as a wired LAN.

[0064] The communication unit 206 controls the antenna 207, the antenna 208, and the antenna 209 to transmit and receive signals generated by the control unit 202 for wireless communication.

[0065] If the communication device is compatible with the NFC standard, Bluetooth standard, or the like in addition to the IEEE802.11bn standard, it may control wireless communication in accordance with these communication standards.

[0066] Furthermore, if the communication device is capable of performing wireless communication in accordance with a plurality of communication standards, it may be configured to have separate communication units and antennas corresponding to each communication standard.

[0067] The communication device then communicates data such as image data, document data, and video data with other communication devices via the communication unit 206.

[0068] (antenna) Antenna 207, antenna 208, and antenna 209 are antennas capable of communication in the 2.4 GHz band, the 5 GHz band, the 6 GHz band, and the like. The antenna 207, the antenna 208, and the antenna 209 may be configured as separate units from the communication unit 206, or may be configured together with the communication unit 206 as a single module.

[0069] FIG. 2 shows a case where the communication device has three antennas: an antenna 207, an antenna 208, and an antenna 209. However, there is no particular limit to the number of antennas that a communication device has, and the number of antennas that a communication device has may be one, two, or even four or more.

[0070] Furthermore, the communication device may be equipped with one or more antennas that are different for each frequency band.

[0071] If the communication device has multiple antennas, the communication device may have a communication unit 206 for each antenna.

[0072] If both the transmitting and receiving sides have multiple antennas, MIMO (Multiple Input Multiple Output), a communication technology that allows transmission and reception using the same frequency during the same period, can be used for transmission and reception.

[0073] [Functional configuration of a communication device functioning as an AP] FIG. 3 is a block diagram showing the functional configuration of a communication device functioning as an AP according to the first embodiment. 3 is a diagram for explaining the main functions of the communication devices (AP 101 and AP 102) that function as APs in this embodiment, and other functions are omitted.

[0074] For example, a communication device that functions as an AP also has functions for establishing a connection with communication devices that function as STAs (STA111 and STA112), control functions for communication, and functions that communication devices generally have.

[0075] Furthermore, FIG. 3 is merely an example, and the multiple functional blocks shown in FIG. 3 may be integrated into one functional block, or one functional block may be divided into multiple functional blocks.

[0076] As shown in FIG. 3, the communication devices (AP101 and AP102) functioning as APs have, as their functional configuration, a frame control unit 301, an access point cooperation control unit 302, a transmission period control unit 303, and a communication control unit 304.

[0077] These functions are 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.

[0078] (Frame control unit 301) The frame control unit 301 generates and analyzes signals (frames) when communicating with other communication devices functioning as APs and communication devices functioning as STAs.

[0079] When the frame control unit 301 is the frame control unit 301 of the AP 101, the other communication device functioning as an AP is the AP . Moreover, the frame control unit 301 is an example of the frame control means according to the present invention.

[0080] For example, the frame control unit 301 generates a management frame for a communication device functioning as an AP to execute a connection procedure and a control frame for controlling communication.

[0081] The management frames include Beacon, Probe Response, Association Response, FILS (Fast Initial Link Setup) Discovery, and other Action frames.

[0082] The management frames generated by the frame control unit 301 are not limited to these, and may include, for example, an authentication frame.

[0083] Furthermore, the frame control unit 301 generates control frames, data frames, and the like.

[0084] Furthermore, the frame control unit 301 generates a TWT (Target Wake Time) element and the like defined in the IEEE802.11 series standard. For example, frame control unit 301 receives notifications from access point cooperation control unit 302 (described later) and transmission period control unit 303 (described later), and generates a frame to which a TWT element and the like are added.

[0085] The TWT element includes information such as a transmission period (cooperative period) during which a communication device functioning as an AP transmits data to a communication device functioning as an STA in cooperation with another communication device functioning as an AP.

[0086] In addition, the frame control unit 301 may obtain the transmission period (period of cooperative operation) of the other communication device functioning as an AP from the TWT element obtained by analyzing the frame received from the other communication device functioning as an AP, and notify the transmission period control unit 303.

[0087] (Access point cooperation control unit 302) The access point cooperation control unit 302 executes communication control of the communication device (AP 101) functioning as a Sharing AP or the communication device (AP 102) functioning as a Shared AP. The access point cooperation control unit 302 is an example of the access point cooperation control means according to the present invention.

[0088] For example, the access point cooperation control unit 302 determines with which other communication device, functioning as an AP, the communication device functioning as an STA should cooperate (coordinate) to transmit data.

[0089] Then, the access point cooperation control unit 302 notifies the frame control unit 301 of information on the other communication devices that function as APs with which it has decided to cooperate.

[0090] The information notified to the frame control unit 301 is information necessary for the frame control unit 301 to create a frame with TWT elements, etc. to be notified to other communication devices that will cooperate with the determined AP in order to cooperate (cooperate) with the other communication devices.

[0091] (Transmission period control unit 303) The transmission period control unit 303 determines a transmission period (a period of cooperative operation) for transmitting data to a communication device functioning as a destination STA in cooperation with another communication device functioning as an AP determined by the access point cooperation control unit 302. The transmission period control unit 303 is an example of a determination unit for determining a period for cooperative operation according to the present invention.

[0092] Then, transmission period control section 303 notifies frame control section 301 of the determined period for cooperative operation.

[0093] The frame control unit 301 uses the determined cooperative operation period to create a frame to which a TWT element including the cooperative operation period is added. Then, the frame with the TWT element etc. containing the created cooperative operation period is notified to other communication devices to cooperate (cooperate) with the other communication devices that function as the AP determined by the access point cooperation control unit 302.

[0094] (Communication control unit 304) The communication control unit 304 is a functional configuration for transmitting and receiving frames, etc. with other communication devices functioning as APs and communication devices functioning as STAs, and the communication control unit 304 is an example of a transmitting means and a receiving means according to the present invention.

[0095] For example, the communication control unit 304 receives frames from other communication devices functioning as APs and communication devices functioning as STAs, and notifies the frame control unit 301 of the received frames.

[0096] In addition, the communication control unit 304 transmits frames to notify, for example, other communication devices functioning as APs and communication devices functioning as STAs, of frames to which TWT elements, etc., generated by the frame control unit 301 have been added.

[0097] The TWT element includes a transmission period (a period of cooperative operation) during which data is transmitted in cooperation, and the communication control unit 304 is an example of a notification means for notifying surrounding communication devices, including other communication devices functioning as APs, of the period of cooperative operation according to the present invention.

[0098] Therefore, the period of cooperative operation is notified to surrounding communication devices, including other communication devices functioning as APs, and the period of cooperative operation is shared with other communication devices functioning as cooperating APs and communication devices functioning as STAs.

[0099] Then, a communication device functioning as an AP aligns the period of cooperative operation with other communication devices functioning as cooperating APs, and transmits data to a communication device functioning as an STA in cooperation with the other cooperating communication devices. That is, AP cooperative communication is performed in which the period of cooperative operation with other cooperating communication devices is the same.

[0100] [TWT information] Next, the TWT information will be described. In this embodiment, the Target Wake Time (TWT) information includes at least information about the Service Period (SP).

[0101] However, the TWT information is not limited to this and may further include information regarding other TWTs. For example, the TWT information may be configured to include Traffic Identifier (TID) information indicating the type of data that can be transmitted in the SP.

[0102] The TWT information may also be configured to include, for example, information about a TWT group indicating a group of communication devices functioning as multiple APs sharing a common SP, or a group of communication devices functioning as STAs.

[0103] In addition, an SP is something that is set through coordination between a communication device functioning as an AP and a communication device functioning as an STA in a network, and the SP indicates the period during which a communication device functioning as an STA is in an awake state (a state in which communication is possible).

[0104] Generally, a communication device functioning as an STA is in a Doze state (a state in which communication is not possible) outside an SP, but this is not limiting and the device may be configured to communicate outside an SP.

[0105] Within the SP, a communication device functioning as an STA is in an awake state and transmits and receives frames. On the other hand, outside the SP, a communication device functioning as a STA can save power by entering a Doze state.

[0106] The TWT information is not limited to this, and may be configured to include information included in TWT Parameter Information, which will be described later.

[0107] Furthermore, information about the SPs includes, for example, information about the start timing of the SPs, information about the time from the start to the end of the SPs, information about the interval between the start timings of the SPs, and the like.

[0108] [AP cooperative communication flow] Next, the flow of AP cooperative communication according to this embodiment will be described. FIG. 4 is a diagram showing a flow of AP cooperative communication according to the first embodiment. Specifically, Figure 4 shows the flow of communication processing when two communication devices (AP101, AP102) functioning as APs cooperate to transmit a data frame to STA111, a communication device functioning as a STA.

[0109] In this embodiment, as described above, it is assumed that the AP 101 is a communication device that functions as a Sharing AP, and the AP 102 is a communication device that functions as a Shared AP.

[0110] In addition, when three or more communication devices functioning as APs communicate in cooperation, one communication device functioning as an AP can function as a Sharing AP, and the remaining two or more communication devices functioning as APs can function as Shared APs.

[0111] Then, for example, a communication device functioning as a Shared AP identifies a period of cooperative operation based on information from a communication device functioning as a Sharing AP, and performs AP cooperative communication within the period of cooperative operation.

[0112] In the following, a communication device functioning as a Sharing AP may be simply referred to as AP 101, and a communication device functioning as a Shared AP may be simply referred to as AP 102.

[0113] Furthermore, the STA111 and STA112, which are communication devices that function as STAs, may also be simply referred to as STA111 and STA112.

[0114] The AP 101 and the AP 102 each start transmitting a Beacon frame in response to the wireless communication function via the wireless LAN being enabled.

[0115] The AP 101 and the AP 102 each periodically transmit a Beacon frame at a timing called a Target Beacon Transmission Time (TBTT).

[0116] The transmission intervals (BI) of the Beacon frames of the AP 101 and the AP 102 may be set individually, and the BI of the AP 101 and the AP 102 may have different values. Note that BI is an abbreviation for Beacon Interval.

[0117] After transmitting the Beacon frame 401, the AP 101 transmits the next Beacon frame 402 after the BI has elapsed.

[0118] Similarly, the AP 101 transmits a Beacon frame 403 after a lapse of BI from the transmission of the Beacon frame 402 .

[0119] In addition, in one example, the AP 102 transmits Beacon frames at a timing (TBTT) different from that of the AP 101.

[0120] The AP 102 transmits a Beacon frame 405 after a BI has elapsed since the transmission of the Beacon frame 404, and further transmits a Beacon frame 406 after a BI has elapsed since the transmission of the Beacon frame 405.

[0121] A TWT element, which will be described later, is assigned to the beacon in order to notify the AP 101 and the STA 111 of the period for which the AP 101 shares the TWT SP. The period of the shared TWT SP is an example of the period of cooperative operation described above, that is, an example of the period of cooperative operation according to the present invention.

[0122] The AP 102 checks the information of the TWT element given by the AP 101, as well as the TBTT and BI, and checks what period the TWT SP set with the STA 111 corresponds to for the AP 102.

[0123] Once the period is confirmed, the AP 102 may indicate the TWT SP by adding a TWT element to the Beacon frame.

[0124] That is, the AP 102 may add a TWT element to the Beacon frame to confirm the period (cooperative operation period) indicated by the shared TWT SP and indicate that the TWT SP has been shared.

[0125] Then, when the period indicated by TWT SP (period of cooperative operation) arrives, cooperative operation phase 411 is executed.

[0126] [Processing flow in collaborative operation phase 411] Next, an example of the flow of processing in the collaboration phase 411 will be described. FIG. 5 is a diagram showing the flow of processing in the collaborative operation phase 411 according to the first embodiment.

[0127] 5 illustrates the cooperative operation phase 411 in FIG. 4, in which the AP 101 and the AP 102 cooperatively transmit a data frame to the STA 111, as described above.

[0128] When the collaboration phase 411 (see FIG. 4) starts, the AP 101 transmits a trigger frame 601 to the AP 102 and the STA 111.

[0129] The trigger frame 601 may be a Basic Trigger Frame defined by IEEE802.11.

[0130] Then, the AP 101 transmits a trigger frame 601, thereby starting a period indicated by TWT SP (a period of cooperative operation). The trigger frame 601 may also be transmitted from the AP 102 at the same time.

[0131] After a SIFS (Short Inter Frame Space) has elapsed since the AP 101 transmitted the trigger frame 601, the AP 101 transmits a data frame 602 to the STA 111, and similarly, the AP 102 transmits a data frame 603 to the STA 111. The AP 101 may also send a data frame to the STA 112 .

[0132] When the STA 111 receives the data frame, it transmits an ACK frame 604 (Block Ack frame in FIG. 6) to the AP 101 and the AP 102 after the SIFS period has elapsed since the data frame was received.

[0133] The AP 101 and the AP 102 may transmit data frames on the same channel or on different channels.

[0134] For example, when the same channel is used, the same data frame may be transmitted to increase the reliability of data transmission.

[0135] Furthermore, when transmitting different data frames on the same channel, the streams (MIMO communication paths (antennas)) of the AP 101 and the AP 102 may be made different. In this way, by transmitting a separate data frame, it is possible to improve communication efficiency and throughput.

[0136] Furthermore, when using a different channel, the STA 111 may have a STA MLD (Multi Link Device) that supports Multi Link, and may receive data frames from the AP 101 and the AP 102 using multiple links.

[0137] For example, STA111 may be connected to AP101 via Link1 and to AP102 via Link2, and may receive data frames from AP101 via Link1 and from AP102 via Link2.

[0138] The number of links connecting the AP 101 and the STA 111 may be multiple. That is, the AP 101 and the STA 111 may be connected by a plurality of links, and the AP 102 and the STA 111 may be connected by a plurality of links.

[0139] The STA 111 transitions to the Awake state in all links at the set TWT SP, receives data frames from the AP 101 and the AP 102, and returns an ACK.

[0140] This limits the period during which the device is in the awake state, enabling communication with reduced power consumption.

[0141] [Operation of communication device functioning as AP] Next, an example of the flow of processing executed by the communication devices (AP 101 and AP 102) functioning as APs will be described. FIG. 6 is a flowchart showing the flow of processing executed by a communication device functioning as an AP according to the first embodiment.

[0142] Note that Figure 6 is merely an example, and the order of the processing steps shown in Figure 6 may be changed, some processing steps may be omitted, or some processing steps may be replaced with different processing steps of the same purpose, as long as there are no problems in performing the processing.

[0143] Furthermore, a plurality of processing steps shown in FIG. 6 may be executed in parallel, and the processing shown in FIG. 6 may be executed repeatedly as long as the communication device functions as an AP. That is, the process shown in FIG. 6 may be repeatedly executed while it is necessary to continue operating as an AP.

[0144] The flowchart of Figure 6 starts when the wireless LAN function of a communication device functioning as an AP is started (enabled), for example, in response to powering on the communication device or a user inputting information into the communication device via input unit 204.

[0145] (S701) The communication device functioning as an AP waits until a connection is established with a communication device functioning as an STA (S701: No). Then, when a connection is established between the communication device functioning as an AP and the communication device functioning as an STA (S701: Yes), the process proceeds to S702.

[0146] (S702) After a connection is established between a communication device functioning as an AP and a communication device functioning as an STA, the communication device functioning as an AP checks with the connected communication device functioning as an STA whether or not to transmit data in cooperation with other communication devices functioning as APs.

[0147] If data transmission is not to be performed in cooperation with other communication devices functioning as APs (S702: No), the process ends. It should be noted that if data transmission is not to be performed in cooperation with other communication devices functioning as APs (S702: No), the process may not end, but may return to S701 again.

[0148] On the other hand, if data transmission is to be performed in cooperation with another communication device functioning as an AP (S702: Yes), the process proceeds to S703.

[0149] For example, S702 may be answered Yes when the communication device functioning as a connected STA is far away and it is desired to transmit data to a greater distance by coordinating with another communication device functioning as an AP.

[0150] Also, the result of S702 may be Yes if, for example, it is desired to transmit data using a stronger radio wave to ensure that the data is delivered to the communication device functioning as the connected STA.

[0151] Furthermore, the result of S702 may be Yes when it is desired to transmit more information at once to a communication device functioning as a connected STA.

[0152] Additionally, the result of S702 may be Yes when it is desired to reduce the loss of data transmitted to a communication device functioning as an STA by cooperating with another communication device functioning as an AP.

[0153] (S703) The communication device functioning as an AP checks whether it will determine the TWT SP (cooperative operation period) itself, and if it will determine it itself (S703: Yes), the process proceeds to S704. On the other hand, if the user himself is not determined (S703: No), the process proceeds to S706. The following are examples of cases where the user makes the decision (S703: Yes).

[0154] "Examples of when you make your own decision" (1) If S703 is Yes, then: The communication device functioning as an AP that receives a TWT SP request directly from a communication device functioning as a connected STA in a TWT Request determines the TWT SP (period of cooperative operation).If the communication device receives the request directly, S703 will be Yes.

[0155] In this case, the communication device functioning as the AP desired by the communication device functioning as the connected STA determines (sets) the TWT SP (period of cooperative operation), so it is likely that the period of cooperative operation will be one that meets the wishes of the communication device functioning as the connected STA.

[0156] In addition, if the above-mentioned provisions are in place and the request has not been received directly by the user, the result of S703 will be No. In cases 2 and 3 described later, the result will also be No if the specified conditions are not met.

[0157] (2) If S703 is Yes, then: In the case where it is specified that the communication device functioning as a Sharing AP determines the TWT SP (cooperative operation period), if the communication device itself is a Sharing AP, the answer to S703 is Yes.

[0158] It is sufficient to define Procedure 1 or Procedure 2 so that the communication device functioning as a Sharing AP always determines the TWT SP (cooperative operation period), and details of Procedure 1 and Procedure 2 will be explained later in S704.

[0159] In this case, the communication device functioning as a Sharing AP collectively manages all TWT SPs (cooperative operation periods) of the communication devices functioning as cooperating APs.

[0160] Furthermore, since the TWT SP (cooperative operation period) is a period during which data is transmitted to a communication device functioning as an STA for which that period is set, it is also a period during which data transmission to another communication device functioning as an STA is restricted.

[0161] However, by having a communication device functioning as a Sharing AP centrally manage all TWT SPs (cooperative operation periods), it becomes possible to determine (set) TWT SPs to improve the efficiency of the entire wireless LAN environment.

[0162] Specifically, the entire connection state shown in FIG. 1 is collectively managed by AP 101, which is a communication device that functions as a Sharing AP. Therefore, in order to improve the efficiency of the entire wireless LAN environment, it becomes easier to control the allocation of TWT SP period A to STA112 connected to AP101, and TWT SP period B, which is different from period A, to STA111 connected to AP101 and AP102.

[0163] (3) If S703 is Yes, then: If it is specified that a communication device functioning as an AP that is close to a communication device functioning as a connected STA determines the TWT SP (cooperative operation period), and if the communication device itself is a communication device functioning as an AP that is close in distance, S703 will be Yes.

[0164] Note that distance here means that the communication environment between the communication device functioning as a connected STA is good; for example, a communication device functioning as an AP with a strong SNR may be determined to be closer in distance.

[0165] In this case, for example, a communication device functioning as a connected STA may measure the SNR and issue a TWT SP request in a TWT Request to a communication device functioning as an AP with a strong SNR.

[0166] Alternatively, the SNR may be measured by a communication device functioning as an AP, and the communication device functioning as an AP with a higher SNR may determine the TWT SP period (cooperative operation period). In this case, procedure 1 or procedure 2 described below in S704 may be performed so that the communication device functioning as an AP with a high SNR always determines the TWT SP period (cooperative operation period).

[0167] By doing as described above, the communication device functioning as an AP with a strong SNR determines the TWT SP, which may enable other communication devices functioning as APs to determine (set) a TWT SP that avoids radio interference that they may not be aware of.

[0168] (S704) Here, the communication device functioning as the AP determines the TWT SP (cooperative operation period). Specifically, the transmission period control unit 303 of the communication device functioning as an AP determines the TWT SP (cooperative operation period), and the transmission period control unit 303 notifies the frame control unit 301 of the determined TWT SP (cooperative operation period).

[0169] Upon receiving notification of the determined TWT SP (cooperative operation period), frame control unit 301 creates a frame to which a TWT element and the like including the determined TWT SP (cooperative operation period) are added.

[0170] However, the TWT SP (cooperative operation period) may be determined unilaterally by the transmission period control unit 303 of the communication device functioning as an AP, or may be determined through negotiation with the communication device functioning as an STA.

[0171] For example, when negotiating, a TWT Suggest frame can be sent to the communication device functioning as the target STA, prompting the communication device functioning as the STA to send a TWT Request to the communication device functioning as the AP.

[0172] It should be noted that the frame does not have to be limited to a TWT Suggest frame, and a new frame may be set to cause a communication device functioning as a target STA to transmit a TWT Request.

[0173] Then, the transmission period control unit 303 of the communication device functioning as an AP determines the TWT SP (cooperative operation period) after receiving a TWT Request from the communication device functioning as the target STA, and returns a TWT Response.

[0174] When returning the TWT Response, the communication device functioning as an AP may confirm with other communication devices functioning as cooperating APs that there are no problems with the determined TWT SP (cooperative operation period). Then, after confirming that there are no problems with the determined TWT SP (cooperative operation period), a TWT Response may be returned.

[0175] However, when determining the TWT SP (cooperative operation period) through negotiation as described above, it may not be possible to determine the TWT SP (cooperative operation period) in a manner that accepts the TWT SP (cooperative operation period) requested by the communication device functioning as the target STA.

[0176] For example, this may occur if the requested TWT SP (cooperative period) has already been allocated to a TWT SP (cooperative period) between a communication device functioning as an AP and another communication device functioning as an STA.

[0177] Similarly, the requested TWT SP (cooperative period) may already be allocated to a TWT SP (cooperative period) between another communication device functioning as a cooperating AP and another communication device functioning as a STA.

[0178] That is, this is the case when the requested TWT SP (cooperative operation period) overlaps with the data transmission period of a communication device functioning as the target STA and another communication device functioning as a different STA.

[0179] In this case, the communication device functioning as an AP may reply with a Reject and then send a Suggest / Demand / Alternate TWT to convey other TWT SP (cooperative period) candidates to the communication device functioning as the target STA.

[0180] On the other hand, when it is specified that a communication device functioning as a Sharing AP determines a TWT SP (cooperative operation period), a communication device functioning as a STA may send a TWT Request to a communication device functioning as a Shared AP.

[0181] Furthermore, when it is specified that a communication device functioning as an AP with a strong SNR determines the TWT SP, a communication device functioning as an STA may transmit a TWT Request to a communication device functioning as an AP with a weak SNR.

[0182] In this case, as mentioned above, procedure 1 or procedure 2 described below should be carried out. In the following, an example will be described in which it is determined that the communication device functioning as a Sharing AP determines the TWT SP (cooperative operation period).

[0183] However, the procedure itself is basically the same even when the communication device functioning as an AP with a strong SNR is set to determine the TWT SP.

[0184] In other words, in the following explanation, a communication device that functions as a Sharing AP should simply be read as a communication device that functions as an AP with a strong SNR, and a communication device that functions as a Shared AP should simply be read as a communication device that functions as an AP with a weak SNR.

[0185] Therefore, a description of the case where the communication device functioning as an AP with a strong SNR is set to determine the TWT SP will be omitted.

[0186] (Step 1) When a communication device functioning as a STA requests a TWT Request from a communication device functioning as a Shared AP, the communication control unit 304 of the communication device functioning as a Shared AP transfers the request to the communication device functioning as a Sharing AP.

[0187] During this transfer, the communication device functioning as a Shared AP may shift the time to match the time managed by the communication device functioning as a Sharing AP.

[0188] The information transferred may be the TWT element itself, which will be described later with reference to FIG. 7, or a part of the TWT element. For example, the following three fields of the TWT element may be transferred:

[0189] TWT Group Assignment field 823 Target Wake Time field 822 Nominal Minimum TWT Wake Duration field 824

[0190] It is assumed that the communication device (AP 101) functioning as a Sharing AP is a communication device functioning as an AP, and the communication device (AP 102) functioning as a Shared AP is another communication device functioning as an AP.

[0191] In this case, the communication control unit 304 of the other communication device functioning as an AP functions as a notification means for transferring some or all of the information of the received TWT Request to the communication device functioning as an AP in order to set the TWT SP.

[0192] Note that a communication device functioning as an AP may also function as another communication device functioning as an AP.

[0193] In this case, the communication control unit 304 of the communication device functioning as an AP also functions as a notification means for transferring part or all of the information of the received TWT Request to another communication device functioning as an AP.

[0194] By transferring the above information, the communication device functioning as a Sharing AP can be notified of the period for which the request was made to the communication device functioning as a Shared AP and the group to which the communication device functioning as the requesting STA belongs.

[0195] When the communication device functioning as the Sharing AP receives the request, the transmission period control unit 303 of the communication device functioning as the Sharing AP determines the TWT SP (cooperative operation period).

[0196] (Step 2) When a communication device functioning as an STA requests a TWT request from a communication device functioning as a Shared AP, the communication device functioning as a Shared AP prompts negotiation with the communication device functioning as a Sharing AP.

[0197] Specifically, the communication device functioning as a Shared AP returns a TWT Response to the communication device functioning as a STA, prompting the communication device to negotiate with the communication device functioning as a Sharing AP. The TWT Response is returned with a Status Code and BSSID that prompts the communication device functioning as the Sharing AP to negotiate.

[0198] This allows the communication device functioning as a STA to retransmit a TWT Request to the communication device functioning as a Sharing AP. Therefore, the transmission period control unit 303 of the communication device functioning as a Sharing AP can determine the TWT SP (cooperative operation period).

[0199] (S705) A communication device functioning as an AP notifies other communication devices functioning as APs and communication devices functioning as STAs of a frame to which a TWT element including a TWT SP (cooperative operation period) created by the frame control unit 301 has been added.

[0200] For example, the notification may be made by unicast, or may be sent to the surrounding area in a batch format including a Beacon frame.

[0201] Note that when a communication device functioning as a Sharing AP determines a TWT SP (period of cooperative operation) through procedure 1 described in S704, the communication device may notify the TWT SP (period of cooperative operation) as follows.

[0202] First, the communication device functioning as a Shared AP is notified of the TWT SP (cooperative operation period). Then, the communication device functioning as a Shared AP that has received the notification returns a TWT SP (cooperative operation period) to the communication device functioning as an STA in the form of a TWT Response frame.

[0203] (S709) The communication device functioning as an AP registers in the storage unit 201 the combination of the determined TWT SP (cooperative operation period) and the communication device functioning as an STA. The MAC address of the communication device functioning as the STA is used as the identifier when registering in the storage unit 201. Alternatively, an AID (Association Identifier) ​​may be used.

[0204] (S706) The process proceeds to S706 when, for example, the TWT SP (cooperative operation period) described above is determined by another communication device functioning as an AP.

[0205] Therefore, a communication device functioning as an AP requests another communication device functioning as an AP to transmit the determined TWT SP (cooperative operation period).

[0206] In addition, other communication devices functioning as APs that have determined the TWT SP (cooperative operation period) may notify surrounding devices functioning as APs by sending a Beacon frame all at once, as explained above in S705.

[0207] In this case, a communication device functioning as an AP can receive the determined TWT SP (period of cooperative operation) from another communication device functioning as an AP without requesting the other communication device functioning as an AP to transmit the determined TWT SP (period of cooperative operation).

[0208] Therefore, if other communication devices functioning as APs transmit the determined TWT SP (cooperative operation period) collectively to surrounding devices functioning as APs, the process may skip S706 and proceed to S707.

[0209] As explained above in S705, as a process corresponding to step 1, another communication device functioning as an AP may directly transmit the determined TWT SP (cooperative operation period). Therefore, in this case too, S706 may be omitted and the process may proceed to S707.

[0210] For example, if the process proceeds from S703 to S706 and the TWT SP (cooperative operation period) determined by another communication device functioning as an AP is not received within the specified time, it is determined that the TWT SP has not been transmitted to the communication device functioning as an AP and the process of S706 is carried out.

[0211] (S707) The communication device functioning as an AP receives the TWT SP (cooperative operation period) determined by the other communication device functioning as an AP, and proceeds to S708.

[0212] Note that the reception here includes not only the reception of the determined TWT SP (period of cooperative operation) in response to the processing of S706 from other communication devices functioning as APs, but also the reception of the determined TWT SP (period of cooperative operation) in response to a batch transmission to the surrounding area.

[0213] In any case, however, the communication device functioning as an AP receives the TWT SP (cooperative operation period) determined by the other communication device functioning as an AP, and upon receiving the TWT SP, the process proceeds to S708.

[0214] (S708) When a communication device functioning as an AP receives a TWT SP (period of cooperative operation) determined by another communication device functioning as an AP, the communication device determines whether to accept the received TWT SP (period of cooperative operation).

[0215] First, the communication device functioning as an AP checks whether the received TWT SP (period of cooperative operation) overlaps with a data transmission period between the communication device functioning as the STA scheduled for AP cooperative communication and another communication device functioning as a different STA.

[0216] Then, if the communication device functioning as an AP is not in a period of superposition, it accepts the received TWT SP (period of cooperative operation), and the transmission period control unit 303 of the communication device functioning as an AP determines (sets) its own TWT SP (period of cooperative operation).

[0217] In this way, if the received TWT SP (cooperative operation period) is accepted (S708: Yes), the process proceeds to S709, and the same processing as described above is performed.

[0218] On the other hand, if the received TWT SP (cooperative operation period) is not accepted (S708: No), the communication device functioning as an AP renegotiates the TWT SP (cooperative operation period). Specifically, if a communication device functioning as an AP is in a period of overlapping, it negotiates with another communication device functioning as an AP that has determined the TWT SP (period of cooperative operation) to see if it can change the TWT SP (period of cooperative operation).

[0219] In addition, if a communication device functioning as an AP has already set a TWT SP for the same period as another STA or for a period that overlaps with the other STA, it may negotiate with the communication device functioning as the STA that is the target of cooperative transmission to see if the TWT SP to be set can be changed.

[0220] For example, a communication device functioning as an AP transmits a TWT Request frame for requesting a change in the period of the TWT SP to another communication device functioning as an AP, and starts the process again from S703.

[0221] Alternatively, the period may be suggested by setting the TWT Setup Command field 832 to 1. The element to be assigned at this time may be a combination of the STA identifier and the TWT element, as will be described later. Alternatively, the TWT element may be extended to include the STA identifier in the TWT element.

[0222] In this way, if the received TWT SP (cooperative operation period) is not accepted (S708: No), the communication device functioning as an AP adjusts the TWT SP with another communication device functioning as an AP that determined the TWT SP.

[0223] By doing as described above, it is possible to set a TWT SP as a period for cooperative operation that does not overlap with the data transmission period of a communication device functioning as the STA that is the target of AP cooperative communication and another communication device functioning as a different STA.

[0224] As a result, each communication device functioning as an STA transmits data in a different data transmission period, thereby reducing interference.

[0225] Furthermore, when a communication device functioning as an AP transmits data to the same communication device functioning as an STA in cooperation with another communication device functioning as an AP, the communication device can set the TWT SP to a period of cooperative operation. As a result, a period of cooperative operation can be shared among a plurality of communication devices functioning as APs, and data can be transmitted to the same communication device functioning as STA during the same period or during periods that overlap.

[0226] Incidentally, in the above, we have explained the case where the period for cooperative operation is determined (set) while avoiding overlapping of data transmission periods. However, if the communication technology suitable for AP cooperative communication shown above is used, AP cooperative communication may be possible even if the periods overlap.

[0227] Therefore, in the following cases, the TWT SP may be set as the period for cooperative operation that overlaps with the data transmission period of a communication device functioning as the STA that is the target of AP cooperative communication and another communication device functioning as a different STA.

[0228] For example, even if a period overlaps with the data transmission period of another communication device functioning as an STA, if cooperative operation is possible by reducing the transmission output, the TWT SP in that overlapping period may be set as the period for cooperative operation. In other words, if coordinated operation is possible by using spatial reuse that limits the power during transmission, the TWT SPs that overlap may be set as periods for coordinated operation.

[0229] Furthermore, even if a period overlaps with a data transmission period, if cooperative operation is possible by not overlapping Resource Units for OFDMA communication, the TWT SP that overlaps the period may be set as a period for cooperative operation.

[0230] Even during a period that overlaps with a data transmission period, if cooperative operation is possible by separating the transmission timing of a communication device functioning as an AP and another communication device functioning as an AP within the overlapping period, the TWT SP that falls within the overlapping period may be set as a period for cooperative operation.

[0231] In other words, if cooperative operation is possible by adjusting the transmission states of a communication device functioning as an STA and a communication device functioning as an AP, the overlapping TWT SP may be set as the period for cooperative operation.

[0232] In addition, even if a period overlaps with a data transmission period, if coordinated operation is possible using Coordinated Beamforming, the TWT SP that overlaps the period may be set as a period for coordinated operation.

[0233] By doing so, the period of time that radio waves are occupied can be reduced, and other periods can be allocated to other communications.

[0234] In any case, when transmitting to a communication device functioning as the same STA, by aligning the TWT SP, the period during which the communication device functioning as the STA is in an awake state can be limited, allowing communication with reduced power consumption. Additionally, allocating other time periods to other communications will make communications more efficient across the environment.

[0235] [TWT element] Next, the Extended TWT element added to the Beacon frame will be described. FIG. 7 is a diagram showing an example of an Extended TWT element added to a Beacon frame according to the first embodiment. The elements shown in FIG. 7 may be used when requesting a change in TWT SP from a communication device functioning as another AP, or in response thereto.

[0236] As shown in FIG. 7, the Extended TWT element includes an Element ID field 801 and a Length field 802. The Extended TWT element also includes an Element ID Extension field 803 , a STA MAC Address field 804 , and a TWT Element field 805 .

[0237] The Element ID field 801 and the Element ID Extension field 803 indicate that the element is an Extended TWT element. The Length field 802 indicates the length of the element.

[0238] The STA MAC Address field 804 indicates the identifier of the communication device that functions as the STA. For example, it may include the MAC address or AID of the communication device that functions as the STA.

[0239] The TWT Element field 805 contains the TWT Element. The TWT Element includes an Element ID field 811, a Length field 812, a Control field 813, and a TWT Parameter Information field 814.

[0240] The Element ID field 811 is set to 216 to indicate that the following element is a TWT element. The Length field 812 indicates the length of the TWT Element. The Control field 813 indicates the type of TWT Element and the type that represents the time to transition to the Awake state.

[0241] Depending on the type indicated in the Control field 813, the content of the TWT Parameter Information field 814 differs in part.

[0242] FIG. 7 shows an example in which the Control field 813 indicates that the TWT information is an individual TWT. The TWT information may also indicate broadcast TWT information.

[0243] The TWT Parameter Information field 814 includes a Request Type field 821 and a Target Wake Time field 822 . The TWT Parameter Information field 814 also includes a TWT Group Assignment field 823 and a Nominal Minimum TWT Wake Duration field 824 .

[0244] Additionally, the TWT Parameter Information field 814 includes a TWT Wake Interval Mantissa field 825 and a TWT Channel field 826 .

[0245] The Request Type field 821 includes a TWT Request field 831 , a TWT Setup Command field 832 , and a TWT Wake Interval Exponent field 833 .

[0246] For example, if the TWT Request field 831 is "1", it indicates a TWT Request. Also, if the TWT Request field 831 is "0", it indicates that it is a TWT Response.

[0247] The TWT Setup Command field 832 indicates the type of procedure for TWT information. For example, if the TWT Setup Command field 832 is "0", it indicates a Request TWT, if it is "1", it indicates a Suggest TWT, and if it is "2", it indicates a Demand TWT.

[0248] The TWT Wake Interval Exponent field 833 and the TWT Wake Interval Mantissa field 825 can indicate the interval of the TWT SP.

[0249] Specifically, the value indicated in the TWT Wake Interval Mantissa field 825 is multiplied by a value with 2 as the base and the value of the TWT Wake Interval Exponent field 833 as the exponent, to obtain the interval between TWT SPs.

[0250] The Target Wake Time field 822 indicates the TSF (timing synchronization function) that is requested of a communication device functioning as an STA to transition to an Awake state.

[0251] The TWT Group Assignment field 823 indicates the TWT group to be assigned to the communication device functioning as an STA, and includes a TWT Group ID. The TWT Group ID may be assigned to each communication device that functions as a STA that is a destination or source of transmission during cooperative operation.

[0252] For example, when data is transmitted simultaneously to a plurality of communication devices (STA111 and STA112) functioning as STAs, the TWT Group IDs of the plurality of communication devices (STA111 and STA112) are set to be the same.

[0253] When communication devices functioning as STAs (not shown) not shown in FIG. 1 are made to cooperate with each other for different periods, different TWT Group IDs are assigned to them.

[0254] Alternatively, a different TWT Group ID is assigned to a communication device that functions as a STA that is not a target of cooperative operation.

[0255] Communication devices functioning as STAs that are assigned the same TWT Group ID will be assigned the same TWT SP.

[0256] Instead of the STA MAC Address field 804, the TWT Group Assignment field 823 may be used to assign communication devices that function as STAs.

[0257] The information about which communication device functioning as an STA is assigned to which TWT Group ID may be shared among communication devices functioning as APs.

[0258] Before cooperating, a communication device functioning as an AP may notify other communication devices functioning as cooperating APs of a combination of a TWT Group ID and a STA MAC address, or a STA MLD MAC address or AID.

[0259] Also, when used in place of the STA MAC Address field 804, only the TWT Element frame is added to the Beacon frame or TWT Request frame.

[0260] The Nominal Minimum TWT Wake Duration field 824 is a field for expressing, in 256 μs units, the minimum period for which a STA is desired to be in an awake state when a TWT SP arrives.

[0261] The TWT Channel field 826 indicates the channel on which the TWT SP is to be performed.

[0262] The STA MAC Address field 804 may be included in the TWT Parameter Information field.

[0263] For example, the Control field 813 may indicate that the element is of a type that includes the STA MAC Address field 804 , and may be included at the end of the TWT Parameter Information field 814 .

[0264] <<Other embodiments>> A storage medium storing software program code for realizing the above-described functions may be supplied to a system or device, and the computer (CPU, MPU) of the system or device may read and execute the program code stored in the storage medium.

[0265] In this case, the program code itself read from the storage medium will realize the functions of the above-described embodiments, and the storage medium storing the program code will constitute the above-described device.

[0266] Examples of storage media that can be used to supply the program code include flexible disks, hard disks, optical disks, magneto-optical disks, CD-ROMs, CD-Rs, magnetic tapes, non-volatile memory cards, ROMs, DVDs, and the like.

[0267] In addition, not only can the above-mentioned functions be realized by the computer executing the program code it has read, but the OS running on the computer can also perform some or all of the actual processing based on the instructions of the program code to realize the above-mentioned functions. OS stands for Operating System.

[0268] Furthermore, the program code read from the storage medium is written into a memory provided on a function expansion board inserted into the computer or a function expansion unit connected to the computer. Then, based on the instructions of the program code, a CPU provided in the function expansion board or function expansion unit may perform some or all of the actual processing to realize the above-mentioned functions.

[0269] The present invention can also be realized by supplying a program that realizes one or more functions of the above-mentioned embodiments to a system or device via a network or storage medium, and having one or more processors in the computer of that system or device read and execute the program. It can also be realized by a circuit (for example, an ASIC) that realizes one or more functions.

[0270] As described above, the present invention is not limited to the above-described embodiments, and modifications and improvements to the embodiments are also included within the technical scope of the invention, which will be clear to those skilled in the art from the description of the claims. In addition, the following supplementary notes are disclosed regarding the above-described embodiment. [Appendix 1] A communication device that functions as an access point (AP) conforming to the IEEE 802.11 series standard, A determination means for determining a TWT SP (Target Wake Time Service Period) to be set as a period for cooperating with other communication devices functioning as other APs; a notification means for notifying the other communication device of information regarding the TWT SP; and a transmitting means for transmitting data in cooperation with the other communication devices using the notified TWT SP. [Appendix 2] The communication device according to claim 2, wherein the determining means sets the TWT SP to a period during which the communication device and the other communication device cooperate to transmit data to the same other communication device. [Appendix 3] The communication device according to claim 1 or 2, wherein the cooperative operation involves multiple APs performing cooperative transmission in parallel using distributed MIMO technology. [Appendix 4] The communication device according to any one of Supplementary Note 1 to Supplementary Note 3, wherein when the communication device and the other communication device transmit data to different counterpart devices, the determination unit sets the TWT SP as the cooperative operation period so that the TWT SP does not overlap with a data transmission period of the other communication device. [Appendix 5] The communication device according to any one of Supplementary Note 1 to Supplementary Note 4, wherein when the communication device and the other communication device transmit data to different counterpart devices, if cooperative operation is possible by the communication device or the other communication device reducing transmission output, the decision unit sets the TWT SP, which is set to a period overlapping with a data transmission period of the other communication device, as the period for cooperative operation. [Appendix 6] the determining unit, when the communication device and the other communication device transmit data to different counterpart devices, sets the TWT SP, which is set to a period overlapping with a data transmission period of the other communication device, as the cooperative operation period if cooperative operation is possible by not overlapping Resource Units of OFDMA communication used by the communication device and the other communication device. [Appendix 7] the determining unit, when the communication device and the other communication device transmit data to different communication devices, sets the TWT SP to a period for cooperative operation that overlaps with a data transmission period of the other communication device if cooperative operation is possible by separating the transmission timing of the communication device and the transmission timing of the other communication device within the TWT SP. [Appendix 8] The communication device according to any one of Supplementary Note 1 to Supplementary Note 7, wherein when the communication device and the other communication device transmit data to different counterpart devices, if the communication device and the other communication device are capable of cooperative operation by Coordinated Beamforming, the determination unit sets the TWT SP to a period overlapping with a data transmission period of the other communication device as the period of cooperative operation. [Appendix 9] The communication device according to any one of Supplementary Note 3 to Supplementary Note 8, wherein the notification means transfers part or all of the information of a TWT Request received from a counterpart device to which the communication device is to send data to the other communication device in order to set the TWT SP. [Appendix 10] A program for causing a computer to function as each step of the communication device described in any one of Supplementary Note 1 to Supplementary Note 9. [Appendix 11] A communication method for a communication device that functions as an access point (AP) conforming to the IEEE 802.11 series standard, a determination step of determining a TWT SP (Target Wake Time Service Period) to be set as a period for cooperating with other communication devices functioning as other APs; a notification step of notifying the other communication device of information about the TWT SP determined in the determination step; a transmitting step of transmitting data in cooperation with the other communication device using the TWT SP notified in the notifying step. [Explanation of symbols]

[0271] 101, 102 AP (communication device), 111, 112 STA (communication device), 101A, 102A communication area, 201 storage unit, 202 control unit, 203 function unit, 204 input unit, 205 output unit, 206 communication unit, 301 frame control unit, 302 access point cooperation control unit, 303 transmission period control unit (determination means), 304 communication control unit (notification means, transmission means)

Claims

1. A communication device that functions as an access point (AP) conforming to the IEEE 802.11 series standard, A determination means for determining a TWT SP (Target Wake Time Service Period) to be set as a period for cooperating with other communication devices functioning as other APs; a notification means for notifying the other communication device of information related to the TWT SP; a transmitting means for transmitting data in cooperation with the other communication devices using the notified TWT SP.

2. 2. The communication device according to claim 1, wherein the determining means sets the TWT SP to the period of cooperative operation when the communication device and the other communication device cooperatively transmit data to the same partner device.

3. The communication device according to claim 1 , wherein the cooperative operation is performed by a plurality of APs performing cooperative transmission in parallel using a distributed MIMO technique.

4. 2. The communication device according to claim 1, wherein the determining means sets the TWT SP to a period of cooperative operation that does not overlap with a data transmission period of the other communication device when the communication device and the other communication device transmit data to different counterpart devices.

5. 2. The communication device according to claim 1, wherein when the communication device and the other communication device transmit data to different counterpart devices, if cooperative operation is possible by the communication device or the other communication device suppressing transmission output, the determination means sets the TWT SP, which is set to a period overlapping with a data transmission period of the other communication device, as the period for cooperative operation.

6. 2. The communication device according to claim 1, wherein when the communication device and the other communication device transmit data to different counterpart devices, if cooperative operation is possible by not overlapping Resource Units of OFDMA communication used by the communication device and the other communication device, the determination means sets the TWT SP, which is set to a period overlapping with a data transmission period of the other communication device, as the period for cooperative operation.

7. 2. The communication device according to claim 1, wherein when the communication device and the other communication device transmit data to different counterpart devices, if cooperative operation is possible by separating the transmission timing of the communication device and the transmission timing of the other communication device within the TWT SP, the determination unit sets the TWT SP, which is a period overlapping with a data transmission period of the other communication device, as the period for cooperative operation.

8. 2. The communication device according to claim 1, wherein, when the communication device and the other communication device transmit data to different counterpart devices, if the communication device and the other communication device are capable of cooperative operation by Coordinated Beamforming, the determination unit sets the TWT SP, which is set to a period overlapping with a data transmission period of the other communication device, as the period of cooperative operation.

9. 9. The communication device according to claim 3, wherein the notification means transfers part or all of information of a TWT Request received from a partner device to which data of the communication device is to be transmitted to the other communication device in order to set the TWT SP.

10. A program for causing a computer to function as each step of the communication device according to any one of claims 1 to 8.

11. A communication method for a communication device that functions as an access point (AP) conforming to the IEEE 802.11 series standard, comprising: a determining step of determining a TWT SP (Target Wake Time Service Period) to be set as a period for cooperating with other communication devices functioning as other APs; a notification step of notifying the other communication device of information about the TWT SP determined in the determination step; a transmitting step of transmitting data in cooperation with the other communication device by the TWT SP notified in the notifying step.

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