Communication control device and communication control method

Abstract

To provide a communication device which realizes data sharing and data cooperative transmission.SOLUTION: A communication device which operates as an access point includes: a communication unit for sending or receiving radio signals; and a control unit for controlling communication operations in the communication unit, the communication operations including a communication operation for sharing data to send to one communication terminal simultaneously between access points next to each other and a communication operation for recognizing completion of sharing of the data. The control unit multiplies the shared data with a transmission stream for another communication device when sending the data between the access points next to each other simultaneously, and sends the data as a multi-user multiplex stream.SELECTED DRAWING: Figure 1

Description

Technical Field

[0001] The technology disclosed in this specification relates to a communication device and a communication method for transmitting and receiving wireless signals.

Background Art

[0002] A technique for spatially multiplexing and wirelessly transmitting multiple data by the Multiple Input Multiple Output (MIMO) method has already been put into practical use. By using this MIMO technology, for example, data can be simultaneously transmitted from one source communication device operating as an access point to a plurality of destination communication devices operating as communication terminals. Specifically, when the access point is equipped with a plurality of antenna modules and the communication terminal is composed of one antenna module, the downlink transmission rate can be increased by using the downlink MIMO technology.

[0003] On the other hand, a technique for avoiding interference between adjacent access points and communicating by operating a plurality of access points in cooperation is also being put into practical use. Recently, a multi-point cooperative transmission technology has been developed in which data is simultaneously transmitted from a plurality of access points to one destination communication device, and the data successfully received at the destination is acquired.

[0004] For example, in a system in which access points are connected via a wired LAN (Local Area Network) such as Ethernet (registered trademark) or other communication means and are synchronized in advance, a method in which the access points cooperate to perform data transmission can be considered. In addition, a proposal has been made for a wireless communication device that aggregates a plurality of groups and performs scheduled access in each group (see, for example, Patent Document 1).

Prior Art Documents

Patent Documents

[0005]

Patent Document 1

[0006] The objective of the technology disclosed herein is to provide a communication device and a communication method that can suitably realize data sharing and coordinated transmission of shared data. [Means for solving the problem]

[0007] The first aspect of the technology disclosed herein is: A communication unit that transmits and receives wireless signals, A control unit that controls the communication operations in the communication unit, including communication operations for sharing data to be simultaneously transmitted to a single communication terminal between adjacent access points, and communication operations for recognizing that the sharing of said data has been completed. It is a communication device that operates as an access point and is equipped with the following features.

[0008] The communication unit is capable of transmitting and receiving wireless signals that consist of multiple data streams. The control unit controls the transmission of the shared data simultaneously with the adjacent access point, by multiplexing it with transmission streams destined for other communication devices, and transmitting it as a multi-user multiplexed stream. The control unit also controls the transmission of data shared between adjacent access points by multiplexing it as multiple streams.

[0009] Furthermore, a second aspect of the technology disclosed herein is: The steps include: sharing data to be sent simultaneously to a single communication terminal between adjacent access points; A step of recognizing that the sharing of the aforementioned data has been completed, The steps include sending the shared data, This is a communication method at an access point that has [a certain characteristic].

[0010] Furthermore, a third aspect of the technology disclosed herein is: A communication unit that transmits and receives wireless signals, A control unit that controls the communication operation in the communication unit, including an operation that recognizes that the same data has been transmitted simultaneously from multiple access points based on the receipt of a predetermined frame from an access point, It is a communication device that operates as a communication terminal connected to an access point, and is equipped with the following features.

[0011] The predetermined frame is a grant frame containing information regarding the sharing of the same data between adjacent access points. The grant frame includes at least one of the following: information regarding the communication terminal, information regarding the number of multiple transmissions when transmitting the shared data, and communication parameters when transmitting the shared data.

[0012] Furthermore, the fourth aspect of the technology disclosed herein is, The steps include receiving a predetermined frame from an access point, The steps include: recognizing, based on the received predetermined frame, that the same data was transmitted simultaneously from multiple access points; The steps include receiving the same data transmitted simultaneously from the multiple access points, This is a communication method for a communication terminal connected to an access point, which has [a certain feature / ability]. [Effects of the Invention]

[0013] The technology disclosed herein provides a communication device and communication method that enables data to be shared between access points in a short time and that allows for efficient use of wireless transmission paths through the coordinated transmission of shared data.

[0014] The effects described herein are merely illustrative, and the effects of the present invention are not limited thereto. Furthermore, the present invention may produce additional effects beyond those described above.

[0015] Other objects, features, and advantages of the technology disclosed in this specification will become apparent from the more detailed description based on the embodiments described below and the accompanying drawings.

Brief Description of the Drawings

[0016] [Figure 1] FIG. 1 is a diagram showing a configuration example of a wireless network. [Figure 2] FIG. 2 is a diagram showing another configuration example of a wireless network. [Figure 3] FIG. 3 is a diagram showing a process of implementing data sharing and cooperative transmission between multiple access points. [Figure 4] FIG. 4 is a diagram showing a process of implementing data sharing and cooperative transmission between multiple access points. [Figure 5] FIG. 5 is a diagram showing an example of a communication sequence for performing an operation check to realize cooperative transmission. [Figure 6] FIG. 6 is a diagram showing an example of a communication sequence for performing an operation check to realize cooperative transmission. [Figure 7] FIG. 7 is a diagram showing a configuration example of an association frame. [Figure 8] FIG. 8 is a diagram showing a configuration example of a cooperative frame. [Figure 9] FIG. 9 is a diagram showing a configuration example of an initiate frame. [Figure 10] FIG. 10 is a diagram showing a configuration example of a grant frame. [Figure 11] FIG. 11 is a diagram showing a configuration example of a trigger frame. [Figure 12] FIG. 12 is a diagram showing the internal structure of a data frame. [Figure 13] FIG. 13 is a diagram showing a configuration example of a data frame. [Figure 14] FIG. 14 is a diagram showing a configuration example of a data frame. [Figure 15] FIG. 15 is a diagram showing a configuration example of a data frame. [Figure 16] Figure 16 shows an example of a data frame structure. [Figure 17] Figure 17 shows an example of a data frame structure. [Figure 18] Figure 18 shows an example of a data frame structure. [Figure 19] Figure 19 shows an example of a data frame structure. [Figure 20] Figure 20 is a schematic diagram showing an example of the functional configuration of the communication device 2000. [Figure 21] Figure 21 shows an example of the internal configuration of the wireless communication module 2005. [Figure 22] Figure 22 is a flowchart showing the process for an access point to register a communication terminal. [Figure 23] Figure 23 is a flowchart showing the process for an access point to register an adjacent access point. [Figure 24] Figure 24 is a flowchart showing the processing procedure when an access point receives transmitted data. [Figure 25] Figure 25 is a flowchart showing the processing steps for an access point to actively perform coordinated transmission. [Figure 26] Figure 26 is a flowchart showing the processing steps for an access point to passively perform coordinated transmission. [Figure 27] Figure 27 is a flowchart illustrating the processing procedure for a communication terminal to receive coordinated transmission data from multiple access points. [Modes for carrying out the invention]

[0017] Hereinafter, embodiments of the technology disclosed herein will be described in detail with reference to the drawings.

[0018] This specification proposes a technology for optimizing data sharing and coordinated transmission among multiple access points. Specifically, it proposes a technology that optimizes data sharing and coordinated transmission by pre-sharing data to be transmitted coordinately between adjacent access points, specifying the communication devices to be transmitted coordinately in a grant frame that notifies that the data has been shared, and notifying them in advance that coordinated transmission will be performed at a later time.

[0019] Furthermore, this specification proposes a technology that efficiently utilizes the wireless transmission path when an access point performs coordinated transmission, by multiplexing not only data destined for one communication device but also data destined for other communication devices using multi-user spatial division multiplexing communication technology.

[0020] Furthermore, this specification proposes a technology that enables the rapid sharing of data between access points by utilizing single-user spatial division multiplexing communication technology, and then synchronizes and transmits the data at a predetermined timing after sharing.

[0021] Figure 1 shows an example configuration of a wireless network to which the technology disclosed herein is applied. The illustrated wireless network consists of a first network group and a second network group.

[0022] The first network group consists of access point AP1 and communication terminals STA1 and STA3 connected to AP1. The second network group consists of access point AP2 and communication terminal STA2 connected to AP2. In Figure 1, the boundaries of each network group are enclosed by dotted lines. The transmission signals of each access point AP1 and AP2 are indicated by solid arrows.

[0023] Here, we assume that access points AP1 and AP2 in each network group are located in a position where they can communicate with each other. Furthermore, we assume that communication terminal STA3 in the first network group is located in a position where it can communicate with access point AP2 and communication terminal STA2 of the second network group.

[0024] Furthermore, in the wireless network shown in Figure 1, it is assumed that interference waves from other communication systems (Other) and other interference sources reach both communication terminal STA3 in the first network group and communication terminal STA2 in the second network group. In Figure 1, the interference signals are indicated by dotted arrows.

[0025] Since STA3 can communicate with both AP1 and AP2, it can receive the same data from multiple access points AP1 and AP2. Therefore, if data is shared between AP1 and AP2, AP1 and AP2 can transmit the same data simultaneously. STA3 can then receive this simultaneously transmitted data, thereby ensuring more reliable data reception.

[0026] Furthermore, data sharing between access points AP1 and AP2 may be performed via wired communication such as Ethernet (registered trademark) instead of wireless communication.

[0027] Figure 2 shows another example configuration of a wireless network to which the technology disclosed herein is applied. The illustrated wireless network consists of a first network group and a second network group.

[0028] The first network group consists of access point AP1 and communication terminals STA1 and STA3 connected to AP1. The second network group consists of access point AP2 and communication terminal STA2 connected to AP2. The wireless network shown in Figure 2 also assumes the existence of a master access point (M-AP) that oversees both network groups, and the presence of other communication systems that act as interference sources. Interference waves from the interference sources are assumed to reach communication terminal STA3 in the first network group and communication terminal STA2 in the second network group. In Figure 2, the boundaries of each network group are enclosed by dotted lines. The transmission signals of access points AP1 and AP2 are shown by solid arrows, and the interference signals are shown by dotted arrows.

[0029] Since the M-AP can communicate with both AP1 and AP2, data can be shared. Specifically, the M-AP can transmit the received data to AP1 and AP2 at high speed, and both AP1 and AP2 can coordinately deliver the data to STA3. Then, STA3 can receive the data transmitted simultaneously from AP1 and AP2, thus ensuring more reliable data reception.

[0030] Furthermore, data sharing between access point M-AP and AP1 and AP2 may be performed via wired communication such as Ethernet (registered trademark) instead of wireless communication.

[0031] Figure 3 illustrates the flow of data sharing and coordinated data transmission between multiple access points. However, it assumes the wireless network configuration shown in Figure 1, with the horizontal axis representing time. The solid rectangles on each horizontal axis represent the signals (or frames) transmitted by the corresponding communication device during the corresponding time interval. The dotted rectangles represent the signals (or frames) received by the corresponding communication device during the corresponding time interval.

[0032] Here, access point AP1 actively performs coordinated transmission, while AP2 passively performs coordinated transmission. Furthermore, communication terminals STA1 and STA3 operate within the first network group operated by AP1, and communication terminal STA2 operates within the second network group operated by AP2.

[0033] Furthermore, STA2 and STA3 receive interference signals from other communication systems and other interference sources (Other). STA2 and STA3 can recognize the period during which interference signals are received as a BUSY state. Therefore, each access point AP1 and AP2 can understand that they cannot communicate with STA2 and STA3 because there is no response during the period when interference signals (BUSY) are received from the interference source (Other).

[0034] Under these circumstances, access point AP1 initiates a data sharing initiation (Ini) for coordinated transmission to its subordinate communication terminal STA3, specifying the target access point AP2.

[0035] The data sharing initiation is started by the access point that actively performs coordinated transmission, as needed. In the example shown in Figure 3, AP1 initiates the initiation. The initiation may also be started immediately after notification is sent between both access points AP1 and AP2 in advance, or immediately before coordinated transmission is performed. Alternatively, the initiation may be sent along with the shared data when coordinated transmission is performed.

[0036] During the initiation process, access point AP2, which passively performs cooperative transmission, will receive shared data in response to requests from access point AP1, which actively performs cooperative transmission. For example, using SU (Single User)-MIMO spatial division multiplexing technology or frequency channel bonding technology, data to be transmitted cooperatively is sent from AP1 to AP2, and data destined for STA3 (DMU-3) is shared between AP1 and AP2 in a short time.

[0037] It should be noted that by utilizing the BUSY state in which STA2 and STA3 are affected by interference signals from the interference source (Other), communication processing can be carried out between AP1 and AP2 to share data (DMU-3) destined for STA3. Furthermore, by using a high-speed transmission MCS (Modulation and Coding Scheme) in the communication of shared data (DMU-3) from AP1 to AP2, data sharing between access points can be achieved in a short time.

[0038] When AP2 receives shared data from AP1, it sends back a grant frame to AP1 acknowledging receipt and specifying STA3 as the target to receive the coordinated transmission.

[0039] Grant frames transmitted from AP2 reach not only AP1 but also STA2 and STA3. The frame interval between grant frames and data frames (described later) that coordinately transmit shared data is constant. Therefore, STA2 and STA3, having received the grant frame, can ensure time synchronization with access points AP1 and AP2, and can recognize that coordinated transmission by surrounding access points will be carried out within a predetermined time.

[0040] AP1 then sends a trigger frame containing various parameters for coordinated transmission to its subordinate communication terminals STA1 and STA3, and to AP2, which passively performs coordinated transmission. Subsequently, AP1 and AP2 synchronize their timing and simultaneously transmit the shared data in a coordinated manner.

[0041] The trigger frame transmitted from AP1 reaches not only AP2, but also STA1 and STA3. The frame interval between the trigger frame and the data frame immediately following it is constant. Therefore, AP2, STA1, and STA3, having received the trigger frame, can ensure precise (microsecond-level) time synchronization with access point AP1.

[0042] Here, the data transmitted from each access point AP1 and AP2 may also be spatially multiplexed at each access point. In the example shown in Figure 3, from AP1, data for STA3 (CDMU-3) shared with AP2 is multiplexed with data for STA1 under AP1 (CDMU-1) using spatial multiplexing technology and transmitted. Similarly, from AP2, data for STA2 under AP2 (CDMU-2) is multiplexed with data for STA3 (CDMU-3) shared with AP1 (CDMU-3) using spatial multiplexing technology and transmitted. In this way, access points can efficiently utilize the wireless transmission path by spatially multiplexing the data they transmit in cooperation with data destined for other communication terminals.

[0043] Furthermore, when an access point spatially multiplexes data to be transmitted in coordination with data destined for other communication terminals, it is configured to synchronize the time lengths of each transmission data before transmission, and padding (P) is applied to the transmission data with the shorter time length.

[0044] In the example shown in Figure 3, AP1 applies padding (P) to the data for STA1 (CDMU-1), which is shorter than the data for co-transmitted to STA3 (CDMU-3), to equalize the duration of CDMU-3 before transmission. Similarly, AP2 applies padding (P) to the data for STA2 (CDMU-2), which is shorter than the data for co-transmitted to STA3 (CDMU-3), to equalize the duration of CDMU-3 before transmission.

[0045] The data transmitted by AP1 and AP2 via spatial division multiplexing is received by STA1, STA2, and STA3. STA1, STA2, and STA3 then collect the data addressed to themselves and send back acknowledgments in the form of block ACKs (BAs). In the case of STA3, acknowledgment is considered complete if it successfully receives either the CDMU-3 data sent from AP1 or the CDMU-3 data sent from AP2.

[0046] Each access point sends a Block ACK Request (BAR) at a different time, and each communication terminal replies with a Block ACK at a different time for each access point. In the example shown in Figure 3, AP1 sends a Block ACK Request at the first timing, and ACK frames to AP1 are replied by STA1 and STA3. Then, AP2 sends a Block ACK Request at the second timing, and ACK frames to AP2 are replied by STA2 and STA3.

[0047] These ACK frames may be returned using uplink multi-user MIMO technology, or they may be returned as response frames to a given trigger frame.

[0048] If AP1 has received all ACK frames returned from both STA1 and STA3, it discards all of the transmission data CDMU-1 and CDMU-3 stored in its transmit buffer. In other words, even if either AP1 or AP2 fails to receive CDMU-3 correctly, STA3 will still consider it received. If AP1 fails to receive any ACK frames, it will begin retransmitting the corresponding data. Similarly, if AP2 has received all ACK frames returned from both STA2 and STA3, it discards all of the transmission data CDMU-2 and CDMU-3 stored in its transmit buffer. If AP2 fails to receive any ACK frames, it will begin retransmitting the corresponding data.

[0049] Figure 4 illustrates the flow of data sharing and coordinated data transmission between multiple access points. However, it assumes the wireless network configuration shown in Figure 2, with the horizontal axis representing time. Each rectangle on the horizontal axis represents the signal (or frame) transmitted by the corresponding communication device during the corresponding time interval. The rectangles drawn with dotted lines represent the signal (or frame) received by the corresponding communication device during the corresponding time interval.

[0050] Here, a master access point (M-AP) manages coordinated transmission, and access points AP1 and AP2 in each network group passively perform coordinated transmission under the management of the M-AP. Furthermore, communication terminals STA1 and STA3 operate as part of the first network group operated by AP1, and communication terminal STA2 operates as part of the second network group operated by AP2.

[0051] Furthermore, STA2 and STA3 receive interference signals from other communication systems and other interference sources (Other). STA2 and STA3 can recognize the period during which interference signals are received as a BUSY state. Therefore, each access point AP1 and AP2 can understand that communication to STA2 and STA3 is not possible during the period when signals are received from the interference source (Other).

[0052] Under these circumstances, the master AP initiates an Ini (Initiation Ini) for data sharing for coordinated transmission, specifying the target access points AP1 and AP2.

[0053] The data sharing initiation is started by the access point managing the coordinated transmission as needed. In the example shown in Figure 4, the master AP initiates the initiation. The initiation may also be started immediately after notification is sent between the two access points in advance, or immediately before coordinated transmission is performed. Alternatively, the initiation may be sent along with the shared data when coordinated transmission is performed.

[0054] During the initiation process, access points AP1 and AP2, which passively perform coordinated transmission, receive shared data in response to requests from the master AP that manages the coordinated transmission. For example, data destined for each communication terminal STA1, STA2, and STA3 is transmitted from the master AP. For example, using SU-MIMO spatial division multiplexing technology or frequency channel bonding technology, data to be transmitted coordinately is sent from the master AP to AP1 and AP2, and the data destined for STA3 (DMU-3) is shared between AP1 and AP2 in a short time. In addition, data destined for STA1 (DMU-1) is sent from the master AP to AP1, and data destined for STA2 (DMU-2) is sent from the master AP to AP2. Then, using MU-MIMO technology, this data is transmitted from AP1 and AP2 to each communication terminal STA1, STA2, and STA3 (described later).

[0055] It should be noted that by utilizing the BUSY state in which STA2 and STA3 are affected by interference signals from an interference source (Other), communication processing can be performed between the master AP and AP1 and AP2 to share data (DMU-3) destined for STA3. Furthermore, by using a high-speed transmission MCS in the communication of shared data (DMU-3) from the master AP to AP1 and AP2, data sharing between access points can be achieved in a short time.

[0056] Upon receiving shared data from the master AP, AP1 and AP2 each send back an acknowledgment of receipt and a grant frame targeting STA3, which should receive the coordinated transmission, to the master AP. Although AP1 and AP2 send grant frames simultaneously here, the configuration is such that transmission is performed using uplink multi-user MIMO spatial division multiplexing, etc.

[0057] Grant frames transmitted from AP1 reach not only the master AP but also AP2, STA1, and STA3, and grant frames transmitted from AP2 reach not only the master AP but also AP1, STA2, and STA3. The frame interval between grant frames and data frames (described later) that coordinately transmit shared data is constant. Therefore, STA2 and STA3, which have received a grant frame, can ensure time synchronization with the master AP, AP1, and AP2, and can recognize that coordinated transmission by surrounding access points will be carried out within a predetermined time.

[0058] The master AP then sends a trigger frame containing various parameters for coordinated transmission to AP1 and AP2. Subsequently, AP1 and AP2 synchronize their timing and simultaneously transmit the shared data in a coordinated manner. The frame interval between the trigger frame and the data frame immediately following it is constant. Therefore, AP1 and AP2, having received the trigger frame, can ensure precise (microsecond-level) time synchronization with the master AP.

[0059] Here, the data transmitted from each access point AP1 and AP2 may also be spatially multiplexed at each access point. In the example shown in Figure 4, the data transmitted from AP1 is multiplexed and transmitted as data for STA1 (CDMU-1) and data for STA3 (CDMU-3). Similarly, the data transmitted from AP2 is multiplexed and transmitted as data for STA2 (CDMU-2) and data for STA3 (CDMU-3). In this way, by spatially multiplexing the data that access points are co-transmitting with data destined for other communication terminals, the wireless transmission path can be used efficiently.

[0060] When an access point spatially multiplexes data to be transmitted in coordination with data destined for other communication terminals, it is configured to equalize the time length of each transmission data before transmission, and padding (P) is applied to the shorter transmission data. In the example shown in Figure 4, AP1 applies padding (P) to the data destined for STA1 (CDMU-1), which is shorter than the data to be transmitted in coordination for STA3 (CDMU-3), to equalize the time length of CDMU-3 before transmission. Similarly, AP2 applies padding (P) to the data destined for STA2 (CDMU-2), which is shorter than the data to be transmitted in coordination for STA3 (CDMU-3), to equalize the time length of CDMU-3 before transmission.

[0061] The data transmitted by AP1 and AP2 via spatial division multiplexing is received by STA1, STA2, and STA3. STA1, STA2, and STA3 then collect the data addressed to themselves and send back acknowledgments in the form of block ACKs (BAs). In the case of STA3, acknowledgment is considered complete if it successfully receives either the CDMU-3 data sent from AP1 or the CDMU-3 data sent from AP2.

[0062] Each access point sends a Block ACK Request (BAR) at a different timing, and each communication terminal replies with a Block ACK at a different timing for each access point. In other words, even if either the CDMU-3 sent from AP1 or AP2 is not received correctly, STA3 will still be able to receive it. In the example shown in Figure 4, at the first timing, AP1 sends a Block ACK Request, and ACK frames to AP1 are replied from STA1 and STA3. At the second timing, AP2 sends a Block ACK Request, and ACK frames to AP2 are replied from STA2 and STA3.

[0063] These ACK frames may be returned using uplink multi-user MIMO technology, or they may be returned as response frames to a given trigger frame.

[0064] If AP1 has received all ACK frames returned from STA1 and STA3, it will discard all of the transmission data CDMU-1 and CDMU-3 stored in its transmit buffer. If AP1 fails to receive any ACK frames, it will begin retransmitting the corresponding data. Similarly, if AP2 has received all ACK frames returned from STA2 and STA3, it will discard all of the transmission data CDMU-2 and CDMU-3 stored in its transmit buffer. If AP2 fails to receive any ACK frames, it will begin retransmitting the corresponding data.

[0065] Although omitted in Figures 2 and 4, it is also conceivable that the M-AP operates a wireless network with one or more communication terminals under its control, and, similar to AP1 and AP2, can spatially multiplex the data to be transmitted in coordination with data destined for other communication terminals.

[0066] Figure 5 shows an example of a communication sequence used to verify the operation of coordinating data transmission by multiple access points.

[0067] However, Figure 5 assumes that, as in the wireless network shown in Figure 1, an access point AP1 that actively performs cooperative transmission, an access point AP2 that passively performs cooperative transmission, communication terminals STA1 and STA3 belonging to AP1's network, and communication terminal STA2 belonging to AP2's network are all in operation.

[0068] First, STA1 sends an Association Request to AP1 (SEQ501). Then, if AP1 allows STA1 to associate with its network, it sends an Association Response back to STA1 (SEQ502).

[0069] Similarly, STA2 sends an association request to AP2 (SEQ503). Then, if AP2 allows STA2 to associate with its network, it sends an association response back to STA2 (SEQ504).

[0070] Furthermore, STA3 sends an association request to AP1 (SEQ505). If AP1 allows STA3 to associate with its network, it sends an association response back to STA3 (SEQ506).

[0071] Here, each communication terminal STA1, STA2, and STA3 exchanges information with access point AP1 or AP2 during the association procedure described above, including a Coordinate Transmit Information Element that contains the spatial division multiplexing parameters it can receive. This Coordinate Transmit Information Element includes the number of transmit multiplexing and receive multiplexing devices (described later). Therefore, AP1 can determine the number of spatial multiplexing streams that its subordinate STA1 and STA3 can each receive. Similarly, AP2 can determine the number of spatial multiplexing streams that its subordinate STA2 can receive.

[0072] Furthermore, when AP1 and AP2 determine, for example, that they are in a location where they can communicate with each other, they exchange Coordinate Requests and Coordinate Responses (SEQ507, SEQ508), which consist of Coordinate Transmission Information Elements, to determine that they can coordinately transmit communications to communication terminals whose presence can be detected by both access points. In addition, AP1 can determine the number of spatial multiplexed streams in AP2's wireless network, and AP2 can determine the number of spatial multiplexed streams that STA1 and STA3 can receive in AP1's wireless network.

[0073] Figure 6 shows another example of a communication sequence used to verify the operation of coordinating data transmission by multiple access points.

[0074] However, Figure 6 assumes that, as in the wireless network shown in Figure 2, a master AP access point (M-AP) manages cooperative transmission, access points AP1 and AP2 passively perform cooperative transmission, communication terminals STA1 and STA3 belonging to AP1's network, and communication terminal STA2 belonging to AP2's network are all operating.

[0075] First, STA1 sends an association request to AP1 (SEQ601). If AP1 allows STA1 to associate with its network, it sends an association response back to STA1 (SEQ602). Similarly, STA2 sends an association request to AP2 (SEQ603). If AP2 allows STA2 to associate with its network, it sends an association response back to STA2 (SEQ604). Furthermore, STA3 sends an association request to AP1 (SEQ605). If AP1 allows STA3 to associate with its network, it sends an association response back to STA3 (SEQ606).

[0076] Here, each communication terminal STA1, STA2, and STA3 exchanges information including a cooperative transmission information element that describes the spatial division multiplexing parameters it can receive when performing the association procedure described above with access point AP1 or AP2. Therefore, AP1 can determine the number of spatial multiplexing streams that its subordinate STA1 and STA3 can each receive. Similarly, AP2 can determine the number of spatial multiplexing streams that its subordinate STA2 can receive.

[0077] Furthermore, when the M-AP detects that AP1 is located in a position where it can communicate with AP2, it exchanges a Coordinate Request and a Coordinate Response, both consisting of Coordinate Transmission Information elements (SEQ607, SEQ608). Similarly, when the M-AP detects that AP2 is located in a position where it can communicate with AP2, it exchanges a Coordinate Request and a Coordinate Response, both consisting of Coordinate Transmission Information elements (SEQ609, SEQ610). This allows the M-AP to understand that it is possible to coordinate transmission communications to communication terminals whose presence can be detected at both AP1 and AP2 access points. The M-AP can also determine the number of spatially multiplexed streams in each of the wireless networks of AP1 and AP2.

[0078] Figure 7 shows an example of the configuration of an association frame. However, the association frame referred to here includes both an association request frame and an association response frame. Furthermore, fields that are particularly distinctive in this embodiment are highlighted in gray.

[0079] The illustrated association frame is structured as a management frame in the MAC (Media Access Control) layer, following a PLCP (Physical Layer Convergence Protocol) header as a preamble in a given PHY layer. That is, it includes fields such as Frame Control (indicating the frame type), Duration (indicating the frame duration), Receive Address (indicating the recipient address), and Transmit Address (indicating the sender address), as per the conventional association frame structure. Following these conventional fields, a Coordinate Transmit Information Element is included, and at the end, a Frame Check Sequence (FCS), calculated from the entire frame according to a predetermined calculation procedure, is appended. The structure of the Coordinate Transmit Information Element will be described later (see Figure 8).

[0080] Figure 8 shows an example of the configuration of a coordination frame. Here, the coordination frame includes both a coordination request frame and a coordination response frame. Furthermore, fields that are particularly distinctive in this embodiment are highlighted in gray.

[0081] The illustrated coordinate frame is structured as a management frame in the MAC layer, following a PLCP header as a preamble in a given PHY layer. Specifically, it includes fields such as Frame Control, which indicates the type of frame; Duration, which indicates the duration of the frame; Receive Address, which indicates the destination address; and Transmit Address, which indicates the source address. Following these fields are AP Attribute, which indicates the attributes of the access point, and Coordinate Transmit Information Element, with a Frame Check Sequence (FCS) appended at the end.

[0082] A co-transmission information element includes parameters such as Element Type, which indicates the format of the information element; Length, which indicates the information length; Available MCS, which indicates the available modulation and encoding schemes; Timing Parameter, which indicates the transmission timing parameters; and A-MPDU (Aggregation MPDU) Counts, which indicates the number of MPDUs (MAC Protocol Data Inits) to be aggregated.

[0083] Furthermore, the co-transmission information element includes parameters such as the transmit multiplexing number Tx MIMO and the receive multiplexing number Rx MIMO, as spatial division multiplexing parameters.

[0084] Furthermore, the co-transmission information element also includes frequency parameters such as Bands, which indicate the available bandwidth, and Channels, which indicate the number of available channels.

[0085] Furthermore, the cooperative transmission information element within the cooperative frame may be set with various parameters other than those shown in Figure 8, as needed.

[0086] Figure 9 shows an example of the configuration of an initiate frame. However, fields that are particularly distinctive in this embodiment are filled in gray. The initiate frame is used by access points that actively perform coordinated transmission, or by master access points that manage coordinated transmission, when initiating data sharing for coordinated transmission to communication terminals (see, for example, Figures 3 and 4).

[0087] The illustrated initiator frame is configured as a control frame in the MAC layer, following a PLCP header as a preamble in a given PHY layer. That is, as a conventional control frame structure, it includes fields such as Frame Control indicating the type of frame, Duration indicating the duration of the frame, Target AP Address1 indicating the address of the target access point, and AP MAC Address indicating the address of the source access point, and optionally includes Target AP Address2 indicating the address of a second target access point.

[0088] The target access points referred to here are those designated as partners for coordinated transmission by access points that actively perform coordinated transmission or by the master access point that manages coordinated transmission. Basically, target access points are those that passively perform coordinated transmission. The second target access point is, for example, the second target access point designated by the master access point. Following the examples shown in Figures 2 and 4, it is assumed that the M-AP designates AP1 as the first target access point and AP2 as the second target access point. Furthermore, when coordinating transmission is performed using three or more access points, the initiate frame will contain fields for storing the Target AP Address3, ... indicating the address of the third target access point.

[0089] Following these fields, the data includes further parameters such as Coorinate Tx Timing, which indicates the timing of coordinated transmission; Coordinate MCS Info, which indicates the modulation scheme and coding rate used during coordinated transmission; and Coordinate Channels, which indicates the channels used for coordinated transmission. Finally, a frame check sequence (FCS) is appended to the end.

[0090] Figure 10 shows an example of a grant frame configuration. However, fields that are particularly distinctive in this embodiment are highlighted in gray. Grant frames are used by access points that passively perform cooperative transmission to confirm receipt of shared data (see, for example, Figures 3 and 4).

[0091] The illustrated grant frame is structured as a control frame in the MAC layer, following a PLCP header as a preamble in a given PHY layer. That is, as a conventional control frame structure, it includes fields such as Frame Control indicating the type of frame, Duration indicating the duration of the frame, Receive Address indicating the recipient's address, and Transmit Address indicating the source address. Following these fields, it further includes parameters such as Target Address indicating the communication terminal to be transmitted in coordinate, Coordinate Multiplex (number of coordinate multiplex transmissions), Coordinate Parameter (parameters used in coordinate transmission), and BA Control and BA Information, which are block ACK information of the frame received as shared data, and a Frame Check Sequence (FCS) is appended to the end. The Coordinate Parameter contains various communication parameters such as MCS, transmit power, and guard interval length used in coordinate transmission.

[0092] Please note that by including information about the communication terminal that will be the receiving target for coordinated transmission in the grant frame, and specifying the communication terminal that will receive the coordinated transmission data, it is possible to make that receiving terminal aware in advance that coordinated transmission will be performed.

[0093] Figure 11 shows an example of the trigger frame configuration. However, fields that are particularly distinctive in this embodiment are filled in gray. The trigger frame is used by access points that actively perform coordinated transmission, or by master access points that manage coordinated transmission, to time the coordinated transmission precisely (in microseconds) with access points that passively perform coordinated transmission (see, for example, Figures 3 and 4).

[0094] The illustrated trigger frame is configured as a control frame in the MAC layer, following a PLCP header which serves as a preamble in a given PHY layer. That is, it includes fields such as Frame Control, which indicates the type of frame; Duration, which indicates the duration of the frame; Receive Address, which indicates the address of the recipient; and Transmit Address, which indicates the address of the sender, as per the conventional control frame structure. Following these fields, Common Information, which is common to all recipients, and User Information, which is necessary for each user (each receiving communication device), are added as needed, and a Frame Check Sequence (FCS) is added at the end.

[0095] Common Information includes bits for Coordinate Transmit, which indicates that coordinated transmission will be performed, and Coordinate Multiplex, which indicates that the communication is multiplexed along with the coordinated transmission.

[0096] Furthermore, User Information, which is information necessary for each user, includes Coordinate Parameters, which are transmission parameters specific to each user required when performing coordinated transmission. Coordinate Parameters include various communication parameters used during coordinated transmission, such as MCS, transmission power, and guard interval length.

[0097] Figure 12 shows the internal structure of the data frame. The data frame shown is assumed to be composed of an A-MPDU frame, which is an aggregate of multiple subframes (MPDUs).

[0098] The preamble of the illustrated data frame consists of the following groups: L (Legacy)-STF (Short Training Field), L-LTF (Long Training Field), L-SIG, RL-SIG (Repeated L-SIG), HE (High Efficiency)-SIG-A, HE-SIG-B, HE-STF, and HE-LTF. STF is used, for example, for coarse synchronization acquisition, while LTF is used, for example, for detailed synchronization acquisition and channel estimation. In addition, each SIG field contains signaling information corresponding to its respective standard.

[0099] A distinctive feature of the HE-SIG-A parameter included in the preamble is the presence of a Coordinate Transmit bit, which identifies that coordinated transmission is being performed. Based on this bit, the receiving communication device of the data frame can identify that the same MPDU is included in other spatially multiplexed A-MPDUs (i.e., that the same MPDU is being transmitted coordinately from multiple sources).

[0100] Furthermore, the HE-SIG-B parameters included in the preamble contain a Coordinate Parameter, which lists the parameters for performing coordinated transmission. The Coordinate Parameter lists various communication parameters used during coordinated transmission, such as MCS, transmit power, and guard interval length.

[0101] Furthermore, in the example shown in Figure 12, eight MPDUs (subframes), from MPDU-1 to MPDU-8, are aggregated to form an A-MPDU, and EOF (End of Frame) padding is added as needed. However, the number of aggregated subframes is not limited to eight; it may be seven or fewer, or nine or more.

[0102] Each MPDU, which is configured as a subframe of the A-MPDU frame, is given a predetermined delimiter and, if necessary, trailing padding.

[0103] Each MPDU consists of a predetermined MAC header and data payload, and a frame check sequence (FCS) calculated according to a predetermined calculation procedure is appended to the end of each MPDU.

[0104] The MAC header consists of the following fields: Frame Control, which indicates the format of the frame; Duration, which indicates the duration of the frame; Address1 to Address4, which appropriately specify the transmitting and receiving devices; Sequence Control, which stores sequence numbers and other information; QoS Control, which contains QoS (Quality of Service) parameters; and HT (High Throughput) Control, which contains high-speed transmission parameters.

[0105] Figures 13 to 19 show examples of data frame configurations applicable to data sharing and collaborative transmission. In each figure, the horizontal axis represents time.

[0106] Figure 13 shows an example of a frame configuration used when sharing data between access points using multiple spatially multiplexed streams. According to the illustrated frame configuration, when sharing data from MPDU-1 to MPDU-4, each MPDU can be configured as a different spatially multiplexed stream SD1 to SD4 and transmitted via multiplexing, allowing for data sharing in a shorter time.

[0107] For example, in the wireless network configuration shown in Figure 1, by transmitting the data frame shown in Figure 13 from AP1, which actively performs cooperative transmission, to AP2, which passively performs cooperative transmission, the sharing of cooperative transmission data from MPDU-1 to MPDU-4 between AP1 and AP2 can be achieved in a short time. Furthermore, by using a high-speed transmission-capable MCS, the time required for data sharing can be further reduced.

[0108] Figure 14 shows the data structure transmitted from access point AP1 in the wireless network shown in Figure 1. Here, data that AP1 transmits in coordination to its subordinate communication terminal STA3 (MPDU-1 to MPDU-4) is configured as the first spatial multiplexed stream SD1, and data destined for other subordinate communication terminals STA1 (MPDU-1 to MPDU-6) is configured as the second spatial multiplexed stream SD2. When the data lengths do not match between spatial multiplexed streams, padding is applied to the shorter spatial multiplexed stream to equalize the data lengths. In the example shown in Figure 14, SD2 padding is applied. However, the data structure shown in Figure 14 assumes that STA1, the receiving destination, can receive 1 spatial multiplexed stream, and STA3 can receive 2 or more spatial multiplexed streams.

[0109] Figure 15 shows the data structure transmitted from access point AP2 in the wireless network shown in Figure 1. Here, data that AP2 transmits in coordination to communication terminal STA3 belonging to another wireless network (MPDU-1 to MPDU-4) is configured as the first spatial multiplexed stream SD3, and data destined for other communication terminals under its control, STA2 (MPDU-1 to MPDU-8), is configured as the second spatial multiplexed stream SD4. When the data lengths do not match between spatial multiplexed streams, padding is applied to the shorter spatial multiplexed stream to equalize the data lengths. In the example shown in Figure 15, padding is applied to SD4. However, the data structure shown in Figure 15 assumes that STA2 can receive 1 spatial multiplexed stream, and STA3 can receive 2 or more spatial multiplexed streams.

[0110] Figure 16 shows an example of a data frame configuration for sending shared data from a master access point (M-AP) to multiple access points. Here, in the wireless network shown in Figure 2, an example is shown in which four spatially multiplexed streams SD1 to SD4 are configured as frames to be sent from the M-AP to each access point AP1 and AP2.

[0111] First, the data that AP1 and AP2 will transmit in coordination to STA3 (MPDU-1 to MPDU-4) is configured as the first spatial multiplexed stream SD1. The data that AP1 will send to another communication terminal STA1 (MPDU-1 to MPDU-6) is then configured as the second spatial multiplexed stream SD2. Furthermore, the data that AP2 will send to another communication terminal STA2 (MPDU-1 to MPDU-8) is configured as the third spatial multiplexed stream SD3. Finally, the data addressed to AP2 (MPDU-1 to MPDU-7) is configured as the fourth spatial multiplexed stream SD4. When the data lengths do not match between spatial multiplexed streams, padding is applied to the shorter spatial multiplexed stream to equalize the data lengths. In the example shown in Figure 16, padding is applied to SD2, SD3, and SD4.

[0112] By transmitting the data frame shown in Figure 16, the sharing of cooperative transmission data from MPDU-1 to MPDU-4 between AP1 and AP2 can be achieved in a short time, and data that AP1 and AP2 each intend to send to other communication terminals can also be sent at the same time. Furthermore, by using a high-speed transmission MCS, the time required for data sharing can be further reduced.

[0113] Figure 17 shows another example of a data frame configuration for sending shared data from a master access point (M-AP) to multiple access points. Here, in the wireless network shown in Figure 2, an example is shown in which eight spatial multiplexed streams SD1 to SD8 are configured as frames to be sent from the M-AP to each access point AP1 and AP2.

[0114] First, the data that AP1 and AP2 transmit in coordination to STA3 (MPDU-1 to MPDU-4) is configured as the first spatial multiplexed stream SD1. A portion of the data that AP1 transmits to the communication terminal STA1 (MPDU-1 to MPDU-4) is then configured as the second spatial multiplexed stream SD2, and the remaining portion of the data that AP1 transmits to STA1 (MPDU-5 to MPDU-6) is then configured as the third spatial multiplexed stream SD3.

[0115] Furthermore, a portion of the data that AP2 sends to another communication terminal STA2 (MPDU-1 to MPDU-4) is configured as a fourth spatial multiplexed stream SD4, and the remaining portion of the data that AP2 sends to STA2 (MPDU-5 to MPDU-8) is configured as a fifth spatial multiplexed stream SD5.

[0116] Furthermore, a portion of the data destined for AP2 (MPDU-1 to MPDU-4) is configured as a sixth spatial multiplexed stream, SD6, and the remaining portion of the data destined for AP2 (MPDU-5 to MPDU-7) is configured as a seventh spatial multiplexed stream, SD7.

[0117] Furthermore, in order to improve the reliability of the data (MPDU-1 to MPDU-4) that AP1 and AP2 transmit in coordination to STA3, the eighth spatial multiplexed stream, SD8, is also configured as the same data as SD1.

[0118] By transmitting the data frame shown in Figure 17, the sharing of cooperative transmission data from MPDU-1 to MPDU-4 between AP1 and AP2 can be achieved in a short time, and data that AP1 and AP2 each intend to send to other communication terminals can also be sent at the same time. Furthermore, by using a high-speed transmission MCS, the time required for data sharing can be further reduced.

[0119] Figure 18 shows an example of the data frame structure transmitted from access point AP1 in the wireless network shown in Figure 2.

[0120] In this diagram, the data (MPDU-1 to MPDU-4) that AP1 transmits in coordination to its subordinate communication terminal STA3 is configured as the first spatial multiplexed stream SD1. In addition, the data (MPDU-1 to MPDU-6) destined for other subordinate communication terminals STA1 is configured as the second spatial multiplexed stream SD2.

[0121] Furthermore, in order to improve the reliability of the data (MPDU-1 to MPDU-4) that is transmitted in coordination to STA3, a third spatial multiplexed stream, SD3, is configured with the same data as the first spatial multiplexed stream, SD1.

[0122] Furthermore, in order to improve the reliability of the data (MPDU-1 to MPDU-6) transmitted multiplexed to STA1, a fourth spatial multiplexed stream, SD4, is configured with the same data as the second spatial multiplexed stream, SD2.

[0123] When the data lengths do not match between spatially multiplexed streams, padding is applied to the shorter spatially multiplexed stream to equalize the data lengths. In the example shown in Figure 18, padding is applied to both SD2 and SD4. However, the data configuration shown in Figure 18 assumes that STA1, the receiving device, can receive 2 or more spatially multiplexed streams, and STA3 can receive 4 or more spatially multiplexed streams.

[0124] Figure 19 shows an example of the data frame structure transmitted from access point AP2 in the wireless network shown in Figure 2.

[0125] In this diagram, the data (MPDU-1 to MPDU-4) to be transmitted in coordination to the communication terminal STA3 belonging to another wireless network is configured as the first spatial multiplexed stream SD1. In addition to this, the data (MPDU-1 to MPDU-8) to the subordinate communication terminal STA2 is configured as the third spatial multiplexed stream SD3.

[0126] Furthermore, in order to improve the reliability of the data (MPDU-1 to MPDU-4) that is transmitted in coordination to STA3, a second spatial multiplexed stream, SD2, is configured as the same data as the first spatial multiplexed stream, SD1.

[0127] Furthermore, in order to improve the reliability of the data (MPDU-1 to MPDU-8) transmitted multiplexed to STA2, a fourth spatial multiplexed stream, SD4, is configured with the same data as the third spatial multiplexed stream, SD3.

[0128] When the data lengths do not match between spatially multiplexed streams, padding is applied to the shorter spatially multiplexed stream to equalize the data lengths. In the example shown in Figure 19, padding is applied to both SD3 and SD4. However, the data configuration shown in Figure 19 assumes that STA2, the receiving device, can receive 2 or more spatially multiplexed streams, and STA3 can receive 4 or more spatially multiplexed streams.

[0129] Figure 20 schematically shows an example of the functional configuration of a communication device 2000 that can operate as a communication terminal and an access point. The illustrated communication device 2000 includes an internet connection module 2001, an information input module 2002, an equipment control unit 2003, an information output module 2004, and a wireless communication module 2005. However, the communication device 2000 can be configured to consist only of the modules necessary to operate as a communication terminal or access point, with unnecessary modules being simplified or omitted, or conversely, the communication device 2000 can be configured by further incorporating other functional modules not shown.

[0130] The Internet connection module 2001 implements functions such as a communication modem for connecting to the Internet network, for example, when the communication device 2000 operates as an access point, and realizes Internet connectivity via a public communication line and an Internet service provider.

[0131] The information input module 2002 is a functional module for inputting information that conveys instructions from the user, and is composed of, for example, push buttons, a keyboard, or a touch panel.

[0132] The device control unit 2003 is a functional module that controls the communication device 2000 to operate as a communication terminal or access point as intended by the user.

[0133] The information output module 2004 is a functional module that presents the user with the operating status of the communication device 2000 and information obtained via the Internet. The information output module 2004 is composed of devices such as display elements like LEDs (Light Emitting Diodes), liquid crystal panels, and organic EL (Electro-Luminescence) displays, as well as speakers that output sound and music. The information output module 2004 is configured to display or notify the user of information being processed or processed by the device control unit 2003.

[0134] The wireless communication module 2005 is a functional module in the communication device 2000 that processes wireless communication, and is composed of a processor and circuits such as a microprocessor. Wireless communication as used herein includes operating as an access point that actively or passively performs coordinated transmission, or as a master access point that manages coordinated transmission, to share data between access points and to perform coordinated transmission of data to communication terminals. Details of the wireless communication operation will be described later.

[0135] Figure 21 shows an example of the internal configuration of the wireless communication module 2005 within the communication device 2000 shown in Figure 20. The illustrated wireless communication module 2005 includes an interface 2101, a transmit buffer 2102, a network management unit 2103, a transmit frame construction unit 2104, a receive data construction unit 2105, a receive buffer 2106, a cooperative communication management unit 2107, a spatial multiplex transmission processing unit 2108, a spatial multiplex reception processing unit 2109, a management information generation unit 2110, a management information processing unit 2111, a wireless transmission processing unit 2112, a transmit power control unit 2113, a transmit / receive antenna control unit 2114, a detection threshold control unit 2115, and a wireless reception processing unit 2116.

[0136] Here, interface 2101, transmit buffer 2102, network management unit 2103, transmit frame construction unit 2104, receive data construction unit 2105, and receive buffer 2106 are configured as parts common to the software in a wireless LAN system based on standards such as IEEE802.11. In addition, the wireless transmission processing unit 2112, transmit power control unit 2113, transmit / receive antenna control unit 2114, detection threshold control unit 2115, and wireless reception processing unit 2116 are configured as parts common to the baseband processing in a wireless LAN system.

[0137] Interface 2101 is a functional module for exchanging user input, data from the Internet network, and information to the user in a predetermined signal format.

[0138] The transmit buffer 2102 is a functional module for temporarily storing user input and signals to be transmitted wirelessly when received from the interface 2101.

[0139] The network management unit 2103 is a functional module that manages address information and other data for communication devices included in the wireless network. When the communication device 2000 is operating as an access point, the network management unit 2103 manages the address information of communication devices (such as communication terminals) connected to its own station. When the communication device 2000 is operating as a communication terminal, the network management unit 2103 manages the address information of the access point to which it will connect.

[0140] In this embodiment, the access point is configured to be aware of the presence of other access points in its vicinity and to cooperate with those other access points as needed. Therefore, when the communication device 2000 is operating as an access point, the network management unit 2103 is configured to also manage information on other access points in its vicinity as needed.

[0141] The transmission frame construction unit 2104 is a functional module for constructing wireless transmission data as a data frame for wireless transmission. The transmission frame construction unit 2104 also collects multiple MPDUs stored in the transmission buffer 2102 and constructs an A-MPDU.

[0142] The received data construction unit 2105 is a functional module for reconstructing the original data from a wirelessly received data frame. For example, when an A-MPDU is received, the received data construction unit 2105 removes predetermined header information from the A-MPDU data frame, extracts the MPDU, and extracts only the necessary data portion.

[0143] The receive buffer 2106 is a functional module that temporarily stores the data portion extracted by the received data construction unit 2105 based on its sequence number until all data frames are available. The receive buffer 2106 is configured to store the received data until the time comes to output the data to an application device (not shown) connected via interface 2101.

[0144] When the communication device 2000 is operating as an access point, the cooperative communication management unit 2107 recognizes the presence of other access points in the vicinity, determines whether or not to perform cooperative transmission operations with those other access points, and sets parameters, etc.

[0145] Specifically, when the communication device 2000 operates as an access point that actively performs coordinated transmission (or a master access point that manages coordinated transmission), the coordinated communication management unit 2107 controls the transmission of an initiate frame (see Figure 9) during the initiation of data sharing for coordinated transmission, and the transmission of a trigger frame (see Figure 11) to other access points that passively perform coordinated transmission.

[0146] Furthermore, when the communication device 2000 operates as an access point that passively performs cooperative transmission, the cooperative communication management unit 2107 controls the reception of initiator frames from other access points and the transmission of grant frames (see Figure 10) when confirming receipt of shared data.

[0147] On the other hand, when the communication device 2000 is connected to the wireless network of any access point as a communication terminal, the cooperative communication management unit 2107 performs various settings within the wireless communication module 2005 for receiving data transmitted cooperatively from multiple surrounding access points.

[0148] The spatial multiplexing transmission processing unit 2108 is a functional module that sets the number of spatial multiplexers and various parameters necessary for transmitting spatial multiplexed streams, which are required for simultaneous transmission of multiple spatial multiplexed streams.

[0149] For example, when the communication device 2000 performs coordinated transmission as an access point, the spatial multiplex transmission processing unit 2108 sets up the spatial multiplex streams for coordinated transmission and, when multiplexing and transmitting data destined for a communication terminal, sets the necessary parameters each time. Specifically, the spatial multiplex transmission processing unit 2108 synchronizes the timing of coordinated transmission with adjacent access points and performs control to ensure that the necessary parameters are matched during transmission.

[0150] The spatial multiplexing reception processing unit 2109 is a functional module that sets the number of spatial multiplexing streams and various parameters necessary for receiving spatial multiplexing streams, which are required for simultaneously receiving multiple spatial multiplexing streams. Specifically, the spatial multiplexing reception processing unit 2109 controls the extraction of spatial multiplexing streams that it needs to receive from among spatial multiplexing frames sent from one or more surrounding access points.

[0151] Furthermore, in a wireless network environment where data sharing and coordinated transmission are performed by multiple access points, the spatial multiplexing receiving processing unit 2109 recognizes that the same data is being transmitted from different access points and, if necessary, performs control to combine these received data to construct the received data.

[0152] The management information generation unit 2110 is a functional module that constructs beacon signals necessary for network management, as well as control frames and management frames necessary for communication control protocols. In this embodiment, when the communication device 2000 operates as an access point, the management information generation unit 2110 generates initiate frames, grant frames, block ACK request frames, etc. On the other hand, when the communication device 2000 operates as a communication terminal, the management information generation unit 2110 generates ACK frames.

[0153] The Management Information Processing Unit 2111 is a functional module that constructs the control information necessary for the communication control protocol when the received frame is a control frame or a management frame. If the received frame is a beacon frame, the Management Information Processing Unit 2111 passes the parameters described in the beacon frame to the Cooperative Communication Management Unit 2107 or the Network Management Unit 2103 to determine the access point parameters. If the received frame is an initiate frame or a grant frame, the Management Information Processing Unit 2111 notifies the Cooperative Communication Management Unit 2107 of the parameters and performs the necessary subsequent processing depending on whether the communication device 2000 is operating as an access point or a communication terminal.

[0154] The wireless transmission processing unit 2112 is a functional module that adds a predetermined preamble to frames such as data frames to be transmitted wirelessly on a predetermined frequency channel, converts them into a predetermined baseband signal, and processes them as an analog signal. In Figure 21, the wireless transmission processing unit 2112 is depicted as a single functional module, but when dealing with multiple spatially multiplexed streams, a configuration in which multiple elements operate in parallel to transmit each stream simultaneously is also possible. Alternatively, a configuration in which signals from different spatially multiplexed streams are supplied to the transmitting antenna from multiple wireless transmission processing units.

[0155] The transmit power control unit 2113 is a functional module that controls the transmit power so that the signal does not reach an unnecessary range when transmitting a predetermined frame. In this embodiment, the transmit power control unit 2113 is configured to control data transmission by adjusting the transmit power to the minimum necessary level so that the signal reaches the receiving side with the intended received field strength.

[0156] The transmitting and receiving antenna control unit 2114 has multiple antenna elements connected to it and performs control for wirelessly transmitting signals as spatially multiplexed streams, and processing for receiving these signals transmitted as spatially multiplexed streams.

[0157] The detection threshold control unit 2115 is a functional module that, when transmission power control is implemented, sets a signal detection level that allows detection of signals from communication devices within the radio wave range, and controls the system to detect signals at the minimum necessary detection threshold. The detection threshold control unit 2115 is configured to detect signals above a predetermined detection level if the channel is currently in use.

[0158] The wireless reception processing unit 2116 is a functional module that, upon detecting a predetermined preamble signal, separates the individual spatially multiplexed streams and performs reception processing for the header and data portions added after the preamble. In Figure 21, the wireless reception processing unit 2116 is depicted as a single functional module, but when dealing with multiple spatially multiplexed streams, a configuration in which multiple elements operate in parallel to receive each stream simultaneously is also possible.

[0159] When the communication device 2000 is configured as an access point, it supports spatial multiplexing, as can be seen from the configuration within the wireless communication module 2005 shown in Figure 21. On the other hand, when the communication device 2000 is configured as a communication terminal, it is preferable, but not required, that it supports spatial multiplexing.

[0160] Figure 22 shows a flowchart illustrating the process by which an access point registers a communication terminal. The illustrated process is assumed to be performed by a communication device 2000 operating as an access point.

[0161] When an access point receives an association request frame (see Figure 7) from an existing (already connected to) communication terminal or a new (not connected to) communication terminal (Yes in step S2201), it obtains the parameters of that communication terminal (step S2202) and checks whether that communication terminal can receive data transmitted collaboratively from multiple access points, for example, based on the contents of the collaborative transmission information element (step S2203).

[0162] If the communication terminal requesting association supports receiving data transmitted in coordination (cooperative reception) (Yes in step S2203), the access point registers that communication terminal as a cooperative reception-compatible terminal (step S2204) and terminates this process.

[0163] On the other hand, if the communication terminal requesting association does not support receiving data that is transmitted in coordination (cooperative reception) (No in step S2203), the access point further checks whether the communication terminal supports receiving spatial multiplexed streams (multiplex reception) (step S2205).

[0164] If the communication terminal requesting association supports reception of spatial multiplexed streams (Yes in step S2205), the access point registers the communication terminal as a multiplexed reception-compatible terminal (step S2206) and terminates this process. If the communication terminal requesting association does not support reception of spatial multiplexed streams (No in step S2205), the access point registers the communication terminal as a multiplexed reception-incompatible terminal (step S2207) and terminates this process.

[0165] Figure 23 shows a flowchart illustrating the procedure for an access point to register an adjacent access point. The illustrated procedure is assumed to be performed by a communication device 2000 operating as an access point (an access point that actively performs coordinated transmission, or a master access point that manages coordinated transmission).

[0166] If an access point receives a signal (OBSS signal) from an overlapping BSS (Basic Service Set) (Yes in step S2301), it obtains the operating parameters of the adjacent access point from the received signal (step S2302). An OBSS signal is assumed to be, for example, an association response frame transmitted by a communication terminal (see Figure 7), and the operating parameters of the adjacent access point can be obtained based on the contents of the cooperative transmission information element.

[0167] Next, the access point checks whether the adjacent access point supports cooperative transmission based on the contents of the cooperative transmission information element (step S2303).

[0168] If the adjacent access point supports coordinated transmission (Yes in step S2303), the access point registers that adjacent access point as a coordinated transmission-compatible access point (step S2304) and terminates this process. If the adjacent access point does not support coordinated transmission (No in step S2303), the access point terminates this process without registering that adjacent access point.

[0169] The above-mentioned registration process for cooperative transmission-enabled access points may be performed at all access points, or it may be permitted to perform the registration process only at access points that actively perform cooperative transmission or at master access points that manage cooperative transmission, while access points that passively perform cooperative transmission do not.

[0170] Figure 24 shows a flowchart illustrating the processing procedure when an access point receives transmitted data. The illustrated processing procedure is assumed to be performed by a communication device 2000 operating as an access point.

[0171] When the access point receives transmission data via interface 2001 (Yes in step S2401), it obtains the address information of the communication device that will receive the transmission data (step S2402), and further obtains the association information of the communication device (communication terminal) that will receive the data (step S2403).

[0172] Next, the access point checks whether spatial multiplexing of the data to be transmitted is possible (step S2404). Whether spatial multiplexing is possible is determined by whether the access point itself supports spatial multiplexing, as well as whether the receiving communication device supports spatial multiplexing. If spatial multiplexing is possible on both sides, the configuration determines the allowable (maximum) number of spatial multiplexed streams based on the number of multiplexed streams that each of the access point and the receiving communication device can handle.

[0173] Then, if spatial multiplexing is possible (Yes in step S2404), the access point obtains the connection status with the overlapping BSS (OBSS) access point (step S2405) and further checks whether coordinated transmission with that OBSS AP is possible (step S2406).

[0174] In step S2406, the case in which coordinated transmission can be performed is specifically when the access point itself has the capability to perform coordinated transmission, and when there is an OBSS AP that has already been registered as a coordinated transmission-compatible access point in accordance with the processing procedure shown in Figure 23.

[0175] If coordinated transmission with the OBSS AP is possible (Yes in step S2406), the access point sets the transmission data received in step S2401 to be capable of coordinated spatial multiplexing transmission between access points (step S2407). On the other hand, if coordinated transmission with the OBSS AP is not possible (No in step S2406), the access point sets the transmission data to be capable of independent spatial multiplexing transmission (step S2408).

[0176] Furthermore, if spatial multiplexing is not possible (No. in step S2404), the access point sets the transmission data received in step S2401 to be transmittable as not compatible with spatial multiplexing (step S2409).

[0177] Then, the access point stores the data destined for the communication device for which address information was obtained in step S2402, along with the possibility of transmission (whether cooperative transmission is possible, single spatial multiplexing is possible, or single non-multiplexing is possible), in the transmission buffer (step S2410), and terminates this process.

[0178] Figure 25 shows a flowchart illustrating the processing procedure for an access point to actively perform coordinated transmission. The illustrated processing procedure is assumed to be performed by a communication device 2000 operating as an access point.

[0179] The access point checks whether it is possible to perform coordinated transmission when there is data to be transmitted and the transmission timing has arrived (Yes in step S2501) (step S2502).

[0180] In step S2501, the case where there is data to be transmitted is, for example, when the data to be transmitted has been received according to the processing procedure shown in Figure 24 and stored in the transmission buffer 2102. Furthermore, in step S2502, the case where coordinated transmission can be performed is, specifically, when the access point itself has the capability to perform coordinated transmission and there are already registered coordinated transmission-compatible access points according to the processing procedure shown in Figure 23 or the like.

[0181] If coordinated transmission is possible (Yes in step S2502), the access point sends an initiate frame (see Figure 9) to an adjacent access point that supports coordinated transmission (step S2503), then sends shared data for coordinated transmission (step S2504), and then waits for a grant frame (see Figure 10) from the access point to which the initiate frame was sent (step S2505). In step S2503, the adjacent access point that supports coordinated transmission is, for example, an access point registered as a coordinated transmission-compatible access point according to the processing procedure shown in Figure 23. In step S2504, by using a high-speed transmission-capable MCS, data sharing between access points can be achieved in a short time.

[0182] Furthermore, if coordinated transmission cannot be performed (No. in step S2502), or if a grant frame cannot be received from an adjacent coordinated transmission-compatible access point (No. in step S2505), the access point checks whether multiplex transmission of data is possible (step S2506).

[0183] In step S2506, whether multiplex transmission is possible is determined by whether the access point itself supports multiplex transmission, as well as whether the receiving communication device supports multiplex transmission. If multiplex transmission is possible on both sides, the configuration determines the allowable (maximum) number of multiplex streams based on the number of multiplex streams that each of the access point and the receiving communication device can handle.

[0184] Then, if the access point receives a grant frame from the access point to which the initiate frame was sent and can confirm receipt of the shared data (Yes in step S2505), or if it could not receive a grant frame but data multiplexing is possible (Yes in step S2506), the access point further checks whether it can perform spatial multiplexing transmission within the access point (step S2507). Specifically in step S2507, the access point checks whether there is a communication terminal that supports spatial multiplexing transmission within its network and whether there is data addressed to that communication terminal.

[0185] If spatial multiplexing can be performed within the access point (Yes in step S2507), the access point acquires other spatial multiplexed data (step S2508). That is, the access point acquires data destined for its subordinate communication terminals to be transmitted simultaneously with the coordinated transmission of shared data via spatial multiplexing.

[0186] Next, the access point sends a trigger frame to an adjacent co-transmission-enabled access point to perform downlink multi-user space multiplexing (DL MU-MIMO) (step S2509).

[0187] Then, after transmitting the trigger frame, the access point transmits data at a predetermined transmission timing (step S2510). The frame interval between the trigger frame and the spatially multiplexed transmission frame is constant. Therefore, by transmitting the trigger frame in advance, time synchronization in microseconds can be ensured between access points performing coordinated transmission. In addition, in step S2510, the access point can efficiently utilize the wireless transmission path by multiplexing the data to be transmitted in coordination with data destined for other communication terminals (acquired in step S2508) using spatial multiplexing technology.

[0188] Furthermore, if multiplex transmission of data is not possible (No. in step S2506), the access point transmits the data at a predetermined transmission timing without sending a trigger frame (step S2510).

[0189] After transmitting data, the access point sends a block ACK request frame if necessary (step S2511) and waits for the reception of an ACK frame from the data receiver (step S2512).

[0190] Then, upon receiving an ACK frame, if all of the data has been successfully received (Yes in step S2512), the access point discards the transmitted data from the transmit buffer 2101 (step S2513) and terminates this process.

[0191] When an access point coordinates the transmission of shared data, the receiving communication terminal sends back an ACK if it receives the data from any of the access points that performed the coordinated transmission. In any case, if the access point receives an ACK from the receiving communication terminal of the shared data (Yes in step S2512), it discards the shared data from the transmission buffer 2101 (step S2513) and terminates this process.

[0192] On the other hand, if an ACK frame is not received and not all of the data has been received (No. in step S2512), the process returns to step S2502, and the access point performs data retransmission.

[0193] Figure 26 shows a flowchart illustrating the processing procedure for an access point to passively perform coordinated transmission. The illustrated processing procedure is assumed to be performed by a communication device 2000 operating as an access point.

[0194] When an access point that passively performs coordinated transmission receives an initiate frame (see Figure 9) from an adjacent access point (that actively performs coordinated transmission) (Yes in step S2601), it obtains the parameters related to coordinated transmission described in that frame and configures the settings for coordinated transmission (step S2602).

[0195] Furthermore, when an access point receives shared data for coordinated transmission that is sent thereafter (Yes in step S2603), it stores this data in the transmission buffer 2101 as data for coordinated transmission (step S2604). By transmitting shared data using the high-speed transmission-capable MCS from an access point that actively performs coordinated transmission, data sharing between access points can be achieved in a short time.

[0196] Next, if the access point confirms that it supports coordinated transmission or agrees to perform coordinated transmission (Yes in step S2605), it sends a grant frame (see Figure 10) back to the access point that sent the initiate frame (step S2606).

[0197] Next, the access point further checks whether it can perform spatial multiplexing transmission within the access point (step S2607). Specifically in step S2607, the access point checks whether there is a communication terminal that supports spatial multiplexing transmission within its network and whether there is data destined for that communication terminal. It also determines the allowable (maximum) number of multiplexed streams based on the number of multiplexed streams that the access point itself and the receiving communication device can each handle.

[0198] Then, if spatial multiplexing transmission can be performed within the access point (Yes in step S6507), the access point acquires other spatial multiplexed data (step S2608). That is, the access point acquires data destined for its subordinate communication terminals to be transmitted simultaneously with the coordinated transmission of shared data via spatial multiplexing.

[0199] Subsequently, upon receiving a trigger frame for performing downlink multi-user spatial multiplexing transmission, the timing for coordinated transmission arrives (step S2609), and the access point performs data transmission via coordinated transmission (step S2610). The frame interval between the trigger frame and the spatial multiplexing transmission frame is constant. Therefore, by receiving the trigger frame in advance, time synchronization in microseconds can be ensured between the access points performing coordinated transmission. Furthermore, in step S2610, the access point can efficiently utilize the wireless transmission path by multiplexing the data to be transmitted coordinately with data destined for other communication terminals (obtained in step S2608) using spatial multiplexing technology.

[0200] After transmitting data, the access point sends a block ACK request frame if necessary (step S2611) and waits for the reception of an ACK frame from the data receiver (step S2612).

[0201] Then, upon receiving an ACK frame, if all of the data has been successfully received (Yes in step S2612), the access point discards the transmitted data from the transmit buffer 2101 (step S2613) and terminates this process.

[0202] When an access point coordinates the transmission of shared data, the receiving communication terminal sends back an ACK if it receives the data from any of the access points that performed the coordinated transmission. In any case, if the access point receives an ACK from the receiving communication terminal of the shared data (Yes in step S2612), it discards the shared data from the transmission buffer 2101 (step S2613) and terminates this process.

[0203] On the other hand, if an ACK frame is not received and not all of the data has been received (No. in step S2612), the process returns to step S2601, and the access point performs data retransmission.

[0204] Figure 27 shows a flowchart illustrating the processing procedure for a communication terminal to receive coordinated transmission data from multiple access points. The illustrated processing procedure is assumed to be performed by a communication device 2000 operating as a communication terminal under one of the access points.

[0205] If the communication terminal receives a grant frame (see Figure 10) from a nearby access point (Yes in step S2701) and is designated as a receiving target for coordinated transmission data within that grant frame (Yes in step S2702), or if it receives a trigger frame (see Figure 11) from a nearby access point and is designated as a receiving destination within that trigger frame (Yes in step S2704), it obtains the parameter information described in the received grant frame or trigger frame (step S2705).

[0206] The communication terminal then receives and processes the multiplexed data that is sent at a predetermined timing (step S2706). The multiplexed data includes cooperative transmission data for which the terminal itself (or another communication terminal) is designated as the target, and data for which another communication terminal (or the terminal itself) is designated as the recipient.

[0207] It is important to understand that by including information about the communication terminal that will be the receiving target for coordinated transmission in the grant frame, and specifying the communication terminal that will receive the coordinated transmission data, it is possible to make that target terminal aware in advance that coordinated transmission will be performed.

[0208] Furthermore, the frame intervals of the ground frame, trigger frame, and subsequent coordinated transmission data frames are constant. Therefore, by receiving the ground frame and trigger frame in advance, the communication terminal can ensure time synchronization with the access point performing the coordinated transmission. In particular, if the preceding trigger frame is received, time synchronization can be ensured down to the microsecond level.

[0209] If the communication terminal successfully receives the data in step S2706 (step S2707), it records the MPDU sequence number as ACK information (step S2708).

[0210] The communication terminal returns to step S2706 and repeatedly receives the aggregated MPDU until it has received the end of the frame (aggregation frame) (No. in step S2709).

[0211] Then, after the communication terminal has finished receiving the frame to the end (Yes in step S2709), when it receives a predetermined block ACK request (BAR) to which it is instructed to respond (step S2710), it sends back an ACK frame containing the ACK information recorded in step S2708 (step S2711).

[0212] After sending back an ACK frame, if all data has been collected (Yes in step S2712), the communication terminal terminates this process. On the other hand, if not all data has been received (No in step S2712), the process returns to step S2701, and the communication terminal waits for data to be retransmitted.

[0213] Finally, we will summarize the effects and advantages of the technologies proposed in this specification for optimizing data sharing and coordinated transmission among multiple access points.

[0214] (1) Multiple access points simultaneously coordinate the transmission of shared data, enabling stable data reception at the destination communication terminal.

[0215] (2) When sharing data for cooperative transmission between adjacent access points, data sharing can be achieved in a short time by configuring multiple data (MPDU) as a spatially multiplexed stream.

[0216] (3) It is possible to use the timing when data transmission to the communication terminal that is the receiving target of cooperative transmission is not possible to perform data sharing communication between access points.

[0217] (4) By including information about the communication terminal that will be the receiving target of the cooperative transmission in the grant frame that notifies the confirmation of receipt of the shared data, and by specifying the communication terminal that will receive the cooperative transmission data, the receiving terminal can be made aware in advance that the cooperative transmission will be performed.

[0218] (5) When coordinating transmission is performed by multiple access points, data destined for other communication terminals can be multiplexed as a spatial multiplexed stream with data destined for other communication terminals that are the target of the coordinating transmission, thereby enabling efficient wireless transmission.

[0219] (6) When coordinating transmission with multiple access points, the transmission parameters selected will be an encoding and modulation scheme that ensures reliable reception of transmissions from access points with poorer connectivity. Therefore, although coordinating transmission may occupy the wireless transmission path for a relatively long period of time, this time can be used to improve the efficiency of transmission path utilization by multiplexing and transmitting more data to other communication devices with better connectivity.

[0220] (7) An access point can efficiently utilize the wireless transmission path by simultaneously performing communication to a communication terminal connected to itself and communication to a communication terminal connected to another access point using spatial division multiplexing technology.

[0221] (8) By multiplexing and transmitting multiple spatially multiplexed streams from one access point to one communication terminal, the amount of data transmitted per unit time can be increased. [Industrial applicability]

[0222] The technologies disclosed herein have been described in detail above with reference to specific embodiments. However, it will be obvious that those skilled in the art can modify or substitute these embodiments without departing from the essence of the technologies disclosed herein.

[0223] The technologies disclosed herein can be applied to, but are not limited to, wireless networks based on wireless LAN standards such as IEEE 801.11. The technologies disclosed herein can also be applied to various types of wireless systems in which adjacent access points or base stations can operate in cooperation with each other.

[0224] In short, the technologies disclosed herein have been described in the form of examples, and the contents of this specification should not be interpreted restrictively. To determine the gist of the technologies disclosed herein, the claims should be taken into consideration.

[0225] Furthermore, the technology disclosed in this specification may also take the following configuration.

[0226] (1) A communication unit that transmits and receives wireless signals, A control unit that controls the communication operations in the communication unit, including communication operations for sharing data to be simultaneously transmitted to a single communication terminal between adjacent access points, and communication operations for recognizing that the sharing of said data has been completed. A communication device that operates as an access point and is equipped with the following features.

[0227] The aforementioned communication unit is capable of transmitting and receiving wireless signals that are configured as multiple streams of multiple data, The control unit controls the transmission of the shared data simultaneously with the adjacent access point, by multiplexing it with transmission streams destined for other communication devices and transmitting it as a multi-user multiplexed stream. The communication device described in (1) above.

[0228] (2-1) The communication unit is capable of transmitting and receiving wireless signals that are configured as spatially multiplexed streams of multiple data, The control unit controls the transmission of the shared data simultaneously with the adjacent access point, by multiplexing it with transmission streams destined for other communication devices and transmitting it as a multi-user space multiplexed stream. The communication device described in (1) above.

[0229] (3) The communication unit is capable of transmitting and receiving wireless signals that consist of multiple data as multiple streams, The control unit controls the communication of data to be shared between adjacent access points by multiplexing it as multiple streams. A communication device as described in either (1) or (2) above.

[0230] (3-1) The communication unit is capable of transmitting and receiving wireless signals that are configured as spatially multiplexed streams of multiple data, The control unit controls the communication of data to be shared between adjacent access points by multiplexing it as a spatially multiplexed stream. A communication device as described in any of (1) to (3) above.

[0231] (4) The control unit controls the system to perform communication operations to share the data between adjacent access points during a time interval in which one communication terminal is unable to communicate. A communication device as described in any of (1) to (3) above.

[0232] (5) The control unit controls the communication for sharing the data between adjacent access points to be carried out using a high-speed transmission encoding or modulation scheme. A communication device as described in any of (1) to (4) above.

[0233] (6) The control unit transmits a predetermined initiation frame to notify the adjacent access point to share the data or to simultaneously transmit the shared data to one communication terminal. A communication device as described in any of (1) through (5) above.

[0234] (7) The control unit recognizes, upon receiving a predetermined initiation frame from the adjacent access point, that it will share the data or simultaneously transmit the shared data to one communication terminal. A communication device as described in any of (1) through (5) above.

[0235] (8) The Initiate Frame includes information about access points that simultaneously transmit the shared data, A communication device as described in either (6) or (7) above.

[0236] (9) The initiator frame further includes at least one of the following: information regarding the timing of transmission of the shared data, information regarding the encoding or modulation scheme used when transmitting the shared data, and information regarding the channel through which the shared data is transmitted. The communication device described in (8) above.

[0237] (10) The control unit controls the timing of transmission of the shared data based on the transmission of a predetermined trigger frame or the receipt of the trigger frame from the adjacent access point. A communication device as described in any of (1) through (9) above.

[0238] (11) The control unit recognizes the sharing of the data based on the communication of a predetermined grant frame with the adjacent access point. A communication device as described in any of (1) through (10) above.

[0239] (12) The control unit controls the adjacent access point that has transmitted the shared data to send back the grant frame. The communication device described in (11) above.

[0240] (13) The control unit controls the receiving process of the grant frame sent back from the adjacent access point which is the destination for the shared data. The communication device described in (11) above.

[0241] (14) The grant frame includes at least one of the following: information relating to one communication terminal, information relating to the number of multiple transmissions when transmitting the shared data, and communication parameters when transmitting the shared data. A communication device as described in any of (11) to (13) above.

[0242] (15) The communication unit is capable of transmitting and receiving wireless signals that consist of multiple data as multiple streams, The grant frame further includes at least one of the following: information regarding the number of multiple transmissions when transmitting the shared data, and communication parameters when transmitting the shared data. The communication device described in (13) above.

[0243] (16) The control unit discards the shared data based on the completion of receiving the shared data at one of the communication terminals. A communication device as described in any of (1) through (15) above.

[0244] (17) The control unit controls the multiplexed transmission of data based on the number of multiple streams that can be received by the one communication terminal and the other communication terminal. The communication device described in (2) above.

[0245] (18) A step of sharing data to be transmitted simultaneously to one communication terminal between adjacent access points, A step of recognizing that the sharing of the aforementioned data has been completed, The steps include sending the shared data, A communication method at an access point, comprising the following features.

[0246] (19) A communication unit that transmits and receives wireless signals, A control unit that controls the communication operation in the communication unit, including an operation that recognizes that the same data has been transmitted simultaneously from multiple access points based on the receipt of a predetermined frame from an access point, A communication device that operates as a communication terminal connected to an access point, equipped with the following features.

[0247] (19-1) The predetermined frame is a grant frame containing information regarding the sharing of the same data between adjacent access points. The communication device described in (19) above.

[0248] (19-2) The grant frame includes at least one of the following: information about the communication terminal, information about the number of multiple transmissions when transmitting the shared data, and communication parameters when transmitting the shared data. The communication device described in (19-1) above.

[0249] (19-3) The communication unit is capable of transmitting and receiving wireless signals that consist of multiple data as multiple streams, The control unit controls the reception of a multi-user multiplexed stream from the multiple access points, in which the same data stream and transmission streams destined for other communication devices are multiplexed. The communication device described in (19) above.

[0250] (20) The step of receiving a predetermined frame from an access point, The steps include: recognizing, based on the received predetermined frame, that the same data was transmitted simultaneously from multiple access points; The steps include receiving the same data transmitted simultaneously from the multiple access points, A communication method in a communication terminal connected to an access point, having the following features. [Explanation of Symbols]

[0251] 2000...Communication equipment, 2001...Internet connection module 2002…Information input module, 2003…Equipment control unit 2004…Information output module, 2005…Wireless communication module 2101…Interface, 2102…Transmit buffer 2103...Network Management Department, 2104...Transmission Frame Construction Department 2105...Received data construction unit, 2106...Receive buffer 2107... Cooperative Communication Management Unit, 2108... Spatial Multiplexing Transmission Processing Unit 2109...Spatial multiplex reception processing unit, 2110...Management information generation unit 2111...Management Information Processing Unit, 2112...Wireless Transmission Processing Unit 2113...Transmit power control unit, 1014...Transmit / receive antenna control unit 2115...Detection threshold control unit, 2116...Wireless reception processing unit

Claims

1. The third wireless communication device includes a control unit that controls a communication unit so as to receive a first signal containing first information relating to a signal to be wirelessly transmitted to a second wireless communication device in cooperation with a first wireless communication device. The control unit controls the communication unit to transmit a second signal containing information indicating the second wireless communication device, in response to receiving the first signal. Communication control device.

2. The first information includes data to be wirelessly transmitted to the second wireless communication device in cooperation with the first wireless communication device. The communication control device according to claim 1.

3. The control unit controls the communication unit to wirelessly transmit the second signal to the first wireless communication device. The communication control device according to claim 2.

4. The transmission time of the third signal transmitted from the first wireless communication device and including the data and the transmission time of the fourth signal transmitted from the third wireless communication device and including the data overlap at least partially. The communication control device according to claim 3.

5. The third signal and the fourth signal are simultaneously transmitted to the second wireless communication device. The communication control device according to claim 4.

6. The second signal includes information on communication parameters used when the first wireless communication device and the third wireless communication device cooperate to transmit the data. The communication control device according to claim 4.

7. The information of the communication parameters includes information relating to the Modulation and Coding Scheme (MCS) and information relating to the transmission power, The communication control device according to claim 6.

8. The third signal and the fourth signal are transmitted in response to the reception of the fifth signal, The fifth signal includes information indicating that coordinated transmission will be performed. The communication control device according to claim 4.

9. The fifth signal includes information indicating the transmission power of the third signal and information indicating the transmission power of the fourth signal, The communication control device according to claim 8.

10. The fifth signal includes information indicating the Modulation and Coding Scheme (MCS) of the third signal and information indicating the MCS of the fourth signal, The communication control device according to claim 9.

11. The fourth signal includes information for identifying that a coordinated transmission operation is being performed. The communication control device according to claim 4.

12. The first signal includes information indicating a fourth wireless communication device that, in cooperation with the first wireless communication device and the third wireless communication device, transmits the data to the second wireless communication device. The communication control device according to claim 4.

13. The interval between the second signal and the fourth signal is a predetermined interval. The communication control device according to claim 4.

14. The control unit controls the communication unit to transmit the fourth signal by multiplexing it with the sixth signal transmitted to the fifth wireless communication device. The communication control device according to claim 4.

15. The second signal includes at least one of the following: information regarding the number of multiple transmissions when transmitting the data with the fourth signal, and communication parameters when transmitting the data. The communication control device according to claim 4.

16. The information indicating the second wireless communication device is information indicating the address of the second wireless communication device. The communication control device according to claim 1.

17. The control unit controls the communication unit to receive the first signal from the first wireless communication device and transmit the second signal to the first wireless communication device. The communication control device according to claim 1.

18. The control unit controls the communication unit to receive the first signal from the sixth wireless communication device and transmit the second signal to the sixth wireless communication device. The communication control device according to claim 1.

19. The information indicating that the coordinated transmission will be performed is common information for a plurality of wireless communication devices that receive the data. The communication control device according to claim 8.

20. The fifth signal includes information indicating parameters for coordinating the transmission of the data, The communication control device according to claim 8.

21. Information indicating the parameters for coordinating the transmission of the data is sent as necessary information for each of the multiple wireless communication devices. The communication control device according to claim 20.

22. A control step is provided to control a communication unit provided in a third wireless communication device so as to receive a first signal which includes first information relating to a signal to be wirelessly transmitted to a second wireless communication device in cooperation with a first wireless communication device, In the control step, the communication unit is controlled to transmit a second signal containing information indicating the second wireless communication device in response to receiving the first signal. Communication control method.

23. A control unit that controls a communication unit to transmit a first signal containing first information relating to a signal that the first wireless communication device and the third wireless communication device cooperate to transmit wirelessly to the second wireless communication device, The control unit controls the communication unit to receive a second signal, which is transmitted in response to the reception of the first signal and includes information indicating the second wireless communication device. Communication control device.

24. The communication unit is included in the first wireless communication device, The second signal is transmitted wirelessly from the third wireless communication device. The communication control device according to claim 23.

25. A control step is provided to control a communication unit so that a first wireless communication device and a third wireless communication device cooperate to transmit a first signal containing first information relating to a signal to be wirelessly transmitted to a second wireless communication device, The control step involves controlling the communication unit to receive a second signal, which is transmitted in response to the reception of the first signal and includes information indicating the second wireless communication device. Communication control method.

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