Communication method and communication system

Abstract

This communication method comprises: a step A in which a master base station 1, upon determining that the master base station 1 can perform joint transmission with m slave base stations among n slave base stations 2-1 to 2-n, calculates m data amounts of m transmission data to be respectively allocated to the m slave base stations; a step B in which the master base station 1 transmits a transmission timing notification to the m slave base stations by wireless communication; a step C in which the master base station transmits the m transmission data respectively having the m data amounts to the m slave base stations via a backhaul; and a step D in which the master base station 1 and the m slave base stations generate and transmit (m+1) transmission frames to a wireless device 3.

Description

Communication methods and systems

[0001] The present invention relates to a communication method and a communication system.

[0002] Toward the realization of Society 5.0, there is a demand for high-capacity, simultaneous multi-connection transmission technologies for high-definition video, sensing information, and other data in fields such as education and medical care, as well as for the advancement of communication tools such as AR and VR, and mobility (Non-Patent Documents 1 to 3).

[0003] For example, if you try to transmit full-spec 8K video at 120 fps uncompressed to reduce latency, a communication speed of over 100 Gbps is required.

[0004] For example, when focusing on wireless LANs (Local Area Networks), the maximum communication speed of the IEEE 802.11 wireless LAN standard (176 Gbps for IEEE 802.11ay), which has been completed and published to date, is insufficient when considering the simultaneous provision of services to multiple users and widespread use.

[0005] On the other hand, IEEE 802.15.3d, whose standard was completed and published in 2017, utilizes the terahertz band, which allows for wide frequency channel widths, enabling point-to-point communication at a maximum transmission speed of 100 Gbps. However, it does not support license-free simultaneous connections by multiple terminals, as typified by IEEE 802.11 wireless LAN.

[0006] Currently, at the IEEE 802.11 standardization conference, discussions are underway on Joint Transmission, which involves linking a plurality of access points to transmit data over a plurality of links.

[0007] Cabinet Office, "Society 5.0: A New Society Pioneered by Science, Technology, and Innovation" Explanatory Material Cabinet Office, "6th Science, Technology, and Innovation Basic Plan", March 2021 KDDI Corporation, "Beyond5G / 6G White Paper Ver.2.0.1", October 2021

[0008] To perform Joint Transmission, it is necessary to allocate data to be transmitted in advance to each cooperating access point.

[0009] However, if the same channel as that used for data transmission from each access point to a wireless device is used to distribute transmission data to each cooperating access point, wireless resources become constrained, resulting in a problem of low throughput.

[0010] In cellular CoMP (Coordination Multi-Point), data transmission time is fixed by time slot unit transmission and scheduling, but IEEE 802.11 wireless LAN uses channel access by CSMA / CA (Carrier Sense Multiple Access with Collision Avoidance) and the transmission time is variable, which causes the above problem.

[0011] Therefore, according to an embodiment of the present invention, a communication method is provided that can improve the throughput when transmitting data from an access point to a wireless device.

[0012] Furthermore, according to the embodiment of the present invention, a communication system is provided that can improve the throughput when transmitting data from an access point to a wireless device.

[0013] (Configuration 1) According to an embodiment of the present invention, a communication method transmits transmission data D_trsm to a wireless device using joint transmission in which a master base station and m (m is an integer satisfying 1≦m≦n) slave base stations out of n (n is an integer equal to or greater than 1) slave base stations jointly transmit transmission data D_trsm to the wireless device by CSMA / CA wireless communication using one channel, the communication method comprising: a first step in which the master base station determines whether joint transmission is possible; a second step in which the master base station calculates m data amounts of the m transmission data to be allocated to the m slave base stations, when it is determined in the first step that joint transmission is possible; a third step in which the master base station, after the second step, transmits transmission timing notifications to the m slave base stations by wireless communication, notifying the m slave base stations of timings for transmitting transmission frames to the wireless device; and a fourth step in which the master base station, after the second step, transmits the m transmission data, each having m data amounts, to the m slave base stations using backhaul, The method includes a fifth step in which the master base station and each of the m slave base stations perform a transmission frame generation process, which is a process of generating a transmission frame based on the amount of data, after the second step; a sixth step in which the master base station and the m slave base stations transmit (m+1) transmission frames to the wireless device by joint transmission when it is time to transmit; and a seventh step in which the master base station receives a block ACK from the wireless device, after the sixth step, which sends an ACK in bulk to confirm reception of the frames.

[0014] (Configuration 2) In configuration 1, the fourth and fifth steps are executed in parallel with the third step.

[0015] (Configuration 3) In configuration 1, in the second step, the master base station calculates, for all m slave base stations, the amount of data to be allocated to the slave base station for which the amount of data is to be calculated, so that the amount of data is proportional to the wireless transmission rate of the transmission data at the slave base station for which the amount of data is to be calculated and inversely proportional to the sum of the wireless transmission rate of the transmission data at the master base station and the m wireless transmission rates at the m slave base stations, thereby calculating m amounts of data.

[0016] (Configuration 4) In configuration 1, in the third step, the master base station transmits padding having a length equal to the padding time and a notification of the transmission timing to m slave base stations via wireless communication.

[0017] (Configuration 5) In configuration 4, the padding time is the maximum padding time among m padding times in m slave base stations.

[0018] (Configuration 6) In configuration 5, in the third step, the master base station calculates the padding time of one slave base station using the transmission time when transmitting transmission data having a data amount allocated to one slave base station via backhaul to one slave base station, the processing time for generating a transmission frame in one slave base station, the transmission time when transmitting a notification of the transmission timing to one slave base station, and the SIFS time in the CSMA / CA method, for all m slave base stations, thereby calculating m padding times.

[0019] (Configuration 7) In configuration 6, in the third step, the master base station calculates the padding time of one slave base station by subtracting the transmission time of the notification of transmission timing and the SIFS time from the sum of the transmission time and the processing time for generating the transmission frame.

[0020] (Configuration 8) In configuration 1, in the transmission frame generation process of the fifth step, the m slave base stations each generate m transmission frames to be transmitted to the wireless device, each of the m transmission frames consisting of physical layer frames, based on each of the m transmission data transmitted by the master base station in the fourth step.

[0021] (Configuration 9) In configuration 1, the configuration further includes an eighth step in which, when it is determined in the first step that joint transmission is not possible, the master base station transmits a transmission frame including transmission data D_trsm to the wireless device by wireless communication only, instead of the second to sixth steps.

[0022] (Configuration 10) In Configuration 1, when a state in which a base station and a wireless device can transmit and receive data to and from each other in a wireless LAN is defined as "being under its control," a channel that a base station uses in common with all wireless devices under its control is defined as a primary channel, a channel that a base station can use together with the primary channel to expand the bandwidth of communication with wireless devices under its control is defined as a secondary channel, and a channel that a base station can use together with the primary channel to expand the bandwidth of communication with wireless devices under its control is defined as a channel Ch_JT_CMM among a master base station, a slave base station, and wireless devices participating in a joint transmission JT, which is "a configuration that is part of the common part of 'primary channel and secondary channel' or the widest channel of the common part and includes the primary channel, under the condition that the primary channels of all base stations and wireless devices are included," the following conditions are satisfied: a first condition that the primary channel of the wireless device is the same as the primary channel of the master base station; a second condition that the secondary channel of the wireless device is within the range of the secondary channel of the master base station; a third condition that the primary channels of m slave base stations are within the range of the primary channel or secondary channel of the wireless device; and a fourth condition that the primary channel of the wireless device is within the range of the secondary channel of m slave base stations when the primary channel of the wireless device is different from the primary channels of m slave base stations. In the sixth step, the master base station and m slave base stations use "CSMA / CA wireless communication using channel Ch_JT_CMM" instead of "CSMA / CA wireless communication using one channel," and when the transmission timing arrives, they transmit (m+1) transmission frames to the wireless device by joint transmission.

[0023] (Configuration 11) According to an embodiment of the present invention, a communication system transmits transmission data D_trsm to a wireless device using joint transmission in which a master base station and m (m is an integer satisfying 1≦m≦n) slave base stations out of n (n is an integer equal to or greater than 1) slave base stations jointly transmit transmission data D_trsm to the wireless device by CSMA / CA wireless communication using one channel, the communication system comprising: the master base station, when it is determined that joint transmission is possible, performing: a calculation process of calculating m data amounts of the m transmission data to be assigned to each of the m slave base stations; a first transmission process of transmitting, after the calculation process, transmission timing notifications to the m slave base stations by wireless communication, notifying the timing of when to transmit the transmission frames to the wireless device; a second transmission process of transmitting, after the calculation process, the m transmission data, each having m data amounts, to the m slave base stations using a backhaul; and a transmission frame generation process of generating a transmission frame based on its own transmission data after the calculation process; the system comprises m slave base stations, each of which performs a first reception process to receive notification of transmission timing from the master base station and a second reception process to receive m pieces of transmission data from the master base station using a backhaul; and a wireless device that receives (m+1) transmission frames transmitted by joint transmission between the master base station and the m slave base stations, and transmits a block ACK to the master base station to collectively acknowledge reception of the frames, wherein each of the m slave base stations performs a transmission frame generation process to generate a transmission frame based on the transmission data received in the second reception process, and when it is transmission timing, the master base station and the m slave base stations transmit the (m+1) transmission frames to the wireless device by joint transmission, and the master base station receives the block ACK from the wireless device after transmitting the (m+1) transmission frames to the wireless device by joint transmission with the m slave base stations.

[0024] (Configuration 12) In configuration 11, the master base station executes the second transmission process and the transmission frame generation process in parallel with the first transmission process, and each of the m slave base stations executes the transmission frame generation process in parallel with the first transmission process.

[0025] (Configuration 13) In configuration 11, in the calculation process, the master base station calculates, for all m slave base stations, the amount of data to be allocated to the slave base station for which the amount of data is to be calculated, so that the amount of data is proportional to the wireless transmission rate of the transmission data at the slave base station for which the amount of data is to be calculated, and inversely proportional to the sum of the wireless transmission rate of the transmission data at the master base station and the m wireless transmission rates at the m slave base stations, thereby calculating m amounts of data.

[0026] (Configuration 14) In configuration 11, in the first transmission process, the master base station transmits padding having a length equal to the padding time and a notification of the transmission timing to m slave base stations via wireless communication.

[0027] (Configuration 15) In configuration 14, the padding time is the maximum padding time among m padding times of m slave base stations.

[0028] (Configuration 16) In configuration 15, in the first transmission process, the master base station calculates the padding time of one slave base station using the transmission time when transmitting transmission data having a data amount allocated to one slave base station via backhaul to one slave base station, the processing time for generating a transmission frame in one slave base station, the transmission time when transmitting a notification of transmission timing to one slave base station, and the SIFS time in the CSMA / CA method, for all m slave base stations, to calculate m padding times.

[0029] (Configuration 17) In configuration 16, in the first transmission process, the master base station calculates the padding time of one slave base station by subtracting the transmission time of the notification of the transmission timing and the SIFS time from the sum of the transmission time and the processing time for generating the transmission frame.

[0030] (Configuration 18) In configuration 11, in a transmission frame generation process, the m slave base stations each generate m transmission frames to be transmitted to a wireless device, the m transmission frames being made up of physical layer frames, based on the m pieces of transmission data transmitted by the master base station in the second transmission process.

[0031] (Configuration 19) In configuration 11, when the master base station determines that joint transmission is not possible, instead of performing the first transmission process, the calculation process, the second transmission process, the transmission frame generation process, and transmitting (m+1) transmission frames to the wireless device through joint transmission with m slave base stations, the master base station alone transmits transmission data D_trsm to the wireless device via wireless communication.

[0032] (Configuration 20) In configuration 11, when a base station and a wireless device are in a state in which they can transmit and receive data to and from each other in a wireless LAN, the base station defines a channel that is commonly used between the base station and all wireless devices subordinate to it as a primary channel, a channel that the base station can use together with the primary channel to expand the bandwidth of communication with the wireless devices subordinate to it as a secondary channel, and a channel that is "a configuration that is a common part of the 'primary channel and secondary channel' or a part of the widest channel of the common part and includes the primary channel, under the condition that the primary channels of all base stations and wireless devices are included" among the master base station, slave base stations, and wireless devices participating in the joint transmission JT is defined as channel Ch_JT_CMM, the following conditions are satisfied: a first condition that the primary channel of the wireless device is the same as the primary channel of the master base station; a second condition that the secondary channel of the wireless device is within the range of the secondary channel of the master base station; a third condition that the primary channels of m slave base stations are within the range of the primary channel or secondary channel of the wireless device; and a fourth condition that the primary channel of the wireless device is within the range of the secondary channel of m slave base stations when the primary channel of the wireless device is different from the primary channels of m slave base stations. The master base station and m slave base stations use "CSMA / CA wireless communication using channel Ch_JT_CMM" instead of "CSMA / CA wireless communication using one channel" and, when the transmission timing arrives, transmit (m+1) transmission frames to the wireless device by joint transmission.

[0033] Radio resources can be used effectively to improve throughput.

[0034] 1 is a schematic diagram of a communication system according to embodiment 1 of the present invention. FIG. 1 is a schematic diagram of a master base station 1 shown in FIG. 1. FIG. 1 is a schematic diagram of a slave base station 2-1 shown in FIG. 1. FIG. 1 is a schematic diagram of a wireless device 3 shown in FIG. 1. FIG. 1 is a conceptual diagram for explaining a method of generating transmission data in the master base station 1 and m slave base stations. FIG. 1 is a conceptual diagram showing the configuration of a transmission frame. FIG. 1 is a schematic diagram showing frame processing in the communication system 10 shown in FIG. 1. FIG. 1 is a schematic diagram showing conventional frame processing. FIG. 1 is another schematic diagram showing frame processing in the communication system 10 shown in FIG. 1. FIG. 1 is a first flowchart for explaining the operation of the communication system 10 shown in FIG. 1. FIG. 1 is a second flowchart for explaining the operation of the communication system 10 shown in FIG. 1. FIG. 1 is a schematic diagram of a communication system according to embodiment 2. FIG. 12 is a schematic diagram of a master base station 1A shown in FIG. 12. FIG. 13 is a schematic diagram showing information held in advance by a control unit 13A. FIG. 13 is a schematic diagram showing frame processing in the communication system 10A shown in FIG. 12. FIG. 14 is another schematic diagram showing frame processing in the communication system 10A shown in FIG. 12. FIG. 15 is a first flowchart for explaining the operation of the communication system 10A shown in FIG. 12. FIG. 16 is a second flowchart for explaining the operation of the communication system 10A shown in FIG. 12. FIG. 18 is a flowchart for explaining the detailed operation of step S17 in FIG. 17. FIG. 19 is a diagram showing an example of the configuration of channel Ch_JT_CMM. FIG. 20 is a diagram showing another example of the configuration of channel Ch_JT_CMM. FIG. 21 is a diagram showing yet another example of the configuration of channel Ch_JT_CMM. FIG. 22 is a schematic diagram showing frame processing when channel Ch_JT_CMM is used. FIG. 23 is another schematic diagram of the master base station 1 shown in FIG. 2. FIG. 24 is another schematic diagram of the master base station 1A shown in FIG. 13. FIG. 25 is another schematic diagram of the slave base station 2-1 shown in FIG. 3. FIG. 26 is another schematic diagram of the wireless device 3 shown in FIG. 4.

[0035] DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be described in detail with reference to the drawings. In the drawings, the same or corresponding parts are designated by the same reference numerals and description thereof will not be repeated.

[0036] 1 is a schematic diagram of a communication system according to a first embodiment of the present invention. Referring to Fig. 1, a communication system 10 according to the first embodiment of the present invention includes a master base station 1, n (n is an integer of 1 or more) slave base stations 2-1 to 2-n, and a wireless device 3.

[0037] In FIG. 1, solid arrows represent transmission and reception of data via wireless communication and notification of transmission results via wireless communication, and dotted arrows represent transmission and reception of control information via wireless communication.

[0038] A master base station 1, n slave base stations 2-1 to 2-n, and a wireless device 3 are arranged in a wireless communication space.

[0039] The master base station 1 is connected to n slave base stations 2-1 to 2-n via a backhaul 4.

[0040] The master base station 1 and the n slave base stations 2-1 to 2-n are located at mutually different positions, and the wireless device 3 is located within the communication range of wireless communication by the master base station 1 and each of the n slave base stations 2-1 to 2-n.

[0041] The master base station 1, n slave base stations 2-1 to 2-n, and wireless device 3 perform wireless communication using a single channel, Ch_JT, according to the CSMA / CA method.

[0042] The channel Ch_JT is, for example, the primary channel of the master base station 1 (= a channel that the base station uses in common with all wireless devices under its control). "Being under its control" means that the base station and the wireless devices can transmit and receive data to and from each other in the wireless LAN.

[0043] In this embodiment of the present invention, "joint transmission JT" means that the master base station 1 and m (m is an integer satisfying 1≦m≦n) slave base stations out of n slave base stations 2-1 to 2-n jointly transmit transmission data D_trsm to the wireless device 3 via CSMA / CA wireless communication using channel Ch_JT.

[0044] The master base station 1 receives the transmission data D_trsm from the source and then transmits an RTS (Request To Send) to the n slave base stations 2-1 to 2-n and the wireless device 3 by wireless communication using the channel Ch_JT.

[0045] Thereafter, when the master base station 1 receives a CTS (Clear To Send) from the wireless device 3 via wireless communication using the channel Ch_JT, the master base station 1 transmits a confirmation frame F via wireless communication using the channel Ch_JT to confirm whether or not the joint transmission JT is to be started. Ｓ＿ＰＢ is transmitted to n slave base stations 2-1 to 2-n.

[0046] Then, the master base station 1 transmits a confirmation frame F Ｓ＿ＰＢ Response frame F indicating whether joint transmission JT is possible or not ＲＳＰ are received from n slave base stations 2-1 to 2-n.

[0047] Here, the response frame F ＲＳＰ contains "JT_OK" indicating that joint transmission JT is possible, or "JT_NG" indicating that joint transmission JT is not possible.

[0048] The master base station 1 receives n response frames F from n slave base stations 2-1 to 2-n. ＲＳＰ When receiving n response frames F ＲＳＰ Based on this, it is determined whether joint transmission JT is possible.

[0049] More specifically, the master base station 1 receives n response frames F ＲＳＰ Among them, m response frames F ＲＳＰ If the JT_OK flag is set to "JT_OK", the master base station 1 determines that joint transmission JT is possible with m slave base stations among the n slave base stations 2-1 to 2-n.

[0050] On the other hand, the master base station 1 receives n response frames F ＲＳＰ If all of the above include "JT_NG", it is determined that joint transmission JT is not possible.

[0051] Note that n response frames F ＲＳＰ Among them, m response frames F ＲＳＰ contains "JT_OK" indicates that at least one response frame F among the n response frames FRSP ＲＳＰ This corresponds to including "JT_OK".

[0052] When the master base station 1 determines that joint transmission JT is possible, it determines the amount of data d to be distributed to m slave base stations by a method to be described later. １ ~d ｍ Calculate.

[0053] Then, the master base station 1 executes the following steps (1) to (3).

[0054] (1) The master base station 1 transmits a notification of the transmission timing to m slave base stations by wireless communication using the channel Ch_JT.

[0055] (2) The master base station 1 receives the data amount (= the calculated data amount d １ ~d ｍ ) and distributes the transmission data to the slave base stations via the backhaul 4 in parallel with (1).

[0056] (3) The master base station 1 and the slave base station perform a transmission frame generation process in parallel with (1).

[0057] The transmission timing is the timing at which a transmission frame is transmitted to the wireless device 3, and the notification of the transmission timing is the notification of the timing at which a transmission frame is transmitted to the wireless device 3.

[0058] When the above steps (1) to (3) are executed, the master base station 1 and the m slave base stations simultaneously transmit transmission frames to the wireless device 3 by wireless communication using the channel Ch_JT.

[0059] Thereafter, the master base station 1 receives a block Ack from the wireless device 3, which sends a block Ack to confirm reception of the frames.

[0060] On the other hand, when the master base station 1 determines that joint transmission JT is not possible, it executes the following (A) or (B).

[0061] (A) The master base station 1 transmits a transmission frame F_trsm including transmission data D_trsm to the wireless device 3 by wireless communication using the channel Ch_JT.

[0062] (B) The master base station 1 does not transmit the transmission frame F_trsm including the transmission data D_trsm to the wireless device 3 .

[0063] The n slave base stations 2-1 to 2-n receive the RTS transmitted from the master base station 1 by wireless communication using the channel Ch_JT.

[0064] Furthermore, the n slave base stations 2-1 to 2-n receive the confirmation frame F transmitted by the master base station 1 via wireless communication using the channel Ch_JT. Ｓ＿ＰＢ Receive.

[0065] Then, each of the n slave base stations 2-1 to 2-n transmits a confirmation frame F Ｓ＿ＰＢ In response to receiving the JT, the master base station 1 determines whether joint transmission JT with the master base station 1 is possible.

[0066] When each of the n slave base stations 2-1 to 2-n is capable of joint transmission JT with the master base station 1, it transmits a response frame F including "JT_OK" by wireless communication using the channel Ch_JT. ＲＳＰ to the master base station 1.

[0067] On the other hand, when the joint transmission JT with the master base station 1 is impossible, each of the n slave base stations 2-1 to 2-n transmits a response frame F including "JT_NG" by wireless communication using the channel Ch_JT. ＲＳＰ to the master base station 1.

[0068] However, each of the n slave base stations 2-1 to 2-n transmits a response frame F ＲＳＰ If the master base station 1 is unable to transmit a response frame F ＲＳＰto the master base station 1. In this case, the master base station 1 may not transmit the response frame F ＲＳＰ For slave base stations that do not receive the JT signal, it is determined that joint transmission JT is not possible.

[0069] Response frame F containing "JT_OK" ＲＳＰ The m slave base stations that have transmitted the data amount d １ ~d ｍ After calculating the above, the following steps (4) to (6) are executed.

[0070] (4) Each of the m slave base stations receives notification of the transmission timing from the master base station 1 by wireless communication using the channel Ch_JT.

[0071] (5) Each of the m slave base stations receives transmission data from the master base station 1 via the backhaul 4 in parallel with (4).

[0072] (6) Each of the m slave base stations performs a transmission frame generation process in parallel with (4).

[0073] Here, (4) is executed in response to the above-mentioned "(1) The master base station 1 transmits a notification of the transmission timing to m slave base stations by wireless communication using the channel Ch_JT." Also, (5) is executed in response to the above-mentioned "(2) The master base station 1 calculates the data amount (= the calculated data amount d １ ~d ｍ In parallel with (1), (6) is executed in response to the above-mentioned "(3) The master base station 1 and m slave base stations perform a transmission frame generation process in parallel with (1)."

[0074] Thereafter, each of the m slave base stations transmits a transmission frame to the wireless device 3 simultaneously with the master base station 1 through wireless communication using channel Ch_JT.

[0075] The wireless device 3 receives an RTS from the master base station 1 through wireless communication using the channel Ch_JT. Then, the wireless device 3 transmits a CTS to the master base station 1 through wireless communication using the channel Ch_JT.

[0076] Thereafter, when joint transmission JT is enabled, the wireless device 3 receives (m+1) transmission frames from the master base station 1 and the m slave base stations by wireless communication using the channel Ch_JT.

[0077] Then, the wireless device 3 transmits a Block Ack to the master base station 1 by wireless communication using the channel Ch_JT.

[0078] On the other hand, when joint transmission JT is not possible, the wireless device 3 receives a transmission frame F_trsm including transmission data D_trsm only from the master base station 1 by wireless communication using channel Ch_JT.

[0079] Then, the wireless device 3 transmits a Block Ack to the master base station 1 by wireless communication using the channel Ch_JT.

[0080] It should be noted that when joint transmission JT is not possible, the wireless device 3 may not receive the transmission frame F_trsm including the transmission data D_trsm from only the master base station 1 .

[0081] Fig. 2 is a schematic diagram of the master base station 1 shown in Fig. 1. Referring to Fig. 2, the master base station 1 includes an antenna 11, a receiving unit 12, a control unit 13, a radio unit 14, generating units 15 and 16, and a transmitting unit 17.

[0082] The receiving unit 12 receives the transmission data D_trsm addressed to the wireless device 3 via the network, and outputs the received transmission data D_trsm to the control unit 13 .

[0083] When the control unit 13 receives the transmission data D_trsm from the receiving unit 12, it outputs an RTS to the wireless unit 14 and controls the wireless unit 14 to transmit the RTS to n slave base stations 2-1 to 2-n and the wireless device 3 via wireless communication using the channel Ch_JT.

[0084] After that, when the control unit 13 receives a CTS from the wireless unit 14, it sends a confirmation frame F Ｓ＿ＰＢ Then, the control unit 13 generates a confirmation frame F Ｓ＿ＰＢ to the wireless unit 14, and transmits a confirmation frame F Ｓ＿ＰＢ The radio unit 14 is controlled so as to transmit the above signal to the n slave base stations 2-1 to 2-n.

[0085] The control unit 13 receives a confirmation frame F Ｓ＿ＰＢ to the wireless unit 14, and then n response frames F ＲＳＰ The control unit 13 then receives n response frames F ＲＳＰ It is determined whether joint transmission JT is possible based on the above.

[0086] In this case, the control unit 13 receives n response frames F ＲＳＰ Among them, m response frames F ＲＳＰ includes "JT_OK", the control unit 13 determines that joint transmission JT is possible. That is, the control unit 13 determines that joint transmission JT with m slave base stations out of the n slave base stations 2-1 to 2-n (at least one slave base station out of the n slave base stations 2-1 to 2-n) is possible.

[0087] On the other hand, the control unit 13 receives n response frames F ＲＳＰ If all of the above include "JT_NG", it is determined that joint transmission JT is not possible.

[0088] The control unit 13 calculates n wireless transmission rates r １ ~r ｎ The n addresses Add of the n slave base stations 2-1 to 2-n are respectively １ ~Addｎ The timer includes a timer and a correspondence table TBL in advance that associates the time stamps with the time stamps.

[0089] Then, the control unit 13 refers to the correspondence table TBL and obtains m addresses Add of m slave base stations that can perform joint transmission JT with the master base station 1. １ ~Add ｍ m wireless transmission rates r of m slave base stations based on １ ~r ｍ Detect.

[0090] Thereafter, the control unit 13 receives the transmission data D_trsm and the m wireless transmission rates r １ ~r ｍ to the generating unit 15, and the data amount D of the transmission data D_trsm and the m wireless transmission rates r １ ~r ｍ The amount of data d allocated to the master base station 1 based on ｍｓｔ and the amount of data d distributed to m slave base stations １ ~d ｍ and calculate the data volume d ｍｓｔ The transmission data d of the master base station 1 having ｍｓｔ＿ｔｒｓｍ and the amount of data d １ ~d ｍ m transmission data d of m slave base stations each having １＿ｔｒｓｍ ~d ｍ＿ｔｒｓｍ and the transmission data d of the master base station 1 is generated. ｍｓｔ＿ｔｒｓｍ to the generating unit 16, and m transmission data d １＿ｔｒｓｍ ~d ｍ＿ｔｒｓｍ to the control unit 13.

[0091] The control unit 13 receives the transmission data D_trsm and m wireless transmission rates r １ ~r ｍ to the generating unit 15, and then the m transmission data d １＿ｔｒｓｍ ~d ｍ＿ｔｒｓｍ When it receives the notification from the generating unit 15, it generates a notification of the transmission timing.

[0092] When the control unit 13 generates a notification of the transmission timing, it outputs the generated notification of the transmission timing to the radio unit 14 and controls the radio unit 14 to transmit the notification of the transmission timing to m slave base stations via radio communication using the channel Ch_JT.

[0093] The control unit 13 also receives m pieces of transmission data d １＿ｔｒｓｍ ~d ｍ＿ｔｒｓｍ to the transmitting unit 17, and m pieces of transmission data d １＿ｔｒｓｍ ~d ｍ＿ｔｒｓｍ to the m slave base stations, respectively.

[0094] Furthermore, the control unit 13 receives the transmission data d of the master base station 1 from the generation unit 15. ｍｓｔ＿ｔｒｓｍ Based on this, the master base station 1 transmits the frame F ｍｓｔ＿ｔｒｓｍ and generates the generated transmission frame F ｍｓｔ＿ｔｒｓｍ to the wireless unit 14.

[0095] Thereafter, the control unit 13 refers to the timer and when the transmission timing comes, the control unit 13 transmits the transmission frame F ｍｓｔ＿ｔｒｓｍ to the wireless device 3. ＩＳＴＲ to the wireless unit 14, and receives the transmission frame F of the master base station 1 from the generating unit 16 by wireless communication using the channel Ch_JT. ｍｓｔ＿ｔｒｓｍ to the wireless device 3.

[0096] The control unit 13 outputs an instruction signal S ＩＳＴＲ to the wireless unit 14, and then receives a Block Ack from the wireless unit 14. The wireless device 3 then transmits a transmission frame F ｍｓｔ＿ｔｒｓｍ , F １＿ｔｒｓｍ ~F ｍ＿ｔｒｓｍ Detects that a message has been received.

[0097] On the other hand, when the control unit 13 determines that joint transmission JT between the master base station 1 and m slave base stations is not possible, it outputs the transmission data D_trsm to the generation unit 16, generates a transmission frame F_trsm including the transmission data D_trsm, and controls the generation unit 16 to output the generated transmission frame F_trsm to the wireless unit 14.

[0098] Then, the control unit 13 receives the Block Ack from the wireless unit 14 and detects that the wireless device 3 has received the transmission frame F_trsm transmitted only by the master base station 1 .

[0099] If the control unit 13 determines that joint transmission JT between the master base station 1 and the m slave base stations is not possible and does not transmit the transmission data D_trsm to the wireless device 3, it discards the transmission data D_trsm.

[0100] When the wireless unit 14 receives the RTS from the control unit 13, it transmits the RTS to the n slave base stations 2-1 to 2-n and the wireless device 3 via the antenna 11 by wireless communication using the channel Ch_JT.

[0101] Furthermore, the wireless unit 14 receives a CTS from the wireless device 3 via the antenna 11 by wireless communication using the channel Ch_JT, and outputs the received CTS to the control unit 13 .

[0102] After that, the wireless unit 14 transmits a confirmation frame F Ｓ＿ＰＢ When the control unit 13 receives the confirmation frame F via the antenna 11 by wireless communication using the channel Ch_JT, Ｓ＿ＰＢ is transmitted to n slave base stations 2-1 to 2-n.

[0103] Then, the wireless unit 14 transmits n response frames F via the antenna 11 by wireless communication using the channel Ch_JT. ＲＳＰ are received from the n slave base stations 2-1 to 2-n, respectively, and the received n response frames F ＲＳＰ is output to the control unit 13.

[0104] Furthermore, when the radio unit 14 receives a notification of the transmission timing from the control unit 13, it transmits the notification of the transmission timing to the m slave base stations via the antenna 11 by radio communication using the channel Ch_JT.

[0105] Thereafter, the wireless unit 14 transmits an instruction signal S ＩＳＴＲ from the control unit 13, and the transmission frame F ｍｓｔ＿ｔｒｓｍ from the generating unit 16, an instruction signal S ＩＳＴＲ In response to this, a transmission frame F is transmitted via the antenna 11 by wireless communication using the channel Ch_JT. ｍｓｔ＿ｔｒｓｍ to the wireless device 3.

[0106] The wireless unit 14 transmits a transmission frame F ｍｓｔ＿ｔｒｓｍ After transmitting the Block Ack, the control unit 13 receives a Block Ack from the wireless device 3 by wireless communication using the channel Ch_JT, and outputs the received Block Ack to the control unit 13.

[0107] Furthermore, the wireless unit 14 receives a transmission frame F_trsm from the generating unit 16 when joint transmission JT is not possible and the master base station 1 only transmits transmission data D_trsm to the wireless device 3 .

[0108] Then, the wireless unit 14 transmits the transmission frame F_trsm to the wireless device 3 via the antenna 11 by wireless communication using the channel Ch_JT.

[0109] The generation unit 15 calculates the data amount D of the transmission data D_trsm, the wireless transmission rate r of the master base station 1, and the m wireless transmission rates r of the m slave base stations. １ ~r ｍ is received from the control unit 13.

[0110] Then, the generation unit 15 calculates the data amount D of the transmission data D_trsm, the wireless transmission rate r of the master base station 1, and the m wireless transmission rates r of the m slave base stations. １ ~r ｍ Substituting this into equation (1) gives the data volume d ｉ The calculation is performed for all of i=1 to m, and the amount of m data d １ ~dｍ Calculate.

[0111]

[0112] In formula (1A), d ｉ is the amount of data allocated to the i-th slave base station, and r ｉ is the wireless transmission rate of the i-th slave base station (= the wireless transmission rate of the transmission data in the slave base station for which the data amount is to be calculated), R is expressed by equation (1B), and D is the total amount of data transmitted to the wireless device 3. In equation (1B), r is the wireless transmission rate of the transmission data in the master base station 1, and r ｉ is the wireless transmission rate of the transmitted data at the slave base station i capable of joint transmission JT included in the set M. As a result, R is the sum of the wireless transmission rate of the master base station 1 and the wireless transmission rates of all slave base stations capable of joint transmission JT.

[0113] Furthermore, in equation (1), when all of the n slave base stations 2-1 to 2-n are capable of performing joint transmission JT, the set M in equation (1) is M={iεN|1≦i≦n}.

[0114] On the other hand, in equation (1), if m slave base stations out of n slave base stations 2-1 to 2-n are capable of performing joint transmission JT, the set M in equation (1) is M = {i∈N|1≦i≦m}.

[0115] Then, according to equation (1), the generating unit 15 calculates the data amount d ｉ The transmission data d at the slave base station to be calculated ｉ＿ｔｒｓｍ Wireless transmission speed r ｉ and the transmission data d ｍｓｔ＿ｔｒｓｍ and m wireless transmission rates r in m slave base stations. １ ~r ｍ (or n wireless transmission rates r １ ~r ｎ ) and the data amount d of the slave base station to be calculated. ｉ Calculate.

[0116] In other words, the generation unit 15 assigns the largest amount of data to the slave base station with the fastest wireless transmission speed r, the second largest amount of data to the slave base station with the second fastest wireless transmission speed r, and so on, similarly assigning the second smallest amount of data to the slave base station with the second slowest wireless transmission speed r and the smallest amount of data to the slave base station with the slowest wireless transmission speed r.

[0117] The generating unit 15 calculates m data amounts d for all m slave base stations according to the formula (1). １ ~d ｍ When the amount of data d １ ~d ｍ The sum of (= d １ +d ２ +...+d ｍ ) and add it to the total data amount D (= d １ +d ２ +...+d ｍ ) to obtain the data amount d ｍｓｔ (=D-(d １ +d ２ +...+d ｍ Then, the generation unit 15 calculates the calculated data amount d １ ~d ｍ , d ｍｓｔ (=(m+1) data amount d １ ~d ｍ＋１ ) based on the transmission data d ｍｓｔ＿ｔｒｓｍ and m transmission data d of m slave base stations １＿ｔｒｓｍ ~d ｍ＿ｔｒｓｍ and generate.

[0118] Then, the generating unit 15 generates m pieces of transmission data d １＿ｔｒｓｍ ~d ｍ＿ｔｒｓｍ to the control unit 13, and the transmission data d ｍｓｔ＿ｔｒｓｍ to the generation unit 16.

[0119] The generating unit 16 generates the transmission data d ｍｓｔ＿ｔｒｓｍThe generating unit 16 receives the transmission data d ｍｓｔ＿ｔｒｓｍ Based on the transmitted frame F ｍｓｔ＿ｔｒｓｍ and generates the generated transmission frame F ｍｓｔ＿ｔｒｓｍ to the wireless unit 14.

[0120] Furthermore, when joint transmission JT between the master base station 1 and the m slave base stations is not possible, the generation unit 16 receives transmission data D_trsm from the control unit 13. Then, the generation unit 16 generates a transmission frame F_trsm based on the transmission data D_trsm and outputs the generated transmission frame F_trsm to the wireless unit 14.

[0121] The transmitting unit 17 is connected to the backhaul 4. The transmitting unit 17 receives m pieces of transmission data d １＿ｔｒｓｍ ~d ｍ＿ｔｒｓｍ When the control unit 13 receives the m pieces of transmission data d １＿ｔｒｓｍ ~d ｍ＿ｔｒｓｍ are transmitted to m slave base stations, respectively.

[0122] Fig. 3 is a schematic diagram of the slave base station 2-1 shown in Fig. 1. Referring to Fig. 3, the slave base station 2-1 includes an antenna 21, a radio unit 22, a receiving unit 23, a control unit 24, and a generating unit 25.

[0123] The radio unit 22 receives the RTS from the master base station 1 via the antenna 21 by radio communication using the channel Ch_JT, and outputs the received RTS to the control unit 24 .

[0124] The wireless unit 22 also transmits a confirmation frame F via the antenna 21 by wireless communication using the channel Ch_JT. Ｓ＿ＰＢ from the master base station 1, and the received confirmation frame F Ｓ＿ＰＢ to the control unit 24.

[0125] After that, the wireless unit 22 transmits a confirmation frame F Ｓ＿ＰＢ Response frame F to ＲＳＰWhen the control unit 24 receives the response frame F via the antenna 21 by wireless communication using the channel Ch_JT, ＲＳＰ to the master base station 1.

[0126] Furthermore, the radio unit 22 receives a notification of the transmission timing from the master base station 1 via the antenna 21 by radio communication using the channel Ch_JT, and outputs the received notification of the transmission timing to the control unit 24 .

[0127] Furthermore, when the wireless unit 22 receives the transmission frame from the control unit 24, the wireless unit 22 transmits the transmission frame F via the antenna 21 by wireless communication using the channel Ch_JT. １＿ｔｒｓｍ to the wireless device 3.

[0128] The receiving unit 23 is connected to the backhaul 4. The receiving unit 23 receives the transmission data d from the transmitting unit 17 of the master base station 1 via the backhaul 4. １＿ｔｒｓｍ and receives the received transmission data d １＿ｔｒｓｍ to the control unit 24.

[0129] The control unit 24 receives the RTS from the radio unit 22. The control unit 24 also receives the confirmation frame F Ｓ＿ＰＢ from the wireless unit 22. The control unit 24 then receives a confirmation frame F Ｓ＿ＰＢ In response to this, the slave base station 2-1 determines whether joint transmission JT with the master base station 1 is possible.

[0130] In this case, for example, if the slave base station 2-1 is conducting wireless communication with a wireless device other than the wireless device 3, the control unit 24 determines that the slave base station 2-1 is unable to conduct joint transmission JT with the master base station 1, and if the slave base station 2-1 is not conducting wireless communication with a wireless device other than the wireless device 3, the control unit 24 determines that the slave base station 2-1 is able to conduct joint transmission JT with the master base station 1.

[0131] Alternatively, the following method may be used to determine whether joint transmission JT is possible: The radio unit 22 detects a received signal strength indicator (RSSI) when transmitting radio waves on channel Ch-JT via the antenna 21, and outputs the detected received signal strength RSSI to the control unit 24. When the received signal strength RSSI received from the radio unit 22 is equal to or less than a threshold RSSI_th (e.g., −83 dBm), the control unit 24 determines that no other radio communication is taking place and that joint transmission JT is possible. On the other hand, when the received signal strength RSSI is greater than the threshold RSSI_th, the control unit 24 determines that another radio communication is taking place and that joint transmission JT is impossible.

[0132] When the control unit 24 determines that the joint transmission JT is possible, it sends a response frame F containing "JT_OK". ＲＳＰ Then, the control unit 24 generates a response frame F ＲＳＰ to the wireless unit 22, and a response frame F including "JT_OK" is transmitted by wireless communication using the channel Ch_JT. ＲＳＰ to the master base station 1.

[0133] On the other hand, when the control unit 24 determines that the joint transmission JT is not possible, it sends a response frame F containing "JT_NG". ＲＳＰ Then, the control unit 24 generates a response frame F ＲＳＰ to the wireless unit 22, and a response frame F including "JT_NG" is transmitted by wireless communication using the channel Ch_JT. ＲＳＰ to the master base station 1.

[0134] The control unit 24 also receives notification of the transmission timing from the wireless unit 22 and transmits the transmission data d １＿ｔｒｓｍ The control unit 24 receives the transmission data d １＿ｔｒｓｍ to the generating unit 25, and the transmission data d １＿ｔｒｓｍThe generating unit 25 is controlled to perform the frame generating process based on the above.

[0135] Thereafter, the control unit 24 receives the transmission data d １＿ｔｒｓｍ A transmission frame F including １＿ｔｒｓｍ (PPDU1) from generation unit 25.

[0136] Then, when the transmission timing arrives, the control unit 24 sends the transmission data d １＿ｔｒｓｍ A transmission frame F including １＿ｔｒｓｍ (PPDU1) to the wireless unit 22, and transmits a transmission frame F via wireless communication using the channel Ch_JT. １＿ｔｒｓｍ The wireless unit 22 is controlled to transmit (PPDU1) to the wireless device 3.

[0137] The generating unit 25 generates the transmission data d １＿ｔｒｓｍ When the control unit 24 receives the transmitted data d １＿ｔｒｓｍ A transmission frame F including １＿ｔｒｓｍ A process for generating a transmission frame F (PPDU1) is executed. １＿ｔｒｓｍ (PPDU1) is output to the control unit 24.

[0138] Each of the slave base stations 2-2 to 2-n shown in FIG. 1 has the same configuration as the slave base station 2-1 shown in FIG.

[0139] Fig. 4 is a schematic diagram of the wireless device 3 shown in Fig. 1. Referring to Fig. 4, the wireless device 3 includes an antenna 31, a wireless unit 32, a control unit 33, and an application 34.

[0140] The radio unit 32 receives the RTS from the master base station 1 via the antenna 31 by radio communication using the channel Ch_JT, and outputs the received RTS to the control unit 33 .

[0141] Thereafter, the wireless unit 32 receives the CTS from the control unit 33. Then, the wireless unit 32 transmits the CTS to the master base station 1 via the antenna 31 by wireless communication using the channel Ch_JT.

[0142] The wireless unit 32 also transmits a transmission frame F via the antenna 31 by wireless communication using the channel Ch_JT. ｍｓｔ＿ｔｒｓｍ , F １＿ｔｒｓｍ ~F ｍ＿ｔｒｓｍ (=(m+1) transmission frames) are received from the master base station 1 and m slave base stations, respectively, and the received transmission frames F ｍｓｔ＿ｔｒｓｍ , F １＿ｔｒｓｍ ~F ｍ＿ｔｒｓｍ (=(m+1) transmission frames) to the control unit 33.

[0143] Thereafter, when the radio unit 32 receives the block Ack from the control unit 33, it transmits the block Ack to the master base station 1 via the antenna 31 by radio communication using the channel Ch_JT.

[0144] Furthermore, when joint transmission JT is not possible, the wireless unit 32 receives a transmission frame F_trsm (= a frame including transmission data D_trsm) from the master base station 1 via the antenna 31 by wireless communication using the channel Ch_JT, and outputs the received transmission frame F_trsm (= a frame including transmission data D_trsm) to the control unit 33.

[0145] Thereafter, when the radio unit 32 receives the block Ack from the control unit 33, it transmits the block Ack to the master base station 1 via the antenna 31 by radio communication using the channel Ch_JT.

[0146] The control unit 33 receives the RTS from the radio unit 32. Then, the control unit 33 receives from the radio unit 32 the received signal strength RSSI when radio waves are transmitted on the channel Ch-JT via the antenna 31, and when the received signal strength RSSI is equal to or less than the threshold RSSI_th, determines that no other radio communication is taking place, and when the received signal strength RSSI is greater than the threshold RSSI_th, determines that another radio communication is taking place.

[0147] When the control unit 33 determines that no other wireless communication is taking place, it outputs a CTS to the wireless unit 32 and controls the wireless unit 32 to transmit the CTS to the master base station 1 via wireless communication using channel Ch_JT.

[0148] Thereafter, the control unit 33 transmits the transmission frame F ｍｓｔ＿ｔｒｓｍ , F １＿ｔｒｓｍ ~F ｍ＿ｔｒｓｍ (=(m+1) transmission frames) from the wireless unit 32, the transmission frame F ｍｓｔ＿ｔｒｓｍ , F １＿ｔｒｓｍ ~F ｍ＿ｔｒｓｍ (=(m+1) transmission frames) and outputs the transmission data D_trsm to the application 34.

[0149] Subsequently, the control unit 33 outputs the block acknowledgment to the radio unit 32 and controls the radio unit 32 to transmit the block acknowledgment to the master base station 1 by radio communication using the channel Ch_JT.

[0150] Furthermore, when the control unit 33 receives a transmission frame F_trsm (= a frame including transmission data D_trsm) from the wireless unit 32 , it decodes the transmission frame (= a frame including transmission data D_trsm) and outputs the transmission data D_trsm to the application 34 .

[0151] Thereafter, the control unit 33 outputs the block acknowledgment to the radio unit 32 and controls the radio unit 32 to transmit the block acknowledgment to the master base station 1 by radio communication using the channel Ch_JT.

[0152] The application 34 receives the transmission data D_trsm from the control unit 33 .

[0153] FIG. 5 is a conceptual diagram for explaining a method for generating transmission data in the master base station 1 and m slave base stations.

[0154] 5, the transmission data D_trsm has a data amount D. The generation unit 15 of the master base station 1 generates the data amount d to be allocated to m slave base stations by the above-mentioned method. １ ~dｍ , the data amount d from the beginning of the transmission data D_trsm is calculated. １ Cut out the part and reduce the data volume d １ Transmission data d having １＿ｔｒｓｍ Generate.

[0155] Next, the generating unit 15 calculates the amount of data d １ The data amount d from the beginning of the cut transmission data D_trsm ２ Cut out the part and reduce the data volume d ２ Transmission data d having ２＿ｔｒｓｍ Generate.

[0156] Furthermore, the generating unit 15 generates the data amount d １ +d ２ The data amount d from the beginning of the cut transmission data D_trsm ３ Cut out the part and reduce the data volume d ３ Transmission data d having ３＿ｔｒｓｍ Generate.

[0157] Similarly, the generating unit 15 generates the data amount d １ +d ２ +...+d ｍ－１ The data amount d from the beginning of the cut transmission data D_trsm ｍ Cut out the part and reduce the data volume d ｍ Transmission data d having ｍ＿ｔｒｓｍ Generate.

[0158] Then, the generation unit 15 calculates the remaining data amount (=D-(d １ +d ２ +...+d ｍ )) transmission data d ｍｓｔ＿ｔｒｓｍ Generate.

[0159] Then, the generating unit 15 generates the transmission data d １＿ｔｒｓｍ ~d ｍ＿ｔｒｓｍ are the transmission data to be transmitted to m slave base stations, and the transmission data d ｍｓｔ＿ｔｒｓｍ is the transmission data of the master base station 1.

[0160] Fig. 6 is a conceptual diagram showing the structure of a transmission frame, which is a structure of a transmission frame in IEEE 802.11a.

[0161] Referring to FIG. 6, a transmission frame PPDU (PLCP Protocol Data Unit) includes RATE, Reserved, Length, Parity, Tail, Service, PSDU, Tail, and Padding.

[0162] RATE, Reserved, Length, Parity, Tail and Service make up the PLCP Header.

[0163] A PLCP Service Data Unit (PSDU) follows the PLCP Header and is passed from a higher layer to the physical layer. PLCP stands for Physical Layer Convergence Protocol.

[0164] Since a bit-tailing convolutional code is used as the error correction code in the physical layer (PHY layer), tail bits are added after the PSDU in the physical layer (PHY layer).

[0165] The end of the packet is terminated with an Orthogonal Frequency Division Multiplexing (OFDM) symbol, and bits are padded as necessary.

[0166] RATE, Reserved, Length, Parity, and Tail constitute Signal, and Service, PSDU, Tail, and Padding constitute Data.

[0167] Therefore, the PPDU consists of a signal and data. When the master base station 1 generates a transmission frame, the transmission data d ｍｓｔ＿ｔｒｓｍ When each of the m slave base stations generates a transmission frame, the transmission data d ｉ＿ｔｒｓｍ (i=1 to m) is stored in Data.

[0168] In the “transmission frame generation process”, the master base station 1 generates a transmission frame F having the configuration shown in FIG. ｍｓｔ＿ｔｒｓｍ (=PPDU0) is generated.

[0169] In addition, the slave base station 2-1 generates a transmission frame F having the configuration shown in FIG. １＿ｔｒｓｍ (=PPDU1), and the slave base station 2-2 generates a transmission frame F having the configuration shown in FIG. ２＿ｔｒｓｍ (=PPDU2) is generated.

[0170] That is, the master base station 1 receives the data amount d ｍｓｔ Based on the transmitted frame F ｍｓｔ＿ｔｒｓｍ The slave base station 2-1 executes a transmission frame generation process, which is a process for generating a data amount d １ Based on the transmitted frame F １＿ｔｒｓｍ The transmission frame generation process is executed to generate a transmission frame (=PPDU1).

[0171] Fig. 7 is a schematic diagram showing frame processing in the communication system 10 shown in Fig. 1. Note that Fig. 7 shows only the slave base station 2-1 out of the m slave base stations.

[0172] Referring to FIG. 7, the master base station 1 transmits an RTS to the slave base station 2-1 and the wireless device 3 by wireless communication using the channel Ch_JT.

[0173] Then, the slave base station 2-1 and the wireless device 3 receive the RTS from the master base station 1 by wireless communication using the channel Ch_JT.

[0174] Thereafter, the wireless device 3 transmits a CTS to the master base station 1 by wireless communication using the channel Ch_JT.

[0175] Then, when the master base station 1 receives a CTS from the wireless device 3 via wireless communication using the channel Ch_JT, it sends a confirmation frame F Ｓ＿ＰＢ and transmits a confirmation frame F via wireless communication using the channel Ch_JT. Ｓ＿ＰＢto the slave base station 2-1.

[0176] The slave base station 2-1 transmits a confirmation frame F via wireless communication using the channel Ch_JT. Ｓ＿ＰＢ When the slave base station 2-1 receives the JT_OK signal from the master base station 1, it determines whether or not joint transmission JT with the master base station 1 is possible. When the slave base station 2-1 determines that joint transmission JT with the master base station 1 is possible, it sends a response frame F including "JT_OK". ＲＳＰ When it is determined that joint transmission JT with the master base station 1 is impossible, a response frame F ＲＳＰ Generate.

[0177] Then, the slave base station 2-1 transmits a confirmation frame F via wireless communication using the channel Ch_JT. Ｓ＿ＰＢ Response frame F to ＲＳＰ (Response frame F containing "JT_OK" or "JT_NG" ＲＳＰ ) to the master base station 1.

[0178] The master base station 1 transmits a response frame F ＲＳＰ is received from the slave base station 2-1.

[0179] Then, the master base station 1 sends a response frame F ＲＳＰ (Response frame F containing "JT_OK" ＲＳＰ ) and then determines whether joint transmission JT is possible, the amount of data d ｍｓｔ , d １ Calculate.

[0180] Thereafter, the master base station 1 executes the following steps (1) to (3).

[0181] (1) The master base station 1 transmits a "transmission timing notification" to the slave base station 2-1 by wireless communication using the channel Ch_JT, and (2) the master base station 1 transmits the transmission data d １＿ｔｒｓｍ (data volume d １(3) the master base station 1 and the slave base station 2-1 perform a process of generating a transmission frame in parallel with (1).

[0182] In this case, the above (2) is executed earliest in terms of time, the above (1) is executed in parallel with (2), and after (2) is finished, the above (3) is executed in parallel with (1). As a result, the time required for the allocation of transmission data (2) in the master base station 1 partially overlaps with the time required for the transmission of the transmission timing notification (1), and the time required for the generation process of the transmission frame (3) in the master base station 1 and the slave base station 2-1 partially overlaps with the time required for the transmission of the transmission timing notification (1).

[0183] The allocation of transmission data in the master base station 1 (2) and the generation of transmission frames in the master base station 1 and slave base station 2-1 (3) are executed serially.

[0184] Here, (2) the master base station 1 transmits the transmission data d １＿ｔｒｓｍ (data volume d １ ) to the slave base station 2-1 in parallel with (1). １＿ｔｒｓｍ (data volume d １ The time required to distribute the transmission data (transmission data having the value .intg., .gt.) to the slave base station 2-1 and the time required to transmit the notification of the transmission timing in (1) overlap at least partially.

[0185] Furthermore, (3) the master base station 1 and the slave base station 2-1 perform the process of generating the transmission frame in parallel with (1), which means that the time required for the process of generating the transmission frame and the time required for sending the notification of the transmission timing in (1) overlap for at least a portion of the time length.

[0186] After the process of generating the transmission frame is completed, the master base station 1 and the slave base station 2-1 each transmit a transmission frame Fｍｓｔ＿ｔｒｓｍ (=PPDU0),F １＿ｔｒｓｍ (=PPDU1) is simultaneously transmitted to wireless device 3.

[0187] Then, the wireless device 3 receives a transmission frame F from the master base station 1 by wireless communication using the channel Ch_JT. ｍｓｔ＿ｔｒｓｍ (=PPDU0) is received from the slave base station 2-1, and the transmission frame F １＿ｔｒｓｍ Upon receiving (=PPDU1), the master base station 1 transmits a Block Ack to the master base station 1 via wireless communication using channel Ch_JT.

[0188] Then, the master base station 1 receives a Block Ack from the wireless device 3 by wireless communication using the channel Ch_JT, and the wireless device 3 receives a transmission frame F transmitted by the joint transmission JT between the master base station 1 and the slave base station 2-1. ｍｓｔ＿ｔｒｓｍ (=PPDU0),F １＿ｔｒｓｍ (=PPDU1) is received.

[0189] Therefore, the master base station 1 transmits a “transmission timing notification” to the slave base station 2-1 and transmits the transmission data d via the backhaul 4. １＿ｔｒｓｍ to the slave base station 2-1, and after the master base station 1 and the slave base station 2-1 perform the transmission frame generation process, they each generate a transmission frame F ｍｓｔ＿ｔｒｓｍ (=PPDU0),F １＿ｔｒｓｍ (=PPDU1) is transmitted to wireless device 3.

[0190] In FIG. 7, the master base station 1 receives the １ After transmitting the RTS to the slave base station 2-1 and the wireless device 3 at time t ２ The block Ack is received from the wireless device 3 at .

[0191] As a result, the time required for data transmission from the master base station 1 and the slave base station 2-1 to the wireless device 3 is t ２ -t １ is.

[0192] 8 is a schematic diagram showing conventional frame processing. Referring to FIG. 8, in the conventional frame processing, the master base station 1 transmits a notification of transmission timing to the slave base station 2-1 by wireless communication using channel Ch_JT, and then allocates transmission data by wireless communication, and thereafter the master base station 1 and the slave base station 2-1 perform processing to generate a transmission frame.

[0193] That is, in FIG. 8, the transmission of the notification of the transmission timing to the slave base station 2-1, the allocation of the transmission data, and the generation of the transmission frame are executed serially.

[0194] As a result, the master base station 1 and the slave base station 2-1 each transmit a transmission frame F, which is a frame of the physical layer (PHY layer), by wireless communication using the channel Ch_JT. ｍｓｔ＿ｔｒｓｍ (=PPDU0),F １＿ｔｒｓｍ The timing at which the transmission of PPDU1 (=PPDU1) to the wireless device 3 is completed is timing t ３ becomes.

[0195] Then, the master base station 1 receives the signal at timing t ３ A timing t later than ４ The block Ack is received from the wireless device 3 at .

[0196] Then, at timing t ４ 7, the timing t ２ This is a later timing than that.

[0197] 7, in the communication system 10 according to the first embodiment, the master base station 1 allocates transmission data to the slave base stations 2-1 using the backhaul 4, which reduces the amount of wireless resources used compared to when allocating transmission data to the slave base stations 2-1 by wireless communication, thereby improving throughput.

[0198] Furthermore, as shown in FIG. 7, in the communication system 10 according to the first embodiment, the master base station 1 distributes transmission data to the slave base station 2-1 using the backhaul 4, and the master base station 1 and the slave base station 2-1 perform the process of generating a transmission frame, in parallel with the master base station 1 transmitting a notification of the transmission timing to the slave base station 2-1 by wireless communication using channel Ch_JT. Therefore, compared to the frame processing shown in FIG. 8, the time required to transmit transmission data to the wireless device 3 can be shortened, and throughput can be further improved.

[0199] Fig. 9 is another schematic diagram showing frame processing in the communication system 10 shown in Fig. 1. Fig. 9 shows frame processing in the case where the number of slave base stations is two.

[0200] 9, the master base station 1 transmits an RTS to the slave base stations 2-1 and 2-2 and the wireless device 3 by wireless communication using the channel Ch_JT.

[0201] Then, the slave base stations 2-1 and 2-2 and the wireless device 3 receive the RTS through wireless communication using the channel Ch_JT.

[0202] Thereafter, the wireless device 3 transmits a CTS to the master base station 1 by wireless communication using the channel Ch_JT.

[0203] Then, when the master base station 1 receives the CTS via wireless communication using the channel Ch_JT, it transmits a confirmation frame F via wireless communication using the channel Ch_JT. Ｓ＿ＰＢ to the slave base stations 2-1 and 2-2.

[0204] The slave base stations 2-1 and 2-2 transmit a confirmation frame F via wireless communication using the channel Ch_JT. Ｓ＿ＰＢ is received from the master base station 1.

[0205] Then, each of the slave base stations 2-1 and 2-2 determines whether joint transmission JT with the master base station 1 is possible, and when it determines that joint transmission JT with the master base station 1 is possible, it sends a response frame F including "JT_OK".ＲＳＰ When it is determined that joint transmission JT with the master base station 1 is impossible, a response frame F ＲＳＰ The same is true for the slave base station 2-2.

[0206] Then, each of the slave base stations 2-1 and 2-2 transmits a confirmation frame F Ｓ＿ＰＢ Response frame F to ＲＳＰ (Response frame F containing "JT_OK" or "JT_NG" ＲＳＰ ) to the master base station 1.

[0207] The master base station 1 transmits a response frame F ＲＳＰ＿１ , F ＲＳＰ＿２ are received from the slave base stations 2-1 and 2-2, respectively.

[0208] Then, the master base station 1 sends a response frame F ＲＳＰ＿１ , F ＲＳＰ＿２ When it is determined that the joint transmission JT is possible based on the above, the master base station 1 determines the amount of data d to be allocated to each of the slave base stations 2-1 and 2-2. １ , d ２ Calculate.

[0209] Thereafter, the master base station 1 executes the following steps (1) to (3).

[0210] (1) The master base station 1 transmits a "transmission timing notification" to the slave base stations 2-1 and 2-2 by wireless communication using the channel Ch_JT, and (2) the master base station 1 transmits the transmission data d １＿ｔｒｓｍ (data volume d １ transmission data having the transmission data d ２＿ｔｒｓｍ (data volume d ２ (1) is performed in parallel with (3), and (4) the master base station 1 and the slave base stations 2-1 and 2-2 perform a process of generating a transmission frame.

[0211] In this case, the above (2) is executed earliest in terms of time, the above (1) is executed in parallel with (2), and after (2) is completed, the above (3) is executed in parallel with (1). As a result, the time required for the allocation of transmission data (2) in the master base station 1 partially overlaps with the time required for the transmission of the transmission timing notification (1), and the time required for the transmission frame generation process (3) in the master base station 1 and the slave base stations 2-1 and 2-2 partially overlaps with the time required for the transmission of the transmission timing notification (1).

[0212] The allocation of transmission data in the master base station 1 (2) and the generation of transmission frames in the master base station 1 and the slave base stations 2-1 and 2-2 (3) are executed serially.

[0213] Then, the master base station 1, the slave base station 2-1, and the slave base station 2-2 each transmit a transmission frame F by wireless communication using the channel Ch_JT in the joint transmission JT. ｍｓｔ＿ｔｒｓｍ (=PPDU0),F １＿ｔｒｓｍ (=PPDU1),F ２＿ｔｒｓｍ (=PPDU2) is simultaneously transmitted to wireless device 3.

[0214] Then, the wireless device 3 receives a transmission frame F from the master base station 1 by wireless communication using the channel Ch_JT. ｍｓｔ＿ｔｒｓｍ (=PPDU0) is received from the slave base station 2-1, and the transmission frame F １＿ｔｒｓｍ (=PPDU1) and receives the transmission frame F ２＿ｔｒｓｍ (=PPDU2) and transmits a Block Ack to the master base station 1 via wireless communication using channel Ch_JT.

[0215] Then, the master base station 1 receives a Block Ack from the wireless device 3 by wireless communication using the channel Ch_JT, and the wireless device 3 transmits a transmission frame F via joint transmission JT between the master base station 1 and the slave base stations 2-1 and 2-2. ｍｓｔ＿ｔｒｓｍ (=PPDU0),F １＿ｔｒｓｍ (=PPDU1),F ２＿ｔｒｓｍ (=PPDU2) is received.

[0216] Therefore, the master base station 1 transmits a "transmission timing notification" to the slave base stations 2-1 and 2-2, and the master base station 1 distributes transmission data to the slave base stations 2-1 and 2-2 via the backhaul 4 in parallel with transmitting the "transmission timing notification" to the slave base stations 2-1 and 2-2. After that, the master base station 1 and the slave base stations 2-1 and 2-2 generate a transmission frame in parallel with transmitting the "transmission timing notification" to the slave base stations 2-1 and 2-2. Then, the master base station 1 and the slave base stations 2-1 and 2-2 each generate a transmission frame F ｍｓｔ＿ｔｒｓｍ (=PPDU0),F １＿ｔｒｓｍ (=PPDU1),F ２＿ｔｒｓｍ (=PPDU2) is transmitted to wireless device 3.

[0217] Therefore, as shown in Figure 9, in the communication system 10 according to embodiment 1, the master base station 1 allocates transmission data to the slave base stations 2-1 and 2-2 using the backhaul 4, and therefore the amount of wireless resources used is less than when allocating transmission data to the slave base stations 2-1 and 2-2 by wireless communication, as shown in Figure 8, and therefore the throughput can be improved compared to the case shown in Figure 8.

[0218] Furthermore, as shown in FIG. 9, in the communication system 10 according to the first embodiment, the master base station 1 transmits a notification of the transmission timing to the slave base stations 2-1 and 2-2 by wireless communication using the channel Ch_JT, the master base station 1 allocates the transmission data to the slave base stations 2-1 and 2-2 using the backhaul 4 in parallel with the transmission of the "notification of the transmission timing" to the slave base stations 2-1 and 2-2, and the master base station 1 and the slave base stations 2-1 and 2-2 perform the process of generating the transmission frame in parallel with the transmission of the "notification of the transmission timing" to the slave base stations 2-1 and 2-2. Therefore, compared to the frame processing shown in FIG. 8, the time required to transmit the transmission data to the wireless device 3 can be shortened, and the throughput can be further improved.

[0219] In FIG. 7, the frame processing has been described for the case where there is one slave base station, and in FIG. 9, the frame processing has been described for the case where there are two slave base stations.

[0220] As a result, the only change in frame processing due to the addition of one slave base station is the confirmation frame F Ｓ＿ＰＢ The number of response frames F ＲＳＰ 9 , the number of slave base stations, calculation of the amount of data to be allocated to the slave base stations, allocation of transmission data to the slave base stations, and the number of transmission frame PPDUs. Therefore, if frame processing for the case where there is one slave base station and frame processing for the case where there are two slave base stations are explained, frame processing can generally be performed in the same manner as the frame processing shown in FIG. 9 even when there are m slave base stations capable of joint transmission JT.

[0221] Figures 10 and 11 are first and second flowcharts, respectively, for explaining the operation of communication system 10 shown in Figure 1. Referring to Figure 10, when operation of communication system 10 starts, master base station 1 transmits an RTS to slave base stations (=n slave base stations 2-1 to 2-n) and wireless device 3 by wireless communication using channel Ch_JT (step S1).

[0222] Then, the slave base stations (= n slave base stations 2-1 to 2-n) receive the RTS from the master base station 1 via wireless communication using channel Ch_JT (step S2), and the wireless device 3 receives the RTS from the master base station 1 via wireless communication using channel Ch_JT (step S3).

[0223] Thereafter, the wireless device 3 transmits a CTS to the master base station 1 by wireless communication using the channel Ch_JT (step S4).

[0224] The master base station 1 receives the CTS from the wireless device 3 through wireless communication using the channel Ch_JT (step S5).

[0225] Then, the master base station 1 transmits a confirmation frame F via wireless communication using the channel Ch_JT to confirm whether or not the joint transmission JT can be started. Ｓ＿ＰＢ to the slave base stations (=n slave base stations 2-1 to 2-n) (step S6).

[0226] The slave base stations (=n slave base stations 2-1 to 2-n) transmit a confirmation frame F by wireless communication using the channel Ch_JT. Ｓ＿ＰＢ When the master base station 1 receives the confirmation frame F Ｓ＿ＰＢ Response frame F indicating whether joint transmission JT is possible or not ＲＳＰ to the master base station 1 (step S7).

[0227] Then, the master base station 1 transmits a response frame F ＲＳＰ are received from the slave base stations (=n slave base stations 2-1 to 2-n) (step S8).

[0228] Then, the master base station 1 sends a response frame F ＲＳＰ (=n response frames F ＲＳＰ ) and then it is determined whether joint transmission JT is possible (step S9).

[0229] In this case, the master base station 1 sends a response frame F ＲＳＰ (=n response frames F ＲＳＰ If the response frame F contains "JT_OK", it is determined that the joint transmission JT is possible, and the response frame F ＲＳＰ (=n response frames F ＲＳＰ If all of the above) include "JT_NG", it is determined that joint transmission JT is not possible.

[0230] If it is determined in step S9 that joint transmission JT is possible, the master base station 1 calculates the amount of data to be distributed to the slave base stations (=m slave base stations) (step S10).

[0231] Then, (1) the master base station 1 transmits a notification of the transmission timing to the slave base stations (= m slave base stations capable of joint transmission JT) via in-band (= via wireless communication using the same channel as the channel when the master base station and each of the m slave base stations transmit data to the wireless device), (2) the master base station 1 distributes the transmission data to the slave base stations (= m slave base stations) via the backhaul 4 in parallel with (1), and (3) the master base station 1 and the slave base stations (= m slave base stations) perform a transmission frame generation process in parallel with (1) (step S11).

[0232] Then, after step S11, the operation of the communication system 10 proceeds to step S12 in FIG. 11, and when it is determined in step S9 that joint transmission JT is not possible, the operation of the communication system 10 proceeds to step S16 in FIG. 11.

[0233] Referring to FIG. 11, after step S11 in FIG. 10, the master base station 1 and the slave base stations (= m slave base stations) simultaneously transmit transmission data (transmission frames) to the wireless device 3 by wireless communication using channel Ch_JT (step S12).

[0234] The wireless device 3 receives data from the master base station 1 and the slave base stations (=m slave base stations) by wireless communication using the channel Ch_JT (step S13).

[0235] Then, the wireless device 3 transmits a Block Ack to the master base station 1 by wireless communication using the channel Ch_JT (step S14).

[0236] The master base station 1 receives the Block Ack from the wireless device 3 through wireless communication using the channel Ch_JT (step S15).

[0237] On the other hand, when it is determined in step S9 of FIG. 10 that joint transmission JT is not possible, only the master base station 1 transmits the transmission data D_trsm to the wireless device 3 by wireless communication using the channel Ch_JT, or stops transmitting data to the wireless device 3 (step S16).

[0238] Thereafter, the wireless device 3 determines whether or not data has been received from the master base station 1 by wireless communication using the channel Ch_JT (step S17).

[0239] In this case, if the master base station 1 transmits transmission data D_trsm in step S16, the wireless device 3 determines in step S17 that the data has been received, and if the master base station 1 stops transmitting data in step S16, the wireless device 3 determines in step S17 that the data has not been received.

[0240] If it is determined in step S17 that the wireless device 3 has received the data, the above-described steps S14 and S15 are executed in sequence.

[0241] After step S15, or when it is determined in step S17 that the wireless device 3 has not received data, the operation of the communication system 10 ends.

[0242] In the flowcharts shown in FIGS. 10 and 11, the following steps (1) to (3) are executed in step S11.

[0243] (1) The master base station 1 transmits a notification of the transmission timing to the slave base stations (= m slave base stations) via in-band (= via wireless communication using the same channel as the channel used when the master base station and each of the m slave base stations transmit data to the wireless device). (2) The master base station 1 distributes the transmission data to the slave base stations (= m slave base stations) via the backhaul 4 in parallel with (1). (3) The master base station 1 and the slave base stations (= m slave base stations) perform transmission frame generation processing in parallel with (1). Therefore, because the transmission data is distributed to the slave base stations (= m slave base stations) using the backhaul 4, it is possible to reduce the amount of wireless resources used compared to distributing the transmission data to the slave base stations (= m slave base stations) via wireless communication. As a result, it is possible to improve throughput.

[0244] Furthermore, the master base station 1 distributes transmission data to the slave base stations (= m slave base stations) using the backhaul 4, and the master base station 1 and the slave base stations (= m slave base stations) perform the process of generating transmission frames, in parallel with the master base station 1 transmitting notifications of transmission timing to the slave base stations (= m slave base stations) by wireless communication using channel Ch_JT, so the time required to transmit transmission data to the wireless device 3 can be further reduced and throughput can be further improved.

[0245] In the above-described first embodiment, in step S11 of FIG. 10, (2) does not have to be executed in parallel with (1), and (3) does not have to be executed in parallel with (1).

[0246] Even if (2) and (3) are not executed in parallel with (1), if the master base station 1 executes the allocation of transmission data to the slave base stations (= m slave base stations) via the backhaul 4, the amount of wireless resources used can be reduced compared to the case where transmission data is allocated to the slave base stations (= m slave base stations) by wireless communication, and the transmission frame F from the master base station 1 and the m slave base stations to the wireless device 3 can be reduced. ｍｓｔ＿ｔｒｓｍ , F１＿ｔｒｓｍ ~F ｍ＿ｔｒｓｍ This is because it can improve the throughput when transmitting.

[0247] (Example 1) When data is transmitted to a wireless device 3 using one master base station and two slave base stations A and B, the total amount of data transmitted to the wireless device 3, the wireless transmission rate of the one master base station, and the wireless transmission rate of the two slave base stations A and B are shown in Table 1.

[0248]

[0249] When the amount of data to be allocated to the slave base stations A and B is calculated by equation (1) using the total data amount and wireless transmission rate shown in Table 1, the amount of data d allocated to the slave base station A is １ is expressed as shown in equation (2), and the amount of data d ２ is expressed as shown in equation (3).

[0250]

[0251]

[0252] As a result, the amount of data allocated to the master base station is 250 [Kbytes] - (67.5 [Kbytes] + 82.5 [Kbytes]) = 100 [Kbytes].

[0253] The only difference between equation (2) and equation (3) is that “2.7×10 9 ” in equation (2) and “3.3×10 9 ” in equation (3) are the same, and the rest are the same.

[0254] And, the numerator of formula (2) is "2.7 × 10 ９ " is the wireless transmission rate of the slave base station A, and "3.3 × 10 ９ " is the wireless transmission rate of the slave base station B.

[0255] Therefore, the amount of data d allocated to the slave base station A and the slave base station B by the formula (1) is １ , d ２ can be calculated in proportion to the wireless transmission rate of the slave base station A and the wireless transmission rate of the slave base station B, respectively.

[0256] [Embodiment 2] Fig. 12 is a schematic diagram of a communication system according to embodiment 2. Referring to Fig. 12, a communication system 10A according to embodiment 2 is the same as communication system 10, except that master base station 1 of communication system 10 shown in Fig. 1 is replaced with a master base station 1A.

[0257] A master base station 1A, n slave base stations 2-1 to 2-n, and a wireless device 3 are arranged in a wireless communication space.

[0258] The master base station 1A is connected to n slave base stations 2-1 to 2-n via a backhaul 4.

[0259] The master base station 1A and the n slave base stations 2-1 to 2-n are located at mutually different positions, and the wireless device 3 is located within the communication range of wireless communication between the master base station 1A and the n slave base stations 2-1 to 2-n.

[0260] The master base station 1A performs wireless communication on the channel Ch_JT using the CSMA / CA method.

[0261] The master base station 1A receives n response frames F from n slave base stations 2-1 to 2-n. ＲＳＰ When it is determined that joint transmission JT is possible based on １ ~d ｍ Calculate.

[0262] Then, the master base station 1A calculates the data volume d １ ~d ｍ The required padding time is calculated using

[0263] Then, the master base station 1A executes the following (1A), (2A), and (3A).

[0264] (1A) The master base station 1A transmits a notification of transmission timing and padding PD having a length equal to the padding time to m slave base stations by wireless communication using the channel Ch_JT.

[0265] (2A) The master base station 1A transmits m transmission data, each having m data amounts, to m slave base stations via the backhaul 4 in parallel with the "transmission of padding PD" in (1A).

[0266] (3A) The master base station 1A and m slave base stations perform the transmission frame generation process in parallel with the "transmission of padding PD" in (1A).

[0267] Then, when the padding time ends (i.e., when the transmission of the padding PD ends), the master base station 1A and the m slave base stations simultaneously transmit transmission frames to the wireless device 3 by wireless communication using the channel Ch_JT.

[0268] In addition, the master base station 1A performs the same operations as the master base station 1 described above.

[0269] Fig. 13 is a schematic diagram of the master base station 1A shown in Fig. 12. Referring to Fig. 13, the master base station 1A is the same as the master base station 1, except that the control unit 13 of the master base station 1 shown in Fig. 2 is replaced with a control unit 13A and an arithmetic unit 18 is added.

[0270] 14 is a schematic diagram showing information held in advance by the control unit 13A. Referring to FIG. 14, the control unit 13A holds basic information B_info in advance. The basic information B_info is basic information used when calculating the padding time.

[0271] The basic information B_info includes the transmission speed, the transmission frame generation processing time, the transmission time T, and the SIFS time T ＳＩＦＳ Includes:

[0272] Address Add １ ~Add ｎ are the addresses of the slave base stations 2-1 to 2-n, and are associated with the transmission speed and the transmission frame generation processing time, respectively.

[0273] Transmission speed S １ is the master base station 1A and the address Add １is the transmission rate of the backhaul 4 between the slave base station 2-1 and the slave base station 2-2, and the transmission rate S ２ is the master base station 1A and the address Add ２ is the transmission rate of the backhaul 4 between the slave base station 2-2 and the slave base station 2-1, and similarly, the transmission rate S ｎ is the master base station 1A and the address Add ｎ is the transmission speed of the backhaul 4 between the slave base station 2-n having the same frequency band.

[0274] And the transmission speed S １ ~S ｎ are the addresses Add and １ ~Add ｎ can be associated with

[0275] In addition, the transmission frame generation processing time t １＿Ｆ is the address Add １ is the processing time for generating a transmission frame in the slave base station 2-1 having the transmission frame generation processing time t ２＿Ｆ is the address Add ２ The transmission frame generation processing time t ｎ＿Ｆ is the address Add ｎ is the processing time for generating a transmission frame in the slave base station 2-n having the above-mentioned sine wave number .

[0276] Then, the transmission frame generation processing time t １＿Ｆ ~t ｎ＿Ｆ are the addresses Add and １ ~Add ｎ can be associated with

[0277] Furthermore, the transmission time T is the transmission time for the notification of the transmission timing transmitted from the master base station 1A to each of the n slave base stations 2-1 to 2-n.

[0278] Furthermore, the SIFS time T ＳＩＦＳ is the time length of a SIFS.

[0279] The processing time for generating n transmission frames is t １＿Ｆ ~t ｎ＿ＦEach of the time slots includes a signaling delay time. ＳＩＦＳ is a value specified in IEEE 802.11.

[0280] The control unit 13A controls m slave base stations 2 １ ~2 ｍ Transmission data d to be allocated to １＿ｔｒｓｍ ~d ｍ＿ｔｒｓｍ The amount of data d １ ~d ｍ The control unit 13A receives the m slave base stations 2 １ ~2 ｍ m addresses Add １ ~Add ｍ m transmission rates S １ ~S ｍ is detected from the basic information B_info. Here, m transmission rates S １ ~S ｍ Each of these is the transmission rate S １ ~S ｎ It consists of either:

[0281] The control unit 13A also stores m addresses Add １ ~Add ｍ The m transmission frame generation processing times t １＿Ｆ ~t ｍ＿Ｆ is detected from the basic information B_info. Here, the processing time t １＿Ｆ ~t ｍ＿Ｆ are the transmission frame generation processing time t １＿Ｆ ~t ｎ＿Ｆ It consists of either:

[0282] Furthermore, the control unit 13A detects the transmission time T from the basic information B_info.

[0283] Furthermore, the control unit 13A determines the SIFS time T ＳＩＦＳ is detected from the basic information B_info.

[0284] Then, the control unit 13A calculates the m pieces of data amount d １ ~d ｍ, m transmission rates S １ ~S ｍ , m transmission frame generation processing time t １＿Ｆ ~t ｍ＿Ｆ , transmission time T and SIFS time T ＳＩＦＳ to the arithmetic unit 18, and the minimum required padding time T ｐａｄｄｉｎｇ＿ｎｄ The calculation unit 18 is controlled to calculate the following.

[0285] Padding time T ｐａｄｄｉｎｇ＿ｎｄ The calculation unit 18 calculates the amount of m data d １ ~d ｍ , m transmission rates S １ ~S ｍ , m transmission frame generation processing time t １＿Ｆ ~t ｍ＿Ｆ , transmission time T and SIFS time T ＳＩＦＳ is received from the control unit 13A.

[0286] Then, the calculation unit 18 calculates m pieces of data d １ ~d ｍ , m transmission rates S １ ~S ｍ , m transmission frame generation processing time t １＿Ｆ ~t ｍ＿Ｆ , transmission time T and SIFS time T ＳＩＦＳ Based on this, m padding times T ｐａｄｄｉｎｇ＿１ ~T ｐａｄｄｉｎｇ＿ｍ Calculate the following.

[0287] In this case, the calculation unit 18 calculates the data amount d ｉ (i is any one of 1 to m), transmission speed S_i, transmission frame generation processing time t ｉ＿Ｆ , transmission time T and SIFS time T ＳＩＦＳ Substituting into equation (4) gives the padding time T ｐａｄｄｉｎｇ＿ｉ Calculating m padding times T ｐａｄｄｉｎｇ＿１ ~T ｐａｄｄｉｎｇ＿ｍ Calculate the following.

[0288]

[0289] In formula (4), d ｉis the amount of data allocated to the i-th slave base station, and S ｉ is the transmission rate of the backhaul 4 between the master base station 1A and the i-th slave base station, and t ｉ＿Ｆ is the transmission frame generation processing time in the i-th slave base station, T is the transmission time of the notification of the transmission timing transmitted from the master base station 1A to each slave base station, and T ＳＩＦＳ is the SIFS time, and T ｐａｄｄｉｎｇ＿ｉ is the padding time of the i-th slave base station.

[0290] Note that m padding times T ｐａｄｄｉｎｇ＿１ ~T ｐａｄｄｉｎｇ＿ｍ Each of the is the length of the padding PD, which is a fixed value.

[0291] Furthermore, in equation (4), when all of the n slave base stations 2-1 to 2-n can perform joint transmission JT, M in equation (4) is M={i∈N|1≦i≦n}. As a result, the calculation unit 18 calculates n padding times T ｐａｄｄｉｎｇ＿１ ~T ｐａｄｄｉｎｇ＿ｎ Calculate.

[0292] On the other hand, in equation (4), if m slave base stations among the n slave base stations 2-1 to 2-n are capable of performing joint transmission JT, M in equation (4) is M={i∈N|1≦i≦m}. As a result, the calculation unit 18 calculates m padding times T ｐａｄｄｉｎｇ＿１ ~T ｐａｄｄｉｎｇ＿ｍ Calculate.

[0293] Then, the calculation unit 18 calculates m padding times T ｐａｄｄｉｎｇ＿１ ~T ｐａｄｄｉｎｇ＿ｍ (or n padding times T ｐａｄｄｉｎｇ＿１ ~T ｐａｄｄｉｎｇ＿ｎ ) is calculated, m padding times T ｐａｄｄｉｎｇ＿１ ~T ｐａｄｄｉｎｇ＿ｍ (or n padding times T ｐａｄｄｉｎｇ＿１ ~T ｐａｄｄｉｎｇ＿ｎ ) into equation (5) to obtain the required padding time T ｐａｄｄｉｎｇ＿ｎｄ Calculate.

[0294]

[0295] Then, the calculation unit 18 calculates the required padding time T ｐａｄｄｉｎｇ＿ｎｄ is output to the control unit 13A.

[0296] In addition, in the formula (5), the padding time T ｐａｄｄｉｎｇ＿ｎｄ T ｐａｄｄｉｎｇ＿ｎｄ If ≦0, the padding time T ｐａｄｄｉｎｇ＿ｎｄ =0.

[0297] In addition, in equation (5), the padding time T ｐａｄｄｉｎｇ＿１ , T ｐａｄｄｉｎｇ＿２ , ..., T ｐａｄｄｉｎｇ＿ｍ Among these, a plurality of maximum padding times T ｐａｄｄｉｎｇ If there are multiple maximum padding times T ｐａｄｄｉｎｇ , and any one of them is padded with the padding time T ｐａｄｄｉｎｇ＿ｎｄ n padding times Tpadding_1 to T ｐａｄｄｉｎｇ＿ｎ The same applies when is calculated.

[0298] The control unit 13A determines the padding time T ｐａｄｄｉｎｇ＿ｎｄ When the signal is received from the arithmetic unit 18, the signal is sent with a notification of the transmission timing and a padding time T ｐａｄｄｉｎｇ＿ｎｄ and the padding time T ｐａｄｄｉｎｇ＿ｎｄ and padding PD having a length of m to m slave base stations.

[0299] In the second embodiment, the response frame F containing "JT-OK" ＲＳＰ The m slave base stations that have transmitted the data amount d １ ~d ｍ After calculating the above, the following steps (4A) to (6A) are executed.

[0300] (4A) Each of the m slave base stations receives a notification of transmission timing and a padding time T from the master base station 1A by wireless communication using the channel Ch_JT. ｐａｄｄｉｎｇ＿ｎｄ Receive.

[0301] (5A) Each of the m slave base stations receives transmission data from the master base station 1A via the backhaul 4 as the “padding time T ｐａｄｄｉｎｇ＿ｎｄ This is executed in parallel with "Receive Message".

[0302] (6A) Each of the m slave base stations performs the transmission frame generation process within the “padding time T ｐａｄｄｉｎｇ＿ｎｄ This is executed in parallel with "Receive Message".

[0303] Here, (4A) is executed in response to the above-mentioned "(1A) The master base station 1A transmits, to m slave base stations by wireless communication using channel Ch_JT, notification of transmission timing and a padding PD having a length consisting of a padding time." Also, (5A) is executed in response to the above-mentioned "(2A) The master base station 1A transmits m pieces of transmission data, each having m data amounts, to m slave base stations via the backhaul 4, in parallel with the "transmission of padding PD" in (1A)." Furthermore, (6A) is executed in response to the above-mentioned "(3A) The master base station 1A and the m slave base stations perform a transmission frame generation process in parallel with the "transmission of padding PD" in (1A)."

[0304] Fig. 15 is a schematic diagram showing frame processing in the communication system 10A shown in Fig. 12. Note that Fig. 15 shows frame processing in the communication system 10A when there is one slave base station.

[0305] 15, the master base station 1A transmits a response frame F ＲＳＰ is received from the slave base station 2-1.

[0306] Then, the control unit 13A of the master base station 1A sends a response frame F ＲＳＰ If it is determined that joint transmission JT with the slave base station 2-1 is possible based on the above, the generation unit 15 of the master base station 1A determines the amount of data d to be allocated to the slave base station 2-1. １ Calculate.

[0307] Thereafter, the calculation unit 18 of the master base station 1A calculates the data amount d １ , and the padding time T ｐａｄｄｉｎｇ＿ｎｄ Calculate.

[0308] Then, (1A) the master base station 1A transmits "transmission timing notification" and "padding time T ｐａｄｄｉｎｇ＿ｎｄ (2A) the master base station 1A transmits the transmission data d via the backhaul 4 to the slave base station 2-1. １＿ｔｒｓｍ (= data volume d １ (3A) the master base station 1A and the slave base station (=slave base station 2-1) perform a process of generating a transmission frame in parallel with the transmission of the padding PD in (1A).

[0309] In (1A), the master base station 1A transmits a "transmission timing notification" by wireless communication using the channel Ch_JT, and then transmits a "padding time T ｐａｄｄｉｎｇ＿ｎｄ , and transmits padding PD having a length of .times. ...

[0310] Then, after the master base station 1A has finished transmitting the ping PD, when the transmission timing arrives, the master base station 1A and the slave base station 2-1 each transmit a transmission frame F by wireless communication using the channel Ch_JT in the joint transmission JT. ｍｓｔ＿ｔｒｓｍ (=PPDU0),F １＿ｔｒｓｍ (=PPDU1) is simultaneously transmitted to wireless device 3.

[0311] The rest of the description of FIG. 15 is the same as the description of FIG.

[0312] According to the frame processing shown in FIG. 15, the use of radio resources can be minimized by transmitting the "transmission timing notification" and the padding PD. ｐａｄｄｉｎｇ＿ｎｄThis is because is calculated as the minimum required time using the method described above.

[0313] According to the frame processing shown in FIG. 15, the master base station 1A ｐａｄｄｉｎｇ＿ｎｄ The master base station 1A and the slave base station 2-1 transmit the padding PD having a length of ｍｓｔ＿ｔｒｓｍ (=PPDU0),F １＿ｔｒｓｍ By the time the PPDU 1 (=PPDU 1) is transmitted to the wireless device 3, it is possible to prevent wireless devices in other BSSs (Basic Service Sets) from obtaining the transmission right by the CSMA / CA method and performing wireless communication.

[0314] That is, the master base station 1A and the slave base station 2-1 are connected to each other when the master base station 1A receives the padding time T ｐａｄｄｉｎｇ＿ｎｄ When the transmission of the padding PD is completed, the transmission frame F ｍｓｔ＿ｔｒｓｍ (=PPDU0),F １＿ｔｒｓｍ In other words, the master base station 1A and the slave base station 2-1 can secure the right to transmit the transmission frame F (=PPDU1) to the wireless device 3 without having to confirm that the wireless communication space is available by the CSMA / CA method, once the master base station 1A finishes transmitting the padding PD (when the slave base station 2-1 finishes receiving the padding PD). ｍｓｔ＿ｔｒｓｍ (=PPDU0),F １＿ｔｒｓｍ (=PPDU1) to the wireless device 3.

[0315] As a result, the master base station 1A and the slave base station 2-1 each transmit a transmission frame F ｍｓｔ＿ｔｒｓｍ (=PPDU0),F １＿ｔｒｓｍ This can improve the throughput when transmitting (=PPDU1) to the wireless device 3.

[0316] A BSS is a network made up of one base station and wireless devices within the radio wave range of that base station.

[0317] Fig. 16 is another schematic diagram showing frame processing in the communication system 10A shown in Fig. 12. Note that Fig. 16 shows frame processing in the communication system 10A in the case where there are two slave base stations.

[0318] 16, the master base station 1A transmits an RTS to the slave base stations 2-1 and 2-2 and the wireless device 3 by wireless communication using the channel Ch_JT.

[0319] Then, the master base station 1A receives the CTS from the wireless device 3 through wireless communication using the channel Ch_JT.

[0320] Thereafter, the master base station 1A transmits a confirmation frame F Ｓ＿ＰＢ to the slave base stations 2-1 and 2-2.

[0321] The slave base stations 2-1 and 2-2 transmit a confirmation frame F via wireless communication using the channel Ch_JT. Ｓ＿ＰＢ is received from the master base station 1A.

[0322] Then, each of the slave base stations 2-1 and 2-2 determines whether or not the joint transmission JT is possible by the above-mentioned method, and sends a response frame F including "JT_OK" or "JT_NG". ＲＳＰ Create a.

[0323] Then, the slave base stations 2-1 and 2-2 transmit a response frame F via wireless communication using the channel Ch_JT. ＲＳＰ to the master base station 1A.

[0324] Then, the master base station 1A transmits two response frames F ＲＳＰ＿１ , F ＲＳＰ＿２ are received from the two slave base stations 2-1 and 2-2, respectively.

[0325] The master base station 1A receives a response frame F ＲＳＰ＿１Based on the above, it is determined whether joint transmission JT with the slave base station 2-1 is possible, and the response frame F ＲＳＰ＿２ Based on this, it is determined whether joint transmission JT with the slave base station 2-2 is possible.

[0326] When the master base station 1A determines that joint transmission JT with the two slave base stations 2-1 and 2-2 is possible, it calculates the data volume d １ , d ２ Calculate.

[0327] Thereafter, the master base station 1A calculates the data volume d １ , d ２ Using the padding time T ｐａｄｄｉｎｇ＿ｎｄ Calculate.

[0328] In this case, the padding time T calculated for the slave base station 2-1 is ｐａｄｄｉｎｇ＿２＿１ and the padding time T calculated for the slave base station 2-2. ｐａｄｄｉｎｇ＿２＿２ Among these, the maximum padding time is padding time T ｐａｄｄｉｎｇ＿ｎｄ (see equation (5)).

[0329] Note that the padding time T ｐａｄｄｉｎｇ＿２＿１ is the padding time T ｐａｄｄｉｎｇ＿２＿２ , the master base station 1A determines the padding time T ｐａｄｄｉｎｇ＿２＿１ , T ｐａｄｄｉｎｇ＿２＿２ , and any one of them is padded with the padding time T ｐａｄｄｉｎｇ＿ｎｄ Let's say.

[0330] The master base station 1A receives the padding time T ｐａｄｄｉｎｇ＿ｎｄ After calculating the value of the padding time T ｐａｄｄｉｎｇ＿ｎｄ (2A) the master base station 1A transmits the transmission data d via the backhaul 4 to the slave base stations 2-1 and 2-2. １＿ｔｒｓｍ , d ２＿ｔｒｓｍ(3A) The master base station 1A and the slave base stations 2-1 and 2-2 perform the process of generating the transmission frame in parallel with the transmission of the padding PD in (1A).

[0331] Then, when the "transmission of padding PD" is completed, the master base station 1A, the slave base station 2-1, and the slave base station 2-2 each transmit a transmission frame F by wireless communication using the channel Ch_JT in the joint transmission JT. ｍｓｔ＿ｔｒｓｍ (PPDU0), F １＿ｔｒｓｍ (PPDU1), F ２＿ｔｒｓｍ (PPDU2) is simultaneously transmitted to wireless device 3.

[0332] Then, the wireless device 3 transmits a transmission frame F ｍｓｔ＿ｔｒｓｍ (PPDU0) is received from the master base station 1A, and the transmission frame F １＿ｔｒｓｍ (PPDU1) is received from the slave base station 2-1, and the transmission frame F ２＿ｔｒｓｍ (PPDU2) is received from the slave base station 2-2.

[0333] Then, the wireless device 3 transmits a Block Ack to the master base station 1A by wireless communication using the channel Ch_JT.

[0334] The master base station 1A receives a Block Ack from the wireless device 3 by wireless communication using the channel Ch_JT, and the wireless device 3 transmits a transmission frame F by joint transmission JT with the slave base stations 2-1 and 2-2. ｍｓｔ＿ｔｒｓｍ (PPDU0), F １＿ｔｒｓｍ (PPDU1), F ２＿ｔｒｓｍ The receiver detects that (PPDU2) has been received.

[0335] According to the frame processing shown in FIG. 16, a transmission frame F is transmitted by joint transmission JT from the master base station 1A, the slave base station 2-1, and the slave base station 2-2. ｍｓｔ＿ｔｒｓｍ (PPDU0), F １＿ｔｒｓｍ (PPDU1), F ２＿ｔｒｓｍWhen transmitting (PPDU2) to the wireless device 3, the use of wireless resources can be minimized by "notifying the transmission timing" and "transmitting the padding PD." ｐａｄｄｉｎｇ＿ｎｄ This is because is calculated as the minimum required time using the method described above.

[0336] According to the frame processing shown in FIG. 16, the master base station 1A ｐａｄｄｉｎｇ＿ｎｄ The master base station 1A and the slave base stations 2-1 and 2-2 transmit the padding PD having a length of ｍｓｔ＿ｔｒｓｍ (PPDU0), F １＿ｔｒｓｍ (PPDU1), F ２＿ｔｒｓｍ By the time (PPDU2) is transmitted to the wireless device 3, it is possible to prevent wireless devices in other BSSs from obtaining the transmission right by the CSMA / CA method and performing wireless communication.

[0337] That is, the master base station 1A and the slave base stations 2-1 and 2-2 are connected to each other when the master base station 1A receives the padding time T ｐａｄｄｉｎｇ＿ｎｄ By transmitting the padding PD having a length of 0 to the slave base stations 2-1 and 2-2, wireless devices of other BSSs cannot acquire the transmission right by the CSMA / CA method. Therefore, when the master base station 1A finishes transmitting the padding PD (i.e., when the slave base stations 2-1 and 2-2 finish receiving the padding PD), each of the slave base stations 2-1 and 2-2 transmits the transmission frame F ｍｓｔ＿ｔｒｓｍ (PPDU0), F １＿ｔｒｓｍ (PPDU1), F ２＿ｔｒｓｍ The right to transmit (PPDU2) to the wireless device 3 can be secured by the CSMA / CA method.

[0338] The reason is as follows: The padding time T ｐａｄｄｉｎｇ＿ｉ is the amount of data d transmitted by each slave base station ｉ (see equation (4)), and the required padding time T ｐａｄｄｉｎｇ＿ｎｄ is the padding time T ｐａｄｄｉｎｇ＿１and padding time T ｐａｄｄｉｎｇ＿２ Since the required padding time is T ｐａｄｄｉｎｇ＿ｎｄ This is because it is possible to prevent wireless devices of other BSSs from obtaining the transmission right by the CSMA / CA method and performing wireless communication until the transmission of the padding PD is completed (i.e., until the transmission of the padding PD is completed).

[0339] As a result, the master base station 1A and the slave base stations 2-1 and 2-2 each transmit a transmission frame F ｍｓｔ＿ｔｒｓｍ (PPDU0), F １＿ｔｒｓｍ (PPDU1), F ２＿ｔｒｓｍ This improves the throughput when transmitting (PPDU2) to the wireless device 3.

[0340] In FIG. 15, the frame processing has been described for the case where there is one slave base station, and in FIG. 16, the frame processing has been described for the case where there are two slave base stations.

[0341] As a result, the only change in frame processing due to the addition of one slave base station is the confirmation frame F Ｓ＿ＰＢ The number of response frames F ＲＳＰ , calculation of the amount of data to be distributed to the slave base station, padding time T ｐａｄｄｉｎｇ＿ｎｄ , allocation of transmission data to slave base stations, and the number of transmission frame PPDUs. Therefore, if frame processing for the case where there is one slave base station and frame processing for the case where there are two slave base stations are explained, frame processing can generally be performed in the same manner as the frame processing shown in Figure 16 even when there are m slave base stations capable of joint transmission JT.

[0342] 17 and 18 are first and second flowcharts, respectively, for explaining the operation of the communication system 10A shown in FIG.

[0343] The flowcharts shown in FIGS. 17 and 18 are the same as the flowcharts shown in FIGS. 10 and 11 except that step S17 is added to the flowchart shown in FIG. 10, step S11 in the flowchart shown in FIG. 10 is changed to step S18, and step S12 in FIG. 11 is changed to step S12A.

[0344] Referring to FIG. 17, when the operation of communication system 10A is started, steps S1 to S9 described above are executed in sequence.

[0345] If it is determined in step S9 that joint transmission JT is possible, step S10 described above is executed.

[0346] After step S10, the calculation unit 18 of the master base station 1A calculates the required padding time T ｐａｄｄｉｎｇ＿ｎｄ is calculated (step S17).

[0347] Thereafter, (1A) the master base station 1A notifies the transmission timing and padding time T via in-band (= via wireless communication using the same channel as the channel when the master base station and each of the m slave base stations transmit data to the wireless device). ｐａｄｄｉｎｇ＿ｎｄ (2A) the master base station 1A distributes transmission data to the slave base stations (= m slave base stations) via the backhaul 4 in parallel with the transmission of the padding PD of (1A); and (3A) the master base station 1A and the slave base stations (= m slave base stations) perform transmission frame generation processing in parallel with the transmission of the padding PD of (1A) (step S18).

[0348] After step S18, the operation of the communication system 10A proceeds to step S12A shown in FIG.

[0349] Referring to FIG. 18, after step S18 in FIG. 17, when the padding time ends (when the master base station 1A completes transmission of the padding PD and the slave base stations (= m slave base stations) complete reception of the padding PD), the master base station 1A and the slave base stations (= m slave base stations) simultaneously transmit transmission data to the wireless device 3 by wireless communication using channel Ch_JT at the transmission timing (step S12A).

[0350] Thereafter, the above-described steps S13 to S15 are executed in sequence, and the operation of the communication system 10A is completed.

[0351] On the other hand, when it is determined in step S9 of Figure 17 that joint transmission JT is not possible, the operation of communication system 10A proceeds to step S16 shown in Figure 18, and the above-mentioned steps S16, "YES" of step S17, step S14 and step S15 are executed sequentially, and the operation of communication system 10A is terminated, or the above-mentioned steps S16 and step S17 are executed sequentially, and the operation of communication system 10A is terminated.

[0352] FIG. 19 is a flowchart for explaining the detailed operation of step S17 in FIG.

[0353] 19, after step S10 in FIG. 17, the calculation unit 18 of the master base station 1A calculates m pieces of data amount d １ ~d ｍ , m transmission rates S １ ~S ｍ , m transmission frame generation processing time t １＿Ｆ ~t ｍ＿Ｆ , transmission time T and SIFS time T ＳＩＦＳ is received from the control unit 13A (step S171).

[0354] Then, the arithmetic unit 18 sets i=1 (step S172), where i is an argument indicating each of the m slave base stations 21 to 2m, and i=1 to m.

[0355] After step S172, the calculation unit 18 calculates the data amount d ｉ, transmission speed S ｉ , transmission frame generation processing time t ｉ＿Ｆ , transmission time T and SIFS time T ＳＩＦＳ Substituting into equation (4) gives the padding time T ｐａｄｄｉｎｇ＿ｉ is calculated (step S173).

[0356] Then, the arithmetic unit 18 determines whether i=m (step S174).

[0357] If it is determined in step S174 that i is not equal to m, the arithmetic unit 18 sets i to i+1 (step S175).

[0358] Thereafter, the operation of the arithmetic unit 18 proceeds to step S173, and steps S173 to S175 are repeatedly executed until it is determined in step S174 that i=m.

[0359] Then, in step S174, when it is determined that i=m, the calculation unit 18 calculates m padding times T ｐａｄｄｉｎｇ＿１ ~T ｐａｄｄｉｎｇ＿ｍ Substituting into equation (5) the required padding time T ｐａｄｄｉｎｇ＿ｎｄ is calculated (step S176).

[0360] Here, the required padding time T ｐａｄｄｉｎｇ＿ｎｄ is m padding times T ｐａｄｄｉｎｇ＿１ ~T ｐａｄｄｉｎｇ＿ｍ The maximum padding time is

[0361] After step S176, the operation of the communication system 10A proceeds to step S18 in FIG.

[0362] In the above-mentioned second embodiment, in step S18 of FIG. 17, (2A) does not have to be executed in parallel with the transmission of the padding PD of (1A), and (3A) does not have to be executed in parallel with the transmission of the padding PD of (1A).

[0363] Even if (2A) and (3A) are not executed in parallel with the transmission of the padding PD in (1A), if the master base station 1A executes the allocation of the transmission data to the slave base stations (= m slave base stations) via the backhaul 4, the amount of wireless resources used can be reduced compared to the case where the transmission data is allocated to the slave base stations (= m slave base stations) by wireless communication, and the transmission frame F is transmitted from the master base station 1A and the m slave base stations to the wireless device 3. ｍｓｔ＿ｔｒｓｍ , F １＿ｔｒｓｍ ~F ｍ＿ｔｒｓｍ This is because it can improve the throughput when transmitting.

[0364] (Example 2) When data is transmitted to a wireless device 3 using one master base station and two slave base stations A and B, the total amount of data transmitted to the wireless device 3, the wireless transmission rate of the one master base station, the wireless transmission rate of the two slave base stations A and B, the backhaul transmission rate, the frame generation processing time, the transmission time of the frame that transmits notification of the transmission timing, and the SIFS time are shown in Table 2.

[0365]

[0366] When the amount of data to be allocated to the slave base stations A and B is calculated using the total data amount and wireless transmission rate shown in Table 2, the amount of data d allocated to the slave base station A is １ As mentioned above, ３ [byte] (see equation (2)), and the amount of data to be allocated to the slave base station B is d ２ is 82.5 x 10 ３ [bytes] (see equation (3)). The amount of data allocated to the master base station is 100 [Kbytes], as described above.

[0367] Next, the padding time T ｐａｄｄｉｎｇ＿Ａ is calculated as shown in Equation (6), and the padding time T ｐａｄｄｉｎｇ＿Ｂ is calculated as shown in equation (7).

[0368]

[0369]

[0370] Then, the required padding time T ｐａｄｄｉｎｇ＿ｎｄ is calculated as shown in equation (8).

[0371]

[0372] In equations (6) and (7), the backhaul transmission rate (5×10 ９ [bps]), the transmission time of the notification of the transmission timing sent from the master base station to each slave base station (40×10 －６ [bps]) and SIFS time (16 x 10 － 6 [sec]) are the same.

[0373] The amount of data allocated to the slave base station A is 67.5×10 ３ [bytes], and the amount of data allocated to slave base station B is 82.5×10 ３ [byte].

[0374] The frame generation processing time of the slave base station A is 125×10 －６ [sec], and the frame generation processing time of the slave base station B is 105×10 －６ [sec].

[0375] Then, the first term on the right side of equation (6) is 108 x 10 －６ [sec], and the first term on the right side of equation (7) is 132 × 10 －６ It becomes [sec].

[0376] 108 x 10 －６ [sec] is the amount of data 67.5 x 10 ３ is the transmission time when transmitting transmission data [bytes] from the master base station to the slave base station A via the backhaul 4, and is 132×10 －６ [sec] is the amount of data 82.5 × 10 ３ This is the transmission time when transmitting transmission data in [byte] from the master base station to the slave base station B via the backhaul 4.

[0377] Then, the transmission time of the transmission data to the slave base station B (= 132 × 10 －６[sec]) and the transmission time of the transmission data to the slave base station A (=108×10 －６ [sec]) (= 24 × 10 －６ [sec]) is the frame generation processing time of the slave base station A (=125×10 －６ [sec]) and the frame generation processing time of slave base station B (= 105 × 10 －６ [sec]) (= 20 × 10 －６ [sec]).

[0378] As a result, the padding time T ｐａｄｄｉｎｇ＿Ｂ (=181 x 10 －６ [sec]) is the padding time T ｐａｄｄｉｎｇ＿Ａ (=177 x 10 －６ [sec]).

[0379] Therefore, the required padding time T ｐａｄｄｉｎｇ＿ｎｄ is the padding time T of the slave base station B ｐａｄｄｉｎｇ＿Ｂ (=181 [μsec]).

[0380] In this way, the amount of data d allocated to the slave base stations A and B using equation (1) is calculated. Ａ , d Ｂ and using equations (4) and (5), the required padding time T ｐａｄｄｉｎｇ＿ｎｄ It has been found that by calculating the above, it is possible to secure the right to transmit by wireless communication using channel Ch_JT until the master base station and all of the slave base stations A and B start transmitting the transmission frame PPDU.

[0381] Other aspects of the second embodiment are the same as those of the first embodiment.

[0382] In the above description, the channel Ch_JT is made up of one channel, but in the embodiment of the present invention, the channel Ch_JT may be made up of the channels Ch_JT_CMM shown below.

[0383] Fig. 20 is a diagram showing an example of the configuration of channel Ch_JT_CMM when the maximum bandwidth is 320 MHz in the 6 GHz band.

[0384] Referring to Figure 20, the conditions for performing joint transmission JT using channel Ch_JT_CMM are that the destination terminal, wireless device 3, is under the control of the master base station 1 (or master base station 1A), and the following (I) to (IV) are satisfied.

[0385] Note that "being under control" means that the base station and the wireless device can transmit and receive data to and from each other in the wireless LAN.

[0386] (I) The primary channel Ch_PR_WD (=45ch) of the wireless device 3 is the same as the primary channel Ch_PR_MBS (=45ch) of the master base station 1 (or master base station 1A).

[0387] (II) The secondary channel Ch_SC_WD (=33ch, 37ch, 41ch, 49ch, 53ch, 57ch, 61ch) of the wireless device 3 is within the range of the secondary channel Ch_SC_MBS (=33ch, 37ch, 41ch, 49ch, 53ch, 57ch, 61ch) of the master base station 1 (or master base station 1A).

[0388] (III) The primary channel Ch_PR_SV (=33ch, 45ch, 61ch) of the slave base stations 2-1, 2-2, 2-3, 2-4 is within the range of the primary channel Ch_PR_WD (=45ch) of the wireless device 3 or the range of the secondary channel Ch_SC_WD (=33ch, 37ch, 41ch, 49ch, 53ch, 57ch, 61ch).

[0389] (IV) When the primary channel Ch_PR_WD (= 45ch) of the wireless device 3 is different from the primary channel Ch_PR_SV (= 33ch, 61ch) of the slave base stations 2-1 and 2-2, the primary channel Ch_PR_WD (= 45ch) of the wireless device 3 is within the range of the secondary channel Ch_SC_SV (= 37ch to 57ch) of the slave base stations 2-1 and 2-2.

[0390] The channel Ch_JT_CMM consists of channels that are "part of the common part of the 'primary channel and secondary channel' or the widest channel of the common part and include the primary channel, provided that the primary channels of all base stations and wireless devices are included" among the master base station, slave base station and wireless devices participating in the joint transmission JT.

[0391] When the master base station 1 (or the master base station 1A) performs joint transmission JT, the master base station 1 (or the master base station 1A) receives the primary channel Ch_PR_WD (=45ch) and secondary channel Ch_SC_WD (=1ch to 41ch, 49ch to 61ch) of the wireless device 3, the primary channel Ch_PR_SV (=33ch) and secondary channel Ch_SC_SV (=37ch to 61ch) of the slave base station 2-1, and the primary channel Ch_PR_SV (=61ch) and secondary channel Ch_SC_SV (=33ch to 57ch) of the slave base station 2-2. h), the primary channel Ch_PR_SV (=45ch) and secondary channel Ch_SC_SV (=1ch to 41ch, 49ch to 61ch) of the slave base station 2-3, and the common portion (=33ch to 61ch) of the primary channel Ch_PR_SV (=45ch) and secondary channel Ch_SC_SV (=33ch to 41ch, 49ch to 93ch) of the slave base station 2-4, are transmitted to the destination terminal (=wireless device 3) and slave base stations 2-1 to 2-4 on channel Ch_JT_CMM1.

[0392] The wireless device 3 is equipped with an antenna capable of receiving frames transmitted on channels 33ch to 61ch that make up the channel Ch_JT_CMM1. The wireless device 3 receives the channel Ch_JT_CMM1 from the master base station 1 (or master base station 1A) on the channel Ch_JT_CMM1.

[0393] Each of the slave base stations 2-1 to 2-4 receives the channel Ch_JT_CMM1 from the master base station 1 (or master base station 1A) on the channel Ch_JT_CMM1.

[0394] Table 3 shows a transmission method in which the master base station 1 (or master base station 1A) and the slave base station 2-1 transmit a transmission frame to the wireless device 3 by joint transmission JT.

[0395]

[0396] In Table 3, transmission method (1) is a method in which the master base station 1 (or the master base station 1A) transmits a transmission frame F on the primary channel (ch45) and the secondary channels (ch33 to ch41). ｍｓｔ＿ｔｒｓｍ (=PPDU0) to the wireless device 3, and the slave base station 2-1 transmits a transmission frame F １＿ｔｒｓｍ (=PPDU1) to the wireless device 3.

[0397] In addition, in Table 3, in transmission method (2), the master base station 1 (or the master base station 1A) transmits a transmission frame F on the primary channel (45ch) and the secondary channels (33ch to 41ch, 49ch to 61ch). ｍｓｔ＿ｔｒｓｍ (=PPDU0) to the wireless device 3, and the slave base station 2-1 transmits a transmission frame F １＿ｔｒｓｍ (=PPDU1) to the wireless device 3.

[0398] As a result, transmission method (2) uses a wider bandwidth than transmission method (1), and therefore can transmit transmission frames to wireless device 3 faster than transmission method (1).

[0399] In FIG. 20, the primary channel (45ch) of the master base station 1 (or master base station 1A) is different from the primary channel (33ch) of the slave base station 2-1, so the four channels (33ch, 37ch, 41ch, 45ch) in the common portion that includes both the primary channel (45ch) of the master base station 1 (or master base station 1A) and the primary channel (33ch) of the slave base station 2-1 are designated as channel Ch_JT_CMM1.

[0400] Table 4 shows a transmission method in which the master base station 1 (or master base station 1A) and the slave base station 2-2 transmit a transmission frame to the wireless device 3 by joint transmission JT.

[0401]

[0402] In Table 4, transmission method (1) is a method in which the master base station 1 (or the master base station 1A) transmits a transmission frame F on the primary channel (ch45) and the secondary channels (ch33 to ch41, ch49 to ch61). ｍｓｔ＿ｔｒｓｍ (=PPDU0) to the wireless device 3, and the slave base station 2-2 transmits a transmission frame F ２＿ｔｒｓｍ (=PPDU2) to the wireless device 3.

[0403] In FIG. 20, the primary channel (45ch) of the master base station 1 (or master base station 1A) is different from the primary channel (61ch) of the slave base station 2-2, so the eight channels (33ch, 37ch, 41ch, 45ch, 49ch, 53ch, 57ch, 61ch) in the common portion that includes both the primary channel (45ch) of the master base station 1 (or master base station 1A) and the primary channel (61ch) of the slave base station 2-2 are designated as channel Ch_JT_CMM1.

[0404] When microwaves are used, one of the following may be used: one channel (bandwidth 20 MHz), two channels (bandwidth 40 MHz), four channels (bandwidth 80 MHz), eight channels (bandwidth 160 MHz), or sixteen channels (bandwidth 320 MHz).

[0405] Table 5 shows a transmission method in which the master base station 1 (or master base station 1A) and the slave base stations 2-3 transmit a transmission frame to the wireless device 3 by joint transmission JT.

[0406]

[0407] In Table 5, transmission method (1) is a method in which the master base station 1 (or the master base station 1A) transmits a transmission frame F ｍｓｔ＿ｔｒｓｍ (=PPDU0) to the wireless device 3, and the slave base station 2-3 transmits a transmission frame F ３＿ｔｒｓｍ (=PPDU3) to the wireless device 3.

[0408] In Table 5, transmission method (2) is a method in which the master base station 1 (or the master base station 1A) transmits a transmission frame F on the primary channel (45ch) and the secondary channel (41ch). ｍｓｔ＿ｔｒｓｍ (=PPDU0) to the wireless device 3, and the slave base station 2-3 transmits a transmission frame F ３＿ｔｒｓｍ (=PPDU3) to the wireless device 3.

[0409] Furthermore, in Table 5, transmission method (3) is a method in which the master base station 1 (or the master base station 1A) transmits a transmission frame F on the primary channel (ch45) and the secondary channels (ch33 to ch41). ｍｓｔ＿ｔｒｓｍ (=PPDU0) to the wireless device 3, and the slave base station 2-3 transmits a transmission frame F ３＿ｔｒｓｍ (=PPDU3) to the wireless device 3.

[0410] Furthermore, in Table 5, in transmission method (4), the master base station 1 (or the master base station 1A) transmits a transmission frame F on the primary channel (45ch) and the secondary channels (33ch to 41ch, 49ch to 61ch). ｍｓｔ＿ｔｒｓｍ (=PPDU0) to the wireless device 3, and the slave base station 2-3 transmits a transmission frame F ３＿ｔｒｓｍ (=PPDU3) to the wireless device 3.

[0411] Furthermore, in Table 5, transmission method (5) is a method in which the master base station 1 (or the master base station 1A) transmits a transmission frame F on the primary channel (45ch) and the secondary channels (1ch to 41ch, 49ch to 61ch). ｍｓｔ＿ｔｒｓｍ (=PPDU0) to the wireless device 3, and the slave base station 2-3 transmits a transmission frame F on the primary channel (ch45) and the secondary channels (ch1 to ch41, ch49 to ch61). ３＿ｔｒｓｍ (=PPDU3) to the wireless device 3.

[0412] In FIG. 20, channel Ch_JT_CMM1 is shown as consisting of channels 33ch to 61ch, but when transmission method (5) is used, channel Ch_JT_CMM1 consists of the common portion (=1ch to 61ch) of channels 1ch to 61ch of the master base station 1 (or master base station 1A) and channels 1ch to 61ch of the slave base station 2-3.

[0413] In FIG. 20, the primary channel (45ch) of the master base station 1 (or master base station 1A) is the same as the primary channel (45ch) of the slave base station 2-3, so there are three types of transmission method: transmission method (1) in which the master base station 1 (or master base station 1A) and the slave base station 2-3 transmit transmission frames using one channel, 45ch; transmission method (2) in which the master base station (or master base station 1A) and the slave base station 2-3 transmit transmission frames using two channels, 41ch and 45ch; and transmission method (3) in which the master base station (or master base station 1A) and the slave base station 2-3 transmit transmission frames using four channels, 33ch, 37ch, 41ch, 42ch, 43ch, 44ch, 45ch, 46ch, 47ch, 48ch, 49ch, 50ch, 51ch, 52ch, 53ch, 54ch, 55ch, 56ch, 57ch, 58ch, 59ch, 60ch, 61ch, 62ch, 63ch, 64ch, 65ch, 66ch, 67ch, 68ch, 69ch, 70ch, 71ch, 72ch, 73ch, 74ch, 75ch, 76ch, 77ch, 78ch, 79ch, 80ch, 81ch, 82ch, 83ch, 84ch, 85ch, 86ch, 87ch, 88ch, 89ch, 90ch, 91ch, 92ch, 93ch, 94ch, 95ch, 96ch, 97ch, 98ch, 99ch, 100ch, 101ch, 102ch, a transmission method (4) in which the master base station 1 (or the master base station 1A) and the slave base stations 2-3 transmit transmission frames using eight channels: 33ch, 37ch, 41ch, 45ch, 49ch, 53ch, 57ch, and 61ch; and a transmission method (5) in which the master base station 1 (or the master base station 1A) and the slave base stations 2-3 transmit transmission frames using 16 channels: 1ch, 5ch, 9ch, 13ch, 17ch, 21ch, 25ch, 29ch, 33ch, 37ch, 41ch, 45ch, 49ch, 53ch, 57ch, and 61ch.

[0414] Therefore, in Table 5, transmission method (2) uses a wider bandwidth than transmission method (1), and therefore can transmit transmission frames to wireless device 3 faster than transmission method (1); transmission method (3) uses a wider bandwidth than transmission method (2), and therefore can transmit transmission frames to wireless device 3 faster than transmission method (2); transmission method (4) uses a wider bandwidth than transmission method (3), and therefore can transmit transmission frames to wireless device 3 faster than transmission method (3); and transmission method (5) uses a wider bandwidth than transmission method (4), and therefore can transmit transmission frames to wireless device 3 faster than transmission method (4).

[0415] Table 6 shows a transmission method in which the master base station 1 (or master base station 1A) and the slave base stations 2-3 and 2-4 transmit a transmission frame to the wireless device 3 by joint transmission JT.

[0416]

[0417] In Table 6, transmission method (1) is a method in which the master base station 1 (or the master base station 1A) transmits a transmission frame F on the primary channel (ch45). ｍｓｔ＿ｔｒｓｍ (=PPDU0) to the wireless device 3, and the slave base station 2-3 transmits a transmission frame F ３＿ｔｒｓｍ (=PPDU3) to the wireless device 3, and the slave base station 2-4 transmits a transmission frame F ４＿ｔｒｓｍ (=PPDU4) to the wireless device 3.

[0418] In addition, in Table 6, in transmission method (2), the master base station 1 (or the master base station 1A) transmits a transmission frame F on the primary channel (45ch) and the secondary channel (41ch). ｍｓｔ＿ｔｒｓｍ (=PPDU0) to the wireless device 3, and the slave base station 2-3 transmits a transmission frame F ３＿ｔｒｓｍ (=PPDU3) to the wireless device 3, and the slave base station 2-4 transmits a transmission frame F ４＿ｔｒｓｍ (=PPDU4) to the wireless device 3.

[0419] Furthermore, in Table 6, transmission method (3) is a method in which the master base station 1 (or the master base station 1A) transmits a transmission frame F on the primary channel (ch45) and the secondary channels (ch33 to ch41). ｍｓｔ＿ｔｒｓｍ (=PPDU0) to the wireless device 3, and the slave base station 2-3 transmits a transmission frame F ３＿ｔｒｓｍ (=PPDU3) to the wireless device 3, and the slave base station 2-4 transmits a transmission frame F ４＿ｔｒｓｍ (=PPDU4) to the wireless device 3.

[0420] Furthermore, in Table 6, transmission method (4) is a method in which the master base station 1 (or the master base station 1A) transmits a transmission frame F using the primary channel (45ch), the secondary channels (33ch to 41ch), and the secondary channels (49ch to 61ch). ｍｓｔ＿ｔｒｓｍ (=PPDU0) to the wireless device 3, and the slave base station 2-3 transmits a transmission frame F using the primary channel (ch45), the secondary channels (ch33 to ch41), and the secondary channels (ch49 to ch61). ３＿ｔｒｓｍ (=PPDU3) to the wireless device 3, and the slave base station 2-4 transmits a transmission frame F using the primary channel (ch45), the secondary channels (ch33 to ch41), and the secondary channels (ch49 to ch61). ４＿ｔｒｓｍ (=PPDU4) to the wireless device 3.

[0421] In FIG. 20 , the primary channel (45ch) of the master base station 1 (or master base station 1A) is the same as the primary channel (45ch) of the slave base stations 2-3 and 2-4, and so there are transmission method (1) in which the master base station 1 (or master base station 1A) and the slave base stations 2-3 and 2-4 transmit transmission frames using one channel, 45ch; transmission method (2) in which the master base station 1 (or master base station 1A) and the slave base stations 2-3 and 2-4 transmit transmission frames using two channels, 41ch and 45ch; transmission method (3) in which the master base station 1 (or master base station 1A) and the slave base stations 2-3 and 2-4 transmit transmission frames using four channels, 33ch, 37ch, 41ch, and 45ch; and transmission method (4) in which the master base station 1 (or master base station 1A) and the slave base stations 2-3 and 2-4 transmit transmission frames using eight channels, 33ch, 37ch, 41ch, 45ch, 49ch, 53ch, 57ch, and 61ch.

[0422] Therefore, in Table 6, transmission method (2) uses a wider bandwidth than transmission method (1), and therefore can transmit transmission frames to wireless device 3 faster than transmission method (1); transmission method (3) uses a wider bandwidth than transmission method (2), and therefore can transmit transmission frames to wireless device 3 faster than transmission method (2); and transmission method (4) uses a wider bandwidth than transmission method (3), and therefore can transmit transmission frames to wireless device 3 faster than transmission method (3).

[0423] Table 7 shows a transmission method in which the master base station 1 (or master base station 1A) and the slave base stations 2-1, 2-2, and 2-3 transmit a transmission frame to the wireless device 3 by joint transmission JT.

[0424]

[0425] In Table 7, transmission method (1) is a method in which the master base station 1 (or the master base station 1A) transmits a transmission frame F on the primary channel (45ch), the secondary channels (33ch to 41ch), and the secondary channels (49ch to 61ch). ｍｓｔ＿ｔｒｓｍ (=PPDU0) to the wireless device 3, and the slave base station 2-1 transmits a transmission frame F １＿ｔｒｓｍ (=PPDU1) to the wireless device 3, and the slave base station 2-2 transmits a transmission frame F ２＿ｔｒｓｍ (=PPDU2) to the wireless device 3, and the slave base station 2-3 transmits a transmission frame F on the primary channel (ch45), secondary channels (ch33 to ch41) and secondary channels (ch49 to ch61). ３＿ｔｒｓｍ (=PPDU3) to the wireless device 3.

[0426] Table 8 shows a transmission method in which the master base station 1 (or master base station 1A) and the slave base stations 2-1 to 2-4 transmit a transmission frame to the wireless device 3 by joint transmission JT.

[0427]

[0428] In Table 8, transmission method (1) is a method in which the master base station 1 (or the master base station 1A) transmits a transmission frame F on the primary channel (45ch), the secondary channels (33ch to 41ch), and the secondary channels (49ch to 61ch). ｍｓｔ＿ｔｒｓｍ (=PPDU0) to the wireless device 3, and the slave base station 2-1 transmits a transmission frame F １＿ｔｒｓｍ (=PPDU1) to the wireless device 3, and the slave base station 2-2 transmits a transmission frame F ２＿ｔｒｓｍ (=PPDU2) to the wireless device 3, and the slave base station 2-3 transmits a transmission frame F on the primary channel (ch45), secondary channels (ch33 to ch41) and secondary channels (ch49 to ch61). ３＿ｔｒｓｍ (=PPDU3) to the wireless device 3, and the slave base station 2-4 transmits a transmission frame F on the primary channel (ch45), secondary channels (ch33 to ch41) and secondary channels (ch49 to ch61). ４＿ｔｒｓｍ (=PPDU4) to the wireless device 3.

[0429] In addition, when only the master base station 1 (or the master base station 1A) transmits a transmission frame including the transmission data D_trsm to the wireless device 3 via wireless communication, the master base station 1 (or the master base station 1A) may transmit the transmission frame including the transmission data D_trsm to the wireless device 3 using only the primary channel shown in any of Tables 3 to 8, or may transmit the transmission frame including the transmission data D_trsm to the wireless device 3 using both the primary channel and the secondary channel shown in any of Tables 3 to 8.

[0430] Fig. 21 is a diagram showing another example of the configuration of the channel Ch_JT_CMM when the bandwidth is 40 MHz in the 2.4 GHz band.

[0431] Referring to FIG. 21, the primary channel Ch_PR_MBS of the master base station 1 (or master base station 1A) is channel 5ch, and the secondary channel Ch_SC_MBS of the master base station 1 (or master base station 1A) is channel 9ch.

[0432] The primary channel Ch_PR_WD of the wireless device 3 is channel 5ch, and the secondary channel Ch_SC_WD of the wireless device 3 is channel 9ch.

[0433] Furthermore, the primary channel Ch_PR_SV of the slave base station 2-1 is channel 9ch, and the secondary channel Ch_SC_SV of the slave base station 2-1 is channel 5ch.

[0434] As a result, the channel Ch_JT_CMM2 (=5ch, 9ch) satisfies the above-mentioned conditions (I) to (IV).

[0435] Table 9 shows a transmission method in which the master base station 1 (or master base station 1A) and the slave base station 2-1 transmit a transmission frame to the wireless device 3 by joint transmission JT.

[0436]

[0437] In Table 9, transmission method (1) is a method in which the master base station 1 (or the master base station 1A) transmits a transmission frame F on the primary channel (5ch) and the secondary channel (9ch). ｍｓｔ＿ｔｒｓｍ (=PPDU0) to the wireless device 3, and the slave base station 2-1 transmits a transmission frame F １＿ｔｒｓｍ (=PPDU1) to the wireless device 3.

[0438] When the master base station 1 (or master base station 1A) performs joint transmission JT, it transmits channel Ch_JT_CMM2, which consists of the common parts (=5ch, 9ch) of the primary channel Ch_PR_WD (=5ch) and secondary channel Ch_SC_WD (=9ch) of the wireless device 3 and the primary channel Ch_PR_SV (=9ch) and secondary channel Ch_SC_SV (=5ch) of the slave base station 2-1, to the slave base station 2-1 and the wireless device 3 on channel Ch_JT.

[0439] The wireless device 3 is equipped with an antenna capable of receiving frames transmitted on channel Ch_JT_CMM2 (ch 5, ch 9). The wireless device 3 receives channel Ch_JT_CMM2 (ch 5, ch 9) from the master base station 1 (or master base station 1A) on channel Ch_JT.

[0440] The slave base station 2-1 receives the channel Ch_JT_CMM2 (5ch, 9ch) from the master base station 1 (or the master base station 1A) on the channel Ch_JT.

[0441] In the joint transmission JT, the master base station 1 (or the master base station 1A) transmits a transmission frame F on the primary channel ch5 and the secondary channel ch9. ｍｓｔ＿ｔｒｓｍ (=PPDU0) to the wireless device 3, and the slave base station 2-1 transmits a transmission frame F on the primary channel 9ch and the secondary channel 5ch. １＿ｔｒｓｍ (=PPDU1) is transmitted to wireless device 3.

[0442] In addition, when only the master base station 1 (or the master base station 1A) transmits a transmission frame including the transmission data D_trsm to the wireless device 3 via wireless communication, the master base station 1 (or the master base station 1A) may transmit the transmission frame including the transmission data D_trsm to the wireless device 3 using the primary channel (5ch) and secondary channel (9ch) shown in Table 9.

[0443] Fig. 22 is a diagram showing yet another example of the configuration of channel Ch_JT_CMM, where Fig. 22 shows an example of the configuration of channel ChJT_CMM when the bandwidth is 40 MHz in the 2.4 GHz band.

[0444] Referring to FIG. 22, the primary channel Ch_PR_MBS of the master base station 1 (or master base station 1A) is channel 7ch, and the secondary channel Ch_SC_MBS of the master base station 1 (or master base station 1A) is channel 11ch.

[0445] The primary channel Ch_PR_WD of the wireless device 3 is channel 7ch, and the secondary channel Ch_SC_WD of the wireless device 3 is channel 11ch.

[0446] Furthermore, the primary channel Ch_PR_SV of the slave base station 2-1 is channel 7ch, and the secondary channel Ch_SC_SV of the slave base station 2-1 is channel 3ch.

[0447] As a result, channel Ch_JT_CMM3 (=7ch) satisfies the above-mentioned conditions (I) to (IV).

[0448] Table 10 shows a transmission method in which the master base station 1 (or master base station 1A) and the slave base station 2-1 transmit a transmission frame to the wireless device 3 by joint transmission JT.

[0449]

[0450] In Table 10, transmission method (1) is a method in which the master base station 1 (or the master base station 1A) transmits a transmission frame F ｍｓｔ＿ｔｒｓｍ (=PPDU0) to the wireless device 3, and the slave base station 2-1 transmits a transmission frame F １＿ｔｒｓｍ (=PPDU1) to the wireless device 3.

[0451] When the master base station 1 (or master base station 1A) performs joint transmission JT, it transmits channel Ch_JT_CMM3, which consists of the common portion (=7ch) of the primary channel Ch_PR_MBS (=7ch) and secondary channel Ch_SC_MBS (=11ch) of the master base station 1 (or master base station 1A), the primary channel Ch_PR_WD (=7ch) and secondary channel Ch_SC_WD (=11ch) of the wireless device 3, and the primary channel Ch_PR_SV (=7ch) and secondary channel Ch_SC_SV (=3ch) of the slave base station 2-1, to the slave base station 2-1 and the wireless device 3 on channel Ch_JT.

[0452] The wireless device 3 is equipped with an antenna capable of receiving frames transmitted on channel Ch_JT_CMM3 (7ch). The wireless device 3 receives channel Ch_JT_CMM3 (7ch) from the master base station 1 (or master base station 1A) on channel Ch_JT.

[0453] The slave base station 2-1 receives the channel Ch_JT_CMM3 (7ch) from the master base station 1 (or the master base station 1A) on the channel Ch_JT.

[0454] When performing joint transmission JT, the master base station 1 (or the master base station 1A) transmits a transmission frame F on the primary channel Ch_PR_MBS (=7ch). ｍｓｔ＿ｔｒｓｍ (=PPDU0) to the wireless device 3, and the slave base station 2-1 transmits a transmission frame F １ｔ＿ｔｒｓｍ (=PPDU1) is transmitted to wireless device 3.

[0455] According to the transmission methods shown in Tables 3 to 10 above, the master base station and the slave base station transmit transmission frames to the wireless device 3 using at least the primary channel out of the primary channel and secondary channels.

[0456] Therefore, in an embodiment of the present invention, when channel Ch_JT_CMM is used, the master base station and the slave base station use "CSMA / CA wireless communication using at least the primary channel of the master base station and the primary channel of the slave base station" instead of "CSMA / CA wireless communication using one channel", and when the transmission timing arrives, transmit the transmission frame to the wireless device by joint transmission.

[0457] As described above, a slave base station generally consists of m slave base stations, and therefore, in an embodiment of the present invention, the master base station and the m slave base stations use "CSMA / CA wireless communication using at least the primary channel of the master base station and m primary channels of the m slave base stations" instead of "CSMA / CA wireless communication using one channel", and when the transmission timing arrives, transmit (m+1) transmission frames to the wireless device by joint transmission.

[0458] FIG. 23 is a schematic diagram showing frame processing when using channel Ch_JT_CMM.

[0459] Referring to FIG. 23, the master base station 1 transmits an RTS to the slave base station 2-1 and the wireless device 3 by wireless communication using the channel Ch_JT_CMM.

[0460] Then, the slave base station 2-1 and the wireless device 3 receive the RTS from the master base station 1 by wireless communication using the channel Ch_JT_CMM.

[0461] Thereafter, the wireless device 3 transmits a CTS to the master base station 1 by wireless communication using the channel Ch_JT_CMM.

[0462] Then, when the master base station 1 receives a CTS from the wireless device 3 by wireless communication using the channel Ch_JT_CMM, it sends a confirmation frame F Ｓ＿ＰＢ and generates a confirmation frame F by wireless communication using the channel Ch_JT_CMM. Ｓ＿ＰＢ to the slave base station 2-1.

[0463] The slave base station 2-1 transmits a confirmation frame F via wireless communication using the channel Ch_JT_CMM. Ｓ＿ＰＢ When the slave base station 2-1 receives the JT_OK signal from the master base station 1, it determines whether or not joint transmission JT with the master base station 1 is possible. When the slave base station 2-1 determines that joint transmission JT with the master base station 1 is possible, it sends a response frame F including "JT_OK". ＲＳＰ When it is determined that joint transmission JT with the master base station 1 is impossible, a response frame F ＲＳＰ Generate.

[0464] Then, the slave base station 2-1 transmits a confirmation frame F via wireless communication using the channel Ch_JT_CMM. Ｓ＿ＰＢ Response frame F to ＲＳＰ (Response frame F containing "JT_OK" or "JT_NG" ＲＳＰ ) to the master base station 1.

[0465] The master base station 1 transmits a response frame F via wireless communication using the channel Ch_JT_CMM. ＲＳＰ is received from the slave base station 2-1.

[0466] Then, the master base station 1 sends a response frame F ＲＳＰ (Response frame F containing "JT_OK" ＲＳＰ ) and then determines whether joint transmission JT is possible, the amount of data d ｍｓｔ , d １ Calculate.

[0467] Thereafter, the master base station 1 executes the following steps (1) to (3).

[0468] (1) The master base station 1 transmits a "transmission timing notification" to the slave base station 2-1 by wireless communication using the channel Ch_JT_CMM, and (2) the master base station 1 transmits the transmission data d １＿ｔｒｓｍ (data volume d １(3) the master base station 1 and the slave base station 2-1 perform a process of generating a transmission frame in parallel with (1).

[0469] In this case, the above (2) is executed earliest in terms of time, the above (1) is executed in parallel with (2), and after (2) is finished, the above (3) is executed in parallel with (1). As a result, the time required for the allocation of transmission data (2) in the master base station 1 partially overlaps with the time required for the transmission of the transmission timing notification (1), and the time required for the generation process of the transmission frame (3) in the master base station 1 and the slave base station 2-1 partially overlaps with the time required for the transmission of the transmission timing notification (1).

[0470] The allocation of transmission data in the master base station 1 (2) and the generation of transmission frames in the master base station 1 and slave base station 2-1 (3) are executed serially.

[0471] Here, (2) the master base station 1 transmits the transmission data d １＿ｔｒｓｍ (data volume d １ ) to the slave base station 2-1 in parallel with (1). １＿ｔｒｓｍ (data volume d １ The time required to distribute the transmission data (transmission data having the value .intg., .gt.) to the slave base station 2-1 and the time required to transmit the notification of the transmission timing in (1) overlap at least partially.

[0472] Furthermore, (3) the master base station 1 and the slave base station 2-1 perform the process of generating the transmission frame in parallel with (1), which means that the time required for the process of generating the transmission frame and the time required for sending the notification of the transmission timing in (1) overlap for at least a portion of the time length.

[0473] After the process of generating the transmission frame is completed, the master base station 1 and the slave base station 2-1 each transmit a transmission frame F ｍｓｔ＿ｔｒｓｍ (=PPDU0),F １＿ｔｒｓｍ (=PPDU1) is simultaneously transmitted to wireless device 3.

[0474] Then, the wireless device 3 receives a transmission frame F from the master base station 1 by wireless communication using the channel Ch_JT_CMM. ｍｓｔ＿ｔｒｓｍ (=PPDU0) is received from the slave base station 2-1, and the transmission frame F １＿ｔｒｓｍ Upon receiving (=PPDU1), the master base station 1 transmits a Block Ack to the master base station 1 via wireless communication using the channel Ch_JT_CMM.

[0475] Then, the master base station 1 receives a Block Ack from the wireless device 3 by wireless communication using the channel Ch_JT_CMM, and the wireless device 3 receives a transmission frame F transmitted by the joint transmission JT between the master base station 1 and the slave base station 2-1. ｍｓｔ＿ｔｒｓｍ (=PPDU0),F １＿ｔｒｓｍ (=PPDU1) is received.

[0476] Therefore, the master base station 1 transmits a “transmission timing notification” to the slave base station 2-1 and transmits the transmission data d via the backhaul 4. １＿ｔｒｓｍ to the slave base station 2-1, and after the master base station 1 and the slave base station 2-1 perform the transmission frame generation process, they each generate a transmission frame F ｍｓｔ＿ｔｒｓｍ (=PPDU0),F １＿ｔｒｓｍ (=PPDU1) is transmitted to wireless device 3 on channel Ch_JT_CMM.

[0477] 23. Also, when channel Ch_JT_CMM is used, the frame processing consists of the frame processing shown in FIG. 9 and the frame processing shown in FIG. 16, modified in the same manner as described in FIG.

[0478] When the channel Ch_JT_CMM is used, the operation of the communication system 10 is performed according to the flowchart shown in Figures 10 and 11, to which an additional step "the master base station 1 transmits the channel Ch_JT_CMM to the slave base station and the wireless device 3 using the channel Ch_JT_CMM" has been added when it is determined that joint transmission JT is possible ("YES" in step S9).

[0479] Furthermore, when channel Ch_JT_CMM is used, the operation of communication system 10A is performed according to the flowchart shown in Figures 17 and 18, to which an additional step "the master base station 1A transmits channel Ch_JT_CMM to the slave base station and wireless device 3 using channel Ch_JT_CMM" has been added when it is determined that joint transmission JT is possible ("YES" in step S9).

[0480] Fig. 24 is another schematic diagram of the master base station 1 shown in Fig. 2. The master base station 1 shown in Fig. 2 may be constituted by a master base station 1B shown in Fig. 24.

[0481] Referring to Figure 24, the master base station 1B is the same as the master base station 1 shown in Figure 2, except that the receiving unit 12, control unit 13, radio unit 14, generating unit 15, generating unit 16 and transmitting unit 17 of the master base station 1 shown in Figure 2 are replaced with a receiving circuit 12A, a control circuit 13A, a radio circuit 14A, a generating circuit 15A, a generating circuit 16A and a transmitting circuit 17A, respectively.

[0482] The receiving circuit 12A, the control circuit 13A, the radio circuit 14A, the generating circuit 15A, the generating circuit 16A and the transmitting circuit 17A perform the same operations as the receiving unit 12, the control unit 13, the radio unit 14, the generating unit 15, the generating unit 16 and the transmitting unit 17 described above, respectively.

[0483] Fig. 25 is another schematic diagram of the master base station 1A shown in Fig. 13. The master base station 1A shown in Fig. 13 may be configured as a master base station 1C shown in Fig. 25.

[0484] 25, the master base station 1C is the same as the master base station 1A shown in FIG. 13 except that the receiving unit 12, control unit 13A, radio unit 14, generation unit 15, generation unit 16, transmission unit 17 and arithmetic unit 18 of the master base station 1A shown in FIG. 13 are replaced with a receiving circuit 12A, a control circuit 13B, a radio circuit 14A, a generation circuit 15A, a generation circuit 16A, a transmission circuit 17A and arithmetic circuit 18A, respectively.

[0485] The receiving circuit 12A, the control circuit 13B, the radio circuit 14A, the generating circuit 15A, the generating circuit 16A, the transmitting circuit 17A and the arithmetic circuit 18A perform the same operations as the receiving unit 12, the control unit 13A, the radio unit 14, the generating unit 15, the generating unit 16, the transmitting unit 17 and the arithmetic unit 18 described above, respectively.

[0486] Fig. 26 is another schematic diagram of the slave base station 2-1 shown in Fig. 3. The slave base station 2-1 shown in Fig. 3 may be constituted by the slave base station 2-1A shown in Fig. 26.

[0487] Referring to FIG. 26, the slave base station 2-1A is the same as the slave base station 2-1 shown in FIG. 3, except that the radio unit 22, receiving unit 23, control unit 24, and generating unit 25 shown in FIG. 3 are replaced with a radio circuit 22A, a receiving circuit 23A, a control circuit 24A, and a generating circuit 25A, respectively.

[0488] The radio circuit 22A, the receiving circuit 23A, the control circuit 24A and the generating circuit 25A perform the same operations as the radio unit 22, the receiving unit 23, the control unit 24 and the generating unit 25 described above, respectively.

[0489] Each of the slave base stations 2-2 to 2-n (or slave base station 2-m) described above has the same configuration as the slave base station 2-1A shown in FIG.

[0490] Figure 27 is another schematic diagram of the wireless device 3 shown in Figure 4. The wireless device 3 shown in Figure 4 may be a wireless device 3A shown in Figure 27.

[0491] 27, a wireless device 3A is the same as the wireless device 3 shown in FIG. 4, except that the wireless unit 32 and the control unit 33 shown in FIG. 4 are replaced with a wireless circuit 32A and a control circuit 33A, respectively.

[0492] The radio circuit 32A and the control circuit 33A perform the same operations as the radio unit 32 and the control unit 33 described above, respectively.

[0493] In the above-mentioned first embodiment, it has been explained that: (1) the master base station transmits a notification of the transmission timing to the slave base station via in-band (i.e., via wireless communication using the same channel as the channel used when the master base station and each of the m slave base stations transmit data to the wireless device); (2) the master base station distributes the transmission data to the slave base stations via the backhaul in parallel with (1); and (3) the master base station and the slave base station perform the transmission frame generation process in parallel with (1).

[0494] In the first embodiment, it has been explained that the above (2) and (3) do not have to be executed in parallel with (1).

[0495] Furthermore, in the above-mentioned second embodiment, it has been explained that: (1A) the master base station transmits a padding PD having a length consisting of notification of transmission timing and padding time to the slave base station via in-band (= via wireless communication using the same channel as the channel when the master base station and each of the m slave base stations transmit data to the wireless device); (2A) the master base station distributes transmission data to the slave base stations via the backhaul in parallel with the transmission of the padding PD in (1A); and (3A) the master base station and the slave base station perform transmission frame generation processing in parallel with the transmission of the padding PD in (1A).

[0496] In the second embodiment, it has been explained that the above (2A) and (3A) do not have to be executed in parallel with the transmission of the padding PD in (1A).

[0497] As a result, the first and second embodiments have in common the following points: (1) the master base station transmits a notification of the transmission timing to the slave base station via in-band (i.e., via wireless communication using the same channel as the channel used when the master base station and each of the m slave base stations transmit data to the wireless device); (2) the master base station distributes the transmission data to the slave base stations via the backhaul; and (3) the master base station and the slave base station perform the transmission frame generation process.

[0498] Therefore, according to an embodiment of the present invention, a communication method is a communication method for transmitting transmission data D_trsm to a wireless device using joint transmission, in which a master base station and m (m is an integer satisfying 1≦m≦n) slave base stations out of n (n is an integer equal to or greater than 1) slave base stations jointly transmit transmission data D_trsm to the wireless device by CSMA / CA wireless communication using one channel, the communication method comprising: a first step in which the master base station determines whether joint transmission is possible; a second step in which the master base station calculates m data amounts of the m transmission data to be allocated to the m slave base stations respectively when it is determined in the first step that joint transmission is possible; a third step in which the master base station, after the second step, transmits transmission timing notifications to the m slave base stations by wireless communication, notifying the timing of transmitting a transmission frame to the wireless device; and a fourth step in which the master base station, after the second step, transmits m transmission data, each having m data amounts, to the m slave base stations using backhaul, The method may include a fifth step in which the master base station and each of the m slave base stations perform a transmission frame generation process, which is a process of generating a transmission frame based on the amount of data, after the second step; a sixth step in which the master base station and the m slave base stations transmit (m+1) transmission frames to the wireless device by joint transmission when the transmission timing arrives; and a seventh step in which the master base station receives a block ACK from the wireless device, after the sixth step, which sends an ACK in bulk to confirm reception of the frames.

[0499] If the communication method includes the first to seventh steps, m pieces of transmission data, each having m amounts of data, are transmitted to m slave base stations using the backhaul, so wireless resources are less constrained than when m pieces of transmission data, each having m amounts of data, are transmitted in-band, which results in improved throughput when the master base station and the m slave base stations transmit transmission frames to wireless devices.

[0500] When the channel Ch_JT_CMM is used, the communication method defines a state in which a base station and a wireless device can transmit and receive data to and from each other in a wireless LAN as being "under control," defines a channel that the base station uses in common with all wireless devices under its control as a primary channel, defines a channel that the base station can use together with the primary channel to expand the bandwidth of communication with wireless devices under its control as a secondary channel, and defines the common part of the "primary channel and secondary channel," or the widest channel of the common part, as "under the condition that the primary channels of all base stations and wireless devices are included" among the master base station, slave base station, and wireless devices participating in the joint transmission JT. When channel Ch_JT_CMM is a channel consisting of "a configuration in which the primary channel of the wireless device is part of a group and includes a primary channel," the channel satisfies the following conditions: a first condition that the primary channel of the wireless device is the same as the primary channel of the master base station; a second condition that the secondary channel of the wireless device is within the range of the secondary channel of the master base station; a third condition that the primary channels of m slave base stations are within the range of the primary channel or secondary channel of the wireless device; and a fourth condition that, when the primary channel of the wireless device is different from the primary channels of the m slave base stations, the primary channel of the wireless device is within the range of the secondary channels of the m slave base stations. In the sixth step, the master base station and the m slave base stations use "CSMA / CA wireless communication using channel Ch_JT_CMM" instead of "CSMA / CA wireless communication using one channel," and transmit (m+1) transmission frames to the wireless device by joint transmission when the transmission timing arrives.

[0501] Furthermore, according to an embodiment of the present invention, a communication system transmits transmission data D_trsm to a wireless device using joint transmission in which a master base station and m (m is an integer satisfying 1≦m≦n) slave base stations out of n (n is an integer equal to or greater than 1) slave base stations jointly transmit transmission data D_trsm to the wireless device by CSMA / CA wireless communication using one channel, the communication system comprising: the master base station, when it is determined that joint transmission is possible, performing: a calculation process of calculating m data amounts of the m transmission data to be assigned to each of the m slave base stations; a first transmission process of, after the calculation process, transmitting to the m slave base stations by wireless communication, transmission timing notifications that notify the timing of transmitting the transmission frames to the wireless device; a second transmission process of, after the calculation process, transmitting to the m slave base stations using a backhaul, the m transmission data, each having m data amounts; and a transmission frame generation process of generating a transmission frame based on its own transmission data after the calculation process; The system comprises m slave base stations, each of which performs a first receiving process for receiving notification of transmission timing from the master base station and a second receiving process for receiving m pieces of transmission data from the master base station using a backhaul; and a wireless device that receives (m+1) transmission frames transmitted by joint transmission between the master base station and the m slave base stations, and transmits a block ACK to the master base station to collectively acknowledge reception of the frames, wherein each of the m slave base stations performs a transmission frame generation process for generating a transmission frame based on the transmission data received in the second receiving process, and when it is transmission timing, the master base station and the m slave base stations transmit the (m+1) transmission frames to the wireless device by joint transmission, and the master base station receives the block ACK from the wireless device after transmitting the (m+1) transmission frames to the wireless device by joint transmission with the m slave base stations.

[0502] If a communication system includes a master base station, m slave base stations, and a wireless device, the master base station transmits m pieces of transmission data, each having m amounts of data, to the m slave base stations using the backhaul, thereby reducing the strain on wireless resources compared to when the m pieces of transmission data, each having m amounts of data, are transmitted in-band. As a result, the throughput when the master base station and the m slave base stations transmit transmission frames to the wireless device can be improved.

[0503] When the channel Ch_JT_CMM is used, the communication system defines a state in which a base station and a wireless device can transmit and receive data to and from each other in a wireless LAN as being "under its control," defines a channel that the base station uses in common with all wireless devices under its control as a primary channel, defines a channel that the base station can use together with the primary channel to expand the bandwidth of communication with wireless devices under its control as a secondary channel, and defines a common part of the "primary channel and secondary channel," or the widest common part of the "common channel," under the condition that the primary channels of all base stations and wireless devices are included, among the master base station, slave base station, and wireless devices participating in the joint transmission JT. When a channel consisting of "a configuration in which the wireless device is part of a network and includes a primary channel" is defined as channel Ch_JT_CMM, the following conditions are satisfied: a first condition that the primary channel of the wireless device is the same as the primary channel of the master base station; a second condition that the secondary channel of the wireless device is within the range of the secondary channel of the master base station; a third condition that the primary channels of m slave base stations are within the range of the primary channel or secondary channel of the wireless device; and a fourth condition that, when the primary channel of the wireless device is different from the primary channels of the m slave base stations, the primary channel of the wireless device is within the range of the secondary channels of the m slave base stations. The master base station and the m slave base stations may transmit (m+1) transmission frames to the wireless device by joint transmission when the transmission timing arrives, using "CSMA / CA wireless communication using channel Ch_JT_CMM" instead of "CSMA / CA wireless communication using one channel."

[0504] In the embodiment of the present invention, step S9 shown in FIG. 10 or step S9 shown in FIG. 17 constitutes a "first step" in which the master base station determines whether joint transmission is possible.

[0505] Furthermore, in an embodiment of the present invention, step S10 shown in FIG. 10 or step S10 shown in FIG. 17 constitutes a "second step" in which the master base station calculates m data amounts of m transmission data to be allocated to each of the m slave base stations when it is determined in the first step that joint transmission is possible.

[0506] Furthermore, in an embodiment of the present invention, step S11 shown in FIG. 10 , “(1) the master base station transmits a transmission timing notification to the slave base station via in-band (= via wireless communication using the same channel as the channel used when the master base station and each of the m slave base stations transmit data to the wireless device)” constitutes a “third step” in which, when it is determined in the first step that joint transmission is possible, the master base station transmits a transmission timing notification to the m slave base stations via wireless communication, notifying them of the timing at which to transmit a transmission frame to the wireless device.

[0507] Furthermore, in an embodiment of the present invention, "(2) The master base station allocates transmission data to the slave base stations via the backhaul" in step S11 shown in FIG. 10 constitutes a "fourth step" in which, when it is determined in the first step that joint transmission is possible, the master base station transmits m pieces of transmission data, each having m amounts of data, to m slave base stations using the backhaul.

[0508] Furthermore, in an embodiment of the present invention, "(3) The master base station and the slave base station perform a transmission frame generation process" in step S11 shown in FIG. 10 constitutes a "fifth step" in which, when it is determined in the first step that joint transmission is possible, the master base station and each of the m slave base stations perform a transmission frame generation process, which is a process for generating a transmission frame based on the amount of data.

[0509] Furthermore, in an embodiment of the present invention, step S12 in FIG. 11 constitutes a "sixth step" in which, when the transmission timing arrives, the master base station and m slave base stations transmit (m+1) transmission frames to the wireless device by joint transmission.

[0510] Furthermore, in this embodiment of the present invention, step S15 in FIG. 11 constitutes a "seventh step" in which the master base station receives a block ACK from the wireless device after the sixth step, which is an ACK that collectively confirms reception of the frame.

[0511] Furthermore, in an embodiment of the present invention, step S16 in Figure 11 or 18, "only the master base station transmits the transmission data to the wireless device," constitutes an "eighth step" in which, when it is determined in the first step that joint transmission is not possible, only the master base station transmits a transmission frame including the transmission data D_trsm to the wireless device by wireless communication, instead of steps 2 to 6.

[0512] Furthermore, in the embodiment of the present invention, step S10 shown in FIG. 10 or step S10 shown in FIG. 17 constitutes a "calculation process" that calculates m data amounts of m transmission data to be allocated to m slave base stations, respectively, when it is determined that joint transmission is possible.

[0513] Furthermore, in an embodiment of the present invention, "(1) The master base station transmits a notification of the transmission timing to the slave base station via in-band (= via wireless communication using the same channel as the channel used when the master base station and each of the m slave base stations transmit data to the wireless device)" in step S11 shown in FIG. 10 constitutes a "first transmission process" in which, after the calculation process, a transmission timing notification is transmitted to the m slave base stations via wireless communication to notify them of the timing at which to transmit the transmission frame to the wireless device.

[0514] Furthermore, in an embodiment of the present invention, "(2) The master base station allocates transmission data to the slave base stations via the backhaul" in step S11 shown in FIG. 10 constitutes a "second transmission process" in which, after the calculation process, m pieces of transmission data, each having m data amounts, are transmitted to m slave base stations using the backhaul.

[0515] Furthermore, in an embodiment of the present invention, in FIG. 9, the slave base stations 2-1 and 2-2 receiving notification of transmission timing from the master base station constitutes a "first reception process" in which each of the m slave base stations receives notification of transmission timing from the master base station.

[0516] Furthermore, in an embodiment of the present invention, in FIG. 9, the reception of transmission data allocation by the slave base stations 2-1 and 2-2 constitutes a "second reception process" in which m transmission data are each received from the master base station using the backhaul.

[0517] The embodiments disclosed herein should be considered to be illustrative in all respects and not restrictive. The scope of the present invention is defined by the claims, not by the description of the above embodiments, and is intended to include all modifications within the meaning and scope of the claims.

[0518] The present invention is applicable to a communication method and a communication system.

Claims

1. A communication method for transmitting transmission data D_trsm to a wireless device by using cooperative transmission in which a master base station and m (m is an integer satisfying 1 ≦ m ≦ n) out of n (n is an integer of 1 or more) slave base stations jointly transmit the transmission data D_trsm to the wireless device by CSMA / CA-based wireless communication using one channel, the method including: a first step in which the master base station determines whether the cooperative transmission is possible; a second step in which, when it is determined in the first step that the cooperative transmission is possible, the master base station calculates amounts of m pieces of transmission data to be respectively assigned to the m slave base stations; a third step in which, after the second step, the master base station transmits, by the wireless communication, a transmission timing notification for notifying a timing for transmitting a transmission frame to the wireless device to the m slave base stations; a fourth step in which, after the second step, the master base station transmits, using a backhaul, the m pieces of transmission data respectively having the m amounts of data to the m slave base stations; a fifth step in which each of the master base station and the m slave base stations performs a transmission frame generation process that is a process of generating a transmission frame based on the amount of data after the second step; a sixth step in which, when the transmission timing arrives, the master base station and the m slave base stations transmit the (m + 1) transmission frames to the wireless device by the cooperative transmission; and a seventh step in which, after the sixth step, the master base station receives a block Ack in which Acks for confirming reception of frames are collectively performed from the wireless device.

2. The communication method according to claim 1, wherein the fourth step and the fifth step are executed in parallel with the third step.

3. In the second step, the master base station calculates, for each of the m slave base stations, the amount of data to be allocated to the slave base station that is the target of data amount calculation, which is proportional to the radio transmission rate of the transmission data in the slave base station that is the target of data amount calculation and inversely proportional to the sum of the radio transmission rate of the transmission data in the master base station and the m radio transmission rates in the m slave base stations, to calculate the m amounts of data. The communication method according to claim 1.

4. In the third step, the master base station transmits, by wireless communication to the m slave base stations, padding having a length consisting of padding time and notification of the transmission timing. The communication method according to claim 1.

5. The padding time consists of the maximum padding time among the m padding times in the m slave base stations. The communication method according to claim 4.

6. In the third step, the master base station calculates, for each of the m slave base stations, the padding time of one slave base station by using the transmission time when transmitting the transmission data having the amount of data allocated to one slave base station to the one slave base station by backhaul, the generation processing time of the transmission frame in the one slave base station, the transmission time when transmitting the notification of the transmission timing to the one slave base station, and the SIFS time in the CSMA / CA method, to calculate the m padding times. The communication method according to claim 5.

7. In the third step, the master base station calculates the padding time of one slave base station by subtracting the transmission time of the notification of the transmission timing and the SIFS time from the addition result of the transmission time and the generation processing time of the transmission frame. The communication method according to claim 6.

8. In the generation processing of the transmission frame in the fifth step, based on each of the m pieces of transmission data transmitted by the master base station in the fourth step, the m slave base stations generate, respectively, m transmission frames to be transmitted to the wireless devices, which are m transmission frames consisting of frames of the physical layer. The communication method according to claim 1.

9. When the master base station determines in the first step that the joint transmission is impossible, instead of the second step to the sixth step, the communication method according to claim 1 further comprises an eighth step of transmitting, by itself only, a transmission frame including the transmission data D_trsm to the wireless device by the wireless communication.

10. In a wireless LAN, a state in which a base station and a wireless device can mutually transmit and receive is defined as "being under the control of", a channel commonly used among all wireless devices under the control of the base station is defined as a primary channel, a channel that can be used together with the primary channel to expand the bandwidth of communication between the base station and wireless devices under its control is defined as a secondary channel, and when a channel consisting of "under the condition that the primary channels of all base stations and wireless devices are included, the common part of the 'primary channel and secondary channel', or a part of the widest channel in the common part, and including the primary channel" is defined as a channel Ch_JT_CMM among the master base station, slave base stations, and wireless devices participating in joint transmission JT, the first condition that the primary channel of the wireless device is the same as the primary channel of the master base station, the second condition that the secondary channel of the wireless device is within the range of the secondary channel of the master base station, the third condition that the primary channels of the m slave base stations are within the range of the primary channel or secondary channel of the wireless device, and when the primary channel of the wireless device is different from the primary channels of the m slave base stations, the fourth condition that the primary channel of the wireless device is within the range of the secondary channels of the m slave base stations are satisfied. When the master base station and the m slave base stations use "CSMA / CA-based wireless communication using the channel Ch_JT_CMM" instead of "CSMA / CA-based wireless communication using the one channel" in the sixth step at the transmission timing, the (m + 1) transmission frames are transmitted to the wireless device by the joint transmission. The communication method according to claim 1.

11. A communication system for transmitting transmission data D_trsm to a wireless device by using cooperative transmission in which a master base station and m (where m is an integer satisfying 1 ≦ m ≦ n) out of n (n is an integer of 1 or more) slave base stations jointly transmit the transmission data D_trsm to the wireless device by CSMA / CA-based wireless communication using one channel. When it is determined that the cooperative transmission is possible, a calculation process for calculating the amounts of m pieces of transmission data to be respectively assigned to the m slave base stations, a first transmission process for transmitting a notification of transmission timing for notifying the timing of transmitting a transmission frame to the wireless device by the wireless communication to the m slave base stations after the calculation process, a second transmission process for transmitting the m pieces of transmission data each having the m data amounts to the m slave base stations by using a backhaul after the calculation process, and a generation process for generating a transmission frame based on its own transmission data after the calculation process. A master base station that executes the generation process of the transmission frame, which is a process of generating a transmission frame; m slave base stations that each execute a first reception process of receiving the notification of the transmission timing from the master base station and a second reception process of receiving the m pieces of transmission data from the master base station by using the backhaul; and a wireless device that receives the (m + 1) transmission frames transmitted by the cooperative transmission between the master base station and the m slave base stations and transmits a block Ack for collectively performing Acks for confirming frame reception to the master base station. Each of the m slave base stations executes a generation process for generating a transmission frame based on the transmission data received in the second reception process. The master base station and the m slave base stations transmit the (m + 1) transmission frames to the wireless device by the cooperative transmission when the transmission timing arrives. After transmitting the (m + 1) transmission frames to the wireless device by the cooperative transmission with the m slave base stations, the master base station receives the block Ack from the wireless device.

12. The master base station executes the second transmission process and the generation process of the transmission frame in parallel with the first transmission process, and each of the m slave base stations executes the generation process of the transmission frame in parallel with the first transmission process. The communication system according to claim 11.

13. In the calculation process, the master base station calculates the data amount to be allocated to the slave base station whose data amount is to be calculated in proportion to the wireless transmission speed of the transmission data in the slave base station and in inverse proportion to the sum of the wireless transmission speed of the transmission data in the master base station and the m wireless transmission speeds in the m slave base stations for all of the m slave base stations to calculate the m data amounts. The communication system according to claim 11.

14. In the first transmission process, the master base station transmits padding having a length consisting of padding time and the notification of the transmission timing to the m slave base stations by wireless communication. The communication system according to claim 11.

15. The padding time consists of the maximum padding time among the m padding times of the m slave base stations. The communication system according to claim 14.

16. In the first transmission process, the master base station calculates the padding time of one slave base station by using the transmission time when transmitting the transmission data having the data amount allocated to one slave base station to the one slave base station by backhaul, the generation process time of the transmission frame in the one slave base station, the transmission time when transmitting the notification of the transmission timing to the one slave base station, and the SIFS time in the CSMA / CA method for all of the m slave base stations to calculate the m padding times. The communication system according to claim 15.

17. In the first transmission process, the master base station calculates the padding time of one slave base station by subtracting the transmission time of the notification of the transmission timing and the SIFS time from the addition result of the transmission time and the generation process time of the transmission frame. The communication system according to claim 16.

18. The m slave base stations generate, in the transmission frame generation process, m transmission frames to be transmitted to the wireless device, respectively, each of the m transmission frames being composed of a physical layer frame, based on each of the m pieces of transmission data transmitted by the master base station in the second transmission process. The communication system according to claim 11.

19. When the master base station determines that the joint transmission is impossible, instead of the first transmission process, the calculation process, the second transmission process, the transmission frame generation process, and the transmission of the (m + 1) transmission frames to the wireless device by the joint transmission with the m slave base stations, the master base station alone transmits a transmission frame including the transmission data D_trsm to the wireless device by the wireless communication. The communication system according to claim 11.

20. In a wireless LAN, the state where a base station and a wireless device can communicate with each other is defined as "being subordinate to". The channel commonly used between the base station and all wireless devices subordinate to itself is defined as the primary channel. The channels that can be used together with the primary channel to expand the communication bandwidth between the base station and the wireless devices subordinate to itself are defined as secondary channels. When a channel consisting of "the common part of the 'primary channel and secondary channel', or a part of the widest channel in the common part, and including the primary channel, under the condition that the primary channels of all base stations and wireless devices are included" among the master base station, slave base stations, and wireless devices participating in the joint transmission JT is defined as the channel Ch_JT_CMM, the first condition that the primary channel of the wireless device is the same as the primary channel of the master base station, the second condition that the secondary channel of the wireless device is within the range of the secondary channel of the master base station, the third condition that the primary channels of the m slave base stations are within the range of the primary channel or secondary channel of the wireless device, and the fourth condition that when the primary channel of the wireless device is different from the primary channels of the m slave base stations, the primary channel of the wireless device is within the range of the secondary channels of the m slave base stations are satisfied. The master base station and the m slave base stations use "CSMA / CA-based wireless communication using the channel Ch_JT_CMM" instead of "CSMA / CA-based wireless communication using the one channel", and at the transmission timing, transmit the (m + 1) transmission frames to the wireless device by the joint transmission. The communication system according to claim 11.

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