Wireless communication system, base station apparatus, and wireless communication method

Abstract

To improve the transmission efficiency of terminal-coordinated MIMO communication, in which a plurality of terminal devices are coordinated to perform MIMO communication.SOLUTION: A wireless communication system includes a base station device and a plurality of terminal devices. The base station device includes a terminal information collection unit configured to collect terminal information including information indicating the coordination status of terminal-coordinated MIMO communication, from the terminal devices; and a wireless communication unit configured to transmit data in the terminal-coordinated MIMO communication to the terminal devices in which the number of coordinated terminals that are coordinated in the terminal-coordinated MIMO communication is equal to or more than a predetermined number based on the terminal information, and to transmit data in MU-MIMO communication to the terminal devices in which the number of coordinated terminals is less than the predetermined number.SELECTED DRAWING: Figure 2

Description

Technical Field

[0001] The present invention relates to a wireless communication system, a base station device, and a wireless communication method.

Background Art

[0002] As a technology currently widely used for increasing the capacity in a wireless communication system, there is MIMO (Multiple Input Multiple Output) that performs spatial division multiplexing in the same wireless channel using multiple antennas, and it is adopted in various wireless systems.

[0003] Also, a transmission method for performing wireless communication by combining MIMO communication using terminal joint interference cancellation and MU (Multi User)-MIMO communication has been studied (see, for example, Non-Patent Document 1).

Prior Art Documents

Non-Patent Documents

[0004]

Non-Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0005] In the technology disclosed in Non-Patent Document 1, multiple terminal devices jointly cancel interference, thereby realizing spatial multiplexing transmission (hereinafter referred to as terminal cooperation MIMO communication) with a number of antennas greater than the number of antennas each terminal device has. In this technology, the base station device determines whether to transmit data by terminal cooperation MIMO communication or to transmit data by MU-MIMO communication based on whether the terminal device is in an isolated state, and then performs subsequent data transmission.

[0006] However, in reality, although the other terminal devices to be coordinated vary depending on the destination terminal device to which data is to be transmitted, in the conventional technology shown in Non-Patent Document 1, the variation of the other terminal devices to be coordinated is not considered, and the transmission efficiency of the terminal-coordinated MIMO communication may decrease.

[0007] An embodiment of the present invention has been made in view of the above problems, and improves the transmission efficiency of terminal-coordinated MIMO communication in which a plurality of terminal devices cooperate to perform MIMO communication.

Means for Solving the Problems

[0008] In order to solve the above problems, a wireless communication system according to an embodiment of the present invention is a wireless communication system including a base station device and a plurality of terminal devices, wherein the base station device is configured to collect terminal information including information indicating a cooperation state of terminal-coordinated MIMO communication from the terminal device, and based on the terminal information, for the terminal devices in which the number of cooperating terminal devices in the terminal-coordinated MIMO communication is equal to or more than a predetermined number, transmit data in the terminal-coordinated MIMO communication, and for the terminal devices in which the number of cooperating terminal devices is less than the predetermined number, transmit data in MU-MIMO communication.

Effects of the Invention

[0009] According to the embodiment of the present invention, it is possible to improve the transmission efficiency of terminal-coordinated MIMO communication in which a plurality of terminal devices cooperate to perform MIMO communication.

Brief Description of the Drawings

[0010]

Figure 1

Figure 2

Figure 3

Figure 4

Figure 5

Figure 6

Figure 7

Embodiments for Carrying Out the Invention

[0011] Hereinafter, embodiments of the present invention (the present embodiment) will be described with reference to the drawings. The embodiments described below are merely examples, and the embodiments to which the present invention is applied are not limited to the following embodiments.

[0012] <System Configuration> FIG. 1 is a diagram showing an example of the system configuration of the wireless communication system according to the present embodiment. The wireless communication system 1 includes, for example, as shown in FIG. 1, a base station apparatus 10 and a plurality of terminal apparatuses 20-1 to 20-6 that can communicate with the base station apparatus 10 by wireless communication. In the following description, when indicating an arbitrary terminal apparatus among the plurality of terminal apparatuses 20-1 to 20-6, "terminal apparatus 20" is used. Also, the number of terminal apparatuses 20 shown in FIG. 1 is an example, and the number of terminal apparatuses 20 may be two or more other numbers.

[0013] The wireless communication system 1 has a function, for example, in which other terminal apparatuses 20-2 to 20-4 that cooperate with the destination terminal apparatus 20-1 relay and transmit the wireless signal received from the base station apparatus 10 to the destination terminal apparatus 20-1. Further, the wireless communication system 1 performs terminal cooperation MIMO communication 30 to expand the capacity of MIMO transmission using the wireless signal 12 received from the base station apparatus 10 and the wireless signals 21 relayed and transmitted from other terminal apparatuses 20-2 to 20-4 by the destination terminal apparatus 20-1. Furthermore, the wireless communication system 1 performs individual MU (Multi User)-MIMO communication 40 with, for example, terminal apparatuses 20-5 and 20-6 that are not cooperating with other terminal apparatuses 20.

[0014] In the conventional technology disclosed in Non-Patent Document 1, the base station device 10 classifies a plurality of terminal devices 20-1 to 20-6 into a non-isolated state and an isolated state. For example, for non-isolated terminal devices such as the terminal device 20-1, data is transmitted by terminal cooperative MIMO communication. On the other hand, the base station device 10 individually transmits data by MU-MIMO communication to isolated terminal devices such as the terminal device 20-6, for example.

[0015] However, in view of the actual usage situation, it is considered that a considerable number of terminal devices 20 that are not in a completely isolated state but are partially cooperative (for example, cooperative with about one or two devices) will occur. However, in the conventional technology, partially cooperative terminals are not considered. In addition, it is conceivable that depending on the destination terminal device 20, other terminal devices 20 that require cooperation change, and thereby the isolated state of the terminal device 20 fluctuates. However, this has not been considered in the conventional technology. As a result, in the conventional technology, for example, a terminal device 20 that should be treated as an isolated state may be treated as a non-isolated state, resulting in a decrease in the transmission efficiency of terminal cooperative MIMO communication.

[0016] Therefore, in the wireless communication system 1 according to the present embodiment, the base station device 10 collects terminal information including information indicating the cooperation state of the terminal cooperative MIMO communication 30 from the terminal device 20. Further, based on the collected terminal information, the base station device 10 transmits data by the terminal cooperative MIMO communication 30 to the terminal device 20 in which the number of cooperative terminals, which is the number of other terminal devices 20 that cooperate in the terminal cooperative MIMO communication 30, is equal to or more than a predetermined number. On the other hand, the base station device 10 individually transmits data by, for example, MU-MIMO communication to the terminal device 20 in which the number of cooperative terminals is less than the predetermined number. Furthermore, the base station device 10 dynamically controls whether to transmit data by the terminal cooperative MIMO communication or to transmit data by the MU-MIMO communication to the destination terminal device 20 of the communication by repeatedly executing the above processing.

[0017] Accordingly, according to the wireless communication system 1 according to the present embodiment, it is possible to improve the transmission efficiency of the terminal cooperation MIMO communication that performs MIMO communication by cooperating a plurality of terminal devices 20.

[0018] <Functional configuration of the wireless communication system> FIG. 2 is a diagram showing an example of the functional configuration of the wireless communication system according to the present embodiment.

[0019] (Functional configuration of the terminal device) The terminal device 20 includes, for example, a computer configuration, and when the computer executes a predetermined program stored in a storage medium or the like, it realizes a wireless communication unit 211, an inter-terminal cooperation unit 212, a wireless signal processing unit 213, and the like. Note that at least a part of each of the above functional configurations may be realized by hardware. Also, in FIG. 2, it is assumed that the terminal devices 20-2, ··· have the same functional configuration as the terminal device 20-1.

[0020] The wireless communication unit 211 executes wireless communication processing for performing wireless communication with the base station device 10 based on a predetermined wireless communication standard. For example, the wireless communication unit 211 transmits and receives control information with the base station device 10 and transmits terminal information to the base station device 10. Also, the wireless communication unit 211 uses a plurality of antennas 214 to transmit and receive data by MIMO signals with the base station device 10.

[0021] The inter-terminal cooperation unit 212 establishes a wireless link for relay communication that relays the wireless signal of the terminal cooperation MIMO communication received from the base station apparatus 10 to the destination terminal apparatus 20, using the wireless communication unit 211. Also, the inter-terminal cooperation unit 212 controls the relay communication for relaying the received wireless signal to the destination terminal apparatus 20 according to the control information included in the wireless signal received from the base station apparatus 10. For example, when the wireless signal received by the wireless communication unit 211 is a wireless signal addressed to another terminal apparatus 20-2 with reference to the control information, the inter-terminal cooperation unit 212 of the terminal apparatus 20-1 relays (transfers) the wireless signal to the other terminal apparatus 20-2 via a wireless link for relay communication. Also, the inter-terminal cooperation unit 212 of the terminal apparatus 20-1 receives the wireless signal relayed from the other terminal apparatus 20-2 to the terminal apparatus 20-1.

[0022] Preferably, the inter-terminal cooperation unit 212 performs relay communication by wireless communication using a frequency channel different from the frequency channel in which the wireless communication unit 211 receives the wireless signal from the base station apparatus 10. Note that the wireless communication method by which the wireless communication unit 211 receives the wireless signal from the base station apparatus 10 and the wireless communication method by which the wireless communication unit 211 performs relay communication may be the same wireless communication method or different wireless communication methods.

[0023] The wireless signal processing unit 213 demodulates and decodes the MOMO signal using the wireless signal addressed to its own apparatus received by the wireless communication unit 211 from the base station apparatus 10 and the wireless signal received by the inter-terminal cooperation unit 212 from another terminal apparatus 20 to receive data. Also, the wireless signal processing unit 213 generates a wireless signal that the terminal apparatus 20 transmits to the base station apparatus 10.

[0024] (Functional Configuration of Base Station Apparatus) The base station apparatus 10 includes, for example, a computer configuration, and realizes the wireless communication unit 201, the terminal information collection unit 202, the communication control unit 203, the wireless signal processing unit 204, etc. by executing a predetermined program stored in a storage medium or the like by the computer. Note that at least a part of each of the above functional configurations may be realized by hardware.

[0025] The wireless communication unit 201 executes communication processing for performing wireless communication with a plurality of terminal devices 20-1, 20-2, ··· based on a predetermined wireless communication standard. For example, the wireless communication unit 201 transmits and receives control signals to and from the terminal device 20, and receives terminal information from the terminal device 20. Further, the wireless communication unit 201 uses a plurality of antennas 11 to perform data communication with the terminal device 20 in MUMO communication such as terminal cooperation MIMO communication or MU-MIMO communication.

[0026] The terminal information collection unit 202 collects terminal information including information indicating the cooperation state of the terminal cooperation MIMO communication (hereinafter referred to as cooperation state information) from the terminal device 20 via the wireless communication unit 201. This cooperation state information includes, for example, information indicating with which other terminal device 20 the terminal device 20 is cooperating and the degree of wireless quality (e.g., received power).

[0027] Preferably, the terminal information collection unit 202 acquires terminal information including propagation path information and cooperation state information from each terminal device 20 in accordance with CSI (Channel State Information) estimation.

[0028] The communication control unit 203 executes communication control processing for dynamically controlling whether the wireless communication unit 201 transmits data to the destination terminal device 20 in terminal cooperation MIMO communication or in MU-MIMO communication based on the terminal information collected from the destination terminal device 20. For example, when the number of cooperating terminals of the destination terminal device 20 is equal to or more than a predetermined number, the communication control unit 203 controls the wireless communication unit 201 to transmit data to the destination terminal device 20 in terminal cooperation MIMO communication. On the other hand, when the number of cooperating terminals of the destination terminal device 20 is less than the predetermined number, the communication control unit 203 controls the wireless communication unit 201 to transmit data to the destination terminal device 20 in MU-MIMO communication.

[0029] As a result, the wireless communication unit 201 transmits data by means of terminal-cooperating MIMO communication to the terminal device 20 in which the number of cooperating terminals for terminal-cooperating MIMO communication is equal to or greater than a predetermined number, and transmits data by means of MU-MIMO communication to the terminal device 20 in which the number of cooperating terminals is less than the predetermined number.

[0030] The wireless signal processing unit 204 generates a MIMO communication wireless signal to be transmitted to the terminal device 20. Further, the wireless signal processing unit 204 extracts control information, data, or the like from the wireless signal received from the terminal device 20.

[0031] For example, in the example of FIG. 1, the wireless signal processing unit 204 generates a wireless signal for terminal-cooperating MIMO communication including data for the destination terminal device 20-1 and control information for the other terminal devices 20-2, 20-3, and 20-4. The control information for the other terminal devices 20-2, 20-3, and 20-4 includes, for example, information for identifying the destination terminal device 20-1, information on a frequency channel used for relay communication, information indicating the transmission order of relay communication, and information on an antenna pattern.

[0032] <Flow of processing> Subsequently, the flow of processing of the wireless communication method according to the present embodiment will be described.

[0033] (Processing of base station device) FIG. 3 is a flowchart showing an example of processing of the base station device according to the present embodiment. This processing shows an example of processing executed when the base station device 10 transmits data to a destination terminal device 20.

[0034] In step S301, the terminal information collection unit 202 of the base station device 10 collects terminal information including, for example, cooperation state information indicating the cooperation state of terminal-cooperating MIMO communication and propagation path information of a relay communication link from the destination terminal device 20.

[0035] In step S302, the communication control unit 203 of the base station apparatus 10 determines whether the number of associated terminals of the destination terminal apparatus 20 is equal to or greater than a predetermined number based on the collected association status information. Here, the number of associated terminals is the number of other terminal apparatuses 20 with which the destination terminal apparatus 20 has established a wireless link for relay communication. The predetermined number is a threshold value for the base station apparatus 10 to determine whether to transmit data by terminal cooperation MIMO communication or by MU-MIMO communication, and is assumed to be preset by, for example, a system administrator or the like.

[0036] If the number of associated terminals is equal to or greater than the predetermined number, the communication control unit 203 causes the process to proceed to step S303. On the other hand, if the number of associated terminals is less than the predetermined number, the communication control unit 203 causes the process to proceed to step S304.

[0037] When the process proceeds to step S303, the communication control unit 203 controls the base station apparatus 10 to transmit data to the destination terminal apparatus 20 by terminal cooperation MOMO communication. For example, the communication control unit 203 controls the base station apparatus 10 to execute the associated terminal determination process as shown in FIG. 4 and the data transmission process as shown in FIG. 5.

[0038] On the other hand, when the process proceeds from step S302 to step S304, the communication control unit 203 controls the base station apparatus 10 to transmit data to the destination terminal apparatus 20 by known MU-MIMO communication. Note that the data transmission by MU-MIMO communication may be the same as the conventional techniques such as Non-Patent Document 1, and thus the description thereof is omitted here.

[0039] The communication control unit 203 of the base station apparatus 10 dynamically controls whether to transmit data to the destination terminal apparatus 20 by terminal cooperation MIMO communication or by MU-MIMO communication by repeatedly executing the process of FIG. 3.

[0040] (Determination Process of Associated Terminals) FIG. 4 is a flowchart showing an example of the determination process of the cooperation terminal according to the present embodiment. This process is, for example, an example of a process executed by the communication control unit 203 of the base station apparatus 10 to determine another terminal device (cooperation terminal) that relays the radio signal of the terminal cooperation MIMO communication to the destination terminal device 20 in step S303 of FIG. 3.

[0041] In step S401, the communication control unit 203 of the base station apparatus 10 determines whether there are a plurality of other terminal devices 20 that can cooperate with the destination terminal device 20 from the cooperation state information included in the terminal information collected from the destination terminal device 20. Here, the other terminal devices 20 that can cooperate with the destination terminal device 20 are, for example, terminal devices 20 that have established a radio link for relay communication with the destination terminal device 20.

[0042] If there are a plurality of other terminal devices 20 that can cooperate, the communication control unit 203 shifts the process to step S403. On the other hand, if there is only one other terminal device 20 that can cooperate, the communication control unit 203 shifts the process to step S402.

[0043] When shifting to step S402, the communication control unit 203 determines the other terminal device 20 that can cooperate as the cooperation terminal. Note that when the predetermined number for determining whether to transmit data by terminal cooperation MIMO communication to the destination terminal device 20 is 2 or more, the processes of steps S401 and S402 are unnecessary.

[0044] When shifting to step S403, the communication control unit 203 collects terminal information from the other terminal devices 20 that can cooperate using the terminal information collection unit 202.

[0045] In step S404, the communication control unit 203 obtains the number of cooperating terminals of a plurality of other terminal devices 20 that can cooperate with the destination terminal device 20 from the collected terminal information, and selects a predetermined number of other terminal devices 20 with fewer cooperating terminals. For example, if there are six other terminal devices that can cooperate with the destination terminal device 20, and four of them are to be selected, the communication control unit 203 selects four other terminal devices 20 with fewer cooperating terminals than the other terminal devices 20.

[0046] In step S405, the communication control unit 203 determines whether a predetermined number of other terminal devices could be selected in step S404. For example, if there are multiple other terminal devices 20 with the same number of cooperating terminals among the six other terminal devices 20 that can cooperate with the destination terminal device 20, and four other terminal devices 20 cannot be selected, the communication control unit 203 determines that a predetermined number of other terminal devices cannot be selected.

[0047] If a predetermined number of other terminal devices 20 can be selected, the communication control unit 203 causes the process to proceed to step S407. On the other hand, if a predetermined number of other terminal devices 20 cannot be selected, the communication control unit 203 causes the process to proceed to step S406.

[0048] When proceeding to step S406, the communication control unit 203 selects a predetermined number of other terminal devices 20 by selecting other terminal devices 20 with higher wireless quality for relay communication from other terminal devices 20 with the same number of cooperating terminals.

[0049] When proceeding to step S407, the communication control unit 203 determines the other terminal devices 20 selected in the processes of steps S404 to S406 as cooperating terminals that relay a wireless signal to the destination terminal device 20. Note that the method for determining the cooperating terminals shown in FIG. 4 is an example, and the communication control unit 203 may determine the cooperating terminals by other determination methods.

[0050] (Data transmission process) FIG. 5 is a flowchart showing an example of data transmission processing according to this embodiment. This processing shows an example of a process in which the base station apparatus 10 transmits data to the destination terminal apparatus 20 by terminal cooperative MIMO communication using the cooperative terminal determined in the processing of FIG. 4.

[0051] In step S501, the wireless communication unit 201 of the base station apparatus 10 transmits a wireless signal of terminal cooperative MIMO communication including data to be transmitted to the destination terminal apparatus 20 and a control signal to the cooperative terminal determined in the processing of FIG. 4.

[0052] In step S502, another terminal apparatus 20 different from the destination terminal apparatus 20 relays the wireless signal received from the base station apparatus 10 to the destination terminal apparatus 20 via a wireless link for relay communication according to the control information included in the received wireless signal. For example, when another terminal apparatus 20 is the cooperative terminal determined in the processing of FIG. 4, the received wireless signal includes control information addressed to its own apparatus. In this case, another terminal apparatus 20 transmits the received wireless signal to the destination terminal apparatus 20 indicated by the control information in the indicated frequency channel and the transmission order of the relay communication.

[0053] On the other hand, when another terminal apparatus 20 is not the cooperative terminal determined in the processing of FIG. 4, the received wireless signal does not include control information addressed to its own apparatus. In this case, another terminal apparatus 20 discards the received wireless signal.

[0054] In step S503, the destination terminal apparatus 20 performs MIMO reception of data using the wireless signal addressed to its own apparatus received from the base station apparatus 10 and the wireless signal addressed to its own apparatus received from another terminal apparatus 20. Thereby, in the destination terminal apparatus 20, terminal cooperative MIMO communication can be performed to expand the capacity of MIMO transmission compared to the number of antennas provided in the destination terminal apparatus 20.

[0055] (Establishment process of link for relay communication) FIG. 6 is a flowchart showing an example of the process for establishing a wireless link for relay communication according to the present embodiment. This process is executed by the wireless communication system 1, for example, before executing the process of the base station apparatus described with reference to FIG. 3.

[0056] In step S601, the communication control unit 203 of the base station apparatus 10 transmits control information for instructing the establishment of a wireless link for relay communication to the destination terminal device 20.

[0057] In step S602, the inter-terminal cooperation unit 212 of the destination terminal device 20 transmits a predetermined broadcast signal in accordance with the instruction from the base station apparatus 10. The predetermined broadcast signal is, for example, a predetermined signal that requests other terminal devices 20 that have received the broadcast signal to transmit a connection request to the terminal device 20 that has transmitted the broadcast signal.

[0058] In step S603, the inter-terminal cooperation unit 212 of the destination terminal device 20 determines whether or not a predetermined time has elapsed since the broadcast signal was transmitted. If the predetermined time has not elapsed, the process proceeds to step S604. On the other hand, if the predetermined time has elapsed, the inter-terminal cooperation unit 212 proceeds to step S606. The predetermined time is set in advance to be the time required for other terminal devices that have received the predetermined broadcast signal to receive the connection request.

[0059] When the process proceeds to step S604, the inter-terminal cooperation unit 212 of the destination terminal device 20 determines whether or not a connection request has been received from another terminal device 20. If a connection request has been received from another terminal device 20, the process of step S605 is executed. On the other hand, if a connection request has not been received from another terminal device 20, the inter-terminal cooperation unit 212 returns the process to step S603.

[0060] When the process proceeds to step S605, the inter-terminal cooperation unit 212 of the destination terminal device 20 transmits a connection permission to the other terminal device 20 that has sent the connection request, establishes a wireless link for relay communication with the other terminal device 20 of the source, and returns the process to step S603.

[0061] Through the processes of steps S603 to S605, the inter-terminal cooperation unit 212 of the destination terminal device 20 establishes a wireless link for relay communication with other terminal devices 20 around the destination terminal device 20.

[0062] When the process proceeds from step S603 to S606, the inter-terminal cooperation unit 212 of the destination terminal device 20 transmits the establishment result of the wireless link for relay communication to the base station device 10.

[0063] Preferably, the wireless communication system 1 re-executes the process shown in FIG. 7, for example, every time a predetermined time elapses, to update the wireless link for relay communication.

[0064] As described above, the wireless communication system 1 and the wireless communication method according to the present embodiment have been described. However, the wireless communication system 1 and the wireless communication method according to the present invention can be variously modified and applied.

[0065] For example, in each of the above descriptions, each terminal device 20 has been described as having the function of terminal cooperation MIMO communication. However, the wireless communication system 1 may include a terminal device 20 that does not have the function of terminal cooperation MIMO communication. Further, even a terminal device 20 that has the function of terminal cooperation MIMO communication, for example, a terminal device 20 whose battery remaining amount has decreased and does not desire terminal cooperation MIMO communication may be treated as a terminal device 20 that does not have the function of terminal cooperation MIMO communication. Note that the base station device 10 transmits data by MU-MIMO communication to a terminal device 20 that does not have the function of terminal cooperation MIMO communication as, for example, a terminal device 20 with the number of cooperating terminals being "0".

[0066] Further, the wireless communication system 1 may treat a terminal device 20, such as a terminal device 20 that moves at high speed, etc., for which the applicable time of the terminal cooperation function is short and the effect of terminal cooperation MIMO communication is assumed to be low, as a terminal device 20 that does not have the function of terminal cooperation MIMO communication.

[0067] Also, although the description has so far assumed a single wireless communication method and wireless system, for example, a plurality of different wireless communication methods may be combined and used between the base station device - terminal device and between the terminal device - terminal device.

[0068] <Hardware Configuration Example> FIG. 7 is a diagram showing an example of the hardware configuration of the base station device and the terminal device according to the present embodiment. The base station device 10 and the terminal device 20 are provided with a configuration of a computer 1000 as shown in FIG. 7, for example. In the example of FIG. 7, the computer 1000 has a processor 1001, a memory 1002, a storage device 1003, a communication device 1004, an input device 1005, an output device 1006, a bus B, and the like.

[0069] The processor 1001 is an arithmetic device such as a CPU (Central Processing Unit) that realizes various functions by executing a predetermined program stored in a storage medium (recording medium), etc. The memory 1002 is a storage medium readable by the computer 1000 and includes, for example, RAM (Random Access Memory), ROM (Read Only Memory), etc. The storage device 1003 is a computer-readable storage medium and may include, for example, an HDD (Hard Disk Drive), an SSD (Solid State Drive), various optical disks, and magneto-optical disks.

[0070] The communication device 1004 includes one or more hardware components (transmission / reception devices) for communicating with other devices via a wireless or wired network. In this embodiment, the communication device 1004 includes, for example, a plurality of antennas, a wireless circuit, and a communication processor that executes baseband processing and communication control processing, etc.

[0071] The input device 1005 is an input device (e.g., keyboard, mouse, microphone, switch, button, sensor, etc.) that receives external input. The output device 1006 is an output device (e.g., display, speaker, LED lamp, etc.) that performs external output. Note that the input device 1005 and the output device 1006 may have an integrated configuration (e.g., an input / output device such as a touch panel display).

[0072] The bus B is commonly connected to each of the above components and transmits, for example, address signals, data signals, and various control signals, etc. Note that the processor 1001 is not limited to a CPU and may be, for example, a DSP (Digital Signal Processor), a PLD (Programmable Logic Device), or an FPGA (Field Programmable Gate Array), etc.

[0073] (Supplementary Note) Note that the base station device 10 and the terminal device 20 in this embodiment are not limited to being realized by dedicated devices and may be realized by a general-purpose computer. In that case, a program for realizing this function may be recorded on a computer-readable recording medium, and the program recorded on this recording medium may be read into a computer system and executed to realize it. Here, the "computer system" is assumed to include hardware such as an OS and peripheral devices.

[0074] In addition, the "computer-readable recording medium" includes various storage devices such as flexible disks, magneto-optical disks, ROMs, portable media such as CD-ROMs, and hard disks built into computer systems. Furthermore, the "computer-readable recording medium" also includes those that dynamically hold a program for a short time, such as a communication line when transmitting a program via a network such as the Internet or a communication line such as a telephone line, and those that hold a program for a certain period of time, such as volatile memory inside a computer system serving as a server or a client in that case.

[0075] Also, the above program may be for realizing a part of the functions described above, and may further be realized in combination with a program already recorded in the computer system for the functions described above, or may be realized using hardware such as a PLD (Programmable Logic Device) or an FPGA (Field Programmable Gate Array).

[0076] <Effects of the Embodiment> According to this embodiment, it is possible to improve the transmission efficiency of terminal cooperative MIMO communication in which a plurality of terminal devices 20 cooperate to perform MIMO communication.

[0077] <Summary of the Embodiment> This specification discloses at least the wireless communication methods and wireless communication systems of the following respective items. (Item 1) A wireless communication system including a base station device and a plurality of terminal devices, wherein the base station device is configured to collect terminal information including information indicating a cooperation state of terminal cooperative MIMO communication from the terminal device, Based on the terminal information, data is transmitted in the terminal cooperative MIMO communication to the terminal device for which the number of cooperative terminals in the terminal cooperative MIMO communication is equal to or more than a predetermined number, and data is transmitted in the MU-MIMO communication to the terminal device for which the number of cooperative terminals is less than the predetermined number. A radio communication unit configured as such. A radio communication system having the same. (Item 2) Based on the terminal information collected from the terminal device that is the destination of the communication, the communication control unit is configured to dynamically control whether to transmit data in the terminal cooperative MIMO communication or in the MU-MIMO communication to the destination terminal device. The radio communication system according to Item 1. (Item 3) The communication control unit When transmitting data in the terminal cooperative MIMO communication to the terminal device that is the destination of the communication, Based on the terminal information collected from the destination terminal device and other terminal devices that can cooperate with the destination terminal device, among the other terminal devices, a terminal device that relays the radio signal of the terminal cooperative MIMO communication to the destination terminal device is determined. The radio communication system according to Item 2. (Item 4) Among the other terminal devices, the communication control unit determines, as the terminal device that relays the radio signal to the destination terminal device, a terminal device with a smaller number of cooperative terminals. The radio communication system according to Item 3. (Item 5) The terminal information collected from the destination terminal device includes propagation path information between the destination terminal device and other terminal devices. When there are a plurality of the other terminal devices with the same number of cooperative terminals, the communication control unit determines, as the terminal device that relays the radio signal to the destination terminal device, a terminal device with higher radio quality of the radio link for relay communication that relays the radio signal to the destination terminal device. The radio communication system according to Item 4. (Item 6) The terminal cooperative MIMO communication The base station apparatus transmits the wireless signal including data to be transmitted to the destination terminal apparatus and control information to another terminal apparatus that relays the data to the destination terminal apparatus. The other terminal apparatus relays the received wireless signal to the destination terminal apparatus via a wireless link for relaying according to the control information of the received wireless signal. The destination terminal apparatus receives the data by using the wireless signal received from the base station apparatus and the wireless signal received via the wireless link for relaying. The wireless communication system according to any one of items 3 to 5. (Item 7) A base station apparatus that performs wireless communication with a plurality of terminal apparatuses, a terminal information collection unit configured to collect terminal information including information indicating a cooperation state of terminal cooperation MIMO communication from the terminal apparatuses; a wireless communication unit configured to transmit data by terminal cooperation MIMO communication to the terminal apparatuses having a number of cooperating terminals in the terminal cooperation MIMO communication equal to or greater than a predetermined number based on the terminal information, and to transmit data by MU-MIMO communication to the terminal apparatuses having a number of cooperating terminals less than the predetermined number; A base station apparatus having the above. (Item 8) In a wireless communication system including a base station apparatus and a plurality of terminal apparatuses, the base station apparatus performs a process of collecting terminal information including information indicating a cooperation state of terminal cooperation MIMO communication from the terminal apparatuses, and performs a process of transmitting data by terminal cooperation MIMO communication to the terminal apparatuses having a number of cooperating terminals in the terminal cooperation MIMO communication equal to or greater than a predetermined number based on the terminal information, and transmitting data by MU-MIMO communication to the terminal apparatuses having a number of cooperating terminals less than the predetermined number. A wireless communication method for executing the above.

[0078] As described above, although the present embodiment has been described, the present invention is not limited to such a specific embodiment, and various modifications and changes are possible within the scope of the gist of the present invention described in the claims.

Description of Symbols

[0079] 1 Wireless communication system 10 Base station device 20, 20-1 to 20-6 Terminal devices 201 Wireless communication section 202 Terminal information collection section 203 Communication control section 212 Inter-terminal cooperation section 1000 Computer

Claims

1. A wireless communication system including a base station device and a plurality of terminal devices, wherein the base station device, is configured with a terminal information collection unit for collecting terminal information including information indicating a cooperation state of terminal cooperation MIMO communication from the terminal device, based on the terminal information, for the terminal devices with the number of cooperating terminals in the terminal cooperation MIMO communication being equal to or more than a predetermined number, data is transmitted in the terminal cooperation MIMO communication, and for the terminal devices with the number of cooperating terminals being less than the predetermined number, data is transmitted in MU-MIMO communication, a wireless communication unit configured as such, A wireless communication system having the above.

2. The wireless communication system according to claim 1, further comprising a communication control unit configured to dynamically control whether to transmit data to the destination terminal device in the terminal cooperation MIMO communication or to transmit data in the MU-MIMO communication based on the terminal information collected from the destination terminal device of the communication.

3. The communication control unit, when transmitting data to the destination terminal device in the terminal cooperation MIMO communication, based on the terminal information collected from the destination terminal device and other terminal devices capable of cooperating with the destination terminal device, among the other terminal devices, determines a terminal device that relays a wireless signal of the terminal cooperation MIMO communication to the destination terminal device. The wireless communication system according to claim 2.

4. The wireless communication system according to claim 3, wherein the communication control unit determines, among the other terminal devices, a terminal device with a smaller number of cooperating terminals as the terminal device that relays the wireless signal to the destination terminal device.

5. The terminal information collected from the destination terminal device includes propagation path information between the destination terminal device and other terminal devices, the communication control unit, when there are a plurality of the other terminal devices with the same number of cooperating terminals, determines, as the terminal device that relays the wireless signal to the destination terminal device, a terminal device with a higher wireless quality of the wireless link for relay communication that relays the wireless signal to the destination terminal device.

6. The terminal cooperation MIMO communication, the base station device transmits the wireless signal including data to be transmitted to the destination terminal device and control information to other terminal devices that relay the data to the destination terminal device, the other terminal devices relay the received wireless signal to the destination terminal device via a wireless link for relay communication according to the control information of the received wireless signal. The destination terminal device receives the data by using the radio signal received from the base station device and the radio signal received through the radio link for relay communication. The wireless communication system according to any one of claims 3 to 5.

7. A base station device that performs wireless communication with a plurality of terminal devices, a terminal information collection unit configured to collect terminal information including information indicating a cooperation state of terminal cooperation MIMO communication from the terminal device; a wireless communication unit configured to transmit data by the terminal cooperation MIMO communication to the terminal device having a number of cooperating terminals in the terminal cooperation MIMO communication of a predetermined number or more based on the terminal information, and to transmit data by MU-MIMO communication to a terminal device having a number of cooperating terminals less than the predetermined number; A base station device having the above.

8. In a wireless communication system including a base station device and a plurality of terminal devices, the base station device performs a process of collecting terminal information including information indicating a cooperation state of terminal cooperation MIMO communication from the terminal device; performs a process of transmitting data by the terminal cooperation MIMO communication to the terminal device having a number of cooperating terminals in the terminal cooperation MIMO communication of a predetermined number or more based on the terminal information, and transmitting data by MU-MIMO communication to a terminal device having a number of cooperating terminals less than the predetermined number; A wireless communication method for executing the above.

Images