WO2019087240A1

WO2019087240A1 - Terminal apparatus, base station apparatus, communication method, and wireless communication system

Info

Publication number: WO2019087240A1
Application number: PCT/JP2017/039107
Authority: WO
Inventors: 松原俊太朗; 赤澤公久; 大出高義
Original assignee: 富士通株式会社
Priority date: 2017-10-30
Filing date: 2017-10-30
Publication date: 2019-05-09

Abstract

A terminal apparatus, in a wireless communication system including the terminal apparatus and a plurality of base station apparatuses wirelessly communicating with the terminal apparatus, comprises: a control unit that wirelessly connects to the plurality of base station apparatuses and that controls the wireless connection; a reception unit that receives data packets cooperatively transmitted from the plurality of base station apparatuses; and a transmission unit that, upon reception of at least one of the cooperatively transmitted data packets without errors, transmits a positive response, indicating that the data packet has been successfully received without errors, to the base station apparatus that is the transmission source of the data packet and to a plurality of base station apparatuses performing the cooperative transmission.

Description

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

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

In wireless communication, Multi Connectivity communication (hereinafter sometimes referred to as MC communication) in which a plurality of base station apparatuses cooperate to construct a communication path of data packets is being studied. In a communication system to which MC communication is applied, for example, packet replication may be performed in which packets including the same data are simultaneously transmitted from a plurality of base station apparatuses. In MC communication that performs packet replication, the terminal device can acquire data by receiving any one of the plurality of transmitted packets, so throughput and reliability are improved.

However, in MC communication that performs packet duplication, when the terminal device can receive the packet arriving first without error, it is not necessary to receive the packet transmitted from another base station device that arrives later. Therefore, using radio resources for packet transmission in another base station apparatus may not result in efficient use of radio resources.

The base station apparatus may retransmit a packet when the terminal apparatus can not receive the transmitted packet without error. However, since packet retransmission is performed for each base station apparatus, packet retransmission may be performed even when a terminal apparatus receives a packet transmitted by another base station apparatus without error. The retransmitted packet is a packet already received by the terminal device, and a packet not used by the terminal device will be transmitted using a radio resource, which may not be efficient use of the radio resource.

Therefore, one aspect of the disclosure provides a terminal apparatus, a base station apparatus, a communication method, and a wireless communication system that efficiently use a wireless resource in a communication system to which MC communication is applied.

A terminal unit and a terminal unit in a wireless communication system having a plurality of base station apparatuses wirelessly communicating with the terminal unit, the control unit wirelessly connecting to the plurality of base station apparatuses and controlling the wireless connection; When at least one data packet of the cooperatively transmitted data packet is received without error, the data packet can be received without an error. And a transmitting unit that transmits an acknowledgment indicating that the transmission has been made to the base station apparatus that is the transmission source of the data packet, and the plurality of base station apparatuses that perform cooperative transmission.

According to an embodiment of the present disclosure, radio resources can be efficiently used in a communication system to which MC communication is applied.

FIG. 1 is a diagram showing an example of the configuration of a wireless communication system 10. FIG. 2 is a diagram illustrating an example of a sequence of MC communication involving packet duplication. FIG. 3 is a diagram illustrating an example of a sequence of MC communication involving packet duplication. FIG. 4 is a view showing a configuration example of the terminal device 100. FIG. 5 is a diagram showing a configuration example of the base station apparatus 200. FIG. 6 is a diagram illustrating an example of a sequence when MC communication is started. FIG. 7 is a diagram illustrating an example of a sequence in the case where the terminal device 100 can not receive the MC communication packet from all the MC communication base stations without error. FIG. 8 is a diagram showing an example of a processing flowchart of the MC communication packet reception processing S106. FIG. 9 is a diagram showing an example of a processing flowchart of the reception success process S107. FIG. 10 is a diagram showing an example of a processing flowchart of the reception failure processing S108. FIG. 11 is a diagram showing an example of the MC communication packet reception state management table 123. As shown in FIG. FIG. 12 is a diagram showing an example of a sequence when the terminal device 100 receives a subsequent MC communication packet without error. FIG. 13 is a diagram showing an example of the MC communication packet reception state management table 123. As shown in FIG. FIG. 14 is a diagram illustrating an example of a sequence in the case where the terminal device 100 receives an initial MC communication packet without error. FIG. 15 is a diagram showing an example of the MC communication packet reception state management table 123. As shown in FIG. FIG. 16 is a diagram showing an example of a processing flowchart of reception waiting timer monitoring processing S500. FIG. 17 is a diagram illustrating an example of a sequence when the terminal device 100 can not receive an MC communication packet without error. FIG. 18 is a diagram showing an example of a processing flowchart of MC communication packet reception processing S600. FIG. 19 is a diagram illustrating an example of a sequence in the case where the terminal device receives an MC communication packet without error. FIG. 20 is a diagram illustrating an example of a sequence of MC communication.

<Configuration Example of Communication System>
FIG. 1 is a diagram showing an example of the configuration of a wireless communication system 10. The wireless communication system 10 includes a terminal device 100, base station devices 200-1 to 3 (hereinafter sometimes referred to as a base station device 200), a control device 300, and a network 400.

The wireless communication system 10 is, for example, a wireless communication network such as LTE (Long Term Evolution). The wireless communication system 10 is a communication system that provides communication to the terminal device 100, for example, because the terminal device 100 receives the service of the external network 400 such as the Internet. The terminal device 100 implements communication by transmitting and receiving data with the external network 400 via the base station device 200 and the control device 300.

The terminal device 100 is a device that performs wireless connection with the base station device 200 and performs communication by transmitting and receiving packets with the base station device 200, and is, for example, a mobile communication device such as a smartphone. Although one terminal device 100 is shown in FIG. 1, a plurality of terminal devices 100 may exist.

The base station apparatus 200 wirelessly connects to the terminal apparatus 100 and transmits / receives packets, for example, eNodeB (evolved Node B) or 5G (5th generation mobile) in a communication system based on LTE (Long Term Evolution). Communication system) (next “generation Node B”).

The control device 300 is a device that manages movement and communication of the terminal device 100 subordinate to the base station device 200, and is, for example, a server machine such as MME (Mobility Management Entity).

In the radio communication system 10, the base station apparatus 200 may perform MC communication. The MC communication is, for example, communication in which a plurality of base station apparatuses 200 among the base station apparatuses 200 included in the wireless communication system 10 cooperate to transmit a packet (data packet) including data to the terminal apparatus 100.

MC communication may involve packet duplication. In the wireless communication system, a plurality of base station apparatuses 200 (for example, base station apparatuses 200-1 and 200-2) perform MC communication with packet replication to the terminal apparatus 100. In MC communication involving packet duplication, for example, the packet including the same data is transmitted from a plurality of base station apparatuses 200 (packet duplication) to improve the packet reception possibility in the terminal apparatus 100, and the terminal apparatus 100 Improve the possibility of acquiring data. Although two base station apparatuses 200 of base station apparatuses 200-1 and 200-2 perform MC communication in FIG. 1, three or more base station apparatuses 200 may perform MC communication.

Furthermore, MC communication may not involve packet duplication. In the wireless communication system, a plurality of base station apparatuses 200 (for example, base station apparatuses 200-1 and 200-2) perform MC communication without packet duplication with the terminal apparatus 100. In MC communication that does not perform packet replication, for example, by transmitting packets including different data from a plurality of base station apparatuses 200, many radio resources can be used simultaneously, and throughput for the terminal apparatus 100 is improved.

The MC communication is performed, for example, when the terminal device 100 moves to the area end of the communication area of the base station device 200 in communication. For example, the terminal device 100 in communication with the base station device 200-1 moves to the area end of the communication area A200-1 of the base station device 200-1 shown in FIG. Then, for example, the base station apparatus 200-1 detects that the terminal apparatus 100 has moved to the area end of the communication area, and can communicate with another base station apparatus 200 capable of communicating with the terminal apparatus 100 (in FIG. The device 200-2) is requested to perform MC communication. The base station device 200-2 transmits the data received from the base station device 200-1 to the terminal device 100 in response to the request to perform the MC communication. Hereinafter, the base station apparatus 200 (base station apparatus 200-1 in FIG. 1) that is the request source of MC communication is ANode (Anchor Node), and the base station apparatus 200 that is the request destination of MC communication (base station in FIG. The apparatus 200-2) may be referred to as an SNode (Splitting Node). Also, a plurality of base station apparatuses 200 (base station apparatuses 200-1 and 200-2 in FIG. 1) performing MC communication may be referred to as an MC communication base station.

<MC communication>
FIG. 2 is a diagram illustrating an example of a sequence of MC communication involving packet duplication. Hereinafter, the method of MC communication accompanied by packet duplication shown in FIG. 2 may be referred to as a basic method. Also, hereinafter, solid arrows in the sequence indicate wired communication, and dotted arrows indicate wireless communication.

In the basic scheme, when the base station device 200-1 (ANode) detects an MC communication start trigger, it transmits an MC communication start request for requesting the start of MC communication to the base station device 200-2 (SNode) ( S10).

When receiving the MC communication start request, the base station apparatus 200-2 transmits an MC communication start response to the base station apparatus 200-1 (S11). When receiving the MC communication start response, the base station apparatus 200-1 starts MC communication.

The base station apparatus 200 manages the packet to be transmitted by including the sequence number (SN: Sequence Number) in the packet. Packets transmitted by ANode and SNode are packets including the same data if the sequence numbers are the same.

Further, the base station apparatus 200-2, which is an SNode, receives (acquires) data to be transmitted from, for example, the base station apparatus 200-1, which is an ANode. The base station apparatus 200-2 may receive data included in one packet or may collectively receive data included in a plurality of packets. Also, for example, the base station apparatus 200-2, which is an SNode, may receive data from the base station apparatus 200-1, which is an A Node, before transmission of a packet, or may transmit data including a plurality of packets by the A Node. Data may be acquired by receiving the received MC communication start request.

The base station apparatus 200-1 transmits a packet including data to be transmitted to the terminal apparatus 100 to the terminal apparatus 100 in MC communication (S12). The sequence number of the packet to be transmitted is, for example, SN1.

When the terminal device 100 receives the packet without error (reception success) (S13), an acknowledgment (ACK: Acknowledgement) indicating that the packet of SN1 has been received without error (or with reception quality higher than a predetermined quality), The packet is transmitted to the transmission source base station apparatus 200-1 (S14).

Similarly, in MC communication, the base station apparatus 200-2 transmits a packet including data to be transmitted to the terminal apparatus 100 (for example, the same data as data included in a packet transmitted by the base station apparatus 200-1) to a terminal It transmits to the apparatus 100 (S15). The sequence number of the packet to be transmitted is, for example, SN1 like the packet transmitted by the base station device 200-1.

In MC communication, for example, when the data to be transmitted is the same, the sequence number is also the same. Thereby, the terminal device 100 can recognize that the data is the same by the sequence number without performing the data comparison. In the subsequent sequences, it is assumed that packets having the same sequence number have the same data included.

When the terminal device 100 successfully receives the packet without error (S16), the terminal device 100 transmits an ACK (SN1) indicating that the packet of SN1 has been received without error to the base station device 200-2 of the packet transmission source (S17) .

According to the sequence of FIG. 2, the terminal device 100 succeeds in acquiring data by receiving the packet S12 transmitted from the base station device 200-1. Therefore, the terminal device 100 does not need to receive the packet S15 transmitted by the base station device 200-2. Therefore, even if the packet S15 and the ACKS 17 are omitted in the sequence of FIG. 2, there may be a case where no problem occurs in data acquisition of the terminal device 100.

FIG. 3 is a diagram illustrating an example of a sequence of MC communication involving packet duplication. The method of MC communication shown in FIG. 3 is a basic method.

Steps S10 to S12 are the same as steps S10 to S12 in the sequence shown in FIG. The terminal device 100 fails to receive the packet S12 (S21). The case where reception of a packet fails includes, for example, a case where an error is included in the received packet (for example, a parity error or an authentication error) or a case where only a part of the pat can be received. If the terminal device 100 fails to receive the packet (S21), a negative acknowledgment (NACK: Negative Acknowledgment) indicating that the SN1 packet could not be received without error is sent to the base station device 200-1 of the packet transmission source. Send (S22). Hereinafter, the case where a packet can not be received without error may be referred to as reception failure.

On the other hand, the base station apparatus 200-2 transmits a packet to the terminal apparatus 100 in MC communication (S15). When the terminal device 100 successfully receives the packet without error (S16), the terminal device 100 transmits an ACK indicating that the packet of SN1 has been received without error to the base station device 200-2 of the packet transmission source (S17).

When receiving the NACK of SN1 (S22), the base station apparatus 200-1 retransmits the packet of SN1 (S23). When the terminal device 100 successfully receives the packet without error (S24), the terminal device 100 transmits an ACK indicating that the packet of SN1 has been received without error to the base station device 200-1 of the packet transmission source (S25).

According to the sequence of FIG. 3, the terminal device 100 succeeds in acquiring data by receiving the packet S15 transmitted from the base station device 200-2. Therefore, the terminal device 100 does not have to receive the packet S23 retransmitted by the base station device 200-1. Therefore, in the sequence of FIG. 3, even if the packet S23 and the ACKS 25 are omitted, data acquisition by the terminal device 100 succeeds.

First Embodiment
The first embodiment will be described.

<Configuration Example of Terminal Device>
FIG. 4 is a diagram showing an exemplary configuration of the terminal device 100. As shown in FIG. The terminal device 100 is, for example, a mobile communication terminal, and includes a central processing unit (CPU) 110, a storage 120, a memory 130, and an RF (radio frequency) circuit 150.

The storage 120 is an auxiliary storage device such as a flash memory, a hard disk drive (HDD), or a solid state drive (SSD) that stores programs and data. The storage 120 has an MC communication start notification receiving program 121, an MC communication packet receiving program 122, and an MC communication packet reception state management table 123.

The MC communication packet reception state management table 123 is a table for managing a packet received in MC communication. The MC communication packet reception state management table 123 manages, for example, an identifier of the base station apparatus 200 that performs MC communication. Then, the MC communication packet reception state management table 123 stores, for example, a packet in MC communication received for each base station apparatus 200. Furthermore, the MC communication packet reception state management table 123 stores the reception state of packets in MC communication. Details of the MC communication packet reception state management table 123 will be described later.

The memory 130 is an area for loading a program stored in the storage 120. The memory 130 is also used as an area for storing data by the program.

The RF circuit 150 is wirelessly connected to the base station apparatus 200 and is, for example, an apparatus that communicates with the network 400. The RF circuit 150 transmits and receives packets using the antenna 151 to realize communication with other devices.

The CPU 110 is a processor that loads a program stored in the storage 120 into the memory 130, executes the loaded program, and implements each process.

The CPU 110 constructs an acquisition unit by executing the MC communication start notification reception program 121, and performs an MC communication start notification reception process. The MC communication start notification reception process is a process of receiving an MC communication start notification from the base station apparatus 200 (for example, ANode). The terminal device 100 acquires information (for example, an identifier of the base station device 200) related to a base station device (MC communication base station) performing MC communication in the MC communication start notification reception process.

The CPU 110 executes the MC communication packet reception program 122 to construct a receiver and a transmitter, and performs an MC communication packet reception process. The MC communication packet reception process is a process of receiving a packet (hereinafter, may be referred to as an MC communication packet) transmitted by MC communication transmitted from the MC communication base station. In the MC communication packet reception process, the terminal device 100 manages the reception state of the MC communication packet, and transmits ACK or NACK to the MC communication base station according to the reception state to be managed.

The CPU 110 executes the communication control program 124 to construct a control unit and perform communication control processing. The communication control process is, for example, a process of wirelessly connecting to a plurality of base station apparatuses 200 and controlling a plurality of wireless connections.

<Example of Configuration of Base Station Device>
FIG. 5 is a diagram showing a configuration example of the base station apparatus 200. The base station apparatus 200 includes a CPU 210, a storage 220, a memory 230, NICs 240-1 to n, an RF circuit 250, and an antenna 251.

The storage 220 is an auxiliary storage device such as an HDD or an SSD that stores programs and data. The storage 220 stores an MC communication program 221, an SNode-side MC communication program 222, and a transmission data storage table 223.

The transmission data storage table 223 is a table for storing data to be transmitted to the terminal device 100. The transmission data storage table 223, for example, stores a sequence number and transmission data in association with each other. When receiving the ACK, the base station apparatus 200 deletes transmission data corresponding to the received ACK. The transmission data storage table 223 may be stored in the memory 230 or another storage device. The transmission data storage table 223 operates as, for example, a storage unit. The transmission data storage table 223 stores data transmitted by the base station 200 to the terminal 100 and part or all of data transmitted by the other MC communication base station to the terminal 100.

The memory 230 is an area for loading a program stored in the storage 220. The memory 230 is also used as an area for storing data in the program.

The NICs 240-1 to n are devices connected to the control device 300 and the network to perform communication. The NICs 240-1 to n may be connected to the control device 300 via hubs or switches. Also, the NICs 240-1 to n may be used for connection between the base station apparatuses 200.

The RF circuit 250 is a device that realizes transmission and reception of radio waves (packets) via the antenna 251. The RF circuit 250 wirelessly communicates with, for example, the terminal device 100 located in the cell (within the communication area) of the base station device 200 via wireless communication.

The CPU 210 executes the MC communication program 221 to construct a wireless control unit, a response receiving unit, and a coordinated transmission unit, and performs MC communication processing. The MC communication processing is processing in which the own base station apparatus becomes an ANode and performs MC communication with one or more SNodes. The base station apparatus 200 selects an SNode in MC communication processing, and notifies the selected SNode to perform MC communication. Also, in the MC communication process, the base station apparatus 200 includes information (for example, an identifier) related to the base station apparatus 200 that performs MC communication in the MC communication start notification, and transmits it to the terminal apparatus 100.

The CPU 210 executes the SNode-side MC communication program 222 to construct a response receiving unit, a cooperative transmission unit, and a data control unit, and performs SNode-side MC communication processing. The SNode-side MC communication process is a process in which the own base station apparatus becomes an SNode and performs MC communication in response to a request from the base station apparatus 200 which is an ANode. The base station apparatus 200 receives an MC communication start request from the ANode in SNode-side MC communication processing, and transmits a packet of MC communication to the terminal apparatus 100 according to an instruction from the base station apparatus 200 of ANode. When operating as an SNode, the base station apparatus 200 receives transmission data from the base station apparatus 200, which is an ANode, and stores the transmission data in the transmission data storage table 223.

<Process at start of MC communication>
In the first embodiment, at the start of MC communication, base station apparatus 200 transmits an MC communication start notification notifying terminal apparatus 100 to start MC communication. The terminal device 100 recognizes that the MC communication base station performs MC communication by receiving the MC communication start notification. In the first embodiment, the MC communication base station performs MC communication with packet duplication for transmitting a packet including the same data.

FIG. 6 is a diagram illustrating an example of a sequence when MC communication is started. In FIG. 6, the base station apparatus 200-1 is an ANode, and the base station apparatus 200-2 is an SNode.

When the base station device 200-1 detects an opportunity to start MC communication, it performs MC communication processing (S100). The base station apparatus 200-1 selects an SNode in MC communication processing S100, and transmits an MC communication start request to the base station apparatus 200-2 which is the selected SNode (S101). The MC communication start request is a message requesting the base station apparatus 200 to become an SNode in MC communication, and includes, for example, data that the SNode transmits to the terminal apparatus, information on transmission timing, and the like. The MC communication start request is, for example, an SGNB ADDITION REQUEST.

When receiving the MC communication start request, the base station apparatus 200-2 performs SNode-side MC communication processing (S102). The base station apparatus 200-2 detects the terminal apparatus 100 that is the transmission target of MC communication in SNode-side MC communication processing S102. Then, the base station apparatus 200-2 wirelessly connects with the terminal apparatus 100 in the SNode-side MC communication processing S102, and transmits an MC communication start response for accepting MC communication to the base station apparatus 200-1 (S103). ). The MC communication start response is, for example, SGNB ADDTION REQUEST ACK.

When receiving the MC communication start response, the base station apparatus 200-1 transmits an MC communication start notification to the terminal apparatus 100 (S104). The MC communication start notification is, for example, an identifier of the base station apparatus 200 (the base station apparatus 200-2 in the case of FIG. 6) which is an SNode, start timing and end timing of MC communication, and packets transmitted by MC communication. Contains information about the sequence number.

When the terminal device 100 receives the MC communication start notification, the terminal device 100 performs an MC communication start notification reception process (S105). The terminal device 100 stores the MC communication base station in MC communication start notification reception processing S105, and performs MC communication packet reception processing (S106).

<Process when receiving MC communication packet>
In the first embodiment, when the terminal device 100 receives an MC communication packet, the terminal device 100 manages the reception state of the MC communication packet. Then, the terminal device 100 transmits ACK or NACK to the MC communication base station according to the reception state of the MC communication packet. Hereinafter, the terminal device 100 will be described using a sequence for each pattern in which the MC communication packet is received without error (reception success) or reception failure.

<1. In the event of failure to receive MC communication packets from all MC communication base stations>
FIG. 7 is a diagram illustrating an example of a sequence in the case where the terminal device 100 fails to receive the MC communication packet from all the MC communication base stations.

The base station device 200-1 transmits the packet SN1 of sequence number 1 (hereinafter, the packet of sequence number x is expressed as packet SNx) to the terminal device 100 (S201). The terminal device 100 receives the packet SN1 in the MC communication packet reception process S106.

FIG. 8 is a diagram showing an example of a processing flowchart of the MC communication packet reception processing S106. The terminal device 100 waits to receive an MC communication packet (No in S106-1). When the terminal device 100 receives the MC communication packet (Yes in S106-1), the terminal device 100 checks whether the MC communication packet has been received without error (S106-2). Failure in reception of the MC communication packet includes, for example, when the reception power of the packet SN1 is lower than a threshold, or when the frame error rate of the packet SN1 is higher than the threshold.

When the terminal device 100 receives the MC communication packet without error (Yes in S106-2), the terminal device 100 performs reception success processing (S107). On the other hand, when the terminal device 100 fails to receive the MC communication packet (No in S106-2), the terminal device 100 performs a reception failure process (S108). Then, the terminal device 100 waits to receive the MC communication packet again (S106-1).

FIG. 9 is a diagram showing an example of a processing flowchart of the reception success process S107. The terminal device 100 confirms whether the packet (MC communication packet received without error) has been received (S107-1). For example, the terminal device 100 refers to the MC communication packet reception state management table 123, and when the reception state of the packet with the sequence number of the packet has been received, determines that the packet has been received.

When the terminal device 100 has not received the packet (No in S107-1), the terminal device 100 transmits an ACK to all MC communication base stations (S107-2). Then, the terminal device 100 changes the reception status of the packet of all the MC communication base stations in the MC communication packet reception status management table 123 to “received” (S107-3), and ends the processing.

On the other hand, when the terminal device 100 has received the packet (Yes in S107-1), the terminal device 100 ends the process. In this case, the terminal device 100 may discard the received packet. Also, in this case, the terminal device 100 may transmit an ACK indicating that the packet has been received, to the transmission source base station device 200 of the packet.

FIG. 10 is a diagram showing an example of a processing flowchart of the reception failure processing S108. The terminal device 100 confirms whether or not the packet (MC communication packet that failed to be received) has been received (S108-1). If the terminal device 100 has received the packet (Yes in S108-1), the process ends.

On the other hand, when the terminal device 100 has not received the packet (No in S108-1), the terminal device 100 checks whether the packet has failed to be received at least once (S108-2). If the terminal device 100 has not failed to receive the packet (No in S108-2), the terminal device 100 determines that it is the first failure to receive the packet, and the reception waiting timer corresponding to the received packet is It starts (S108-3). If the terminal device 100 fails to receive the packet (Yes in S108-2), the reception waiting timer corresponding to the packet is already activated, and thus does not activate the reception waiting timer. The terminal device 100 refers to the MC communication packet reception state management table 123, and when reception failure of the packet of the packet with the sequence number of the packet is present, determines that the reception of the packet has failed.

Then, the terminal device 100 confirms whether or not the packet has been received from all the MC communication base stations (S108-4). The terminal device 100 refers to the MC communication packet reception state management table 123, and when there is unreception in the reception state of the packet of the sequence number of the packet, the packet is not received from all MC communication base stations (It is determined that there is an MC communication packet of an MC communication base station which has not yet received and failed to receive).

When the terminal device 100 receives the packet from all the MC communication base stations (Yes in S10804), the terminal device 100 transmits a NACK indicating that the reception of the packet has failed to all the MC communication base stations (S108- 5).

When the terminal device 100 receives the packet without error, as shown in the process flowchart of FIG. 9, the terminal device 100 changes the reception status of the packet of all the MC communication base stations to “received” (S107-3 in FIG. 9). . That is, when the packet has not been received and the packet has been received from all the MC communication base stations, the packet transmitted from all the MC communication base stations including the MC communication base station received this time It means that it has failed to receive. Therefore, the terminal device 100 transmits NACK to all the MC communication base stations, and causes the MC communication base station to retransmit the packet.

Then, the terminal device 100 updates the reception status of the packet of all the MC communication base stations in the MC communication packet reception status management table 123 to unreceived (S108-6), and stops the reception waiting timer of the packet. (S108-7), and the process ends. The reception status of the packet of all MC communication base stations in the MC communication packet reception status management table 123 is updated to “not received”, for example, waiting for reception of retransmission of the packet from the MC communication base station It is for.

On the other hand, when the terminal device 100 has not received the packet from all the MC communication base stations (there is an unreceived MC communication base station) (Yes in S10804), the MC communication base of the transmission source of the packet The reception state of the station is updated to failure (S108-8), and the process is ended.

Returning to the sequence of FIG. 7, the terminal device 100 fails to receive the packet SN1 from the base station device 200-1 in the MC communication packet reception processing S106 (S202, No in S106-2 of FIG. 8), reception failure Process S108 is performed.

FIG. 11 is a diagram showing an example of the MC communication packet reception state management table 123. As shown in FIG. FIG. 11A is a diagram showing an example of the MC communication packet reception state management table 123 before the terminal device 100 receives the packet SN1 from the base station device 200-1 in the sequence of FIG. FIG. 11A shows that the MC communication base stations are the base station apparatuses 200-1 and 200-2. Further, the MC communication base station indicates that the reception status of the packets SN1 and SN2 of the base station apparatuses 200-1 and 200-2 is a non-reception state (no success or failure in reception).

The terminal device 100 confirms whether or not the packet SN1 has been received in the reception failure processing S108 (S108-1 in FIG. 10). The terminal device 100 refers to the MC communication packet reception state management table 123, and as shown in FIG. 11A, since the reception state of the packet SN1 of the base station devices 200-1 and 200-2 is not received, It is confirmed that the packet SN1 has not been received yet (No in S108-1 of FIG. 10). Then, the terminal device 100 refers to the MC communication packet reception state management table 123, and as shown in FIG. 11A, the reception state of the packet SN1 of the base station devices 200-1 and 200-2 does not fail. The packet SN1 is determined not to fail in reception (Yes in S108-2 in FIG. 10), and the reception waiting timer is activated (S108-3 in FIG. 10).

Then, the terminal device 100 confirms whether or not the packet SN1 has been received from all the MC communication base stations (S108-4 in FIG. 10). Since the terminal device 100 has not received the packet SN1 of the base station device 200-2 other than the base station device 200-1 that received the packet SN1 this time, the MC communication base that has not received the packet SN1 yet It is determined that the station exists (No in S108-4 in FIG. 10), and the reception status of the packet SN1 of the base station apparatus 200-1 in the MC communication packet reception status management table 123 is updated to failure (S108 in FIG. -8).

FIG. 11B is a diagram showing an example of the MC communication packet reception state management table 123 after the process S108-8 of the reception failure process S108. As shown in FIG. 11B, the reception state of the packet SN1 of the base station device 200-1 in the MC communication packet reception state management table 123 is changed from not receiving to failure.

The base station device 200-2 transmits the packet SN1 to the terminal device 100 (S203). The terminal device 100 fails to receive the packet SN1 (S204).

The terminal device 100 fails to receive the packet SN1 from the base station device 200-2 in the MC communication packet reception process S106 (S204, No in S106-2 in FIG. 8), and performs reception failure process S108.

The terminal device 100 confirms whether or not the packet SN1 has been received in the reception failure processing S108 (S108-1 in FIG. 10). The terminal device 100 refers to the MC communication packet reception state management table 123, and as shown in FIG. 11B, since the reception state of the packet SN1 of the base station device 200-1 is failure, the packet SN1 has already been received. (Yes in S108-1 in FIG. 10). Then, the terminal device 100 refers to the MC communication packet reception state management table 123, and as shown in FIG. 11B, the reception state of the packet SN1 of the base station device 200-1 is a failure, so the packet SN1 is It is determined that the reception has failed (Yes in S108-2 of FIG. 10).

Then, the terminal device 100 confirms whether or not the packet SN1 has been received from all the MC communication base stations (S108-4 in FIG. 10). In the terminal device 100, the reception status of the packet SN1 of the base station device 200-1 other than the base station device 200-2 that received the packet SN1 this time is failure, and there is no other unreceived base station device 200. Therefore, it is determined that there is no MC communication base station that has not received the packet SN1 (Yes in S108-4 in FIG. 10). Then, the terminal device 100 transmits NACK (SN1) which is NACK for the packet SN1 to the base station devices 200-1 and 200-2 which are all MC communication base stations (S205, S206, S108-5 in FIG. 10). ). Then, the terminal device 100 updates the reception status of the packet SN1 of all MC communication base stations (base station devices 200-1 and 200-2) in the MC communication packet reception status management table 123 to unreceived (see FIG. The step S108-6 of 10) stops the reception waiting timer (S108-7 in FIG. 10).

FIG. 11C is a diagram showing an example of the MC communication packet reception state management table 123 after the process S108-6 of the reception failure process S108. As shown in FIG. 11C, the reception status of the packet SN1 of the base station apparatuses 200-1 and 200-2 in the MC communication packet reception status management table 123 is updated to unreceived.

When receiving the NACK, the base station apparatuses 200-1 and 200-2 retransmit the packet SN1 corresponding to the NACK to the terminal apparatus 100 (S207, S208).

In the first embodiment, the terminal device 100 does not transmit NACK until it fails to receive packets transmitted from all MC communication base stations. Even if the terminal device 100 fails to receive an MC communication packet from a certain base station device, the terminal device 100 can obtain data by receiving an MC communication packet including the same data from another base station device without error. it can. Therefore, when there is a possibility that data can be acquired from another base station apparatus, unnecessary retransmission processing can be suppressed by not transmitting NACK.

<2. When receiving a later MC communication packet without error>
FIG. 12 is a diagram illustrating an example of a sequence in the case where the terminal device 100 receives a subsequent MC communication packet without error. Steps S201 to S203 are the same as steps S201 to S203 shown in the sequence of FIG.

FIG. 13 is a diagram showing an example of the MC communication packet reception state management table 123. As shown in FIG. FIG. 13A is a diagram showing an example of the MC communication packet reception state management table 123 before the terminal device 100 receives the packet SN1 from the base station device 200-1 in the sequence of FIG. FIG. 13B is a diagram showing an example of the MC communication packet reception state management table 123 after the process S108-8 of the reception failure process S108. As shown in FIG. 13B, the reception state of the packet SN1 of the base station device 200-1 in the MC communication packet reception state management table 123 is changed from not receiving to failure.

The terminal device 100 receives the packet SN1 from the base station device 200-2 without error in the MC communication packet reception processing S106 (S300, Yes in S106-2 of FIG. 8), and performs reception success processing S107.

The terminal device 100 confirms whether or not the packet SN1 has been received in the reception success process S107 (S107-1 in FIG. 9). The terminal device 100 refers to the MC communication packet reception state management table 123, and as shown in FIG. 13B, the reception state of the packet SN1 of the base station device 200-1 is not yet received (failure). It is confirmed that the packet SN1 has not been received yet (No in S107-1 of FIG. 9). Then, the terminal device 100 transmits an ACK (SN1) indicating that the packet SN1 has been received without error to all of the MC communication base stations (base station devices 200-1 and 200-2) (S107 in FIG. 9). 2).

Then, the terminal device 100 updates the reception status of the packet SN1 of all the MC communication base stations (base station devices 200-1 and 200-2) in the MC communication packet reception status management table 123 to "received" (Fig. S107-3 of 9).

FIG. 13C is a diagram showing an example of the MC communication packet reception state management table 123 after the process S107-3 of the reception success process S107. As shown in FIG. 13C, the reception status of the packet SN1 of the base station apparatuses 200-1 and 200-2 in the MC communication packet reception status management table 123 is updated to "received".

In the first embodiment, the terminal device 100 transmits an ACK to all the MC communication base stations if it receives the subsequent MC communication packet without error even if the preceding reception of the MC communication packet fails. As a result, since retransmission of the base station apparatus 200 by transmitting NACK is not performed, it is possible to suppress the use of radio resources by retransmission.

<3. In the case of receiving the initial MC communication packet without error>
FIG. 14 is a diagram illustrating an example of a sequence in the case where the terminal device 100 receives an initial MC communication packet without error.

The base station device 200-1 transmits the packet SN1 to the terminal device 100 (S201). The terminal device 100 receives the packet SN1 from the base station device 200-1 without error in the MC communication packet reception processing S106 (S400, Yes in S106-2 of FIG. 8), and performs reception success processing S107.

FIG. 15 is a diagram showing an example of the MC communication packet reception state management table 123. As shown in FIG. FIG. 15A is a diagram showing an example of the MC communication packet reception state management table 123 before the terminal device 100 receives the packet SN1 from the base station device 200-1 in the sequence of FIG.

The terminal device 100 confirms whether or not the packet SN1 has been received in the reception success process S107 (S107-1 in FIG. 9). The terminal device 100 refers to the MC communication packet reception state management table 123, and as shown in FIG. 15A, the reception state of the packet SN1 of the base station devices 200-1 and 200-2 has not been received, It is determined that the packet SN1 has not been received (No in S107-1 of FIG. 9).

Then, the terminal device 100 transmits an ACK (SN1) indicating that the packet SN1 has been received without error to all of the MC communication base stations (base station devices 200-1 and 200-2) (S402, S203, FIG. 9 of S107-2). The terminal device 100 updates the reception status of the packet SN1 of all MC communication base stations (base station apparatuses 200-1 and 200-2) in the MC communication packet reception status management table 123 to "received" (FIG. 9) S107-3).

FIG. 15B is a diagram showing an example of the MC communication packet reception state management table 123 after the process S107-3 of the reception success process S107. As shown in FIG. 15B, the reception status of the packet SN1 of the base station apparatuses 200-1 and 200-2 in the MC communication packet reception status management table 123 is updated to "received".

Then, the terminal device 100 receives the packet SN1 from the base station device 200-2 in the MC communication packet reception process S106 (S403, Yes in S106-1 of FIG. 8). The terminal device 100 performs the reception success process S107 when receiving without error (Yes in S106-2 of FIG. 8), and performs the reception failure process S108 when failing in reception (No in S106-2 of FIG. 8). Then, the terminal device 100 has already received the packet SN1 as shown in FIG. 15 (B) in any of the reception success process S107 and the reception failure process S108 (Yes in S107-1 of FIG. 9, Alternatively, the process ends without transmitting the ACK or NACK or updating the MC communication packet reception state management table 123 in S108-1 of FIG. 10).

In the first embodiment, when the terminal device 100 succeeds in receiving the packet transmitted from the preceding MC communication base station, all of the terminal communication devices 100 do not receive the MC communication packet of the subsequent MC communication base station. Send an ACK to the MC communication base station. This makes it possible to suppress the retransmission process regardless of the success or failure of the reception of the MC communication packet of the subsequent MC communication base station.

<MC communication packet reception wait timer>
Failure to receive the MC communication packet in the first embodiment also includes timeout of a reception waiting timer. FIG. 16 is a diagram showing an example of a processing flowchart of reception waiting timer monitoring processing S500. The terminal device 100 executes a reception waiting timer monitoring process S500 in parallel with the MC communication packet reception process S106. The timer value (predetermined time) of the reception waiting timer is stored, for example, in the internal memory of the terminal device 100.

The terminal device 100 monitors the reception waiting timer until the reception waiting timer times out (No in S500-1). When the reception waiting timer times out (Yes in S500-1), the terminal device 100 transmits a NACK of a packet corresponding to the reception waiting timer that has timed out to all MC communication base stations (S500-2). Then, the terminal device 100 updates the reception status of the packet of all the MC communication base stations in the MC communication packet reception status management table 123 to “not received” (S500-3).

In the first embodiment, by activating and monitoring the reception waiting timer, NACK can be transmitted even when the MC communication packet does not reach the terminal device 100.

In the first embodiment, when the terminal device 100 receives at least one packet without error, it transmits an ACK to all MC communication base stations. As a result, retransmission from another base station apparatus can be suppressed, and radio resources can be efficiently used. In addition, even if the terminal device 100 fails to receive a packet in advance, it can suppress retransmission by NACK by not waiting for a NACK to be transmitted immediately and waiting for a packet from another base station device 200.

Second Embodiment
Next, a second embodiment will be described. In the second embodiment, in the second embodiment, the MC communication base station performs MC communication without packet duplication in which packets including different data are transmitted. Hereinafter, the case where the terminal device 100 fails to receive the MC communication packet and the case where the terminal device 100 receives the MC communication packet without error will be described.

<1. If reception of MC communication packet fails>
FIG. 17 is a diagram illustrating an example of a sequence in the case where the terminal device 100 fails to receive the MC communication packet. In the sequence of FIG. 17, it is assumed that base station apparatus 200-1 and base station apparatus 200-2 transmit packets of different sequence numbers. For example, the base station apparatus 200-1 transmits the packet SN1, the base station apparatus 200-2 transmits the packet SN2, and in the sequence of FIG. 17, the sequence in which the base station apparatus 200-2 transmits the packet SN2 I omit it.

The base station device 200-1 transmits the packet SN1 to the terminal device 100 (S601). The terminal device 100 receives the packet SN1 in the MC communication packet reception process S600.

FIG. 18 is a diagram showing an example of a processing flowchart of MC communication packet reception processing S600. The terminal device 100 waits to receive an MC communication packet (No in S600-1). When receiving the MC communication packet (Yes in S600-1), the terminal device 100 confirms whether the MC communication packet has been received without error (S600-2).

When the terminal device 100 receives the MC communication packet without error (Yes in S600-2), the terminal device 100 transmits an ACK to all MC communication base stations (S600-3). On the other hand, when the terminal device 100 fails to receive the MC communication packet (No in S600-2), the terminal device 100 transmits NACK to all MC communication base stations (S600-4). Then, the terminal device 100 waits to receive the MC communication packet again (S600-1).

Returning to the sequence of FIG. 17, the terminal device 100 fails to receive the packet SN1 from the base station device 200-1 in the MC communication packet reception process S600 (S602, No in S600-2 of FIG. 18), A NACK is transmitted to the MC communication base stations (base station apparatuses 200-1 and 200-2) (S600-4, S603, and S604 in FIG. 18).

When receiving the NACK of the packet SN1, the base station device 200-1 retransmits the packet SN1 (S606).

When receiving the NAC of the packet SN1, the base station apparatus 200-2 transmits (retransmits) the packet SN1 to the terminal apparatus 100 (S605).

The base station apparatuses 200-1 and 200-2 in the second embodiment hold data not transmitted by the own apparatus for retransmission. When the base station apparatus 200 receives a NACK of a packet transmitted by another MC communication base station, the base station apparatus 200 transmits the packet to the terminal apparatus although it is not a NACK for the packet transmitted by the own apparatus. Thereby, when the terminal device 100 fails to receive the packet, the packet is retransmitted from the plurality of base station devices 200, and the probability of being able to receive the packet is increased.

<2. When receiving MC communication packet without error>
FIG. 19 is a diagram illustrating an example of a sequence in the case where the terminal device receives the MC communication packet without error.

The base station device 200-1 transmits the packet SN1 to the terminal device 100 (S601). The terminal device 100 receives the packet SN1 from the base station device 200-1 without error in the MC communication packet reception process S600 (S700, Yes in S600-2 of FIG. 18), and all MC communication base stations (base stations The ACK is transmitted to the devices 200-1 and 200-2) (S701, S702, S600-3 in FIG. 18).

When the base station devices 200-1 and 2 receive the ACK of the packet SN1, the base station devices 200-1 and 2 discard the data of the packet SN1 (delete from the memory) (S703, S704).

In the second embodiment, the terminal device 100 transmits an ACK to all MC communication base stations. As a result, the base station apparatus 200 receives an ACK for the packet transmitted by the other base station apparatus 200, discards the data of the packet held for retransmission, thereby lengthening the data for retransmission. Memory capacity can be suppressed without storing in time memory.

Third Embodiment
Next, a third embodiment will be described. In the second embodiment, the MC communication base station includes a data transmission base station (first base station apparatus) and a data retransmission base station (second base station apparatus).

<MC communication>
FIG. 20 is a diagram illustrating an example of a sequence of MC communication. In FIG. 20, with respect to the terminal device 100 to which MC communication is applied, the base station device 200-1 is a data transmission base station, and the base station device 200-2 is a retransmission base station. The data transmission base station performs initial transmission and retransmission of data to the terminal device 100. On the other hand, the retransmission base station does not perform initial transmission of data to the terminal device 100, but only performs retransmission.

The base station device 200-1 transmits the packet SN1 to the terminal device 100 (S800). The terminal device 100 receives the packet SN1 without error (S801), and transmits an ACK to the MC communication base station (base station devices 200-1 and 200-2) (S802, S803).

The base station device 200-1 transmits the packet SNn to the terminal device 100 (S804). The terminal device 100 fails to receive the packet SNn (S805), and transmits NACK to the MC communication base station (base station devices 200-1 and 200-2) (S806, S807).

When receiving the NACK corresponding to the packet SNn, the base station apparatus 200-1 retransmits the packet SNn (S809). On the other hand, when receiving the NACK corresponding to the packet SNn, the base station apparatus 200-1 transmits the packet SNn to the terminal apparatus even though it is not the NACK corresponding to the packet transmitted by the own base station apparatus (S808). .

In the third embodiment, for example, a base station apparatus capable of low delay transfer is a data transmission base station, and a base station apparatus capable of highly reliable transfer but not low delay than the data transmission base station is retransmitted. It may be a base station. The retransmission base station includes, for example, an eNodeB in a communication system compliant with LTE.

[Other Embodiments]
Next, other embodiments will be described.

<1. Use of Grant-Free Radio Resource>
The terminal device 100 may use, for example, Grant-Free radio resources when transmitting ACKs and NACKs. The Grant-Free radio resource is a radio resource that can be used by the terminal device 100 without allocating a radio resource to the base station device 200. By using the Grant-Free radio resource, the procedure of radio resource allocation with the base station apparatus 200 can be omitted, and ACK and NACK can be transmitted in a short time.

<2. Use of Communication Message between Base Stations>
The radio communication system 10 may substitute for the process in which the terminal device 100 transmits an ACK or NACK to the MC communication base station, and may use a communication message between the base station devices (DDDS: Downlink Data Delivery Status). When using the DDDS, the base station apparatus 200 that has received ACK or NACK transmits DDDS including transmission success (ACK) or transmission failure (NACK) to another MC communication base station. The other MC communication base stations that have received the DDDS perform the same processing as when receiving an ACK or NACK.

Also, the radio communication system 10 may properly use the process in which the terminal device 100 transmits an ACK or NACK to the MC communication base station and the process in which the DDDS is used. For example, in a wireless communication system in which the number of message transmissions between base station apparatuses is large, even if the terminal apparatus 100 transmits an ACK or NACK to the MC communication base station in order to suppress the communication amount of communication between base station apparatuses. Good. On the other hand, in a wireless communication system in which a shortage of wireless resources occurs, a process using DDDS may be performed.

<3. Transmission timing coordination at retransmission>
In the radio communication system 10, a plurality of MC communication base stations may retransmit a packet including the same data. In this case, for example, the ANode may control the timing at which another SNode transmits a packet. For example, the ANode calculates the phase of each packet transmitted by each SNode so that the reception power of a plurality of identical data packets in the terminal device 100 becomes maximum, and controls the transmission timing of the SNode so as to obtain the calculated phase. It is also good. Also, in the initial transmission, the SNode may be controlled to transmit a packet at a timing different from the timing when the terminal device 100 fails in reception.

10: Wireless communication system 100: Terminal device 110: CPU
120: storage 121: MC communication start notification reception program 122: MC communication packet reception program 123: MC communication packet reception state management table 130: memory 150: RF circuit 151: antenna 200: base station apparatus 210: CPU
220: Storage 221: MC communication program 222: SNode side MC communication program 223: transmission data storage table 230: memory 250: RF circuit 251: antenna 300: control device 400: external network

Claims

A terminal device in a wireless communication system, comprising: a terminal device; and a plurality of base station devices wirelessly communicating with the terminal device,
A control unit that wirelessly connects to the plurality of base station apparatuses and controls the wireless connection;
A receiving unit that receives data packets cooperatively transmitted from the plurality of base station apparatuses;
When at least one data packet among the cooperatively transmitted data packets is received without error, an acknowledgment indicating that the data packet has been received without error is a base station apparatus of a transmission source of the data packet, A terminal apparatus comprising: a transmitter configured to transmit to the plurality of base station apparatuses performing cooperative transmission.
The coordinated transmission includes the plurality of coordinated transmission base stations transmitting data packets including the same data.
The terminal device according to claim 1.
The transmitter is configured to receive a negative acknowledgment indicating that the data packet could not be received without error when all the data packets transmitted by the plurality of cooperatively transmitting base stations can not be received without error. The terminal device according to claim 2, wherein transmission is performed to a transmission source base station device and the plurality of base station devices that perform cooperative transmission.
The case where all the data packets can not be received without error includes the case where the data packet can not be received without error for a predetermined time from when the data packet containing the error is first received. Terminal equipment.
The terminal device according to claim 4, wherein the transmitting unit does not transmit the negative acknowledgment until it detects that all the data packets transmitted by the plurality of cooperatively transmitting base stations can not be received without error.
The terminal apparatus according to claim 1, wherein the receiving unit further receives, from at least one base station apparatus of the plurality of base station apparatuses performing the coordinated transmission, information on the plurality of base station apparatuses performing the coordinated transmission.
The terminal apparatus according to claim 1, wherein the transmission unit transmits the acknowledgment using a radio resource which can be used without assignment of a radio resource from the base station apparatus to the terminal apparatus.
The terminal device according to claim 3, wherein the transmission unit transmits the negative acknowledgment using a radio resource which can be used without assignment of a radio resource from the base station device to the terminal device.
The cooperative transmission includes the plurality of cooperatively transmitting base stations transmitting data packets including different data, respectively.
The base station apparatus has a storage unit that stores data or data packets transmitted by the own base station apparatus, and data or data packets transmitted by the plurality of base station apparatuses other than the own base station apparatus that performs cooperative transmission. The terminal device according to Item 1.
The transmitting unit transmits the data packet with a negative acknowledgment indicating that the data packet could not be received without error when the plurality of base station devices performing cooperative transmission can not receive the data packet without error. It transmits to the original base station apparatus and the plurality of base station apparatuses that perform cooperative transmission other than the transmission source base station apparatus, and the cooperative transmission other than the transmission source base station apparatus and the transmission source base station apparatus The terminal apparatus according to claim 9, wherein the terminal apparatus transmits the data packet which can not be received without error to a plurality of base station apparatuses.
In the coordinated transmission, a second base station apparatus, which is a plurality of base station apparatuses that the first base station apparatus transmits a data packet to the terminal apparatus and the coordinated transmission other than the first base station apparatus, is the terminal apparatus Sending a data packet corresponding to the negative acknowledgment to the terminal device when receiving a negative acknowledgment indicating that the data packet transmitted by the first base station device could not be received without error from the terminal device;
The transmission unit transmits a negative acknowledgment corresponding to the data packet to the first and second base station apparatuses when the data packet transmitted by the first base station apparatus can not be received without error. Terminal device described.
The first base station apparatus includes gNodeB (next “generation Node B”) in the fifth generation mobile communication system,
The terminal device according to claim 11, wherein the second base station device includes an eNodeB (envolved Node B) in a communication system compliant with Long Term Evolution (LTE).
A base station device in a wireless communication system, comprising: a terminal device; and a plurality of base station devices wirelessly communicating with the terminal device,
A wireless control unit that wirelessly connects to the terminal device and controls the wireless connection;
A cooperative transmission unit that cooperates with the plurality of base station apparatuses and cooperatively transmits to the terminal apparatus;
When the terminal apparatus receives at least one data packet among the data packets transmitted by the plurality of base station apparatuses performing cooperative transmission without error, the base station apparatus of the transmission source of the data packet, and the transmission source A response receiving unit that transmits to the plurality of cooperatively transmitting base stations other than the base station, and receives an acknowledgment indicating that the data packet has been received without error;
And a data control unit that deletes data corresponding to the acknowledgment when the acknowledgment is received.
The coordinated transmission includes the plurality of coordinated transmission base stations transmitting data packets including the same data.
The base station apparatus according to claim 13.
The response receiving unit also transmits a plurality of base station apparatuses that perform cooperative transmission when the terminal apparatus can not receive all the data packets transmitted by the plurality of base station apparatuses that perform cooperative transmission without an error. Receiving a negative acknowledgment indicating that the data packet could not be received without error;
The base station apparatus according to claim 14, wherein the data control unit transmits a data packet corresponding to the negative response to the terminal apparatus when the negative response is received.
The base station apparatus according to claim 13, further comprising: transmitting, to the terminal apparatus, information on the plurality of base station apparatuses to perform cooperative transmission.
The coordinated transmission includes the plurality of coordinated transmission base stations transmitting data packets including different data,
And a storage unit configured to store data transmitted by the own base station apparatus and data transmitted by the plurality of base station apparatuses other than the own base station apparatus performing the coordinated transmission.
The response receiving unit also transmits a plurality of base station apparatuses that perform cooperative transmission when the terminal apparatus can not receive data packets transmitted by the plurality of base station apparatuses that perform cooperative transmission without error. Receiving a negative acknowledgment indicating that the data packet could not be received without error;
The base station apparatus according to claim 13, wherein the data control unit transmits a data packet corresponding to the negative response to the terminal apparatus when the negative response is received.
The plurality of base station apparatuses, wherein the response receiving unit performs the coordinated transmission when the terminal apparatus receives without error a data packet transmitted by a base station apparatus included in the plurality of base station apparatuses other than the own base station apparatus. Receiving an acknowledgment indicating that the data packet was successfully received, sent to
The base station apparatus according to claim 17, wherein the data control unit deletes data corresponding to the acknowledgment stored in the storage unit when the acknowledgment is received.
A communication method in the terminal device of a wireless communication system having a terminal device and a plurality of base station devices wirelessly connected to the terminal device,
Wirelessly connect to the plurality of base station apparatuses and control the wireless connection;
Receiving data packets cooperatively transmitted from the plurality of base station apparatuses;
When at least one data packet among the cooperatively transmitted data packets is received without error, an acknowledgment indicating that the data packet has been received without error is a base station apparatus of a transmission source of the data packet, A communication method for transmitting to the plurality of base station apparatuses for cooperative transmission.
A wireless communication system comprising: a terminal device; and a plurality of base station devices wirelessly communicating with the terminal device,
The terminal apparatus wirelessly connects to the plurality of base station apparatuses and controls the wireless connection;
The base station apparatus cooperates with the plurality of base station apparatuses to cooperatively transmit data packets to the terminal apparatus,
The terminal apparatus receives the data packet cooperatively transmitted from the plurality of base station apparatuses, and when at least one data packet of the cooperatively transmitted data packet is received without error, the data packet is not erroneously A wireless communication system for transmitting an acknowledgment indicating that reception was possible to a base station apparatus as a transmission source of the data packet and a plurality of base station apparatuses that perform cooperative transmission.