WO2017199360A1 - Communication system, terminal, base station, and communication method - Google Patents

Abstract

A terminal (130) can receive data addressed thereto by simultaneously using a wireless communication system adopting a first communication method and a wireless communication system adopting a second communication method different from the first communication method. A first base station (110) wirelessly transmits, using the first communication method, first data included in data to the terminal (130). A second base station (120) wirelessly transmits, using the second communication method, second data included in the data to the terminal (130); and in the case where a request for retransmission of the first data that has been wirelessly transmitted from the first base station (110) to the terminal (130) is received from the terminal (130), the second base station wirelessly transmits, using the second communication method, the first data to the terminal (130). In the case where reception of the first data that has been wirelessly transmitted from the first base station (110) has failed, the terminal (130) wirelessly transmits the request for retransmission of the first data to the second base station (120).

Description

Communication system, terminal, base station, and communication method

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

Conventionally, mobile communication systems such as the third generation mobile communication system (3G), LTE corresponding to the 3.9th generation mobile communication system, and LTE-Advanced corresponding to the fourth generation mobile communication system are known. In addition, studies on technologies relating to the fifth generation mobile communication system (5G) have also started. LTE is an abbreviation for Long Term Evolution. Further, a technique is known in which a wireless terminal performs communication simultaneously with a plurality of wireless base stations (see, for example, Patent Documents 1 to 4 below).

JP 2002-112347 A Japanese Patent Laying-Open No. 2015-185891 Japanese Patent Application Laid-Open No. 2014-120941 JP2015-173392A

When communicating with a plurality of different wireless communication systems, it is required to reduce delay by efficiently performing data retransmission.

In one aspect, an object of the present invention is to provide a communication system, a terminal, a base station, and a communication method that can shorten a delay in data retransmission due to a data error.

In order to solve the above-described problems and achieve the object, according to one aspect of the present invention, a terminal uses a wireless communication system based on a first communication system and a wireless communication system based on a second communication system different from the first communication system. And the first base station wirelessly transmits the first data included in the data to the terminal by the first communication method, and the second base station Wirelessly transmits the second data included in the data to the terminal by the second communication method, and receives a retransmission request from the terminal for the first data wirelessly transmitted from the first base station to the terminal. When the first data is wirelessly transmitted to the terminal by the second communication method, and the terminal fails to receive the first data wirelessly transmitted from the first base station, the first data 1 data There are the retransmission requesting communication system for wirelessly transmitting to the second base station, the terminal, the base station and a communication method are proposed.

According to another aspect of the present invention, the first base station can perform wireless communication using the first communication method, and the second base station can perform wireless communication using a second communication method different from the first communication method. Communication is possible, and the terminal can transmit data from its own station simultaneously using the wireless communication system according to the first communication method and the wireless communication system according to the second communication method, and is included in the data First data to be transmitted to the first base station by the first communication method, and second data included in the data is wirelessly transmitted to the second base station by the second communication method. A communication system, a terminal, which wirelessly transmits the first data to the second base station by the second communication method when a retransmission request for the first data wirelessly transmitted to the station is received from the first base station; Base station and Shin method is proposed.

According to one aspect of the present invention, it is possible to shorten the delay at the time of data retransmission due to a data error.

FIG. 1 is a diagram illustrating an example of a communication system according to the first embodiment. FIG. 2 is a diagram illustrating an example of retransmission of 4G packets in the communication system according to the first embodiment. FIG. 3 is a sequence diagram illustrating an example of processing in the communication system according to the first embodiment. FIG. 4 is a sequence diagram illustrating another example of processing in the communication system according to the first embodiment. FIG. 5 is a diagram of an example of the first base station according to the first embodiment. FIG. 6 is a diagram of an example of the second base station according to the first embodiment. FIG. 7 is a diagram of an example of a hardware configuration of the first base station and the second base station according to the first embodiment. FIG. 8 is a diagram of an example of the terminal according to the first embodiment. FIG. 9 is a diagram of an example of a hardware configuration of the terminal according to the first embodiment. FIG. 10 is a flowchart of an example of processing by the first base station according to the first embodiment. FIG. 11 is a flowchart of an example of processing by the second base station according to the first embodiment. FIG. 12 is a flowchart of an example of processing performed by the terminal according to the first embodiment. FIG. 13 is a diagram of an example of the second base station according to the second embodiment. FIG. 14 is a diagram of an example of a terminal according to the second embodiment. FIG. 15 is a sequence diagram of an example of processing in the communication system according to the third embodiment. FIG. 16 is a diagram of an example of the second base station according to the third embodiment. FIG. 17 is a diagram of an example of a terminal according to the third embodiment. FIG. 18 is a diagram illustrating an example of a hardware configuration of a terminal according to the third embodiment. FIG. 19 is a sequence diagram illustrating an example of processing in the communication system according to the fourth embodiment. FIG. 20 is a diagram of an example of the second base station according to the fourth embodiment. FIG. 21 is a diagram of an example of a terminal according to the fourth embodiment. FIG. 22 is a flowchart of an example of processing performed by the terminal according to the fourth embodiment. FIG. 23 is a sequence diagram of an example of processing in the communication system according to the fifth embodiment. FIG. 24 is a diagram of an example of the first base station according to the fifth embodiment. FIG. 25 is a diagram of an example of the second base station according to the fifth embodiment. FIG. 26 is a flowchart of an example of processing by the first base station according to the fifth embodiment. FIG. 27 is a flowchart of an example of processing by the second base station according to the fifth embodiment. FIG. 28 is a diagram of an example of a communication system according to the sixth embodiment. FIG. 29 is a diagram of an example of retransmission of 4G packets in the communication system according to the sixth embodiment. FIG. 30 is a sequence diagram illustrating an example of processing in the communication system according to the sixth embodiment. FIG. 31 is a diagram of an example of the first base station according to the sixth embodiment. FIG. 32 is a diagram of an example of the second base station according to the sixth embodiment. FIG. 33 is a diagram of an example of a terminal according to the sixth embodiment. FIG. 34 is a flowchart of an example of processing by the first base station according to the sixth embodiment. FIG. 35 is a flowchart of an example of processing by the second base station according to the sixth embodiment. FIG. 36 is a flowchart of an example of processing by the terminal according to the sixth embodiment. FIG. 37 is a diagram illustrating an example of retransmission of 4G packets by 5G in the communication system according to the embodiment.

Hereinafter, embodiments of a communication system, a terminal, a base station, and a communication method according to the present invention will be described in detail with reference to the drawings.

(Embodiment 1)
(Communication system according to Embodiment 1)
FIG. 1 is a diagram illustrating an example of a communication system according to the first embodiment. As illustrated in FIG. 1, the communication system 100 according to the first embodiment includes a first base station 110, a second base station 120, and a terminal 130. The terminal 130 is a UE (User Equipment) as an example.

The first base station 110 is a base station that constitutes a wireless communication system based on the first communication method with the terminal 130 (can perform wireless communication based on the first communication method). The 2nd base station 120 is a base station which constitutes the radio communications system by the 2nd communication system different from the 1st communication system between terminals 130 (a radio communication by the 2nd communication system is possible).

For example, the second communication method is a communication method having a shorter radio frame length than the first communication method. Further, for example, the second communication method is a communication method having a data retransmission cycle shorter than that of the first communication method. As a result, the second communication method has a shorter time required for retransmission when data retransmission occurs than the first communication method, that is, the delay is shorter. In FIG. 1, as an example, a case will be described in which the first communication method is 4G (fourth generation communication method) and the second communication method is 5G (fifth generation communication method). The difference in time required for retransmission between 4G and 5G will be described later (see, for example, FIG. 37).

The terminal 130 is addressed to its own station by simultaneously using a wireless communication system using the first communication method with the first base station 110 and a wireless communication system using the second communication method with the second base station 120. It is a terminal that can receive the data. The simultaneous use of the wireless communication system based on the first communication method and the wireless communication system based on the second communication method means, for example, using the wireless communication system based on the first communication method and the wireless communication system based on the second communication method in parallel. It is.

For example, the terminal 130 receives a data signal from the second base station 120 to 5G based on a control signal received from the first base station 110 to 4G. Alternatively, the terminal 130 receives data of one application (communication service) by link aggregation using 4G of the first base station 110 and 5G of the second base station 120. In addition, the terminal 130 simultaneously uses the wireless communication system according to the first communication method with the first base station 110 and the wireless communication system with the second communication method with the second base station 120 to perform data transmission. May be transmittable.

The EPC 101 is a core network to which the first base station 110 is connected. Note that EPC is an abbreviation for Evolved Packet Core. The aggregation unit 111 is a processing unit that distributes DL data transmitted from the EPC 101 to the terminal 130 into 4G packets (first data) wirelessly transmitted by 4G and 5G packets (second data) wirelessly transmitted by 5G. is there. However, in the communication system 100, 4G packets may be wirelessly transmitted by 5G during retransmission.

The aggregation unit 111 is a processing unit provided in the first base station 110 or the second base station 120, for example. Alternatively, the aggregation unit 111 may be a processing unit provided in a communication device different from the first base station 110 and the second base station 120. In the example illustrated in FIG. 1, the aggregation unit 111 is provided in the first base station 110.

The aggregation unit 111 transmits 4G packets and 5G packets to the second base station 120. At this time, for example, the aggregation unit 111 may add identification information indicating that the 4G packet is a retransmission 4G packet different from the 5G packet to the 4G packet. For example, the aggregation unit 111 uses a 4G retransmission IP address as a destination IP address of the second base station 120 in addition to 5G.

The first base station 110 wirelessly transmits the 4G packet obtained by the distribution by the aggregation unit 111 to the terminal 130. The second base station 120 wirelessly transmits the 5G packet transmitted from the aggregation unit 111 to the terminal 130. Further, the second base station 120 holds the 4G packet transmitted from the aggregation unit 111 for retransmission.

The 4G packet and the 5G packet distributed by the aggregation unit 111 are packets associated with each other. For example, the 4G packet and the 5G packet are each packet in one communication service used by the terminal 130.

The terminal 130 on the receiving side performs processing based on both the received 4G packet and 5G packet. For example, the terminal 130 receives a data signal using a 5G packet based on a control signal received using a 4G packet. Alternatively, the terminal 130 restores data of one application (communication service) by combining the received 4G packet and 5G packet in the link aggregation.

(Retransmission of 4G packets in the communication system according to the first embodiment)
FIG. 2 is a diagram illustrating an example of retransmission of 4G packets in the communication system according to the first embodiment. In FIG. 2, the same parts as those shown in FIG. As illustrated in FIG. 2, it is assumed that the terminal 130 fails to receive the 4G packet wirelessly transmitted from the first base station 110. That is, it is assumed that an error has occurred in the wireless transmission of 4G packets from the first base station 110 to the terminal 130.

When the terminal 130 detects an error in the 4G packet wirelessly transmitted from the first base station 110, the terminal 130 transmits a retransmission request for the 4G packet to the second base station 120. On the other hand, the second base station 120 wirelessly transmits the 4G packet received and held from the aggregation unit 111 to the terminal 130 using a 5G wireless frame (5G wireless format).

The 5G wireless transmission of the second base station 120 has a shorter delay due to the occurrence of data retransmission than the 4G wireless transmission of the first base station 110. Therefore, the retransmission of the 4G packet wirelessly transmitted by the 4G of the first base station 110 By using 5G of the second base station 120, the retransmission delay can be shortened. For this reason, for example, the time until the terminal 130 normally receives both the 4G packet and the 5G packet and restores the DL data from the EPC 101 can be shortened.

(Processing in the communication system according to the first embodiment)
FIG. 3 is a sequence diagram illustrating an example of processing in the communication system according to the first embodiment. In the communication system 100 according to the first embodiment, for example, each step shown in FIG. 3 is executed. In the example illustrated in FIG. 3, the aggregation unit 111 is described as a configuration that is logically or physically different from the first base station 110 (the same applies to other sequence diagrams).

First, the EPC 101 transmits DL data to the terminal 130 to the aggregation unit 111 (step S301). Next, the aggregation unit 111 performs packet distribution to distribute the data received from the EPC 101 in step S301 into 4G packets and 5G packets (step S302).

Next, the aggregation unit 111 transmits the 4G packet obtained by the packet distribution in step S302 to the first base station 110 (step S303). Further, the aggregation unit 111 transmits the 4G packet obtained by the packet distribution in step S302 to the second base station 120 (step S304). Further, the aggregation unit 111 transmits the 5G packet obtained by the packet distribution in step S302 to the second base station 120 (step S305). The order of steps S303 to S305 may be changed. Steps S303 to S305 may be executed simultaneously. Executing a plurality of steps simultaneously means, for example, executing a plurality of steps in parallel processing.

Next, the first base station 110 generates a 4G radio frame based on the 4G packet received from the aggregation unit 111 in step S303 (step S306). Next, the first base station 110 wirelessly transmits the 4G wireless frame generated in step S306 to the terminal 130 (step S307). The wireless transmission of the 4G wireless frame in step S307 is a new transmission.

Also, the second base station 120 generates a 5G radio frame based on the 5G packet received from the aggregation unit 111 in step S305 (step S308). Next, the second base station 120 wirelessly transmits the 5G wireless frame generated in step S308 to the terminal 130 (step S309). The wireless transmission of the 5G wireless frame in step S309 is a new transmission.

Next, the terminal 130 performs retransmission determination for determining whether or not retransmission is necessary based on the error detection result of the 4G radio frame (4G packet) received from the first base station 110 in step S307 (step S310). In the example illustrated in FIG. 3, it is assumed that the terminal 130 determines that the 4G radio frame received from the first base station 110 needs to be retransmitted (retransmission required) in step S307.

Next, the terminal 130 wirelessly transmits to the second base station 120 a 5G retransmission request for requesting the second base station 120 to retransmit the data of the 4G wireless frame received from the first base station 110 in step S307 ( Step S311). In this retransmission by the second base station 120, the data transmitted by the first base station 110 through the 4G radio frame is retransmitted by the second base station 120 through the 5G radio frame, and the 5G retransmission by switching from 4G to 5G (4G → 5G ).

3 is a UL (Up Link) 5G packet transmitted from the terminal 130 to the second base station 120. The 5G packet 310 illustrated in FIG. In step S310, a MAC PDU including the MAC header 311 and the MAC SDU 312 is generated. MAC is an abbreviation for Media Access Control. SDU is an abbreviation for Service Data Unit. PDU is an abbreviation for Protocol Data Unit. In step S311, the terminal 130 may transmit a 5G retransmission request by adding information (4G retransmission) requesting retransmission of data transmitted by 4G to 5G in the MAC header 311 of the 5G packet 310, for example. it can.

Next, the second base station 120 generates a 5G radio frame based on the 4G packet data received and held from the aggregation unit 111 in step S304 (step S312). Next, the second base station 120 performs the above-described 5G retransmission (4G → 5G) by wirelessly transmitting the 5G wireless frame generated in step S312 to the terminal 130 (step S313).

For example, in order to easily ensure compatibility with the conventional communication procedure, the terminal 130 sends a NACK (negative acknowledgment) to the 4G radio frame received from the first base station 110 in step S307 to the first base station 110. Wireless transmission may be performed (step S314). In this case, the first base station 110 wirelessly transmits the 4G wireless frame transmitted in step S307 to the terminal 130 (step S315). The wireless transmission of the 4G wireless frame in step S315 is a retransmission for the new transmission in step S307.

However, since the data of the 4G radio frame transmitted in step S315 is the same as the data of the 5G radio frame wirelessly transmitted in step S313, the data is redundant and has a large delay. Therefore, for example, the terminal 130 discards the data of the 4G radio frame received from the first base station 110 in step S315 in the upper layer. The upper layer is a TCP (Transmission Control Protocol) layer as an example.

FIG. 4 is a sequence diagram illustrating another example of processing in the communication system according to the first embodiment. In the communication system 100 according to the first embodiment, for example, each step shown in FIG. 4 may be executed. Steps S401 to S408 shown in FIG. 4 are the same as steps S301 to S304 and S306 to S309 shown in FIG. 3, respectively. That is, in the example illustrated in FIG. 4, the aggregation unit 111 may not immediately transmit the 4G packet obtained by the packet distribution in step S302 to the second base station 120.

After step S406, the first base station 110 gives discard time information based on the transmission timing of the 4G packet in step S406 to the 4G packet received from the aggregation unit 111 in step S403 (step S409). In step S409, for example, the first base station 110 adds discard time information to the extended information (option) of the IPv4 IP header in the 4G packet. IP is an abbreviation for Internet Protocol. The discard time information given to the 4G packet is information that allows the second base station 120 that has received the 4G packet to specify the discard time at which the 4G packet should be discarded. The discard time information will be described later.

Next, the first base station 110 transmits the 4G packet provided with the discard time information in step S409 to the aggregation unit 111 (step S410). Next, the aggregation unit 111 transmits the 4G packet received from the first base station 110 in step S410 to the second base station 120 (step S411).

Next, for the 4G packet received from the aggregation unit 111 in step S411, the second base station 120 starts packet discard monitoring based on the discard time information given to the 4G packet (step S412). Packet discard monitoring for a 4G packet is, for example, a process of monitoring whether the current time has passed the discard time specified by the discard time information, and discarding the 4G packet when the current time has passed the discard time. It is. Steps S413 to S418 shown in FIG. 4 are the same as steps S310 to S315 shown in FIG.

Thus, the discard time information based on the transmission timing of the 4G packet from the first base station 110 to the terminal 130 may be added to the 4G packet transferred to the second base station 120 for retransmission. Accordingly, when the 4G packet from the first base station 110 is normally received by the terminal 130, the second base station 120 can efficiently discard the 4G packet that does not require retransmission.

(First base station according to the first embodiment)
FIG. 5 is a diagram of an example of the first base station according to the first embodiment. In the example illustrated in FIG. 5, a configuration in which the aggregation unit 111 illustrated in FIG. 1 is provided in the first base station 110 will be described. In FIG. 5, for example, a configuration in which discard time information is added to a 4G packet transferred from the first base station 110 to the second base station 120 as illustrated in FIG. 4 will be described.

The first base station 110 according to the first embodiment includes, for example, an aggregation unit 111, an IP packet processing unit 501, a 4G packet processing unit 502, and a radio frame processing unit 503 as illustrated in FIG. . In addition, the first base station 110 includes a radio unit 504, an antenna 505, a radio scheduler 506, and a discard time information generation unit 507.

The IP packet processing unit 501 receives the DL data transmitted from the EPC 101 and outputs the received DL data to the aggregation unit 111. The IP packet processing unit 501 also outputs the DL 4G packet output from the aggregation unit 111 to the 4G packet processing unit 502. Further, the IP packet processing unit 501 transmits the DL 5G packet output from the aggregation unit 111 to the second base station 120. For example, an interface between base stations such as an X2 interface can be used for communication between the IP packet processing unit 501 and the second base station 120.

Also, the IP packet processing unit 501 outputs the DL 4G packet for transfer to the second base station 120 output from the 4G packet processing unit 502 to the aggregation unit 111. Further, the IP packet processing unit 501 transmits the DL 4G packet for transfer to the second base station 120 output from the aggregation unit 111 to the second base station 120.

Also, the IP packet processing unit 501 outputs the UL 4G packet output from the 4G packet processing unit 502 to the aggregation unit 111. Further, the IP packet processing unit 501 outputs the UL 5G packet received from the second base station 120 to the aggregation unit 111. Further, the IP packet processing unit 501 transmits the UL data output from the aggregation unit 111 to the EPC 101.

The aggregation unit 111 performs packet distribution for distributing DL data output from the IP packet processing unit 501 into DL 4G packets and DL 5G packets. Then, the aggregation unit 111 outputs the DL 4G packet and the DL 5G packet obtained by packet distribution to the IP packet processing unit 501.

Also, the aggregation unit 111 outputs the DL 4G packet for transfer to the second base station 120 output from the IP packet processing unit 501 to the IP packet processing unit 501. In the example illustrated in FIG. 5, the DL 4G packet for transfer to the second base station 120 is configured to be folded back by the aggregation unit 111, but the configuration is not limited thereto. For example, the IP packet processing unit 501 may transmit a DL 4G packet for transfer to the second base station 120 to the second base station 120 without passing through the aggregation unit 111.

Further, the aggregation unit 111 generates UL data by combining the UL 4G packet and the UL 5G packet output from the IP packet processing unit 501, and outputs the generated UL data to the IP packet processing unit 501. . In the example illustrated in FIG. 5, the configuration in which the UL 4G packet and the UL 5G packet are combined in the aggregation unit 111 has been described, but the configuration is not limited thereto. For example, the aggregation unit 111 transmits the UL 4G packet and the UL 5G packet to the EPC 101 via the IP packet processing unit 501 without combining them, and combines the UL 4G packet and the UL 5G packet in the EPC 101 device. May be performed.

The 4G packet processing unit 502 performs 4G packet transmission / reception processing in accordance with control from the wireless scheduler 506. For example, the 4G packet processing unit 502 outputs the DL 4G packet output from the IP packet processing unit 501 to the radio frame processing unit 503 and holds it. When the discard time information for the retained DL 4G packet is output from the discard time information generation unit 507, the 4G packet processing unit 502 adds the output discard time information to the DL 4G packet.

Also, the 4G packet processing unit 502 outputs the DL 4G packet with the discard time information to the IP packet processing unit 501 as a DL 4G packet for transfer to the second base station 120. Also, the 4G packet processing unit 502 outputs the UL 4G packet output from the radio frame processing unit 503 to the IP packet processing unit 501.

The radio frame processing unit 503 performs 4G radio frame transmission / reception processing in accordance with control from the radio scheduler 506. For example, the radio frame processing unit 503 generates a DL 4G radio frame based on the DL 4G packet output from the 4G packet processing unit 502. The radio frame processing unit 503 outputs the generated DL 4G radio frame to the radio unit 504.

Also, the radio frame processing unit 503 notifies the discard time information generation unit 507 of the transmission time of the DL 4G radio frame from the first base station 110 to the terminal 130. The transmission time of the 4G radio frame from the first base station 110 to the terminal 130 is, for example, the time when the radio frame processing unit 503 outputs the 4G radio frame to the radio unit 504.

Also, the radio frame processing unit 503 acquires a UL 4G packet from the UL 4G radio frame output from the radio unit 504. The radio frame processing unit 503 then outputs the acquired UL 4G packet to the 4G packet processing unit 502. Also, retransmission of the 4G radio frame in step S315 in FIG. 3 or steps S413 to S418 in FIG. 4 is performed by, for example, the radio frame processing unit 503.

The radio unit 504 performs an RF transmission process on the DL 4G radio frame output from the radio frame processing unit 503. RF is an abbreviation for Radio Frequency. The RF transmission processing by the radio unit 504 includes, for example, conversion from a digital signal to an analog signal, frequency conversion from a baseband band to an RF band, amplification, and the like. The radio unit 504 outputs the DL 4G radio frame subjected to the RF transmission process to the antenna 505.

Also, the radio unit 504 performs RF reception processing on the UL 4G radio frame output from the antenna 505. The RF reception processing by the radio unit 504 includes, for example, amplification, frequency conversion from the RF band to the baseband, conversion from an analog signal to a digital signal, and the like. The radio unit 504 outputs the UL 4G radio frame subjected to the RF reception process to the radio frame processing unit 503.

The antenna 505 wirelessly transmits the DL 4G wireless frame output from the wireless unit 504 to the terminal 130. Further, the antenna 505 receives the UL 4G radio frame wirelessly transmitted from the terminal 130 and outputs the received UL 4G radio frame to the radio unit 504.

The wireless scheduler 506 performs scheduling of 4G wireless communication between the first base station 110 and the terminal 130. The radio communication scheduling is a process of assigning radio resources to radio communication, for example. The radio scheduler 506 controls 4G packet transmission / reception processing in the 4G packet processing unit 502 and 4G radio frame transmission / reception processing in the radio frame processing unit 503 based on the scheduling result.

The discard time information generation unit 507 generates discard time information based on the transmission time of the DL 4G packet notified from the radio frame processing unit 503. Then, the discard time information generation unit 507 outputs the generated discard time information to the 4G packet processing unit 502. As described above, the discard time information is information that allows the second base station 120 that has received the DL 4G packet for retransmission to specify the discard time at which the DL 4G packet should be discarded.

For example, the discard time information can be information directly indicating a time after a predetermined time has elapsed from the time when the first base station 110 wirelessly transmits a DL 4G packet to the terminal 130. Alternatively, when the predetermined time is known in the second base station 120, the discard time information is, for example, the time (time stamp) when the first base station 110 wirelessly transmits a DL 4G packet to the terminal 130. Can do. The predetermined time is, for example, the time required from when the DL 4G packet is wirelessly transmitted from the first base station 110 to the terminal 130 until the 5G retransmission request is wirelessly transmitted from the terminal 130 to the second base station 120.

Although the configuration for giving the discard time information to the 4G packet transferred from the first base station 110 to the second base station 120 (see, for example, FIG. 4) has been described, the configuration is not limited thereto. That is, a configuration in which discard time information is not added to the 4G packet transferred from the first base station 110 to the second base station 120 (see, for example, FIG. 3) may be adopted. In this case, the discard time information generation unit 507 may be omitted from the first base station 110 illustrated in FIG. In this case, the 4G packet processing unit 502 outputs the DL 4G packet output from the IP packet processing unit 501 to the IP packet processing unit 501 without waiting for the discard time information from the discard time information generation unit 507.

(Second base station according to the first embodiment)
FIG. 6 is a diagram of an example of the second base station according to the first embodiment. In FIG. 6, a configuration in which the aggregation unit 111 illustrated in FIG. 1 is provided in the first base station 110 will be described. In addition, in FIG. 6, for example, as illustrated in FIG. 4, a configuration in which discard time information is added to a 4G packet transferred from the first base station 110 to the second base station 120 will be described.

For example, as shown in FIG. 6, the second base station 120 according to the first embodiment includes an IP packet processing unit 601, a 5G packet processing unit 602, and a radio frame processing unit 603. The second base station 120 includes a radio unit 604, an antenna 605, a MAC layer 4G / 5G processing unit 606, a radio scheduler 607, a 4G packet processing unit 608, and a packet discard processing unit 609.

The IP packet processing unit 601 receives the DL 5G packet transmitted from the first base station 110, and outputs the received DL 5G packet to the 5G packet processing unit 602. Also, the IP packet processing unit 601 receives the DL 4G packet transmitted from the first base station 110, and outputs the received DL 4G packet to the 4G packet processing unit 608. Also, the IP packet processing unit 601 transmits the UL 5G packet output from the 5G packet processing unit 602 to the first base station 110.

The 5G packet processing unit 602 performs 5G packet transmission / reception processing in accordance with control from the wireless scheduler 607. For example, the 5G packet processing unit 602 outputs the DL 5G packet output from the IP packet processing unit 601 to the radio frame processing unit 603. Also, the 5G packet processing unit 602 outputs the UL 5G packet output from the radio frame processing unit 603 to the IP packet processing unit 601.

The radio frame processing unit 603 performs 5G radio frame transmission / reception processing in accordance with control from the radio scheduler 607. For example, the radio frame processing unit 603 generates a DL 5G radio frame based on the DL 5G packet output from the 5G packet processing unit 602. The radio frame processing unit 603 then outputs the generated DL 5G radio frame to the radio unit 604.

The radio frame processing unit 603 holds the generated DL 5G radio frame for a predetermined period, and when the radio scheduler 607 instructs to retransmit the 5G packet, the 5G packet is again transmitted to the radio unit 604. Output. Accordingly, the 5G packet transmitted from the second base station 120 to the terminal 130 can be retransmitted to the terminal 130.

Also, when a 4G packet for retransmission is output from the 4G packet processing unit 608 under the control of the radio scheduler 607, the radio frame processing unit 603 generates a 5G radio frame based on the 4G packet. Then, the radio frame processing unit 603 outputs the generated 5G radio frame to the radio unit 604. Thereby, the data transmitted from the first base station 110 at 4G can be retransmitted at 5G.

Also, the radio frame processing unit 603 acquires a UL 5G packet from the UL 5G radio frame output from the radio unit 604. The radio frame processing unit 603 then outputs the acquired UL 5G packet to the 5G packet processing unit 602 and the MAC layer 4G / 5G processing unit 606.

The radio unit 604 performs RF transmission processing on the DL 5G radio frame output from the radio frame processing unit 603. The RF transmission processing by the radio unit 604 includes, for example, conversion from a digital signal to an analog signal, frequency conversion from a baseband to an RF band, amplification, and the like. The radio unit 604 outputs the DL 5G radio frame subjected to the RF transmission process to the antenna 605.

Also, the radio unit 604 performs RF reception processing on the UL 5G radio frame output from the antenna 605. The RF reception processing by the radio unit 604 includes, for example, amplification, frequency conversion from the RF band to the baseband, conversion from an analog signal to a digital signal, and the like. The radio unit 604 outputs the UL 5G radio frame subjected to the RF reception process to the radio frame processing unit 603.

The antenna 605 wirelessly transmits the DL 5G wireless frame output from the wireless unit 604 to the terminal 130. The antenna 605 receives a UL 5G radio frame wirelessly transmitted from the terminal 130 and outputs the received UL 5G radio frame to the radio unit 604.

The MAC layer 4G / 5G processing unit 606 acquires a 5G retransmission request included in the 5G packet output from the radio frame processing unit 603 by processing of the MAC layer. Then, the MAC layer 4G / 5G processing unit 606 outputs the acquired 5G retransmission request to the wireless scheduler 607. As described above, the 5G retransmission request is a control signal for requesting that data transmitted from the first base station 110 to 4G be retransmitted from the second base station 120 to 5G.

Also, the MAC layer 4G / 5G processing unit 606 acquires a retransmission request for the 5G packet transmitted from the second base station 120 included in the 5G packet output from the radio frame processing unit 603 by processing of the MAC layer. Then, the MAC layer 4G / 5G processing unit 606 outputs a retransmission request for the acquired 5G packet to the wireless scheduler 607.

The wireless scheduler 607 performs scheduling of 5G wireless communication between the second base station 120 and the terminal 130. The radio scheduler 607 controls 5G packet transmission / reception processing in the 5G packet processing unit 602 and 5G radio frame transmission / reception processing in the radio frame processing unit 603 based on the scheduling result.

Also, when a 5G retransmission request is output from the MAC layer 4G / 5G processing unit 606, the wireless scheduler 607 transmits a 4G packet requested to be retransmitted by the 5G retransmission request to the 4G packet processing unit 608 as a radio frame processing unit. Instruct to output to 603. Also, when a retransmission request for a 5G packet is output from the MAC layer 4G / 5G processing unit 606, the wireless scheduler 607 instructs the wireless frame processing unit 603 to retransmit the 5G packet.

The 4G packet processing unit 608 holds the 4G packet output from the IP packet processing unit 601. In response to an instruction from the radio scheduler 607 to output the held 4G packet to the radio frame processing unit 603, the 4G packet processing unit 608 outputs the held 4G packet to the radio frame processing unit 603.

The packet discard processing unit 609 refers to the discard time information attached to the 4G packet held by the 4G packet processing unit 608, and controls the 4G packet processing unit 608 to discard the 4G packet whose discard time has passed. Monitor packet discard.

Also, for example, as shown in FIG. 3, the configuration may be such that the discard time information is not added to the 4G packet transferred from the first base station 110 to the second base station 120. In this case, the packet discard processing unit 609 discards, for example, a packet for which a predetermined time has elapsed from the time of reception by the second base station 120 among 4G packets held by the 4G packet processing unit 608. Control may be performed as described above.

Alternatively, the packet discard processing unit 609 may monitor the free capacity of the memory used by the 4G packet processing unit 608 for holding 4G packets. The packet discard processing unit 609 preferentially discards the packet with the old reception time by the second base station 120 among the 4G packets held by the 4G packet processing unit 608 when the free capacity becomes a predetermined value or less. You may control so that it may.

The transmission unit that transmits data to the terminal 130 can be realized by, for example, the radio frame processing unit 603, the radio unit 604, and the antenna 605. Also, the reception unit that receives the retransmission request from the terminal 130 can be realized by the radio frame processing unit 603, the radio unit 604, and the antenna 605, for example.

(Hardware configurations of the first base station and the second base station according to the first embodiment)
FIG. 7 is a diagram of an example of a hardware configuration of the first base station and the second base station according to the first embodiment. Each of first base station 110 shown in FIG. 5 and second base station 120 shown in FIG. 6 can be realized by base station apparatus 700 shown in FIG. 7, for example.

The base station apparatus 700 includes antennas 711 to 713, RF modules 721 to 723, a selector 730, a DSP 740, and an NWP 750. DSP is an abbreviation for Digital Signal Processor. NWP is an abbreviation for NetWork Processor.

The RF module 721 is an RF module corresponding to a 4G communication band, and transmits and receives radio signals using the antenna 711. The RF module 722 is an RF module corresponding to a 5G communication band, and transmits and receives radio signals using the antenna 712. The RF module 723 is an RF module corresponding to a WLAN (Wireless Local Area Network) communication band, and transmits and receives radio signals using an antenna 713. For example, Wi-Fi (registered trademark) can be used for the WLAN.

Each of the RF modules 721 to 723 is connected to the DSP 740 via the selector 730. Each of the RF modules 721 to 723 includes, for example, an amplifier for amplification, a mixer for frequency conversion, a DAC for conversion from a digital signal to an analog signal, and an ADC for conversion from an analog signal to a digital signal Etc. are included. DAC is an abbreviation for Digital / Analog Converter. ADC is an abbreviation for Analog / Digital Converter.

The DSP 740 controls the radio communication in the base station apparatus 700 by controlling the RF modules 721 to 723 via the selector 730. NWP 750 is a communication circuit that performs communication with another communication apparatus connected to base station apparatus 700. By using the DSP 740 as a circuit for controlling the RF modules 721 to 723, an SDR (Software Defined Radio: software defined radio) configuration in which the control software can be changed without changing the electronic circuit can be obtained.

For example, when the first base station 110 shown in FIG. 5 is realized by the base station device 700, the aggregation unit 111, the IP packet processing unit 501, and the 4G packet processing unit 502 shown in FIG. 5 are realized by the NWP 750, for example. can do. Further, the radio frame processing unit 503, the radio scheduler 506, and the discard time information generation unit 507 illustrated in FIG. 5 can be realized by the DSP 740, for example. Further, the wireless unit 504 illustrated in FIG. 5 can be realized by the RF module 721, for example. Further, the antenna 505 illustrated in FIG. 5 can be realized by the antenna 711, for example. The antennas 712 and 713 and the RF modules 722 and 723 may be omitted.

When the second base station 120 illustrated in FIG. 6 is realized by the base station device 700, the IP packet processing unit 601, the 5G packet processing unit 602, the 4G packet processing unit 608, and the packet discard processing unit 609 illustrated in FIG. For example, it can be realized by NWP750. Further, the radio frame processing unit 603, the MAC layer 4G / 5G processing unit 606, and the radio scheduler 607 illustrated in FIG. 6 can be realized by the DSP 740, for example. Moreover, the radio | wireless part 604 shown in FIG. 6 is realizable with RF module 722, for example. Further, the antenna 605 illustrated in FIG. 6 can be realized by the antenna 712, for example. The antennas 711 and 713 and the RF modules 721 and 723 may be omitted.

(Terminal according to Embodiment 1)
FIG. 8 is a diagram of an example of the terminal according to the first embodiment. For example, as illustrated in FIG. 8, the terminal 130 according to the first embodiment includes an antenna 801, a radio unit 802, a radio frame processing unit 803, and a radio frame processing unit 804. The terminal 130 also includes an IP packet processing unit 805, an application processing unit 806, a 4G / 5G simultaneous use detection unit 807, and a MAC layer 4G / 5G processing unit 808.

The antenna 801 receives the DL 4G radio frame wirelessly transmitted from the first base station 110, and outputs the received DL 4G radio frame to the radio unit 802. The antenna 801 also receives the DL 5G radio frame wirelessly transmitted from the second base station 120, and outputs the received DL 5G radio frame to the radio unit 802.

In addition, the antenna 801 wirelessly transmits the UL 4G wireless frame output from the wireless unit 802 to the first base station 110. The antenna 801 wirelessly transmits the UL 5G wireless frame output from the wireless unit 802 to the second base station 120.

The radio unit 802 performs RF reception processing on the DL 4G radio frame and 5G radio frame output from the antenna 801. The RF reception processing by the wireless unit 802 includes, for example, amplification, frequency conversion from the RF band to the baseband, conversion from an analog signal to a digital signal, and the like. The radio unit 802 outputs the DL 4G radio frame subjected to the RF reception process to the radio frame processing unit 803 (4G). Also, the radio unit 802 outputs the DL 5G radio frame subjected to the RF reception process to the radio frame processing unit 804 (5G).

Also, the radio unit 802 performs RF transmission processing on the UL 4G radio frame output from the radio frame processing unit 803 (4G). The radio unit 802 performs RF transmission processing on the UL 5G radio frame output from the radio frame processing unit 804 (5G). The RF transmission processing by the wireless unit 802 includes, for example, conversion from a digital signal to an analog signal, frequency conversion from a baseband to an RF band, amplification, and the like. The radio unit 802 outputs the UL 4G radio frame and 5G radio frame subjected to the RF transmission processing to the antenna 801.

The radio frame processing unit 803 acquires a DL 4G packet from the DL 4G radio frame output from the radio unit 802. The radio frame processing unit 803 then outputs the acquired DL 4G packet to the IP packet processing unit 805. In addition, when detecting an error in the acquired DL 4G packet (when decoding is not possible), the radio frame processing unit 803 notifies the MAC layer 4G / 5G processing unit 808 to that effect.

Also, the radio frame processing unit 803 generates a UL 4G radio frame based on the UL 4G packet output from the IP packet processing unit 805. The radio frame processing unit 803 then outputs the generated UL 4G radio frame to the radio unit 802.

The radio frame processing unit 804 acquires a DL 5G packet from the DL 5G radio frame output from the radio unit 802. The radio frame processing unit 804 then outputs the acquired DL 5G packet to the IP packet processing unit 805.

Further, the radio frame processing unit 804 generates a UL 5G radio frame based on the UL 5G packet output from the IP packet processing unit 805. Then, the radio frame processing unit 804 outputs the generated UL 5G radio frame to the radio unit 802.

In addition, when instructed by the MAC layer 4G / 5G processing unit 808 to transmit a 5G retransmission request, the radio frame processing unit 804 performs 5G based on the UL 5G packet in which information requesting retransmission by 5G is added to the MAC header. Generate a radio frame. Accordingly, a 5G retransmission request can be transmitted to the second base station 120.

The IP packet processing unit 805 combines the 4G packet output from the radio frame processing unit 803 and the 5G packet output from the radio frame processing unit 804 to generate DL data, and generates the generated DL data. The data is output to the application processing unit 806.

Also, the IP packet processing unit 805 performs packet distribution that distributes UL data output from the application processing unit 806 into 4G packets and 5G packets. Then, the IP packet processing unit 805 outputs the 4G packet obtained by the packet distribution to the radio frame processing unit 803, and outputs the 5G packet obtained by the packet distribution to the radio frame processing unit 804.

Application processing unit 806 is a processing unit that executes an application using communication. An application executed by the application processing unit 806 performs processing based on DL data output from the IP packet processing unit 805. Also, the application executed by the application processing unit 806 generates UL data and outputs it to the IP packet processing unit 805.

The 4G / 5G simultaneous use detection unit 807 detects the simultaneous use (for example, dual connectivity) of 4G communication and 5G communication by the terminal 130 by monitoring the radio frame processing units 803 and 804. Then, the 4G / 5G simultaneous use detection unit 807 notifies the MAC layer 4G / 5G processing unit 808 of the detection result of the simultaneous use of 4G communication and 5G communication by the terminal 130.

The MAC layer 4G / 5G processing unit 808 performs the above-mentioned 5G retransmission request transmission processing by the MAC layer processing based on the notification results from the radio frame processing unit 803 and the 4G / 5G simultaneous use detection unit 807. For example, when an error in a DL 4G packet is detected during simultaneous use of 4G communication and 5G communication by the terminal 130, the MAC layer 4G / 5G processing unit 808 wirelessly transmits a 5G retransmission request for the 4G packet. Instructs the frame processing unit 804.

The receiving unit that receives each data from the first base station 110 and the second base station 120 can be realized by the antenna 801, the radio unit 802, and the radio frame processing units 803 and 804, for example. The transmission unit that transmits the retransmission request to the second base station 120 can be realized by, for example, the antenna 801, the radio unit 802, and the radio frame processing units 803 and 804.

(Hardware configuration of the terminal according to the first embodiment)
FIG. 9 is a diagram of an example of a hardware configuration of the terminal according to the first embodiment. The terminal 130 illustrated in FIG. 8 can be realized by, for example, the terminal device 900 illustrated in FIG. The terminal device 900 includes an antenna 911, 912, an RF module 921, 922, a DSP 930, an MPU 940, and a flash memory 950. MPU is an abbreviation for Micro Processing Unit.

The RF module 921 is an RF module corresponding to a 4G communication band, and transmits and receives radio signals using the antenna 911. The RF module 922 is an RF module corresponding to a 5G communication band, and transmits and receives radio signals using the antenna 912. Each of the RF modules 921 and 922 is connected to the DSP 930. Each of the RF modules 921 and 922 includes, for example, an amplifier for amplification, a mixer for frequency conversion, a DAC for conversion from a digital signal to an analog signal, and an ADC for conversion from an analog signal to a digital signal Etc. are included.

The DSP 930 controls wireless communication in the terminal device 900 by controlling the RF modules 921 and 922. The MPU 940 is a processing unit that executes an application in the terminal 130. An application executed by the MPU 940 instructs the DSP 930 to transmit / receive data. The flash memory 950 is a nonvolatile memory that stores programs executed by the MPU 940 and various data.

The antenna 801 shown in FIG. 8 can be realized by the antennas 911 and 912, for example. The wireless unit 802 illustrated in FIG. 8 can be realized by the RF modules 921 and 922, for example. The radio frame processing units 803, 804, 4G / 5G simultaneous use detection unit 807 and MAC layer 4G / 5G processing unit 808 shown in FIG. 8 can be realized by the DSP 930, for example. The IP packet processing unit 805 and the application processing unit 806 shown in FIG. 8 can be realized by the MPU 940, for example.

(Processing by the first base station according to the first embodiment)
FIG. 10 is a flowchart of an example of processing by the first base station according to the first embodiment. The first base station 110 according to the first embodiment repeatedly executes, for example, each step illustrated in FIG. In the example illustrated in FIG. 10, the case where the aggregation unit 111 illustrated in FIG. 1 is provided in the first base station 110 will be described (the same applies to other flowcharts).

First, the first base station 110 receives DL data (for example, a packet) transmitted from the EPC 101 (step S1001). Next, the first base station 110 performs packet distribution to distribute the data received in step S1001 into 4G packets and 5G packets (step S1002).

Next, the first base station 110 transmits the 4G packet and the 5G packet obtained by the packet distribution in step S1002 to the second base station 120 (step S1003). In addition, the first base station 110 wirelessly transmits the 4G packet obtained by the packet distribution in step S1002 to the terminal 130 (step S1004). Steps S1003 and S1004 may be switched in order or executed simultaneously.

Next, the first base station 110 determines whether or not a retransmission request for the 4G packet transmitted in step S1004 has been received from the terminal 130 (step S1005). In step S1005, when the retransmission request is not received (step S1005: No), the first base station 110 ends the series of processes. When the retransmission request is received (step S1005: Yes), the first base station 110 retransmits the 4G packet wirelessly transmitted in step S1004 to the terminal 130 (step S1006), and ends a series of processing.

In the example shown in FIG. 10, the DL data received by the first base station 110 in step S1001 has been described once in steps S1002 to S1006. However, the present invention is not limited to such a process. For example, the first base station 110 may transmit the DL data received in step S1001 in multiple steps by repeating steps S1002 to S1006.

In addition, the first base station 110 may determine whether or not the 4G packet retransmission request transmitted in step S1006 has been received from the terminal 130, and may further retransmit the 4G packet when the retransmission request is received. Good.

(Processing by the second base station according to the first embodiment)
FIG. 11 is a flowchart of an example of processing by the second base station according to the first embodiment. The second base station 120 according to the first embodiment repeatedly executes, for example, each step shown in FIG. First, the second base station 120 receives DL 4G packets and 5G packets transmitted from the first base station 110 (step S1101).

Next, the second base station 120 wirelessly transmits the 5G packet received in step S1101 to the terminal 130 (step S1102). Also, the second base station 120 determines whether or not a retransmission request for the 5G packet wirelessly transmitted in step S1102 has been received from the terminal 130 (step S1103).

In step S1103, when the 5G packet retransmission request is not received (step S1103: No), the second base station 120 proceeds to step S1105. When the 5G packet retransmission request is received (step S1103: Yes), the second base station 120 retransmits the 5G packet wirelessly transmitted in step S1102 to the terminal 130 (step S1104).

Also, the second base station 120 determines whether or not the 5G retransmission request for the 4G packet wirelessly transmitted from the first base station 110 to the terminal 130 has been received from the terminal 130 (step S1105). When the 5G retransmission request has not been received (step S1105: No), the second base station 120 ends the series of processes.

In Step S1105, when the 5G retransmission request is received (Step S1105: Yes), the second base station 120 proceeds to Step S1106. That is, the second base station 120 wirelessly transmits the 4G packet corresponding to the received 5G retransmission request among the 4G packets received in step S1101 to the terminal 130 using the 5G radio frame (step S1106), and ends the series of processes. To do.

Steps S1103 and S1104 and steps S1105 and S1106 may be switched in order or may be executed simultaneously. Moreover, the 2nd base station 120 may perform step S1103, S1104, without waiting for reception of 5G packet, when 5G packet is received in step S1101, and 4G packet is not received. In this case, the second base station 120 executes steps S1105 and S1106 after receiving the 4G packet from the first base station 110.

(Processing by the terminal according to the first embodiment)
FIG. 12 is a flowchart of an example of processing performed by the terminal according to the first embodiment. The terminal 130 according to the first embodiment repeatedly executes each step shown in FIG. 12, for example. First, the terminal 130 receives DL 4G packets and 5G packets (new transmission) transmitted from the first base station 110 and the second base station 120 (step S1201).

Next, the terminal 130 determines whether or not the 4G packet received in step S1201 has been decoded (step S1202). If the 4G packet can be decoded (step S1202: Yes), the terminal 130 proceeds to step S1207.

In step S1202, if the 4G packet cannot be decoded (step S1202: No), the terminal 130 wirelessly transmits a 5G retransmission request for the 4G packet to the second base station 120 (step S1203). Next, the terminal 130 receives the 4G packet retransmitted by the 5G radio frame from the second base station 120 in response to the 5G retransmission request in step S1203 (step S1204).

Also, the terminal 130 wirelessly transmits a 4G packet retransmission request to the first base station 110 (step S1205). Next, the terminal 130 receives the 4G packet retransmitted by the 4G radio frame from the first base station 110 in response to the retransmission request in step S1205 (step S1206). However, the terminal 130 discards the 4G packet received in step S1206.

Note that steps S1203 and S1204 and steps S1205 and S1206 may be switched in order or may be executed simultaneously. Further, the processing may be performed by omitting steps S1205 and S1206.

Next, the terminal 130 determines whether or not the 5G packet received in step S1201 has been decoded (step S1207). When the 5G packet can be decoded (step S1207: Yes), the terminal 130 ends the series of processes. When the 5G packet cannot be decoded (step S1207: No), the terminal 130 wirelessly transmits a retransmission request for the 5G packet to the second base station 120 (step S1208). Next, the terminal 130 receives the 5G packet retransmitted by the 5G radio frame from the second base station 120 in response to the retransmission request in step S1208 (step S1209), and ends the series of processes.

Note that the order of steps S1202 to S1206 and steps S1207 to S1209 may be interchanged or may be executed simultaneously. In addition, the terminal 130 determines whether or not the 4G packet received in step S1204 has been decoded, and performs a process of transmitting a 5G retransmission request for the 4G packet to the second base station 120 if the decoding has failed. Also good. Further, the terminal 130 may determine whether or not the 5G packet received in step S1209 has been decoded, and may perform a process of transmitting a retransmission request for the 5G packet to the second base station 120 if the decoding is not possible. .

When the series of processes shown in FIG. 12 is completed, the terminal 130 performs a process of combining the received 4G packet and 5G packet to restore DL data transmitted from the EPC 101 to the terminal 130.

As described above, in the communication system 100 according to the first embodiment, when the terminal 130 fails to receive the 4G packet wirelessly transmitted from the first base station 110 using the 4G radio frame, retransmission of the 4G packet is performed. The request is wirelessly transmitted to the second base station 120. Then, when the second base station 120 receives a retransmission request for a 4G packet from the first base station 110, the second base station 120 wirelessly transmits the 4G packet to the terminal 130 using a 5G radio frame. Thereby, the delay at the time of data retransmission due to a data error can be shortened.

Also, the first base station 110 generates information that can specify the discard time of the 4G packet based on the time when the first base station 110 wirelessly transmitted the 4G packet to the terminal 130. Then, the second base station 120 holds the 4G packet, and discards the held 4G packet based on the information generated by the first base station 110. Thereby, the 2nd base station 120 can specify the discard time when the 4G packet currently hold | maintained for resending becomes unnecessary, and can discard the 4G packet hold | maintained efficiently.

(Embodiment 2)
In the second embodiment, parts different from the first embodiment will be described. In the second embodiment, a configuration in which a 5G retransmission request is transmitted not in the MAC layer but in an RRC (Radio Resource Control) layer will be described.

(Processing in the communication system according to the second embodiment)
The process in the communication system 100 according to the second embodiment is the same as the process illustrated in FIGS. 3 and 4, for example. However, in step S311 illustrated in FIG. 3 and step S414 illustrated in FIG. 4, the terminal 130 transmits a 5G retransmission request in the RRC layer. For example, the terminal 130 transmits a 5G retransmission request to the second base station 120 by adding information requesting retransmission of 5G data transmitted by 4G to the Inter-Rat IE of the RRC layer of the UL 5G packet. To do.

(Second base station according to the second embodiment)
FIG. 13 is a diagram of an example of the second base station according to the second embodiment. In FIG. 13, the same parts as those shown in FIG. For example, as illustrated in FIG. 13, the second base station 120 according to the second embodiment includes an RRC layer 4G / 5G processing unit 1301 instead of the MAC layer 4G / 5G processing unit 606 illustrated in FIG. 6. The RRC layer 4G / 5G processing unit 1301 acquires a 5G retransmission request included in the 5G packet output from the radio frame processing unit 603 by processing of the RRC layer. Then, the RRC layer 4G / 5G processing unit 1301 outputs the acquired 5G retransmission request to the radio scheduler 607.

(Terminal according to the second embodiment)
FIG. 14 is a diagram of an example of a terminal according to the second embodiment. In FIG. 14, the same parts as those shown in FIG. For example, as illustrated in FIG. 14, the terminal 130 according to the second embodiment includes an RRC layer 4G / 5G processing unit 1401 instead of the MAC layer 4G / 5G processing unit 808 illustrated in FIG. 8.

The RRC layer 4G / 5G processing unit 1401 performs the above-described 5G retransmission request transmission processing based on the notification results from the radio frame processing unit 803 and the 4G / 5G simultaneous use detection unit 807 by RRC layer processing. For example, when an error in a DL 4G packet is detected during simultaneous use of 4G communication and 5G communication by the terminal 130, the RRC layer 4G / 5G processing unit 1401 wirelessly transmits a 5G retransmission request for the 4G packet. Instructs the frame processing unit 804.

As described above, according to the communication system 100 according to the second embodiment, in the configuration in which the retransmission request for the 4G packet is transmitted by the processing of the RRC layer, as in the first embodiment, at the time of data retransmission due to the data error The delay can be shortened. The transmission of the 5G retransmission request is not limited to the MAC layer (Embodiment 1) or the RRC layer (Embodiment 2), and can be performed by processing of various layers.

Further, the second embodiment can be realized in combination with each configuration of the first embodiment described above. For example, in the second embodiment, the second base station 120 may discard the 4G packet using the discard time information described above.

(Embodiment 3)
The third embodiment will be described with respect to differences from the first and second embodiments. In the first and second embodiments, the configuration in which the second base station 120 performs 5G wireless communication has been described. However, in the third embodiment, the second base station 120 performs wireless communication by WLAN (for example, Wi-Fi). The structure which performs is demonstrated. Similar to 5G, WLAN is a communication method that has a shorter delay associated with data retransmission than 4G.

(Processing in the communication system according to the third embodiment)
FIG. 15 is a sequence diagram of an example of processing in the communication system according to the third embodiment. In the communication system 100 according to the third embodiment, for example, each step shown in FIG. 15 is executed. Steps S1501 to S1515 shown in FIG. 15 are the same as steps S301 to S315 shown in FIG.

However, the second base station 120 performs wireless communication by WLAN. That is, in step S1502, the aggregation unit 111 performs packet distribution that distributes the data received from the EPC 101 in step S1501 into 4G packets and WLAN packets. In step S1505, the aggregation unit 111 transmits the WLAN packet obtained by the packet distribution in step S1502 to the second base station 120.

In step S1508, the second base station 120 generates a WLAN radio frame based on the WLAN packet received from the aggregation unit 111 in step S1505. In step S1509, the second base station 120 wirelessly transmits the WLAN radio frame generated in step S1508 to the terminal 130.

Also, in step S1511, the terminal 130 wirelessly sends a WLAN retransmission request to the second base station 120 for making a retransmission request to the second base station 120 for data of the 4G radio frame received from the first base station 110 in step S1507. Send. The retransmission by the second base station 120 is a WLAN retransmission (4G → WLAN) by switching from 4G to WLAN in which the second base station 120 retransmits the data transmitted by the first base station 110 by 4G by WLAN.

In step S1512, the second base station 120 generates a WLAN radio frame based on the 4G packet data received and held from the aggregation unit 111 in step S1505. In step S1513, the second base station 120 performs the above-described WLAN retransmission (4G → WLAN) by wirelessly transmitting the WLAN radio frame generated in step S1512 to the terminal 130.

In the communication system 100 according to the third embodiment, for example, as illustrated in FIG. 4, the 4G packet transferred from the first base station 110 to the terminal 130 is transferred to the 4G packet transferred to the second base station 120 for retransmission. The discard time information based on the transmission timing may be added. Accordingly, when the 4G packet from the first base station 110 is normally received by the terminal 130, the second base station 120 can efficiently discard the 4G packet that does not require retransmission.

(First base station according to the third embodiment)
The first base station 110 according to the third embodiment is the same as the first base station 110 illustrated in FIG. 5, for example. However, the aggregation unit 111 of the first base station 110 according to the third embodiment performs packet distribution that distributes DL data output from the IP packet processing unit 501 into DL 4G packets and DL WLAN packets. Then, the aggregation unit 111 outputs the DL 4G packet and the DL WLAN packet obtained by packet distribution to the IP packet processing unit 501.

In addition, the IP packet processing unit 501 transmits the DL WLAN packet output from the aggregation unit 111 to the second base station 120. Also, the IP packet processing unit 501 outputs the UL WLAN packet received from the second base station 120 to the aggregation unit 111. In addition, the aggregation unit 111 generates UL data by combining the UL 4G packet and the UL WLAN packet output from the IP packet processing unit 501, and outputs the generated UL data to the IP packet processing unit 501. .

(Second base station according to the third embodiment)
FIG. 16 is a diagram of an example of the second base station according to the third embodiment. In FIG. 16, the same parts as those shown in FIG. For example, as shown in FIG. 16, the second base station 120 according to the third embodiment replaces the 5G packet processing unit 602 and the MAC layer 4G / 5G processing unit 606 with a WLAN packet processing unit 1601 and a MAC layer 4G / WLAN. A processing unit 1602 is provided.

The WLAN packet processing unit 1601 can be realized by, for example, the NWP 750 shown in FIG. The MAC layer 4G / WLAN processing unit 1602 can be realized by, for example, the DSP 740 shown in FIG.

The IP packet processing unit 601 receives the DL WLAN packet transmitted from the first base station 110, and outputs the received DL WLAN packet to the WLAN packet processing unit 1601. Further, the IP packet processing unit 601 transmits the UL WLAN packet output from the WLAN packet processing unit 1601 to the first base station 110.

The WLAN packet processing unit 1601 performs WLAN packet transmission / reception processing according to control from the wireless scheduler 607. For example, the WLAN packet processing unit 1601 outputs the DL WLAN packet output from the IP packet processing unit 601 to the radio frame processing unit 603. Also, the WLAN packet processing unit 1601 outputs the UL WLAN packet output from the wireless frame processing unit 603 to the IP packet processing unit 601.

The wireless frame processing unit 603 performs WLAN wireless frame transmission / reception processing according to control from the wireless scheduler 607. For example, the radio frame processing unit 603 generates a DL WLAN radio frame based on the DL WLAN packet output from the WLAN packet processing unit 1601. The radio frame processing unit 603 then outputs the generated DL WLAN radio frame to the radio unit 604.

The radio frame processing unit 603 holds the generated DL WLAN radio frame for a predetermined period, and when the radio scheduler 607 instructs to retransmit the WLAN packet, the radio frame processing unit 603 outputs the WLAN packet to the radio unit 604 again. . Thereby, the WLAN packet transmitted from the second base station 120 to the terminal 130 can be retransmitted to the terminal 130.

Further, when a 4G packet for retransmission is output from the 4G packet processing unit 608 under the control of the radio scheduler 607, the radio frame processing unit 603 generates a WLAN radio frame based on the 4G packet. Then, the radio frame processing unit 603 outputs the generated WLAN radio frame to the radio unit 604. Thereby, the data transmitted by 4G from the 1st base station 110 can be retransmitted by WLAN.

Further, the radio frame processing unit 603 acquires a UL WLAN packet from the UL WLAN radio frame output from the radio unit 604. The radio frame processing unit 603 then outputs the acquired UL WLAN packet to the WLAN packet processing unit 1601 and the MAC layer 4G / WLAN processing unit 1602.

The radio unit 604 performs RF transmission processing on the DL WLAN radio frame output from the radio frame processing unit 603, and outputs the DL WLAN radio frame subjected to the RF transmission processing to the antenna 605. The radio unit 604 performs RF reception processing on the UL WLAN radio frame output from the antenna 605, and outputs the UL WLAN radio frame subjected to the RF reception processing to the radio frame processing unit 603.

The antenna 605 wirelessly transmits the DL WLAN wireless frame output from the wireless unit 604 to the terminal 130. Further, the antenna 605 receives the UL WLAN radio frame wirelessly transmitted from the terminal 130 and outputs the received UL WLAN radio frame to the radio unit 604.

The MAC layer 4G / WLAN processing unit 1602 acquires the WLAN retransmission request included in the WLAN packet output from the wireless frame processing unit 603 by processing of the MAC layer, and outputs the acquired WLAN retransmission request to the wireless scheduler 607. As described above, the WLAN retransmission request is a control signal for requesting retransmission of data transmitted from the first base station 110 through 4G from the second base station 120 through the WLAN.

Further, the MAC layer 4G / WLAN processing unit 1602 acquires a retransmission request for the WLAN packet transmitted from the second base station 120, which is included in the WLAN packet output from the radio frame processing unit 603, by processing of the MAC layer. Then, the MAC layer 4G / WLAN processing unit 1602 outputs a retransmission request for the acquired WLAN packet to the wireless scheduler 607.

The wireless scheduler 607 performs WLAN wireless communication scheduling between the second base station 120 and the terminal 130. The wireless scheduler 607 controls WLAN packet transmission / reception processing in the WLAN packet processing unit 1601 and WLAN wireless frame transmission / reception processing in the wireless frame processing unit 603 based on the scheduling result.

Further, when a WLAN retransmission request is output from the MAC layer 4G / WLAN processing unit 1602, the wireless scheduler 607 sends the 4G packet requested to be retransmitted to the 4G packet processing unit 608 to the wireless frame processing unit 603. Instruct to output. In addition, when a retransmission request for a WLAN packet is output from the MAC layer 4G / WLAN processing unit 1602, the wireless scheduler 607 instructs the wireless frame processing unit 603 to retransmit the WLAN packet.

(Terminal according to the third embodiment)
FIG. 17 is a diagram of an example of a terminal according to the third embodiment. 17, parts that are the same as the parts shown in FIG. 8 are given the same reference numerals, and descriptions thereof will be omitted. As illustrated in FIG. 17, the terminal 130 according to the third embodiment replaces the 4G / 5G simultaneous usage detection unit 807 and the MAC layer 4G / 5G processing unit 808 illustrated in FIG. 8 with a 4G / WLAN simultaneous usage detection unit 1701. And a MAC layer 4G / WLAN processing unit 1702.

The antenna 801 receives the DL WLAN radio frame wirelessly transmitted from the second base station 120, and outputs the received DL WLAN radio frame to the radio unit 802. The antenna 801 wirelessly transmits the UL WLAN radio frame output from the radio unit 802 to the second base station 120.

The radio unit 802 performs an RF reception process on the DL WLAN radio frame output from the antenna 801, and outputs the DL WLAN radio frame subjected to the RF reception process to the radio frame processing unit 804 (WLAN). Also, the wireless unit 802 performs RF transmission processing on the UL WLAN wireless frame output from the wireless frame processing unit 804 (WLAN), and outputs the UL WLAN wireless frame subjected to the RF transmission processing to the antenna 801.

When the radio frame processing unit 803 detects an error in the acquired DL 4G packet, the radio frame processing unit 803 notifies the MAC layer 4G / WLAN processing unit 1702 to that effect.

The radio frame processing unit 804 acquires a DL WLAN packet from the DL WLAN radio frame output from the radio unit 802. The radio frame processing unit 804 then outputs the acquired DL WLAN packet to the IP packet processing unit 805.

The wireless frame processing unit 804 generates a UL WLAN wireless frame based on the UL WLAN packet output from the IP packet processing unit 805. Then, the radio frame processing unit 804 outputs the generated UL WLAN radio frame to the radio unit 802. In addition, when instructed by the MAC layer 4G / WLAN processing unit 1702 to transmit a WLAN retransmission request, the wireless frame processing unit 804 generates a WLAN radio generated based on a UL WLAN packet to which information requesting retransmission in WLAN is added. The frame is output to the wireless unit 802. Thereby, a WLAN retransmission request can be transmitted to the second base station 120.

The IP packet processing unit 805 generates DL data by combining the 4G packet output from the radio frame processing unit 803 and the WLAN packet output from the radio frame processing unit 804, and generates the generated DL data. The data is output to the application processing unit 806.

Also, the IP packet processing unit 805 performs packet distribution that distributes UL data output from the application processing unit 806 into 4G packets and WLAN packets. Then, the IP packet processing unit 805 outputs the 4G packet obtained by the packet distribution to the radio frame processing unit 803, and outputs the WLAN packet obtained by the packet distribution to the radio frame processing unit 804.

The 4G / WLAN simultaneous use detection unit 1701 detects the simultaneous use of 4G communication and WLAN communication by the terminal 130 by monitoring the radio frame processing units 803 and 804. Then, the 4G / WLAN simultaneous use detection unit 1701 notifies the MAC layer 4G / WLAN processing unit 1702 of the detection result of the simultaneous use of 4G communication and WLAN communication by the terminal 130.

The MAC layer 4G / WLAN processing unit 1702 performs the above-described WLAN retransmission request transmission processing by MAC layer processing based on the notification results from the wireless frame processing unit 803 and the 4G / WLAN simultaneous use detection unit 1701. For example, when an error of a DL 4G packet is detected during simultaneous use of 4G communication and WLAN communication by the terminal 130, the MAC layer 4G / WLAN processing unit 1702 wirelessly transmits a WLAN retransmission request for the 4G packet. Instructs the frame processing unit 804.

(Hardware configuration of the terminal according to the third embodiment)
FIG. 18 is a diagram illustrating an example of a hardware configuration of a terminal according to the third embodiment. 18, parts that are the same as the parts shown in FIG. 9 are given the same reference numerals, and descriptions thereof will be omitted. The terminal 130 shown in FIG. 17 can be realized by, for example, the terminal device 900 shown in FIG. A terminal device 900 shown in FIG. 18 includes an RF module 1811 and an ASIC 1821 corresponding to WLAN instead of the RF module 922 shown in FIG. ASIC is an abbreviation for Application Specific Integrated Circuit.

The RF module 1811 is an RF module compatible with the WLAN communication band, and transmits and receives radio signals using the antenna 912. The RF module 1811 is connected to the ASIC 1821. The RF module 1811 includes, for example, an amplifier for amplification, a mixer for frequency conversion, a DAC for conversion from a digital signal to an analog signal, an ADC for conversion from an analog signal to a digital signal, and the like. .

The ASIC 1821 controls the wireless communication of the WLAN in the terminal device 900 by controlling the RF module 1811. The application executed by the MPU 940 instructs at least one of the DSP 930 and the ASIC 1821 to transmit and receive data.

The 4G / WLAN simultaneous use detection unit 1701 and the MAC layer 4G / WLAN processing unit 1702 shown in FIG. 17 can be realized by a DSP 930 or an MPU 940, for example.

(Processing by the first base station according to the third embodiment)
The process performed by the first base station 110 according to the third embodiment is the same as the process illustrated in FIG. 10, for example. However, in step S1002 shown in FIG. 10, the first base station 110 performs packet distribution that distributes the data received in step S1001 into 4G packets and WLAN packets. In step S1003, the first base station 110 transmits the WLAN packet obtained by the packet distribution in step S1002 to the second base station 120.

(Processing by the second base station according to the third embodiment)
The process performed by the second base station 120 according to the third embodiment is the same as the process illustrated in FIG. 11, for example. However, in step S1101 illustrated in FIG. 11, the second base station 120 receives the DL 4G packet and the WLAN packet transmitted from the first base station 110. In step S1102, the second base station 120 wirelessly transmits the WLAN packet received in step S1101 to the terminal 130.

In step S1103, the second base station 120 determines whether or not a retransmission request for the WLAN packet wirelessly transmitted in step S1102 has been received from the terminal 130. In step S1104, the second base station 120 retransmits the WLAN packet wirelessly transmitted in step S1102 to the terminal 130.

In step S1105, the second base station 120 determines whether or not the WLAN retransmission request for the 4G packet wirelessly transmitted from the first base station 110 to the terminal 130 has been received from the terminal 130. In step S1106, the second base station 120 wirelessly transmits the 4G packet corresponding to the received WLAN retransmission request among the 4G packets received in step S1101 to the terminal 130 using the WLAN radio frame.

(Processing by the terminal according to the third embodiment)
The process by the terminal 130 according to the third embodiment is the same as the process shown in FIG. 12, for example. However, in step S1201 illustrated in FIG. 12, the terminal 130 receives DL 4G packets and WLAN packets (new transmission) transmitted from the first base station 110 and the second base station 120. In step S1203, the terminal 130 wirelessly transmits a WLAN retransmission request for the 4G packet to the second base station 120.

In step S1204, the terminal 130 receives the 4G packet retransmitted by the WLAN radio frame from the second base station 120 in response to the WLAN retransmission request in step S1203. In step S1207, the terminal 130 determines whether the WLAN packet received in step S1201 has been decoded.

In step S1208, a WLAN packet retransmission request is wirelessly transmitted to the second base station 120. In step S1209, the terminal 130 receives the WLAN packet retransmitted by the WLAN radio frame from the second base station 120 in response to the retransmission request in step S1208. Then, when the series of processing illustrated in FIG. 12 is completed, the terminal 130 reconstructs DL data transmitted from the EPC 101 to the terminal 130 by performing a process of combining the received 4G packet and the WLAN packet.

Thus, according to the communication system 100 according to the third embodiment, even in the configuration in which the second base station 120 performs wireless communication by WLAN, the delay at the time of data retransmission due to a data error is reduced as in the first embodiment. Can be shortened. Further, the communication method of the second base station 120 is not limited to WLAN, and various communication methods that have a shorter delay due to the occurrence of data retransmission than the communication method of the first base station 110 can be used. In addition, the communication method of the first base station 110 is not limited to 4G, and various communication methods having a longer wireless transmission delay than the communication method of the second base station 120 can be used.

Further, the third embodiment can be realized in combination with each configuration of the first and second embodiments described above. For example, in the third embodiment, the second base station 120 may discard the 4G packet using the discard time information as shown in FIG. 4, for example. Moreover, in Embodiment 3, it is good also as a structure which transmits the resending request | requirement about 4G packet by the process of a RRC layer like Embodiment 2. FIG.

(Embodiment 4)
In the fourth embodiment, parts different from the first to third embodiments will be described. In the fourth embodiment, a configuration in which a predetermined retransmission area is used for transmitting a 5G retransmission request will be described.

(Processing in the communication system according to the fourth embodiment)
FIG. 19 is a sequence diagram illustrating an example of processing in the communication system according to the fourth embodiment. In the communication system 100 according to the third embodiment, for example, each step shown in FIG. 19 is executed. Steps S1901 to S1910 shown in FIG. 19 are the same as steps S301 to S310 shown in FIG.

Next to step S1910, the terminal 130 scans a predetermined retransmission area (step S1911). The predetermined retransmission area is a frequency band for transmitting a 5G retransmission request (or WLAN retransmission request), and is a frequency band that the terminal 130 shares with other bands. The predetermined retransmission area is, for example, a part of an area allocated for 5G communication. The predetermined retransmission area may be a dedicated band for a 5G retransmission request. As an example, the predetermined retransmission region is one of each subband separated by filtering in F-OFDM (Filtered-OFDM). By scanning a predetermined retransmission area in step S1911, an area that is not used by another terminal in the predetermined retransmission area can be detected.

Next, the terminal 130 determines a band to be used for transmission of a 5G retransmission request in a predetermined retransmission area based on the scan result of step S1911 (step S1912). Steps S1913 to S1917 shown in FIG. 19 are the same as steps S311 to S315 shown in FIG. However, in step S1913, the terminal 130 wirelessly transmits a 5G retransmission request to the second base station 120 using the band determined in step S1912.

If it is determined in step S1911 that there is no area that is not used by another terminal in the predetermined retransmission area, the terminal 130 does not proceed to step S1912, but continues the scan in step S1911. . Then, when the terminal 130 detects an area that is not used by another terminal in the predetermined retransmission area, the terminal 130 proceeds to step S1912.

(Second base station according to the fourth embodiment)
FIG. 20 is a diagram of an example of the second base station according to the fourth embodiment. 20, parts that are the same as the parts shown in FIG. 6 are given the same reference numerals, and descriptions thereof will be omitted. For example, as illustrated in FIG. 20, the second base station 120 according to the fourth embodiment includes a radio frame processing unit 2001 in addition to the configuration illustrated in FIG. 6.

The radio unit 604 outputs, to the radio frame processing unit 2001, the radio frame in the predetermined retransmission area described above among the UL 5G radio frames subjected to the RF reception process. A radio frame processing unit 2001 performs reception processing of a radio frame in a predetermined retransmission area output from the radio unit 604. Radio frame processing section 2001 then outputs the 5G packet obtained by the reception processing to MAC layer 4G / 5G processing section 606.

The MAC layer 4G / 5G processing unit 606 acquires the 5G retransmission request included in the 5G packet output from the wireless frame processing unit 2001 by processing of the MAC layer, and outputs the acquired 5G retransmission request to the wireless scheduler 607.

(Terminal according to Embodiment 4)
FIG. 21 is a diagram of an example of a terminal according to the fourth embodiment. In FIG. 21, the same parts as those shown in FIG. For example, as illustrated in FIG. 21, the terminal 130 according to the fourth embodiment includes a radio frame processing unit 2101 in addition to the configuration illustrated in FIG. 8.

The radio unit 802 performs RF transmission processing on the UL 5G radio frame output from the radio frame processing units 803 and 804 and the radio frame processing unit 2101. The MAC layer 4G / 5G processing unit 808 instructs the radio frame processing unit 2101 to transmit a 5G retransmission request through the MAC layer processing.

When instructed by the MAC layer 4G / 5G processing unit 808 to transmit a 5G retransmission request, the wireless frame processing unit 2101 generates 5G based on the UL 5G packet added to the MAC header with information requesting retransmission by 5G. The wireless frame is output to the wireless unit 802. Accordingly, a 5G retransmission request can be transmitted to the second base station 120.

Further, for example, scanning of a predetermined retransmission area in step S1911 illustrated in FIG. 19 can be performed by the radio frame processing unit 2101 controlling the radio unit 802, for example. The radio frame processing unit 2101 controls the radio unit 802 to transmit a 5G retransmission request using a free area of a predetermined retransmission area detected by scanning.

(Processing by the terminal according to the fourth embodiment)
FIG. 22 is a flowchart of an example of processing performed by the terminal according to the fourth embodiment. The terminal 130 according to the fourth embodiment repeatedly executes each step shown in FIG. 22, for example. Steps S2201 and S2202 shown in FIG. 22 are the same as steps S1201 and S1202 shown in FIG.

However, if the 4G packet can be decoded in step S2202 (step S2202: Yes), the terminal 130 proceeds to step S2209. If the 4G packet cannot be decoded (step S2202: NO), the terminal 130 proceeds to step S2203. That is, the terminal 130 scans a predetermined retransmission area to determine whether or not there is a vacancy that is not used by another terminal in the predetermined retransmission area (step S2203), and determines that there is a vacancy. (Step S2203: No loop). If there is a vacancy (step S2203: Yes), the terminal 130 determines an area to be used for transmission of the 5G retransmission request from a predetermined retransmission area vacancy (step S2204).

Steps S2205 to S2211 shown in FIG. 22 are the same as steps S1203 to S1209 shown in FIG. However, in step S2205, the terminal 130 wirelessly transmits a 5G retransmission request for the 4G packet to the second base station 120 using the area determined in step S2204.

Thus, according to the communication system 100 according to the fourth embodiment, when the terminal 130 fails to receive the 4G packet wirelessly transmitted from the first base station 110, it can be used in the 5G wireless communication system. It is possible to detect a free band in a predetermined band. Then, the terminal 130 can wirelessly transmit a retransmission request for the 4G packet to the second base station 120 based on the detected available bandwidth. Thereby, the retransmission request for the 4G packet can be wirelessly transmitted to the second base station 120 with a short delay. For this reason, the delay at the time of data retransmission due to a data error can be shortened.

Further, the fourth embodiment can be realized in combination with each configuration of the first to third embodiments described above. For example, in the fourth embodiment, the second base station 120 may discard the 4G packet using the discard time information as shown in FIG. 4, for example. Moreover, in Embodiment 4, it is good also as a structure which transmits the resending request | requirement about 4G packet by the process of an RRC layer like Embodiment 2. FIG. Further, in the fourth embodiment, the second base station 120 may perform wireless communication by WLAN as in the third embodiment.

(Embodiment 5)
In the fifth embodiment, parts different from the first to fourth embodiments will be described. In the fifth embodiment, a configuration will be described in which transfer of a retransmission packet from the first base station 110 to the second base station 120 is not performed immediately after packet separation.

(Processing in Communication System According to Embodiment 5)
FIG. 23 is a sequence diagram of an example of processing in the communication system according to the fifth embodiment. In the communication system 100 according to the fifth embodiment, for example, each step shown in FIG. 23 is executed.

Steps S2301 to S2310 shown in FIG. 23 are the same as steps S301 to S304 and S306 to S311 shown in FIG. 3, respectively. That is, in Embodiment 5, the aggregation unit 111 may not immediately transmit the 5G packet obtained by the packet distribution in step S2302 to the second base station 120. However, the first base station 110 holds the 4G packet wirelessly transmitted in step S2306 for a predetermined time.

Next to step S2310, the second base station 120 transmits the 5G retransmission request received from the terminal 130 in step S2309 to the first base station 110 (step S2311). Next, the first base station 110 extracts the 4G packet that was wirelessly transmitted and retained in step S2306 (step S2312).

Next, the first base station 110 transmits the 4G packet extracted in step S2312 to the second base station 120 (step S2313). Steps S2314 to S2317 shown in FIG. 23 are the same as steps S312 to S315 shown in FIG. However, in step S2314, the second base station 120 generates a 5G radio frame based on the 4G packet data received from the first base station 110 in step S2313.

(First base station according to the fifth embodiment)
FIG. 24 is a diagram of an example of the first base station according to the fifth embodiment. In FIG. 24, the same parts as those shown in FIG. For example, as illustrated in FIG. 24, the first base station 110 according to the fifth embodiment includes a packet extraction unit 2401 in addition to the configuration illustrated in FIG. The packet extraction unit 2401 can be realized by the NWP 750 shown in FIG. 7, for example. Also, the first base station 110 according to the fifth embodiment may not include the discard time information generation unit 507 illustrated in FIG.

The IP packet processing unit 501 outputs the 5G retransmission request received from the second base station 120 to the 4G packet processing unit 502. Also, the IP packet processing unit 501 transmits the DL 4G packet for transfer to the second base station 120 output from the packet extraction unit 2401 to the second base station 120. The 4G packet processing unit 502 outputs the 5G retransmission request output from the IP packet processing unit 501 to the packet extraction unit 2401.

The packet extraction unit 2401 extracts the corresponding 4G packet from the 4G packets held by the 4G packet processing unit 502 based on the 5G retransmission request output from the 4G packet processing unit 502. Then, the packet extraction unit 2401 outputs the extracted 4G packet to the IP packet processing unit 501 as a DL 4G packet for transfer to the second base station 120.

Also, the 4G packet processing unit 502 may perform packet discard monitoring that discards packets that have passed a predetermined time since being transmitted by the radio frame processing unit 503 among the held 4G packets.

(Second base station according to the fifth embodiment)
FIG. 25 is a diagram of an example of the second base station according to the fifth embodiment. In FIG. 25, the same parts as those shown in FIG. For example, as illustrated in FIG. 25, the second base station 120 according to the fifth embodiment replaces the 4G packet processing unit 608 and the packet discard processing unit 609 illustrated in FIG. 6 with 4G packet retransmission request units 2501 and 4G packets. A retransmission processing unit 2502 is provided. The 4G packet retransmission request unit 2501 and the 4G packet retransmission processing unit 2502 can be realized by, for example, the NWP 750 illustrated in FIG.

The MAC layer 4G / 5G processing unit 606 acquires the 5G retransmission request included in the 5G packet output from the radio frame processing unit 603 by the MAC layer processing, and outputs the acquired 5G retransmission request to the 4G packet retransmission request unit 2501 To do. The 4G packet retransmission request unit 2501 outputs the 5G retransmission request output from the MAC layer 4G / 5G processing unit 606 to the IP packet processing unit 601.

The IP packet processing unit 601 transmits the 5G retransmission request output from the 4G packet retransmission request unit 2501 to the first base station 110. Thereby, a 4G packet corresponding to the 5G retransmission request can be requested to the first base station 110. Also, the IP packet processing unit 601 outputs the DL 4G packet for retransmission transmitted from the first base station 110 to the 4G packet retransmission processing unit 2502.

The 4G packet retransmission processing unit 2502 outputs the 4G packet output from the IP packet processing unit 601 to the wireless frame processing unit 603 under the control of the wireless scheduler 607. Thereby, the data transmitted from the first base station 110 by 4G can be retransmitted by the second base station 120 by the WLAN.

(Processing by the first base station according to the fifth embodiment)
FIG. 26 is a flowchart of an example of processing by the first base station according to the fifth embodiment. The first base station 110 according to the fifth embodiment repeatedly executes the steps shown in FIG. 26, for example. Steps S2601 to S2606 shown in FIG. 26 are the same as steps S1001 to S1006 shown in FIG. However, in step S2603, the first base station 110 transmits the 5G packet obtained by the packet distribution in step S2602 to the second base station 120, and holds the 4G packet obtained by the packet distribution.

After step S2606, the first base station 110 determines whether a 5G retransmission request for the 4G packet wirelessly transmitted in step S2604 has been received from the second base station 120 (step S2607). When the 5G retransmission request has not been received (step S2607: No), the first base station 110 ends the series of processes. When the 5G retransmission request is received (step S2607: Yes), the first base station 110 transmits the 4G packet obtained and retained by the packet distribution in step S2602 to the second base station 120 (step S2608). Then, a series of processing is completed.

Note that the order of steps S2605 and S2606 and steps S2607 and S2608 may be interchanged or may be executed simultaneously. Moreover, it is good also as the process which excluded step S2605 and S2606.

(Processing by the second base station according to the fifth embodiment)
FIG. 27 is a flowchart of an example of processing by the second base station according to the fifth embodiment. The second base station 120 according to the fifth embodiment repeatedly executes, for example, each step shown in FIG. Steps S2701 to S2705 shown in FIG. 27 are the same as steps S1101 to S1105 shown in FIG. However, in step S2701, the second base station 120 receives the DL 5G packet transmitted from the first base station 110.

When the 5G retransmission request is received in step S2705 (step S2705: Yes), the second base station 120 transmits the received 5G retransmission request to the first base station 110 (step S2706). Next, the second base station 120 receives the 4G packet transmitted from the first base station 110 (step S2707). Next, the second base station 120 wirelessly transmits the 4G packet received in step S2707 to the terminal 130 using a 5G wireless frame (step S2708), and ends a series of processing.

Thus, according to the communication system 100 according to the fifth embodiment, the first base station 110 can hold the 4G packet wirelessly transmitted to the terminal 130. When the second base station 120 receives a retransmission request for a 4G packet from the terminal 130, the second base station 120 receives the 4G packet held by the first base station 110 from the first base station 110, and receives the received 4G packet. 130 can be wirelessly transmitted. As a result, the number of 4G packets received and held by the second base station 120 for retransmission can be reduced, thereby improving the throughput and reducing the memory capacity for the 4G packets in the second base station 120.

Further, the fifth embodiment can be realized in combination with each configuration of the first to fourth embodiments described above. For example, in the fifth embodiment, a retransmission request for a 4G packet may be transmitted by RRC layer processing as in the second embodiment. Further, in the fifth embodiment, the second base station 120 may be configured to perform wireless communication by WLAN as in the third embodiment. Further, in the fifth embodiment, as in the fourth embodiment, a configuration may be adopted in which a retransmission request for a 4G packet is transmitted using a predetermined bandwidth.

(Embodiment 6)
The sixth embodiment will be described with respect to differences from the first to fifth embodiments. In the first to fifth embodiments, the configuration in which the present invention is applied to DL data transmission from the EPC 101 to the terminal 130 has been described. In the sixth embodiment, UL data transmission from the terminal 130 to the EPC 101 is described. A configuration to which the present invention is applied will be described.

(Communication system according to Embodiment 6)
FIG. 28 is a diagram of an example of a communication system according to the sixth embodiment. In FIG. 28, the same parts as those shown in FIG. In the sixth embodiment, the terminal 130 performs packet distribution that distributes UL data to be transmitted to the EPC 101 into 4G packets and 5G packets. Then, the terminal 130 wirelessly transmits the 4G packet obtained by packet distribution to the first base station 110 using a 4G wireless frame. Also, the terminal 130 wirelessly transmits the 5G packet obtained by packet distribution to the second base station 120 using a 5G wireless frame.

The second base station 120 transmits the 5G packet acquired from the 5G radio frame received from the terminal 130 to the aggregation unit 111 (first base station 110). The aggregation unit 111 restores the UL data by combining the 4G packet acquired from the 4G radio frame received by the first base station 110 from the terminal 130 and the 5G packet transmitted from the second base station 120. To do.

Then, the aggregation unit 111 transmits the restored UL data to the EPC 101. However, the synthesis of the 4G packet and the 5G packet is not limited to the aggregation unit 111, and may be performed by another device in the EPC 101, for example. In this case, the aggregation unit 111 transmits the 4G packet and the 5G packet to another apparatus of the EPC 101 that combines the 4G packet and the 5G packet.

(Retransmission of 4G packets in the communication system according to the sixth embodiment)
FIG. 29 is a diagram of an example of retransmission of 4G packets in the communication system according to the sixth embodiment. 29, the same parts as those shown in FIG. 2 are denoted by the same reference numerals, and description thereof is omitted. As shown in FIG. 29, it is assumed that an error occurs in transmission of a 4G packet from the terminal 130 to the first base station 110, and the 4G packet cannot be decoded in the first base station 110.

In this case, the terminal 130 generates a 5G radio frame based on the data of the 4G packet in which an error has occurred, and wirelessly transmits the generated 5G radio frame to the second base station 120. The second base station 120 acquires a 4G packet from the 5G radio frame received from the terminal 130, and transmits the acquired 4G packet to the first base station 110. Thereby, retransmission of 4G packets can be performed by 5G.

(Processing in the communication system according to the sixth embodiment)
FIG. 30 is a sequence diagram illustrating an example of processing in the communication system according to the sixth embodiment. In the communication system 100 according to the sixth embodiment, for example, each step shown in FIG. 30 is executed.

First, the terminal 130 generates a 5G radio frame based on the 5G packet (step S3001). The 5G packet in step S3001 is, for example, a 5G packet obtained by performing packet distribution in which terminal 130 distributes UL data to 4G packets and 5G packets. Next, the terminal 130 wirelessly transmits the 5G wireless frame generated in step S3001 to the second base station 120 (step S3002). The wireless transmission of the 5G wireless frame in step S3002 is a new transmission.

Next, the second base station 120 transmits the 5G packet acquired from the 5G radio frame received from the terminal 130 in step S3002 to the aggregation unit 111 (step S3003). Next, the aggregation unit 111 transmits the 5G packet received from the second base station 120 in step S3003 to the EPC 101 (step S3004).

Further, the terminal 130 generates a 4G radio frame based on the 4G packet (step S3005). The 4G packet in step S3005 is, for example, a 4G packet obtained by performing packet distribution in which terminal 130 distributes UL data into 4G packets and 5G packets. Next, the terminal 130 wirelessly transmits the 4G wireless frame generated in step S3005 to the first base station 110 (step S3006). The wireless transmission of the 4G wireless frame in step S3006 is a new transmission.

Next, the first base station 110 performs retransmission determination for determining whether or not retransmission is necessary based on the error detection result of the 4G radio frame (4G packet) received from the terminal 130 in step S3006 (step S3007). In the example illustrated in FIG. 30, it is assumed that the first base station 110 determines that it is necessary to retransmit the 4G radio frame received from the terminal 130 in step S3007 (retransmission required).

Next, the first base station 110 wirelessly transmits to the terminal 130 a retransmission request (NACK) for the 4G wireless frame received from the terminal 130 in step S3006 (step S3008). Next, the terminal 130 generates a 5G radio frame based on the data of the 4G packet wirelessly transmitted by the 4G radio frame in step S3006 (step S3009).

Next, the terminal 130 wirelessly transmits the 5G wireless frame generated in step S3009 to the second base station 120 (step S3010). Thereby, the data of the 4G packet transmitted by 4G in step S3006 can be retransmitted. The retransmission by the terminal 130 is a 5G retransmission (4G → 5G) by switching from 4G to 5G, in which data transmitted to the first base station 110 by a 4G radio frame is retransmitted to the second base station 120 by a 5G radio frame. .

Next, the second base station 120 acquires a 4G packet from the 5G radio frame received from the terminal 130 in step S3010, and transmits the acquired 4G packet to the aggregation unit 111 (step S3011). Next, the aggregation unit 111 transmits the 4G packet received from the second base station 120 in step S3011 to the EPC 101 (step S3012).

Note that the order of steps S3001 to S3004 and steps S3005 to S3012 may be interchanged or may be executed simultaneously.

For example, in order to easily ensure compatibility with the conventional communication procedure, the terminal 130 wirelessly transmits the 4G radio frame generated in step S3005 to the first base station 110 in response to the NACK received in step S3008. It may be done (step S3013). In this case, the first base station 110 transmits the 4G packet acquired from the 4G radio frame received from the terminal 130 in step S3013 to the aggregation unit 111 (step S3014).

Next, the aggregation unit 111 transmits the 4G packet received from the first base station 110 in step S3014 to the EPC 101 (step S3015), and the series of processing ends. However, since the data of the 4G packet transmitted in step S3015 is the same as the data of the 5G radio frame wirelessly transmitted in step S3012, the data is redundant and has a large delay. For this reason, for example, the apparatus of the EPC 101 discards the data of the 4G packet received from the aggregation unit 111 in step S3015 in the upper layer.

In the example illustrated in FIG. 30, the aggregation unit 111 has described the process of transmitting the 4G packet and the 5G packet received from the first base station 110 and the second base station 120 to another apparatus of the EPC 101 without combining them. It is not restricted to such a process. For example, the aggregation unit 111 may restore the UL data by combining the 5G packet received from the second base station 120 in step S3004 and the 4G packet received from the second base station 120 in step S3012. Good. In this case, the aggregation unit 111 transmits the restored UL data to the EPC 101.

(First base station according to the sixth embodiment)
FIG. 31 is a diagram of an example of the first base station according to the sixth embodiment. In FIG. 31, parts that are the same as the parts shown in FIG. 5 are given the same reference numerals, and descriptions thereof will be omitted. For example, as shown in FIG. 31, the first base station 110 according to the sixth embodiment may be configured to omit the 4G packet processing unit 502 and the discard time information generating unit 507 shown in FIG.

The IP packet processing unit 501 outputs the UL 4G packet output from the radio frame processing unit 503 to the aggregation unit 111. Also, the IP packet processing unit 501 outputs the UL 4G packet and 5G packet received from the second base station 120 to the aggregation unit 111. Further, the IP packet processing unit 501 transmits the UL data output from the aggregation unit 111 to the EPC 101. Alternatively, the IP packet processing unit 501 transmits the UL 4G packet and the UL 5G packet output from the aggregation unit 111 to the EPC 101.

The aggregation unit 111 combines the UL 4G packet and the UL 5G packet output from the IP packet processing unit 501 to generate UL data, and outputs the generated UL data to the IP packet processing unit 501. Alternatively, when the 4G packet and the 5G packet are combined by the apparatus of the EPC 101, the aggregation unit 111 does not combine the UL 4G packet and the UL 5G packet output from the IP packet processing unit 501, and the IP packet processing unit Output to 501.

(Second base station according to the sixth embodiment)
FIG. 32 is a diagram of an example of the second base station according to the sixth embodiment. 32, the same parts as those shown in FIG. 6 are denoted by the same reference numerals and description thereof is omitted. For example, as illustrated in FIG. 32, the second base station 120 according to the sixth embodiment includes a 5G packet processing unit 602, a MAC layer 4G / 5G processing unit 606, a 4G packet processing unit 608, and a packet discarding unit illustrated in FIG. The processing unit 609 can be omitted.

Also, the radio frame processing unit 603 acquires a UL 4G packet or a 5G packet from the UL 5G radio frame output from the radio unit 604. Then, the radio frame processing unit 603 outputs the acquired UL 4G packet or 5G packet to the IP packet processing unit 601. The IP packet processing unit 601 transmits the UL 4G packet and 5G packet output from the radio frame processing unit 603 to the first base station 110.

(Terminal according to Embodiment 6)
FIG. 33 is a diagram of an example of a terminal according to the sixth embodiment. In FIG. 33, the same parts as those shown in FIG. For example, as illustrated in FIG. 33, the terminal 130 according to the sixth embodiment includes a 5G retransmission unit 3301 instead of the MAC layer 4G / 5G processing unit 808 illustrated in FIG.

When the radio frame processing unit 803 detects, from the DL 4G radio frame output from the radio unit 802, a retransmission request (NACK) for the 4G packet transmitted from the terminal 130 to the first base station 110 using the 4G radio frame, This is notified to the 5G retransmission unit 3301.

The 5G retransmission unit 3301 performs UL 5G retransmission (4G → 5G) by switching from 4G to 5G based on the notification results from the radio frame processing unit 803 and the 4G / 5G simultaneous use detection unit 807. For example, when a retransmission request for a 4G packet is detected during simultaneous use of 4G communication and 5G communication by the terminal 130, the 5G retransmission unit 3301 outputs a 5G retransmission request for the 4G packet to the IP packet processing unit 805. .

The IP packet processing unit 805 outputs the 4G packet obtained by the packet distribution to the radio frame processing unit 803 and holds the 4G packet for a predetermined time. When the 5G retransmission request for the 4G packet is output from the 5G retransmission unit 3301, the IP packet processing unit 805 transmits the 4G packet corresponding to the 5G retransmission request among the held 4G packets to the radio frame processing unit 804. Output to. Accordingly, a 5G retransmission request can be transmitted to the second base station 120, and 5G retransmission can be performed by switching from 4G to 5G.

(Processing by the first base station according to the sixth embodiment)
FIG. 34 is a flowchart of an example of processing by the first base station according to the sixth embodiment. The first base station 110 according to the sixth embodiment repeatedly executes the steps shown in FIG. 34, for example. First, the first base station 110 receives a 4G packet transmitted by a 4G radio frame from the terminal 130 (step S3401). Next, the first base station 110 determines whether or not the 4G packet received in step S3401 has been decoded (step S3402).

In step S3402, if 4G packet reception can be decoded (step S3402: YES), the first base station 110 proceeds to step S3406. If 4G packet reception cannot be decoded (step S3402: NO), the first base station 110 wirelessly transmits a retransmission request for the 4G packet received in step S3401 to the terminal 130 (step S3403).

Next, in response to the retransmission request wirelessly transmitted in step S3403, the first base station 110 transmits the terminal 130 to the second base station 120 using a 5G wireless frame and receives the 4G packet transferred from the second base station 120. (Step S3404). Further, the first base station 110 receives the 4G packet retransmitted by the 4G radio frame from the terminal 130 in response to the retransmission request wirelessly transmitted in step S3403 (step S3405). Note that steps S3404 and S3405 may be switched in order or executed simultaneously. Further, the process may be performed without step S3405.

Next, the first base station 110 receives the 5G packet that the terminal 130 transmits to the second base station 120 using a 5G radio frame and transferred from the second base station 120 (step S3406). Next, the first base station 110 combines the 4G packet received in steps S3401 and S3404 and the 5G packet received from the second base station 120 in step S3406 (step S3407). Next, the first base station 110 transmits the UL data obtained by the synthesis in step S3407 to the EPC 101 (step S3408), and ends the series of processes.

Note that the order of steps S3401 to S3405 and step S3406 may be interchanged, or may be executed simultaneously.

(Processing by the second base station according to the sixth embodiment)
FIG. 35 is a flowchart of an example of processing by the second base station according to the sixth embodiment. The second base station 120 according to the sixth embodiment repeatedly executes the steps shown in FIG. 35, for example. First, the second base station 120 receives a 5G packet transmitted by a 5G radio frame from the terminal 130 (step S3501). Next, the second base station 120 determines whether or not the 5G packet received in step S3501 has been decoded (step S3502).

In step S3502, if 5G packet reception can be decoded (step S3502: Yes), the second base station 120 proceeds to step S3505. When the 5G packet reception cannot be decoded (step S3502: No), the first base station 110 wirelessly transmits a retransmission request for the 5G packet received in step S3501 to the terminal 130 (step S3503).

Next, the second base station 120 receives the 5G packet retransmitted by the 5G radio frame from the terminal 130 in response to the retransmission request wirelessly transmitted in step S3503 (step S3504). Next, the second base station 120 transmits the 5G packet received from the terminal 130 in steps S3501 and S3504 to the first base station 110 (step S3505).

Next, the second base station 120 determines whether or not the 4G packet wirelessly transmitted from the terminal 130 by the 5G wireless frame is received in response to the retransmission request from the first base station 110 (step S3506). When the 4G packet has not been received (step S3506: No), the second base station 120 ends the series of processes. When the 4G packet is received (step S3506: Yes), the second base station 120 transmits (transfers) the received 4G packet to the first base station 110 (step S3507), and ends a series of processes.

(Processing by the terminal according to the sixth embodiment)
FIG. 36 is a flowchart of an example of processing by the terminal according to the sixth embodiment. For example, the terminal 130 according to the sixth embodiment repeatedly executes the steps shown in FIG. First, the terminal 130 performs packet distribution for distributing UL data into 4G packets and 5G packets (step S3601). Next, the terminal 130 wirelessly transmits the 4G packet and the 5G packet obtained by the packet distribution in step S3601 to the first base station 110 and the second base station 120, respectively (step S3602).

Next, the terminal 130 determines whether a retransmission request for the 4G packet wirelessly transmitted in step S3602 has been received from the first base station 110 (step S3603). If a retransmission request has not been received (step S3603: NO), the terminal 130 proceeds to step S3606.

In step S3603, when a retransmission request is received (step S3603: Yes), the terminal 130 wirelessly transmits the 4G packet wirelessly transmitted in step S3602 to the second base station 120 using a 5G wireless frame (step S3604). Also, the terminal 130 retransmits the 4G packet wirelessly transmitted in step S3602 to the first base station 110 using a 4G wireless frame (step S3605). Note that steps S3604 and S3605 may be switched in order or executed simultaneously. Further, the processing may be performed without step S3605.

Next, the terminal 130 determines whether a retransmission request for the 5G packet wirelessly transmitted in step S3602 has been received from the second base station 120 (step S3606). When the retransmission request has not been received (step S3606: No), the terminal 130 ends the series of processes. When the retransmission request is received (step S3606: Yes), the terminal 130 retransmits the 5G packet wirelessly transmitted in step S3602 to the second base station 120 using the 5G wireless frame (step S3607), and ends the series of processes. .

As described above, according to the communication system 100 according to the sixth embodiment, when the terminal 130 receives a retransmission request for a 4G packet wirelessly transmitted to the first base station 110, the 4G packet is transmitted using a 5G wireless frame. Wireless transmission to the second base station 120 is possible. Thereby, also in the uplink from the terminal 130 to the EPC 101, the delay at the time of data retransmission due to a data error can be shortened as in the first embodiment.

Further, the sixth embodiment can be realized in combination with the configuration of each of the embodiments described above. For example, in the sixth embodiment, a configuration may be adopted in which a retransmission request for a 4G packet is transmitted by RRC layer processing as in the second embodiment. Further, in the sixth embodiment, the second base station 120 may perform wireless communication by WLAN as in the third embodiment.

As described above, according to the communication system, the terminal, the base station, and the communication method, the delay at the time of data retransmission due to a data error can be shortened.

For example, in LTE-Advanced, there is a dual connectivity (Dual Connectivity) as a configuration in which a master base station and a slave base station linked with the master base station can be connected to both the master base station and the slave base station. In the LTE-Advanced enhanced 5G network, for example, the master base station is a 4G macro base station and the slave base station is a 5G small cell.

In the dual connectivity in which the terminal is connected to both the 4G macro base station and the 5G small base station, when an error occurs in radio communication, the terminal makes a retransmission request to the base station in which the radio error has occurred, Retransmission is performed by the base station.

For example, the radio frame length in 4G is, for example, 1 [ms]. On the other hand, the radio frame length in 5G is 0.1 [ms]. Therefore, when a retransmission of a radio error occurs, the delay required for retransmission differs depending on whether it is via 4G or 5G. As an example, a case will be described in which HARQ (Hybrid Automatic Repeat reQuest) is retransmitted by 8 TTI (Time To Interval). In this case, retransmission by 5G can be performed in 0.8 [ms], but retransmission by 4G requires 8 [ms].

For example, when 5G data communication is performed based on a 4G control signal, 5G data communication may be awaited due to a 4G wireless error. Alternatively, when data communication of one application is transmitted by 4G and 5G link aggregation, an IP packet cannot be correctly decoded due to a wireless error on the 4G side, and as a result, a TCP window is locked.

On the other hand, according to each of the above-described embodiments, when a 4G-side radio error occurs, retransmission at 5G can reduce the delay at the time of data retransmission.

Suppose that 4G packets are retransmitted by 4G. The time required for initial transmission of 4G packets is 1 [ms], the time required for decoding 4G packets on the receiving side and 4G NACK transmission is 4 [ms], and the time required for NACK decoding and 4G packet retransmission on the transmitting side. 4 [ms]. In this case, the time required for the initial transmission and retransmission of the 4G packet is 1 + 4 + 4 = 9 [ms].

On the other hand, it is assumed that 4G packets are retransmitted by 5G as in the first embodiment described above. The time required for initial transmission of 4G packets is 1 [ms], the time required for decoding 4G packets on the receiving side and NACK transmission in 5G is α [ms], and the time required for NACK decoding and retransmission of 4G packets on the transmitting side. 0.4 [ms]. In this case, the time required for the initial transmission and retransmission of the 4G packet is 1 + α + 0.4 = 1.4 + α [ms]. α is the time required for decoding 4G packets and NACK transmission in 5G on the receiving side as described above, and 1.4 + α [ms] is shorter than 9 [ms].

(Retransmission of 4G packets by 5G in the communication system according to the embodiment)
FIG. 37 is a diagram illustrating an example of retransmission of 4G packets by 5G in the communication system according to the embodiment. A 4G wireless frame 3710 shown in FIG. 37 is a 4G wireless frame of a 4G packet that is wirelessly transmitted from the first base station 110 to the terminal 130. 5G wireless frames 3721 to 3723,... Are 5G wireless frames of 5G packets that are wirelessly transmitted from the second base station 120 to the terminal 130.

For example, when an error occurs in the 4G radio frame 3710, in the communication system 100, the data of the 4G radio frame 3710 is retransmitted to the terminal 130 by the 5G radio frame 3731. In this case, the time required for the initial transmission (4G) and retransmission (5G) of data is 1.4 + α [ms] as described above.

As described above, 4G and 5G have the same retransmission period (for example, 8 TTI) and have different radio frame lengths, so that the time required for retransmission differs. The configuration in which the 4G and 5G retransmission cycles are the same has been described, but the 4G and 5G retransmission cycles may be different from each other. Even in this case, the time required for retransmission differs between 4G and 5G.

100 communication system 101 EPC
110 1st base station 111 aggregation part 120 2nd base station 130 terminal 310 5G packet 311 MAC header 312 MAC SDU
501, 601, 805 IP packet processor 502, 608 4G packet processor 503, 603, 803, 804, 2001, 2101 Radio frame processor 504, 604, 802 Radio unit 505, 605, 711 to 713, 801, 911, 911 912 Antenna 506, 607 Radio scheduler 507 Discard time information generation unit 602 5G packet processing unit 606,808 MAC layer 4G / 5G processing unit 609 Packet discard processing unit 700 Base station apparatus 721 to 723, 921, 922, 1811 RF module 730 selector 740, 930 DSP
750 NWP
806 Application processing unit 807 4G / 5G simultaneous use detection unit 900 terminal device 940 MPU
950 Flash memory 1301, 1401 RRC layer 4G / 5G processing unit 1601 WLAN packet processing unit 1701 4G / WLAN simultaneous use detection unit 1821 ASIC
2401 Packet extraction unit 2501 4G packet retransmission request unit 2502 4G packet retransmission processing unit 3301 5G retransmission unit 3710 4G radio frame 3721 to 3723, 3731 5G radio frame

Claims (17)

A terminal capable of receiving data addressed to itself using a wireless communication system according to the first communication method and a wireless communication system according to a second communication method different from the first communication method;
A first base station that wirelessly transmits first data included in the data to the terminal by the first communication method;
When the second data included in the data is wirelessly transmitted to the terminal by the second communication method, and a retransmission request for the first data wirelessly transmitted from the first base station to the terminal is received from the terminal A second base station that wirelessly transmits the first data to the terminal by the second communication method;
The terminal wirelessly transmits the retransmission request for the first data to the second base station when reception of the first data wirelessly transmitted from the first base station fails.
A communication system characterized by the above. 2. The communication system according to claim 1, wherein the second communication method is a communication method in which a delay associated with data retransmission is shorter than that of the first communication method. The communication system according to claim 1, wherein the second communication method is a communication method having a shorter radio frame length than the first communication method. The communication system according to any one of claims 1 to 3, wherein the terminal wirelessly transmits the retransmission request to the second base station using the second communication method. A processing unit for obtaining the first data and the second data from the data;
The first base station wirelessly transmits the first data acquired from the processing unit,
The second base station wirelessly transmits the second data acquired from the processing unit, holds the first data acquired from the processing unit, and receives a retransmission request for the first data from the terminal In this case, the held first data is wirelessly transmitted to the terminal.
The communication system according to any one of claims 1 to 4, wherein: The first base station generates information capable of specifying a discard time of the first data based on a time at which the first base station wirelessly transmits the first data to the terminal,
The second base station retains the first data and discards the retained first data at the discard time specified by the information generated by the first base station;
The communication system according to any one of claims 1 to 5, wherein: The first base station holds the first data wirelessly transmitted to the terminal,
When the second base station receives the retransmission request from the terminal, the second base station receives the first data held by the first base station from the first base station, and receives the received first data from the terminal. Wirelessly transmit to
The communication system according to any one of claims 1 to 4, wherein: When the terminal fails to receive the first data wirelessly transmitted from the first base station, the terminal detects and detects a free band in a predetermined band that can be used in the wireless communication system of the second communication method. 8. The communication system according to claim 1, wherein the retransmission request for the first data is wirelessly transmitted to the second base station using the free band. A terminal capable of receiving data addressed to itself using a wireless communication system according to a first communication method and a wireless communication system according to a second communication method different from the first communication method;
First data and second data included in the data, the first data wirelessly transmitted from the first base station by the first communication method, and the wireless transmission from the second base station by the second communication method A receiving unit for receiving the received second data;
A transmission unit that wirelessly transmits a retransmission request for the first data to the second base station when reception of the first data wirelessly transmitted from the first base station fails;
The receiving unit receives the first data wirelessly transmitted from the second base station by the second communication method,
A terminal characterized by that. The transmitter wirelessly transmits a PDU (Protocol Data Unit) including the first data, to which information indicating a retransmission request for the first data is added, to the second base station,
The terminal according to claim 9. A terminal included in the data includes a wireless communication system based on the first communication system and a wireless communication system based on a second communication system that is different from the first communication system. A transmitter that wirelessly transmits the second data of one data and second data to the terminal by the second communication method;
A receiving unit that receives a retransmission request from the terminal for the first data that is wirelessly transmitted from the other base station to the terminal by the first communication method and failed to be received at the terminal;
The transmission unit wirelessly transmits the first data to the terminal by the second communication method when the retransmission request is received by the reception unit.
A base station characterized by that. The receiving unit receives a PDU (Protocol Data Unit) including the first data, to which information indicating a retransmission request for the first data is attached, from the terminal.
The base station according to claim 11. A communication method by a terminal capable of receiving data addressed to the own station by simultaneously using a wireless communication system according to a first communication method and a wireless communication system according to a second communication method different from the first communication method,
First data and second data included in the data, the first data wirelessly transmitted from the first base station by the first communication method, and the wireless transmission from the second base station by the second communication method Received the second data,
When reception of the first data wirelessly transmitted from the first base station fails, a retransmission request for the first data is wirelessly transmitted to the second base station,
Receiving the first data wirelessly transmitted by the second communication method from the second base station;
A communication method characterized by the above. A terminal included in the data includes a wireless communication system based on the first communication system and a wireless communication system based on a second communication system that is different from the first communication system. Wirelessly transmitting the second data of one data and second data to the terminal by the second communication method;
Receiving a retransmission request from the terminal for the first data which is wirelessly transmitted to the terminal by the first communication method from another base station and failed to be received at the terminal;
When the retransmission request is received, the first data is wirelessly transmitted to the terminal by the second communication method;
A communication method characterized by the above. A first base station capable of a wireless communication system according to a first communication method;
A second base station capable of a wireless communication system according to a second communication scheme different from the first communication scheme;
A terminal capable of transmitting data from a local station using the wireless communication system according to the first communication method and the wireless communication system according to the second communication method at the same time, wherein the first data included in the data is The first communication system wirelessly transmits to the first base station, the second data included in the data is wirelessly transmitted to the second base station by the second communication system, and the wirelessly transmitted to the first base station A terminal that wirelessly transmits the first data to the second base station by the second communication method when a retransmission request for the first data is received from the first base station;
A communication system comprising: A terminal capable of receiving data addressed to the local station simultaneously using a radio communication system according to a first communication scheme and a radio communication system according to a second communication scheme different from the first communication scheme;
A transmitter that wirelessly transmits the first data included in the data to the first base station by the first communication method, and wirelessly transmits the second data included in the data to the second base station by the second communication method; ,
A receiver for receiving a retransmission request from the first base station for the first data wirelessly transmitted to the first base station by the transmitter;
The transmission unit wirelessly transmits the first data to the second base station by the second communication method when the retransmission request is received by the reception unit.
A terminal characterized by that. A communication method by a terminal capable of receiving data addressed to the own station by simultaneously using a wireless communication system according to a first communication method and a wireless communication system according to a second communication method different from the first communication method,
The first data included in the data is wirelessly transmitted to the first base station by the first communication method, the second data included in the data is wirelessly transmitted to the second base station by the second communication method,
Receiving a retransmission request from the first base station for the first data wirelessly transmitted to the first base station;
When the retransmission request is received, the first data is wirelessly transmitted to the second base station by the second communication method;
A communication method characterized by the above.

Images