Relay device, communication system, and relay method

Abstract

A relay device (100) according to the present disclosure is provided with: a communication unit (101) for transmitting, to a reception-side communication device (300) via a network, a downlink packet received via the network from a transmission-side communication device (200), and transmitting, to the transmission-side communication device (200) via the network, an ACK packet for the downlink packet, received via the network from the reception-side communication device (300); and, a transmission timing control unit (102) for controlling, so that the received ACK packet is transmitted at a specific interval, the transmission timing of the ACK packet by the communication unit (101).

Description

Technical Field

[0001] The present disclosure relates to a relay device, a communication system, and a relay method.

Background Art

[0002] In TCP (Transmission Control Protocol), network congestion control is performed by a method called congestion window control (for example, Patent Document 1).

[0003] In the congestion window control method, the transmitting communication device changes the size of the congestion window according to the congestion state of the network, and limits the amount of data (TCP segment) flowing into the network according to the size of the congestion window.

[0004] Specifically, the transmitting communication device determines the congestion state of the network according to the RTT (Round Trip Time), which is the time from when data is sent into the network until an ACK (acknowledge) packet for that data is returned from the other party. When the transmitting communication device determines that the network is not congested according to the RTT, it increases the size of the congestion window. On the other hand, when the transmitting communication device determines that the network is congested according to the RTT, it decreases the size of the congestion window. Thereby, the transmitting communication device can send a large amount of data into the network while avoiding network congestion.

Prior Art Documents

Patent Documents

[0005]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0006] However, the inventors have found that in the convergence window control method, for example, when the receiving-side communication device uses the TDD (Time Division Duplex) method, the transmitting-side communication device may experience wasted time during which it does not transmit data even though it could, due to the growth of the convergence window stopping (i.e., not increasing in size).

[0007] Therefore, an object of the present disclosure is to provide a relay device, a communication system, and a relay method capable of reducing wasted time in a transmitting-side communication device in view of the above-described problems.

Means for Solving the Problems

[0008] A relay device according to one aspect includes: a communication unit that transmits a downstream packet received from a transmitting-side communication device via a network to a receiving-side communication device via the network, and transmits an ACK (Acknowledge) packet for the downstream packet, received from the receiving-side communication device via the network, to the transmitting-side communication device via the network; a transmission timing control unit that controls the transmission timing of the ACK packet by the communication unit so as to transmit the received ACK packet at a specific interval.

[0009] A communication system according to one aspect includes: a first communication unit that transmits a downstream packet received from a transmitting-side communication device via a network to a receiving-side communication device via the network, and transmits an ACK (Acknowledge) packet for the downstream packet, received from the receiving-side communication device via the network, to the transmitting-side communication device via the network; a transmission timing control unit that controls the transmission timing of the ACK packet by the first communication unit so as to transmit the received ACK packet at a specific interval.

[0010] A relay method according to one aspect is a relay method by a relay device, including a communication step of transmitting a downstream packet received from a transmitting-side communication device via a network to a receiving-side communication device via the network, and transmitting, via the network, an ACK (Acknowledge) packet for the downstream packet received from the receiving-side communication device via the network to the transmitting-side communication device; and a transmission timing control step of controlling the transmission timing of the ACK packet in the communication step so as to transmit the received ACK packet at a specific interval.

Advantages of the Invention

[0011] According to the above aspect, an effect is obtained in that a relay device, a communication system, and a relay method capable of reducing wasted time in a transmitting-side communication device can be provided.

Brief Description of the Drawings

[0012]

Figure 1

Figure 2

Figure 3

Figure 4

Figure 5

Figure 6

Figure 7

Figure 8

Figure 9

Figure 10

Modes for Carrying Out the Invention

[0013] Before explaining this embodiment, problems in the congestion window control method discovered by the inventors will be described with reference to FIG. 1. In the example of FIG. 1, a Web server 20 transmits data to a UE (User Equipment) 40 via a proxy server 90 and a base station 30. That is, the Web server 20 serves as a transmitting-side communication device, the base station 30 serves as a receiving-side communication device, and the proxy server 90 serves as a relay device. Also, the TDD method is used for communication between the base station 30 and the UE 40. Further, "D" in the figure indicates a downlink slot which is a time slot allocated to the downlink from the base station 30 to the UE 40, and "U" in the figure indicates an uplink slot which is a time slot allocated to the uplink from the UE 40 to the base station 30.

[0014] At time t1, the Web server 20 transmits a downlink packet with a data amount corresponding to the size of the congestion window at that time to the proxy server 90, and the proxy server 90 transmits the downlink packet to the base station 30. Since a downlink slot is allocated when the base station 30 receives a downlink packet from the proxy server 90, the base station 30 transmits the downlink packet received from the proxy server 90 to the UE 40.

[0015] When the UE 40 receives a downlink packet, it transmits an ACK packet for that downlink packet. However, at the time when the UE 40 receives a downlink packet from the base station 30, a downlink slot is already allocated. Therefore, the UE 40 is made to wait until the transmission opportunity at time t3 when an uplink slot is allocated to transmit the ACK packet. Then, at time t3, the UE 40 transmits a plurality of ACK packets to the base station 30 in a batch, and the base station 30 transmits the plurality of ACK packets to the proxy server 90 in a batch.

[0016] Here, in TCP, as described above, network congestion control is performed. Similarly, network congestion control is also performed in QUIC. QUIC is a protocol located above UDP (User Datagram Protocol).

[0017] Generally, in the proxy server 90, by using techniques such as TCP splitting, TCP can be terminated, and intervention in congestion control can be achieved on a relay device such as the proxy server 90. On the other hand, in QUIC, encryption is performed by TLS (Transport Layer Security) on top of UDP, and due to the influence of performing congestion control in the upper layer, a relay device such as the proxy server 90 cannot directly participate in the congestion control of QUIC. Therefore, regarding QUIC, the proxy server 90 will transfer the ACK packets received from the base station 30 directly to the web server 20.

[0018] When the web server 20 receives an ACK packet from the base station 30, it resumes the transmission of downlink packets. In this way, in the web server 20, to transmit the next downlink packet, it has to wait until it receives an ACK packet. As a result, in the web server 20, the time from time t2 when the transmission of the downlink packet is completed to time t3 when the ACK packet is received becomes wasted time during which the downlink packet could have been transmitted but is not.

[0019] Further, the Web server 20 determines whether the network is congested according to the RTT from the transmission of the downstream packet to the reception of the ACK packet. At this time, for example, assume that the RTT is as shown in FIG. 2. In FIG. 2, the vertical axis represents the RTT, and the horizontal axis represents the packet number of the downstream packet. Here, the Web server 20 increments the packet number each time it transmits a downstream packet. Therefore, the downstream packet with the largest packet number is the most recently transmitted downstream packet. In the example of FIG. 2, the RTT is serrated. This is because the UE 40 transmits a plurality of ACK packets for a plurality of downstream packets received in a plurality of downstream slots in one upstream slot, and the base station 30 and the proxy server 90 also transmit the plurality of ACK packets together.

[0020] When the RTT is serrated as shown in FIG. 2, the Web server 20 determines that the network is congested. Therefore, in the Web server 20, the growth of the congestion window stops (the size does not increase). Therefore, when the Web server 20 transmits the next downstream packet, it can only transmit a downstream packet with a data amount corresponding to the size of the congestion window in the state where the growth has stopped. As a result, in the Web server 20, wasted time occurs even after the next downstream packet is transmitted.

[0021] Hereinafter, embodiments of the present disclosure will be described with reference to the drawings. Note that the following description and drawings are appropriately omitted and simplified for clarity of explanation. Also, in the following drawings, the same elements are denoted by the same reference numerals, and redundant explanations are omitted as necessary. In addition, the specific numerical values shown below are merely examples for facilitating the understanding of the present disclosure and are not limited thereto.

[0022] <Embodiment 1> First, with reference to FIG. 3, a configuration example of the communication system 1 according to the first embodiment will be described. As shown in FIG. 3, the communication system 1 according to Embodiment 1 includes a relay device 100, a transmission-side communication device 200, and a reception-side communication device 300. The relay device 100 includes a communication unit (first communication unit) 101 and a transmission timing control unit 102. Note that the relay device 100 is, for example, a proxy server, the transmission-side communication device 200 is, for example, a web server, and the reception-side communication device 300 is, for example, a base station.

[0023] The communication unit 101 receives a downstream packet from the transmission-side communication device 200 via the network and transmits the downstream packet to the reception-side communication device 300 via the network. The communication unit 101 also receives an ACK packet for the downstream packet from the reception-side communication device 300 via the network and transmits the ACK packet to the transmission-side communication device 200 via the network.

[0024] Note that the network according to Embodiment 1 generally refers to a communication network including a communication network (regardless of wired or wireless) between the transmission-side communication device 200 and the relay device 100 and a communication network (regardless of wired or wireless) between the relay device 100 and the reception-side communication device 300. However, when the reception-side communication device 300 is a base station, the network refers to a communication network including the above communication network and a wireless communication network between the reception-side communication device 300 and a terminal such as a UE.

[0025] The transmission timing control unit 102 controls the transmission timing of the ACK packet by the communication unit 101 so as to transmit the ACK packet received from the reception-side communication device 300 to the transmission-side communication device 200 at specific intervals. In response to this, the communication unit 101 transmits the ACK packet to the transmission-side communication device 200 at the transmission timing controlled by the transmission timing control unit 102.

[0026] Note that the transmitting-side communication device 200 may be implemented by any communication device as long as it has a function of transmitting a downlink packet to the relay device 100 and receiving an ACK packet for the downlink packet from the relay device 100. Further, the receiving-side communication device 300 may be implemented by any communication device as long as it has a function of receiving a downlink packet from the relay device 100 and transmitting an ACK packet for the downlink packet to the relay device 100, or a function of receiving a downlink packet from the relay device 100 and forwarding it to another device (if the receiving-side communication device 300 is a base station, the other device is a terminal such as a UE) and transmitting an ACK packet for the downlink packet received from the other device to the relay device 100. Therefore, the detailed configurations of the transmitting-side communication device 200 and the receiving-side communication device 300 will not be described.

[0027] Subsequently, with reference to FIG. 4, an example of a schematic operation flow of the relay device 100 according to the first embodiment will be described. As shown in FIG. 4, the communication unit 101 transmits a downlink packet received from the transmitting-side communication device 200 via the network to the receiving-side communication device 300 via the network, and also receives an ACK packet for the downlink packet from the receiving-side communication device 300 via the network (step S11). Thereafter, the transmission timing control unit 102 controls the transmission timing of the ACK packet by the communication unit 101 so as to transmit the ACK packet received from the receiving-side communication device 300 to the transmitting-side communication device 200 at specific intervals (step S12).

[0028] As described above, according to the first embodiment, the relay device 100 controls the transmission timing of the ACK packet by the communication unit 101 so as to transmit the ACK packet received from the receiving-side communication device 300 to the transmitting-side communication device 200 at specific intervals. As a result, in the transmitting-side communication device 200, the RTT does not become sawtooth-like as shown in FIG. 2 and does not fluctuate greatly, so it is determined that the network is not congested, and the congestion window can be grown (the size can be increased). As a result, in the transmitting-side communication device 200, since the data amount of the downlink packets flowing through the network increases, the wasted time can be reduced.

[0029] Note that the communication unit 101 may receive a plurality of ACK packets from the receiving-side communication device 300, and the transmission timing control unit 102 may control the transmission timing of the plurality of ACK packets by the communication unit 101 based on the interval of network scheduling and the number of the plurality of ACK packets received from the receiving-side communication device 300. For example, when the receiving-side communication device 300 is a base station that communicates with a terminal in the TDD mode, the interval of network scheduling may be the interval of uplink slots allocated to the uplink. Note that the interval of network scheduling may be calculated by any component in the relay device 100 or received from an external device.

[0030] Also, the communication unit 101 may receive a plurality of ACK packets from the receiving-side communication device 300 within a predetermined time corresponding to a predetermined slot, and the transmission timing control unit 102 may control the transmission timing of the plurality of ACK packets by the communication unit 101 based on the interval of network scheduling and the number of the plurality of ACK packets received within the predetermined time from the receiving-side communication device 300. For example, when the receiving-side communication device 300 is a base station that communicates with a terminal in the TDD mode, the predetermined slot may be an uplink slot.

[0031] Further, the transmission timing control unit 102 may control the transmission timing of a plurality of ACK packets by the communication unit 101 so that all the plurality of ACK packets are transmitted within the scheduling interval of the network and the plurality of ACK packets are transmitted at regular intervals.

[0032] Further, it may include a second communication unit that transmits a downstream packet to the communication unit 101 in the relay device 100 and receives an ACK packet for the downstream packet from the communication unit 101 in the relay device 100, and a transmission rate control unit that acquires the state of the network and controls the transmission bit rate of the downstream packet by the second communication unit based on the acquired network state. In this case, the second communication unit may be provided in the transmission-side communication device 200. Further, the transmission rate control unit may acquire the situation of increase and decrease of RTT in the network as the state of the network.

[0033] <Embodiment 2> Subsequently, with reference to FIG. 5, a configuration example of the communication system 2 according to the second embodiment will be described. The second embodiment corresponds to a more specific embodiment of the first embodiment described above.

[0034] As shown in FIG. 5, the communication system 2 according to the second embodiment includes a proxy server 10, a Web server 20, a base station 30, and a UE 40. Note that the TDD method is used for communication between the base station 30 and the UE 40. Further, the proxy server 10 is an example of a relay device, the Web server 20 is an example of a transmission-side communication device, and the base station 30 is an example of a reception-side communication device.

[0035] The proxy server 10 includes a communication unit (first communication unit) 11 and a transmission timing control unit 12. The communication unit 11 transmits the downstream packet received from the Web server 20 to the UE 40 via the base station 30, and also transmits the ACK packet for the downstream packet received from the UE 40 via the base station 30 to the Web server 20.

[0036] Note that the network according to Embodiment 2 refers to a communication network including a communication network (regardless of wired or wireless) between the Web server 20 and the proxy server 10, a communication network (regardless of wired or wireless) between the proxy server 10 and the base station 30, and a wireless communication network between the base station 30 and the UE 40. Note that the wireless communication network between the base station 30 and the UE 40 may be LTE (Long Term Evolution), 4G (Generation), 5G, or local 5G, etc.

[0037] The transmission timing control unit 12 controls the transmission timing of the ACK packet by the communication unit 11 so as to transmit the ACK packet received from the base station 30 to the Web server 20 at a specific interval. In response to this, the communication unit 11 transmits the ACK packet to the Web server 20 at the transmission timing controlled by the transmission timing control unit 12.

[0038] For example, as shown in FIG. 6, the transmission timing control unit 12 controls the transmission timing of the ACK packet so as to transmit the ACK packet at regular intervals. As a result, in the Web server 20, since the RTT does not fluctuate greatly, the congestion window can be grown (the size can be increased).

[0039] Subsequently, the operation of the transmission timing control unit 12 will be described in detail. As described above, the TDD system is used for the communication between the base station 30 and the UE 40. Therefore, even if the UE 40 receives a downlink packet in a downlink slot, it cannot immediately transmit an ACK packet for the downlink packet and waits until the next uplink slot which is the next transmission opportunity. Therefore, the UE 40 transmits a plurality of ACK packets for a plurality of downlink packets transmitted by the base station 30 in a divided manner in a plurality of downlink slots in one uplink slot. Also, the base station 30 also transmits the plurality of ACK packets to the proxy server 10 in a lump.

[0040] Therefore, the communication unit 11 will receive a plurality of ACK packets from the base station 30 in a time period corresponding to the uplink slot in a batch. Therefore, the transmission timing control unit 12 controls the transmission timing of the ACK packets so that all of the plurality of ACK packets can be transmitted within the period until the next uplink slot and so that the plurality of ACK packets can be transmitted at regular intervals.

[0041] Specifically, the transmission timing control unit 12 sets the interval of network scheduling, that is, the interval of the uplink slot, as δ. Then, the transmission timing control unit 12 sets the transmission timing a of the i-th ACK packet as shown in the following Equation 1. i to set.

Equation

[0042] Note that the Web server 20 may be implemented by any server as long as it has a function of transmitting a downlink packet to the proxy server 10 and receiving an ACK packet for the downlink packet from the proxy server 10. Further, the base station 30 may be implemented by any base station as long as it has a function of communicating with the UE 40 in the TDD mode, receiving a downlink packet from the proxy server 10 and forwarding it to the UE 40, and receiving an ACK packet for the downlink packet from the UE 40 and transmitting it to the proxy server 10. Further, the UE 40 may be implemented by any terminal as long as it has a function of communicating with the base station 30 in the TDD mode, receiving a downlink packet from the base station 30, and transmitting an ACK packet for the downlink packet to the base station 30. Therefore, the detailed configurations of the Web server 20, the base station 30, and the UE 40 are omitted from the description.

[0043] Subsequently, with reference to FIG. 7, an example of a schematic operation flow of the proxy server 10 according to Embodiment 2 will be described. As shown in FIG. 7, the communication unit 11 transmits the downstream packet received from the Web server 20 to the base station 30, and also receives an ACK packet for the downstream packet from the base station 30 (step S21).

[0044] Thereafter, the transmission timing control unit 12 controls the transmission timing of the ACK packet by the communication unit 11 so as to transmit the ACK packet received from the base station 30 to the Web server 20 at a specific interval (step S22).

[0045] As described above, according to the second embodiment, the proxy server 10 controls the transmission timing of the ACK packet by the communication unit 11 so as to transmit the ACK packet received from the base station 30 to the Web server 20 at a specific interval. As a result, in the Web server 20, the RTT does not become serrated as shown in FIG. 2 and does not fluctuate greatly, so it is determined that the network is not congested, and the congestion window can be grown (the size can be increased). As a result, in the Web server 20, the amount of data of the downstream packet flowing through the network increases, so that the wasted time can be reduced.

[0046] <Embodiment 3> Subsequently, with reference to FIG. 8, a configuration example of the communication system 3 according to the third embodiment will be described. As shown in FIG. 8, the communication system 3 according to the third embodiment is different from the second embodiment described above in that the Web server 20 is replaced with a Web server 20A.

[0047] The Web server 20A includes a communication unit (second communication unit) 21 and a transmission rate control unit 22. The communication unit 21 transmits a downstream packet to the proxy server 10 and receives an ACK packet for the downstream packet from the proxy server 10.

[0048] The transmission rate control unit 22 acquires the state of the network and controls the transmission bit rate of the downstream packets by the communication unit 21 based on the acquired network state. For example, the transmission rate control unit 22 acquires, as the state of the network, the situation of increase or decrease of the RTT in the network. In response to this, the communication unit 21 transmits the downstream packets to the proxy server 10 at the transmission bit rate controlled by the transmission rate control unit 22.

[0049] Subsequently, the operation of the transmission rate control unit 22 will be described in detail. The transmission rate control unit 22 acquires, as the state of the network, the situation of increase or decrease of the RTT in the network. Here, it is assumed that the situation of increase or decrease of the RTT indicates either increase, stability, or decrease.

[0050] For example, in a situation where the RTT is increasing, the transmission rate control unit 22 decreases the transmission bit rate Rate(t) [bps] of the ACK packet. For example, the transmission rate control unit 22 sets Rate(t) as shown in the following formula 2.

Equation

[0051] On the other hand, in a situation where the RTT is stable or decreasing, the transmission rate control unit 22 increases the transmission bit rate Rate(t) [bps] of the ACK packet. For example, the transmission rate control unit 22 sets Rate(t) as shown in the following formula 3.

Equation

[0052] Subsequently, with reference to FIG. 9, an example of the schematic operation flow of the Web server 20A according to the third embodiment will be described. As shown in FIG. 9, first, the transmission rate control unit 22 acquires the state of the network (step S31). Subsequently, the transmission rate control unit 22 controls the transmission bit rate of the downstream packet by the communication unit 21 based on the acquired network state (step S32).

[0053] Note that, in the third embodiment, the configurations and operations other than the Web server 20A are the same as those in the second embodiment described above. Therefore, the descriptions of the configurations and operations other than the Web server 20A are omitted.

[0054] As described above, according to the third embodiment, the Web server 20A can increase the data amount of the ACK packets flowing through the network by growing the congestion window. However, if the data amount exceeds the allowable amount that can be transmitted in the downstream slot existing between two upstream slots, a queuing delay will occur. Therefore, the Web server 20A acquires the state of the network and controls the transmission bit rate of the downstream packet by the communication unit 21 based on the network state. Thereby, according to the network state, the data amount of the downstream packet flowing through the network can be controlled so that no queuing delay occurs. As a result, in the Web server 20, the throughput can be improved. The effects other than those described above in the third embodiment are the same as those in the second embodiment described above.

[0055] <Hardware Configuration of Relay Device, Proxy Server, and Web Server According to Embodiment> Subsequently, with reference to FIG. 10, a hardware configuration example of a computer 50 that realizes the relay device 100 according to the first embodiment described above, the proxy server 10 according to the second embodiment described above, and the Web server 20A according to the third embodiment described above will be described.

[0056] As shown in FIG. 10, the computer 50 includes a processor 51, a memory 52, a storage 53, an input / output interface (input / output I / F) 54, a communication interface (communication I / F) 55, and the like. The processor 51, the memory 52, the storage 53, the input / output interface 54, and the communication interface 55 are connected by a data transmission path for transmitting and receiving data to and from each other.

[0057] The processor 51 is an arithmetic processing device such as a CPU (Central Processing Unit) or a GPU (Graphics Processing Unit), for example. The memory 52 is a memory such as a RAM (Random Access Memory) or a ROM (Read Only Memory), for example. The storage 53 is a storage device such as an HDD (Hard Disk Drive), an SSD (Solid State Drive), or a memory card, for example. Also, the storage 53 may be a memory such as a RAM or a ROM.

[0058] The storage 53 stores a program for realizing the functions of the components included in the relay device 100, the proxy server 10, or the Web server 20A. The processor 51 realizes the functions of the components included in the relay device 100, the proxy server 10, or the Web server 20A by executing these programs. Here, when executing the above programs, the processor 51 may read these programs onto the memory 52 and then execute them, or may execute them without reading them onto the memory 52. Also, the memory 52 and the storage 53 also play a role in realizing the storage functions included in the relay device 100, the proxy server 10, or the Web server 20A.

[0059] In addition, when the above-described program is loaded into a computer, it includes a set of instructions (or software code) for causing the computer to perform one or more functions in the relay device 100, the proxy server 10, or the Web server 20A described in the above-described embodiments. The program may be stored in a non-transitory computer-readable medium or a tangible storage medium. By way of example and not limitation, the computer-readable medium or tangible storage medium includes RAM, ROM, flash memory, SSD, or other memory technologies, compact disc (CD)-ROM, digital versatile disk (DVD), Blu-ray (registered trademark) disc, or other optical disc storage, magnetic cassette, magnetic tape, magnetic disk storage, or other magnetic storage devices. The program may also be transmitted on a transient computer-readable medium or a communication medium. By way of example and not limitation, the transient computer-readable medium or communication medium includes electrical, optical, acoustic, or other forms of propagated signals.

[0060] The input / output interface 54 is connected to a display device 541, an input device 542, a sound output device 543, and the like. The display device 541 is a device that displays a screen corresponding to the drawing data processed by the processor 51, such as an LCD (Liquid Crystal Display), a CRT (Cathode Ray Tube) display, or a monitor. The input device 542 is a device that receives the operation input of the operator, such as a keyboard, a mouse, and a touch sensor. The display device 541 and the input device 542 may be integrated and realized as a touch panel. The sound output device 543 is a device that acoustically outputs a sound corresponding to the acoustic data processed by the processor 51, such as a speaker.

[0061] The communication interface 55 transmits and receives data to and from an external device. For example, the communication interface 55 communicates with an external device via a wired communication path or a wireless communication path.

[0062] The present disclosure has been described with reference to the embodiments above, but the present disclosure is not limited to the above-described embodiments. Various modifications that can be understood by those skilled in the art can be made to the configuration and details of the present disclosure within the scope of the present disclosure.

[0063] Also, some or all of the above-described embodiments can be described as follows in the appended claims, but are not limited thereto. (Appended Claim 1) A communication unit that transmits a downstream packet received from a transmission-side communication device via a network to a reception-side communication device via the network, and transmits an ACK (Acknowledge) packet for the downstream packet received from the reception-side communication device via the network to the transmission-side communication device via the network; A transmission timing control unit that controls the transmission timing of the ACK packet by the communication unit so as to transmit the received ACK packet at a specific interval. Relay device. (Appended Claim 2) The communication unit receives a plurality of ACK packets from the reception-side communication device, The transmission timing control unit controls the transmission timing of the plurality of ACK packets by the communication unit based on the scheduling interval of the network and the number of the plurality of ACK packets received from the reception-side communication device. The relay device according to Appended Claim 1. (Appended Claim 3) The communication unit receives a plurality of ACK packets from the reception-side communication device within a predetermined time corresponding to a predetermined slot, The transmission timing control unit controls the transmission timing of the plurality of ACK packets by the communication unit based on the scheduling interval of the network and the number of the plurality of ACK packets received within the predetermined time from the reception-side communication device. The relay device according to Appended Claim 1. (Appended Claim 4) The transmission timing control unit controls the transmission timing of a plurality of ACK packets by the communication unit so that all of the plurality of ACK packets are transmitted within the scheduling interval of the network and the plurality of ACK packets are transmitted at regular intervals. The relay device according to appended note 2 or 3. (Appended note 5) A first communication unit that transmits a downstream packet received from a transmission-side communication device via a network to a reception-side communication device via the network, and transmits an ACK (Acknowledge) packet for the downstream packet, received from the reception-side communication device via the network, to the transmission-side communication device via the network; A transmission timing control unit that controls the transmission timing of the ACK packet by the first communication unit so that the received ACK packet is transmitted at a specific interval. Communication system. (Appended note 6) The first communication unit receives a plurality of ACK packets from the reception-side communication device. The transmission timing control unit controls the transmission timing of a plurality of ACK packets by the first communication unit based on the scheduling interval of the network and the number of the plurality of ACK packets received from the reception-side communication device. The communication system according to appended note 5. (Appended note 7) The first communication unit receives a plurality of ACK packets from the reception-side communication device within a predetermined time corresponding to a predetermined slot. The transmission timing control unit controls the transmission timing of a plurality of ACK packets by the first communication unit based on the scheduling interval of the network and the number of the plurality of ACK packets received from the reception-side communication device within the predetermined time. The communication system according to appended note 5. (Appended note 8) The transmission timing control unit controls the transmission timing of a plurality of ACK packets by the first communication unit so that all of the plurality of ACK packets are transmitted within the scheduling interval of the network and the plurality of ACK packets are transmitted at regular intervals. The communication system according to Supplementary Note 6 or 7. (Supplementary Note 9) A second communication unit provided in the transmission-side communication device, which transmits a downstream packet to the first communication unit via the network and receives an ACK packet for the downstream packet from the first communication unit via the network. A transmission rate control unit that acquires the state of the network and controls the transmission bit rate of the downstream packet by the second communication unit based on the acquired state of the network. The communication system according to any one of Supplementary Notes 5 to 8. (Supplementary Note 10) The transmission rate control unit acquires, as the state of the network, the situation of increase or decrease in RTT (Round Trip Time), which is the time from when the transmission-side communication device transmits a downstream packet until the transmission-side communication device receives an ACK packet for the downstream packet. The communication system according to Supplementary Note 9. (Supplementary Note 11) A relay method by a relay device, A communication step of transmitting a downstream packet received from a transmission-side communication device via a network to a reception-side communication device via the network, and transmitting an ACK (Acknowledge) packet for the downstream packet received from the reception-side communication device via the network to the transmission-side communication device via the network, A transmission timing control step of controlling the transmission timing of the ACK packet in the communication step so that the received ACK packet is transmitted at a specific interval. Relay method. (Supplementary Note 12) In the communication step, a plurality of ACK packets are received from the reception-side communication device. In the transmission timing control step, based on the scheduling interval of the network and the number of a plurality of ACK packets received from the receiving-side communication device, the transmission timing of the plurality of ACK packets in the communication step is controlled. The relay method according to Supplementary Note 11. (Supplementary Note 13) In the communication step, a plurality of ACK packets are received from the receiving-side communication device within a predetermined time corresponding to a predetermined slot. In the transmission timing control step, based on the scheduling interval of the network and the number of a plurality of ACK packets received from the receiving-side communication device within the predetermined time, the transmission timing of the plurality of ACK packets in the communication step is controlled. The relay method according to Supplementary Note 11. (Supplementary Note 14) In the transmission timing control step, the transmission timing of the plurality of ACK packets in the communication step is controlled such that all of the plurality of ACK packets are transmitted within the scheduling interval of the network and the plurality of ACK packets are transmitted at regular intervals. The relay method according to Supplementary Note 12 or 13.

Explanation of Signs

[0064] 1, 2, 3 Communication system 100 Relay device 101 Communication unit 102 Transmission timing control unit 200 Transmitting-side communication device 300 Receiving-side communication device 10 Proxy server 11 Communication unit 12 Transmission timing control unit 20, 20A Web server 21 Communication unit 22 Transmission rate control unit 30 Base station 40 UE 50 Computer 51 Processor 52 Memory 53 Storage 54 Input / Output Interface 541 Display Device 542 Input Device 543 Audio Output Device 55 Communication Interface

Claims

1. A communication unit that transmits a downstream packet received from a transmitting-side communication device via a network to a receiving-side communication device via the network, and transmits an ACK (Acknowledge) packet for the downstream packet received from the receiving-side communication device via the network to the transmitting-side communication device via the network; A transmission timing control unit that controls the transmission timing of the ACK packet by the communication unit so as to transmit the received ACK packet at a specific interval; The communication unit receives a plurality of ACK packets from the receiving-side communication device; The transmission timing control unit controls the transmission timing of a plurality of ACK packets by the communication unit based on the scheduling interval of the network and the number of a plurality of ACK packets received from the receiving-side communication device; A relay device.

2. The receiving-side communication device is a base station that communicates with a terminal in a TDD (Time Division Duplex) mode, The scheduling interval of the network is the interval of uplink slots allocated to the uplink; The relay device according to Claim 1.

3. The transmission timing control unit controls the transmission timing of a plurality of ACK packets by the communication unit so that all of the plurality of ACK packets are transmitted within the scheduling interval of the network and the plurality of ACK packets are transmitted at a constant interval; The relay device according to Claim 1 or 2.

4. A first communication unit that transmits a downstream packet received from a transmitting-side communication device via a network to a receiving-side communication device via the network, and transmits an ACK (Acknowledge) packet for the downstream packet received from the receiving-side communication device via the network to the transmitting-side communication device via the network; A transmission timing control unit that controls the transmission timing of the ACK packet by the first communication unit so as to transmit the received ACK packet at a specific interval; The first communication unit receives a plurality of ACK packets from the receiving-side communication device; The transmission timing control unit controls the transmission timing of a plurality of ACK packets by the first communication unit based on the scheduling interval of the network and the number of a plurality of ACK packets received from the receiving-side communication device; Communication system.

5. The receiving-side communication device is a base station that communicates with a terminal in a TDD (Time Division Duplex) mode, wherein the scheduling interval of the network is the interval of uplink slots allocated to the uplink. The communication system according to claim 4.

6. The transmission timing control unit controls the transmission timing of a plurality of ACK packets by the first communication unit such that all of the plurality of ACK packets are transmitted within the scheduling interval of the network and the plurality of ACK packets are transmitted at regular intervals. The communication system according to claim 4 or 5.

7. A second communication unit provided in the transmitting-side communication device, which transmits a downlink packet to the first communication unit via the network and receives an ACK packet for the downlink packet from the first communication unit via the network; and a transmission rate control unit that acquires the state of the network and controls the transmission bit rate of the downlink packet by the second communication unit based on the acquired state of the network. The communication system according to any one of claims 4 to 6.

8. The transmission rate control unit acquires, as the state of the network, the change situation of the RTT (Round Trip Time), which is the time from when the transmitting-side communication device transmits a downlink packet until the transmitting-side communication device receives an ACK packet for the downlink packet. The communication system according to claim 7.

9. A relay method by a relay device, comprising: a communication step of transmitting a downlink packet received from a transmitting-side communication device via a network to a receiving-side communication device via the network, and transmitting an ACK (Acknowledge) packet for the downlink packet received from the receiving-side communication device via the network to the transmitting-side communication device via the network; and a transmission timing control step of controlling the transmission timing of the ACK packet in the communication step so as to transmit the received ACK packet at a specific interval. In the communication step, a plurality of ACK packets are received from the receiving-side communication device. In the transmission timing control step, based on the scheduling interval of the network and the number of a plurality of ACK packets received from the receiving-side communication device, the transmission timing of the plurality of ACK packets in the communication step is controlled. Relay method.

10. The receiving-side communication device is a base station that communicates with a terminal in a TDD (Time Division Duplex) mode. The scheduling interval of the network is the interval of uplink slots allocated to the uplink. The relay method according to claim 9.

11. In the transmission timing control step, the transmission timing of the plurality of ACK packets in the communication step is controlled such that all of the plurality of ACK packets are transmitted within the scheduling interval of the network and the plurality of ACK packets are transmitted at regular intervals. The relay method according to claim 9 or 10.

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