Communication device, communication system, and communication method

Abstract

A communication device (100) according to the present disclosure comprises: a communication unit (101) for transmitting a downstream packet via a network and receiving an ACK packet in response to the downstream packet via a network; an acquisition unit (102) for acquiring an RTT regarding the downstream packet already transmitted by the communication unit (101), the RTT being the time until the ACK packet is received by the communication unit (101) after the downstream packet is transmitted by the communication unit (101), and the transmission time for the downstream packet already transmitted by the communication unit (101); and a transmission timing control unit (103) for controlling the timing at which a downstream packet is transmitted by the communication unit (101), the timing being controlled on the basis of the RTT regarding the downstream packet already transmitted by the communication unit (101) and the time that the downstream packet is transmitted by the communication unit (101).

Description

Technical Field

[0001] The present disclosure relates to a communication device, a communication system, and a communication 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 through 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 magnitude of the RTT (Round Trip Time), which is the time from when data is sent through the network until an ACK (acknowledge) packet for that data is returned from the other party. When the RTT is small, the transmitting communication device determines that the network is not congested and increases the size of the congestion window. On the other hand, when the RTT is large, the transmitting communication device determines that the network is congested and reduces the size of the congestion window. Thereby, the transmitting communication device can send a large amount of data through 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 congestion 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 congestion window stopping (not increasing in size).

[0007] Therefore, an object of the present disclosure is to provide a communication device, a communication system, and a communication 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 communication device according to one aspect includes: a communication unit that transmits a downstream packet via a network and receives an ACK (Acknowledge) packet for the downstream packet via the network; an acquisition unit that acquires an RTT (Round Trip Time) for a downstream packet already transmitted by the communication unit, which is the time from when the communication unit transmits the downstream packet until the communication unit receives the ACK packet, and the transmission time of the downstream packet already transmitted by the communication unit; a transmission timing control unit that controls the transmission timing of the downstream packet by the communication unit based on the RTT for the downstream packet already transmitted by the communication unit and the transmission time of the downstream packet already transmitted by the communication unit.

[0009] A communication system according to one aspect includes: a communication unit that transmits a downstream packet to a receiving-side communication device via a network and receives an ACK (Acknowledge) packet for the downstream packet from the receiving-side communication device via the network; An acquisition unit that acquires an RTT (Round Trip Time) for a downstream packet already transmitted by the communication unit, which is the time from when the communication unit transmits the downstream packet until it receives the ACK packet, and the transmission time of the downstream packet already transmitted by the communication unit. A transmission timing control unit that controls the transmission timing of downstream packets by the communication unit based on the RTT for the downstream packets already transmitted by the communication unit and the transmission times of the downstream packets already transmitted by the communication unit.

[0010] A communication method according to one aspect is A communication method by a communication device, A communication step of transmitting a downstream packet via a network and receiving an ACK (Acknowledge) packet for the downstream packet via the network, An acquisition step of acquiring an RTT (Round Trip Time) for a downstream packet already transmitted in the communication step, which is the time from when the downstream packet is transmitted in the communication step until the ACK packet is received in the communication step, and the transmission time of the downstream packet already transmitted in the communication step, A transmission timing control step of controlling the transmission timing of downstream packets in the communication step based on the RTT for the downstream packets already transmitted in the communication step and the transmission times of the downstream packets already transmitted in the communication step.

Advantages of the Invention

[0011] According to the above aspect, there is an effect that a communication device, a communication system, and a communication method capable of reducing wasted time in a transmission-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

Mode for Carrying Out the Invention

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

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

[0015] When the UE 30 receives the downlink packet, it transmits an ACK packet for the downlink packet. However, since a downlink slot is allocated when the base station 20 receives the downlink packet, the UE 30 is made to wait for the transmission opportunity of the ACK packet until time t3 when an uplink slot is allocated. Then, when time t3 arrives, the UE 30 transmits the ACK packet to the base station 20, and the base station 20 transmits the ACK packet to the server 90.

[0016] When the server 90 receives the ACK packet from the base station 20, it resumes the transmission of the downlink packet. In this way, at the server 90, in order to transmit the next downlink packet, it has to wait until it receives the ACK packet. As a result, at the server 90, the time from time t2 when the transmission of the downlink packet is completed to time t3 when the ACK packet is received is wasted time during which the downlink packet could have been transmitted but is not.

[0017] Also, at the server 90, since the RTT from the transmission of the downlink packet to the reception of the ACK packet becomes large, it is determined that the network is congested, and the growth of the congestion window stops (the size does not increase). Therefore, at the server 90, when transmitting the next downlink packet, it can only transmit a downlink packet with a data volume corresponding to the size of the congestion window in the state where the growth has stopped. As a result, at the server 90, wasted time also occurs after the transmission of the next downlink packet.

[0018] Hereinafter, embodiments of the present disclosure will be described with reference to the drawings. Note that, for the sake of clarity of explanation, the following description and drawings are appropriately omitted and simplified. Also, in the following drawings, the same elements are denoted by the same reference numerals, and redundant descriptions 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.

[0019] <Embodiment 1> First, with reference to FIG. 2, a configuration example of the communication system 1 according to the first embodiment will be described. As shown in FIG. 2, the communication system 1 according to the first embodiment includes a transmitting-side communication device 100 and a receiving-side communication device 200. The transmitting-side communication device 100 includes a communication unit 101, an acquisition unit 102, and a transmission timing control unit 103. Note that the transmitting-side communication device 100 is, for example, a server such as a Web server, and the receiving-side communication device 200 is, for example, a base station.

[0020] The communication unit 101 transmits a downlink packet to the receiving-side communication device 200 via the network, and receives an ACK packet for the downlink packet from the receiving-side communication device 200 via the network.

[0021] Note that the network according to the first embodiment generally refers to a communication network (regardless of wired or wireless) between the transmitting-side communication device 100 and the receiving-side communication device 200. However, when the receiving-side communication device 200 is a base station, the network refers to a communication network including a communication network between the transmitting-side communication device 100 and the receiving-side communication device 200 and a wireless communication network between the receiving-side communication device 200 and terminals such as UEs.

[0022] The acquisition unit 102 acquires the RTT for the downlink packets already transmitted by the communication unit 101 and the transmission time of the downlink packets already transmitted by the communication unit 101. The RTT for the downlink packets already transmitted by the communication unit 101 is the time from when the communication unit 101 transmits the downlink packet until the communication unit 101 receives the ACK packet for the downlink packet. For example, it is conceivable that the acquisition unit 102 uses ping to acquire the RTT. However, the method for acquiring the RTT is not limited to this. Also, for example, regarding the transmission time of the downlink packet, the acquisition unit 102 may manage it by itself or acquire it from the communication unit 101.

[0023] The transmission timing control unit 103 controls the transmission timing of the downlink packets by the communication unit 101 based on the RTT for the downlink packets already transmitted by the communication unit 101 and the transmission time of the downlink packets already transmitted by the communication unit 101. Note that the transmission timing controlled by the transmission timing control unit 103 is the transmission timing of the downlink packets that the communication unit 101 will transmit next. In response to this, the communication unit 101 transmits the downlink packet at the transmission timing controlled by the transmission timing control unit 103.

[0024] Note that the receiving-side communication device 200 may be any communication device as long as it has the function of receiving the downlink packet from the transmitting-side communication device 100 and transmitting the ACK packet for the downlink packet to the transmitting-side communication device 100, or the function of receiving the downlink packet from the transmitting-side communication device 100 and forwarding it to another device (if the receiving-side communication device 200 is a base station, the other device is a terminal such as a UE) and receiving the ACK packet for the downlink packet from the other device and transmitting it to the transmitting-side communication device 100. Therefore, the detailed configuration of the receiving-side communication device 200 will not be described.

[0025] Subsequently, with reference to FIG. 3, an example of the schematic operation flow of the transmitting-side communication device 100 according to Embodiment 1 will be described. As shown in FIG. 3, first, the acquisition unit 102 acquires the RTT for the downstream packet that the communication unit 101 has already transmitted and the transmission time of the downstream packet that the communication unit 101 has already transmitted (step S11).

[0026] Thereafter, the transmission timing control unit 103 controls the transmission timing of the downstream packet by the communication unit 101 based on the RTT for the downstream packet that the communication unit 101 has already transmitted and the transmission time of the downstream packet that the communication unit 101 has already transmitted (step S12).

[0027] As described above, according to the first embodiment, the transmission-side communication device 100 controls the transmission timing of the downstream packet by the communication unit 101 based on the RTT for the downstream packet that the communication unit 101 has already transmitted and the transmission time of the downstream packet that the communication unit 101 has already transmitted. As a result, the RTT can be reduced, so that the transmission-side communication device 100 can grow the congestion window (increase the size). As a result, in the transmission-side communication device 100, since the data amount of the downstream packet flowing through the network increases, the wasted time can be reduced.

[0028] Note that the transmission timing control unit 103 may specify the transmission time of the downstream packet with the minimum RTT among the downstream packets that the communication unit 101 has already transmitted, and control the transmission timing of the downstream packet by the communication unit 101 based on the specified transmission time and the scheduling interval of the network. For example, when the reception-side communication device 200 is a base station that communicates with a terminal in the TDD mode, the scheduling interval of the network may be the interval of the uplink slots allocated to the uplink. Note that the scheduling interval of the network may be calculated by any component in the transmission-side communication device 100 or acquired from an external device.

[0029] Further, the transmission-side communication device 100 may control the transmission timing of the downstream packet by the communication unit 101 so that the downstream packet is transmitted when the time corresponding to the scheduling interval of the network has elapsed since the specified transmission time. Note that the transmission timing may have a time width, for example, determined within a predetermined time range before and after the timing when the time corresponding to the scheduling interval has elapsed.

[0030] Further, the transmission-side communication device 100 may further include a transmission rate control unit that acquires the state of the network and controls the transmission bit rate of the downstream packet by the communication unit 101 based on the acquired network state. In this case, the communication unit 101 may transmit the downstream packet at the transmission bit rate controlled by the transmission rate control unit. Further, the transmission rate control unit may acquire the situation of increase and decrease of the RTT in the network as the state of the network.

[0031] Further, the transmission timing control unit 103 may specify the transmission time of the downstream packet with the minimum RTT among the downstream packets already transmitted by the communication unit 101, and based on the specified transmission time, the scheduling interval of the network, and the transmission bit rate of the downstream packet by the communication unit 101, control the transmission timing of the downstream packet by the communication unit 101.

[0032] <Embodiment 2> Subsequently, with reference to FIG. 4, 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.

[0033] As shown in FIG. 4, the communication system 2 according to Embodiment 2 includes a server 10, a base station 20, and a UE 30. Note that a TDD system is used for communication between the base station 20 and the UE 30. The server 10 includes a communication unit 11, an acquisition unit 12, a transmission timing control unit 13, and a transmission rate control unit 14. The server 10 is an example of a transmission-side communication device, such as a Web server or the like. The base station 20 is an example of a reception-side communication device.

[0034] The communication unit 11 transmits a downlink packet to the UE 30 via the base station 20, and receives an ACK packet for the downlink packet from the UE 30 via the base station 20.

[0035] Note that the network according to Embodiment 2 refers to a communication network including a communication network (regardless of wired or wireless) between the server 10 and the base station 20 and a wireless communication network between the base station 20 and the UE 30. The wireless communication network between the base station 20 and the UE 30 may be LTE (Long Term Evolution), 4G (Generation), 5G, or local 5G, etc.

[0036] The acquisition unit 12 acquires the RTT for the downlink packet already transmitted by the communication unit 11 and the transmission time of the downlink packet already transmitted by the communication unit 11. The RTT for the downlink packet already transmitted by the communication unit 11 is the time from when the communication unit 11 transmits the downlink packet until the communication unit 11 receives the ACK packet for the downlink packet. For example, it is conceivable that the acquisition unit 12 uses ping to acquire the RTT. However, the method for acquiring the RTT is not limited to this. Also, for example, the acquisition unit 12 may manage the transmission time of the downlink packet by itself or may acquire it from the communication unit 11.

[0037] The transmission timing control unit 13 controls the transmission timing of the downstream packet by the communication unit 11 based on the RTT for the downstream packet already transmitted by the communication unit 11 and the transmission time of the downstream packet already transmitted by the communication unit 11. Note that the transmission timing controlled by the transmission timing control unit 13 is the transmission timing of the downstream packet to be transmitted by the communication unit 11 in the future. For example, as shown in FIG. 5, the transmission timing control unit 13 takes into account the reception timing of the ACK packet and brings the transmission timing of the downstream packet closer to the uplink slot in which the base station 20 transmits the ACK packet to the server 10. As a result, the RTT can be reduced, so that the congestion window can be grown (the size can be increased).

[0038] The transmission rate control unit 14 acquires the state of the network and controls the transmission bit rate of the downstream packet by the communication unit 11 based on the acquired state of the network. For example, the transmission rate control unit 14 acquires, as the state of the network, the situation of increase or decrease of the RTT in the network.

[0039] In response to this, the communication unit 11 transmits the downstream packet at the transmission timing controlled by the transmission timing control unit 13 and the transmission bit rate controlled by the transmission rate control unit 14.

[0040] Subsequently, the operations of the transmission timing control unit 13 and the transmission rate control unit 14 will be described in detail. First, the operation of the transmission timing control unit 13 will be described in detail. FIG. 6 shows an example of the RTT acquired by the acquisition unit 12. In FIG. 6, the vertical axis represents the RTT, and the horizontal axis represents the packet number of the downstream packet. Here, the communication unit 11 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.

[0041] In the example of FIG. 6, the RTT is serrated. This is due to the UE 30 transmitting a plurality of ACK packets for a plurality of downlink packets that the base station 20 has transmitted separately in a plurality of downlink slots in one uplink slot.

[0042] Therefore, there are downlink packets with a small RTT and downlink packets with a large RTT. Among these, it is considered that the transmission time of the downlink packet with a small RTT is close to the uplink slot time when the base station 20 transmits an ACK packet to the server 10.

[0043] For example, in the example of FIG. 7, it is considered that the time t1 close to the uplink slot is the transmission time of the downlink packet with a small RTT. Therefore, if the downlink packet is transmitted based on this time t1, it is considered that the state with a small RTT is maintained.

[0044] Therefore, the transmission timing control unit 13 controls the transmission timing of the downlink packet so that the downlink packet is transmitted when the time corresponding to the interval between uplink slots has elapsed from the transmission time of the downlink packet with a small RTT.

[0045] Specifically, the transmission timing control unit 13 sets the transmission time of the downlink packet with the minimum RTT as S base and sets the interval of network scheduling, that is, the interval between uplink slots, as δ. Then, the transmission timing control unit 13 sets the transmission timing of the downlink packet as shown in the following formula 1.

Equation

[0046] Here, n = 1, 2, 3,.... Also, offset is a coefficient that increases as the transmission bit rate increases. However, offset is a coefficient that satisfies 0 ≦ offset < δ.

[0047] Next, the operation of the transmission rate control unit 14 will be described in detail. The transmission rate control unit 14 acquires, as the state of the network, the situation of increase or decrease in the RTT in the network. Here, it is assumed that the situation of increase or decrease in the RTT indicates either increase, stability, or decrease.

[0048] For example, in a situation where the RTT is increasing, the transmission rate control unit 14 decreases the transmission bit rate Rate(t) [bps] of the downlink packet. For example, the transmission rate control unit 14 sets Rate(t) as in the following formula 2.

Equation

[0049] On the other hand, in a situation where the RTT is stable or decreasing, the transmission rate control unit 14 increases the transmission bit rate Rate(t) [bps] of the downlink packet. For example, the transmission rate control unit 14 sets Rate(t) as in the following formula 3.

Equation

[0050] Note that the base station 20 may be implemented by any base station as long as it has the function of communicating with the UE 30 in the TDD mode, receiving downlink packets from the server 10 and forwarding them to the UE 30, and receiving ACK packets for the downlink packets from the UE 30 and transmitting them to the server 10. Also, the UE 30 may be implemented by any terminal as long as it has the function of communicating with the base station 20 in the TDD mode, receiving downlink packets from the base station 20, and transmitting ACK packets for the downlink packets to the base station 20. Therefore, the detailed configurations of the base station 20 and the UE 30 will be omitted from the description.

[0051] Next, referring to FIG. 8, an example of a schematic operation flow of the server 10 according to Embodiment 2 will be described. As shown in FIG. 8, first, the acquisition unit 12 acquires the RTT for the downstream packet already transmitted by the communication unit 11 and the transmission time of the downstream packet already transmitted by the communication unit 11 (step S21).

[0052] Next, the transmission timing control unit 13 controls the transmission timing of the downstream packet by the communication unit 11 based on the RTT for the downstream packet already transmitted by the communication unit 11 and the transmission time of the downstream packet already transmitted by the communication unit 11 (step S22).

[0053] Thereafter, the transmission rate control unit 14 acquires the state of the network and controls the transmission bit rate of the downstream packet by the communication unit 101 based on the acquired network state (step S23).

[0054] Note that the order of steps S22 and S23 is not limited to this. For example, first, step S23 may be executed, and then step S22 may be executed, or steps S22 and S23 may be executed in parallel substantially simultaneously.

[0055] As described above, according to Embodiment 2, the server 10 controls the transmission timing of the downstream packet by the communication unit 11 based on the RTT for the downstream packet already transmitted by the communication unit 11 and the transmission time of the downstream packet already transmitted by the communication unit 11. As a result, the RTT can be reduced, so the server 10 can grow the congestion window (increase the size). As a result, in the server 10, since the data amount of the downstream packet flowing through the network increases, the wasted time can be reduced.

[0056] In addition, the server 10 can increase the amount of data of the downstream packets flowing through the network by growing the congestion window. However, if the amount of data exceeds the allowable amount that can be transmitted in the downstream slot existing between two upstream slots, queuing delay will occur. Therefore, the server 10 acquires the state of the network and controls the transmission bit rate of the downstream packets by the communication unit 11 based on the state of the network. As a result, the amount of data of the downstream packets flowing through the network can be controlled so that queuing delay does not occur according to the state of the network. As a result, throughput can be improved in the server 10.

[0057] <Hardware Configuration of Transmission-Side Communication Device and Server According to Embodiment> Subsequently, with reference to FIG. 9, a hardware configuration example of a computer 40 that realizes the transmission-side communication device 100 according to the above-described Embodiment 1 and the server 10 according to the above-described Embodiment 2 will be described.

[0058] As shown in FIG. 9, the computer 40 includes a processor 41, a memory 42, a storage 43, an input / output interface (input / output I / F) 44, a communication interface (communication I / F) 45, and the like. The processor 41, the memory 42, the storage 43, the input / output interface 44, and the communication interface 45 are connected by a data transmission path for transmitting and receiving data to and from each other.

[0059] The processor 41 is an arithmetic processing device such as a CPU (Central Processing Unit) or a GPU (Graphics Processing Unit), for example. The memory 42 is a memory such as a RAM (Random Access Memory) or a ROM (Read Only Memory), for example. The storage 43 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 43 may be a memory such as a RAM or a ROM.

[0060] The storage 43 stores a program that realizes the functions of the components included in the transmission-side communication device 100 or the server 10. The processor 41 realizes the functions of the components included in the transmission-side communication device 100 or the server 10 by executing each of these programs. Here, when executing each of the above programs, the processor 41 may read these programs onto the memory 42 and then execute them, or may execute them without reading them onto the memory 42. Also, the memory 42 and the storage 43 also serve to realize the storage function included in the transmission-side communication device 100 or the server 10.

[0061] Also, 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 transmission-side communication device 100 or the server 10 described in the above-described embodiment. 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 disk storage, magnetic cassette, magnetic tape, magnetic disk storage, or other magnetic storage devices. The program may be transmitted on a temporary computer-readable medium or a communication medium. By way of example and not limitation, the temporary computer-readable medium or communication medium includes electrical, optical, acoustic, or other forms of propagated signals.

[0062] The input / output interface 44 is connected to a display device 441, an input device 442, a sound output device 443, etc. The display device 441 is a device that displays a screen corresponding to drawing data processed by the processor 41, such as an LCD (Liquid Crystal Display), a CRT (Cathode Ray Tube) display, or a monitor. The input device 442 is a device that receives the operator's operation input, such as a keyboard, a mouse, and a touch sensor. The display device 441 and the input device 442 may be integrated and realized as a touch panel. The sound output device 443 is a device that acoustically outputs sound corresponding to acoustic data processed by the processor 41, such as a speaker.

[0063] The communication interface 45 transmits and receives data to and from an external device. For example, the communication interface 45 communicates with an external device via a wired communication path or a wireless communication path.

[0064] As described above, the present disclosure has been described with reference to the embodiments, but the present disclosure is not limited to the above-described embodiments. Various changes 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.

[0065] Also, some or all of the above-described embodiments can be described as follows in the following supplementary notes, but are not limited thereto. (Supplementary Note 1) A communication unit that transmits a downstream packet via a network and receives an ACK (Acknowledge) packet for the downstream packet via the network; An acquisition unit that acquires an RTT (Round Trip Time) for a downstream packet already transmitted by the communication unit, which is the time from when the communication unit transmits the downstream packet until the communication unit receives the ACK packet, and the transmission time of the downstream packet already transmitted by the communication unit; A transmission timing control unit that controls the transmission timing of the downstream packet by the communication unit based on the RTT for the downstream packet already transmitted by the communication unit and the transmission time of the downstream packet already transmitted by the communication unit. Communication device. (Appendix 2) The transmission timing control unit Identifies the transmission time of the downstream packet with the minimum RTT among the downstream packets already transmitted by the communication unit, Based on the identified transmission time and the scheduling interval of the network, controls the transmission timing of the downstream packet by the communication unit. The communication device according to Appendix 1. (Appendix 3) The transmission timing control unit controls the transmission timing of the downstream packet by the communication unit so that the downstream packet is transmitted when the time corresponding to the scheduling interval of the network has elapsed from the identified transmission time. The communication device according to Appendix 2. (Appendix 4) Further includes a transmission rate control unit that acquires the state of the network and controls the transmission bit rate of the downstream packet by the communication unit based on the acquired state of the network. The communication device according to Appendix 3. (Appendix 5) The transmission rate control unit acquires, as the state of the network, the situation of increase or decrease of the RTT in the network. The communication device according to Appendix 4. (Appendix 6) The transmission timing control unit Based on the identified transmission time, the scheduling interval of the network, and the transmission bit rate of the downstream packet by the communication unit, controls the transmission timing of the downstream packet by the communication unit. The communication device according to Appendix 4 or 5. (Appendix 7) Transmits a downstream packet to a receiving communication device via a network, and receives an ACK (Acknowledge) packet for the downstream packet from the receiving communication device via the network; a communication unit An acquisition unit that acquires an RTT (Round Trip Time) for a downstream packet already transmitted by the communication unit, which is the time from when the communication unit transmits the downstream packet until the communication unit receives the ACK packet, and the transmission time of the downstream packet already transmitted by the communication unit A transmission timing control unit that controls the transmission timing of the downstream packet by the communication unit based on the RTT for the downstream packet already transmitted by the communication unit and the transmission time of the downstream packet already transmitted by the communication unit A communication system (Appendix 8) The transmission timing control unit Identifies the transmission time of the downstream packet with the minimum RTT among the downstream packets already transmitted by the communication unit Controls the transmission timing of the downstream packet by the communication unit based on the identified transmission time and the scheduling interval of the network The communication system according to Appendix 7 (Appendix 9) The transmission timing control unit controls the transmission timing of the downstream packet by the communication unit such that a downstream packet is transmitted when a time corresponding to the scheduling interval of the network has elapsed from the identified transmission time The communication system according to Appendix 8 (Appendix 10) Further includes a transmission rate control unit that acquires the state of the network and controls the transmission bit rate of the downstream packet by the communication unit based on the acquired state of the network The communication system according to Appendix 9 (Appendix 11) The transmission rate control unit acquires, as the state of the network, the situation of increase or decrease of the RTT in the network The communication system described in Supplementary Note 10. (Supplementary Note 12) The transmission timing control unit controls the transmission timing of the downstream packet by the communication unit based on the specified transmission time, the scheduling interval of the network, and the transmission bit rate of the downstream packet by the communication unit. The communication system described in Supplementary Note 10 or 11. (Supplementary Note 13) A communication method by a communication device, including a communication step of transmitting a downstream packet via a network and receiving an ACK (Acknowledge) packet for the downstream packet via the network, an acquisition step of acquiring the RTT (Round Trip Time) for the downstream packet already transmitted in the communication step, which is the time from transmitting the downstream packet in the communication step to receiving the ACK packet in the communication step, and the transmission time of the downstream packet already transmitted in the communication step, and a transmission timing control step of controlling the transmission timing of the downstream packet in the communication step based on the RTT for the downstream packet already transmitted in the communication step and the transmission time of the downstream packet already transmitted in the communication step. Communication method. (Supplementary Note 14) In the transmission timing control step, specify the transmission time of the downstream packet with the minimum RTT among the downstream packets already transmitted in the communication step, and control the transmission timing of the downstream packet in the communication step based on the specified transmission time and the scheduling interval of the network. The communication method described in Supplementary Note 13. (Supplementary Note 15) In the transmission timing control step, the transmission timing of the downstream packet in the communication step is controlled such that the downstream packet is transmitted when the time corresponding to the scheduling interval of the network has elapsed since the specified transmission time. The communication method according to Supplementary Note 14. (Supplementary Note 16) Further including a transmission rate control step of obtaining the state of the network and controlling the transmission bit rate of the downstream packet in the communication step based on the obtained state of the network. The communication method according to Supplementary Note 15. (Supplementary Note 17) In the transmission rate control step, the increase or decrease situation of the RTT in the network is obtained as the state of the network. The communication method according to Supplementary Note 16. (Supplementary Note 18) In the transmission timing control step, the transmission timing of the downstream packet in the communication step is controlled based on the specified transmission time, the scheduling interval of the network, and the transmission bit rate of the downstream packet in the communication step. The communication method according to Supplementary Note 16 or 17.

Explanation of Signs

[0066] 1,2 Communication system 100 Transmitting-side communication device 101 Communication unit 102 Acquisition unit 103 Transmission timing control unit 200 Receiving-side communication device 10 Server 11 Communication unit 12 Acquisition unit 13 Transmission timing control unit 14 Transmission rate control unit 20 Base station 30 UE 40 Computer 41 Processor 42 Memory 43 Storage 44 Input / Output Interface 441 Display Device 442 Input Device 443 Audio Output Device 45 Communication Interface

Claims

1. A communication unit that transmits downstream packets via a network and receives an ACK (Acknowledge) packet for the downstream packets via the network; An acquisition unit that acquires an RTT (Round Trip Time) for a downstream packet already transmitted by the communication unit, which is the time from when the communication unit transmits the downstream packet until the communication unit receives the ACK packet, and the transmission time of the downstream packet already transmitted by the communication unit; A transmission timing control unit that controls the transmission timing of downstream packets by the communication unit based on the RTT for the downstream packets already transmitted by the communication unit and the transmission time of the downstream packets already transmitted by the communication unit; The transmission timing control unit: Identifies the transmission time of the downstream packet with a small RTT among the downstream packets already transmitted by the communication unit; Controls the transmission timing of downstream packets by the communication unit based on the identified transmission time and the scheduling interval of the network; A communication device.

2. The transmission timing control unit controls the transmission timing of downstream packets by the communication unit such that a downstream packet is transmitted when a time equal to the scheduling interval of the network has elapsed from the identified transmission time. The communication device according to Claim 1.

3. Further comprising a transmission rate control unit that acquires the state of the network and controls the transmission bit rate of downstream packets by the communication unit based on the acquired state of the network. The communication device according to Claim 2.

4. The transmission rate control unit acquires, as the state of the network, the situation of increase or decrease of the RTT in the network. The communication device according to Claim 3.

5. The transmission timing control unit: Controls the transmission timing of downstream packets by the communication unit based on the identified transmission time, the scheduling interval of the network, and the transmission bit rate of the downstream packets by the communication unit. The communication device according to Claim 3 or 4.

6. A communication unit that transmits downstream packets to a receiving-side communication device via a network and receives an ACK (Acknowledge) packet for the downstream packets from the receiving-side communication device via the network; An acquisition unit that acquires an RTT (Round Trip Time) for a downstream packet already transmitted by the communication unit, which is the time from when the communication unit transmits the downstream packet until the communication unit receives the ACK packet, and the transmission time of the downstream packet already transmitted by the communication unit. A transmission timing control unit that controls the transmission timing of downstream packets by the communication unit based on the RTT for the downstream packets already transmitted by the communication unit and the transmission times of the downstream packets already transmitted by the communication unit. The transmission timing control unit identifies the transmission time of the downstream packet with a small RTT among the downstream packets already transmitted by the communication unit. Based on the identified transmission time and the scheduling interval of the network, controls the transmission timing of the downstream packets by the communication unit. Communication system.

7. The transmission timing control unit controls the transmission timing of the downstream packets by the communication unit such that a downstream packet is transmitted when a time equal to the scheduling interval of the network has elapsed from the identified transmission time. The communication system according to claim 6.

8. A communication method by a communication device, comprising: a communication step of transmitting a downstream packet via a network and receiving an ACK (Acknowledge) packet for the downstream packet via the network; an acquisition step of acquiring an RTT (Round Trip Time) for the downstream packet already transmitted in the communication step, which is the time from when the downstream packet is transmitted in the communication step until the ACK packet is received in the communication step, and the transmission time of the downstream packet already transmitted in the communication step; a transmission timing control step of controlling the transmission timing of the downstream packet in the communication step based on the RTT for the downstream packet already transmitted in the communication step and the transmission time of the downstream packet already transmitted in the communication step, wherein in the transmission timing control step, the transmission time of the downstream packet with a small RTT among the downstream packets already transmitted in the communication step is identified. Controlling the transmission timing of the downstream packet in the communication step based on the specified transmission time and the scheduling interval of the network. Communication method.

Images