Communication device, round trip time estimation method, and round trip time estimation program

Abstract

The invention relates to a communication device, a round-trip time estimation method, and a round-trip time estimation program. A communication device (2) that transmits a communication packet to a counterpart device and receives a delivery confirmation packet for the communication packet from the counterpart device, the communication device being provided with: a sequence information acquisition unit (9) that acquires sequence information of the communication packet and the delivery confirmation packet; and a round-trip time estimation unit (10) that estimates the round-trip time on the basis of the acquisition results of the sequence information acquisition unit. The round-trip time is estimated on the basis of at least the transmission time of one of the communication packets, the reception time of one of the acknowledgement packets, and either the transmission time of another communication packet or the reception time of another of the acknowledgement packets.

Description

Technical Field

[0001] The present invention relates to a communication device, a round-trip time estimation method, and a round-trip time estimation program. Background Art

[0002] In packet communication, a communication device sends a communication packet to a counterpart device, and when the counterpart device receives the communication packet from the communication device, it sends a delivery confirmation packet for the communication packet to the communication device. For example, Patent Document 1 discloses a technique for estimating a round-trip time (hereinafter referred to as RTT (Round-Trip Time)) based on the transmission time of the communication packet and the reception time of the delivery confirmation packet when sequence information of the communication packet sent from the communication device to the counterpart device and sequence information of the delivery confirmation packet sent from the counterpart device to the communication device match.

[0003] Patent Document 1: U.S. Patent No. 11516098

[0004] In the method disclosed in Patent Document 1, in order to determine the delivery confirmation packet that matches the sequence information of the communication data packet, it is necessary to determine the sequence information of multiple delivery confirmation packets before and after the delivery confirmation packet that matches the sequence information. Therefore, there is a problem of increased processing load. In addition, even if the delivery confirmation packet that matches the sequence information of the communication data packet is determined, when the delivery confirmation packet is a delayed packet or a duplicate packet, there is a problem of reduced RTT estimation accuracy. Summary of the invention

[0005] The present invention has been made in view of the above-mentioned circumstances, and an object of the present invention is to provide a communication device, a round-trip time estimation method, and a round-trip time estimation program capable of appropriately estimating a round-trip time.

[0006] According to one embodiment of the present disclosure, a communication data packet is sent to a counterpart device, and a delivery confirmation data packet for the communication data packet is received from the counterpart device. A sequence information acquisition unit acquires sequence information of the communication data packet and the delivery confirmation data packet. A round-trip time estimation unit estimates the round-trip time based on at least one of the three times of sending a communication data packet, receiving a delivery confirmation data packet, and sending another communication data packet or receiving another delivery confirmation data packet according to the acquisition result of the sequence information acquisition unit.

[0007] The round trip time is estimated based on at least three times: the time when a communication data packet is sent, the time when a delivery confirmation data packet is received, and any one of the time when another communication data packet is sent or the time when another delivery confirmation data packet is received. It is not necessary to determine the sequence information of multiple delivery confirmation data packets before and after the delivery confirmation data packet that contains the sequence information that matches, so that an increase in processing load can be avoided. It is also not necessary to determine the delivery confirmation data packet that matches the sequence information of the communication data packet, so that a decrease in the estimation accuracy of RTT can be avoided. It is possible to take into account both the avoidance of an increase in processing load and the avoidance of a decrease in estimation accuracy, and the round trip time can be appropriately estimated. BRIEF DESCRIPTION OF THE DRAWINGS

[0008] Figure 1 It is a functional block diagram showing the overall structure of one embodiment.

[0009] Figure 2 : is a flowchart showing the RTT estimation process based on the first method.

[0010] Figure 3 This is a diagram for explaining the RTT estimation process based on the first method.

[0011] Figure 4 This is a diagram for explaining the RTT estimation process based on the first method.

[0012] Figure 5 : is a flowchart showing the RTT estimation process based on the second method.

[0013] Figure 6 This is a diagram for explaining the RTT estimation process based on the second method.

[0014] Figure 7 This is a diagram for explaining the RTT estimation process based on the second method.

[0015] Figure 8 This is a flowchart showing the process of estimating the lower limit of the RTT variation range.

[0016] Fig. 9 This is a diagram for explaining the process of estimating the lower limit of the RTT variation range.

[0017] Fig.10 This is a diagram for explaining the process of estimating the lower limit of the RTT variation range. DETAILED DESCRIPTION

[0018] Hereinafter, with reference to the accompanying drawings, an embodiment in which the present invention is applied to a communication node mounted on a vehicle, for example, will be described. Figure 1As shown, the communication system 1 is configured so that the communication node 2 (equivalent to the communication device) and the counterpart node 3 (equivalent to the counterpart device) can perform data communication via a wireless line. The data communication performed between the communication node 2 and the counterpart node 3 is data communication that conforms to the communication protocol of TCP / IP (Transmission Control Protocol / Internet Protocol). The communication node 2 sends a communication data packet to the counterpart node 3 via a wireless line. When the counterpart node 3 receives a communication data packet from the communication node 2, it sends a delivery confirmation data packet for the received communication data packet to the communication node 2 via the wireless line. In addition, it can also be configured so that the communication node 2 and the counterpart node 3 can perform data communication via a relay base station, the communication node 2 and the base station perform data communication via a wireless line, and the counterpart node 3 and the base station perform data communication via a wired line.

[0019] The communication node 2 sends the driving control data related to driving control, such as vehicle speed, acceleration and deceleration, sharp turns, driving route, fuel consumption, etc., to the counterpart node 3. The counterpart node 3 can communicate data with multiple communication nodes 2 via wireless lines, and is, for example, a server having the function of performing statistical processing on driving control data for many non-specific vehicles. When the counterpart node 3 receives driving control data from each communication node 2 mounted on many non-specific vehicles, it performs statistical processing on the received driving control data. In addition, the data sent and received between the communication node 2 and the counterpart node 3 may also be data other than the above-mentioned driving control data, or may be data used for other purposes.

[0020] The communication node 2 has a control unit 4 that controls the overall operation of the node. The control unit 4 is mainly composed of a microcomputer having a CPU (Central Processing Unit), a ROM (Read Only Memory), a RAM (Random Access Memory), and an I / O (Input / Output). The functions provided by the control unit 4 can be provided by software recorded in a physical memory device and a computer that executes the software, only software, only hardware, or a combination thereof. For example, in the case where the control unit 4 is provided by an electronic circuit as hardware, the control unit 4 can be provided by a digital circuit or an analog circuit including many logic circuits. The control unit 4 executes a program stored in a non-transitional physical recording medium to perform processing corresponding to the program, and executes a method corresponding to the program.

[0021] The control unit 4 includes a packet generation unit 5, an in-vehicle communication interface unit 6 (equivalent to a packet receiving unit), an out-vehicle communication interface unit 7, a processing scheduling unit 8, a sequence information acquisition unit 9, an RTT estimation unit 10, a determination value calculation unit 11, and a variation range estimation unit 12, according to each function. Each of these units 5 to 12 executes an RTT estimation program and performs an RTT estimation method.

[0022] The packet generation unit 5 generates a communication packet according to the execution of the application by the control unit 4, and outputs the generated communication packet to the sequence information acquisition unit 9. When the in-vehicle communication interface unit 6 receives a communication packet from the external node 13 (equivalent to an external device), it outputs the received communication packet to the sequence information acquisition unit 9.

[0023] The vehicle-exterior communication interface unit 7 sends the communication data packet to the counterpart node 3 via the wireless line. The processing scheduling unit 8 schedules the processing of the communication data packet and the delivery confirmation data packet. When the processing of the communication data packet and the delivery confirmation data packet has been scheduled by the processing scheduling unit 8, the sequence information acquisition unit 9 acquires the sequence number (equivalent to the sequence information) of the communication data packet and the delivery confirmation data packet after the processing is scheduled. The sequence number is information that can respectively determine the order in which the communication data packet is sent and the order in which the delivery confirmation data packet is received. If the order in which the communication data packet is sent and the order in which the delivery confirmation data packet is received can be determined respectively, it is not limited to the sequence number, and information other than the sequence number can also be used.

[0024] When the sequence numbers of the communication data packets and the delivery confirmation data packets are acquired by the sequence information acquisition unit 9, the RTT estimation unit 10 estimates the RTT based on the transmission time of the communication data packets and the reception time of the delivery confirmation data packets according to the acquisition result. As a method of estimating the RTT, there are a first method of estimating the RTT based on the transmission time of one communication data packet and the reception time of two delivery confirmation data packets, and a second method of estimating the RTT based on the transmission time of two communication data packets and the reception time of one delivery confirmation data packet.

[0025] In the first method, the RTT estimation unit 10 estimates the RTT when the sequence number of the later delivery confirmation packet matches the sequence number of the communication packet, or the sequence number between the sequence numbers of the two delivery confirmation packets matches the sequence number of the communication packet, under the condition that two delivery confirmation packets are received after the transmission of one communication packet. In the second method, the RTT estimation unit 10 estimates the RTT when the sequence number of the earlier communication packet matches the sequence number of the delivery confirmation packet, or the sequence number between the sequence numbers of the two communication packets matches the sequence number of the delivery confirmation packet, under the condition that one delivery confirmation packet is received after the transmission of two communication packets.

[0026] The determination value calculation unit 11 calculates the upper limit and lower limit of the RTT of each sample for a plurality of samples in a predetermined measurement period, calculates the minimum value among the calculated plurality of upper limits as the upper limit determination value, and calculates the maximum value among the calculated plurality of lower limits as the lower limit determination value. When the determination value calculation unit 11 calculates the upper limit determination value and the lower limit determination value, the fluctuation range estimation unit 12 compares the calculated upper limit determination value and the lower limit determination value, and when the upper limit determination value is smaller than the lower limit determination value, estimates the difference between the upper limit determination value and the lower limit determination value as the lower limit of the RTT fluctuation range.

[0027] Next, refer to Figures 2 to 10 Here, the function of the above-mentioned structure is described. Here, the RTT estimation process of estimating the RTT and the RTT variation range lower limit estimation process of estimating the lower limit of the RTT variation range are described.

[0028] (1) RTT estimation process

[0029] As described above, there are the first method and the second method for estimating the RTT. Hereinafter, each process will be described.

[0030] (1-1) RTT estimation process based on the first method (see Figures 2 to 4 )

[0031] The control unit 4 starts the RTT estimation process based on the first method, and when a request to send a communication data packet is generated, the control unit 4 obtains the sequence number of the communication data packet that is the object of the sending request (S1, equivalent to the first information acquisition step). When the control unit 4 sends the communication data packet to the other node 3, it stores the sending time of the communication data packet in correspondence with the sequence number of the acquired communication data packet (S2).

[0032] When receiving a delivery confirmation packet from the counterpart node 3, the control unit 4 obtains the sequence number of the received delivery confirmation packet (S3, equivalent to the second information acquisition step). The control unit 4 stores the reception time of the delivery confirmation packet in association with the sequence number of the obtained delivery confirmation packet (S4).

[0033] When receiving another delivery confirmation packet from the counterpart node 3, the control unit 4 obtains the sequence number of the received another delivery confirmation packet (S5, equivalent to the second information acquisition step). The control unit 4 stores the reception time of the other delivery confirmation packet in correspondence with the sequence number of the obtained other delivery confirmation packet (S6).

[0034] The control unit 4 determines whether the condition for estimating the RTT is satisfied. The control unit 4 determines whether the sequence number of the later delivery confirmation packet matches the sequence number of the communication packet (S7). If it is determined to match (S7: "Yes"), the control unit 4 estimates the RTT based on the three times of the transmission time of one communication packet and the reception time of the two delivery confirmation packets (S9), and ends the RTT estimation process based on the first method.

[0035] On the other hand, when it is determined that there is no match (S7: "No"), the control unit 4 determines whether the sequence number between the sequence numbers of the two delivery confirmation packets matches the sequence number of the communication packet (S8). When it is determined that there is a match (S8: "Yes"), in this case, the control unit 4 also estimates the RTT based on the three times of the transmission time of one communication packet and the reception time of the two delivery confirmation packets (S9), and ends the RTT estimation process based on the first method. On the other hand, when it is determined that there is no match (S8: "No"), the control unit 4 does not estimate the RTT, and ends the RTT estimation process based on the first method.

[0036] like Figure 3 As shown, the control unit 4 sets "n" as the segment size, a>0, b≥0, sends a communication data packet with sequence number "s1" to the counterpart node 3 at the sending time "Ts(s1)", receives a delivery confirmation data packet with sequence number "s1-an" from the counterpart node 3 at the receiving time "Ta(s1-an)", and when a delivery confirmation data packet with sequence number "s1+bn" is received from the counterpart node 3 at the receiving time "Ta(s1+bn)", the RTT is estimated by the following calculation formula.

[0037] Ta(s1-an)-Ts(s1)<RTT<Ta(s1+bn)-Ts(s1)

[0038] That is, the control unit 4 estimates that the RTT is within a range with Ta(s1-an)-Ts(s1) as a lower limit and Ta(s1+bn)-Ts(s1) as an upper limit.

[0039] The control unit 4 calculates the difference between the upper limit and the lower limit of the RTT of each sample as the estimation error based on a plurality of samples in a predetermined measurement period. Figure 4 As shown, the control unit 4 estimates the difference between the upper limit and the lower limit of the transmission of the communication data packet with the sequence number "s1" as the estimation error using the following calculation formula.

[0040] Estimation error = Ta(s1+bn)-Ta(s1-an)

[0041] When the control unit 4 transmits a communication data packet with a sequence number “s1” and then transmits a communication data packet with a sequence number “s2”, assuming that c>0 and d≥0, the RTT is estimated similarly using the following calculation formula.

[0042] Ta(s2-cn)-Ts(s2)<RTT<Ta(s2+dn)-Ts(s2)

[0043] That is, the control unit 4 estimates that the RTT is within a range with Ta(s2-cn)-Ts(s2) as a lower limit and Ta(s2+dn)-Ts(s2) as an upper limit.

[0044] The control unit 4 estimates the difference between the upper limit and the lower limit of the transmission of the communication data packet with the sequence number "s2" as the estimation error using the following calculation formula.

[0045] Estimation error = Ta(s1+dn)-Ta(s1-cn)

[0046] When the estimation error of each sample is calculated for a plurality of samples, the control unit 4 estimates the RTT for the sample with the relatively small estimation error. The control unit 4 performs statistical processing on the samples with the estimation error less than x% of the average value of all samples as valid samples to estimate the RTT. "x" is, for example, a value that satisfies the estimation accuracy required by the system. Figure 4 In the example, the estimation error of the sample of the communication data packet with sequence number "s2" is smaller than that of the sample of the communication data packet with sequence number "s1", so the sample of the communication data packet with sequence number "s2" is more likely to be adopted as a valid sample.

[0047] (2) RTT estimation process based on the second method (see Figures 5 to 7 )

[0048] The control unit 4 starts the RTT estimation process based on the second method, and when a request to send a communication data packet is generated, the control unit 4 obtains the sequence number of the communication data packet that is the object of the sending request (S11, equivalent to the first information acquisition step). When the control unit 4 sends the communication data packet to the other node 3, it stores the sending time of the communication data packet in correspondence with the sequence number of the acquired communication data packet (S12).

[0049] When a transmission request of another communication data packet is generated, the control unit 4 obtains the sequence number of the other communication data packet that is the object of the transmission request (S13, equivalent to the first information acquisition step). When the control unit 4 transmits the other communication data packet to the counterpart node 3, it stores the transmission time of the communication data packet in correspondence with the sequence number of the other communication data packet obtained (S14).

[0050] When receiving a delivery confirmation packet from the counterpart node 3, the control unit 4 obtains the sequence number of the received delivery confirmation packet (S15, equivalent to the second information acquisition step). The control unit 4 stores the reception time of the delivery confirmation packet in association with the sequence number of the obtained delivery confirmation packet (S16).

[0051] The control unit 4 determines whether the condition for estimating the RTT is satisfied. The control unit 4 determines whether the sequence number of the communication data packet on the previous side matches the sequence number of the delivery confirmation data packet (S17). When it is determined that they match (S7: "Yes"), the control unit 4 estimates the RTT based on the three times of the transmission time of the two communication data packets and the reception time of the delivery confirmation data packet (S19), and ends the RTT estimation process based on the second method.

[0052] On the other hand, when it is determined that there is no match (S17: "No"), the control unit 4 determines whether the sequence number between the sequence numbers of the two communication data packets matches the sequence number of the delivery confirmation data packet (S18). When it is determined that there is a match (S18: "Yes"), in this case, the control unit 4 also estimates the RTT based on the three times of the transmission time of the two communication data packets and the reception time of one delivery confirmation data packet (S19), and ends the RTT estimation process based on the second method. On the other hand, when it is determined that there is no match (S18: "No"), the control unit 4 does not estimate the RTT, and ends the RTT estimation process based on the second method.

[0053] like Figure 6 As shown, the control unit 4 sets "n" as the segment size, a≥0, b>0, sends a communication data packet with sequence number "s1-an" to the other node 3 at the sending time "Ts(s1-an)", sends a communication data packet with sequence number "s1+bn" to the other node 3 at the sending time "Ts(s1+bn)", and when a delivery confirmation data packet with sequence number "s1" is received from the other node 3 at the receiving time "Ta(s1)", the RTT is estimated by the following calculation formula.

[0054] Ta(s1)-Ts(s1+bn)<RTT<Ta(s1)-Ts(s1-an)

[0055] That is, the control unit 4 estimates that the RTT is within a range with Ta(s1)-Ts(s1+bn) as a lower limit and Ta(s1)-Ts(s1-an) as an upper limit.

[0056] In this case, the control unit 4 also calculates the difference between the upper limit and the lower limit of the RTT of each sample as the estimation error for a plurality of samples in a predetermined measurement period. Figure 7As shown, the control unit 4 estimates the difference between the upper limit and the lower limit of the reception of the delivery confirmation packet with the sequence number "s1" as the estimation error using the following calculation formula.

[0057] Estimation error = Ts(s1+bn)-Ts(s1-an)

[0058] When the control unit 4 sends the delivery confirmation packets of sequence numbers "s1-an" and "s1+bn" and then sends the delivery confirmation packets of sequence numbers "s1-cn" and "s1+dn", c≥0 and d>0 are assumed and the RTT is estimated by the following calculation formula.

[0059] Ta(s2)-Ts(s2+dn)<RTT<Ta(s2)-Ts(s2-cn)

[0060] That is, the control unit 4 estimates that the RTT is within a range with Ta(s2)-Ts(s2+dn) as a lower limit and Ta(s2)-Ts(s2-cn) as an upper limit.

[0061] The control unit 4 estimates the difference between the upper limit and the lower limit of the reception of the delivery confirmation packet with the sequence number "s2" as the estimation error using the following calculation formula.

[0062] Estimation error = Ts(s2+dn)-Ts(s2-cn)

[0063] When the estimation error of each sample is calculated for a plurality of samples, the control unit 4 estimates the RTT for the sample with the relatively small estimation error. The control unit 4 performs statistical processing on the samples with the estimation error less than x% of the average value of all samples as valid samples to estimate the RTT. Figure 7 In the example, the estimation error of the sample of the delivery confirmation packet with sequence number "s2" is smaller than that of the sample of the delivery confirmation packet with sequence number "s1", so the sample of the delivery confirmation packet with sequence number "s2" is more likely to be adopted as a valid sample.

[0064] (2) Estimation of the lower limit of the RTT fluctuation range (see Figures 8 to 10 )

[0065] When the control unit 4 starts estimating the lower limit of the RTT variation range, it calculates the upper limit and lower limit of the RTT of each sample for a plurality of samples in a predetermined measurement period. The control unit 4 calculates the minimum value among the calculated plurality of upper limits as the upper limit judgment value (S21), and calculates the maximum value among the calculated plurality of lower limits as the lower limit judgment value (S22).

[0066] The control unit 4 compares the upper limit judgment value with the lower limit judgment value, and judges whether the upper limit judgment value is smaller than the lower limit judgment value (S23). When it is judged that the upper limit judgment value is smaller than the lower limit judgment value (S23: "Yes"), the control unit 4 estimates the difference between the upper limit judgment value and the lower limit judgment value as the lower limit of the fluctuation range of the RTT (S24), and ends the estimation process of the lower limit of the fluctuation range of the RTT. On the other hand, when it is judged that the upper limit judgment value is not smaller than the lower limit judgment value (S23: "No"), the control unit 4 does not estimate the lower limit of the fluctuation range of the RTT, and ends the estimation process of the lower limit of the fluctuation range of the RTT.

[0067] like Fig. 9 As shown, for example, when the number of samples a to d in the predetermined measurement period is four, if the control unit 4 determines that the upper limit judgment value is smaller than the lower limit judgment value, the difference between the upper limit judgment value and the lower limit judgment value is estimated as the lower limit of the fluctuation range of the RTT. Fig.10 As shown, for example, when the number of samples e to h in the predetermined measurement period is four, the control unit 4 does not estimate the lower limit of the RTT fluctuation range when it is determined that the upper limit determination value is not smaller than the lower limit determination value.

[0068] As described above, according to this embodiment, the following effects can be obtained.

[0069] In the communication node 2, the RTT is estimated based on at least three times: the time when a communication data packet is sent, the time when a delivery confirmation data packet is received, and the time when another communication data packet is sent or the time when another delivery confirmation data packet is received. It is not necessary to determine the sequence numbers of multiple delivery confirmation data packets before and after the delivery confirmation data packet whose sequence number matches, so that an increase in processing load can be avoided. It is also not necessary to determine the delivery confirmation data packet that matches the sequence number of the communication data packet, so that a decrease in the estimation accuracy of the RTT can be avoided. It is possible to take into account both the avoidance of an increase in processing load and the avoidance of a decrease in estimation accuracy, and the RTT can be appropriately estimated.

[0070] Under the condition that two delivery confirmation packets are received after one communication packet is sent, when the sequence number of the later delivery confirmation packet matches the sequence number of the communication packet, or when the sequence number between the sequence numbers of the two delivery confirmation packets matches the sequence number of the communication packet, the RTT is estimated based on the sending time of one communication packet and the receiving time of the two delivery confirmation packets. The RTT can be appropriately estimated using the sending time of one communication packet and the receiving time of the two delivery confirmation packets.

[0071] Under the condition that a delivery confirmation packet is received after two communication data packets are sent, when the sequence number of the previous communication data packet matches the sequence number of the delivery confirmation packet, or when the sequence number between the sequence numbers of the two communication data packets matches the sequence number of the delivery confirmation packet, the RTT is estimated based on the sending time of the two communication data packets and the receiving time of the one delivery confirmation packet. The RTT can be appropriately estimated using the sending time of the two communication data packets and the receiving time of the one delivery confirmation packet.

[0072] The RTT is estimated by acquiring the sequence number of the communication data packet generated by the communication node 2. The RTT can be estimated appropriately using the sequence number of the communication data packet generated by the communication node 2.

[0073] The RTT is estimated by acquiring the sequence number of the communication data packet received from the external node 13. The RTT can be estimated appropriately using the sequence number of the communication data packet received from the external node 13.

[0074] The RTT is estimated by acquiring the sequence numbers of the communication data packets and the delivery confirmation data packets after the scheduling. The RTT can be estimated appropriately by using the sequence numbers of the communication data packets and the delivery confirmation data packets after the scheduling.

[0075] The difference between the upper limit and the lower limit of the RTT of each sample is calculated as an estimation error for a plurality of samples in a predetermined measurement period, and the RTT is estimated for samples with relatively small estimation errors. By estimating the RTT for samples with relatively small estimation errors, the influence caused by the delay of the delivery confirmation packet can be suppressed, and false detection of congestion can be avoided in advance.

[0076] The upper limit and lower limit of RTT of each sample are calculated for a plurality of samples in a predetermined measurement period, the minimum value among the plurality of calculated upper limits is calculated as the upper limit judgment value, and the maximum value among the plurality of lower limits is calculated as the lower limit judgment value, and when the upper limit judgment value is smaller than the lower limit judgment value, the difference between the upper limit judgment value and the lower limit judgment value is estimated as the lower limit of the fluctuation range of RTT. By estimating the difference between the upper limit judgment value and the lower limit judgment value when the upper limit judgment value is smaller than the lower limit judgment value as the lower limit of the fluctuation range of RTT, the lower limit of the fluctuation range of RTT caused by the delay of the line itself in a period assuming that the line condition is constant can be estimated, and the estimation accuracy of RTT can be improved.

[0077] Although the present disclosure is described based on the embodiments, it should be understood that the present disclosure is not limited to the above-mentioned embodiments and structures. The present disclosure also includes various modifications and modifications within the equivalent range. In addition, various combinations and methods, and other combinations and methods containing only one element, above or below them, also belong to the scope and thought range of the present disclosure.

[0078] The control unit and method described in the present disclosure may also be implemented by a special-purpose computer, which is provided by a processor and a memory programmed to execute one or more functions embodied by a computer program. Alternatively, the control unit and method described in the present disclosure may also be implemented by a special-purpose computer, which is provided by a processor composed of one or more special-purpose hardware logic circuits. Alternatively, the control unit and method described in the present disclosure may also be implemented by one or more special-purpose computers, which are composed of a combination of a processor and a memory programmed to execute one or more functions and a processor composed of one or more hardware logic circuits. In addition, a computer program may also be stored as an instruction executed by a computer in a computer-readable non-transient tangible recording medium.

Claims

1. A communication device, which transmits a communication data packet to a counterpart device and receives a delivery confirmation data packet for the communication data packet from the counterpart device, wherein: have: a sequence information acquisition unit that acquires sequence information of the communication data packet and the delivery confirmation data packet; and The round-trip time estimation unit estimates the round-trip time based on at least three moments according to the acquisition result of the above-mentioned sequence information acquisition unit, and the above-mentioned three moments are the sending moment of the above-mentioned communication data packet, the receiving moment of the above-mentioned delivery confirmation data packet, and any one of the sending moment of another above-mentioned communication data packet and the receiving moment of another above-mentioned delivery confirmation data packet.

2. The communication device according to claim 1, wherein: The round-trip time estimation unit estimates the round-trip time based on the sending time of one communication data packet and the receiving time of two delivery confirmation data packets, under the condition that two delivery confirmation data packets are received after the sending of one communication data packet, and when the sequence information of the latter delivery confirmation data packet matches the sequence information of the communication data packet, or when the sequence information between the two delivery confirmation data packets matches the sequence information of the communication data packet.

3. The communication device according to claim 1, wherein: The round-trip time estimation unit estimates the round-trip time based on the sending time of two communication data packets and the receiving time of one delivery confirmation data packet, under the condition that a delivery confirmation data packet is received after the sending of two communication data packets, and when the sequence information of the communication data packet on the front side matches the sequence information of the delivery confirmation data packet, or when the sequence information between the sequence information of the two communication data packets matches the sequence information of the delivery confirmation data packet.

4. The communication device according to any one of claims 1 to 3, wherein: A data packet generating unit is provided, wherein the data packet generating unit generates a data packet. The sequence information acquisition unit acquires the sequence information of the communication packet generated by the packet generation unit.

5. The communication device according to any one of claims 1 to 4, wherein: A data packet receiving unit is provided, the data packet receiving unit receives the communication data packet from an external device, The sequence information acquisition unit acquires sequence information of the communication packet received by the packet reception unit from the external device.

6. The communication device according to any one of claims 1 to 5, wherein: A scheduling unit is provided, wherein the scheduling unit schedules the processing of the communication data packet and the delivery confirmation data packet, The sequence information acquisition unit acquires sequence information of the communication data packets and the delivery confirmation data packets whose processing is scheduled by the processing scheduling unit.

7. The communication device according to any one of claims 1 to 6, wherein: The round trip time estimation unit calculates a difference between an upper limit and a lower limit of the round trip time for each sample as an estimation error for a plurality of samples in a predetermined measurement period, and estimates the round trip time for a sample having a relatively small calculated estimation error.

8. The communication device according to any one of claims 1 to 7, wherein: have: a determination value calculation unit that calculates an upper limit and a lower limit of the round trip time for each sample for a plurality of samples in a predetermined measurement period, calculates a minimum value among the plurality of calculated upper limits as an upper limit determination value, and calculates a maximum value among the plurality of lower limits as a lower limit determination value; as well as The fluctuation range estimation unit estimates a difference between the upper limit judgment value and the lower limit judgment value as a lower limit of the fluctuation range of the round-trip time when the upper limit judgment value calculated by the judgment value calculation unit is smaller than the lower limit judgment value.

9. A method for estimating a round trip time, wherein a communication device that sends a communication data packet to a counterpart device and receives a delivery confirmation data packet for the communication data packet from the counterpart device, performs the following steps: A first information acquisition step of acquiring sequence information of the communication data packet; A second information acquisition step of acquiring sequence information of the delivery confirmation data packet; and An estimating step of estimating the round trip time based on at least three times according to the acquisition result of the first information acquisition step and the acquisition result of the second information acquisition step, wherein: The three times are a transmission time of one of the communication data packets, a reception time of one of the delivery confirmation data packets, and any one of a transmission time of another of the communication data packets and a reception time of another of the delivery confirmation data packets.

10. A storage medium storing a round-trip time estimation program, wherein: The control unit of the communication device that transmits a communication data packet to a counterpart device and receives a delivery confirmation data packet for the communication data packet from the counterpart device executes the following steps: A first information acquisition step of acquiring sequence information of the communication data packet; A second information acquisition step of acquiring sequence information of the delivery confirmation data packet; and According to the acquisition result of the above-mentioned first information acquisition step and the acquisition result of the above-mentioned second information acquisition step, an estimation step of estimating the round-trip time is based on at least three moments, wherein the above-mentioned three moments are the sending moment of the above-mentioned communication data packet, the receiving moment of the above-mentioned delivery confirmation data packet, and any one of the sending moment of another above-mentioned communication data packet and the receiving moment of another above-mentioned delivery confirmation data packet.

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