Packet transmission device, packet transmission method, and packet transmission program

Abstract

To maintain high communication stability by preventing frequent re-transmissions while broadband communication is performed when a communication line including a plurality of different types of wireless communication is used.SOLUTION: A packet transmitting device 10 transmits data packets to a packet receiving device 20 using a first communication line and a second communication line whose communication possible area, where communication is possible, is smaller than that of the first communication line. The packet transmitting device includes: a communication status determination unit 102 that determines the communication status of the second communication line; a main / sub-line setting unit 103 that sets either the first communication line or the second communication line as a main communication line and the other as a sub-communication line; a transmission packet generation unit 104 that generates main data packets that are not subjected to band-limiting processing and sub-data packets that are subjected to band-limiting processing; and a transmission instruction unit 105 that gives instructions to transmit the main data packets through the main communication line and the sub-data packets through the sub-communication line.SELECTED DRAWING: Figure 2

Description

[Technical field]

[0001] The present invention relates to a packet transmission device, a packet transmission method, and a packet transmission device program for performing communication by using in parallel a communication line including a plurality of different types of wireless communication. [Background technology]

[0002] In recent years, studies have been conducted on linking a plurality of different types of wireless communication to perform communication in parallel.

[0003] Patent document 1 discloses transmitting data using a number of modems having different communication performance characteristics, and supplying packets to the associated modems for transmission according to the optimal rate under the conditions prevailing at the time.

[0004] This makes it possible to carry out virtually broadband communications. [Prior art documents] [Patent documents]

[0005] [Patent Document 1] Patent Publication 2015-173494 Summary of the Invention [Problem to be solved by the invention]

[0006] Here, the present inventors have found the following problem. In a technology for distributing communication loads such as that disclosed in Patent Document 1, a large number of packets are allocated to a broadband communication line. However, if the broadband communication line is interrupted, a large number of packets allocated will be lost. Normally, packet loss is restored using error correction and correction technology such as FEC, but this is not possible when a large amount of packet loss occurs, and retransmission will be necessary. In particular, in vehicle applications, the communication environment is expected to change drastically over time and space, and retransmissions may occur frequently.

[0007] Therefore, an object of the present invention is to suppress packet loss and prevent frequent retransmission when multiple communication lines are used. [Means for solving the problem]

[0008] A packet transmitting device (10) according to the present disclosure is a packet transmitting device (10) that transmits a data packet to a packet receiving device (20) using a first communication line and a second communication line having a narrower communication coverage area than the first communication line, A packet storage unit (101) for storing the data packets; a communication state determination unit (102) for determining a communication state of the second communication line; a main / sub-line setting unit (103) that sets one of the first communication line and the second communication line as a main communication line and the other as a sub-communication line based on a determination by the communication state determination unit; a transmission packet generating unit (104) for generating a main data packet not subjected to band limiting processing and a sub data packet subjected to band limiting processing from the data packet; a transmission instruction unit (105) for instructing transmission of the main data packet over the main communication line and the sub data packet over the sub communication line; The data transmission device includes a first communication unit (106) that transmits the main data packet or the secondary data packet using the first communication line based on an instruction from the transmission instruction unit, and a second communication unit (107) that transmits the secondary data packet or the main data packet using the second communication line.

[0009] In addition, the claims and the numbers in parentheses attached to the constituent elements of the invention described in this section indicate the correspondence between the present invention and the embodiments described below, and are not intended to limit the present invention. Effect of the Invention

[0010] With the above-described configuration, the packet transmission device of the present disclosure can reduce packet loss and prevent frequent retransmissions. [Brief description of the drawings]

[0011] [Figure 1] FIG. 1 is an explanatory diagram for explaining a communication system according to an embodiment of the present invention; [Diagram 2] FIG. 1 is a block diagram showing the configuration of a packet transmission device according to an embodiment of the present invention. [Diagram 3] FIG. 2 is an explanatory diagram of the data structure of a data packet and a main / sub data packet according to the embodiment; [Figure 4] FIG. 1 is an explanatory diagram of a data structure of an Ack packet according to the present embodiment; [Diagram 5] A main flow diagram showing the operation of the packet transmitting device 10 of the present embodiment. [Figure 6] FIG. 1 is an explanatory diagram showing a reception status of an Ack packet in a narrow area communication line according to an embodiment of the present invention; [Figure 7] FIG. 1 is a flow diagram showing a method for determining the communication state of a narrow area communication line according to an embodiment of the present invention. [Figure 8] FIG. 1 is an explanatory diagram showing the reception status of Ack packets on a wide area communication line and a narrow area communication line according to an embodiment of the present invention; [Figure 9] FIG. 1 is a flow diagram showing a method for setting a main communication line and a sub-communication line according to an embodiment of the present invention. [Figure 10] FIG. 1 is a flow diagram showing a method for generating a main data packet and a sub data packet according to an embodiment of the present invention. [Figure 11] FIG. 1 is a flow diagram showing a method for instructing transmission of a main data packet and a sub data packet according to an embodiment of the present invention. [Figure 12] FIG. 1 is a block diagram showing the configuration of a packet receiving device 20 according to an embodiment of the present invention. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0012] Hereinafter, an embodiment of the present invention will be described with reference to the drawings.

[0013] The present invention means the invention described in the claims or in the Summary of the Invention section, and is not limited to the following embodiments. Furthermore, at least the words in quotation marks mean the words described in the claims or in the Summary of the Invention section, and are not limited to the following embodiments.

[0014] The configurations and methods described in the dependent claims are optional configurations and methods in the invention described in the independent claims. The configurations and methods of the embodiments corresponding to the configurations and methods described in the dependent claims, and the configurations and methods described only in the embodiments without being described in the claims, are optional configurations and methods in the present invention. The configurations and methods described in the embodiments when the description of the claims is broader than the description of the embodiments are also optional configurations and methods in the present invention in the sense that they are examples of the configurations and methods of the present invention. In either case, by being described in the independent claims, they become essential configurations and methods of the present invention.

[0015] The effects described in the embodiments are effects obtained when the configurations of the embodiments are provided as examples of the present invention, and are not necessarily effects that the present invention possesses.

[0016] When there are multiple embodiments, the configurations disclosed in each embodiment are not limited to each embodiment, but can be combined across the embodiments. For example, a configuration disclosed in one embodiment may be combined with another embodiment. Also, configurations disclosed in each of the multiple embodiments may be collected and combined. The same applies to modified examples and examples.

[0017] The problem described in the section on problems that the invention is intended to solve is not a publicly known problem, but was discovered independently by the inventor, and this, together with the configuration and method of the present invention, is a fact that affirms the inventive step of the invention.

[0018] 1. Embodiment (1) Overview of the Communication System and Present Embodiment An example of the configuration of a communication system 1 including a packet transmitting device 10 of this embodiment will be described with reference to FIG.

[0019] The communication system 1 is composed of a packet transmitting device 10, a packet receiving device 20, a wide area communication line, and a narrow area communication line. The wide area communication line is realized by a base station 30, and the narrow area communication line is realized by a base station 31.

[0020] A wide-area communication line (corresponding to the "first communication line") is a communication line with a wide coverage area per base station, that is, a communication area where communication is possible. Because the communication area is wide, there is a low possibility of communication interruption due to movement. Examples of wide-area communication lines include W-CDMA (Wideband Code Division Multiple Access), HSPA (High Speed ​​Packet Access), LTE (Long Term Evolution), LTE-A (Long Term Evolution Advanced), 4G (4th Generation Mobile Communication System), and standalone (SA type) 5G (5th Generation Mobile Communication System).

[0021] When 4G is used as a wide-area communication line, the communication area is as wide as 10 kilometers if a macrocell is used. Also, the communication speed of the uplink from the packet transmitting device 10 to the base station 30 is about 100 Mbps at maximum.

[0022] A narrow area communication line (corresponding to the "second communication line") is a communication line in which the coverage area per base station, i.e., the communication area, is narrower than a wide area communication line. Because the communication area is narrow, there is a higher possibility of communication interruption due to movement compared to a wide area communication line. Typically, narrow area communication lines have faster communication speeds, i.e., higher throughput, than wide area communication lines. Examples of narrow area communication lines include non-standalone (NSA type) 5G (5th Generation Mobile Communication System), IEEE802.11 (Wi-Fi (registered trademark)), or IEEE802.16 (WiMAX (registered trademark)).

[0023] When non-standalone 5G is used as a narrow area communication line, the communication area is limited to a radius of a few hundred meters even in places with good visibility if small cells are used. In addition, the communication speed of the uplink from the packet transmission device 10 to the base station 31 is a maximum of 10 Gbps, which is much faster than 4G.

[0024] However, the relationship between the wide area communication line and the narrow area communication line may be relative and is not limited to the above example. The width of the communication area may be evaluated in consideration of beamforming and directivity in addition to cell size, transmission power, or carrier frequency. Other examples of these communication lines that are wireless communication lines include Bluetooth (registered trademark), Ultra Wide Band (UWB), and Dedicated Short Range Communication (DSRC).

[0025] The type of communication between the base station 30 and the packet receiving device 20 and between the base station 31 and the packet receiving device 20 is not particularly limited, but may be, for example, a backbone line of a telecommunications carrier, the Internet, or a LAN for in-house connection. Alternatively, wireless communication lines and wired communication lines may be mixed. Alternatively, the wide area communication line or the narrow area communication line may be wireless communication that directly connects the packet transmitting device 10 and the packet receiving device 20 without going through the base station 31 or the base station 32 .

[0026] The packet transmitting device 10 is a device that transmits a "data packet" to the packet receiving device 20 using a wide area communication line and a narrow area communication line. Here, a "data packet" is a data unit for communication, and may be of variable length or fixed length. For example, when a data packet is a TCP segment, the data packet may be a variable-length packet of up to 1460 bytes. The name of the data packet is arbitrary. For example, it may be called a frame, subframe, subblock, etc., in addition to a packet.

[0027] Specifically, the packet transmitting device 10 sets either the wide area communication line or the narrow area communication line as the main communication line and the other as the sub-communication line, transmits packets from the main communication line without thinning them out, and transmits packets from the sub-communication line with thinning them out. For example, in FIG. 1, when the wide area communication line is set as the main communication line and the narrow area communication line is set as the sub-communication line, all packets consisting of P1 to P9 are transmitted from the wide area communication line, and only packets P1, P4, and P7 of the data packets are transmitted from the narrow area communication line. Also, in FIG. 1, when the wide area communication line is set as the sub-communication line and the narrow area communication line is set as the main communication line, only packets P1, P3, P5, P7, and P9 of the data packets are transmitted from the wide area communication line, and all packets consisting of P1 to P9 are transmitted from the narrow area communication line.

[0028] The packet receiving device 20 receives a data packet from the packet transmitting device 10, and transmits an Ack packet to the packet transmitting device 10 as an acknowledgement.

[0029] In this embodiment, the packet transmitting device 10 is "mounted" on a "mobile body". However, it may be mounted on a fixed object instead of a mobile body. The packet receiving device 20 is assumed to be a server device in a data center, but is not limited thereto, and may be "mounted" on a "mobile body", for example. Where: "Mobile object" refers to an object that can move and can move at any speed. It also includes cases where the mobile object is stationary. For example, it includes, but is not limited to, automobiles, motorcycles, bicycles, pedestrians, ships, aircraft, and objects mounted on these. "Mounted" includes not only the case where it is directly fixed to the moving body, but also the case where it is not fixed to the moving body but moves with the moving body. For example, it can be carried by a person riding on the moving body, or it can be mounted on cargo placed on the moving body.

[0030] (2) Configuration of Packet Transmitting Device 10 The configuration of the packet transmitting device 10 of this embodiment will be described with reference to FIG. The packet transmitting device 10 includes a packet storage unit 101, a communication state determination unit 102, a main / subline setting unit 103, a transmission packet generation unit 104, a transmission instruction unit 105, a wide area communication unit 106, and a narrow area communication unit 107. The wide area communication unit 106 transmits and receives data packets, etc., using a wide area communication line, and the narrow area communication unit 107 transmits and receives data packets, etc., using a narrow area communication line.

[0031] The packet storage unit 101 stores data packets to be transmitted to the packet receiving device 20. The packet storage unit 101 can be realized by any readable and writable recording medium, for example, a RAM, various semiconductor memories, a hard disk, etc. Also, it may be configured by either a non-volatile memory or a volatile memory.

[0032] The communication status determination unit 102 determines the communication status of the narrow area communication line. Specifically, it determines whether the communication status of the narrow area communication line is good or bad by using an Ack packet that is an acknowledgement of a data packet transmitted through the narrow area communication line. The Ack packet itself may be transmitted through the narrow area communication line or through a wide area communication line. A specific determination method of the communication state determination unit 102 will be described in the section on the operation of the packet transmitting device 10. A specific example of an Ack packet will be described in the sections on the wide area communication unit 106 and the short area communication unit 107.

[0033] Based on the determination of the communication state determination unit 102, the main / sub-line setting unit 103 sets either the wide area communication line or the narrow area communication line as the main communication line, and sets the other as the sub-communication line. A specific setting method of the main and sub-channel setting unit 103 will be explained in the section on the operation of the packet transmitting device 10.

[0034] The transmission packet generating unit 104 generates a main data packet that is not subjected to "bandwidth limiting processing" and a sub data packet that is subjected to "bandwidth limiting processing" from the data packets stored in the packet storage unit 101. In this embodiment, the bandwidth limiting processing is a policing process that thins out data packets on a packet-by-packet basis within a specified bandwidth. Here, "bandwidth limiting processing" refers to processing that reduces the amount of data communication per unit time, and may be policing, which discards some of the data packets, or shaping, which accumulates data packets in a buffer and delays their transmission time.

[0035] 3 is a diagram showing a data packet, and a main data packet and a sub data packet generated from the data packet. In the following description, a data packet basically means a set of individual packets, but does not prevent an individual packet from being interpreted as a data packet. Fig. 3(a) shows data packets stored in packet storage unit 101. In Fig. 3(a), the data packets consist of nine packets #1 to #9, which are stored in the order in which they are transmitted from the main communication line. Note that the number attached to # is a sequence number, and indicates the transmission order excluding retransmissions. Fig. 3(b) shows a main data packet. Since the main data packet is not subjected to band limiting processing, it contains all packets #1 to #9. The main data packet has the same packet structure whether it is transmitted over a wide area communication line or a narrow area communication line.

[0036] Fig. 3(c1) shows a secondary data packet transmitted over a wide-area communication line. The secondary data packet has been subjected to policing processing, so data packets have been thinned out. In Fig. 3(c1), packets #1, #3, #5, #7, and #9 are included, and packets #2, #4, #6, and #8 have been thinned out. It is desirable to perform policing at a relatively wide bandwidth, for example, about 10 Mbps. The degree of policing may be fixed or variable. It is desirable to monitor the communication status of the wide area communication line and perform policing to the extent that congestion does not occur. Packets to be thinned out by the policing process may be selected randomly. Alternatively, specific packets may be selected. For example, if the packet size of the packets is variable, packets having a packet size larger than a predetermined size may be thinned out.

[0037] Fig. 3(c2) shows a secondary data packet transmitted over a narrow area communication line. The secondary data packet has been subjected to policing processing, so that the data packets have been thinned out. In Fig. 3(c2), packets #1, #4, and #7 are included, and packets #2, #3, #5, #6, #8, and #9 have been thinned out. That is, in the policing processing, when the narrow area communication line is the secondary communication line, the degree of thinning is greater than when the wide area communication line is the secondary communication line. Which line the secondary data packet is transmitted over, i.e., which line the secondary data packet to be transmitted over is generated, can be determined based on the setting of the main and secondary line setting unit 103. It is desirable to perform policing in a relatively narrow band, for example, about 1 Mbps or 128 Kbps. The degree of policing may be fixed or variable. Packets to be thinned out by the policing process may be selected randomly. Alternatively, specific packets may be selected. For example, if the packet size of the packets is variable, packets having a packet size larger than a predetermined size may be thinned out.

[0038] The transmission packet generation unit 104 can determine whether the policing process (c1) or (c2) is to be performed by receiving the setting of the main and sub-line setting unit 103. That is, the transmission packet generation unit 104 can know from the setting of the main and sub-line setting unit 103 whether the sub data packet is to be transmitted through the wide area communication line or the narrow area communication line. Of course, it is also possible to generate a secondary data packet that has been subjected to policing in each of (c1) and (c2) without receiving the setting from the main secondary line setting unit 103.

[0039] 3(d) shows each packet included in the main data packet and the sub data packet. In addition to a sequence number, each packet stores line type 1 (i.e., whether to transmit via a wide area communication line or a narrow area communication line), line type 2 (i.e., whether to transmit via a main communication line or a sub communication line), payload size, and payload. Line type 1 and line type 2 are determined based on the setting of the main and sub line setting unit 103.

[0040] The transmission instruction unit 105 instructs the wide area communication unit 106 and the narrow area communication unit 107 to transmit the main data packet generated by the transmission packet generation unit 104 through the main communication line and the sub data packet through the sub communication line. Based on the setting of the main and sub line setting unit 103, the transmission instruction unit 105 instructs the wide area communication unit 106 and the narrow area communication unit 107 which of the wide area communication unit 106 and the narrow area communication unit 107 will be the main communication line and the other will be the sub communication line.

[0041] The transmitting section of the wide area communication unit 106 (corresponding to the “first communication unit”) transmits a main data packet when the wide area communication line is the main communication line, and transmits a secondary data packet when the wide area communication line is the secondary communication line, based on instructions from the transmission instruction unit 105. The transmitting section of the short-range communication unit 107 (corresponding to the "second communication unit") transmits a main data packet when the short-range communication line is the main communication line, and transmits a sub-data packet when the short-range communication line is the sub-communication line, based on an instruction from the transmission instruction unit 105. Note that when the short-range communication line is the sub-communication line, the communication conditions of the short-range communication line are poor, so that the sub-data packet cannot be transmitted and only a transmission command is output; however, in this embodiment, outputting a transmission command is also expressed as "transmitting". As described above, when comparing secondary data packets when a wide area communication line is the secondary communication line and secondary data packets when a narrow area communication line is the secondary communication line, the degree to which packets are thinned out differs. It should be noted that what the packet transmitting device 10 transmits is a main data packet and a sub-data packet, but since the main data packet contains all the packets that make up the data packet, the transmission target of the packet transmitting device 10 can be evaluated as a data packet.

[0042] The receiving section of the wide area communication section 106 and the receiving section of the short range communication section 107 receive, from the packet receiving device 20, an Ack packet which is an acknowledgement response to a packet transmitted by each transmitting section.

[0043] FIG. 4A is a diagram showing an Ack packet according to the present embodiment. The line type 1 and line type 2 indicate the type of line that transmitted the packet that triggers the generation of the Ack packet, and are the same as those in FIG. 3(d). The maximum received sequence number indicates the maximum sequence number of packets already received by packet receiving device 20. The previous Ack maximum sequence number indicates the previous received maximum sequence number when the packet receiving device 20 transmitted an Ack packet. The receive sequence number is the sequence number of the packet that triggered the generation of this Ack packet. If the packet receiving device 20 is able to receive packets in the order of the sequence numbers, the maximum received sequence number and the receive sequence number will be the same number, but due to the influence of line delays and the like, they may not be the same. The unreceived sequence number is the sequence number of a packet that has not yet been received by packet receiving device 20. If there are multiple packets that have not yet been received, multiple sequence numbers are stored. For example, if packet receiving device 20 receives packets #1, #3, #4, #5, and #9, the Ack packet it sends upon receiving packet #9 will contain #9 as the maximum received sequence number, #5 as the maximum previously Ack'd sequence number, #9 as the received sequence number, and #2, #6, #7, and #8 as unreceived sequence numbers.

[0044] In this embodiment, the Ack packet for the wide area communication line and the Ack packet for the narrow area communication line are configured to store the packet reception status for each line, but the Ack packet may be configured to store the reception status for these lines collectively.

[0045] For example, as shown in FIG. 4(b), the Ack use line type indicating the type of line through which the Ack packet is transmitted (i.e., whether it is a wide area communication line or a narrow area communication line), the received sequence number, the maximum received sequence number, the main line unreceived sequence number indicating the sequence number of a packet not yet received on the line through which the Ack packet is transmitted, and the other line unreceived sequence number indicating the sequence number of a packet not yet received on a line different from the line through which the Ack packet is transmitted may be stored.

[0046] (3) Operation of the Packet Transmitting Device 10 The operation of the packet transmitting device 10 of this embodiment will be described with reference to FIG. 5 to FIG. The following operations not only show a packet transmission method in the packet transmitting device 10, but also show the processing procedure of a packet transmission program executed by the packet transmitting device 10. These operations or processes are not limited to the order shown in Figures 5 to 11. In other words, the order may be changed as long as there is no constraint such as a relationship in which a certain step utilizes the result of the previous step. The above applies not only to this embodiment, but also to other embodiments and modified examples.

[0047] (a) Main flow (main routine) First, a main flow of the operation of the packet transmitting device 10 of this embodiment will be described with reference to FIG.

[0048] The communication status determination unit 102 determines the communication status of the narrow area communication line (S101). Specifically, it determines whether the communication status of the narrow area communication line is good or bad based on an Ack packet received by the receiving unit of the narrow area communication unit 107. A specific flow of S101 will be described later with reference to FIG.

[0049] Based on the determination in S101, the main and sub-line setting unit 103 sets either the wide area communication line or the narrow area communication line as the main communication line and the other as the sub-communication line (S102). A specific flow of S102 will be described later with reference to FIG.

[0050] The transmission packet generating unit 104 generates (S103) a main data packet that is not subjected to "bandwidth limiting processing" and a sub data packet that is subjected to "bandwidth limiting processing" from the data packets stored in the packet storage unit 101. A specific flow of S103 will be described later with reference to FIG.

[0051] The transmission instruction unit 105 instructs the wide area communication unit 106 and the local area communication unit 107 to transmit the main data packet generated by the transmission packet generation unit 104 through the main communication line and the sub data packet through the sub communication line (S104). A specific flow of S104 will be described later with reference to FIG.

[0052] Based on the instruction in S104, the wide area communication unit 106 transmits the main data packet or the secondary data packet using the wide area communication line, and the short range communication unit 107 transmits the secondary data packet or the main data packet using the second communication line (S105).

[0053] The above process is repeated every time a data packet consisting of a predetermined number of packets is stored in packet storage unit 101.

[0054] (b) Determining the communication state of the narrow area communication line (subroutine of S101) A method for determining the communication state of a narrow area communication line will be described with reference to FIG. 6 and FIG.

[0055] FIG. 6 shows the reception status of an Ack packet on a narrow area communication line. 6(a) shows a case where the narrow area communication line is the main communication line. The transmission section of the narrow area communication unit 107 transmits a main data packet that has not been subjected to policing processing, and the reception section of the narrow area communication unit 107 receives an Ack packet for the packet transmitted from the transmission section from the packet reception device 20. In the figure, ◯ indicates that an Ack packet has been received, and × indicates that an Ack packet has not been received.

[0056] The communication status determination unit 102 determines that the communication status is good if an Ack packet is received, and determines that the communication status is poor if an Ack packet is not received for a predetermined time (Δt). For example, the predetermined time is the elapsed time from the transmission of a packet. In FIG. 6(a), the communication status is determined to be poor if a predetermined time (Δt) has elapsed from t5, which is the time when #5 was transmitted. The reason for waiting for the passage of a predetermined time before making a judgment is to exclude cases where a communication delay of an acceptable degree has occurred.

[0057] As another example of the predetermined time, it may be a case where a predetermined number of Ack packets are not received. In Fig. 6(a), when Ack packets for two packets #5 and #6 are not received, it is determined that the communication state is poor. The reason why a predetermined number of Ack packets are not received is to exclude cases where there is no problem with the communication state but the cause is packet loss.

[0058] 6B shows a case where the narrow area communication line is a secondary communication line. The transmission unit of the narrow area communication unit 107 transmits a secondary data packet that has been subjected to policing processing, and the reception unit of the narrow area communication unit 107 receives an Ack packet from the packet reception device 20 in response to the packet transmitted from the transmission unit.

[0059] The communication status determination unit 102 determines that the communication status is good when an Ack packet is received, and determines that the communication status is bad when no Ack packet is received for a predetermined time (Δt). In FIG. 6(b), the communication status is determined to be good when an Ack packet for #7 is received.

[0060] FIG. 7 is a flow chart showing a method for determining the communication state of a narrow area communication line. The communication state determination unit 102 determines whether or not an Ack packet for a packet transmitted from the transmission unit of the short range communication unit 107 has been received from the packet reception device 20 (S151). If it has been received, the process proceeds to S152, and if it has not been received, the process proceeds to S153.

[0061] If an Ack packet is received, the communication state determining unit 102 determines that the communication state of the narrow area communication line is good (S152).

[0062] If an Ack packet has not been received, the communication status determination unit 102 determines whether or not a predetermined time has elapsed since the packet was transmitted (S153). If the predetermined time has not elapsed, the process proceeds to S152, and if the predetermined time has elapsed, the process proceeds to S154.

[0063] If the predetermined time has elapsed, the communication state determining unit 102 determines that the communication state of the narrow area communication line is poor (S154).

[0064] (c) Setting of the main communication line and the sub-communication line (subroutine of S102) A method for setting the main communication line and the sub-communication line will be described with reference to FIGS.

[0065] FIG. 8 shows the reception status of Ack packets on a wide area communication line and a narrow area communication line. FIG. 8(a) shows a case where a narrow area communication line is a main communication line and a wide area communication line is a secondary communication line, and then the wide area communication line is switched to the main communication line and the narrow area communication line is switched to the secondary communication line. Initially, since the narrow area communication line is the main communication line, the transmission unit of the narrow area communication unit 107 transmits a main data packet that has not been subjected to policing. Also, since the wide area communication line is the secondary communication line, the transmission unit of the wide area communication unit 106 transmits a secondary data packet that has been subjected to policing. In this case, since both the narrow area communication line and the wide area communication line are capable of communication, the reception unit of the wide area communication unit 106 and the reception unit of the narrow area communication unit 107 both receive Ack packets for the data packets transmitted from the respective transmission units.

[0066] If the receiving section of the short-range communication unit 107 does not receive the Ack packets of #5 and #6, the communication state judgment section 102 determines that the communication state of the short-range communication line is poor since no Ack packets have been received for a predetermined time. In response to this, the main / sub-line setting section 103 sets the wide-area communication line as the main communication line and the short-area communication line as the sub-communication line (i.e., switches). After the switch, the transmitting section of the short-range communication unit 107 transmits a sub-data packet that has been subjected to policing, but does not receive an Ack packet because the communication state is poor. In response to this, the transmitting section of the wide-area communication unit 106 transmits a main data packet that has not been subjected to policing and receives an Ack packet.

[0067] In the policing process when the narrow area communication line is the secondary communication line, the degree of packet thinning is greater than that when the wide area communication line is the secondary communication line. This is because when the narrow area communication line is the secondary communication line, the communication state is poor and the transmitted packets are less likely to reach the packet receiving device 20. Also, this is because it is sufficient to detect when the communication state of the narrow area communication line has changed to good. In this way, when a narrow area communication line is a secondary communication line, by transmitting a secondary data packet subjected to policing processing, a resource request for securing a data bandwidth in the narrow area communication line is periodically made, so that it is possible to quickly detect that the narrow area communication line has entered an available range. As a result, it is possible to quickly connect to a narrow area communication line, which generally has a margin in communication speed and communication capacity.

[0068] In addition, when the communication state determination unit 102 determines that the communication state of the narrow area communication line is poor, the transmission instruction unit 105 may instruct the transmitting unit of the wide area communication unit 106, which communicates through the wide area communication line switched to the main communication line, to retransmit data packets that have been transmitted from the transmitting unit of the narrow area communication unit 107 through the narrow area communication line but have not yet received an Ack packet. In the case of Fig. 8(a), the transmission instruction unit 105 instructs the transmitting unit of the wide area communication unit 106 to transmit packets #5 and #6. However, since packet #5 has already been transmitted as a secondary data packet on the wide area communication line set as the secondary communication line and has already been received by packet receiving device 20, it is possible to instruct packet #5 not to be retransmitted and to transmit only packet #6.

[0069] FIG. 8(b) shows a case where the wide area communication line is the main communication line and the narrow area communication line is the secondary communication line, and then the wide area communication line is switched to the secondary communication line and the narrow area communication line is switched to the main communication line. When the receiving section of the short-range communication unit 107 receives the Ack packet of #7, the communication state determination section 102 determines that the communication state of the short-range area communication line is good. In response to this, the main and sub-line setting section 103 sets the wide-area communication line as the sub-communication line and the short-area communication line as the main communication line (i.e., switches). After the switch, the transmitting section of the short-range communication unit 107 transmits main data packets that have not been subjected to policing, but receives an Ack packet because the communication state is good. The transmitting section of the wide-area communication unit 106 transmits sub data packets that have been subjected to policing, and receives an Ack packet.

[0070] In the policing process when the wide-area communication line is the secondary communication line, the degree of packet thinning is smaller than in the case when the narrow-area communication line is the secondary communication line. This is because the packet loss caused by the disconnection of the narrow-area communication line is compensated for by redundant transmission on the wide-area communication line, and retransmission processing is minimized. In this case, it is desirable to perform the policing process to the extent that the wide-area communication line does not become congested. In this way, when the wide area communication line is the secondary communication line, the secondary data packet that has been subjected to the policing process is transmitted, so that the packet loss caused by the disconnection of the narrow area communication line can be compensated for. Also, the retransmission process caused by the disconnection of the narrow area communication line can be minimized.

[0071] FIG. 9 is a flow chart showing a method for setting a main communication line and a secondary communication line. The main / subline setting unit 103 judges whether the current main communication line is a narrow area communication line (S161). If it is a narrow area communication line, the process proceeds to S162, and if it is not a narrow area communication line but a wide area communication line, the process proceeds to S163.

[0072] When the main communication line is a narrow area communication line, the communication state determination unit 102 checks whether the communication state of the narrow area communication line is good or bad (S162). When it is judged to be good, the main and sub-line setting unit 103 maintains the narrow area communication line as the main communication line and ends the process. When it is judged to be bad, the main and sub-line setting unit 103 sets the wide area communication line as the main communication line and sets the narrow area communication line as the sub-communication line (i.e., switches) (S164). Then, the transmission instruction unit 105 instructs the transmitting unit of the wide area communication unit 106 to retransmit, via the wide area communication line, packets that have been transmitted via the narrow area communication line but for which no Ack packet has been received (S165).

[0073] If the main communication line is not a narrow area communication line, i.e., if it is a wide area communication line, the communication state determination unit 102 checks whether it has determined the communication state of the narrow area communication line to be good or bad (S163). If it is determined to be bad, the main and sub-line setting unit 103 maintains the wide area communication line as the main communication line and ends the process. If it is determined to be good, the main and sub-line setting unit 103 sets the narrow area communication line as the main communication line and sets the wide area communication line as the sub-communication line (i.e., switches) (S166).

[0074] (d) Generation of main data packets and secondary data packets (subroutine of S103) A method for generating a main data packet and a sub data packet will be described with reference to FIG. FIG. 10 is a flow diagram showing a method for generating a primary data packet and a secondary data packet. The transmission packet generator 104 generates a copy of the data packet stored in the packet storage unit 101 (S171). The transmission packet generating unit 104 checks whether the main communication line set by the main / subline setting unit 103 is a narrow area communication line (S172). If the main communication line is a narrow area communication line, the process proceeds to S172, and if the main communication line is not a narrow area communication line, i.e., if the main communication line is a wide area communication line, the process proceeds to S175.

[0075] When the main communication line is a narrow area communication line, the transmission packet generating unit 104 generates a main data packet to be transmitted on the narrow area communication line (S173). Specifically, as explained in Fig. 3(b), a main data packet that is not subjected to policing processing is generated from the data packet, and the necessary information explained in Fig. 3(d) is stored in the packet header. The transmission packet generating unit 104 generates a sub-data packet to be transmitted through the wide area communication line (S174). Specifically, as explained in Fig. 3(c1), a sub-data packet is generated by performing policing processing from the data packet, and the necessary information explained in Fig. 3(d) is stored in the header of the packet.

[0076] When the main communication line is a wide area communication line, the transmission packet generating unit 104 generates a main data packet to be transmitted on the wide area communication line (S175). Specifically, as explained in Fig. 3(b), a main data packet that is not subjected to policing processing is generated from the data packet, and the necessary information explained in Fig. 3(d) is stored in the header of the packet. The transmission packet generating unit 104 generates a sub-data packet to be transmitted through the narrow area communication line (S176). Specifically, as explained in Fig. 3(c2), a sub-data packet is generated by performing policing processing from the data packet, and the necessary information explained in Fig. 3(d) is stored in the header of the packet.

[0077] (e) Transmission instruction for main data packet and sub data packet (subroutine of S104) A method of issuing a transmission instruction for a main data packet and a sub data packet will be described with reference to FIG. FIG. 11 is a flow chart showing a method for instructing transmission of a main data packet and a sub data packet. The transmission instruction unit 105 checks whether the main communication line set by the main / subline setting unit 103 is a narrow area communication line (S181). If the main communication line is a narrow area communication line, the process proceeds to S182, and if the main communication line is not a narrow area communication line, i.e., if the main communication line is a wide area communication line, the process proceeds to S184.

[0078] If the main communication line is a narrow area communication line, the transmission instruction unit 105 instructs the transmitting unit of the narrow area communication unit 107 to transmit a main data packet (S182). Also, the transmission instruction unit 105 instructs the transmitting unit of the wide area communication unit 106 to transmit a sub data packet (S183).

[0079] If the main communication line is a wide area communication line, the transmission instruction unit 105 instructs the transmitting unit of the wide area communication unit 106 to transmit a main data packet (S184). Also, the transmission instruction unit 105 instructs the transmitting unit of the short range communication unit 107 to transmit a sub data packet (S183).

[0080] (4) Summary As described above, according to this embodiment, multiple communication lines are used to transmit main data packets from one side and sub data packets from the other side, so that the transmitted data packets can have redundancy. As a result, packet loss can be suppressed and frequent retransmission can be prevented. In addition, the maximum throughput can enjoy the performance of a narrow area communication line while maintaining the high connectivity of a wide area communication line. More specifically, according to this embodiment, even if the communication state of the narrow area communication line is poor, the sub data packet is transmitted using the narrow area communication line, so that it is possible to quickly detect that the communication state of the narrow area communication line has improved, and to more quickly connect the narrow area communication line. Also, according to this embodiment, even if the communication state of the narrow area communication line is good, the sub data is transmitted using the wide area communication line, so that it is possible to compensate for packet loss that occurs when the narrow area communication line becomes poor.

[0081] (5) Configuration of the Packet Receiving Device 20 The configuration of a packet receiving device 20 of this embodiment will be described with reference to FIG. The packet receiving device 20 includes a communication unit 201 , a narrow area communication line packet storage unit 202 , a wide area communication line packet storage unit 203 , an unreceived packet information generation unit 204 , an Ack packet generation unit 205 , and a transmission instruction unit 206 .

[0082] The receiving section of the communication unit 201 receives a main data packet or a sub data packet transmitted from the packet transmitting device 10 using a wide area communication line or a narrow area communication line. As described in FIG. 1, the communication unit 201 does not have to be a device that directly receives wireless communication of the wide area communication line or the narrow area communication line. The transmitting section of the communication unit 201 transmits an Ack packet to the packet transmitting device 10 based on an instruction from a transmission instruction section 206, which will be described later.

[0083] The packet storage unit 202 for narrow area communication line stores the main data packet or the sub data packet transmitted through the narrow area communication line. The fact that the data packet was transmitted through the narrow area communication line can be determined based on the line type 1 of the data packet in FIG. 3(d).

[0084] The wide-area communication line packet storage unit 203 stores the main data packet or the sub data packet transmitted through the wide-area communication line. The fact that the data packet has been transmitted through the wide-area communication line can be determined based on the line type 1 of the data packet in FIG. 3(d).

[0085] The unreceived packet information generating unit 204 acquires the unreceived status of the main data packets and the sub data packets transmitted through the narrow area communication line and the wide area communication line. For example, Based on the sequence number of the data packet in FIG. 3(d) and line type 2, a data packet with a sequence number smaller than the currently received sequence number and which has not been received by the receiving section of communication section 201 is determined to be an unreceived packet. Although the unreceived packets may be determined based on the sequence number of the main data packet transmitted on the main communication line, it is preferable to exclude the already received sub-data packets from the unreceived packets. In particular, when the sub-data packets are transmitted on the wide area communication line, they can be transmitted with redundancy, so that packet loss can be minimized.

[0086] The Ack packet generator 205 generates an Ack packet for a main data packet or a sub data packet transmitted over a wide area communication line or a narrow area communication line. An example of the Ack packet is as shown in FIG.

[0087] The transmission instruction unit 206 instructs the transmitting unit of the communication unit 201 to transmit an Ack packet. Note that the Ack packet is instructed to be transmitted over the communication line through which the received data packet was transmitted, but may be instructed to be transmitted over both the wide area communication line and the narrow area communication line regardless of the type of the communication line through which the received data packet was transmitted.

[0088] 2. Other embodiments As another embodiment, the packet transmitting device 10 or the packet receiving device 20 may have the following configurations and features.

[0089] The wide area communication line or the narrow area communication line may each use multiple channels instead of a single channel. For example, the packet transmitting device 10 may use eight channels as the wide area communication line and transmit the main data packet divided into eight. This can increase the effective transmission speed of each communication line.

[0090] Furthermore, data for FEC (Forward Error Correction) may be added to the main data packet or the sub data packet transmitted from the packet transmitting device 10. FEC data may be added only to a narrow area communication line that has a high communication speed but a narrow communication area. In this way, even if a part of the main data packet is lost, the lost main data packet can be corrected or modified by FEC, so there is no need to request a retransmission.

[0091] The packet transmitting device 10 may have the functions of the packet receiving device 20. Also, the packet receiving device 20 may have the functions of the packet transmitting device 10.

[0092] In this embodiment, the number of communication lines is two, but it may be three or more. It is sufficient that two of the lines have the relationship as described in this embodiment. Furthermore, the wide area communication line and the narrow area communication line may each use a plurality of lines. In this case, the plurality of lines can be collectively evaluated as the wide area communication line and the narrow area communication line of the present embodiment.

[0093] 3. Summary The features of the packet transmitting device, the packet receiving device, and the communication system in each embodiment of the present invention have been described above.

[0094] The terms used in each embodiment are merely examples and may be replaced with synonymous terms or terms having the same functions.

[0095] The block diagrams used to explain the embodiments classify and organize the configuration of the device by function. The blocks showing the respective functions are realized by any combination of hardware or software. In addition, since the block diagrams show the functions, they can also be understood as disclosures of a method invention and a program invention that realizes the method.

[0096] The order of the functional blocks that can be understood as the processes, flows, and methods described in each embodiment may be changed as long as there are no constraints such as a relationship in which one step utilizes the results of another step prior to it.

[0097] The terms first, second, through Nth (N is an integer) used in each embodiment and in the claims are used to distinguish two or more configurations or methods of the same type, and do not limit the order or superiority or inferiority.

[0098] Each embodiment is based on an apparatus mounted on a vehicle, but the present invention also includes dedicated or general-purpose apparatuses other than those for use in vehicles, unless otherwise limited by the claims.

[0099] In each embodiment, the device disclosed in each embodiment has been described on the assumption that it is mounted on a vehicle, but it may also be carried by a pedestrian.

[0100] Examples of the form of the device of the present invention are as follows. Examples of the component include a semiconductor element, a semiconductor circuit, an electronic circuit, a module, and a microcomputer. Examples of semi-finished products include an electronic control unit (ECU), an electronic control unit, and a system board. Finished product forms include mobile phones, smartphones, mobile routers, tablets, personal computers (PCs), workstations, and servers. Other examples include devices with communication functions, such as video cameras, still cameras, and car navigation systems.

[0101] Additionally, necessary functions such as an antenna and a communication interface may be added to the device.

[0102] It is envisioned that the device of the present invention will be used for the purpose of providing various services, and the device of the present invention will be used, the method of the present invention will be used, and / or the program of the present invention will be executed in conjunction with the provision of such services.

[0103] In addition, the present invention can be realized not only by dedicated hardware having the configuration and functions described in each embodiment, but also as a combination of a program for realizing the present invention recorded on a recording medium such as a memory or a hard disk, and general-purpose hardware having a dedicated or general-purpose CPU and memory capable of executing the program.

[0104] A program for the device of the present invention, which is stored in a non-transient substantial recording medium (for example, an external storage device (hard disk, USB memory, CD / BD, etc.) or an internal storage device (RAM, ROM, etc.)) of dedicated or general-purpose hardware, can also be provided to the dedicated or general-purpose hardware via the recording medium, or via a communication line from a server without using a recording medium. This makes it possible to always provide the latest functions through program upgrades. [Industrial Applicability]

[0105] The packet transmitting device of the present invention is a packet transmitting device that communicates using multiple communication lines and can be widely applied to communications while a vehicle is parked or traveling, communications on ships or aircraft, or communications handling large amounts of data at fixed facilities. [Explanation of symbols]

[0106] 10 packet transmitting device, 101 packet storage unit, 102 communication state determination unit, 103 main / sub-line setting unit, 104 transmission packet generating unit, 105 transmission instruction unit, 106 wide-area communication unit, 106 narrow-area communication unit, 20 packet receiving device

Claims

1. A packet transmitting device (10) that transmits a data packet to a packet receiving device (20) using a first communication line and a second communication line having a narrower communication coverage area than the first communication line, A packet storage unit (101) for storing the data packet; a communication state determination unit (102) for determining a communication state of the second communication line; a main / sub-line setting unit (103) that sets either the first communication line or the second communication line as a main communication line and the other as a sub-communication line based on a determination by the communication state determination unit; a transmission packet generating unit (104) for generating a main data packet not subjected to band limiting processing and a sub data packet subjected to band limiting processing from the data packet; a transmission instruction unit (105) for instructing transmission of the main data packet over the main communication line and the sub data packet over the sub communication line; a first communication unit (106) for transmitting the main data packet or the auxiliary data packet using the first communication line based on an instruction from the transmission instruction unit, and a second communication unit (107) for transmitting the auxiliary data packet or the main data packet using the second communication line, Packet sending device.

2. the communication state determination unit determines a communication state of the second communication line based on an acknowledgement transmitted from the packet receiving device that has received the main data packet or the sub data packet.

2. The packet transmitting device according to claim 1.

3. the communication state determination unit determines that the communication state is poor when the acknowledgement is not received within a predetermined time period after the main data packet is transmitted.

3. The packet transmitting device according to claim 2.

4. The bandwidth limiting process is a policing process that thins out the data packets on a packet-by-packet basis.

2. The packet transmitting device according to claim 1.

5. In the policing process, when the second communication line is the secondary communication line, a degree of thinning is larger than when the first communication line is the secondary communication line.

5. The packet transmitting device according to claim 4.

6. When the communication state determination unit determines that the communication state of the second communication line is poor, the transmission instruction unit instructs the first communication unit to transmit the data packet for which the acknowledgement has not been received despite being transmitted from the second communication unit; 4. The packet transmitting device according to claim 3.

7. When the communication state determination unit determines that the communication state of the second communication line is poor, the transmission instruction unit instructs the first communication unit to transmit the data packet that has been transmitted from the second communication unit but for which the confirmation response has not been received and that has not been transmitted from the first communication unit in the past.

4. The packet transmitting device according to claim 3.

8. The packet transmission device is mounted on a moving object. The packet transmitting device according to any one of claims 1 to 7.

9. A packet transmission method executed by a packet transmission device (10) for transmitting a data packet to a packet reception device (20) using a first communication line and a second communication line having a narrower communication coverage area than the first communication line, comprising: A communication state of the second communication line is determined (S101); Based on the judgment of the communication state, either the first communication line or the second communication line is set as a main communication line, and the other is set as a sub-communication line (S102); A main data packet that is not subjected to the band limiting process and a sub data packet that is subjected to the band limiting process are generated from the data packets stored in the packet storage unit (101) (S103); instructing to transmit the main data packet through the main communication line and the sub data packet through the sub communication line (S104); transmitting the main data packet or the auxiliary data packet using the first communication line and transmitting the auxiliary data packet or the main data packet using the second communication line based on the instruction (S105); Packet transmission method.

10. A packet transmission program executable by a packet transmission device (10) for transmitting a data packet to a packet reception device (20) using a first communication line and a second communication line having a narrower communication coverage area than the first communication line, the program comprising: A communication state of the second communication line is determined (S101); Based on the judgment of the communication state, either the first communication line or the second communication line is set as a main communication line, and the other is set as a sub-communication line (S102); A main data packet that is not subjected to the band limiting process and a sub data packet that is subjected to the band limiting process are generated from the data packets stored in the packet storage unit (101) (S103); instructing to transmit the main data packet through the main communication line and the sub data packet through the sub communication line (S104); transmitting the main data packet or the auxiliary data packet using the first communication line and transmitting the auxiliary data packet or the main data packet using the second communication line based on the instruction (S105); Packet sending program.

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