Ship-to-land communication line simulator and ship-to-land communication evaluation system

Abstract

To provide a ship-to-land communication line simulator capable of simulating a plurality of ship-to-land communication lines, and a ship-to-land communication evaluation system for evaluating ship-to-land communication.SOLUTION: A ship-to-land communication line simulator 8 includes a pseudo-communication line unit 81 that communicates in accordance with set communication conditions when the communication conditions including at least one of communication speed, communication delay time, and packet loss are set, and a communication control unit 82 that sets, in the pseudo-communication line unit 81, communication conditions according to a ship-to-land communication line to be simulated. By performing communication between a test computer 7 and a test server 8, it is possible to evaluate the ship-to-land communication line on a desk.SELECTED DRAWING: Figure 2

Description

[Technical Field]

[0001] The present invention relates to a ship-to-shore communication line simulator used to simulate multiple ship-to-shore communication lines connecting an onboard network and a server at a land facility, and a ship-to-shore communication evaluation system for evaluating ship-to-shore communications. [Background technology]

[0002] For communication between a ship and a land facility, multiple ship-to-land communication lines are used, which are switched appropriately depending on the ship's operational status, the purpose of the communication, etc. (See, for example, Patent Document 1.) For example, when a ship is sailing on the open ocean, a satellite line that allows stable communication is used, and when the ship is sailing along the coast, a mobile phone communication line (for example, LTE: Long Term Evolution) that has low communication costs and is high speed is used.

[0003] In addition, satellite circuits use various satellites, such as geostationary high earth orbit (GEO), medium earth orbit (MEO), and low earth orbit (LEO), which can be switched as needed. Although geostationary high earth orbit (GEO) satellites have a large latency, communication can be achieved simply by tracking satellites that always exist in the same direction, making it relatively easy to build a stable communication system. In contrast, low earth orbit (LEO) satellites have a small latency, but communication requires switching between multiple satellites to overcome communication blockages, making it more difficult to build a stable communication system. However, with the increase in the number of satellites and improvements in tracking technology in recent years, these issues are being largely resolved. However, there are still areas where the service is not permitted and communication is not possible, so a switching system is required. Medium earth orbit (MEO) satellites have a latency somewhere between that of low earth orbit (LEO) satellites and geostationary high earth orbit (LEO) satellites. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] Japanese Patent Application Laid-Open No. 2014-075627 Summary of the Invention [Problem to be solved by the invention]

[0005] Previously, to evaluate a ship-to-shore communication system that uses multiple ship-to-shore communication lines, it was necessary to conduct field tests using an actual ship. This resulted in problems with the time and cost involved in the evaluation. Furthermore, because switching between ship-to-shore communication lines depends on factors such as route conditions, there are some conditions that cannot be evaluated (for example, testing a coastal-to-offshore satellite switchover test on a coastal route such as the Seto Inland Sea). This makes it difficult to perform repeated evaluations, full-pattern evaluations that switch between all communication lines, or evaluations near the limit at which communication lines switch.

[0006] Therefore, an object of the present invention is to provide a ship-to-shore communication line simulator capable of simulating multiple ship-to-shore communication lines, and a ship-to-shore communication evaluation system for evaluating ship-to-shore communications. [Means for solving the problem]

[0007] In order to solve the above problem, the invention described in claim 1 is a ship-to-shore communication line simulator used to simulate multiple ship-to-shore communication lines connecting an in-ship network installed on a ship and a server installed at a land facility, characterized in that it comprises: a pseudo-communication line means that, when communication conditions including at least one of communication speed, communication delay time, and packet loss are set, communicates in accordance with the set communication conditions; and a communication control means that sets the communication conditions in the pseudo-communication line means according to the ship-to-shore communication line to be simulated.

[0008] The invention described in claim 2 is a ship-to-shore communication line simulator described in claim 1, characterized in that the pseudo communication line means comprises a computer having a first communication interface and a second communication interface, with the first communication interface and the second communication interface bridge-connected, and the communication control means sets the communication conditions between the first communication interface and the second communication interface according to the ship-to-shore communication line to be simulated.

[0009] The invention described in claim 3 is a ship-to-shore communication line simulator described in claim 1 or 2, characterized in that the communication control means switches the communication conditions according to a test scenario that indicates a state in which the multiple ship-to-shore communication lines are switched depending on the operating status of the ship.

[0010] The invention described in claim 4 is a ship-to-shore communication evaluation system characterized by comprising the ship-to-shore communication line simulator described in claim 1 or 2, and an evaluation device connected to the ship-to-shore communication line simulator and evaluating communications performed by the pseudo communication line means.

[0011] The invention described in claim 5 is a ship-to-shore communication evaluation system comprising a plurality of ship-to-shore communication line simulators described in claim 1 or 2, a communication switching device connected to the plurality of ship-to-shore communication line simulators, and an evaluation device connected to the communication switching device, wherein the plurality of ship-to-shore communication line simulators each simulate a different ship-to-shore communication line, the communication switching device switches between the ship-to-shore communication line simulators that perform communication according to predetermined conditions, and the evaluation device evaluates the switching of the ship-to-shore communication line simulators by the communication switching device. [Effects of the Invention]

[0012] According to the invention described in claim 1, it is possible to simulate multiple ship-to-shore communication lines, so it is possible to generate and evaluate all ship-to-shore communication lines on a desk without actually operating the ship. In addition, because tests can be easily performed on a desk, it can also be used for prior examination of the ship-to-shore communication lines to be used and for demonstrating the control program of an autonomously operating ship. This makes it possible to significantly reduce the evaluation time and costs involved compared to conducting field tests.

[0013] Furthermore, according to the invention described in claim 2, the pseudo communication line means is constructed simply by bridging the first communication interface and the second communication interface of one computer, and by changing the communication conditions of this bridge connection, it is possible to simulate a ship-to-shore communication line, making it possible to construct a ship-to-shore communication line simulator at very low cost and in a small size.

[0014] Furthermore, according to the invention described in claim 3, communication conditions can be switched according to a test scenario that shows how multiple ship-to-shore communication lines are switched depending on the ship's operating status, making it possible to reproduce the actual operating conditions of the ship and perform more accurate evaluations.

[0015] Furthermore, according to the invention described in claim 4, ship-to-shore communications tests can be easily performed on a desk, which makes it possible to significantly reduce the evaluation time and costs involved compared to conducting field tests.

[0016] Furthermore, according to the invention described in claim 5, since the communication switching device can be easily tested on a desk, it is possible to significantly reduce the evaluation time and costs involved in the evaluation compared to conducting a field test. [Brief explanation of the drawings]

[0017] [Figure 1] FIG. 1 is a diagram showing a schematic configuration of a conventional ship-to-shore communication system. [Figure 2]1 is a diagram showing a schematic configuration of a ship-to-shore communication evaluation system according to a first embodiment, which uses a ship-to-shore communication line simulator according to an embodiment of the present invention. [Figure 3] 3 is a diagram illustrating a control state of communication speed, communication delay time, and packet loss by the pseudo communication line unit shown in FIG. 2. [Figure 4] FIG. 3 is a diagram showing a specific schematic configuration of the ship-to-shore communication line simulator shown in FIG. 2. [Figure 5] This is a test scenario showing a situation in which the ship-to-shore communication line simulator shown in Figure 2 switches the line in use over time. [Figure 6] 3 is a table showing test results obtained for each test content using the ship-to-shore communication evaluation system shown in FIG. 2. [Figure 7] FIG. 10 is a diagram showing a schematic configuration of a ship-to-shore communication evaluation system according to a second embodiment, which uses a ship-to-shore communication line simulator according to an embodiment of the present invention. DETAILED DESCRIPTION OF THE INVENTION

[0018] The present invention will be described below based on the illustrated embodiments.

[0019] Figure 1 is a schematic diagram showing an example of a ship-to-shore communication system 1 that uses multiple ship-to-shore communication lines. This ship-to-shore communication system 1 is a system used for communication between a ship capable of navigating the open sea and a land-based facility that supports the operation of the ship, and includes a ship 2, a ship operation support server 3 installed in the land-based facility, and a ship-to-shore communication line 4 that connects the ship 2 and the ship operation support server 3.

[0020] The ship 2 is equipped with an in-ship network 21 installed on board the ship, a ship control device 22 connected to the in-ship network 21, and a switching router (communication switching device) 23 connected between the in-ship network 21 and the ship-to-shore communication line 4. The in-ship network 21 is a local area network for communication within the ship 2, and uses, for example, a wired LAN such as Ethernet (registered trademark).

[0021] The ship control device 22 is a device for controlling each part of the ship 2, and is connected to the in-ship network 21 to control each part of the ship 2. The ship control device 22 is a so-called computer equipped with five major devices: input, output, memory, control, and calculation, and functions as the ship control device 22 by operating in accordance with a ship control program 221 that is pre-installed.

[0022] The ship-to-shore communication line 4 is connected to the operation support server 3 via a WAN (Wide Area Network) 5 such as the Internet. The ship-to-shore communication line 4 includes, for example, a first line 41 consisting of a mobile phone communication line (hereinafter also referred to as LTE), a second line 42 which is a satellite line using a low earth orbit satellite (hereinafter also referred to as LEO), and a third line 43 which is a satellite line using a geostationary high earth orbit satellite (hereinafter also referred to as GEO).

[0023] In this embodiment, the communication speeds of the first line 41, second line 42, and third line 43 are assumed to be first line 41 > second line 42 > third line 43. Furthermore, the magnitude of communication delays of the first line 41, second line 42, and third line 43 depends on the distance, so the order is first line 41 < second line 42 < third line 43. Note that the rate of packet loss is not determined by the line, but depends on conditions such as the frequency used, weather conditions, distance from the base station (communication satellite), and obstructions between the base station, so no ranking is given in this embodiment.

[0024] The switching router 23 of the ship 2 appropriately switches the connection to the onboard network 21 between the first line 41, the second line 42 and the third line 43 to optimize communication quality depending on the communication conditions of the first line 41, the second line 42 and the third line 43 (such as whether communication is possible, communication quality such as communication speed, etc.).

[0025] The operation support server 3 is a server on which an operation support program 31 is installed, which has functions such as updating the ship control program 221 of the ship control device 22 in addition to functions to support the operation of the ship 2, and is installed, for example, in a land support center located on land. The operation support server 3 is a so-called computer equipped with five major devices: input, output, memory, control, and calculation, and functions as the operation support server 3 by operating in accordance with the operation support program 31 installed in advance.

[0026] For example, data detected by various sensors installed on board the ship, and image data such as still images and videos taken by cameras installed on board and outside the ship are transmitted from the ship control device 22 to the operation support server 3. In addition, the operation support server 3 transmits to the ship control device 22 the shortest and most optimal route that has been determined based on information such as the position, destination, and estimated time of arrival of the ship 2, taking into account weather and sea conditions, as well as update data for the ship control program 221.

[0027] To evaluate the ship-to-shore communication system 1 that uses the above-mentioned multiple ship-to-shore communication lines, it is necessary to actually operate the ship 2 and conduct field tests, which poses problems such as the evaluation being time-consuming and costly. In order to solve these problems, the present inventor invented a ship-to-shore communication line simulator that can simulate multiple ship-to-shore communication lines.

[0028] (Embodiment 1) 2 is a schematic diagram showing an example of a ship-to-shore communication evaluation system 6 that uses the above-mentioned ship-to-shore communication line simulator to enable desktop evaluation of the ship-to-shore communication system 1. The ship-to-shore communication evaluation system 6 includes a test computer 7, a ship-to-shore communication line simulator 8, a test server 9, etc.

[0029] The test computer 7 is a device in which a vessel control test program 71 is installed. The vessel control test program 71 is a program that combines the above-mentioned vessel control program 221 with a function for evaluating ship-to-shore communications. The vessel control test program 71 causes the test computer 7 to function as the vessel control device 22 and also as a device for evaluating ship-to-shore communications.

[0030] The test server 9 is a device on which a flight operation support test program 91 is installed. The flight operation support test program 91 is a program that combines the above-mentioned flight operation support program 31 with a function for evaluating ship-to-shore communications. The flight operation support test program 91 causes the test server 9 to function as the flight operation support server 3 and also as an evaluation device for ship-to-shore communications.

[0031] The ship-to-shore communication line simulator 8 includes a pseudo-communication line unit (pseudo-communication line means) 81 that communicates in accordance with the set communication conditions, including at least one of communication speed, communication delay time, and packet loss, and a communication control unit (communication control means) 82 that sets communication conditions in the pseudo-communication line unit 81 according to the ship-to-shore communication line to be simulated.

[0032] 3A to 3C are diagrams illustrating the control of communication speed, communication delay time, and packet loss by the pseudo-communication line unit 81. As shown in FIG. 3A, the pseudo-communication line unit 81 controls the communication band (shown as a cylindrical communication line in the figure) to widen or narrow, thereby changing the amount of information in packets P1 to P3 that can be transmitted within the same time, thereby switching the communication speed. Also, as shown in FIG. 3B, the pseudo-communication line unit 81 switches the communication delay time by delaying the passage of packets P1 to P3. Furthermore, as shown in FIG. 3C, the pseudo-communication line unit 81 causes packet loss by dropping an arbitrary packet (packet P2 in the figure) when packets P1 to P3 are allowed to pass.

[0033] FIG. 4 shows a more specific schematic configuration of the ship-shore communication line simulator 8. The ship-shore communication line simulator 8 is composed of a computer 83 equipped with at least two LAN ports. The pseudo-communication line unit 81 of the ship-shore communication line simulator 8 is configured by bridging a first LAN port (first communication interface) 831 pre-installed in the computer 83 with a second LAN port (second communication interface) 832 also pre-installed in the computer 83. In FIG. 4, the first LAN port 831 is connected to the test computer 7, and the second LAN port 832 is connected to the test server 9. However, the test server 9 may be connected to the first LAN port 831, and the test computer 7 may be connected to the second LAN port 832. Furthermore, if the computer used as the ship-shore communication line simulator 8 has only one built-in LAN port, a USB-LAN cable adapter may be connected to the USB port to serve as a second LAN port.

[0034] Furthermore, the communication control unit 82 of the ship-shore communication line simulator 8 is realized using a communication control function that is already included in the OS of the computer 83. For example, if the OS used by the computer 83 is LINUX (registered trademark), the communication conditions for the bridge connection between the first LAN port 831 and the second LAN port 832 are controlled by the tc command.

[0035] In LINUX (registered trademark), tc commands such as "rate," "ceil," "burst," and "cburst" are used to control communication bandwidth (i.e., to set communication speed). tc commands such as "delay" are used to control communication delay time. tc commands such as "loss" are used to control packet loss. Furthermore, by combining control of communication bandwidth and control of packet loss, it is also possible to arbitrarily set the upload time of a data file, etc.

[0036] In other words, the ship-land communication line simulator 8 according to this embodiment can simulate communications via the first line 41, the second line 42, and the third line 43 by arbitrarily setting the communication speed, packet loss, communication delay time, file upload time, etc. using the tc command.

[0037] Next, we will explain the method for evaluating ship-to-shore communications using the ship-to-shore communication evaluation system 6. The communication control unit 82 of the ship-to-shore communication line simulator 8 sets communication conditions (communication speed, packet loss, communication delay time, file upload time, etc.) for the pseudo communication line unit 81 according to the ship-to-shore communication line to be evaluated, for example, the first line (LTE) 41.

[0038] Depending on the test content, the test computer 7 and the test server 9 communicate data, files, etc. with each other via the ship-to-shore communication line simulator 8. The evaluation results may be displayed on either or both of the test computer 7 and the test server 9.

[0039] In addition, a test scenario may be created in advance that shows the state in which multiple ship-to-shore communication lines are switched depending on the ship's operating status, and evaluation may be performed by sequentially switching the ship-to-shore communication lines according to this test scenario.

[0040] Figure 5(A) shows a test scenario illustrating changes in the line used depending on route conditions. Time progresses from left to right in the figure. For example, when ship 2 departs from port, it is located near the coast and uses line 1 (LTE) 41, which has a high communication speed and low latency. When ship 2 then heads out to sea and loses connection to line 1 (LTE) 41, it connects to line 3 (GEO) 43 (or line 2 (LEO) 42), which has a slower communication speed than LTE but is more stable. When ship 2 completes its voyage and enters port, it reconnects to line 1 (LTE) 41. By performing an evaluation according to this test scenario, it is possible to perform an evaluation similar to that performed in the field while ship 2 is actually operating.

[0041] As shown in FIG. 5(B), the test scenario may change the line used depending on the satellite blocking conditions caused by obstacles such as the ship's obstacles on the open ocean. For example, when the ship 2 can communicate without blocking on the open ocean, the second line (LEO) 42, which has a relatively fast communication speed and relatively little delay, is used. Next, when the second line (LEO) 42 is blocked and the communication situation becomes unstable, the third line (GEO) 43, which has a slower communication speed than LEO but is more stable, is connected. When the blocking is resolved, the second line (LEO) 42 is connected again. In this way, by performing an evaluation according to the test scenario, it is possible to perform an evaluation similar to that when the ship 2 is actually operated and a field test is performed.

[0042] Specific test contents may include, for each communication line, updating of the vessel control program 221 by the vessel operation support server 3 and transmission of images from the vessel 2 to the vessel operation support server 3, as shown in Figure 6. The table shown in Figure 6 shows the evaluation results, with a circle mark indicating that the test has been passed and a cross mark indicating that the test has not been passed. This test result table may be displayed on either the test computer 7 or the test server 9, or on both.

[0043] The ship-to-shore communication line simulator 8 according to this embodiment can simulate ship-to-shore communication lines assuming multiple fields, making it possible to simulate and evaluate all ship-to-shore communication lines on a desk without actually operating the ship 2. Furthermore, because tests can be easily performed on a desk, it can also be used for prior examination of the ship-to-shore communication lines to be used and for demonstrations of the ship control program 221. This makes it possible to significantly reduce the evaluation time and costs involved in evaluation compared to conducting field tests.

[0044] Furthermore, the pseudo-communication line unit 81 is constructed simply by bridging between a first LAN port (first communication interface) 831 and a second LAN port 832 that are pre-installed in one computer 83, and by changing the communication conditions of this bridge connection, it is possible to simulate a ship-to-shore communication line, making it possible to construct a ship-to-shore communication line simulator 8 at very low cost and in a small size.

[0045] Furthermore, since communication conditions can be switched according to a test scenario that shows how multiple ship-to-shore communication lines are switched depending on the operating status of ship 2, it is possible to reproduce the actual operating conditions of ship 2 and perform a more accurate evaluation.

[0046] Furthermore, according to the ship-to-shore communication evaluation system 6 of this embodiment, which utilizes the ship-to-shore communication line simulator 8 of this embodiment, ship-to-shore communication tests can be easily performed on a desk, making it possible to significantly reduce the evaluation time and costs involved in the evaluation compared to conducting field tests.

[0047] (Embodiment 2) Next, a ship-to-shore communication evaluation system according to embodiment 2 of the present invention will be described. The ship-to-shore communication evaluation system according to embodiment 2 of the present invention is a system used to evaluate a switching router (communication switching device) that switches between multiple ship-to-shore communication lines. In this embodiment 2, the same components as those in the ship-to-shore communication evaluation system 6 according to embodiment 1 will be designated by the same reference numerals, and detailed description thereof will be omitted.

[0048] The ship-to-shore communication evaluation system 6A according to the second embodiment includes a test computer 7, a switching router 23, a plurality of ship-to-shore communication line simulators 8A, 8B, and 8C, and a test server 9. The ship-to-shore communication line simulators 8A, 8B, and 8C have the same configuration as the ship-to-shore communication line simulator 8.

[0049] Unlike the ship-to-shore communication line simulator 8 according to embodiment 1, the ship-to-shore communication line simulators 8A, 8B, and 8C each simulate a fixed ship-to-shore communication line. That is, the ship-to-shore communication line simulator 8A simulates a first line (LTE) 41, the ship-to-shore communication line simulator 8B simulates a second line (LEO) 42, and the ship-to-shore communication line simulator 8C simulates a third line (GEO) 43.

[0050] The switching router 23 switches the ship-to-shore communication line between LTE, LEO, and GEO so as to optimize communication quality according to the communication conditions between the test computer 7 and the test server 9. The test computer 7 and the test server 9 determine whether the switching router 23 is appropriately switching the ship-to-shore communication line according to the communication conditions. For example, when testing the switching of the line used due to route conditions, the communication conditions are set to a state in which the ship 2 is heading out to sea from a coastal area, and a test is performed to determine whether the ship-to-shore communication line can be appropriately switched according to this change in communication conditions.

[0051] According to the ship-to-shore communication evaluation system 6A of this embodiment, the switching router 23 can be easily tested on a desk, which makes it possible to significantly reduce the evaluation time and costs involved in the evaluation compared to conducting field tests.

[0052] The above describes an embodiment of the present invention, but the specific configuration is not limited to the above embodiment, and even if there are design changes or the like within the scope of the gist of the present invention, they are included in the present invention.

[0053] For example, in the above embodiment, a general ship that sails on the open ocean has been used as an example of a ship, but it can also be applied to ships that only sail along coastal areas or autonomous ships that can sail unmanned.

[0054] 1 Ship-to-shore communication system 2 ships 21 Onboard Network 22 Ship control device 23 Switching router (communication switching device) 221 Ship Control Program 3 Flight support server 31 Flight Support Program 4 Ship-to-shore communication lines 41 Line 1 42 Second Line 43 Third Line 5 WAN 6, 6A Ship-to-shore communication evaluation system 7 Test Computer (Evaluation Device) 71 Ship Control Test Program 8, 8A, 8B, 8C Ship-to-shore communication line simulator 81 Pseudo communication line unit (pseudo communication line means) 82 Communication control unit (communication control unit) 83 Computer 831 First LAN port (first communication interface) 832 Second LAN port (second communication interface) 9 Test Server (Evaluation Device) 91 Flight Support Test Program

Claims

1. A ship-to-shore communication line simulator used to simulate a plurality of ship-to-shore communication lines connecting an onboard network installed on a ship and a server installed in a land facility, a pseudo communication line means for performing communication in accordance with a communication condition set including at least one of a communication speed, a communication delay time, and a packet loss; a communication control means for setting the communication conditions in the pseudo communication line means according to the ship-to-shore communication line to be simulated; A ship-to-shore communication line simulator comprising:

2. the pseudo communication line means comprises a computer having a first communication interface and a second communication interface, the first communication interface and the second communication interface being bridge-connected; the communication control means sets the communication conditions between the first communication interface and the second communication interface in accordance with the ship-to-shore communication line to be simulated; 2. The ship-to-shore communication line simulator according to claim 1.

3. the communication control means switches the communication conditions in accordance with a test scenario that indicates a state in which the plurality of ship-to-shore communication lines are switched depending on the operational status of the ship; 3. The ship-to-shore communication line simulator according to claim 1 or 2.

4. 3. A ship-to-shore communication evaluation system comprising: a ship-to-shore communication line simulator according to claim 1 or 2; and an evaluation device connected to the ship-to-shore communication line simulator and for evaluating communications carried out by the pseudo communication line means.

5. A ship-to-shore communication line simulator according to claim 1 or 2, a communication switching device connected to the ship-to-shore communication line simulators, and an evaluation device connected to the communication switching device, The plurality of ship-to-shore communication line simulators each simulate a different ship-to-shore communication line, the communication switching device switches the ship-to-shore communication line simulator that performs communication according to a predetermined condition; the evaluation device evaluates switching of the ship-to-shore communication line simulator by the communication switching device; A ship-to-shore communication evaluation system.

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