JP7705651B2 - A simulation signal generator for mobile satellite communications. - Google Patents

Description

The present invention relates to a simulation signal output device for mobile satellite communications.

In the field of satellite communications, particularly for Ka (K-above) band satellite communications systems, the 19.7-20.2 GHz and 29.5-30.0 GHz frequency bands that were allocated to fixed satellite communications at the World Radiocommunication Conference for ESIM (Earth Station in Motion) were approved as ESIM frequency bands. After that, 17.7-19.7 GHz and 27.5-29.5 GHz were additionally approved as ESIM frequency bands. For these reasons, Ka-band mobile satellite communications are attracting increasing attention. For this reason, congestion control algorithms for satellite circuits such as those disclosed in Non-Patent Document 1 are attracting attention.

The technology disclosed in Non-Patent Document 1 discloses a congestion control algorithm for satellite links that can handle the unique characteristics of satellite links, such as long delay times and packet loss due to bit errors.

Qi Zhao, Huanren Zhou, and Hongwei Deng, “An enhanced Vegas congestion control algorithmbased on BeiDou navigation system”, IEICE Communications Express, Vol.1, No.7, pp.275-281,December 2012.

On the other hand, mobile satellite communication systems, especially land mobile satellite communication systems, perform satellite communication while moving. As a result, communication interruptions occur frequently due to the effects of obstructions such as man-made objects and buildings. This phenomenon cannot be avoided, and there is a problem that it has a negative effect on data communication. In addition, even if the given physical line bandwidth is wide, there is a problem that the TCP (Transmission Control Protocol) throughput does not increase. In order to solve these problems, it is necessary to improve the efficiency of data communication by using emulators or simulators that mimic a mobile satellite communication system while moving.

However, Non-Patent Document 1 does not take into account communication interruptions caused by obstructions that occur when a mobile satellite communication system moves, and is premised on the use of fixed earth stations such as VSATs (Very Small Aperture Terminals). It is extremely difficult for a mobile satellite communication system to travel on roads or other areas that are completely free of obstructions, and the effects of the congestion control algorithm for satellite links, TCP accelerators, and link optimization based on the results of satellite communication network simulations, as described in Non-Patent Document 1, are limited because they do not take into account communication interruptions caused by obstructions. Other problems include changes in the moving speed of the mobile satellite communication system, variations in the duration of communication interruptions depending on the type of obstruction, and the complexity of the interlock control that occurs each time.

The present invention was developed to solve the above-mentioned problems, and aims to provide a simulation signal output device for mobile satellite communications that can simulate a signal that a mobile object can receive in a mobile satellite communications system, even if the mobile object is not moving.

The simulation signal output device for mobile satellite communications according to the first invention is a simulation signal output device for simulating a mobile satellite communications system that outputs a simulated simulation signal that can be received from a satellite by a mobile body moving along a first moving path at a first moving speed, and is characterized in that it comprises an attenuation means for attenuating a newly received first evaluation signal by referring to a time-series simulation signal that reflects the first moving speed and attenuation due to an obstruction that blocks the signal from the satellite when moving along the first moving path .

The simulation signal output device for mobile satellite communications according to the second invention is the same as in the first invention, further comprising a simulation signal generating means for generating the simulation signal based on position information relating to a position of an obstruction that blocks a signal from the satellite as the mobile body moves along the first movement path and on the first movement speed .

A simulation signal output device for mobile satellite communications according to a third aspect of the present invention is a simulation signal output device for simulating a mobile satellite communications system that outputs a simulated simulation signal that a mobile body moving along a first movement path at a first movement speed can receive from a satellite, the simulation signal output device comprising: an output means for outputting a time-series simulation signal reflecting the first movement speed and attenuation due to an obstacle that blocks a signal from the satellite when the mobile body moves along the first movement path, the simulation signal output device further comprising: an output means for outputting a time-series simulation signal reflecting the first movement speed and attenuation due to an obstacle that blocks a signal from the satellite when the mobile body moves along the first movement path, the simulation signal output means ... a storage means for storing an attenuation model in which obstacle information relating to a type and/or width of the obstacle and an attenuation pattern relating to a pattern of attenuation of a signal due to the obstacle are associated with each other, the attenuation model having the obstacle information as an input and the attenuation pattern as an output; an obstacle information acquisition means for acquiring the obstacle information of an obstacle that blocks a signal from the satellite when the mobile body moves along the first movement path, and a simulation signal generation means for generating a simulation signal from the attenuation pattern output by inputting the obstacle information acquired by the obstacle information acquisition means into the attenuation model stored in the storage means .

A simulation signal output device for mobile satellite communication according to a fourth aspect of the present invention is a simulation signal output device for simulating a mobile satellite communication system in which a mobile body moving along a first movement path at a first movement speed outputs a simulated simulation signal that can be received from a satellite, the simulation signal output device comprising: an output means for outputting a time-series simulation signal reflecting the first movement speed and attenuation due to an obstruction that blocks the signal from the satellite when the mobile body moves along the first movement path; a storage means for storing a data table in which attenuation patterns related to the attenuation patterns for each position on the first movement path are linked to each other; a travel time acquisition means for acquiring a travel time of the mobile body; a current position calculation means for determining a virtual current position on the first movement path based on the travel time acquired by the travel time acquisition means and the first movement speed; an attenuation pattern selection means for selecting the attenuation pattern for a position corresponding to the virtual current position calculated by the current position calculation means by referring to the data table stored in the storage means; and a simulation signal generation means for generating a simulation signal from the attenuation pattern selected by the attenuation pattern selection means.

The simulation signal output device for mobile satellite communications according to the fifth aspect of the present invention is the first aspect of the present invention, further comprising: a memory means for storing an attenuation model in which obstacle information relating to the type and/or width of an obstacle and an attenuation pattern relating to the pattern of signal attenuation due to the obstacle are mutually associated, the obstacle information being an input and the attenuation pattern being an output; an obstacle information acquisition means for acquiring the obstacle information of an obstacle that blocks a signal from the satellite as the mobile body moves along the first movement path; and a simulation signal generation means for generating a simulation signal from the attenuation pattern output by inputting the obstacle information acquired by the obstacle information acquisition means into the attenuation model stored in the memory means .

The simulation signal output device for mobile satellite communications according to the sixth aspect of the present invention is a simulation signal output device for simulating a mobile satellite communications system in which a mobile body moving along a first path at a first moving speed outputs a simulation signal that can be received from a satellite, the simulation signal output device being characterized in that it comprises: a second attenuation means for attenuating a second evaluation signal to be newly transmitted by referring to a time-series simulation signal that reflects the first moving speed and attenuation due to an obstruction that blocks the signal from the satellite when moving along the first path; and a transmitting antenna for transmitting the second evaluation signal attenuated by the second attenuation means.

According to the first to sixth inventions, the simulation signal output device for mobile satellite communication outputs a time-series simulation signal that reflects the first moving speed and the attenuation caused by an obstruction that blocks a signal from a satellite when moving along a first moving path. This makes it possible to simulate and output a received signal attenuated by an obstruction in a mobile satellite communication system. Therefore, it is possible to simulate the attenuation caused by an obstruction in a mobile satellite communication system without moving the mobile body. In addition, it is possible to simulate the attenuation caused by an obstruction in a mobile satellite communication system in a laboratory, making it possible to study the influence of communication interruption caused by an obstruction that occurs while the mobile satellite communication system is moving and to study a congestion control algorithm accordingly. Also, according to the first invention, the simulation signal output device for mobile satellite communication attenuates a newly received first evaluation signal by referring to the simulation signal. This makes it possible to reflect the amount of attenuation in the simulation signal in the first evaluation signal. Therefore, it is possible to output an evaluation signal that reflects the amount of attenuation in the mobile satellite communication system.

In particular , according to the second aspect of the present invention, the simulation signal output device for mobile satellite communication generates a simulation signal based on the position information and the first moving speed. This makes it possible to generate a simulation signal based on the position of an obstruction and the speed of the moving body. This makes it possible to simulate received signals of a mobile satellite communication system with more diverse patterns.

In particular, according to the third aspect of the present invention, the simulation signal output device for mobile satellite communications generates a simulation signal from an attenuation pattern output by inputting obstruction information into an attenuation model. This makes it possible to generate a simulation signal that reflects the attenuation that varies depending on the type and size of the obstruction. This makes it possible to simulate received signals of a mobile satellite communications system with a wider variety of patterns.

In particular, according to the fourth aspect of the present invention, the simulation signal output device for mobile satellite communication refers to a data table, selects an attenuation pattern for a position corresponding to a virtual current position, and generates a simulation signal from the selected attenuation pattern. This makes it possible to generate a simulation signal according to the virtual position. This makes it possible to generate a simulation signal suitable for the environment of the virtual position, and enables more accurate simulation of a received signal in a mobile satellite communication system.

In particular, according to the fifth aspect of the present invention, the simulation signal output device for mobile satellite communications generates a simulation signal from an attenuation pattern output by inputting obstruction information into an attenuation model. This makes it possible to generate a simulation signal that reflects the attenuation that varies depending on the type and size of the obstruction. This makes it possible to simulate received signals of a mobile satellite communications system with a wider variety of patterns.

In particular, according to the sixth aspect of the present invention, the simulation signal output device for mobile satellite communications refers to the simulation signal, attenuates the second evaluation signal to be newly transmitted, and transmits the attenuated second evaluation signal. This makes it possible to attenuate the evaluation signal to be transmitted, and to attenuate the evaluation signals to be transmitted and received individually by the ODU (Out Door Unit) and the IDU (In Door Unit). This makes it possible to consider the effect on data communications of an interlock, which is a function that stops transmission when a communication interruption occurs, for example.

FIG. 1 is a schematic diagram showing an example of a mobile satellite communication system. FIG. 2 is a schematic diagram showing an example of a moving object moving along a moving path. FIG. 3 is a diagram showing an example of a received signal and a simulation signal. FIG. 4 is a schematic diagram showing the entire configuration of a simulation signal output device according to a first embodiment of the present invention. FIG. 5 is a schematic diagram showing the entire configuration of a simulation signal output device according to a second embodiment of the present invention. FIG. 6 is a diagram showing an example of actual measured values and calculated values of a signal attenuated by a utility pole and received by a moving body. FIG. 7 is a diagram showing an example of obstruction information and attenuation patterns at each position.

First Embodiment
A simulation signal output device 1 according to a first embodiment of the present invention will be described in detail below with reference to the drawings.

The simulation signal output device 1 simulates a received signal that a mobile unit 53 may receive from a satellite 52 in a mobile satellite communication system 100, such as that shown in FIG. 1.

The mobile satellite communication system 100 is a communication system that includes, for example, a gateway station 51, a satellite 52 that transmits and receives signals to and from the gateway station 51, and a mobile unit 53 that transmits and receives signals to and from the satellite 52.

The gateway station 51 functions as a so-called base station, serves as a wireless access point between devices in the wireless communication network, and serves as an interface between the gateway station 51 and public communication networks such as the Internet. In other words, the gateway station 51 serves as a relay means through which devices can send and receive signals between the gateway station 51 and public communication networks such as the Internet.

The satellite 52 is an artificial satellite that orbits in a geostationary earth orbit (GEO), which is a geosynchronous orbit around the earth with an orbital period that coincides with the earth's rotation period, or in a low earth orbit (LEO) or medium earth orbit (MEO), which revolves independently of the earth's rotation period, or even flies in deep space. This satellite 52 may be one that has been launched for any purpose. Furthermore, this satellite 52 is not limited to those that orbit GEO, LEO, or MEO, but is a concept that includes any other satellite that flies in outer space.

The mobile body 53 is a moving object capable of communicating with the satellite 52. For example, the mobile body 53 is a car, a bus, an airplane, a ship, etc. equipped with an antenna. In the mobile satellite communication system 100, the mobile body 53 communicates between the satellite 52 and the mobile body 53, and transmits and receives signals that are attenuated by the shielding object 54.

In the mobile satellite communication system 100, the shield 54 is a structure such as a house, building, utility pole, or mercury lamp, or a natural object such as a tree or mountain, which shields and attenuates the communication signal between the satellite 52 and the mobile unit 53.

2 is a diagram showing the correspondence relationship between the reception signal received by the mobile body 53 and the positions of the mercury lamp 61 and the utility pole 62 on the path 60 when the mobile body 53 moves at a set moving speed in the mobile satellite communication system 100. The graph shown in the lower part of FIG. 2 shows the data transfer rate (Bits/s) of the reception signal received by the mobile body 53 versus time (s). In the mobile satellite communication system 100, the signal received by the mobile body 53 moving along the path 60 from the satellite 52 is attenuated due to communication interruptions caused by, for example, the mercury lamp 61 or the utility pole 62 on the path 60. As a result, the reception power of the reception signal received by the mobile body 53 from the satellite 52 is attenuated. As the reception power is attenuated, the data transfer rate of the reception signal is also attenuated. The graph at the bottom of Figure 2, which converts the attenuation of the data transfer rate of the received signal onto a time axis, shows that the data transfer rate of the received signal received by the mobile unit 53 attenuates when passing the positions of the mercury lamp 61 and the utility pole 62 on the moving path 60. This is because the received power of the signal received by the mobile unit 53 from the satellite 52 is attenuated by the mercury lamp 61 and the utility pole 62 on the moving path 60. In addition, the attenuation pattern of the received signal received by the mobile unit 53 differs depending on, for example, the type and width of the obstruction 54 (mercury lamp 61, utility pole 62, etc.). For example, the attenuation pattern when the mobile unit 53 passes the mercury lamp 61 is different from the attenuation pattern when the mobile unit 53 passes the utility pole 62.

The attenuation pattern here refers to the pattern of attenuation of the received signal received by the mobile unit 53 when attenuated due to the influence of the obstruction 54. The attenuation pattern includes an attenuation amount that indicates the extent to which the signal has attenuated. The attenuation pattern also includes an attenuation width that is the difference between the distance at which the signal begins to attenuate and the distance at which the signal has attenuated.

The simulation signal output device 1 of the first embodiment to which the present invention is applied outputs a simulation signal that simulates a received signal that is actually attenuated by an obstruction 54 and received from a satellite 52 by a mobile unit 53 moving along a first moving path that can also be set at a first moving speed that can be set in this mobile satellite communication system 100.

The graph in FIG. 3 is an example of a graph showing the attenuation (dB) of an actual received signal received from a satellite 52 by a mobile body 53 moving along a first moving path at a first moving speed, and the attenuation (dB) of a simulated signal that simulates this received signal, versus distance (m). The simulated signal is a signal that is generated based on the received signal received from a satellite 52 by a mobile body 53 moving along a first moving path at a first moving speed. The simulated signal is a time-series signal that reflects the first moving speed and attenuation due to a shield 54 that blocks the signal from the satellite 52 while moving along the first moving path. The simulated signal may also be a signal that is associated with each position on the first moving path. The simulated signal may also be a signal that reflects attenuation due to the above-mentioned shield, the moving speed of the mobile body 53, and the line margin.

Figure 4 (a) is an overall schematic diagram of a simulation signal output device 1 according to a first embodiment of the present invention. The simulation signal output device 1 is mounted on a moving body 53, for example, but is not limited to this and may be installed in a stationary state indoors.

The simulation signal output device 1 is connected to, for example, an ODU 11 and an IDU 14. The simulation signal output device 1 includes a first stepless attenuator 13 and a second stepless attenuator 15 connected to the IDU 14 and the ODU 11, and an attenuation control unit 17 connected to the first stepless attenuator 13 and the second stepless attenuator 15.

The ODU 11 includes a receiving antenna for receiving the first evaluation signal and a transmitting antenna for transmitting the second evaluation signal. The ODU 11 may receive the first evaluation signal from, for example, a satellite 52, but is not limited to this, and may receive the first evaluation signal from the satellite 52. The ODU 11 may also transmit the second evaluation signal to, for example, a satellite 52, but is not limited to this, and may transmit the second evaluation signal to the satellite 52. The ODU 11 outputs the first evaluation signal received by, for example, the receiving antenna to the first stepless attenuator 13. The evaluation signal is a time-series signal to be attenuated. The first evaluation signal is an evaluation signal received by the ODU 11. The second evaluation signal is an evaluation signal transmitted by the ODU 11.

The IDU 14 is, for example, a modem for modulating and demodulating signals transmitted to and received from the evaluation device 19. The IDU 14 outputs to the evaluation device 19, for example, data extracted from the demodulated first evaluation signal attenuated by the first stepless attenuator 13. The IDU 14 also generates, for example, a second evaluation signal and outputs the generated second evaluation signal to the second stepless attenuator 15.

The first stepless attenuator 13 is an attenuator that attenuates the first evaluation signal input from the ODU 11 based on the attenuation control signal output from the attenuation control unit 17. The first stepless attenuator 13 outputs the attenuated first evaluation signal to the IDU 14.

The second stepless attenuator 15 is an attenuator that attenuates the second evaluation signal output from the IDU 14 based on the attenuation control signal output from the attenuation control unit 17. The second stepless attenuator 15 outputs the second evaluation signal to the ODU 11.

The attenuation control unit 17 controls the attenuation in the first stepless attenuator 13 and the second stepless attenuator 15. For example, the attenuation control unit 17 generates an attenuation control signal and outputs the generated attenuation control signal to the first stepless attenuator 13 and the second stepless attenuator 15.

The evaluation device 19 is a device that evaluates the evaluation signal attenuated by the simulation signal output device 1. For example, in the mobile satellite communication system 100, the evaluation device 19 may compare and evaluate the received signal actually received by the mobile unit 53 with the evaluation signal that has been attenuated under the control of the attenuation control unit 17.

As shown in FIG. 4(b), the attenuation control unit 17 includes an acquisition unit 171, a generation unit 172, an output unit 173, and a storage unit 174, which are connected to each other. Each function of the attenuation control unit 17 may be realized by software.

The acquisition unit 171 acquires various information input by the user via a keyboard or the like.

The generator 172 generates various information such as simulation signals and attenuation control signals.

The memory unit 174 stores various information acquired by the acquisition unit 171 and various information generated by the generation unit 172.

The output unit 173 outputs the simulation signal stored in the memory unit 174 to the first stepless attenuator 13 and the second stepless attenuator 15.

Next, we will explain the operation of outputting a simulation signal in this embodiment.

First, the ODU 11 receives a first evaluation signal from the satellite 52. The ODU 11 outputs the received first evaluation signal to the first stepless attenuator 13.

The generator 172 in the attenuation control unit 17 references the simulation signal and generates an attenuation control signal. The output unit 173 outputs the generated attenuation control signal to the first variable-speed attenuator 13.

The first variable-speed attenuator 13 then attenuates the first evaluation signal based on the attenuation control signal. In this case, the first variable-speed attenuator 13 can attenuate the first evaluation signal by reflecting the attenuation caused by the obstruction. This makes it possible to reflect the amount of attenuation in the simulation signal in the first evaluation signal. The first variable-speed attenuator 13 outputs the attenuated first evaluation signal to the IDU 14.

The IDU 14 outputs data extracted from the demodulated first evaluation signal sent from the first stepless attenuator 13 to the evaluation device 19. The evaluation device 19, to which the data extracted from the demodulated first evaluation signal is output from the IDU 14, evaluates the first evaluation signal.

The IDU 14 may also generate a second evaluation signal that is different from the first evaluation signal. In such a case, the IDU 14 outputs the generated second evaluation signal to the second stepless attenuator 15.

Next, the second stepless attenuator 15 attenuates the second evaluation signal input from the IDU 14 based on the attenuation control signal input from the attenuation control unit 17.

Next, the second stepless attenuator 15 outputs the second evaluation signal to the ODU 11, and the ODU 11 transmits the second evaluation signal to the satellite 52. This allows the second evaluation signal to be transmitted and the first evaluation signal received to be attenuated separately for transmission and reception. This also makes it possible to consider the effect on data communication of an interlock, which is a function that stops transmission when a communication interruption occurs, for example.

This makes it possible to simulate and output a received signal attenuated by the obstruction 54 in the mobile satellite communication system 100. This makes it possible to simulate the attenuation caused by the obstruction 54 in the mobile satellite communication system 100 without moving the mobile body 53. In addition, it is possible to simulate the attenuation caused by the obstruction 54 in the mobile satellite communication system 100 in a laboratory, making it possible to study the effects of communication interruptions caused by the obstruction 54 while the mobile satellite communication system 100 is moving, and to study congestion control algorithms accordingly.

Second Embodiment
The simulation signal output device 1 according to the second embodiment of the present invention will be described in detail below.

Figure 5 is an overall schematic diagram of a simulation signal output device 1 of a second embodiment to which the present invention is applied. The simulation signal output device 1 outputs a simulation signal. The simulation signal output device 1 may be installed indoors, for example, in a laboratory. The simulation signal output device 1 includes a mobile body simulation unit 4, a satellite simulation unit 3 connected to the mobile body simulation unit 4, and a gateway station simulation unit 2 connected to the satellite simulation unit 3.

The mobile simulation unit 4 simulates a mobile unit 53 that communicates with a satellite 52 in the mobile satellite communication system 100. The mobile simulation unit 4 outputs a simulated signal that the mobile unit 53 can receive from the satellite 52 to the satellite simulation unit 3 and the evaluation device 19a.

The evaluation device 19a evaluates the data extracted from the demodulated simulation signal output from the mobile body simulation unit 4.

The moving body simulator 4 includes a damping control unit 17 and a modem 41 and a modem 43 connected to the damping control unit 17.

The attenuation control unit 17 outputs the simulation signal to modem 41 and modem 43.

The modem 41 modulates and demodulates signals transmitted to and received from the satellite simulation unit 3. The modem 41 outputs the simulation signal output from the attenuation control unit 17 to the satellite simulation unit 3.

The modem 43 modulates and demodulates signals transmitted to and received from the evaluation device 19a. The modem 43 outputs data extracted from the demodulated simulation signal output from the attenuation control unit 17 to the evaluation device 19a.

The satellite simulation unit 3 simulates, for example, a gateway station 51 and a satellite 52 that communicates with a mobile unit 53 in a mobile satellite communication system 100. The satellite simulation unit 3 delays a simulation signal output from, for example, the mobile unit simulation unit 4, and outputs the delayed simulation signal to the gateway station simulation unit 2. The satellite simulation unit 3 includes a delay device unit 31 for delaying the signal.

The delay unit 31 is a delay circuit that delays a signal. The delay unit 31 delays, for example, a simulation signal output from the modem 41. The delay unit 31 outputs the delayed simulation signal to the gateway station simulation unit 2.

The gateway station simulation unit 2 simulates a gateway station 51 that communicates with a satellite 52 in the mobile satellite communication system 100. The gateway station simulation unit 2 outputs a simulation signal from the satellite simulation unit 3. The gateway station simulation unit 2 also includes a modem 21 and a modem 22 connected to the modem 21.

The modem 22 modulates and demodulates signals transmitted to and received from the satellite simulation unit 3. The modem 22 outputs, for example, a simulation signal output from the satellite simulation unit 3 to the modem 21.

The modem 21 is a transmitting/receiving device for modulating and demodulating signals transmitted to and received from the evaluation device 19b. The modem 21 outputs the data extracted from the demodulated simulation signal output from the modem 22 to the evaluation device 19b.

The evaluation device external device 19b evaluates the data extracted from the demodulated simulation signal output from the gateway station simulation unit 2.

Next, we will explain the operation of outputting the simulation signal to evaluation device 19a and evaluation device 19b in this embodiment.

First, the attenuation control unit 17 outputs the simulation signal to the modem 41 or the modem 43. In this case, the attenuation control unit 17 may output the simulation signal stored in the memory unit 174 itself. This makes it possible to simulate the attenuation caused by the obstruction 54 in the mobile satellite communication system 100 without moving the mobile unit 53.

Next, the simulation signal output device 1 outputs a simulation signal to the evaluation device 19a and the evaluation device 19b. The modem 41 to which the simulation signal is output from the attenuation control unit 17 outputs the simulation signal to the delay device unit 31. The delay device unit 31 to which the simulation signal is output delays the simulation signal. This makes it possible to simulate the delay that occurs when a signal is transmitted from the mobile unit 53 to the gateway station 51 via the satellite 52 in the mobile satellite communication system 100.

Next, the delay device 31 outputs the delayed simulation signal to the modem 22. The modem 22, to which the simulation signal has been output, outputs the data extracted from the demodulated simulation signal to the evaluation device 19b via the modem 21. This makes it possible to simulate the signal transmitted from the mobile unit 53 to the gateway station 51 via the satellite 52 in the mobile satellite communication system 100.

The modem 43 also outputs the data extracted from the demodulated output simulation signal to the evaluation device 19a. This allows the evaluation device 19a to evaluate the data extracted from the demodulated simulation signal output by the mobile body simulation unit 4.

Third Embodiment
The simulation signal output device 1 according to the third embodiment of the present invention will be described in detail below. The third embodiment is different from the first and second embodiments in that a simulation signal is generated by the generation unit 172 in the first and second embodiments.

An example of the operation of generating a simulation signal in this embodiment will be described. In the operation of generating a simulation signal in this embodiment, first, position information and a first moving speed are acquired. Next, a simulation signal is generated based on the position information and the first moving speed. Each process will be described in detail below.

First, the attenuation control unit 17 acquires position information on the position of the obstruction 54 that blocks the signal from the satellite 52 as the moving body 53 moves along the first movement path, and the first movement speed of the moving body 53. In this case, the acquisition unit 171 may acquire the position information of the obstruction 54 and the first movement speed input by a user who requests an evaluation of the evaluation signal.

The position information of the obstruction 54 is information about the position of the obstruction 54 that blocks the signal from the satellite 52 when the mobile unit 53 moves along the first movement path. The position information of the obstruction 54 and the first movement speed may be parameters arbitrarily set by the user as described above. In addition, the position information of the obstruction 54 and the first movement speed may use parameters actually obtained in the mobile satellite communication system 100.

Next, the generating unit 172 generates a simulation signal based on the position information of the shielding object 54 acquired by the acquiring unit 171 and the first moving speed. In such a case, the signal is converted into a time-series signal based on each piece of position information and the first moving speed. The generating unit 172 calculates the time when the moving body 53 passes each shielding object 54 from the position information of the shielding object 54 and the first moving speed. Then, the generating unit 172 reads out the attenuation pattern preset for each shielding object 54, and generates a simulation signal that reflects the attenuation pattern in the time-series signal.

Fourth Embodiment
A detailed description will now be given of a fourth embodiment of the simulation signal output device 1 to which the present invention is applied. The fourth embodiment differs from the third embodiment in that a simulation signal is generated from an attenuation pattern output by inputting shielding object information on a shielding object 54 to an attenuation model.

Next, an example of the operation of generating a simulated signal in this embodiment will be described. In the operation of generating a simulated signal in this embodiment, an attenuation model is prepared in advance, and newly acquired obstruction information is input to this attenuation model to output an attenuation pattern as a search solution, and a simulated signal is generated from the attenuation pattern obtained as the search solution.

The shielding information is information about the type and/or width of the shielding 54. The shielding information may also be information about, for example, the type or model number of the shielding 54, the width of the shielding, the line margin, interlocks caused by the shielding, etc.

The attenuation model is a model consisting of a plurality of data in which obstruction information and attenuation patterns are associated with each other, with the input being obstruction information and the output being an attenuation pattern as a search solution. The attenuation model may be a table in which the obstruction information and the attenuation pattern are uniquely associated with each other, as shown in Table 1. The operation of generating a simulated signal will be described in detail below.

First, an attenuation model is prepared in which the attenuation pattern is associated with the shielding information regarding the type and/or width of the shielding object 54, and the input is the shielding information, and the output is the attenuation pattern as a search solution, and is stored in advance in the storage unit 174. In such a case, in the mobile satellite communication system 100, the shielding information of the shielding object 54 actually on the moving path and the attenuation pattern of the received signal received by the moving object 53 moving on the moving path may be acquired as the input and output of the attenuation model, respectively.

Figure 6 is a graph showing the measured and calculated values of the attenuation (dB) of a signal with a frequency of 18.9 GHz received by a mobile body 53 equipped with a vehicle-mounted antenna with an aperture diameter of 65 cm when the mobile body 53 passes a utility pole 62 with a diameter of 350 mm while tracking a satellite 52 in a mobile satellite communication system 100, versus the distance (mm) from the center of the antenna of the mobile body 53 to the utility pole 62. The calculated value here is the attenuation (dB) value calculated using a formula that approximates the measured value. As shown in Figure 6, the calculated value according to the measured value of the signal received by the mobile body 53 moving along the actually acquired travel path may be stored as the attenuation pattern of the output of the attenuation model. In such a case, the shielding information of the utility pole 62 may be used as the input of the attenuation model, and the calculated value may be used as the output of the attenuation pattern.

After preparing the attenuation model in this manner, the acquisition unit 171 acquires the obstruction information. The acquisition unit 171 may be configured to accept input of the obstruction information from a user who actually performs analysis using the evaluation device 19.

Next, the generation unit 172 outputs an attenuation pattern by inputting the obstruction information acquired by the acquisition unit 171 into the attenuation model stored in the storage unit 174. In this case, when the acquisition unit 171 acquires the obstruction information B, it may output the attenuation pattern B associated with the obstruction information B that corresponds to the input in the attenuation model of Table 1.

Next, the generation unit 172 generates a simulated signal from the output attenuation pattern. This makes it possible to generate a simulated signal that reflects the attenuation that varies depending on the type and size of the obstruction 54. This makes it possible to simulate received signals of a mobile satellite communication system with a wider variety of patterns.

Fifth Embodiment
A detailed description will now be given of a simulation signal output device 1 to which the fifth embodiment of the present invention is applied. The fifth embodiment differs from the fourth embodiment in that a simulation signal for a position corresponding to a virtual current position is generated by referring to a data table.

The operation of generating a simulation signal in this embodiment will be described. The storage unit 174 stores in advance a data table in which attenuation patterns for each position on the first moving path are linked to each other. Table 2 shows an example of the data table, which is a table in which attenuation patterns for each position on the first moving path are linked to each other. The data table is a table in which each position assigned every 1 m from the starting point, the shielding object information, and the attenuation pattern are uniquely associated with each other. However, this data table does not necessarily require that the shielding object information is linked, and may be a table in which only the position and the attenuation pattern are linked to each other.

After preparing such a data table, the acquisition unit 171 acquires the first moving speed and running time of the moving body 53. At this time, the acquisition unit 171 determines a virtual current position on the first moving path based on the running time and the first moving speed. The generation unit 172 refers to the data table stored in the memory unit 174, selects a damping pattern for a position corresponding to the virtual current position, and generates a simulated signal from the selected damping pattern. For example, if the virtual current position is "2 m from the starting point," damping pattern B associated with this becomes the search solution.

As another example of a data table, as shown in FIG. 7, information on obstructions at a distance on a moving path and an attenuation pattern of a received signal received by a moving body 53 moving along the above-mentioned moving path at a distance may be prepared. The lower part of FIG. 7 is a graph showing the amount of signal attenuation (dB) versus the position (distance) from the starting point.

In FIG. 7, the obstruction information of utility pole 62a is linked at a position (distance) of 1 m from the starting point, and the obstruction information of utility pole 62b is linked at a position (distance) of 3 m from the starting point.

In the process of creating this data table, when new obstruction information and the amount of attenuation of the received signal are acquired, they are linked together. For example, as shown in FIG. 7, when obstruction information of utility pole 62a and the attenuation pattern of the received signal are acquired at a position (distance) of 1 m from the starting point, they are linked together, and when obstruction information of utility pole 62b and the attenuation pattern of the received signal are acquired at a position (distance) of 3 m from the starting point, they are linked together to create a data table.

Next, the acquisition unit 171 acquires the travel time of the moving body 53.

Next, the acquisition unit 171 obtains a virtual current position on the first movement path based on the obtained running time and the first movement speed. In this case, the acquisition unit 171 may obtain the virtual current position on the first movement path from, for example, the product of the running time and the first movement speed.

Next, the generation unit 172 refers to the data table stored in the memory unit 174 and selects an attenuation pattern for a position corresponding to the virtual current position obtained by the acquisition unit 171. In such a case, for example, if the position corresponding to the virtual current position is 3 m from the starting point, the acquisition unit 171 refers to the data table in FIG. 7 and selects an attenuation pattern of the simulated signal for the current position 3 m from the starting point.

Next, the generator 172 generates a simulation signal according to the selected attenuation pattern. This makes it possible to generate a simulation signal according to a virtual position.

Although an embodiment of the present invention has been described, this embodiment is presented as an example and is not intended to limit the scope of the invention. Such a novel embodiment can be embodied in various other forms, and various omissions, substitutions, and modifications can be made without departing from the gist of the invention. This embodiment and its modifications are included in the scope and gist of the invention, and are included in the scope of the invention and its equivalents described in the claims.

1 Simulation signal output device 2 Gateway station simulation unit 3 Satellite simulation unit 4 Mobile unit simulation unit 11 ODU
13 First stepless attenuator 14 IDU
15 Second stepless attenuator 17 Attenuation control section 19 Evaluation device 21 Modem 22 Modem 31 Delay device section 41 Modem 43 Modem 100 Mobile satellite communication system

51 Gateway station 52 Satellite 53 Mobile object 54 Shield 60 Travel path 61 Mercury lamp 62 Utility pole 171 Acquisition unit 172 Generation unit 173 Output unit 174 Storage unit

Claims (6)

1. A simulation signal output device for simulating a mobile satellite communication system, the simulation signal output device outputting a simulation signal that can be received from a satellite by a mobile object moving along a first moving path at a first moving speed,
a signal output device for mobile satellite communication, the signal output device comprising: an attenuation means for attenuating a newly received first evaluation signal by referring to a time-series simulation signal that reflects the first moving speed and attenuation caused by an obstruction that blocks the signal from the satellite when moving along the first moving path. 2. The simulation signal output device for mobile satellite communication according to claim 1, further comprising a simulation signal generating means for generating the simulation signal based on position information relating to a position of an obstruction that blocks a signal from the satellite when the mobile body moves along the first movement path and on the first movement speed. A simulation signal output device for simulating a mobile satellite communication system that outputs a simulation signal that can be received from a satellite by a mobile object moving along a first moving path at a first moving speed, comprising:
an output means for outputting a time-series simulation signal reflecting the first moving speed and attenuation caused by an obstruction that blocks a signal from the satellite when moving along the first moving path ,
A storage means for storing an attenuation model in which shielding object information relating to a type and/or width of a shielding object and an attenuation pattern relating to a pattern of attenuation of a signal due to the shielding object are associated with each other, the attenuation model having the shielding object information as an input and the attenuation pattern as an output;
a shielding information acquisition means for acquiring the shielding information of a shield that blocks a signal from the satellite when the moving body moves along the first movement path;
a simulation signal generating means for generating a simulation signal from the attenuation pattern output by inputting the obstruction information acquired by the obstruction information acquiring means into the attenuation model stored in the memory means . 1. A simulation signal output device for simulating a mobile satellite communication system, the simulation signal output device outputting a simulation signal that can be received from a satellite by a mobile object moving along a first moving path at a first moving speed,
an output means for outputting a time-series simulation signal reflecting the first moving speed and attenuation caused by an obstruction that blocks a signal from the satellite when moving along the first moving path ,
a storage means for storing a data table in which attenuation patterns relating to the attenuation patterns for each position on the first moving path are linked to each other;
A travel time acquisition means for acquiring a travel time of the moving body;
a current position calculation means for calculating a virtual current position on a first movement path based on the travel time acquired by the travel time acquisition means and the first movement speed;
an attenuation pattern selection means for selecting the attenuation pattern for a position corresponding to the virtual current position calculated by the current position calculation means, by referring to the data table stored in the storage means;
A simulation signal output device for mobile satellite communications , further comprising simulation signal generating means for generating a simulation signal from the attenuation pattern selected by said attenuation pattern selecting means . A storage means for storing an attenuation model in which shielding object information relating to a type and/or width of a shielding object and an attenuation pattern relating to a pattern of attenuation of a signal due to the shielding object are associated with each other, the attenuation model having the shielding object information as an input and the attenuation pattern as an output;
a shielding information acquisition means for acquiring the shielding information of a shield that blocks a signal from the satellite when the moving body moves along the first movement path;
2. The simulation signal output device for mobile satellite communication according to claim 1, further comprising: a simulation signal generating means for generating a simulation signal from the attenuation pattern output by inputting the obstruction information acquired by the obstruction information acquiring means into the attenuation model stored in the memory means. 1. A simulation signal output device for simulating a mobile satellite communication system, the simulation signal output device outputting a simulation signal that can be received from a satellite by a mobile object moving along a first moving path at a first moving speed,
a second attenuation means for attenuating a second evaluation signal to be newly transmitted by referring to a time-series simulation signal that reflects the first moving speed and attenuation caused by an obstruction that blocks the signal from the satellite when moving along the first moving path;
a transmitting antenna for transmitting the second evaluation signal attenuated by the second attenuation means.