Wireless communication system, wireless communication method, and communication control system

Abstract

This radio communication system comprises: a communication requirement management unit 301 which, when performing radio communication between two parties of which at least one is a moving body, sets the number of times in which transmission of each of safety information and non-safety information, i.e. information other than the safety information, is to be repeated in accordance with the quality of the radio communication; and a radio control unit 302 which controls the radio communication in accordance with the set number of repetitions. As a result, a radio communication system, a radio communication method, and a communication control system are provided with which it is possible not only to perform radio communication pertaining to both safety information and non-safety information but to also secure stable radio communication pertaining to the safety information.

Description

[Technical Field]

[0001] The present invention relates to a radio communication system, a radio communication method, and a communication control system. In particular, the present invention relates to a radio communication system, a radio communication method, and a communication control system suitable for performing radio communication including safety information and non-safety information between two parties at least one of which is a mobile body. [Background Art]

[0002] In recent years, systems that use radio communication to transmit safety information between, for example, railway trackside equipment and on-board equipment have been used. It is also conceivable to use radio communication to communicate non-safety information such as audio information and video information.

[0003] Patent Document 1 discloses a radio communication system. In this radio communication system, trains travel on the same route. The route is divided into a plurality of sections. When the reception level in each section changes after data transmitted by a mobile station mounted on a train at a constant transmission rate is received by the upper station side, the reception level is set in four stages A to D based on the number of retransmissions. A corresponds to the case where the reception level is the highest (the number of retransmissions is zero), and D corresponds to the case where the reception level is the lowest (the number of retransmissions is large). The transmission rate is set to S1 when the reception level is A, S2 when the reception level is B, S3 when the reception level is C, and S4 when the reception level is D (S1>S2>S3>S4).

[0004] Patent Document 2 describes a data distribution method. In this data distribution method, based on train operation information, the radio base station starts transmitting a beacon to detect the mobile station's entry into the radio base station's communication area when the mobile station mounted on the train enters the communication area. A timer is also used to ensure that file transmission is performed only while the mobile station is within the communication area, thereby preventing wasted operation and channel usage at the radio base station. Furthermore, the radio base station checks the radio wave conditions before transmitting a beacon, and if the default channel is congested, it uses an available channel as the channel to be used. Immediately after entering the communication area, it notifies the mobile station of this channel on the default channel, and then performs file transmission on the channel to further improve transmission efficiency. [Prior art documents] [Patent Documents]

[0005] [Patent Document 1] Japanese Patent Publication No. 2020-108009 [Patent Document 2] Japanese Patent Publication No. 2005-20365 [Overview of the initiative] [Problems that the invention aims to solve]

[0006] However, due to network congestion and degraded signal quality, there are situations where communication resources are insufficient. In such cases, it may become impossible to communicate not only non-security information but also security information properly. The present invention aims to provide a wireless communication system, a wireless communication method, and a communication control system that can transmit both security information and non-security information wirelessly, and can ensure stable wireless communication for security information. [Means for solving the problem]

[0007] To solve the above problems, the present invention provides a wireless communication system comprising: a setting unit that sets the number of transmission repetitions for security information and non-security information (information other than security information) according to the quality of the wireless communication when wireless communication is performed between two entities, at least one of which is a mobile entity; and a control unit that controls the wireless communication according to the set number of repetitions.

[0008] Here, the settings unit can set the number of repetitions for each type of information, according to the priority determined by the type of security information and non-security information, when the quality of wireless communication deteriorates. In this case, the number of repetitions can be set according to the importance of the information. Furthermore, the settings unit can increase the number of repetitions of security information compared to non-security information when the quality of wireless communication deteriorates. In this case, the number of repetitions of security information, which is more important than non-security information, can be increased. Furthermore, the settings unit can increase the number of repetitions of security information when the quality of wireless communication deteriorates. In this case, the number of repetitions can be increased for security information, which is considered more important. Furthermore, the settings unit can increase the predetermined number of repetitions if the quality of the wireless communication does not reach a predetermined level. In this case, more stable wireless communication can be ensured for security information, which is of higher importance. Furthermore, the configuration unit can reduce the number of repetitions of non-security information when the quality of wireless communication deteriorates. In this case, the consumption of communication resources for less important non-security information can be reduced. Furthermore, when the quality of wireless communication recovers to a predetermined level, the settings unit can reset the number of repetitions for transmitting security information and non-security information to a predetermined initial number. In this case, wireless communication can be performed while simultaneously transmitting both security information and non-security information. Furthermore, the number of repetitions can be set to the upper limit of continuous transmission or retransmission. In this case, controlling the wireless communication becomes easier.

[0009] Furthermore, the quality of wireless communication can be determined by at least one of the quality of wireless communication reception and communication congestion. This makes it easier to determine the quality of wireless communication. Furthermore, reception quality can be estimated based on the relationship between RSRP (Reference Signal Received Power) and SINR (Signal to Interference and Noise Power Ratio). In this case, reception quality can be determined with greater accuracy. Furthermore, at least one of the RSRP and SINR can be obtained from at least one of the radio base station and the radio terminal. In this case, the RSRP and SINR can be obtained more easily. Furthermore, communication congestion can be estimated based on the relationship between transmission delay time and estimated population along the railway line. In this case, communication congestion can be determined with greater accuracy. Furthermore, the transmission delay time can be obtained from application software for mobile devices. In this case, the transmission delay time can be obtained more easily.

[0010] Furthermore, the present invention is a wireless communication method comprising: a setting unit that sets the number of transmission repetitions for security information and non-security information, which is information other than security information, according to the quality of the wireless communication when wireless communication is performed between two entities, at least one of which is a mobile entity; and a control unit that controls the wireless communication according to the set number of repetitions.

[0011] Furthermore, the present invention relates to a communication control system for wireless communication between two entities, at least one of which is a mobile entity, wherein at least one of the two entities comprises a setting unit that sets the number of transmission repetitions for security information and non-security information (information other than security information) according to the quality of wireless communication, and a control unit that controls wireless communication according to the set number of repetitions. [Effects of the Invention]

[0012] According to the present invention, it is possible to provide a radio communication system, a radio communication method, and a communication control system that can perform radio communication for both safety information and non-safety information, and can secure stable radio communication for safety information. BRIEF DESCRIPTION OF THE DRAWINGS

[0013] [Figure 1] It is a conceptual diagram showing the overall configuration of the communication control system in the present embodiment. [Figure 2] It shows a state where the quality of radio communication is low. [Figure 3] It shows a state where the quality of radio communication is low. [Figure 4] It shows a first example of the functional configuration and processing flow of the radio communication system. [Figure 5] It shows a second example of the functional configuration and processing flow of the radio communication system. [Figure 6] It shows a third example of the functional configuration and processing flow of the radio communication system. [Figure 7] It shows a fourth example of the functional configuration and processing flow of the radio communication system. [Figure 8] It is a diagram showing a reception quality determination method in a communication quality determination unit. [Figure 9] It is a diagram showing a communication congestion determination method in a communication quality determination unit. [Figure 10] It is a diagram showing control when communication quality determination results are made in two stages of "low" and "normal". [Figure 11] It is a diagram showing control when communication quality determination results are made in N stages of "level 1, 2, ..., N". [Figure 12] It is a diagram showing the data structure of a communication requirement management unit when communication quality determination results are made in two stages of "low" and "normal" and radio communication is controlled. [Figure 13]This figure shows the data structure of the communication requirement management unit when communication quality is determined in N levels of "level 1, 2, ..., N" to control wireless communication. [Figure 14] This figure shows the control flow for dynamically changing the number of repetitions of application communication in a configuration that estimates communication quality from parameters acquired from railway-oriented applications.

Mode for Carrying Out the Invention

[0014] Hereinafter, embodiments of the present invention will be described in detail with reference to the accompanying drawings. <Description of Overall Configuration of Communication Control System S> FIG. 1 is a conceptual diagram showing the overall configuration of the communication control system S according to the present embodiment. The communication control system S includes ground equipment 101, which is communication equipment installed on the ground, wireless communication systems 102 and 107 that perform wireless communication, and on-board equipment 108 mounted on a train 106.

[0015] The ground equipment 101 is communication equipment installed on the ground that handles wireless communication with a train 106, which is an example of a mobile body. The ground equipment 101 is installed, for example, in an operation control center that instructs the operation of the train 106. Further, the ground equipment 101 is installed, for example, in trackside equipment arranged along the line of the train 106 to control the operation of the train 106. Here, the ground equipment 101 transmits and receives safety information and non-safety information to and from the train 106. "Safety information" is information necessary for operating a mobile body such as the train 106. Examples of the safety information include train position information, speed limits, train control information including any of stopping limit points, camera videos used during remote operation, and voice call information used as a substitute for train radio. Further, "non-safety information" is information other than safety information. Examples of the non-safety information include information on on-board content distributed to passengers on the train 106. As shown in Figure 1, the ground equipment 101 controls and manages the operation of train 106. The ground equipment 101 also functions as a maintenance terminal. Furthermore, it monitors video footage captured by cameras installed on train 106 and transmits onboard content provided on train 106.

[0016] The wireless communication system is mounted on at least one of the ground equipment 101 and the on-board equipment 108, and connected to them. In Figure 1, however, the wireless communication system is mounted on both the ground equipment 101 and the on-board equipment 108. That is, as shown in the figure, the wireless communication system 102 is located on the ground equipment 101 side, and the wireless communication system 107 is located on the on-board equipment 108 side. The wireless communication system 102 is connected to the ground equipment 101 and communicates wirelessly with the on-board equipment 108 via the Radio Access Network (RAN). The wireless communication system 107 is also connected to the on-board equipment 108 and communicates wirelessly with the ground equipment 101 via the Radio Access Network and the on-board control unit 109.

[0017] This section describes the case where either a privately owned RAN, RAN103 (also shown as RAN1), or a public RAN, RAN104 (also shown as RAN2), operated by an external communication carrier, is used as the wireless access network. RAN103, the privately owned RAN, is, for example, a communication network owned by a railway operator that operates train 106. RAN104, the public RAN, is, for example, a communication network owned by a mobile network operator (MNO), and is also connected to the internet 105. By using this communication network, the mobile network operator provides services such as 4G, 5G, and LTE (Long Term Evolution) communication systems.

[0018] RAN103 or RAN104 connects to wireless communication system 102. When train 106 enters the communication range of RAN103 or RAN104, it connects to wireless communication system 107 installed on train 106. As a result, ground equipment 101 or onboard equipment 108 communicate with each other via RAN103 or RAN104 using wireless communication systems 102 and 107. The on-board control unit 109 includes wireless terminals used for wireless communication. In this case, the wireless terminals include a wireless terminal for RAN1 and a wireless terminal for RAN2.

[0019] The onboard equipment 108 is mounted on train 106 and controls the equipment within train 106. Here, the onboard equipment 108 is used during remote operation and includes a camera that captures images of the direction of travel of train 106, and a train radio device, which is a wireless communication device for the train. Furthermore, the onboard equipment 108 is equipped with train control devices such as an Automatic Train Operation (ATO) system and an Automatic Train Control (ATC) system. In addition, the onboard equipment 108 includes a monitor device that displays, monitors, and controls the status of various devices, and an onboard content device that provides content on train 106.

[0020] <Description of wireless communication systems 102 and 107> Next, we will explain the wireless communication systems 102 and 107 in more detail. Note that wireless communication systems 102 and 107 have the same configuration. Therefore, in the following explanation, we will use wireless communication system 102 as an example. The wireless communication system 102 includes a communication requirements management unit 301 that manages the conditions for wireless communication, a communication control unit 302 that controls wireless communication, and a communication quality determination unit 303 that determines the quality of communication.

[0021] The communication requirements management unit 301, as will be described in detail later, maintains the relationship between communication application information, which is information about a communication application that operates using wireless communication, and the number of transmission repetitions. In this embodiment, the number of transmission repetitions is the upper limit of continuous transmission or retransmission. In this embodiment, the communication requirements management unit 301 is an example of a setting unit that sets the number of transmission repetitions for security information and non-security information, respectively, according to the quality of wireless communication. The specific method for doing so will be described later.

[0022] The communication control unit 302 controls wireless communication. More specifically, the communication control unit 302 performs communication control of packets of the communication application. Furthermore, the communication control unit 302 is an example of a control unit that performs wireless communication control according to a set number of repetitions.

[0023] The communication quality determination unit 303 determines the quality of the wireless communication. The communication quality determination unit 303 determines the quality of the wireless communication based on at least one of the wireless communication reception quality and communication congestion. The communication quality determination unit 303 estimates the reception quality based on the relationship between RSRP (Reference Signal Received Power) and SINR (Signal to Interference and Noise Power Ratio) obtained from RAN 103 or RAN 104. RSRP is the strength of the radio waves received by the wireless communication systems 102 and 107. A high (large) RSRP indicates a strong radio wave and good reception quality. Conversely, a low (small) RSRP indicates a weak radio wave and poor reception quality. On the other hand, SINR is a parameter that indicates the power ratio of usable signals among the radio signals, including noise, received by the wireless communication systems 102 and 107. A high (large) SINR indicates a good communication environment, while a low (small) SINR indicates a poor communication environment. Furthermore, the communication quality determination unit 303 estimates communication congestion based on the relationship between the transmission delay time and the estimated population along the line. A high (large) transmission delay time indicates communication congestion, while a low (small) transmission delay time indicates no communication congestion. Similarly, a high (large) estimated population along the line indicates communication congestion, while a low (small) population estimate indicates no communication congestion.

[0024] The communication quality determination unit 303 determines the communication quality from various parameters of the communication path and notifies the communication control unit 302 of the result of the communication quality determination. The communication control unit 302 checks the communication requirements management unit 301 based on the result of the communication quality determination. The communication control unit 302 performs communication control based on the determination result of the communication quality determination unit 303 and the check result of the communication requirements management unit 301.

[0025] Figure 1 shows a state of high wireless communication quality. Figure 1 shows a case where both reception quality and communication congestion are good, resulting in high communication quality. In this case, the communication quality determination unit 303 determines "Reception quality: High" and "Communication congestion: None," and outputs a determination result of "Communication quality: High" based on these results.

[0026] Figure 2 illustrates the state of low wireless communication quality. Figure 2 shows a scenario where reception quality is good, but communication quality deteriorates due to congestion during rush hour. Here, RAN104 is connected to user terminals (mobile phones, smartphones, etc.) 201 of general carrier users, generating a large amount of communication traffic. In addition, the increase in the number of trains during rush hour also increases communication traffic from other trains 202. In this case, the communication quality determination unit 303 determines that the reception quality is "high," but that the communication congestion is "congestion present." Based on these results, the communication quality determination unit 303 outputs a determination result of "low communication quality."

[0027] Figure 3 shows a state of low wireless communication quality. Figure 3 shows a case where train 106 has reached the vicinity of the communication range of RAN103 or RAN104, and a deterioration in reception quality from RAN103 or RAN104 is occurring. In this case, the communication quality determination unit 303 detects that the reception quality is lower than normal and determines "Reception quality: Low". On the other hand, it determines "Communication congestion: None" for communication congestion. Based on these results, the communication quality determination unit 303 outputs a determination result of "Communication quality: Low".

[0028] Figure 4 shows a first example of the functional configuration and processing flow of the wireless communication system 102. The communication quality determination unit 303 of the wireless communication system 102 can acquire at least communication channel parameters such as RSRP and SINR from the wireless base station or wireless terminal 401 which constitutes RAN103 or RAN104 in Figure 1. The communication control unit 302 transmits application packets a predetermined number of times to the wireless base station or wireless terminal 401. The communication quality determination unit 303 receives various parameters of the communication path as wireless communication quality information from the wireless base station or wireless terminal 401. The communication quality determination unit 303 then estimates the communication quality from the various parameters of the communication path received from the wireless base station or wireless terminal 401 and transmits the determination result to the communication control unit 302. The communication control unit 302 checks the communication requirements management unit 301 based on the communication quality determination result and obtains information from the communication requirements management unit 301 regarding the number of transmission repetitions according to the communication quality. The communication control unit 302 then performs continuous transmission control or retransmission control accordingly.

[0029] Figure 5 shows a second example of the functional configuration and processing flow of a wireless communication system. The communication quality determination unit 303 of the wireless communication system 102 can acquire at least communication channel parameters such as RSRP and SINR from the wireless base station or wireless terminal 401 which constitutes RAN103 or AN104 in Figure 1. Furthermore, the transmitting wireless communication system 102 (shown at the top of the figure) can obtain communication channel parameters from the wireless base station or wireless terminal 401 (shown at the bottom of the figure) connected to the opposing wireless communication system 102 (shown at the bottom of the figure) via RAN103 and 104 in Figure 1. These parameters are then used by the communication quality determination unit 303, which constitutes the transmitting wireless communication system 102, to determine the communication quality. The communication quality determination unit 303 estimates the communication quality based on the communication path parameters obtained via the opposing wireless communication system 102 and transmits the determination result to the communication control unit 302. The communication control unit 302 checks the communication requirements management unit 301 based on the communication quality determination result and obtains information from the communication requirements management unit 301 regarding the number of transmission repetitions according to the communication quality. The communication control unit 302 then performs continuous transmission control or retransmission control accordingly.

[0030] Figure 6 shows a third example of the functional configuration and processing flow of a wireless communication system. The communication quality determination unit 303 of the wireless communication system 102 can acquire parameters from the railway application (mobile application software) 402, including statistical information on application communication, such as the error rate and transmission delay time. The communication quality determination unit 303 can also acquire parameters from the railway application 402, including parameters related to onboard equipment and the number of passengers boarding and alighting at stations. The communication quality determination unit 303 estimates the communication quality from parameters obtained from the railway application 402 and transmits the determination result to the communication control unit 302. The communication control unit 302 checks the communication requirements management unit 301 based on the communication quality determination result and obtains information from the communication requirements management unit 301 regarding the number of transmissions according to the communication quality. The communication control unit 302 then performs continuous transmission control or retransmission control accordingly.

[0031] Figure 7 shows a fourth example of the functional configuration and processing flow of a wireless communication system. The communication quality determination unit 303 of the wireless communication system 102 can acquire parameters from the railway application 402 (shown at the bottom of the figure), which is connected to the opposing wireless communication system 102 (shown at the bottom of the figure), including either the error rate or the transmission delay time, which are statistical information of the application communication. The communication quality determination unit 303 can also acquire parameters from the railway application 402, which is connected to the opposing wireless communication system 102, including either the onboard equipment or the number of passengers getting on and off at stations. These parameters are then used by the communication quality determination unit 303, which constitutes the transmitting wireless communication system 102, to determine the communication quality. Based on the acquired parameters, the communication quality determination unit 303 estimates the communication quality and transmits the determination result to the communication control unit 302. Based on the communication quality determination result, the communication control unit 302 checks with the communication requirements management unit 301 and obtains information from the communication requirements management unit 301 regarding the number of transmission repetitions according to the communication quality. The communication control unit 302 then performs continuous transmission control or retransmission control accordingly.

[0032] Figure 8 shows the method for determining reception quality in the communication quality determination unit 303. Here, the communication quality determination unit 303 determines the reception quality based on the relationship between RSRP and SINR. The communication quality determination unit 303 determines whether RSRP and SINR have reached predetermined levels. Specifically, the communication quality determination unit 303 sets predetermined thresholds for RSRP and SINR, and if either exceeds this threshold, it determines that the reception quality is "high". Conversely, if both are below this threshold, it determines that the reception quality is "low".

[0033] Figure 9 shows the method for determining communication congestion in the communication quality determination unit 303. Here, the communication quality determination unit 303 determines communication congestion based on the relationship between transmission delay time and the estimated population along the line. The communication quality determination unit 303 determines whether the transmission delay time and the estimated population along the line have reached predetermined levels. Specifically, the communication quality determination unit 303 sets predetermined thresholds for both the transmission delay time and the estimated population along the line, and if either exceeds this threshold, it determines that "communication congestion: present". Conversely, if both are below this threshold, it determines that "communication congestion: absent".

[0034] Figure 10 shows the control process when the communication quality is judged in two stages: "low" and "normal". Figure 10 is a state transition diagram of wireless communication when the communication control unit 302 controls wireless communication according to the communication quality determination result of the communication quality determination unit 303. The communication quality determination unit 303 notifies the communication control unit 302 of the communication quality determination result according to a predetermined time interval. Upon receiving the notification, the communication control unit 302 notifies the communication requirements management unit 301 of either "low" or "normal" as the communication quality determination result, and performs wireless communication according to a predetermined number of repetitions output from the communication requirements management unit 301. For example, when the communication quality was "normal," if the communication control unit 302 receives a "normal" result from the communication quality determination unit 303, it continues the number of repetitions for normal conditions. On the other hand, when the communication quality was "normal," if the communication control unit 302 receives a "low" result from the communication quality determination unit 303, the communication control unit 302 checks with the communication requirements management unit 301, obtains the control parameters for "low" communication quality, and performs wireless communication control according to the obtained number of repetitions.

[0035] Figure 11 shows the control when the communication quality is judged in N levels, "Level 1, 2, ..., N". Here, it is shown that as N increases, the communication quality improves, and as N decreases, the communication quality deteriorates. Figure 11 is a state transition diagram of wireless communication when the communication control unit 302 controls wireless communication according to the communication quality determination result of the communication quality determination unit 303. The communication quality determination unit 303 notifies the communication control unit 302 of the communication quality determination result according to a predetermined time interval. Upon receiving the notification, the communication control unit 302 notifies the communication requirements management unit 301 of one of the levels 1, 2, ..., N as the communication quality determination result, and performs wireless communication according to a predetermined number of repetitions output from the communication requirements management unit 301. For example, when the communication quality is level 2, if the communication control unit 302 receives a result of "level 2" from the communication quality determination unit 303, it continues the number of repetitions for level 2. On the other hand, when the communication quality is level 2, if the communication control unit 302 receives a result of "level 1" from the communication quality determination unit 303, the communication control unit 302 checks with the communication requirements management unit 301, obtains the control parameters for when the communication quality is "level 1", and performs wireless communication control according to the obtained number of repetitions.

[0036] Figure 12 shows the data structure of the communication requirements management unit 301 when controlling wireless communication based on a two-stage determination of communication quality, "low" and "normal," as shown in Figure 10. The communication requirements management unit 301 manages the number of repetitions for determining whether a data name corresponds to safety information, the error rate, the priority, and the two-stage communication quality judgment result ("low" or "normal"). For example, the data for the train control device is "safety information," and its error rate is required to be "very low." The priority is "highest," and the number of transmission repetitions is 3 when the communication quality is "normal," and 5 when the communication quality is "low." If this count is 0, it indicates that no further transmission or retransmission will be performed for this information. In other words, this information will only be transmitted once, the initial time. If this count is 3, it indicates that the maximum number of transmissions or retransmissions is 3. In other words, this information can be transmitted up to 4 times, including the initial transmission.

[0037] Figure 13 shows the data structure of the communication requirements management unit 301 when controlling wireless communication by determining the communication quality in N stages, "Level 1, 2, ..., N," as shown in Figure 11. Here, it is shown that as N increases, the communication quality improves, and as N decreases, the communication quality deteriorates. The communication requirements management unit 301 manages the number of repetitions for determining whether a data name corresponds to safety information, the error rate, the priority, and the N-level communication quality ("Level 1, 2, ..., N") for each data name. For example, the data for the train control device is "safety information," and its error rate is required to be "very low." The priority is "highest," and the number of transmission repetitions is 3 when the communication quality is "Level N." Furthermore, it is 5 times when the communication quality is "Level 2," and 10 times when the communication quality is "Level 1."

[0038] As shown in Figures 12 and 13, when the quality of wireless communication deteriorates, the communication requirements management unit 301 sets the number of repetitions for each type of information, according to the priority determined by the type of security information and non-security information. Furthermore, when the quality of wireless communication deteriorates, the communication requirements management unit 301 increases the number of repetitions for security information to more than the number of repetitions for non-security information. In addition, when the quality of wireless communication deteriorates, the communication requirements management unit 301 may increase the number of repetitions depending on the type of security information. Furthermore, when the quality of wireless communication deteriorates, the communication requirements management unit 301 decreases the number of repetitions for non-security information. Furthermore, when the quality of the wireless communication is restored to a predetermined level, the communication requirements management unit 301 can reset the number of repetitions of transmission of security information and non-security information to a predetermined initial number.

[0039] Figure 14 shows the control flow when dynamically changing the number of application communication repetitions in a configuration that estimates communication quality from parameters obtained from railway application 402. Figure 14 illustrates an example of control when the train control device data does not meet the communication requirements of the application held by the communication requirements management unit 301. In this case, the wireless communication system 102 obtains a parameter indicating a "high error rate" from the railway application 402. The communication requirements management unit 301 then compares this with the communication requirements of the corresponding communication application. In this case, since the error rate requirement exceeds "extremely low," the communication requirements management unit 301 determines that the communication quality is not satisfactory and increases the number of repetitions by 3. That is, it increases the number of repetitions to 8. The communication requirements management unit 301 then outputs the increased number of repetitions. The communication control unit 302 performs wireless communication control according to the increased number of repetitions. In this case, if the quality of the wireless communication does not reach a predetermined level, the communication requirements management unit 301 further increases the predetermined number of repetitions.

[0040] The communication control system S described above has been explained in the context of wireless communication on a railway, such as between ground equipment 101 and train 106, but it is not limited to this. For example, it is not limited to train 106, but any mobile body that requires safety information. Examples of such mobile bodies include ships and airplanes. It can also be applied when an automobile is driven autonomously. Furthermore, it is sufficient if wireless communication is conducted between two entities, at least one of which is a mobile body. In other words, both parties may be mobile bodies. For example, the communication control system S described above can also be applied when wireless communication (satellite communication) is conducted between a satellite and train 106.

[0041] According to the wireless communication system 102 described above, both security information and non-security information can be transmitted wirelessly, and stable communication of security information can be ensured. In other words, even when non-security information such as content information is transmitted wirelessly, security information can be reliably transmitted. This ensures the safety of moving objects such as trains 106.

[0042] <Explanation of wireless communication methods> Here, the processing performed by the wireless communication system 102 can be understood as a wireless communication method comprising: a setting unit that sets the number of transmission repetitions for security information and non-security information (information other than security information) according to the quality of the wireless communication when wireless communication is performed between two parties, at least one of which is a mobile entity; and a control unit that controls the wireless communication according to the set number of repetitions.

[0043] Although this embodiment has been described above, the technical scope of the present invention is not limited to the scope described in the above embodiment. It is clear from the claims that various modifications or improvements made to the above embodiment are also included in the technical scope of the present invention. [Explanation of symbols]

[0044] 101...Ground equipment, 102, 107...Wireless communication system, 103, 104...RAN, 106...Train, 108...On-board equipment, 109...On-board control unit, 301...Communication requirements management unit, 302...Communication control unit, 303...Communication quality determination unit, 401...Wireless base station or wireless terminal, 402...Railway application, S...Communication control system

Claims

1. When two entities, at least one of which is a mobile entity, communicate wirelessly, A setting unit sets the number of transmission repetitions for security information and non-security information (information other than the aforementioned security information), depending on the quality of the wireless communication. A control unit that controls wireless communication according to the set number of repetitions, Equipped with, The quality of the aforementioned wireless communication is estimated based on the population estimate along the line. Wireless communication system.

2. When two entities, at least one of which is a mobile entity, communicate wirelessly, A setting unit sets the number of transmission repetitions for security information and non-security information (information other than the aforementioned security information), depending on the quality of the wireless communication. A control unit that controls wireless communication according to the set number of repetitions, Equipped with, The quality of the aforementioned wireless communication is estimated based on the relationship between the transmission delay time and the estimated population along the route. Wireless communication system.

3. The wireless communication system according to claim 2, wherein the transmission delay time is obtained from the application software for the mobile device.

4. When wireless communication is performed between two entities, at least one of which is a mobile entity, Based on estimated population figures along the railway line, the quality of wireless communication was estimated. Depending on the quality of the aforementioned wireless communication, the number of transmission repetitions is set for each type of information, namely security information and non-security information (information other than security information). The wireless communication is controlled according to the number of repetitions. Wireless communication method.

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