wireless devices

Abstract

A radio device (100) installed in a first moving body comprises a communication unit (110) for receiving position information of a second moving body in which a radio device (200) is installed, and speed information of the second moving body, and a control unit (120) for performing control to: acquire position information of the first moving body, speed information of the first moving body, a sleep state time, and a range over which the radio device (100) and the radio device (200) communicate, or a radius of said range; calculate a first distance on the basis of the speed information of the first moving body, the speed information of the second moving body, and the sleep state time; calculate a sleep state determination distance using the range or the radius of the range, and the first distance; calculate a second distance on the basis of the position information of the first moving body and the position information of the second moving body; and, if the second distance is greater than the sleep state determination distance, migrate the radio device (100) to a sleep state.

Description

Technical Field

[0001] This disclosure relates to a wireless device.

Background Art

[0002] A mobile body is equipped with a wireless device. For example, the mobile body is a train. Here, a technique for displaying the train arrival time on a portable device has been proposed (see Patent Document 1). For example, the portable device calculates the train arrival time using the portable position of the portable device, the train position of the train, and the speed of the train. The portable device displays the train arrival time.

Prior Art Documents

Patent Documents

[0003]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0004] By the way, a wireless device that receives information (hereinafter, the receiving-side wireless device) needs to always be powered on in order to receive the information from a wireless device that transmits the information (hereinafter, the transmitting-side wireless device). However, when the distance between the transmitting-side wireless device and the receiving-side wireless device is far, the receiving-side wireless device does not need to be powered on. Nevertheless, the receiving-side wireless device is powered on. Therefore, the power consumption of the receiving-side wireless device increases.

[0005] An object of this disclosure is to suppress the power consumption of the receiving-side wireless device.

Means for Solving the Problems

[0006] A wireless device according to one aspect of the present disclosure is provided. The wireless device is a receiving wireless device mounted on a first mobile body. The wireless device includes a communication unit that receives location information and speed information of a second mobile body on which a transmitting wireless device is mounted, and the location information of the first mobile body, the speed information of the first mobile body, This is the sleep time. The sleep state time and the communication range between the receiving wireless device and the transmitting wireless device or the radius of the range are obtained, a first distance is calculated based on the speed information of the first moving object, the speed information of the second moving object, and the sleep state time, a sleep state determination distance is calculated using the range or the radius of the range and the first distance, and based on the position information of the first moving object and the position information of the second moving object, This is the distance between the first moving body and the second moving body. The system includes a control unit that calculates a second distance and, if the second distance is greater than the sleep state determination distance, performs control to transition the receiving wireless device to a sleep state. The radius of the range used when calculating the sleep state determination distance is the radius obtained by calculating based on the acquired range, or the radius of the acquired range. [Effects of the Invention]

[0007] According to this disclosure, the power consumption of the receiving wireless device can be reduced. [Brief explanation of the drawing]

[0008] [Figure 1] This is a diagram showing the communication system of Embodiment 1. [Figure 2] This figure shows the hardware of the wireless device according to Embodiment 1. [Figure 3] This is a block diagram showing the functions of the transmitting wireless device in Embodiment 1. [Figure 4] This is a block diagram showing the functions of the base station in Embodiment 1. [Figure 5] This is a block diagram showing the functions of the receiving wireless device in Embodiment 1. [Figure 6] This is a sequence diagram showing an example of processing performed in the communication system of Embodiment 1. [Figure 7] This figure shows an example of a communication system according to Embodiment 2. [Figure 8] This is a sequence diagram (part 1) showing an example of processing performed in the communication system of Embodiment 2. [Figure 9] This is a sequence diagram (part 2) showing an example of processing performed in the communication system of Embodiment 2. [Figure 10] This figure shows an example of a communication system according to Embodiment 3. [Figure 11] This is a sequence diagram (part 1) showing an example of processing performed in the communication system of Embodiment 3. [Figure 12] This is a sequence diagram (part 2) showing an example of processing performed in the communication system of Embodiment 3. [Modes for carrying out the invention]

[0009] The embodiments will be described below with reference to the drawings. The following embodiments are merely examples, and various modifications are possible within the scope of this disclosure.

[0010] Embodiment 1. Figure 1 shows a communication system according to Embodiment 1. The communication system includes a wireless device 100, a wireless device 200, and a base station 300. The wireless device 100 is mounted on a mobile body. This mobile body is also referred to as the first mobile body. The wireless device 200 is also mounted on a mobile body. This mobile body is also referred to as the second mobile body. For example, the first mobile body and the second mobile body are trains, monorails, etc. Also, for example, the first mobile body and the second mobile body are cars moving on roadways, people moving on sidewalks, etc. In the following description, the first mobile body and the second mobile body will be referred to as trains. The first mobile body will be referred to as the first train, and the second mobile body as the second train.

[0011] The second train, equipped with radio equipment 200, is traveling along route 10. Route 10 is a straight path. The direction of travel for the second train is direction D. The first train, equipped with radio equipment 100, is traveling near route 10.

[0012] The wireless device 100 receives the information transmitted by the wireless device 200 and determines whether to transition to the sleep state using the information. As described above, since the wireless device 100 receives the information, it is also referred to as the receiving-side wireless device. The wireless device 200 transmits the information, so it is also referred to as the transmitting-side wireless device. Note that the sleep state means a power-saving mode or a power-off mode.

[0013] The base station 300 communicates with the wireless device 100 and the wireless device 200. The GPS (Global Positioning System) satellite 400 transmits GPS signals to the wireless device 100 and the wireless device 200. The wireless device 100 and the wireless device 200 calculate position information based on the GPS signals. Also, the wireless device 100 and the wireless device 200 may receive position information from GNSS (Global Navigation Satellite System). The distance X1, distance X2, range R1, range R2, and determination position N depicted in FIG. 1 will be described later.

[0014] Next, the hardware of the wireless device 100 will be described. FIG. 2 is a diagram showing the hardware of the wireless device according to Embodiment 1. The wireless device 100 includes a processor 101, a volatile memory device 102, and a non-volatile memory device 103.

[0015] The processor 101 controls the entire wireless device 100. For example, the processor 101 is a CPU (Central Processing Unit), an FPGA (Field Programmable Gate Array), or the like. The processor 101 may be a multi-processor. Also, the wireless device 100 may have a processing circuit.

[0016] The volatile memory device 102 is the main memory of the first train. For example, the volatile memory device 102 is RAM (Random Access Memory). The non-volatile memory device 103 is the auxiliary memory of the first train. For example, the non-volatile memory device 103 is an HDD (Hard Disk Drive) or an SSD (Solid State Drive). Furthermore, the wireless device 200, like the wireless device 100, has a processor, a volatile memory device, and a non-volatile memory device.

[0017] Next, before describing the functions of the wireless device 100, we will describe the functions of the wireless device 200 and the base station 300. Figure 3 is a block diagram showing the functions of the transmitting wireless device of Embodiment 1. The wireless device 200 has a communication unit 210 and a control unit 220.

[0018] Some or all of the communication unit 210 and control unit 220 may be implemented by processing circuits in the wireless device 200. Alternatively, some or all of the communication unit 210 and control unit 220 may be implemented as modules of programs executed by the processor in the wireless device 200.

[0019] The communication unit 210 receives position information of the second train from GNSS. The communication unit 210 may also receive GPS signals from GPS satellite 400.

[0020] When a GPS signal is received, the control unit 220 calculates the position information of the second train based on the GPS signal. Alternatively, the control unit 220 may calculate the position information of the second train based on the signal received from GNSS. The control unit 220 acquires speed information of the second train. For example, the control unit 220 acquires this speed information from a speed sensor installed on the second train. The control unit 220 acquires information on the direction of travel of the second train. For example, the control unit 220 acquires this information from sensors installed on the second train. Alternatively, the control unit 220 may acquire this information by calculating the direction of travel of the second train based on the information obtained from sensors installed on the second train.

[0021] The communications unit 210 transmits the location information of the second train, the speed information of the second train, and the direction of travel information of the second train to the base station 300.

[0022] Figure 4 is a block diagram showing the functions of the base station in Embodiment 1. The base station 300 has a communication unit 310. The communication unit 310 receives information on the position of the second train, the speed of the second train, and the direction of travel of the second train from the radio device 200. The communication unit 310 transmits the position information of the second train, the speed information of the second train, and the direction of travel information of the second train to the wireless device 100. If there are multiple receiving wireless devices, the communication unit 310 may transmit the position information of the second train, the speed information of the second train, and the direction of travel information of the second train to each of the multiple receiving wireless devices.

[0023] Figure 5 is a block diagram showing the functions of the receiving wireless device in Embodiment 1. The wireless device 100 includes a communication unit 110, a control unit 120, a storage unit 130, and a power supply 140.

[0024] The storage unit 130 may be implemented as a storage area reserved in the volatile storage device 102 or the non-volatile storage device 103. Some or all of the communication unit 110 and the control unit 120 may be implemented by processing circuits. Alternatively, some or all of the communication unit 110 and the control unit 120 may be implemented as modules of a program executed by the processor 101.

[0025] The communication unit 110 communicates with the base station 300. The communication unit 110 receives the location information of the second train, the speed information of the second train, and the direction of travel information of the second train. For example, the communication unit 110 receives the location information of the second train, the speed information of the second train, and the direction of travel information of the second train from the base station 300. Alternatively, for example, the communication unit 110 receives the location information of the second train, the speed information of the second train, and the direction of travel information of the second train from the base station 300 via a communication device that can be connected to the wireless device 100.

[0026] The communication unit 110 receives position information of the first train from GNSS. The communication unit 110 may also receive GPS signals from GPS satellites 400.

[0027] The control unit 120 obtains the position information of the first train from the communication unit 110. Furthermore, if a GPS signal is received, the control unit 120 calculates the position information of the first train based on the GPS signal. The control unit 120 then obtains the position information of the first train based on this calculation. Furthermore, the control unit 120 may calculate the position information of the first train based on the signal received from the GNSS.

[0028] The control unit 120 acquires speed information of the first train. For example, the control unit 120 acquires this speed information from a speed sensor installed on the first train. The control unit 120 acquires information on the direction of travel of the first train. For example, the control unit 120 acquires this information from sensors mounted on the first train. Alternatively, the control unit 120 may acquire this information by calculating the direction of travel of the first train based on the information obtained from sensors mounted on the first train.

[0029] The control unit 120 acquires time T. For example, the control unit 120 acquires time T from the storage unit 130. Alternatively, for example, the control unit 120 acquires time T from an external device. For example, the external device is a device that can be connected to the wireless device 100. The diagram of the external device is omitted. Note that time T is the sleep state time. Time T is a predetermined time.

[0030] The control unit 120 acquires the range R1. Range R1 is the range in which wireless device 100 and wireless device 200 communicate. Range R1 is also a predetermined range. The control unit 120 may also acquire the radius of range R1. For example, the control unit 120 acquires range R1 or the radius of range R1 from the storage unit 130. Alternatively, for example, the control unit 120 acquires range R1 or the radius of range R1 from an external device.

[0031] The control unit 120 calculates the distance X1 based on the direction of travel information of the first train, the direction of travel information of the second train, the speed information of the first train, the speed information of the second train, and time T. Specifically, the control unit 120 calculates the distance X1 using equation (1). Note that distance X1 is also called the first distance.

[0032] Distance X1 = Time T × (Speed ​​of the first train - Speed ​​of the second train) ... (1)

[0033] Here, the control unit 120 assigns a positive sign to the speed of the first train and the speed of the second train if the direction of travel indicated by the direction of travel information of the first train and the direction of travel indicated by the direction of travel information of the second train are the same. Also, the control unit 120 may assign different signs to the speed of the first train and the speed of the second train if the direction of travel indicated by the direction of travel information of the first train and the direction of travel indicated by the direction of travel information of the second train are different. For example, if the speed of the first train is assigned a positive sign, the control unit 120 assigns a negative sign to the speed of the second train. Also, for example, if the speed of the second train is assigned a positive sign, the control unit 120 assigns a negative sign to the speed of the first train. If the distance X1 is a negative value, the control unit 120 uses the absolute value.

[0034] The control unit 120 calculates the sleep state determination distance M using the radius of range R1 and the distance X1. Here, if range R1 is obtained, the control unit 120 calculates the radius of range R1. Then, the control unit 120 calculates the sleep state determination distance M using equation (2). Note that the sleep state determination distance M is the distance used to determine whether or not to transition to sleep state.

[0035] Sleep state detection distance M = distance X1 + radius of range R1 ... (2)

[0036] The control unit 120 can calculate the range R2 (= sleep state determination distance M × 2). The control unit 120 calculates the distance X2 based on the position information of the first train and the position information of the second train. Here, distance X2 is also called the second distance. The control unit 120 performs control to transition the wireless device 100 to sleep mode if the distance X2 is greater than the sleep state determination distance M.

[0037] Furthermore, the control unit 120 may perform the following processing. The control unit 120 calculates the determination position N based on the position information of the first train and the sleep state determination distance M. Specifically, the control unit 120 calculates the determination position N using equation (3). For example, the determination position N is the position in the opposite direction to the direction of travel indicated by the direction of travel information of the second train.

[0038] Judgment position N = position information of the first train + sleep state judgment distance M ... (3)

[0039] Figure 1 shows the determination position N. If the position indicated by the position information of the second train is farther than the determination position N, the control unit 120 performs control to put the wireless device 100 into sleep mode.

[0040] When the control unit 120 transitions the wireless device 100 to sleep mode, the control unit 120 switches the power supply 140 to power-off mode or power-saving mode. The duration of the sleep state is time T.

[0041] Next, we will explain the processes performed in the communication system. Figure 6 is a sequence diagram showing an example of processing performed in the communication system of Embodiment 1. (Step ST101) The radio device 200 receives position information of the second train from GNSS. The radio device 200 obtains speed information of the second train. The radio device 200 obtains direction of travel information of the second train. In addition, if the radio device 200 receives a GPS signal from GPS satellite 400, it may calculate the position information of the second train based on the GPS signal. (Step ST102) The radio device 200 transmits the position information of the second train, the speed information of the second train, and the direction of travel information of the second train to the base station 300.

[0042] (Step ST103) The base station 300 transmits the position information of the second train, the speed information of the second train, and the direction of travel information of the second train to the radio device 100. If there are multiple transmitting wireless devices, the base station 300 may combine the information received from the multiple transmitting wireless devices and transmit that information to the wireless device 100. (Step ST104) The radio device 100 receives position information of the first train from GNSS. The radio device 100 acquires speed information of the first train. The radio device 100 acquires direction of travel information of the first train. In addition, if the radio device 100 receives a GPS signal from GPS satellite 400, it may calculate the position information of the first train based on the GPS signal.

[0043] (Step ST105) The wireless device 100 calculates the distance X1 based on the direction of travel information of the first train, the direction of travel information of the second train, the speed information of the first train, the speed information of the second train, and time T. (Step ST106) The wireless device 100 calculates the sleep state determination distance M using the distance X1 and the radius of the range R1. (Step ST107) The wireless device 100 calculates the distance X2 based on the position information of the first train and the position information of the second train. (Step ST108) The wireless device 100 determines whether the distance X2 is greater than the sleep state determination distance M. The distance X2 is assumed to be greater than the sleep state determination distance M. (Step ST109) The wireless device 100 enters a sleep state for a period of time T.

[0044] Furthermore, in Figure 6, the wireless device 100 receives information about the second train via the base station 300. The wireless device 100 may also receive information about the second train from the wireless device 200 without going through the base station 300. The wireless device 100 may correct the distance X1 using the acceleration of the first train and the acceleration of the second train.

[0045] According to Embodiment 1, the wireless device 100 enters a sleep state when the distance between the transmitting wireless device and the receiving wireless device is large. Therefore, the power consumption of the wireless device 100 is suppressed.

[0046] Furthermore, the communication unit 110 does not need to receive information on the direction of travel of the second train. The control unit 120 does not need to acquire information on the direction of travel of the first train. The control unit 120 may calculate the distance X1 based on the speed information of the first train, the speed information of the second train, and time T. Specifically, the control unit 120 calculates the distance X1 using equation (1). The control unit 120 calculates the distance X1 without regard to the sign of the speed.

[0047] The above describes the case where wireless device 100 is the receiving wireless device and wireless device 200 is the transmitting wireless device. However, wireless device 100 may be the transmitting wireless device and wireless device 200 may be the receiving wireless device. The same effect as described above is achieved even when wireless device 100 is the transmitting wireless device and wireless device 200 is the receiving wireless device.

[0048] Embodiment 2. Next, Embodiment 2 will be described. Embodiment 2 will mainly describe the differences from Embodiment 1. In Embodiment 2, the explanation of matters common to Embodiment 1 will be omitted. Embodiment 1 described the case where the second train travels along a straight path 10. For example, Embodiment 2 describes the case where the second train travels along a path that includes curves.

[0049] Figure 7 shows an example of a communication system according to Embodiment 2. The communication system further includes a map information management device 500. The map information management device 500 connects to the base station 300 via a network. The network is either a wired or wireless network. The map information management device 500 manages map information.

[0050] A second train equipped with a wireless device 200 travels along route 11. Route 11 includes curves. A first train equipped with a wireless device 100 travels near route 11. For example, when the second train rounds a curve, the first and second trains come into temporary close proximity. When the two trains come into temporary close proximity, and using the technology of Embodiment 1, the wireless device 100 may become active. However, since the two trains are only coming into temporary close proximity, the active state is undesirable. Therefore, Embodiment 2 describes a case in which such a situation can be prevented.

[0051] The communication unit 110 may receive map information from the map information management device 500 via the base station 300. The control unit 120 may acquire map information from the communication unit 110. Alternatively, the control unit 120 may acquire map information from the storage unit 130. The control unit 120 acquires route information for the second train. For example, the control unit 120 acquires this route information from the storage unit 130. Alternatively, for example, the control unit 120 acquires this route information from an external device.

[0052] The control unit 120 calculates the distance X3 using map information, route information, the position information of the first train, and the position information of the second train. The distance X3 is also called the third distance. Furthermore, the control unit 120 may calculate the distance X3 each time it acquires the position information of the first train. The control unit 120 may also calculate the distance X3 each time the communication unit 110 receives the position information of the second train. The control unit 120 may also calculate the distance X3 each time the communication unit 110 receives map information. In addition, if the control unit 120 is unable to acquire new position information of the first train or receive new position information of the second train, it may use the old position information of the first train or the old position information of the second train to calculate the distance X3.

[0053] The control unit 120 performs control to put the wireless device 100 into sleep mode if the distance X3 is greater than the sleep mode determination distance M. The control unit 120 does not put the wireless device 100 into sleep mode if the distance X3 is less than or equal to the sleep mode determination distance M.

[0054] Next, we will explain the processes performed in the communication system. Figure 8 is a sequence diagram (part 1) showing an example of processing performed in the communication system of Embodiment 2. (Step ST111) The radio device 200 receives position information of the second train from GNSS. The radio device 200 obtains speed information of the second train. The radio device 200 obtains direction of travel information of the second train. In addition, if the radio device 200 receives a GPS signal from GPS satellite 400, it may calculate the position information of the second train based on the GPS signal. (Step ST112) The radio device 200 transmits the position information of the second train, the speed information of the second train, and the direction of travel information of the second train to the base station 300. (Step ST113) The base station 300 transmits the position information of the second train, the speed information of the second train, and the direction of travel information of the second train to the radio device 100. If there are multiple transmitting wireless devices, the base station 300 may combine the information received from the multiple transmitting wireless devices and transmit that information to the wireless device 100.

[0055] (Step ST114) The map information management device 500 transmits map information to the base station 300. (Step ST115) The base station 300 transmits map information to the radio device 100. If there are multiple receiving radio devices, the base station 300 may transmit map information to multiple receiving radio devices. (Step ST116) The radio device 100 receives position information of the first train from GNSS. The radio device 100 acquires speed information of the first train. The radio device 100 acquires direction of travel information of the first train. In addition, if the radio device 100 receives a GPS signal from GPS satellite 400, it may calculate the position information of the first train based on the GPS signal.

[0056] Figure 9 is a sequence diagram (part 2) showing an example of processing performed in the communication system of Embodiment 2. (Step ST121) The wireless device 100 calculates the distance X1 based on the direction of travel information of the first train, the direction of travel information of the second train, the speed information of the first train, the speed information of the second train, and time T. (Step ST122) The wireless device 100 calculates the sleep state determination distance M using the distance X1 and the radius of the range R1.

[0057] (Step ST123) The wireless device 100 calculates the distance X3 using the map information, the route information of the second train, the position information of the first train, and the position information of the second train. (Step ST124) The wireless device 100 determines whether the distance X3 is greater than the sleep state determination distance M. The distance X3 is assumed to be greater than the sleep state determination distance M. (Step ST125) The wireless device 100 enters sleep mode.

[0058] According to Embodiment 2, even when the first train and the second train are temporarily close to each other, unnecessary active states are reduced, resulting in a high power consumption reduction effect.

[0059] Embodiment 3. Next, Embodiment 3 will be described. Embodiment 3 will mainly describe the differences from Embodiment 2. In Embodiment 3, the explanation of matters common to Embodiment 2 will be omitted. Wireless communication signals can become difficult to receive depending on the circumstances. For example, this can occur when there are tall buildings around the base station 300 or when the weather is bad. In such situations, the timing of the transition to sleep mode will be delayed. Embodiment 3 describes a method to address this situation.

[0060] Figure 10 shows an example of a communication system according to Embodiment 3. The communication system further includes a weather information management device 600. The weather information management device 600 connects to the base station 300 via a network. The network is either a wired or wireless network. The weather information management device 600 manages weather information.

[0061] Here, base station 300 receives information from radio device 200. For example, if there are tall buildings around base station 300, the received radio signal strength of base station 300 will be low. When the received radio signal strength of base station 300 is low, it is difficult for base station 300 to reliably receive information from radio device 200. Therefore, radio device 100 adds a margin to distance X1. In other words, radio device 100 corrects distance X1. Also, if the weather is bad, it is difficult for base station 300 to reliably receive information from radio device 200. Therefore, radio device 100 adds a margin to distance X1. In other words, radio device 100 corrects distance X1.

[0062] The following mainly explains the correction of distance X1. The communications unit 110 may receive weather information from the base station 300. The weather information indicates the weather conditions at the location where the base station 300 is located.

[0063] The control unit 120 may correct the distance X1 based on the weather information. For example, if the weather information indicates cloudy skies, the control unit 120 adds a first value corresponding to cloudy skies to the distance X1. If the weather information indicates rain, the control unit 120 adds a second value corresponding to rain to the distance X1. The second value is greater than the first value. In this way, the control unit 120 adds a larger value to the distance X1 the worse the weather. Also, for example, if the amount of precipitation or rain clouds indicated by the weather information is Y, the control unit 120 calculates a parameter P1 (= a × Y). a is a fixed value. The control unit 120 adds the parameter P1 to the distance X1.

[0064] The control unit 120 acquires information indicating that the location of the base station 300 is included in an area with low received radio wave strength. For example, the control unit 120 may acquire information indicating that the location of the base station 300 is included in an area with low received radio wave strength based on the location information of the base station 300 and information indicating an area with low received radio wave strength. The control unit 120 may also acquire information indicating that the location of the base station 300 is included in an area with low received radio wave strength if the received radio wave strength received by the communication unit 110 from the base station 300 is below a predetermined threshold. The received radio wave strength is the received radio wave strength when the base station 300 receives information from the radio device 200. The control unit 120 may also acquire information indicating that the location of the base station 300 is included in an area with low received radio wave strength from the base station 300 via the communication unit 110.

[0065] The control unit 120 may correct the distance X1 if it obtains information indicating that the location of the base station 300 is in an area with low received radio wave strength. For example, the control unit 120 adds a predetermined value to the distance X1. Alternatively, if the control unit 120 obtains such information, it may correct the distance X1 based on the received radio wave strength. For example, if the received radio wave strength is Z, the control unit 120 calculates the parameter P2 (= b / Z), where b is a fixed value. The control unit 120 then adds the parameter P2 to the distance X1.

[0066] Furthermore, if the control unit 120 acquires information indicating that the location of the base station 300 is in an area with low received radio wave strength, the control unit 120 adds a value corresponding to the weather information and a predetermined value to the distance X1. Also, if the control unit 120 acquires such information, it may correct the distance X1 based on the weather information and the received radio wave strength. For example, the control unit 120 adds a value corresponding to the weather information and parameter P2 to the distance X1. For example, the control unit 120 adds parameter P1 and parameter P2 to the distance X1. Here, the corrected distance X1 is referred to as distance X4. Distance X4 is also called the fourth distance.

[0067] Next, we will explain the processes performed in the communication system. Figure 11 is a sequence diagram (part 1) showing an example of processing performed in the communication system of Embodiment 3. (Step ST131) The radio device 200 receives position information of the second train from GNSS. The radio device 200 obtains speed information of the second train. The radio device 200 obtains direction of travel information of the second train. In addition, if the radio device 200 receives a GPS signal from GPS satellite 400, it may calculate the position information of the second train based on the GPS signal. (Step ST132) The radio device 200 transmits the position information of the second train, the speed information of the second train, and the direction of travel information of the second train to the base station 300. (Step ST133) The base station 300 transmits the position information of the second train, the speed information of the second train, and the direction of travel information of the second train to the radio device 100. If there are multiple transmitting wireless devices, the base station 300 may combine the information received from the multiple transmitting wireless devices and transmit that information to the wireless device 100. (Step ST134) The map information management device 500 transmits map information to the base station 300.

[0068] (Step ST135) The base station 300 transmits map information to the radio device 100. If there are multiple receiving radio devices, the base station 300 may transmit map information to multiple receiving radio devices. (Step ST136) The weather information management device 600 transmits weather information to the base station 300. (Step ST137) The base station 300 transmits weather information to the radio device 100. If there are multiple receiving radio devices, the base station 300 may transmit weather information to multiple receiving radio devices. (Step ST138) The radio device 100 receives position information of the first train from GNSS. The radio device 100 acquires speed information of the first train. The radio device 100 acquires direction of travel information of the first train. In addition, if the radio device 100 receives a GPS signal from GPS satellite 400, it may calculate the position information of the first train based on the GPS signal.

[0069] Figure 12 is a sequence diagram (part 2) showing an example of processing performed in the communication system of Embodiment 3. (Step ST141) The wireless device 100 calculates the distance X1 based on the direction of travel information of the first train, the direction of travel information of the second train, the speed information of the first train, the speed information of the second train, and time T. (Step ST142) The wireless device 100 corrects the distance X1 based on weather information. As a result, the wireless device 100 obtains the distance X4, which is the corrected distance X1. Furthermore, if the wireless device 100 obtains information indicating that the location of the base station 300 is included in an area with low received radio wave strength, it may correct the distance X1. (Step ST143) The wireless device 100 calculates the sleep state determination distance M using the distance X4 and the radius of the range R1. Specifically, the wireless device 100 calculates the sleep state determination distance M using equation (4).

[0070] Sleep state detection distance M = distance X4 + radius of range R1 ... (4)

[0071] (Step ST144) The wireless device 100 calculates the distance X3 using the map information, the route information of the second train, the position information of the first train, and the position information of the second train. (Step ST145) The wireless device 100 determines whether the distance X3 is greater than the sleep state determination distance M. The distance X3 is assumed to be greater than the sleep state determination distance M. (Step ST146) The wireless device 100 enters sleep mode.

[0072] According to Embodiment 3, the wireless device 100 can prevent a delay in the transition timing to the sleep state.

[0073] A modified example of Embodiment 3. Next, a modified example of Embodiment 3 will be described. In the modified example of Embodiment 3, the differences from Embodiment 1 will be mainly described. In the modified example of Embodiment 3, the explanation of matters common to Embodiment 1 will be omitted. In the modified version of Embodiment 3, a combination of Embodiment 1 and Embodiment 3 will be described. Furthermore, the correction of distance X1 is the same as in Embodiment 3. Therefore, the same content as in Embodiment 3 will be omitted from the explanation.

[0074] The control unit 120 calculates the sleep state determination distance M using the radius of the range R1 and the distance X4. More specifically, the control unit 120 calculates the sleep state determination distance M using equation (4). The control unit 120 calculates the distance X2 based on the position information of the first train and the position information of the second train. The control unit 120 performs control to transition the wireless device 100 to sleep mode if the distance X2 is greater than the sleep state determination distance M.

[0075] The control unit 120 may also perform the following processing: The control unit 120 calculates a determination position N based on the position information of the first train and the sleep state determination distance M. If the position indicated by the position information of the second train is farther than the determination position N, the control unit 120 performs control to put the wireless device 100 into sleep state.

[0076] According to a modified version of Embodiment 3, the wireless device 100 can prevent a delay in the transition timing to the sleep state.

[0077] The features of each embodiment described above can be combined with each other as appropriate. [Explanation of symbols]

[0078] 10 routes, 11 routes, 100 wireless device, 101 processor, 102 volatile memory device, 103 non-volatile memory device, 110 communication unit, 120 control unit, 130 memory unit, 140 power supply, 200 wireless device, 210 communication unit, 220 control unit, 300 base station, 310 communication unit, 400 GPS satellite, 500 map information management device, 600 weather information management device.

Claims

1. A radio device which is a receiving radio device mounted on the first mobile body, A communication unit that receives location information of a second mobile body equipped with a transmitting wireless device, and speed information of the second mobile body, A control unit that obtains the position information of the first mobile body, the velocity information of the first mobile body, the sleep state time which is the duration of the sleep state, and the range or radius of the range in which the receiving wireless device and the transmitting wireless device communicate, calculates a first distance based on the velocity information of the first mobile body, the velocity information of the second mobile body, and the sleep state time, calculates a sleep state determination distance using the radius of the range and the first distance, calculates a second distance which is the distance between the first mobile body and the second mobile body based on the position information of the first mobile body and the position information of the second mobile body, and if the second distance is greater than the sleep state determination distance, performs control to transition the receiving wireless device to a sleep state, It has, The radius of the range used when calculating the sleep state determination distance is the radius obtained by calculating based on the acquired range, or the radius of the acquired range. Radio equipment.

2. The control unit, Map information and route information of the second moving object are obtained. Using the map information, the route information, the location information of the first moving object, and the location information of the second moving object, a third distance is calculated, which is the distance along the route indicated by the route information and the distance between the first moving object and the second moving object. If the third distance is greater than the sleep state determination distance, control is performed to put the receiving wireless device into sleep state. The wireless device according to claim 1.

3. A radio device which is a receiving radio device mounted on the first mobile body, A communication unit that receives location information of a second mobile body equipped with a transmitting wireless device, and speed information of the second mobile body, A control unit that obtains the position information of the first mobile body, the velocity information of the first mobile body, the sleep state time which is the duration of the sleep state, and the range or radius of the range in which the receiving wireless device and the transmitting wireless device communicate, calculates a first distance based on the velocity information of the first mobile body, the velocity information of the second mobile body, and the sleep state time, calculates a sleep state determination distance using the radius of the range and the first distance, calculates a determination position based on the position information of the first mobile body and the sleep state determination distance, and controls the receiving wireless device to enter a sleep state if the position indicated by the position information of the second mobile body is farther than the determination position, It has, The radius of the range used when calculating the sleep state determination distance is the radius obtained by calculating based on the acquired range, or the radius of the acquired range. Radio equipment.

4. The communication unit receives the direction of travel information of the second moving object, The control unit acquires the direction of travel information of the first moving body, and calculates the first distance based on the direction of travel information of the first moving body, the direction of travel information of the second moving body, the velocity information of the first moving body, the velocity information of the second moving body, and the sleep state time. A wireless device according to any one of claims 1 to 3.

5. The aforementioned communications unit receives weather information from the base station indicating the weather conditions at the location where the base station is located. The control unit corrects the first distance based on the weather information and calculates the sleep state determination distance using the radius of the range and the corrected first distance, which is the fourth distance. A wireless device according to any one of claims 1 to 3.

6. The aforementioned communication unit communicates with the base station, When the control unit obtains information indicating that the location of the base station is included in an area with low received radio wave strength, it corrects the first distance. The sleep state determination distance is calculated using the radius of the range and the corrected first distance, which is the fourth distance. A wireless device according to any one of claims 1 to 3.

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