Wireless communication systems and mobile stations

Abstract

This suppresses sections where the line section and the corresponding CH do not match. [Solution] The wireless communication system comprises a mobile station and a plurality of base stations, wherein a line section has at least one branch, and the line sections branching off from the line section are designated as a first branch line section and a second branch line section, and the plurality of base stations include a first base station positioned corresponding to the first branch line section at the branch and a second base station positioned corresponding to the second branch line section at the branch, and the mobile station switches the frequency for wireless communication based on the signal with the higher received signal strength between the signal from the first base station and the signal from the second base station.

Description

Technical Field

[0004]

[0001] The technology disclosed in this specification relates to wireless communication technology between a mobile station and a base station.

Background Art

[0002] Train radio that performs voice communication or data communication between a mobile station mounted on a train or the like and a base station installed on the ground is manually or automatically switched to a radio frequency channel (hereinafter referred to as CH) corresponding to the running section.

[0003] When the CH is manually switched, for example, a train driver presses a CH switching button of an operating device at a CH switching point such as a station to switch the CH, but switching errors may occur when there are multiple CHs.

[0004] To solve this problem, in the wireless communication system shown in Patent Document 1, the CH is automatically switched using a switching signal from a base station for CH switching installed on the ground.

Prior Art Documents

Patent Documents

[0005]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0006] In a conventional wireless communication system, the section may branch in two directions, and one of the branched sections may maintain the same CH as before the branch, while the other branched section may automatically switch to a CH different from that before the branch.

[0007] In that case, a mobile station moving to a different channel line than the one before the branching needs to receive only the confirmation signal from the channel switching confirmation base station installed on the branched channel, which is a different channel line than the one before the branching, and then switch channels.

[0008] Therefore, to prevent the wrong signal from being received from a base station used for confirming channel switching on the branched section of track, which uses the same channel as the section before the branch, base stations for confirming channel switching are not installed near the branch. Base stations for confirming channel switching need to be installed, for example, on the section of track several hundred meters away from the branch.

[0009] As a result, the base station for confirming channel switching is installed away from the branch line, so from immediately after the branch until the confirmation signal is received from the base station for confirming channel switching on the branched section of the line, it is necessary to operate on the channel of the line before the branch, which creates a problem where the line and channel do not match in that section.

[0010] Having sections where the line section and the channel (CH) do not match is undesirable because it can lead to the inability to conduct radio communications in those sections, and can also cause delays in the timing of train drivers manually switching channels if the channel switching operation is not performed properly.

[0011] The technology disclosed in this specification was developed in consideration of the problems described above, and is a technology for suppressing sections where the line section and the corresponding CH do not coincide. [Means for solving the problem]

[0012] A first aspect of the technology disclosed in this specification is a wireless communication system comprising a mobile station for moving along a line section and a plurality of base stations for wireless communication with the mobile station, wherein the line section has at least one branch, and the line sections branching off from the line section at the branch are designated as a first branch line section and a second branch line section, and the plurality of base stations include a first base station positioned corresponding to the first branch line section at the branch and a second base station positioned corresponding to the second branch line section at the branch, wherein the mobile station switches the frequency for wireless communication based on the signal with the higher received signal strength between the signal from the first base station and the signal from the second base station. [Effects of the Invention]

[0013] According to at least a first aspect of the technology disclosed in this specification, it is possible to determine which base station's signal to select based on the RSSI difference between signals from a first base station and a second base station positioned corresponding to each line section at a junction. Therefore, channel switching can be performed automatically near the junction, and sections where the line section and the corresponding channel do not match can be suppressed.

[0014] Furthermore, the purposes, features, aspects, and advantages related to the technology disclosed in this specification will become even clearer from the detailed description and accompanying drawings provided below. [Brief explanation of the drawing]

[0015] [Figure 1] This figure shows an example of the configuration of a wireless communication system according to an embodiment. [Figure 2] This is an enlarged view showing an example of the configuration near the branch in the embodiment. [Figure 3] This figure shows examples of wireless communication frames for normal base station transmission, base station transmission for channel switching confirmation, and mobile station reception according to the embodiment. [Figure 4] This diagram conceptually illustrates an example of the configuration of a base station for determining channel switching according to an embodiment. [Figure 5]It is a diagram conceptually showing an example of the configuration of a base station for CH switching determination related to an embodiment. [Figure 6] It is a diagram showing an example of the configuration of a mobile station related to an embodiment. [Figure 7] It is a flowchart showing an example of the CH switching operation of a wireless communication system related to an embodiment. [Figure 8] It is a flowchart showing an example of the detailed operation of step ST2 in FIG. 7. [Figure 9] It is a flowchart showing an example of the detailed operation of step ST5 in FIG. 7. [Figure 10] It is a diagram showing an example of the configuration of a wireless communication system related to an embodiment. [Figure 11] It is a diagram showing an example of the configuration of a wireless communication system related to an embodiment.

Mode for Carrying Out the Invention

[0016] Hereinafter, embodiments will be described with reference to the accompanying drawings. In the following embodiments, detailed features and the like are also shown for the purpose of explaining the technology, but they are examples, and not all of them are necessarily essential features for the embodiments to be implementable.

[0017] Note that the drawings are schematically shown, and for convenience of explanation, omissions or simplifications of the configuration are made in the drawings as appropriate. Also, the mutual relationships of the sizes and positions of the configurations shown in different drawings are not necessarily accurately described and can be changed as appropriate. Also, in drawings such as a plan view that is not a cross-sectional view, hatching may be added to facilitate understanding of the content of the embodiment.

[0018] Also, in the explanations shown below, the same reference numerals are used to illustrate the same components, and their names and functions are also assumed to be the same. Therefore, detailed explanations thereof may be omitted to avoid duplication.

[0019] Furthermore, in the descriptions contained in this specification, when a certain component is described as "equipped with," "includes," or "has," unless otherwise specified, it is not an exclusive expression that excludes the existence of other components.

[0020] Furthermore, even if ordinal numbers such as "first" or "second" are used in the descriptions contained herein, these terms are used for convenience to facilitate understanding of the embodiments, and the contents of the embodiments are not limited to the order that may result from these ordinal numbers.

[0021] <First Embodiment> The wireless communication system and mobile station according to this embodiment will be described below.

[0022] <About the configuration of the wireless communication system> Figure 1 shows an example of the configuration of a wireless communication system according to this embodiment. As illustrated in Figure 1, the wireless communication system comprises at least one mobile station 2 and a plurality of base stations capable of wireless communication with the mobile station 2. The mobile station 2 is mounted on a train and is mobile along the railway line.

[0023] When a train on line section A1 passes through junction 100 and proceeds to line section A2 on the same CH, the mobile station 2 mounted on the train at train position 1 first communicates with the normal base station 51 on frequency fA via antenna 151 within the area 51A1 of the normal base station 51.

[0024] Next, as the train passes through area 61A1 of the CH switching notification base station 61, the mobile station 2 mounted on the train at train position 1 receives a CH switching notification signal transmitted via antenna 161 on frequency fA from the CH switching notification base station 61, and then passes through junction 100 in this state.

[0025] Then, mobile station 2 alternately receives channel switching confirmation signals from a leaky coaxial cable (i.e., LCX) 172 connected to a channel switching confirmation base station 72 laid near branch 100 of line section A2 after branching, and from an LCX 171 connected to a channel switching confirmation base station 71 laid near branch 100 of line section B after branching. Here, the channel switching confirmation base station 72 transmits the channel switching confirmation signal at frequency fA. Meanwhile, the channel switching confirmation base station 71 transmits the channel switching confirmation signal at frequencies fA and fB.

[0026] When a train on line A1 passes through junction 100 and proceeds to line A2 on the same channel, the distance between the train and LCX 172 is short, so the channel switching confirmation signal from the channel switching confirmation base station 72, which has a high received signal strength indicator (RSSI), is selected by the mobile station 2. As a result, the frequency fA does not switch in response to the channel switching confirmation signal from the channel switching confirmation base station 72, and the mobile station 2 mounted on the train at train position 4 communicates with the normal base station 52 via antenna 152 at frequency fA within the normal base station 52 area 52A2.

[0027] Furthermore, if a train on line A2 passes through junction 100 and proceeds to line A1 on the same CH, the mobile station 2 mounted on the train at train position 4 first communicates with the normal base station 52 via antenna 152 on frequency fA within the area 52A2 of the normal base station 52.

[0028] Next, as the train passes near junction 100, mobile station 2 alternately receives channel switching confirmation signals from LCX172 of base station 72, which is installed near junction 100 in line section A2, and from LCX171 of base station 71, which is installed near junction 100 in line section B.

[0029] In this case, regardless of which channel switching confirmation signal is received, mobile station 2 has not received a channel switching notification signal in advance, so frequency fA does not switch, and it communicates with base station 51 via antenna 151 at frequency fA within area 51A1 of base station 51.

[0030] On the other hand, when a train on line A1 passes through junction 100 and proceeds to line B on a different CH, the mobile station 2 mounted on the train at train position 1 first communicates with the normal base station 51 via antenna 151 on frequency fA within the area 51A1 of the normal base station 51.

[0031] Next, as the train passes through area 61A1 of the CH switching notification base station 61, the mobile station 2 mounted on the train at train position 1 receives a CH switching notification signal transmitted via antenna 161 on frequency fA from the CH switching notification base station 61, and then passes through junction 100 in this state.

[0032] Then, mobile station 2 alternately receives channel switching confirmation signals from LCX172 of base station 72, which is installed near branch 100 of line section A2 after the branching, and from LCX171 of base station 71, which is installed near branch 100 of line section B after the branching.

[0033] When a train on line A1 passes through junction 100 and proceeds to line B on a different channel, the distance between the train and LCX 171 is short, so the channel switching confirmation signal from the channel switching confirmation base station 71, which has a high RSSI, is selected by the mobile station 2. As a result, in response to the channel switching confirmation signal from the channel switching confirmation base station 71, the frequency switches from fA to fB, and the mobile station 2 mounted on the train at train position 3 communicates with the normal base station 53 via antenna 153 at frequency fB within the area 53B of the normal base station 53.

[0034] Furthermore, if a train on line section B passes through junction 100 and proceeds to line section A1 on a different CH, the mobile station 2 mounted on the train at train position 3 first communicates with the normal base station 53 via antenna 153 on frequency fB within the area 53B of the normal base station 53.

[0035] Next, as the train passes through area 62B of the base station 62 for channel switching warnings, mobile station 2 receives a channel switching warning signal transmitted via antenna 162 at frequency fB from the base station 62 for channel switching warnings, and then passes through junction 100 in this state.

[0036] Then, mobile station 2 alternately receives channel switching confirmation signals from LCX172 of base station 72, which is installed near junction 100 of line section A2, and from LCX171 of base station 71, which is installed near junction 100 of line section B.

[0037] When a train on line B passes through junction 100 and proceeds to line A1 on a different channel, the distance between the train and LCX 171 is short, so the channel switching confirmation signal from base station 71, which has a high RSSI, is selected by mobile station 2. As a result, mobile station 2 receives the channel switching confirmation signal transmitted from LCX 171 at frequency fB, but does not receive the channel switching confirmation signal transmitted from LCX 172 at frequency fA, and therefore switches to frequency fA. Then, mobile station 2 communicates with base station 51 via antenna 151 at frequency fA within area 51A1 of base station 51.

[0038] As described later, the base station 71 for channel switching confirmation includes a base station 271 for channel switching confirmation that transmits a channel switching confirmation signal from line section A to line section B at frequency fA, and a base station 371 for channel switching confirmation that transmits a channel switching confirmation signal from line section B to line section A at frequency fB, and the LCX171 is shared by the shared unit 31.

[0039] Figure 2 is an enlarged view showing an example of the configuration near branch 100 according to this embodiment. The distance 110A between the LCX 172 of the CH switching confirmation base station 72 and line section A2 is equal to the distance 110B between the LCX 171 of the CH switching confirmation base station 71 and line section B. Also, the distance 111 between the LCX 172 of the CH switching confirmation base station 72 and the antenna 21 of the mobile station 2 mounted on the train on line section B increases as the train at train position 3 moves from branch 100 along line section B. Note that LCX 171 and LCX 172 are laid near branch 100, and the distance from branch 100 to the end of each LCX is about a few meters.

[0040] If the input power of the LCX171 of the base station 71 for channel switching confirmation and the input power of the LCX172 of the base station 72 for channel switching confirmation are the same, and distance 111 is 6m, and distances 110A and 110B are 3m, then the separation loss at distance 111 is 10 × LOG(6m / 1.5m) = 3dB, and the separation loss at distances 110A and 110B is 10 × LOG(3m / 1.5m) = 6dB.

[0041] Therefore, the RSSI of mobile station 2 is 3 dB higher at base station 71 for channel switching confirmation than at base station 72 for channel switching confirmation. As the train at train position 3 proceeds from junction 100 to line section B, distance 111 increases while distances 110A and 110B remain unchanged, causing the above RSSI difference to widen further.

[0042] Figure 3 shows examples of wireless communication frames for normal base station transmission, base station transmission for channel switching confirmation, and mobile station reception according to this embodiment.

[0043] In normal base station transmission, base station transmission for channel switching confirmation, and mobile station reception, the data consists of radio frame 0, radio frame 1, radio frame 2, radio frame 3, radio frame 4, radio frame 5, and radio frame X as a single unit.

[0044] The normal base stations 51, 52, and 53 transmit radio frames 0, 2, 3, 4, 5, and X, excluding radio frame 1. The channel switching base stations 71 and 72 transmit radio frame 1 at different times. The mobile station 2 receives the data transmission consisting of these radio frames.

[0045] Wireless frame 1 includes information such as that it is a channel switching base station, its type (e.g., announcement, confirmation, etc.), the channel after switching, and the base station number.

[0046] The channel switching confirmation base stations 71 and 72, which use the same frequency fA, transmit data in radio frame 1 alternately (in other words, at different timings). Specifically, channel switching confirmation base station 71 transmits data D71 in radio frame 1, and channel switching confirmation base station 72 transmits data D72 in radio frame 1.

[0047] Mobile station 2 alternately receives data D71 and data D72 in radio frame 1. Since the regular base station and the base station used for channel switching confirmation are time-synchronized, no radio interference occurs between the regular base station and the base station used for channel switching confirmation.

[0048] <Device configuration> Figure 4 is a conceptual diagram showing an example of the configuration of a base station 71 for channel switching confirmation according to this embodiment. As shown in the example in Figure 4, the base station 71 for channel switching confirmation includes a base station 271 that transmits at frequency fA and is used when a mobile station 2 mounted on a train is traveling from line section A1 to line section B, a base station 371 that transmits at frequency fB and is used when a mobile station 2 mounted on a train is traveling from line section B to line section A1, a sharer 31 for sharing the LCX171 between the base stations 271 and 371, an inter-device coaxial cable CX1 connecting the base stations 271 and 371 to the sharer 31, and an inter-device coaxial cable CX2 connecting the sharer 31 to the LCX171.

[0049] Figure 5 is a conceptual diagram showing an example of the configuration of a base station 72 for channel switching confirmation according to this embodiment. As shown in the example in Figure 5, the base station 72 for channel switching confirmation includes a base station 272 that transmits at frequency fA and is used when a mobile station 2 mounted on a train moves from line section A1 to line section A2, an attenuator (ATT) 32 for matching the input power of LCX171 and LCX172, an inter-device coaxial cable CX3 connecting the base station 272 and the ATT 32, and an inter-device coaxial cable CX4 connecting the ATT 32 and the LCX172.

[0050] Furthermore, when proceeding from line section A2 to line section A1, since a channel switching notification signal has not been received in advance, reception from base station 72 for confirming channel switching will be invalid.

[0051] Figure 6 shows an example of the configuration of a mobile station according to this embodiment. As shown in the example in Figure 6, the mobile station 2 comprises an operation unit 25, a transmitting / receiving unit 22 connected to an antenna 21, a control unit 23 that controls the operation unit 25 and the transmitting / receiving unit 22, and a memory 24 connected to the control unit 23.

[0052] The transmitting / receiving unit 22 can switch the frequency of the signal transmitted and received by the antenna 21 between frequency fA and frequency fB. The antenna 21 and the transmitting / receiving unit 22 are connected by an inter-device coaxial cable CX5. The control unit 23 and the transmitting / receiving unit 22 are connected by control line W1, the control unit 23 and the operation unit 25 are connected by control line W3, and the control unit 23 and the memory 24 are connected by control line W2.

[0053] The control unit 23 determines channel switching based on the RSSI of the signal (radio wave) transmitted from the channel switching base station (channel switching notification base station and channel switching confirmation base station), or a comparison of the said RSSI with threshold information pre-stored in the memory 24.

[0054] The control unit 25 is equipped with a manual channel switching button, and pressing this button sends a signal to the control unit 23 connected to the control unit 25. This signal also allows the channel of the transmitting / receiving unit 22 to be switched manually.

[0055] <Operation> Next, the operation of the wireless communication system according to this embodiment will be described. Figure 7 is a flowchart showing an example of the channel switching operation of the wireless communication system according to this embodiment.

[0056] First, the mobile station 2 mounted on the train begins waiting for channel switching (step ST1 in Figure 7). Next, the mobile station 2 receives a channel switching notification signal from the channel switching notification base station 61 (step ST2 in Figure 7). The reception of the channel switching notification signal will be described later.

[0057] Next, the system determines whether the received channel switching notification signal has been received (steps ST3 and ST4 in Figure 7). If the RSSI is determined to be higher than the threshold, the system proceeds to step ST5. On the other hand, if the RSSI is determined to be lower than the threshold, the system proceeds to step ST9.

[0058] In step ST5, the channel switching confirmation signal from base station 71 and the channel switching confirmation signal from base station 72 are received. The reception of the channel switching confirmation signal will be described later.

[0059] Next, the reception of the received channel switching confirmation signal is determined (steps ST6 and ST7 in Figure 7). If the RSSI is higher than the threshold, it is determined which signal, from channel switching confirmation base station 71 or channel switching confirmation base station 72, has a higher RSSI.

[0060] When the train moves from line section A1 to line section B, the distance 110B between the antenna 21 of the mobile station 2 mounted on the train and the LCX 171 of the CH switching confirmation base station 71 is small. Therefore, the RSSI from the CH switching confirmation signal from the CH switching confirmation base station 71 is higher than that from the CH switching confirmation signal from the CH switching confirmation base station 72. Thus, mobile station 2 selects the CH switching confirmation signal from the CH switching confirmation base station 71 and performs a CH switch from frequency fA to frequency fB (step ST8 in Figure 7).

[0061] On the other hand, when the train moves from line section A1 to line section A2, the distance 110A between the antenna 21 of the mobile station 2 mounted on the train and the LCX 172 of the base station 72 for confirming channel switching is small. Therefore, the RSSI from the base station 72 for confirming channel switching is higher than that from the base station 71 for confirming channel switching. Thus, mobile station 2 selects the channel switching confirmation signal from base station 72 and does not perform channel switching while maintaining the frequency fA (step ST9 in Figure 7).

[0062] Furthermore, as described above, if the RSSI of the channel switching warning signal is determined to be lower than the threshold in step ST4, the process proceeds to step ST9 and the channel switching is not performed.

[0063] Figure 8 is a flowchart showing a detailed example of the operation of step ST2 in Figure 7.

[0064] As shown in Figure 8, first, reception of the channel switching warning signal is started (step ST21 in Figure 8). Next, the RSSI of the channel switching warning signal is measured (step ST22 in Figure 8). Finally, reception of the channel switching warning signal is terminated (step ST23 in Figure 8).

[0065] Figure 9 is a flowchart showing a detailed example of the operation of step ST5 in Figure 7.

[0066] As shown in Figure 9, first, reception of the channel switching confirmation signal from the channel switching confirmation base station 71 and the channel switching confirmation signal from the channel switching confirmation base station 72 is initiated (step ST51 in Figure 9).

[0067] Next, the following steps are repeated any number of times (step ST52 in Figure 9). Specifically, the measurement of the RSSI of the channel switching confirmation signal from the channel switching confirmation base station 71 (step ST53 in Figure 9) and the measurement of the RSSI of the channel switching confirmation signal from the channel switching confirmation base station 72 (step ST54 in Figure 9) are repeated any number of times (for example, Y times) (step ST55 in Figure 9). In other words, the channel switching confirmation signal from the channel switching confirmation base station 71 and the channel switching confirmation signal from the channel switching confirmation base station 72 are received alternately multiple times, and the RSSI of each is measured. Note that the order of steps ST53 and ST54 may be reversed.

[0068] As described above, by repeatedly measuring the RSSI of the channel switching confirmation signal from base station 71 and base station 72, the difference between these channel switching confirmation signals can be determined with high accuracy.

[0069] Then, the reception of the channel switching confirmation signal is terminated (step ST56 in Figure 9).

[0070] In this embodiment, the length of the LCX of the base station for confirming channel switching is determined as follows, based on the train speed at the installation location of the LCX, the time width T of the radio frame shown in Figure 3, and the number of times the channel switching confirmation signal for steps ST51, ST52, ST53, ST54, ST55, and ST56 shown in Figure 9 is received.

[0071] For example, if the train speed is 60 km / h, the time interval T = 500 ms, and the number of receptions Y = 3, then 60000 / 3600 × (500 / 1000 × 3 × 2) = 50 m.

[0072] If the difference between the distance 110B between the antenna 21 and LCX171 of mobile station 2 at branch 100 and the distance 110A between the antenna 21 and LCX172 is small, the accuracy of the RSSI difference can be improved by increasing the number of receptions Y and lengthening the LCX.

[0073] When a signal (radio wave) transmitted from the LCX of a channel-switching base station is received by mobile station 2 mounted on the nearest train, the RSSI (1dB step) is very stable while the train is stopped at the platform, with an accuracy of about 1dB.

[0074] On the other hand, while the train is in motion, instantaneous value fluctuations occur due to multipath fading, which can cause a drop of several dB in RSSI. Therefore, by increasing the number of receptions Y, the RSSI difference can be detected with high accuracy, and as a result, the channel switching accuracy can be improved.

[0075] Furthermore, to improve the accuracy of channel switching, this method may be combined with a method of recognizing the track section using a global positioning system (GPS) in the illuminated section (ground section).

[0076] As described above, the system is configured to determine which base station's signal to select based on the difference in reception levels (RSSI difference) at mobile station 2 due to the separation loss between LCX171 and LCX172 installed on each line section near branch 100 and the antenna 21 of mobile station 2. This allows for automatic channel switching near branch 100, and enables matching of line sections and channels.

[0077] Furthermore, if the number of times the channel switching confirmation signal needs to be received can be reduced due to the track alignment near branch 100, for example, if the track sections immediately separate after the branch, increasing the distance between the track sections and thus increasing the RSSI difference, and the RSSI difference can be determined with sufficiently high accuracy even with fewer receptions of the channel switching confirmation signal, then the length of the LCX can be shortened, thereby reducing construction costs.

[0078] <Second Embodiment> A wireless communication system and a mobile station according to this embodiment will be described. In the following description, components similar to those described in the embodiments described above will be denoted by the same reference numerals, and their detailed descriptions will be omitted as appropriate.

[0079] <About the configuration of the wireless communication system> In the first embodiment, an example was shown in which the branch 100 is located on the running track section. In this embodiment, however, the case where the branch occurs immediately before the platform will be described.

[0080] Figure 10 shows an example of the configuration of a wireless communication system according to this embodiment. As shown in the example in Figure 10, the wireless communication system comprises at least one mobile station 2 and a plurality of base stations capable of wireless communication with the mobile station 2.

[0081] In the example shown in Figure 10, track section A1 has a junction 100 immediately before platform 120. On the other hand, there is no junction at position 101 immediately after platform 120, resulting in a track alignment where track sections A2 and B extend in different directions.

[0082] In this case, the LCX171 of the base station 71 for channel switching confirmation and the LCX172 of the base station 72 for channel switching confirmation are provided at positions parallel to the home 120 and at the same distance (separation) from the home 120.

[0083] For a train stopped at platform 120, traveling from line A1 to line A2, the RSSI of the signal received from LCX172 is higher because LCX172 of the CH switching confirmation base station 72 is closer than LCX171 of the CH switching confirmation base station 71. Therefore, the CH switching confirmation signal from CH switching confirmation base station 72 is selected, and the CH switching is not performed while the frequency fA remains unchanged. In the case of a train stopped at platform 120, traveling from line A2 to line A1, the frequency fA does not switch because a CH switching warning signal has not been received in advance.

[0084] On the other hand, for a train stopped at platform 120 traveling from line A1 to line B, the LCX171 of the CH switching confirmation base station 71 is closer than the LCX172 of the CH switching confirmation base station 72, resulting in a higher RSSI for the signal received from LCX171. Therefore, the CH switching confirmation signal transmitted at frequency fA from the CH switching confirmation base station 71 is selected, and the CH is switched from frequency fA to frequency fB. For a train stopped at platform 120 traveling from line B to line A1, the CH switching confirmation signal transmitted at frequency fB from the CH switching confirmation base station 71 is selected, and the CH is switched from frequency fB to frequency fA.

[0085] <Effects> As described above, the system is configured to determine which base station's signal to select for channel switching based on the difference in reception levels (RSSI difference) at mobile station 2 due to the separation loss between LCX171 and LCX172 installed at home 120 and the antenna 21 of mobile station 2. Therefore, channel switching can be performed automatically on home 120.

[0086] <Third Embodiment> A wireless communication system and a mobile station according to this embodiment will be described. In the following description, components similar to those described in the embodiments described above will be denoted by the same reference numerals, and their detailed descriptions will be omitted as appropriate.

[0087] <About the configuration of the wireless communication system> In the first embodiment, an example was shown in which the branch 100 is located on the running track section. In this embodiment, however, the case where the branch occurs immediately before and immediately after the platform will be described.

[0088] Figure 11 shows an example of the configuration of a wireless communication system according to this embodiment. As illustrated in Figure 11, the wireless communication system comprises at least one mobile station 2 and a plurality of base stations capable of wirelessly communicating with the mobile station 2.

[0089] In the example shown in Figure 11, the railway lines intersect at grade, and it is possible to travel between line A1 and line A2, between line A1 and line B2, between line B1 and line A2, and between line B1 and line B2.

[0090] When a train on track A1 passes through junction 100, platform 120, and then junction 101 located immediately after platform 120, and proceeds to track A2 on the same CH, the mobile station 2 mounted on the train at train position 1 first communicates with the normal base station 51 on frequency fA via antenna 151 within area 51A of the normal base station 51. Here, since the mobile station 2 has not received a CH switching notification signal in advance, it rejects the CH switching confirmation signal from the LCX 174 connected to the CH switching confirmation base station 74 on track A1.

[0091] Next, at home 120, a channel switching notification signal is received from LCX163 connected to channel switching notification base station 63 at frequency fA. In this state, channel switching confirmation signals are alternately received from LCX173 of channel switching confirmation base station 73 and LCX171 of channel switching confirmation base station 71, which are installed near the branch 101. Here, channel switching confirmation base stations 73 and 71 transmit channel switching confirmation signals at frequencies fA and fB.

[0092] When a train on line A1 passes through junctions 100 and 101 and proceeds to line A2 on the same CH, the distance between the train and LCX 173 is short, so the CH switching confirmation signal from the CH switching confirmation base station 73, which has a high RSSI, is selected by the mobile station 2. As a result, frequency fA does not switch in response to the CH switching confirmation signal from the CH switching confirmation base station 73, and the mobile station 2 mounted on the train at train position 4 continues to communicate with the normal base station 51 via antenna 151 on frequency fA within the normal base station 51's area 51A.

[0093] Conversely, if a train on line A2 passes through junctions 101 and 100 and proceeds to line A1 on the same channel, after receiving a channel switching notification signal transmitted from LCX163 at frequency fA, the mobile station 2 selects the channel switching confirmation signal from the channel switching confirmation base station 74, which has a higher RSSI. As a result, frequency fA does not switch in response to the channel switching confirmation signal from the channel switching confirmation base station 74, and the mobile station 2 mounted on the train at train position 1 continues to communicate with the normal base station 51 via antenna 151 at frequency fA within the normal base station 51 area 51A. Here, the channel switching confirmation base stations 74 and 75 transmit channel switching confirmation signals at frequencies fA and fB.

[0094] When a train on line A1 passes through junction 100, platform 120, and then junction 101, and proceeds to line B2 on a different channel, the mobile station 2 mounted on the train at train position 1 first communicates with the normal base station 51 on frequency fA via antenna 151 within area 51A of the normal base station 51. Here, since the mobile station 2 has not received a channel switching notification signal in advance, it rejects the channel switching confirmation signal from the LCX 174 of the channel switching confirmation base station 74 on line A1.

[0095] Next, at home 120, the system receives a channel switching notification signal transmitted at frequency fA from the LCX163 of the channel switching notification base station 63. In this state, it alternately receives channel switching confirmation signals from the LCX173 of the channel switching confirmation base station 73 and the LCX171 of the channel switching confirmation base station 71, which are installed near the branch 101.

[0096] When a train on track A1 passes through junctions 100 and 101 and proceeds to track B2 on a different channel, the distance between the train and LCX 171 is short, so the channel switching confirmation signal from the channel switching confirmation base station 71, which has a high RSSI, is selected by the mobile station 2. As a result, in response to the channel switching confirmation signal from the channel switching confirmation base station 71, the frequency is switched to fB, and the mobile station 2 mounted on the train at train position 3 communicates with the normal base station 53 via antenna 153 at frequency fB within the area 53B of the normal base station 53.

[0097] Conversely, if a train on line section B2 passes through junctions 101 and 100 and proceeds to line section A1 on a different channel, after receiving a channel switching notification signal transmitted from LCX163 at frequency fB, the mobile station 2 selects the channel switching confirmation signal from the channel switching confirmation base station 74, which has a higher RSSI. As a result, it switches to frequency fA in response to the channel switching confirmation signal from the channel switching confirmation base station 74, and the mobile station 2 mounted on the train at train position 1 communicates with the normal base station 51 via antenna 151 at frequency fA within the normal base station 51 area 51A.

[0098] If a train on track B1 passes through junctions 100 and 101 and proceeds to track A2 on a different channel, after receiving a channel switching notification signal transmitted from LCX 163 at frequency fB, the mobile station 2 selects the channel switching confirmation signal from the channel switching confirmation base station 73, which has a higher RSSI, because the distance between the train and LCX 173 is short. As a result, it switches to frequency fA in response to the channel switching confirmation signal from the channel switching confirmation base station 73, and the mobile station 2, mounted on the train at train position 4, continues to communicate with the normal base station 51 via antenna 151 at frequency fA within the normal base station 51 area 51A.

[0099] Conversely, if a train on line A2 passes through junctions 101 and 100 and proceeds to line B1 on a different channel, after receiving a channel switching notification signal transmitted from LCX163 at frequency fA, the mobile station 2 selects the channel switching confirmation signal from the channel switching confirmation base station 75, which has a higher RSSI. As a result, it switches to frequency fB in response to the channel switching confirmation signal from the channel switching confirmation base station 75, and the mobile station 2 communicates with the normal base station 53 via antenna 153 at frequency fB within the area 53B of the normal base station 53.

[0100] If a train on line section B1 passes through junctions 100 and 101 and proceeds to line section B2 on the same channel, after receiving a channel switching notification signal transmitted from LCX 163 at frequency fB, the mobile station 2 selects the channel switching confirmation signal from the channel switching confirmation base station 71, which has a high RSSI, because the distance between the train and LCX 171 is short. As a result, the frequency fB does not switch in response to the channel switching confirmation signal from the channel switching confirmation base station 71, and the mobile station 2 mounted on the train at train position 3 communicates with the normal base station 53 via antenna 153 at frequency fB within the normal base station 53 area 53B.

[0101] Conversely, if a train on line B2 passes through junctions 101 and 100 and proceeds to line B1 on the same channel, after receiving a channel switching notification signal transmitted from LCX163 at frequency fB, the mobile station 2 selects the channel switching confirmation signal from the channel switching confirmation base station 75, which has a high RSSI. As a result, the frequency fB does not switch in response to the channel switching confirmation signal from the channel switching confirmation base station 75, and the mobile station 2 communicates with the normal base station 53 via antenna 153 at frequency fB within the area 53B of the normal base station 53.

[0102] As described above, after receiving a channel switching notification signal from the channel switching notification base station 63 installed on platform 120, signals are alternately received from LCXs connected to two channel switching confirmation base stations installed on each line section near junction 100 or junction 101. Then, the system determines which channel switching confirmation base station's signal to select based on the RSSI difference derived from the distance to the antenna 21 of the mobile station 2. With this configuration, even with complex track layouts such as level crossings, channel switching can be performed automatically near junctions, and the line section and channel can be matched.

[0103] <Regarding the effects resulting from the multiple embodiments described above> Next, examples of the effects produced by the multiple embodiments described above will be shown. In the following description, the effects will be described based on the specific configurations illustrated in the multiple embodiments described above, but they may be replaced with other specific configurations illustrated in this specification to the extent that similar effects are produced. That is, for convenience, in the following, only one of the corresponding specific configurations may be described as representative, but the specific configuration described as representative may be replaced with other corresponding specific configurations.

[0104] Furthermore, such substitutions may be made across multiple embodiments. That is, the configurations exemplified in different embodiments may be combined to produce similar effects.

[0105] According to the embodiment described above, the wireless communication system comprises a mobile station 2 for moving along a line section and a plurality of base stations for communicating wirelessly with the mobile station 2. Here, the plurality of base stations correspond to, for example, a normal base station 51, a normal base station 52, a normal base station 53, a base station for CH switching notification 61, a base station for CH switching notification 62, a base station for CH switching notification 63, a base station for CH switching notification 71, a base station for CH switching notification 72, a base station for CH switching notification 73, a base station for CH switching notification 74, a base station for CH switching notification 75, a base station for CH switching confirmation 271, a base station for CH switching confirmation 272, a base station for CH switching confirmation 371, and so on. A line section has at least one branch (only branch 100, or branch 100 and branch 101). Line sections that branch off from a line section by a branch are designated as the first branch line section and the second branch line section. For example, in Figures 1 and 10, if the first branch line section corresponds to line section B, then the second branch line section corresponds to line section A2 or line section A1. Furthermore, for example in Figure 11, if the first branch line corresponds to line B2, then the second branch line corresponds to line A2, line A1, or line B1. Multiple base stations include a first base station positioned corresponding to the first branch line in the branch and a second base station positioned corresponding to the second branch line in the branch. For example in Figures 1 and 10, if the first base station corresponds to the CH switching confirmation base station 71, then the second base station corresponds to the CH switching confirmation base station 72. Also, for example in Figure 11, if the first base station corresponds to the CH switching confirmation base station 71, then the second base station corresponds to the CH switching confirmation base station 73, CH switching confirmation base station 74, or CH switching confirmation base station 75. The mobile station 2 then switches the frequency for wireless communication based on the signal with the higher received signal strength between the signal from the first base station and the signal from the second base station.

[0106] With this configuration, it is possible to determine which base station's signal to select for channel switching based on the RSSI difference from LCX171 and LCX172 installed on each line section near branch 100. Therefore, channel switching can be performed automatically near branch 100, and sections where the line section and the corresponding channel do not match can be suppressed.

[0107] Furthermore, the same effect can be achieved even if other configurations exemplified in this specification are appropriately added to the above configuration, that is, if other configurations in this specification that are not mentioned as the above configuration are appropriately added.

[0108] Furthermore, according to the embodiments described above, the first base station is connected to the first leaky coaxial cable laid along the first branch line section at the branch. The second base station is connected to the second leaky coaxial cable laid along the second branch line section at the branch. For example, in Figures 1 and 10, if the first leaky coaxial cable corresponds to LCX171, the second leaky coaxial cable corresponds to LCX172. Also, for example, in Figure 11, if the first leaky coaxial cable corresponds to LCX171, the second leaky coaxial cable corresponds to LCX173, LCX174, or LCX175. The mobile station 2 then switches the frequency for wireless communication based on the signal with the higher received signal strength between the signal transmitted from the first leaky coaxial cable and the signal transmitted from the second leaky coaxial cable. With this configuration, the distance between each LCX and the line section can be set to be equal, and the LCX of the line section selected after branching can be placed further from the mobile station than the LCX that was not selected after branching, so that the channel can be switched appropriately based on the received signal strength.

[0109] Furthermore, according to the embodiment described above, the line section has multiple branches. A first base station is located corresponding to the first branch line section at each branch. A second base station is located corresponding to the second branch line section at each branch. The mobile station 2 switches the frequency for wireless communication for each branch based on the signal with the higher received signal strength between the signal from the first base station and the signal from the second base station. With this configuration, even when multiple branches are provided, the channel can be appropriately switched at each branch, and the channel corresponding to the line section can be matched.

[0110] Furthermore, according to the embodiment described above, the mobile station 2 receives signals from the first base station and signals from the second base station alternately multiple times. With this configuration, the RSSI measurement of the channel switching confirmation signal from the channel switching confirmation base station 71 and the RSSI measurement of the channel switching confirmation signal from the channel switching confirmation base station 72 are repeated, making it possible to determine the difference between these channel switching confirmation signals with high accuracy.

[0111] According to the embodiments described above, the mobile station switches the frequency for wireless communication based on the signal with the higher received signal strength among the signal from the first base station and the signal from the second base station.

[0112] With this configuration, the mobile station can determine which channel switching base station signal to select based on the RSSI difference from LCX171 and LCX172 installed on each line section near junction 100. Therefore, channel switching can be performed automatically near junction 100, and sections where the line section and the corresponding channel do not match can be suppressed.

[0113] Furthermore, the same effect can be achieved even if other configurations exemplified in this specification are appropriately added to the above configuration, that is, if other configurations in this specification that are not mentioned as above configurations are appropriately added.

[0114] Furthermore, according to the embodiment described above, the mobile station 2 switches the frequency for wireless communication based on the signal with the higher received signal strength among the signal transmitted from the first leaky coaxial cable and the signal transmitted from the second leaky coaxial cable. With this configuration, the distance between each LCX and the line section can be set to be equal, and the LCX of the line section selected after branching can be made farther from the mobile station than the LCX that was not selected after branching, so that the CH can be switched appropriately based on the received signal strength.

[0115] Furthermore, according to the embodiment described above, the mobile station 2 switches the frequency for wireless communication at each branch based on the signal with the higher received signal strength between the signal from the first base station and the signal from the second base station. With this configuration, even if multiple branches are provided, the channel switching can be appropriately performed at each branch, and the channel corresponding to the line section can be matched.

[0116] <Modifications of the multiple embodiments described above> In the various embodiments described above, the dimensions, shapes, relative arrangements, or conditions of implementation of each component may also be described, but these are all examples and not limiting in any way.

[0117] Accordingly, countless variations and equivalents not shown are envisioned within the scope of the art disclosed herein. These include, for example, modifications, additions, or omissions of at least one component, as well as the extraction of at least one component from at least one embodiment and its combination with a component from another embodiment.

[0118] Furthermore, unless contradictory, when it is stated that "one" component is provided in the embodiments described above, "one or more" such components may be provided.

[0119] Furthermore, each component in the embodiments described above is a conceptual unit, and the scope of the technology disclosed in this specification includes cases where one component consists of multiple structures, where one component corresponds to a part of a structure, and where multiple components are provided in a single structure.

[0120] Furthermore, each component in the embodiments described above shall include structures having other structures or shapes, as long as they perform the same function.

[0121] Furthermore, the descriptions in this specification are referenced for all purposes related to the present technology and are not considered to be prior art.

[0122] The various aspects of this disclosure are summarized below as an appendix.

[0123] (Note 1) A mobile station for moving along the railway line, The system comprises multiple base stations for wireless communication with the aforementioned mobile station, The aforementioned line section has at least one branch, The sections of track that branch off from the aforementioned section at the aforementioned junction are designated as the first branch section and the second branch section, The plurality of base stations include a first base station located in correspondence with the first branch line section in the branch, and a second base station located in correspondence with the second branch line section in the branch, The mobile station switches the frequency for wireless communication based on the signal with the higher received signal strength among the signal from the first base station and the signal from the second base station. Wireless communication system.

[0124] (Note 2) This is the wireless communication system described in Appendix 1. The first base station is connected to a first leaky coaxial cable laid along the first branch line section at the branch, The second base station is connected to a second leaky coaxial cable laid along the second branch line section at the branch, The mobile station switches the frequency for wireless communication based on the signal with the higher received signal strength among the signal transmitted from the first leaky coaxial cable and the signal transmitted from the second leaky coaxial cable. Wireless communication system.

[0125] (Note 3) A wireless communication system as described in Appendix 1 or 2, The aforementioned line section includes multiple branches, A first base station is positioned corresponding to the first branch line section at each of the aforementioned branches. A second base station is positioned corresponding to the second branch line section at each of the aforementioned branches. The mobile station switches the frequency for wireless communication based on the signal with the higher received signal strength between the signal from the first base station and the signal from the second base station, for each branch. Wireless communication system.

[0126] (Note 4) A wireless communication system described in any one of the appendices 1 to 3, The mobile station receives signals from the first base station and signals from the second base station alternately multiple times. Wireless communication system.

[0127] (Note 5) It is a mobile station that moves along a railway line and communicates wirelessly with multiple base stations. The aforementioned line section has at least one branch, The sections of track that branch off from the aforementioned section at the aforementioned junction are designated as the first branch section and the second branch section, The plurality of base stations include a first base station located in correspondence with the first branch line section in the branch, and a second base station located in correspondence with the second branch line section in the branch, The mobile station switches the frequency for wireless communication based on the signal with the higher received signal strength among the signal from the first base station and the signal from the second base station. Mobile station.

[0128] (Note 6) This is the mobile station described in Appendix 5. The first base station is connected to a first leaky coaxial cable laid along the first branch line section at the branch, The second base station is connected to a second leaky coaxial cable laid along the second branch line section at the branch, The mobile station switches the frequency for wireless communication based on the signal with the higher received signal strength among the signal transmitted from the first leaky coaxial cable and the signal transmitted from the second leaky coaxial cable. Mobile station.

[0129] (Note 7) The mobile station is one of the stations listed in Appendix 5 or 6. The aforementioned line section includes multiple branches, A first base station is positioned corresponding to the first branch line section at each of the aforementioned branches. A second base station is positioned corresponding to the second branch line section at each of the aforementioned branches. The mobile station switches the frequency for wireless communication based on the signal with the higher received signal strength between the signal from the first base station and the signal from the second base station, for each branch. Mobile station. [Explanation of Symbols]

[0130] 1 Train position, 2 Mobile station, 3 Train position, 4 Train position, 21 Antenna, 22 Transceiver unit, 23 Control unit, 24 Memory, 25 Operation unit, 31 Shared unit, 51 Normal base station, 51A area, 51A1 area, 52 Normal base station, 52A2 area, 53 Normal base station, 53B area, 61 Base station for CH switching announcement, 61A1 area, 62 Base station for CH switching announcement, 62B area, 63 Base station for CH switching announcement, 71 Base station for CH switching confirmation, 72 Base station for CH switching confirmation, 73 Base station for CH switching confirmation, 74 Base station for CH switching confirmation, 75 Base station for CH switching confirmation, 100 Branch, 101 Branch, 110A Distance, 110B Distance, 111 Distance, 120 Home, 151 Antenna, 152 Antenna, 153 Antenna, 161 Antenna, 162 Antenna, 163 LCX, 171 LCX, 172 LCX, 173 LCX, 174 LCX, 175 LCX, 271 Base station for CH switching confirmation, 272 Base station for CH switching confirmation, 371 Base station for CH switching confirmation.

Claims

1. A mobile station for moving along the railway line, The system comprises multiple base stations for wireless communication with the aforementioned mobile station, The aforementioned line section has at least one branch, The sections of track that branch off from the aforementioned section at the aforementioned junction are designated as the first branch section and the second branch section, The plurality of base stations include a first base station located in correspondence with the first branch line section in the branch, and a second base station located in correspondence with the second branch line section in the branch, The mobile station switches the frequency for wireless communication based on the signal with the higher received signal strength among the signal from the first base station and the signal from the second base station. Wireless communication system.

2. The wireless communication system according to claim 1, The first base station is connected to a first leaky coaxial cable laid along the first branch line section at the branch, The second base station is connected to a second leaky coaxial cable laid along the second branch line section at the branch, The mobile station switches the frequency for wireless communication based on the signal with the higher received signal strength among the signal transmitted from the first leaky coaxial cable and the signal transmitted from the second leaky coaxial cable. Wireless communication system.

3. A wireless communication system according to claim 1 or 2, The aforementioned line section includes multiple branches, A first base station is positioned corresponding to the first branch line section at each of the aforementioned branches. A second base station is positioned corresponding to the second branch line section at each of the aforementioned branches. The mobile station switches the frequency for wireless communication based on the signal with the higher received signal strength among the signal from the first base station and the signal from the second base station, for each branch. Wireless communication system.

4. A wireless communication system according to claim 1 or 2, The mobile station receives signals from the first base station and signals from the second base station alternately multiple times. Wireless communication system.

5. It is a mobile station that moves along a railway line and communicates wirelessly with multiple base stations. The aforementioned line section has at least one branch, The sections of track that branch off from the aforementioned section at the aforementioned junction are designated as the first branch section and the second branch section, The plurality of base stations include a first base station located in correspondence with the first branch line section in the branch, and a second base station located in correspondence with the second branch line section in the branch, The mobile station switches the frequency for wireless communication based on the signal with the higher received signal strength among the signal from the first base station and the signal from the second base station. Mobile station.

6. The mobile station described in claim 5, The first base station is connected to a first leaky coaxial cable laid along the first branch line section at the branch, The second base station is connected to a second leaky coaxial cable laid along the second branch line section at the branch, The mobile station switches the frequency for wireless communication based on the signal with the higher received signal strength among the signal transmitted from the first leaky coaxial cable and the signal transmitted from the second leaky coaxial cable. Mobile station.

7. A mobile station according to claim 5 or 6, The aforementioned line section includes multiple branches, A first base station is positioned corresponding to the first branch line section at each of the aforementioned branches. A second base station is positioned corresponding to the second branch line section at each of the aforementioned branches. The mobile station switches the frequency for wireless communication based on the signal with the higher received signal strength among the signal from the first base station and the signal from the second base station, for each branch. Mobile station.

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