Wireless-communication system and relay device

Abstract

The purpose of the present disclosure is to provide a wireless-communication system capable of transmitting a highly accurate mobile-station communication signal to a base station. A relay device 20-i has an amplification unit 21b and a pilot-monitoring control unit 22b therein. The pilot-monitoring control unit 22b detects signal strength of a mobile-station pilot signal included in a mobile-station communication signal and generates a gain control signal S2b indicating the signal strength of the mobile-station pilot signal. An amplifier 210b of the amplification unit 21b amplifies the mobile-station communication signal with a fixed amplification factor AK, and a variable-gain control unit 211b of the amplification unit 21b attenuates the mobile-station communication signal amplified by the amplifier 210b with a variable attenuation rate BK. The variable-gain control unit 211b determines the variable attenuation rate BK on the basis of the signal strength of the mobile-station pilot signal indicated by the gain control signal S2b. A base-station direction amplification factor CK for the mobile-station communication signal by the amplification unit 21b is {CK = AK × BK}.

Description

Wireless communication system and relay device

[0001] The present disclosure relates to a wireless communication system, typified by a train radio system, which performs wireless communication between a base station and a mobile station, and a relay device used in the wireless communication system.

[0002] In a wireless communication system such as a train radio system in which a base station and a mobile station communicate via a leaky coaxial cable, a repeater is used to repeat the wireless communication. As a repeater that automatically sets the gain of an amplifier, for example, there is a repeater that repeats a leaky coaxial cable, as disclosed in Patent Document 1.

[0003] In a conventional wireless communication system including the relay device disclosed in Patent Document 1, the amplification factor (gain) of the mobile station direction amplifier that amplifies the base station communication signal transmitted from the base station to the mobile station and the amplification factor of the base station direction amplifier that amplifies the mobile station communication signal transmitted from the mobile station to the base station are set to a common value by detecting the signal level of the base station communication signal.

[0004] Japanese Patent Application Laid-Open No. 2007-60504

[0005] As mentioned above, in a relay device used in a conventional wireless communication system such as a train radio system, the gain of the mobile station direction amplifier and the gain of the base station direction amplifier are set to a common gain based on the signal level of the base station communication signal.

[0006] For this reason, although the amplification factor of the mobile station direction amplifier could be set according to the signal level of the base station communication signal, the amplification factor of the base station direction amplifier was not set individually based on the mobile station communication signal transmitted from the mobile station.

[0007] Therefore, in the process of transmitting from the mobile station to the base station, the amplification factor could not be set appropriately, and the mobile station communication signal was amplified more than necessary, which increased unnecessary noise other than the mobile station communication signal, leading to a deterioration in communication quality.

[0008] As described above, conventional wireless communication systems have had the problem that mobile station communication signals transmitted from mobile stations cannot be transmitted to the base station with high accuracy.

[0009] The present disclosure aims to solve the above-mentioned problems and provide a wireless communication system and a relay device used in the wireless communication system that can transmit highly accurate mobile station communication signals to a base station.

[0010] A wireless communication system according to the present disclosure includes a base station, a mobile station moving along a moving path, a plurality of communication paths provided along the moving path and carrying communication signals transmitted and received between the base station and the mobile station, and a plurality of relay devices relaying between the plurality of communication paths, wherein a mobile station communication signal wirelessly transmitted from the mobile station is transmitted to the base station by a base station direction transmission process, the communication signal including the mobile station communication signal, the plurality of communication paths function as a mobile station input communication path or a mobile station output communication path for the mobile station communication signal for each of the plurality of relay devices, the mobile station communication signal including a mobile station real signal and a mobile station pilot signal, and each of the plurality of relay devices, upon receiving the mobile station communication signal from the mobile station input communication path, performs a base station direction amplification process to amplify the mobile station communication signal by a base station direction amplification factor, and outputs the amplified new mobile station communication signal from the mobile station output communication path. The mobile station communication system includes a base station direction amplification unit, the base station direction amplification unit having a base station direction amplification factor determination unit that executes a base station direction amplification factor determination process that determines the base station direction amplification factor in accordance with the signal strength of the mobile station pilot signal, and the base station direction transmission process, when executed via first to Kth (≧1) relay devices, is a process in which the mobile station communication signal is wirelessly transmitted from the mobile station to the mobile station input communication path of the first relay device, and then the mobile station communication signal is transmitted to the base station from the mobile station output communication path of the Kth relay device via the first to Kth relay devices in the order of first, second, ..., Kth, and the base station direction amplification unit of the ith (i = any one of 1 to K) relay device, when receiving the mobile station communication signal from the mobile station input communication path, executes the base station direction amplification process with the base station direction amplification factor determined in the base station direction amplification factor determination process, and outputs the new mobile station communication signal obtained by executing the base station direction amplification process to the mobile station output communication path.

[0011] In the wireless communication system of the present disclosure, the first to Kth relay devices involved in the base station direction transmission process each have a base station direction amplification unit that performs a base station direction amplification process to amplify a mobile station communication signal by a base station direction amplification factor and generates a new amplified mobile station communication signal.

[0012] The base station direction amplification factor is determined by a base station direction amplification factor determination unit in accordance with the signal strength of a mobile station pilot signal contained in a mobile station communication signal to be relayed.

[0013] Therefore, even if the mobile station and the base station are far apart, when the base station direction transmission process is executed via the first to Kth relay devices, a highly accurate mobile station communication signal can be transmitted to the base station without degrading the signal level of the mobile station communication signal.

[0014] The objects, features, aspects, and advantages of the present disclosure will become more apparent from the following detailed description and the accompanying drawings.

[0015] Fig. 1 is an explanatory diagram schematically showing the overall configuration of a train radio system according to an embodiment 1. Fig. 2 is an explanatory diagram schematically showing the internal configuration of a repeater used in the train radio system according to an embodiment 1. Fig. 3 is an explanatory diagram schematically showing the internal configuration of a repeater used in the train radio system according to an embodiment 2.

[0016] First Embodiment FIG. 1 is an explanatory diagram schematically illustrating the overall configuration of a train radio system 100 according to a first embodiment, which is a radio communication system of the present disclosure.

[0017] As shown in the figure, the train radio system 100 of the first embodiment includes, as main components, a base station 10, a plurality of (radio) repeater devices 20, a plurality of LCXs 31, a plurality of LCXs 32, and a mobile station 40 that moves along a rail 41, which is a moving path. Note that "LCX (Leaky Coaxial Cable)" means a leaky coaxial cable.

[0018] 1, N relay devices 20-1 to 20-N are shown as the multiple relay devices 20, N LCXs 31-1 to 31-N and N LCXs 32-1 to 32-N are shown as the multiple communication paths, and two mobile stations 40-1 and 40-2 are shown as the mobile stations 40.

[0019] The base station 10 is connected to LCX31-1 and LCX32-1, and the relay device 20-i (i = any one of 1 to (N-1)) is provided between LCX31-i and LCX32-i and LCX31-(i+1) and LCX32-(i+1). The relay device 20-N is connected to LCX31-N and LCX32-N.

[0020] Hereinafter, when referring to relay devices 20-1 to 20-N collectively, they may be simply referred to as "relay devices 20," when referring to LCXs 31-1 to 31-N collectively, they may be simply referred to as "LCX 31," when referring to LCXs 32-1 to 32-N collectively, they may be simply referred to as "LCX 32," and when referring to mobile stations 40-1 and 40-2 collectively, they may be simply referred to as "mobile stations 40."

[0021] Additionally, the communication direction from the mobile station 40 to the base station 10 may be simply referred to as the "uplink direction," and the communication direction from the base station 10 to the mobile station 40 may be simply referred to as the "downlink direction."

[0022] The communication signals handled by the train radio system 100 include mobile station communication signals and base station communication signals. In the train radio system 100, a mobile station communication signal wirelessly transmitted from a mobile station 40 is transmitted to the base station in the uplink direction by a base station direction transmission process, and a base station communication signal transmitted from the base station 10 is transmitted to the mobile station 40 in the downlink direction by a mobile station direction transmission process.

[0023] The multiple communication paths, N LCXs 31 and N LCXs 32, function as input communication paths for mobile stations for mobile station communication signals or output communication paths for mobile stations for mobile station communication signals for each of relay devices 20-1 to 20-N, and also function as input communication paths for base stations for base station communication signals or output communication paths for base stations for base station communication signals.

[0024] In this way, N relay devices 20 are connected in series between the base station 10 and the N LCXs 31 and N LCXs 32. Therefore, the N relay devices 20 relay between the N LCXs 31 and N LCXs 32.

[0025] The train radio system 100 is designed to simultaneously communicate mobile station communication signals and base station communication signals, and in order to prevent deterioration of the communication quality of the two communication signals, two LCXs 31 and 32 are provided in the uplink and downlink directions of the relay device 20.

[0026] The mobile station 40 is a device for wireless communication with the base station 10, and is specifically mounted on a train that travels along rails 41, which are a travel route arranged along LCXs 31-1 to 31-N and LCXs 32-1 to 32-N. Note that the train is not shown in FIG. 1, and only the mobile station 40 is shown. Therefore, the mobile station 40 moves along the rails 41 as the train travels.

[0027] The N LCXs 31 and N LCXs 32 are arranged along the rail 41, which is the travel path, and function as multiple communication paths that carry communication signals (mobile station communication signals, base station communication signals) transmitted and received between the base station 10 and the mobile station 40.

[0028] Each of the N relay devices 20 has a function of relaying a signal of wireless communication (a mobile station communication signal or a base station communication signal) between the base station 10 and the mobile station 40 via the LCXs 31 and 32 .

[0029] The relay function for the mobile station communication signal is to amplify the level of the mobile station communication signal transmitted from the mobile station 40 in accordance with the level of attenuation at the LCX 31 or LCX 32 on the downlink side, which is the mobile station input communication path, and output the signal to the LCX 31 or LCX 32 on the uplink side, which is the mobile station output communication path.

[0030] The relay function for the base station communication signal is to amplify the level of the base station communication signal transmitted from the base station 10 according to the level of attenuation at the LCX31 or LCX32 on the uplink side, which is the base station input communication path, and output the signal to the LCX31 or LCX32 on the downlink side, which is the base station output communication path.

[0031] Since communication between the base station 10 and the mobile station 40, which are far from each other, passes through a large number of LCXs 31 or LCXs 32 and a large number of relay devices 20, it is essential to improve the communication quality of the relay devices 20.

[0032] As described above, the train radio system 100 of embodiment 1 performs a mobile station direction transmission process for transmitting a base station communication signal from the base station 10 to the mobile station 40, and a base station direction transmission process for transmitting a mobile station communication signal from the mobile station 40 to the base station 10.

[0033] 2 is an explanatory diagram showing a schematic internal configuration of a repeater 20-i (i=1 to N) used in the train radio system 100 of the first embodiment. However, the LCX 31-(N+1) and LCX 32-(N+1) on the downstream side of the repeater 20-N may be omitted.

[0034] A base station communication signal transmitted from base station 10 is received by relay device 20-i via LCX 31-i or LCX 32-i on the uplink side. On the other hand, a mobile station communication signal transmitted from mobile station 40 is received by LCX 31-(i+1) or LCX 32-(i+1) on the downlink side. For convenience of explanation, the following description will be made assuming that the base station communication signal is received via LCX 31-i and the mobile station communication signal is received via LCX 31-(i+1).

[0035] The relay device 20-i includes, as main components, branching filters 23a and 23b, amplifiers 21a and 21b, and pilot monitoring control units 22a and 22b.

[0036] The demultiplexer 23a has a first demultiplexing function of receiving a base station communication signal from the base station 10 via the demultiplexer input / output line L21 and outputting the base station communication signal to the amplifier 21a via the amplifier input line L22. The demultiplexer 23a further has a second demultiplexing function, which will be described later.

[0037] The base station communication signal includes a base station actual signal and a base station pilot signal. The base station actual signal is the original communication signal containing the content to be transmitted to the mobile station 40, and the base station pilot signal is a signal for detecting the signal strength of the base station communication signal. The base station communication signal is set to a frequency within the frequency band for base station communication signals, and the base station actual signal and the base station pilot signal are set to mutually different frequencies within the frequency band for base station communication signals. The base station 10 transmits the base station pilot signal at an earlier timing than the base station actual signal.

[0038] The pilot monitoring control unit 22a, which is a base station pilot monitoring unit, monitors a base station pilot signal included in the base station communication signal flowing through the amplifier input line L22, detects the signal strength of the base station pilot signal, and executes base station pilot monitoring processing to generate a gain control signal S2a indicating the base station pilot signal strength. The base station pilot signal strength indicated by the gain control signal S2a, which is a base station control signal, is the power level (dB) of the base station pilot signal. A CW (Continuous wave) wave, for example, can be used as the base station pilot signal.

[0039] The amplifying section 21a, which is a mobile station direction amplifying section, includes an amplifier 210a and a variable gain control section 211a as main components.

[0040] The amplifier 21a, which is a mobile station direction amplifier, receives a base station communication signal from the LCX 31-i, which is an input communication path for the base station, via the branching filter 23a and the amplifier input line L22.

[0041] Amplifier 210a amplifies the base station communication signal by a fixed gain AM, and variable gain control section 211a attenuates the base station communication signal amplified by amplifier 210a by a variable attenuation factor BM. Therefore, the mobile station direction gain CM of amplifier section 211a for the base station communication signal is {CM = AM x BM}, where {AM > 1} and {BM < 1} are satisfied.

[0042] The variable gain control unit 211a, which is a mobile station direction gain determination unit, determines the variable attenuation factor BM based on the base station pilot signal strength indicated by the gain control signal S2a, which is a control signal for the base station. For example, if the default value of the variable attenuation factor BM corresponding to the reference strength of the base station pilot signal is set to BM1, when the base station pilot signal strength is higher than the reference strength, the variable attenuation factor BM is set lower than the default value BM1, and when the base station pilot signal strength is lower than the reference strength, the variable attenuation factor BM is set higher than the default value BM1.

[0043] The amplified new base station communication signal output from the amplifier 21a is input to the duplexer 23b via the duplexer input line L23.

[0044] The demultiplexer 23b has a third demultiplexing function that outputs the base station communication signal input from the amplifier 21a via the demultiplexer input line L23 to the downstream side LCX31-(i+1) that serves as the base station output communication path. The demultiplexer 23b further has a fourth demultiplexing function, which will be described later.

[0045] In this way, the amplifier unit 21a having the amplifier 210a and the variable gain control unit 211a executes a mobile station direction transmission process that amplifies the base station communication signal at the mobile station direction amplification factor CM, and outputs the amplified new base station direction amplification process from LCX31-(i+1), which becomes the output communication path for the base station, via the splitter input line L23, the splitter 23b and the splitter input / output line L24.

[0046] The variable gain control unit 211a, which is a mobile station direction gain determination unit, changes the variable attenuation factor BM in accordance with the base station pilot signal strength indicated by the gain control signal S2a and executes the mobile station direction gain determination process. In this way, the variable gain control unit 211a executes the mobile station direction gain determination process, which determines the mobile station direction gain CM (=AM×BM) in accordance with the base station pilot signal strength.

[0047] The demultiplexer 23b has a fourth demultiplexing function of acquiring a mobile station communication signal from the mobile station 40 via LCX31-(i+1) and the demultiplexer input / output line L24, and outputting the mobile station communication signal to the amplifier 21b via the amplifier input line L25. In other words, the demultiplexer 23b has third and fourth demultiplexing functions.

[0048] The mobile station communication signal includes a mobile station actual signal and a mobile station pilot signal. The mobile station actual signal is the original communication signal containing the content to be transmitted to the base station 10, and the mobile station pilot signal is a signal for detecting the signal strength of the mobile station communication signal. The mobile station communication signal is set to a frequency within the frequency band for mobile station communication signals. The frequency band for mobile station communication signals is set to a band different from the frequency band for base station communication signals. Within the frequency band for mobile station communication signals, the mobile station actual signal and the mobile station pilot signal are set to different frequencies. The mobile station 40 wirelessly transmits the mobile station pilot signal at an earlier timing than the mobile station actual signal.

[0049] The mobile station pilot signal and the mobile station actual signal are set to different frequencies in the mobile station communication signal because the mobile station actual signal is a burst signal and the detection accuracy of the signal level of the mobile station actual signal, which is received non-steadily, is low, making it difficult to accurately set the base station direction gain CK (variable attenuation factor BK) of the amplifier 21b. For this reason, a gain setting process is performed to determine the base station direction gain CK of the amplifier 21b using the mobile station pilot signal, which is a monitoring target signal separate from the communication actual signal. The mobile station pilot signal is a signal transmitted as a mobile station communication signal to the base station 10 via the multiple LCXs 31 and 32 and the multiple relay devices 20.

[0050] The pilot monitoring control unit 22b, which is a mobile station pilot monitoring unit, monitors a mobile station pilot signal included in a mobile station communication signal flowing through the amplifier input line L25, detects the signal strength of the mobile station pilot signal, and executes a mobile station pilot monitoring process to generate a gain control signal S2b indicating the mobile station pilot signal strength. The mobile station pilot signal strength indicated by the gain control signal S2b, which is a mobile station control signal, is the power level (dB) of the mobile station pilot signal. In addition, a CW wave can be considered as an example of the mobile station pilot signal. The signal strength of a CW wave mobile station pilot signal is relatively easy to detect.

[0051] The amplifier 21b, which is an amplifier for the base station direction, includes an amplifier 210b and a variable gain control section 211b as main components.

[0052] The amplifier 21b, which is a base station direction amplifier, receives a mobile station communication signal from the LCX 31-(i+1) on the downlink side, which is an input communication path for the mobile station, via the branching filter 23b and amplifier input line L25.

[0053] Amplifier 210b amplifies the mobile station communication signal by a fixed gain AK, and variable gain control section 211b attenuates the mobile station communication signal amplified by amplifier 210b by a variable attenuation factor BK. Therefore, the base station direction gain CK of amplifier section 211b for the mobile station communication signal is {CK = AK x BK}, where {AK > 1} and {BK < 1} are satisfied.

[0054] The variable gain control unit 211b, which is a base station direction gain determination unit, determines the variable attenuation factor BK based on the mobile station pilot signal strength indicated by the gain control signal S2b, which is a control signal for the mobile station. For example, if the default value of the variable attenuation factor BK corresponding to the reference strength of the mobile station pilot signal is set to BK1, when the mobile station pilot signal strength is higher than the reference strength, the variable attenuation factor BK is set lower than the default value BK1, and when the mobile station pilot signal strength is lower than the reference strength, the variable attenuation factor BK is set higher than the default value BK1.

[0055] The mobile station communication signal output from the amplifier 21b is input to the duplexer 23a via the duplexer input line L26.

[0056] The demultiplexer 23a has a second demultiplexing function of outputting the mobile station communication signal input from the amplifier 21b via the demultiplexer input line L26 to the LCX 31-i on the uplink side, which serves as the mobile station output communication path. In other words, the demultiplexer 23a has first and second demultiplexing functions.

[0057] In this way, the amplifier unit 21b having the amplifier 210b and the variable gain control unit 211b executes a base station direction transmission process that amplifies the mobile station communication signal at the base station direction amplification factor CK, and outputs the amplified new mobile station direction amplification process from LCX31-i, which becomes the output communication path for the mobile station, via the branching filter input line L26, the branching filter 23a, and the branching filter input / output line L21.

[0058] The variable gain control unit 211b, which is a base station direction gain determination unit, then performs a base station direction gain determination process that varies the variable attenuation factor BK in accordance with the mobile station pilot signal strength indicated by the gain control signal S2b. In this way, the variable gain control unit 211b performs a base station direction gain determination process that determines the base station direction gain CK (=AK×BK) in accordance with the mobile station pilot signal strength.

[0059] In the train radio system 100 configured as described above, a base station direction transmission process for transmitting a mobile station communication signal from the mobile station 40 to the base station 10 is executed as follows.

[0060] Here, consider a case where the base station direction transmission process is executed via the first to Kth relay devices (1≦K≦N). For example, when K=3, the relay device 20-3 shown in FIG. 1 is the first relay device, the relay device 20-2 is the second relay device, and the relay device 20-1 is the Kth (=3) relay device.

[0061] In this case, a mobile station communication signal is wirelessly transmitted from mobile station 40 to LCX 31-4 or LCX 32-4, which serves as the mobile station input communication path of relay device 20-3, and then passes through the first to Kth relay devices in the order of relay device 20-3, relay device 20-2, and relay device 20-1. The base station direction transmission process is then completed by transmitting the mobile station communication signal to base station 10 from LCX 31-1 or LCX 32-1, which serves as the mobile station output communication path of relay device 20-1.

[0062] Amplification unit 21b, which serves as the base station direction amplification unit of the i-th relay device (i = any one of 1 to K), receives a mobile station communication signal from LCX31-(i+1) or LCX32-(i+1), which serves as the mobile station input communication path. Amplification unit 21b then performs base station direction amplification processing to amplify the mobile station communication signal by the base station direction amplification factor CK determined in the base station direction amplification factor determination processing, and outputs a new mobile station communication signal obtained by performing the base station direction amplification processing to LCX31-i or LCX32-i on the uplink direction side, which serves as the mobile station output communication path.

[0063] On the other hand, in the train radio system 100 of the first embodiment, a mobile station direction transmission process for transmitting a base station communication signal from the base station 10 to the mobile station 40 is executed as follows.

[0064] Here, consider a case where the mobile station-directed transmission process is executed via the first to Lth relay devices (1≦L≦N). For example, when L=3, the relay device 20-1 shown in FIG. 1 is the first relay device, the relay device 20-2 is the second relay device, and the relay device 20-3 is the Lth (=3) relay device.

[0065] In this case, a base station communication signal is transmitted from base station 10 to LCX 31-1 or LCX 32-1, which serves as the base station input communication path of relay device 20-1, and then passes through the first to Kth relay devices in the order of relay device 20-1, relay device 20-2, and relay device 20-3. The base station communication signal is then wirelessly transmitted from LCX 31-4 or LCX 32-4, which serves as the base station output communication path of relay device 20-3, to mobile station 40, thereby completing the mobile station direction transmission process.

[0066] Amplifier 21a, which serves as the mobile station direction amplifier of the ith (i = any one of 1 to L) relay device, receives a base station communication signal from LCX31-i or LCX32-i, which serves as an input communication path for the base station. Amplifier 21a performs mobile station direction amplification processing on the base station communication signal at the mobile station direction amplification factor CM determined in the mobile station direction amplification factor determination processing, and outputs a new base station communication signal obtained by performing the mobile station direction amplification processing to LCX31-(i+1) or LCX32-(i+1) on the downlink direction side, which serves as an output communication path for the base station.

[0067] (Effect) In the train radio system 100 according to the first embodiment, which is a radio communication system of the present disclosure, the relay devices 20-1 to 20-N function as first to Kth relay devices involved in the base station direction transmission process. The amplifier 21b, which is the base station direction amplifier of each of the first to Kth relay devices, performs the base station direction amplification process of amplifying the mobile station communication signal by a base station direction amplification factor CK (= AK × BK) to generate a new amplified mobile station communication signal.

[0068] The variable attenuation factor BK, which is a variable parameter of the base station direction gain CK, is determined by the variable gain control unit 211b, which is a base station direction gain determination unit, in accordance with the signal strength of the mobile station pilot signal contained in the mobile station communication signal to be relayed.

[0069] Therefore, even if the mobile station 40 and the base station 10 are far apart, when the base station direction transmission process is executed via the first to Kth relay devices, a highly accurate mobile station communication signal can be transmitted to the base station 10 without degrading the signal level of the mobile station communication signal.

[0070] In other words, with regard to the mobile station communication signal transmitted from the mobile station 40 to the base station 10, each relay device 20 can set the mobile station actual signal to a constant output level, thereby achieving the effect of improving the communication line quality of the train radio system 100.

[0071] Each of the multiple relay devices 20 has a relatively simple configuration including a pilot monitoring control unit 22b, which is a mobile station pilot monitoring unit, and a variable gain control unit 211b, which is a base station direction amplification factor determination unit, and can cause the variable gain control unit 211b to execute the base station direction amplification factor determination process.

[0072] Additionally, in the train radio system 100 of the first embodiment, the repeaters 20-1 to 20-N also function as first to Lth repeaters involved in the mobile station direction transmission process. The amplifier 21a, which is the mobile station direction amplifier of each of the first to Lth repeaters, performs the mobile station direction amplification process of amplifying the base station communication signal by a mobile station direction amplification factor CM (=AM×BM) to generate a new amplified base station communication signal.

[0073] The variable attenuation factor BM, which is a variable parameter of the mobile station direction gain CM, is determined by the variable gain control unit 211a, which is a mobile station direction gain determination unit, in accordance with the signal strength of the base station pilot signal included in the base station communication signal to be relayed.

[0074] Therefore, even if the base station 10 and the mobile station 40 are far apart, when the mobile station direction transmission process is executed via the first to Lth relay devices, a highly accurate base station communication signal can be transmitted to the mobile station 40 without degrading the output level.

[0075] Furthermore, the variable gain control unit 211a, which is a mobile station direction gain determining unit, can accurately determine the mobile station direction gain CM (AM × BM) based on the signal strength of a dedicated base station pilot signal that is provided separately from the base station actual signal.

[0076] The train radio system 100 of embodiment 1 can transmit mobile station communication signals and mobile station communication signals without reducing the level during train operation using multiple leaky coaxial cables, N LCX31 and N LCX32.

[0077] The amplifier 21b, which serves as the mobile station direction amplifier of the repeater device 20-i used in the train radio system 100 of embodiment 1, relays the mobile station communication signal when the base station direction transmission process performed in the train radio system 100 is executed, and performs the base station direction amplification process in which the mobile station communication signal is amplified by the base station direction amplification factor CK to generate a new amplified mobile station communication signal.

[0078] The variable gain control unit 211b, which is a base station direction amplification factor determination unit, executes a base station direction amplification factor determination process to determine the base station direction amplification factor CK (variable attenuation factor BK) according to the signal strength of the mobile station pilot signal contained in the mobile station communication signal to be relayed.

[0079] Therefore, the repeater device 20-i used in the train radio system 100 of the first embodiment can relay the mobile station communication signal with high accuracy without degrading the output level when executing the base station direction transmission process.

[0080] Similarly, the amplifier 21a, which serves as the base station direction amplifier of the relay device 20-i, relays the base station communication signal when the mobile station direction transmission process is executed, and performs the mobile station direction amplification process in which the base station communication signal is amplified by the mobile station direction amplification factor CM to generate a new amplified base station communication signal.

[0081] The pilot monitoring control unit 22a, which is a mobile station direction gain determination unit, executes a mobile station direction gain determination process to determine the mobile station direction gain CM (variable attenuation factor BM) according to the signal strength of the base station pilot signal included in the base station communication signal to be relayed.

[0082] Therefore, the repeater device 20-i used in the train radio system 100 of the first embodiment can relay a base station communication signal with high accuracy without degrading the output level when performing a mobile station direction transmission process.

[0083] (Other) In the train radio system 100 of embodiment 1, the base station communication signal includes a base station pilot signal, but a modified example is conceivable in which the base station communication signal includes only the base station actual signal without including the base station pilot signal.

[0084] In the modified train radio system 100, the pilot monitoring control unit 22a performs a mobile station pilot monitoring process in which the actual base station signal itself is monitored instead of the base station pilot signal, the signal strength of the actual base station signal is detected, and a gain control signal S2a indicating the actual base station signal strength is obtained.

[0085] On the other hand, the variable gain control section 211a, which is a base station direction amplification factor determination section, executes a base station direction amplification factor determination process for determining a variable attenuation factor BM based on the actual base station signal strength indicated by the gain control signal S2a.

[0086] Since the actual base station signal is not a burst signal but a steady signal, the variable gain control section 211a can determine the variable attenuation factor BM with high accuracy based on the actual base station signal strength indicated by the gain control signal S2a.

[0087] 3 is an explanatory diagram schematically illustrating the internal configuration of a relay device 50-i (where i = 1 to N) used in a train radio system according to a second embodiment of the present disclosure, which is a radio communication system. However, the LCX 31-(N+1) and LCX 32-(N+1) on the downstream side of the relay device 50-N may be omitted.

[0088] The overall configuration of the train radio system of the second embodiment is the same as that shown in FIG. 1, except that the repeaters 20-1 to 20-N are replaced with repeaters 50-1 to 50-N.

[0089] Therefore, the base station 10 is connected to LCX31-1 and LCX32-1, and the relay device 50-i (where i = 1 to (N-1)) is provided between LCX31-i and LCX32-i and LCX31-(i+1) and LCX32-(i+1). The relay device 50-N is connected to LCX31-N and LCX32-N. Hereinafter, when the relay devices 50-1 to 50-N are collectively referred to, they will be simply referred to as "relay device 50."

[0090] The multiple communication paths, N LCXs 31 and N LCXs 32, function as input communication paths for mobile stations for mobile station communication signals or output communication paths for mobile stations for mobile station communication signals for each of relay devices 50-1 to 50-N, and also function as input communication paths for base stations for base station communication signals or output communication paths for base stations for base station communication signals.

[0091] Since the base station communication signal from the base station 10 to the mobile station 40 is constantly transmitted, the amplifier 51a in the (wireless) repeater 50 must constantly perform mobile station direction amplification processing. On the other hand, the mobile real signal included in the mobile station communication signal from the mobile station 40 to the base station 10 is a burst signal, and a no-input state occurs in which no mobile station communication signal is input to the amplifier 51b in the repeater 50. The repeater 50-i of the second embodiment takes this no-input state into consideration.

[0092] The following description will focus on the features of the relay device 50 of the second embodiment, omitting the description of parts common to the relay device 20 of the first embodiment shown in FIGS. 1 and 2 as appropriate.

[0093] A base station communication signal transmitted from base station 10 is received by relay device 50-i via LCX31-i or LCX32-i (not shown). On the other hand, a mobile station communication signal transmitted from mobile station 40 is received by LCX31-(i+1) or LCX32-(i+1) (not shown). For convenience of explanation, the following description will be made assuming that the base station communication signal is output to branching filter input / output line L51 via LCX31-i, and the mobile station communication signal is output to branching filter input / output line L54 via LCX31-(i+1).

[0094] As shown in FIG. 3, the repeater device 50-i includes, as its main components, branching filters 53a and 53b, amplifiers 51a and 51b, a signal detector 55, and a repeater device monitor and control unit 56.

[0095] The demultiplexer 53a has a first demultiplexing function of receiving a base station communication signal from the base station 10 via the demultiplexer input / output line L51 and outputting the base station communication signal to the amplifier 51a via the amplifier input line L52. The demultiplexer 53a further has a second demultiplexing function, which will be described later.

[0096] The amplifier 51a, which is a mobile station direction amplifier, receives a base station communication signal from the LCX31-i, which is an input communication path for the base station, via a branching filter 53a and an amplifier input line L52. The amplifier 51a, which is a mobile station direction amplifier, includes an amplifier 510a, a variable gain control unit 511a, and a pilot monitoring control unit 512a as its main components.

[0097] The pilot monitoring control unit 512a, which is a base station pilot monitoring unit, monitors the base station pilot signal included in the base station communication signal flowing through the amplifier input line L52, detects the signal strength of the base station pilot signal, and executes base station pilot monitoring processing to generate a gain control signal S5a indicating the base station pilot signal strength. The mobile station pilot signal strength indicated by the gain control signal S5a, which is a control signal for the base station, is the power level (dB) of the base station pilot signal.

[0098] Amplifier 510a amplifies the base station communication signal by a fixed gain AM, and variable gain control section 511a attenuates the base station communication signal amplified by amplifier 510a by a variable attenuation factor BM. Therefore, the mobile station direction gain CM for the base station communication signal obtained by the combination of amplifier 510a and variable gain control section 511a, which are the main components of amplifier section 51a, is {CM = AM × BM}.

[0099] The variable gain control section 511a, which is a mobile station direction amplification factor determining section, determines the variable attenuation factor BM based on the base station pilot signal strength indicated by the gain control signal S5a, which is a control signal for the base station.

[0100] The base station communication signal output from the amplifier 51a is input to the duplexer 53b via the duplexer input line L53.

[0101] The duplexer 53b has a third demultiplexing function of outputting the base station communication signal input from the amplifier 51a via the duplexer input line L53 to the downstream side LCX31-(i+1) (not shown), which serves as the output communication path for the base station, via the duplexer input / output line L54. The duplexer 53b further has a fourth demultiplexing function, which will be described later.

[0102] In this way, the amplifier unit 51a having the amplifier 510a, the variable gain control unit 511a, and the pilot monitoring control unit 512a executes a mobile station direction transmission process for amplifying the base station communication signal at the mobile station direction amplification factor CM, and outputs the amplified new base station communication signal from LCX31-(i+1), not shown, which serves as an output communication path for the base station, via the branching filter input line L53, the branching filter 53b, and the branching filter input / output line L54.

[0103] The variable gain control unit 511a, which is a mobile station direction gain determination unit, executes a mobile station direction gain determination process to determine the mobile station direction gain CM by changing the variable attenuation factor BM in accordance with the signal strength of the base station pilot signal, i.e., the base station pilot signal strength indicated by the gain control signal S5a.

[0104] The demultiplexer 53b has a third demultiplexing function that outputs the base station communication signal input from the amplifier 51a via the demultiplexer input line L53 to the downstream side LCX31-(i+1) that serves as the base station output communication path. The demultiplexer 53b further has a fourth demultiplexing function, which will be described later.

[0105] In this way, the amplifier 51a executes a mobile station direction transmission process that amplifies the base station communication signal at the mobile station direction amplification factor CM, and outputs the amplified new base station communication signal from LCX31-(i+1), which serves as the output communication path for the base station, via the splitter input line L53, splitter 53b and splitter input / output line L54.

[0106] Then, the variable gain control unit 511a, which is a mobile station direction amplification factor determination unit, executes a mobile station direction amplification factor determination process to determine the mobile station direction amplification factor CM by changing the variable attenuation factor BM in accordance with the base station pilot signal strength indicated by the gain control signal S5a.

[0107] The demultiplexer 53b has a fourth demultiplexing function of receiving a mobile station communication signal from the mobile station 40 via the demultiplexer input / output line L54 and outputting the mobile station communication signal to the amplifier 51b via the amplifier input line L55. In this way, the demultiplexer 53b has the third and fourth demultiplexing functions.

[0108] The amplifier 51b, which is an amplifier for the base station direction, includes an amplifier 510b, a variable gain control section 511b, and a pilot monitoring control section 512b as main components.

[0109] Pilot monitoring control section 512b, which is a mobile station pilot monitoring section, monitors a mobile station pilot signal included in a mobile station communication signal flowing through amplifier input line L55, detects the signal strength of the mobile station pilot signal, and executes mobile station pilot monitoring processing to generate gain control signal S5b. Gain control signal S5b, which is a control signal for the mobile station, indicates the mobile station pilot signal strength. The mobile station pilot signal strength indicated by gain control signal S5b, which is a control signal for the mobile station, is the power level (dB) of the mobile station pilot signal.

[0110] The amplifier 51b, which is a base station direction amplifier, receives a mobile station communication signal from LCX31-(i+1), which is an input communication path for the mobile station, via the branching filter input / output line L54, the branching filter 53b and the amplifier input line L55.

[0111] Amplifier 510b amplifies the mobile station communication signal by a fixed amplification factor AK, and variable gain control unit 511b attenuates the mobile station communication signal amplified by amplifier 510b by a variable attenuation factor BK. Therefore, the base station direction amplification factor CK for the mobile station communication signal, achieved by the combination of amplifier 510b and variable gain control unit 511b, which are the main components of amplifier unit 51b, is {CK = AK x BK}.

[0112] The variable gain control section 511b, which is a base station direction amplification factor determining section, determines the variable attenuation factor BK based on the mobile station pilot signal strength indicated by the gain control signal S5b.

[0113] The mobile station communication signal output from the amplifier 51b is input to the duplexer 53a via the duplexer input line L56.

[0114] The demultiplexer 53a has a second demultiplexing function of outputting the mobile station communication signal input from the amplifier 51b via the demultiplexer input line L56 to the LCX31-i on the uplink side, which serves as the output communication path for the mobile station, via the demultiplexer input / output line L51. In other words, the demultiplexer 53a has first and second demultiplexing functions.

[0115] In this way, the amplifier 51b having the amplifier 510b, the variable gain control unit 511b, and the pilot monitoring control unit 512b executes a base station direction transmission process for amplifying the mobile station communication signal at the base station direction amplification factor CK, and outputs the amplified new mobile station communication signal from LCX31-i, which serves as an output communication path for the mobile station, via the branching filter input line L56, the branching filter 53a, and the branching filter input / output line L51.

[0116] Then, the variable gain control unit 511b, which is a base station direction amplification factor determination unit, executes a base station direction amplification factor determination process to determine the base station direction amplification factor CK (= AK × BK) by changing the variable attenuation factor BK in accordance with the mobile station pilot signal strength indicated by the gain control signal S5b.

[0117] The signal detection section 55 checks whether or not a mobile station pilot signal flowing through the amplifier input line L55 is being received, and outputs a detection signal S55 indicating whether or not a mobile station pilot signal is being received to the repeater monitor control section 56.

[0118] The repeater device monitoring control unit 56 outputs an amplifier control signal S6 to the amplifier 51b based on the detection signal S55. For example, when the detection signal S55 indicates that a mobile station pilot signal has been received, the amplifier control signal S6 goes high, and when the detection signal S55 indicates that a mobile station pilot signal has not been received, the amplifier control signal S6 goes low.

[0119] The repeater monitoring control section 56 instantly switches the amplifier control signal S6 between "H" and "L" based on the instruction of the detection signal S55.

[0120] The amplifier 51b is in an "operating state" when the amplifier control signal S6 is "H", and is in a "standby state" when the amplifier control signal S6 is "L".

[0121] When amplifier 51b is in operation, amplifier 510b amplifies the mobile station communication signal with an amplification factor AK, and variable gain control unit 511b attenuates the output signal of amplifier 510b with a variable attenuation factor BK determined based on the mobile station pilot signal strength indicated by gain control signal S5b. Furthermore, pilot monitoring control unit 512b executes mobile station pilot monitoring processing.

[0122] When amplifier 51b is in the standby state, amplifier 510b amplifies the mobile station communication signal and variable gain control unit 511b attenuates the mobile station communication signal. Furthermore, when amplifier 51b is in the standby state, pilot monitoring control unit 512b disables the mobile station pilot monitoring process.

[0123] Thus, the operational state of the amplifier 51b means a state in which the amplifier 51b is executing the base station direction amplification process and the mobile station pilot monitoring process. On the other hand, the standby state of the amplifier 51b means a state in which the amplifier 51b is halting the base station direction amplification process and the mobile station pilot monitoring process. Therefore, the relay device 50-i can minimize the standby current in the standby state, thereby reducing power consumption. However, the amount of standby current is set so that the amplifier 51b can instantly return to the operational state from the standby state.

[0124] Even when the amplifier 51b is in a standby state, the function of monitoring whether or not a mobile station pilot signal is input from the mobile station 40 by the signal detector 55 located outside the amplifier 51b is always valid.

[0125] As described above, the relay device 50-i of the second embodiment has an activation control unit including the signal detection unit 55 and the relay device monitoring control unit 56.

[0126] The above-mentioned validation control unit performs a first validation control process that validates the base station direction amplification process by the "amplifier 510b+variable gain control unit 511b," which is the main part of the amplification unit 51b, during the reception confirmation period of the mobile station pilot signal, and invalidates the base station direction amplification process during other periods.

[0127] Furthermore, the validation control unit performs a second validation control process that validates the mobile station pilot monitoring process of the pilot monitoring control unit 512b during the reception confirmation period of the mobile station pilot signal, and invalidates the mobile station pilot monitoring process during other periods.

[0128] In this way, the validation control unit configured by the signal detection unit 55 and the repeater device monitoring control unit 56 executes the first and second validation control processes described above.

[0129] (Effects) The train radio system and the repeater 50 according to the second embodiment, which have N repeaters 50 as shown in FIG. 3, have the following unique effects in addition to the effects of the train radio system 100 according to the first embodiment.

[0130] In the train radio system of the second embodiment, each of the N repeaters 50 has an activation control unit including a signal detection unit 55 and a repeater monitoring control unit 56. The above-mentioned first activation control process of this activation control unit selectively activates the base station direction amplification process of the main part of the amplifier unit 51b, thereby reducing power consumption.

[0131] In this way, the repeater device 50 used in the train radio system of embodiment 2 can reduce power consumption by selectively enabling the base station direction amplification processing by the amplifier unit 51b, which is a base station direction amplifier unit, using the activation control unit that executes the first activation control processing.

[0132] That is, the main parts of the amplifier unit 51b consume less power when operating in standby mode than when operating in operation mode, and therefore it is possible to suppress the output of unnecessary noise from the repeater device 50. In this way, the train radio system of the second embodiment having a plurality of repeater devices 50 can reduce the power consumption of the devices in addition to reducing unnecessary noise when in standby mode, thereby achieving the effects of improving the communication quality of the communication signals transmitted by the train radio system and reducing power consumption.

[0133] In addition, since the mobile station pilot signal is wirelessly transmitted from the mobile station 40 at an earlier timing than the mobile station actual signal, selectively enabling the base station direction amplification process does not impede the base station direction amplification process for the mobile station communication signal including the mobile station actual signal.

[0134] Each of the N relay devices 50 has an activation control unit that executes a second activation control process, and selectively activates the mobile station pilot monitoring process by the pilot monitoring control unit 512b, which serves as a mobile station pilot monitoring unit, thereby further reducing power consumption.

[0135] 3, the pilot monitoring control unit 512b is provided inside the amplifier unit 51b. As a modification, the pilot monitoring control unit 512b may be provided outside the amplifier unit 51b, similar to the relay device 20-i of the first embodiment.

[0136] In this case, the mobile station pilot monitoring process by the pilot monitoring control unit 512b is always enabled. Therefore, the basic configuration shown in Fig. 3 is more effective in reducing power consumption than the modified example because the mobile station pilot monitoring process by the pilot monitoring control unit 512b can also be disabled during standby.

[0137] Although the present disclosure has been described in detail, the above description is illustrative in all respects and does not limit the present disclosure to the above. It is understood that countless variations not illustrated can be envisioned without departing from the scope of the present disclosure.

[0138] 10 base station, 20, 20-1 to 20-N, 50, 50-1 to 50-N relay device, 21a, 21b, 51a, 51b amplifier, 211a, 211b, 511a, 511b variable gain control unit, 22a, 22b, 512a, 512b pilot monitoring control unit, 23a, 23b, 53a, 53b splitter, 31, 31-1 to 31-N, 32, 32-1 to 32-N LCX (leaky coaxial cable), 40, 40-1, 40-2 mobile station, 41 rail, 55 signal detection unit, 56 relay device monitoring control unit, 100 train radio system.

Claims

1. Base station and A mobile station that moves along the route, A plurality of communication paths provided along the aforementioned mobile path, which carry communication signals transmitted and received between the base station and the mobile station, The system includes a plurality of relay devices that relay between the plurality of communication paths, The mobile station communication signal transmitted wirelessly from the mobile station is transmitted toward the base station by a base station direction transmission process, and the communication signal includes the mobile station communication signal. The plurality of communication paths function as either a mobile station input communication path for the mobile station communication signal or a mobile station output communication path for the mobile station communication signal for each of the plurality of relay devices. The aforementioned mobile station communication signals include a mobile station actual signal and a mobile station pilot signal. Each of the plurality of relay devices, upon receiving the mobile station communication signal from the mobile station input communication path, includes a base station direction amplification unit that performs base station direction amplification processing to amplify the mobile station communication signal with a base station direction amplification factor, and outputs the amplified new mobile station communication signal from the mobile station output communication path. The base station direction amplification unit includes a base station direction amplification unit that performs a base station direction amplification unit determination process to determine the base station direction amplification rate according to the signal strength of the mobile station pilot signal, The base station direction transmission process is performed via the first to K (≧1) relay devices, and involves the mobile station communication signal being wirelessly transmitted from the mobile station to the input communication path for the mobile station of the first relay device, and then transmitted to the base station from the output communication path for the mobile station of the K relay device via the first, second, ..., K relay devices in that order. The base station direction amplification unit of the i-th relay device (i = any of 1 to K) receives the mobile station communication signal from the mobile station input communication path, performs the base station direction amplification process with the base station direction amplification rate determined in the base station direction amplification rate determination process, and outputs the new mobile station communication signal obtained by performing the base station direction amplification process to the mobile station output communication path. Wireless communication system.

2. A wireless communication system according to claim 1, Each of the aforementioned multiple relay devices, The system further includes a mobile station pilot monitoring unit that performs a mobile station pilot monitoring process that detects the signal strength of the mobile station pilot signal and generates a mobile station control signal indicating the mobile station pilot signal strength, The base station direction amplification factor determination unit performs the base station direction amplification factor determination process based on the mobile station pilot signal strength indicated by the mobile station control signal. Wireless communication system.

3. A wireless communication system according to claim 2, Each of the aforementioned multiple relay devices, The system further includes an activation control unit that checks whether or not the mobile station pilot signal has been received, activates the base station direction amplification processing by the base station direction amplification unit during the period in which the mobile station pilot signal has been confirmed to be received, and disables the base station direction amplification processing during other periods. The mobile station transmits the mobile station pilot signal wirelessly at an earlier timing than the mobile station actual signal. Wireless communication system.

4. A wireless communication system according to claim 3, The activation control unit activates the mobile station pilot monitoring process by the mobile station pilot monitoring unit during the period for confirming receipt of the mobile station pilot signal, and disables the mobile station pilot monitoring process during other periods. Wireless communication system.

5. A wireless communication system according to claim 1, The aforementioned mobile station is installed inside the train. The aforementioned travel path includes the rails used for the operation of the aforementioned train. The aforementioned multiple communication paths include multiple leaky coaxial cables. Wireless communication system.

6. A wireless communication system according to any one of claims 1 to 5, The base station communication signal from the base station is transmitted toward the mobile station by a mobile station direction transmission process, and the communication signal includes the base station communication signal. The plurality of communication paths function as either an input communication path for the base station communication signal or an output communication path for the base station communication signal for each of the plurality of relay devices. Each of the aforementioned relay devices, upon receiving the base station communication signal from the base station input communication path, includes a mobile station direction amplification unit that performs a mobile station direction amplification process to amplify the base station communication signal with a mobile station direction amplification factor, and outputs the amplified new base station communication signal from the base station output communication path. The mobile station direction amplification unit includes a mobile station direction amplification unit that performs a mobile station direction amplification rate determination process to determine the mobile station direction amplification rate according to the signal strength of the base station communication signal. The aforementioned mobile station direction transmission process, when performed via relay devices 1 to L (≧1), involves the base station transmitting the base station communication signal wirelessly from the base station output communication path of the L relay device, via the relay devices 1 to L in the order of 1, 2, ... L. The mobile station direction amplification unit of the i-th relay device (i = any of 1 to L) receives the base station communication signal from the base station input communication path, executes the mobile station direction amplification process with the mobile station direction amplification rate determined in the mobile station direction amplification rate determination process, and outputs the new base station communication signal obtained by executing the mobile station direction amplification process to the base station output communication path. Wireless communication system.

7. A wireless communication system according to claim 6, The base station communication signal includes the base station actual signal and the base station pilot signal. The mobile station direction amplification factor determination unit performs the mobile station direction amplification factor determination process according to the signal strength of the base station pilot signal included in the base station communication signal. Wireless communication system.

8. A relay device used in wireless communication systems, The aforementioned wireless communication system is near Base station and It comprises a mobile station that moves along a travel route, The wireless communication system performs a base station direction transmission process to transmit a mobile station communication signal wirelessly transmitted from the mobile station to the base station, and the mobile station communication signal includes a mobile station actual signal and a mobile station pilot signal. The relay device is, When the base station direction transmission process is executed, the mobile station communication signal is relayed. The unit includes a base station direction amplification unit that performs base station direction amplification processing to amplify the mobile station communication signal with a base station direction amplification factor, thereby generating a new amplified mobile station communication signal. The base station direction amplification unit includes a base station direction amplification unit that performs a base station direction amplification unit determination process to determine the base station direction amplification rate according to the signal strength of the mobile station pilot signal included in the mobile station communication signal. Relay device.

9. A relay device according to claim 8, The system further includes an activation control unit that checks whether or not the mobile station pilot signal has been received, activates the base station direction amplification processing by the base station direction amplification unit during the period in which the mobile station pilot signal has been confirmed to be received, and disables the base station direction amplification processing during other periods. Relay device.