Wireless communication system and relay device

Abstract

This wireless communication system comprises a base station (10) and a plurality of relay devices (20) that are cascade-connected to the base station (10). The base station (10) comprises: a receiver (11); a local oscillator (12) that outputs a local oscillation signal; and a shared unit (13) that transmits the local oscillation signal from the local oscillator (12) to a transmission path, and transmits a reception signal from the transmission path to the receiver (11). Each relay device (20) comprises: a reception signal generation path for frequency-converting a reception wave signal based on a reception wave inputted using the local oscillation signal from the base station (10), into a reception signal with a frequency lower than the frequency of the reception wave signal, and for transmitting the reception signal to the transmission path; a local oscillation signal transmission path for transmitting the local oscillation signal to the transmission path connected to a next-stage relay device (20); and a reception signal transmission path for transmitting a reception signal from the next-stage relay device (20) to the transmission path.

Description

Technical Field

[0001] The present disclosure relates to a wireless communication system that communicates with a mobile station and a relay device in the wireless communication system.

Background Art

[0002] A train communication method for communicating between a base station and a train is disclosed in Patent Document 1. In the train communication method disclosed in Patent Document 1, in a relay amplifier disposed in the middle of a leaky coaxial transmission line connecting a base station and a receiving station, an intermediate frequency signal transmitted from the base station is amplified by an amplifier and then converted to a high frequency by a frequency converter and transmitted to the leaky coaxial transmission line and sent to the train. A high-frequency signal transmitted from the train is amplified by an amplifier after being down-converted to an intermediate frequency by a frequency converter and transmitted to the leaky coaxial transmission line and sent to the receiving station.

Prior Art Documents

Patent Documents

[0003]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0004] Patent Document 1 does not describe a local oscillation signal used for a frequency converter that down-converts a high-frequency signal to an intermediate frequency, and a local oscillation signal used for a frequency converter that up-converts an intermediate frequency signal to a high frequency. In addition, only one relay amplifier is shown, and no example of cascade connection of a plurality of relay amplifiers is shown at all. When performing long-distance transmission by cascade connection of a plurality of relay amplifiers, if it is attempted to perform the transmission at a low frequency with small transmission loss, in order to obtain high frequency stability for the frequency-converted signal, there is a problem of how to generate the local oscillation signal used for the frequency converter in each of the plurality of relay amplifiers.

[0005] The present disclosure has been made in view of the above points, and an object thereof is to obtain a wireless communication system in which a high frequency stability can be obtained for a frequency-converted signal in a wireless communication system including a base station and a plurality of relay devices connected in cascade to the base station.

Means for Solving the Problems

[0006] The wireless communication system according to the present disclosure includes a base station and 、 is connected in cascade to the base station , each receiving the transmission wave from the mobile station as a received wave a plurality of relay devices. The base station includes a receiver, a local oscillator that outputs a local oscillation signal, and a duplexer that transmits the local oscillation signal from the local oscillator to a transmission line and transmits the received signal from the transmission line to the receiver. Among the plurality of relay devices, the relay device adjacent to the base station receives the local oscillation signal from the base station and uses the local oscillation signal 、 a reception signal generation path that frequency-converts a reception wave signal by an input reception wave to a reception signal having a frequency lower than the frequency of the reception wave signal and transmits the reception signal to a transmission line connected to the base station, a local oscillation signal transmission path that transmits the local oscillation signal from the base station to a transmission line connected to the next-stage relay device, and a reception signal transmission path that transmits a reception signal from the next-stage relay device to a transmission line connected to the base station. Among the plurality of relay devices, relay devices other than the relay device adjacent to the base station receive the local oscillation signal from the local oscillation signal transmission path in the previous-stage relay device, and use the local oscillation signal to frequency-convert a reception wave signal by an input reception wave to a reception signal having a frequency lower than the frequency of the reception wave signal and transmit the reception signal to a transmission line connected to the previous-stage relay device, a local oscillation signal transmission path that transmits the local oscillation signal from the local oscillation signal transmission path in the previous-stage relay device to a transmission line connected to the next-stage relay device, and a reception signal transmission path that transmits a reception signal from the next-stage relay device to a transmission line connected to the previous-stage relay device.

Advantages of the Invention

[0007] According to the present disclosure, a local oscillator that outputs a local oscillation signal is provided in a base station, and the local oscillation signal from the local oscillator in the base station is used for frequency conversion in a plurality of cascaded relay devices. Therefore, high frequency stability can be obtained for the frequency-converted signal.

Brief Description of the Drawings

[0008]

Figure 1

Figure 2

Figure 3

Figure 4

Figure 5

Figure 6

Figure 7

Embodiments for Carrying Out the Invention

[0009] Embodiment 1. The wireless communication system according to Embodiment 1 will be described with reference to FIGS. 1 to 4. The wireless communication system according to Embodiment 1 includes a base station 10 and a plurality of relay devices 20 1 , 20 k cascaded to the base station 10. k is an integer of 2 or more. The relay device 20 1 represents the first-stage relay device adjacent to the base station, and the relay device 20 k represents the relay devices from the second stage onwards.

[0010] The base station 10 includes a receiver 11, a local oscillator 12, and a duplexer 13. The local oscillator 12 outputs a local oscillation signal LO with a frequency f LO . The frequency f LO is in the range of several MHz to 100 MHz in this example. Note that due to the increase in loss for signals transmitted through the transmission line connecting the base station 10 and the first-stage relay device 20 1 , and the change in frequency where loss can be suppressed or loss increases for signals transmitted through the transmission line connecting adjacent relay devices 20, the frequency f LO is selected as an appropriate frequency by the transmission line.

[0011] The duplexer 13 transmits the local oscillation signal LO from the local oscillator 12 to the transmission line connected to the first-stage relay device 20 1 , and transmits the received signal RX with an intermediate frequency f 1 from the transmission line connected to the first-stage relay device 20 IF to the receiver 11. IF The duplexer 13 has an input terminal, an output terminal, and an input / output terminal. The input terminal is connected to the output terminal of the local oscillator 12, the output terminal is connected to the input terminal of the receiver 11, and the input / output terminal is 1 connected to the transmission line connected to the first-stage relay device 20 connected .

[0012] In the duplexer 13, as shown in FIG. 2, the local oscillation signal LO with a frequency f LO input to the input terminal is transmitted to the input / output terminal, and the received signal RX with an intermediate frequency f 1 received by the first-stage relay device 20 1 and the received signal RX with an intermediate frequency f IF from the received wave RX IF1 input to the input / output terminal via the first-stage relay device 20 1 and the received signal RX with an intermediate frequency f 2 from the next-stage relay device 20 IF input to the input / output terminal are transmitted to the output terminal. IF2 The duplexer 13 is a frequency duplexer that appropriately distributes frequencies, that is, the frequency fLO and has the function of a band-pass filter, a low-pass filter, or a high-pass filter for appropriately distributing the intermediate frequency f IF1

[0013] The transmission path connecting the base station 10 and the first-stage relay device 20 1 is a coaxial cable or an antenna. 1 When the transmission path is a coaxial cable, the input and output terminals of the duplexer 13 are connected to the coaxial cable by connectors. When the transmission path is an antenna, the input and output terminals of the duplexer 13 are connected to the antenna that transmits the local oscillation signal LO and the antenna that receives the received signal RX 1 from the first-stage relay device 20 IF1 RX IFk IFk Note that the input and output terminals of the duplexer 13 may be divided into an input terminal and an output terminal and connected to different transmission paths.

[0014] The plurality of relay devices 20 1 20 k basically have the same configuration, and as shown in FIG. 1, include a first duplexer 21, a second duplexer 22, a frequency converter 23, a distributor 24, and a first amplifier 25 to a third amplifier 27. The first amplifier 25 to the third amplifier 27 are provided to compensate for the signal strength of the signal to be transmitted, that is, to increase the signal strength. The plurality of relay devices 20 1 20 k are installed in the direction of gradually moving away from the base station 10.

[0015] The plurality of relay devices 20 1 20 k each have a reception area for receiving the transmission wave from the mobile station, which is the reception wave for the relay device, and receive the transmission wave from the mobile station existing in the corresponding reception area as the reception wave. The mobile station is, in this example, for example, a transmitter mounted on a railway vehicle or an automobile.

[0016] The plurality of relay devices 20 1 20k Each of the first and second sub-bands includes a reception signal generating path, a local oscillation signal transmitting path, and a reception signal transmitting path. A plurality of relay devices 20 1 , 20 k Among these, the first stage relay device 20 connected to the base station 10 via a transmission line 1 The received signal generation path in LO Receives a local oscillation signal LO and receives a received wave RX input using the local oscillation signal 1 The frequency of the received wave signal converted into an electrical signal is f RX The frequency of the received wave signal is f RX Lower intermediate frequency f IF Received signal RX IF1 The signal is then frequency-converted and transmitted to a transmission line connected to the base station 10. frequency f RX In this example, the frequency is in the UHF band, such as 300 MHz to 500 MHz, and the intermediate frequency f IF is the frequency f RX More frequency f LO This is a lower value.

[0017] First stage repeater 20 1 As shown in FIG. 1, the received signal generation path in the has a first duplexer 21, a second duplexer 22, a frequency converter 23, and a first amplifier 25. The second duplexer 22 receives and transmits a received wave RX 1 by frequency f RX The frequency converter 23 converts the received wave signal into a frequency f LO Using one of the local oscillator signals LO, frequency f RX The lower frequency, intermediate frequency f IF Received signal RX IF1 Then, the intermediate frequency f IF Received signal RX IF1 is amplified by the first amplifier 25 and then output to the transmission line via the first duplexer 21. frequency f RX and intermediate frequency f IF The relationship with f IF =f RX -f LO become.

[0018] The first-stage relay device 20 1 The local oscillation signal transmission path in transmits the local oscillation signal LO of frequency f from the base station 10 LO to the transmission path connected to the next-stage relay device 20 2 . The local oscillation signal transmission path in the first-stage relay device 20 1 has a first duplexer 21, a second duplexer 22, a distributor 24, and a second amplifier 26. As shown in FIG. 1, the first duplexer 21 receives and transmits the local oscillation signal LO of frequency f LO , distributes the local oscillation signal LO, outputs one of the distributed local oscillation signals LO of frequency f LO to the frequency converter 23, amplifies the other distributed local oscillation signal LO of frequency f LO by the second amplifier 26, and then outputs it to the transmission path connected to the next-stage relay device 20 2 via the second duplexer 22

[0019] The received signal transmission path in the first-stage relay device 20 1 transmits the received signal RX of intermediate frequency f 2 from the next-stage relay device 20 IF2 to the transmission path connected to the base station 10 IF2 . The received signal transmission path in the first-stage relay device 20 1 has a first duplexer 21, a second duplexer 22, and a third amplifier 27. As shown in FIG. 1, the second duplexer 22 receives and transmits the received signal RX of intermediate frequency f 2 from the next-stage relay device 20 IF , amplifies the received signal RX by the third amplifier 27, and then outputs it to the transmission path via the first duplexer 21 IF2 .

[0020] The first duplexer 21 is a frequency duplexer. It receives the local oscillation signal LO of frequency f LO output from the local oscillator 12 of the base station 10, outputs the local oscillation signal LO to the distributor 24, and outputs the received signal RX of intermediate frequency f IF in which the received wave signal by the received wave is frequency-converted and amplified by the first amplifier 25 from the frequency converter 23IF1 is output to the base station 10, and the intermediate relay device 20 at the next stage that is transmitted from the second multiplexer 22 and amplified by the third amplifier 27 2 from the intermediate frequency f IF of the received signal RX IF2 is output to the base station 10.

[0021] As shown in FIG. 3, the first multiplexer 21 has an input / output terminal, a first input terminal, a second input terminal, and an output terminal. The input / output terminal is connected to a transmission line connected to the base station 10. The first input terminal is connected to the output terminal of the first amplifier 25 that constitutes the received signal generation path. The second input terminal is connected to the output terminal of the third amplifier 27 in the received signal transmission path. The output terminal is connected to the input terminal of the distributor 24 that constitutes the local oscillation signal transmission path.

[0022] In the first multiplexer 21, as shown in FIG. 3, the local oscillation signal LO of the frequency f LO input to the input / output terminal is transmitted to the output terminal, and the received wave signal by the received wave RX 1 input to the first input terminal is frequency-converted by the frequency converter 23 to the received signal RX of the intermediate frequency f IF and transmitted to the input / output terminal, and the received signal RX of the intermediate frequency f IF1 from the intermediate relay device 20 at the next stage input to the second input terminal 2 is transmitted to the input / output terminal. IF of the received signal RX IF2 is transmitted to the input / output terminal. The first multiplexer 21 has a function of appropriately distributing frequencies, that is, a band-pass filter, a low-pass filter, or a high-pass filter for appropriately distributing the frequencies f LO , the intermediate frequency f IF .

[0023] When the transmission line connected to the base station 10 is a coaxial cable, the input / output terminals of the first multiplexer 21 are connected to the coaxial cable by a connector. When the transmission line is an antenna, the input / output terminals of the first multiplexer 21 are an antenna that receives the local oscillation signal LO and the received signal RX IF1、 RX IFkIt is connected to the antenna that transmits. In addition, the input / output terminals of the first multiplexer 21 may be divided into input terminals and output terminals corresponding to the input / output terminals of the multiplexer 13 in the base station 10 and connected to different transmission paths.

[0024] The second multiplexer 22 is a frequency multiplexer that outputs the received wave signal due to the received wave to the frequency converter 23, and the local oscillation signal LO is distributed by the distributor 24 at the frequency f LO of the other local oscillation signal LO to the next-stage relay device 20 2 and outputs the intermediate frequency f 2 from the next-stage relay device 20 IF of the received signal RX IF2 to the first multiplexer 21 via the third amplifier 27.

[0025] As shown in FIG. 4, the second multiplexer 22 has input / output terminals, input terminals, a first output terminal, and a second output terminal. The input / output terminals are connected to the transmission path connected to the next-stage relay device 20 2 , the input terminals are connected to the output terminals of the second amplifier 26 that constitutes the local oscillation signal transmission path, the first output terminal is connected to the input terminals of the frequency converter 23 that constitutes the received signal generation path, and the second output terminal is connected to the input terminals of the third amplifier 27 in the received signal transmission path.

[0026] In the second multiplexer 22, as shown in FIG. 4, the received wave signal of the frequency f 1 of the received wave RX input to the input / output terminals is transmitted to the first output terminal, and the intermediate frequency f RX of the received signal RX from the next-stage relay device 20 2 input to the input / output terminals is transmitted to the second output terminal, and the local oscillation signal LO of the frequency f IF input to the input terminals is transmitted to the input / output terminals. IF2 The second multiplexer 22 appropriately distributes the frequencies, that is, the frequency f LO of the local oscillation signal LO is transmitted to the input / output terminals. The second multiplexer 22 appropriately distributes the frequencies, that is, the frequency f LO , the frequency f RX , the intermediate frequency f IFIt has the function of a band-pass filter, a low-pass filter, or a high-pass filter for appropriate distribution.

[0027] The input and output terminals of the second multiplexer 22 are connected to an antenna that receives a transmission wave from a mobile station existing within the reception area in the first-stage relay device 20. 1 When the transmission line connected to the next-stage relay device 20 is a coaxial cable, the input and output terminals of the second multiplexer 22 are connected to the coaxial cable by a connector. 2 When the transmission line is an antenna, the input and output terminals of the second multiplexer 22 are connected to an antenna that transmits the local oscillation signal LO and an antenna that receives the received signal RX. IFk Note that the input and output terminals of the second multiplexer 22 may be divided into an input terminal and an output terminal corresponding to the input and output terminals of the second multiplexer 22 in the next-stage relay device 20 and connected to different transmission lines. 2

[0028] Note that in FIGS. 1 to 4, the signal is represented by frequency, and a subscript indicating the stage in the relay device 20 is added to the received wave RX input to each stage of the relay device 20, and a subscript indicating the stage in the next-stage relay device 20 is added to the received signal RX from the next-stage relay device 20. Although the subscript is added, the frequency is the same. IF In the following description, unless otherwise specified, the subscript indicating the stage is omitted for simplicity.

[0029] Among the plurality of relay devices 20 1 , 20 k , the relay devices 20 from the second stage and later other than the first-stage relay device 20 adjacent to the base station 10 1 also have the same configuration as the first-stage relay device 20, and as shown in FIG. 1, they have the first multiplexer 21, the second multiplexer 22, the frequency converter 23, the distributor 24, and the first amplifier 25 to the third amplifier 27. k 1

[0030] The transmission lines connecting adjacent relay devices 20 are each a coaxial cable or an antenna, similar to the transmission line connecting the base station 10 and the first-stage relay device 20. 1 The transmission lines connecting adjacent relay devices 20 are each a coaxial cable or an antenna, similar to the transmission line connecting the base station 10 and the first-stage relay device 20. Each of the plurality of relay devices 20 has an antenna that receives the transmission wave from the mobile station existing within the corresponding reception area as the reception wave RX, and the reception wave RX received by the reception antenna is input to the input / output terminals of the second duplexer 22.

[0031] The relay devices 20 from the second stage onwards k also, like the first-stage relay device 20 1 receive the local oscillation signal LO of frequency f from the local oscillation signal transmission path in the previous-stage relay device 20, and use the local oscillation signal LO to convert the frequency f of the received wave signal by the received wave RX input LO to an intermediate frequency f RX lower than frequency f RX of the received signal RX IF and transmit it to the transmission line connected to the previous-stage relay device 20 via a reception signal generation path, and transmit the local oscillation signal LO of frequency f IF from the local oscillation signal transmission path in the previous-stage relay device 20 to the transmission line connected to the next-stage relay device 20 via a local oscillation signal transmission path, and transmit the intermediate frequency f LO of the received signal RX IF from the next-stage relay device 20 to the transmission line connected to the previous-stage relay device 20 via a reception signal transmission path. IF The relay devices 20 from the second stage onwards

[0032] also have a reception signal generation path in the same manner as the reception signal generation path in the first-stage relay device 20, having the first duplexer 21, the second duplexer 22, the frequency converter 23, and the first amplifier 25. The frequency converter 23 uses one of the local oscillation signals LO of frequency f k distributed from the distributor 24 to convert the received wave signal of frequency f 1 received by the second duplexer 22 and transmitted to an intermediate frequency f RX of the received signal RX LO and converts it to an intermediate frequency f IF of the received signal RX IF and the converted intermediate frequency f IFReceived signal RX IF1 is amplified by the first amplifier 25 and then output to the transmission line via the first multiplexer 21.

[0033] Relay device 20 from the second stage onwards k The local oscillation signal transmission path in also has the first multiplexer 21, the second multiplexer 22, the distributor 24, and the second amplifier 26, similar to the local oscillation signal transmission path in the first-stage relay device 20 1 The first multiplexer 21 receives and distributes the local oscillation signal LO of frequency f LO One of the distributed local oscillation signals LO of frequency f LO is output to the frequency converter 23, and the other distributed local oscillation signal LO of frequency f LO is amplified by the second amplifier 26 and then output to the transmission line connected to the next-stage relay device 20 via the second multiplexer 22.

[0034] Relay device 20 from the second stage onwards k The received signal transmission path in also has the first multiplexer 21, the second multiplexer 22, and the third amplifier 27, similar to the received signal transmission path in the first-stage relay device 20 1 The second multiplexer 22 receives and transmits the received signal RX of the intermediate frequency f 2 from the next-stage relay device 20 IF is amplified by the third amplifier 27 and then output to the transmission line via the first multiplexer 21. IF Note that the final-stage relay device 20 may not have a received signal transmission path, and in the local oscillation signal transmission path, the path after the second amplifier 26 may not be present.

[0035] Next, the operation of the wireless communication system according to Embodiment 1 will be described. The local oscillation signal LO of frequency f LO from the local oscillator 12 in the base station 10 is distributed by the multiplexer 13 and transmitted via the transmission line to the first-stage relay device 20 1 . In the first-stage relay device 20 1 , the frequency f LOThe local oscillation signal LO is distributed by the distributor 24, and the frequency f LO One of the local oscillation signals LO is output to the frequency converter 23 that constitutes the reception signal generation path, and the frequency f LO The other local oscillation signal LO is amplified by the second amplifier 26 that constitutes the local oscillation signal transmission path, and then from the second duplexer 22 through the transmission line to the next-stage relay device 20 2 is output.

[0036] For the relay devices 20 in the second stage and subsequent stages k In the relay device 20 of the previous stage, the local oscillation signal LO with the frequency f LO is distributed by the distributor 24, and the frequency f LO One of the local oscillation signals LO is sent to the frequency converter 23, and the frequency f LO The other local oscillation signal LO is output to the next-stage relay device 20.

[0037] That is, the local oscillation signal LO with the frequency f LO from the local oscillator 12 in the base station 10 is transmitted to the next-stage relay device 20 sequentially through the local oscillation signal transmission path in each relay device 20 and is used in the frequency converter 23 that constitutes the reception signal generation path. Since no local oscillator is provided in each relay device 20 and the local oscillation signal LO with the frequency f LO used in each relay device 20 is aggregated in the local oscillator 12 in the base station 10, by ensuring the frequency stability of the local oscillator 12 in the base station 10, the frequency stability in each relay device 20 can also be ensured, and high frequency stability can be obtained for the entire wireless communication system.

[0038] As the frequency f LO of the local oscillation signal LO, in this example, for example, for the received wave RX 1 of the received wave signal, frequencies in the range of several MHz to 100 MHz can be used for the UHF band such as 300 MHz to 500 MHz, and between the base station 10 and the first-stage relay device 20 RX 1 ​It is possible to suppress the transmission loss in the local oscillation signal LO due to the transmission path connecting thereto and the transmission path connecting to the adjacent relay device 20, and the local oscillation signal LO can be transmitted over a longer distance in a state with a small transmission loss.

[0039] In each relay device 20, when receiving the transmission wave from the mobile station existing in the corresponding reception area as a reception wave, the frequency f of the received reception wave RX RX of the reception wave signal is distributed by the second multiplexer 22 and input to the frequency converter 23 constituting the reception signal generation path. The frequency converter 23 uses one of the local oscillation signals LO of the frequency f RX distributed by the distributor 24 to convert the frequency of the reception wave signal of the frequency f LO to an intermediate frequency f RX lower than f IF (=f RX -f LO ) of the reception signal RX IF for frequency conversion. The reception signal RX of the intermediate frequency f IF is amplified by the first amplifier 25 constituting the reception signal generation path, and then output from the first multiplexer 21 to the previous-stage relay device 20 via the transmission path. IF

[0040] On the other hand, in each relay device 20 that has received the reception signal RX of the intermediate frequency f IF from the next-stage relay device 20, the reception signal RX of the intermediate frequency f IF is distributed by the second multiplexer 22 and amplified by the third amplifier 27 constituting the reception signal transmission path, and then output from the first multiplexer 21 to the previous-stage relay device 20 via the transmission path, and finally transmitted to the base station 10. IF IF At the base station 10, the reception signal RX of the intermediate frequency f IF is distributed by the multiplexer 13 and input to the receiver 11. IF

[0041] That is, the frequency f of the received wave RX received by each relay device 20 RX The received wave signal of is at the frequency f in each relay device 20 RX Lower intermediate frequency f IF (=f RX -f LO ) The received signal RX IF Is frequency-converted to the received signal RX at the intermediate frequency f IF The received signal RX IF Is amplified at the lower intermediate frequency f in the previous-stage relay device 20 IF And is sequentially relayed by the relay device 20 to reach the base station 10.

[0042] The frequency f of the received wave RX received RX The received wave signal of is converted to the received signal RX at the lower intermediate frequency f IF And is sequentially relayed by the relay device 20 to reach the base station 10. Therefore, the transmission loss in the received signal RX IF In the transmission line connecting adjacent relay devices 20 and the transmission line connecting the base station 10 and the first-stage relay device 20 1 Can be suppressed, and the received signal RX IF Can be transmitted over a longer distance with less transmission loss. IF

[0043] As described above, the wireless communication system according to Embodiment 1 includes a base station 10 including a local oscillator 12 that outputs a local oscillation signal LO of a frequency f LO And a plurality of relay devices 20 connected in series to the base station 10. Each relay device 20 uses the local oscillation signal LO of the frequency f from the base station 10 to receive the received wave signal by the received wave RX input LO To the received signal RX at an intermediate frequency f lower than the frequency f of the received wave signal RX IF (=f(=f RX -f LO ) And transmits it to the transmission line, a local oscillation signal transmission path that transmits the local oscillation signal LO of the frequency f from the base station 10 to the transmission line connected to the next-stage relay device 20, and an intermediate frequency f from the next-stage relay device 20 IF LO The local oscillation signal LO of is transmitted to the transmission line connected to the next-stage relay device 20, and the intermediate frequency f from the next-stage relay device 20 IFReceived signal RX IF Since it includes a received signal transmission path that transmits the received signal RX to the transmission path, the local oscillation signal transmission path has a frequency f from the local oscillator 12 in the base station 10 LO In order to transmit the local oscillation signal LO of to the relay device 20 in the next stage in sequence, by ensuring the frequency stability of the local oscillator 12 in the base station 10, the frequency stability in each relay device 20 can also be ensured, and high frequency stability can be obtained for the entire wireless communication system.

[0044] Moreover, the wireless communication system according to Embodiment 1 has a frequency f of the local oscillation signal LO LO As a low frequency, the transmission loss in the local oscillation signal LO due to the transmission path connecting the base station 10 and the first-stage relay device 20 1 And the transmission path connecting adjacent relay devices 20 can be suppressed, and the local oscillation signal LO can be transmitted over a longer distance with a small transmission loss.

[0045] Furthermore, in the wireless communication system according to Embodiment 1, the received wave signal by the received wave RX received in each relay device 20 is converted to an intermediate frequency f at a frequency lower than the frequency f of the received wave signal by the received signal generation path RX Of the received signal RX IF Is transmitted by the received signal transmission path in the relay device 20 in the previous stage to the relay device 20 in the previous stage in sequence and transmitted to the base station 10. Therefore, the base station 10 and the first-stage relay device 20 IF The transmission loss in the received signal RX due to the transmission path connecting and the transmission path connecting adjacent relay devices 20 can be suppressed, and the received signal RX 1 Can be transmitted over a longer distance with a small transmission loss. IF In IF

[0046] Embodiment 2. The wireless communication system according to Embodiment 2 will be described with reference to FIG. 5. The wireless communication system according to Embodiment 1 includes a receiving system that frequency-converts a received wave signal by the received received wave RX into a received signal and relays it to the previous relay device 20 for transmission to the base station 10.

[0047] On the other hand, the wireless communication system according to Embodiment 2 is different in that, in addition to the receiving system in the wireless communication system according to Embodiment 1, it includes a transmitting system that transmits a transmission signal to a plurality of relay devices 20A connected in cascade from the transmitter 14 in the base station 10A. Therefore, hereinafter, in the wireless communication system according to Embodiment 2, since the receiving system is the same as the receiving system in the wireless communication system according to Embodiment 1, the description will be centered on the transmitting system. In FIG. 5, the same reference numerals as those in FIGS. 1 to 4 denote the same or corresponding parts.

[0048] The wireless communication system according to Embodiment 2 includes a base station 10A and a plurality of relay devices 20A connected in cascade to the base station 10A 1 , 20A k . k is an integer of 2 or more. The base station 10A includes a receiver 11, a local oscillator 12, a duplexer 13A, and a transmitter 14. The receiver 11 and the local oscillator 12 are the same as the receiver 11 and the local oscillator 12 in Embodiment 1.

[0049] From the transmitter 14, a transmission signal TX IFT of an intermediate frequency f IFT is output. The intermediate frequency f IFT of the transmission signal TX IFT is a frequency in the same frequency band as the intermediate frequency f IF of the received signal RX IF , and in a full-duplex communication where transmission and reception are simultaneous, it is several MHz to several tens of MHz higher or lower than the intermediate frequency f IF of the received signal RX IF . In a half-duplex communication where transmission and reception are performed alternately, the intermediate frequency f IFT of the transmission signal TX IFT and the intermediate frequency f IF of the received signal RXIF It may be set to the same frequency.

[0050] The multiplexer 13A transmits the local oscillation signal LO from the local oscillator 12 and the intermediate frequency f IFT of the transmission signal TX IFT to the transmission line connected to the first-stage relay device 20A 1 and transmits the intermediate frequency f 1 from the transmission line connected to the first-stage relay device 20A IF of the received signal RX IF to the receiver 11. The multiplexer 13A has a first input terminal, a second input terminal, an output terminal, and an input / output terminal. The first input terminal is connected to the output terminal of the local oscillator 12, the second input terminal is connected to the output terminal of the transmitter 14, the output terminal is connected to the input terminal of the receiver 11, and the input / output terminal is connected to the transmission line connected to the first-stage relay device 20A 1 is connected.

[0051] Similar to the multiplexer 13 in Embodiment 1, the multiplexer 13A has the function of a band-pass filter, a low-pass filter, or a high-pass filter for appropriately distributing the frequencies f LO , the intermediate frequency f IF , the intermediate frequency f IFT . Also, similar to the multiplexer 13 in Embodiment 1, when the transmission line is a coaxial cable, the input / output terminals of the multiplexer 13A are connected to the coaxial cable by connectors. When the transmission line is an antenna, the input / output terminals of the multiplexer 13A are connected to the antenna that transmits the local oscillation signal LO, the antenna that transmits the transmission signal TX IFT , and the antenna that receives the received signal RX 1 from the first-stage relay device 20A IF1 , RX IFk .

[0052] The plurality of relay devices 20A 1 , 20A k basically have the same configuration and include a receiving system, a transmitting system, a fifth multiplexer 41, and a sixth multiplexer 42. The plurality of relay devices 20A1 and 20A k each receive a transmission wave from a mobile station existing in a corresponding reception area as a reception wave, and transmit a transmission wave based on a transmission signal from a transmitter 14 of a base station to a mobile station existing in a transmission area that is the same as the corresponding reception area. 10A to a mobile station existing in the transmission area that is the same as the corresponding reception area.

[0053] The receiving system is the same as the receiving system in the first embodiment, and as shown in FIG. 5, includes a first multiplexer 21, a second multiplexer 22, a frequency converter 23, a distributor 24A, and a third amplifier 27 from a first amplifier 25. The receiving system includes a received signal generation path, a local oscillation signal transmission path, and a received signal transmission path in the same manner as the receiving system in the first embodiment. Therefore, in the following description, a detailed description of the receiving system is omitted.

[0054] As shown in FIG. 5, the transmitting system includes a third multiplexer 31, a fourth multiplexer 32, a frequency converter 33, a distributor 24A, a fourth amplifier 35, and a fifth amplifier 37. The fourth amplifier 35 and the fifth amplifier 37 are provided to supplement the signal strength of the signal to be transmitted, that is, to increase the signal strength. The transmitting system includes a transmission wave signal generation path, a transmission signal transmission path, and a local oscillation signal transmission path. The local oscillation signal transmission path in the transmitting system is shared with the local oscillation signal transmission path in the receiving system.

[0055] The first-stage relay device 20A 1 In, the fifth multiplexer 41 is a frequency multiplexer, and receives a local oscillation signal LO of a frequency f from a local oscillator 12 of a base station, outputs the local oscillation signal LO to a distributor 24A, and receives an intermediate frequency f transmission signal TX output from a transmitter 14 of a base station, outputs it to a third multiplexer 31, and receives a received signal RX of an intermediate frequency f obtained by frequency-converting a received wave signal by a received wave by a frequency converter 23 and amplifying it by a first amplifier 25 from a first multiplexer 21. 10A from a local oscillator 12 of a base station, LO outputs the local oscillation signal LO to a distributor 24A, and 10A receives an intermediate frequency f IFT transmission signal TX IFT output from a transmitter 14 of a base station, outputs it to a third multiplexer 31, and receives a received signal RX of an intermediate frequency f IF obtained by frequency-converting a received wave signal by a received wave by a frequency converter 23 and amplifying it by a first amplifier 25 from a first multiplexer 21.IF1 is output to the base station 10, and the next-stage relay device 20A transmitted from the second combiner 22 and amplified by the third amplifier 27 2 the intermediate frequency f from IF the received signal RX IF2 is output to the base station 10A .

[0056] The fifth combiner 41 has an input / output terminal, an input terminal, a first output terminal, and a second output terminal. The input / output terminal is connected to a transmission line connected to the base station 10A . The input terminal is connected to the output terminal of the first combiner 21. The first output terminal is connected to the input terminal of the splitter 24A , and the second output terminal is connected to the input terminal of the third combiner 31.

[0057] In the fifth combiner 41, the local oscillation signal LO of the frequency f LO input to the input / output terminal is transmitted to the first output terminal, and the received wave signal by the received wave RX 1 input to the input terminal is frequency-converted by the frequency converter 23 to the intermediate frequency f IF the received signal RX IF1 and the next-stage relay device 20A 2 the intermediate frequency f from IF the received signal RX IF2 are transmitted to the input / output terminal, and the transmission signal TX of the intermediate frequency f IFT input to the input / output terminal is transmitted to the second output terminal. IFT The fifth combiner 41 appropriately distributes frequencies, that is, it has the function of a band-pass filter, a low-pass filter, or a high-pass filter for appropriately distributing the frequencies f LO , the intermediate frequency f IF , the intermediate frequency f IFT .

[0058] Base station 10A When the transmission line connected to is a coaxial cable, the input / output terminals of the fifth combiner 41 are connected to the coaxial cable by a connector. ​When the transmission line is an antenna, the input and output terminals of the fifth duplexer 41 are an antenna that receives the local oscillation signal LO, the received signal RX IF1、 RX IFk to the transmitting antenna and the transmitting signal TX IFT are connected to the transmitting antenna. Note that the input and output terminals of the fifth duplexer 41 may be divided into an input terminal and an output terminal corresponding to the input and output terminals of the duplexer 13A in the base station 10A and connected to different transmission lines.

[0059] The sixth duplexer 42 outputs the received wave signal generated by the received wave to the second duplexer 22, the local oscillation signal LO is distributed by the distributor 24A, and the second local oscillation signal LO of the frequency f LO amplified by the second amplifier 26 is output to the relay device 20A 2 in the next stage, and the received signal RX 2 of the intermediate frequency f IF from the relay device 20A IF2 in the next stage is output to the second duplexer 22, and the transmission signal TX IFT of the intermediate frequency f IFT from the fourth duplexer 32 is frequency-converted by the frequency converter 33 and amplified by the fourth amplifier 35 to obtain a transmission wave signal of the frequency f TX which is output to the antenna, transmitted from the third duplexer 31, and amplified by the fifth amplifier 37 to obtain a transmission signal TX IFT of the intermediate frequency f IFT which is output to the relay device 20A 2 in the next stage.

[0060] The sixth duplexer 42 has an input / output terminal, a first input terminal, a second input terminal, and an output terminal. The input / output terminal is connected to a transmission line connected to the relay device 20A 2 in the next stage. The first input terminal is connected to the output terminal of the second amplifier 26 that constitutes the local oscillation signal transmission path. The output terminal is connected to the input terminal of the second duplexer 22. The second input terminal is connected to the output terminal of the 4 duplexer 32 in the first stage.

[0061] In the sixth multiplexer 42, the received received wave RX input to the input / output terminal 1 at the frequency f RX of the received wave signal and the intermediate frequency f 2 from the next-stage relay device 20A IF of the received signal RX IF2 are transmitted to the output terminal, and the local oscillation signal LO at the frequency f LO input to the first input terminal is transmitted to the input / output terminal, and the signal for the transmission wave at the frequency f TX input to the second input terminal and the intermediate frequency f IFT of the transmission signal TX IFT are transmitted to the input / output terminal. The sixth multiplexer 42 appropriately distributes frequencies, that is, it has the function of a band-pass filter, a low-pass filter, or a high-pass filter for appropriately distributing the frequencies f LO , the intermediate frequencies f IF , the intermediate frequencies f IFT , and the frequencies f TX .

[0062] The input / output terminal of the sixth multiplexer 42 is connected to an antenna that receives a transmission wave from a mobile station existing within the reception area in the first-stage relay device 20A 1 . The input / output terminal of the sixth multiplexer 42 is connected to an antenna that transmits a transmission wave to a mobile station existing within the transmission area in the first-stage relay device 20A 1 .

[0063] When the transmission line connected to the next-stage relay device 20A 2 is a coaxial cable, the input / output terminal of the sixth multiplexer 42 is connected to the coaxial cable by a connector. When the transmission line is an antenna, the input / output terminal of the sixth multiplexer 42 is connected to an antenna that transmits the local oscillation signal LO, an antenna that receives the received signal RX IFk , and an antenna that transmits the transmission signal TX IFT . Note that the input / output terminal of the sixth multiplexer 42 corresponds to the input / output terminal of the second multiplexer 22 in the next-stage relay device 20A 2 . causingIt may be divided into an input terminal and an output terminal and connected to different transmission paths.

[0064] The first-stage relay device 20A 1 The signal generation path for the transmission wave in is the base station 10A The intermediate frequency f from the transmitter 14 of IFT The transmission signal TX IFT Is frequency-converted using the local oscillation signal LO with frequency f from the base station 10 to a frequency f LO Higher than the local oscillation signal LO and transmitted to the antenna that transmits the transmission wave TX. TX

[0065] The first-stage relay device 20A 1 The signal generation path for the transmission wave in has a third combiner 31, a fourth combiner 32, a second frequency converter 33, and a fourth amplifier 35. As shown in FIG. 5, the third combiner 31 receives the intermediate frequency f IFT The transmission signal TX IFT And the second frequency converter 33 frequency-converts it to a frequency f LO Of the third local oscillation signal LO distributed from the distributor 24A to a transmission wave signal with a frequency higher than the intermediate frequency f IFT Of f TX After frequency-converting the transmission wave signal of, the transmission wave signal of the frequency-converted f TX Is amplified by the fourth amplifier 35 and then transmitted to the sixth combiner 42 via the fourth combiner 32.

[0066] The frequency f TX The sixth combiner 42 into which the transmission wave signal of is input outputs the transmission wave signal of frequency f TX To the antenna, and is transmitted from the antenna as a transmission wave TX with frequency f TX To the corresponding transmission area. The frequency f TX And the intermediate frequency f IFT The relationship between and is f TX = f IFT + f LO Is established.

[0067] The first-stage relay device 20A 1 The transmission signal transmission path in is the base station10A The intermediate frequency f from the transmitter 14 IFT of the transmission signal TX IFT is transmitted to the transmission line connected to the next-stage relay device 20A 2 . The transmission signal transmission path in the first-stage relay device 20A 1 has a third duplexer 31, a fourth duplexer 32, and a fifth amplifier 37. As shown in FIG. 5, the third duplexer 31 receives the intermediate frequency f IFT of the transmission signal TX IFT , amplifies it by the fifth amplifier 37, and then transmits it to the sixth duplexer 42 via the fourth duplexer 32 The sixth duplexer 42 transmits the intermediate frequency f IFT of the transmission signal TX IFT to the transmission line connected to the next-stage relay device 20A 2 .

[0068] The third duplexer 31 is a frequency duplexer that receives the intermediate frequency f IFT of the transmission signal TX IFT , and transmits the transmission signal TX IFT to the second frequency converter 33 and the fifth amplifier 37 respectively The third duplexer 31 has a function of distributing the intermediate frequency f IFT of the transmission signal TX IFT to the second frequency converter 33 and the fifth amplifier 37 respectively

[0069] The third duplexer 31 has an input terminal, a first output terminal, and a second output terminal. The input terminal is connected to the second output terminal of the fifth duplexer 41, the first output terminal is connected to the input terminal of the second frequency converter 33, and the second output terminal is connected to the input terminal of the fifth amplifier 37 The intermediate frequency f IFT of the transmission signal TX input to the input terminal of the third duplexer 31 IFT is transmitted to the first output terminal and the second output terminal The third duplexer 31 has the function of a band-pass filter, a low-pass filter, or a high-pass filter

[0070] The fourth combiner 32 is a frequency combiner, and the second frequency converter 33 converts the transmission signal TX IFT at the intermediate frequency f IFT and transmits the transmission wave signal at the intermediate frequency f TX amplified by the fourth amplifier 35 and the transmission signal TX IFT at the intermediate frequency f IFT from the fifth amplifier 37 to the sixth combiner 42. The fourth combiner 32 has a first input terminal, a second input terminal, and an output terminal. The first input terminal is connected to the output terminal of the fourth amplifier 35, the second input terminal is connected to the output terminal of the fifth amplifier 37, and the output terminal is connected to the input terminal of the sixth combiner 42.

[0071] In the fourth combiner 32, the transmission wave signal at the frequency f TX input to the first input terminal is transmitted to the output terminal, and the transmission signal TX IFT at the intermediate frequency f IFT input to the second input terminal is transmitted to the output terminal. The fourth combiner 32 appropriately distributes frequencies, that is, it has the function of a band-pass filter, a low-pass filter, or a high-pass filter for appropriately distributing the intermediate frequency f IFT and the frequency f TX .

[0072] In addition, in FIG. 5, the signals are represented by frequencies, and a subscript indicating the stage in the relay device 20A is added to the received wave RX input to each stage of the relay device 20A, and a subscript indicating the stage in the next-stage relay device 20A is added to the received signal RX IF from the next-stage relay device 20A. Although subscripts are added, the frequencies are the same. In the following description, unless otherwise specified, the subscripts indicating the stages are omitted for simplicity.

[0073] The relay devices 20A from the second stage onwards k also, like the first-stage relay device 20A 1It has the same configuration, and as shown in FIG. 5, as a receiving system, from the first combiner 21, the second combiner 22, the first frequency converter 23, the distributor 24A, and the first amplifier 25 to the third amplifier 27, and as a transmitting system, it has the third combiner 31, the fourth combiner 32, the frequency converter 33, the distributor 24A, the fourth amplifier 35, the fifth amplifier 37, the fifth combiner 41, and the sixth combiner 42.

[0074] The transmission lines connecting between adjacent relay devices 20A are each a coaxial cable or an antenna, similar to the transmission line connecting the base station 10A and the first-stage relay device 20A. 1 Each of the plurality of relay devices 20A has an antenna for receiving a transmission wave from a mobile station existing within a corresponding reception area as a reception wave RX, and the reception wave RX received by the reception antenna is input to the input / output terminals of the sixth combiner 42. Also, each of the plurality of relay devices 20A has an antenna for transmitting a transmission wave to a mobile station existing within a corresponding transmission area, and a transmission wave signal obtained by frequency-converting a transmission signal from the transmitter 14 in the base station 10A for the transmission wave transmitted by the transmission antenna is input to the input / output terminals of the sixth combiner 42.

[0075] For the relay devices 20A from the second stage onwards k the fifth combiner 41 also, similar to the fifth combiner 41 of the first-stage relay device 20A 1 transmits the local oscillation signal LO of frequency f from the local oscillation signal transmission path in the previous-stage relay device 20A input to the input / output terminals to the first output terminal, and transmits the received wave signal by the received wave RX LO input to the input / output terminals to the received signal RX of intermediate frequency f 1 frequency-converted by the frequency converter 23, and IF the received signal RX IF and the received signal RX of intermediate frequency f from the next-stage relay device 20A IF to the input / output terminals, and transmits from the input / output terminals to the second output terminal the transmission signal transmission path in the previous-stage relay device 20A input thereto. IF

[0076] ​​ The relay device 20A from the second stage onwards k The sixth combiner 42 of the relay device 20A in the first stage 1 Similarly to the sixth combiner 42 of the relay device 20A in the first stage, the received wave RX input to the input / output terminals 1 The received wave signal of frequency f RX And the received signal RX of intermediate frequency f from the relay device 20A in the next stage IF Are transmitted to the output terminals, and the local oscillation signal LO of frequency f input to the first input terminal is transmitted to the input / output terminals, and the signal for transmission wave of frequency f and the transmission signal TX of intermediate frequency f IF Input to the second input terminal are transmitted to the input / output terminals. LO The relay device 20A from the second stage onwards TX Also, similarly to the relay device 20A in the first stage, the local oscillation signal LO of frequency f from the local oscillation signal transmission path in the relay device 20A in the previous stage and the transmission signal TX of intermediate frequency f from the transmission signal transmission path in the relay device 20A in the previous stage IFT Are received, and using the local oscillation signal LO, the transmission signal TX IFT Is frequency-converted to a signal for transmission wave of a frequency f higher than the intermediate frequency f

[0077] And transmitted to the transmission wave generation path for transmitting the transmission wave to the antenna, and the transmission signal TX of intermediate frequency f k From the transmission signal transmission path in the relay device 20A in the previous stage is provided with a transmission signal transmission path for transmitting to the transmission line connected to the relay device 20A in the next stage. 1 The transmission wave generation path in the relay device 20A from the second stage onwards LO Also, similarly to the transmission wave generation path in the relay device 20A in the first stage, has a third combiner 31, a fourth combiner 32, a second frequency converter 33, and a fourth amplifier 35, and the third combiner 31 receives the transmission signal TX of intermediate frequency f IFT From the fifth combiner 41 IFT And the transmission signal TX of intermediate frequency f from the transmission signal transmission path in the relay device 20A in the previous stage IFT Are received, and using the local oscillation signal LO, the transmission signal TX IFT Is frequency-converted to a signal for transmission wave of a frequency f higher than the intermediate frequency f TX And transmitted to the antenna for transmitting the transmission wave, and the transmission signal TX of intermediate frequency f IFT From the transmission signal transmission path in the relay device 20A in the previous stage is provided with a transmission signal transmission path for transmitting to the transmission line connected to the relay device 20A in the next stage. IFT The relay device 20A from the second stage onwards

[0078] The transmission wave generation path in the relay device 20A from the second stage onwards k Also, similarly to the transmission wave generation path in the relay device 20A in the first stage, has a third combiner 31, a fourth combiner 32, a second frequency converter 33, and a fourth amplifier 35, and the third combiner 31 receives the transmission signal TX of intermediate frequency f 1 From the fifth combiner 41 IFT Of the transmission signal TXIFT The second frequency converter 33 uses the third local oscillation signal LO of the frequency f distributed from the distributor 24A LO to convert the intermediate frequency f IFT to a frequency f that is higher than the frequency f TX of the transmission wave signal, and after amplifying the frequency-converted transmission wave signal of the frequency f TX by the fourth amplifier 35, it is transmitted to the sixth duplexer 42 via the fourth duplexer 32.

[0079] The transmission signal transmission path in the relay device 20A from the second stage onwards k is also the same as the transmission signal transmission path in the first-stage relay device 20A 1 and has the third duplexer 31, the fourth duplexer 32, and the fifth amplifier 37. The third duplexer 31 receives the intermediate frequency f IFT of the transmission signal TX IFT from the fifth duplexer 41, amplifies it by the fifth amplifier 37, and then transmits it to the sixth duplexer 42 via the fourth duplexer 32. Note that the final-stage relay device 20A may not have a reception signal transmission path, and in the local oscillation signal transmission path, the path after the second amplifier 26 may not be provided, and the transmission signal transmission path may not be provided either.

[0080] Next, the operation of the wireless communication system according to Embodiment 2 will be described. The operation of the reception system is the same as that of the wireless communication system according to Embodiment 1, so the description will be omitted. The local oscillation signal LO of the frequency f from the base station 10 LO is distributed to the fifth duplexer 41 in each relay device 20A, and is distributed by the distributor 24A to the first to third local oscillation signals LO of the frequency f. The first local oscillation signal LO of the frequency f LO is output to the first frequency converter 23 that constitutes the reception signal generation path, and the second local oscillation signal LO of the frequency f LO is amplified by the second amplifier 26 that constitutes the local oscillation signal transmission path, and then output from the sixth duplexer 42 to the next-stage relay device 20A via the transmission line. The frequency f LOThe third local oscillation signal LO is output to the second frequency converter 33 that constitutes the transmission wave signal generation path.

[0081] That is, the base station 10A The local oscillation signal LO with frequency f from the local oscillator 12 in is transmitted to the next-stage relay device 20A in sequence through the local oscillation signal transmission path in each relay device 20A, and is used in the first frequency converter 23 that constitutes the reception signal generation path and the second frequency converter 33 that constitutes the transmission wave signal generation path. LO Since no local oscillator is provided in each relay device 20A and the local oscillation signal LO with frequency f used in each relay device 20A is aggregated in the local oscillator 12 in the base station, by ensuring the frequency stability of the local oscillator 12 in the base station 10, the frequency stability in each relay device 20A can also be ensured, and high frequency stability can be obtained for the entire wireless communication system. In each relay device 20A, the intermediate frequency f LO The local oscillation signal LO is aggregated in the local oscillator 12 in the base station 10A Since it is aggregated, by ensuring the frequency stability of the local oscillator 12 in the base station 10, the frequency stability in each relay device 20A can also be ensured, and high frequency stability can be obtained for the entire wireless communication system.

[0082] In each relay device 20A, the transmission signal TX of the intermediate frequency f IFT That is distributed to the fifth duplexer 41 and further distributed to the third duplexer 31 is input to the second frequency converter 33. IFT The second frequency converter 33 uses the third local oscillation signal LO with frequency f That is distributed by the distributor 24A to convert the frequency of the transmission signal TX of the intermediate frequency f IFT To a transmission wave signal with a frequency f IFT Higher than the intermediate frequency f LO (=f IFT +f TX (=f IFT +f LO ). The transmission wave signal with frequency f TX Is amplified by the first amplifier 25 that constitutes the transmission wave signal generation path, then input to the antenna from the sixth duplexer 42 through the fourth duplexer 32, and transmitted as a transmission wave to the mobile station existing in the corresponding transmission area from the antenna.

[0083] On one hand, in each relay device 20A, the intermediate frequency f input to the input terminal of the fifth amplifier 37 that constitutes the transmission signal transmission path, which is distributed by the fifth multiplexer 41 and further distributed by the third multiplexer 31 IFT of the transmission signal TX IFT is amplified by the fifth amplifier 37, then output from the sixth multiplexer 42 via the fourth multiplexer 32 to the next-stage relay device 20A through the transmission path, and finally transmitted to the relay device 20A at the final stage.

[0084] That is, in each relay device 20A, the input intermediate frequency f IFT of the transmission signal TX IFT is frequency-converted in each relay device 20A into a transmission wave signal of frequency f TX to form a configuration for each relay device 20A from to transmit a transmission wave. doing Therefore, the transmission signal TX input to each relay device 20A IFT remains at the low intermediate frequency f IFT to transmit through the transmission path connecting adjacent relay devices 20A and the base station 10A and the transmission path connecting the base station 1 to the first-stage relay device 20A. IFT Thus, the transmission loss in the transmission signal TX IFT can be suppressed, and the transmission signal TX IFT can be transmitted over a longer distance with a smaller transmission loss.

[0085] The wireless communication system according to Embodiment 2 has the same effects as the wireless communication system according to Embodiment 1 in the receiving system. Furthermore, each relay device 20A uses the local oscillation signal LO of frequency f 10A from the local oscillator 12 in the base station LO and the transmission signal TX of intermediate frequency f 10A from the transmitter 14 in the base station IFT to frequency-convert the transmission signal TX IFT to a frequency f IFT higher than the intermediate frequency f IFT , which is frequency f TX (=f IFT +f LOConvert it into a signal for the transmission wave, and transmit it to the antenna that transmits the transmission wave. The signal generation path for the transmission wave is transmitted to the transmission signal transmission path that is transmitted to the relay device 20A in the next stage. Since the transmission system is provided, the local oscillation signal LO of the frequency f from the local oscillator 12 and the intermediate frequency f of the transmitter 14 IFT The transmission signal TX IFT Is transmitted to the transmission path connected to the relay device 20A in the next stage. Therefore, by ensuring the frequency stability of the local oscillator 12 in the base station 10A, the frequency stability can also be ensured in the transmission system of each relay device 20A, and high frequency stability can be obtained for the entire wireless communication system. LO The local oscillation signal LO and the intermediate frequency f of the transmitter 14 IFT The transmission signal TX IFT In order to transmit it to the relay device 20A in the next stage in sequence, by ensuring the frequency stability of the local oscillator 12 in the base station 10A, the frequency stability can also be ensured in the transmission system of each relay device 20A, and high frequency stability can be obtained for the entire wireless communication system.

[0086] Furthermore, the intermediate frequency f IFT The transmission signal TX IFT Is transmitted by the transmission signal transmission path in the relay device 20A to the relay device 20A in the next stage in sequence and transmitted to the relay device 20A in the final stage. Therefore, the transmission loss in the transmission signal TX IFT Can be suppressed, and the transmission signal TX IFT Can be transmitted over a longer distance with a small transmission loss.

[0087] Note that the wireless communication system according to the second embodiment uses the local oscillation signal LO of the frequency f from the local oscillator 12 for both the reception system and the transmission system. However, for the transmission system, the frequency f of the reception system LO Is different from the frequency f LO Of the local oscillation signal LO of the frequency f LOT Is generated by a local oscillator provided in the base station 10A. In each relay device 20A, the local oscillation signal LO of the frequency f from the local oscillator in the base station 10A T Is used by the second frequency converter 33 to convert the intermediate frequency f LOT The transmission signal TX T Into a signal for the transmission wave of the frequency (f IFT The transmission signal TX IFT May be frequency-converted into a signal for the transmission wave of the frequency (f IFT + f LOT ).

[0088] In this case, in each relay device 20A, similar to the receiving system, a local oscillation signal LO LOT with a frequency f T is distributed, and one local oscillation signal LO LOT with a frequency f T is output to the second frequency converter 33, and a distributor that outputs the other local oscillation signal LO LOT with a frequency f T to the next-stage relay device 20A may be provided.

[0089] Thus, in the receiving system and the transmitting system, the degrees of freedom in frequency selection can be increased by the different frequencies f T of the local oscillation signals LO, LO LO , f LOT . Also, by ensuring the frequency stability of the local oscillator for the transmitting system in the base station 10A , the frequency stability can also be ensured in the transmitting system of each relay device 20A, and high frequency stability can be obtained for the entire wireless communication system.

[0090] Embodiment 3. A wireless communication system according to Embodiment 3 will be described with reference to FIG. 6. The wireless communication system according to Embodiment 3 is different from the wireless communication system according to Embodiment 1 in that each relay device 20B is provided with a frequency multiplier 28 that multiplies one local oscillation signal LO from the distributor 24 and outputs it to the frequency converter 23, and the other points are the same. In FIG. 6, the same reference numerals as those in FIGS. 1 to 4 indicate the same or corresponding parts.

[0091] Hereinafter, the description will focus on the differences from the wireless communication system according to Embodiment 1. The wireless communication system according to Embodiment 2 includes a base station 10 and a plurality of relay devices 20B 1 , 20B k vertically connected to the base station 10. k is an integer of 2 or more. The relay device 20B 1 represents the first-stage relay device adjacent to the base station, and the relay device 20B kIt shows the relay devices from the second stage onwards.

[0092] The base station 10 is the same as the wireless communication system according to Embodiment 1, and as shown in FIG. 6, it includes a receiver 11, a local oscillator 12, and a duplexer 13. The local oscillator 12 outputs a local oscillation signal LO with a frequency f LO . A plurality of relay devices 20B 1 , 20B k basically have the same configuration. As shown in FIG. 6, they have a first duplexer 21, a second duplexer 22, a frequency converter 23, a distributor 24, a frequency multiplier 28, and amplifiers 25 to 27.

[0093] The frequency multiplier 28 multiplies the frequency of one of the local oscillation signals LO with a frequency f LO distributed from the distributor 24, and outputs it as the local oscillation signal LO with a frequency f LOH to the frequency converter. H The relationship between the frequency f LO and the frequency f LOH is f LOH = mf LO . m is a number greater than 1, and f LOH > f LO .

[0094] The frequency converter 23 frequency-converts the received wave signal with a frequency f RX of the received wave RX received by the second duplexer 22 to an intermediate frequency f LOH lower than the frequency f H using the local oscillation signal LO with a frequency f RX from the frequency multiplier 28. IFL The received signal RX IFL The relationship between the frequency f RX and the intermediate frequency f IFL is f IFL = f RX - f LOH = f RX - mf LO < f RX - f LO .

[0095] Therefore, in each relay device 20, the received wave signal by the received wave RX received is frequency-converted to an intermediate frequency f that is lower than the frequency f RX of the received wave signal by the received signal generation path IFL of the received signal RX IFL is sequentially transmitted to the previous relay device 20B through the received signal transmission path in the previous relay device 20B and then transmitted to the base station 10. Therefore, the transmission loss of the received signal RX 1 in the transmission path connecting the base station 10 and the first-stage relay device 20B and the transmission path connecting adjacent relay devices 20B can be further suppressed, and the received signal RX IFL can be transmitted over a longer distance in a state with low transmission loss. IFL

[0096] Next, the operation of the wireless communication system according to Embodiment 3 will be described. The wireless communication system according to Embodiment 3 is different from the wireless communication system according to Embodiment 1 described above in that a frequency multiplier 28 that multiplies one local oscillation signal LO from the distributor 24 and outputs it to the frequency converter 23 is provided in each relay device 20B. Since the other points are the same, the operation of the wireless communication system according to Embodiment 2 is basically the same as the operation of the wireless communication system according to Embodiment 1, so it will be briefly described.

[0097] The local oscillation signal LO with frequency f LO from the local oscillator 12 in the base station 10 is distributed by the combiner 13 and transmitted to the first-stage relay device 20B 1 through the transmission path. The first-stage relay device 20B 1 The input local oscillation signal LO with frequency f LO is transmitted to the next-stage relay device 20B sequentially through the local oscillation signal transmission path in each relay device 20B, similar to the wireless communication system according to Embodiment 1.

[0098] In each relay device 20B, the input frequency f LOThe local oscillation signal LO is distributed by the distributor 24, and the distributed frequency is f LO One of the local oscillation signals LO is multiplied by the frequency multiplier 28, and the frequency is f LOH The local oscillation signal LO H is input to the frequency converter 23 as such. On the other hand, in each relay device 20B, when receiving the transmission wave from the mobile station existing in the corresponding reception area as the reception wave, the frequency f RX of the received wave signal is converted by the frequency converter 23 into the intermediate frequency f LOH using the local oscillation signal LO H to convert the received wave signal of the frequency f IFL (=f RX -f LOH ) into the received signal RX IFL of the frequency.

[0099] Also, in each relay device 20 that has received the received signal RX IFL of the intermediate frequency f IFL from the next-stage relay device 20B, the received signal RX IFL of the intermediate frequency f IFL is sequentially transmitted to the previous-stage relay device 20B through the received signal transmission path and finally transmitted to the base station 10. At the base station 10, the received signal RX IFL of the intermediate frequency f IFL is distributed by the multiplexer 13 and input to the receiver 11.

[0100] As described above, the wireless communication system according to Embodiment 3 has the same effects as the wireless communication system according to Embodiment 1. In addition, the frequency of the local oscillation signal LO of the frequency f LO is multiplied by the frequency multiplier 28 and input to the frequency converter 23. The frequency converter 23 uses the local oscillation signal LO LOH to convert the received wave signal of the frequency f H received by the received wave RX into the received signal RX RX of the intermediate frequency f IFL (=f RX -f LOH ) of the frequency IFL and converts it into the lower intermediate frequency f IFLSince it is sequentially relayed to the relay device 20B and reaches the base station 10 as it is, the transmission loss in the received signal RX due to the transmission line connecting the base station 10 and the first-stage relay device 20B 1 and the transmission line connecting adjacent relay devices 20B can be further suppressed, and the received signal RX IFL can be transmitted over a longer distance in a state with low transmission loss. IFL

[0101] Note that in the wireless communication system according to Embodiment 3, the frequency of the local oscillation signal LO from the local oscillator 12 is f LO However, if the frequency of the local oscillation signal LO from the local oscillator 12 is set to a frequency lower than f LO and the multiplication by the frequency multiplier 28 is increased, the local oscillation signal LO and the received signal RX transmitted through the transmission line connecting the base station 10 and the first-stage relay device 20B 1 and the transmission line connecting adjacent relay devices 20 can be set to a lower frequency, and the local oscillation signal LO and the received signal RX IFL can be transmitted over a longer distance in a state with low transmission loss. IFL

[0102] Also, in the wireless communication system according to Embodiment 3, the idea of providing a frequency multiplier 28 that multiplies one of the local oscillation signals LO from the distributor 24 and outputs it to the frequency converter 23 is not only applicable to the receiving system in the wireless communication system according to Embodiment 2, but may also be applied to the transmitting system.

[0103] That is, in the wireless communication system according to Embodiment 2, the received signal generation path has a first frequency multiplier that multiplies the second local oscillation signal LO having a frequency f LO distributed from the distributor 24 and outputs the local oscillation signal LO having a frequency f LOH to the first frequency converter 23 as (= mf H ), and the transmission wave signal generation path multiplies the third local oscillation signal LO having a frequency f LO distributed from the distributor 24A and outputs the local oscillation signal LO having a frequency f LOH to the first frequency converter 23 as (= mf LOH )​​H Output it as the second frequency multiplier that outputs to the second frequency converter 33 as (=mf LO ) may be provided. Note that the multiplication by the first frequency multiplier and the second frequency multiplier is the same, but different multiplications may also be used.

[0104] Embodiment 4. The wireless communication system according to Embodiment 4 will be described with reference to FIG. 7. The wireless communication system according to Embodiment 4 is different from the wireless communication system according to Embodiment 1 in that a leaky coaxial cable (LCX: Leaky Coaxial Cable) 100 is used as the transmission line connecting the base station 10 and the first-stage relay device 20 1 and the transmission line connecting between the transmission line connecting the adjacent relay devices 20, and the other points are the same. In FIG. 6, the same reference numerals as those attached to FIGS. 1 to 4 indicate the same or corresponding parts.

[0105] Hereinafter, the description will focus on the differences from the wireless communication system according to Embodiment 1. The input and output terminals of the duplexer 13 are connected to the leaky coaxial cable 100 by a connector. In each relay device 20, the input and output terminals of the first duplexer 21 are connected to the leaky coaxial cable 100 by a connector, and the input and output terminals of the second duplexer 22 are connected to the leaky coaxial cable 100 by a connector.

[0106] Since the input and output terminals of the second duplexer 22 are connected to the leaky coaxial cable 100, each relay device 20 does not require an antenna for receiving the transmission wave from the mobile station existing in the corresponding reception area as the reception wave RX, and the leaky coaxial cable 100 connected to the input and output terminals of the second duplexer 22 receives the transmission wave from the mobile station existing in the corresponding reception area as the reception wave RX.

[0107] The leaky coaxial cable 100 has the characteristic that the lower the frequency, the less likely the passing signal is to leak and the smaller the transmission loss. Therefore, the frequency f of the local oscillation signal LO from the local oscillator 12 in the base station 10 LO and the received wave RX in each relay device 1 The received signal RX obtained by frequency-converting the received wave signal by IF The intermediate frequency f of IF As, a low frequency that is difficult to leak from the leaky coaxial cable 100 is selected.

[0108] The configurations and operations of the base station 10 and each relay device 20 in the wireless communication system according to Embodiment 4 are substantially the same as those of the base station 10 and each relay device 20 in the wireless communication system according to Embodiment 1, and thus the description thereof is omitted.

[0109] The wireless communication system according to Embodiment 4 has the same effects as the wireless communication system according to Embodiment 1, and in addition, has the following effects. That is, the local oscillation signal LO from the local oscillator 12 in the base station 10 is transmitted to the first-stage relay device 20 via the leaky coaxial cable 100 1 Therefore, a lower frequency f can be selected according to the leaky coaxial cable 100, and transmission over a longer distance can be performed in a state with small transmission loss. Furthermore, leakage of the local oscillation signal LO from the leaky coaxial cable 100 can be substantially suppressed from being radiated into space LO Therefore, the frequency utilization efficiency does not decrease. able For

[0110] In each relay device, the frequency f of the local oscillation signal LO transmitted to the next-stage relay device 20 through the local oscillation signal transmission path LO Is also selected to a lower frequency f according to the leaky coaxial cable 100 LO In order to transmit the leaky coaxial cable 100 connecting between adjacent relay devices 20, transmission over a longer distance can be performed in a state with small transmission loss.

[0111] Also, in each relay device, the received wave RX 1 The received signal RX obtained by frequency-converting the received wave signal by IF The intermediate frequency f of IFA lower frequency f can be selected according to the leakage coaxial cable 100, and the leakage coaxial cable 100 is transmitted at the low intermediate frequency f and sequentially relayed to the relay device 20 and then reaches the base station 10. Therefore, transmission over a longer distance can be performed with a small transmission loss. LO can be selected, and the leakage coaxial cable 100 is transmitted at the low intermediate frequency f IF and sequentially relayed to the relay device 20 and then reaches the base station 10. Therefore, transmission over a longer distance can be performed with a small transmission loss.

[0112] Note that the wireless communication system according to the fourth embodiment applies the idea of using the leakage coaxial cable 100 as the transmission line connecting the base station 10 and the first-stage relay device 20 1 and the transmission line connecting between adjacent relay devices 20 to the wireless communication system according to the second embodiment and the wireless communication system according to the third embodiment. That is, for the wireless communication system according to the second embodiment, the leakage coaxial cable 100 may be used as the transmission line connecting the base station 10 and the first-stage relay device 20A 1 and the transmission line connecting between adjacent relay devices 20A. Further, for the wireless communication system according to the third embodiment, the leakage coaxial cable 100 may be used as the transmission line connecting the base station 10 and the first-stage relay device 20B 1 and the transmission line connecting between adjacent relay devices 20B.

[0113] In addition, free combinations of each embodiment, or modifications of any components of each embodiment, or omissions of any components in each embodiment are possible.

Industrial Applicability

[0114] The wireless communication system according to the present disclosure is suitable for a wireless communication system that uses a transmitter mounted on a railway vehicle or an automobile as a mobile station and relays wireless communication for trains or road traffic.

Explanation of Signs

[0115] 10 Base station, 11 Receiver, 12 Local oscillator, 13, 13A Diplexer, 14 Transmitter, 20, 20 1 、20k、 20A, 20A 1 , 20A k、 20B, 20B 1 , 20B k Relay device, 21 First coupler, 22 Second coupler, 23 Frequency converter, 24, 24A Distributor, 25 - 27 First amplifier to third amplifier, 28 Frequency multiplier, 31 Third coupler, 32 Fourth coupler, 33 Frequency converter, 35 Fourth amplifier, 37 Fifth amplifier, 41 Fifth coupler, 42 Sixth coupler, 100 Leaky coaxial cable.

Claims

1. A base station and a plurality of relay devices connected in cascade to the base station, each receiving a transmission wave from a mobile station as a received wave, The base station includes a receiver, a local oscillator that outputs a local oscillation signal, and a duplexer that transmits the local oscillation signal from the local oscillator to a transmission line and transmits a received signal from the transmission line to the receiver. Among the plurality of relay devices, the relay device adjacent to the base station receives the local oscillation signal from the base station, uses the local oscillation signal to frequency-convert a received wave signal by an input received wave into a received signal having a frequency lower than the frequency of the received wave signal, and transmits the frequency-converted received signal to a transmission line connected to the base station; a received signal generation path for transmission; a local oscillation signal transmission path for transmitting the local oscillation signal from the base station to a transmission line connected to the next-stage relay device; a received signal transmission path for transmitting a received signal from the next-stage relay device to a transmission line connected to the base station, Among the plurality of relay devices, relay devices other than the relay device adjacent to the base station receive the local oscillation signal from the local oscillation signal transmission path in the previous-stage relay device, use the local oscillation signal to frequency-convert a received wave signal by an input received wave into a received signal having a frequency lower than the frequency of the received wave signal, and transmit the frequency-converted received signal to a transmission line connected to the previous-stage relay device; a received signal generation path for transmission; a local oscillation signal transmission path for transmitting the local oscillation signal from the local oscillation signal transmission path in the previous-stage relay device to a transmission line connected to the next-stage relay device; a received signal transmission path for transmitting a received signal from the next-stage relay device to a transmission line connected to the previous-stage relay device, A wireless communication system.

2. Each of the plurality of relay devices has a first duplexer, a second duplexer, a frequency converter, and a distributor. The received signal generation path includes the first duplexer, the second duplexer, and the frequency converter. The second duplexer receives a received wave signal by a received wave that has received a transmission wave from a mobile station as a received wave, and the frequency converter uses one of the local oscillation signals distributed from the distributor to frequency-convert the received wave signal into a received signal, and outputs the frequency-converted received signal via the first duplexer. The local oscillation signal transmission path includes the first duplexer, the second duplexer, and the distributor. The distributor distributes the local oscillation signal received and transmitted by the first duplexer, and outputs the other distributed local oscillation signal via the second duplexer. The received signal transmission path has the first combiner and the second combiner, and outputs a received signal from a relay device at the next stage received and transmitted by the second combiner via the first combiner. The wireless communication system according to claim 1.

3. The wireless communication system according to claim 2, wherein the received signal generation path has a frequency multiplier that multiplies one local oscillation signal distributed from the distributor and outputs the multiplied signal to the frequency converter.

4. The base station includes a transmitter. Each of the plurality of relay devices includes an antenna that transmits a transmission wave. The relay device adjacent to the base station A transmission wave signal generation path that frequency-converts a transmission signal from the transmitter into a transmission wave signal having a frequency higher than that of the local oscillation signal using the local oscillation signal from the base station and transmits the signal to an antenna that transmits a transmission wave; A transmission signal transmission path that transmits a transmission signal from the transmitter to a transmission line connected to a relay device at the next stage. Relay devices other than the relay device adjacent to the base station A transmission wave signal generation path that frequency-converts a transmission signal from the transmission signal transmission path in the previous relay device into a transmission wave signal having a frequency higher than that of the transmission signal using the local oscillation signal from the local oscillation signal transmission path in the previous relay device and transmits the signal to an antenna that transmits a transmission wave; A transmission signal transmission path that transmits a transmission signal from the transmission signal transmission path in the previous relay device to a transmission line connected to a relay device at the next stage. The wireless communication system according to claim 1.

5. Each of the plurality of relay devices has a first combiner, a second combiner, a first frequency converter, a distributor, a third combiner, a fourth combiner, a second frequency converter, a fifth combiner, and a sixth combiner. The received signal generation path has the first combiner, the second combiner, and the first frequency converter. A received wave signal generated by a received wave received as a transmission wave from a mobile station is received by the sixth combiner, and the received wave signal generated by the received wave transmitted via the second combiner is frequency-converted into a received signal by the first frequency converter using the first local oscillation signal distributed from the distributor. The frequency-converted received signal is output via the first combiner and the fifth combiner. The local oscillation signal transmission path includes the first combiner, the second combiner, and the distributor. The distributor distributes the local oscillation signal received and transmitted by the first combiner via the fifth combiner, and outputs the distributed second local oscillation signal via the second combiner and the sixth combiner. The received signal transmission path includes the first combiner and the second combiner. The received signal from the next-stage relay device received and transmitted by the second combiner via the sixth combiner is output via the first combiner and the fifth combiner. The transmission wave signal generation path includes the third combiner, the fourth combiner, and the second frequency converter. The second frequency converter frequency-converts the transmission signal received by the third combiner via the fifth combiner into a transmission wave signal using the third local oscillation signal distributed from the distributor, and outputs it via the fourth combiner and the sixth combiner. The transmission signal transmission path includes the third combiner and the fourth combiner. The transmission signal received by the third combiner via the fifth combiner is output via the fourth combiner and the sixth combiner. The wireless communication system according to claim 4.

6. The received signal generation path includes a first frequency multiplier that multiplies the second local oscillation signal distributed from the distributor and outputs it to the first frequency converter. The wireless communication system according to claim 5, wherein the transmission wave signal generation path includes a second frequency multiplier that multiplies the third local oscillation signal distributed from the distributor and outputs it to the second frequency converter.

7. The transmission line connecting the received signal generation path in the base station and the relay device adjacent to the base station, the transmission line connecting the local oscillation signal transmission path in the previous stage and the received signal generation path in the next-stage relay device in the adjacent relay devices among the plurality of relay devices, the transmission line connecting the received signal transmission path in the relay device adjacent to the base station and the base station, and the transmission lines connecting the received signal transmission paths in the adjacent relay devices among the plurality of relay devices are all coaxial cables. The wireless communication system according to any one of claims 1 to 6.

8. A transmission line connecting a reception signal generation path in the base station and a relay device adjacent to the base station, a transmission line connecting a previous-stage local oscillation signal transmission path in an adjacent relay device among the plurality of relay devices and a reception signal generation path in a next-stage relay device, a transmission line connecting a reception signal transmission path in a relay device adjacent to the base station and the base station, and a transmission line connecting reception signal transmission paths in adjacent relay devices among the plurality of relay devices are each an antenna. The wireless communication system according to any one of claims 1 to 6.

9. A transmission line connecting a reception signal generation path in the base station and a relay device adjacent to the base station, a transmission line connecting a previous-stage local oscillation signal transmission path in an adjacent relay device among the plurality of relay devices and a reception signal generation path in a next-stage relay device, a transmission line connecting a reception signal transmission path in a relay device adjacent to the base station and the base station, and a transmission line connecting reception signal transmission paths in adjacent relay devices among the plurality of relay devices are each a leaky coaxial cable. The wireless communication system according to any one of claims 1 to 6.

10. A relay device of a wireless communication system that receives a transmission wave from a mobile station as a reception wave, having a first duplexer, a second duplexer, a frequency converter, and a distributor, The first duplexer receives a local oscillation signal output from a local oscillator of a base station, outputs the local oscillation signal to the distributor, outputs a reception signal obtained by frequency-converting a reception wave signal by a reception wave from the frequency converter, and outputs a reception signal from a next-stage relay device from the second duplexer. The second duplexer receives a reception wave signal by a reception wave that receives a transmission wave from a mobile station as a reception wave, outputs the reception wave signal by the reception wave to the frequency converter, outputs the other local oscillation signal obtained by distributing the local oscillation signal by the distributor to a next-stage relay device, and outputs a reception signal from the next-stage relay device to the first duplexer. The frequency converter uses one local oscillation signal obtained by distributing the local oscillation signal by the distributor for a reception wave signal by a reception wave from the second duplexer, frequency-converts it to a reception signal having a frequency lower than the frequency of the reception wave signal by the reception wave, and outputs it to the first duplexer. A relay device of a wireless communication system.

11. The relay device of the wireless communication system according to claim 10, having a frequency multiplier that multiplies one of the local oscillation signals distributed from the distributor and outputs the multiplied signal to the frequency converter.

12. A relay device of a wireless communication system that receives a transmission wave from a mobile station as a reception wave, comprising a first duplexer, a second duplexer, a first frequency converter, a distributor, a third duplexer, a fourth duplexer, a second frequency converter, a fifth duplexer, and a sixth duplexer, The fifth duplexer receives a local oscillation signal output from a local oscillator of a base station and a transmission signal output from a transmitter of the base station, outputs the local oscillation signal to the distributor, outputs the transmission signal to the third duplexer, and outputs a reception signal from the first duplexer. The sixth duplexer receives a reception wave signal due to a reception wave that receives a transmission wave from a mobile station as a reception wave, outputs the reception wave signal due to the reception wave to the second duplexer, outputs a reception signal from a subsequent relay device to the second duplexer, outputs a second local oscillation signal obtained by distributing the local oscillation signal by the distributor to a subsequent relay device, outputs a transmission signal from the fourth duplexer to a subsequent relay device, and outputs a signal for a transmission wave from the fourth duplexer. The first duplexer outputs a reception signal obtained by frequency-converting a reception wave signal due to a reception wave from the frequency converter to the fifth duplexer, and outputs a reception signal from a subsequent relay device from the second duplexer to the fifth duplexer. The second duplexer outputs a reception wave signal due to a reception wave from the sixth duplexer to the frequency converter, and outputs a reception signal from a subsequent relay device from the sixth duplexer to the first duplexer. The first frequency converter frequency-converts a reception wave signal due to a reception wave from the second duplexer into a reception signal having a frequency lower than the frequency of the reception wave signal due to the reception wave, using a first local oscillation signal obtained by distributing the local oscillation signal by the distributor, and outputs the converted signal to the first duplexer. The second frequency converter frequency-converts a transmission signal from the third duplexer into a signal for a transmission wave having a frequency higher than the frequency of the transmission signal, using a third local oscillation signal obtained by distributing the local oscillation signal by the distributor, and outputs the converted signal to the sixth duplexer. A relay device of a wireless communication system.

13. a first frequency multiplier that multiplies the second local oscillation signal distributed from the distributor and outputs the multiplied signal to the first frequency converter; The relay device of the wireless communication system according to claim 12, comprising a second frequency multiplier that multiplies the third local oscillation signal distributed from the distributor and outputs the multiplied signal to the second frequency converter.

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