JP5608894B2 - Mobile communication system - Google Patents

Description

  The present invention relates to a mobile communication system including a plurality of relay stations arranged at predetermined distances of a communication path arranged along a movement path of a mobile station, and a base station capable of communication connection with the relay station. .

  Conventionally, various types of railway communication systems have been proposed that show communication between inside and outside of a train moving on a track (see, for example, Patent Documents 1-3). In such a communication system, communication is performed by laying a communication path along a track and connecting the communication path and a train traveling on the track by a wireless communication line. This communication path is configured by a leaky coaxial cable (hereinafter referred to as “LCX”). That is, for example, by laying a plurality of LCXs in parallel with the track via relay stations installed at predetermined distances (for example, 1.5 km), a communication path along the train track is configured.

  In the communication system using LCX as described above, the thermal noise generated during the amplification process at the relay station is superimposed on each relay station, so the number of relay stations connected to one radio base station is limited. Will receive. In order to suppress such an increase in thermal noise, for example, in Patent Document 1, a communication path is configured by LCX and an optical fiber, and from each relay station toward the line (the grading directions are alternated). In addition, a communication system is disclosed in which LCX is laid to increase the relay distance between relay stations and reduce the number of relays. Here, the grading direction refers to a direction away from the feeding point of power to the LCX.

JP-A-8-11719 JP 2002-118870 A JP 2004-056617 A

  However, in the communication system of Patent Document 1 described above, although it is possible to suppress an increase in thermal noise as compared with the case where the communication path is configured only by LCX, the heat generated by the photoelectric conversion processing executed at the relay station. Since noise is superimposed at each relay station, there is a problem that the number of relay stations connected to one radio base station is still limited.

  Further, in the communication system of Patent Document 1 described above, LCXs are laid in both directions from each relay station, so that the LCX grading direction between the relay stations is transmitted from the preceding relay station. A propagation delay difference of about 3.0 km occurs between the power to be transmitted and the power transmitted from the next relay station. For this reason, it is necessary to separately add a timing compensation function such as a delay memory for delay compensation (for example, the “timing compensation function” of Patent Document 2), which increases the deterioration factor of communication quality.

  Furthermore, in the communication system of Patent Document 1 described above, the transmission quality in each span (between the base station or the relay station and the relay station) in the communication path is not uniform, and the more relays the relay station increases, the more wireless There has been a problem that transmission quality in a span away from the base station is greatly deteriorated.

  The present invention solves the above-described problems and improves the transmission quality even when the number of relay stations connectable to one radio base station is increased in a mobile communication system that performs communication with a mobile station such as a train. It aims to be able to maintain high quality.

  A mobile communication system of the present invention includes a plurality of relay stations arranged at predetermined distances of a communication path arranged along a movement path of a mobile station, and a base station capable of communication connection with the relay station. A mobile communication system, comprising an optical signal line for individually connecting the base station to each of the plurality of relay stations, and a photoelectric converter for mutually converting an optical signal and an electric signal provided on the base station side Is the optical signal line transmission loss to the corresponding relay station, the insertion loss of the optical signal distributor used for the corresponding relay station, and the correction fixed provided for the output to each relay station Distribute the optical signal output to the relay station for output to each relay station so that the total loss, including the fixed fixed attenuation that indicates the attenuation of the attenuator, is less than the allowable loss value for all relay stations Including a non-uniformly lossy optical signal distributor configured to To.

  With the above configuration, even when the number of relay stations connectable to one radio base station is increased, the transmission quality can be maintained at a high quality.

  The non-uniform loss optical signal distributor is configured by connecting a plurality of optical signal distributors that distribute optical signals, and among the plurality of optical signal distributors, an optical signal distributed by a preceding optical signal distributor is provided. An optical signal to be output to the relay station side is distributed to each relay station by partially distributing the optical signal for output to one of the relay stations and further distributing another part by the optical signal distributor in the subsequent stage. It may be configured to distribute for the output.

  Further, the mobile communication system of the present invention includes a plurality of relay stations arranged at predetermined distances of a communication path arranged along the movement path of the mobile station, and a base station capable of communication connection with the relay station. A mobile communication system comprising: an optical signal line that connects each of the base station and the plurality of relay stations, each of the plurality of relay stations on a lower side as viewed from the base station; When a relay station exists, the optical signal line transmission loss to the lower relay station, the insertion loss of the optical signal distributor used for the corresponding relay station, and the output to each relay station The optical signal is transmitted to the lower relay station so that the total loss combined with the correction fixed attenuation amount indicating the attenuation amount of the correction fixed attenuator provided in the lower relay station is equal to or less than an allowable loss value for the lower relay station. Non-uniform loss optical signal distributor configured to distribute for output to An optical signal obtained by combining an optical signal from the lower relay station and an optical signal converted from the electric signal transmitted from the mobile station when there is a lower relay station when viewed from the base station. And a non-uniform optical multiplexer that transmits the signal to a higher-order relay station or the base station.

  The non-uniform optical multiplexer is an optical signal obtained by converting an optical signal from the lower relay station and an electrical signal transmitted from the mobile station when there is a lower relay station when viewed from the base station. May be configured to transmit an optical signal synthesized by wavelength multiplexing.

  The number of cores of the optical signal line is provided according to the moving path of the mobile station for communication on the downlink side going from the base station to the lower relay station and the uplink side going to the base station side. Each route of system 1 and system 2 is composed of a total of four cores, and the non-uniform optical multiplexer is connected to the lower side when there is a lower side relay station when viewed from the base station. An optical signal synthesized by time-division multiplexing an optical signal from a relay station and an optical signal obtained by converting an electric signal transmitted from the mobile station may be transmitted.

  The number of cores of the optical signal line is provided according to the moving path of the mobile station for communication on the downlink side going from the base station to the lower relay station and the uplink side going to the base station side. Each route of 1 route and 2 route is composed of a total of 2 wires, and each of the plurality of relay stations communicates with the base station side or another relay station using wavelength multiplexed signals. In order to perform the wavelength division multiplexing of the downlink side signal and the uplink side signal and wavelength separation of the downlink side signal and the uplink side signal, an optical wavelength separator for each of the 1 system and 2 system is provided. You may be set as the structure each provided about a route.

  The combination of the electrical / optical signal converter and the optical / electrical signal converter provided in the base station and the plurality of relay stations may be a pair between each station.

  According to the present invention, even when the number of relay stations connectable to one radio base station is increased, the transmission quality can be maintained at a high quality.

It is a signal system block diagram which shows the structural example of the mobile communication system in the 1st Embodiment of this invention. It is a block diagram which shows the example of a structure of the radio base station and photoelectric converter in the 1st Embodiment of this invention. It is a block diagram which shows the example of a structure of the relay station in the 1st Embodiment of this invention. It is explanatory drawing which shows the example of a structure of a nonuniform loss light divider | distributor. It is explanatory drawing which shows the specific example of a structure (distribution ratio and insertion loss) of three types of nonuniform loss 1: 2 divider | distributors. It is an optical section loss figure. It is an optical section loss figure. It is a signal system block diagram which shows the structural example of the mobile communication system in the 2nd Embodiment of this invention. It is a block diagram which shows the example of a structure of the radio base station and photoelectric converter in the 2nd Embodiment of this invention. It is a block diagram which shows the example of a structure of the relay station in the 2nd Embodiment of this invention. It is a signal system block diagram which shows the structural example of the mobile communication system in the 3rd Embodiment of this invention. It is a block diagram which shows the example of a structure of the radio base station and photoelectric converter in the 3rd Embodiment of this invention. It is a block diagram which shows the example of a structure of the relay station in the 3rd Embodiment of this invention. It is a signal system block diagram which shows the structural example of the mobile communication system in the 4th Embodiment of this invention. It is a block diagram which shows the example of a structure of the radio base station and photoelectric converter in the 4th Embodiment of this invention. It is a block diagram which shows the example of a structure of the relay station in the 4th Embodiment of this invention.

  Hereinafter, embodiments of the present invention will be described with reference to the drawings.

[First Embodiment]
FIG. 1 is a signal system block diagram showing a configuration example of a mobile communication system 100 according to the first embodiment of the present invention.

  As shown in FIG. 1, a mobile communication system 100 includes a radio base station 102 connected to a communication network such as the Internet, a photoelectric converter 402 that mutually converts an optical signal and an electric signal, and a photoelectric converter 402. The relay station 401 (n) [in this example, n = 1 to 20] connected via the optical fibers 401up and 401dn, and the grading direction is one direction along the line, and 20 spans (in this example, 1 span length = about 1.5 km) and LCX 105a. As shown in FIG. 1, the mobile communication system 100 has one relay station 401 (n) for each span, and one span LCX 105a is laid in the same direction from each relay station 401 (n). Has been. In this example, under one radio base station 102, there is a zone (in this example, the zone length = about 30 km) constituted by 20 spans of the LCX 105a laid in one direction. FIG. 1 also shows a wireless mobile station 106 that is a train or the like that moves on the track.

  In the mobile communication system 100, as shown in FIG. 1, any of the relay stations 401 (n) is electrically connected to the base point of the LCX 105a in each span.

  As shown in FIG. 1, each relay station 401 (n) has a function of mutually converting an electrical signal transmitted and received by the radio base station 102 and an optical signal transmitted by the optical fibers 401up and 401dn. Is directly connected to the optical device 402 through four-core optical fibers 401up and 401dn. Therefore, when 20 relay stations 401 (n) are used as in this example, the required number of fiber cores is 80 cores [= 2 cores / route × 2 routes (1 route and 2 route shown in FIG. 1). 2 routes) × number of relay stations = 2 × 2 × 20].

  As shown in FIG. 1, the photoelectric converter 402 connected to the radio base station 102 and each relay station 401 (n) have a “star” connection form via optical fibers 401up and 401dn. . Therefore, the optical fiber lengths of the optical fibers 401up and 401dn differ depending on the relay stations 401 (n) to be connected, and as the span of the relay station 401 (1) closest to the photoelectric converter 402 is increased by one span. It becomes longer by about 1.5km.

  In this example, the downlink signal (DL) from the radio base station 102 to the radio mobile station 106 is broadcast to all the radio mobile stations 106 in the zone, and the radio mobile station 106 is directed to the radio base station 102. The uplink signal (UL) is premised on a communication access method that is transmitted “burstly” when communication is required.

  FIG. 2 is a block diagram showing an example of the configuration of the radio base station 102 and the photoelectric converter 402 in the first embodiment of the present invention. FIG. 3 is a block diagram illustrating an example of the configuration of the relay station 401 (n) according to the first embodiment of this invention.

  In FIG. 2, a downlink electrical signal 402dn (s) input from the radio base station 102 to the photoelectric converter 402 is distributed to the two routes of the first and second systems by the electric distributor 402h, and then in each route. It is input to the EO converter 402b. The downlink optical signal 402dn converted from an electric signal to an optical signal by the EO converter 402d is input to the non-uniform loss optical distributor 402d and is transmitted to each relay station 401 (n) [in this example, n = 1 to 20]. Is distributed to the downlink optical signal 402dn (n) toward the integer], and is output via the correction fixed attenuator 402t (n) corresponding to each port [in this example, n = 1 to 20]. The

  As shown in FIG. 3, the downlink optical signal 402dn (n) transmitted from the two routes is input to each repeater 401 (n) via the optical fiber 401dn, and each repeater 401 (n) is provided. The OE converter 401c restores the electric signal.

  In general, the optical output level of the EO converter 402b and the optical input level of the OE converter 401c are limited in the input / output range. Further, this level difference becomes an allowable transmission loss in the optical transmission section. Here, for simplicity of explanation, it is assumed that the output level of the EO converter 402b is +10 dBm, the minimum reception input level of the OE converter 401c is −20 dBm, and the maximum allowable reception level is −15 dBm. Therefore, the maximum allowable loss between the EO converter 402b and the OE converter 401c is assumed to be 30 dB here.

  In FIG. 2, when the output of the EO converter 402b is distributed to 20 routes by the non-uniform loss optical distributor 402d, if “equal distribution” is simply performed, the insertion loss to each port becomes equal to about 13 dB. In this example, the non-uniform loss optical distributor 402d is realized by a non-uniform loss type distributor 10a, 10b, 10c as shown in FIG.

  FIG. 5 is an explanatory diagram showing a specific example of the configuration (distribution ratio and insertion loss) of the above three types of non-uniform loss distributors. FIG. 5A is an explanatory diagram showing a specific example of the distributor 10a of the type 10a in the table of FIG. 5D. FIG. 5B is an explanatory diagram showing a specific example of the type 10b distributor 10b in the table of FIG. 5D. FIG. 5C is an explanatory diagram showing a specific example of the type 10c distributor 10c in the table of FIG. 5D.

  For example, when a signal is input to the input port 10a (in), the distributor 10a illustrated in FIG. 5A outputs a signal to the drop-side output port 10a (x) with a power distribution ratio of 1/40. The signal is output to the relay side output port 10a (y) at 39/40.

  For example, when a signal is input to the input port 10b (in), the distributor 10b illustrated in FIG. 5B outputs a signal to the drop-side output port 10b (x) with a power distribution ratio of 1/20. The signal is output to the relay side output port 10b (y) at 19/20.

  For example, when a signal is input to the input port 10c (in), the distributor 10c illustrated in FIG. 5C outputs a signal to the drop-side output port 10c (x) with a power distribution ratio of 1/2. The signal is output to the relay side output port 10c (y) at 1/2.

  The power distribution ratio of each of the distributors 10a to 10c is not necessarily the numerical value shown in FIG. 5D, but as a procedure for configuring the nonuniform loss optical distributor 402d, first, it is assigned to each output port. A distributor 10a having a large distribution ratio difference is used on the young port number side, a distributor 10b having a medium distribution ratio difference is used on the middle port number, and the distribution ratio difference is smallest on the last port number stage. A distributor 10c is used. In this example, the nonuniform loss optical distributor 402d is provided with 20 output ports of port numbers 1-20.

  In the example shown in FIG. 4, the three types of distributors 10 a to 10 c are configured, but four types may be used, and this distribution ratio is not necessarily required.

Here, a specific example of the procedure for determining the configuration of the non-uniform loss optical distributor 402d by the distributors 10a to 10c will be described with reference to the optical section loss diagram shown in FIG.
First, the optical fiber transmission loss up to each relay station 401 (n) is graphed (thick solid arrow 20 in FIG. 6).
Here, the transmission loss of the optical repeater fiber is 1 dB / span. (0.3 dB / km x 1.5 km + 4 connector connection loss 5.5 dB = 1 dB)
Next, the distributors 10a to 10c are sequentially assigned from the lowest numbered port (1), and [optical fiber transmission loss + distributor insertion loss (drop side)] is calculated for each port. The total loss is 30 dB. The type of the distributor is sequentially selected within a range not exceeding (10a → 10b → 10c). Here, the total loss 30 dB is determined as the maximum allowable loss between the EO converter 402b and the OE converter 401c. In FIG. 6, the distributor insertion loss (drop side) by the distributors 10 a to 10 c is indicated by a dotted arrow 30.
The distributor 10a is assigned in order from the port (1), and the total loss of [optical fiber transmission loss + distributor insertion loss (drop side)] exceeds 30 dB (example shown in FIGS. 4 and 6). Then, the distributor 10b is assigned from the port (14), and the total loss of [optical fiber transmission loss + distributor insertion loss (drop side)] exceeds 30 dB (FIGS. 4 and 6). In the example shown in FIG. 4, the distributor 10c is assigned from the port (18). In FIG. 6, the solid line arrow 20 and the dotted line arrow 30 are graphed so that it can be easily grasped that the total loss of [optical fiber transmission loss + distributor insertion loss (drop side)] does not exceed 30 dB. Yes.

  As described above, the distributor type (specification) corresponding to each port number is determined, and the detailed configuration of the non-uniform loss optical distributor 402d shown in FIG. 4 is determined by the daisy chain configuration of the three types of distributors 10a to 10c. can do. Moreover, the attenuation amount of the correction fixed attenuator 402t (n) corresponding to each port in FIG. 2 can be determined from the thin solid arrow 40 shown in FIG. The value corresponding to the length of the thin solid arrow 40 is calculated from the maximum allowable loss (30 dB in this example) between the EO converter 402b and the OE converter 401c, [optical fiber transmission loss + distributor insertion loss (drop Side)]] is subtracted from the total loss. Therefore, for example, the value of the corrected fixed attenuation amount of the fixed attenuator 402t (n) of each port may be determined so as to be a value within the range 50 (= 25 dB or more and 30 dB or less) shown in FIG.

  As described above, the configuration of the non-uniform loss optical splitter 402d on the downlink side and the configuration of the correction fixed attenuation amount of the correction fixed attenuator 402t (n) in the base station configuration of FIG. 2 can be determined.

  In the configuration of the uplink side in the base station configuration of FIG. 2, the input / output conditions of the uplink side EO converter 401b of FIG. 3 and the uplink side OE converter 402c of FIG. Since each port is connected with an optical fiber, the corrected fixed attenuation amount of the correction attenuator 402r (n) on the uplink side in FIG. The value of can be determined. That is, the attenuation amount of the correction fixed attenuator 402r (n) corresponding to each port in the base station configuration of FIG. 2 can be determined from the thin solid arrow 40 shown in FIG. The value corresponding to the length of the thin solid arrow 40 is determined from the maximum allowable loss (30 dB in this example) between the EO converter 401b and the OE converter 402c, and the optical fiber transmission loss (thick solid arrow 20 in FIG. 7). ) Is subtracted. Accordingly, the fixed attenuation of each port so that the value at which the tip of the thin solid arrow 40 shown in FIG. 7 is located is a value within a predetermined range (for example, 25 dB or more and 30 dB or less) in FIG. The value of the corrected fixed attenuation amount of the device 402r (n) may be determined.

  As described above, according to the first embodiment, the wireless base station 102 and each relay station 401 (n) are directly connected by the four-core optical fiber, and the loss on the downlink side is uneven. Since the distributor 402d is used, the optical transmission loss between the EO converter 402b and the OE converter 401c can be kept within a predetermined range and constant. Further, the pair of the EO converter 402b and the OE converter 401c is only one pair (times) for each relay station 401 (n), and within this optical loss section (the EO converter 402b and the OE converter 401c Since only optical passive elements are used in the middle), it is possible to prevent the active element in the optical section from affecting the signal quality to the lower relay station and to maintain high reliability. It becomes. Further, as apparent from the above-described embodiment in which there are 20 relay stations 401 (n) as an example, it is possible to handle 20 spans, and one radio base while maintaining high transmission quality. The number of relay stations that can be connected to the station 102 can be increased.

[Second Embodiment]
Next, a second embodiment of the present invention will be described with reference to the drawings. In addition, about the same structure as 1st Embodiment mentioned above, the same code | symbol is provided and the detailed description is abbreviate | omitted.

  FIG. 8 is a signal system block diagram illustrating a configuration example of the mobile communication system 200 according to the second embodiment of the present invention.

  As shown in FIG. 8, the mobile communication system 200 is connected to a radio base station 102, a photoelectric converter 502 that mutually converts an optical signal and an electrical signal, a photoelectric converter 502, and optical fibers 501up and 501dn. Relay station 501 (n) [in this example, an integer of n = 1 to 20] and the grading direction is one direction along the line and 20 spans (in this example, 1 span length = about 1.5 km) And LCX 105a installed in As shown in FIG. 8, the mobile communication system 200 is provided with one relay station 501 (n) for each span, and one span LCX 105a is laid in the same direction from each relay station 501 (n). Has been. In this example, similarly to the first embodiment described above, a zone composed of 20 spans of LCX 105a in which the grading direction is laid in one direction is subordinate to one radio base station 102 (in this example, Zone length = about 30 km).

  In the mobile communication system 200, as shown in FIG. 8, any of the relay stations 501 (n) is electrically connected to the base point of the LCX 105a in each span.

  Among the relay stations 501 (n), the most upstream relay station 501 (1) closest to the radio base station 102 side, as shown in FIG. 8, the electrical signal transmitted and received by the radio base station 102 and the optical fibers 501up and 501dn. Are connected directly to the photoelectric converter 502 having a function of mutually converting the optical signal transmitted through the optical fiber 501up and 501dn through two optical fibers 501up and 501dn.

  Also, as shown in FIG. 8, among the relay stations 501 (n), the relay stations 501 (2) to 501 (20) are each one upstream upstream relay station 501 close to the radio base station 102 side. (N-1) and a total of four cores are directly connected via two-core optical fibers 501up and 501dn.

  That is, the mobile communication system 200 of the present example has a configuration in which spans between the photoelectric converter 502 and each relay station 501 (n) are connected by two-core optical fibers 501up and 501dn (total of four cores). Yes.

  FIG. 9 is a block diagram illustrating an example of the configuration of the radio base station 102 and the photoelectric converter 502 according to the second embodiment of the present invention. FIG. 10 is a block diagram illustrating an example of a configuration of the relay station 501 (n) according to the second embodiment of the present invention. Note that the EO converter 502b and the OE converter 502c shown in FIGS. 9 and 10 are the same as the EO converter 402b and the OE converter 402c described above in terms of output level and input level. However, in this example, the EO converter 502b is an optical continuous carrier type EO converter (an EO converter that performs conversion processing of a carrier signal that is continuously transmitted instead of burst-like), and the OE converter 502c includes It is assumed that it is an optical continuous carrier type OE converter (an OE converter that performs conversion processing of a carrier signal that is transmitted continuously instead of in a burst manner).

First, the downlink side will be described.
The downlink signal transmitted from the radio base station 102 needs to be broadcast to all the radio mobile stations 106 in the zone. In FIG. 9, the downlink electrical signal 502dn (s) from the radio base station 102 to the radio mobile station 106 is distributed to the two routes of the system 1 route and the system 2 route by the electrical distributor 502h, and then the respective routes. The downlink optical signal 502dn (n) input to the EO converter 502b and converted into an optical signal is sent to the optical fiber 501dn.

  The downlink optical signal 502dn (n) is first input to the first-stage relay station 501 (1) closest to the radio base station 102 side. As shown in the relay station 501 (n) shown in FIG. 10, the downlink optical signal 501dn (n: n = 1) is input to the non-uniform loss optical distributor 501zt and distributed to the two routes as an optical signal. One of the distributed downlink optical signals 501dn (n + 1: n = 1) is sent to the second-stage relay station 501 (2) that is second closest to the radio base station 102 side, and a one-span repeater optical fiber It is transmitted via 501dn. Thereafter, the same operation is repeated for the relay station 501 (3) and subsequent nodes, and the downlink signal 501dn (n) is transmitted to the final 20th-stage relay station 501 (20).

  On the other hand, the downlink optical signal distributed to the other by the nonuniform loss optical distributor 501zt in FIG. 10 is radiated to the LCX 105a (n) connected to the relay station 501 (n) as shown in FIG. It is a signal to be. The distributed downlink optical signal is attenuated by passing through the correction optical fixed attenuator 501tt (n), and then restored to an electrical signal from the optical signal by the OE transformer 501c, and is routed through the route selection switch 501s. Later, the signal is amplified by the electric signal amplifier 501x, and then radiated from the LCX 105a (n) toward the wireless mobile station 106 via the distributor 501h and the transmission / reception signal separator / synthesizer 501a.

  The non-uniform loss optical distributor 501zt and the correction optical fixed attenuator 501tt (n) for the corresponding span have different types and fixed attenuation values depending on each relay station 501 (n). However, this selection determination procedure (method) can be determined by using the selection determination method described with reference to FIG. 6 and the like in the first embodiment described above as it is.

Next, the uplink side will be described.
Here, the transmission wavelength λn of the uplink-side EO converter 501b (n) in the relay station 501 (n) in FIG. 10 is different in each of the relay stations 501 (1) to 501 (20). .

  The uplink signal transmitted from the wireless mobile station 106 is input to the EO converter 501b (n) via the amplifier 501y as an electrical signal via the LCX 105a of the corresponding span, and is converted into an uplink optical signal. This uplink optical signal is input to the non-uniform loss optical multiplexer 501zr via the uplink fixed attenuator 501tr (n).

  As shown in FIG. 10, the non-uniform loss optical multiplexer 501zr includes an uplink optical signal input from the LCX 105a (n) to the relay station 501 (n) and an uplink light from the lower relay station 501 (n + 1). The signal 501up (n + 1) is multiplexed (wavelength multiplexed), and the multiplexed uplink optical signal 501up (n) is sent to the upper relay station 501 (n-1). Thereafter, the same operation is sequentially repeated after the upper relay station 501 (n−1) and transmitted to the radio base station 102 via the photoelectric converter 502.

  In the uplink system diagram of the base station configuration example of FIG. 9, the uplink optical signal 502upw is a wavelength multiplexed signal (λx: x = 1 to 20). This wavelength multiplexed signal is optical wavelength separated by the optical wavelength separator 502f (n), separated into uplink optical signals 502up (n) from the respective relay stations 501 (n), and input to the respective OE converters 502c. It is returned to the electric signal and transmitted to the radio base station 102.

  In FIG. 10, an uplink fixed attenuator 501tr (n) and an uplink nonuniform loss optical multiplexer 501zr are the same as the above-described downlink correction optical fixed attenuator 501tt (n) and nonuniform loss light. The same type as the distributor 501zt is used as it is.

  As described above, according to the second embodiment, the radio base station 102 and the most upstream relay station 501 (1) are directly connected by a total of four-core optical fibers, and each relay station 501 (n ) Are connected by a total of four optical fibers, so that the optical transmission loss between the EO converter 502b and the OE converter 501c is within a predetermined range as in the first embodiment. And can be constant. Further, the pair of the EO converter 502b and the OE converter 501c is only one pair (times) for each relay station 401 (n), and within this optical loss section (the EO converter 502b and the OE converter 501c Since only optical passive elements are used in the middle), it is possible to prevent the active element in the optical section from affecting the signal quality to the lower relay station and to maintain high reliability. It becomes.

  Furthermore, according to the second embodiment, the number of optical fiber cores used in one zone is between the photoelectric converter 502 and the relay station 501 (1), between the relay station 501 (n) and the relay station 501 ( Since each station between n + 1) and each station is configured with two cores (four cores in total), it is more economical than the first embodiment.

  That is, in the first embodiment, the number of optical fiber cores used per zone is as high as 80 cores, but in the second embodiment, the number of optical fiber cores is four, which is used. The number of optical fiber cores to be reduced can be reduced, and the construction cost of the system can be greatly reduced as compared with the first embodiment.

[Third Embodiment]
Next, a third embodiment of the present invention will be described with reference to the drawings. In addition, about the same structure as 2nd Embodiment mentioned above, the same code | symbol is provided and the detailed description is abbreviate | omitted.

  FIG. 11 is a signal system block diagram illustrating a configuration example of the mobile communication system 300 according to the third embodiment of the present invention.

  As illustrated in FIG. 11, the mobile communication system 300 includes a radio base station 102, a photoelectric converter 502 that mutually converts an optical signal and an electric signal, and a photoelectric converter 502, like the mobile communication system 200 described above. And the relay station 501 (n) [in this example, n = 1 to 20] connected through the optical fibers 501up and 501dn, and the grading direction is one direction along the line and 20 spans (in this example) 1 span length = about 1.5 km) and LCX 105a. As in the mobile communication system 200 described above, the mobile communication system 300 is provided with one relay station 501 (n) for each span, as shown in FIG. 11, and from each relay station 501 (n) in the same direction. A one-span LCX 105a is constructed. In this example, similarly to the first embodiment described above, a zone composed of 20 spans of LCX 105a in which the grading direction is laid in one direction is subordinate to one radio base station 102 (in this example, Zone length = about 30 km).

  Further, as shown in FIG. 11, in the mobile communication system 300, the connection configuration of the radio base station 102, the photoelectric converter 502, each relay station 501 (n), and the LCX 105a in each span is the same as the mobile communication system 200 described above. It is the same as.

  FIG. 12 is a block diagram showing an example of the configuration of the radio base station 102 and the photoelectric converter 502 in the third embodiment of the present invention. FIG. 13 is a block diagram illustrating an example of a configuration of the relay station 501 (n) according to the third embodiment of the present invention. The configuration and operation on the downlink side are the same as those in the second embodiment described above. Therefore, only the explanation on the uplink side will be given.

  The functional blocks constituting the relay station 501 (n) in FIG. 13 are the same as those shown in FIG. 10, but the uplink EO on which the uplink signal from the radio mobile station 106 is input as a “burst” signal. Regarding the converter 501f, the output optical signal 501up of the EO converter 501f is of a type in which the optical carrier signal is “burst” output in conjunction with the input burst signal.

  Therefore, assuming that the transmission wavelength (λn) of the EO converter 501f of this type is the same in any relay station 501 (n), the output of the non-uniform loss optical multiplexer 501zr is the lower relay station 501 (n + 1). ) And an optical signal multiplexed by time division multiplexing and sent to the higher-level relay station 501 (n-1) or the photoelectric converter 501. In the uplink side system in the photoelectric converter 502 of FIG. 12, the time division multiplexed uplink optical signal 502up at a single wavelength is restored from the optical signal to the electric signal by the OE converter 502e, and the radio base station 102 Will be received.

As described above, according to the third embodiment, the same effect as that of the second embodiment can be obtained, and a single wavelength that is time-division multiplexed on the uplink side without using wavelength multiplexing. Therefore, the configuration of the photoelectric converter 502 can be simplified, and the system construction cost can be further reduced.
That is, as compared with the second embodiment described above, the optical wavelength separator 502f (n) on the uplink side includes a plurality of OE converters 502c and a plurality of electric distributors 502h used for each of the two routes. There is no need, and the photoelectric converter 502 can have a simplified configuration including two OE converters 502e and the like that are used one by one for each of the two routes on the uplink side. Therefore, the system construction cost can be further reduced.

[Fourth Embodiment]
Next, a fourth embodiment of the present invention will be described with reference to the drawings. In addition, about the same structure as 3rd Embodiment mentioned above, the same code | symbol is provided and the detailed description is abbreviate | omitted.

  FIG. 14 is a signal system block diagram showing a configuration example of a mobile communication system 400 according to the fourth embodiment of the present invention.

  As shown in FIG. 14, the mobile communication system 400 is similar to the mobile communication system 300 described above, the radio base station 102, a photoelectric converter 502 that mutually converts an optical signal and an electric signal, and a photoelectric converter 502. And the relay station 501 (n) [in this example, n = 1 to 20] connected through the optical fibers 501up and 501dn, and the grading direction is one direction along the line and 20 spans (in this example) 1 span length = about 1.5 km) and LCX 105a. Similarly to the mobile communication system 300 described above, the mobile communication system 400 is provided with one relay station 501 (n) for each span as shown in FIG. 14, and each relay station 501 (n) is connected in the same direction. A one-span LCX 105a is constructed. In this example, similarly to the first embodiment described above, a zone composed of 20 spans of LCX 105a in which the grading direction is laid in one direction is subordinate to one radio base station 102 (in this example, Zone length = about 30 km).

  Among the relay stations 501 (n), the most upstream relay station 501 (1) closest to the radio base station 102 side, as shown in FIG. 14, the electrical signals transmitted and received by the radio base station 102 and optical fibers 501up and 501dn. Are connected directly to a photoelectric converter 502 having a function of mutually converting an optical signal transmitted between the optical signal and two optical fibers 501up and 501dn.

  Further, as shown in FIG. 14, among the relay stations 501 (n), the relay stations 501 (2) to 501 (20) are each one upstream upstream relay station 501 close to the radio base station 102 side. (N-1) and a total of two cores are directly connected via one-core optical fibers 501up and 501dn.

  That is, the mobile communication system 400 of this example has a configuration in which spans between the photoelectric converter 502 and the relay stations 501 (n) are connected by optical fibers 501up and 501dn (two cores in total) of one core. Yes.

  FIG. 15 is a block diagram showing an example of the configuration of the radio base station 102 and the photoelectric converter 502 in the fourth embodiment of the present invention. FIG. 16 is a block diagram illustrating an example of the configuration of the relay station 501 (n) according to the fourth embodiment of the present invention.

  As shown in the signal system block diagram of FIG. 15, in this example, in order to reduce the number of optical fiber cores, each span is realized with one optical fiber per one route and two routes per route (total of two cores). doing. In this case, the transmission wavelength (λ0) of the EO converter 502b on the downlink side in the photoelectric converter 502 shown in FIG. 15 and the transmission of the optical burst carrier type EO converter 501f of each relay station 501 (n) shown in FIG. Only two types of wavelengths (λ1) are set, and any station between the photoelectric converter 502 and the relay station 501 (1) and between the relay station 501 (n) and the relay station 501 (n + 1). In this case, it is only necessary to connect the optical fibers of one route (two cores in total) between the stations and perform wavelength division multiplexing transmission between each station using a downlink optical signal and an uplink optical signal.

  In this example, as shown in FIG. 15, the photoelectric converter 502 and each relay station 501 (n) are optical wavelength demultiplexers for wavelength-division-multiplexing downlink optical signals and uplink optical signals between the stations, respectively. The system has a configuration for each of the first and second routes. The photoelectric converter 502 is configured to have an optical wavelength separator for wavelength multiplexing or wavelength separation for processing the signal transmitted to and received from the relay station 501 (1) for each of the 1-system and 2-system routes. Yes. For each relay station 501 (n), an optical wavelength demultiplexer for wavelength multiplexing or wavelength separation to process signals transmitted to and received from the upper relay station 501 (n-1), and a lower relay station 501 (n + 1) and an optical wavelength separator for wavelength-multiplexing or wavelength-separation for processing signals transmitted and received are provided for each of the 1-system and 2-system routes.

  As described above, according to the fourth embodiment, the same effects as those of the third embodiment can be obtained, and in addition, the inter-station fiber can be realized with a single route core, and further the system. Can become more economical.

[effect]
As described above, in the embodiment of the present invention, a plurality of relays arranged at predetermined distances of a communication path (for example, LCX 105a) disposed along the movement path of a mobile station (for example, wireless mobile station 106). A mobile communication system 100 including a station 401 (n) and a base station (for example, the radio base station 102) that can be connected to the relay station 401 communicates the base station 102 to each of the relay stations 401 (n) The photoelectric converter 402 that includes optical signal lines (for example, optical fibers 401dn and 401up) that are individually connected to each other and that mutually converts an optical signal and an electrical signal provided on the base station 102 side corresponds to the corresponding relay station 401 (n). Optical signal line transmission loss up to, the insertion loss of the optical signal distributors 10a to 10c used for the corresponding relay station 401 (n), and the output pair to each relay station 401 (n) Relay station 401 so that the total loss combined with the correction fixed attenuation amount indicating the attenuation amount of correction fixed attenuator 402t (n) provided in is less than the allowable loss value for all relay stations 401 (n). The configuration including the non-uniform loss optical signal distributor 402d configured to distribute the optical signal output to the (n) side for output to each relay station 401 (n) makes it possible to provide one radio base station 102. Even if the number of relay stations 401 (n) that can be connected to is increased, the transmission quality can be kept high.

  In the above-described embodiment, the non-uniform loss optical signal distributor 402d is configured by connecting a plurality of optical signal distributors 10a to 10c that distribute optical signals. A non-uniform loss optical signal distributor 402d having a simple configuration in which the devices 10a to 10c are simply connected and the total loss is accurately equal to or less than the permissible loss value for all the relay stations 401 (n). Is possible.

  In the above-described embodiment, the optical signal distributed by the non-uniform loss optical signal distributor 402d by the preceding optical signal distributor (for example, the optical signal distributor 10a) among the plurality of optical signal distributors 10a to 10c. Are used as optical signals for output to any one of the relay stations 401 (n), and other parts are used as optical signal distributors in the subsequent stage (for example, optical signal distributors 10a of the same type different from those in the previous stage). Since the optical signal output to the relay station 401 (n) is distributed for output to each relay station 401 (n), the total loss can be easily and accurately distributed. It becomes possible to configure the non-uniform loss optical signal distributor 402d so that it becomes less than the allowable loss value for all relay stations 401 (n).

  In the embodiment of the present invention, a plurality of relay stations 501 (n) arranged at predetermined distances of a communication path (for example, LCX 105a) disposed along a movement path of a mobile station (for example, wireless mobile station 106). ) And a base station (for example, the radio base station 102) communicably connected to the relay station 501 (n), the mobile communication system 200, 300, 400 includes the base station 102 and a plurality of relay stations 501 (n). A plurality of relay stations 501 (n) are connected to each other when there is a relay station 501 (n + 1) on the lower side when viewed from the base station 102. Optical signal line transmission loss up to the relay station 501 (n + 1), distributor insertion loss of the optical signal distributors 10a to 10c used for the corresponding relay station 501 (n + 1), and each relay station 501 (n) Output to The optical signal is transmitted to the lower relay station so that the total loss combined with the correction fixed attenuation amount indicating the attenuation amount of the correction fixed attenuator 501tt provided is less than the allowable loss value for the lower relay station. When the non-uniform loss optical signal distributor 501zt configured to distribute the signal to the output to the base station 102 and the lower relay station 501 (n + 1) viewed from the base station 102 exist, the lower relay station 501 (n + 1) ) And an optical signal obtained by combining the optical signal converted from the electric signal transmitted from the mobile station 106 is transmitted to the upper relay station 501 (n-1) or the base station 102. With the configuration including the optical multiplexer 501zr, it is possible to maintain high transmission quality even when the number of relay stations 501 (n) that can be connected to one radio base station 102 is increased. There is an effect.

  Further, in the above-described embodiment, the non-uniform optical multiplexer 501zr receives the light from the lower relay station 501 (n + 1) when the lower relay station 501 (n + 1) is present when viewed from the base station 102. When the optical signal synthesized by combining the signal and the optical signal converted from the electric signal transmitted from the mobile station 106 by wavelength multiplexing is transmitted, the signal synthesized by wavelength multiplexing is transmitted to the upper side. It is possible to transmit to the relay station 501 (n−1) or the base station 102.

  In the above-described embodiment, the number of optical signal lines is moved for communication on the downlink side from the base station 102 toward the lower relay station 501 (n + 1) and the uplink side toward the base station 102. Each of the 1-system and 2-system 2 routes provided according to the movement path of the station 106 is configured with a total of 4 cores, and the non-uniform optical multiplexer 501zr is the lower side as viewed from the base station 102. When the relay station 501 (n + 1) is present, the optical signal from the lower relay station 501 (n + 1) and the optical signal converted from the electrical signal transmitted from the mobile station 106 are time-division multiplexed. When the combined optical signal is transmitted, the configuration of the photoelectric converter 502 can be simplified, and a system can be constructed at low cost.

  In the above-described embodiment, a configuration in which only one pair of OE converters and EO converters provided in the base station 102 and the plurality of relay stations 401 (n) and 501 (n) is provided between the stations. Therefore, it is possible to prevent the active element in the optical section from affecting the signal quality to the lower relay station, and it is possible to maintain high reliability.

  In the above-described embodiment, the number of optical signal lines is moved for communication on the downlink side from the base station 102 toward the lower relay station 501 (n + 1) and the uplink side toward the base station 102. Each route of the 1-system and 2-system 2 routes provided according to the movement route of the station 106 is configured by a total of 2 cores, and the plurality of relay stations 501 (n) are respectively connected to the base station 102 side. Or, wavelength-division of the downlink side signal and the uplink side signal or wavelength separation into the downlink side signal and the uplink side signal in order to communicate with other relay stations using wavelength multiplexed signals. If the optical wavelength separator (see FIG. 16) is provided for each of the 1-system and 2-system routes, the system can be constructed at a lower cost.

  In the above-described embodiment, a non-uniform loss optical splitter (for example, non-uniform loss optical splitter 501zt) and a non-uniform loss optical multiplexer (for example, non-uniform loss optical multiplexer 501zr) are used. , An EO / OE converter (for example, EO converter 502b, OE converter 502c) on the base station 102 side and an OE / EO converter (for example, EO converter 501b, OE) of each relay station (for example, relay station 501 (n)). The optical transmission loss between the converters 501c) can be set (designed) to be within a certain value, and as a result, the wireless mobile station 106 is located in any span. However, it is possible to ensure a certain level of communication quality.

  In the above-described embodiment, the EO / OE converter (for example, EO converter 502b, OE converter 502c) on the base station 102 side and the OE / EO converter of each relay station (for example, relay station 501 (n)). Between the EO converter 501b and the OE converter 501c (for example, a pair of (one-facing) EO-OE conversion), and the optical transmission loss is configured to be only passive elements, so that thermal noise is superimposed. In addition, the reliability design of a high-quality and high-stable system in which the fluctuation factor of the optical transmission loss is minimized can be designed independently for each span.

  Further, in the above-described embodiment, the uplink side uses the uplink optical signal 502up with a single wavelength that is time-division multiplexed without using wavelength multiplexing, and the radio base station 102 to the relay station 501 (1). When the optical fiber between each station between the relay station 501 (1) and the relay station 501 (20) is realized with a two-core configuration, the radio base station 102 side (specifically, The configuration of the photoelectric converter 502) can be greatly simplified, and the system construction cost can be reduced.

  In the above-described embodiment, the photoelectric converter 502 and each relay station 501 (n) each have one optical wavelength separator that wavelength-division-multiplexes the downlink optical signal and the uplink optical signal between the stations. A configuration is provided for each of the two routes, and the optical fibers between the radio base station 102 and the relay station 501 (1) and between the relay station 501 (1) and the relay station 501 (20) are routed. When it is realized with a single-core configuration, the system construction cost can be further reduced.

  In the above-described embodiment, an example in which the span length between relay stations is equal to 1.5 km is shown. However, the present invention can be applied even when the distance between the stations is not equal and random. . In the above-described embodiment, the number of relay stations has been described as 20. However, the present invention can be applied to the case where the number is 19 or less. The present invention can be applied as long as it is within the allowable transmission loss.

  The present invention is useful for maintaining high transmission quality even when the number of relay stations connectable to one radio base station is increased.

100 mobile communication system 102 radio base station 105a LCX
106 wireless mobile station 401 relay station 401dn optical fiber for downlink 401up optical fiber for uplink 402 photoelectric converter

Claims (7)

A mobile communication system comprising a plurality of relay stations arranged at predetermined distances of a communication path arranged along a movement path of a mobile station, and a base station capable of communication connection with the relay station,
An optical signal line for individually connecting the base station to each of the plurality of relay stations,
The photoelectric converter provided on the base station side that mutually converts an optical signal and an electrical signal includes an optical signal line transmission loss to the corresponding relay station, and an optical signal distributor used for the corresponding relay station. Non-uniform loss configured to distribute the optical signal output to the relay station for output to each relay station so that the total loss including the distributor insertion loss is less than the allowable loss value for all relay stations look including the optical signal distributor,
The non-uniform loss optical signal distributor is:
It is constituted by connecting a plurality of optical signal distributors that distribute optical signals,
Among the plurality of optical signal distributors, a part of the optical signal distributed by the preceding optical signal distributor is used as an optical signal for output to any one of the relay stations, and the other part is provided by the subsequent optical signal distributor. By further distributing, the optical signal output to the relay station side is distributed for output to each relay station,
In the plurality of optical signal distributors, the same kind of distributors are arranged in a range in which the total loss of the optical signal line transmission loss and the distributor insertion loss does not exceed the allowable loss value. Mobile communication system. The plurality of optical signal distributors allocate the first type of optical signal distributor from the port on the previous stage side, and the combined loss of the optical signal line transmission loss and the distributor insertion loss exceeds the allowable loss value. By assigning a second type of optical signal distributor different from the first type of optical signal distributor from a different port, a loss combining the optical signal line transmission loss and the insertion loss of the distributor 2. The mobile communication system according to claim 1, wherein the same type of distributor is arranged in a range that does not exceed the allowable loss value . A mobile communication system comprising a plurality of relay stations arranged at predetermined distances of a communication path arranged along a movement path of a mobile station, and a base station capable of communication connection with the relay station,
Including an optical signal line for connecting each of the base station and the plurality of relay stations,
Each of the plurality of relay stations is
When there is a lower relay station when viewed from the base station, the optical signal line transmission loss to the lower relay station and the insertion loss of the optical signal distributor used for the corresponding relay station A non-uniform loss optical signal distributor configured to distribute an optical signal for output to the lower relay station such that a loss combined with the lower relay station is less than an allowable loss value; ,
When there is a lower relay station when viewed from the base station, an optical signal obtained by combining the optical signal from the lower relay station and the optical signal converted from the electric signal transmitted from the mobile station a heterogeneous optical multiplexer to be transmitted to the side of the relay station or the base station seen including,
The non-uniform loss optical signal distributor is characterized in that the same type of distributor is arranged in a range in which the total loss of the optical signal line transmission loss and the distributor insertion loss does not exceed the allowable loss value. Mobile communication system. The non-uniform optical multiplexer is an optical signal obtained by converting an optical signal from the lower relay station and an electrical signal transmitted from the mobile station when there is a lower relay station when viewed from the base station. The mobile communication system according to claim 3, wherein a combined optical signal is transmitted by wavelength multiplexing. The number of cores of the optical signal line is provided according to the moving path of the mobile station for communication on the downlink side going from the base station to the lower relay station and the uplink side going to the base station side. Consists of a total of 4 cores, 2 cores for each of the 1 system and 2 system 2 routes.
The non-uniform optical multiplexer is an optical signal obtained by converting an optical signal from the lower relay station and an electrical signal transmitted from the mobile station when there is a lower relay station when viewed from the base station. The mobile communication system according to claim 3, wherein an optical signal synthesized by time-division multiplexing is transmitted. The number of cores of the optical signal line is provided according to the moving path of the mobile station for communication on the downlink side going from the base station to the lower relay station and the uplink side going to the base station side. Consists of a total of two cores, one core for each of the two routes of system 1 and system 2.
Each of the plurality of relay stations wavelength-multiplexes or downlinks a downlink side signal and an uplink side signal in order to perform communication using the wavelength multiplexed signal with the base station side or another relay station. The mobile communication system according to claim 3, further comprising an optical wavelength separator for wavelength-separating into a signal on the side and an uplink signal for each of the 1-system and 2-system routes. The combination of the electrical / optical signal converter and the optical / electrical signal converter provided in the base station and the plurality of relay stations is only one pair between the stations. The mobile communication system described.

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