Communication system and optical delay correcting method

Abstract

To provide a communication system that performs optical delay correction simultaneously at a plurality of locations within an area served by a single base station.SOLUTION: A communication system includes a plurality of first relay devices W connected to a base station 1 via a first optical fiber cable, and a plurality of second relay devices E connected to the base station 1 via a second optical fiber cable. The first relay device includes an optical delay correction unit that corrects the delay difference with an adjacent first relay device farther from the base station. The second relay device includes an optical delay correction unit that corrects the delay difference with an adjacent second relay device farther from the base station 1. The base station includes a first optical delay correction unit that corrects the delay difference with a closest first relay device, and a second optical delay correction unit that corrects the delay difference with a closest second relay device to the base station 1. The first optical delay correction unit and the second optical delay correction unit of the base station further correct the delay difference between the plurality of first relay devices and the plurality of second relay devices.SELECTED DRAWING: Figure 1

Description

[Technical field]

[0001] The present disclosure relates to a technique for correcting signal delay in a communication system by correcting optical delay due to optical cable length. [Background technology]

[0002] There is known an optical delay compensation device that compensates for signal delays in a communication system by compensating for optical delays caused by optical cable lengths. For example, Patent Document 1 discloses a wireless relay system in which an optical delay compensation device installed at a base station and a relay device are connected one-to-one via an optical fiber transmission line, and the optical delay compensation device compensates for transmission delays in upstream and downstream communications. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] JP 2004-236165 A Summary of the Invention [Problem to be solved by the invention]

[0004] In conventional communication systems, where a repeater converts an optical signal that has passed through an optical delay compensation device into a high-frequency electrical signal, amplifies it, and transmits it in the upstream and downstream directions, delay adjustment is performed by combining an optical delay compensation device on the base station side with an optical delay compensation unit on the repeater side. In this case, delay adjustment must be performed starting from the repeater at the farthest end of either the upstream or downstream direction of the area served by one base station. In addition, in communication systems that include multiple base stations, delay adjustment is also required between the areas served by each base station, and delay adjustment must be performed starting from the area served by the base station at the edge of the communication system.

[0005] The present disclosure has been made to solve the above problems, and aims to enable optical delay correction to be performed simultaneously at multiple locations within the area covered by a single base station. [Means for solving the problem]

[0006] A communication system according to the present disclosure includes a base station, a plurality of first relay devices connected to the base station via a first optical fiber cable, and a plurality of second relay devices connected to the base station via a second optical fiber cable, each of the first relay devices includes an optical delay correction unit that corrects a signal delay difference between the first relay device and an adjacent first relay device that is farther from the base station, each of the second relay devices includes an optical delay correction unit that corrects a signal delay difference between the second relay device and an adjacent second relay device that is farther from the base station, the base station includes a first optical delay correction unit that corrects a signal delay difference between the first relay device that is closest to the base station, and a second optical delay correction unit that corrects a signal delay difference between the second relay device that is closest to the base station, and the first optical delay correction unit and the second optical delay correction unit of the base station further correct the signal delay difference between the first relay devices and the second relay devices. Effect of the Invention

[0007] According to the present disclosure, it becomes possible to perform optical delay correction simultaneously at multiple locations within the area served by one base station. [Brief description of the drawings]

[0008] [Figure 1] FIG. 1 is a diagram showing a configuration of a communication system according to a first embodiment. [Diagram 2] FIG. 2 is a diagram showing a configuration of a base station according to the first embodiment. [Diagram 3] FIG. 2 is a diagram illustrating a configuration of a relay device according to the first embodiment. [Figure 4] 4 is a flowchart of optical delay correction according to the first embodiment. [Diagram 5] FIG. 11 is a diagram showing a configuration of a communication system according to a second embodiment. [Figure 6] 11 is a flowchart of optical delay correction according to the second embodiment. [Figure 7]11 is a flowchart of optical delay correction according to the second embodiment. [Figure 8] 11 is a flowchart of optical delay correction according to the second embodiment. [Figure 9] FIG. 11 is a diagram showing a configuration of a communication system according to a third embodiment. [Figure 10] 13 is a flowchart of optical delay correction according to the third embodiment. [Figure 11] 13 is a flowchart of optical delay correction according to the third embodiment. [Figure 12] 13 is a flowchart of optical delay correction according to the third embodiment. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0009] <Embodiment 1> Fig. 1 is a diagram showing a configuration of a communication system according to the first embodiment. As shown in Fig. 1, the communication system according to the first embodiment includes a base station 1, a plurality of relay devices 2 that relay communication between a mobile station (not shown) and the base station 1, an optical fiber cable 5 connected between the base station 1 and the plurality of relay devices 2, a coupler 3 that divides signals transmitted and received between the base station 1 and the plurality of relay devices 2 through the optical fiber cable 5 for each relay device 2, and a coaxial cable 4 for transmitting and receiving radio frequency (RF) signals. Here, a leaky coaxial (LCX) cable is used as the coaxial cable 4.

[0010] 1, base station A is shown as base station 1, and the area covered by base station A is defined as "zone A." Zone A is divided into two areas, area W and area E, and area W of zone A is defined as "zone AW," and area E of zone A is defined as "zone AE."

[0011] A plurality of relay devices 2 are installed in each of the zones AW and AE. The M relay devices 2, namely relay devices W(1), W(2), . . . , W(M-1), and W(M), belong to the zone AW. The N relay devices 2, namely relay devices E(1), E(2), . . . , E(N-1), and E(N), belong to the zone AE. The numbers in parentheses attached to the symbols W and E indicate the number of the relay device 2. In this embodiment, the numbers of the relay devices 2 are assigned in the order of 1, 2, 3, . . . in order from the side closer to the base station A. M and N are any positive integers, and there are no restrictions on their values. The distance from the base station A means the distance in the cable length direction of the optical fiber cable 5.

[0012] 2 is a configuration diagram of base station 1. Base station 1 includes an RF unit 1a, an E / O unit 1b, an optical delay correction unit 1c, an O / E unit 1d, an optical delay correction unit 1e, and an O / E unit 1f. The E / O unit 1b is an electrical-to-optical converter that converts an electrical signal into an optical signal. The O / E units 1d and 1f are optical-to-electrical converters that convert an optical signal into an electrical signal.

[0013] The optical delay correction unit 1c and the optical delay correction unit 1e are correctors that correct the optical propagation delay (also referred to as "optical delay") in zone A. The optical delay correction unit 1c is a first optical delay correction unit connected to the optical fiber cable 5 (first optical fiber cable) to which the repeater 2 (first repeater) in zone AE is connected. The optical delay correction unit 1e is a second optical delay correction unit connected to the optical fiber cable 5 (second optical fiber cable) to which the repeater 2 (second repeater) in zone AW is connected.

[0014] The correction of optical propagation delay performed by the optical delay correction unit 1c and the optical delay correction unit 1e can adjust the optical delay for three types of routes: (i) the route connected to the O / E unit, (ii) the route connected to the repeater device, and (iii) the route obtained by aggregating the route connected to the O / E unit and the route connected to the repeater device.

[0015] The RF unit 1a is a transceiver that transmits and receives digital signals. The RF unit 1a has a modulation function for converting a digital signal to be transmitted into radio waves, and a demodulation function for extracting a digital signal from a received radio wave. The RF unit 1a may further have a signal amplification function.

[0016] Fig. 3 is a configuration diagram of the repeater device 2. Fig. 3 shows, as an example, the configuration of the repeater device 2 as repeaters W(1) and E(1). The repeater device 2 includes an optical delay correction unit 2a, an O / E unit 2b, an E / O unit 2c, and an RF unit 2d.

[0017] The RF unit 2d is connected to the LCX cable 4. The O / E unit 2b, the E / O unit 2c, and the RF unit 2d have the same functions as the O / E unit, the E / O unit, and the RF unit of the base station 1, respectively. The optical delay correction unit 2a corrects the optical propagation delay between the repeater 2 having the assignment number that is one number larger than the assignment number of the repeater 2 itself, that is, corrects the optical propagation delay between the repeater 2 itself and the adjacent repeater 2 that is farther from the base station 1.

[0018] 4 is a flowchart showing a process of optical delay correction performed by the communication system according to the embodiment 1. Hereinafter, the optical delay correction performed by the communication system according to the embodiment 1 will be described with reference to the flowchart in FIG.

[0019] Step S1 is the initial state before optical delay correction. Optical delay correction is performed separately for the optical delay correction on the zone AE side shown in steps S10 to S18 and the optical delay correction on the zone AW side shown in steps S20 to S28. The optical delay correction on the zone AE side and the optical delay correction on the zone AW side may be performed simultaneously.

[0020] When performing optical delay correction on the zone AE side, the process transitions from step S1 to step S10, and optical delay correction on the zone AE side is started. In the following step S11, the affiliation number N of the repeater E(N) at the end farthest from the base station A is saved in the variable n. At this time, the repeater E(n) is set as the reference repeater.

[0021] Next, in step S12, the optical delay correction unit 2a of the repeater E(n-1) adjusts the delay difference in order to correct the signal delay difference (hereinafter simply referred to as the "delay difference") at the RF signal matching point between the reference repeater E(n) and the adjacent repeater E(n-1) closer to the base station 1. When this correction is completed, the variable n is decremented by 1 in step S13.

[0022] Next, in step S14, it is determined whether the reference relay device has become the relay device E(1) closest to the base station, i.e., whether the variable n is 1. If the reference relay device is not the relay device E(1), the process proceeds to step S15, where the delay difference between the relay device E(n) and the relay device E(n-1) is corrected by the optical delay correction unit 2a of the relay device E(n-1) in the same manner as in step S12. When this correction is completed, the variable n is decremented by 1 in step S16, and the process returns to step S14. Thus, steps S15 and S16 are repeated until the reference relay device becomes the relay device E(1).

[0023] If the reference repeater becomes the repeater E(1), the process proceeds to step S17. In step S17, the delay difference is adjusted by the optical delay correction unit 1c of the base station A in order to correct the delay difference at the RF signal matching point between the repeater E(1) and the base station A. This completes the optical delay correction for zone AE.

[0024] When the optical delay correction for zone AE is completed, in step S18, it is confirmed whether or not the optical delay correction for zone AW is completed. If the optical delay correction for zone AW is not completed, the process waits for its completion.

[0025] On the other hand, when optical delay correction is performed on the zone AW side, a transition is made from step S1 to step S20, and optical delay correction on the zone AW side shown in steps S20 to S28 is started. In steps S20 to S27, the same processing as in steps S10 to S17 described above is performed on the repeaters W(1) to W(M) in zone AW. That is, the repeaters E(1) to E(N) and the variable n in the explanation of steps S10 to S17 should be replaced with the repeaters W(1) to W(M) and the variable m. Therefore, the explanation of steps S20 to S27 is omitted.

[0026] When the optical delay correction for the zone AW is completed, in step S28, it is confirmed whether or not the optical delay correction for the zone AE is completed. If the optical delay correction for the zone AE is not completed, the process waits for its completion.

[0027] When both the optical delay correction on the zone AW side and the optical delay correction on the zone AE side are completed, in step S30, the delay difference between zone AW and zone AE is corrected by optical delay correction unit 1c or 1e of base station A. This completes the optical delay correction for zone A.

[0028] In this way, in the communication system according to the first embodiment, the area covered by one base station 1 is divided into two zones, and the delay difference in each zone is corrected by the optical delay correction unit 2a of the relay device 2, so that optical delay correction can be performed in parallel in the two zones. At this time, it is expected that a delay difference will occur at the boundary between the two zones, but this delay difference can be corrected by the optical delay correction unit 1c or the optical delay correction unit 1e of the base station 1. Therefore, according to the communication system according to the first embodiment, it is possible to simultaneously perform optical delay correction at multiple locations within the area covered by one base station. As a result, an effect is obtained in that the time required for optical delay correction can be shortened.

[0029] <Embodiment 2> In the first embodiment, an example has been shown in which the communication system has only one base station 1, but there may be a plurality of base stations 1. In the second embodiment, an example of a communication system having a plurality of base stations 1 will be shown.

[0030] Fig. 5 is a diagram showing a configuration of a communication system according to embodiment 1. In Fig. 5, elements similar to those shown in Figs. 1 to 3 are given the same reference numerals.

[0031] In FIG. 5, two base stations A and B are shown as base station 1. The area covered by base station A is defined as "zone A." Zone A is divided into two areas, W and E, with the W area of ​​zone A being defined as "zone AW" and the E area of ​​zone A being defined as "zone AE." The area covered by base station B is defined as "zone B." Zone B is divided into two areas, W and E, with the W area of ​​zone B being defined as "zone BW" and the E area of ​​zone B being defined as "zone BE."

[0032] The configuration of zone A is the same as that of embodiment 1. In zone B, multiple relay devices 2 are installed in zone BW and zone BE. K relay devices 2, namely relay devices W(1), W(2), . . . , W(K-1), and W(K), belong to zone BW. J relay devices 2, namely relay devices E(1), E(2), . . . , E(J-1), and E(J), belong to zone BE. The number in parentheses attached to the symbol W or E indicates the number of the relay device 2. The numbers of the relay devices 2 are assigned in the order of 1, 2, 3, . . . in order from the side closest to base station B. K and J are any positive integers, and there are no restrictions on their values.

[0033] 6 to 8 are flowcharts showing the process of optical delay correction performed by the communication system according to the embodiment 2. Hereinafter, the optical delay correction performed by the communication system according to the embodiment 2 will be described with reference to the flowcharts of FIGS.

[0034] Steps S1, S10 to S18, S20 to S28, and S30 shown in Fig. 6 are the same as those in Fig. 4. That is, the process of optical delay correction for repeaters W(1) to W(N) and repeaters E(1) to E(M) in zone A is the same as that in the first embodiment.

[0035] 7, processes similar to those in steps S1, S10 to S18, S20 to S28, and S30 are performed on relay devices W(1) to W(K) and relay devices E(1) to E(J) in zone B. That is, relay devices E(1) to E(N) and variable n, and relay devices W(1) to W(M) and variable m in steps S1, S10 to S18, S20 to S28, and S30 should be replaced with relay devices E(1) to E(J) and variable j, and relay devices W(1) to W(K) and variable k.

[0036] The optical delay correction on the zone A side (FIG. 6) and the optical delay correction on the zone B side (FIG. 7) are performed separately, or may be performed simultaneously.

[0037] When the optical delay correction on the zone A side is completed, in step S31, it is confirmed whether the optical delay correction on the zone B side is completed or not. If the optical delay correction on the zone B side is not completed, the process waits for its completion.

[0038] When the optical delay correction for zone B is completed, in step S71, it is confirmed whether or not the optical delay correction for zone A is completed. If the optical delay correction for zone A is not completed, the process waits for its completion.

[0039] When both the optical delay correction on the zone A side and the optical delay correction on the zone B side are completed, in step S80, the delay difference between zone A and zone B is corrected by the optical delay correction unit 1c or 1e of the reference base station 1 (specific base station) of base station A and base station B. In other words, the optical delay correction unit 1c or 1e of the reference base station 1 corrects the phase difference between the reference base station 1 and another base station 1. This completes the optical delay correction for zone A and zone B.

[0040] In this way, in the communication system according to the second embodiment, when there are multiple base stations 1, it is possible to perform optical delay correction simultaneously at multiple locations within the areas covered by each base station. Note that, although the second embodiment shows an example in which there are two base stations 1, the number of base stations 1 may be three or more.

[0041] <Embodiment 3> In the first and second embodiments, an example is shown in which one optical fiber cable 5 is connected to each of the optical delay correction unit 1c and the optical delay correction unit 1e of the base station 1, but a plurality of optical fiber cables 5 may be connected to the optical delay correction unit 1c and the optical delay correction unit 1e. In the third embodiment, an example is shown in which two optical fiber cables 5 are connected to each of the optical delay correction unit 1c and the optical delay correction unit 1e.

[0042] Fig. 9 is a diagram showing a configuration of a communication system according to embodiment 3. In Fig. 9, the same elements as those shown in Figs. 1 to 3 are given the same reference numerals.

[0043] 9, base station A is shown as the base station 1, and similarly to the first embodiment, the area covered by base station A is defined as "zone A", the W area of ​​zone A as "zone AW", and the E area of ​​zone A as "zone AE". Furthermore, M relay devices 2, namely relay devices W(1), W(2), . . . , W(M-1), and W(M), belong to zone AW, and N relay devices 2, namely relay devices E(1), E(2), . . . , E(N-1), and E(N), belong to zone AE.

[0044] However, in the third embodiment, among the relay devices 2 belonging to the zone AW, the optical fiber cables 5 connected to the relay devices W(1), W(2), . . ., W(Mp-2), and W(Mp-1) are different from the optical fiber cables 5 connected to the relay devices W(Mp), W(M-p+1), . . ., W(M-1), and W(M), and these two optical fiber cables 5 are connected to the optical delay correction unit 1e of the base station 1. Also, among the relay devices 2 belonging to the zone AE, the optical fiber cables 5 connected to the relay devices E(1), E(2), . . ., E(Mq-2), and E(Mq-1) are different from the optical fiber cables 5 connected to the relay devices E(Mq), E(M-q+1), . . ., E(M-1), and E(M), and these two optical fiber cables 5 are connected to the optical delay correction unit 1c of the base station 1.

[0045] Here, within the zone AW, the area to which the relay devices W(Mp) to W(M) belong is defined as "zone AW1," and the area to which the relay devices W(1) to W(Mp-1) belong is defined as "zone AW2." Additionally, within the zone AE, the area to which the relay devices E(Mq) to E(M) belong is defined as "zone AE1," and the area to which the relay devices E(1) to E(Mq-1) belong is defined as "zone AE2."

[0046] In addition, the number of optical fiber cables 5 connected from the base station 1 to multiple relay devices 2 in zone AW or zone AE is not limited to two, and can be increased up to a maximum number that is one-to-one with the relay device 2 (i.e., N or M).

[0047] 10 to 12 are flowcharts showing the process of optical delay correction performed by the communication system according to embodiment 3. Hereinafter, the optical delay correction performed by the communication system according to embodiment 2 will be described with reference to the flowcharts of FIGS.

[0048] In Fig. 10, step SS1 is the initial state before optical delay correction for zones AW1 and AW2. In steps SS10 to SS16, the same processes as steps S10 to S16 in Fig. 4 are performed for the repeaters W(Mp) to W(M) belonging to zone AW1, and when these processes are completed, optical delay correction on the zone AW1 side is completed (step SS17). When optical delay correction on the zone AW1 side is completed, in step SS18, it is confirmed whether optical delay correction on the zone AW2 side is completed or not. If optical delay correction on the zone AW2 side is not completed, completion of this correction is awaited.

[0049] In steps SS20 to SS27, the same processes as steps S10 to S17 in Fig. 4 are performed on the repeaters W(1) to W(Mp-1) belonging to zone AW2, and when these processes are completed, optical delay correction on the zone AW2 side is completed. When optical delay correction on the zone AW2 side is completed, in step SS28, it is confirmed whether optical delay correction on the zone AW1 side is completed or not. If optical delay correction on the zone AW1 side is not completed, the process waits for its completion.

[0050] The optical delay correction on the zone AW1 side and the optical delay correction on the zone AW2 side are performed separately, or both may be performed simultaneously.

[0051] When optical delay correction on both the zone AW1 side and the zone AW2 side is completed, in step SS30, the delay difference between zone AW1 and zone AW2 is corrected by optical delay correction unit 1e of base station A. This corrects the phase difference between the optical fiber cable 5 in zone AW1 and the optical fiber cable 5 in zone AW2, and optical delay correction for zones AW1 and AW2 is completed.

[0052] In Fig. 11, step SS41 is the initial state before optical delay correction for zones AE1 and AE2. In steps SS50 to SS56, the same processes as steps S10 to S16 in Fig. 4 are performed for repeaters E(Nq) to E(N) belonging to zone AE1, and when these processes are completed, optical delay correction on the zone AE1 side is completed (step SS57). When optical delay correction on the zone AE1 side is completed, in step SS58, it is confirmed whether optical delay correction on the zone AE2 side is completed or not. If optical delay correction on the zone AE2 side is not completed, completion of this correction is awaited.

[0053] In steps SS60 to SS67, the same processes as steps S10 to S17 in Fig. 4 are performed on repeaters E(1) to E(Nq-1) belonging to zone AE2, and when these processes are completed, optical delay correction on the zone AE2 side is completed. When optical delay correction on the zone AE2 side is completed, in step SS68, it is confirmed whether optical delay correction on the zone AE1 side is completed or not. If optical delay correction on the zone AE1 side is not completed, completion of this correction is awaited.

[0054] The optical delay correction on the zone AE1 side and the optical delay correction on the zone AE2 side are performed separately, or both may be performed simultaneously.

[0055] When the optical delay correction on both the zone AE1 side and the zone AE2 side is completed, in step SS70, the delay difference between zone AE1 and zone AE2 is corrected by the optical delay correction unit 1c of base station A. As a result, the phase difference between the optical fiber cable 5 of zone AE1 and the optical fiber cable 5 of zone AE2 is corrected, and the optical delay correction of zones AE1 and AE2 is completed.

[0056] When the optical delay correction on the zones AW1 and AW2 side is completed, in step SS31, it is confirmed whether the optical delay correction on the zones AE1 and AE2 side is completed or not. If the optical delay correction on the zones AE1 and AE2 side is not completed, the completion of the correction is awaited.

[0057] When the optical delay correction for zones AE1 and AE2 is completed, in step SS71, it is confirmed whether the optical delay correction for zones AW1 and AW2 is completed or not. If the optical delay correction for zones AW1 and AW2 is not completed, the process waits for its completion.

[0058] When optical delay correction on both the side of zones AW1 and AW2 and the side of zones AE1 and AE2 is completed, in step SS80, the delay difference between zones AW2 and AE2 is corrected by optical delay correction unit 1c or 1e of base station A. This corrects the phase difference between zones AW1 and AW2 and zones AE1 and AE2, and completes optical delay correction for zone A.

[0059] In this way, in the communication system of embodiment 3, multiple optical fiber cables are connected to the optical delay correction unit of the base station, and even if the area covered by the base station is divided into optical fiber cable units, it is possible to perform optical delay correction simultaneously at multiple locations within the area.

[0060] It should be noted that the embodiments can be freely combined, and each embodiment can be modified or omitted as appropriate.

[0061] <Additional Notes> Various aspects of the present disclosure are summarized below as appendices.

[0062] (Appendix 1) A base station; a plurality of first relay devices connected to the base station via a first optical fiber cable; a plurality of second relay devices connected to the base station via second optical fiber cables; Equipped with Each of the first relay devices includes an optical delay correction unit that corrects a signal delay difference between the first relay device and an adjacent first relay device that is farther from the base station; Each of the plurality of second relay devices includes an optical delay correction unit that corrects a signal delay difference between the second relay device and an adjacent second relay device that is farther from the base station; The base station, a first optical delay correction unit that corrects a signal delay difference between the base station and the first relay device that is closest to the base station; a second optical delay correction unit that corrects a signal delay difference between the base station and the second relay device that is closest to the base station; Equipped with the first optical delay correction unit and the second optical delay correction unit of the base station further correct a signal delay difference between the first relay devices and the second relay devices; Communication systems.

[0063] (Appendix 2) a plurality of the first or second optical fiber cables, each of which is connected to a plurality of the first or second repeater devices, are connected to the first or second optical delay correction unit of the base station; The first or second optical delay correction unit further corrects a phase difference between the first or second optical fiber cables. 2. A communication system as claimed in claim 1.

[0064] (Appendix 3) The system includes a plurality of sets of the base station, a plurality of the first relay devices connected thereto, and a plurality of the second relay devices connected thereto; The first optical delay correction unit and the second optical delay correction unit of a specific base station predetermined as a reference base station further correct a signal delay difference between the specific base station and other base stations. 3. A communication system according to claim 1 or 2.

[0065] (Appendix 4) An optical delay correction method in a communication system according to claim 1, comprising: (a) correcting a signal delay difference by the optical delay correction units of the first relay devices in order from the one farthest from the base station; (b) after the step (a), a first optical delay correction unit of the base station corrects a signal delay difference between the base station and the first relay device that is closest to the base station; (c) correcting the signal delay difference by the optical delay correction units of the second relay devices in order from the one farthest from the base station; (d) after the step (c), a second optical delay correction unit of the base station corrects a signal delay difference between the base station and the second relay device closest to the base station; (e) after both the steps (b) and (d) are completed, the first optical delay correction unit and the second optical delay correction unit of the base station correct a signal delay difference between the first relay devices and the second relay devices; An optical delay correction method comprising:

[0066] (Appendix 5) An optical delay correction method in a communication system according to claim 2, comprising: (a) correcting a signal delay difference by the optical delay correction units of the first relay devices in order from the one farthest from the base station; (b) after the step (a), a first optical delay correction unit of the base station corrects a signal delay difference between the base station and the first relay device closest to the base station, and when there are a plurality of the first optical fiber cables, further corrects a phase difference between the plurality of the first optical fiber cables; (c) correcting the signal delay difference by the optical delay correction units of the second relay devices in order from the one farthest from the base station; (d) after the step (c), a second optical delay correction unit of the base station corrects a signal delay difference between the base station and the second relay device closest to the base station, and when there are a plurality of the second optical fiber cables, further corrects a phase difference between the plurality of the second optical fiber cables; (e) after both the steps (b) and (d) are completed, the first optical delay correction unit and the second optical delay correction unit of the base station correct a signal delay difference between the first relay devices and the second relay devices; An optical delay correction method comprising:

[0067] (Appendix 6) An optical delay correction method in a communication system according to claim 3, comprising: (a) correcting a signal delay difference by the optical delay correction units of the first relay devices in order from the one farthest from the base station; (b) after the step (a), a first optical delay correction unit of the base station corrects a signal delay difference between the base station and the first relay device that is closest to the base station; (c) correcting the signal delay difference by the optical delay correction units of the second relay devices in order from the one farthest from the base station; (d) after the step (c), a second optical delay correction unit of the base station corrects a signal delay difference between the base station and the second relay device closest to the base station; (e) after both the steps (b) and (d) are completed, the first optical delay correction unit and the second optical delay correction unit of the base station correct a signal delay difference between the first relay devices and the second relay devices; (f) after the step (e), the first optical delay correction unit and the second optical delay correction unit of the specific base station correct a signal delay difference between the specific base station and another base station; An optical delay correction method comprising: [Explanation of symbols]

[0068] 1 base station, 1a RF section, 1b E / O section, 1c optical delay correction section, 1d O / E section, 1e optical delay correction section, 1f O / E section, 2 repeater, 2a optical delay correction section, 2b O / E section, 2c E / O section, 2d RF section, 3 coupler, 4 LCX cable, 5 optical fiber cable.

Claims

1. A base station; a plurality of first relay devices connected to the base station via a first optical fiber cable; a plurality of second relay devices connected to the base station via second optical fiber cables; Equipped with Each of the first relay devices includes an optical delay correction unit that corrects a signal delay difference between the first relay device and an adjacent first relay device that is farther from the base station; Each of the plurality of second relay devices includes an optical delay correction unit that corrects a signal delay difference between the second relay device and an adjacent second relay device that is farther from the base station; The base station, a first optical delay correction unit that corrects a signal delay difference between the base station and the first relay device that is closest to the base station; a second optical delay correction unit that corrects a signal delay difference between the base station and the second relay device that is closest to the base station; Equipped with the first optical delay correction unit and the second optical delay correction unit of the base station further correct a signal delay difference between the first relay devices and the second relay devices; Communication systems.

2. a plurality of the first or second optical fiber cables, each of which is connected to a plurality of the first or second repeater devices, are connected to the first or second optical delay correction unit of the base station; The first or second optical delay correction unit further corrects a phase difference between the first or second optical fiber cables. The communication system according to claim 1 .

3. a plurality of sets of the base station, a plurality of the first relay devices connected thereto, and a plurality of the second relay devices connected thereto; The first optical delay correction unit and the second optical delay correction unit of a specific base station predetermined as a reference base station further correct a signal delay difference between the specific base station and other base stations. The communication system according to claim 1 or 2.

4. 2. A method for correcting optical delay in a communication system according to claim 1, comprising: (a) correcting a signal delay difference by the optical delay correction units of the first relay devices in order from the one farthest from the base station; (b) after the step (a), a first optical delay correction unit of the base station corrects a signal delay difference between the base station and the first relay device that is closest to the base station; (c) correcting the signal delay difference by the optical delay correction units of the second relay devices in order from the one farthest from the base station; (d) after the step (c), a second optical delay correction unit of the base station corrects a signal delay difference between the base station and the second relay device that is closest to the base station; (e) after both the steps (b) and (d) are completed, the first optical delay correction unit and the second optical delay correction unit of the base station correct a signal delay difference between the first relay unit and the second relay unit; An optical delay correction method comprising:

5. 3. A method for correcting optical delay in a communication system according to claim 2, comprising: (a) correcting a signal delay difference by the optical delay correction units of the first relay devices in order from the one farthest from the base station; (b) after the step (a), a first optical delay correction unit of the base station corrects a signal delay difference between the base station and the first relay device that is closest to the base station, and when there are a plurality of the first optical fiber cables, further corrects a phase difference between the plurality of the first optical fiber cables; (c) correcting the signal delay difference by the optical delay correction units of the second relay devices in order from the one farthest from the base station; (d) after the step (c), a second optical delay correction unit of the base station corrects a signal delay difference between the base station and the second relay device closest to the base station, and when there are a plurality of the second optical fiber cables, further corrects a phase difference between the plurality of the second optical fiber cables; (e) after both the steps (b) and (d) are completed, the first optical delay correction unit and the second optical delay correction unit of the base station correct a signal delay difference between the first relay unit and the second relay unit; An optical delay correction method comprising:

6. 4. A method for correcting optical delay in a communication system according to claim 3, comprising: (a) correcting a signal delay difference by the optical delay correction units of the first relay devices in order from the one farthest from the base station; (b) after the step (a), a first optical delay correction unit of the base station corrects a signal delay difference between the base station and the first relay device that is closest to the base station; (c) correcting the signal delay difference by the optical delay correction units of the second relay devices in order from the one farthest from the base station; (d) after the step (c), a second optical delay correction unit of the base station corrects a signal delay difference between the base station and the second relay device that is closest to the base station; (e) after both the steps (b) and (d) are completed, the first optical delay correction unit and the second optical delay correction unit of the base station correct a signal delay difference between the first relay unit and the second relay unit; (f) after the step (e), the first optical delay correction unit and the second optical delay correction unit of the specific base station correct a signal delay difference between the specific base station and another base station; An optical delay correction method comprising:

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