Optical communication system, control circuit, storage medium, and optical communication method

Abstract

This optical communication system (40) comprises: a control unit (10) that controls the transmission timings of packet signals transmitted from optical transmitters (1-1 to 1-M) and calculates a scheduled reception time for each redundant packet signal for each of optical receivers (2-1 to 2-M+1); a transmission information holding unit (8) that provides reception data information indicating a packet signal scheduled to be received; a selection control management unit (9) that outputs, on the basis of the reception data information, memory destination information indicating a memory in which the packet signal indicated by the reception data information is stored and output destination information indicating an output destination of the packet signal indicated by the reception data information, from among memories (5-1 to 5-M+1) in which the packet signals received by the optical receiver (2-1 to 2-M+1) are stored; and a packet selection unit (6-1) that selects two memories of reference destinations from the memories (5-1 to 5-M+1) on the basis of the memory destination information, acquires a packet signal from one memory, and outputs the packet signal to an output destination indicated by the output destination information.

Description

[Technical field]

[0001] The present disclosure relates to an optical communication system that performs optical communication, a control circuit, a storage medium, and an optical communication method. [Background technology]

[0002] Conventionally, in networks that communicate by transferring packets, uninterruptible functions have been considered to prevent packet loss when a failure occurs. For example, Patent Document 1 discloses a technology in which a transmitting unit transmits packets of the same data via two routes, system 0 and system 1, and a receiving unit compares the packets received via the two routes, system 0 and system 1, selects one packet, and discards the other packet, thereby performing redundant packet communication. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] JP 2012-178665 A Summary of the Invention [Problem to be solved by the invention]

[0004] When the uninterruptible function of the above-mentioned conventional technology is applied to an optical communication system that uses TDM (Time Division Multiplexing) to achieve redundancy over multiple stages, the receiving device needs a packet selection unit for each transmitter to which communication is targeted. Therefore, the receiving device has a problem that the circuit scale becomes larger according to the number of transmitters as the number of transmitters to which communication is targeted increases due to system expansion, etc.

[0005] The present disclosure has been made in consideration of the above, and has an object to provide an optical communication system capable of suppressing an increase in circuit size when the system is expanded. [Means for solving the problem]

[0006] In order to solve the above-mentioned problems and achieve the object, the present disclosure provides an optical communication system for performing optical communication between a transmitting device having a plurality of optical transmitters and a receiving device having a plurality of optical receivers. The optical communication system is characterized by comprising: a control unit for controlling the transmission timing of packet signals transmitted from the plurality of optical transmitters, calculating the estimated reception time for each of the packet signals transmitted from the plurality of optical transmitters and redundantly made for each of the plurality of optical receivers, and providing the calculated time to the receiving device; a transmission information holding unit for providing reception data information indicating the packet signal to be received indicated by the estimated reception time in the receiving device; a selection control management unit for outputting, based on the reception data information, memory destination information indicating a memory in which the packet signal indicated by the reception data information is stored among a plurality of memories in which the packet signals received by the plurality of optical receivers are stored, and output destination information indicating an output destination of the packet signal indicated by the reception data information; and a packet selection unit for selecting two reference memories from the plurality of memories based on the memory destination information, acquiring a packet signal from one of the two memories, and outputting the packet signal to the output destination indicated by the output destination information. Effect of the Invention

[0007] The optical communication system according to the present disclosure has an advantage that it is possible to suppress an increase in circuit size when the system is expanded. [Brief description of the drawings]

[0008] [Figure 1] FIG. 1 is a diagram showing a configuration example of an optical communication system according to a first embodiment; [Diagram 2] FIG. 1 is a diagram showing a transmission timing at which an optical transmitter transmits a packet signal and a reception timing at which an optical receiver receives the packet signal in the optical communication system according to the first embodiment. [Diagram 3] FIG. 1 is a diagram showing an example of a management table used by a control unit of the optical communication system according to the first embodiment when calculating and managing a scheduled reception time for each packet signal for each optical receiver; [Figure 4]FIG. 1 is a diagram showing an example of a packet selection unit used in response to a packet signal, a memory to be referenced, and a management table used to manage an output destination from the packet selection unit in a receiving device of an optical communication system according to a first embodiment; [Diagram 5] 1 is a flowchart showing the operation of the optical communication system according to the first embodiment. [Figure 6] FIG. 1 is a diagram showing an example of the configuration of a processing circuit that realizes an optical communication system according to a first embodiment, in the case where the processing circuit is configured with a processor and a memory; [Figure 7] FIG. 1 is a diagram showing an example of a processing circuit for implementing an optical communication system according to a first embodiment, the processing circuit being configured with dedicated hardware; [Figure 8] FIG. 1 is a first diagram showing a configuration example of an optical communication system according to a second embodiment; [Figure 9] FIG. 1 is a first diagram showing a transmission timing at which an optical transmitter transmits a packet signal and a reception timing at which an optical receiver receives the packet signal in an optical communication system according to a second embodiment; [Figure 10] FIG. 2 is a second diagram showing a configuration example of an optical communication system according to the second embodiment; [Figure 11] FIG. 2 is a second diagram showing a transmission timing at which an optical transmitter transmits a packet signal and a reception timing at which an optical receiver receives a packet signal in an optical communication system according to a second embodiment; [Figure 12] FIG. 11 is a diagram showing an example of a management table used by a control unit of an optical communication system according to a second embodiment when calculating and managing a scheduled reception time for each packet signal for each optical receiver. [Figure 13] FIG. 11 is a diagram showing an example of a packet selection unit used in response to a packet signal, a memory to be referenced, and a management table used to manage an output destination from the packet selection unit in a receiving device of an optical communication system according to a second embodiment; DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0009] Hereinafter, an optical communication system, a control circuit, a storage medium, and an optical communication method according to embodiments of the present disclosure will be described in detail with reference to the drawings.

[0010] Embodiment 1 FIG. 1 is a diagram showing a configuration example of an optical communication system 40 according to the first embodiment. The optical communication system 40 includes a control unit 10, a transmitting device 20, a receiving device 30, first optical couplers 3-1 to 3-M, and second optical couplers 4-1 to 4-M+1. The optical communication system 40 can be connected in series over a plurality of stages. In the example of FIG. 1, a transmitting device 20 of the optical communication system 40 in the next stage is also shown, but since the operation of the optical communication system 40 in each stage is similar, the following description will be given within the scope shown in FIG. 1. The transmitting device 20 includes optical transmitters 1-1 to 1-M. The receiving device 30 includes optical receivers 2-1 to 2-M+1, memories 5-1 to 5-M+1, a packet selecting unit 6-1, a read control unit 7-1, a transmission information holding unit 8, and a selection control management unit 9. The packet selecting unit 6-1 includes a comparing unit 11-1 and a path selecting unit 12-1.

[0011] In the following description, when the optical transmitters 1-1 to 1-M are not distinguished, they are referred to as an optical transmitter 1, when the optical receivers 2-1 to 2-M+1 are not distinguished, they are referred to as an optical receiver 2, when the first optical couplers 3-1 to 3-M are not distinguished, they are referred to as a first optical coupler 3, when the second optical couplers 4-1 to 4-M+1 are not distinguished, they are referred to as a second optical coupler 4, and when the memories 5-1 to 5-M+1 are not distinguished, they are referred to as a memory 5. In the first embodiment, M is a positive integer equal to or greater than 2. The optical communication system 40 is a communication system that performs optical communication between a transmitting device 20 having a plurality of optical transmitters 1 and a receiving device 30 having a plurality of optical receivers 2.

[0012] The first optical couplers 3-1 to 3-M are provided corresponding to the optical transmitters 1-1 to 1-M via the transmission paths 13-1 to 13-M, respectively. The first optical couplers 3 split an optical signal transmitted from the corresponding optical transmitter 1 into two paths, a working system and a standby system, and output the split optical signals to two different second optical couplers 4. The first optical couplers 3-1 to 3-M are, for example, power splitters.

[0013] The second optical couplers 4-1 to 4-M+1 are provided corresponding to the optical receivers 2-1 to 2-M+1 via the transmission lines 15-1 to 15-M+1, respectively. The second optical coupler 4 combines two optical signals output from two different first optical couplers 3, and outputs the combined signal to the corresponding optical receiver 2. The first optical couplers 3-1 to 3-M and the second optical couplers 4-1 to 4-M+1 are connected by one or two of the transmission lines 14-1a to 14-Mb. Note that the second optical couplers 4-1 and 4-M+1 only obtain an optical signal from one first optical coupler 3 due to the arrangement relationship within the optical communication system 40. Therefore, the optical communication system 40 may be configured without the second optical coupler 4-1 and the second optical coupler 4-M+1. The second optical couplers 4-1 to 4-M+1 are, for example, power splitters.

[0014] The optical transmitters 1-1 to 1-M acquire a data signal for which there is a transmission request. The optical transmitters 1-1 to 1-M may acquire the data signal for which there is a transmission request from M signal generating units (not shown) or from the receiving device 30 of the optical communication system 40 at the previous stage. The optical transmitters 1-1 to 1-M also acquire two types of control signals, a reference clock and a transmission timing signal, generated by the control unit 10, from the control unit 10. The optical transmitters 1-1 to 1-M buffer the acquired data signal once and output it as a packet signal in accordance with the transmission timing signal. In this embodiment, the control unit 10 controls the transmission timing signal so that a packet signal is not transmitted from another optical transmitter 1 while a packet signal is being transmitted from a certain optical transmitter 1. The bit rate of the packet signal transmitted from the optical transmitters 1-1 to 1-M is determined by the reference clock generated by the control unit 10.

[0015] For example, when all the optical transmitters 1-1 to 1-M have the same size of packet signal transmission requests, as shown in FIG. 2, the optical transmitter 1-1 transmits a packet signal in the section of time slot 1, and the other optical transmitters 1-2 to 1-M do not transmit a packet signal in the section of time slot 1. FIG. 2 is a diagram showing the transmission timing at which the optical transmitters 1-1 to 1-M transmit packet signals and the reception timing at which the optical receivers 2-1 to 2-M+1 receive packet signals in the optical communication system 40 according to the first embodiment. FIG. 2 shows the relationship between the packet signals transmitted and received between the optical transmitters 1-1 to 1-M and the optical receivers 2-1 to 2-M+1 and the time slots. In FIG. 2, the packet signals are represented by data 1 to data M. In FIG. 2, the time slots are represented by the time on the horizontal axis. The same applies to the following. When there are no signal transmission requests from M signal generating units at the same time, the control unit 10 may perform control to reduce the total number of time slots in a certain time section according to the number of transmission requests. Additionally, the width of each time slot may or may not be the same.

[0016] Furthermore, the control unit 10 calculates and manages the scheduled reception time for each packet signal for each optical receiver 2 based on the transmission timing signal provided to each optical transmitter 1-1 to 1-M and the transmission path information between the transmitting device 20 and the receiving device 30. The control unit 10 performs management using a management table as shown in Fig. 3, for example. Fig. 3 is a diagram showing an example of a management table used when the control unit 10 of the optical communication system 40 according to the first embodiment calculates and manages the scheduled reception time for each packet signal for each optical receiver 2. Fig. 3 shows the scheduled reception time at each optical receiver 2 for each data, i.e., for each packet signal.

[0017] For example, in the configuration of the optical communication system 40 shown in FIG. 1, a packet signal transmitted from an optical transmitter 1-1 passes through a transmission line 13-1 and is then branched by a first optical coupler 3-1 into two paths, a working system and a backup system. The working system packet signal passes through a transmission line 14-1a, a second optical coupler 4-1, and a transmission line 15-1 and is received by an optical receiver 2-1. The backup system packet signal passes through a transmission line 14-1b, a second optical coupler 4-2, and a transmission line 15-2 and is received by an optical receiver 2-2. When the transmission distance of the path of the working system packet signal and the transmission distance of the path of the backup system packet signal are the same, the control unit 10 calculates that the scheduled reception time of the working system packet signal received by the optical receiver 2-1 and the scheduled reception time of the backup system packet signal received by the optical receiver 2-2 are the same, as shown in FIG. 3. In addition, the transmission distance of the path of the packet signal of the current system and the path of the packet signal of the protection system do not need to be the same, and the scheduled reception time of the packet signal of the current system and the scheduled reception time of the packet signal of the protection system do not need to be the same.

[0018] The control unit 10 provides information on the estimated reception time for each optical receiver 2 calculated for each packet signal to the transmission information storage unit 8 of the receiving device 30. In this way, the control unit 10 controls the transmission timing of packet signals transmitted from the multiple optical transmitters 1, calculates the estimated reception time for each redundant packet signal transmitted from the multiple optical transmitters 1 for each of the multiple optical receivers 2, and provides it to the receiving device 30. The control unit 10 also calculates the estimated reception time based on the transmission timing of the packet signal and the transmission distance of the path of the packet signal of the working system in which the packet signal is made redundant and the transmission distance of the path of the packet signal of the backup system.

[0019] In the receiving device 30, the transmission information holding unit 8 manages information on the scheduled reception time for each optical receiver 2 calculated for each packet signal provided from the control unit 10. At this time, the transmission information holding unit 8 may manage the information in a management table as shown in FIG. 3, similar to the control unit 10. The transmission information holding unit 8 also monitors the scheduled reception time, which is the time slot of the packet signal to be received next, and provides the selection control management unit 9 with reception data information on the packet signal to be received when the scheduled reception time arrives. The reception data information includes the type of packet signal, such as data 1, the scheduled reception time, and the like. In this way, the transmission information holding unit 8 provides the selection control management unit 9 with reception data information indicating the packet signal to be received, which is indicated by the scheduled reception time. In detail, the transmission information holding unit 8 holds and monitors information on the scheduled reception time provided from the control unit 10, and provides the selection control management unit 9 with reception data information on the packet signal to be received in the next time slot when the packet signal is transmitted in units of a specified time slot.

[0020] The selection control management unit 9 manages information of the packet selection unit 6-1 to be used according to the received data information, memory destination information indicating the memory 5 to be referred to by the packet selection unit 6-1, and the output destination from the packet selection unit 6-1. The selection control management unit 9 manages using, for example, a management table as shown in FIG. 4. FIG. 4 is a diagram showing an example of a management table used when managing the packet selection unit 6-1 to be used according to a packet signal, the memory 5 to be referred to, and the output destination from the packet selection unit 6-1 in the receiving device 30 of the optical communication system 40 according to the first embodiment. FIG. 4 shows the packet selection unit 6-1 to be used, the memory 5 to be referred to, and the output destination from the packet selection unit 6-1 for each data, that is, for each packet signal. The selection control management unit 9 provides the memory destination information to be referred to and the output destination information to the target packet selection unit 6-1 corresponding to the received data information based on the received data information provided from the transmission information holding unit 8. In the first embodiment, the receiving device 30 has one packet selection unit 6-1, but a case in which the receiving device has multiple packet selection units will be described in the second embodiment described later.

[0021] In this way, the selection control management unit 9 outputs, based on the received data information, memory destination information indicating the memory 5 in which the packet signal indicated by the received data information is stored among the multiple memories 5 in which packet signals received by the multiple optical receivers 2 are stored, and output destination information indicating the output destination of the packet signal indicated by the received data information. The selection control management unit 9 manages, for each packet signal, information on the packet selection unit 6-1 to be used, memory destination information indicating the two memories 5, and output destination information indicating the output destination of the packet signal, and provides the memory destination information and output destination information to the packet selection unit 6-1 to be used based on the received data information provided from the transmission information holding unit 8.

[0022] As described above, the packet selection unit 6-1 includes a comparison unit 11-1 and a route selection unit 12-1. The comparison unit 11-1 compares the oldest packet signal among the packet signals stored in the memory 5 indicated by the memory destination information provided by the selection control management unit 9 with respect to the packet signals of the working system and the packet signals of the backup system, and determines to acquire one of the packet signals of the working system and the backup system and to discard the other. For example, the comparison unit 11-1 acquires the packet signal stored in the memory 5 that is older in time and discards the packet signal stored in the memory 5 that is newer in time. The comparison unit 11-1 can also acquire the packet signal stored in the memory 5 that is newer in time and discard the packet signal stored in the memory 5 that is older in time. The comparison unit 11-1 provides information about the memory 5 in which the packet signal to be acquired is stored and the memory 5 in which the packet to be discarded is stored to the read control unit 7-1 and the route selection unit 12-1.

[0023] The receiving device 30 needs to have the same number of packet selection units 6-1 as the number of data present in the same time slot section, i.e., the number of packet signals. In this embodiment, the number of data present in the same time slot section, i.e., the number of packet signals, is one. Therefore, the receiving device 30 only needs to have one packet selection unit 6-1, regardless of the number of optical transmitters 1 provided in the transmitting device 20.

[0024] The path selection unit 12-1 selects the optical transmitter 1 to which the packet signal is to be output based on the output destination information provided by the selection control management unit 9. The path selection unit 12-1 also selects an acquisition path for the packet signal so as to select only the packet signal from the acquisition target memory 5 according to the information provided by the comparison unit 11-1. The path selection unit 12-1 functions like a multiplexer in the packet selection unit 6-1.

[0025] In this way, the packet selection unit 6-1 selects two reference memories 5 from the multiple memories 5 based on the memory destination information, acquires a packet signal from one of the two memories 5, and outputs the packet signal to the output destination indicated by the output destination information. The packet selection unit 6-1 also includes a comparison unit 11-1 that selects two reference memories 5 from the multiple memories 5 based on the memory destination information, refers to the packet signals stored in the two memories 5, acquires a packet signal from one memory 5, and decides to discard the packet signal in the other memory 5. The packet selection unit 6-1 also includes a path selection unit 12-1 that controls to acquire a packet signal from one memory 5 and not to acquire a packet signal from the other memory 5 according to the decision of the comparison unit 11-1, and outputs the packet signal acquired from one memory 5 to the output destination.

[0026] The read control unit 7-1 reads out the packet signal from the memory 5 to be acquired according to the information provided by the comparison unit 11-1. At this time, the read control unit 7-1 may not read out the packet signal to be discarded from the memory 5, or may discard it after reading it. When the read control unit 7-1 does not read out the packet signal from the memory 5, the area in the memory 5 where the packet signal was stored is overwritten, resulting in a result that is substantially the same as when the packet signal is discarded. When the read control unit 7-1 reads out and discards the packet signal, it may discard it before passing it to the path selection unit 12-1, or may prevent the path selection unit 12-1 from acquiring it. In this way, the read control unit 7-1 reads out the packet signal from one of the memories 5 according to the decision of the comparison unit 11-1 and outputs it to the path selection unit 12-1.

[0027] In the example of Figure 1, in the receiving device 30, the read control unit 7-1, comparison unit 11-1, and path selection unit 12-1 are connected to memories 5-1 and 5-2, but can also be connected to other memories 5, such as memory 5-3, as shown by dotted lines.

[0028] Next, a specific example of the operation of the optical communication system 40 will be described. As for the transmitting device 20, the optical transmitters 1-1 to 1-M control the timing of transmitting packet signals according to a control signal from the control unit 10, but other operations are similar to those of a general transmitting device, so detailed explanations will be omitted. Below, the operation of the receiving device 30 will first be described using as an example a case where a packet signal of data 1 transmitted from the transmitting device 20 in the section of time slot 1 is received.

[0029] In the receiving device 30, the transmission information storage unit 8 monitors the scheduled reception time for the section of time slot 1. For example, when the information managed by the transmission information storage unit 8 is the management table shown in Fig. 3, the transmission information storage unit 8 monitors the scheduled reception time for the section of time slot 1 to be received next, and provides the selection control management unit 9 with reception data information about the packet signal of data 1 when the scheduled reception time (00.00.30) is reached.

[0030] The selection control management unit 9 provides memory destination information to be referenced to the target packet selection unit 6-1 based on the received data information provided by the transmission information storage unit 8. The selection control management unit 9 has a management table such as that shown in Fig. 4, for example, and when the received data information on the packet signal of data 1 is provided from the transmission information storage unit 8, it notifies the comparison unit 11-1 to select memories 5-1 and 5-2 as the memory destination information to be referenced. In addition, the selection control management unit 9 notifies the path selection unit 12-1 to select the optical transmitter 1-1 as the output destination as the output destination information.

[0031] Comparator 11-1 compares the oldest packet signal of data 1 among the packet signals of data 1 stored in memories 5-1 and 5-2 notified as the memory destination information, and determines from which memory 5 the packet signal of data 1 is to be acquired and from which memory 5 the packet signal of data 1 is to be discarded. Comparator 11-1 provides information on the memory 5 from which the packet signal of data 1 is to be read and the memory 5 from which the packet signal of data 1 is to be discarded to read controller 7-1 and path selector 12-1.

[0032] The read control unit 7-1 reads the packet signal of data 1 from the memory 5 to be acquired in accordance with the information provided by the comparison unit 11-1. For example, when the read control unit 7-1 is notified by the comparison unit 11-1 to acquire the packet signal of data 1 stored in memory 5-1 and discard the packet signal of data 1 stored in memory 5-2, the read control unit 7-1 reads the packet signal of data 1 from memory 5-1 and discards the packet signal of data 1 stored in memory 5-2. The read control unit 7-1 outputs the packet signal of data 1 read from memory 5-1 to the path selection unit 12-1.

[0033] For example, when the route selection unit 12-1 is notified by the comparison unit 11-1 to acquire the packet signal of data 1 stored in memory 5-1 and discard the packet signal of data 1 stored in memory 5-2, the route selection unit 12-1 controls to select only the packet signal of data 1 on the route from memory 5-1 and not to select the packet signal of data 1 on the route from memory 5-2. The route selection unit 12-1 controls to transfer the packet signal of data 1 from memory 5-1 to the optical transmitter 1-1.

[0034] Through the above operation, the receiving device 30 is able to use the packet selection unit 6-1 to determine whether to select or discard the current system packet signal and the protection system packet signal of data 1 transmitted from the optical transmitter 1-1 in the section of time slot 1.

[0035] Next, the operation of the receiving device 30 will be described taking as an example a case where a packet signal of data 2 transmitted from the transmitting device 20 in the section of time slot 2 is received.

[0036] The transmission information holding unit 8 monitors the scheduled reception time of the next receiving section of time slot 2, and provides the selection control management unit 9 with reception data information on the packet signal of data 2 when the scheduled reception time (00.00.75) arrives.

[0037] The selection control management unit 9 provides memory destination information to be referenced to the target packet selection unit 6-1 based on the received data information provided by the transmission information storage unit 8. The selection control management unit 9 notifies the comparison unit 11-1 to select memories 5-2 and 5-3 as the memory destination information to be referenced. The selection control management unit 9 also notifies the path selection unit 12-1 to select the optical transmitter 1-2 as the output destination information.

[0038] Comparator 11-1 compares the oldest packet signal of data 2 among the packet signals of data 2 stored in memories 5-2 and 5-3 notified as the memory destination information, and determines from which memory 5 the packet signal of data 2 is to be acquired and from which memory 5 the packet signal of data 2 is to be discarded. Comparator 11-1 provides information on the memory 5 from which the packet signal of data 2 is to be read and the memory 5 from which the packet signal of data 2 is to be discarded to read controller 7-1 and path selector 12-1.

[0039] The read control unit 7-1 reads the packet signal of data 2 from the memory 5 to be acquired in accordance with the information provided by the comparison unit 11-1. For example, when the read control unit 7-1 is notified by the comparison unit 11-1 to acquire the packet signal of data 2 stored in memory 5-3 and discard the packet signal of data 2 stored in memory 5-2, the read control unit 7-1 reads the packet signal of data 2 from memory 5-3 and discards the packet signal of data 2 stored in memory 5-2. The read control unit 7-1 outputs the packet signal of data 2 read from memory 5-3 from memory 5-3 to the path selection unit 12-1.

[0040] For example, when the route selection unit 12-1 is notified by the comparison unit 11-1 to acquire the packet signal of data 2 stored in the memory 5-3 and discard the packet signal of data 2 stored in the memory 5-2, the route selection unit 12-1 controls to select only the packet signal of data 2 on the route from the memory 5-3 and not to select the packet signal of data 2 on the route from the memory 5-2. The route selection unit 12-1 controls to transfer the packet signal of data 2 from the memory 5-3 to the optical transmitter 1-2.

[0041] By the above operation, the receiving device 30 is able to use the packet selection unit 6-1 to determine whether to select or discard the current system packet signal and the protection system packet signal of data 2 transmitted from the optical transmitter 1-2 in the section of time slot 2.

[0042] 5 is a flowchart showing the operation of the optical communication system 40 according to the first embodiment. In the optical communication system 40, the control unit 10 calculates the expected reception time for each packet signal transmitted from the multiple optical transmitters 1 and made redundant for each of the multiple optical receivers 2, and provides the information of the expected reception time to the transmission information holding unit 8 of the receiving device 30 (step S1). The transmission information holding unit 8 provides the reception data information indicating the packet signal to be received indicated by the expected reception time to the selection control management unit 9 (step S2). The selection control management unit 9 outputs, based on the reception data information, memory destination information indicating the memory 5 in which the packet signal indicated by the reception data information is stored among the multiple memories 5 in which the packet signals received by the multiple optical receivers 2 are stored, and output destination information indicating the output destination of the packet signal indicated by the reception data information (step S3). The packet selection unit 6-1 selects two reference memories 5 from the multiple memories 5 based on the memory destination information, acquires a packet signal from one of the two memories 5, and outputs the packet signal to the optical transmitter 1 indicated by the output destination information (step S4).

[0043] Next, the hardware configuration of the optical communication system 40 will be described. In the optical communication system 40, the optical transmitter 1 is a communication device capable of transmitting an optical signal. The optical receiver 2 is a communication device capable of receiving an optical signal. The first optical coupler 3 and the second optical coupler 4 are power splitters. The memory 5 is a storage device such as a buffer. The packet selection unit 6-1, the read control unit 7-1, the transmission information holding unit 8, the selection control management unit 9, and the control unit 10 are realized by processing circuits. The processing circuit may be a processor and memory that executes a program stored in the memory, or may be dedicated hardware. The processing circuit is also called a control circuit.

[0044] FIG. 6 is a diagram showing a configuration example of a processing circuit 90 for implementing the optical communication system 40 according to the first embodiment, in the case where the processing circuit is configured with a processor 91 and a memory 92. The processing circuit 90 shown in FIG. 6 is a control circuit, and includes a processor 91 and a memory 92. When the processing circuit 90 is configured with the processor 91 and the memory 92, each function of the processing circuit 90 is implemented by software, firmware, or a combination of software and firmware. The software or firmware is described as a program and stored in the memory 92. In the processing circuit 90, each function is implemented by the processor 91 reading and executing the program stored in the memory 92. That is, the processing circuit 90 includes a memory 92 for storing a program that results in the processing of the optical communication system 40 being executed. This program can also be said to be a program for causing the optical communication system 40 to execute each function implemented by the processing circuit 90. This program may be provided by a storage medium in which the program is stored, or may be provided by other means such as a communication medium.

[0045] The above program can also be said to be a program executed in the optical communication system 40, which includes a first step in which the control unit 10 controls the transmission timing of packet signals transmitted from the multiple optical transmitters 1, calculates the scheduled reception time for each of the redundant packet signals transmitted from the multiple optical transmitters 1 for each of the multiple optical receivers 2, and provides the received signal to the receiving device 30; a second step in which the transmission information holding unit 8 provides received data information indicating the packet signal scheduled to be received, indicated by the scheduled reception time, at the receiving device 30; a third step in which the selection control management unit 9 outputs, based on the received data information, memory destination information indicating the memory 5 in which the packet signal indicated by the received data information is stored, among the multiple memories 5 in which the packet signals received by the multiple optical receivers 2 are stored, and output destination information indicating the output destination of the packet signal indicated by the received data information; and a fourth step in which the packet selection unit 6-1 selects two reference memories 5 from the multiple memories 5 based on the memory destination information, acquires a packet signal from one of the two memories 5, and outputs the packet signal to the output destination indicated by the output destination information.

[0046] Here, the processor 91 is, for example, a CPU (Central Processing Unit), a processing device, an arithmetic device, a microprocessor, a microcomputer, or a DSP (Digital Signal Processor), etc. Also, the memory 92 is, for example, a non-volatile or volatile semiconductor memory such as a RAM (Random Access Memory), a ROM (Read Only Memory), a flash memory, an EPROM (Erasable Programmable ROM), an EEPROM (Electrically EPROM), a magnetic disk, a flexible disk, an optical disk, a compact disk, a mini disk, or a DVD (Digital Versatile Disc), etc.

[0047] Fig. 7 is a diagram showing an example of a processing circuit 93 in the case where the processing circuit for implementing the optical communication system 40 according to the first embodiment is configured with dedicated hardware. The processing circuit 93 shown in Fig. 7 corresponds to, for example, a single circuit, a composite circuit, a programmed processor, a parallel programmed processor, an ASIC (Application Specific Integrated Circuit), an FPGA (Field Programmable Gate Array), or a combination of these. The processing circuit may be partially implemented with dedicated hardware and partially implemented with software or firmware. In this way, the processing circuit can realize each of the above-mentioned functions by dedicated hardware, software, firmware, or a combination of these.

[0048] As described above, according to this embodiment, the receiving apparatus 30 of the optical communication system 40 shares and uses one packet selection unit 6-1 for M optical transmitters 1-1 to 1-M. When the packet selection unit 6-1 refers to the memory 5 storing the packet signal of the active system and the memory 5 storing the packet signal of the standby system, it selects the memory 5 to be referred to for each time slot based on the scheduled reception time provided from the control unit 10. Thereby, when the non-interrupt function of Patent Document 1 described above is applied to the optical communication system 40 that realizes redundancy in multiple stages using TDM, the number of packet selection units 6-1 and the number of read control units 7-1, which were required to be M in the related art, can be reduced to 1 / M. Therefore, the optical communication system 40 can suppress an increase in the circuit scale when the system is expanded, and can significantly reduce the circuit scale.

[0049] Embodiment 2. In Embodiment 2, a case where the receiving apparatus includes N packet selection units and read control units, where N is less than M, the number of optical transmitters 1 included in the transmitting apparatus 20, will be described. Note that, in Embodiment 2, N is a positive integer of 2 or more, and M is a positive integer such that N < M.

[0050] FIG. 8 is a first diagram showing a configuration example of an optical communication system 40a according to a second embodiment. The optical communication system 40a includes a control unit 10, a transmitting device 20, a receiving device 30a, first optical couplers 3-1 to 3-M, and second optical couplers 4-1 to 4-M+1. The optical communication system 40a can be serially connected over a plurality of stages, and in the example of FIG. 8, the transmitting device 20 of the optical communication system 40a in the next stage is also shown, but since the operation of the optical communication system 40a in each stage is similar, the following description will be given within the scope shown in FIG. 8. The transmitting device 20 includes optical transmitters 1-1 to 1-M. The receiving device 30a includes optical receivers 2-1 to 2-M+1, memories 5-1 to 5-M+1, packet selection units 6-1 to 6-N, read control units 7-1 to 7-N, a transmission information holding unit 8, and a selection control management unit 9. The packet selection unit 6-1 includes a comparison unit 11-1 and a route selection unit 12-1. The packet selection unit 6-N includes a comparison unit 11-N and a route selection unit 12-N. Although not shown, the packet selection units 6-2 to 6-(N-1) also include a comparison unit and a route selection unit, respectively. That is, the receiving device 30a includes comparison units 11-1 to 11-N and route selection units 12-1 to 12-N.

[0051] In the following description, when packet selection units 6-1 to 6-N are not distinguished, they may be referred to as packet selection unit 6, when read control units 7-1 to 7-N are not distinguished, they may be referred to as read control unit 7, when comparison units 11-1 to 11-N are not distinguished, they may be referred to as comparison unit 11, and when path selection units 12-1 to 12-N are not distinguished, they may be referred to as path selection unit 12.

[0052] The optical transmitters 1-1 to 1-M acquire a data signal for which there is a transmission request. The optical transmitters 1-1 to 1-M may acquire the data signal for which there is a transmission request from M signal generating units (not shown) or from the receiving device 30a of the optical communication system 40a at the previous stage. The optical transmitters 1-1 to 1-M also acquire two types of control signals, a reference clock and a transmission timing signal, generated by the control unit 10, from the control unit 10. The optical transmitters 1-1 to 1-M buffer the acquired data signal once and output it as a packet signal in accordance with the transmission timing signal. In this embodiment, the control unit 10 controls the transmission timing signal so that the optical transmitters 1 having paths for transmitting packet signals to the same second optical coupler 4 do not transmit packet signals at the same timing.

[0053] For example, assume that all of the optical transmitters 1-1 to 1-M have the same size packet signal transmission request. Since the optical transmitters 1 having a path for transmitting a packet signal to the second optical coupler 4-2 are the optical transmitters 1-1 and 1-2, the control unit 10 performs transmission control such that the optical transmitter 1-1 transmits a packet signal in the section of time slot 1 and the optical transmitter 1-2 does not transmit a packet signal in the section of time slot 1, as shown in FIG. 9. In the next section of time slot 2, the control unit 10 performs transmission control such that the optical transmitter 1-2 transmits a packet signal in the section of time slot 2 and the optical transmitter 1-1 does not transmit a packet signal in the section of time slot 2, as shown in FIG. 9. FIG. 9 is a first diagram showing transmission timings at which the optical transmitters 1-1 to 1-M transmit packet signals and reception timings at which the optical receivers 2-1 to 2-M+1 receive packet signals in the optical communication system 40a according to the second embodiment.

[0054] Moreover, since the optical transmitters 1 having a path for transmitting a packet signal to the second optical coupler 4-3 are the optical transmitters 1-2 and 1-3, the control unit 10 performs transmission control such that the optical transmitter 1-3 transmits a packet signal in the section of time slot 1, and the optical transmitter 1-2 does not transmit a packet signal in the section of time slot 1, as shown in Fig. 9. In the next section of time slot 2, the control unit 10 performs transmission control such that the optical transmitter 1-2 transmits a packet signal in the section of time slot 2, and the optical transmitter 1-3 does not transmit a packet signal in the section of time slot 2, as shown in Fig. 9. Note that in the optical communication system 40a, the transmission timings of the optical transmitters 1 that do not transmit packet signals to the same second optical coupler 4 may be the same or different.

[0055] The transmission information holding unit 8 monitors the scheduled reception time, which is the time slot of the next packet signal to be received, and provides the selection control management unit 9 with reception data information regarding the multiple packet signals to be received when the scheduled reception time arrives.

[0056] Based on a plurality of pieces of received data information provided from the transmission information storage unit 8, the selection control management unit 9 provides memory destination information and output destination information to the target packet selection unit 6 corresponding to the received data information.

[0057] The receiving device 30a needs to have the same number of packet selection units 6 as the number of data present in the same time slot section, i.e., the number of packet signals. In this embodiment, the number of data present in the same time slot section, i.e., the number of packet signals, is N. Therefore, the receiving device 30a only needs to have N packet selection units 6, regardless of the number of optical transmitters 1 included in the transmitting device 20.

[0058] Next, a case where M=4 will be described as a specific example of the operation of the optical communication system 40a. As for the transmitting device 20, the optical transmitters 1-1 to 1-M control the timing of transmitting packet signals according to a control signal from the control unit 10, but other operations are similar to those of a general transmitting device, so detailed description will be omitted. In the following, the operation of the receiving device 30a will be described by first taking as an example a case where a packet signal of data 1 and a packet signal of data 3 transmitted from the transmitting device 20 in a section of time slot 1 are received. FIG. 10 is a second diagram showing a configuration example of the optical communication system 40a according to the second embodiment. FIG. 11 is a second diagram showing the transmission timing at which the optical transmitters 1-1 to 1-M transmit packet signals and the reception timing at which the optical receivers 2-1 to 2-M+1 receive packet signals in the optical communication system 40a according to the second embodiment.

[0059] When the receiving device 30a receives a packet signal of data 1 and a packet signal of data 3 transmitted in the section of time slot 1, the transmission information holding unit 8 monitors the scheduled reception time in the section of time slot 1. For example, when the information to be managed is the management table shown in Fig. 12, the transmission information holding unit 8 provides the selection control management unit 9 with received data information on the packet signal of data 1 and the packet signal of data 3 at the scheduled reception time (00.00.30). Fig. 12 is a diagram showing an example of a management table used when the control unit 10 of the optical communication system 40a according to the second embodiment calculates and manages the scheduled reception time for each packet signal for each optical receiver 2.

[0060] The selection control management unit 9 provides the target packet selection unit 6 with memory destination information to be referenced based on the received data information provided from the transmission information holding unit 8. The selection control management unit 9 has a management table as shown in FIG. 13, for example, and when the transmission information holding unit 8 provides received data information on the packet signal of data 1 and the packet signal of data 3, it notifies the comparison unit 11-1 to select the memories 5-1 and 5-2 as the memory destination information to be referenced, and notifies the comparison unit 11-2 to select the memories 5-3 and 5-4 as the memory destination information to be referenced. The selection control management unit 9 also notifies the path selection unit 12-1 to select the optical transmitter 1-1 as the output destination as the output destination information, and notifies the path selection unit 12-2 to select the optical transmitter 1-3 as the output destination as the output destination information. FIG. 13 is a diagram showing an example of a management table used to manage the packet selection unit 6 used in response to a packet signal in a receiving device 30a of an optical communication system 40a relating to embodiment 2, the memory 5 to be referenced, and the output destination from the packet selection unit 6.

[0061] Comparator 11-1 compares the oldest packet signal of data 1 among the packet signals of data 1 stored in memories 5-1 and 5-2 notified as the memory destination information, and determines from which memory 5 the packet signal of data 1 is to be acquired and from which memory 5 the packet signal of data 1 is to be discarded. Comparator 11-1 provides information on the memory 5 from which the packet signal of data 1 is to be read and the memory 5 from which the packet signal of data 1 is to be discarded to read controller 7-1 and path selector 12-1.

[0062] Furthermore, comparison unit 11-2 compares the oldest packet signal of data 3 among the packet signals of data 3 stored in memories 5-3 and 5-4 notified as the memory destination information, and determines from which memory 5 the packet signal of data 3 is to be acquired and from which memory 5 the packet signal of data 3 is to be discarded. Comparison unit 11-2 provides information on the memory 5 from which the packet signal of data 3 is to be read and the memory 5 from which the packet signal of data 3 is to be discarded to read control unit 7-2 and path selection unit 12-2.

[0063] The read control unit 7-1 reads the packet signal of data 1 from the memory 5 to be acquired in accordance with the information provided by the comparison unit 11-1, and discards the packet signal of data 1 stored in the memory 5 to be discarded. The read control unit 7-2 reads the packet signal of data 3 from the memory 5 to be acquired in accordance with the information provided by the comparison unit 11-2, and discards the packet signal of data 3 stored in the memory 5 to be discarded.

[0064] The path selection unit 12-1 performs control so that only the packet signal of data 1 from the memory 5 to be acquired is transferred to the optical transmitter 1-1 at the subsequent stage according to the information provided by the comparison unit 11-1. For example, the path selection unit 12-1 performs control so that the packet signal of data 1 from the memory 5-1 is transferred to the optical transmitter 1-1. Also, the path selection unit 12-2 performs control so that only the packet signal of data 3 from the memory 5 to be acquired is transferred to the optical transmitter 1-3 at the subsequent stage according to the information provided by the comparison unit 11-2. For example, the path selection unit 12-2 performs control so that the packet signal of data 3 from the memory 5-3 is transferred to the optical transmitter 1-3.

[0065] By the above operation, the receiving device 30a is able to use the packet selection units 6-1, 6-2 to determine whether to select or discard the working system packet signal and the backup system packet signal of data 1 transmitted from the optical transmitter 1-1 in the section of time slot 1, and the working system packet signal and the backup system packet signal of data 3 transmitted from the optical transmitter 1-3 in the section of time slot 1.

[0066] Next, the operation of the receiving device 30a will be described taking as an example a case where a packet signal of data 2 and a packet signal of data 4 transmitted from the transmitting device 20 in the section of time slot 2 are received.

[0067] When receiving device 30a receives a packet signal of data 2 and a packet signal of data 4 transmitted in the section of time slot 2, transmission information storage unit 8 monitors the scheduled reception time in the section of time slot 2. When the scheduled reception time (00.00.75) arrives, transmission information storage unit 8 provides selection control management unit 9 with reception data information regarding the packet signal of data 2 and the packet signal of data 4.

[0068] The selection control management unit 9 provides memory destination information to be referenced to the target packet selection unit 6 based on the received data information provided from the transmission information holding unit 8. The selection control management unit 9 notifies the comparison unit 11-1 to select memories 5-2 and 5-3 as memory destination information to be referenced, and notifies the comparison unit 11-2 to select memories 5-4 and 5-5 as memory destination information to be referenced. The selection control management unit 9 also notifies the path selection unit 12-1 to select optical transmitter 1-2 as the output destination as output destination information, and notifies the path selection unit 12-2 to select optical transmitter 1-4 as the output destination as output destination information.

[0069] Comparator 11-1 compares the oldest packet signal of data 2 among the packet signals of data 2 stored in memories 5-2 and 5-3 notified as the memory destination information, and determines from which memory 5 the packet signal of data 2 is to be acquired and from which memory 5 the packet signal of data 2 is to be discarded. Comparator 11-1 provides information on the memory 5 from which the packet signal of data 2 is to be read and the memory 5 from which the packet signal of data 2 is to be discarded to read controller 7-1 and path selector 12-1.

[0070] Furthermore, comparison unit 11-2 compares the oldest packet signal of data 4 among the packet signals of data 4 stored in memories 5-4 and 5-5 notified as the memory destination information, and determines from which memory 5 the packet signal of data 4 is to be acquired and from which memory 5 the packet signal of data 4 is to be discarded. Comparison unit 11-2 provides information on the memory 5 from which the packet signal of data 4 is to be read and the memory 5 from which the packet signal of data 4 is to be discarded to read control unit 7-2 and path selection unit 12-2.

[0071] The read control unit 7-1 reads the packet signal of data 2 from the memory 5 to be acquired in accordance with the information provided by the comparison unit 11-1, and discards the packet signal of data 2 stored in the memory 5 to be discarded. The read control unit 7-2 reads the packet signal of data 4 from the memory 5 to be acquired in accordance with the information provided by the comparison unit 11-2, and discards the packet signal of data 4 stored in the memory 5 to be discarded.

[0072] The path selection unit 12-1 performs control so that only the packet signal of data 2 from the memory 5 to be acquired is transferred to the optical transmitter 1-2 at the subsequent stage according to the information provided by the comparison unit 11-1. For example, the path selection unit 12-1 performs control so that the packet signal of data 2 from the memory 5-2 is transferred to the optical transmitter 1-2. Also, the path selection unit 12-2 performs control so that only the packet signal of data 4 from the memory 5 to be acquired is transferred to the optical transmitter 1-4 at the subsequent stage according to the information provided by the comparison unit 11-2. For example, the path selection unit 12-2 performs control so that the packet signal of data 4 from the memory 5-5 is transferred to the optical transmitter 1-4.

[0073] By the above operation, the receiving device 30a is able to use the packet selection units 6-1, 6-2 to determine whether to select or discard the working system packet signal and the backup system packet signal of data 2 transmitted from the optical transmitter 1-2 in the section of time slot 2, and the working system packet signal and the backup system packet signal of data 4 transmitted from the optical transmitter 1-4 in the section of time slot 2.

[0074] As described above, according to the present embodiment, the receiving device 30a of the optical communication system 40a uses N packet selection units 6, i.e., packet selection units 6-1 to 6-N, in common with M optical transmitters 1-1 to 1-M. When referring to the memory 5 in which the packet signals of the working system are stored and the memory 5 in which the packet signals of the backup system are stored, the packet selection units 6-1 to 6-N switch the memory 5 to be referred to for each time slot based on the expected reception time provided by the control unit 10. This makes it possible for the receiving device 30a to reduce the number of packet selection units 6 and the read control units 7, which were required in the case of applying the uninterrupted function of the above-mentioned Patent Document 1 to the optical communication system 40a that realizes redundancy over multiple stages using TDM, to N / M. Therefore, the optical communication system 40a can suppress an increase in the circuit scale when the system is expanded, and can significantly reduce the circuit scale.

[0075] The configurations shown in the above embodiments are merely examples, and may be combined with other known technologies, or the embodiments may be combined with each other. Also, parts of the configurations may be omitted or modified without departing from the spirit of the invention. [Explanation of symbols]

[0076] 1-1 to 1-M optical transmitters, 2-1 to 2-M+1 optical receivers, 3-1 to 3-M first optical couplers, 4-1 to 4-M+1 second optical couplers, 5-1 to 5-M+1, 92 memory, 6-1 to 6-N packet selection units, 7-1 to 7-N read control units, 8 transmission information storage units, 9 selection control management units, 10 control units, 11-1 to 11-N comparison units, 12-1 to 12-N route selection units, 13-1 to 13-M, 14-1a to 14-Mb, 15-1 to 15-M+1 transmission paths, 20 transmission devices, 30, 30a reception devices, 40, 40a optical communication systems, 90, 93 processing circuits, 91 processors.

Claims

1. An optical communication system for performing optical communication between a transmitting device having a plurality of optical transmitters and a receiving device having a plurality of optical receivers, a control unit that controls transmission timings of packet signals transmitted from the plurality of optical transmitters, calculates a scheduled reception time for each of the packet signals transmitted from the plurality of optical transmitters and made redundant for each of the plurality of optical receivers, and provides the scheduled reception time to the receiving device; a transmission information storage unit for providing reception data information indicating the packet signal to be received, the packet signal being indicated by the scheduled reception time, in the receiving device; a selection control management unit that outputs, based on the received data information, memory destination information indicating a memory in which the packet signal indicated by the received data information is stored among a plurality of memories in which the packet signals received by the plurality of optical receivers are stored, and output destination information indicating an output destination of the packet signal indicated by the received data information; a packet selection unit that selects two reference memories from the plurality of memories based on the memory destination information, acquires the packet signal from one of the two memories, and outputs the packet signal to the output destination indicated by the output destination information; An optical communication system comprising:

2. the control unit calculates the expected reception time based on the transmission timing of the packet signal, and a transmission distance of a route of a packet signal of a working system in which the packet signal is made redundant and a transmission distance of a route of a packet signal of a backup system.

2. The optical communication system according to claim 1 .

3. The control unit provides information of the scheduled reception time to the transmission information storage unit, the transmission information storage unit stores and monitors the information of the scheduled reception time provided from the control unit, and when the packet signal is transmitted in units of a specified time slot, provides the selection control management unit with the reception data information regarding the packet signal to be received in the next time slot.

2. The optical communication system according to claim 1 .

4. the selection control management unit manages, for each of the packet signals, information on the packet selection unit to be used, the memory destination information indicating the two memories, and the output destination information indicating the output destination of the packet signal, and provides the memory destination information and the output destination information to the packet selection unit to be used based on the reception data information provided from the transmission information holding unit.

2. The optical communication system according to claim 1 .

5. The packet selection unit a comparison unit that selects two of the memories to be referenced from the plurality of memories based on the memory destination information, refers to the packet signals stored in the two memories, and determines to acquire the packet signal from one of the memories and discard the packet signal in the other memory; 5. The optical communication system according to claim 1, further comprising:

6. The packet selection unit a route selection unit that performs control to acquire the packet signal from one of the memories and not to acquire the packet signal from the other of the memories according to a decision of the comparison unit, and outputs the packet signal acquired from one of the memories to the output destination; 6. The optical communication system according to claim 5, further comprising:

7. a read control unit that reads the packet signal from one of the memories in accordance with the decision of the comparison unit and outputs the packet signal to the path selection unit; 7. The optical communication system according to claim 6, further comprising:

8. A control circuit for controlling an optical communication system that performs optical communication between a transmitting device having a plurality of optical transmitters and a receiving device having a plurality of optical receivers, comprising: controlling transmission timings of packet signals transmitted from the plurality of optical transmitters, calculating a scheduled reception time for each of the packet signals transmitted from the plurality of optical transmitters and made redundant for each of the plurality of optical receivers, and providing the calculated scheduled reception time to the receiving device; providing, in the receiving device, reception data information indicating the packet signal to be received, which is indicated by the scheduled reception time; outputting, based on the received data information, memory destination information indicating a memory in which the packet signal indicated by the received data information is stored among a plurality of memories in which the packet signals received by the plurality of optical receivers are stored, and output destination information indicating an output destination of the packet signal indicated by the received data information; selecting two reference memories from the plurality of memories based on the memory destination information, acquiring the packet signal from one of the two memories, and outputting the packet signal to the output destination indicated by the output destination information; A control circuit for causing the optical communication system to implement the above.

9. A storage medium storing a program for controlling an optical communication system that performs optical communication between a transmitting device having a plurality of optical transmitters and a receiving device having a plurality of optical receivers, The program is controlling transmission timings of packet signals transmitted from the plurality of optical transmitters, calculating a scheduled reception time for each of the packet signals transmitted from the plurality of optical transmitters and made redundant for each of the plurality of optical receivers, and providing the calculated scheduled reception time to the receiving device; providing, in the receiving device, reception data information indicating the packet signal to be received, which is indicated by the scheduled reception time; outputting, based on the received data information, memory destination information indicating a memory in which the packet signal indicated by the received data information is stored among a plurality of memories in which the packet signals received by the plurality of optical receivers are stored, and output destination information indicating an output destination of the packet signal indicated by the received data information; selecting two reference memories from the plurality of memories based on the memory destination information, acquiring the packet signal from one of the two memories, and outputting the packet signal to the output destination indicated by the output destination information; A storage medium for causing the optical communication system to implement the above.

10. An optical communication method for an optical communication system that performs optical communication between a transmitting device having a plurality of optical transmitters and a receiving device having a plurality of optical receivers, comprising: a first step in which a control unit controls transmission timings of packet signals transmitted from the plurality of optical transmitters, calculates a scheduled reception time for each of the packet signals transmitted from the plurality of optical transmitters and made redundant for each of the plurality of optical receivers, and provides the scheduled reception time to the receiving device; a second step of providing, by a transmission information storage unit, reception data information indicating the packet signal to be received, which is indicated by the scheduled reception time, at the receiving device; a third step in which a selection control management unit outputs, based on the received data information, memory destination information indicating a memory in which the packet signal indicated by the received data information is stored among a plurality of memories in which the packet signals received by the plurality of optical receivers are stored, and output destination information indicating an output destination of the packet signal indicated by the received data information; a fourth step in which a packet selection unit selects two reference memories from the plurality of memories based on the memory destination information, acquires the packet signal from one of the two memories, and outputs the packet signal to the output destination indicated by the output destination information; 13. An optical communication method comprising:

Images