Control device and control method

Abstract

This control device comprises: a plurality of communication stations that are connected to one or more terminals directly or via another device; a cooperation information collection unit that acquires cooperation information indicating a state of communication with the one or more terminals from the plurality of communication stations; and an analysis unit that determines one or more communication stations, which are to be subjected to sleep control, from among the plurality of communication stations on the basis of a result of rearranging the plurality of communication stations based on the cooperation information, and executes sleep control on the one or more communication stations to be subjected to sleep control.　

Description

Control device and control method

[0001] The present invention relates to a control device and a control method.

[0002] In conventional communication systems that perform wireless communication between terminals and base stations, each base station calculates its throughput and autonomously goes into sleep mode when the throughput exceeds a threshold, thereby saving power. In such communication systems, terminals connected to the sleeping base station are instructed to hand over to the base station with the highest throughput, allowing the terminal to continue communication.

[0003] Yong Sheng Soh, Tony QSQuek, and Marios Kountouris, “Dynamic Sleep Mode Strategies in Energy Efficient Cellular Networks”, IEEE, Communications Theory, pp.3131 3136, June 2013.

[0004] However, in conventional communication systems, a terminal connected to a sleeping base station may be handed over to a base station already connected to a large number of terminals, resulting in a deterioration in communication quality.Furthermore, in conventional communication systems, each base station autonomously determines whether to sleep, which can limit the effectiveness of power saving by preventing optimization of the entire system.

[0005] In view of the above circumstances, an object of the present invention is to provide a technique that can increase the effect of power saving without deteriorating communication quality.

[0006] One aspect of the present invention is a control device that includes a plurality of communication stations connected directly or via other devices to one or more terminals, a coordination information collection unit that acquires coordination information from the plurality of communication stations that indicates the state of communication between the one or more terminals, and an analysis unit that determines one or more communication stations from the plurality of communication stations that are to be subject to sleep control based on a result of rearranging the plurality of communication stations based on the coordination information, and executes sleep control on the one or more communication stations that are to be subject to sleep control.

[0007] One aspect of the present invention is a control method that acquires, from a plurality of communication stations connected directly or via other devices to one or more terminals, coordination information indicating the state of communication between the one or more terminals and the plurality of communication stations, determines one or more communication stations from the plurality of communication stations to be subject to sleep control based on the results of rearranging the plurality of communication stations based on the coordination information, and executes sleep control on the one or more communication stations to be subject to sleep control.

[0008] According to the present invention, it is possible to increase the effect of power saving without deteriorating the communication quality.

[0009] 1 is a diagram for explaining an overview of the overall configuration and processing of a mobile NW system in an embodiment. FIG. 1 is a diagram for explaining a conventional method for selecting a central station to be put to sleep. FIG. 2 is a diagram for explaining a method for selecting a central station to be put to sleep in the first embodiment. FIG. 3 is a diagram for explaining a conventional method for selecting a central station to be put to sleep. FIG. 4 is a diagram for explaining a method for selecting a central station to be put to sleep in the first embodiment. FIG. 5 is a diagram for explaining a method for selecting a central station to be put to sleep in the first embodiment. FIG. 6 is a diagram for explaining a configuration example of a mobile NW system in the first embodiment. FIG. 7 is a flowchart showing an example of the flow of sleep processing executed by a management control device in the first embodiment. FIG. 8 is a flowchart showing an example of the flow of sleep processing executed by a management control device in the first embodiment. FIG. 9 is a diagram for explaining an example of the configuration of a mobile NW system in a first modified example of the first embodiment. FIG. 10 is a diagram for explaining an example of the configuration of a mobile NW system in a second modified example of the first embodiment. FIG. 10 is a flowchart showing an example of the flow of sleep processing executed by the management control device in the second embodiment. FIG. 11 is a flowchart showing an example of the flow of sleep release processing executed by the management control device in the second embodiment. FIG. 12 is a diagram for explaining the overall configuration and processing overview of a wired NW system in an embodiment. FIG. 13 is a diagram showing an example of the configuration of a wired NW system in a third embodiment. FIG. 14 is a flowchart showing an example of the flow of sleep processing executed by the management control device in the third embodiment. FIG. 15 is a flowchart showing an example of the flow of sleep release processing executed by the management control device in the third embodiment.

[0010] An embodiment of the present invention will be described below with reference to the drawings. (Outline of First Embodiment) Fig. 1 is a diagram for explaining an overview of the overall configuration and processing of a mobile network system in an embodiment. First, the overall configuration of the mobile network system will be described. The mobile network system is an example of a communication system. The mobile network system is, for example, a fifth-generation mobile communication system (hereinafter referred to as "5G"). The mobile network system includes multiple radio stations 12, a transfer device 14, multiple central stations 16, and a management control device 20.

[0011] Each wireless station 12 and the transfer device 14, and each wireless station 14 and each central station 16 are connected by optical fiber that transmits optical signals. The transfer device 14 and the management control device 20, and each central station 16 and the management control device 20 are connected by electric wires or optical fiber that transmit electric signals. The example shown in Fig. 1 shows a case where there are M (M is an integer of 2 or more) wireless stations 12 and N (N is an integer of 2 or more) central stations 16. Note that although multiple transfer devices 14 may be provided, the following explanation will be given using a single device as an example.

[0012] Each wireless station 12 includes one or more antennas and performs wireless communication with one or more terminals 11. For example, each wireless station 12 receives signals transmitted from one or more terminals 11 and transmits the received signals to a central station 16 connected via a transfer device 14. Each wireless station 12 transmits the signals received via the transfer device 14 to one or more terminals 11. The wireless station 12 is, for example, a radio unit (RU) in the 5G communication standard. The wireless station 12 is one aspect of another device.

[0013] If the radio station 12 has multiple antennas, the radio station 12 may perform wireless communication with one or more terminals 11 using beamforming. The radio station 12 transitions to a sleep state in accordance with a sleep instruction transmitted from the management control device 20. The sleep state is a state in which power saving is possible by stopping some functions or stopping the entire device. Furthermore, the radio station 12 controls the optical path in accordance with an optical path control instruction transmitted from the management control device 20. An optical path is a route along which an optical signal propagates. The optical path control instruction is an instruction related to optical path control, and includes, for example, an instruction to start setting up an optical path and an instruction to stop setting up an optical path. For example, the radio station 12 stops setting up an optical path with the transfer device 14 in response to receiving the optical path control instruction. Stopping the setting up of an optical path in the radio station 12 means not emitting light on the path from the radio station 12 to the transfer device 14 (stopping light emission).

[0014] The transfer device 14 is provided between the radio station 12 and the central station 16. The transfer device 14 is a switch that connects the radio station 12 and the central station 16 via an optical path. The transfer device 14 controls the optical path in accordance with control instructions (hereinafter referred to as "optical path control information") related to the optical path transmitted from the management control device 20. For example, the optical path control performed by the transfer device 14 includes switching of the optical path and formation of a new optical path. The transfer device 14 controls the connection between the radio station 12 and the central station 16 by controlling the optical path. For example, upon receiving optical path control information for the optical path transmitted from the management control device 20, the transfer device 14 performs switching so that the optical path is connected between the radio station 12, which is the switching destination of the optical path, and the central station 16.

[0015] The central station 16 receives uplink signals transmitted from one or more wireless stations 12 via the transfer device 14. The central station 16 transmits downlink signals to the wireless stations 12 connected via the transfer device 14. The uplink signals transmitted from one or more wireless stations 12 are signals transmitted by the terminal 11, and the downlink signals are signals addressed to the terminal 11. Each central station 16 transitions to a sleep state in accordance with a sleep instruction transmitted from the management control device 20. The central station 16 is, for example, a distributed unit (DU) in the 5G communication standard. Information acquired by the management control device 20 from the central station 16 is called cooperation information. The cooperation information is information indicating the state of communication between each central station 16 and one or more terminals 11. The central station 16 is one aspect of a communication station.

[0016] The coordination information in the first embodiment includes, for example, information on the traffic volume of each central office 16. Hereinafter, the traffic volume information is referred to as traffic information. Note that, for example, traffic information is described in DCI (Downlink Control Information) or O-RAN CTI (O-RAN.WG4.CTI-TCP.0-v01.00). In the O-RAN CTI, it refers to schedule information. Furthermore, the central office 16 controls the optical paths in accordance with the optical path control instructions transmitted from the management and control device 20. For example, the central office 16 stops setting up the optical path between the central office 16 and the transfer device 14 in response to receiving the optical path control instruction. Stopping the setting up of the optical path in the central office 16 means not irradiating light on the path from the central office 16 to the transfer device 14 (stopping the optical irradiation).

[0017] The management control device 20 is a device that manages the entire mobile NW system. The management control device 20 acquires coordination information from each central station 16. The management control device 20 uses a coordination interface when acquiring coordination information from each central station 16. The coordination interface is an interface that connects the management control device 20 and each central station 16. The management control device 20 determines whether optical path control and sleep control are necessary based on the acquired coordination information. For example, if the management control device 20 determines that sleep control is necessary, it determines that optical path control is necessary. If the management control device 20 determines that optical path control and sleep control are necessary, it performs optical path control processing and sleep control processing. The optical path control processing is processing that switches optical paths between the radio stations 12 and the central station 16 and generates optical paths. The sleep control processing is processing that executes sleep or cancels sleep for each radio station 12 and each central station 16 that are subject to sleep control.

[0018] The transfer device 14 and the management control device 20 are installed in a section called a mobile front haul (MFH). The central station 16 may be regarded as an aggregation station, the radio stations 12 as distributed stations, and the transfer device 14 and the management control device 20 may be regarded as being installed in a mobile mid haul (MMH).

[0019] Next, an overview of the processing of the mobile network system will be explained. The upper diagram of Fig. 1 shows the connection state of the mobile network system before optical path switching, and the lower diagram of Fig. 1 shows the connection state of the mobile network system after optical path switching. The upper diagram of Fig. 1 shows an example in which terminals 11-1 and 11-2 are connected to wireless station 12-1, wireless station 12-1 is connected to central station 16-1 via transfer device 14, terminals 11-3 and 11-4 are connected to wireless station 12-M, and wireless station 12-M is connected to central station 16-N via transfer device 14.

[0020] The management and control device 20 determines, based on the cooperation information collected from each central office 16, that sleep control is necessary when one central office 16 can accommodate the traffic of the other central offices 16. That is, based on the cooperation information collected from each central office 16, the management and control device 20 performs optical path control processing and sleep control processing when one central office 16 can accommodate the traffic of the other central offices 16. For example, the management and control device 20 performs optical path control processing and sleep control processing in central office 16-N when all of the traffic of central office 16-1 can be accommodated. In this way, by accommodating the traffic of the other central offices 16 in one central office 16, the other central offices 16 that no longer have traffic can transition to a sleep state.

[0021] When performing optical path control processing, the management control device 20 transmits information on the optical path switching destination to the transfer device 14, and instructs the radio station 12 and the central station 16, which are the targets of optical path switching, to switch the optical path. For example, the management control device 20 transmits information on the optical path switching destination to the transfer device 14, for switching the optical path between the radio station 12-1 and the central station 16-1 to the optical path between the radio station 12-M and the central station 16-N, and instructs the radio station 12-1 and the central station 16-1, which are the targets of optical path switching, to switch the optical path.

[0022] Since the connection destination of the terminal 11 changes due to the switching of the optical path, the management control device 20 may instruct the central station 16, which is the target of the optical path switching, to change the connection. The transfer device 14 switches the optical path between the radio station 12 and the central station 16 in accordance with the instruction from the management control device 20. After the optical path switching is completed, the transfer device 14 notifies the management control device 20 of the completion of the optical path switching. The radio station 12 and the central station 16, which are the target of the optical path switching, switch the optical path in accordance with the instruction from the management control device 20.

[0023] When the optical path control process is completed, the management control device 20 transmits a sleep permission notification to the radio stations 12 and the central station 16 that are to be transitioned to the sleep state. The sleep permission notification is a signal that includes an instruction to transition the radio stations 12 and the central station 16 to the sleep state. As a result, the radio stations 12 and the central station 16 that are to be transitioned to the sleep state transition to the sleep state.

[0024] 1 shows an example in which terminals 11-1 to 11-4 are connected to wireless station 12-M, and wireless station 12-1 and central station 16-1 are in a sleep state. Hereinafter, the wireless station 12 and central station 16 that are the targets of optical path switching may be referred to as a switching source wireless station and a switching source central station, respectively, and the wireless station 12 and central station 16 that are the destination of optical path switching may be referred to as a switching destination wireless station and a switching destination central station, respectively.

[0025] Next, a method for selecting a central station 16 to be put into sleep mode in the first embodiment will be described. Here, the differences between the conventional method and the present invention will be explained. FIG. 2 is a diagram illustrating a conventional method for selecting a central station to be put into sleep mode. In FIG. 2, central stations 1 to 4 are used as an example. FIG. 2A shows traffic information collected from each of central stations 1 to 4. Conventionally, when performing sleep control, the traffic volumes of the central stations are summed in order without reference to the traffic volume of each station, and then compared with a threshold. For example, in the example shown in FIG. 2B, the sum of the traffic volumes of central station 1 and central station 2 is compared with the threshold. As shown in FIG. 2B, the sum is less than the threshold, so the management control device determines central station 2 to be put into sleep mode, as shown in FIG. 2C.

[0026] The management control device then sums the traffic volume of central station 3 with that of central station 1, as shown in Fig. 2(D), and compares the sum with a threshold. For example, in the example shown in Fig. 2(D), the total value obtained by adding together the traffic volumes of central station 1, central station 2, and central station 3 is compared with the threshold. As shown in Fig. 2(D), the total value exceeds the threshold, so the management control device determines that central station 3 cannot go to sleep.

[0027] Next, the management control device sums the traffic volume of central station 4 to that of central station 1 and compares the sum with a threshold, as shown in Fig. 2(E). For example, in the example shown in Fig. 2(E), the total value obtained by adding together the traffic volumes of central station 1, central station 2, and central station 4 is compared with the threshold. As shown in Fig. 2(E), the total value exceeds the threshold, so the management control device determines that central station 4 cannot go to sleep.

[0028] As a result, in the conventional method of selecting a central station to be put to sleep, only central station 2 is selected as the sleep target. However, as can be seen from FIG. 2 , the traffic volume of central stations 3 and 4 is relatively small, and even if the traffic of central stations 3 and 4 is consolidated into central station 1, the traffic volume does not exceed the threshold. Therefore, if the traffic of central stations 3 and 4 is consolidated into central station 1, both central stations 3 and 4 can be selected as the sleep targets. In this way, by focusing on the traffic volume when selecting the sleep target, it is believed that the sleep target can be selected more efficiently.

[0029] FIG. 3 is a diagram illustrating a method for selecting a central station to be put into sleep mode in the first embodiment. Similar to FIG. 2, FIG. 3 uses central stations 1 to 4 as an example. (A) in FIG. 3 shows traffic information collected from each of central stations 1 to 4. The management and control device 20 in the first embodiment sorts central stations 1 to 4 in descending order of traffic volume identified by the traffic information. As a result, as shown in (B) in FIG. 3, the order is central station 3, central station 4, central station 2, and central station 1.

[0030] Then, as shown in FIG. 3D, the management control device 20 adds the traffic volumes of the central station 3 with the lowest traffic volume in ascending order. In this case, the management control device 20 adds the traffic volumes of the central station 4 with the second lowest traffic volume in ascending order until the threshold value is not exceeded. Specifically, the management control device 20 first adds the traffic volume of the central station 4 with the second lowest traffic volume to the traffic volume of the central station 3 with the highest traffic volume, and compares the result with the threshold value. In this case, the management control device 20 compares the total value obtained by adding the traffic volumes of the central station 3 and the central station 4 with the threshold value. Since the total value is less than the threshold value, the management control device next adds the traffic volume of the central station 2 with the third lowest traffic volume to the traffic volume of the central station 3.

[0031] In this case, the management control device 20 compares the total value obtained by adding together the traffic volumes of central station 3, central station 4, and central station 2 with the threshold. Because the total value is less than the threshold, the management control device next adds the traffic volume of central station 1, which has the fourth lowest traffic volume, to central station 3. In this case, the management control device 20 compares the total value obtained by adding together the traffic volumes of central station 3, central station 4, central station 2, and central station 1 with the threshold. Because the total value exceeds the threshold, the management control device 20 selects sleep targets based on the traffic volume added up before the threshold was exceeded.

[0032] For example, the management control device 20 selects a sleep target from among central stations 3, 4, and 2, which are sleep candidate targets, based on the traffic volume added up before the threshold was exceeded. Central station 1 is not a sleep candidate because the total value of the added traffic volume has exceeded the threshold. Next, the management control device 20 determines which central station will be the aggregation destination from among central stations 3, 4, and 2. For example, the management control device 20 may determine as the aggregation destination central station the central station with the largest traffic volume among the added traffic volumes that do not exceed the threshold.

[0033] The method for determining the central station to be the aggregation destination is not limited to the above method, and other methods may be used. For example, the management control device 20 may determine the central station with the second largest traffic volume among the traffic volumes totaled within a range that does not exceed a threshold as the central station to be the aggregation destination. In the following explanation, an example will be given in which the management control device 20 determines the central station with the largest traffic volume among the traffic volumes totaled within a range that does not exceed a threshold as the central station to be the aggregation destination. In this case, the management control device 20 determines central station 2 as the central station to be the aggregation destination.

[0034] Then, as shown in FIG. 3D, the management control device 20 selects central stations 3 and 4, which are candidate central stations for sleep other than the aggregation destination, as the central stations to be put to sleep from among central stations 3, 4, and 2. Then, as shown in FIG. 3E, the management control device 20 sorts the central stations in descending order of traffic volume. Thus, in the method of selecting central stations to be put to sleep in the first embodiment, central stations with low traffic volume are prioritized as the sleep target, so more central stations can be put to sleep. As a result, power savings can be achieved compared to conventional methods.

[0035] The above is the method for selecting a sleep target in the first embodiment. Next, we will explain the method for selecting a central station 16 to be woken up in the first embodiment. Here, we will explain the differences between the conventional method and the present invention. FIG. 4 is a diagram for explaining the conventional method for selecting a central station to be woken up. In FIG. 4, central stations 1 to 4 are used as an example. As shown in FIG. 4A, central stations 2 to 4 are assumed to be in a sleep state. If the traffic volume of central station 1 exceeds the threshold, the management control device determines to wake up the sleep state. In this case, the management control device wakes up the sleep state of the central station, starting with the central station with the most recently added traffic volume, as shown in FIG. 4B.

[0036] For example, the management control device determines the central stations to be woken up in order of the most recently added traffic volume, such as central station 4, central station 3, etc., so that the traffic volume of central station 1 is less than the threshold. As a result, in the conventional method of selecting the central station to be woken up, as shown in Figure 4C, central stations 3 and 4 are determined to be woken up, and only central station 2 continues to be in sleep mode. However, as can be seen from Figure 4, the traffic volumes of central stations 3 and 4 are relatively low, while the traffic volume of central station 2 is high. In this case, if central station 2 is determined to be woken up, the other central stations can continue to be in sleep mode. In this way, it is believed that determining the wake-up target based on traffic volume can more efficiently determine the wake-up target.

[0037] FIG. 5 is a diagram illustrating a method for selecting a central station to be released from sleep mode in the first embodiment. In FIG. 5, as in FIG. 4, central stations 1 to 4 are used as an example. As shown in FIG. 5A, central stations 2 to 4 are assumed to be in a sleep state. If the traffic volume of central station 1 exceeds a threshold, the management control device 20 determines to release the central station from sleep mode. In this case, the management control device 20 identifies the central station with the largest traffic volume (including a sleeping central station) among the traffic volumes of central station 1. Alternatively, the management control device 20 may identify the central station with the largest traffic volume by targeting only sleeping central stations. The traffic volume of central station 1 is excluded from the target.

[0038] Here, the traffic volume is assumed to be smallest among central stations 2, 3, and 4 (central station 2 has the largest traffic volume, and central station 4 has the smallest traffic volume). In this case, the management control device 20 identifies central station 2 as the central station with the largest traffic volume. The management control device 20 then determines the identified central station 2 as the sleep-wake target. The management control device 20 then distributes the traffic of central station 1 to central station 2, the identified sleep-wake target. As a result, when the traffic volume of central station 1 falls below the threshold, the management control device 20 terminates the selection of the sleep-wake target. As a result, in the method for selecting a sleep-wake target according to the first embodiment, central station 2 is determined as the sleep-wake target, and the two central stations 3 and 4 continue to be in the sleep state, as shown in FIG. 5C . In this way, the method for selecting a sleep-wake target according to the first embodiment prioritizes central stations with large traffic volumes as the sleep-wake target, so that fewer central stations can be selected as the sleep-wake target. As a result, the number of central stations that continue to be in the sleep state can be increased compared to the conventional method, thereby achieving power savings.

[0039] A specific configuration for selecting a sleep target and a sleep release target as described above will be described below.

[0040] (Details of the First Embodiment) Fig. 6 is a diagram showing an example of the configuration of a mobile network system 100 according to the first embodiment. The mobile network system 100 according to the first embodiment includes a plurality of wireless stations 12-1 to 12-M, a transfer device 14, a plurality of central stations 16-1 to 16-N, and a management and control device 20. The wireless stations 12, the transfer device 14, and the central station 16 have been described in Fig. 1, and therefore further description thereof will be omitted.

[0041] The management control device 20 includes a cooperation information collection unit 21, an analysis unit 22, and a control unit 23. The cooperation information collection unit 21 includes an acquisition unit 211. The acquisition unit 211 collects cooperation information from each central station 16 at a predetermined interval or at any timing. For example, the acquisition unit 211 collects traffic information of each central station 16 as cooperation information.

[0042] The analysis unit 22 includes a coordination information storage unit 221 and a real-time analysis unit 222. The coordination information storage unit 221 records the collected coordination information in a predetermined storage device. The real-time analysis unit 222 analyzes the state of communication between each central office 16 and the terminal 11 based on the coordination information. Specifically, the real-time analysis unit 222 determines whether optical path control and sleep control are necessary based on the coordination information.

[0043] For example, the real-time analysis unit 222 determines that optical path control and sleep control are necessary when all terminals 11 accommodated by one central office 16 can be accommodated in one of the central offices 16. In this case, the real-time analysis unit 222 notifies the control unit 23 of control information including an optical path control instruction and a sleep instruction. The optical path control instruction is an instruction to request optical path switching, and includes, for example, information indicating the central office 16 that is the source of the optical path switching and information indicating the central office 16 that is the destination of the optical path switching. The sleep instruction is an instruction to execute sleep, and includes, for example, information indicating the radio station 12 and central office 16 that are to be put into sleep mode. The method of selecting the sleep target in the real-time analysis unit 222 is as described in FIG. 3.

[0044] Furthermore, when the traffic volume of a certain central station 16 exceeds a threshold, the real-time analysis unit 222 determines that optical path control and sleep control are necessary. In this case, the real-time analysis unit 222 notifies the control unit 23 of control information including an optical path control instruction and a sleep release instruction. The sleep release instruction is an instruction to release the sleep state, and includes, for example, information indicating the wireless station 12 and central station 16 to be released from sleep. The method of selecting the sleep release target in the real-time analysis unit 222 is as described in FIG. 5.

[0045] The control unit 23 includes an optical path control unit 231 and a sleep control unit 232. The optical path control unit 231 determines the radio station 12 and central station 16 that will be the source of optical path switching and the radio station 12 and central station 16 that will be the destination of optical path switching based on the analysis results of the real-time analysis unit 222. For example, the optical path control unit 231 determines the radio station 12 and central station 16 that will be the source of optical path switching based on information indicating the central station 16 that will be the source of optical path switching, which is included in the control information notified from the real-time analysis unit 222. For example, the optical path control unit 231 determines the radio station 12 and central station 16 that will be the destination of optical path switching based on information indicating the central station 16 that will be the destination of optical path switching, which is included in the control information notified from the real-time analysis unit 222. The optical path control unit 231 holds information about the radio stations 12 connected to the central station 16.

[0046] The optical path control unit 231 transmits optical path control information including information indicating the radio station 12 and central station 16 to which the determined optical path is to be switched to the transfer device 14. As a result, the optical path control unit 231 instructs the transfer device 14 to switch the optical path. Furthermore, the optical path control unit 231 transmits an optical path control instruction to the radio station 12 and central station 16 to which the determined optical path is to be switched.

[0047] Based on the analysis results of the real-time analysis unit 222, the sleep control unit 232 causes the wireless stations 12 and the central station 16 that are the targets of sleep control to enter or exit sleep mode.

[0048] 7 is a flowchart showing an example of the flow of sleep processing executed by the management control device 20 in the first embodiment. The processing in FIG. 7 is repeatedly executed at a predetermined cycle. Here, traffic information will be used as an example of the cooperation information. In FIG. 7, the explanation will be given assuming M=N=4.

[0049] The acquisition unit 211 acquires cooperation information from each of the central stations 16-1 to 16-4 (step S101). For example, the acquisition unit 211 may collect information once per unit time, which is a predetermined cycle, or may collect information at any timing. The unit time here refers to, for example, a slot length, a subframe length, a frame length, 1 millisecond, 1 second, or 1 minute. The acquisition unit 211 stores the acquired cooperation information for each central station 16 in the cooperation information storage unit 221 (step S102).

[0050] The real-time analysis unit 222 calculates the traffic volume of each of the central stations 16-1 to 16-4 based on the cooperation information for each central station 16 stored in the cooperation information storage unit 221. Then, the real-time analysis unit 222 sorts the central stations 16-1 to 16-4 in ascending order of the calculated traffic volumes (step S103).

[0051] The real-time analysis unit 222 determines an addition target A for the traffic volume (step S104). The addition target A is, for example, the central station 16 with the smallest traffic volume. In the example of FIG. 3, the addition target A is central station 3. Next, the real-time analysis unit 222 determines an addition target B for the traffic volume (step S105). The addition target B is, for example, the central station 16 with the second smallest traffic volume. In the example of FIG. 3, the addition target A is central station 4. The real-time analysis unit 222 adds up the traffic volume of addition target A and the traffic volume of addition target B to obtain a traffic volume addition value T ｔｏｔａｌ is calculated (step S106).

[0052] The real-time analysis unit 222 calculates the calculated traffic volume sum T ｔｏｔａｌ The real-time analysis unit 222 compares the calculated traffic volume sum T ｔｏｔａｌ is compared with the threshold value of the central office 16 corresponding to the sum A.

[0053] The real-time analysis unit 222 calculates the traffic volume sum T ｔｏｔａｌ The real-time analysis unit 222 determines whether the traffic volume sum T ｔｏｔａｌ is not greater than the threshold (step S107—NO), the real-time analysis unit 222 adds the smallest traffic volume among the traffic volumes that have not been added, thereby obtaining a new traffic volume addition value T ｔｏｔａｌ is calculated (step S108).

[0054] After that, the real-time analysis unit 222 executes the process of step S107 again. In this case, the real-time analysis unit 222 calculates the newly calculated traffic volume sum T ｔｏｔａｌ The real-time analysis unit 222 determines whether the traffic volume sum T ｔｏｔａｌ is greater than the threshold (step S107—YES), the real-time analysis unit 222 determines the central station 16 to which the traffic volume is to be aggregated (step S108). Specifically, the real-time analysis unit 222 determines the central station 16 with the largest traffic volume from among the central stations 16 whose traffic volumes were added up before the threshold was exceeded as the central station 16 to which the traffic volume is to be aggregated (step S109).

[0055] For example, if the central stations 16 having the respective traffic volumes added up before exceeding the threshold are the central stations 16-1 to 16-3, the real-time analysis unit 222 selects the central station 16 with the largest traffic volume from among the central stations 16-1 to 16-3 as the central station 16 to be aggregated. Here, it is assumed that the central station 16-1 is selected as the aggregation destination.

[0056] Thereafter, the real-time analysis unit 222 notifies the control unit 23 of control information including an optical path control instruction and a sleep instruction. The real-time analysis unit 222 includes, for example, information indicating that the central stations from which the switching is to be performed are the central stations 16-2 and 16-3 and information indicating that the central station to which the switching is to be performed is the central station 16-1 in the optical path control instruction. The real-time analysis unit 222 includes, for example, information indicating that the central stations to be put to sleep are the central stations 16-2 and 16-3, information indicating the wireless station 12 connected to the central station 16-2, and information indicating the wireless station 12 connected to the central station 16-3.

[0057] The optical path control unit 231 determines the central office 16 that will be the source of the optical path switching and the central office 16 that will be the destination of the optical path switching, based on the optical path control instructions included in the control information notified from the real-time analysis unit 222. Here, the optical path control unit 231 determines the central office 16-1 as the destination of the optical path switching, and determines the central offices 16-2 and 16-3 as the source of the optical path switching. The optical path control unit 231 transmits optical path control information to the transfer device 14, including information indicating the destination central office and source central office of the determined optical path switching (step S110).

[0058] As a result, the transfer device 14 switches the optical path route by switching the optical paths heading to the central stations 16-2 and 16-3 to those heading to the central station 16-1. Furthermore, the optical path control unit 231 transmits an optical path control instruction to the switching source central station of the determined optical path and the radio stations 12 connected to the switching source central station (step S111).

[0059] The sleep control unit 232 determines the wireless stations 12 and central stations 16 to be put to sleep based on the sleep instruction included in the control information notified by the real-time analysis unit 222. Here, the sleep control unit 232 determines the wireless stations 12 connected to the central station 16-2, and the wireless stations 12 connected to the central station 16-3 as the sleep targets. The sleep control unit 232 transmits a sleep instruction to each of the determined devices (step S112). This allows the sleep target devices to transition to a sleep state.

[0060] 7 shows a configuration in which sleep control is performed after optical path switching control is performed, but optical path switching control may be performed after sleep control is performed. Furthermore, the process of step S111 may be performed by the optical path switching function of the transfer device 14.

[0061] 8 is a flowchart showing an example of the flow of a sleep release process executed by the management control device 20 in the first embodiment. Note that, here, traffic information will be used as an example of the linkage information. In FIG. 8, the description will be given assuming M=N=4.

[0062] The acquisition unit 211 acquires cooperation information from each of the central stations 16-1 to 16-4 (step S201). The acquisition unit 211 stores the acquired cooperation information for each central station 16 in the cooperation information storage unit 221.

[0063] The real-time analysis unit 222 reads the linkage information for each central station 16 stored in the linkage information storage unit 221 (step S202). Based on the linkage information for each central station 16, the real-time analysis unit 222 calculates the traffic volume for each of the central stations 16-1 to 16-4 (step S203). The real-time analysis unit 222 compares the traffic volume for each of the central stations 16-1 to 16-4 with a threshold. The threshold used here may be the same as or different from the threshold used in FIG. 7 .

[0064] The real-time analysis unit 222 determines whether there is a central station 16 whose traffic volume exceeds the threshold (step S204). If the real-time analysis unit 222 determines that there is no central station 16 whose traffic volume exceeds the threshold (step S204-NO), the management control device 20 ends the processing of FIG.

[0065] On the other hand, if the real-time analysis unit 222 determines that there is a central station 16 whose traffic volume exceeds the threshold (step S204—YES), the real-time analysis unit 222 determines which central station 16 is to be woken up from sleep mode (step S205). Here, let us assume that the central station 16 whose traffic volume exceeds the threshold is the central station 16-1. The real-time analysis unit 222 identifies the other central station 16 with the highest traffic volume aggregated at the central station 16-1 from among the sleeping central stations 16-2 to 16-4. The following two methods can be used to identify this central station 16.

[0066] (Identification Method 1) Assuming that the terminal 11 will return its connection to the original central office 16, the real-time analysis unit 222 first calculates the traffic volume of the terminal 11 and calculates the traffic volume of the sleeping central office 16. The real-time analysis unit 222 then identifies the central office 16 with the largest traffic volume among the calculated traffic volumes as the other central office 16 with the largest traffic volume among the traffic volumes aggregated at the central office 16-1.

[0067] (Identification Method 2) First, the real-time analysis unit 222 predicts the central office 16 to which the terminal 11 will connect after waking up from sleep mode, based on the location of the terminal 11. Next, the real-time analysis unit 222 calculates the traffic volume of the sleeping central office 16 based on the prediction result. Then, the real-time analysis unit 222 identifies the central office 16 with the largest traffic volume among the calculated traffic volumes as the other central office 16 with the largest traffic volume among the traffic volumes aggregated at the central office 16-1.

[0068] Assume that the central station 16-2 is identified as the other central station 16 with the highest traffic volume by one of the above identification methods. The real-time analysis unit 222 determines the identified central station 16-2 as the central station 16 to be woken up. The real-time analysis unit 222 then notifies the control unit 23 of control information including an optical path control instruction and a sleep wake-up instruction. For example, the real-time analysis unit 222 includes in the optical path control instruction information indicating that the central station to be switched to is the central station 16-2. For example, the real-time analysis unit 222 includes information indicating that the central station to be woken up is the central station 16-2 and information indicating the wireless station 12 to be woken up.

[0069] The optical path control unit 231 determines the central office 16 that will be the control target of the optical path based on the optical path control instruction included in the control information notified from the real-time analysis unit 222. Here, the optical path control unit 231 determines the central office 16-2 as the control target of the optical path. The optical path control unit 231 transmits optical path control information including information indicating the central office that will be the control target of the determined optical path to the transfer device 14 (step S206). As a result, the transfer device 14 forms an optical path toward the central office 16-2.

[0070] The sleep control unit 232 determines the wireless stations 12 and the central station 16 to be released from sleep mode based on the release instruction included in the control information notified by the real-time analysis unit 222. Here, the sleep control unit 232 determines the central station 16-2 and the wireless station 12 connected to the central station 16-2 as the release targets. The sleep control unit 232 transmits a release instruction to each of the determined devices (step S207). This allows the devices to be released from sleep mode.

[0071] The mobile network system 100 configured as described above includes a cooperation information collection unit 21 that acquires cooperation information from multiple central stations 16, and an analysis unit 22 that determines one or more central stations 16 to be subject to sleep control from among the multiple central stations 16 based on the results of sorting the multiple central stations 16 based on the cooperation information, and executes sleep control on the one or more central stations 16 that are subject to sleep control. This allows the sleep control to be determined taking into account the cooperation information obtained from each central station 16. This makes it possible to increase the effect of power saving without degrading communication quality.

[0072] More specifically, the mobile network system 100 collects traffic information from each central station 16 as linkage information. The real-time analysis unit 222 sorts the multiple central stations 16 in ascending order of traffic volume based on the collected traffic information from each central station 16. After sorting the multiple central stations 16, the real-time analysis unit 222 adds up the traffic volumes in ascending order until the traffic volume exceeds a threshold. The real-time analysis unit 222 determines the central station 16 with the largest traffic volume from among the central stations 16 from which the traffic volume added up until the traffic volume exceeds the threshold as the aggregation destination, and determines the central stations 16 other than the aggregation destination as sleep targets. In this way, by adding up the traffic volumes in ascending order, more traffic can be aggregated to a single central station 16. As a result, more central stations 16 can be put into sleep mode. This increases the power saving effect.

[0073] (Variation 1 of the First Embodiment) In the above-described embodiment, a configuration has been shown in which the management and control device 20 performs optical path control processing and sleep control processing. In contrast, a forwarding device may be configured to perform optical path control processing and sleep control processing. FIG. 9 is a diagram showing an example configuration of a mobile NW system 100a in Variation 1 of the first embodiment. The mobile NW system 100a includes multiple wireless stations 12-1 to 12-M, a forwarding device 14, multiple central stations 16-1 to 16-N, and a management and control device 20a.

[0074] 9, the transfer device 14 includes a control unit 23, while the management control device 20a does not include a control unit 23. The real-time analysis unit 222 of the management control device 20a notifies the transfer device 14 of control information. Note that the real-time analysis unit 222 may notify the transfer device 14 of control information only when optical path control and sleep control are performed. The control unit 23 of the transfer device 14 performs optical path control processing and sleep control processing based on the control information notified from the management control device 20a.

[0075] The control unit 23 of the transfer device 14 includes an optical path control unit 231 and a sleep control unit 232. The optical path control unit 231 performs the same processing as the optical path control unit 231 described above. The sleep control unit 232 performs the same processing as the sleep control unit 232 described above.

[0076] (Variation 2 of the First Embodiment) In the above-described embodiment, a configuration has been shown in which the management control device 20 performs optical path control processing and sleep control processing. Alternatively, a configuration may be adopted in which the management control device performs sleep control processing and the forwarding device performs optical path control processing. FIG. 10 is a diagram showing an example configuration of a mobile NW system 100b in Variation 2 of the first embodiment. The mobile NW system 100b includes multiple radio stations 12-1 to 12-M, a forwarding device 14b, multiple central stations 16-1 to 16-N, and a management control device 20b.

[0077] 10 , the transfer device 14b includes a control unit 141. The control unit 141 includes an optical path control unit 231. The control unit 23b of the management control device 20b includes a sleep control unit 232. The real-time analysis unit 222 of the management control device 20b notifies the transfer device 14b of control information including information indicating the central station 16 that is the source of the optical path switching and information indicating the central station 16 that is the destination of the optical path switching, and notifies the control unit 23b of control information including information indicating the radio station 12 and the central station 16 that are the targets of sleep control.

[0078] The real-time analysis unit 222 may notify the control information only when optical path control and sleep control are performed. The control unit 141 of the transfer device 14b performs optical path control processing based on the control information notified from the management control device 20b. The control unit 23b of the management control device 20b performs sleep control processing based on the control information notified from the real-time analysis unit 222. The optical path control unit 231 included in the control unit 141 of the transfer device 14b performs processing similar to that of the optical path control unit 231 described above.

[0079] (Variation 3 of the First Embodiment) In the above-described embodiment, a configuration has been shown in which the management control device 20 performs optical path control processing and sleep control processing. In contrast, the optical path control processing and sleep control processing may be performed by different devices. FIG. 11 is a diagram showing a configuration example of a mobile NW system 100c in Variation 3 of the first embodiment. The mobile NW system 100c includes multiple radio stations 12-1 to 12-M, a forwarding device 14, multiple central stations 16-1 to 16-N, an optical transmission management control device 65, and a wireless transmission management control device 70. As shown in FIG. 11, the mobile NW system 100c includes the optical transmission management control device 65 and the wireless transmission management control device 70 instead of the management control device 20.

[0080] The optical transmission management control device 65 controls the optical transmission section. The optical transmission management control device 65 includes a cooperation information collection unit 21, an analysis unit 22, and a control unit 66. The cooperation information collection unit 21 and the analysis unit 22 perform the same processes as the cooperation information collection unit 21 and the analysis unit 22 provided in the management control device 20 described above. The control unit 66 includes an optical path control unit 231. The optical path control unit 231 performs the same processes as the optical path control unit 231 provided in the management control device 20 described above.

[0081] The wireless transmission management control device 70 controls the wireless transmission section. The wireless transmission management control device 70 includes a control unit 71. The control unit 71 includes a sleep control unit 232. The sleep control unit 232 performs the same processing as the sleep control unit 232 included in the management control device 20 described above.

[0082] The real-time analysis unit 222 of the optical transmission management control device 65 transmits control information including information indicating the radio stations 12 and the central station 16 that are subject to sleep control to the radio transmission management control device 70. Based on the control information transmitted from the optical transmission management control device 65, the radio transmission management control device 70 causes the radio stations 12 and the central station 16 that are subject to sleep control to put into sleep mode or to cancel sleep mode.

[0083] With this configuration, different processes such as optical path switching and sleep control can be performed by a plurality of devices, thereby reducing the amount of processing performed by a single device.

[0084] (Variation 4 of the First Embodiment) In the above-described embodiment, the configuration has been described in which the management control device 20 performs optical path control processing and sleep control processing. However, the optical path control processing and sleep control processing may be performed by different devices. FIG. 12 is a diagram showing an example configuration of a mobile NW system 100d in Variation 4 of the first embodiment. The mobile NW system 100d includes multiple radio stations 12-1 to 12-M, a forwarding device 14, multiple central stations 16-1 to 16-N, an optical transmission management control device 65, and a wireless transmission management control device 70. As shown in FIG. 12, the mobile NW system 100d includes the optical transmission management control device 65 and the wireless transmission management control device 70 instead of the management control device 20.

[0085] The optical transmission management control device 65 shown in Fig. 12 controls the optical transmission section. The optical transmission management control device 65 shown in Fig. 12 includes a control unit 66. The control unit 66 includes an optical path control unit 231. The optical path control unit 231 performs the same processing as the optical path control unit 231 included in the management control device 20 described above.

[0086] The wireless transmission management control device 70 shown in Fig. 12 controls the wireless transmission section. The wireless transmission management control device 70 shown in Fig. 12 includes a cooperation information collection unit 21, an analysis unit 22, and a control unit 71. The cooperation information collection unit 21 and the analysis unit 22 perform the same processes as the cooperation information collection unit 21 and the analysis unit 22 provided in the management control device 20 described above. The control unit 71 includes a sleep control unit 232. The sleep control unit 232 performs the same processes as the sleep control unit 232 provided in the management control device 20 described above.

[0087] The real-time analysis unit 222 of the wireless transmission management control device 70 transmits control information including information indicating the central office 16 from which the optical path is switched and information indicating the central office 16 to which the optical path is switched to, to the optical transmission management control device 65. The optical transmission management control device 65 switches the optical path based on the control information transmitted from the wireless transmission management control device 70.

[0088] With this configuration, different processes such as optical path switching and sleep control can be performed by a plurality of devices, thereby reducing the amount of processing performed by a single device.

[0089] (Fifth Modification of the First Embodiment) The mobile network system 100c shown in Fig. 11 may be configured as shown in Fig. 13. Fig. 13 is a diagram showing a configuration example of a mobile network system 100e in a fifth modification of the first embodiment. The mobile network system 100e includes a plurality of radio stations 12-1 to 2-M, a transfer device 14, a plurality of central stations 16-1 to 16-N, an optical transmission management controller 65, a radio transmission management controller 70, and an orchestrator 75. As shown in Fig. 13, the mobile network system 100e further includes the orchestrator 75 in addition to the mobile network system 100c.

[0090] The orchestrator 75 is provided above the optical transmission management control device 65 and the wireless transmission management control device 70, and is a higher-level device that controls the optical transmission management control device 65 and the wireless transmission management control device 70. The orchestrator 75 transfers signals between the optical transmission management control device 65 and the wireless transmission management control device 70. The orchestrator 75 includes a signal transfer unit 751. The signal transfer unit 751 receives control information addressed to the wireless transmission management control device 70 and transmitted from the optical transmission management control device 65. The signal transfer unit 751 transfers the received control information to the wireless transmission management control device 70.

[0091] The optical transmission management control device 65 performs the same processing as the optical transmission management control device 65 shown in Fig. 11 except that it transmits control information addressed to the wireless transmission management control device 70 to the orchestrator 75. The wireless transmission management control device 70 performs the same processing as the wireless transmission management control device 70 shown in Fig. 11 except that it receives control information from the orchestrator 75.

[0092] (Variation 6 of the First Embodiment) The mobile NW system 100d shown in Fig. 12 may be configured as shown in Fig. 14. Fig. 14 is a diagram showing a configuration example of a mobile NW system 100f in Variation 6 of the first embodiment. The mobile NW system 100f includes a plurality of radio stations 12-1 to 12-M, a transfer device 14, a plurality of central stations 16-1 to 16-N, an optical transmission management controller 65, a radio transmission management controller 70, and an orchestrator 75. As shown in Fig. 14, the mobile NW system 100f further includes the orchestrator 75 in addition to the mobile NW system 100d.

[0093] The orchestrator 75 is provided above the optical transmission management control device 65 and the wireless transmission management control device 70, and is a higher-level device that controls the optical transmission management control device 65 and the wireless transmission management control device 70. The orchestrator 75 transfers signals between the optical transmission management control device 65 and the wireless transmission management control device 70. The orchestrator 75 includes a signal transfer unit 751. The signal transfer unit 751 receives control information addressed to the optical transmission management control device 65 and transmitted from the wireless transmission management control device 70. The signal transfer unit 751 transfers the received control information to the optical transmission management control device 65.

[0094] The optical transmission management control device 65 performs the same processing as the optical transmission management control device 65 shown in Fig. 12 except that it receives control information from the orchestrator 75. The wireless transmission management control device 70 performs the same processing as the wireless transmission management control device 70 shown in Fig. 12 except that it transmits control information addressed to the optical transmission management control device 65 to the orchestrator 75.

[0095] (Seventh Modification of the First Embodiment) The mobile network system 100 may be configured as shown in FIG. 15 . FIG. 15 is a diagram illustrating a configuration example of a mobile network system 100g in a seventh modification of the first embodiment. The mobile network system 100g includes a plurality of radio stations 12-1 to 12-M, a forwarding device 14, a plurality of central stations 16-1 to 16-N, an optical transmission management controller 65, and a radio transmission management controller 70. As shown in FIG. 15 , the mobile network system 100g includes the optical transmission management controller 65 and the radio transmission management controller 70 instead of the management controller 20. The mobile network system 100g is configured such that the optical transmission management controller 65 and the radio transmission management controller 70 each receive cooperation information from each central station 16.

[0096] The optical transmission management control device 65 shown in Fig. 15 includes a cooperation information collection unit 67, an analysis unit 68, and a control unit 66. The cooperation information collection unit 67 includes an acquisition unit 671. The acquisition unit 671 performs the same processing as the acquisition unit 211 included in the management control device 20 described above. The analysis unit 68 includes a cooperation information storage unit 681 and a real-time analysis unit 682. The cooperation information storage unit 681 and the real-time analysis unit 682 perform the same processing as the cooperation information storage unit 221 and the real-time analysis unit 222 included in the management control device 20 described above. The control unit 66 includes an optical path control unit 231. The optical path control unit 231 performs the same processing as the optical path control unit 231 included in the management control device 20 described above.

[0097] The wireless transmission management control device 70 includes a cooperation information collection unit 72, an analysis unit 73, and a control unit 71. The cooperation information collection unit 72 includes an acquisition unit 721. The acquisition unit 721 performs the same processing as the acquisition unit 211 included in the management control device 20 described above. The analysis unit 73 includes a cooperation information accumulation unit 731 and a real-time analysis unit 732. The cooperation information accumulation unit 731 and the real-time analysis unit 732 perform the same processing as the cooperation information accumulation unit 221 and the real-time analysis unit 222 included in the management control device 20 described above. The control unit 71 includes a sleep control unit 232. The sleep control unit 232 performs the same processing as the sleep control unit 232 included in the management control device 20 described above.

[0098] The timing at which the optical transmission management control device 65 performs the optical path control processing and the timing at which the wireless transmission management control device 70 performs the sleep control processing may be timings determined by each device. The mobile NW system 100g may include an orchestrator 75 that controls the optical transmission management control device 65 and the wireless transmission management control device 70, and the orchestrator 75 may synchronize the timing at which the optical transmission management control device 65 performs the optical path control processing and the timing at which the wireless transmission management control device 70 performs the sleep control processing.

[0099] (Variation 8 of the First Embodiment) In the above-described configuration, the sleep control unit 232 puts both the sleep target wireless station 12 and the central station 16 to sleep, but the sleep control unit 232 may put either the sleep target wireless station 12 or the central station 16 to sleep. Furthermore, in the above-described configuration, the sleep control unit 232 wakes up both the sleep target wireless station 12 and the central station 16 to wake up, but the sleep control unit 232 may wake up either the sleep target wireless station 12 or the central station 16 to wake up.

[0100] (Ninth Modification of the First Embodiment) The cooperation information may include, for example, information regarding the number of terminals 11 accommodated by each central station 16 (hereinafter referred to as the "number of accommodated terminals"). The cooperation information may include, for example, information regarding the processing load of the central station 16 (hereinafter referred to as the "processing load information"). The processing load information may be, for example, information regarding the memory usage rate of the central station 16 or information regarding the usage rate of the CPU (Central Processing Unit). The cooperation information may include information regarding the communication quality of the terminals 11 connected to each central station 16 (hereinafter referred to as the "communication quality information"). The communication quality information may be, for example, a modulation and coding scheme (MCS), a reference signal received power (RSRP), a reference signal received quality (RSRQ), a signal-to-noise ratio (SINR), packet delay, location information, etc.

[0101] When the cooperation information includes information about the number of accommodated terminals, the real-time analysis unit 222 may use the information about the number of accommodated terminals to select a sleep control target (for example, a sleep target or a sleep release target). In this configuration, the real-time analysis unit 222 may select a central station to be subject to sleep control, in the same way as when traffic information is used.

[0102] First, the real-time analysis unit 222 sorts the central stations 16 in ascending order of the number of accommodated terminals, as identified by the information regarding the number of accommodated terminals. Then, the real-time analysis unit 222 adds up the central stations 16 with the fewest accommodated terminals, in ascending order of the number of accommodated terminals. The real-time analysis unit 222 compares the summed total with a threshold and adds up the numbers of accommodated terminals in ascending order until the threshold is exceeded. Based on the summed number of accommodated terminals before the threshold is exceeded, the real-time analysis unit 222 selects a central station 16 to be put to sleep from among the multiple central stations 16 corresponding to the summed number of accommodated terminals. Next, the real-time analysis unit 222 determines a central station to be put to sleep from among the multiple central stations 16 corresponding to the summed number of accommodated terminals. For example, the real-time analysis unit 222 determines the central station that accommodates the most terminals 11 within the summed number of accommodated terminals within the range that does not exceed the threshold as the central station to be put to sleep. Then, the real-time analysis unit 222 determines a central station 16 other than the central station 16 to be put to sleep from among the multiple central stations 16 corresponding to the summed number of accommodated terminals.

[0103] When the collaboration information includes processing load information and communication quality information, the real-time analysis unit 222 may select a sleep control target (e.g., a sleep target or a sleep release target) using the processing load information or communication quality information in addition to the traffic information. For example, when selecting a sleep control target using communication quality information in addition to traffic information, the real-time analysis unit 222 determines to perform sleep control if a condition based on the traffic information and a condition based on the communication quality information are satisfied. The condition based on the communication quality information may be, for example, a condition based on whether a path after sleep is feasible (e.g., whether quality degradation occurs). In this case, even if the real-time analysis unit 222 determines the central office 16 to be the sleep target and the central office 16 to be the optical path control target based on a condition based on traffic information, quality degradation may occur after the path switching. Therefore, even if the real-time analysis unit 222 determines the central office 16 to be the sleep target and the central office 16 to be the optical path control target based on a condition based on traffic information, the real-time analysis unit 222 may not execute sleep if quality degradation occurs on the path after optical path control.

[0104] Second Embodiment In a second embodiment, a configuration will be described in which a base station is provided in which a wireless station, a remote station, and a central station are integrated.

[0105] (Outline of the Second Embodiment) FIG. 16 is a diagram for explaining an outline of the processing of the mobile network system in the second embodiment. First, the overall configuration of the mobile network system in the second embodiment will be explained. The mobile network system in the second embodiment is an example of a communication system. The mobile network system in the second embodiment is, for example, 5G. The mobile network system in the second embodiment includes a transfer device 14, multiple base stations 17-1 to 17-M, one or more servers 19, and a management control device 20.

[0106] Optical fibers that transmit optical signals are used to connect each base station 17 and the transfer device 14, and between the transfer device 14 and the server 19. Optical fibers or electrical lines that transmit electrical signals are used to connect the transfer device 14 and the management control device 20, and between each base station 17 and the management control device 20.

[0107] 16 shows an example in which there are M base stations 17 and one server 19. There is no particular limit to the number of base stations 17 and servers 19. Note that although a plurality of transfer devices 14 may be provided, the following description will be given taking the case of one device as an example.

[0108] Each base station 17 is a device that integrates a wireless station, a remote station, and a central station. The base station 17 is equipped with one or more antennas and performs wireless communication with one or more terminals 11 located within its communication area. For example, each base station 17 transmits signals transmitted from one or more terminals 11 to the server 19 via the transfer device 14. Each base station 17 transmits signals received via the transfer device 14 to one or more terminals 11. The base station 17 transmits cooperation information to the management control device 20. The base station 17 transmits signals received via the transfer device 14 to the terminal 11.

[0109] If the base station 17 is equipped with multiple antennas, the base station 17 may perform wireless communication with one or more terminals 11 using beamforming. The base station 17 transitions to a sleep state in accordance with a sleep instruction transmitted from the management control device 20. The base station 17 releases the sleep state in accordance with a sleep release instruction transmitted from the management control device 20. Furthermore, the base station 17 switches the optical path in accordance with an optical path control instruction transmitted from the management control device 20. For example, upon receiving an optical path control instruction, the base station 17 stops setting up an optical path with the transfer device 14. Stopping the setting up of an optical path in the base station 17 means not irradiating light on the path from the base station 17 to the transfer device 14 (stopping optical irradiation). The base station 17 is one aspect of a communication station.

[0110] The transfer device 14 in the second embodiment is provided between the base station 17 and the server 19. The transfer device 14 switches the optical path in accordance with optical path control information for the optical path transmitted from the management control device 20. The transfer device 14 switches the connection between the base station 17 and the server 19 by switching the optical path. For example, when the transfer device 14 receives optical path control information for the optical path transmitted from the management control device 20, it executes switching so that the optical path is connected between the base station 17, which is the switching destination of the optical path, and the server 19.

[0111] The coordination information in the second embodiment includes, for example, traffic information of each base station 17. The traffic information is the same as that in the first embodiment. Furthermore, the base station 17 controls the optical path in accordance with an optical path control instruction transmitted from the management control device 20. When the base station 17 receives an optical path switching start instruction after receiving the optical path control instruction, it stops setting up the optical path between the base station 17 and the transfer device 14.

[0112] The management control device 20 in the second embodiment is a device that manages the entire mobile NW system. The management control device 20 acquires cooperation information from each base station 17. When acquiring cooperation information from each base station 17, the management control device 20 uses a cooperation interface. The management control device 20 determines whether optical path control and sleep control are necessary based on the acquired cooperation information. When the management control device 20 determines that optical path control and sleep control are necessary, it performs optical path control processing and sleep control processing. The optical path control processing in the second embodiment is processing that switches optical paths between the base station 17 and the forwarding device 14 and generates optical paths. The sleep control processing in the second embodiment is processing that puts the base station 17 that is the target of sleep control into sleep mode or releases sleep mode.

[0113] Next, an overview of the processing of the mobile network system will be described. The upper diagram of Fig. 16 shows the connection state of the mobile network system before optical path switching, and the lower diagram of Fig. 16 shows the connection state of the mobile network system after optical path switching. The upper diagram of Fig. 16 shows an example in which terminals 11-1 and 11-2 are connected to base station 17-1, base station 17-1 is connected to server 19 via transfer device 14, terminals 11-3 and 11-4 are connected to base station 17-M, and base station 17-M is connected to server 19 via transfer device 14.

[0114] The management control device 20 determines, based on the cooperation information collected from each base station 17, that sleep control is necessary when one base station 17 can accommodate the traffic of other base stations 17. That is, based on the cooperation information collected from each base station 17, the management control device 20 performs optical path control processing and sleep control processing when one base station 17 can accommodate the traffic of other base stations 17. For example, the management control device 20 performs optical path control processing and sleep control processing in base station 17-M when all of the traffic of base station 17-1 can be accommodated. In this way, by accommodating the traffic of other base stations 17 in one base station 17, it is possible to transition the other base stations 17 that no longer have traffic to a sleep state.

[0115] When performing optical path control processing, the management control device 20 transmits information about the optical path switching destination to the transfer device 14 and instructs the base station 17 to which the optical path is to be switched to switch the optical path. Note that, because the connection destination of the terminal 11 changes due to the optical path switching, the management control device 20 may instruct the base station 17 to which the optical path is to be switched to change the connection. The transfer device 14 switches the optical path of the base station 17 in accordance with the instruction from the management control device 20. After completing the optical path switching, the transfer device 14 notifies the management control device 20 of the completion of the optical path switching. The base station to which the optical path is to be switched switches the optical path in accordance with the instruction from the management control device 20.

[0116] When the optical path control process is completed, the management control device 20 transmits a sleep permission notification to the base station 17 that is to be transitioned to the sleep state. As a result, the base station 17 that is to be transitioned to the sleep state transitions to the sleep state. Note that in the above explanation, an example was given of a configuration in which the management control device 20 performs the sleep control process after the optical path control process is completed, but the management control device 20 may also perform the optical path control process after the sleep control process is completed. In the following explanation, an example is given of a configuration in which the sleep control process is performed after the optical path control process is completed. The lower diagram of Figure 16 shows an example in which terminals 11-1 to 11-4 are connected to base station 17-M and base station 17-1 is transitioning to the sleep state.

[0117] (Details of the Second Embodiment) Fig. 17 is a diagram showing an example of the configuration of a mobile NW system 200 in the second embodiment. The mobile NW system 200 in the second embodiment includes a transfer device 14, multiple base stations 17-1 to 17-M, one or more servers 19, and a management control device 20. The transfer device 14, the base stations 17, and the server 19 have been described in Fig. 16, so a description thereof will be omitted.

[0118] The management control device 20 includes a cooperation information collection unit 21, an analysis unit 22, and a control unit 23. The acquisition unit 211 collects cooperation information from each base station 17 at a predetermined period or at any timing. For example, the acquisition unit 211 collects traffic information of each base station 17 as cooperation information.

[0119] The analysis unit 22 includes a cooperation information storage unit 221 and a real-time analysis unit 222. The cooperation information storage unit 221 records the collected cooperation information in a predetermined storage device. The real-time analysis unit 222 analyzes the state of communication between each base station 17 and the terminal 11 based on the cooperation information. Specifically, the real-time analysis unit 222 determines whether optical path control and sleep control are necessary based on the cooperation information.

[0120] The real-time analysis unit 222 determines that optical path control and sleep control are necessary when any of the base stations 17 can accommodate all of the terminals 11 accommodated by one base station 17. In this case, the real-time analysis unit 222 notifies the control unit 23 of control information including an optical path control instruction and a sleep instruction. The optical path control instruction in the second embodiment is an instruction to request switching of the optical path, and includes, for example, information indicating the base station 17 that is the source of the optical path switching and information indicating the base station 17 that is the destination of the optical path switching. The sleep instruction in the second embodiment is an instruction to execute sleep, and includes, for example, information indicating the base station 17 that is the sleep target. The method of selecting the sleep target in the real-time analysis unit 222 is the same as in the first embodiment.

[0121] Furthermore, when the traffic volume of a certain base station 17 exceeds a threshold, the real-time analysis unit 222 determines that optical path control and sleep control are necessary. In this case, the real-time analysis unit 222 notifies the control unit 23 of control information including an optical path control instruction and a sleep release instruction. The sleep release instruction in the second embodiment is an instruction to execute sleep release, and includes, for example, information indicating the base station 17 to be released from sleep. The method of selecting the base station to be released from sleep in the real-time analysis unit 222 is the same as in the first embodiment.

[0122] The control unit 23 includes an optical path control unit 231 and a sleep control unit 232. The optical path control unit 231 determines the base station 17 that will be the source of optical path switching and the base station 17 that will be the destination of optical path switching based on the analysis results of the real-time analysis unit 222. For example, the optical path control unit 231 determines the base station 17 that will be the source of optical path switching based on information that indicates the base station 17 that will be the source of optical path switching, which is included in the control information notified from the real-time analysis unit 222. For example, the optical path control unit 231 determines the base station 17 that will be the destination of optical path switching based on information that indicates the base station 17 that will be the destination of optical path switching, which is included in the control information notified from the real-time analysis unit 222.

[0123] The optical path control unit 231 transmits optical path control information including information indicating the base station 17 to which the determined optical path is to be switched to, to the transfer device 14. As a result, the optical path control unit 231 instructs the transfer device 14 to switch the optical path. Furthermore, the optical path control unit 231 transmits an optical path control instruction to the base station 17 to which the determined optical path is to be switched.

[0124] Based on the analysis result of the real-time analysis unit 222, the sleep control unit 232 causes the base station 17 that is the target of sleep control to execute sleep or cancel sleep.

[0125] Fig. 18 is a flowchart showing an example of the flow of sleep processing executed by the management control device 20 in the second embodiment. The processing in Fig. 18 is repeatedly executed at a predetermined cycle. Note that, here, traffic information will be used as an example of the cooperation information. In Fig. 18, the explanation will be given assuming M=4.

[0126] The acquisition unit 211 acquires cooperation information from each of the base stations 17-1 to 17-4 (step S301). For example, the acquisition unit 211 may collect information once per unit time as a predetermined cycle, or may collect information at any timing. The acquisition unit 211 stores the acquired cooperation information for each base station 17 in the cooperation information storage unit 221 (step S302).

[0127] The real-time analysis unit 222 calculates the traffic volume of each of the base stations 17-1 to 17-4 based on the cooperation information for each base station 17 stored in the cooperation information storage unit 221. Then, the real-time analysis unit 222 sorts the base stations 17-1 to 17-4 in ascending order of the calculated traffic volumes (step S303).

[0128] The real-time analysis unit 222 determines an addition target A for the traffic volume (step S304). The addition target A is, for example, the base station 17 with the smallest traffic volume. Next, the real-time analysis unit 222 determines an addition target B for the traffic volume (step S305). The addition target B is, for example, the base station 17 with the second smallest traffic volume. The real-time analysis unit 222 adds up the traffic volume of addition target A and the traffic volume of addition target B to determine a traffic volume addition value T ｔｏｔａｌ is calculated (step S306).

[0129] The real-time analysis unit 222 calculates the calculated traffic volume sum T ｔｏｔａｌ The real-time analysis unit 222 compares the calculated traffic volume sum value T ｔｏｔａｌ is compared with the threshold value of the base station 17 corresponding to the addition target A.

[0130] The real-time analysis unit 222 calculates the traffic volume sum T ｔｏｔａｌ The real-time analysis unit 222 determines whether the traffic volume sum T ｔｏｔａｌ is not greater than the threshold (step S307—NO), the real-time analysis unit 222 adds the smallest traffic volume among the traffic volumes that have not been added, thereby obtaining a new traffic volume addition value T ｔｏｔａｌ is calculated (step S308).

[0131] After that, the real-time analysis unit 222 executes the process of step S307 again. In this case, the real-time analysis unit 222 calculates the newly calculated traffic volume sum T ｔｏｔａｌ The real-time analysis unit 222 determines whether the traffic volume sum T ｔｏｔａｌ is greater than the threshold (step S307-YES), the real-time analysis unit 222 determines the base station 17 to be aggregated (step S308). Specifically, the real-time analysis unit 222 determines the base station 17 with the largest traffic volume from among the base stations 17 with the traffic volumes added up before the threshold was exceeded as the base station 17 to be aggregated (step S309).

[0132] For example, if the base stations 17 having the traffic volumes added up before exceeding the threshold are base stations 17-1 to 17-3, the real-time analysis unit 222 may determine the base station 17 having the largest traffic volume from among the base stations 17-1 to 17-3 as the base station 17 to be aggregated. Note that the method for determining the base station 17 to be aggregated is not limited to the above method and other methods may be used. Here, it is assumed that base station 17-1 is determined as the base station to be aggregated.

[0133] Thereafter, the real-time analysis unit 222 notifies the control unit 23 of control information including an optical path control instruction and a sleep instruction. The real-time analysis unit 222 includes, for example, information indicating that the switching source central stations are base stations 17-2 and 17-3 and information indicating that the switching destination base station is base station 17-1 in the optical path control instruction. The real-time analysis unit 222 includes, for example, information indicating that the base stations to be put to sleep are base stations 17-2 and 17-3.

[0134] The optical path control unit 231 determines the base station 17 that will be the source of optical path switching and the base station 17 that will be the destination of optical path switching, based on the optical path control instructions included in the control information notified from the real-time analysis unit 222. Here, the optical path control unit 231 determines base station 17-1 as the destination of optical path switching, and determines base stations 17-2 and 17-3 as the source of optical path switching. The optical path control unit 231 transmits optical path control information including information indicating the destination base station and source base station of the determined optical path to the transfer device 14 (step S310).

[0135] As a result, the transfer device 14 switches the optical path route by switching the optical paths heading toward the base stations 17-2 and 17-3 to head toward the base station 17-1. Furthermore, the optical path control unit 231 transmits an optical path control instruction to the switching source base station of the determined optical path (step S311).

[0136] The sleep control unit 232 determines the base station 17 to be put to sleep based on the sleep instruction included in the control information notified from the real-time analysis unit 222. Here, the sleep control unit 232 determines the base station 17-2 and base station 17-3 as the sleep targets. The sleep control unit 232 transmits a sleep instruction to the determined base stations 17-2 and 17-3 (step S312). This allows the sleep target base stations 17-2 and 17-3 to transition to a sleep state.

[0137] 18 shows a configuration in which sleep control is performed after optical path switching control is performed, but optical path switching control may be performed after sleep control is performed. Furthermore, the process of step S311 may be executed by the optical path switching function of the transfer device 14.

[0138] 19 is a flowchart showing an example of the flow of a sleep release process executed by the management control device 20 in the second embodiment. Note that, here, the description will be given taking traffic information as an example of the cooperation information. In FIG. 19, the description will be given assuming M=4.

[0139] The acquisition unit 211 acquires cooperation information from each of the base stations 17-1 to 17-4 (step S401). The acquisition unit 211 stores the acquired cooperation information for each base station 17 in the cooperation information storage unit 221.

[0140] The real-time analysis unit 222 reads the association information for each base station 17 stored in the association information storage unit 221 (step S402). The real-time analysis unit 222 calculates the traffic volume for each base station 17-1 to 17-4 based on the association information for each base station 17 that has been read (step S403). The real-time analysis unit 222 compares the traffic volume for each base station 17-1 to 17-4 with a threshold. The threshold used here may be the same as or different from the threshold used in FIG. 18.

[0141] The real-time analysis unit 222 determines whether there is any base station 17 whose traffic volume exceeds the threshold (step S404). If the real-time analysis unit 222 determines that there is no base station 17 whose traffic volume exceeds the threshold (step S404-NO), the management control device 20 ends the processing of FIG.

[0142] On the other hand, if the real-time analysis unit 222 determines that there is a base station 17 whose traffic volume exceeds the threshold (step S404—YES), the real-time analysis unit 222 determines the base station 17 to be released from sleep mode (step S405). Here, it is assumed that the base station 17 whose traffic volume exceeds the threshold is base station 17-1. The real-time analysis unit 222 identifies, from among the sleeping base stations 17-2 to 17-4, the other base station 17 with the highest traffic volume among the traffic volumes aggregated at base station 17-1. As a method for identifying this base station, either (Identification Method 1) or (Identification Method 2) described in the first embodiment is used.

[0143] It is assumed that base station 17-2 is identified as the other base station 17 with the highest traffic volume by one of the above identification methods. The real-time analysis unit 222 determines the identified base station 17-2 as the base station 17 to be released from sleep mode. Thereafter, the real-time analysis unit 222 notifies the control unit 23 of control information including an optical path control instruction and a sleep release instruction. For example, the real-time analysis unit 222 includes, in the optical path control instruction, information indicating that the base station to be switched to is base station 17-2. For example, the real-time analysis unit 222 includes information indicating that the base station to be released from sleep mode is base station 17-2.

[0144] The optical path control unit 231 determines the base station 17 to be the control target of the optical path based on the optical path control instruction included in the control information notified from the real-time analysis unit 222. Here, the optical path control unit 231 determines the base station 17-2 as the control target of the optical path. The optical path control unit 231 transmits optical path control information including information indicating the base station 17 to be the control target of the determined optical path to the transfer device 14 (step S406). As a result, the transfer device 14 forms an optical path directed to the base station 17-2.

[0145] The sleep control unit 232 determines the base station 17 to be released from sleep mode based on the sleep release instruction included in the control information notified by the real-time analysis unit 222. Here, the sleep control unit 232 determines the base station 17-2 as the base station to be released from sleep mode. The sleep control unit 232 transmits the sleep release instruction to the determined base station 17-2 (step S407). This allows the base station 17-2 to be released from sleep mode.

[0146] The mobile network system 100 according to the second embodiment configured as described above includes a cooperation information collection unit 21 that acquires cooperation information from a plurality of base stations 17, and an analysis unit 22 that determines one or more base stations 17 to be subjected to sleep control from among the plurality of base stations 17 based on a result of sorting the plurality of base stations 17 based on the cooperation information, and executes sleep control on the one or more base stations 17 to be subjected to sleep control. This makes it possible to determine sleep control taking into account the cooperation information obtained from each base station 17. This makes it possible to increase the effect of power saving without degrading communication quality.

[0147] (Variation 1 of the Second Embodiment) In the above-described embodiment, the configuration has been shown in which the management control device 20 performs optical path control processing and sleep control processing. In contrast, the forwarding device may be configured to perform optical path control processing and sleep control processing. In this configuration, the mobile NW system 200 includes a forwarding device 14a shown in FIG. 9 instead of the forwarding device 14, and a management control device 20a shown in FIG. 9 instead of the management control device 20. For specific processing, the radio station 12 and the central station 16 can be read as base stations 17.

[0148] (Variation 2 of Second Embodiment) In the above-described embodiment, a configuration has been shown in which the management control device 20 performs optical path control processing and sleep control processing. Alternatively, a configuration may be adopted in which the management control device performs sleep control processing and the forwarding device performs optical path control processing. In such a configuration, the mobile NW system 200 includes a forwarding device 14b shown in FIG. 10 instead of the forwarding device 14, and a management control device 20b shown in FIG. 10 instead of the management control device 20. For specific processing, the radio station 12 and the central station 16 can be read as base stations 17.

[0149] (Variation 3 of the Second Embodiment) In the above-described embodiment, a configuration has been shown in which the management control device 20 performs optical path control processing and sleep control processing. However, the optical path control processing and sleep control processing may be performed by different devices. In such a configuration, the mobile NW system 200 includes an optical transmission management control device 65 and a radio transmission management control device 70 shown in FIG. 11 instead of the management control device 20. For specific processing, the radio station 12 and the central station 16 can be read as the base station 17.

[0150] (Variation 4 of the Second Embodiment) In the above-described embodiment, a configuration has been shown in which the management control device 20 performs optical path control processing and sleep control processing. However, the optical path control processing and sleep control processing may be performed by different devices. In such a configuration, the mobile NW system 200 includes an optical transmission management control device 65 and a radio transmission management control device 70 shown in FIG. 12 instead of the management control device 20. For specific processing, the radio station 12 and the central station 16 can be read as the base station 17.

[0151] (Fifth Modification of the Second Embodiment) The mobile NW system 200 may be configured as shown in Fig. 13. In this configuration, the mobile NW system 200 includes an optical transmission management control device 65, a radio transmission management control device 70, and an orchestrator 75 shown in Fig. 13 instead of the management control device 20. Specific processing can be performed by replacing the radio station 12 and the central station 16 with the base station 17.

[0152] (Variation 6 of the Second Embodiment) The mobile NW system 200 may be configured as shown in Fig. 14. In this configuration, the mobile NW system 200 includes an optical transmission management control device 65, a radio transmission management control device 70, and an orchestrator 75 shown in Fig. 14 instead of the management control device 20. Specific processing can be performed by replacing the radio station 12 and the central station 16 with the base station 17.

[0153] (Seventh Modification of the Second Embodiment) The mobile NW system 200 may be configured as shown in Fig. 15. In this configuration, the mobile NW system 200 includes an optical transmission management control device 65 and a radio transmission management control device shown in Fig. 15 instead of the management control device 20. Specific processing can be performed by replacing the radio station 12 and the central station 16 with the base station 17.

[0154] (Variation 8 of the Second Embodiment) The cooperation information may include, for example, information on the number of terminals accommodated in each base station 17. The cooperation information may include, for example, processing load information of the base station 17. The processing load information in the second embodiment may be, for example, information on memory usage rate or CPU usage rate of the base station 17. The cooperation information may include communication quality information of the terminals 11 connected to each base station 17.

[0155] When the cooperation information includes information regarding the number of accommodated terminals, the real-time analysis unit 222 may select a base station to be subjected to sleep control (for example, a base station to be subjected to sleep or a base station to be released from sleep) using the information regarding the number of accommodated terminals. When configured in this manner, the real-time analysis unit 222 may select a base station to be subjected to sleep control in the same way as when traffic information is used.

[0156] First, the real-time analysis unit 222 sorts the base stations 17 in ascending order of the number of accommodated terminals, as specified by the information on the number of accommodated terminals. Then, the real-time analysis unit 222 adds up the base stations 17 with the fewest accommodated terminals, in ascending order of the number of accommodated terminals. The real-time analysis unit 222 compares the summed total with a threshold and adds up the base stations 17 with the fewest accommodated terminals until the threshold is exceeded. Based on the summed number of accommodated terminals before the threshold is exceeded, the real-time analysis unit 222 selects a base station 17 to be put to sleep from among the multiple base stations 17 corresponding to the summed number of accommodated terminals. Next, the real-time analysis unit 222 determines a base station 17 to be put to sleep from among the multiple base stations 17 corresponding to the summed number of accommodated terminals. For example, the real-time analysis unit 222 determines the base station 17 to be the aggregation destination, which is the base station 17 that accommodates the most terminals 11 within the summed number of accommodated terminals within the range that does not exceed the threshold. Then, the real-time analysis unit 222 determines a base station 17 other than the aggregation destination, as a base station 17 to be put to sleep from among the multiple base stations 17 corresponding to the summed number of accommodated terminals.

[0157] When the collaboration information includes processing load information and communication quality information, the real-time analysis unit 222 may select a sleep control target (e.g., a sleep target or a sleep release target) using the processing load information or communication quality information in addition to the traffic information. For example, when selecting a sleep control target using communication quality information in addition to traffic information, the real-time analysis unit 222 determines to perform sleep control if a condition based on the traffic information and a condition based on the communication quality information are satisfied. The condition based on the communication quality information may be, for example, a condition based on whether a path after sleep is feasible (e.g., whether quality degradation occurs). In this case, even if the real-time analysis unit 222 determines the base station 17 to be the sleep target and the base station 17 to be the optical path control target based on a condition based on traffic information, quality degradation may occur after the path is switched. Therefore, even if the real-time analysis unit 222 determines the base station 17 to be the sleep target and the base station 17 to be the optical path control target based on a condition based on traffic information, the real-time analysis unit 222 may not perform sleep if quality degradation occurs on the path after optical path control.

[0158] (Third Embodiment) In the above-described first and second embodiments, configurations for solving problems that arise in mobile network systems have been described. Specifically, in the first and second embodiments, configurations for solving a problem that arises in a mobile network system in which wireless communication is performed between a terminal and each base station, each base station autonomously determines whether or not to sleep, which may prevent overall optimization and limit the effect of power saving. However, such problems are not limited to mobile network systems, but may also arise in wired network systems in which terminals are connected by wire. Therefore, in the third embodiment, a configuration for solving the above problems that may arise in wired network systems will be described.

[0159] (Overall configuration and processing overview of wired network system) FIG. 20 is a diagram for explaining an overview of the overall configuration and processing of a wired network system in an embodiment. First, the overall configuration of the wired network system will be explained. The wired network system is an example of a communication system. The wired network system is, for example, a PON (Passive Optical Network). In the following explanation, a case will be explained in which the wired network system is a PON, but the wired network system may have other configurations as long as terminals are connected by wire. For example, the wired network system may have a configuration in which terminals are connected point-to-point. The wired network system includes one or more ONUs 42, a transfer device 43, multiple OLTs 44, a concentrator 45, a core device 46, and a management control device 50.

[0160] Optical fibers that transmit optical signals are connected between each ONU 42 and the transfer device 43, between the transfer device 43 and each OLT 44, between each OLT 44 and the concentrator 45, and between the concentrator 45 and the core device 46. Electrical lines or optical fibers that transmit electrical signals are connected between the transfer device 43 and the management control device 50, and between each OLT 44 and the management control device 50. The example shown in Figure 20 shows a case where there are four ONUs 42 and two OLTs 44. Note that multiple transfer devices 43 may be provided, but the following explanation will be given using a case where there is one.

[0161] The ONUs 42 are optical subscriber line terminals provided in user premises that terminate optical signals. One or more terminals 41 are connected to each ONU 42 via wires such as electrical lines. Each ONU 42 performs wired communication with the terminals 41. For example, each ONU 42 receives an electrical signal transmitted from the terminal 41 and converts the received electrical signal into an optical signal. Each ONU 42 transmits the converted optical signal to the OLT 44 connected thereto via a transfer device 43. Each ONU 42 receives the optical signal via the transfer device 43. Each ONU 42 converts the received optical signal into an electrical signal and transmits it to the terminal 41. The ONUs 42 are one aspect of other devices.

[0162] The transfer device 43 is provided between the ONU 42 and the OLT 44. The transfer device 43 is a switch that connects the ONU 42 and the OLT 44 via an optical path. The transfer device 43 switches the optical path in accordance with optical path control information transmitted from the management control device 50. The transfer device 43 switches the connection between the ONU 42 and the OLT 44 by switching the optical path.

[0163] The OLT 44 is an optical line termination device provided on the electric utility side and terminates optical signals. The OLT 44 receives upstream signals transmitted from one or more ONUs 42 via a transfer device 43. The OLT 44 transmits downstream signals to one or more ONUs 42 connected via the transfer device 43. The upstream signals transmitted from one or more ONUs 42 are signals obtained by converting signals transmitted from the terminal 41 into optical signals, and the downstream signals are optical signals addressed to the terminal 41. Each OLT 44 transitions to a sleep state in accordance with a sleep instruction transmitted from the management control device 50. Information acquired by the management control device 50 from the OLT 44 is called coordination information. The coordination information in the third embodiment is information indicating the state of communication between each OLT 44 and the terminal 41. The OLT 44 is one aspect of a communication station.

[0164] The cooperation information in the third embodiment includes, for example, information on the traffic volume of each central office 16. The traffic information is the same as in the first embodiment.

[0165] The OLT 44 includes at least a transmitter, a receiver, and a sleep processor. The transmitter transmits coordination information to the management controller 50 either in response to a request from the management controller 50 or independently. The receiver receives an optical path control instruction from the management controller 50. The OLT 44 receiving an optical path control instruction from the management controller 50 indicates that the management controller 50 has determined, based on the coordination information, that it is necessary to switch the optical path between the ONU 42 and the OLT 44. The sleep processor transitions to a sleep state after switching the optical path based on the optical path control instruction. Furthermore, the OLT 44 includes an optical path switching processor for performing optical path switching processing.

[0166] The concentrator 45 aggregates the upstream signals transmitted by the OLTs 44. The concentrator 45 distributes the downstream signals.

[0167] The core device 46 performs signal processing on the upstream signals aggregated by the concentrator 45. The concentrator 45 transmits the signals obtained as a result of the signal processing performed on the upstream signals to an external network. The core device 46 receives signals from the external network.

[0168] The core device 46 performs predetermined signal processing on signals received from an external network, and transmits the signals obtained as a result of the signal processing performed on the signals received from the external network to the concentrator 45 as downstream signals.

[0169] The management control device 50 is a device that manages the entire wired network system. The management control device 50 acquires coordination information from each OLT 44. When acquiring coordination information from each OLT 44, the management control device 50 uses a coordination interface. The management control device 50 determines whether optical path control and sleep control are necessary based on the acquired coordination information. When it is determined that optical path control and sleep control are necessary, the management control device 50 performs optical path control processing and sleep control processing. The optical path control processing in the third embodiment is processing that switches optical paths between the ONU 42 and the OLT 44 and generates optical paths. The sleep control processing in the third embodiment is processing that puts the OLT 44 into sleep mode or releases sleep.

[0170] Next, an overview of the processing of the wired network system will be explained. The upper diagram of Fig. 20 shows the connection state of the wired network system before optical path switching, and the lower diagram of Fig. 20 shows the connection state of the wired network system after optical path switching. The upper diagram of Fig. 20 shows an example in which ONUs 42-1 and 42-2 are connected to OLT 44-1, and ONUs 42-3 and 42-4 are connected to OLT 44-2.

[0171] The management control device 50 performs optical path control processing and sleep control processing when one OLT 44 can accommodate traffic of another OLT 44 based on the coordination information collected from each OLT 44. For example, the management control device 50 performs optical path control processing and sleep control processing in OLT 44-2 when traffic of OLT 44-1 can be accommodated. In this way, by accommodating traffic of another OLT 44 in one OLT 44, the other OLT 44 can be transitioned to a sleep state.

[0172] When the management control device 50 determines that the optical path control process should be performed, it transmits information about the optical path switching destination to the transfer device 43 and instructs the OLT 44, which is the optical path switching target, to switch the optical path.

[0173] The lower diagram of Figure 20 shows an example in which ONUs 42-1 to 42-4 are connected to OLT 44-1 and OLT 44-2 has transitioned to a sleep state. In this way, in a wired network system, based on the linkage information collected from each OLT 44, a terminal 41 connected to an OLT 44 that can transition to a sleep state is connected to another OLT 44, thereby transitioning the OLT 44 that can transition to a sleep state to a sleep state. Hereinafter, an OLT 44 that can transition to a sleep state will be referred to as a switching source OLT, and an OLT 44 that will be the new connection destination of a terminal 41 connected to the switching source OLT will be referred to as a switching destination OLT. A specific configuration will be described below.

[0174] Fig. 21 is a diagram showing an example of the configuration of a wired NW system 300 according to the third embodiment. The wired NW system 300 according to the fifth embodiment includes a plurality of ONUs 42-1 to 42-M, a transfer device 43, a plurality of OLTs 44-1 to 44-N, a concentrator 45, a core device 46, and a management control device 50. The ONUs 42, the transfer device 43, the OLT 44, the concentrator 45, and the core device 46 have been described in Fig. 20, and therefore description thereof will be omitted.

[0175] The management control device 50 includes a cooperation information collection unit 51, an analysis unit 52, and a control unit 53. The cooperation information collection unit 51 includes an acquisition unit 511. The acquisition unit 511 collects cooperation information from each OLT 44 at a predetermined period or at any timing. For example, the acquisition unit 511 collects traffic information of each OLT 44 as cooperation information.

[0176] The analysis unit 52 includes a coordination information storage unit 521 and a real-time analysis unit 522. The coordination information storage unit 521 records the collected coordination information in a predetermined storage device. The real-time analysis unit 522 analyzes the state of communication between each OLT 44 and the terminal 41 based on the coordination information. Specifically, the real-time analysis unit 522 determines whether optical path control and sleep control are necessary based on the coordination information.

[0177] For example, the real-time analysis unit 522 determines that optical path control and sleep control are necessary when all terminals 41 accommodated by one OLT 44 can be accommodated by another OLT 44. In this case, the real-time analysis unit 522 notifies the control unit 53 of control information including an optical path control instruction and a sleep instruction. The optical path control instruction in the third embodiment is an instruction to request switching of the optical path, and includes, for example, information indicating the OLT 44 that is the source of the optical path switching and information indicating the OLT 44 that is the destination of the optical path switching. The sleep instruction in the third embodiment is an instruction to execute sleep, and includes, for example, information indicating the OLT 44 that is the sleep target. Note that the method of selecting the sleep target in the real-time analysis unit 522 is the same as in the first embodiment.

[0178] Furthermore, when the traffic volume of a certain OLT 44 exceeds a threshold, the real-time analysis unit 522 determines that optical path control and sleep control are necessary. In this case, the real-time analysis unit 522 notifies the control unit 53 of control information including an optical path control instruction and a sleep release instruction. The sleep release instruction in the third embodiment is an instruction to execute sleep release, and includes, for example, information indicating the OLT 44 to be released from sleep. The method of selecting the OLT 44 to be released from sleep in the real-time analysis unit 522 is the same as in the first embodiment.

[0179] The control unit 53 includes an optical path control unit 531 and a sleep control unit 532. The optical path control unit 531 determines the OLT 44 that will be the source of optical path switching and the OLT 44 that will be the destination of optical path switching based on the analysis results of the real-time analysis unit 522. For example, the optical path control unit 531 determines the OLT 44 that will be the source of optical path switching based on information indicating the OLT 44 that will be the source of optical path switching, which is included in the control information notified from the real-time analysis unit 522. For example, the optical path control unit 531 determines the OLT 44 that will be the destination of optical path switching based on information indicating the OLT 44 that will be the destination of optical path switching, which is included in the control information notified from the real-time analysis unit 522.

[0180] The optical path control unit 531 transmits optical path control information including information indicating the OLT 44 to which the determined optical path is to be switched to the transfer device 43. As a result, the optical path control unit 531 instructs the transfer device 43 to switch the optical path. Furthermore, the optical path control unit 531 transmits an optical path control instruction to the OLT 44 to which the determined optical path is to be switched.

[0181] The sleep control unit 532 causes the OLT 44 that is the target of sleep control to execute sleep or cancel sleep based on the analysis result of the real-time analysis unit 522 .

[0182] Fig. 22 is a flowchart showing an example of the flow of sleep processing executed by the management control device 50 in the third embodiment. The processing in Fig. 22 is repeatedly executed at a predetermined cycle. Note that, here, traffic information will be used as an example of the cooperation information. In Fig. 22, the explanation will be given assuming M = N = 4.

[0183] The acquisition unit 511 acquires cooperation information from each of the OLTs 44-1 to 44-4 (step S501). For example, the acquisition unit 511 may collect information once per unit time as a predetermined cycle, or may collect information at any timing. The acquisition unit 511 stores the acquired cooperation information for each OLT 44 in the cooperation information storage unit 521 (step S502).

[0184] The real-time analysis unit 522 calculates the traffic volume of each of the OLTs 44-1 to 44-4 based on the cooperation information for each OLT 44 stored in the cooperation information storage unit 521. Then, the real-time analysis unit 522 sorts the OLTs 44-1 to 44-4 in ascending order of the calculated traffic volumes (step S503).

[0185] The real-time analysis unit 522 determines an addition target A for the traffic volume (step S504). The addition target A is, for example, the OLT 44 with the smallest traffic volume. Next, the real-time analysis unit 522 determines an addition target B for the traffic volume (step S505). The addition target B is, for example, the OLT 44 with the second smallest traffic volume. The real-time analysis unit 522 adds up the traffic volume of addition target A and the traffic volume of addition target B to obtain a traffic volume addition value T ｔｏｔａｌ is calculated (step S506).

[0186] The real-time analysis unit 522 calculates the calculated traffic volume sum T ｔｏｔａｌ The threshold value in the third embodiment is a value for control determination, and may be the same for each OLT 44, or may be a different value for each OLT 44. The threshold value may be calculated based on the cooperation information, or may be stored in advance by the real-time analysis unit 522 for each OLT 44. The real-time analysis unit 522 compares the calculated traffic volume sum value T ｔｏｔａｌ is compared with the threshold value of the OLT 44 corresponding to the addition target A.

[0187] The real-time analysis unit 522 calculates the traffic volume sum T ｔｏｔａｌ The real-time analysis unit 522 determines whether the traffic volume sum T ｔｏｔａｌ is not greater than the threshold (step S507—NO), the real-time analysis unit 522 adds the smallest traffic volume among the traffic volumes that have not been added, thereby obtaining a new traffic volume addition value T ｔｏｔａｌ is calculated (step S508).

[0188] After that, the real-time analysis unit 522 executes the process of step S507 again. In this case, the real-time analysis unit 522 calculates the newly calculated traffic volume sum T ｔｏｔａｌ The real-time analysis unit 522 determines whether the traffic volume sum T ｔｏｔａｌis greater than the threshold (step S507-YES), the real-time analysis unit 522 determines the OLT 44 to be aggregated (step S508). Specifically, the real-time analysis unit 522 determines the OLT 44 with the largest traffic volume from among the OLTs 44 with the traffic volumes added up to the time when the threshold was exceeded as the OLT 44 to be aggregated (step S509).

[0189] For example, if the OLTs 44 having the traffic volumes added up before exceeding the threshold are OLTs 44-1 to 44-3, the real-time analysis unit 522 may determine the OLT 44 having the largest traffic volume from among the OLTs 44-1 to 44-3 as the aggregation destination OLT 44. Note that the method for determining the aggregation destination OLT 44 is not limited to the above method and other methods may also be used. Here, it is assumed that OLT 44-1 is determined as the aggregation destination.

[0190] Thereafter, the real-time analysis unit 522 notifies the control unit 53 of control information including an optical path control instruction and a sleep instruction. The real-time analysis unit 522 includes, for example, information indicating that the switching source OLTs are the central office OLTs 44-2 and 44-3 and information indicating that the switching destination OLT is the OLT 44-1 in the optical path control instruction. The real-time analysis unit 522 includes, for example, information indicating that the sleep target OLTs are the OLTs 44-2 and 44-3.

[0191] The optical path control unit 531 determines the OLT 44 that will be the source of optical path switching and the OLT 44 that will be the destination of optical path switching, based on the optical path control instructions included in the control information notified from the real-time analysis unit 522. Here, the optical path control unit 531 determines OLT 44-1 as the destination of optical path switching, and determines OLTs 44-2 and 44-3 as the source of optical path switching. The optical path control unit 531 transmits optical path control information including information indicating the destination OLT and source OLT of the determined optical path to the transfer device 43 (step S510).

[0192] As a result, the transfer device 43 switches the optical path route by switching the optical paths heading toward the OLTs 44-2 and 44-3 to the OLT 44-1. Furthermore, the optical path control unit 531 transmits an optical path control instruction to the OLT from which the determined optical path is to be switched (step S511).

[0193] The sleep control unit 532 determines the OLT 44 to be put into sleep mode based on the sleep instruction included in the control information notified from the real-time analysis unit 522. Here, the sleep control unit 532 determines the OLT 44-2 and OLT 44-3 as the sleep targets. The sleep control unit 532 transmits a sleep instruction to the determined OLT 44-2 and OLT 44-3 (step S512). This allows the sleep-target OLT 44-2 and OLT 44-3 to transition to a sleep state.

[0194] 22 shows a configuration in which sleep control is performed after optical path switching control is performed, but optical path switching control may be performed after sleep control is performed. Furthermore, the process of step S511 may be performed by the optical path switching function of the transfer device 43.

[0195] 23 is a flowchart showing an example of the flow of a sleep release process executed by the management control device 50 in the third embodiment. Note that, here, the description will be given taking traffic information as an example of the cooperation information. In FIG. 23, the description will be given assuming M=N=4.

[0196] The acquisition unit 511 acquires the cooperation information from each of the OLTs 44-1 to 44-4 (step S601). The acquisition unit 511 stores the acquired cooperation information for each OLT 44 in the cooperation information storage unit 521.

[0197] The real-time analysis unit 522 reads the linkage information of each OLT 44 stored in the linkage information storage unit 521 (step S602). The real-time analysis unit 522 calculates the traffic volume of each OLT 44-1 to 44-4 based on the read linkage information for each OLT 44 (step S603). The real-time analysis unit 522 compares the traffic volume of each OLT 44-1 to 44-4 with a threshold. The threshold used here may be the same as or different from the threshold used in FIG. 22.

[0198] The real-time analysis unit 522 determines whether there is an OLT 44 whose traffic volume exceeds the threshold (step S604). If the real-time analysis unit 522 determines that there is no OLT 44 whose traffic volume exceeds the threshold (step S604-NO), the management control device 50 ends the processing of FIG. 23.

[0199] On the other hand, if the real-time analysis unit 522 determines that there is an OLT 44 whose traffic volume exceeds the threshold (step S604—YES), the real-time analysis unit 522 determines the OLT 44 to be woken up (step S605). Here, it is assumed that the OLT 44 whose traffic volume exceeds the threshold is OLT 44-1. The real-time analysis unit 522 identifies the other OLT 44 with the largest traffic volume among the traffic volumes aggregated to OLT 44-1 from among the sleeping OLTs 44-2 to 44-4. As a method for identifying this OLT, either (Identification Method 1) or (Identification Method 2) described in the first embodiment is used.

[0200] It is assumed that the OLT 44-2 is identified as the other OLT 44 with the highest traffic volume by any of the above identification methods. The real-time analysis unit 522 determines the identified OLT 44-2 as the OLT 44 to be woken up from sleep mode. Thereafter, the real-time analysis unit 522 notifies the control unit 53 of control information including an optical path control instruction and a sleep wake-up instruction. For example, the real-time analysis unit 522 includes information indicating that the OLT to be switched to is the OLT 44-2 in the optical path control instruction. For example, the real-time analysis unit 522 includes information indicating that the OLT to be woken up from sleep mode is the OLT 44-2.

[0201] The optical path control unit 531 determines the OLT 44 that will be the control target of the optical path based on the optical path control instruction included in the control information notified from the real-time analysis unit 522. Here, the optical path control unit 531 determines the OLT 44-2 as the control target of the optical path. The optical path control unit 531 transmits optical path control information including information indicating the OLT that will be the control target of the determined optical path to the transfer device 43 (step S606). As a result, the transfer device 43 forms an optical path toward the OLT 44-2.

[0202] The sleep control unit 532 determines the OLT 44 to be released from sleep mode based on the sleep release instruction included in the control information notified from the real-time analysis unit 522. Here, the sleep control unit 532 determines the OLT 44-2 as the release target. The sleep control unit 532 transmits a sleep release instruction to the determined OLT 44-2 (step S607). This allows the OLT 44-2 to be released from sleep mode.

[0203] The wired network system 300 configured as described above includes a collaboration information collection unit 51 that acquires collaboration information from a plurality of OLTs 44, and an analysis unit 52 that determines one or more OLTs 44 to be subjected to sleep control from among the plurality of OLTs 44 based on a result of sorting the plurality of OLTs 44 based on the collaboration information, and executes sleep control on the one or more OLTs 44 to be subjected to sleep control. This allows the sleep control to be determined taking into account the collaboration information obtained from each OLT 44. This makes it possible to increase the effect of power saving without degrading communication quality.

[0204] (Variation 1 of the Third Embodiment) The collaboration information may include, for example, information on the number of terminals accommodated in each OLT 44. The collaboration information may include, for example, processing load information of the OLT 44. The processing load information in the third embodiment may be, for example, information on the memory usage rate or CPU usage rate of the OLT 44. The collaboration information may include communication quality information of the terminals 41 connected to each OLT 44.

[0205] When the cooperation information includes information regarding the number of accommodated terminals, the real-time analysis unit 522 may select a sleep control target (for example, a sleep target or a sleep release target) using the information regarding the number of accommodated terminals. When configured in this manner, the real-time analysis unit 522 may select an OLT to be a sleep control target, in the same way as when traffic information is used.

[0206] First, the real-time analysis unit 522 sorts the OLTs 44 in order of the number of accommodated terminals identified by the information on the number of accommodated terminals. Then, the real-time analysis unit 522 sums the OLTs 44 with the fewest number of accommodated terminals in ascending order. The real-time analysis unit 522 compares the summed total with a threshold and sums the OLTs 44 with the fewest number of accommodated terminals in ascending order until the threshold is exceeded. Based on the summed number of accommodated terminals before the threshold is exceeded, the real-time analysis unit 522 selects a sleep target from among the multiple OLTs 44 with respect to the summed number of accommodated terminals. Next, the real-time analysis unit 522 determines an OLT to be aggregated from among the multiple OLTs 44 with respect to the summed number of accommodated terminals. For example, the real-time analysis unit 522 determines the OLT 44 with the most terminals 41 among the summed number of accommodated terminals within the range that does not exceed the threshold as the aggregation target OLT 44. Thereafter, the real-time analysis unit 522 determines, from among the plurality of OLTs 44 relating to the total number of accommodated terminals, the OLTs 44 other than the aggregation destination as targets for sleep.

[0207] When the collaboration information includes processing load information and communication quality information, the real-time analysis unit 522 may select a sleep control target (e.g., a sleep target or a sleep release target) using the processing load information or communication quality information in addition to the traffic information. For example, when selecting a sleep control target using communication quality information in addition to traffic information, the real-time analysis unit 522 determines to perform sleep control when a condition based on the traffic information and a condition based on the communication quality information are satisfied. The condition based on the communication quality information may be, for example, a condition based on whether a path after sleep is feasible (e.g., whether quality degradation occurs). In this case, even if the real-time analysis unit 522 determines the OLT 44 to be the sleep target and the OLT 44 to be the optical path control target based on a condition based on traffic information, quality degradation may occur after the path is switched. Therefore, even if the real-time analysis unit 522 determines the OLT 44 to be the sleep target and the OLT 44 to be the optical path control target based on a condition based on traffic information, the real-time analysis unit 522 may not execute sleep if quality degradation occurs on the path after optical path control.

[0208] At least some or all of the functional units of the management control devices 20, 20a, 20b, and 50, some or all of the functional units of the transfer devices 14, 14a, 14b, and 43, and some or all of the functional units of the OLT 44 are realized as software by a processor such as a central processing unit (CPU) executing a program stored in a storage device having a non-volatile storage medium (non-transitory storage medium) and a storage unit. The program may be recorded on a computer-readable non-transitory storage medium. Examples of computer-readable non-transitory storage media include portable media such as flexible disks, magneto-optical disks, read-only memories (ROMs), and compact disc read-only memories (CD-ROMs), and storage devices such as hard disks built into computer systems.

[0209] At least some or all of the functional units of the management control devices 20, 20a, 20b, 50, some or all of the functional units of the transfer devices 14, 14a, 14b, 43, or some or all of the functional units of the OLT 44 may be realized using hardware including electronic circuits (electronic circuits or circuitry) using, for example, an LSI (Large Scale Integrated circuit), an ASIC (Application Specific Integrated Circuit), a PLD (Programmable Logic Device), or an FPGA (Field Programmable Gate Array).

[0210] Although an embodiment of the present invention has been described above in detail with reference to the drawings, the specific configuration is not limited to this embodiment, and includes designs within the scope of the gist of the present invention.

[0211] The present invention can be applied to optical communication systems such as optical access systems.

[0212] 11, 41... terminal, 12, 12-1 to 12-M... radio station, 14, 14a, 14b, 43... forwarding device, 16, 16-1 to 16-N... central office, 17, 17-1 to 17-M... base station, 19... server, 20, 20a, 20b, 50... management control device, 21... cooperation information collection unit, 22... analysis unit, 23, 23b, 66, 71, 141... control unit, 42, 42-1 to 42-M... ONU, 44, 44-1 to 44-N... OLT, 45... concentrator, 46... core device, 65... optical transmission management control device, 70... wireless transmission management control device, 75... orchestrator, 211, 671, 771... acquisition unit, 221, 681, 731... Coordination information storage unit, 222, 682, 732... Real-time analysis unit, 231... Optical path control unit, 232... Sleep control unit, 100, 100a, 100b, 100c, 100d, 100e, 100f, 100g, 200... Mobile NW system, 300... Wired NW system, 751... Signal transfer unit

Claims

1. A control device comprising: a coordination information collection unit that acquires coordination information from a plurality of communication stations that are connected to one or more terminals directly or via other devices and indicates a state of communication between the one or more terminals; and an analysis unit that determines one or more communication stations to be subject to sleep control from among the plurality of communication stations based on a result of rearranging the plurality of communication stations based on the coordination information, and executes sleep control on the one or more communication stations to be subject to sleep control.

2. The control device of claim 1, wherein, when determining the one or more communication stations to be put to sleep as part of the sleep control, the analysis unit rearranges the multiple communication stations in order of the value specified in the cooperation information of the communication station with the lowest value, adds up the values ​​specified in the cooperation information of the communication station with the lowest value, determines as candidates for sleep the one or more communication stations from which each value added up before the threshold was exceeded was obtained, and determines from among the candidates for sleep the communication stations other than the communication station with the largest value specified in the cooperation information as the one or more communication stations to be put to sleep.

3. The control device of claim 2, wherein the coordination information is information on the traffic volume of each communication station, and the analysis unit rearranges the multiple communication stations in order of the traffic volume from least to greatest, adds up the traffic volumes of the communication stations in ascending order, determines one or more communication stations from which the traffic volumes added up before the threshold was exceeded were obtained as candidates for sleep, and determines from among the candidates for sleep the communication stations other than the communication station with the largest traffic volume as the one or more communication stations to be put to sleep.

4. The control device of claim 2, wherein the coordination information is information on the number of terminals accommodated in each communication station, and the analysis unit rearranges the multiple communication stations in ascending order of the number of terminals accommodated, adds up the numbers of terminals accommodated by the communication stations with the lowest number of terminals in order, determines one or more communication stations from which the numbers of terminals accommodated were obtained before the total number exceeded a threshold as candidates for sleep, and determines from among the candidates for sleep, all communication stations other than the communication station with the largest number of terminals accommodated, as the one or more communication stations to be put to sleep.

5. The control device according to any one of claims 1 to 4, wherein the analysis unit determines the communication station having the largest value identified by the cooperation information as the aggregation destination for terminals connected to other communication stations, and instructs the determined aggregation destination communication station to aggregate the terminals connected to the other communication stations.

6. The control device described in claim 5, wherein the coordination information is information on the traffic volume of each communication station or information on the number of terminals accommodated in each communication station, and when the analysis unit determines the one or more communication stations to be targets for awakening as part of the sleep control, it determines as the communication station to be awakened the communication station that has the largest traffic volume or the largest number of terminals accommodated for one or more sleeping communication stations among the communication stations to be aggregated and whose traffic volume or number of terminals exceeds a threshold, and instructs the determined communication station to be awakened to be awakened.

7. A control device as claimed in any one of claims 1 to 4, further comprising an optical path control unit that controls the optical paths of the plurality of communication stations, or a sleep control unit that executes sleep control for one or more communication stations that are subject to the sleep control before or after the optical path control is performed.

8. A control method comprising: acquiring, from a plurality of communication stations connected directly or via other devices to one or more terminals, coordination information indicating a state of communication between the one or more terminals and the plurality of communication stations; determining one or more communication stations to be subject to sleep control from among the plurality of communication stations based on a result of rearranging the plurality of communication stations based on the coordination information; and executing sleep control on the one or more communication stations to be subject to sleep control.