Control device, communication system, control method and program

Abstract

A control device according to the present invention is provided with: an acquisition unit that acquires information from a distributed station which announces, at a prescribed announcement frequency, information relating to one or more events that have occurred within a predetermined time period; an information analysis unit that analyses the information; a frequency deriving unit that derives the occurrence frequency of the information; a load deriving unit that derives the load of analysis of the information; and a frequency control unit that, on the basis of at least one from among information analysis results, the occurrence frequency of the information, and the load of the analysis of the information, controls the prescribed announcement frequency by using, as an upper limit, a frequency which is lower than the occurrence frequency.

Description

[Technical field]

[0001] The present invention relates to a control device, a communication system, a control method, and a program. [Background technology]

[0002] "O-RAN (Open Radio Access Network) CTI (Cooperative transport interface)" is known as an interface in the mobile fronthaul of an optical communication system. "CTI Report message" including communication scheduling information is exchanged between a distributed station (O-DU: O-RAN Distributed Unit) and a transport node (TN: Transport Node) in the mobile fronthaul (see Non-Patent Document 1).

[0003] Scheduling is performed between the remote station and a user equipment (UE: User Equipment) regarding the transmission of packets transmitted uplink from the user equipment. Also, communication scheduling is performed between a transport node and a transport unit (TU: Transport Unit) in a mobile fronthaul transport network.

[0004] In order to improve the efficiency of these scheduling operations, the distributed unit (O-DU) periodically notifies the transport node of scheduling information at the smallest scheduling unit (TTI: Transmission Time Interval) using the CTI. The transport node performs scheduling control in the transport network based on the scheduling information.

[0005] In order for a "CTI Report message" to be exchanged between a distributed station and a transport node, both the distributed station and the transport node must support the same exchange frequency. In "O-RAN CTI," the minimum value of the exchange frequency is defined as the performance parameter "CTI_MIN." The minimum supported exchange frequency is 250 μs. In addition, the nominal value of the exchange frequency (CTI Nominal message exchange time interval) is defined as the performance parameter "CTI_NOM." The exchange frequency of "CTI messages" between a distributed station and a transport node is determined based on the performance parameter "CTI_NOM." [Prior art documents] [Non-patent literature]

[0006] [Non-Patent Document 1] "Cooperative Transport Interface Transport Control Plane Specification," O-RAN.WG4.CTI-TCP.0-v01.00, O-RAN Fronthaul Working Group 4, November, 2020 Summary of the Invention [Problem to be solved by the invention]

[0007] "O-RAN CTI" specifies that the scheduling information notified periodically should be analyzed at the minimum scheduling unit (TTI). However, "O-RAN CTI" does not specify operations such as analyzing the notified scheduling information when the minimum scheduling unit is shorter than 250 μs (for example, when the minimum scheduling unit is 125 μs or less). In addition, it does not specify a method for notifying scheduling information related to events that occur irregularly.

[0008] For this reason, it is necessary to extend the CTI. When the CTI is extended, not only the scheduling information but also, for example, information specified in the specification number "TS28.552" of the Third Generation Partnership Project (3GPP) and information specified in the specification numbers "TS23.502 4.2.2" and "TS38.401" of the 3GPP may be notified to the wavelength allocation control device as information used for determining whether to switch the wavelength to the optical path (hereinafter referred to as "switching determination information").

[0009] The information specified in specification number "TS28.552" is, for example, information (session information) on the number of user terminals connected in a cell (UE active) and average throughput information of the user terminals.

[0010] The information specified in the specification numbers "TS23.502 4.2.2" and "TS38.401" is, for example, "Registration information" of the user equipment (UE Registration).

[0011] It is also necessary for the distributed station to notify the wavelength allocation controller of the switching decision information using the above-mentioned extended CTI. Here, even if the minimum unit of scheduling is shorter than 250 μs, the wavelength allocation controller analyzes the switching decision information notified using the extended CTI. For example, the wavelength allocation controller analyzes fluctuations in communication bandwidth. Based on the analysis result (prediction result), the wavelength allocation controller reallocates wavelengths to the route (optical path) of the optical signal. In this way, the wavelength allocation controller controls the optical paths in the optical communication system.

[0012] In a 5th generation mobile communication system (5G), a distributed station may notify a wavelength allocation controller of switching judgment information at a cycle of 125 μs or less to support low latency services. When the wavelength allocation controller analyzes the switching judgment information at a cycle of 125 μs or less, the processing load of the wavelength allocation controller for allocating wavelengths to optical paths increases compared to when the wavelength allocation controller analyzes the switching judgment information at a cycle of 250 μs. However, there is a problem in that it is not possible to suppress the increase in the processing load for allocating wavelengths to optical paths.

[0013] In view of the above circumstances, an object of the present invention is to provide a control device, a communication system, a control method, and a program capable of suppressing an increase in the load of the process of allocating wavelengths to optical paths. [Means for solving the problem]

[0014] One aspect of the present invention is a control device that includes an acquisition unit that acquires information regarding one or more events that have occurred within a predetermined period of time from a remote station that notifies the information at a predetermined notification frequency, an information analysis unit that performs analytical processing on the information, a frequency derivation unit that derives the occurrence frequency of the information, a load derivation unit that derives the load of the analytical processing of the information, and a frequency control unit that controls the predetermined notification frequency based on at least one of a result of the analysis of the information, the occurrence frequency of the information, and the load of the analytical processing of the information, with an upper limit set to a frequency lower than the occurrence frequency.

[0015] One aspect of the present invention is a communications system comprising a distributed station and a control device, wherein the distributed station comprises a notification processing unit that notifies information relating to one or more events that have occurred within a predetermined period of time at a predetermined notification frequency, and the control device comprises an acquisition unit that acquires the information, an information analysis unit that performs analytical processing on the information, a frequency derivation unit that derives the occurrence frequency of the information, a load derivation unit that derives the load of the analytical processing of the information, and a frequency control unit that controls the predetermined notification frequency based on at least one of a result of the analysis of the information, the occurrence frequency of the information, and the load of the analytical processing of the information, with an upper limit set to a frequency lower than the occurrence frequency.

[0016] One aspect of the present invention is a control method executed by a control device, the control method including an acquisition step of acquiring information from a remote station that notifies information regarding one or more events that have occurred within a predetermined period of time at a predetermined notification frequency, an information analysis step of performing analytical processing on the information, a frequency derivation step of deriving the occurrence frequency of the information, a load derivation step of deriving the load of the analytical processing of the information, and a frequency control step of controlling the predetermined notification frequency, with an upper limit set to a frequency lower than the occurrence frequency, based on at least one of a result of the analysis of the information, the occurrence frequency of the information, and the load of the analytical processing of the information.

[0017] One aspect of the present invention is a program for causing a computer to function as the above-mentioned control device. Effect of the Invention

[0018] According to the present invention, it is possible to suppress an increase in the load of the process of allocating wavelengths to optical paths. [Brief description of the drawings]

[0019] [Figure 1] FIG. 1 is a diagram illustrating an example of the configuration of a communication system in a first embodiment. [Diagram 2] FIG. 2 is a diagram illustrating an example of the configuration of a wavelength allocation control device in the first embodiment. [Diagram 3]5 is a flowchart showing an example of an operation of the wavelength allocation control device in response to irregular information in the first embodiment. [Figure 4] 5 is a time chart showing an example of an operation of the wavelength allocation control device in response to irregular information in the first embodiment. [Diagram 5] 5 is a flowchart showing an example of an operation of a wavelength allocation control device with respect to periodic information in the first embodiment. [Figure 6] 5 is a time chart showing an example of an operation of the wavelength allocation control device in response to periodic information in the first embodiment. [Figure 7] 10 is a flowchart showing an example of an operation of the wavelength allocation control device in response to irregular information in the second embodiment. [Figure 8] 10 is a time chart showing an example of an operation of the wavelength allocation control device in response to irregular information in the second embodiment. [Figure 9] FIG. 13 is a diagram illustrating an example of the configuration of a communication system in a third embodiment. [Figure 10] FIG. 13 is a diagram illustrating an example of the configuration of a wavelength allocation control device in a third embodiment. [Figure 11] FIG. 2 is a diagram illustrating an example of a hardware configuration of a wavelength allocation control device in each embodiment. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0020] DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be described in detail with reference to the drawings. (First embodiment) FIG. 1 is a diagram showing an example of the configuration of a communication system 1a in the first embodiment. The communication system 1a is a system that communicates using optical signals. The optical signals are transmitted through optical paths. The communication system 1a includes a higher-level device 2, a central station 3, a wavelength allocation control device 4, N (N is an integer equal to or greater than 1) wavelength switching devices 5, M (M is an integer equal to or greater than 1) distributed stations 6, and M wireless stations 7. One or more wireless terminals 8 can be communicatively connected to the wireless station 7 associated with the distributed station 6.

[0021] The higher-level device 2 acquires upstream data from the wireless terminal 8 via the wireless station 7, the distributed station 6, the wavelength switching device 5, and the aggregation station 3. The higher-level device 2 transmits downstream data to the wireless terminal 8 via the aggregation station 3, the wavelength switching device 5, the distributed station 6, and the wireless station 7.

[0022] The central station 3 receives optical signals from one or more remote stations 6. The central station 3 transmits upstream data corresponding to the received optical signals to the higher-level device 2. The central station 3 receives downstream data from the higher-level device 2. The central station 3 transmits optical signals corresponding to the downstream data to each remote station 6.

[0023] The wavelength allocation controller 4 (controller) (wavelength instruction device) acquires switching judgment information (coordination information) notified from the distributed station 6 at a predetermined notification frequency. The coordination information is used for coordination between the wavelength allocation controller 4 and the distributed station 6. The wavelength allocation controller 4 assigns wavelengths to the optical path between the aggregation station 3 and the distributed station 6 based on the analysis result of the switching judgment information and the network topology of the multiple wavelength switching devices 5. The wavelength allocation controller 4 transmits a control signal (hereinafter referred to as an "assignment signal") regarding the assignment of wavelengths to the optical path to each wavelength switching device 5. The assignment signal may include control information of the physical port (for example, "OpenConfig"). The wavelength allocation controller 4 assigns wavelengths to the optical path between the aggregation station 3 and the distributed station 6 using the assignment signal.

[0024] By allocating wavelengths to optical paths, it is possible to control the route (optical path) of an optical signal between the central station 3 and the distributed station 6. For example, when the wireless terminal 8 is communicatively connected only to the distributed station 6-1, the wavelength allocation control device 4 may generate an allocation signal so as to gather a plurality of optical paths to the distributed station 6-1.

[0025] The wavelength allocation controller 4 transmits a control signal (hereinafter referred to as a "frequency signal") regarding the notification frequency of the switching determination information to the remote station 6. This makes it possible to change the notification frequency of the switching determination information from the remote station 6 to the wavelength allocation controller 4.

[0026] The wavelength switching device 5 (transfer device) is, for example, an optical gateway. The wavelength switching device 5 acquires an allocation signal from the wavelength allocation control device 4. The wavelength switching device 5 switches the wavelength of the optical signal between the aggregation station 3 and the distribution station 6 based on the allocation signal. In this way, the wavelength switching device 5 switches the path (optical path) of the optical signal between the aggregation station 3 and the distribution station 6.

[0027] The remote station 6 communicates with one or more wireless terminals 8 (user terminals) via the wireless station 7. The remote station 6 acquires a signal corresponding to the upstream data of the wireless terminal 8 from the wireless station 7. The remote station 6 transmits an optical signal corresponding to the upstream data to the central station 3 using an optical path.

[0028] The remote station 6 transmits switching determination information to the wavelength allocation control device 4 at a notification frequency corresponding to the frequency signal. For example, the remote station 6 transmits switching determination information related to a periodically occurring event (hereinafter referred to as "periodic information") to the wavelength allocation control device 4 at a notification frequency corresponding to the frequency signal. The periodic information is, for example, scheduling information. The notification frequency is, for example, at a cycle of 125 μs.

[0029] For example, the remote station 6 transmits switching determination information related to an event that occurs irregularly (hereinafter referred to as "irregular information") to the wavelength allocation control device 4 at a notification frequency according to the frequency signal. The irregular information is, for example, "Registration information" related to the number of connections (number of sessions) of the wireless terminals 8.

[0030] A wireless station 7 (RU: Radio Unit) executes wireless communication with a wireless terminal 8. The wireless terminal 8 (user terminal) is, for example, a mobile terminal or an IoT (Internet of Things) terminal. The wireless terminal 8 transmits an uplink data signal to the remote station 6 via the wireless station 7. This allows the wireless terminal 8 to transmit the uplink data to the higher-level device 2. The wireless terminal 8 acquires a downlink data signal from the remote station 6 via the wireless station 7. This allows the wireless terminal 8 to acquire the downlink data from the higher-level device 2.

[0031] 2 is a diagram showing an example of the configuration of the wavelength allocation control device 4 in the first embodiment. The wavelength allocation control device 4 includes an acquisition unit 41, an analysis unit 42, a control unit 43, and a frequency signal transmission unit 44. The analysis unit 42 includes a storage processing unit 421, a storage unit 422, an information analysis unit 423, a wavelength switching determination unit 424, a load derivation unit 425, and a frequency control unit 427. The control unit 43 includes a wavelength allocation unit 431 and an allocation signal transmission unit 432. The remote station 6 includes a notification processing unit 61.

[0032] The switching determination information may include, for example, information defined in at least one of "O-RAN CTI", "ITU-T G.989.3 Amd.3 G suppl.66", "3GPP TS28.552", "3GPP TS38.300", "3GPP TS23.502 4.2.2", "3GPP TS38.401", and "3GPP TS23.401 5.3.2".

[0033] For example, the switching determination information (periodic information) may include scheduling information (O-RAN CTI) (ITU-T G.989.3 Amd.3 G suppl.66) of the wireless terminal 8 as information (bandwidth information) related to the traffic volume. The scheduling information may be, for example, downlink control information (DCI). For example, the switching determination information (periodic information) may include average throughput information of the wireless terminal 8 as information related to the traffic volume.

[0034] For example, the switching determination information (irregular information) may include "UE active number" (3GPP TS28.552), which is information on the number of connections of wireless terminal 8 in a cell, as information on the communication connection of wireless terminal 8. For example, the switching determination information (irregular information) may include "Registration information" (UE Registration) (3GPP TS23.502 4.2.2, TS38.401), as information on the number of connections of wireless terminal 8.

[0035] The notification processing unit 61 notifies the acquisition unit 41 of switching determination information (linkage information) at a notification frequency according to the frequency signal acquired from the frequency signal transmission unit 44. The notification processing unit 61 transmits the periodic information to the acquisition unit 41 at a notification frequency according to the frequency signal. The notification frequency of the periodic information is lower than the occurrence frequency of the periodic information.

[0036] The notification processing unit 61 transmits the irregular information to the wavelength allocation control device 4 at a notification frequency according to the frequency signal. The notification frequency of the irregular information is lower than the occurrence frequency of the irregular information.

[0037] The acquisition unit 41 acquires the switching determination information (linkage information) from the notification processing unit 61. The acquisition unit 41 outputs the switching determination information to the storage processing unit 421 every time the acquisition unit 41 acquires the switching determination information.

[0038] The storage processing unit 421 records the notified switching determination information in the storage unit 422. The storage processing unit 421 may record the notified switching determination information in the storage unit 422 in association with the notification time. For example, the storage processing unit 421 records the notified switching determination information in association with the notification time in the storage unit 422 in the form of table information. The storage processing unit 421 may output the notified switching determination information to the frequency control unit 427.

[0039] The storage processing unit 421 outputs the notified switching determination information to the information analysis unit 423. The storage processing unit 421 may output the switching determination information stored in the storage unit 422 to the information analysis unit 423. When a discard instruction signal is input from the frequency control unit 427, the storage processing unit 421 discards the past switching determination information from the storage unit 422.

[0040] The storage unit 422 outputs the switching determination information to the storage processing unit 421 in response to an instruction from the storage processing unit 421. The storage unit 422 stores or discards (deletes) the switching determination information in response to an instruction from the storage processing unit 421.

[0041] The information analysis unit 423 executes a predetermined analysis process on the switching determination information. For example, the information analysis unit 423 derives (predicts) the traffic volume based on periodic information (scheduling information). For example, the information analysis unit 423 derives the amount of change in the number of connections (number of sessions) per unit time for the wireless terminal 8 based on non-periodic information.

[0042] When the amount of change in the number of connections per unit time is equal to or greater than a predetermined threshold, the information analysis unit 423 multiplies the number of sessions by the traffic volume to derive a bandwidth required in the future (prediction result). The information analysis unit 423 outputs the analysis result (prediction result) to the wavelength switching determination unit 424. For example, the analysis result includes information on the bandwidth required in the future. The information analysis unit 423 may output the analysis result (prediction result) to the frequency control unit 427.

[0043] The wavelength switching determination unit 424 (wavelength switching decision unit) determines whether or not to reallocate a wavelength to the optical path based on the analysis result. That is, the wavelength switching determination unit 424 determines whether or not to switch the wavelength of the optical signal transmitted through the optical path based on the analysis result. For example, the wavelength switching determination unit 424 compares the size of a bandwidth required in the future with the currently allocated bandwidth. The wavelength switching determination unit 424 determines whether or not to reallocate a wavelength to the optical path based on the comparison result. For example, if the currently allocated bandwidth is insufficient for the bandwidth required in the future, the wavelength switching determination unit 424 decides to reallocate a wavelength to the optical path. The wavelength switching determination unit 424 outputs a signal instructing wavelength allocation (hereinafter referred to as an "allocation instruction signal") to the wavelength allocation unit 431.

[0044] The wavelength switching determination unit 424 may acquire a signal requesting wavelength allocation (hereinafter referred to as an “allocation request signal”) from the frequency control unit 427. The wavelength switching determination unit 424 outputs an allocation instruction signal to the wavelength allocation unit 431 even when acquiring an allocation request signal.

[0045] The load derivation unit 425 derives the processing load (the analysis processing load of the switching determination information) in the information analysis unit 423. The load derivation unit 425 outputs information indicating the processing load in the information analysis unit 423 (hereinafter referred to as “load information”) to the frequency control unit 427.

[0046] The frequency derivation unit 426 derives the occurrence frequency of the switching determination information notified to the storage processing unit 421. The frequency derivation unit 426 outputs information indicating the occurrence frequency of the notified switching determination information (hereinafter referred to as “frequency information”) to the frequency control unit 427.

[0047] The frequency control unit 427 generates a frequency signal based on at least one of the analysis result of the information for switching determination, the load information of the information analysis unit 423, and the frequency information of the information for switching determination. The frequency control unit 427 generates a frequency signal that indicates a frequency lower than the frequency of occurrence of the information for switching determination.

[0048] For example, when the frequency of occurrence of the switching determination information in a certain time (certain unit period) is equal to or higher than a first threshold, the frequency control unit 427 generates a frequency signal to increase the frequency of notification of the switching determination information, with an upper limit lower than the frequency of occurrence of the switching determination information. The first threshold is determined in advance. The frequency of occurrence of the switching determination information may be the number of occurrences of the switching determination information per unit time in the certain time, or may be the average value of the number of occurrences of the switching determination information per unit time in the certain time.

[0049] The frequency control unit 427 outputs the frequency signal to the frequency signal transmission unit 44. The frequency signal transmission unit 44 transmits the frequency signal to the notification processing unit 61. This controls the notification frequency of the switching determination information.

[0050] The frequency control unit 427 may generate a discard instruction signal when the frequency of occurrence of switching determination information within a certain period of time is less than a first threshold value. This causes past switching determination information to be discarded from the storage unit 422. Since past switching determination information is discarded from the storage unit 422, the amount of switching determination information to be analyzed by the information analysis unit 423 decreases. This makes it possible to suppress an increase in the load of the process of allocating wavelengths to optical paths.

[0051] The frequency control unit 427 may generate an allocation request signal when the frequency of occurrence of the switching determination information in a certain time period is equal to or greater than a second threshold. The second threshold is determined in advance. The absolute value of the second threshold is, for example, greater than the absolute value of the first threshold. The frequency control unit 427 outputs the allocation request signal to the wavelength switching determination unit 424. The frequency control unit 427 may generate an allocation request signal when a change in the frequency of occurrence of the switching determination information in a certain time period is equal to or greater than a predetermined threshold.

[0052] The wavelength allocation unit 431 acquires an allocation instruction signal from the wavelength switching determination unit 424. When the wavelength allocation unit 431 acquires an allocation instruction signal from the wavelength switching determination unit 424, the wavelength allocation unit 431 generates an allocation signal based on the network topology of the multiple wavelength switching devices 5 and the allocation instruction signal. The allocation instruction signal includes, for example, an analysis result by the wavelength switching determination unit 424. The wavelength allocation unit 431 executes allocation of wavelengths to optical paths using the allocation signal. That is, the wavelength allocation unit 431 executes switching of wavelengths for optical paths. The wavelength allocation unit 431 may add and discard wavelengths to and from optical paths.

[0053] The allocation signal transmitter 432 transmits the allocation signal to each wavelength switching device 5. By switching the wavelength of the optical signal, it is possible to control the path (optical path) of the optical signal between the central station 3 and the remote station 6.

[0054] Next, an example of the operation of the communication system 1a will be described. 3 is a flowchart showing an example of the operation of the wavelength allocation control device 4 in response to irregular information in the first embodiment. The frequency derivation unit 426 determines whether a certain time (a certain unit period) has elapsed (step S101). This certain time is not limited to a specific time length, but is, for example, 125 μs. If it is determined that the certain time has not elapsed (step S101: NO), the frequency control unit 427 returns the process to step S101.

[0055] If it is determined that the certain time has elapsed (step S101: YES), the frequency derivation unit 426 determines whether or not notification of irregular information such as information on the number of connections of the wireless terminal 8 (Registration information) has been received within the certain time (step S102). If it is determined that notification of irregular information has not been received within the certain time (step S102: NO), the frequency control unit 427 returns the process to step S101.

[0056] When it is determined that the irregular information has been notified within the fixed time (step S102: YES), the frequency derivation unit 426 derives the frequency of occurrence of the irregular information (step S103). The frequency control unit 427 determines whether the frequency of occurrence of the irregular information is equal to or greater than the first threshold (step S104). When it is determined that the frequency of occurrence of the irregular information is less than the first threshold (step S104: NO), the storage processing unit 421 does not record the irregular information notified within the fixed time in the storage unit 422, and discards the irregular information notified within the fixed time based on a discard instruction signal (step S105). Note that the frequency control unit 427 may generate a frequency signal so as to lower the frequency of notification of the irregular information. For example, the notification frequency after being changed to a lower frequency is half the notification frequency before being changed to a lower frequency. For example, the notification frequency after being changed to a lower frequency may be one-fourth the notification frequency before being changed to a lower frequency.

[0057] If it is determined that the frequency of occurrence of irregular information is equal to or greater than the first threshold (step S104: NO), the frequency control unit 427 generates a frequency signal to increase the notification frequency of irregular information, with an upper limit lower than the frequency of occurrence of irregular information. For example, the notification frequency after being increased is twice the notification frequency before being increased (step S106).

[0058] The frequency control unit 427 may determine whether or not the processing load in the information analysis unit 423 is equal to or greater than a predetermined threshold based on the load information. When it is determined that the load is equal to or greater than the predetermined threshold, the frequency control unit 427 may generate a frequency signal to reduce the frequency of notifying the non-periodic information.

[0059] The frequency control unit 427 determines whether the frequency of occurrence of the irregular information is equal to or greater than the second threshold (step S107). If it is determined that the frequency of occurrence of the irregular information is less than the second threshold (step S107: NO), the frequency control unit 427 returns the process to step S101.

[0060] If it is determined that the frequency of occurrence of the irregular information is equal to or greater than the second threshold (step S107: YES), the frequency control unit 427 outputs an allocation request signal to the wavelength switching determination unit 424 to instruct the wavelength switching determination unit 424 to reallocate the wavelengths (step S108). The frequency control unit 427 returns the process to step S101.

[0061] 4 is a time chart showing an example of the operation of the wavelength allocation control device 4 in response to irregular information in the first embodiment. The irregular information is, for example, "Registration information" which is information on the number of connections (number of sessions) of wireless terminals 8. The information that the information analysis unit 423 should grasp is information on the increase and deletion of bandwidth up to the time of switching the wavelength of the optical path. For this reason, it is not necessary to notify irregular information every time it occurs. Also, it is not necessary to control the wavelength of the optical path every time irregular information occurs.

[0062] The notification processing unit 61 compiles each piece of irregular information generated during a fixed time period (fixed unit cycle) from time t1 to time t2 up to time t2 based on the frequency signal, and notifies the acquisition unit 41. If the frequency of occurrence of irregular information during the fixed time period from time t1 to time t2 is less than a first threshold, the storage processing unit 421 discards from the storage unit 422 the irregular information generated up to time t2.

[0063] No irregular information occurs during the fixed time period from time t2 to time t3, so the notification processing unit 61 does not notify the acquisition unit 41 of the irregular information during the fixed time period from time t2 to time t3.

[0064] The notification processing unit 61 compiles each piece of irregular information generated during a fixed time period from time t3 to time t4 up to time t4 based on the frequency signal and notifies the acquisition unit 41. When the frequency of occurrence of irregular information during a fixed time period from time t3 to time t4 is equal to or greater than a first threshold, the storage processing unit 421 records the irregular information generated during the fixed time period from time t3 to time t4 (irregular information during the latest period) in the storage unit 422. The notification processing unit 61 may generate a frequency signal so as to increase the frequency of notification of irregular information, with a frequency lower than the frequency of occurrence of irregular information as the upper limit. In addition, when the frequency of occurrence of irregular information is equal to or greater than a second threshold, the frequency control unit 427 may output an allocation request signal to the wavelength switching determination unit 424 to instruct the wavelength switching determination unit 424 to reallocate the wavelength. The frequency control unit 427 may generate an allocation request signal when the amount of change in the frequency of occurrence of irregular information during a fixed time period is equal to or greater than a predetermined threshold.

[0065] The notification processing unit 61 compiles each piece of irregular information generated during a certain time period from time t4 to time t5 up to time t5 based on the frequency signal and notifies the acquisition unit 41. If the frequency of occurrence of irregular information during a certain time period from time t4 to time t5 is equal to or greater than a first threshold, the storage processing unit 421 records the irregular information generated during the period from time t4 to time t5 (irregular information for the latest period) in the storage unit 422. The notification processing unit 61 may generate a frequency signal so as to increase the frequency of notification of irregular information, with a frequency lower than the frequency of occurrence of irregular information as the upper limit. In addition, if the frequency of occurrence of irregular information is equal to or greater than a second threshold, the frequency control unit 427 may output an allocation request signal to the wavelength switching determination unit 424 to instruct the wavelength switching determination unit 424 to reallocate the wavelength.

[0066] The notification processing unit 61 compiles each piece of irregular information generated during a fixed time period from time t5 to time t6 up to time t6 based on the frequency signal, and notifies the acquisition unit 41. If the frequency of occurrence of irregular information during a fixed time period from time t5 to time t6 is less than a first threshold, the storage processing unit 421 discards from the storage unit 422 the irregular information generated up to time t6.

[0067] 5 is a flowchart showing an example of the operation of the wavelength allocation control device 4 with respect to the periodic information in the first embodiment. The operation of step S201 is similar to the operation of step S101 shown in FIG.

[0068] If it is determined that the certain time has elapsed (step S201: YES), the frequency derivation unit 426 determines whether or not notification of periodic information such as scheduling information has occurred within the certain time (step S202). If it is determined that notification of periodic information has not occurred within the certain time (step S202: NO), the frequency control unit 427 returns the process to step S201.

[0069] If it is determined that the periodic information has been notified within the certain time (step S202: YES), the frequency control unit 427 derives an index based on the periodic information notified within the certain time. For example, the frequency control unit 427 derives an index based on the analysis result of the periodic information (scheduling information) (step S203).

[0070] This indicator is not limited to a specific indicator, but for example, the amount of data described in each scheduling information notified within a certain period of time, "D n (The subscript "n" is an integer of 1 or more) is the average or total value of this data volume "D n " is, for example, the amount of upstream data scheduled for transmission.

[0071] The indicator is the amount of data written in each scheduling information notified within a certain period of time, "D n Representative value of "D a " is also acceptable.

[0072] The frequency control unit 427 judges whether the index has changed to a predetermined threshold or more (step S204). When it is judged that the amount of change in the index is less than the predetermined threshold (step S204: NO), the frequency control unit 427 outputs a discard instruction signal to the storage processing unit 421, thereby discarding the periodic information within the fixed time up to the previous time from the storage unit 422. That is, the frequency control unit 427 uses the discard instruction signal to discard the periodic information already stored from the storage unit 422 (step S205). The storage processing unit 421 records the periodic information within the latest fixed time (latest period) in the storage unit 422. That is, the storage processing unit 421 records the periodic information within the current fixed time in the storage unit 422 (step S206).

[0073] The frequency control unit 427 judges whether the index is equal to or greater than the third threshold (step S207). If it is judged that the index is equal to or greater than the third threshold (step S207: YES), the storage processing unit 421 records the periodic information within the latest fixed time period (latest period) in the storage unit 422 (step S208). The frequency control unit 427 generates a frequency signal to increase the frequency of notification of the periodic information, with the upper limit set to a frequency lower than the frequency of occurrence of the periodic information (step S209). The frequency control unit 427 returns the process to step S201.

[0074] If it is determined that the index is less than the third threshold (step S207: NO), the storage processing unit 421 records the periodic information within the latest fixed time period (latest period) in the storage unit 422 (step S210). The frequency control unit 427 generates a frequency signal to lower the frequency of notification of the periodic information (step S211). The frequency control unit 427 returns the process to step S201.

[0075] 6 is a time chart showing an example of the operation of the wavelength allocation control device 4 in response to periodic information in the first embodiment. The periodic information is, for example, scheduling information. The scheduling information is, for example, downlink control information. The information that the information analysis unit 423 should grasp is information regarding the increase and deletion of bandwidth up to the time of switching the wavelength of the optical path. For this reason, it is not necessary to notify the periodic information every time it occurs. Also, it is not necessary to control the wavelength of the optical path every time periodic information occurs.

[0076] The notification processing unit 61 compiles each piece of periodic information generated during a fixed time period (fixed unit cycle) from time t11 to time t12 up to time t12 based on the frequency signal, and notifies the acquisition unit 41. For example, each piece of generated periodic information (each piece of scheduling information) is "(time, amount of uplink data) = (t11, D1)". The frequency control unit 427 derives an index based on the analysis result of the periodic information (scheduling information). The index is, for example, the amount of data "D nThe index is the average or total value of the upstream data volume “D n Representative value of "D a The storage processing unit 421 records in the storage unit 422 the periodic information that occurs between time t11 and time t12.

[0077] The notification processing unit 61 compiles each piece of periodic information generated during a fixed time period from time t12 to time t13 up to time t13 based on the frequency signal and notifies the acquisition unit 41. Each piece of generated periodic information (each piece of scheduling information) is, for example, "(time, amount of upstream data)=(t12, D2)". The frequency control unit 427 derives an index based on the analysis result of the periodic information (scheduling information). If the index from time t12 to time t13 is equal to or greater than the third threshold, the storage processing unit 421 records the periodic information within the fixed time period from time t12 to time t13 in the storage unit 422. The frequency control unit 427 generates a frequency signal so as to increase the frequency of notification of the periodic information, with an upper limit lower than the frequency of occurrence of the periodic information.

[0078] The notification processing unit 61 notifies the acquisition unit 41 of each piece of periodic information generated during a fixed time period from time t13 to time t14, by time t14 based on the frequency signal, at a frequency higher than the frequency of notification during a fixed time period from time t12 to time t13. For example, each piece of periodic information (each piece of scheduling information) generated is "(time, amount of upstream data) = (t13, D3)". If the index during the period from time t13 to time t14 is less than the third threshold, the storage processing unit 421 records the periodic information during the fixed time period from time t13 to time t14 in the storage unit 422. The frequency control unit 427 generates a frequency signal to lower the frequency of notification of periodic information.

[0079] The notification processing unit 61 collects each piece of periodic information generated during a fixed time period from time t14 to time t15 up to time t15 based on the frequency signal, and notifies the acquisition unit 41. For example, each piece of periodic information (each piece of scheduling information) generated is "(time, amount of upstream data) = (t14, D4)". The frequency control unit 427 derives an index based on the analysis result of the periodic information (scheduling information). The storage processing unit 421 records the periodic information generated from time t14 to time t15 in the storage unit 422.

[0080] During the fixed time from time t15 to time t16, periodic information similar to the periodic information generated during the fixed time from time t14 to time t15 occurs. Therefore, the storage processing unit 421 discards the periodic information generated up to time t15 from the storage unit 422. The storage processing unit 421 records in the storage unit 422 the periodic information generated between time t15 and time t16 (periodic information for the latest period).

[0081] As described above, the remote station 6 notifies the acquisition unit 41 of switching determination information related to one or more events that have occurred within a certain period of time at a predetermined notification frequency. The acquisition unit 41 acquires the switching determination information from the notification processing unit 61. The information analysis unit 423 executes analysis processing on the switching determination information. The frequency derivation unit 426 derives the occurrence frequency of the switching determination information. The load derivation unit 425 derives the load of the analysis processing of the switching determination information. The frequency control unit 427 controls the predetermined notification frequency of the switching determination information based on at least one of the analysis result (index) of the switching determination information, the occurrence frequency of the switching determination information, and the load of the analysis processing of the switching determination information, with a frequency lower than the occurrence frequency as the upper limit.

[0082] This makes it possible to suppress an increase in the load of the process of allocating wavelengths to optical paths.

[0083] The switching determination information is notified at a notification frequency according to a frequency signal indicating a frequency lower than the occurrence frequency of the switching determination information. This prevents the switching determination information from being notified every time it occurs, thereby preventing the notification frequency from becoming high. There is no need to increase the capacity of the memory unit 422 of the wavelength allocation controller 4. The notified switching determination information may be discarded. Since the capacity of the switching determination information stored in the memory unit 422 is reduced, the wavelength allocation controller 4 does not need to analyze bandwidth fluctuations based on a large amount of switching determination information. The processor of the wavelength allocation controller 4 does not need to be highly functional. Since the processor does not need to be highly functional, the cost of the wavelength allocation controller 4 is prevented from increasing.

[0084] Second embodiment The second embodiment differs from the first embodiment in that the cycle length of the analysis process is variable. The second embodiment will be described focusing on the differences from the first embodiment.

[0085] 7 is a flowchart showing an example of the operation of the wavelength allocation control device 4 for irregular information in the second embodiment. The frequency derivation unit 426 determines whether or not the variable time (variable unit period) has elapsed (step S301). If it is determined that the variable time has not elapsed (step S301: NO), the frequency control unit 427 returns the process to step S301.

[0086] If it is determined that the variable time has elapsed (step S301: YES), the frequency derivation unit 426 determines whether or not notification of non-periodic information, such as information regarding the number of connections of the wireless terminal 8 (Registration information), occurred within the variable time (step S302).

[0087] If it is determined that the irregular information was notified within the variable time (step S302: YES), the frequency derivation unit 426 derives the frequency of occurrence of the irregular information (step S303). The frequency control unit 427 determines whether the frequency of occurrence of the irregular information is equal to or greater than a first threshold (step S304). If it is determined that the frequency of occurrence of the irregular information is less than the first threshold (step S304: NO), the storage processing unit 421 does not record the irregular information notified within the variable time in the storage unit 422, and discards the notified irregular information based on a discard instruction signal (step S305).

[0088] If it is determined that the notification of irregular information was not made within the variable time (step S302: NO), the frequency control unit 427 and the information analysis unit 423 change the variable time in step S301 so as to make it longer than the initial value of the variable time. That is, the information analysis unit 423 lengthens the period of the analysis process. For example, the information analysis unit 423 doubles the period of the analysis process (step S306). The frequency control unit 427 generates a frequency signal so as to lower the frequency of notification of irregular information. For example, the notification frequency after being changed to a lower frequency is half the notification frequency before being changed to a lower frequency (step S307). The frequency control unit 427 returns the process to step S301.

[0089] If it is determined that the frequency of occurrence of irregular information is equal to or greater than the first threshold (step S304: NO), the frequency control unit 427 and the information analysis unit 423 change the variable time in step S301 so as to make it shorter than the initial value of the variable time. That is, the information analysis unit 423 shortens the period of the analysis process. For example, the information analysis unit 423 halves the period of the analysis process (step S308). The frequency control unit 427 generates a frequency signal so as to increase the frequency of notification of irregular information, with a frequency lower than the frequency of occurrence of irregular information as the upper limit. For example, the notification frequency after being increased is twice the notification frequency before being increased (step S309).

[0090] The frequency control unit 427 determines whether the frequency of occurrence of the irregular information is equal to or greater than the second threshold (step S310). If it is determined that the frequency of occurrence of the irregular information is less than the second threshold (step S310: NO), the frequency control unit 427 returns the process to step S301.

[0091] If it is determined that the frequency of occurrence of the irregular information is equal to or greater than the second threshold (step S310: YES), the frequency control unit 427 outputs an allocation request signal to the wavelength switching determination unit 424 to instruct the wavelength switching determination unit 424 to reallocate the wavelengths (step S311). The frequency control unit 427 returns the process to step S301.

[0092] 8 is a time chart showing an example of the operation of the wavelength allocation control device 4 with respect to irregular information in the second embodiment. The notification processing unit 61 compiles each piece of irregular information generated during a variable time from time t21 to time t22 up to time t22 based on the frequency signal, and notifies the acquisition unit 41. If the frequency of occurrence of irregular information during the variable time from time t21 to time t22 is less than the first threshold, the storage processing unit 421 discards from the storage unit 422 the irregular information generated up to time t22.

[0093] No irregular information occurs during the variable time from time t22 to time t23. Therefore, during the variable time from time t22 to time t23, the notification processing unit 61 does not notify the acquisition unit 41 of the irregular information. Since no irregular information occurs, the information analysis unit 423 lengthens the period of the analysis process (period of observation). The frequency control unit 427 generates a frequency signal to lower the frequency of notification of irregular information.

[0094] The notification processing unit 61 compiles each piece of irregular information occurring during a variable time from time t23 to time t25 up to time t25 based on the frequency signal, and notifies the acquisition unit 41. If the frequency of occurrence of irregular information during a variable time (variable unit period) from time t23 to time t25 is equal to or greater than a first threshold, the storage processing unit 421 records the irregular information occurring during the variable time from time t23 to time t25 (irregular information of the latest period) in the storage unit 422. The frequency control unit 427 generates a frequency signal so as to increase the frequency of notification of irregular information, with an upper limit set to a frequency lower than the frequency of occurrence of irregular information. Furthermore, the information analysis unit 423 shortens the period of analysis processing (period of observation).

[0095] The notification processing unit 61 compiles each piece of irregular information generated during a variable time from time t25 to time t26 up to time t26 based on the frequency signal, and notifies the acquisition unit 41. If the frequency of occurrence of irregular information during a variable time from time t25 to time t26 is equal to or greater than a first threshold, the storage processing unit 421 records the irregular information generated during time t23 to time t25 (irregular information for the latest period) in the storage unit 422. If the frequency of occurrence of irregular information is equal to or greater than a second threshold, the frequency control unit 427 outputs an allocation request signal to the wavelength switching determination unit 424 to instruct the wavelength switching determination unit 424 to reallocate wavelengths.

[0096] The notification processing unit 61 compiles each piece of irregular information generated during the variable time from time t26 to time t27 up to time t27 based on the frequency signal, and notifies the acquisition unit 41. If the frequency of occurrence of irregular information during the variable time from time t26 to time t27 is less than the first threshold, the storage processing unit 421 discards from the storage unit 422 the irregular information generated up to time t27.

[0097] As described above, the information analysis unit 423 may lengthen the period of the analysis process. The information analysis unit 423 may shorten the period of the analysis process. The remote station 6 notifies the acquisition unit 41 of the switching determination information related to one or more events that occurred within the variable time at a predetermined notification frequency. The acquisition unit 41 acquires the switching determination information from the notification processing unit 61. The information analysis unit 423 executes an analysis process on the switching determination information. The frequency derivation unit 426 derives the occurrence frequency of the switching determination information. The load derivation unit 425 derives the load of the analysis process of the switching determination information. The frequency control unit 427 controls the predetermined notification frequency of the switching determination information based on at least one of the analysis result (index) of the switching determination information, the occurrence frequency of the switching determination information, and the load of the analysis process of the switching determination information, with a frequency lower than the occurrence frequency as the upper limit.

[0098] This makes it possible to suppress an increase in the load of the process of allocating wavelengths to optical paths.

[0099] Third embodiment The third embodiment differs from the first and second embodiments in that a distributed station control device that controls a distributed station 6 transmits switching determination information to a wavelength allocation control device 4. The third embodiment will be described focusing on the differences from the first and second embodiments.

[0100] 9 is a diagram showing a configuration example of a communication system 1b in the third embodiment. The communication system 1b includes a higher-level device 2, a central station 3, a wavelength allocation control device 4, N wavelength switching devices 5, M distributed stations 6, M wireless stations 7, and a distributed station control device 9. One or more wireless terminals 8 may be communicatively connected to the distributed station 6 via the wireless stations 7. The distributed station control device 9 controls the operation of each of the distributed stations 6. For example, the distributed station control device 9 controls the frequency of notification of switching determination information transmitted from the distributed station 6.

[0101] 10 is a diagram showing an example of the configuration of the wavelength allocation control device 4 in the third embodiment. The frequency signal transmission unit 44 transmits a frequency signal to the distributed station control device 9. The distributed station control device 9 transmits the frequency signal to the notification processing unit 61. The notification processing unit 61 transmits the switching determination information to the acquisition unit 41 at a notification frequency according to the frequency signal acquired from the distributed station control device 9. The acquisition unit 41 acquires the notified switching determination information from the notification processing unit 61. The acquisition unit 41 outputs the switching determination information to the storage processing unit 421 every time it acquires the switching determination information.

[0102] As described above, the distributed station control device 9 controls the operation of each distributed station 6. The distributed station control device 9 controls the frequency of notification of switching determination information transmitted from the distributed station 6 based on the frequency signal.

[0103] This makes it possible to suppress an increase in the load of the process of allocating wavelengths to optical paths, even if a frequency signal is not transmitted to each remote station 6.

[0104] (Hardware configuration example) FIG. 11 is a diagram showing an example of a hardware configuration of the wavelength allocation control device 4 in each embodiment. A part or all of the functional units of the wavelength allocation control device 4 are realized as software by a processor 101 such as a CPU (Central Processing Unit) executing a program stored in a storage device 102 having a non-volatile recording medium (non-transient recording medium) and a storage unit 103. The program may be recorded in a computer-readable non-transient recording medium. The computer-readable non-transient recording medium is, for example, a portable medium such as a flexible disk, a magneto-optical disk, a ROM (Read Only Memory), a CD-ROM (Compact Disc Read Only Memory), or a storage device such as a hard disk built into a computer system. The communication unit 104 executes a predetermined communication process. The communication unit 104 may acquire data and a program.

[0105] Some or all of the functional units of the wavelength allocation control device 4 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), an FPGA (Field Programmable Gate Array), or the like.

[0106] The embodiments may be combined.

[0107] Although an embodiment of the present invention has been described in detail above with reference to the drawings, the specific configuration is not limited to this embodiment, and designs that do not deviate from the gist of the present invention are also included. [Industrial Applicability]

[0108] The present invention is applicable to optical communication systems such as optical access systems. [Explanation of symbols]

[0109] Reference Signs List 1a, 1b...communication system, 2...host device, 3...aggregation station, 4...wavelength allocation control device, 5...wavelength switching device, 6...distributed station, 7...radio station, 8...radio terminal, 9...distributed station control device, 41...acquisition unit, 42...analysis unit, 43...control unit, 44...frequency signal transmission unit, 61...notification processing unit, 101...processor, 102...storage device, 103...storage unit, 104...communication unit, 421...storage processing unit, 422...storage unit, 423...information analysis unit, 424...wavelength switching determination unit, 425...load derivation unit, 426...frequency derivation unit, 427...frequency control unit, 431...wavelength allocation unit, 432...allocation signal transmission unit

Claims

1. an acquisition unit that acquires information on one or more events that have occurred within a predetermined time period from a remote station that notifies the information at a predetermined notification frequency; A frequency derivation unit that derives an occurrence frequency of the information; a frequency control unit that controls the predetermined notification frequency based on an occurrence frequency of the information, with an upper limit being a frequency lower than the occurrence frequency; a storage processing unit that discards the notified information from a storage unit when it is determined that the occurrence frequency of the information is less than a predetermined threshold value; A control device comprising:

2. A communication system including a remote station and a control device, The remote station comprises: a notification processing unit that notifies information relating to one or more events that have occurred within a predetermined time period at a predetermined notification frequency; The control device includes: An acquisition unit for acquiring the information; A frequency derivation unit that derives an occurrence frequency of the information; a frequency control unit that controls the predetermined notification frequency based on an occurrence frequency of the information, with an upper limit being a frequency lower than the occurrence frequency; a storage processing unit that discards the notified information from the storage unit when it is determined that the occurrence frequency of the information is less than a predetermined threshold. Communication systems.

3. A control method executed by a control device, an acquisition step of acquiring information on one or more events occurring within a predetermined time period from a remote station that notifies the information at a predetermined notification frequency; A frequency deriving step of deriving an occurrence frequency of the information; a frequency control step of controlling the predetermined notification frequency based on an occurrence frequency of the information, with an upper limit being a frequency lower than the occurrence frequency of the information; a storage processing step of discarding the notified information from a storage unit when it is determined that the occurrence frequency of the information is less than a predetermined threshold value; A control method comprising:

4. A program for causing a computer to function as the control device according to claim 1.

Images