Communication system, communication control device, and communication control method

Abstract

The present invention aims to operate a wireless access network of a mobile communication network with low power consumption while suppressing degradation in the quality of communication services. [Solution] The present invention relates to a communication system having a plurality of wireless antenna devices, a signal processing device, and an optical transmission path for transmitting data between the wireless antenna devices and the signal processing device. The communication system of the present invention is characterized in that it changes a wireless terminal connected to a wireless antenna device whose communication speed is to be changed to a wireless antenna device of a neighboring cell, performs a communication speed change control process to change the communication speed of the wireless antenna device whose communication speed is to be changed, and changes some or all of the wireless terminals connected to the wireless antenna device of the neighboring cell to the wireless antenna device whose communication speed is to be changed.

Description

[Technical Field]

[0001] The present invention relates to a communication system, a communication control device, and a communication control method, and can be applied to the control of radio base stations in a mobile communication network, for example. [Background technology]

[0002] In a radio access network that constitutes a conventional mobile communication network, RUs (Remote Units) are arranged as antenna base stations (radio antenna devices) for each cell, and DUs / Centralized Units (DUs / CUs) that process signals with the RUs for each cell, and the RUs and DUs / CUs are connected by optical communication lines. Non-patent documents 1 and 2 describe technologies related to communication control including the RUs and DUs / CUs in conventional mobile communication networks.

[0003] Non-Patent Document 1 proposes a method for power-saving operation by changing the speed and modulation method of the optical transmission path between the RU and the DU / CU according to the traffic volume.

[0004] Furthermore, Non-Patent Document 2 proposes that when traffic on the subscriber side is low, some RUs are stopped and instead the radio power of the RUs that are in operation is increased to expand the coverage area of ​​the area where the RUs are stopped, and by accommodating terminals in that area, power consumption can be reduced. [Prior art documents] [Non-patent literature]

[0005] [Non-Patent Document 1] Hiroyuki Saito, Keisuke Nakahira, Masayuki Kashima, Masahiro Sarashina, "Study on Optimizing Communication Rate of PON Systems for Future High-Capacity and Low-Power Mobile Networks," IEICE Technical Report, vol. 123, no. 248, CS2023-66, pp. 19-20, November 2023 [Non-patent document 2] Hiroyuki Saito, Yoshihiro Nakahira, Masayuki Kashima, Masahiro Sarashina, "Research and Development of Mobile Access Network for 6G," IEICE Technical Report, vol. 124, no. 191, CQ2024-53, pp. 60-62, September 2024 Summary of the Invention [Problem to be solved by the invention]

[0006] However, in conventional mobile communication networks, when attempting to change the speed of the optical transmission path between the RU and DU / CU for power-saving operation, there is a problem in that communication may be temporarily halted (i.e., the quality of communication service for users may be reduced) until the processing required for the change (for example, processing to establish bit synchronization and frame synchronization on the receiving side) is completed.

[0007] In view of the above problems, there is a demand for a communication system, a communication control device, and a communication control method that can operate in a power-saving manner while suppressing degradation in the quality of communication services in a wireless access network of a mobile communication network. [Means for solving the problem]

[0008] The first invention of the present invention is a communication system comprising a plurality of wireless antenna devices for transmitting and receiving wireless signals to and from wireless terminals, a signal processing device for processing transmission and reception of signals to and from the wireless terminals via the wireless antenna devices, and an optical communication network for transmitting data between each of the wireless antenna devices and the signal processing devices, the optical communication network having slave station communication devices connected to each of the wireless antenna devices, a master station communication device connected to the signal processing devices, and an optical transmission path connecting the master station communication devices to each of the slave station communication devices, the optical communication network comprising a wireless control management means for managing and controlling each of the wireless antenna devices, cells corresponding to each of the wireless antenna devices, and the wireless terminals connected to each of the wireless antenna devices, and an optical control management means for controlling the communication speed between each of the wireless antenna devices and the signal processing device on the optical communication network. and a wired / wireless cooperative control means for controlling communication of the wireless terminals in each cell via the wireless control management means and the wired control management means, wherein when a wireless antenna device for which a communication speed change is to be performed is found, the wired / wireless cooperative control means performs a first connection change process to change the connection of the wireless terminals connected to the wireless antenna device for which a communication speed change is to be performed to the wireless antenna device of a neighboring cell located near the cell provided by the wireless antenna device for which the communication speed change is to be performed, and after the first connection change process, performs a communication speed change control process to change the communication speed of the wireless antenna device for which the communication speed change is to be performed, and after the communication speed change control process, performs a second connection change process to change the connection of some or all of the wireless terminals connected to the wireless antenna device of the neighboring cell to the wireless antenna device for which the communication speed change is to be performed.

[0009] The second aspect of the present invention is a communication control device for controlling a communication system comprising a plurality of wireless antenna devices for transmitting and receiving wireless signals to and from wireless terminals, a signal processing device for processing transmission and reception of signals to and from the wireless terminals via the wireless antenna devices, and an optical communication network for transmitting data between each of the wireless antenna devices and the signal processing devices, the optical communication network having slave station communication devices connected to each of the wireless antenna devices, a master station communication device connected to the signal processing devices, and an optical transmission path connecting the master station communication device to each of the slave station communication devices, the communication control device comprising: a wireless control management means for managing and controlling each of the wireless antenna devices, cells corresponding to each of the wireless antenna devices, and the wireless terminals connected to each of the wireless antenna devices; and a communication control means for controlling a communication speed between each of the wireless antenna devices and the signal processing device on the optical communication network. and a wired and wireless cooperative control means for controlling the communication of the wireless terminals in each cell via the wireless control management means and the wired control management means, wherein when a wireless antenna device for which a communication speed change is to be performed is found, the wired and wireless cooperative control means performs a first connection change process to change the connection of the wireless terminals connected to the wireless antenna device for which a communication speed change is to be performed to the wireless antenna device of a neighboring cell located near the cell provided by the wireless antenna device for which the communication speed change is to be performed, and after the first connection change process, performs a communication speed change control process to change the communication speed of the wireless antenna device for which the communication speed change is to be performed, and after the communication speed change control process, performs a second connection change process to change the connection of some or all of the wireless terminals connected to the wireless antenna device of the neighboring cell to the wireless antenna device for which the communication speed change is to be performed.

[0010] The third aspect of the present invention provides a communication control method performed by a communication control device that controls a communication system including a plurality of wireless antenna devices that transmit and receive wireless signals to and from wireless terminals, a signal processing device that processes transmission and reception of signals to and from the wireless terminals via the wireless antenna devices, and an optical communication network that transmits data between each of the wireless antenna devices and the signal processing device, the optical communication network having slave station communication devices connected to each of the wireless antenna devices, a master station communication device that connects to the signal processing device, and an optical transmission path that connects the master station communication devices to each of the slave station communication devices. The communication control device has a wireless control management means, a wired control management means, and a wired / wired cooperation control means, the wireless control management means manages and controls each of the wireless antenna devices, cells corresponding to each of the wireless antenna devices, and the wireless terminals connected to each of the wireless antenna devices, and the wired control management means manages and controls the optical communication network. and a wired / wireless cooperation control means for controlling a communication speed between each of the wireless antenna devices and the signal processing device on a network, the wired / wireless cooperation control means controlling communication of the wireless terminals in each cell via the wireless control management means and the wired control management means, and when a wireless antenna device for which a communication speed change is to be performed is found, the wired / wireless cooperation control means performs a first connection change process to change the connection of the wireless terminals connected to the wireless antenna device for which a communication speed change is to be performed to the wireless antenna device of a neighboring cell located near the cell to which the wireless antenna device for which the communication speed change is to be performed, after the first connection change process, performs a communication speed change control process to change the communication speed of the wireless antenna device for which the communication speed change is to be performed, and after the communication speed change control process, performs a second connection change process to change the connection of some or all of the wireless terminals connected to the wireless antenna device of the neighboring cell to the wireless antenna device for which the communication speed change is to be performed. [Effects of the Invention]

[0011] According to the present invention, it is possible to operate a radio access network of a mobile communication network in a power-saving manner while suppressing degradation in the quality of communication services. [Brief explanation of the drawings]

[0012] [Figure 1] 1 is a block diagram showing the overall configuration of a communication system according to a first embodiment. [Figure 2] 1 is a block diagram showing an example of the internal configuration of a radio access network according to a first embodiment. [Figure 3] FIG. 1 is a diagram (part 1) showing an example (first scenario) of state transitions of each cell for explaining the operation of the communication system according to the first embodiment. [Figure 4] FIG. 2 is a diagram (part 2) showing an example (first scenario) of state transitions of each cell for explaining the operation of the communication system according to the first embodiment. [Figure 5] FIG. 10 is a diagram (part 3) showing an example (first scenario) of state transitions of each cell for explaining the operation of the communication system according to the first embodiment. [Figure 6] FIG. 10 is a diagram (part 4) showing an example (first scenario) of state transitions of each cell to explain the operation of the communication system according to the first embodiment. [Figure 7] FIG. 10 is a diagram (part 5) showing an example (first scenario) of state transitions of each cell to explain the operation of the communication system according to the first embodiment. [Figure 8] FIG. 10 is a diagram (part 6) illustrating an example (first scenario) of state transitions of each cell to explain the operation of the communication system according to the first embodiment. [Figure 9] FIG. 10 is a diagram (part 7) illustrating an example (first scenario) of state transitions of each cell to explain the operation of the communication system according to the first embodiment. [Figure 10] FIG. 10 is a diagram (part 8) illustrating an example (first scenario) of state transitions of each cell to explain the operation of the communication system according to the first embodiment. [Figure 11] FIG. 10 is a diagram (part 1) illustrating an example (second scenario) of state transitions of each cell for explaining a problem associated with the communication system of the first embodiment. [Figure 12]FIG. 10 is a diagram (part 2) illustrating an example (second scenario) of state transitions of each cell for explaining a problem associated with the communication system of the first embodiment. [Figure 13] FIG. 10 is a block diagram showing the overall configuration of a communication system according to a second embodiment. [Figure 14] FIG. 10 is a diagram (part 1) showing an example (third scenario) of state transition of each cell for explaining the operation of the communication system according to the second embodiment. [Figure 15] FIG. 10 is a diagram (part 2) showing an example (third scenario) of state transitions of each cell for explaining the operation of the communication system according to the second embodiment. [Figure 16] FIG. 10 is a diagram (part 3) showing an example (third scenario) of state transitions of each cell for explaining the operation of the communication system according to the second embodiment. [Figure 17] FIG. 10 is a block diagram showing an example of the internal configuration of a radio access network according to a modified example of the first embodiment. DETAILED DESCRIPTION OF THE INVENTION

[0013] (A) First embodiment A first embodiment of a communication system, a communication control device, and a communication control method according to the present invention will be described below in detail with reference to the drawings.

[0014] (A-1) Configuration of the First Embodiment FIG. 1 is a block diagram showing the overall configuration of a communication system 1 according to the first embodiment.

[0015] The communication system 1 is a mobile communication network system (for example, a network system of a communication carrier or the like) for connecting wireless terminals TE, and includes a plurality of wireless access networks 100 (100-1, 100-2, ...), a communication control device 10 that controls each wireless access network 100, and a mobile core network 71. Each wireless access network 100 and the communication control device 10 are connected to the mobile core network 71. As shown in FIG. 1, the mobile core network 71 may be connected to external networks such as the Internet 73 and a network 74 of another communication carrier.

[0016] Next, the internal configuration of each wireless access network 100 will be described with reference to FIG.

[0017] FIG. 2 is a block diagram showing an example of the internal configuration of the wireless access network 100-1.

[0018] For ease of explanation, the internal configuration of each wireless access network 100 will be described as being the same, but some parts (for example, the number of devices) may be different.

[0019] Each radio access network 100 includes N RUs (Radio Units) 50 (50-1 to 50-N) as antenna devices that transmit and receive radio signals and convert them into electrical signals, DU / CUs (Distributed Units / Centralized Units) 20 as signal processing devices that modulate and demodulate the electrical signals transmitted and received by each RU 50, an optical communication network 101 as an optical transmission path connecting each RU 50 and the DU / CU 20 via a PON (Passive Optical Network), and the DU / CU 20. The RU 50 transmits and receives radio signals to and from radio terminals TE subscribed to a mobile communication network formed by the communication system 1. The DU / CU 20 communicates with the radio terminal TE via the RU 50.

[0020] The optical communication network 101 has an OLT (Optical Line Terminal) 30 as a parent station communication device and N ONUs (Optical Network Units) 40 (40-1 to 40-N) as child station communication devices. The OLT 30 is connected to an optical fiber 60, which is branched into N (multiple branches for the ONUs 40) by a splitter 70, and each branch is connected to the ONUs 40-1 to 40-N. The optical fiber 60 and the splitter 70 are also included in the optical communication network 101. Note that the configuration for branching the optical fiber 60 is not limited to the configuration in FIG. 1, and a configuration in which multiple splitters 70 are used to branch the optical fiber 60 in multiple stages (hierarchically) may also be used.

[0021] In this embodiment, a single optical transmission path (optical fiber 60) is shared between the OLT 30 and multiple ONUs 40 using WDM (Wavelength Division Multiplexing) and TDMA (Time Division Multiple Access) (TWDM). That is, each OLT 30 is WDM compatible and can communicate with each ONU 40 using one of multiple wavelengths. Furthermore, under each OLT 30, multiple ONUs 40 can share a transmission path formed by one wavelength using TDMA.

[0022] In this embodiment, each OLT 30 and ONU 40 is assumed to support multiple communication speed operation modes. In other words, each OLT 30 is assumed to be capable of communicating with each ONU 40 at a different communication speed for each wavelength. In this embodiment, each OLT 30 and ONU 40 is assumed to support a mode operating at either 25 Gbps or 10 Gbps, but the number and combination of supported modes are not limited to this. Furthermore, the OLT 30 and ONU 40 tend to consume more power as the communication speed increases (in this embodiment, the power consumption is assumed to be approximately twice as high at 10 Gbps as at 25 Gbps).

[0023] Next, an example of the internal configuration of the OLT 30 and the ONU 40 will be described with reference to FIG.

[0024] As described above, the OLT 30 and ONU 40 (optical communication network 101) of this embodiment are compatible with WDM / TDMA, and therefore must have a configuration such as that shown in FIG.

[0025] As shown in FIG. 2, the OLT 30 includes an electrical switch 31, M (M is any number equal to or greater than 1) OSUs 32-1 to 32-M, L (L is any number equal to or greater than 1) OSUs 33-1 to 33-L, an optical space switch 34, and a wavelength multiplexing unit 35.

[0026] The OSUs 32 and 33 are elements that function as "optical subscriber units" and are capable of PtMP (Point To Multipoint) connection with multiple ONUs 40 via optical fiber 60. The OSUs 32 and 33 are connected to the optical fiber 60 via an optical space switch 34 and a wavelength multiplexer 35. Here, the OSUs 32 and 33 have different communication speeds with the ONUs 40. Specifically, the OSUs 32 and 33 will be described as supporting 10 Gbps and 25 Gbps, respectively. Note that the types (communication speeds) and number (combinations) of OSUs included in the OLT 30 are not limited. The OSUs 32-1 to 32-M and OSUs 33-1 to 33-L can communicate with corresponding ONUs 40 (ONUs 40 controlled to communicate at the same wavelength) using different wavelengths (which may be fixed wavelengths or may be dynamically changeable).

[0027] The electric switch 31 is connected to the upper side (DU / CU 20) to switch electric signals, and is also connected to each of the OSUs 32 and 33 on the lower side.

[0028] The wavelength multiplexing unit 35 is connected to the optical fiber 60 by wavelength division multiplexing (WDM), and is also connected to the optical space switch 34 on the upstream side.

[0029] The optical space switch 34 switches the connection relationship of optical signals between the wavelength multiplexing unit 35 and each of the OSUs 32 and 33 .

[0030] Each ONU 40 has an optical multiplexer / demultiplexer 41, optical transmitters / receivers 42 and 43, and an electrical switch 44. The optical transmitters / receivers 42 and 43 transmit and receive optical signals to and from the PON side (optical fiber 60 side) at different speeds, and function as photoelectric conversion units connected to the downstream electrical switch 31. The optical multiplexer / demultiplexer 41 branches optical signals received from the PON side (optical fiber 60 side) to the optical transmitters / receivers 42 and 43, and combines the optical signals received from the optical transmitters / receivers 42 and 43 and sends them to the PON side (optical fiber 60 side). The electrical switch 31 is connected to the downstream RU 50 and switches electrical signals.

[0031] The optical transceivers 42 and 43 each have a different communication speed for communicating with the OLT 30. In this description, the optical transceiver 42 is assumed to support 10 Gbps, and the optical transceiver 43 is assumed to support 25 Gbps. The types (communication speeds) and numbers (combinations) of optical transceivers included in the ONU 40 are not limited. Each ONU 40 operates only one of the optical transceivers 42 and 43 under control from the OLT 30, and connects to one of the OSUs (OSUs assigned by the OLT 30) using light of a wavelength under control from the OLT 30. In other words, in this embodiment, the ONU 40 is equipped with multiple optical transceivers with different communication speeds and can switch between them, thereby supporting multi-rate connection to the PON side at one of multiple communication speeds.

[0032] In the communication system 1 of this embodiment, the OLT 30 and the ONU 40 are configured as described above, thereby realizing a WDM / TDMA (TWDM) PON.

[0033] Next, an example of the internal configuration of the OLT 30 and the ONU 40 will be described with reference to FIG.

[0034] As described above, the OLT 30 and ONU 40 (optical communication network 101) of this embodiment are compatible with WDM / TDMA, and therefore must have a configuration such as that shown in FIG.

[0035] As shown in Figure 2, the OLT 30 has an electrical switch 31 connected to the upper side (DU / CU 20) and switching electrical signals, a wavelength multiplexing unit 35 connected to the optical communication network 101 (optical fiber 60) via wavelength division multiplexing (WDM), OSUs (Optical Subscriber Units) 32, 33 connected via PON (MtMP) to one or more ONUs 40 via each optical communication network 101 (optical fiber 60), and an optical space switch 34 switching optical signals between the wavelength multiplexing unit 35 and each OSU 32, 33.

[0036] OSUs 32 and 33 are also connected to the upper side (electrical switch 31). OSUs 32 and 33 have different communication speeds when connected to PON (optical fiber 60). Here, OSU 32 is described as supporting 10 Gbps, and OSU 33 is described as supporting 25 Gbps. As shown in FIG. 2, OLT 30 in this embodiment includes M (M is any number equal to or greater than 1) OSUs 32-1 to 32-M and L (L is any number equal to or greater than 1) OSUs 33-1 to 33-L. The types (communication speeds) and numbers (combinations) of OSUs included in OLT 30 are not limited.

[0037] OSU32-1 to 32-M and OSU33-1 to 33-L can each communicate with a corresponding ONU 40 (an ONU 40 assigned to communicate at the same wavelength) at a different wavelength (which may be a fixed wavelength or a dynamically changeable wavelength).

[0038] Each ONU 40 has an optical multiplexer / demultiplexer 41, optical transmitters / receivers 42 and 43, and an electrical switch 44. The optical transmitters / receivers 42 and 43 transmit and receive optical signals to and from the PON side (optical fiber 60 side) at different speeds, and also function as transceivers (optical-electrical conversion units) connected to the downstream electrical switch 31. The optical multiplexer / demultiplexer 41 demultiplexes optical signals received from the PON side (optical fiber 60 side) to the optical transmitters / receivers 42 and 43, and multiplexes the optical signals received from the optical transmitters / receivers 42 and 43 and sends them to the PON side (optical fiber 60 side). The electrical switch 31 is connected to the downstream RU 50 and switches electrical signals.

[0039] The optical transceivers 42 and 43 each have a different communication speed for connecting to the PON (optical fiber 60). Here, the optical transceiver 42 is described as supporting 10 Gbps, and the optical transceiver 43 is described as supporting 25 Gbps. The types (communication speeds) and numbers (combinations) of optical transceivers included in the ONU 40 are not limited. In each ONU 40, only one of the optical transceivers 42 and 43 is activated under control of the OLT 30 to connect to the PON side (optical fiber 60), and to connect to one of the OSUs. In other words, in this embodiment, the ONU 40 is provided with multiple optical transceivers with different communication speeds and can switch between them, thereby supporting multi-rate connections to the PON side at one of multiple communication speeds.

[0040] The ONUs 40-1 to 40-N are connected to the RUs 50-1 to 50-N, respectively. A mobile core network 71 (e.g., a core network of a telecommunications carrier) is connected to the upper side of the DU / CU 20. The DU / CU 20 performs a DU function that performs physical layer processing of signals (e.g., modulation, demodulation, etc.) and MAC layer communication control, and a CU function that controls packet communication between the RUs 50 and the mobile core network 71 and manages the radio resources of each RU 50.

[0041] In the communication system 1, each RU 50 is in charge of wireless communication within one area (hereinafter referred to as a "cell") in principle, and connects to a radio terminal TE within the cell under the control of the DU / CU 20.

[0042] As described above, each RU 50 can communicate with the DU / CU 20 via the optical communication network 101, and can further communicate with the mobile core network 71 via the DU / CU 20.

[0043] The mobile core network 71 may be configured to handle connection settings and various management functions (e.g., management functions such as billing) for each radio terminal TE via each DU / CU 20. The mobile core network 71 may also be configured to have a wide-area data relay function by transferring user data (data transmitted and received by each radio terminal TE) to each DU / CU 20. Furthermore, as described above, the mobile core network 71 may also be connected to external networks (e.g., the Internet 73, other telecommunications carrier networks 74, etc.) and may be capable of communicating with terminals and servers beyond these networks.

[0044] The communication control device 10 is configured to be able to control the PON section (wired section) by connecting to the optical communication network 101 (OLT 30) of each wireless access network 100 via a wired control network 72. The specific configuration of the wired control network 72 is not limited, and various network configurations such as an IP network can be applied.

[0045] Next, the configuration of the communication control device 10 will be described.

[0046] The communication control device 10 is responsible for an orchestration function that controls and operates the entire communication system 1, and as part of this orchestration function, has a presence / absence coordination function unit 11. The presence / absence coordination function unit 11 has a coordination control processing unit 12 as wired / wireless coordination control means, a wireless control management function unit 13 as wireless control management means, and a wired control management function unit 14 as wired control management means.

[0047] The radio control management function unit 13 has the function of controlling radio communications with the mobile core network 71, the DU / CU 20, the RU 50, and the radio terminal TE (hereinafter referred to as "radio control").

[0048] The wired control management function unit 14 has the function of controlling (hereinafter referred to as "wired control") communications in the optical communication network 101 (OLT 30, ONU 40). As described above, the wired control management function unit 14 controls the optical communication network 101 (OLT 30, ONU 40) via the wired control network 72.

[0049] The linked control processing unit 12 performs control processing linking the wired section (the section between the OLT 30 and the ONU 40) and the wireless section (the section between the DU / CU 20 and the RU 50) via the wireless control management function unit 13 and the wired control management function unit 14.

[0050] The radio control management functional unit 13 can collect and store information related to the area (hereinafter referred to as "cell") corresponding to each RU 50. The radio control management functional unit 13 assigns an identification number (hereinafter referred to as "cell number") to each cell (each RU 50) and manages it. The radio control management functional unit 13 also stores information on the positional relationship of each cell (map information). There are no limitations on the method by which the radio control management functional unit 13 stores various information (hereinafter referred to as "cell information") related to each cell (each RU 50). For example, the radio control management functional unit 13 may collect cell information from an upper-level device (e.g., DU / CU 20) that controls each RU 50.

[0051] (A-2) Operation of the First Embodiment Next, the operation of the communication system 1 according to the first embodiment will be described. Here, the operation will be described focusing on the process in which the communication control device 10 controls the radio access network 100-1.

[0052] 3 to 10 are diagrams showing an example of state transition of each cell (hereinafter referred to as "first scenario") for explaining the operation of the communication system 1 of the first embodiment.

[0053] 3 to 10 respectively show the states of steps S101 to S106 that constitute the first scenario of the above-mentioned state transition.

[0054] 3 to 10, nine cells C-1 to C-9 controlled by the communication control device 10 are illustrated in map format. The cells C-1 to C-9 are formed by RUs 50-1 to 50-9, respectively. The RUs 50-1 to 50-9 are connected to ONUs 40-1 to 40-9. Here, the cells C-1 to C-9 are arranged in a 3×3 matrix. Here, it is assumed that cell numbers 1 to 9 are assigned to the cells C-1 to C-9 (RUs 50-1 to 50-9), respectively. In FIGS. 3 to 10, it is assumed that the thickness of the lines (lines corresponding to the branched optical fibers 60) from the splitter 70 to each cell (each ONU 40) represents the allocated bandwidth (the bandwidth allocated by the OLT 30).

[0055] In the first scenario, an example of processing will be described that focuses on four cells C-1 to C-4 among the cells C-1 to C-9. As shown in Figs. 3 to 10, a radio terminal TE exists in each of the cells C-1 to C-4. Although there may be tens to thousands of radio terminals in each cell that constitutes an actual mobile communication network of a communication carrier, for ease of explanation, Figs. 3 to 10 illustrate only one to three radio terminals TE in each cell. Specifically, Figs. 3 to 10 illustrate the radio terminal TE-1 in cell C-1, the radio terminal TE-2 in cell C-2, the radio terminals TE-3 and TE-4 in cell C-3, and the radio terminals TE-5, TE-6, and TE-7 in cell C-4.

[0056] Next, the premise of the first example scenario shown in FIGS. 3 to 10 will be described.

[0057] In the first scenario shown in Figures 3 to 10, it is assumed that there is a time period with low traffic demand in cells C-1 to C-4, and one cell (one RU50 / ONU40) is able to accommodate all radio terminals TE in cells C-1 to C-4.

[0058] For example, let us assume that the required bandwidth (hereinafter simply referred to as "traffic") in the upstream and downstream directions in each of cells C-1 to C-4 is slightly less than 10 Gbps (e.g., approximately 9 Gbps), and that operating the communication speed between the OLT 30 and each ONU 40 (ONUs 40-1 to 40-4) at 10 Gbps results in a traffic volume that is relatively just right for bandwidth utilization efficiency. In this case, four corresponding OSUs 32 on the OLT 30 side are each operating at 10 Gbps on different wavelengths. Also, there is another OSU connected to ONUs 40-5 to 40-9. Then, as time passes, the traffic volume in cells C-1 to C-4 decreases (e.g., it becomes late at night or early in the morning, and traffic volume decreases). In this case, it is assumed that the total traffic of all cells C-1 to C-4 is 24 Gbps (for example, the traffic of each cell is 6 Gbps), and that if the transmission power (transmission power during wireless communication) of RU 50-4 located in cell C-4 is increased, all of the traffic can be accommodated. In this case, by changing the communication speed between ONU 40-4 and OLT 30 in cell C-4 from 10 Gbps to 25 Gbps mode, it is possible to ensure sufficient bandwidth (the required 24 Gbps or more) between RU 50-4 and DU / CU 20. With this accommodation change, the equipment in cells C-1 to C-3 (RUs 50-1 to 50-3, ONUs 40-1 to 40-3, etc.) that do not accommodate the wireless terminal TE and the three OSUs 32 in the OLT 30 connected thereto can be stopped (powered off) or operated in a power-saving mode (power-saving mode), thereby reducing the power consumption of the entire system. However, when changing the communication speed as described above, it is necessary to execute a switching process (for example, a process involving restarting or resynchronizing communication) in RU50-4 and ONU40-4 of cell C-4. For example, when changing the communication speed between ONU40-4 in cell C-4 and ONU40 in OLT30 and the connected OSU from 10 Gbps to 25 Gbps (changing the connection destination from OSU32 to OSU33), if the process remains as is, communication will be temporarily stopped (communication between ONU40-4 and one OSU in OLT30 connected to it will be stopped), and wireless terminals TE-5 to TE-7 connected to RU50-4 will be unable to communicate.Therefore, in this embodiment, the presence / absence cooperation function unit 11 (cooperation control processing unit 12) performs control to avoid communication outages due to the above-mentioned change in communication speed (hereinafter referred to as "communication outage avoidance control"). The first scenario shown in Figures 3 to 10 shows an example of communication outage avoidance control when the above-mentioned communication speed change is performed.

[0059] In the following, when the cooperation control processing unit 12 decides to aggregate and accommodate radio terminals TE in a plurality of cells into one cell, all of the plurality of cells to be aggregated (cells C-1 to C-4 in the first scenario) will be referred to as "aggregation target cells," the cell to which the aggregation target cells are aggregated (cell C-4 in the first scenario) will be referred to as "aggregation destination cell," and the cell (C-1 to C-3 in the first scenario) from which the radio terminal TE is to be transferred to the aggregation destination cell (transfer source) will be referred to as "transfer source cell." Also, in the following, the cell to which the communication speed change is to be performed (cell C-4 in the first scenario) will be referred to as "communication speed change target cell," and the cell to which the radio terminal TE is to be evacuated from the communication speed change target cell (cells C-1 to C-3 in the first scenario) will also be referred to as "evacuation destination cell."

[0060] Next, each step of the first scenario shown in FIGS. 3 to 10 will be described.

[0061] First, in the state of step S101 (FIGS. 3 and 4), it is assumed that all radio terminals TE are performing radio communication with RUs 50 present in the cell in which the respective radio terminals TE are located. In the state of step S101, it is assumed that all ONUs 40-1 to 20-4 are connected to the OLT 30 in a 10 Gbps communication speed mode. Then, in the state of step S101, it is assumed that a time period with low traffic demand has occurred in cells C-1 to C-4, and the presence / absence interlocking function unit 11 has determined to change (change accommodation) the communication speed of cell C-4 (the communication speed between ONUs 40-4 and OLT 30) to 25 Gbps and connect all radio terminals TE in cells C-1 to C-4 to RUs 50-4 in cell C-4. Note that, in the state of step S101, it is assumed that the traffic in each of cells C-1 to C-4 is 6 Gbps, as described above. In other words, it is assumed that the total traffic in cells C-1 to C-4 is 24 Gbps in the state of step S101.

[0062] Note that even in the state of step S101, radio waves from RUs 50 (base stations) of cells (hereinafter referred to as "neighboring cells") neighboring (surrounding) the cell in which the radio terminal TE is located are actually reaching each radio terminal TE at a slightly weak noise level. Therefore, FIG. 4 illustrates a state in which radio terminals TE5 to TE7 in cell C-4 are weakly picking up radio waves from RUs 50 of neighboring cells (connected to the RUs 50 of neighboring cells by dotted lines). Radio terminals TE in cells C-1 to C-4 should also be weakly picking up radio waves from RUs 50 of neighboring cells, but this is not shown to avoid complication. In the state illustrated in FIG. 4, the cooperation control processing unit 12 instructs the cooperation control processing unit 12 to increase the radio waves (transmission power) of RUs 50-1 to 50-3 in cells C-1 to C-3 (evacuation destination cells) and to decrease the radio waves (transmission power) of RU 50-4 in cell C-4 (the cell whose communication speed is to be changed). In this case, the radio terminal TE in cell C-4 will mistakenly believe that it is located in one of cells C-1 to C-3 rather than in cell C-4 (recognizing that the radio waves arriving from at least RUs 50-1 to 50-3 in cells C-1 to C-3 are better), and will switch its connection destination to one of the RUs 50-1 to 50-3. As a result, the states of cells C-1 to C-4 transition to the state in step S102 (FIG. 5). At this time, the amount by which the transmission power (intensity of transmission power) of the RUs 50 (RUs 50-1 to 50-3) of the evacuation destination cell is adjusted and the amount by which the transmission power (intensity of transmission power) of the RU 50 (RU 50-4) of the communication speed change target cell is adjusted can be set to any value (for example, a value derived in advance by design, experiment, etc.).

[0063] 5, in step S102, the connection destination of the radio terminal TE-5 is switched to RU 50-3 in cell C-3, the connection destination of the radio terminal TE-6 is switched to RU 50-1 in cell C-1, and the connection destination of the radio terminal TE-7 is switched to RU 50-2 in cell C-2. In the state of step S102, it is assumed that the traffic of 6 Gbps of the radio terminal TE in cell C-4 is accommodated at 2 Gbps each in the RUs 50 in cells C-1 to C-3. In other words, in the state of step S102, it is assumed that the traffic in each of cells C-1 to C-3 is 8 Gbps (24 Gbps in total).

[0064] Although not shown in Figure 5, radio waves from the RU 50-4 in cell C-4 are also weakly reaching the radio terminals TE in cells C-1 to C-3. However, in this state, the RU 50-4 in cell C-4 is not in use (no radio terminal TE is connected), so even if communication between the ONU 40-4 in cell C-4 and the OLT 30 is interrupted, no problem will occur in the communication service of the radio terminal TE. Therefore, the cooperation control processor 12 performs processing to switch the communication speed between the ONU 40-4 in cell C-4 and the OLT 30 from 10 Gbps to 25 Gbps at this timing. In Figure 5, the thick line between the ONU 40-4 and the OLT 30 indicates that communication is being performed at 25 Gbps.

[0065] After that, the communication speed between the ONU 40-4 and the OLT 30 in the cell C-4 is synchronized at 25 Gbps, and communication between the RU 50-4 and the DU / CU 20 is restored. Furthermore, after that, the cooperative control processing unit 12 instructs the RU 50-4 in the cell C-4 to slightly increase the radio wave (transmission power). As a result, the states of the cells C-1 to C-4 transition to the state in step S103 (FIG. 6). At this time, the amount by which the transmission power (intensity of the transmission power) of the RU 50 (RU 50-4) in the cell whose communication speed is to be changed can be set to any value (for example, a value derived in advance through design, experiment, etc.).

[0066] In the state of step S103, the radio terminal TE in cell C-4 is also receiving radio waves from RU 50-4 in C-4 (in FIG. 6, the radio terminals TE-5 to TE-7 in cell C-4 are also connected to RU 50-4 by dotted lines). Here, it is assumed that the cooperation control processing unit 12 issues an instruction to return the radio wave strength of RUs 50-1 to 50-4 from the state of step S103 to the same state as in step S101 (FIG. 4). As a result, the states of cells C-1 to C-4 transition to the state of step S104 (FIGS. 7 and 8).

[0067] In the state of step S104 (FIG. 7), the connection state of each wireless terminal TE in cells C-1 to C-4 returns to the same state as in step S101 (however, at the time of step S104, the communication speed of ONU 40-4 in cell C-4 has increased to 25 Gbps).

[0068] In the state of step S104, the radio terminal TE in each of the cells C-1 to C-3 also weakly picks up radio waves from the RU 50-4 in the cell C-4. Therefore, FIG. 8 shows a state in which the radio terminals TE1 to TE4 in the cells C-1 to C-3 weakly pick up radio waves from the RU 50 in the neighboring cell (connected to the RU 50-4 in the cell C-4 by the dotted line). Now, let us assume that, from the state of step S104, the cooperation control processing unit 12 issues an instruction to strengthen the radio waves (transmission power) of the RU 50-4 in the cell C-4 and to weaken the radio waves of the RUs 50-1 to 50-3 in the cells C-1 to C-3. In this case, the radio terminal TE in each of the cells C-1 to C-3 mistakenly believes that it is located in the cell C-4 rather than in the cell C-1 to C-3 (recognizing that at least the radio waves arriving from the RU 50-4 in the cell C-4 are better), and switches its connection to the RU 50-4. As a result, the states of cells C-1 to C-4 transition to the state in step S105 (FIG. 9). At this time, the amount by which the transmission power (intensity of transmission power) of the RU 50 (RUs 50-1 to 50-3) of the evacuation destination cell is adjusted and the amount by which the transmission power (intensity of transmission power) of the RU 50 (RU 50-4) of the communication speed change target cell is adjusted can be set to any value (for example, a value derived in advance through design, experiment, etc.).

[0069] In the state of step S105 (FIG. 9), the RUs 50-1 to 50-3 and the ONUs 40-1 to 40-3 in the cells C-1 to C-3 are not in use (no radio terminals TE are connected), so even if they are stopped (powered off) or put into a power-saving operating state (power-saving mode), no problems will occur in the communication service of the radio terminals TE. Therefore, from the state of step S105, the cooperation control processor 12 controls the RUs 50-1 to 50-3 and the ONUs 40-1 to 40-3 to transition to a power-saving operating state (power-saving mode). In addition, the three OSUs 32 in the OLT 30 that were communicating with these ONUs at 10 Gb / s also transition to a power-saving mode or a stopped state. As a result, the states of the cells C-1 to C-4 transition to the state of step S106 (FIG. 10).

[0070] In Figure 10, the fact that ONUs 40-1 to 40-3 and RUs 50-1 to 50-3 are not in use (have transitioned to a stopped or power-saving operating state) is represented by erasing the lines to the OLT 30 side (splitter 70) (however, the physical connection remains, and in fact, ONUs 40-5 to 40-9 in cells C5 to C9 remain connected to the OLT 30 via splitter 70).

[0071] In the above processing of steps S101 to S106, the operation of the radio terminal TE to switch the connected RU 50 is a simplified version of a technique called "hard handover." There are no specific limitations on the specific processing for handing over the radio terminal TE between RUs 50, and for example, the technology described in Reference 1 below may be used. [Reference 1] JP 2009-130740 A

[0072] In addition, since there may be a brief interruption in connection when handing over a radio terminal TE between RUs 50, it is desirable to avoid this by using a technique in which the radio terminal TE performs switching while simultaneously communicating with multiple RUs 50. Specifically, the above switching can be realized by using a technique called DAPS (Dual Active Protocol Stack) described in Reference 2 below. [Reference 2] 3GPP (registered trademark), "5G;NR;NR and NG-RAN Overall description;Stage-2 (3GPP TS 38.300 version 16.4.0 Release 16)", ETSI TS 138 300 V16.4.0 (2021-01), [Retrieved February 14, 2025], <URL:https: / / www.etsi.org / deliver / etsi_ts / 138300_138399 / 138300 / 16.04.00_60 / ts_138300v160400p.pdf>

[0073] (A-3) Effects of the First Embodiment According to the first embodiment, the following effects can be achieved.

[0074] In the communication system 1 of the first embodiment, even if communication between the ONU 40 and the OLT 30 is temporarily interrupted when the communication speed between a specific RU 50 and the upper side is changed, the control processing (communication outage avoidance control) of the cooperative control processing unit 12 can prevent data loss between the radio terminal TE and the mobile core network 71. Specifically, the cooperative control processing unit 12 temporarily evacuates the radio terminal TE connected to the RU 50 whose communication speed is to be changed to an RU 50 in a neighboring cell, changes the communication speed of the optical transmission path (between the ONU 40 and the OLT 30) connected to the RU 50 whose communication speed is to be changed, and performs processing to switch back the connection of the evacuated radio terminal TE.

[0075] Furthermore, in the communication system 1 of the first embodiment, by utilizing the handover function in mobile communication, it is possible to prevent communication interruptions when changing the connection of the radio terminal TE between the RUs 50.

[0076] (B) Second embodiment As a prerequisite for a detailed description of the second embodiment, the problems with the communication system 1 of the first embodiment will be described with reference to FIGS.

[0077] 11 and 12 are diagrams showing an example of state transition of each cell (hereinafter referred to as "second scenario") for explaining the problem associated with the communication system 1 of the first embodiment.

[0078] 11 and 12 each show the states of steps S201 to S202 that constitute the second scenario.

[0079] In the second scenario shown in Fig. 11 and Fig. 12, nine cells C-1 to C-9 controlled by the communication control device 10 are illustrated in map format. In Fig. 11 and Fig. 12, one or more wireless terminal groups TEG each composed of a large number of wireless terminals TE are illustrated in the cells C-1 to C-4. In Fig. 11 and Fig. 12, the wireless terminal group TEG-1 is arranged in the cell C-1, the wireless terminal group TEG-2 in the cell C-2, the wireless terminal group TEG-3 in the cell C-3, and the wireless terminal groups TEG-4 to TEG-6 in the cell C-4. In Fig. 11 and Fig. 12, the total value (unit: [Gbps]) of traffic (requested bandwidth) requested by the included wireless terminals TE is added to each wireless terminal group TEG. Therefore, as shown in Fig. 11, the traffic of the wireless terminal groups TEG-1 to TEG-6 is 10 Gbps, 6 Gbps, 4 Gbps, 3 Gbps, 3 Gbps, and 2 Gbps, respectively. Three wireless terminal groups TEG-4 to TEG-6 are located in cell C-4, and therefore the total traffic of the entire cell C-4 is 8 Gbps.

[0080] 11, in cell C-4, wireless terminal group TEG-4 is made up of wireless terminals TE located closer to cell C-3, and wireless terminal groups TEG-5 and TEG-6 are made up of wireless terminals TE located closer to cell C-2. Here, it is also assumed that wireless terminal group TEG-6 is closer to RU50-2 in cell C-2 than wireless terminal group TEG-5.

[0081] First, the state of step S201 (FIG. 11) in the second scenario will be described.

[0082] In step S201, each of the radio terminals TE of the radio terminal groups TEG-1 to TEG-6 is connected to the RU 50 of the cell in which the radio terminal is located. Also, assume that the communication speed between the ONUs 40-1 to 40-4 and the OLT 30 is 10 Gbps at the time of step S201. In the state of step S201, the total traffic of the cells C-2 to C-4 is 18 Gbps. Here, assume that the cooperation control processing unit 12 has decided to accommodate all of the radio terminals TE of the radio terminal groups TEG-2 to TEG-6 of the cells C-2 to C-4 in the RU 50-4 of the cell C-4. Here, assume that accommodating up to the traffic of the cell C-1 (10 Gbps) in the RU 50-4 of the cell C-4 would exceed the upper limit of the communication speed (25 Gbps even if the communication speed is changed). Therefore, assume that the cooperation control processing unit 12 has decided to leave the radio terminal group TEG-1 of the cell C-1 as it is. At the time of step S201, the communication speed between the ONU 40-4 and the OLT 30 in cell C-4 is 10 Gbps, and this needs to be changed to 25 Gbps. Therefore, the cooperation control processing unit 12 performs a process of evacuating the radio terminals TE in C-4 to the RUs 50-2 and 50-3 in cells C-2 and C-3 so that communication is not interrupted during the change of communication speed. Specifically, the cooperation control processing unit 12 strengthens the radio waves of the RUs 50-2 and 50-3 in cells C-2 and C-3 and further weakens the radio waves of the RU 50-4 in cell C-4, thereby distributing and reaccommodating the radio terminals TE of the radio terminal groups TEG-4 to TEG-6 to the RUs 50-2 and 50-3 in cells C-2 and C-3. As a result, the states of cells C-2 to C-4 transition to the state in step S202 (FIG. 12).

[0083] As described above, in cell C-4, the wireless terminal group TEG-4 is made up of wireless terminals TE located closer to cell C-3, and is therefore connected to RU-3 in cell C-3 in the state of step S202. Also, the wireless terminal groups TEG-5 and TEG-6 are made up of wireless terminals TE located closer to cell C-2, and are therefore connected to RU 50-2 in cell C-2 in the state of step S202. In other words, at the time of step S202, RU 50-2 in cell C-2 is accommodating wireless terminals TE with a total traffic of 11 Gbps, which exceeds the line capacity of 10 Gbps, and there is a risk of degradation in the communication quality of the wireless terminals TE under control of RU 50-2.

[0084] As described above, in the communication system 1 of the first embodiment, when the distribution of radio terminals TE is uneven as in the second scenario above, there is a problem that the communication lines of some cells may overflow when the accommodation is changed.

[0085] (B-1) Configuration of the second embodiment FIG. 13 is a block diagram showing the overall configuration of a communication system 1A according to the second embodiment.

[0086] In FIG. 13, the same or corresponding parts as those in FIG. 1 are denoted by the same or corresponding reference numerals.

[0087] The following describes the second embodiment and the differences from the first embodiment.

[0088] The communication system 1A of the second embodiment differs from the first embodiment in that the communication control device 10 is replaced with a communication control device 10A. Also, the communication control device 10A differs from the first embodiment in that the presence / absence cooperation function unit 11 is replaced with a presence / absence cooperation function unit 11A. Furthermore, the presence / absence cooperation function unit 11A differs from the first embodiment in that the cooperation control processing unit 12 is replaced with a cooperation control processing unit 12A.

[0089] The cooperative control processing unit 12A has an evacuated radio terminal / area selection function unit 121 as an element that performs control processing to solve the problem of communication lines of some cells overflowing when accommodation is changed, as in the second scenario above. The evacuated radio terminal / area selection function unit 121 holds the current traffic volume in each cell, the position of each radio terminal TE, radio wave reception strength, traffic volume, etc., from the radio control management function unit 13 as information necessary for control processing.

[0090] (B-2) Operation of the Second Embodiment Next, the operation of the communication system 1A according to the second embodiment will be described, focusing on the process in which the communication control device 10A controls the radio access network 100-1.

[0091] 14 to 16 are diagrams showing an example of state transition of each cell (hereinafter referred to as "third scenario") for explaining the operation of the communication system 1A of the second embodiment.

[0092] The initial state (step S301) of the third scenario can be shown using the above-mentioned Figure 11. In other words, the initial state of the third scenario (the state of step S301) is the same as the initial state of the above-mentioned second scenario (the state of step S201), so a detailed explanation will be omitted. Also, Figures 14 to 16 show the states of steps S302 to S304 that constitute the third scenario, respectively. Figures 14 to 16 also illustrate the states of cells C-1 to C-4, etc., in the same format as the above-mentioned Figure 11.

[0093] First, in the state of step S301 (FIG. 11), it is assumed that the cooperation control processing unit 12A has decided to accommodate the radio terminals TE of the radio terminal groups TEG-2 to TEG-6 of the cells C-2 to C-4 in the RU 50-4 of the cell C-4. Therefore, in the third scenario, the cell C-4 becomes the target cell for communication speed change (aggregation destination cell), and the cells C-2 and C-3 become evacuation destination cells (source cells).

[0094] At this time, it is assumed that the evacuation wireless terminal / area selection function unit 121 of the cooperation control processing unit 12A has determined that cells C-2 and C-3 (RUs 50-2 and 50-3) are evacuation destination cells for the wireless terminals TE of the wireless terminal group TEG-4 to TEG-6 of cell C-4. Then, it is assumed that the cooperation control processing unit 12A (evacuation wireless terminal / area selection function unit 121) has acquired current traffic information for the evacuation destination cells C-2 and C-3 (information indicating that the traffic of cell C-2 is 6 Gbps and the traffic of cell C-3 is 4 Gbps). Next, the cooperation control processing unit 12A slightly increases the radio wave (transmission strength) of only the RU 50-3 of cell C-3, which has the least current traffic among the evacuation destination cells. As a result, the states of cells C-2 to C-4 transition to the state in step S302 (FIG. 14).

[0095] As described above, in cell C-4, the wireless terminal group TEG-4 is composed of wireless terminals TE located closer to cell C-3. Therefore, in the state of step S302, the wireless terminals TE of the wireless terminal group TEG-4 are connected to RU 50-3 of cell C-3. Then, in the state of step S302, the traffic of cell C-3 (RU 50-3) becomes 7 Gbps in total, which is opposite to the traffic (6 Gbps) of cell C-2, the other evacuation destination, and cell C-2 becomes the evacuation destination with less traffic. Therefore, from the state of step S302, the cooperation control processing unit 12A slightly increases the radio wave (transmission strength) of only the RU 50-2 of cell C-2, which is the evacuation destination with the least current traffic. As a result, the states of cells C-2 to C-4 transition to the state of step S303 (FIG. 15).

[0096] As described above, since the distance to the RU 50-2 of cell C-2 of the wireless terminal group TEG-6 is shorter than that of the wireless terminal group TEG-5, it is assumed that the wireless terminal TE of the wireless terminal group TEG-6 is connected to the RU 50-2 of cell C-2 at the time of step S303. In this case, in the state of step S303, the total traffic of cell C-2 (RU 50-2) is 8 Gbps, which is greater than the total traffic of cell C-3 (7 Gbps), resulting in a reversal of the relationship. Therefore, from the state of step S303, the cooperation control processing unit 12A slightly increases the radio wave (transmission strength) of only the RU 50-3 of cell C-3, which is the evacuation destination cell with the least current traffic. As a result, the states of cells C-2 to C-4 transition to the state of step S304 ( FIG. 16 ).

[0097] At the time of step S304, the radio terminal TE of the radio terminal group TEG-5 is connected to the RU 50-3 of the cell C-3. As a result, all of the radio terminals TE of the radio terminal groups TEG-4 to TEG-6 that were originally connected to the cell C-4 (RU 50-4) have completed evacuation to the evacuation destination (cell C-2 or cell C-3). Thereafter, the cooperation control processing unit 12A changes the communication speed between the ONU 40-4 and the OLT 30 of the cell C-4 to 25 Gbps, as in the first embodiment, and then performs processing to switch all of the radio terminals TE of the radio terminal groups TEG-1 to TEG-6 to the RU 50-4 of the cell C-4 (not shown in the drawing).

[0098] As described above, in the second embodiment, a cell with low traffic (hereinafter referred to as a "low-traffic cell") is selected from the evacuation destination cells (cells C-2 and C-3 in the third scenario) and the process of increasing transmission power is repeated to prompt a change of connection of the radio terminal TE from the communication speed change target cell (cell C-4 in the third scenario) to the evacuation destination cell. Note that, at this time, the amount of adjustment of transmission power at one time for the low-traffic cell can be set to any value (for example, a value derived in advance by design, experiment, etc.).

[0099] (B-3) Effects of the Second Embodiment According to the second embodiment, in addition to the effects of the first embodiment, the following effects can be achieved.

[0100] The communication system 1A (cooperative control processor 12A) of the second embodiment selects a cell with less traffic among the evacuation destination cells and repeats the process of gradually increasing the power of the RU 50. As a result, the communication system 1A of the second embodiment can balance the traffic among the evacuation cells and prevent the traffic of the evacuation cells from overflowing.

[0101] (C) Other embodiments The present invention is not limited to the above-described embodiments, and may include modified embodiments such as those exemplified below.

[0102] (C-1) In the first and second embodiments, the intensity of the transmission power of the RU 50 is used as a parameter for prompting the radio terminal TE to change its connection destination from the communication speed change target cell to the evacuation destination cell. However, other parameters may be used. For example, a parameter representing the priority (weight) when the radio terminal TE selects a connection destination RU 50 (hereinafter referred to as "connection destination priority") may be used as a parameter for prompting the radio terminal TE to change its connection destination from the communication speed change target cell to the evacuation destination cell. For example, the cooperation control processing unit 12 may notify each radio terminal TE of the connection priority value for each RU 50 via the DU / CU 20, so that the mobile terminal TE preferentially connects to an RU 50 with a high connection destination priority. In this way, the cooperation control processing unit 12 can prompt the radio terminal TE to change its connection destination to the evacuation destination by setting the connection destination priority of the evacuation destination cell higher than that of the speed change target cell.

[0103] In addition, in the first and second embodiments, as a method of prompting a radio terminal TE to change its connection destination from a communication speed change target cell to a destination cell, instead of using a parameter for each RU50, it is also possible to perform control (direct control) on each radio terminal TE to change its connection destination to the destination cell.

[0104] (C-2) In the second embodiment, the cooperation control processing unit 12A may suppress overflow of the evacuation cell by processing other than the above. For example, when there are multiple evacuation cells, the cooperation control processing unit 12A may strengthen the radio waves (radio waves of the RUs 50) of cells with less traffic until the traffic of each evacuation cell becomes equal. While maintaining the state in which the traffic of all evacuation cells becomes equal, the cooperation control processing unit 12A may gradually strengthen the radio waves of each evacuation cell to gradually increase the number of accommodated radio terminals TE (accommodated traffic) so that all radio terminals TE of the communication speed change target cell are accommodated in the evacuation cell. Furthermore, for example, the cooperation control processing unit 12A may set a value calculated in advance based on the location information and radio wave intensity information of each radio terminal TE in the communication speed change target cell as to what strength of the radio waves of each RU 50 of each evacuation destination cell is necessary to accommodate distributed communication without overflow. However, if only the distribution of traffic between evacuation cells is simply considered, the communication quality of a specific radio terminal TE (for example, the radio wave state with the RU 50) may deteriorate when the radio terminal TE moves to the evacuation destination cell, which may result in a decrease in traffic in the evacuation destination cell. Therefore, for example, when the cooperation control processing unit 12A moves the radio terminal TE of the communication speed change target cell to the evacuation destination cell, the cooperation control processing unit 12A may distribute and accommodate the radio terminal TE with the worst communication quality in each RU 50 so that the communication quality is as good as possible. Furthermore, for example, when the cooperation control processing unit 12A moves the radio terminal TE of the communication speed change target cell to the evacuation destination cell, the cooperation control processing unit 12A may give up on rescuing the radio terminal TE with poor communication quality and distribute and accommodate the radio terminals TE with the best possible communication quality in each RU 50.

[0105] (C-3) In each of the above embodiments, only a configuration in which a PtMP (Point To Multipoint) connection is established between the OLT 30 and the ONU 40 that constitute the wireless access network 100 has been described, but it may also include a configuration in which a PtP (Point To Point) connection is established, as shown in FIG. 17.

[0106] FIG. 17 is a block diagram showing an example of the internal configuration of a radio access network 100B (configuration of a radio access network according to a modified example of the embodiment).

[0107] The following describes the differences between the wireless access network 100B and the wireless access network 100.

[0108] In a wireless access network 100B shown in FIG. 17, the OLT 30 and the ONU 40 are replaced with an OLT 30B and an ONU 40B.

[0109] The OLT 30 and ONU 40 in the first embodiment are configured to support only 10 Gbps or 25 Gbps MtMP connections, but the wireless access network 100B differs in that it also supports 100 Gbps PtP connections.

[0110] Specifically, OLT 30B differs from OLT 30 in that it additionally includes a media converter 36 (an element that performs optical-to-electrical conversion of signals) that supports transmission and reception of 100 Gbps optical signals. In OLT 30B, P (P is an integer of 1 or greater) media converters 36-1 to 36-P are arranged between electrical switch 31 and optical space switch 34. Furthermore, OLT 30B includes k (k is an integer of 2 or greater) wavelength multiplexing units 35-1 to 35-k, and PONs (optical fibers 60 and N ONUs 40B) are connected to each wavelength multiplexing unit 35. In OLT 30B, each of OSUs 32, 33 and each media converter 36 can be connected to ONUs 40B at different wavelengths.

[0111] For example, if an RU50 requiring a bandwidth (communication speed) of 25 Gbps or more appears in the wireless access network 100B, one of the media converters 36 can be assigned to the ONU 40B connected to the RU50 and connected via PtP, thereby allocating a bandwidth (communication speed) of 100 Gbps to the RU50.

[0112] (C-4) In each of the above embodiments, all ONUs 40, 40B are configured to communicate with the OSUs or media converters in the directly connected OLTs 30, 30B, but it is also possible to provide an optical fiber (not shown) that connects from the optical space switch 34 to other OLTs 30, 30B, and to communicate indirectly with other OLTs 30, 30B via the optical fiber. [Explanation of symbols]

[0113] 1, 1A... communication system, 10, 10A... communication control device, 11, 11A... presence / absence coordination function unit, 12, 12A... wired / wireless coordination control processing unit, 121... evacuation wireless terminal / area selection function unit, 13... wireless control management function unit, 14... wired control management function unit, 20... DU / CU, 30... OLT, 40... ONU, 50... RU, 60... optical fiber, 70... splitter, 71... mobile core network, 72... wired control network, 73... Internet, 74... other telecommunications carrier network, 100... wireless access network, 101... optical communication network, C... cell, TE... wireless terminal, TEG... wireless terminal group

Claims

1. A communication system comprising: a plurality of wireless antenna devices for transmitting and receiving wireless signals to and from wireless terminals; a signal processing device for processing transmission and reception of signals to and from the wireless terminals via the wireless antenna devices; and an optical communication network for transmitting data between each of the wireless antenna devices and the signal processing devices, wherein the optical communication network has a slave station communication device connected to each of the wireless antenna devices, a master station communication device connected to the signal processing device, and an optical transmission path connecting the master station communication device to each of the slave station communication devices, a radio control management means for managing and controlling each of the radio antenna devices, a cell corresponding to each of the radio antenna devices, and the radio terminals connected to each of the radio antenna devices; a wired control management means for controlling a communication speed between each of the wireless antenna devices and the signal processing device on the optical communication network; a wired / wireless cooperative control means for controlling communication of the wireless terminals in each cell via the wireless control management means and the wired control management means; When a wireless antenna device for which a communication speed change is to be performed occurs, the wired and wireless cooperation control means performs a first connection change process to change the connection of the wireless terminal connected to the wireless antenna device for which a communication speed change is to be performed to the wireless antenna device of a neighboring cell located near a cell to which the wireless antenna device for which the communication speed change is to be performed belongs, and after the first connection change process, performs a communication speed change control process to change the communication speed of the wireless antenna device for which the communication speed change is to be performed, and after the communication speed change control process, performs a second connection change process to change the connection of some or all of the wireless terminals connected to the wireless antenna device of the neighboring cell to the wireless antenna device for which the communication speed change is to be performed. A communication system comprising:

2. The wired and wireless cooperation control means In the second connection change process, all of the wireless terminals connected to the wireless antenna device of the neighboring cell are caused to change their connections to the wireless antenna device that is the communication speed change target; After the second connection change process, a power saving control process is performed to stop the wireless antenna device and the slave station communication device of the neighboring cell or to control them to a state where they operate with less power.

2. The communication system according to claim 1.

3. The communication system according to claim 1, characterized in that the wired and wireless cooperation control means performs the first connection change process and the second connection change process by adjusting the strength of the transmission power during wireless communication between the wireless antenna device to be changed in communication speed and the wireless antenna device of the neighboring cell.

4. 4. The communication system according to claim 3, wherein the wired / wireless cooperation control unit, when performing the first connection change process, repeats a process of increasing the intensity of the transmission power of the wireless antenna device of the neighboring cell with less traffic.

5. The communication system according to claim 3, characterized in that, when performing the first connection change process, the wired and wireless cooperation control means adjusts the intensity of the transmission power of the wireless antenna device of the neighboring cell so that the communication quality of the wireless terminal that changes its connection to the wireless antenna device of the neighboring cell is equal to or higher than a predetermined value.

6. The communication system according to claim 1, characterized in that the wired and wireless cooperation control means performs the first connection change process and the second connection change process by adjusting parameters related to connection priority set to the wireless antenna device to be the communication speed change target and the wireless antenna device of the neighboring cell.

7. The communication system according to claim 1, characterized in that the wired and wireless cooperation control means performs the first connection change process and the second connection change process by directly controlling the wireless antenna device to which the communication speed change is to be made and the wireless terminal connected to the wireless antenna device of the neighboring cell.

8. A communication control device for controlling a communication system comprising: a plurality of wireless antenna devices for transmitting and receiving wireless signals to and from wireless terminals; a signal processing device for processing transmission and reception of signals to and from the wireless terminals via the wireless antenna devices; and an optical communication network for transmitting data between each of the wireless antenna devices and the signal processing devices, the optical communication network having a slave station communication device connected to each of the wireless antenna devices, a master station communication device connected to the signal processing devices, and an optical transmission path connecting the master station communication device to each of the slave station communication devices, a radio control management means for managing and controlling each of the radio antenna devices, a cell corresponding to each of the radio antenna devices, and the radio terminals connected to each of the radio antenna devices; a wired control management means for controlling a communication speed between each of the wireless antenna devices and the signal processing device on the optical communication network; a wired / wireless cooperative control means for controlling communication of the wireless terminals in each cell via the wireless control management means and the wired control management means; When a wireless antenna device for which a communication speed change is to be performed occurs, the wired and wireless cooperation control means performs a first connection change process to change the connection of the wireless terminal connected to the wireless antenna device for which a communication speed change is to be performed to the wireless antenna device of a neighboring cell located near a cell to which the wireless antenna device for which the communication speed change is to be performed belongs, and after the first connection change process, performs a communication speed change control process to change the communication speed of the wireless antenna device for which the communication speed change is to be performed, and after the communication speed change control process, performs a second connection change process to change the connection of some or all of the wireless terminals connected to the wireless antenna device of the neighboring cell to the wireless antenna device for which the communication speed change is to be performed. A communication control device characterized by:

9. A communication control method performed by a communication control device that controls a communication system including a plurality of wireless antenna devices that transmit and receive wireless signals to and from wireless terminals, a signal processing device that processes transmission and reception of signals to and from the wireless terminals via the wireless antenna devices, and an optical communication network that transmits data between each of the wireless antenna devices and the signal processing devices, the optical communication network having slave station communication devices connected to each of the wireless antenna devices, a master station communication device connected to the signal processing devices, and optical transmission paths that connect the master station communication devices to each of the slave station communication devices, the communication control device includes a wireless control management means, a wired control management means, and a wired / wireless cooperation control means; the radio control management means manages and controls each of the radio antenna devices, cells corresponding to each of the radio antenna devices, and the radio terminals connected to each of the radio antenna devices; the wired control management means controls the communication speed between each of the wireless antenna devices and the signal processing device on the optical communication network; the wired and wireless cooperation control means controls communication of the wireless terminals in each cell via the wireless control management means and the wired control management means; When a wireless antenna device for which a communication speed change is to be performed occurs, the wired and wireless cooperation control means performs a first connection change process to change the connection of the wireless terminal connected to the wireless antenna device for which a communication speed change is to be performed to the wireless antenna device of a neighboring cell located near a cell to which the wireless antenna device for which the communication speed change is to be performed belongs, and after the first connection change process, performs a communication speed change control process to change the communication speed of the wireless antenna device for which the communication speed change is to be performed, and after the communication speed change control process, performs a second connection change process to change the connection of some or all of the wireless terminals connected to the wireless antenna device of the neighboring cell to the wireless antenna device for which the communication speed change is to be performed. A communication control method comprising:

Images