Communication system, communication control device, and communication control method

Abstract

Regarding wireless access networks for mobile communication networks, the goal is to operate them with low power consumption while suppressing a decline 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 data transmission between the wireless antenna devices and the signal processing device. The communication system of the present invention is characterized by causing a wireless terminal connected to a wireless antenna device to be changed in communication speed to be connected to a wireless antenna device in a neighboring cell, performing a communication speed change control process to change the communication speed of the wireless antenna device to be changed, and causing some or all of the wireless terminals connected to the wireless antenna device in a neighboring cell to be changed in communication speed to be connected to the wireless antenna device 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, for example, control of a radio base station in a mobile communication network. [Background Art]

[0002] In a radio access network constituting a conventional mobile communication network, an RU (Remote Unit) serving as an antenna base station (radio antenna device) for each cell, and a DU / CU (Distributed Unit / Centralized Unit) that performs signal processing with the RU of each cell are arranged, and the RU and the DU / CU are connected via an optical communication line. In conventional mobile communication networks, the technologies of Non-Patent Documents 1 and 2 exist as technologies related to communication control including RU and DU / CU.

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

[0004] In addition, Non-Patent Document 2 proposes that when traffic on the subscriber side is low, some RUs are stopped, and instead, the radio power of operating RUs is increased to expand the coverage area of the area where the stopped RUs were located, and terminals in that area are accommodated, thereby reducing power consumption. [Prior Art Documents] [Non-Patent Documents]

[0005] [Non-Patent Document 1] Hiroyuki Saito, Keisuke Nakadaira, Masayuki Kushima, Masaharu Sarashina, "Study on Communication Rate Optimization of PON Systems for Future Large-Capacity and Low-Power Consumption Mobile Networks", IEICE Technical Report, vol.123, no.248, CS2023-66, pp.19-24, November 2023 [Non-Patent Document 2] Hiroyuki Saito, Yoshihiro Nakahira, Masayuki Kashima, and Masahiro Sarashina, "Research and Development of Mobile Access Networks for 6G," IEICE Technical Report, vol.124, no.191, CQ2024-53, pp.60-62, September 2024. [Overview of the project] [Problems that the invention aims to solve]

[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 that communication may be temporarily interrupted (i.e., the quality of communication service to the user may be reduced) until the processing for that change (for example, the process of establishing bit synchronization and frame synchronization on the receiving side) is completed.

[0007] In light of the above-mentioned problems, there is a need for a communication system, communication control device, and communication control method that can operate wireless access networks of mobile communication networks with low power consumption while suppressing a deterioration in the quality of communication services. [Means for solving the problem]

[0008] The first aspect of the present invention is a communication system comprising: a plurality of wireless antenna devices that transmit and receive wireless signals with a wireless terminal; a signal processing device that performs signal transmission and reception processing with the wireless terminal via the wireless antenna devices; and an optical communication network that performs data transmission between each of the wireless antenna devices and the signal processing device, 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 that connects the master station communication device to each of the slave station communication devices, and each of the wireless antenna devices, a cell corresponding to each of the wireless antenna devices, a wireless control management means for managing and controlling the wireless terminal connected to each of the wireless antenna devices, and a means for controlling the communication speed between each of the wireless antenna devices and the signal processing device on the optical communication network. The system comprises a wired control management means and a wired / wireless cooperation control means that controls the communication of the wireless terminals of each cell via the wireless control management means and the wired control management means, wherein 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 subject to the communication speed change to the wireless antenna device of a neighboring cell located near the cell provided by the wireless antenna device subject to the communication speed change when the wireless antenna device subject to the communication speed change occurs, after the first connection change process, performs a communication speed change control process to change the communication speed of the wireless antenna device subject to the communication speed change, and after the communication speed change control process, performs a second connection change process to change some or all of the wireless terminals connected to the wireless antenna device of the neighboring cell to the wireless antenna device subject to the communication speed change.

[0009] The second aspect of the present invention relates to a communication control device that controls a communication system comprising: a plurality of wireless antenna devices that transmit and receive wireless signals with a wireless terminal; a signal processing device that performs signal transmission and reception processing with the wireless terminal via the wireless antenna devices; and an optical communication network that performs data transmission between each of the wireless antenna devices and the signal processing device, 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 that connects the master station communication device to each of the slave station communication devices, and the communication control device controls each of the wireless antenna devices, a cell corresponding to each of the wireless antenna devices, a wireless control management means for managing and controlling the wireless terminal connected to each of the wireless antenna devices, and the communication speed between each of the wireless antenna devices and the signal processing device on the optical communication network. The system comprises a wired control management means for controlling a wired network, and a wired-wireless cooperation control means for controlling the communication of the wireless terminals of each cell via the wireless control management means and the wired control management means, wherein the wired-wireless cooperation control means, when a wireless antenna device subject to a communication speed change occurs, performs a first connection change process to change the connection of the wireless terminals connected to the wireless antenna device subject to a communication speed change to the wireless antenna device of a neighboring cell located near the cell provided by the wireless antenna device subject to a communication speed change; after the first connection change process, performs a communication speed change control process to change the communication speed of the wireless antenna device subject to a communication speed change; and after the communication speed change control process, performs a second connection change process to change some or all of the wireless terminals connected to the wireless antenna device of the neighboring cell to the wireless antenna device subject to a communication speed change.

[0010] The third aspect of the present invention relates to a communication control method performed by a communication control device that controls a communication system comprising: a plurality of wireless antenna devices that transmit and receive wireless signals with wireless terminals; a signal processing device that performs signal transmission and reception processing with the wireless terminals via the wireless antenna devices; and an optical communication network that performs data transmission between each of the wireless antenna devices and the signal processing device, wherein the optical communication network comprises slave station communication devices connected to each of the wireless antenna devices, a master station communication device connected 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 having wireless control management means, wired control management means and wired linkage control means, the wireless control management means managing and controlling each of the wireless antenna devices, cells corresponding to each of the wireless antenna devices, and wireless terminals connected to each of the wireless antenna devices, and the wired control management means the optical communication network The system controls the communication speed between each of the aforementioned wireless antenna devices and the signal processing device, the wired / wireless cooperation control means controls the communication of the wireless terminals of each cell via the wireless control management means and the wired control management means, and when a wireless antenna device subject to a communication speed change occurs, the wired / wireless cooperation control means performs a first connection change process to change the wireless terminals connected to the wireless antenna device subject to a communication speed change to the wireless antenna device of a neighboring cell located near the cell to which the wireless antenna device subject to a communication speed change belongs, after the first connection change process, performs a communication speed change control process to change the communication speed of the wireless antenna device subject to a communication speed change, and after the communication speed change control process, performs a second connection change process to change some or all of the wireless terminals connected to the wireless antenna device of the neighboring cell to the wireless antenna device subject to a communication speed change. [Effects of the Invention]

[0011] According to the present invention, it is possible to operate a wireless access network of a mobile communication network with low power consumption while suppressing a deterioration in the quality of communication services. [Brief explanation of the drawing]

[0012] [Figure 1] This is a block diagram showing the overall configuration of the communication system according to the first embodiment. [Figure 2] This is a block diagram showing an example of the internal configuration of a wireless access network according to the first embodiment. [Figure 3] This is a diagram (part 1) illustrating an example of the state transitions of each cell (first scenario) to explain the operation of the communication system according to the first embodiment. [Figure 4] This is Figure (2) illustrating an example of the state transitions of each cell (first scenario) to explain the operation of the communication system according to the first embodiment. [Figure 5] This is Figure (3) illustrating an example of the state transitions of each cell (first scenario) to explain the operation of the communication system according to the first embodiment. [Figure 6] This is Figure (4) illustrating an example of the state transitions of each cell (first scenario) to explain the operation of the communication system according to the first embodiment. [Figure 7] This is Figure (5) illustrating an example of the state transitions of each cell (first scenario) to explain the operation of the communication system according to the first embodiment. [Figure 8] This is Figure (6) illustrating an example of the state transitions of each cell (first scenario) to explain the operation of the communication system according to the first embodiment. [Figure 9] Figure (7) shows an example of the state transitions of each cell (first scenario) to explain the operation of the communication system according to the first embodiment. [Figure 10] Figure (8) shows an example of the state transitions of each cell (first scenario) to explain the operation of the communication system according to the first embodiment. [Figure 11] This is a diagram (part 1) illustrating an example of the state transitions of each cell (second scenario) to explain the problems related to the communication system of the first embodiment. [Figure 12]FIG. 12 (part 2) is a diagram showing an example of state transition of each cell (second scenario) for explaining a problem related to the communication system according to the first embodiment. [Figure 13] FIG. 2 is a block diagram showing an overall configuration of a communication system according to a second embodiment. [Figure 14] FIG. 3 (part 1) is a diagram showing an example of state transition of each cell (third scenario) for explaining an operation of the communication system according to the second embodiment. [Figure 15] FIG. 4 (part 2) is a diagram showing an example of state transition of each cell (third scenario) for explaining an operation of the communication system according to the second embodiment. [Figure 16] FIG. 5 (part 3) is a diagram showing an example of state transition of each cell (third scenario) for explaining an operation of the communication system according to the second embodiment. [Figure 17] FIG. 6 is a block diagram showing an example of an internal configuration of a radio access network according to a modification of the first embodiment. MODE FOR CARRYING OUT THE INVENTION

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

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

[0015] Communication system 1 is a mobile communication network system (for example, a network system of a telecommunications carrier) for connecting wireless terminals TE, and has multiple 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 Figure 1, the mobile core network 71 may also be connected to external networks such as the internet 73 or other telecommunications carrier networks 74.

[0016] Next, the internal configuration of each wireless access network 100 will be explained using Figure 2.

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

[0018] For the sake of simplicity, this explanation assumes that the internal configuration of each wireless access network 100 is the same, but it is also possible to have different configurations in some aspects (for example, the number of each device).

[0019] Each wireless access network 100 includes N antenna devices, RU (Radio Unit) 50 (50-1 to 50-N), which transmit and receive wireless signals and convert them into electrical signals; a DU / CU (Distributed Unit / Centralized Unit) 20, which is a signal processing device that modulates and demodulates the electrical signals transmitted and received by each RU 50; and an optical communication network 101, which is an optical transmission path connecting each RU 50 and the DU / CU 20 via a PON (Passive Optical Network). The RU 50 transmits and receives wireless signals with wireless terminals TE that are subscribed to the mobile communication network configured in the communication system 1. The DU / CU 20 also communicates with wireless terminals TE via the RU 50.

[0020] The optical communication network 101 has an OLT (Optical Line Terminal) 30 as a master station communication device and N ONUs (Optical Network Units) 40 (40-1 to 40-N) as slave station communication devices. The OLT 30 is connected to an optical fiber 60, which is split into N branches (same number of branches as the ONU 40) by a splitter 70, and each branch is connected to an ONU 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 Figure 1, and a multi-stage (hierarchical) branching configuration using multiple splitters 70 is also possible.

[0021] In this embodiment, the OLT 30 and the multiple ONUs 40 share a single optical transmission path (optical fiber 60) using WDM (Wavelength Division Multiplexing) and TDMA (Time Division Multiple Access) (TWDM). In other words, each OLT 30 supports WDM and can communicate with each ONU 40 at any of several wavelengths. Under each OLT 30, the multiple ONUs 40 can share a transmission path formed by a single wavelength using TDMA.

[0022] Furthermore, in this embodiment, each OLT30 and ONU40 is assumed to support multiple communication speed operating modes. That is, each OLT30 is assumed to be able to communicate with each ONU40 at different communication speeds for each wavelength. In this example embodiment, each OLT30 and ONU40 is assumed to support a mode that operates at either 25Gbps or 10GB, but the number and combinations of supported modes are not limited to this. In addition, the power consumption of the OLT30 and ONU40 tends to increase as the communication speed increases (in this example embodiment, the power consumption is assumed to be about twice as high at 25Gbps compared to 10Gbps).

[0023] Next, an example of the internal configuration of OLT30 and ONU40 will be explained using Figure 2.

[0024] As described above, the OLT30 and ONU40 (optical communication network 101) in this embodiment need to have a configuration such as that shown in Figure 2 in order to support WDM / TDMA.

[0025] As shown in Figure 2, the OLT 30 includes an electrical switch 31, M (where M is any number of 1 or more) OSUs 32-1 to 32-M, L (where L is any number of 1 or more) OSUs 33-1 to 33-L, an optical spatial switch 34, and a wavelength multiplexing unit 35.

[0026] OSU32 and 33 are elements that function as "Optical Subscriber Units" and can establish PtMP (Point To Multipoint) connections with multiple ONU40s via optical fiber 60. OSU32 and 33 are connected to the optical fiber 60 via an optical space switch 34 and a wavelength multiplexing unit 35. Here, OSU32 and 33 have different communication speeds with the ONU40. Specifically, OSU32 is described as supporting 10 Gbps, and OSU33 is described as supporting 25 Gbps. Note that the types (communication speeds) and number (combinations) of OSUs provided by the OLT30 are not limited. OSU32-1 to 32-M and OSU33-1 to 33-L can communicate with their respective ONU40s (ONU40s controlled to communicate at the same wavelength) at different wavelengths (which may be fixed wavelengths or dynamically changeable wavelengths).

[0027] The electrical switch 31 is connected to the upper side (DU / CU20) to switch electrical signals, and is also connected to the respective OSUs 32 and 33 on the lower side.

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

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

[0030] Each ONU 40 has an optical multiplexer / demultiplexer 41, optical transceivers 42 and 43, and an electrical switch 44. The optical transceivers 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 photoelectric converters connected to the lower-side electrical switch 31. The optical multiplexer / demultiplexer 41 splits the optical signal received from the PON side (optical fiber 60 side) to the optical transceivers 42 and 43, and also merges the optical signals received from the optical transceivers 42 and 43 and sends them back to the PON side (optical fiber 60 side). The electrical switch 31 connects to the lower-side RU 50 and switches electrical signals.

[0031] Furthermore, the optical transceivers 42 and 43 communicate with the OLT 30 at different speeds. In this description, the optical transceiver 42 is assumed to support 10 Gbps, and the optical transceiver 43 is assumed to support 25 Gbps. Note that the type (communication speed) and number (combination) of optical transceivers equipped in the ONU 40 are not limited. In each ONU 40, only one of the optical transceivers 42 or 43 is operated in response to control from the OLT 30, and it connects to one of the OSUs (OSUs assigned by the OLT 30) with light of a wavelength corresponding to the control from the OLT 30. In other words, in this embodiment, the ONU 40 supports multi-rate connectivity to the PON side at one of multiple communication speeds by having and switching between multiple optical transceivers with different communication speeds.

[0032] In this embodiment of communication system 1, WDM / TDMA (TWDM) PON is realized by configuring the OLT30 and ONU40 as described above.

[0033] Next, an example of the internal configuration of OLT30 and ONU40 will be explained using Figure 2.

[0034] As described above, the OLT30 and ONU40 (optical communication network 101) in this embodiment need to have a configuration such as that shown in Figure 2 in order to support WDM / TDMA.

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

[0036] OSU32 and 33 are also connected to the upper side (electrical switch 31). Furthermore, OSU32 and 33 have different communication speeds when connected to the PON (optical fiber 60). In this explanation, OSU32 supports 10Gbps and OSU33 supports 25Gbps. Also, as shown in Figure 2, the OLT30 in this embodiment has M (M is any number of 1 or more) OSU32-1 to 32-M and L (L is any number of 1 or more) OSU33-1 to 33-L. Note that the types (communication speeds) and number (combinations) of OSUs that the OLT30 has are not limited.

[0037] OSU32-1~32-M and OSU33-1~33-L can communicate with their respective ONU40s (ONU40s assigned to communicate on the same wavelength) using different wavelengths (which may be fixed wavelengths or dynamically changeable wavelengths).

[0038] Each ONU 40 has an optical multiplexer / demultiplexer 41, optical transceivers 42 and 43, and an electrical switch 44. The optical transceivers 42 and 43 each transmit and receive optical signals to and from the PON side (optical fiber 60 side) at different speeds and also function as transceivers (photoelectric converters) that connect to the lower-side electrical switch 31. The optical multiplexer / demultiplexer 41 separates the optical signal received from the PON side (optical fiber 60 side) to the optical transceivers 42 and 43, and combines the optical signals received from the optical transceivers 42 and 43 and sends them to the PON side (optical fiber 60 side). The electrical switch 31 connects to the lower-side RU 50 and switches electrical signals.

[0039] Furthermore, the optical transceivers 42 and 43 each have different communication speeds for connecting to the PON (optical fiber 60). In this description, optical transceiver 42 is assumed to support 10 Gbps, and optical transceiver 43 is assumed to support 25 Gbps. Note that the type (communication speed) and number (combination) of optical transceivers equipped in the ONU 40 are not limited. In each ONU 40, in response to control from the OLT 30, only one of the optical transceivers 42 or 43 is activated to connect to the PON side (optical fiber 60) and connect to one of the OSUs. In other words, in this embodiment, the ONU 40 supports multi-rate connections to the PON side at any of multiple communication speeds by having multiple optical transceivers with different communication speeds and switching between them.

[0040] ONU40-1 to 40-N are connected to RU50-1 to 50-N, respectively. The mobile core network 71 (for example, the core network of a telecommunications carrier) is connected to the upper layer of the DU / CU20. The DU / CU20 is responsible for DU functions, which perform physical layer processing of signals (e.g., modulation and demodulation) and MAC layer communication control, and CU functions, which perform packet communication control between the RU50 and the mobile core network 71 and manage the wireless resources of each RU50.

[0041] In communication system 1, each RU50 is responsible for wireless communication within a single area (hereinafter referred to as a "cell"), and connects to the wireless terminal TE within that cell according to the control of the DU / CU20.

[0042] As described above, each RU50 can communicate with the DU / CU20 via the optical communication network 101, and further communicate with the mobile core network 71 via the DU / CU20.

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

[0044] The communication control device 10 is configured to control the PON section (wired section) by connecting to the optical communication network 101 (OLT30) of each wireless access network 100 via the wired control network 72. The specific configuration of the wired control network 72 is not limited, but 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 orchestration functions that control and operate the entire communication system 1, and as part of its orchestration functions, it has an presence / absence linkage function unit 11. The presence / absence linkage function unit 11 has a linkage control processing unit 12 as a wired / wireless linkage control means, a wireless control management function unit 13 as a wireless control management means, and a wired control management function unit 14 as a wired control management means.

[0047] The wireless control management function unit 13 is responsible for controlling wireless communication to the mobile core network 71, DU / CU20, RU50, and wireless terminal TE (hereinafter referred to as "wireless control").

[0048] The wired control management unit 14 is responsible for controlling the communication of the optical communication network 101 (OLT30, ONU40) (hereinafter referred to as "wired control"). As described above, the wired control management unit 14 controls the optical communication network 101 (OLT30, ONU40) via the wired control network 72.

[0049] The linked control processing unit 12 performs control processing that links the wired section (the section between OLT30 and ONU40) and the wireless section (the section between DU / CU20 and RU50) via the wireless control management function unit 13 and the wired control management function unit 14.

[0050] The wireless control management function unit 13 can collect and store information relating to the area corresponding to each RU50 (hereinafter referred to as "cell"). The wireless control management function unit 13 is assumed to manage each cell (each RU50) by assigning an identification number (hereinafter referred to as "cell number"). The wireless control management function unit 13 is also assumed to store information regarding the positional relationship (map information) of each cell. The method by which the wireless control management function unit 13 stores various information relating to each cell (each RU50) (hereinafter referred to as "cell information") is not limited. For example, the wireless control management function unit 13 may collect cell information from a higher-level device that controls each RU50 (for example, a DU / CU20).

[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 explained focusing on the process by which the communication control device 10 controls the wireless access network 100-1.

[0052] Figures 3 to 10 are diagrams illustrating examples of state transitions for each cell (hereinafter referred to as the "first scenario") to explain the operation of the communication system 1 of the first embodiment.

[0053] Figures 3 to 10 show the states of steps S101 to S106, which constitute the first scenario of the state transition described above.

[0054] Figures 3 to 10 illustrate the nine cells C-1 to C-9 controlled by the communication control device 10 in map format. Cells C-1 to C-9 are assumed to be formed by RU50-1 to RU50-9, respectively. ONU40-1 to RU50-9 are connected to ONU40-1 to RU50-9. Here, cells C-1 to C-9 are arranged in a 3x3 matrix. Here, cells C-1 to C-9 (RU50-1 to RU50-9) are assigned cell numbers from 1 to 9, respectively. In Figures 3 to 10, the thickness of the wires (corresponding to the branched optical fibers 60) from the splitter 70 to each cell (each ONU40) represents the allocated bandwidth (bandwidth allocated by OLT30).

[0055] In the first scenario, we will describe an example of processing that focuses particularly on four cells, C-1 to C-4, out of cells C-1 to C-9. As shown in Figures 3 to 10, each of cells C-1 to C-4 has a wireless terminal TE. In reality, each cell in a mobile communication network of a communication carrier may have tens to thousands of wireless terminals, but in Figures 3 to 10, for the sake of simplicity, only 1 to 3 wireless terminals TE are shown in each cell. Specifically, in Figures 3 to 10, wireless terminal TE-1 is shown in cell C-1, wireless terminal TE-2 in cell C-2, wireless terminals TE-3 and TE-4 in cell C-3, and wireless terminals TE-5, TE-6, and TE-7 in cell C-4.

[0056] Next, we will explain the assumptions of the first example scenario shown in Figures 3 to 10.

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

[0058] For example, let's assume that in each of cells C-1 to C-4, the required bandwidth in both the uplink and downlink directions (hereinafter simply referred to as "traffic") is slightly less than 10 Gbps (for example, around 9 Gbps), and that operating the communication speed between OLT30 and each ONU40 (ONU40-1 to 40-4) at 10 Gbps results in a relatively efficient amount of traffic for bandwidth utilization. In this case, on the OLT30 side, four corresponding OSU32 units are operating at 10 Gb / s each at different wavelengths. There are also other OSUs connected to ONU40-5 to 40-9. Then, let's assume that time progresses and the amount of traffic in cells C-1 to C-4 decreases (for example, during late night or early morning hours when traffic volume decreases). In this case, the total traffic of all cells C-1 to C-4 is 24 Gbps (for example, assuming that the traffic of each cell is 6 Gbps), and it is assumed that all can be accommodated by increasing the transmit power (transmit power during wireless communication) of RU50-4 located in cell C-4. In this case, by changing the communication speed between ONU40-4 in cell C-4 and OLT30 from 10 Gbps to 25 Gbps mode, sufficient bandwidth (more than the required 24 Gbps) can be secured between RU50-4 and DU / CU20. With the above accommodation changes, the equipment in cells C-1 to C-3 that do not accommodate wireless terminals TE (RU50-1 to 50-3, ONU40-1 to 40-3, etc.) and the three OSU32 units in OLT30 connected to them can be stopped (powered off) or operated in a low-power state (power-saving mode), thus reducing the power consumption of the entire system. However, when changing the communication speed as described above, it is necessary to perform switching processes (for example, processes involving restarting or resynchronizing communication) in cell C-4's RU50-4 and ONU40-4. For example, when changing the communication speed between cell C-4's ONU40-4 and the OSU connected to ONU40 in OLT30 from 10Gbps to 25Gbps (changing the connection destination from OSU32 to OSU33), if left as is, communication will be temporarily stopped (communication between ONU40-4 and one OSU in OLT30 that is 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 linkage function unit 11 (linkage control processing unit 12) performs control to avoid communication interruptions caused by the above-mentioned change in communication speed (hereinafter referred to as "communication interruption avoidance control"). The first scenario shown in Figures 3 to 10 shows an example of communication interruption avoidance control when the above-mentioned change in communication speed occurs.

[0059] In the following, when the cooperative control processing unit 12 decides to consolidate and accommodate wireless terminals TE from multiple cells into a single cell, the entire set of cells targeted for consolidation (cells C-1 to C-4 in the first scenario) will be referred to as the "consolidation target cell," the cell to which the consolidation target cell will be consolidated (cell C-4 in the first scenario) will be referred to as the "consolidation destination cell," and the cells before the wireless terminals TE are migrated to the consolidation destination cell (the source cells, C-1 to C-3 in the first scenario) will be referred to as the "migration source cells." Furthermore, in the following, the cell targeted for communication speed change (cell C-4 in the first scenario) will be referred to as the "communication speed change target cell," and the cells to which the wireless terminals TE are evacuated from the communication speed change target cell (cells C-1 to C-3 in the first scenario) will also be referred to as the "evacuation destination cells."

[0060] Next, we will explain each step of the first scenario shown in Figures 3 to 10.

[0061] First, in the state of step S101 (Figures 3 and 4), all wireless terminals TE are assumed to be communicating wirelessly with RU50 located within the cell in which their respective devices are located. In the state of step S101, all ONU40-1 to 20-4 are assumed to be connected to OLT30 in a communication speed mode of 10Gbps. Then, in the state of step S101, it is assumed that the traffic demand in cells C-1 to C-4 is low, and the presence / absence linkage function unit 11 has decided to change the communication speed of cell C-4 (communication speed between ONU40-4 and OLT30) to 25Gbps (accommodation change) and connect all wireless terminals TE in cells C-1 to C-4 to RU50-4 in cell C-4. In the state of step S101, as described above, the traffic in each of cells C-1 to C-4 is assumed to be 6Gbps. In other words, in the state of step S101, the total traffic in cells C-1 to C-4 is assumed to be 24Gbps.

[0062] Even in the state of step S101, each wireless terminal TE actually receives radio waves from the RU50 (base station) of a neighboring cell (hereinafter referred to as "neighboring cell") of the cell where the device is located, at a slightly weak noise level. Therefore, Figure 4 illustrates the state in which wireless terminals TE5 to TE7 in cell C-4 are slightly picking up radio waves from the neighboring cell's RU50 (connected to the neighboring cell's RU50 by a dotted line). Wireless terminals TE in cells C-1 to C-4 should also be slightly picking up radio waves from the neighboring cell's RU50, but this is omitted from the illustration for simplicity. In this state as shown in Figure 4, the cooperation control processing unit 12 issues an instruction to strengthen the radio waves (transmission power) of RU50-1 to 50-3 in cells C-1 to C-3 (evacuation destination cells), and further weaken the radio waves (transmission power) of RU50-4 in cell C-4 (the cell subject to communication speed change). As a result, the wireless terminal TE in cell C-4 mistakenly believes it is located in cells C-1 to C-3 rather than in cell C-4 (at least it recognizes that the radio waves coming from RU50-1 to RU50-3 in cells C-1 to C-3 are of better quality), and switches its connection destination to one of RU50-1 to RU50-3. Consequently, the state of cells C-1 to C-4 transitions to the state shown in step S102 (Figure 5). At this time, the amount by which the transmission power (intensity of transmission power) is adjusted for the RU50 (RU50-1 to RU50-3) of the evacuated cell, and the amount by which the transmission power (intensity of transmission power) is adjusted for the RU50 (RU50-4) of the cell subject to the communication speed change, can be set to any value (for example, a value derived in advance through design or experimentation).

[0063] In step S102, as shown in Figure 5, the connection destination of wireless terminal TE-5 switches to RU50-3 in cell C-3, the connection destination of wireless terminal TE-6 switches to RU50-1 in cell C-1, and the connection destination of wireless terminal TE-7 switches to RU50-2 in cell C-2. In the state of step S102, it is assumed that the 6Gbps traffic of wireless terminal TE in cell C-4 is accommodated in RU50 in cells C-1 to C-3 at a rate of 2Gbps each. In other words, in the state of step S102, it is assumed that the traffic in cells C-1 to C-3 is 8Gbps each (24Gbps total).

[0064] Although not shown in Figure 5, weak radio waves from RU50-4 in cell C-4 are also reaching the wireless terminals TE in cells C-1 to C-3. However, in this state, RU50-4 in cell C-4 is not in use (there are no connected wireless terminals TE), so even if communication between ONU40-4 and OLT30 in cell C-4 is interrupted, there will be no problem with the communication service of the wireless terminals TE. Therefore, at this time, the cooperation control processing unit 12 performs a process to switch the communication speed between ONU40-4 and OLT30 in cell C-4 from 10Gbps to 25Gbps. In Figure 5, the line between ONU40-4 and OLT30 is thicker, indicating that communication is taking place at 25Gbps.

[0065] Subsequently, the communication speed between ONU40-4 and OLT30 in cell C-4 is synchronized at 25Gbps, and communication between RU50-4 and DU / CU20 is restored. Furthermore, the cooperation control processing unit 12 then instructs RU50-4 in cell C-4 to slightly increase the radio wave (transmission power). As a result, the state of cells C-1 to C-4 transitions to the state shown in step S103 (Figure 6). At this time, the amount by which the transmission power (intensity of transmission power) is adjusted for RU50 (RU50-4) of the cell subject to the communication speed change can be set to any value (for example, a value derived in advance through design or experimentation).

[0066] In the state of step S103, the wireless terminal TE in cell C-4 is also receiving the radio waves from RU50-4 in C-4 (in Figure 6, the wireless terminals TE-5 to TE-7 in cell C-4 are connected to RU50-4 by dotted lines). Now, let's assume that the cooperation control processing unit 12 has instructed the system to return the strength of the radio waves from RU50-1 to RU50-4 to the same state as in step S101 (Figure 4). As a result, the state of cells C-1 to C-4 transitions to the state of step S104 (Figures 7 and 8).

[0067] In step S104 (Figure 7), the connection status of each wireless terminal TE in cells C-1 to C-4 returns to the same state as in step S101 (however, at step S104, the communication speed of ONU40-4 in cell C-4 has increased to 25Gbps).

[0068] By the way, in the state of step S104, the wireless terminals TE in cells C-1 to C-3 are also picking up a small amount of radio waves from RU50-4 in cell C-4. Therefore, Figure 8 shows the state in which wireless terminals TE1 to TE4 in cells C-1 to C-3 are picking up a small amount of radio waves from the neighboring cell's RU50 (connected to RU50-4 in cell C-4 by a dotted line). Now, let's assume that from the state of step S104, the cooperation control processing unit 12 gives an instruction to increase the radio waves (transmission power) of RU50-4 in cell C-4, and further weaken the radio waves of RU50-1 to RU50-3 in cells C-1 to C-3. In that case, the wireless terminals TE in cells C-1 to C-3 will mistakenly believe that they are located in cell C-4 rather than in cells C-1 to C-3 (at least they will recognize that the radio waves coming from RU50-4 in cell C-4 are better), and will switch their connection destination to RU50-4. As a result, the state of cells C-1 to C-4 transitions to the state shown in step S105 (Figure 9). At this time, the amount by which the transmission power (intensity of transmission power) is adjusted for the RU50 of the backup cell (RU50-1 to 50-3) and the amount by which the transmission power (intensity of transmission power) is adjusted for the RU50 of the cell subject to the communication speed change (RU50-4) can be set to any value (for example, a value derived in advance through design or experimentation).

[0069] In the state of step S105 (Figure 9), RU50-1~50-3 and ONU40-1~40-3 in cells C-1~C-3 are not in use (there are no connected wireless terminals TE), so even if they are stopped (powered off) or operate in a power-saving state (power-saving mode), there will be no problem with the communication service of the wireless terminals TE. Therefore, from the state of step S105, the cooperation control processing unit 12 controls RU50-1~50-3 and ONU40-1~40-3 to switch to a stopped (powered off) or power-saving state (power-saving mode). In addition, the three OSU32 units that were communicating with these ONUs at 10Gb / s within the OLT30 also switch to stopped or power-saving mode. As a result, the state of cells C-1~C-4 transitions to the state of step S106 (Figure 10).

[0070] In Figure 10, the fact that ONU40-1~40-3 and RU50-1~50-3 are not in use (they have transitioned to a stopped or low-power operation state) is represented by erasing the lines to the OLT30 side (splitter 70) (however, the physical connection remains, and in fact, ONU40-5~40-9 in cells C5~C9 are still connected to the OLT30 via splitter 70).

[0071] In the above steps S101 to S106, the operation in which the wireless terminal TE switches the connected RU50 is a simplified representation of a technique called "hard handover". The specific process for handing over the wireless terminal TE between RU50s is not limited, but for example, the technique described in Reference 1 below may be used. [Reference 1] Japanese Patent Publication No. 2009-130740

[0072] Furthermore, even when handing over a wireless terminal TE between RU50s, there may be a brief interruption in connection time. Therefore, it is desirable to avoid this by using a technology that allows the wireless terminal TE to communicate with multiple RU50s simultaneously while switching. Specifically, for example, the above switching can be achieved by using a technology 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 on 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, the control processing (communication interruption avoidance control) of the cooperation control processing unit 12 makes it possible to suppress data loss between the wireless terminal TE and the mobile core network 71 even if communication between the ONU 40 and the OLT 30 is temporarily interrupted when changing the communication speed between a specific RU 50 and the upper side. Specifically, the cooperation control processing unit 12 temporarily moves the wireless terminal TE connected to the RU 50 whose communication speed is to be changed to a neighboring cell's RU 50, 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 then performs a process to switch back the connection of the moved wireless 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 suppress communication interruptions when changing the connection of wireless terminal TE between RU50s.

[0076] (B) Second Embodiment As a prerequisite for a detailed explanation of the second embodiment, the problems in the communication system 1 of the first embodiment will be explained using Figures 11 and 12.

[0077] Figures 11 and 12 are diagrams illustrating examples of state transitions for each cell (hereinafter referred to as the "second scenario") to explain the issues related to the communication system 1 of the first embodiment.

[0078] Figures 11 and 12 show the states of steps S201 to S202, which constitute the second scenario, respectively.

[0079] In the second scenario shown in Figures 11 and 12, the nine cells C-1 to C-9 controlled by the communication control device 10 are illustrated in map format. In Figures 11 and 12, one or more wireless terminal groups TEG, each composed of numerous wireless terminals TE, are shown within cells C-1 to C-4. In Figures 11 and 12, wireless terminal group TEG-1 is located in cell C-1, wireless terminal group TEG-2 in cell C-2, wireless terminal group TEG-3 in cell C-3, and wireless terminal groups TEG-4 to TEG-6 in cell C-4. In Figures 11 and 12, the total value of the traffic (requested bandwidth) requested by the included wireless terminals TE is noted for each wireless terminal group TEG. Therefore, as shown in Figure 11, the traffic of wireless terminal groups TEG-1 to TEG-6 is 10 Gbps, 6 Gbps, 4 Gbps, 3 Gbps, 3 Gbps, and 2 Gbps, respectively. Cell C-4 has three wireless terminal groups, TEG-4 to TEG-6, so the total traffic for cell C-4 is 8 Gbps.

[0080] As shown in Figure 11, within cell C-4, wireless terminal group TEG-4 consists of wireless terminals TE located closer to cell C-3, while wireless terminal groups TEG-5 and TEG-6 consist of wireless terminals TE located closer to cell C-2. Furthermore, it is assumed that wireless terminal group TEG-6 is closer to cell C-2's RU50-2 than wireless terminal group TEG-5.

[0081] First, let's describe the state at step S201 (Figure 11) in the second scenario.

[0082] In step S201, each wireless terminal TE of wireless terminal group TEG-1 to TEG-6 is connected to the RU50 of the cell where the device is located. Also, at step S201, the communication speed between ONU40-1 to 40-4 and OLT30 is assumed to be 10 Gbps. In the state of step S201, the total traffic of cells C-2 to C-4 is 18 Gbps. At this point, the cooperation control processing unit 12 decides to accommodate all wireless terminals TE of wireless terminal group TEG-2 to TEG-6 of cells C-2 to C-4 into RU50-4 of cell C-4. However, if the traffic of cell C-1 (10 Gbps) is also accommodated into RU50-4 of cell C-4, the communication speed limit (25 Gbps even if the communication speed is changed) will be exceeded, so the cooperation control processing unit 12 decides to leave the wireless terminal group TEG-1 of cell C-1 as is. At step S201, the communication speed between ONU40-4 and OLT30 in cell C-4 is 10Gbps, so it needs to be changed to 25Gbps. Therefore, the cooperation control processing unit 12 performs a process to move the wireless terminals TE in C-4 to RU50-2 and 50-3 in cells C-2 and C-3 to prevent communication interruption during the communication speed change. Specifically, the cooperation control processing unit 12 strengthens the radio waves of RU50-2 and 50-3 in cells C-2 and C-3, and weakens the radio wave of RU50-4 in cell C-4, thereby distributing and accommodating the wireless terminals TE of the wireless terminal group TEG-4 to TEG-6 to RU50-2 and 50-3 in cells C-2 and C-3. As a result, the state of cells C-2 to C-4 transitions to the state shown in step S202 (Figure 12).

[0083] As described above, within cell C-4, wireless terminal group TEG-4 consists of wireless terminals TE located closer to cell C-3, and therefore, in the state of step S202, it is connected to RU-3 of cell C-3. Also, wireless terminal groups TEG-5 and TEG-6 consist of wireless terminals TE located closer to cell C-2, and therefore, in the state of step S202, they are connected to RU50-2 of cell C-2. In other words, at the time of step S202, RU50-2 of cell C-2 is accommodating wireless terminals TE with a total traffic of 11 Gbps, exceeding the line capacity of 10 Gbps, and there is a risk that the communication quality of wireless terminals TE under RU50-2 will deteriorate.

[0084] As described above, in the communication system 1 of the first embodiment, if the distribution of wireless terminals TE is uneven as in the second scenario above, there is a problem that the communication lines of some cells will overflow when capacity changes are made.

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

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

[0087] The following describes the differences between the second embodiment and 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 by a communication control device 10A. Furthermore, the communication control device 10A differs from the first embodiment in that the presence / absence linkage function unit 11 is replaced by a presence / absence linkage function unit 11A. In addition, the presence / absence linkage function unit 11A differs from the first embodiment in that the linkage control processing unit 12 is replaced by a linkage control processing unit 12A.

[0089] The collaborative control processing unit 12A has a retraction radio terminal / area selection function unit 121 as an element that performs control processing to solve the problem of some cells' communication lines overflowing during capacity changes, as in the second scenario described above. The retraction radio terminal / area selection function unit 121 holds information necessary for control processing from the radio control management function unit 13, such as the current traffic amount in each cell, the position of each radio terminal TE, radio wave reception strength, and traffic amount.

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

[0091] Figures 14 to 16 are diagrams illustrating examples of state transitions for each cell (hereinafter referred to as the "third scenario") to explain the operation of the communication system 1A in the second embodiment.

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

[0093] First, in the state of step S301 (Figure 11), the cooperation control processing unit 12A decides to accommodate the wireless terminals TE of the wireless terminal group TEG-2 to TEG-6 of cells C-2 to C-4 into RU50-4 of cell C-4. Therefore, in the third scenario, cell C-4 becomes the cell subject to communication speed change (aggregation target cell), and cells C-2 and C-3 become the evacuation target cells (migration source cells).

[0094] At this point, the remote wireless terminal / area selection function unit 121 of the interoperation control processing unit 12A determines that cells C-2 and C-3 (RU50-2, RU50-3) are the remote destination cells for the wireless terminals TE of the wireless terminal group TEG-4 to TEG-6 in cell C-4. The interoperation control processing unit 12A (remote wireless terminal / area selection function unit 121) then acquires the current traffic information for the remote destination cells C-2 and C-3 (acquiring information that the traffic of cell C-2 is 6 Gbps and the traffic of cell C-3 is 4 Gbps). Next, the interoperation control processing unit 12A slightly increases the radio wave (transmission strength) of RU50-3 in cell C-3, which has less traffic than the other remote destination cells. As a result, the state of cells C-2 to C-4 transitions to the state shown in step S302 (Figure 14).

[0095] As described above, within 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 wireless terminal group TEG-4 are connected to RU50-3 of cell C-3. Consequently, in the state of step S302, the total traffic of cell C-3 (RU50-3) is 7 Gbps, which is the opposite of the traffic of the other backup destination, cell C-2 (6 Gbps). Thus, cell C-2 is the backup destination with less traffic. Therefore, the cooperation control processing unit 12A slightly increases the radio wave (transmission strength) of RU50-2 of cell C-2, which currently has less traffic among the backup destinations, from the state of step S302. As a result, the state of cells C-2 to C-4 transitions to the state of step S303 (Figure 15).

[0096] As described above, since the distance to RU50-2 of cell C-2 is shorter for wireless terminal group TEG-6 than for wireless terminal group TEG-5, at step S303, it is assumed that the wireless terminal TE of wireless terminal group TEG-6 is connected to RU50-2 of cell C-2. In this case, at the state of step S303, the total traffic of cell C-2 (RU50-2) becomes 8 Gbps, which is greater than the total traffic of cell C-3 (7 Gbps), causing a reversal. Therefore, the cooperation control processing unit 12A slightly increases the radio wave (transmission strength) of RU50-3 of cell C-3, which currently has less traffic among the backup cells, from the state of step S303. As a result, the state of cells C-2 to C-4 transitions to the state of step S304 (Figure 16).

[0097] At step S304, the wireless terminal TE of wireless terminal group TEG-5 will be connected to RU50-3 of cell C-3. As a result, all wireless terminals TE of wireless terminal groups TEG-4 to TEG-6, which were originally connected to cell C-4 (RU50-4), will have completed their relocation to their respective destinations (cell C-2 or cell C-3). Subsequently, the cooperation control processing unit 12A, similar to the first embodiment, will change the communication speed between the ONU 40-4 of cell C-4 and the OLT 30 to 25 Gbps, and then perform the process of switching all wireless terminals TE of wireless terminal groups TEG-1 to TEG-6 to RU50-4 of cell C-4 (illustrations are omitted).

[0098] As described above, in the second embodiment, the process of selecting a cell with low traffic (hereinafter referred to as a "low-traffic cell") from the backup cell (cells C-2 and C-3 in the third scenario) and increasing the transmission power is repeated, thereby prompting a change in the connection of the wireless terminal TE from the cell subject to the communication speed change (cell C-4 in the third scenario) to the backup cell. At this time, the amount by which the transmission power is adjusted at one time for the low-traffic cell can be set to an arbitrary value (for example, a value derived in advance through design or experimentation).

[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] In the second embodiment, the communication system 1A (cooperation control processing unit 12A) repeatedly selects a cell with low traffic among the evacuated cells and gradually increases the power of the RU50. This allows the communication system 1A in the second embodiment to balance the traffic between evacuated cells and suppress traffic overflow in the evacuated cells.

[0101] (C) Other embodiments The present invention is not limited to the embodiments described above, and modified embodiments such as those exemplified below can also be cited.

[0102] (C-1) In the first and second embodiments, the transmission power strength of RU50 was used as a parameter to prompt the wireless terminal TE to change its connection destination from the cell subject to the communication speed change to the evacuation cell, but other parameters may be used. For example, a parameter representing the priority (weight) that the wireless terminal TE has when selecting the RU50 to connect to (hereinafter referred to as "connection destination priority") may be used as a parameter to prompt the wireless terminal TE to change its connection destination from the cell subject to the communication speed change to the evacuation cell. For example, the cooperation control processing unit 12 may inform each wireless terminal TE of the connection priority value for each RU50 via the DU / CU20, so that the mobile terminal TE preferentially connects to the RU50 with the higher connection destination priority. As a result, the cooperation control processing unit 12 can prompt the wireless terminal TE to change its connection destination to the evacuation cell by setting the connection destination priority of the evacuation cell higher than that of the cell subject to the speed change.

[0103] Furthermore, in the first and second embodiments, instead of using parameters for each RU50 to prompt a wireless terminal TE to change its connection destination from the cell subject to the communication speed change to the backup cell, control (direct control) may be performed to change the connection destination of each wireless terminal TE to the backup cell.

[0104] (C-2) In the second embodiment, the cooperation control processing unit 12A may suppress the overflow of the evacuation cells by processing other than that described above. For example, if there are multiple evacuation cells, the cooperation control processing unit 12A may strengthen the radio waves (RU50 radio waves) of cells with less traffic until the traffic of each evacuation cell becomes equal, and while maintaining the state in which the traffic of all evacuation cells becomes equal, it may gradually increase the number of wireless terminals TE (accommodated traffic) accommodated by gradually strengthening the radio waves of each evacuation cell, so that all wireless terminals TE of the cell subject to communication speed change are accommodated in the evacuation cells. Alternatively, for example, the cooperation control processing unit 12A may set a value calculated in advance from the location information and radio wave strength information of each wireless terminal TE in the cell subject to communication speed change to determine what strength the radio waves of each RU50 of each evacuation destination cell should be to allow distributed accommodation without overflow. By the way, if we simply consider only the distribution of traffic between evacuation cells, there is a possibility that the traffic of the evacuation cell may decrease as a result of the communication quality of a particular wireless terminal TE (for example, the radio signal status with RU50) deteriorating during the transition to the evacuation cell. Therefore, for example, when the interoperation control processing unit 12A migrates the wireless terminal TE of a cell subject to a communication speed change to an evacuation cell, it may distribute and accommodate the wireless terminal TE in each RU50 so that even the wireless terminal TE with the worst communication quality is in the best possible state. Alternatively, for example, when the interoperation control processing unit 12A migrates the wireless terminal TE of a cell subject to a communication speed change to an evacuation cell, it may give up on rescuing the wireless terminal TE with poor communication quality and distribute and accommodate all wireless terminal TEs in each RU50 so that the total throughput of all wireless terminals is maximized.

[0105] (C-3) In each of the above embodiments, only configurations in which the OLT30 and ONU40 constituting the wireless access network 100 are connected via PtMP (Point To Multipoint) have been described, but configurations in which PtP (Point To Point) connections are also to be included, as shown in Figure 17.

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

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

[0108] In the wireless access network 100B shown in Figure 17, the OLT30 and ONU40 have been replaced with the OLT30B and ONU40B.

[0109] While the OLT30 and ONU40 in the first embodiment were configured to support only 10Gbps or 25Gbps MtMP connections, the wireless access network 100B differs in that it also supports 100Gbps PtP connections.

[0110] Specifically, the OLT30B differs from the OLT30 in that it has an additional media converter 36 (an element that performs photoelectric conversion of signals) that supports the transmission and reception of 100Gbps optical signals. In the OLT30B, ​​P media converters 36-1 to 36-P (where P is an integer of 1 or more) are arranged between the electrical switch 31 and the optical space switch 34. Furthermore, the OLT30B has k wavelength multiplexing units 35-1 to 35-k (where k is an integer of 2 or more), and PON (optical fiber 60 and N ONU 40B) are connected under each wavelength multiplexing unit 35. In the OLT30B, ​​each OSU 32, 33 and each media converter 36 can be connected to the ONU 40B at different wavelengths.

[0111] For example, if a RU50 requiring a bandwidth (communication speed) of 25 Gbps or more occurs in the wireless access network 100B, a bandwidth (communication speed) of 100 Gbps can be allocated to the RU50 by assigning one of the media converters 36 to the ONU 40B connected to the RU50 and establishing a PtP connection.

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

[0113] 1, 1A…Communication system, 10, 10A…Communication control device, 11, 11A…Presence / absence linkage function unit, 12, 12A…Wired / wireless linkage 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 that transmit and receive wireless signals with a wireless terminal; a signal processing device that performs signal transmission and reception processing with the wireless terminal 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, 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 that connects the master station communication device to each of the slave station communication devices, Each of the aforementioned wireless antenna devices, each of the cells corresponding to each of the aforementioned wireless antenna devices, and wireless control management means for managing and controlling the wireless terminals connected to each of the aforementioned wireless antenna devices, A wired 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, The system comprises a wired-wired control means for controlling the communication of the wireless terminals of each cell via the wireless control management means and the wired control management means, The wired / wireless cooperation control means, when a wireless antenna device subject to communication speed change occurs, performs a first connection change process to change the wireless terminals connected to the wireless antenna device subject to communication speed change to the wireless antenna device of a neighboring cell located near the cell to which the wireless antenna device subject to communication speed change belongs. After the first connection change process, it performs a communication speed change control process to change the communication speed of the wireless antenna device subject to communication speed change. After the communication speed change control process, it performs a second connection change process to change some or all of the wireless terminals connected to the wireless antenna device of the neighboring cell to the wireless antenna device subject to communication speed change. A communication system characterized by the following features.

2. The aforementioned wired / wireless interoperation control means is In the second connection change process, all wireless terminals connected to the wireless antenna device of the neighboring cell are changed to connect to the wireless antenna device subject to the communication speed change. After the second connection change process, a power saving control process is performed to control the wireless antenna device and the slave station communication device of the neighboring cell to a state of being stopped or operating with less power. The communication system according to feature 1.

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

4. The communication system according to claim 3, characterized in that when the wired / wireless cooperation control means performs the first connection change process, it repeatedly increases the transmission power intensity of the wireless antenna device of the neighboring cell with less traffic.

5. The communication system according to claim 3, characterized in that when the wired / wireless cooperation control means performs the first connection change process, it adjusts the transmission power intensity of the wireless antenna device of the neighboring cell so that the communication quality of the wireless terminal to be changed to the wireless antenna device of the neighboring cell is above a predetermined level.

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

7. The communication system according to claim 1, characterized in that the wired / wireless cooperation control means directly controls the wireless antenna device to be subject to communication speed change and the wireless terminal connected to the wireless antenna device of the neighboring cell to perform the first connection change process and the second connection change process.

8. A communication control device for controlling a communication system comprising: a plurality of wireless antenna devices that transmit and receive wireless signals with a wireless terminal; a signal processing device that processes the transmission and reception of signals with the wireless terminal 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, wherein the optical communication network has slave station communication devices connected to each of the wireless antenna devices, a master station communication device connected to the signal processing device, and an optical transmission path that connects the master station communication device to each of the slave station communication devices, Each of the aforementioned wireless antenna devices, each of the cells corresponding to each of the aforementioned wireless antenna devices, and wireless control management means for managing and controlling the wireless terminals connected to each of the aforementioned wireless antenna devices, A wired 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, The system comprises a wired-wired control means for controlling the communication of the wireless terminals of each cell via the wireless control management means and the wired control management means, The wired / wireless cooperation control means, when a wireless antenna device subject to communication speed change occurs, performs a first connection change process to change the wireless terminals connected to the wireless antenna device subject to communication speed change to the wireless antenna device of a neighboring cell located near the cell to which the wireless antenna device subject to communication speed change belongs. After the first connection change process, it performs a communication speed change control process to change the communication speed of the wireless antenna device subject to communication speed change. After the communication speed change control process, it performs a second connection change process to change some or all of the wireless terminals connected to the wireless antenna device of the neighboring cell to the wireless antenna device subject to communication speed change. A communication control device characterized by the following features.

9. A communication control method performed by a communication control device that controls a communication system comprising: a plurality of wireless antenna devices that transmit and receive wireless signals with a wireless terminal; a signal processing device that performs signal transmission and reception processing with the wireless terminal 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, wherein the optical communication network comprises slave station communication devices connected to each of the wireless antenna devices, a master station communication device connected 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 includes wireless control management means, wired control management means, and wired / wireless interoperation control means. The wireless control management means manages and controls each of the wireless antenna devices, the cells corresponding to each of the wireless antenna devices, and the wireless terminals connected to each of the wireless 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 / wireless coordinated control means controls the communication of the wireless terminals of each cell via the wireless control management means and the wired control management means. The wired / wireless cooperation control means, when a wireless antenna device subject to communication speed change occurs, performs a first connection change process to change the wireless terminals connected to the wireless antenna device subject to communication speed change to the wireless antenna device of a neighboring cell located near the cell to which the wireless antenna device subject to communication speed change belongs. After the first connection change process, it performs a communication speed change control process to change the communication speed of the wireless antenna device subject to communication speed change. After the communication speed change control process, it performs a second connection change process to change some or all of the wireless terminals connected to the wireless antenna device of the neighboring cell to the wireless antenna device subject to communication speed change. A communication control method characterized by the following:

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