Communication station system and communication system

Abstract

To more efficiently accommodate subscriber side devices connected to a plurality of branched optical fibers. [Solution] The present invention relates to a communication system comprising a plurality of communication station systems, and the communication station system of the present invention is a communication station system connected to a plurality of subscriber-side communication devices via a plurality of branched optical fibers, characterized in that it comprises a plurality of station-side accommodation units for accommodating and communicating with the subscriber-side communication devices, an optical switch having a plurality of outside station terminals and a plurality of inside station terminals and capable of switching optical signals between any of the outside station terminals and the inside station terminals, and each station-side accommodation unit is connected to an intra-station splitter that branches the subscriber-side terminals into a plurality of branches and connects them to the inside station terminals of the optical switch.

Description

[Technical Field]

[0001] This invention relates to a communication station system and a communication system, and can be applied, for example, to a communication system in which a one-to-multiple connection is made between a subscriber-side communication device (hereinafter referred to as "subscriber-side communication device") and the subscriber-side communication device using a multi-branched optical fiber (hereinafter simply referred to as "fiber"). [Background technology]

[0002] Conventional technologies for communication systems that connect a communication station (e.g., a communication station of a communication carrier) and a subscriber-side communication device in a one-to-multiple manner using optical fibers branched by a splitter (hereinafter simply referred to as "SP") include the technologies described in Patent Document 1 and Non-Patent Documents 1 and 2.

[0003] In the communication system described in Patent Document 1 (particularly FIG. 1 of Patent Document 1), multiple subscriber-side communication devices (Optical Network Units; hereinafter also referred to as "ONUs") are connected to the "multiple" connection side of a "1"-to-"multiple" connection optical branching network. The "1" connection side optical fiber is connected to an optical switch in a communication station (station equipment), and the optical switch connects the signal to one of the station-side accommodating devices (Optical Subscriber Units; hereinafter also referred to as "OSUs"). In the communication system described in Patent Document 1, when an OSU fails, the failure can be recovered by connecting the optical switch to another unused OSU. In other words, the communication system described in Patent Document 1 provides N+1 OSUs for N sets of optical branching networks, enabling it to respond to failures with fewer spare OSUs than the previous system in which two systems, a normal system and a spare system, were provided for each subscriber network.

[0004] In Non-Patent Document 1 (particularly Figure 5.2), the ONU is shown as an "NG-PON2 ONU" and the OSU is shown as an "NG-PON2 OLT" (hereafter referred to as an ONU and an OSU, respectively). The ONU can connect to any OSU by changing the wavelength.

[0005] Non-Patent Document 2 (particularly F.3-1 on page 91) describes a configuration in which an ONU switches between two connection modes, one-to-one (PtP: Point To Point) and one-to-multipoint (PtMP: Point To MultiPoint), and changes the connection destination. [Prior art documents] [Patent documents]

[0006] [Patent Document 1] Japanese Patent Application Laid-Open No. 2016-025575 [Non-patent literature]

[0007] [Non-Patent Document 1] ITU-T,“G.989 40-Gigabit-capable passive optical networks (NG-PON2): Definitions, abbreviations and acronyms”, [Online], INTERNET, [Retrieved June 2, 2024],<URL:https: / / www.itu.int / rec / T-REC-G.989-201510-I / en> [Non-patent document 2] IOWN Global forum, “Open All-Photonic Network Functional Architecture Version 2.0 (October 19, 2023)”, [Online], INTERNET, [Retrieved June 2, 2024], <URL:https: / / iowngf.org / wp-content / uploads / formidable / 21 / IOWN-GF-RD-Open_APN_Functional_Architecture-2.0.pdf> Summary of the Invention [Problem to be solved by the invention]

[0008] In the communication system described in Patent Document 1, N+1 sets of optical branching networks are prepared for N sets of optical branching networks, and the number of spare OSUs is reduced by connecting them with an optical space switch. Also, in the communication system of Non-Patent Document 1 (G.989), when there is little traffic in the ONUs, all ONUs can be connected to a specific OSU and other OSUs can be stopped, allowing for power-saving operation.

[0009] However, the communication system described in Patent Document 1 has a problem that an ONU in one optical branching network and an ONU in another branching network cannot be connected to the same OSU (hereinafter, this problem will be referred to as the "first problem"). Also, in the configuration shown in Figure 5.2 (NG-PON2 reference logical architecture) of Non-Patent Document 1, NG-PON2 It is not possible to connect an ONU to the above OSU from another ONU that is not connected to the "OSU 1." For example, in the communication system shown in FIG. 1 of Patent Document 1, the ONUs accommodated in the first splitter and the ONUs accommodated in the second splitter cannot be accommodated in the same OSU (if the optical switch is a normal switch with no branching loss in the inter-port connections). Therefore, in the communication system shown in FIG. 1 of Patent Document 1, even if the traffic is extremely low and one OSU can accommodate the traffic of all ONUs, it is not possible to accommodate all ONUs in one ONU. As a result, in the communication system shown in FIG. 1 of Patent Document 1, there are OSUs that operate unnecessarily, and power consumption cannot be reduced any further.

[0010] Furthermore, the communication system described in Patent Document 1 has a problem in that even when traffic is extremely light and the OSU of the first communication station has sufficient traffic capacity, the ONU accommodated in the OSU of the second communication station cannot be relocated to the OSU of the first communication station (hereinafter, this problem will be referred to as the "second problem"). Therefore, the communication system described in Patent Document 1 is inefficient in terms of power saving and fault countermeasures.

[0011] Furthermore, even if the ONU described in Non-Patent Document 2 (an ONU with a mode switching function between one-to-one connection and one-to-multiple connection) is applied to the communication system described in Patent Document 1, there is a problem that the above first and second problems cannot be solved (hereinafter, this problem will be referred to as the "third problem").

[0012] In view of the above problems, there is a need for a communication station system and a communication system that can more efficiently accommodate subscriber devices connected to a plurality of branched optical fibers. [Means for solving the problem]

[0013] The first invention is a communication station system connected to a plurality of subscriber-side communication devices by a plurality of branched optical fibers, comprising a plurality of station-side accommodation units that accommodate and communicate with the subscriber-side communication devices, an optical switch that has a plurality of outside-station terminals and a plurality of inside-station terminals and can switch optical signals between any of the outside-station terminals and the inside-station terminals, and each of the station-side accommodation units is connected to an inside-station splitter that branches the subscriber-side terminals into a plurality of branches and connects them to the inside-station terminals of the optical switch.

[0014] The second present invention is characterized by comprising a plurality of communication station systems according to the first present invention. [Effects of the Invention]

[0015] A communication station system and a communication system are provided that can more efficiently accommodate subscriber devices connected to a plurality of branched optical fibers. [Brief explanation of the drawings]

[0016] [Figure 1] 1 is a block diagram showing the overall configuration of a communication system and the functional configuration of a communication station system according to a first embodiment. [Figure 2] FIG. 2 is a diagram illustrating an example (part 1) of an operation when there is little traffic in the first optical branching network that constitutes the communication system according to the first embodiment. [Figure 3] FIG. 10 is a diagram illustrating an example (part 2) of an operation when there is little traffic in the first optical branching network that constitutes the communication system according to the first embodiment. [Figure 4] 3 is a diagram showing an example of operation when there is little traffic in the communication station system according to the first embodiment. FIG. [Figure 5] 1 is a diagram showing an example of changing the accommodation destination (OSU) of an ONU across communication station systems in a communication system according to a first embodiment. FIG. [Figure 6] 1 is a diagram showing an operation when ONUs are connected one-to-one in a communication system (communication station system) according to a first embodiment. FIG. [Figure 7] FIG. 10 is a block diagram showing the overall configuration of a communication system and the functional configuration of a communication station system according to a second embodiment. [Figure 8] FIG. 10 is a block diagram showing the overall configuration of a communication system and the functional configuration of a communication station system according to a third embodiment. DETAILED DESCRIPTION OF THE INVENTION

[0017] (A) First embodiment A first embodiment of a communication station system and a communication system according to the present invention will be described in detail below with reference to the drawings.

[0018] (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.

[0019] The communication system 1 is a system that connects (communicates) with ONUs 32, which serve as subscriber-side communication devices, and are located in first to third regional subscriber areas. The first to third regional subscriber areas each include a first to third regional office (e.g., a communication office of a communication carrier). The communication system 1 also includes a communication office system 10 (10-1 to 10-3) that connects the first to third regional offices to the ONUs 32 in the corresponding subscriber area. The communication system 1 also includes a core-office communication office system 50 located in a core office that serves as a host office for the first to third regional offices, and an optical space SW network 70 serving as an optical communication network for communication between the communication office systems. The communication system 1 also includes an optical fiber that is branched into multiple optical fibers by an SP 31 located outside the office. In this embodiment, the number of branches of the SP 31 located outside the office is not limited, but all of the SPs are described as having eight branches. That is, in this embodiment, it is assumed that in each regional subscriber area, eight ONUs 32 are connected under each SP 31. Note that it is not necessary for all SPs 31 to have the same number of branches, and this may be changed depending on the location (place) where they are installed.

[0020] The optical space SW network 70 is an optical communication network capable of communicating by optical signals, and can be configured, for example, by a collection of multiple optical switches. The optical space SW network 70 is connected to each of the communication station systems 10, 50 by optical terminals (interfaces that accommodate optical fibers), enabling communication of optical signals between any two communication station systems 10, or between any two communication station systems 10 and 50.

[0021] A data center (hereinafter also referred to as "regional station DC") 40 (40-1 to 40-3) is disposed in each of the first to third regional stations. A data center (hereinafter also referred to as "core station DC") is also disposed in the core station. The regional stations DC40-1 to 40-3 and the core station DC50 are each configured with a network (not shown) (for example, a network configured with layer 2 switches, routers, etc. (not shown)) and a server device (not shown). The communication station systems 10-1 to 10-3 of the first to third regional stations are respectively connected to the regional stations DC40-1 to 40-3 (the network of each data center). The communication station system 50 of the core station is also connected to the core station DC60.

[0022] Next, the internal configuration of the communication station system 10 of each regional station will be described.

[0023] The internal configurations of the communication station systems 10-1 to 10-3 are similar except for the number of elements (for example, the number of components and the number of optical fiber branches), so here we will explain in detail the internal configuration of communication station system 10-1 as a representative.

[0024] In this embodiment, the communication station system 10-1 includes an electric SW 11, k1*4 (k1 is an integer of 2 or more) OSUs 12 (12-1-1, 12-1-2, 12-1-3, 12-1-4, 12-2-1, . . . , 12-k1-1, 12-k1-2, 12-k1-3, 12-k1-4) as station-side accommodation units, k1 (k1 is an integer of 2 or more) ptp transceivers 13 (13-1 to 13-k1) as ptp transceivers (transceivers that perform one-to-one optical-electrical / electrical-optical conversion; hereinafter, also simply referred to as "ptp"), and optical transceivers (Optical Termination The optical fiber includes OTUs 14 (14-1 to 14-p1) as optical fiber splitters (hereinafter simply referred to as "OTUs"), SPs 15 (15-1-1, 15-1-2, 15-1-3, 15-1-4, 15-2-1, . . . , 15-k1-1, 15-k1-2, 15-k1-3, 15-k1-4) as k1*4 intra-office splitters, an optical space switch (SW) 16 as an optical switch, and k1*4 optical wavelength multiplexers / demultiplexers (WDMs). The optical communication network has m1 (m1 is an integer greater than or equal to 2) WDMs 18 (18-1 to 18-m1) as optical communication network connection means, and m1 (m1 is an integer greater than or equal to 2) WDMs 18 as optical communication network connection means.

[0025] Each communication station system 10 is basically designed to accommodate 32 ONUs 32 with four OSUs 12. Communication station system 10-1 has k1 sets of four OSUs 12 (i.e., 4*k1 OSUs 12). And, k1*32 ONUs 32 are arranged under communication station system 10-1 (first regional subscriber area).

[0026] As described above, each SP 31 has eight branches, so four SPs 31 are arranged for one set of OSUs 12 (four OSUs 12). As shown in FIG. 1, 4*k1 SPs 31 (31-1-1, 31-1-2, 31-1-3, 31-1-4, 31-2-1, . . . , 31-k1-1, 31-k1-2, 31-k1-3, 31-k1-4) are arranged in the first regional subscriber area. That is, in each communication station system 10, a communication network with up to 32 branches (hereinafter simply referred to as an "optical branching network") is configured with one set (four) of OSUs 12. That is, in this embodiment, one optical branching network is assumed to have four OSUs 12, four SPs 31, and 32 ONUs 32. In this embodiment, the number of OSUs 12 constituting each optical branching network and the number of ONUs 32 accommodated in each optical branching network are merely examples and are not limited to these. For example, the number of OSUs 12 constituting each optical branching network may be designed to be any number other than four. Furthermore, the number of branches of SPs 31 located outside the station may be designed to be any number other than eight.

[0027] In the communication system 1 of this embodiment, each element is managed by dividing it into optical branching networks, and in each drawing, a reference numeral is assigned to each optical branching network. For example, in the communication station system 10-1, a first branching network is configured with OSUs 12-1-1 to 12-1-4 as the center, and SPs 15-1-1 to SP15-4-4 and WDMs 17-1-1 to 17-1-4 are arranged in the first branching network. ONUs 32-1-1 to ONUs 32-1-32 (including SPs 31-1-1 to SP31-1-4) are assigned under the first branching network. In other words, communication station system 10-1 and its subordinates are configured with k1 optical branching networks, and the qth optical branching network (q is an integer from 1 to k1) is configured with OSU12-q-1 to 12-q-4, SP15-q-1 to SP15-q-4, WDM17-q-1 to 17-q-4, SP31-q-1 to SP31-q-4, and ONU32-q-1 to ONU32-q-32.

[0028] The electrical SW11 is a switch (for example, a network device that can process packets such as a Layer 2 switch, Layer 3 switch, or router) for connecting elements together, such as connecting to the regional station DC40 (inside the station), connecting between the subordinate OSU12 and OTU14, or connecting between the PtP13 and OTU14.

[0029] The optical space SW16 is a device that enables optical communication (optical communication between optical terminals) along any route between elements (optical terminals) in the communication station system 10-1, and can be configured by, for example, an optical switch.

[0030] In the communication station system 10-1, the above-described configuration connects the ONU 32 side (i.e., the subscriber side), the optical space SW network 70, and the local station DC 40. As will be described later, the communication station system 10-1 enables communication of optical signals with other communication station systems 10 or 50 by the OTU 14, the optical space SW 16, the WDM 18, etc.

[0031] Each OSU 12 is connected to an optical space SW 16 via an SP 15 on the subscriber side (optical terminal side), and is connected to an electrical SW 11 on the station side. OSUs 12-1-1 to 12-k1-4 are connected to SPs 15-1-1 to 15-k1-4, respectively.

[0032] Each SP15 is a splitter with a1 number of branches (a1 is an integer equal to or greater than 2). SP15 is connected to OSU12 via one optical fiber (optical terminal), and on the optical space SW16 side, it branches into a1 branches and connects to optical space SW16. Here, a1 (the number of branches of SP15) is desirably greater than the number of OSU12 (four in this embodiment) that make up one optical branching network.

[0033] WDM 17 is connected to SP31 on the subscriber side via one optical fiber (optical terminal), and is connected to optical space SW16 (inside the local office) via b1 (b1 is an integer equal to or greater than 2) optical fibers (optical terminals). WDM 17 multiplexes optical signals of multiple wavelengths onto a single optical fiber for the subscriber side. In this embodiment, WDM 17 is described as multiplexing optical signals of four wavelengths, λ1 to λ4, but the wavelengths (frequency bands) and number of wavelengths of the corresponding optical signals are not limited. In this embodiment, WDMs 17-1-1 to 17-k1-4 are connected to SP31-1-1 to 31-k1-4, respectively, as external splitters.

[0034] Each ptp 13 and each OTU 14 is a means (a transceiver that performs one-to-one optical-electrical / electrical-to-optical conversion) for one-to-one connection between the electrical SW 11 and the optical space SW 16. Each ptp 13 is an element (ptp transceiver) arranged for the purpose of accommodating and connecting an ONU 32 operating in one-to-one connection mode via the optical space SW 16 and the WDM 17. Also, each OTU 14 is an element (hereinafter also referred to as "other station connection means") arranged for one-to-one connection with an OTU 14 arranged in another communication station system 10, 50.

[0035] Each WDM 18 is connected to the optical space SW network 70 outside the station via a single optical fiber (optical terminal), enabling communication using optical signals multiplexed with multiple wavelengths, and is connected to the inside of the station (optical space SW 16) via c1 (c1 is an integer greater than or equal to 2) optical fibers (optical terminals).

[0036] As described above, in the communication station system 10-1, each OSU 12 is connected to an ONU 32 via, in order from the station side, the SP 15, the optical space SW 16, the WDM 17, and the SP 31. Each ONU 32 corresponds to a means (variable wavelength transmitting / receiving means) that can change the wavelength of the optical signal used for communication with the station side to one of the wavelengths (λ1 to λ) supported by the WDM 17. Each ONU 32 is also capable of transmitting and receiving optical signals to and from the station side at a wavelength according to a control signal from the station side.

[0037] Hereinafter, in the optical space SW 16, a connection terminal to the inside of the optical station (SP 15, OTU 14, or ptp 13) will be referred to as an "inside terminal," and a connection terminal to the outside of the optical station (WDM 17 or WDM 18; subscriber side or optical communication network side) will be referred to as an "outside terminal." The optical space SW 16 is assumed to be capable of routing control between at least any combination of inside terminals and outside terminals. For example, the optical space SW 16 is assumed to be capable of routing optical signals so that any outside terminal is connected to any inside terminal. The optical space SW 16 is also assumed to be capable of routing between the subscriber side (any WDM 17) and the optical communication network side (any WDM 18). The specific method (optical switching method) for routing optical signals in the optical space SW 16 is not limited, and various methods can be applied.

[0038] Next, differences between the internal configurations of the communication station systems 10-2 and 10-3 and the communication station system 10-1 will be described.

[0039] 1, the internal configurations of communication station systems 10-2 and 10-3 are the same as those of communication station system 10-1 except for the number of elements. Specifically, communication station system 10-2 differs from communication station system 10-1 in that a1, b1, c1, k1, p1, and m1 are replaced with a2, b2, c2, k2, p2, and m2, respectively. Communication station system 10-3 also differs from communication station system 10-1 in that a1, b1, c1, k1, p1, and m1 are replaced with a3, b3, c3, k3, p3, and m3, respectively. Note that, like a1, a2 to a4 are also preferably greater than the number of OSUs 12 (four in this embodiment) that make up the OSU 12 set.

[0040] Next, the internal configuration of the core station communication station system 50 will be described.

[0041] 1, since there is no corresponding regional subscriber area for the core station, the communication station system 50 of the core station is different from the communication station system 10 in that it is not equipped with a WDM 17 for connecting to the subscriber side (ONU 32). Also, the communication station system 50 differs from the communication station system 10-1 in that a1, c1, k1, p1, and m1 are replaced with a4, c4, k4, p4, and m4, respectively.

[0042] Next, the design concept of each communication station system 10 will be described.

[0043] In the communication system 1, splitters are arranged separately inside and outside each communication station system 10. Specifically, inside each communication station system 10, an SP31 is arranged between an optical space SW16 and an OSU12.

[0044] As a result, each communication station system 10 accommodates k1 basic optical branching networks (optical branching networks each consisting of one OSU 12) with a total of 32 branches, including eight branches outside the station and four branches (or more than four branches) inside the station. As described above, each ONU 32 corresponds to a variable wavelength transmitting / receiving means. In the communication station system 10-1, optical signals from the subscriber side are demultiplexed by wavelength using the WDM 17 and guided to the OSU 12 at the end of the output route set by the optical space SW 16. As described above, in the communication station system 10 of this embodiment, four OSUs 12 are provided per optical branching network 32 subscriber. For an optical branching network with heavy traffic, for example, all four OSUs 12 are operated to accommodate an average of eight ONUs 32 per OSU 12. For an optical branching network with light traffic, only one to three OSUs 12 are operated to accommodate the ONUs 32 under their control, thereby reducing power consumption.

[0045] In the communication station system 10, the OTU14 can be used to access the OTU14 at another base station on a one-to-one basis via the optical space SW16, the WDM 18, and the optical space SW network 70. Furthermore, within the station, the OTU14 is connected to the OSU12 and the data center (regional station DC40, core station DC60) within the station via the electrical SW11. For example, by establishing a one-to-one connection between the OTU14 of the communication station system 10-1 and the OTU14 of the core station communication station system 50 via the optical space SW network 70, a low-latency communication path can be established between the OSU12 of the communication station system 10-1 or the regional station DC40-1 and the OSU12 of the core station communication station system 50 or the core station DC60. Such a low-latency communication path establishment between base stations is suitable for applications requiring connection to a DC other than the DC of the regional station in which the ONU12 is accommodated.

[0046] Furthermore, in each communication station system 10, a WDM 17 is connected to the outside (subscriber side) of the optical space SW 16, and an SP 15 is connected to the inside of the optical space SW 16, thereby enabling separate routing control for communications for each ONU 32 in the optical space SW 16. As a result, in the communication system 1, routing control of the optical space SW 16 and the optical space SW network 70 of each communication station system 10, 50 makes it possible to accommodate ONUs 32 across the communication station systems 10, 50 (areas). Note that the optical space SW 16 network may be an optical wavelength SW network, or may be configured to be directly connected to other regional stations or core stations without going through a switch (for example, a configuration in which a direct optical transmission path is set).

[0047] In this embodiment, even in the core station communication station system 50 that is not intended to directly accommodate ONUs 32, OSUs 12 and ptps 13 are provided to accommodate ONUs 32 under the control of other regional stations. This allows the entire communication system 1 to be configured to further increase the accommodation efficiency of subscribers (ONUs 32). For example, it becomes possible to share the core station communication station system 50 as a shared backup system in each region.

[0048] (A-2) Operation of the First Embodiment Next, the operation of the communication system 1 (communication station systems 10, 50) according to the first embodiment will be described.

[0049] First, using Figure 1, we will explain an example of the operation of communication station system 10-1 (in a first regional subscriber area) when there is heavy traffic and all ONUs 32 in the first regional subscriber area are performing communications suitable for 1:multiple connections. Here, we will focus on the operation of the first optical branching network consisting of OSUs 12-1-1 to 12-1-4. Here, we will assume that ONUs 32-1-1 to 32-1-32 are normally accommodated in the first optical branching network. Here, it is assumed that the eight ONUs 32-1-1 to 32-1-8 under the control of SP15-1-1 transmit optical signals with wavelength λ1, the eight ONUs 32-1-9 to 32-1-16 under the control of SP15-1-2 transmit optical signals with wavelength λ2, the eight ONUs 32-1-17 to 32-1-24 under the control of SP15-1-3 transmit optical signals with wavelength λ3, and the eight ONUs 32-1-25 to 32-1-32 under the control of SP15-1-4 transmit optical signals with wavelength λ4. At this time, the optical signals transmitted from the ONUs 32 belonging to the first optical branching network are time division multiplexed (TDM) by SP15-1-1 to 15-1-4 and input to WDMs 17-1-1 to 17-1-4, respectively. If the number of wavelengths multiplexed in WDM 17 is 32, then b1 = 32, and the output is sent to optical space SW 16. In optical space SW 16, the λ1 output of WDM 17-1-1 is connected to one of a1 terminals of SP1-1 connected to OSU 121-1-1, and is then guided to OSU 121-1-1. Similarly, signals of λ2 to λ4 are guided to OSUs 121-1-2 to 121-1-4. As a result, each OSU 12 constituting the first optical branching network communicates with eight ONUs 32. In other words, OSU1-1-1 is connected to eight ONUs 32-1-1 to 32-1-8 under the control of SP31-1-1, OSU1-1-2 is connected to eight ONUs 32-1-9 to 32-1-16 under the control of SP31-1-2, OSU1-1-3 is connected to eight ONUs 32-17-1 to 32-1-24 under the control of SP31-1-3, and OSU1-1-4 is connected to eight ONUs 32-1-25 to 32-1-32 under the control of SP31-1-4.

[0050] Next, the operation of the first optical branching network when there is little traffic, specifically when one OSU 121 can accommodate all 32 ONUs 32 without any problems, will be described with reference to FIGS. 2 and 3. FIG.

[0051] FIG. 2 is a diagram showing an example (part 1) of the operation when there is little traffic in the first optical branching network that constitutes the communication system 1. In FIG.

[0052] In the state of Figure 2, all 32 ONUs 32-1-1 to 32-1-32 under SPs 31-1-1 to 31-1-4 transmit signals using λ1 and are all connected to OSU 12-1-1. In the state of Figure 2, the other OSUs 12-1-2 to 12-1-4 in the first branch network are stopped, thereby enabling power-saving operation of communication station system 10-1. Furthermore, if the traffic volume in the first branch network is such that two OSUs 12 can accommodate 32 ONUs 32, then 16 ONUs 32-1-1 to 32-1-16 can be connected to OSU 12-1-1 using λ1, and another 16 ONUs 32-1-17 to 32-1-32 can be connected to OSU 12-1-2 using λ2, and the remaining OSUs 12-1-3 and 12-1-4 can be stopped, thereby enabling power-saving operation.

[0053] FIG. 3 is a diagram showing an example (part 2) of the operation when there is little traffic in the first optical branching network constituting the communication system 1. In FIG.

[0054] In Figure 3, the lines (connection paths) between elements are distinguished by the wavelengths used (destination OSU12) and are shown as dashed lines, dashed lines, or two-dot chain lines. In Figure 3, dashed lines indicate paths for communication related to wavelength λ1 (communication with destination OSU12-1-1), dashed lines indicate paths for communication related to wavelength λ2 (communication with destination OSU12-1-2), and dashed lines indicate paths for communication related to wavelength λ3 (communication with destination OSU12-1-3).

[0055] In the first branch network shown in FIG. 3, 32 ONUs 32 are accommodated using three wavelengths (λ1 to λ3) for three OSUs 12-1-1 to 12-1-3. Specifically, in Figure 3, the 32 ONUs 32-1-1 to 32-1-32 are divided into a group of two ONUs, 32-1-3 and 32-1-11 (hereinafter referred to as the "first group"), a group of 14 ONUs, 32-1-1, 32-1-2, 32-1-4 to 32-1-10, and 32-1-12 to 32-1-16 (hereinafter referred to as the "second group"), and a group of 16 ONUs, 32-1-17 to 32-1-32 (hereinafter referred to as the "third group"). The first group is connected to OSU12-1-1 via λ1, the second group is connected to OSU12-1-2 via λ2, and the third group is connected to OSU12-1-3 via λ3. In FIG. 3, the OSU 12-1-4 to which the ONU 32 is not connected is powered off (or put into power saving mode) to operate in a power saving mode.

[0056] So far, we have explained an example in which all ONUs 32 are accommodated by fewer OSUs 12 than usual when traffic is low in one optical branching network, but when traffic is low across the entire communication station system 10, a configuration may be used in which even more ONUs 32 are connected to OSUs 12 across the optical branching network (a configuration in which fewer OSUs 12 are used for operation).For example, as shown in Figure 4, within the communication station system 10, ONUs 32 that are normally divided into multiple optical branching networks and belong to them may be accommodated together in one OSU 12 of any of the optical branching networks.

[0057] FIG. 4 is a diagram showing an example of operation when there is little traffic in the communication station system 10-1.

[0058] Figure 4 shows the operating states of a first optical branching network consisting of OSU12-1-1 to 12-1-4 and ONU32-1-1 to 32-1-32, a second optical branching network consisting of OSU12-2-1 to 12-2-4 and ONU32-2-1 to 32-2-32, and a third optical branching network consisting of OSU12-3-1 to 12-3-4 and ONU32-3-1 to 32-3-32.

[0059] In Figure 4, the lines (connection paths) between elements are distinguished by dashed lines and dashed-dotted lines for each wavelength (destination OSU12). In Figure 4, dashed lines indicate paths for communication related to wavelength λ1 (communication with destination OSU12-1-1), and dashed-dotted lines indicate paths for communication related to wavelength λ2 (communication with destination OSU12-2-1).

[0060] In the first to third branch networks shown in Fig. 4, 96 ONUs 32 are assigned to two OSUs 12-2-1 and 12-2-2 using two wavelengths (λ1 and λ2). Specifically, in Fig. 4, the ONUs are divided into a group of 42 ONUs 32-1-1 to 32-1-32 and 32-2-1 to 32-2-10 (hereinafter referred to as the "fourth group") and a group of 54 ONUs 32-2-11 to 32-2-32 and 32-3-1 to 32-3-32 (hereinafter referred to as the "fifth group"), and the fourth group is connected to OSU 12-1-1 via λ1, and the fifth group is connected to OSU 12-2-1 via λ2. The other OSUs 12 in the first to third branch networks are powered off (or in power-saving mode) for power-saving operation.

[0061] In this case, in the communication station system 10-1, there is little traffic in the first to third branch networks, the traffic generated by the 42 ONUs 32 belonging to the first group is the same as (or slightly less than) the traffic that can be processed by OSU12-1-1 of the first branch network, and the traffic generated by the 54 ONUs 32 belonging to the second group is the same as (or slightly less than) the traffic that can be processed by OSU12-2-1 of the second branch network, so the system is operated as shown in Figure 4.

[0062] As described above, in the communication station system 10, a total of 96 ONUs 32 can be accommodated in two OSUs 12. The reason this type of operation is possible in the communication station system 10 is because the SP15 (a1 branch) is located after the optical space SW16 (inside the station) and a1 is set to a value greater than the number of OSUs 12 (4) in the optical branching network. Furthermore, even when a1 = 4, in the communication station system 10, any ONU 32 can be accommodated in any OSU 12 within the same regional subscriber area, which significantly expands the range of combinations of ONUs 32 that can be accommodated in an OSU 12, thereby improving accommodation efficiency.

[0063] The explanation so far has been about the operation of arbitrarily changing the OSU 12 that accommodates the ONU 32 within the same communication station system 10. However, as shown in FIG. 5, in the communication system 1, the OSU 12 that accommodates the ONU 32 can be changed across the communication station systems 10 and 50.

[0064] FIG. 5 is a diagram showing an example of changing the accommodation location of an ONU 32 across communication station systems 10 and 50. In FIG.

[0065] In FIG. 5, the paths connected to the OSU 12-1-1 that constitutes the communication station system 10-1 of the first regional station are shown by dashed lines.

[0066] Figure 5 shows an example in which a group of eight ONUs 32-1-1 to 32-1-8 in the first regional subscriber area (hereinafter referred to as the "sixth group") and a group of eight ONUs 32-1-1 to 32-1-8 in the third regional subscriber area (hereinafter referred to as the "seventh group") are connected to OSU 12-1-1 that constitutes communication station system 10-1 in the first regional station.

[0067] Here, it is assumed that the total traffic generated by the eight ONUs 32 belonging to the sixth group and the eight ONUs 32 belonging to the seventh group is the same as (or slightly less than) the traffic that can be processed by the OSU 12-1-1 constituting the communication station system 10-1. Therefore, in FIG. 5, the traffic of the sixth group and the traffic of the seventh group can be multiplexed and accommodated by the single OSU 12-1-1 constituting the communication station system 10-1. In the communication station system 10-1 of the first regional station, the wavelength λ1 is set for all of the ONUs 32-1-1 to 32-1-32 belonging to the sixth group. Similarly, in the communication station system 10-3 of the third regional station, the wavelength λ1 is set for all of the ONUs 32-1-1 to 32-1-32 belonging to the seventh group.

[0068] Signals from the sixth group (ONUs 32-1-1 to 32-1-8 in the first regional subscription area) are supplied to OSU 12-1-1 (first regional station) via WDM 17-1-1 (first communication station), optical space SW 16 (first communication station), and SP 15-1-1 (first communication station). Signals from the seventh group (ONUs 32-1-1 to 32-1-8 in the third regional subscription area) are supplied to OSU 12-1-1 (first regional station) via WDM 17-1-1 (third regional station), optical space SW 16 (third regional station), WDM 18-m3 (third regional station), optical space SW network 70, WDM 18-1 (first regional station), optical space SW 16 (first regional station), and SP 15-1-1 (first regional station). At this time, the optical space SW16 (third regional station) switches so that optical signals can be transmitted and received between WDM17-1-1 (third regional station) and WDM18-m3 (third regional station). As a result, in the state of Fig. 5, signals from the sixth group (ONUs 32-1-1 to 32-1-8 in the first regional subscription area) and the seventh group (ONUs 32-1-1 to 32-1-8 in the third regional subscription area) are time division multiplexed (TDM) by SP15-1-1 and supplied to OSU12-1-1.

[0069] In the above description of operation, the ONUs 32 are connected one to many, but as shown in FIG. 6, the ONUs 32 may also operate in a one to one connection mode.

[0070] FIG. 6 shows the operation of the communication system 1 when the ONUs 32 are connected one-to-one.

[0071] 6 shows the communication paths for communication between a group of ONUs 32-1-1 to 32-1-7 in the first regional subscriber area (hereinafter referred to as the "eighth group"), ONU 32-1-8 in the first regional subscriber area, and ONU 32-k1-32 in the first regional subscriber area. In Fig. 6, the communication paths for ONUs 32 in the eighth group (including branching due to packet distribution by electrical SW11) are indicated by dashed lines, the communication paths for ONU 32-1-8 are indicated by dashed lines, and the communication paths for ONU 32-k1-32 are indicated by dashed lines.

[0072] In the state shown in Figure 6, the ONUs 32 in the eighth group operate in a point-to-multipoint connection mode (hereinafter referred to as "PtMP mode"), communicating using λ1, and are accommodated in OSU12-1-1. The seven ONUs 32 in the eighth group can communicate with the regional station DC40-1 in the first regional station, the regional station DC40-2 in the second regional station, and the core station DC60 in the core station, respectively, through the routing process (layer 3 path control) or switching process (layer 2 path control) of the electrical SW11. Packets from the ONUs 32 in the eighth group to the above three destinations are distributed by the electrical SW11 in the first regional station through the routing process or switching process. In the electrical SW11 in the first regional station, packets to other locations are transmitted via the OTU14, etc. For example, a packet from the ONU 32 of the eighth group to the local station DC40-1 of the first local station is directly transferred by the electrical SW11 of the first local station (see the path indicated by the dashed line). Also, for example, a packet from the ONU 32 of the eighth group to the local station DC40-2 of the second local station (see the path also indicated by the dashed line) is distributed to the OTU14-p1 (first local station) by the electrical SW11 of the first local station, and then passes through the optical space SW16 (first local station), the WDM 18-m1 (first local station), the optical space SW network 70, the WDM 18-1 (second local station), the optical space SW16 (second local station), the OTU14-1 (second local station), and the electrical SW11 (second local station) before arriving at the local station DC40-2 of the second local station. Furthermore, for example, a packet from ONU32 of the eighth group to core station DC60 of the core station (see the route also indicated by the dashed line) is distributed to OTU14-1 by electrical SW11 of the first regional station, and then passes through optical space SW16 (first regional station), WDM18-1 (first regional station), optical space SW network 70, WDM18-m4 (core station), optical space SW16 (core station), OTU14-1 (core station) and electrical SW11 (core station) before reaching core station DC60. Note that a packet that has arrived at electrical SW11 of another base from ONU32 of the eighth group may be further forwarded to another base by the forwarding destination electrical SW11.

[0073] 6, the wavelength of ONU 32-1-8 in the first regional subscriber area is set to λ2. The signal transmitted from ONU 32-1-8 in the first regional subscriber area (see the route indicated by the dashed-dotted line) is sent to the communication station system 10-1 of the first regional station together with the signals of ONUs 32-1-1 to 32-1-7 of the eighth group, and after being separated by WDM 17-1-1, reaches the regional station DC 40-1 of the first regional station via optical space SW16, ptp 13-2 and electrical SW11.

[0074] Generally, PtP communication is much faster than PtMP communication, so when a subscriber wants to communicate at high speeds, it is preferable to use a PtP transceiver rather than a PtMP transceiver, or to communicate in PtP mode using an ONU with a PtP / PtMP switching function.In the state shown in Figure 6, ONU32-k1-32 in the first regional subscriber area is operating in a one-to-one connection operating mode with wavelength λ2 (hereinafter referred to as "PtP mode"). A signal transmitted from ONU32-k1-32 in the first regional subscriber area (see the route indicated by the two-dot dashed line) is sent to the communication station system 10-1 of the first regional station, separated by WDM17-k1-4, and then passes through optical space SW16 (first regional station), WDM18-1 (first regional station), optical space SW network 70, WDM18-m4 (core station), optical space SW16 (core station), ptp13-2 (core station), and electrical SW11 (core station) to reach core station DC60. In other words, the signal from ONU32-k1-32 in the first regional subscriber area bound for core station DC60 is wavelength-multiplexed with the signal from ONU32 in the eighth group and transferred.

[0075] (A-3) Effects of the First Embodiment According to the first embodiment, the following effects can be achieved.

[0076] In the communication system 1 of the first embodiment, by disposing the SP 15 between the optical space SW 16 and the OSU 12, any signal from any ONU 32 can be accommodated in any OSU 12. This increases the efficiency of accommodating ONUs 32 in the OSU 12 in the communication system 1, enabling operation with less power consumption. Furthermore, by sharing the spare OSU 12 in the communication system 1, the communication system 1 can reduce construction costs while preparing for failures and the like.

[0077] Furthermore, in the communication system 1 of the first embodiment, the number of connections per OSU 12 can be increased by increasing the number of branches (a1) of the SP 15. However, increasing the number of branches (a1) of the SP 15 also increases branch loss.

[0078] Furthermore, in the communication system 1 of the first embodiment, by disposing an optical space SW network 70 between the communication station systems 10 and 50, it is possible to accommodate both the ONU 32 of another communication station system 10 and the ONU 32 of the own station in the same OSU 12. This allows the communication system 1 to share the OSU 12 across stations (bases), thereby improving the accommodation efficiency of the ONU 32 across stations (bases) and realizing the sharing of a backup system.

[0079] Furthermore, in the communication station systems 10 and 50, even if there is an ONU 32 that operates in the PtP connection mode, it can be accommodated without any problems by providing the ptp 13 and the OTU 14. For example, even if there is an ONU 32 that can be switched between the PtP connection mode and the PtMP connection mode and this ONU 32 operates in the PtP connection mode, it can be accommodated without any problems by directing the connection destination in the communication station system 10 to the ptp 13 instead of the OSU 12.

[0080] (B) Second embodiment A second embodiment of a communication station system and a communication system according to the present invention will be described in detail below with reference to the drawings.

[0081] (B-1) Configuration and operation of the second embodiment FIG. 7 is a block diagram showing the overall configuration of a communication system 1A according to the second embodiment, and the same or corresponding parts as those in FIG. 1 above are denoted by the same or corresponding reference numerals.

[0082] The following describes the differences between the second embodiment and the first embodiment.

[0083] The communication system 1 of the second embodiment differs from the first embodiment in that the communication station systems 10 (10-1 to 10-3) are replaced with communication station systems 10A (10A-1 to 10A-3).

[0084] FIG. 1 shows a detailed configuration of a communication station system 10A-1 of a first regional station as a representative of the communication station systems 10A.

[0085] In the communication station system 10 of the first embodiment, the input / output terminals required for the optical space SW16 are very large, but in the communication station system 10A of the second embodiment, the number of input / output terminals required for the optical space SW16 is configured to be able to be reduced.

[0086] In the first embodiment, all terminals on the inside of each WDM17 are connected to the optical space SW16, but in the second embodiment, some terminals of each WDM17 are directly connected to SP15 in the same optical branching network, thereby reducing the number of terminals directly connected in the optical space SW16.

[0087] 7, two terminals of each WDM 17 are directly connected to SP 15 in the same optical branching network, and the other terminals (i.e., terminals b1-2) are connected to optical space SW 16. Also in FIG. 7, two terminals of each SP 15 are directly connected to WDM 17 in the same optical branching network, and the other terminals (i.e., terminals a1-2) are connected to optical space SW 16. This makes it possible to reduce the number of terminals in optical space SW 16 by 2*k1 on the outside (subscriber side) of the station and by 2*k1 on the inside of the station.

[0088] 7 illustrates an example of the connection relationships within the first optical branching network (OSU12-1-1 to OSU12-1-4). In FIG. 7, WDM 17-1-1 is directly connected to each of SPs 15-1-1 and 15-1-2. Also, in FIG. 7, WDM 17-1-2 is directly connected to each of SPs 15-1-2 and 15-1-3. Furthermore, in FIG. 7, WDM 17-1-3 is directly connected to each of SPs 15-1-3 and 15-1-4. Furthermore, in FIG. 7, WDM 17-1-4 is directly connected to each of SPs 15-1-4 and 15-1-1. Note that in each optical branching network, the combination of SPs 15 to which each WDM 17 is directly connected is not limited to the example in FIG. 7, and various combinations can be applied. In each branch network, the number of terminals directly connected between WDM 17 and SP 15 is not limited as long as it is less than the number of wavelengths to be frequency-multiplexed. For example, in this embodiment, the number of wavelengths that WDM 17 can handle is four, so the number of terminals directly connected must be three or less.

[0089] Each WDM 17 must be assigned a different wavelength for each output destination (either SP 15 or optical space SW 16). For example, in FIG. 7, WDM 17-1-1 is connected to SPs 15-1-1 and 15-1-2 and optical space SW 16, so a different wavelength must be assigned to each. For example, WDM 17-1-1 may assign λ1 to the path to SP 15-1-1 (OSU 12-1-1), λ2 to the path to SP 15-1-2 (OSU 12-1-2), and λ3 and λ4 to the path to optical space SW 16. As a result, ONUs 32-1-1 to 32-1-8 under WDM 17-1-1 communicate using λ1 when connected to OSU 12-1-1, use λ2 when connected to OSU 12-1-2, and use either λ3 or λ4 when connected to other OSUs 12.

[0090] (B-2) 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.

[0091] As described above, in each communication station system 10A constituting the communication system 1A of the second embodiment, the number of terminals required in the optical space SW16 can be reduced compared to the first embodiment.

[0092] (C) Third embodiment A third embodiment of a communication station system and a communication system according to the present invention will be described in detail below with reference to the drawings.

[0093] (C-1) Configuration and Operation of the Third Embodiment FIG. 8 is a block diagram showing the overall configuration of a communication system 1B according to the third embodiment, and the same or corresponding parts as those in FIG. 7 above are denoted by the same or corresponding reference numerals.

[0094] The following describes the differences between the third embodiment and the second embodiment.

[0095] The communication system 1B of the third embodiment differs from the second embodiment in that the communication station systems 10A (10A-1 to 10A-3) are replaced with communication station systems 10B (10B-1 to 10B-3).

[0096] FIG. 1 shows a detailed configuration of a communication station system 10B-1 of a first regional station as a representative of the communication station systems 10B.

[0097] The communication station system 10B of the third embodiment is configured to be able to further reduce the number of input / output terminals required for the optical space SW16 compared to the second embodiment.

[0098] In the communication station system 10B of the third embodiment, some terminals are directly connected to one-to-one connection destinations (for example, ptp 13 and OTU 14) in each WDM 17. This allows the number of terminals in the optical space SW 16 to be reduced by the number of terminals directly connected from the WDM 17 to one-to-one connection destinations.

[0099] For example, in the WDM 17-1-1 in Figure 8, one terminal is directly connected to the ptp 13-1. Since the WDM 17-1-1 is connected to SPs 15-1-1 and 15-1-2, the optical space SW16, and the ptp 13-1, different wavelengths must be assigned to each of them. For example, in the WDM 17-1-1, λ1 may be assigned to the path to SPs 15-1-1 (OSU 12-1-1), λ2 to the path to SPs 15-1-2 (OSU 12-1-2), λ3 to the path to the ptp 13-1, and λ4 to the path to the optical space SW16. As a result, ONUs 32-1-1 to 32-1-8 under WDM 17-1-1 can communicate at λ1 when connecting to OSU 12-1-1, at λ2 when connecting to OSU 12-1-2, at λ3 when connecting to ptp 13-1, and at λ4 when connecting to other destinations. In the example of Fig. 8, by directly connecting WDM 17-1-1 to ptp 13-1, one more terminal can be eliminated in optical space SW16. Note that the example of Fig. 8 is just one example, and the combination of direct connection to one-to-one connection destinations in each WDM 17 is not limited, and various combinations can be applied.

[0100] Furthermore, in the communication station system 10B of the third embodiment, some terminals of each WDM 18 on the optical space SW network 70 side may be directly connected to the SP15, thereby reducing the number of terminals in the spectral space SW16. For example, in WDM 18-1 of FIG. 8, one terminal is connected to SP15-1-1 instead of the optical space SW16. In the example of FIG. 8, by directly connecting WDM 18-1 to SP15-1-1, it is possible to further reduce one terminal in the optical space SW16. Note that the example of FIG. 8 is merely an example, and the combination of direct connections between each WDM 18 and SP15 is not limited, and various combinations can be applied.

[0101] (C-2) Effects of the Third Embodiment According to the third embodiment, in addition to the effects of the second embodiment, the following effects can be achieved.

[0102] As described above, in each communication station system 10B constituting the communication system 1B of the third embodiment, the number of terminals required in the optical space SW16 can be reduced compared to the second embodiment.

[0103] (D) Other embodiments The present invention is not limited to the above-described embodiments, and may include modified embodiments such as those exemplified below.

[0104] (D-1) In the communication systems of the above embodiments, the core station communication station system is arranged as a higher-level station of the regional station communication station system, but it may also be configured with only multiple regional station communication station systems (i.e., the core station communication station system may be excluded). [Explanation of symbols]

[0105] 1...communication system, 10, 10A, 10B...communication station system, 11...electrical SW, 12...OSU, 13...ptp, 14...OTU, 15...SP, 16...optical space SW, 17, 18...WDM, 31...SP, 32...ONU, 40...regional station DC, 50...core station DC, 70...optical space SW network

Claims

1. In a communication station system that connects multiple subscriber communication devices with multiple branched optical fibers, a plurality of station-side accommodating units that accommodate and communicate with the subscriber-side communication devices; an optical switch having a plurality of outside station terminals and a plurality of inside station terminals, and capable of switching an optical signal between any of the outside station terminals and the inside station terminals; An intra-office splitter is connected to each of the office-side accommodation units, which branches the subscriber-side terminals into a plurality of branches and connects them to the office-side terminals of the optical switch. A communication station system characterized by:

2. 2. The communication station system according to claim 1, wherein the intra-station splitter performs a one-to-multiple connection by branching a one-side terminal consisting of one optical terminal into a multi-side optical terminal consisting of a plurality of optical terminals, the one-side optical terminal being connected to the station-side accommodation unit, and the multi-side optical terminal being connected to the intra-station terminal of the optical switch.

3. 2. The communication station system according to claim 1, further comprising an electric switch for switching an electric signal, wherein at least each of the station-side accommodation units is connected to the electric switch.

4. 4. The communication station system according to claim 3, further comprising an optical wavelength multiplexer / demultiplexer connected to the branched optical fiber on the subscriber side to communicate with the plurality of subscriber side communication devices by wavelength division multiplexing, and connected to the external terminal of the optical switch on the station side.

5. 2. The communication station system according to claim 1, further comprising an optical communication network connection means for connecting the outside terminal of the optical switch to an optical communication network capable of communicating with other communication station systems.

6. The communication station system according to claim 4, further comprising a PTP transceiver that connects the inside terminal of the optical switch and the electrical switch in a one-to-one relationship and accommodates and communicates with the subscriber-side communication device operating in a one-to-one connection mode.

7. 6. The communication station system according to claim 5, further comprising other station connection means for connecting the inside terminal of the optical switch to an electrical switch that switches electrical signals on a one-to-one basis, and for connecting one-to-one with the other communication station system via the optical communication network.

8. 5. The communication station system according to claim 4, wherein a part of the terminals on the inside of the station of said optical wavelength multiplexer / demultiplexer is connected to said intra-station splitter.

9. 7. The communication station system according to claim 6, wherein a part of the PTP transmitter / receiver connects a terminal on the station side of the optical wavelength multiplexer / demultiplexer to the electrical switch in a one-to-one relationship.

10. A communication system comprising a plurality of communication station systems according to any one of claims 1 to 9.

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