JP2011065610A - Optical network design support system and program - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To support optical fiber connection design between multiple subscription applicant houses and a plurality of housing stations. <P>SOLUTION: An optical splitter arrangement design function (22) maps the subscription applicant to the nearest node V by referring to position information of the housing stations and the subscription applicants in a position information DB (18) and layable routes G(V, E) in a layable route information DB (21). A clustering processing function (24) classifies the node to which one or more subscription applicants are mapped into clusters, and determines the positions of optical splitters in each cluster under a subscriber number condition and a distance condition. A Voronoi area calculating function (28) divides the route G into Voronoi areas with housing station positions as kernel points. A housing station determining function (26) connects the optical splitters within the Voronoi areas to the housing stations of the same Voronoi areas. <P>COPYRIGHT: (C)2011,JPO&INPIT

Description

  The present invention relates to an optical network design support system and program for supporting the design of a PDS (Passive Double Star) type optical network.

  In a PDS type optical network, that is, a so-called PON (Passive Optical Network) network, when a large number of subscribers are allocated to a plurality of accommodation stations, the conventional technique has been relied on the manual work of skilled technicians. In Non-Patent Documents 1 and 2, it is assumed that PON subscribers' homes are uniformly distributed in a circular area centered on the accommodation station. A minimizing computer approach is described.

Daisuke Udagawa, Takao Matsumoto “Study on Minimum Optical Fiber Length of Multi-Stage Optical Access Network” IEICE General Conference, B-8-29, 2003 Daisuke Udagawa, Takao Matsumoto "Study on cost minimization conditions for multistage branch access network" IEICE General Conference, B-8-11, 2004

  Manual operation by a skilled engineer cannot confirm whether an optimal solution for cost or a preferable solution above a certain level has been obtained. Moreover, enormous effort and time are required for creation.

  The methods described in Non-Patent Documents 1 and 2 cannot be applied to cases where the subscribers' homes are not uniformly distributed, or where the shape of the area covered for each accommodation station is not circular. Moreover, this situation is more realistic.

  Further, the methods described in Non-Patent Documents 1 and 2 are based on the premise that an optical fiber cable can be laid freely in an area. However, in practice, it is necessary to lay the optical fiber cable along the road network or in a pipe prepared in advance, and the methods described in Non-Patent Documents 1 and 2 cannot be applied under such constraint conditions. .

  Therefore, the present invention is preferable with respect to the optical fiber cost in the case where there are restrictions on the layable route of the optical fiber cable on the assumption that a large number of subscribers' homes and a plurality of accommodating stations are unevenly distributed. An object is to present an optical network design support system and program for presenting a solution.

  An optical network design support system according to the present invention holds a location information database that holds location information of accommodation stations and subscribers, and route information that can be laid on an optical fiber and that is expressed by nodes and branches. A layable path information database, an allocating means for assigning the applicant to the nearest node on the plane, a parameter storage means for storing the maximum drop cable length, the number of optical splitter branches, and the initial number of clusters, and one or more Is an optical splitter position determining means for determining an optical splitter position from the nodes to which the subscribers of the mapping are mapped, and divides the nodes to which one or more subscribers are mapped into clusters equal to or greater than the initial number of clusters, The node position where the total path cost from the position of the node belonging to the cluster is minimized is the optical splitter position. Optical splitter position determining means determined as: and optical splitter / acquiring station connection means for connecting each optical splitter at each optical splitter position determined by the optical splitter position determining means to any of the receiving stations, An optical splitter / divider that divides the path represented by the path information into Voronoi areas having the accommodating station as a generating point, and connects the optical splitter at the optical splitter position to the accommodating station serving as the generating point in each Voronoi area And a toll station connecting means.

  An optical network design support program according to the present invention uses a computer to store a position information database that holds position information of accommodation stations and applicants for a plurality of collection stations and a plurality of subscribers, and an optical fiber. Referring to a layable path information database that holds layable path information and path information represented by nodes and branches, under the conditions of the maximum drop cable length and the number of optical splitter branches, the position of the optical splitter, and An optical network design support program for determining a receiving station for acquiring the optical splitter, wherein a function for assigning the subscriber to the nearest node on the plane and one or more subscribers are mapped to the computer An optical splitter position determining function for determining an optical splitter position from a node, wherein one or more addition Optical splitter position determination that divides the mapped nodes into clusters equal to or greater than the initial number of clusters, and determines the node position that minimizes the total path cost from the positions of the nodes belonging to each cluster as the optical splitter position Function and an optical splitter / acquisition station connection function that connects each optical splitter at each optical splitter position determined by the optical splitter position determination function to any of the acquisition stations, and is expressed by the path information Dividing the path into Voronoi regions with the receiving station as the base point, and realizing an optical splitter / acquiring station connection function that connects the optical splitter at the optical splitter position to the receiving station as the base point within each Voronoi region It is characterized by making it.

  According to the present invention, a PDS (Passive) that efficiently accommodates subscribers based on the location information of a large number of subscribers, the location information of a plurality of accommodation stations, and the information on the routes through which optical fibers can be laid. Even when a Double Star type optical fiber network can be designed, a plurality of applicants and a plurality of accommodating stations are non-uniformly distributed, and there are constraints on the route where the optical fiber cable can be laid, A design that gives a sub-optimal solution to the optical fiber cost becomes possible.

It is a schematic block diagram of one Example of this invention. It is a main flowchart of the network design process of a present Example. It is an explanatory example which shows distribution of an acquisition station and a subscription applicant. FIG. 4 is an example in which subscribers are mapped to nearby nodes in the example shown in FIG. 3. It is a detailed flowchart of a network clustering process. It is the example which determined the centroid in the example shown in FIG. It is an example of a connection of the optical cable which connects a centroid and a subscription applicant with respect to the example shown in FIG. It is a detailed flowchart of the process which determines the connection of an optical splitter and a accommodation station. It is an example of arrangement | positioning of the optical cable which connects an optical splitter and a collection station. This is a final design example for connecting the applicant and the accommodation station.

  Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings.

  FIG. 1 shows a schematic block diagram of a design support system according to the present invention. An input device 12 such as a keyboard and a display device 14 are connected to the CPU 10 of the computer. The design support program of this embodiment operates on the CPU 10. The parameter storage device 16 stores various parameters input by the input device 12 necessary for the design support program on the CPU. The parameter storage device 16 includes, for example, a RAM constituting the computer or a hard disk device as a secondary storage device.

The location information database (DB) 18 holds location information on a two-dimensional plane of PON subscribers and accommodation stations located in the design target area of the PON network. The location information of the accommodation station is C _i (i = 1 to N), and the location information of the applicant is X _j (j = 1 to M). In this example, it is assumed that there are N accommodation stations and the number of subscribers is M. C _i (i = 1 to N) indicates a case where each accommodation station is indicated and a case where the position coordinates are indicated. Similarly, X _j (j = 1 to M) may indicate the applicant who wants to subscribe, or may indicate the position coordinates thereof.

The maximum accommodated line number database (DB) 20 indicates the maximum accommodated line number Nf _i (i = 1 to N) of each accommodated station C _i (i = 1 to N). For example, the maximum number of accommodated lines of C ₁ is Nf ₁ .

  Instead of the databases 18 and 20, the database may include a collecting station database that holds the position information of the collecting station and the maximum number of lines to be collected, and a subscription applicant database that holds the position information about the applicant who wants to subscribe. It is clear that it is good.

The layable path information database (DB) 21 stores information on paths on which optical fibers can be laid, with nodes V _i (i = 1, 2,..., K ₁ ) and branches E _j (j = 1, 2,. K ₂ ) is held in the form of a graph G = (V, E). For example, when a road network is assumed as layable route information, the node V indicates the position of an intersection, and the branch E indicates a road connecting two intersections.

  The CPU 10 includes the following functions 22 to 30 as functional elements of the design support program. FIG. 2 shows a flowchart of the main flow of the design support program executed by the CPU 10.

The optical splitter arrangement design function 22 reads the location information C _i (i = 1 to N) of the accommodation station and the location information X _j (j = 1 to M) of the subscribers from the location information DB 18 (S1) and installs them. The path information G = (V, E) capable of laying the optical fiber is read from the possible path information DB 21 (S2).

In this explanation example, it is assumed that there are N accommodation stations, M subscribers, and there are K ₁ nodes and ₂ branches K in the route information G = (V, E). FIG. 3 shows an example of distribution of the applicants and the accommodation stations and the nodes and branches of the route. In the distribution example shown in FIG. 3, it is determined by examining which of the three receiving stations to which 16 subscribers should be connected. It is assumed that the node of the optical fiber layable path is a utility pole. In the example shown in FIG. 3, M = 17, N = 3, K ₁ = 12, and K ₂ = 27. Assume that each receiving station can accommodate one or more PON systems.

  The operator uses the input device 12 to input the basic parameters of the optical network design, here, the maximum drop cable length Lmax, the number of optical splitter branches Ns, and the number of clusters (initial value) Nc to the CPU 10 (S3). Of course, the input of these parameters (S3) may be performed prior to step S1 or S2. The maximum drop cable length Lmax is the maximum allowable distance from the optical splitter to the subscriber's home. The optical splitter branching number Ns is the number of subscribers who can be accommodated in one optical splitter. The number of clusters Nc is the number of PON systems, and here, since one optical splitter is assumed for one PON system, it is also the number of optical splitters. The number of clusters Nc may be increased or decreased during the calculation depending on the number of accommodation stations or the number of subscribers. In the example shown in FIG. 3, since the number of toll stations is 3, the initial value of the cluster number Nc is set to 3.

The optical splitter arrangement design function 22 associates each prospective subscriber _Xj with the closest node V _i on the plane (S4). FIG. 4 shows an example when the process of step S4 is applied to the example shown in FIG. In FIG. 4, the numbers given to the nodes indicate the number of applicants who are associated with the contact points.

  Next, the optical splitter arrangement design function 22 designates the entire area as a target area (S5), designates the number of clusters Nc, the applicant X and the layable route information G, and sends the network clustering function 24 to the network clustering function 24. The process is executed (S6). That is, at this point, the network clustering processing function 24 determines that the number of subscribers in each cluster is Ns or less and drops according to the conditions and initial values set in steps S1 to S3 and stored in the parameter storage device 16. Under the condition that the cable length does not exceed the maximum length Lmax, all subscribers in the target area are clustered to determine the position of the optical splitter candidate.

FIG. 5 shows a detailed operation flowchart of the clustering processing (S6) by the network clustering processing function 24. The network clustering processing function 24 is handed over from the main routine or the optical splitter arrangement design function 22 the target area, the number of clusters Nc, the subscriber (location information) X, and the layable route information G = (V, E). The network clustering processing function 24 randomly sets Nc centroids Y _k (k = _{1 to} Nc) as position candidates of the optical splitter from the nodes V of the layable route information G (S11).

  Of the nodes existing in the target area, the node to which one or more applicants are mapped is divided into Nc clusters by a predetermined clustering process (S12). Here, the positions of the Nc centroids are optimized or determined so that the sum of path costs (for example, road lengths) from the positions of the nodes belonging to each cluster is minimized. As such a cluster processing method, there is a graph clustering method, for example, Graph k-medoids clustering method. Each centroid determined by this clustering process is a position candidate for the optical splitter.

FIG. 6 shows the result of dividing the nodes into five clusters by the clustering process (S12) with respect to the example shown in FIGS. Black circles indicate centroid Y _k (light splitter candidate). In the example shown in FIG. 6, Ns (number of optical splitter branches) = 8 and Nc (number of clusters) = 5.

  For each cluster, the number of subscribers condition and the distance condition are examined. For this purpose, 1 is represented as a loop variable k for designating the target cluster (S13). For the k-th cluster, it is checked whether the number of applicants for subscription is Ns or less (S14), and whether the path length from each subscriber applicant to the centroid is Lmax or less (S15). When the number of subscribers is Ns or less and each path length is Lmax or less (S14, S15), it is checked whether k exceeds Nc (S16). If k is less than or equal to Nc, k is incremented (S17), and the subscriber number condition and distance condition are examined for the next cluster (S14, S15).

  The clustering processing function 24 executes network clustering processing (S18 to S20) for a cluster that is not satisfied by either the subscriber number condition (S14) or the distance condition (S15). That is, of the cluster, Nc = 2, and the optical fiber layable route G, the cluster processing function 24 is recursively using the part (Ga) in the cluster and the subscriber (Xa) located in the cluster as arguments. The network clustering process is executed (S20).

  In the flow shown in FIG. 5, a cluster that does not satisfy the subscriber number condition or the distance condition is divided into two so as to satisfy the subscriber number condition and the distance condition. When there is an unsatisfied cluster, the number of clusters Nc may be incremented, and retry may be performed from step S11. That is, in this case, if the subscriber condition or the distance condition is not satisfied, Nc is incremented and the process returns to step S11.

  By step S6, that is, according to the flow shown in FIG. 5, finally, a centroid satisfying the number of subscribers condition and the distance condition can be determined as the arrangement position of the optical splitter under the restriction of the optical fiber layable route. An example centroid determined for the example shown in FIG. 4 is shown in FIG.

  The centroid determined in this way is determined as the optical splitter position, and the subscriber who is mapped to the node in each cluster is logically connected to the optical splitter (S7). FIG. 7 shows a connection example in which the applicant and the optical splitter are connected by an optical cable to the example shown in FIG. This completes the design of the location of the optical splitter and drop cable.

  Note that graph clustering methods such as the Graph k-medoids clustering method method are known to converge to a local optimal solution. Therefore, the PON network design result obtained here is a suboptimal solution for the optical fiber line length. Become.

  The toll station determining function 26 determines to which toll station each optical splitter whose position has been determined in step S7 is connected (S8). FIG. 8 shows a detailed flowchart of step S8.

  The receiving station determination function 26 instructs the Voronoi area calculation function 28 to divide the path G = (V, E) where the optical fiber can be laid into network Voronoi areas using the positions of the N accommodation stations as a generating point ( S21). The network Voronoi region represents a set of nodes V whose shortest path length from a generating point is shorter than the path lengths from other generating points. What divided the whole of G = (V, E) into a plurality of Voronoi regions is called a network Voronoi diagram. FIG. 9 shows the result of dividing the Voronoi region into the example of arrangement of the receiving station and the optical splitter shown in FIG. 7, and the broken line shows the boundary line of the Voronoi region. As a method for drawing a network Voronoi diagram, M.M. A method proposed by Erwig is known.

The expropriation station determination function 26 executes the following processing for all of the obtained network Voronoi regions. First, a variable k designating a network Voronoi region to be processed is initialized with 1 (S22). The toll station determining function 26 obtains the maximum accommodated line number Nf _k of the _kth accommodated station from the maximum accommodated line number DB 20 (S23). It is determined whether the total of the number of optical splitters existing in the kth network Voronoi region and the number of lines already allocated to the _kth accommodation station is equal to or less than Nfk (S24). That is, it is examined whether or not a PON system equal to the number of optical splitters existing in the kth network Voronoi region can still be accommodated in the kth receiving station.

When the sum of the number of optical splitters existing in the kth network Voronoi region and the number of lines already allocated to the _kth accommodation station is Nfk or less (S24), each light existing in the kth network Voronoi region The splitter is connected to the kth accommodation station (S25). If k is not equal to Nc (S26), k is incremented (S27), and S23 and subsequent steps are repeated. If k is equal to Nc (S26), the process shown in FIG. 8 is terminated.

When the sum of the number of optical splitters existing in the kth network Voronoi region and the number of lines already allocated to the _kth accommodation station exceeds Nf _k (S24), it is no longer in the kth network Voronoi region. The all-optical splitter cannot be connected to the kth accommodation station. Therefore, the adjacent network Voronoi region j (where j ≠ k) is still free even if the total number of optical splitters in the network Voronoi region j and the number of optical splitters in the already connected adjacent region are added. It is checked whether or not there is one having an expropriation station (S28). That is, the possibility of connection to a collecting station in an adjacent network Voronoi area is examined. When there is no such adjacent network Voronoi region j (where j ≠ k) (S28), the toll station determination function 26 displays an error message indicating that the PON network cannot be designed on the display device 14 (S29).

When there is an adjacent network Voronoi region j (where j ≠ k) having a free acquisition station (S28), among the optical splitters in the kth network Voronoi region, the adjacent network Voronoi region j (where The optical splitter closest to the collecting station C _j with j ≠ k) is connected to the collecting station C _j (S30). Then, step S24 and subsequent steps are repeated. As a result, the number of optical splitters to be considered in step S24 is reduced by one. By repeating step S30 as many times as necessary, the condition of step S24 is finally satisfied, and the process proceeds to the next network Voronoi region processing as described above (S26, S27).

  In this way, the all-optical splitter arranged in step S7 can be connected to a collecting station as close as possible. This completes the design of the PON network as shown in FIG. FIG. 10 shows an example of a design result for the example shown in FIG. The design result output function 30 outputs the design result to the display device 14. Of course, the design result may be printed out and stored in a hard disk (not shown).

  By carrying out the above processing for all network Voronoi regions, it is possible to determine the accommodation station and the optical fiber laying path connecting each optical splitter as shown in FIG. 9, and complete the design of the PON network as shown in FIG. To do.

  In this embodiment, the position information of a large number of PON subscribers or the predicted number of PON subscribers predicted for each area, the position information of a plurality of PON accommodation stations, and the path through which optical fibers can be laid Based on the above information, it is possible to design a PDS (Passive Double Star) type optical fiber network that can efficiently accommodate the PON subscribers or the prospective future PON subscribers. It can be applied as an FTTH (Fiber To The Home) network design system for a telecommunications carrier developing a PON service. Specifically, when a plurality of PON subscribers already exist, the present invention can be applied as a PDS type optical fiber network design system that can efficiently accommodate the PON subscribers. Moreover, it can be applied as a design system when an optical splitter and an optical fiber cable between the accommodation station and the optical splitter are laid in advance based on a demand forecast for a future PON system.

  Although the invention has been described with reference to specific illustrative embodiments, various modifications and alterations may be made to the above-described embodiments without departing from the scope of the invention as defined in the claims. This is obvious to an engineer in the field to which the present invention belongs, and such changes and modifications are also included in the technical scope of the present invention.

10: CPU
12: input device 14: display device 16: parameter storage device 18: position information database 20: maximum number of accommodated lines database 21: layable path information database 22: optical splitter arrangement design function 24: clustering processing function 26: receiving station determination function 28: Voronoi area calculation function 30: Design result output function

Claims (8)

A location information database that holds location information of the containment station and applicants;
A layable path information database that holds path information that can be laid with optical fibers and that is represented by nodes and branches;
An assigning means for assigning the applicant to the nearest node on the plane;
Parameter storage means for storing the maximum drop cable length, the number of branches of the optical splitter, and the initial number of clusters;
An optical splitter position determining means for determining an optical splitter position from a node to which one or more subscribers are mapped, and divides the node to which one or more subscribers are mapped into clusters equal to or greater than the initial number of clusters. Optical splitter position determining means for determining, as the optical splitter position, the node position at which the sum of path costs from the position of the nodes belonging to each cluster is minimized,
Optical splitter / acquisition station connection means for connecting each optical splitter at each optical splitter position determined by the optical splitter position determination means to any of the acquisition stations, and the path expressed by the path information And dividing the Voronoi area with the accommodating station as a generating point, and providing an optical splitter / acquiring station connecting means for connecting the optical splitter at the position of the optical splitter to the accommodating station as the generating point within each Voronoi area. A featured optical network design support system. The optical splitter position determining means is
Of the nodes of the route information, a centroid corresponding to the initial value of the number of clusters is randomly set, and a node to which one or more applicants are assigned corresponds to the initial value of the number of clusters. Dividing means for dividing the cluster into a number of clusters and optimizing the centroid;
For each cluster generated by the dividing means, the number of subscribers in the cluster is equal to or less than the number of optical splitter branches, and the join in the same cluster from the position of the centroid in each cluster. A discriminating means for discriminating whether or not a distance condition that a route length to the applicant is equal to or less than the maximum drop cable length is satisfied;
Recursion means for executing the dividing means and the determining means in the cluster for a cluster that does not satisfy at least one of the subscriber number condition and the distance condition;
2. The light according to claim 1, further comprising means for setting the position of the centroid of the cluster determined to satisfy the number of subscribers condition and the distance condition by the determining means as the optical splitter position. Network design support system. The optical splitter position determining means is
Of the nodes of the route information, a centroid corresponding to the initial value of the number of clusters is randomly set, and a node to which one or more applicants are assigned corresponds to the initial value of the number of clusters. Dividing means for dividing the cluster into a number of clusters and optimizing the centroid;
For each cluster generated by the dividing means, the number of subscribers in the cluster is equal to or less than the number of optical splitter branches, and the join in the same cluster from the position of the centroid in each cluster. A discriminating means for discriminating whether or not a distance condition that a route length to the applicant is equal to or less than the maximum drop cable length is satisfied;
Means for increasing the cluster number initial value and re-executing the dividing unit and the determining unit when there is a cluster that does not satisfy at least one of the subscriber number condition and the distance condition;
The optical network according to claim 1, further comprising means for setting the position of the centroid of each cluster as the optical splitter position when all the clusters satisfy the first condition and the second condition. Design support system.   The optical splitter / acquisition station connection means is a means for examining whether connection is possible with an acquisition station in an adjacent Voronoi area when there is no vacancy for connecting the optical splitter in the same Voronoi area to the acquisition station in each Voronoi area. The optical network design support system according to any one of claims 1 to 3, further comprising: Using a computer, a location information database that holds the location information of the accommodation station and the applicants for a plurality of acquisition stations and a plurality of subscribers, and route information that can be laid with optical fibers, including nodes and branches Referring to the layable path information database that holds the path information expressed by the above, determine the position of the optical splitter and the receiving station that will receive the optical splitter under the conditions of the maximum drop cable length and the number of optical splitter branches An optical network design support program comprising the computer
A function for assigning the applicant to the nearest node on the plane;
An optical splitter position determination function for determining an optical splitter position from a node to which one or more subscribers are mapped, and divides the node to which one or more subscribers are mapped into clusters equal to or greater than the initial number of clusters. An optical splitter position determination function for determining, as the optical splitter position, a node position at which the sum of path costs from the positions of the nodes belonging to each cluster is minimized;
An optical splitter / acquisition station connection function for connecting each optical splitter at each optical splitter position determined by the optical splitter position determination function to any of the acquisition stations, and a path expressed by the path information An optical splitter / acquisition station connection function that divides a receiving station into a Voronoi area having a base point and connects the optical splitter at the position of the optical splitter to the receiving station as a base point in each Voronoi area is realized. A featured optical network design support program. The optical splitter position determination function
A random number of centroids corresponding to the initial value of the number of clusters is randomly set from the nodes of the route information on the computer, and a node assigned with one or more applicants is initially set to the initial number of clusters. A division function for dividing the cluster into a number of clusters corresponding to the value and optimizing the centroid;
The same number of subscribers in the cluster is equal to or less than the number of optical splitter branches for each cluster generated by the division function, and the same centroid position in each cluster. A discriminating function for discriminating whether or not a distance condition in which the path length to the subscriber requesting in the cluster is less than or equal to the maximum drop cable length is satisfied
A function for causing the computer to execute the division function and the discrimination function in the cluster for a cluster that does not satisfy at least one of the subscriber number condition and the distance condition;
6. The computer according to claim 5, further comprising means for causing the position of the centroid of the cluster determined to satisfy the subscriber number condition and the distance condition by the determination function to be the optical splitter position. Optical network design support program described in 1. The optical splitter position determination function
A random number of centroids corresponding to the initial value of the number of clusters is randomly set from the nodes of the route information on the computer, and a node assigned with one or more applicants is initially set to the initial number of clusters. A division function for dividing the cluster into a number of clusters corresponding to the value and optimizing the centroid;
The same number of subscribers in the cluster is equal to or less than the number of optical splitter branches for each cluster generated by the division function, and the same centroid position in each cluster. A discriminating function for discriminating whether or not a distance condition in which the path length to the subscriber requesting in the cluster is less than or equal to the maximum drop cable length is satisfied
A function that increases the initial number of clusters and re-executes the division function and the determination function when a cluster that does not satisfy at least one of the subscriber number condition and the distance condition exists in the computer;
6. The computer according to claim 5, further comprising a function of causing the position of the centroid of each cluster to be the optical splitter position when all the clusters satisfy the first condition and the second condition. The described optical network design support program.   The optical splitter / acquisition station connection function can connect to the acquisition station of the adjacent Voronoi area when the computer does not have a space to connect the optical splitter in the same Voronoi area to the acquisition station in each Voronoi area The optical network design support program according to any one of claims 5 to 7, further comprising a function of checking whether or not the optical network is designed.

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