• Journal of the Korean Operations Research and Management Science Society
• /
• v.27 no.4
• /
• pp.1-10
• /
• 2002

The ring routing and wavelength assignment problem arose in the planning of optical communication networks which use WDM rings. Traffic demands are given for each pair of nodes in an ring : each demand must be routed one of the two possible connections round the ring and the wavelength assignments must be made so that there are no conflicts : that is. no two connections whose routes share a link can be assigned the same wavelength along that link. The objective is to minimize the number of used wavelengths. We propose the local optimal routing for the problem and show that there always exists an optimal solution satisfying it. Furthermore we suggest a new lower bound for the problem and show that it is very efficient for the worst case example.

• Proceedings of the Korean Operations and Management Science Society Conference
• /
• 2002.05a
• /
• pp.397-401
• /
• 2002

We consider a routing and wavelength assignment (RWA) problem on wavelength division multiplexing (WDM) ring networks, which is to maximize the established connections between nodes, given a set of usable wavelengths. We propose two new mathematical formulations of it and efficient algorithms based on branch-and-price method. Computational experiments on random instances show that cue of the proposed formulations yields optimal solutions in much shorter time on the average than the previous formulation due to Lee (1998).

• Journal of the Korean Operations Research and Management Science Society
• /
• v.32 no.4
• /
• pp.51-60
• /
• 2007

In this study, we consider the minimum ADM problem which is the fundamental problem for the cost-effective design of SONET ADM embedded in WDM ring networks. To minimize the number of SONET ADMs, efficient algorithms for the routing and wavelength assignment are needed. We propose a mathematical model based on the graph theory for the problem and propose a branch-and-price approach to solve the suggested model effectively within reasonable time. By exploiting the mathematical structure of ring networks, we developed polynomial time algorithms for column generation subroutine at branch-and-bound tree. In a computer simulation study, the suggested approach can find the optimal solution for sufficient size networks and shows better performance than the greedy heuristic method.

• Journal of the Korean Operations Research and Management Science Society
• /
• v.26 no.1
• /
• pp.33-44
• /
• 2001

In this paper, we address a problem of traffic grooming and wavelength routing in all optical WDM ring networks. Given a traffic demand for each node pair, we should aggregate the traffic onto lightpaths between pairs of nodes to transport the demand, and set up the routing path for each lightpath with minimum number of wavelengths to be assigned to lightpaths. In this paper, we formulate our problem as a mixed Integer Programming model. Owing to the problem complexity, it is hard to find an optimal solution for our problem. hence, we develop a heuristic algorithm to solve our problem efficiently. From the computational experiments, we can find the proposed heuristic is very satisfactory in both the computation time and the solution quality generated.

• Proceedings of the Korean Operations and Management Science Society Conference
• /
• 1999.04a
• /
• pp.190-190
• /
• 1999

• The Journal of Korean Institute of Communications and Information Sciences
• /
• v.24 no.6B
• /
• pp.1048-1058
• /
• 1999

This paper compares some architectures to achieve the optimized WDM architecture for all optical transport network, the comparison is presented in terms of the number of required wavelength and LT. These architecture types are PPWDM, SHWDM, DHWDM and fully optical WDM. Topology is a static ring network where the routing pattern is fixed and traffic pattern has uniform demand. This paper also proposes an algorithm for the wavelength assignment for a folly optical WDM ring network which has full mesh traffic pattern. The algorithm is based on heuristic algorithm which assigns traffic connections according to their respective shortest path. Traffic described here that is to be passed through can be routed directly within the optical layer instead of having the higher layer to handle it.

• Proceedings of the Korean Operations and Management Science Society Conference
• /
• 2003.05a
• /
• pp.734-740
• /
• 2003

링 루팅 및 파장할당 문제는 최근 활발하게 구축되는 있는 WDM 링의 설계 및 운용에 있어서 매우 중요한 문제이다. 이 문제는 링 상의 노드 쌍간에 단위수요가 주어졌을 때, 각 수요들을 링 상의 두 가지 가능한 경로 중 하나로 보내기 위한 광경로의 설정과 설정된 광경로에 파장을 할당하는 두 가지 의사결정을 동시에 결정하여야 하는 매우 복잡한 문제이다. 또한 파장할당시에 동일한 링크를 공유하는 광경로에는 동일한 파장을 할당할 수 없다는 제악이 있으면서, 목적함수는 할당하는 파장의 수를 죄소화하는 것이 된다. 본 연구에서는 링 루팅 및 파장할당 문제에 대매 평행루팅을 만족하는 최적해가 항상 존재한다는 것을 보이고, 최적해의 다양한 특성들을 규명하기로 한다. 또한 새로운 하한을 제시하고 이 하한이 기존의 하한에 비해서 매우 효과적임을 보이도록 한다.