• Journal of Korean Institute of Industrial Engineers
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• v.30 no.3
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• pp.213-223
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• 2004

We consider the traffic grooming problem for the design of SONET/WDM(Synchronous Optical NETwork/Wavelength Division Multiplexing) ring networks. Given a physical network with ring topology and a set of traffic demands between pairs of nodes, we are to obtain a stack of rings with the objective of minimizing the number of ADMs installed at the nodes. This problem arises when a single ring capacity is not large enough to accommodate all the demands. As a solution method, an efficient algorithm based on the branch-and-price approach has been reported in the literature for the problem in which only unidirecional path switched ring (UPSR) was considered. In this study, we suggest integer programming models and the algorithms based on the same approach as the above one, considering two-fiber bidirectional line switched ring(BLSR/2), and BLSR/4 additionally. Using the results, we compare the number of required ADMs for all types of the ring architecture.

• Proceedings of the IEEK Conference
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• 1999.06a
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• pp.172-175
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• 1999

In this paper, we propose new algorithm to minimize the total cost of overall system in WDM ring networks. The cost of system includes the number of SONET ADMs as well as the number of wavelength. As optical technologies and WDM components are developed, the dominant cost of system is the number of SONET ADMs which is electronic equipment. To reduce the number of SONET ADMs in nonuniform traffic, we propose two algorithms one is the algorithm to construct full circles as many as possible to minimize gaps by cutting and combining the connections. The other is the algorithm to groom circles Into a wavelength to share the maximum number of nodes. The simulation results show that the proposed algorithm is superior to conventional algorithm in nonuniform traffic

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

• The Journal of Korean Institute of Communications and Information Sciences
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• v.25 no.5B
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• pp.956-965
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• 2000

In this paper, we propose an efficient traffic grooming algorithm to minimize to number of SONET ADMs which is the dominant cost of system in high speed optical ring networks. It is an optimal traffic grooming algorithm to be applied to both unidirectional ring and bi-directional ring under both uniform traffic and nonuniform traffic. The proposed traffic grooming algorithm consists of two subalgorithms : one is the algorithm to construct full connection-rings as many as possible to minimize gaps by cutting the connections and using redirection method, and the other is the algorithm to groom connection-rings into a wavelength to maximize the number of shared nodes. The simulation results show that the proposed algorithm is superior to conventional algorithm under various network conditions.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.25 no.8A
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• pp.1247-1253
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• 2000

To fully utilize the capabilities of a SONET/ADM network, traffic grooming is needed to multiplex a number of lower-rate traffic streams into a higher-rate stream, and vice versa. Although the capacity of a SONET ring network can be upgraded by operating it over multiple wavelengths, the corresponding network design may be costly if it employs a large number of ADMs. A cost-effective design attempts to minimize the total number of ADMs used in the network while carrying the offered traffic. We introduce and evaluate the performance characteristics of a new traffic-grooming approach for WDM ring networks, called multihop. The multihop implementation places an ADM at each node based on the requested traffic in the traffic-demand matrix then, it tries to groom the wavelengths which can be groomed. We select one of the nodes to be the "hub" node which has an ADM for each wavelength. The hub node, therefore, can "bridge" traffic between all of the wavelengths. The algorithm is specified and illustrated by a simple example. Our results demonstrate that it is beneficial to use a single-hop approach, but for a large grooming ratio and node number, we advocate the use of the multihop approach.e multihop approach.