Der-Rong Din

A hybrid method for solving ARWA problem on WDM network

Anycast refers to the transmission of data from a source node to (any) one member in the group of designed recipients in a network. In WDM network, the anycast requests can be used as an optimization tool to ensure survivability. If the anycast requests can be routed and delivered carefully, it is enough to find more free lightpath (or wavelengths) to other traffic (unicast or multicast). When the WDM network and the set of anycast requests are given, the anycast routing and wavelength assignment (ARWA) problem is to find a set of light-paths, one for each source, for anycasting messages to any one of the member in the anycast destination group such that not any path using the same wavelength passes through the same link. The goal of the ARWA problem is to minimize the number of used wavelengths. In this paper, the ARWA problem is formulated and studied; since ARWA problem is NP-hard, a hybrid method which combines simulated annealing and genetic algorithm technologies is proposed to solve it. In the proposed algorithm, the random routing method is used to generate the routing path from source to destination, heuristic algorithm is used to find the assigning wavelength of routing path. Nine types of perturbation schemes are proposed to generate the neighboring configuration, these perturbation schemes can avoid the proposed algorithm to trap into local optimum. Moreover, iterative improving technique is used to reduce the computing time for finding the new wavelength assignment. Simulated results show that the proposed algorithm can get better performance than other GA and heuristic algorithms.

Genetic algorithms for multiple multicast on WDM ring network

The optimal multiple multicast problem (OMMP) on wavelength division multiplexing ring networks without wavelength conversion is considered in this paper. When the physical network and the set of multicast requests are given, OMMP is the problem that selects a suitable path or (paths) and wavelength (or wavelengths) among the many possible choices for each multicast request under the constraint that not any paths using the same wavelength pass through the same link such that the number of used wavelengths is minimized. This problem can be proven to be NP-hard. In the paper, a formulation of OMMP is given and several genetic algorithms (GAs) are proposed to solve it. Experimental results indicate that the proposed GAs are robust for this problem.

A genetic algorithm for solving dual-homing cell assignment problem of the two-level wireless ATM network

In this paper, we investigate the optimal assignment problem, which assigns cells in Personal Communication Service to switches on Asynchronous Transfer Mode network in an optimum manner. The cost has two components: one is the cost of handoffs that involve two switches, and the other is the cost of cabling. This problem is model as dual-homing cell assignment problem, which is a complex integer programming problem. Since finding an optimal solution of this problem is NP-hard, a stochastic search method, based on a genetic approach, is proposed to solve this problem. In this paper, domain-dependent heuristics are encoded into crossover operations, mutations of genetic algorithm (GA) to solve this problem. Simulation results show that GA is robust for this problem.

A genetic algorithm for solving virtual topology configuration transition problem in WDM network

Wavelength-division multiplexing (WDM) technology has emerged as a promising technology for backbone networks. The set of all-optical communication channels (lightpaths) in the optical layer defines the virtual topology for the upper layer applications. Since the traffic demand of upper layer applications fluctuates from time to time, it is required to reconfigure the underlying virtual topology in the optical layer accordingly. However, the reconfiguration for the virtual topology is reluctantly disruptive to the network since some lightpaths should be torn down and some traffic has to be buffered or rerouted during the reconfiguration process. Therefore, it needs to have an efficient transition method to shift the current virtual topology to the new one so as to minimize the effect of the reconfiguration on the upper layer traffic. In this paper, the WDM virtual topology configuration transition problem (WVTCTP) which minimizes the average weighted hop distance is studied. Since the WVTCTP is NP-hard, a genetic algorithm (GA) is proposed to solve it. Simulated results show that the proposed GA can get better performance than heuristic, simulated annealing, and iterative improving methods.

Genetic algorithm for finding minimal cost light-forest of multicast routing on WDM networks

Wavelength division multiplexing (WDM) is an important technique to make use of the large amount of bandwidth in optical fibers to meet the bandwidth requirements of applications. Multicast is the transmission of information from one source to multiple destinations simultaneously. Given a multicast request in a WDM network, the goal is to find a set of light-trees, the assigned wavelengths of light-trees, and construct a light-forest. In this paper, the Minimal cost multicast routing problem (MCMRP) on WDM networks with Tap-and-continue nodes is defined and studied. A new cost model which consists of thewavelength usage and communication cost is defined. The objective is to minimize the sum of the cost of used wavelengths and the communication cost of the light-forest. Specifically, the formulation for the WDM multicast routing problem is given. Because the MCMRP is NP-hard, two genetic algorithms (GAs) are proposed to solve this problem. In the proposed GAs, a path-oriented encoding chromosome is used to represent the routing paths. These routing paths are used to construct source-based light-forests to represent a feasible solution to the multicast request. Moreover, to speed up the convergence of GAs, a Farthest-first greedy heuristic algorithm is proposed and used to generate one of the initial chromosomes. Simulation results demonstrate that the proposed GAs can run efficiently.

A genetic algorithm for solving virtual topology reconfiguration problem in survivable WDM networks with reconfiguration constraint

In wavelength division multiplexing (WDM) networks, the performance of the virtual topology designed for a pre-specified traffic pattern can be improved by performing virtual topology reconfiguration. Simultaneously, the provision of survivability of WDM networks is important, because the transmission of huge data should be protected when fiber fails. Thus, the combination of survivability and reconfiguration is an important issue on WDM networks. In this paper, the virtual topology reconfiguration problem (VTRP) in survivable WDM networks with reconfiguration constraint is studied. Given the physical topology, dedicated path-protection virtual topology and a new traffic demand matrix, the goal of VTRP is to reconfigure current virtual topology under the pre-specified reconfiguration constraint so that the objective cost can be minimized. The object cost of VTRP is the average weighted propagation delay (AWPD). Because designing a polynomial time algorithm to find the optimal solution of VTRP is impractical, in this paper, a genetic algorithm (GA) is proposed to solve this problem. Experiment results reveal that the objective cost can be decreased effectively by using the proposed genetic algorithm.

Genetic algorithm for finding minimal cost light forest of multicast routing on WDM networks

Wavelength division multiplexing (WDM) is an important technique to make use of the large amount of bandwidth in optical fibers to meet the bandwidth requirements of applications. Multicast is the transmission of information from one source to multiple destinations simultaneously. Given a multicast request in a WDM network, the goal is to find a set of light trees, the assigned wavelengths of light trees, and construct a light forest. In this paper, the minimal cost multicast routing problem (MCMRP) on WDM networks with tap-and-continue (TaC) nodes is defined and studied. A new cost model which consists of the wavelength usage and communication cost is defined. The objective is to minimize the sum of the cost of used wavelengths and the communication cost of the light forest. Specifically, the formulation for the WDM multicast routing problem is given. Because the MCMRP is NP-hard, two genetic algorithms (GAs) are proposed to solve this problem. In the proposed GAs, a path-oriented encoding chromosome is used to represent the routing paths. These routing paths are used to construct source-based light forests to represent a feasible solution to the multicast request. Moreover, to speed up the convergence of GAs, a farthest-first greedy heuristic algorithm is proposed and used to generate one of the initial chromosomes. Simulation results demonstrate that the proposed GAs can run efficiently.

Multicast protection problem on elastic optical networks using segment-base protection

In this paper, the multicast protection problem on elastic optical networks (EONs) for the single link-failure case is considered. Two segment-based protection algorithms are proposed to solve this problem, they are Low Spectrum First Segmented Protection Algorithm (LSF-SPA) and K-Tree Segmented Protection Algorithm (KT-SPA). The simulation results for static multicast requests show that the blocking ratio and resource utilization ratio of KT-SPA and LSF-SPA are better than the other conventional methods. The blocking ratio of KT-SPA is better than LSF-SPA.

Heuristic and Hybrid Methods for Solving Optimal Multiple Multicast Problem on WDM Ring Network

Abstract The Optimal Multiple Multicast Problem (OMMP) on wavelength division multiplexing (WDM) ring networks without wavelength conversion is considered in this paper. When the physical network and the set of multicast requests are given, OMMP is the problem that selects a suitable path (or paths) and wavelength (or wavelengths) among the many possible choices for each multicast request such that not any pair of paths using the same wavelength pass through the same link. In this paper, a formulation of OMMP is given; this problem is NP-hard since the famous RWA problem which has been proved NP-hard is a special case of OMMP. In this paper, the OMMP is divided into two subproblems: path routing and wavelength assignment subproblems. For each subproblem, two heuristic algorithms are proposed to solve it. Moreover, a hybrid method which combines heuristic and simulated annealing algorithm is proposed to find the near optimal solution. Experimental results indicate that these algorithms are efficient.

Genetic algorithm for virtual topology design on MLR WDM networks

For the mixed-line-rate (MLR) wavelength-division multiplexing (WDM) networks, each wavelength of fiber can provide different transmitting rates (in 10/40/100Gbps) by using different modulation types. Since the MLR-WDM is becoming the key and a cost-efficient technique for the network upgrading, the problem for constructing an efficient virtual topology becomes an important issue. In this paper, the Virtual Topology Design (VTD) problem on MLR-WDM network is considered. Given the physical backbone network and traffic demand matrix between nodes of the network, the goal of the VTD problem is to determine which node-pairs to be connected by establishing lightpaths, the actual routes of the lightpaths, the transmitting rates of lightpaths, and the assigned wavelengths of lightpaths such that the total cost of deployed transceivers can be minimized. Since the VTD problem on MLR-WDM network is a hard problem, in the paper, a heuristic algorithm (HA) and a genetic algorithm (GA) are proposed to solve it. Experimental results indicate that the proposed GA is robust for this problem.