Ashraf M. Hamad

A survey of multicasting protocols for broadcast-and-select single-hop networks

Multicast communication in single-hop broadcast-and-select wavelength-division multiplexing networks has received considerable attention from researchers. This article presents a comprehensive survey of the multicast scheduling techniques in this environment. It considers different challenges that are faced in the design of the multicasting techniques and presents a classification of such schemes. A survey of specific techniques is then presented and a comparison is drawn between such techniques.

On multicasting in wavelength-routing mesh networks

This paper considers multicasting on wavelength-routing mesh optical networks. Although multicasting has been studied extensively in different network environments, multicasting in this environment is different, and more involved. The paper discusses the challenges of multicast support in optical wavelength routing networks, and reports on the advances made so far in this venue. The paper introduces a classification and a comparison of such techniques, and a study of their advantages and disadvantages.

Routing and wavelength assignment with power aware multicasting in WDM networks

In this paper, we study the routing and wavelength assignment (RWA) problem of a set of multicast sessions on already dimensioned wavelength routed network, while taking optical power impairments into consideration. Our main objective is to minimize the session blocking probability. We formulate the problem as a mixed-integer linear program (MILP). A greedy algorithm is also introduced, which provides fast, yet efficient, solutions for large problem sizes. The CPLEX linear optimization package is used to solve the MILP formulation, while simulation was used to experiment with the greedy algorithm.

Optimal power-aware design of all-optical multicasting in wavelength routed networks

Power loss encountered by the optical signal in the light-trees can be due to attenuation, signal splitting, or both. Optical amplifiers may have to be used in order to recover from the power loss so that the optical signal can still be detected at the receivers. Due to the high cost of optical amplifiers, we introduce an optimal power-aware design of wavelength-routed optical networks supporting multicast traffic. The network design problem is formulated as a mixed-integer linear programming, and the main objective is to minimize the total required gain in the network while allowing unequally powered signals. It also determines the optimal number and placement of the splitters, and the routing and wavelength assignment for the multicast sessions. We used the CPLEX linear optimization package in order to solve the MILP formulation. Then, the number and location of optical amplifiers per link is computed off-line.

Optical Amplifiers Placement in WDM Mesh Networks for Optical Multicasting Service Support

The problem of placing optical amplifiers (OAs) in wavelength-routing mesh networks has been studied in the literature in two contexts: network provisioning and connections provisioning. In this paper, we introduce optimal and heuristic solutions for the network provisioning problem. The solution is based on constructing a multicast forest for each multicast connection with the goal of minimizing the total number of OAs needed in the network, hence reducing its cost. The optimal solution is formulated as a mixed integer linear program (MILP). On the other hand, the heuristic solution is obtained by dividing the problem into subproblems and solving them separately while taking the interdependency between these subproblems into consideration. The results obtained from both solutions are compared and they are found to be a good match.

Power-Aware Connection Provisioning for All-Optical Multicast Traffic in WDM Networks

The connection provisioning problem attempts to achieve its objective of guaranteeing the maximum throughput and minimal blocking probability. In optical networks, this problem is mainly the classical routing and wavelength assignment (RWA) problem, which includes many constraints. In this study, we investigate the RWA problem for connection provisioning under multicast traffic while considering the optical power constraints. The problem is first formulated as a mixed-integer linear program (MILP) with the objective of minimizing the session blocking rate. In order to provide fast and efficient solutions, the paper introduces a novel heuristic solution that divides the problem into subproblems and solves them separately, while still taking the interdependency between them into account. The results obtained from both solutions are found to be closely comparable. The results obtained from the heuristic also provide insight for the network operators about the maximum performance enhancement that can be achieved by upgrading the network capacity.

Efficient Power-Aware Network Provisioning for All-Optical Multicasting in WDM Mesh Networks

Optimal network provisioning is the process of equipping the network with the devices and resources needed to support all traffic demands while minimizing the network cost. Optical amplifiers (OAs) are one of those devices that contribute significantly to the network cost, especially in wide area networks. We propose a heuristic approach for placing the minimum number of OAs in the network. The solution is designed for all-optical multicasting and is based on dividing the problem into smaller subproblems. While solving them separately, the heuristic takes the interdependency between these subproblems into consideration. Therefore, efficient and accurate solutions can be obtained which is shown by the numerical results.