Abstract—We consider the problem of precomputing constrained widest paths and multicast trees in a communication network. Precomputing and storing of the relevant information minimizes the computational overhead required to determine an optimal path when a new connection request arrives. We evaluate algorithms that precompute paths with maximal bandwidth (widest paths), which in addition satisfy given end-to-end delay constraints. We analyze and compare both the worst case and average case performance of the algorithms. We also show how the precomputed paths can be used to provide computationally efficient solutions to the constrained widest multicast tree problem. In this problem, a multicast tree with maximal bandwidth (widest multicast tree) is sought, which in addition satisfies given end-to-end delay constraints for each path on the tree from the source to a multicast destination. Index Terms—Bottleneck paths, graph theory, multicast trees, precomputation, QoS routing, widest paths, widest trees. I.

As the technology of mobile ad hoc networks (MANETs) develops, many new kinds of applications in this field emerge. The group-oriented services which take advantage of the broadcasting nature of wireless networks are of much importance. Therefore, broadcasting/multicasting protocols in MANETs are receiving increased attention. Energy efficiency is a critical issue in MANETs and sensor networks where power of nodes is limited and difficult to recharge. This issue is crucial in the design of new routing protocols since each node acts not only as a host but also as a router. This project gives a general survey of broadcast/multicast routing protocols, network coding approaches and energy-efficient broadcast/multicast routing protocols in MANETs. In order to maximize network lifetime, we propose a new energy-efficient broadcast protocol, called EBOLSR, which adapts the EOLSR protocol to the broadcasting domain. And then we compare the performance of EBOLSR with three other broadcast protocols in two distinct MANET scenarios, Classical Flooding, Simplified Multicast Forwarding (SMF), and a coding-based broadcast protocol (CodeBCast). Simulation results show that EBOLSR protocol has less energy consumption and longer network lifetime than Classical Flooding, and also explain the reason why it does not outperform SMF in terms of the energy consumption and network lifetime.

Abstract. In this paper we consider several problems concerning packet routing in distributed systems. Each problem is formulated using terms from Graph Theory and for each problem we present efficient, novel, algorithmic techniques for computing optimal solutions. We address topics like: bottleneck paths (trees), optimal paths with non-linear costs, optimal paths with multiple optimization objectives, maintaining aggregate connectivity information under a sequence of network link failures, and several others.