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Energy management is the key issue in the design and operation of wireless network applications like sensor networks, pervasive computing and ubiquitous computing where the network is primarily driven by battery-powered embedded devices. This paper studies network coding as an energy minimization technique. Network coding reduces the energy consumption by minimizing the number of transmissions required to communicate a given amount of information across the network. However, aggressive application of network coding adversely affects the network lifetime. We illustrate this trade off in this paper, and show that the existing throughput based network coding approaches cannot be applied to energy-constrained networks. Specifically, we address the following routing problem. Given a set of traffic demands the goal is to route the demands across the network with the objective of minimizing the total energy consumption while providing guarantees on the lifetime of individual nodes. This paper studies multi-path variation of the above routing problem. We present analytical formulations to solve the problem optimally. Evaluation results indicate that the proposed solution is 35% more energy efficient than no-networkcoding solution while still meeting required lifetime constraints.

In this paper we propose a new efficient fault tolerant multipoint routing algorithm for optical networks. The routing for a multipoint request is accomplished by finding a bidirectional cycle simple or nonsimple including all nodes that are participating in the multipoint session. Each link can be used only once. Use of a cycle ensures that a single link (or node in case of simple cycle) failure does not interrupt the session except the failed node if it was part of the multipoint session. Determining the smallest cycle with a given set of Multi-point (MP) nodes is a NP-Complete problem. Therefore, we explore heuristic algorithms to determine an appropriate cycle to route multipoint connections. We allow non-simple cycles to route requests as they use fewer resources than simple cycles in some cases. We also provide an ILP formulation for routing multipoint request and compare its results with the output of our best heuristic algorithm. On Arpanet for over 80% of the time, our best heuristic is able to find a cycle that is within 1.2 times that of the optimal.

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