Energy Efficient Unicast Routing In Wireless Ad Hoc Networks

Wireless ad hoc networks are useful in situations where temporary communication is needed, such as in law enforcement or in disaster relief. So the ad hoc networks draw lots of attention in recent years. Most of the studies performed in the field of wireless ad hoc networks have focused on the problem of routing. Since most ad hoc mobile devices today operate on batteries, energy efficient routings have drawn considerable research interests recently.In fact, the wireless communications are unreliable and often unpredictable, and almost all of current data link layer protocols support the retransmission mechanism. However, existing energy-aware routing protocols ignore the energy consumption on the retransmission. In this thesis, we propose an AODV based energy-efficient routing algorithm REAODV. The main characteristic of REAODV is that it uses the total energy consumption, including the retransmission energy cost, as the metric when choosing routings. Extensive simulations are conducted to show that our new routing algorithm can indeed save more energy than original routing protocols in ad hoc networks.In many scenarios, design of energy-efficient protocols is guided by two essential requirements: minimizing the overall transmission power for each connection request and maximizing the lifetime of ad hoc mobile networks. We present a new energy-aware routing algorithm called Reliable Energy-Aware Routing Protocol (REARP) which can satisfy these two objectives simultaneously. Moreover, dynamic power control, which is realized by cross-layer optimization, is used in the algorithm to reduce the energy cost. Simulation results show that network lifetime of REARP is extended for random traffics while its total energy consumption is decreased.We are also focused on the routing problems for multiple requests with the aim of maximizing network lifetime. We show that this maximum lifetime routing problem is NP-complete, both for the general case and for the geometric one. We then develop a new maximum lifetime routing algorithm called DNLBR, which directly uses the node lifetime as cost metric. Moreover, we improve the algorithm to IDNLBR, which overcomes the large delay of DNLBR by integrating minimum-hop algorithm. To found the maximum lifetime routes for multiple requests networks, IDNLBR iteratively modifies the route by substituting long lifetime nodes for short lifetime nodes. By way of simulations, we compared our algorithms to existing protocols, and the results show that our algorithms are better at extending network lifetime. In order to evaluate and compare the energy-aware protocols in terms of their energy efficiency, an energy-consumption model which can accurately computes the energy consumed by the data communication activities is crucial. We give a comprehensive summary of the existing energy-consumption models, and the characteristics of each model are discussed in detail. We propose a new energy-consumption model which is based on the linear model. All nodes in the new model can change their RF power-rate and radio states according to the communication requirement, and their energy cost can be calculated correctly.