Evaluating Energy Consumption of Proactive and Reactive Routing Protocols in a MANET

Ad hoc routing technology has been developed primarily for networks of mobile nodes. The operational life of untethered nodes will be limited by its power source, so ad hoc networks strongly depend on the efficient use of their batteries. All the layers of communication are coupled in power consumption and solutions addressing the power saving issue include transmission power control, power aware routing and low power modes at the physical layer. At the network layer, routing protocols may balance power consumption at nodes according to their routing decisions. Several authors have proposed power aware routing algorithms based on power cost functions. In this work we present a performance comparison of the DSR (Dynamic Source Routing) and the OLSR (Optimized Link State Routing) in terms of energy consumption. We evaluate how the different approaches affect the energy usage of mobile devices. We found that a reactive protocol takes advantage of its routing policy when the traffic load is low. However, at higher traffic rates, a proactive routing protocol can perform better with an appropriate refresh parameter. In addition, we showed how, independently from the routing protocol selected, the overhearing activity can seriously affect the performance since all the neighbours of a transmitting node also consume their energy. To the best of our knowledge, this is the first simulation study addressing the power saving issue to extensively compare the DSR and OLSR protocols under a wide variety of network scenarios.