Figure 1 shows that AODV_EXT consumes less power than the other four protocols. Most importantly the power consumption of AODV_EXT based network improves in comparison to that of standard AODV as the number of nodes in the network increases beyond 30. The two protocols perform equally in small size networks. DSR protocol based networks consumes more energy compared to AODV and AODV_EXT but shows better performance when the number of nodes in the network is small (up to 30 nodes). On the contrary, the power consumption in networks using DSDV and OLSR rises steadily starting from fairly high levels. With increasing number of nodes, the energy depletion of OLSR based networks increases faster than those for the other protocols. OLSR protocol uses a mechanism that constantly updates information about nodes in the neighbourhood and therefore consumes more energy. As the number of nodes in the network increases, more updates are required and hence proactive protocols perform poorly, especially when the network is subject to changes e.g. in mobile environment.