A Mobile Ad-hoc'NETwork (MANET), also referred as Independent Basic Service Set (IBSS), has nodes which not only sendlreceive'packets associated with them but also co-operate in forwarding data and control packets for the network. Efficient use of energy by the mobile nodes is very important to increase the lifetime of MANET. Since nodes seldom have packets to receive, they remain in Idle mode for long periods of time which cause a lot of energy drain. Co-ordination algorithms reduce the time a node is in the Idle mode by keeping it in Sleep mode as much as possible while coordinators buffer packets for these sleeping nodes.For a given transmit energy, directional antenna has larger transmit range as compared to omni-directional antenna. This feature of directional antenna can be used in protocols which assumes a sparse network. We have chosen SPAN [I] to validate our above claim. SPAN is a protocol which elects a sparse network (i.e. backbone) of coordinators to buffer packets for sleeping nodes. Enhanced SPAN (E-SPAN) is the modified SPAN using directional antenna. Simulations prove the effectiveness of directional antenna and show that E-SPAN reduces average power consumed by the nodes in the network by about 20%.
展开▼
