A POWER CONTROLLED MAC PROTOCOL WITH IMPROVED THROUGHPUT FOR AD HOC NETWORKS

Abstract

Most of the devices in wireless ad hoc networks t.,.se battery power as the energy source; it makes the energy consumption as an important issue for such networks. Though energy maintenance can be performed at each layer but in the past, most of the researchers have focussed on MAC (Medium Access Control) layer to minimize the energy consumption. The existing power controlled MAC protocols stress on reducing the energy consumption but they suffer with the disadvantage of throughput degradation of the network. In our dissertation, we have proposed a power controlled MAC protocol for wireless ad hoc networks that not only reduces the power consumption of each node in the network but also improves the throughput of the network. Our dissertation involves two phases of work. Initially our protocol minimizes the power consumption of each node by sending the RTS (request-to-send) packet with maximum power and CTS (clear-to-send), DATA (data), ACK (acknowledgement) packets with minimum necessary power (also called optimum power) to reach the packet at receiver. DATA packets are periodically sent with maximum power to avoid unnecessary collisions at the source node with ACK packets. And in next phase, to improve the throughput of network, the spatial reuse is increased by changing the virtual carrier sensing mechanism of IEEE 802.11 protocol. Our protocol solves the Hidden Node Problem by using RTS-CTS handshaking mechanism. Additionally, our protocol suggests a solution to the well known Exposed Node Problem. To improve the throughput by solving the Exposed Node Problem, we have made some modifications in virtual carrier sensing (VCS) scheme of IEEE 802.11 MAC protocol to allow more number of simultaneous transmissions. It increases the spatial reuse which, in turn, increases the throughput of the network.