MAC considering energy efficiency and VBR traffic in wireless ad hoc networks

Abstract

A wireless ad hoc network consists of mobiles that self-configure to set up the network without the aid of any pre-deployed infrastructure. In this dissertation, we have studied medium access control (MAC) protocol for wireless ad hoc networks and proposed two MAC protocol, considering energy efficiency and variable bit rate (VBR) traffic. One is the energy-efficient MAC, which is based on scheduling and reservation for power saving. Energy efficiency is an important issue in wireless ad hoc networks because the battery power of a mobile is limited. When the offered data traffic is heavy, the proposed MAC protocol protects mobiles from collisions and subsequent retransmissions that cause the additive energy consumption of battery. We assign priority to low power (LP) mobiles to reduce the possibility that LP mobiles terminate their communications. We evaluate the performance of our proposed MAC with respect to the number of delayed slots, the channel utilization, and the energy efficiency. We derived the fair threshold energy level for the pseudo base station (PBS) reselection, which can increase communication time among mobiles. We showed that there is a need to set the smaller value of $E_{th}$ for the energy efficiency as the number of mobiles increases. The other is the Multi-Code (MC) MAC considering VBR traffic with delay bound. MC MAC is a sort of multiple channel MAC. The MC MAC which simultaneously allocates multiple data codes to the sender after the exchange of RTS/CTS/ACK messages through common code, enhances the previous multi-channel MACs. We develop the queueing model of MC MAC in single hop and multi-hop environments and analyze the effects of the number of data codes and the coverage area of radio signal in terms of throughput, access delay, and the dropping probability of VBR traffic. The performance of MC MAC is improved as the total bandwidth is divided into more data codes and the wider radio coverage makes the performance of MC MAC de...