Design of an efficient medium access protocol for wireless networks using pipelining methods

Abstract

In this work, new techniques for cross layer design of wireless network has been proposed for improving the Quality of Service in wireless networks by considering the MAC and network layers. For this purpose, pipelining techniques have been used at the MAC layer that improves the channel utilization. In wireless MAC protocols, packet scheduling is carried out based on a channel allocation algorithm in which the channel is allotted based on the CSMA/CD algorithm. However, this algorithm is useful only for contention resolution. When the network traffic is increased, it is necessary to service many nodes at a time in order to send multiple packets at the same time. For this purpose, a parallel scheduling algorithm using pipelining has been proposed and implemented in this research work. In this algorithm, a MAC job is split into multiple stages and the execution of various stages is allowed to overlap using pipelining mechanism. In this thesis work, a novel proactive maintenance scheme is followed where a set of 1-hop neighbours called passive nodes around the path between source and destination are maintained. Moreover, the combinations of active and passive nodes maintain a mesh of optimal and sub-optimal paths where sub-optimal paths are backups and activated only when all optimal paths fail. This research work includes an ant based proactive route discovery to increase the connectivity between the nodes. In this ant based proactive route discovery, every node maintains a pheromone table and a probability routing table. Forward ants are used by the source to find the path to the destination and the optimal path is returned in the form of backward ants. In this way, route optimization techniques have been proposed in this thesis. The major contributions of this thesis are the proposal of an architectural frame work for cross layer design, pipelining at the MAC layer, and clustering and ant colony optimization at the network layer for improving the overall performance of the network. newline newline newline