Benefits of opportunistic routing, implicit acknowledgments, and network coding on a linear broadcast network

Abstract

This thesis studies the benefits of using opportunistic routing, implicit acknowledgments, and network coding on a linear broadcast packet network. Nodes are arranged in a line, and the first node wishes to communicate with the end node. When node i transmits, it is received at node j with a probability Pi,j . Several communication protocols are proposed and their performance studied using the mean and variance of the completion time as metrics. The protocols studied use end-to-end retransmission, end-to-end coding, and link-by-link retransmission with network coding both with and without opportunistic routing. Simulation and analytical results are presented. End-to-end coding significantly outperforms end-to-end retransmission on both metrics, and the link-by-link protocols outperform both. Opportunistic routing shows a mixed benefit over link-by-link protocols without it. When using opportunistic routing, the variance of the completion time is higher, and the mean is either similar or lower, depending on the channel conditions. When the loss probabilities are higher, opportunistic routing shows little benefit, whereas with a lower probability of packet loss, opportunistic routing shows a significant reduction in mean completion time.al Engineering and Computer Science.