Coding Improves the Throughput-Delay Tradeoff in Mobile Wireless Networks

Abstract

This paper studies the throughput-delay performance tradeoff in large-scale wireless ad hoc networks. It has been shown that the per source-destination pair throughput can be improved from Θ(1/√{ <i xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">n</i> log <i xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">n</i> }) to Θ(1) if nodes are allowed to move and a two-hop relay scheme is employed. The price paid for such a throughput improvement is large delay. Indeed, the delay scaling of the two-hop relay scheme is Θ( <i xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">n</i> log <i xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">n</i> ) under the random walk mobility model. In this paper, coding techniques are used to improve the throughput-delay tradeoff for mobile wireless networks. For the random walk mobility model, the delay is reduced from Θ( <i xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">n</i> log <i xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">n</i> ) to Θ( <i xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">n</i> ) by employing a maximum distance separable Reed-Solomon coding scheme. This coding approach maintains the diversity gained by mobility while decreasing the delay.