A Unified Metric for Correlated Diversity in Wireless Networks

Recent pioneer work has shown that packet receptions on adjacent links are correlated, which contradicts the long held assumption that wireless links are statistically independent. Since wireless link correlation affects a wide range of protocol designs, it is essential to quantify the impact generically. In particular, this paper focuses on a unified transmission cost metric for diversity-based routing schemes, including opportunistic routing, network coding, and hybrid routing. This paper covers both unicast and broadcast. Compared with the legacy metrics, our metric provides a direct and accurate estimation of the transmission cost in the presence of link correlation. The new metric helps a wide range of routing algorithms determine when they can benefit from reception diversity, and how to maximize the benefit, at negligible costs. We evaluate the metric on one 802.11 test bed and three 802.15.4 test beds running TelosB, MICAz, and GreenOrbs nodes. The experimental results show that our metric 1) reduces 92% and 94% of the estimation error of the transmission cost in unicast and broadcast and 2) outperforms the link independent metric in both unicast and broadcast applications.

I. Introduction

Given the broadcast nature of the wireless medium and the randomness of packet losses, packet reception diversity – a phenomenon in which packets from a node are received by multiple receiving nodes following different reception patterns, often exists. This phenomenon creates great opportunities for performance improvement. A radically new routing category, known as diversity based routing, including opportunistic routing [1], [2], network coding [3], [4], and hybrid routing [5]–[7], thus has been proposed to exploit the potential benefit brought by this diversity. Up to now, more than 1,000 research articles have been published under this category according to the ACM digital library.