An empirical study of asymmetry in low-power wireless links

Experimental studies of wireless sensor networks have shown that asymmetry in low-power wireless links has a significant effect on the performance of WSN protocols. Protocols that work well in simulation studies often fail when link asymmetry is encountered in real-world deployments. Thus, characterization of asymmetry is of importance for the design of resilient WSN protocols that will work in practice. The contribution of this article is twofold. First, it identifies some of the hardware and physical factors that can contribute to link asymmetry, and gives an experimental assessment of their relative importance. Second, it examines the impact of packet length and interpacket interval on protocol operation, and identifies possible interactions that also cause asymmetrical behavior.