Abstract
Most ad hoc and sensor network research assumes idealized radio propagation models without considering fading and shadowing effects. Experimental results have shown that many well-designed protocols will fail simply because of fading and shadowing experienced in a realistic wireless environment. While fading and shadowing for radio propagation are well understood in wireless communication community, they are rarely studied in network level research for wireless sensor networks. This paper studies the fading and shadowing effects on the performance of different MAC protocols for wireless sensor networks. We show that fading and shadowing can have a significant influence on network performance. We study and compare network performance for three different systems: 1) a multi-channel CDMA system; 2) a pure CDMA system; 3) a contention based system. Through discrete event simulation (using ns-2), we show that the multi-channel CDMA system outperforms the pure CDMA system as well as the contention based system under fading and shadowing environments.