Chapter 5 PERFORMANCE OF 802.11B/G IN THE INTERFERENCE LIMITED REGIME

One of the key advantages of mesh networks over cellular-based networks is that mesh nodes are relatively inexpensive. Hence, it is economically feasible to spread mesh nodes at a high enough density to provide high data rates to a dense user population. Speci cally, the high node density results is a short distance between receivers and transmitters, and hence high SNR channels and high bit-rates are possible. However, an important issue of high density networks is that transmissions are signi cantly impacted by interference. Thus, in low density networks, transmission errors are due to low SNR, while in high density networks, transmission errors are due to low SIR. The rst scenario is referred to as the noise limited regime and the second scenario is referred to as the interference limited regime. The behavior of 802.11 is well understood when transmissions are noise limited. However, performance in the interference limited case is considerably less well understood. This work explores 802.11b/g in the interference limited regime. The ndings presented here are the result of a large number of laboratory experiments. Thus, the channels between transmitters and receivers were controlled and all transmissions from external sources were eliminated with EMF shielding. The experiments lead to two key ndings. First, in the interference limited regime, the behavior of 802.11b/g is dominated by the ability of the receiver to synchronize