Impact of mobility on the BER performance of ad hoc wireless networks

In this paper, the authors quantify the impact of mobility on the bit error rate (BER) performance of ad hoc wireless networks. Analytical expressions, relating the BER at the end of a multihop route with the mobility characteristics of the nodes and the switching strategy, are derived on the basis of a rigorous detection-theoretic approach. In particular, two network switching scenarios are considered: 1) opportunistic nonreservation-based switching (ONRBS), where a message flows from source to destination by opportunistically choosing the available shortest consecutive links and 2) reservation-based switching (RBS), where, after the creation of a multihop route from source to destination, the message is "forced" to How over the reserved links, regardless of their actual lengths. The network performance is evaluated for both an ideal case (without interference) and a realistic case (with interference). The improved robustness against mobility offered by ONRBS, with respect to RBS, is analyzed and quantified. In particular, two node mobility models, known as direction-persistent (DP) and direction-non-persistent (DNP), are considered, and it is shown that DP mobility causes a much more profound degradation in the end-to-end route BER than DNP mobility. This conclusion is more pronounced in ad hoc wireless networks employing RBS. Overall, the results show that if the medium access control (MAC) protocol is not efficient in canceling or mitigating the interference, then the role of the switching/routing strategy in network performance is quite minor.