Impact of propagation loss and mobility on the performance of AODV & DSR in ad- hoc networks

Network simulation tools are commonly used to analyze the performance of Mobile Ad-hoc Networks (MANETS) protocols and their applications. The radio propagation models used for these simulations strongly influence the produced results. While the Two Ray Ground (TRG) model is the most widely used path loss model in reported MANETS performance analysis studies, it is not a realistic model for use in urban areas. In this study, we compare the performance of two widely used routing strategies for MANETS, i.e. Adhoc On-demand Distance Vector (AODV) and Dynamic Source Routing (DSR). Using the ns-2 simulator, a variety of mobility models are incorporated in the same scenario (e.g. two group movements and three random mobility patterns) to analyse the performance of an adhoc network with 100 nodes. Two new propagation loss models (i.e. Green-Obaidat Adhoc LoS model (GOALoS) and ITU-LoS in street canyons (ITU-LoS) were incorporated into ns-2 and the results from there were then compared with those produced using the TRG path loss model. The network performance was determined on the basis of Packet Delivery Ratio (PDR), Normalized Routing Load (NRL) and mean end-to-end delay with the effects of changing pause time. The results indicate that the PDR is better if the communication channel behaves like TRG model for AODV and DSR protocols with varying pause time. This study verifies that underestimating physical layer in MANETS may lead to more optimistic rather than realistic network performance.