Abstract. Wireless and mobile communication networks are becoming more and more fashionable in today's mobile world. In wireless communications, Mobile Ad hoc Networks play crucial role. Ad hoc network is an infrastructureless and self -organized collection of autonomous nodes. In mobile ad hoc network, routing is one of the thrust areas. There are no committed routers in MANETs; every network node should contribute to routing. Simulation tools are used to analyze the performance of routing protocols in MANETs. Propagation models show strong impact on the performance of routing protocols during simulations. This paper investigates the impact of familiar propagation models Two-ray and Shadowing on the performance of AODV and DSR routing protocols using NS-2. Experimental results found that both AODV and DSR show better throughput in two-ray ground model.

The infrastructure-less and dynamic nature of mobile ad hoc networks demands a new set of networking strategies to improve the performance of quality of service (QoS). Providing QoS is a major issue in Manets. The traditional layered approach does not fit well for ad hoc networks due to high mobility and dynamic topology. This paper implements the cross layer design approach on DYMO routing protocol in Manets by using Qualnet simulator in both traditional layered approach and proposed cross layer approach. The proposed methodology uses four QoS metrics: throughput, end-to-end delay, packet delivery ratio and jitter. The experimental result reveals that QoS performance is enhanced in CLD approach for DYMO. The throughput in traditional layered approach for DYMO is 1961 b/s, whereas in the CLD approach it is 2986 b/s. Finally this paper concludes that cross layer approach significantly improves the QoS performance when compared with layered approach.