Abstract: A novel cross-layer analytical model for multihop CDMA Ad hoc networks was proposed, which considers the effect of the physical layer, the MAC lay and the route layer on the performance of the networks. Firstly, the probability distribution was derived for the link distance between two randomly positioned nodes, and the probability distribution of the number of hop between the source node and the destination node based on MFR route strategy was also considered.Then, combining with adaptive modulation and coding, packet level QoS performance of the network was analyzed. Morcover, the end-to-end delay and throughput with retransmission mechanism were analyzed, and the effect of transmission range, the queue length and spread gain on the network performance was discussed. The proposed model considers the special MAC protocol and route strategy protocols;however, the approach can be extended to other MAC protocol and route strategy as well.

Key words: Ad hoc network, Cross-layer,Adaptive modulation and coding, QoS, Packet dropping probability, Delay,Throughput