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Cross-Layer Design of AODV Protocol for Multi-Hop Flow in Ad Hoc Network
So-Tsung Chou, Hann-Tzong Chern, Cheng-Mu Shiao and Zne-Jung Lee

In a multi-hop ad hoc network, nodes contend for shared wireless channel with neighbors. The contention results in congestion and greatly degrades the performance of a network due to severe packet collisions. Several papers have shown that the performance of multi-hop ad hoc network is poor and the IEEE 802.11 scheme fails to achieve optimum scheduling for medium access contention. In this paper, we present a multi-hop packet scheduling framework to achieve high throughput, good packet delivery ratio, low routing load, and small link-failure probability in ad hoc environment. The routing information about the total hop count and the remaining hop count, required by a packet to reach its destination, is exploited by this scheme in the MAC layer to recalculate the contention window size of the nodes along routing path and to give priorities for the packets that are closer to their destination. Extensive simulations show that the proposed scheme is able to earn significant improvement over the conventional algorithm.

Keywords: ad hoc network, contention window, receiver blocking, intra-flow contention, frame cost of source, frame cost of destination, link failure probability.

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