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Providing real-time voice support over multihop ad hoc wireless networks is a challenging task. To make a voice application feasible over ad hoc wireless networks, the perceived voice quality must be improved while not significantly increasing the packet overhead. We suggest packet-level media-dependent adaptive forward error correction (FEC) at the application layer in tandem with multipath transport for improving the voice quality. Since adaptive FEC masks packet losses in the network, at the medium access control (MAC) layer, we avoid retransmissions in order to reduce the control overhead and end-to-end delay. Further, we exploit the combined strengths of layered coding and multiple description (MD) coding for supporting error resilient voice communication in ad hoc wireless networks. We propose an efficient packetization scheme in which the important sub-stream of the voice stream is protected adaptively with FEC depending on the loss rate present in the network and is transmitted over two maximally node-disjoint paths. Our scheme achieves significant gains in terms of reduced frame loss rate, reduced control overhead, and minimum end-to-end delay and almost doubles the perceived voice quality compared to the existing approaches.
Date of Publication: Oct. 2008