Iterative source-channel decoding with cross-layer support for wireless VoIP

This paper presents a cross-layer approach for iterative source-channel decoding (ISCD) in wireless VoIP networks. The novelty of the proposed method is the incorporation of both, speech bits as well as protocol header bits, into the ISCD process. The header bits take the role of pilot bits having perfect reliability. These bits are distributed over the frame as strong supporting points for the MAP decoder which. results in a significant enhancement of the output speech quality compared to the benchmark scheme using ISCD for speech only. For this approach, we exploit cross-layer concepts that support the direct communication between non-adjacent layers. These concepts enable the iterative exchange of extrinsic information between the source decoder located on the application layer and the channel decoder located on the physical layer. This technique can also be applied to audio and video transmission.