A distortion optimal rate allocation algorithm for transmission of embedded bitstreams over noisy channels

We propose a distortion optimal rate allocation algorithm for robust transmission of embedded bitstreams over noisy channels. The algorithm is based on the backward application of a Viterbi-like algorithm to a search trellis, and can be applied to both scenarios of fixed and variable channel packet length problems, referred to as FPP and VPP, respectively. For the VPP, the complexity of the algorithm is comparable to the well-known dynamic programming approach of Chande and Farvardin. For the FPP, where no low-complexity algorithm is known, the complexity of the proposed algorithm is O([N.sup.2]), where N is the number of transmitted packets. Index Terms--Combined source/channel coding, distortion optimal rate allocation algorithm, embedded bitstreams, embedded coding, joint source/channel coding, progressively coded bitstreams, trellis, unequal error protection, Viterbi algorithm.