Rateless codes have been shown to be able to provide greater flexibility andefficiency than fixed-rate codes for multicast applications. In the following,we optimize rateless codes for unequal error protection (UEP) for multimediamulticasting to a set of heterogeneous users. The proposed designs have theobjectives of providing either guaranteed or best-effort quality of service(QoS). A randomly interleaved rateless encoder is proposed whereby users onlyneed to decode symbols up to their own QoS level. The proposed coder isoptimized based on measured transmission properties of standardized raptorcodes over wireless channels. It is shown that a guaranteed QoS problemformulation can be transformed into a convex optimization problem, yielding aglobally optimal solution. Numerical results demonstrate that the proposedoptimized random interleaved UEP rateless coder's performance comparesfavorably with that of other recently proposed UEP rateless codes.
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