Optimal joint source-relay multi-resolution multicast networks

The paper studies the scenario of wireless multicast with a single transmitter and a relay that jointly deliver successively refined (or multi-resolution) sources to multiple receivers. By taking the end-to-end mean square error distortion (EED) as the performance metric, the problems of power allocation at the transmitter and relay are formulated. Due to nonlinearity of the formulations, a generalized programming algorithm is developed to obtain near optimal solutions. Case studies are conducted to verify the proposed formulations and solution approaches. The results show the advantages of using a relay assisted multiresolution approach.

I. Introduction

Joint source-channel coding (JSCC) pairs scalable source coding (SSC) and superposition channel coding (SPC) in wireless content delivery networks by mapping the source symbols to multiple successively refined channel symbols. The source symbols from a common source coding block of different resolutions are superimposed into one JSCC symbol for transmission, such that the receiver can recover up to a specific layer of source symbols according to channel quality [2]–[4].