Optimized embedded multicarrier modulation for efficient delivery of layered video data
We tackle the problem of efficient image transmission over multicarrier modulation (MCM) systems, proposing the use of a layered or multiresolution (MR) framework. We treat the source as being characterized by multiple layers of importance, and therefore deserving of multiple levels of noise immunity, i.e, having different BER requirements. We present the idea of embedded multicarrier modulation (EMCM) as a very effective way of achieving this, and introduce a fast table-lookup based power allocation algorithm that optimizes the multicarrier constellation design in terms of maximizing the deliverable throughput bit rates for the different resolution layers, subject to a total power constraint. Simulation results of our EMCM system reveal substantial gains (up to about 25%) in deliverable bit rates over optimized TDM-based MCM designs. Further, in typical image transmission simulations using an embedded wavelet image coder, the EMCM approach yields almost 3 dB gains in delivered quality over conventional single-resolution MCM systems.