Efficient layered video delivery over multicarrier systems using optimized embedded modulation
We tackle the problem of efficient image transmission over multi-carrier modulation (MCM) systems, proposing the use of a layered or multiresolution (MR) framework. In this work, 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 multi-carrier 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 bitrates 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.