LOW-DELAY COMMUNICATION FOR RAYLEIGH FADING CHANNELS - AN APPLICATIONOF THE MULTIPLE DESCRIPTION QUANTIZER

We show the multiple description scalar quantizer (MDSQ) [1], when use d over a slow fading Rayleigh channel, results in a smaller interleavi ng delay than traditional channel code-based approaches and substantia lly outperforms a system using a maximum ratio combiner. We consider a continuous alphabet source without memory over a slow Rayleigh fading channel. Specifically, it is initially assumed the Rayleigh parameter remains constant over a specific time interval and the demodulator ha s available perfect estimates of the Rayleigh parameter. An analysis o f the problem is presented and theoretical justification is provided f or using the MDSQ. For a Gaussian source without memory, performance c omparisons are presented against a traditional maximum ratio combiner (MRC)-based system as well as against channel code-based systems. It i s shown that the performance of the MDSQ-based system dominates the MR C-based system at all channel signal-to-noise ratios and is superior t o channel code-based systems when the interleaving delay is constraine d. Simulation results for a mobile radio channel model at 15 mph indic ate a reduction in the interleaving delay by at least a factor of thre e.