An Adaptive Method of Unequal Error Protection of Celp Parameters by Optimal Energy Distribution

Abstract

We propose an Unequal Error Protection (UEP) alternative to the Rate Compatible Punctured Convolutional (RCPC) Codes by optimally varying the bitlsymbol waveform energy, at transmission, as a function of its significance. In specific, the problem of robust transmission of Code Excited Linear Prediction (CELP) FS1016 (4.8 kbps) parameters over the Rayleigh and A WGN channels is considered. It is shown that the performance of Trellis Coded Modulation combined with unequal energy distribution is as effective in relative performance as an UEP scheme by RCPC. Thus we propose an UEP scheme suitable for bandwidth constrained systems and also for systems which require adaptation to varying channel conditions. The objective performance measures used are Segmental SNR (SSNR) and Average Distance (AD). Subjective tests are also performed to validate the performances ofthe system.