DPCM ENCODING OF REGENERATIVE COMPOSITE PROCESSES

Fixed (nonadaptive) and forward adaptive differential pulse code modul ation of regenerative composite sources is investigated. In the fixed code, an approximate formula is given for the optimal value of the pre diction coefficient. This is then used as an initial guess to optimize the code (predictor and quantizer) through a numerical method. In the forward adaptive scheme, the state of the switch in the composite sou rce is estimated using a MAP sequence estimation algorithm, and the co de is then matched to the mode process corresponding to the estimated switch state. The performance of the two systems is evaluated with qua ntizers of 4, 8, and 16 levels. The results show that the forward adap tive scheme significantly outperforms optimized fixed DPCM in the sens e of mean-squared error. Stochastic stability of the code is also esta blished for the fixed DPCM scheme as well as for an adaptive scheme wh ich receives the switch state as side information.