Adaptive Techniques For Performance Improvement Of Communication Systems For Coded Data

Abstract

The research in this thesis has been concerned with studying in-service error• monitoring techniques at a repeater and a receiver using line codes for digital transmission systems. Pattern violation detection (PVD) and digital sum variation (DSV) techniques have been applied at repeaters. On the other hand, illegal and disparity techniques have been applied at the receiver. Pattern violation detection (PVD) technique is based on detecting invalid code sequences (pattern violations) within the data stream, which correspond to the code symbols. By detecting these pattern violations, it is a straightforward matter to detect single errors in a received signal. The analysis of PVD technique has been introduced in the thesis, also the probabilities of detecting these patterns have been computed. DSV technique involves an extension of the idea of disparity of single symbol rather than a word. The technique has been evaluated through the computer simulation. The simulation has been considered with additive white Gaussian noise channel. The performance of the technique has been measured by calculating efficiency of error detection, detected violation rate, and injected error rate for most practical line codes at different values of signal to noise ratio. The optimum line codes, from the efficiency viewpoint, have been obtained