Coding and decoding for time-discrete amplitude-continuous memoryless channels

In this report we consider some aspects of the general problem of encoding and decoding for time-discrete, amplitude-continuous memoryless channels. The results can be summarized under three main headings. 1. Signal Space Structure: A scheme for constructing a discrete signal space, for which sequential encoding-decoding methods are possible for the general continuous memoryless channel, is described. We consider random code selection from a finite ensemble. The engineering advantage is that each code word is sequentially generated from a small number of basic waveforms. The effects of these signal-space constraints on the average probability of error, for different signal-power constraints, are also discussed. 2. Decoding Schemes: The application of sequential decoding to the continuous asymmetric channel is discussed. A new decoding scheme for convolutional codes, called successive decoding, is introduced. This new decoding scheme yields a bound on the average number of decoding computations for asymmetric channels that is tighter than has yet been obtained for sequential decoding. The corresponding probabilities of error of the two decoding schemes are also discussed. 3. Quantization at the Receiver: We consider the quantization at the receiver, and its effects on probability of error and receiver complexity. 1963 _ I___ _I __ _I__ I _ __ _ I