Improved Sequential Signaling and Decision Techniques for Nonbinary Block Codes

A situation is postulated whereby the goal is to maximize the average number of bits per second reliably communicated by nonbinary block codes over a channel whose conditions are slowly varying in a largely unpredictable fashion. A feedback channel limited to block retransmission requests is assumed. It is demonstrated that repetition usually is not the best signaling technique for sequential decision making under the postulated situation. Examples of improved sequential signaling techniques are given for multilevel amplitude modulation and multiple phase modulation.