Energy Minimization of M-Ary Orthogonal Signals in Communication Systems with Feedback

A communication system with a feedback channel which makes use of orthogonal M-ary signals is considered. The problem of its optimization, by setting a maximum time Tm to decide, is analyzed particularly so that the average energy per bit required to obtain a pre-fixed probability of error results as a minimum. The results, shown on graphs, allow one to evaluate the maximum decision time Tm and, afterwards, the maximum transmission rate.