Commutation signaling—An antimultipath technique

Two types of commutation signaling for combating multipath are introduced: M × N signaling, in which the signal set cycles successively among N different sets of M signals each; and M + N signaling, in which the signal set at any time consists of M members of an alphabet of M + N signals, N of which are inactive at any epoch. In both cases, the objective is to remove from use any signal sent recently enough that it is still "ringing" in the multipath channel. We consider the problems of minimization of M and N, hence the total number signals used; analysis of 2 × N sets (M = 2 is almost uniformly optimal); analysis of the simplest M + N set, i.e., a 2 + 1 set; and presentation of the results of simulation of M × N and M + N signaling through realistic urban/suburban radio channels. Comparison of these simulations to simulations of other antimultipath techniques is also made. The simulation results are due to Kamil [3].