Multipulse Pulse-Position Modulation on Discrete Memoryless Channels
Jon Hamkins, Bruce E. Moision · 2005
We examine several properties of n-pulse M-slot multipulse pulse-position mod-ulation (MPPM) [6] on discrete memoryless channels (DMCs). First, we derive the maximum-likelihood decision rule and an exact expression for the symbol-error rate when n ≥ 1. This extends work on the Poisson channel which considered n = 1 [4], n = 2 [15], and which bounded the symbol-error rate for n ≥ 1 [3]. Next, we present an expression for the capacity of MPPM and show how to choose n ∈ {1, 2, · · ·} and M ∈ {2, 3, · · ·} to maximize capacity when average power, peak power, and bandwidth constraints are simultaneously imposed. The capacity of MPPM can be significantly higher, up to two times, than conventional pulse-position modulation (PPM) in a high average-power region for which the optimal M for conventional PPM is approximately 16 or lower. In lower average-power regions where the optimal M is higher, MPPM offers a negligible increase in capacity. I.