Optimal placement of uncoded memoryless regenerators for OOK signaling

We study the problem of relay design and placement for On-Off Keying signals. We assume that the relay is memoryless and consider both, coherent and non-coherent devices. We derive the optimal coherent relay and compare its performance and placement to those of a coherent hard-limiter and a non-coherent one. Overall we note that the use of a coherent hard-limiter is near optimal, especially after placement optimization, and its performance degradation is mainly due to the energy-inefficiency of OOK signals.