Performance of Uncoded Overlapping PPM Under Communication Constraints

摘要

In a direct-detection optical channel,overlapping pulse position modulation(OPPM)offers significant improvement in throughput over ordinary pulse position modulation(PPM)under bandwidth constraint.This improvement is acquired,however,at the expense of performance degradation.In this paper it is shown that under bandwidth and throughput constraints OPPM,with two pulse positions per pulsewidth,outperforms PPM when the overlap is chosen properly and the throughput is greater than 0.2 nats/slot.This enables us to increase the throughput and/or decrease the energy of the OPPM system,while maintaining the same performance as PPM.The energy saving when using OPPM instead of PPM to transmit reliably a given amount of information is determined for different values of overlapping indices.The maximum throughput that can be achieved under average power and bandwidth constraints (with error probability not exceeding 10-5)is also determined.