Comparison of improved OOK formats with pulse-position modulation in indoor unguided optical links at high bit rates

In this paper, on-off keying (OOK) formats with different pulse shapes and pulse-position modulation (4PPM) for indoor unguided optical links and different channel conditions are compared in terms of performance and required complexity, so as to minimize both intersymbol interference (ISI), induced by multipath propagation, and phase distortion effects, due to the interference suppression receiver filter. By means of a direct application of the correlation operator and the corresponding bit-error rate (BER) computation, we conclude that OOK format with Gaussian pulses and duty cycle lower than 50% provides quite good performances compared with the 4PPM scheme, frequently proposed in reported works but with major implementation complexity