Impact of timing jitter on the BER performance of an M-PPM free space optical link in presence of atmospheric turbulence

An analytical approach is presented to evaluate the impact of timing jitter on the Bit Error Rate (BER) performance of optical M-ary Pulse Position Modulation (M-PPM) Free Space Optical (FSO) link under the influence of atmospheric turbulence modelled by Log-normal distribution. The expression of the conditional BER for a given timing jitter is developed and the unconditional BER is found over the probability density function (pdf) of the timing jitter. The results are evaluated at a bit rate of 10 Gbps over weak turbulence for different M-PPM order. It is found that, there is a significant deterioration in BER performance with increase in timing jitter variance for a given M-PPM order. The system suffers penalty in receiver sensitivity at a given BER due to timing error. Further, it is noticed that higher order M-PPM system suffers less penalty than the lower order M-PPM system at a given bit rate and BER. The analysis may be useful for evaluating the impact of slot timing jitter for M-PPM FSO system with strong turbulence.