1The Effect of Multipath Propagation on the Performance of DPIM on Diffuse Optical Wireless Communications

This paper investigates the performance of digital pulse interval modulation (DPIM) in the presence of multipath propagation and additive white Gaussian noise. The results for optical power requirements normalised to the average optical power required by the on-and-off keying (OOK) verses the channel normalised delay spread for DPIM without guard band and with guard bands are presented, and are compared with PPM and OOK. Results show that for a given order, DPIM with no guard band has a lower bandwidth requirement than PPM and OOK, and consequently has a lower ISI power penalty than PPM employing threshold detection. By introducing a guard band, the performance of DPIM in the presence of ISI can be improved considerably. 1