In this paper, the performance of four modulation schemes (OOK, PPM, DPPM and DPIM) popular in indoor
wireless optical communication systems are analyzed based on average transmitted power, bandwidth requirement and
packet error rate. The results show that each modulation scheme has its unique attractive features as well as its
challenges. In terms of average transmitted power, PPM achieves the smallest followed by DPIM and DPPM, OOK
achieves the biggest. With regard to bandwidth requirement, OOK achieves the smallest followed by DPPM and DPIM,
PPM achieves the biggest. Under the condition of the same number of bits per symbol, PPM achieves the smallest
followed by DPIM and DPPM, OOK achieves the biggest on the part of packet error rate. Furthermore, PPM requires
both slot and symbol synchronizations, while OOK, DPPM and DPIM require no symbol synchronization.