Performance analysis of parallel combinatory hybrid pulse interval modulation optical code division multiple access systems

A parallel combinatory (PC)-hybrid pulse interval modulation-optical code division multiple access (hPIM-OCDMA) system is proposed. In the PC-hPIM-OCDMA system, a user chooses ε among K code sequences assigned to the user and sends ε2^b-ary PIM symbols for a given frame, where b is the number of bits per PIM symbol. The PC-hPIM-OCDMA system can offer higher bit rate than hPIM-OCDMA systems, and then it can reduce the effect of MAI, without reducing the bit rate. The bit error rate (BER) of PC-hPIM-OCDMA is derived, by considering that the dominant interference is MAI, which is caused by cross-correlation of strict optical orthogonal codes (SOOCs). Numerical results show that the PC-hPIM-OCDMA system can offer lower BER and accommodate more users than hPIM-OCDMA systems.