Symbol and Bit Error Rates Analysis of Hybrid PIM-CDMA

A hybrid pulse interval modulation code-division multiple-access (hPIM-CDMA) scheme employing the strict optical orthogonal code (SOCC) with unity and auto- and cross-correlation constraints for indoor optical wireless communications is proposed. In this paper, we analyse the symbol error rate (SER) and bit error rate (BER) of hPIM-CDMA. In the analysis, we consider multiple access interference (MAI), self-interference, and the hybrid nature of the hPIM-CDMA signal detection, which is based on the matched filter (MF). It is shown that the BER/SER performance can only be evaluated if the bit resolution conforms to the condition set by the number of consecutive false alarm pulses that might occur and be detected, so that one symbol being divided into two is unlikely to occur. Otherwise, the probability of SER and BER becomes extremely high and indeterminable. We show that for a large number of users, the BER improves when increasing the code weight. The results presented are compared with other modulation schemes.