Performance of non-directed infrared CDMA

Expressions for the probability of bit error (p_e) for wireless infrared CDMA uplink transmissions in an office nanocell are presented as a function of the number of users in the presence of additive white Gaussian noise. The data modulation was on-off keying, and optical orthogonal codes (OOC) were used in the CDMA process. The choice of the length of the OOC, the number of 1s in the code and the detection threshold had a crucial effect on p_e. The analytical and simulation results were in close agreement. As an example of up-link performance, for 17 users, an SNR of 30 dB, an OOC code of 341 chips, having five logical 1s, a detection threshold parameter of the 4.2, the value of p_e was found to be 1.0×10^-4 in the absence of FEC coding