A new transmitter-receiver architecture for noncoherent multirate OFFH-CDMA system with fixed optimal detection threshold

Analyzes a new transmitter-receiver architecture based on a modified version of unipolar-bipolar correlation proposed for a noncoherent multirate optical fast frequency hopping code-division multiple-access (OFFH-CDMA) system. The system assigns a frequency-shifted version (FSV) of the code used to transmit data bit "1" in order to transmit data bit "0." For the original system, we show that due to the nature of the multimedia network, the fluctuation in the multiple-access interference (MAI) average causes a threshold drift and thus an increase in the probability of error. This paper also provides a stochastic description of the MAI average amplitude fluctuation using a predefined multimedia probability density function. A system model is presented; in addition, the signal-to-interference ratio is derived. From the theoretical analysis and numerical results, it is shown that the proposed system has good performance without dynamic estimation of the detection threshold, and thus is independent of both the number of users and the distribution of those users in the offered multimedia classes.