Multiclass/multirate overlapped optical FFH-CDMA system: SIR performance evaluation and cutoff rates analysis

An optical CDMA network that supports multiple traffic classes is considered. Each class has different processing gain (PG) and performance requirements. In this paper, we generalize the method that we have previously proposed to analyze the cutoff rates for a single-class multirate optical frequency hopping code division multiple access system (OFFH-CDMA), to the case of multiclass multirate OFFH-CDMA system. This approach exploits the linear structure of passive optical CDMA systems and the nominal time required to accomplish the encoding-decoding operations in such systems. A system model is presented and analyzed based on a newly introduced bit-overlap procedure. An expression that relates the cutoff rates of the offered classes is introduced and it is termed the service curve. It is shown that for a required quality of service (QoS) guarantee, a number of active users, and a given probability of hit, the system´s data rates can be increased beyond the nominal limits imposed by the physical constraint of the encoder-decoder sets.