TWO-STATE CDMA RECEIVER FOR SHARED UPLINK SATELLITE CHANNEL

Most of future packet satellite systems are characterized by an high speed downlink channel broadcasted from the earth service gateway and a shared, low speed, return channel from each user equipment. In this paper a CDMA technique is proposed for return channel access mechanism. CDMA is interference limited rather than noise limited. The research for new methods to reduce interference and increase efficiency lead us to formulate a signaling method where fast impulsive silence states are mapped on zero-energy symbols. The theoretical formulation of the optimum receiver is reported and the probability of error for a generic linear CDMA receiver is derived. In particular, conventional and decorrelating two-states CDMA detector probability of errors are calculated. Numerical comparisons between two-states and traditional one-state CDMA conventional receivers are reported in the paper.