METHOD AND APPARATUS FOR INCREASING SPECTRAL EFFICIENCY OF CDMA SYSTEMS USING DIRECT SEQUENCE SPREAD SPECTRUM SIGNALS

摘要

Modulator and demodulator for spread spectrum systems. They can process two data channels at nominal rate or one high speed channel demultiplexed in two. In the modulator one PN sequence generator (306) generates two PN sequences provided to a switch (308). Each channel is demultiplexed (304), one output controls which PN sequence is provided by the switch, the other is modulo-2 added (310) to the chosen PN sequence. The demodulator includes a PN generator providing replicas of the two PN sequences. Each subchannel is multiplied by one of the PN sequences. A decision circuit chooses the subchannel with the largest integrator result magnitude and provides a control signal to a multiplexor. A switch outputs data bit from subchannel chosen. The multiplexor combines the switch output and the control signal.