Burst-by-burst adaptive joint detection CDMA

Adaptive quadrature amplitude modulation (AQAM) is combined with joint detection code division multiple access (JD-CDMA) in order to increase the throughput of a communications system, while maintaining a target BER. The QAM modes are adaptively switched, by estimating the signal to interference plus noise ratio (SINR) at the output of the joint detection receiver. For an eight-user AQAM/JD-CDMA scheme, a bits per symbol (BPS) performance of about 3.5 bits/symbol is achieved at an average SNR of about 18 dB, with a BER of approximately 0.02%, when using three different modulation modes, namely BPSK, 4-QAM and 16-QAM.