Multilevel quantized soft-limiting detector for an FH-SSMA system

A new multilevel quantized soft-limiting (SL-MQ) detector for frequency hopping spread spectrum multiple access (FH-SSMA) system is proposed and analyzed. Numerical and simulation results in both additive white Gaussian noise and frequency selective Rayleigh fading channels show that, as compared to the hard-limiting (HL) detector, the new SL-MQ with M = 4 can improve the system capacity by almost 10% at the bit error rate of 10⁻³. Furthermore, the performance of the SL-MQ is less sensitive to the optimum value of the amplitude threshold b. Hence, the SL-MQ can tolerate an inaccurate estimate of this optimum value in practice. A practical maximum output SNR criterion is also discussed, which can provide a sub-optimum b without knowing the system SNR and the number of interferers.