Performance study of linear and nonlinear diversity-combining techniques in synchronous FFH/MA communication systems over fading channels

Based on the Fourier-Bessel series and exponential characteristic function approach, the paper presents analytical bit-error-rate expressions for synchronous fast frequency-hopped spread-spectrum multiple-access systems over Rician fading channels with M-ary frequency-shift-keying modulation. Linear-combining, product-combining and clipper receivers are studied. Numerical results show that both the clipper and product-combining receivers perform significantly better than the linear-combining receiver. The clipper receiver with an optimum threshold level slightly outperforms the product-combining receiver. However, the product-combining receiver is the preferred diversity-combining method because it is completely nonparametric. In addition, the optimum diversity levels for various diversity-combining receivers over Rayleigh fading channels are higher than that of the Rician fading channels