Comparison of Parametric and Nonparametric Nonlinear Diversity Combining Schemes for Frequency-Hopping FSK Systems in Partial-Band Noise Jamming

Direct comparison is made of error probabilities achieved by several nonlinear diversity combining schemes for L-hop/bit FH/BFSK in worst-case partial-band noise jamming. The schemes studied for combining the L square-law envelope detector samples include adaptive gain control, majority logic combining of perhop hard decisions, a self-normalizing technique, and a method in which the samples are normalized by their maximum on each hop. The first method mentioned is "parametric", while the others are not. Both conventional and random hopping are considered, and thermal noise is included in the analysis. The results show that diversity improvement is realized for all the receiver combining schemes, provided that the thermal noise is relatively weak, not giving rise to substantial noncoherent combining losses. The hard decision scheme is shown to be most vulnerable to such losses.