Maximum-likelihood receivers for FFH/BFSK systems with multitone jamming over frequency-selective Rayleigh fading channels

In this paper, we have investigated the maximum-likelihood (ML) receivers for the fast frequency-hopped binary frequency-shift-keying (FFH/BFSK) spread-spectrum communications system with a worst case multitone jamming (MTJ) and additive white Gaussian noise (AWGN) over frequency-selective Rayleigh fading channels. Owing to the fact that the analysis of the natural logarithm of the modified Bessel function is intractable, two ML diversity-combining receivers, that are named as ML-A and ML-B receivers according to the different conditions of the approximation, have been analyzed theoretically based upon a correlated two-path frequency-selective channel model. The performance of these two receivers compared with that of other diversity-combining receivers in terms of the bit error rate (BER) has been scrutinized. Computer simulations confirm that our numerical analyses are valid. Furthermore, the ML-B receiver outperforms other receivers, while the ML-A receiver is only as good as the ML-B counterpart when the signal-to-jamming ratio (SJR) is greater than 24 dB.