Narrowband Interference Suppression in Frequency-Hopping Spread Spectrum Using Undecimated Wavelet Packet Transform

Suppression of narrowband interference in frequency-hopping spread spectrum (FH-SS) systems is treated in this paper. First, we analyze the effect of continuous-wave tone interference in noncoherent binary frequency-shift keying (BFSK) signaling with FH-SS. Based on this analysis, a new receiver for FH-SS systems is proposed, including a transform-domain interference suppression module. The algorithm is executed in two steps: 1) interference detection and 2) signal reconstruction. The novelty of this suppression algorithm is the combination of the undecimated wavelet packet transform with frequency shifts of the received signal to center the narrowband interference in a subband. Once the subband that contains the interference has been determined, the algorithm removes this subband and then reconstructs the signal. The performance of this receiver has been evaluated in a variety of situations with different types of narrowband interference. The results obtained show the improvement of the proposed receiver in comparison to the traditional FH-SS receiver.