The stable and anti-jamming algorithm for synchronization of Hybrid Spread Spectrum system

Hybrid Spread Spectrum (HSS) link is a suitable and robust physical layer structure for the tactical ad-hoc network. In this link, synchronization consists of two stages: Frequency hopping pattern synchronization and direct sequence code synchronization. In the presence of jamming, the use of the conventional fixed-threshold detection method increases the false alarm rate. Increasing the false alarm rate increases synchronization time in the HSS link. To solve this problem, the noise and jamming power estimator block is usually used at the receiver. Threshold value is adjusted instantaneously based on the estimated power in this method. This method has a high computational load and hardware complexity, and error in estimating noise and jamming power leads to an increase in the false alarm rate. In this paper, the proposed synchronization algorithm of the hybrid spread spectrum system is presented as an adaptive threshold, based on the statistical characteristics of the received signal. In the proposed algorithm, the threshold value is changed adaptively so that the false alarm rate remains constant at a minimum value. The theoretical analysis and simulation results show that the proposed algorithm can improve the detection probability and false alarm rate and reduce the synchronization time in the presence of a jamming compared to the conventional fixed threshold method.