Fast acquisition and time synchronization of frequency hopping burst signals

Abstract

Frequency hopping is used in different communications systems for its robustness by providing frequency diversity against jamming and interfering signals. Successful detection and demodulation of a frequency hopping signal is dependent on proper tuning to transmit frequency and time synchronization of the burst. The sequence of hop frequencies is generally determined by a Pseudo-Noise (PN) sequence and time synchronization is achieved using synchronization preambles in the transmit burst. Successful acquisition of the hop frequency sequence could be achieved when at least a single burst's data is successfully decoded at the receiver. In this paper we present a low complexity, two-level acquisition based scheme for fast acquisition of the frequency hopping and time synchronization of the burst based on the Zadoff-Chu synchronization preambles. We have presented the simulation results detailing the proposed scheme's performance and proposed a low complexity hardware implementation architecture. Simulations show that the single IF channel synchronization detection performance is above 99% for SNRs more than −20dB and wideband multiple digital IF detection performance is similar to single digital IF channel performance for SNRs more than −5dB. The simulations have been carried out for characterizing the performance in different propagation channel environments such as AWGN, LTE-EVA, LTE-ETU and 6-path Rician propagation channels. The performance degradation due to the low complexity hardware is seen to be less than 1% for SNRs above −20dB and the synchronization performance difference reduces to less than 0.1% for SNRs above −5dB.