A Method to Improve 2D Continuity Performance of Differential Frequency Hopping Sequence

Differential frequency hopping (DFH) was believed to be an effective FH technique for increasing data rate of HF communication system. However, it was shown by recent studies that DFH suffered from an inherent serious drawback that the frequency transition matrix may be intercepted by any third-party receiver and this would decline the anti-jamming performance of DFH. The root of this drawback is the poor 2-dimensional (2D) continuity of DFH sequence. Theoretical analysis of 2D continuity performance of DFH sequence is performed in this paper and it is proved that DFH sequence using single G function (GF) generated with most GF construction methods may not have favorable 2D continuity performance. A simple but convenient method, time varying G Function (TVG) method, is put forward to improve 2D continuity performance of DFH sequence. Optimization of TVG method is performed and optimization criterion of GF sequence is deduced. Simulation results verifies the feasibility and effectiveness of this method.