An Improved Time-Domain Autocorrelation Spectrum Detection Algorithm

When a primary user uses frequency hopping communication, cognitive radio users using typically spectrum detection method is the time-domain autocorrelation. But the primary users signal is interfered by a fixed-frequency interference (FFI), the method is invalid. For the problem, this paper improves the traditional time-domain autocorrelation method by using the power spectrum cancellation, and the improved method can effectively avoid the fixed-frequency spectrum interference to increase the spectrum detection performance. Simulation results show that signal-to-noise ratio (SNR) is below -10 dB, and the false alarm probability is 0.05, the detection probability of improved method is greater than that of the traditional time-domain autocorrelation method. In low SNR, the improved method has a good detection performance, and also can prevent the collision between frequency of FFI and frequency of the primary user as well.