Estimating the number of frequency hopping interferers using spectral sensing with time and frequency offset measurements

Design and implementation of spectrum sensing for cognitive radios with a frequency-hopping primary system

“…A method for estimating the FH boundary for bluetooth signal, with help of a Short Time Fourier Transform (STFT), has been discussed in [27]. Based on this approach, we propose a technique to identify the FH boundary by using the already implemented FAR algorithm.…”

“…In this paper, for simplicity, we assume that the number of active PUs, denoted by L, is known. In practice, since the number of active PUs typically varies very slowly compared to the bin occupancy patterns, it can be estimated and tracked based on the sensing outcomes [27]. Let u ∈ {0, 1} K represent the primary occupancy pattern, where u(k) takes the value 0 or 1, depending on whether the k th frequency band is free or occupied, respectively.…”

“…This method can be applied with slight modifications to the case where the primary users when they are not hopping synchronously, by suitably choosing the threshold for the histogram. More details can be found in[27]. Comparison of CR throughput obtained by FAR algorithm with that of ED, obtained through hardware implementation, with N = 64.…”