基于Sub-Nyquist采样的单通道频谱感知技术

宽带频谱感知技术在认知无线电中具有广泛的应用。基于时分的思想,将信号采集时间以固定长度的时间片进行划分,分别与不同的伪随机码信号相乘,经过低通滤波和sub-Nyquist采样,利用采样数据求出信号的频率支集。与已有的多通道频谱感知结构相比,本文用相对简单的单通道结构实现,同样能够利用低速率的采样点完成频谱感知。仿真实验结果表明,在信号的频率支集未知的情况下,该算法能够有效利用sub-Nyquist采样的数据实现频谱感知。

Single-channel Spectrum Sensing Technique Based on Sub-Nyquist Sampling

Spectrum sensing technique for wideband analog signals has been applied widely in cognitive radio. Based on the idea of time-division, this study was conducted with the following steps. Firstly, sampling time was divided into time slices which have fixed length. Secondly, the signal was multiplied by a bank of periodic waveforms which are modulated by pseudorandom number generators, and the product is low-pass filtered and sampled at sub-Nyquist rate. Finally, the samples were used to evaluate frequency support. Compared with the multi-channel structure, the single-channel structure proposed here is much simpler and has the ability to spectrum sensing with low-rate samples. Numerical simulations show that this algorithm can effectively use samples sampling at sub-Nyquist rate to finish the task of spectrum sensing in scenarios that the spectral support is unknown in advance.