On Spectrum Sensing of OFDM Signals at Low SNR: New Detectors and Asymptotic Performance
On Spectrum Sensing of OFDM Signals at Low SNR: New Detectors and Asymptotic Performance
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低 SNR 下 OFDM 信号的频谱感知：新检测器和渐近性能
DOI：
10.1109/tsp.2017.2688967
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发表时间：
2017-06
影响因子：
5.4
通讯作者：
Youming Li
中科院分区：
文献类型：
--
作者：
Ming Jin;Qinghua Guo;Jiangtao Xi;Youming Li
本文研究了正交频分复用 (OFDM) 信号的近乎最优频谱感知，以实现低信噪比 (SNR) 下的可靠检测。似然比检验 (LRT) 是一种简单的假设检验，可提供最佳性能，但要求测试中涉及的参数已知。因此，经常采用广义似然比检验（GLRT），一种复合假设检验。然而，基于 GLRT 的检测器涉及有偏差的参数估计，这可能导致性能较差。在本文中，通过适当的近似，LRT被简化为更简单的形式，只需要噪声功率的知识。然后开发了一种新颖的无偏且一致的噪声功率估计器。该估计量与近似 LRT 相结合，形成渐近简单假设检验 (ASHT)。针对有和没有时间同步的情况提出了两种基于 ASHT 的检测器，并分析了它们的理论性能。仿真结果表明，基于 ASHT 的探测器的性能非常接近最佳 LRT，并且显着优于现有的基于 GLRT 的探测器。研究还表明，基于 ASHT 的检测器对多径信道的影响表现出鲁棒性。
This paper deals with near-optimal spectrum sensing of orthogonal frequency division multiplexing (OFDM) signals to achieve reliable detection at low signal-to-noise ratio (SNR). The likelihood ratio test (LRT), a simple hypothesis test, delivers the optimal performance, but it requires that the parameters involved in the test are known. Hence, the generalized likelihood ratio test (GLRT), a composite hypothesis test, has often been employed. However, GLRT-based detectors involve biased parameter estimation, which may lead to inferior performance. In this paper, with proper approximation, the LRT is reduced to a simpler form, which only requires the knowledge of noise power. Then a novel unbiased and consistent estimator of the noise power is developed. This estimator is combined with the approximate LRT, leading to an asymptotic simple hypothesis test (ASHT). Two ASHT-based detectors are presented for cases with and without time synchronization, and their theoretical performances are analyzed. Simulation results show that the ASHT-based detectors deliver performances very close to that of the optimal LRT, and significantly outperform the existing GLRT-based detectors. It is also shown that the ASHT-based detectors exhibit robustness against the influence of multipath channels.
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