| 摘要: |
| 正交频分复用（Orthogonal Frequency Division Multiplexing,OFDM）调制因其高效的频带利用率和良好的抗多径能力广泛用于合作与非合作通信系统中。合作通信场景下，通常接收机可以利用已知帧结构实现OFDM信号的检测。但在非合作场景下，接收机没有足够的先验信息，导致帧检测难度加大。针对这一问题，提出了一种适合于非合作通信场景的OFDM数据帧的检测算法。所提算法利用快速小波变换将含噪OFDM信号的功率包络进行小波分解与重构，对重构得到的功率包络进行差分运算后，再通过与阈值比较实现OFDM信号的帧检测。相较于混合能量检测算法，所提算法计算预设参数少，复杂度低。仿真结果表明，所提算法在加性高斯白噪声信道和多径衰落信道下带内信噪比分别取-6 dB和3 dB时即可实现零漏报率，且零漏报率的阈值选取范围比混合能量检测算法扩大了约6 dB。 |
| 关键词: 非合作通信 正交频分复用 帧检测 快速小波变换 |
| DOI：10.20079/j.issn.1001-893x.240130002 |
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| 基金项目:国家自然科学基金资助项目(61901291) |
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| An OFDM Frame Detection Algorithm for Non-cooperative Communications |
| DONG Chen,LI Zhe,DENG Wei |
| (1.School of Electronic and Information Engineering,Soochow University,Suzhou 215031,China;2.School of Information Engineering,Jiaxing Nanhu University,Jiaxing 314001,China) |
| Abstract: |
| Orthogonal frequency division multiplexing(OFDM) modulation is widely used in cooperative and non-cooperative communication systems,owing to its high spectral efficiency and robustness to multipath fading.In cooperative communications,frame detection for OFDM signals can be implemented by exploiting its underlying physical frame structure,which is known to the receiver.However,the receiver in non-cooperative communications does not have a priori information,leading to increased difficulty in frame detection.To this end,the authors propose an OFDM frame detection algorithm for non-cooperative communications.The proposed algorithm uses fast wavelet transform to perform wavelet decomposition and reconstruction of the envelope of a noisy OFDM signal.The differential operation is performed on the reconstructed envelope to obtain the power difference sequence,whereby a successful frame capture is confirmed if there exists a sample whose power difference value is above a predetermined threshold.Compared with the hybrid energy detection method(HED),the proposed frame detection algorithm requires fewer parameters and lower computational complexity.Simulations employing both an additive white Gaussian noise channel and a multi-path fading channel demonstrate that the proposed algorithm achieves zero under-reporting rate at in-band signal-to-noise ratios of -6 dB and 3 dB,respectively.Moreover,the threshold selection range to ensure zero under-reporting rate of the proposed algorithm is approximately 6 dB wider than that of the HED method. |
| Key words: non-cooperative communications orthogonal frequency division multiplexing frame detection fast wavelet transform |
