周期前导结构OFDM帧信号的检测

Frame Detection of OFDM Signal with Periodic Preamble

该文研究了具有多周期前导字WLAN OFDM帧信号在多径弥散信道、存在载波频偏条件下的检测。考虑到接收机自动增益控制(AGC)的影响,帧检测可以看作一个含未知参数的假设检验问题.根据广义似然比检验原理,并利用信号周期性的特点,导出一个具有恒虚警特性、对载波频偏不敏感的帧检测器。文中用广义Lambda分布描述帧检测器在无信号时的统计特性,并根据Neyman-Pearson准则给出一定虚警概率下的判决阈值,最后通过计算机仿真得到帧检测性能。

This paper deals with frame detection of OFDM signal with multiple-periodic preambles transmitted over frequency-selective channels and with existence of carrier frequency offset. Involving effect of AGC (Automatic Gala Control), frame detection can be taken as a hypothesis test model with unknown parameters. By applying generalized loglikelihood ratio testing to this model, a simple CFAR (Constant False-Alarm Rate) detector that is insensitive to frequency offset is derived. Parametric generalized lambda distribution is utilized to fit the statistical characteristic of detector when only noise exists, which is then used by Neyman-Pearson rule to determine decision threshold at given false alarm probability. Finally, computer simulations achieve detection performance of the obtained frame detector.