周期前導(dǎo)結(jié)構(gòu)OFDM幀信號(hào)的檢測
Frame Detection of OFDM Signal with Periodic Preamble
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摘要: 該文研究了具有多周期前導(dǎo)字WLAN OFDM幀信號(hào)在多徑彌散信道、存在載波頻偏條件下的檢測?？紤]到接收機(jī)自動(dòng)增益控制(AGC)的影響，幀檢測可以看作一個(gè)含未知參數(shù)的假設(shè)檢驗(yàn)問題。根據(jù)廣義似然比檢驗(yàn)原理，并利用信號(hào)周期性的特點(diǎn)，導(dǎo)出一個(gè)具有恒虛警特性、對(duì)載波頻偏不敏感的幀檢測器。文中用廣義Lambda分布描述幀檢測器在無信號(hào)時(shí)的統(tǒng)計(jì)特性，并根據(jù)Neyman-Pearson準(zhǔn)則給出一定虛警概率下的判決閾值，最后通過計(jì)算機(jī)仿真得到幀檢測性能。Abstract: This paper deals with frame detection of OFDM signal with multiple-periodic preambles transmitted over frequency-selective channels and with existence of carrier fre-quency offset. Involving effect of AGC (Automatic Gain Control), frame detection can be taken as a hypothesis test model with unknown parameters. By applying generalized log-likelihood 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 proba-bility. Finally, computer simulations achieve detection performance of the obtained frame detector.
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