【作者】 张毅；

【导师】 傅丰林；

【作者基本信息】 西安电子科技大学 ， 通信与信息系统， 2008， 硕士

【摘要】 OFDM(正交频分复用)是多载波调制的一种,它将高速串行数据变成多路相对低速的并行数据并对不同的载波进行调制。OFDM技术能够有效对抗多径干扰与频率选择性衰落,并具有频谱利用率高、成本低等优点。因此,对微弱OFDM信号的检测在实际应用中意义十分重大。论文首先研究了在低信噪比环境下,通过自适应滤波方法对OFDM信号进行增强和降噪处理。并且论文提出了改进的自适应算法,通过仿真可以看出,改进后的方法具有更好的性能。论文同时还对OFDM调制信号进行了类间识别研究,提出了一种在瑞利衰落信道条件下的多载波调制盲识别算法。用以区分多载波调制信号(OFDM)和单载波调制信号。该算法利用信号的高阶统计量作为分类特征,采用信噪比(SNR)与特征参数联合估计完成识别。论文还提出了在可以区别出OFDM和单载波信号同时,即使改变信号速率和信号采样速率,此种算法同样有效。以上通过仿真可以得出。更多还原

【Abstract】 OFDM is one of the multi-carrier modulations , it makes different carrier modulation and a high-speed multi-channel serial data is transformed to parallel low speed sub-data streams .OFDM has high utilization ratio of spectrum,low cost and can resist the multi-path interference and frequency-selective fading. So the detection of weak OFDM signal is great significance in practical application.The paper firstly researches the standard adaptive algorithm for OFDM signal detection in low SNR. Then a new adaptive algorithm is presented. The results of the simulations have proved that the new makes the better performance.At the same time ,the paper also researches inter-class recognition of OFDM signal. A new algorithm of inter-class recognition for OFDM signal over Rayleigh channel is proposed, then we can recognized the OFDM signals from the other single carrier signals. The joint estimation of the signal to noise ratio (SNR) and the feature value based on higher order moments can realize the recognition. Simulation result s show that if the f sand f sphave been changed,the algorithm is still effective.更多还原