频率选择性衰落信道下OFDM信噪比盲估计

SNR estimation for OFDM signals in frequency selective fading channels

针对频率选择性衰落信道下带有载波频偏的OFDM(正交频分复用)信号信噪比(SNR)估计问题,提出一种基于空载波OFDM系统的SNR盲估计方法。由于本振和接收信号之间的不一致,会使得接收到的信号带有一定的频偏。频偏的存在破坏了子载波间的正交性,增加了子载波间的干扰噪声,从而减少了SNR。首先分析了频偏对信噪比的影响并得到有无频偏时信噪比之间的关系,其次根据空载波的特点估计出无频偏时的信噪比,再基于上述关系对OFDM信号进行有频偏时的信噪比盲估计,最后通过仿真验证了理论分析的正确性。

For frequency selective fading channel with a carrier frequency of OFDM signal to noise ratio （SNR） estimation problem, this paper proposed an air carrier OFDM system based on blind SNR estimation method. Due to the inconsistency between the oscillator and the received signal, the received signal would be with a certain deviation. The presence of frequency offset destroyed the orthogonality between sub-carriers, and increased the interference noise, and then reduced the SNR. This paper analyzed the effects of frequency offset on the signal to noise ratio and got the relationship between the SNR existed fre- quency offset and no offset. It followed by characteristics of air carrier to estimate the SNR where there was no frequency off- set. And then based on the above premise, it estimated blind SNR when the signal existed frequency offset. Finally, this paper proves the correctness of theoretical analysis by simulation.