一种结合DWT与DCT插值的OFDM信道估计新方法

A new method for channel estimation of OFDM based on DWT and DCT interpolation

针对传统的基于离散余弦变换(DCT)的正交频分复用(OFDM)信道估计算法去除噪声不够理想的问题,提出了一种结合离散小波变换(DWT)与DCT插值的OFDM信道估计新方法.在对信号进行最小二乘(LS)估计后,利用DWT对信号进行阈值量化消噪处理,然后将循环前缀(CP)内各采样点上的能量均值作为DCT线性插值过程中的阈值,对循环前缀内的噪声进行再次处理,从而进一步降低噪声的影响.对算法的误码率(BER)和均方误差(MSE)等进行了试验仿真.仿真结果表明:文中算法的性能明显优于经典的LS算法、传统的DFT算法、基于改进阈值的DCT信道估计算法.新算法使循环前缀内的噪声得到了有效的抑制,与基于改进阈值的DCT信道估计算法相比,在相同BER下,文中算法的SNR提升了约1 dB;当MSE相同时,文中算法SNR约有2 dB提高.

To solve the problem that traditional channel estimation algorithm of orthogonal frequencydivision multiplexing （ OFDM） based on discrete cosine transform （DCT） could not effectively eliminate noise , a new method for channel estimation of OFDM was proposed based on di（DWT） and DCT interpoltion. The DWT was used to quantify the signal threshold after channelestimation by least square （LS）. The average energy of all sampling points within thwas calculated, which was regarded as threshold in the process of DCT interpolation. The noise in the CPwas handled again to further reduce the noise effect. The bit error rate （ ） and the mean squarederor （WISE）of the algorithm were simulated. The simulation results show that the improved algorithm is better than traditional LS algorithm, traditional DFT algorithm and DCT algorithm based on improved threshold. The noise inside CP is suppressed effectively by the treatment of new algorithm. Comparedwith the DCT algorithm based on improved threshold, the SNR of the proposed algorithm is improved byabout 1 dB for the same BER and by about 2 dB for the same MSE.