快时变OFDM系统中非采样间隔信道的信道估计

摘要：在快时变环境下的OFDM（orthogonal frequency division multiplexing，正交频分复用）系统中，针对非采样间隔信道CIR（channel impulse response，信道冲击响应）能量泄漏和ICI（inter-carrier interference，子载波间干扰）的问题，提出了一种基于分数抽头信道近似的复指数基扩展联合反馈离散傅里叶变换信道估计算法。该算法首先根据基于分数抽头信道近似的复指数基扩展模型计算信道参数，再根据该信道参数计算出快时变环境下OFDM系统的ICI系数，然后将初次消除ICI的信号作为反馈进行离散傅里叶变换，进一步消除噪声和ICI。该算法在一定程度上抑制了CIR能量泄漏，消除了ICI和噪声，有效地近似了实际信道。仿真结果表明，该算法在误比特率和信道均方误差方面均有明显提高。

New Channel Estimation Algorithm for Non-Sample-Spaced Channels in Fast Time-Varying OFDM System

In fast time-varying OFDM（orthogonal frequency division multiplexing）system, in order to lessen the effects of the CIR（channel impulse response）leakage and ICI（inter-carrier interference）, a new channel estimation algorithm was proposed, which was adapted to non-sample-spaced channels. The algorithm combined complex exponential basis expansion model and the feedback of DFT（discrete fourier transform）, which was built according to the fraction taps channel approximation.The channel parameters were firstly estimated with the complex exponential basis expansion model based on the fraction taps channel approximation.Then the ICI in fast time-varying OFDM system could be calculated according to the estimated channel parameters. Then the feedback was obtained by the elimination of ICI, and noises could be eliminated by DFT. The algorithm could suppress the CIR leakage, eliminate ICI and noises and effectively approximate the actual channels. The simulation results show that the bit error rate and channel mean square error of the proposed algorithm are both effectively improved.