正交频分复用/偏移正交振幅调制半盲信道估计

非合作通信背景下，针对传统干扰近似法（IAM）进行正交频分复用（OFDM）/偏移正交振幅调制（OQAM）系统信道估计需要导频符号值作为先验信息的问题，提出一种基于OQAM符号特征的IAM（OCB-IAM）估计算法。该算法利用IAM导频结构和OQAM实符号的有限集特征，将信道衰落系数幅度和相位分开估计，在仅获得导频位置而未知导频符号值的条件下实现了OFDM/OQAM系统半盲信道估计。并且证明了OCB-IAM算法由于利用接收符号的二阶统计量将高斯白噪声变为非随机的单音干扰，从而在中低信噪比条件下具有优于IAM算法的估计性能。仿真实验验证了理论推导的正确性和OCB-IAM算法的可靠性。
Interference approximate method (IAM) for orthogonal frequency division multiplexing / offset quadrature amplitude modulation (OFDM/OQAM) channel estimation needs the value of preamble at the background of un-cooperative communications. Motivated by this consideration, an OQAM characteristic based-IAM (OCB-IAM) algorithm, which used IAM preamble framework and OQAM symbols’ real finite-alphabet characteristics, was introduced. OCB-IAM algorithm estimated the amplitude and phase of channel fading coefficients separately, and just needed preamble position, which was a kind of semi-blind channel estimators. OCB-IAM algorithm converted white Gaussian noise into single tone interference based on the second order statistics of received symbols. Then it could be proved that OCB-IAM algorithm has a better performance than IAM algorithm in medium and low SNR regime. Numerical results show the validity of theoretical analysis and the reliability of OCB-IAM algorithm.