修正的MIMO-FSO信道自适应SVD估计算法

Modified Adaptive SVD Estimating Algorithm about MIMO-FSO Channels

针对多入多出(MIMO)无线光通信(FSO)中传统的奇异值分解(SVD)信道估计算法由于训练序列的单极性容易导致信号能量损失,从而引起信道估计值不准确的问题,提出了一种修正的自适应SVD估计算法。该修正算法能对SVD算法中存在的估计误差进行补偿,从而能使该估计方法更好地应用于MIMO-FSO系统中。仿真结果表明,与SVD算法相比,在信噪比为15dB时,修正的算法有2个数量级的均方误差(MSE)性能提高,在信噪比为30dB时,MSE性能有3个数量级的提高。与相同条件下的均值修正SVD算法相比,平均有1dB左右的性能改善。该修正方法可移植性强,在其他信道估计方法中也可采用类似的改进方法。

Because the training serials are unipolar in multi-input multi-output free space optical communication （MIMO-FSO） systems, which leads to the signal energy loss easily, the result of traditional singular value decomposition （SVD） channel estimation algorithm is inaccurate. A kind of modified adaptive SVD estimation algorithm is put forward which can compensate for the estimation errors of SVD algorithm. So the modified adaptive SVD estimation algorithm can be better fit for MIMO-FSO systems. The simulation results indicate that compared with the SVD algorithm, the mean square error （MSE） performance of the modified algorithm is improved by two and three orders of magnitude when the signal-to-noise ratio （SNR） is 15 dB and 30 dB, respectively. Compared with the average value modified SVD algorithm, the modified algorithm has 1 dB improvement of the MSE performance under the same condition. The modified algorithm possesses strong transplanting property and can be adopted in other channel estimation methods.