基于反馈迭代算法的航空通信系统信道估计算法研究

Feedback-Iterative Channel Estimation Algorithm for Aeronautical Communication System

航空通信系统的时变性和大时延,导致传统信道估计算法存在信道参数估计不精确问题。为解决此问题,在建立飞机巡航阶段两径莱斯信道模型的基础上,提出一种反馈迭代信道估计算法。该算法核心思想为:首先利用少量原始导频对信道进行粗略时域最小二乘(least-square,LS)估计,并检测传输信号;之后将检测信号经调制和卷积编码反馈至信道估计器,并作为导频再次进行信道估计;最后将以上过程经过两次迭代得到最终结果。仿真结果表明,提出的算法相比无反馈的LS算法,在信噪比小于20 dB情况下,可获得约2 dB的均方误差增益,从而验证了此迭代估计算法可以起到提高航空信道估计精确度的效果。

The existing channel estimation algorithms have witnessed the disadvantages of high estimation error due to the fast time-varying channel and large propagation delay in the aeronautical communication system.This paper proposed an feedback iterative channel estimation algorithm based on the two-path Rice channel model for the en-route scenario.The proposed algorithm only used a small pilot overhead for rough least square(LS)channel estimation and signal detection,after being modulated and encoded,the obtained signals were fed back to the channel estimator used as pilot symbols again.Finally,the proposed scheme was capable of converging to a stable performance with two iterations.The simulation results demonstrate that the proposed channel estimation scheme was capable of achieving about 2 dB mean square error when the signal-to-noise ratio(SNR)was less than 20 dB,which verified that this algorithm could improve the accuracy of the aeronautical channel estimation.