针对大气激光通信中的帧同步问题, 分别基于信道特征和中心极限定理, 提出了两种帧同步识别算法。首先分析了大气激光通信的信道特征并建立了相应的信道模型; 随后利用此模型, 对输出电平矩阵每一列的数据分布情况进行了讨论, 提出了基于信道特征的帧同步算法; 最后, 针对输出电平矩阵帧数较少的情况, 从输出电平矩阵和值的概率分布情况出发, 提出了基于中心极限定理的帧同步算法。仿真结果表明, 基于信道特征的帧同步算法在帧数较多的情况下性能较好, 当信道比达到6 dB时帧同步识别率可达到100%, 但是, 随着帧数的减少, 其帧同步识别率迅速下降; 而基于中心极限定理的帧同步算法性能受帧数影响较小, 在信噪比大于7 dB时, 即使帧数下降到20, 其帧同步识别率仍可达到100%, 具有良好的帧同步性能。

In view of the problem of frame synchronization in atmospheric laser communication and based on channel characteristics and central limit theorem, two kinds of frame synchronization recognition algorithms are proposed. At first, the atmospheric laser communication channel characteristics are analyzed and the corresponding channel model is established. And then, followed by this model, the data distribution of the output level matrix for each column is discussed, and the frame synchronization algorithm based on the channel characteristics is proposed. At end, aiming at less numbers of matrix frames of the output level, from the probability distribution of the sum value of the output level matrix, the frame synchronization algorithm based on the central limit theorem is proposed. The simulation results show that the performance of the frame synchronization algorithm based on channel characteristics is great on the condition of more number of frames. When SNR reaches 6 dB, the frame synchronous recognition rate can reach 100%, and when the frame number getting small, the frame synchronous recognition rate decreases rapidly. But the number of frames has little effect on the performance of the frame synchronization algorithm based on the central limit theorem. When the SNR is more than 7 dB, even if the number of frames drops to 20, the frame synchronous recognition rate can still reach 100%, which has better frame synchronous performance.