ST序列在沙尘大气激光通信中的信道估计性能研究

Research on channel estimation performance of ST sequence in sand-dust atmospheric laser communication

大气中悬浮的沙尘和气溶胶粒子会对激光产生吸收和散射作用,导致光脉冲出现衰减、时延与展宽的问题,造成信噪比下降和码间串扰现象。为此,利用叠加训练(ST)序列设计了一种针对强度调制/直接检测(I M/DD)的大气激光通信信道估计方法,推导了该方法在沙尘信道下的估计均方误差(MSE)和输出信噪比最大准则下的最佳功率分配因子。通过仿真分析了ST长度、功率分配因子以及信噪比对估计精度和误码率的影响。仿真结果表明,在小信噪比的沙尘大气信道条件下,该方法在取得与传统时分复用方式相近的估计性能和系统误码性能情况下,可以有效提高系统频带利用率、降低算法复杂度。

The absorption and scattering of suspended sand and aerosol particles in the atmosphere will cause the attenuation, delay and broadening of the optical pulse signal and cause the signal-to-noise ratio decrease and the iner-symbol interference. Therefore, an atmospheric laser communication channel estimation method for intensity modulation/direct detection （IM/DD） is proposed by using superimposed training （ST） sequences, the estimated mean square error （MSE） and the optimal power allocation factor of the maximum output sig- nal-to-noise ratio in the sand dust channel are derived. The influence of the superimposed training sequence length, the power allocation factor and signal-to-noise ratio on the estimation accuracy and bit error rate are analyzed by simulation. The simulation results show that under small signal-to-noise ratio sand-dust atmo- spheric channel, the proposed method can effectively improve the system bandwidth utilization and reduce the algorithm complexity under the conditions of similar estimated performance and systematic bit error rate performance compared with the traditional time division multiplexing approach.