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多输入多输出(MIMO)技术是消除大气闪烁对空间光通信的影响和降低误码率(SER)的有效手段之一。针对2×2空间光通信系统,将Alamouti空时码与跳时超宽带技术(TH-UWB)结合,提出一种适合脉冲位置调制(PPM)的循环空时编码(RSTC)方法,推导了等增益合并(EGC)最大似然检测(MLD)和相关矩阵检测(CMD)的两种解码算法,最后分析了系统误码性能。在弱湍流和准静态衰落信道条件下仿真,结果表明,无论是在信道信息(CSI)已知还是未知情况下,编码2×2系统的误码率高于未编码的。该编码方法获得了空间和时间分集,相关矩阵检测法取得相似于信道最大比值合并(MRC)的效果,但随信道间相关性增加其误码性能下降明显。
Multiple-input multiple-output (MIMO) technology is one of the effective means to eliminate the influence of atmospheric flicker on space optical communication and reduce the bit error rate (SER). Aiming at the 2 × 2 space optical communication system, Alamouti space-time code and time-hopping ultra wideband technology (TH-UWB) are combined to propose a cyclic space-time coding (RSTC) method suitable for pulse position modulation (PPM) Two kinds of decoding algorithms of Gain Merge (EGC) Maximum Likelihood Detection (MLD) and Correlation Matrix Detection (CMD), and finally analyze the system error performance. The simulation under weak turbulence and quasi-static fading channels shows that the BER of coding 2 × 2 system is higher than that of uncoded channel, no matter whether the channel information (CSI) is known or unknown. The coding method obtains spatial and temporal diversity, and correlation matrix detection achieves the similar effect of MRC. However, with the increase of the inter-channel correlation, the error performance decreases obviously.