In this paper, the performance of the free-space optical (FSO) system from ground-to-satellite is analyzed considering the combined effect of atmospheric turbulence and beam wandering employing M-ary phase-shift keying (MPSK). Key parameters of the vertical connection, such as satellite altitude, zenith angle, and beam size, are investigated. In order to improve the spectrum efficiency, an adaptive transmission approach is applied to ensure efficient channel capacity usage. The procedure depends on changing the modulation order of the MPSK scheme according to the instantaneous channel state and the acceptable bit error rate. Furthermore, a single-input multiple-output (SIMO) system with maximal ratio combining (MRC) diversity is used to mitigate the effects of atmospheric turbulence and beam wandering. Closed-form and asymptotic expressions are presented for the average bit error rate (BER) for a single-input single-output (SISO) and SIMO techniques. Moreover, closed-form expression is deducted for the upper bound bandwidth efficiency. The accuracy of the derived closed-form and asymptotic expressions are verified by adopting appropriate simulation cases and parameters. The results show that the optimal value of the beam size ratio (BSZ) is $1.6$. Also, the results prove that the adaptive technique improves spectrum efficiency by more four times the non-adaptive method at the same BER threshold of ${10}^{-2}$. By using a $1\times 4$ SIMO system, the same adapted spectrum efficiency is achieved with a reduction of 4 dB in SNR versus $1\times 2$ SIMO system and 8 dB in SNR versus SISO system. A $1\times 4$ SIMO system achieves a threshold bit error rate of 5 dB reduction in SNR compared to a $1\times 2$ SIMO system and a 10 dB reduction in SNR compared to SISO system.

在本文中，考虑了大气湍流和M阶相移键控（MPSK）引起的束流漂移的综合影响，分析了从地面到卫星的自由空间光学（FSO）系统的性能。研究了垂直连接的关键参数，例如卫星高度，天顶角和波束大小。为了提高频谱效率，应用自适应传输方法以确保有效的信道容量使用。该过程取决于根据瞬时信道状态和可接受的误码率来更改MPSK方案的调制顺序。此外，具有最大比率组合（MRC）分集的单输入多输出（SIMO）系统用于减轻大气湍流和波束漂移的影响。给出了单输入单输出（SISO）和SIMO技术的平均误码率（BER）的闭式和渐近表达式。而且，为了上限带宽效率，推导了封闭形式的表达式。通过采用适当的仿真案例和参数，验证了导出的闭合形式和渐近表达式的准确性。结果表明，光束尺寸比（BSZ）的最佳值为$1.6$。结果还证明，在相同的BER阈值下，自适应技术将频谱效率提高了非自适应方法的四倍以上。${10}^{--2}$。通过使用$\mathrm{1个}\times 4$ SIMO系统与SNR相比降低了4 dB，实现了相同的自适应频谱效率 $\mathrm{1个}\times 2$SIMO系统和SNR相对于SISO系统为8 dB。一种$\mathrm{1个}\times 4$ SIMO系统的门限误码率比SNR降低了5 dB $\mathrm{1个}\times 2$ 与SISO系统相比，SIMO系统的信噪比降低了10 dB。