中文摘要：

由于光色散以及电子器件速率的限制，自由空间光通信（FSO）系统传输速率受限，误码性能不理想。为了充分发挥FSO的潜力，支持更高的信息传输速率和改善系统误码特性，将OFDM与FSO这两项较成熟的技术相结合，对系统进行建模并利用Matlab软件对FSO—OFDM系统进行性能仿真，验证了FSO-OFDM系统采用不同调制阶数、不同子载波数、不同保护间隔长度下系统的误码性能，为系统参数的合理选择提供了理论依据。

英文摘要：

Due to the limitations of light dispersion and speed restriction of electronic devices, both the transfer rate and the performance of Free Space Optical （FSO） are limited. In order to sufficiently exploit the potentials of FSO to enhance the transfer rate and the bit error rate （BER） performance of the optical communication system, it needs to adopt a new transmission technology which owns high spectrum efficiency and high ability to combat the atmospheric scattering effect. Hence, the two mature technologies of OFDM and FSO are combined in this paper. The system model is built according to the basic principles of FSO and OFDM. Finally, the system＇s BER performance with different types of modulation, different numbers of carrier, and different guard interval lengths are simulated by Matlab.