基于信号检测的光无线轨道角动量复用系统研究

基于轨道角动量(OAM)的光无线复用通信技术在理想传输条件下能够大幅度提升通信系统性能，然而现实中大气湍流、孔径失配等因素会造成OAM模态间串扰导致误码率(BER)上升。为了降低光无线OAM复用系统在复杂环境中的误码率，该文首先建立了大气湍流、孔径失配场景下基于垂直分层空时码准则(VBLAST)的OAM复用通信系统(VBLAST-OAM)，之后分析对比基于排序干扰连续消除检测算法(OSIC)、基于马尔科夫随机场置信度传播算法(MRF-BP)、基于OAM串扰特性的排序干扰连续消除算法(OAM-OSIC)应用于上述系统时的性能。结果表明:所提信号检测算法均能有效降低OAM复用系统在复杂环境中的误码率，其中，基于MRF-BP算法的系统性能最好；OAM-OSIC虽然属于次优算法，但在算法的运行开销方面具有较大优势。

Research on Optical Wireless Orbital Angular Momentum Multiplexing System Based on Signal Detection

The wireless communication technology based on Orbital Angular Momentum (OAM) can greatly improve the performance of the communication system under ideal transmission conditions. However, in the actual environment, atmospheric turbulence and aperture mismatch can cause crosstalk between OAM modes and increase the Bit Error Rate (BER). In order to reduce the BER of the optical wireless OAM multiplexing system in a complex environment, an OAM multiplexing communication system based on the Vertical Bell LAyered Space Time (VBLAST-OAM) code criterion under the scenario of atmospheric turbulence and the aperture mismatch of the transceiver is established firstly. Then, the system performance are analyzed based on the Ordered Successive Interference Cancellation (OSIC), the Markov Random Field Belief Propagation (MRF-BP) algorithm and the algorithm OAM-OSIC. Simulation results show that the algorithm proposed in this paper can reduce the BER of OAM systems effectively in complex environment and the MRF-BP has the best performance. Although OAM-OSIC is a suboptimal algorithm, it has a great advantage in the running cost.