自由空间光通信中的带符号光正交空间调制  

Signed Optical Quadrature Spatial Modulation in Free Space Optical Communication

作　　者：赵辉[1,2] 刘亮 韩利利 秦玉林 李俊男 ZHAO Hui;LIU Liang;HAN Lili;QIN Yulin;LI Junnan(School of Communication and Information Engineering,Chongqing University of Posts and Telecommunications,Chongqing 400065,China;Chongqing Key Laboratory of Signal and Information Processing,Chongqing 400065,China)

机构地区：[1]重庆邮电大学通信与信息工程学院,重庆400065 [2]信号与信息处理重庆市重点实验室,重庆400065

出　　处：《光通信研究》2024年第3期126-133,共8页Study on Optical Communications

基　　金：国家自然科学基金资助项目(12104078)。

摘　　要：【目的】针对光正交空间调制(OQSM)中频谱效率较低和系统吞吐量受限的问题,文章在自由空间光通信(FSOC)中提出了一种带符号的光正交空间调制(SOQSM)方案;另外,针对OQSM性能分析时所用信道不适合所有湍流的情况,文章采取适合所有湍流强度的Málaga信道对系统的误码性能进行分析。【方法】首先,该方案在发送端将输入的二进制比特流划分为5个部分,第1个部分用于星座符号映射,后4个部分用于激光器映射;然后,星座符号映射用于传输星座符号及其逆符号的实部和虚部;激光器映射分为同相相位与正交相位两部分,用于激活激光器的序列映射;最后,通过信道进行传输,在接收端进行信号的接收和处理。【结果】相比OQSM,SOQSM在一个传输周期内空间域额外携带了2log2 Nt比特的信息,并在符号域和空间域分别计算出平均误码率上界,最终得到SOQSM方案的平均误码率上界,其中计算平均误码率上界的方法具有较好的收敛性。该方案较大程度地提高了系统的频谱效率和传输速率,拥有较好的误码性能。【结论】蒙特卡洛仿真结果表明:在频谱效率相同时,相比光空间调制(OSM)和OQSM,SOQSM方案的误码性能更好,能在信噪比为16 dB时就达到10-6;当调制阶数相同时,SOQSM的误码性能更优,特别是在高信噪比时,仿真与理论契合度较高。在Málaga信道中弱湍流的误码性能更好;另外,不同湍流强度对SOQSM方案误码性能趋势的影响较小,但随着信噪比提高,影响会逐渐增大。因此,SOQSM相比OQSM和OSM具有更好的误码性能。【Objective】Aiming at the problems of low spectral efficiency and limited system throughput in Optical Quadrature Spa tial Modulation(OQSM),a Signed Optical Quadrature Spatial Modulation(SOQSM)scheme is proposed in Free Space Optical Communication(FSOC)in this paper.In addition,in view of the fact that the channel used in the performance analysis of OQSM is not suitable for all turbulence,this paper also adopts the Málaga channel,which is suitable for all turbulence intensities to ana lyze the bit error performance of the system.【Methods】First,the scheme divides the input binary bit stream into five parts at the sending end.The first part is used for constellation symbol mapping,and the last four parts are used for laser mapping.Then,the constellation symbol mapping is used to transmit the real and imaginary parts of the constellation symbol and its inverse symbol.The laser mapping is divided into two parts,the in⁃phase phase and the quadrature phase,which are used to activate the laser se quence mapping.Finally,after transmitting through the channel,the signal received and processed at the receiving end.【Results】Compared with OQSM,SOQSM carries an additional 2log2 Nt bits of information in the space domain within a transmission peri od.The upper bound of the average bit error rate is then calculated in the symbol domain and the space domain respectively.Fi nally,the upper bound of the average bit error rate of the SOQSM scheme is obtained,and the method of calculating the upper bound of the average bit error rate has good convergence.This solution greatly improves the spectral efficiency and transmission rate of the system,and has good bit error rate performance.【Conclusion】The Monte Carlo simulation results show that compared with Optical Spatial Modulation(OSM)and OQSM,the bit error performance of the SOQSM scheme is better when the spectral efficiency is the same.The bit error rate can reach 10-6 when the signal⁃to⁃noise ratio is 16dB.When the modulation order is the same,the bit error p

关 键 词：自由空间光通信 光空间调制 频谱效率 误码性能 

分 类 号：TN929.12[电子电信—通信与信息系统]