Research on Optical Wireless Orbital Angular Momentum Multiplexing System Based on Signal Detection
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摘要: 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。Abstract: 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.
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表 1 OAM在大气湍流中的传播过程
初始化：源端光场$E(r,\phi ,z)$，空间传输函数$H$，相位屏个数N，相位$\varphi (x,y)$ (1) ${\rm{For }}j{\rm{ = 1:}}N$ (2) 傅里叶变换：$U(K,z) = {\rm{FFT}}\left( {E(r,\phi ,z)} \right)$ (3) 真空传播：${U'}(K,z) = {\rm{IFFT}}\left( {U(K,z) \times H} \right)$ (4) 穿过随机相位屏：$E(r,\phi ,z) = {U'}(K,z) \times \exp \left( {{\rm{j}} \times \varphi (x,y)} \right)$ (5) End For 
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表 2 OSIC算法
初始化：复用的OAM数目${ {{N} }_{{t} } }$，串扰信道$H$，接收到的信号r，噪声方差${\sigma ^2}$ (1) ${\rm{For } }j{\rm{ = 1:} }{ {{N} }_{{t} } }$ (2) 加权矢量W: 基于ZF/MMSE准则：$W = {\rm{pinv(} }H{\rm{)/pinv(} }{H^{\rm{H} } }{\rm{ + } }{\sigma ^2} \times {I_{ {N_{\rm{t} } } - j + 1} }{\rm{)} } \times {H^{\rm{H} } }$ (3) 首先对W的每一行求范数，并对范数排序，选取最小范数行k (OSIC) (4) 省略步骤(3) (OAM-OSIC) (5) $y(k) = W(k,:) \times r$ 判决统计量(优化前) (6) $y(k) = W(1,:) \times r$ 判决统计量(优化后) (7) 根据数据判决得到x(k) (8) $r = r{\rm{ - }}x(k) \times H$ 消除前一次检测的数据 (9) $H(:,k) = [\;]$ 将信道矩阵的第k列清除(优化前) $H(:,1) = [\;]$ 将信道矩阵的第1列清除(优化后) (10) 重复步骤(2)，更新W (11) ${\rm{End\; For}}$
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表 3 MRF-BP算法
初始化：$m_{i,j}^0 = b_i^0$, $z,R, p({x_i} = 1) = p({x_i} = - 1), \forall i,j \in $$ (1,2,\cdots,N)$, M是信息迭代次数 (1) ${\rm{For }}\;i{\rm{ = 1:}}N$ 势函数 (2) ${\rm{For }}\;j{\rm{ = 1:}}N$ ${\rm{ }}i \ne j{\rm{ }}$ (3) 根据式(24)计算${\psi _{i,j}}$； (4) ${\rm{End\; For}}$ (5) ${\rm{End\; For}}$ (6) ${\rm{For }}\;i{\rm{ = 1:}}N$ 相容函数 (7) 根据式(25)计算${\phi _i}$； (8) ${\rm{End\; For}}$ (9) ${\rm{For} }\; t = 1:M$ 迭代更新 (10)${\rm{For }}\;i{\rm{ = 1:}}N$ (11) ${\rm{For\; }}j{\rm{ = 1:}}N$ ${\rm{ }}i \ne j{\rm{ }}$ (12) 第t次迭代得到更新的信息$\overline m _{i,j}^t$，利用信息阻尼方式得到新信息$m_{i,j}^t$； (13) ${\rm{End\; For}}$ (14) ${\rm{End\; For}}$ (15) ${\rm{End\; For}}$ (16) ${\rm{For }}\;i{\rm{ = 1:}}N$ 置信度计算 (17) 根据式(20)计算置信度${b_i}$； (18) ${\rm{End\; For}}$
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[1] 郭忠义, 龚超凡, 刘洪郡, 等. OAM光通信技术研究进展[J]. 光电工程, 2020, 47(3): 190593. doi: 10.12086/OEE.2020.190593GUO Zhongyi, GONG Chaofan, LIU Hongjun, et al. Research advances of orbital angular momentum based optical communication technology[J]. Opto-Electronic Engineering, 2020, 47(3): 190593. doi: 10.12086/OEE.2020.190593 [2] ALLEN L, BEIJERSBERGEN M W, SPREEUW R J C, et al. Orbital angular momentum of light and the transformation of Laguerre-Gaussian laser modes[J]. Physical Review A, 1992, 45(11): 8185–8189. doi: 10.1103/PHYSREVA.45.8185 [3] GIBSON G, COURTIAL J, PADGETT M J, et al. Free-space information transfer using light beams carrying orbital angular momentum[J]. Optics Express, 2004, 12(22): 5448–5456. doi: 10.1364/OPEX.12.005448 [4] WANG Jian, YANG J Y, FAZAL I M, et al. Demonstration of 12.8-bit/s/Hz spectral efficiency using 16-QAM signals over multiple orbital-angular-momentum modes[C]. 2011 37th European Conference and Exhibition on Optical Communication, Geneva, Switzerland, 2011: 1–3. [5] HUANG Hao, REN Yongxiong, YAN Yan, et al. Performance analysis of spectrally efficient free-space data link using spatially multiplexed orbital angular momentum beams[C]. SPIE 8647, Next-Generation Optical Communication: Components, Sub-Systems, and Systems II, San Francisco, USA, 2013: 864706. [6] WANG Jian, LI Shuhui, LI Chao, et al. Ultra-high 230-bit/s/Hz spectral efficiency using OFDM/OQAM 64-QAM signals over Pol-Muxed 22 orbital angular momentum (OAM) modes[C]. OFC 2014, San Francisco, USA, 2014: 1–3. [7] CHEN Rui, ZHOU Hong, MORETTI M, et al. Orbital angular momentum waves: Generation, detection, and emerging applications[J]. IEEE Communications Surveys & Tutorials, 2020, 22(2): 840–868. doi: 10.1109/COMST.2019.2952453 [8] 廖希, 周晨虹, 王洋, 等. 面向无线通信的轨道角动量关键技术研究进展[J]. 电子与信息学报, 2020, 42(7): 1666–1677. doi: 10.11999/JEIT190372LIAO Xi, ZHOU Chenhong, WANG Yang, et al. A survey of orbital angular momentum in wireless communication[J]. Journal of Electronics &Information Technology, 2020, 42(7): 1666–1677. doi: 10.11999/JEIT190372 [9] 邹丽, 王乐, 张士兵, 等. 基于波前校正的轨道角动量复用通信系统抗干扰研究[J]. 通信学报, 2015, 36(10): 76–84. doi: 10.11959/j.issn.1000-436x.2015264ZOU Li, WANG Le, ZHANG Shibing, et al. Compensation of orbital-angular-momentum multiplexed communication system with wavefront correction[J]. Journal on Communications, 2015, 36(10): 76–84. doi: 10.11959/j.issn.1000-436x.2015264 [10] ZOU Li, WANG Le, ZHAO Shengmei, et al. Turbulence mitigation scheme based on multiple-user detection in an orbital-angular-momentum multiplexed system[J]. Chinese Physics B, 2016, 25(11): 114215. doi: 10.1088/1674-1056/25/11/114215 [11] ZHAO Shengmei, WANG Le, ZOU Li, et al. Both channel coding and wavefront correction on the turbulence mitigation of optical communications using orbital angular momentum multiplexing[J]. Optics Communications, 2016, 376: 92–98. doi: 10.1016/J.OPTCOM.2016.04.075 [12] ZOU Li, WANG Le, and ZHAO Shengmei. Turbulence mitigation scheme based on spatial diversity in orbital-angular-momentum multiplexed system[J]. Optics Communications, 2017, 400: 123–127. doi: 10.1016/J.OPTCOM.2017.05.022 [13] ZHANG Yan, WANG Ping, GUO Lixin, et al. Performance analysis of an OAM multiplexing-based MIMO FSO system over atmospheric turbulence using space-time coding with channel estimation[J]. Optics Express, 2017, 25(17): 19995–20011. doi: 10.1364/OE.25.019995 [14] YOUSIF B B and ELSAYED E E. Performance enhancement of an orbital-angular-momentum-multiplexed free-space optical link under atmospheric turbulence effects using spatial-mode multiplexing and hybrid diversity based on adaptive MIMO equalization[J]. IEEE Access, 2019, 7: 84401–84412. doi: 10.1109/ACCESS.2019.2924531 [15] WANG Lei, JIANG Fa, CHEN Mingkai, et al. Interference mitigation based on optimal modes selection strategy and CMA-MIMO equalization for OAM-MIMO communications[J]. IEEE Access, 2018, 6: 69850–69859. doi: 10.1109/ACCESS.2018.2880988 [16] DEDO M I, WANG Zikun, GUO Kai, et al. Retrieving performances of vortex beams with GS algorithm after transmitting in different types of turbulences[J]. Applied Sciences, 2019, 9(11): 2269. doi: 10.3390/app9112269 [17] AMHOUD E M, TRICHILI A, OOI B S, et al. OAM mode selection and space-time coding for atmospheric turbulence mitigation in FSO communication[J]. IEEE Access, 2019, 7: 88049–88057. doi: 10.1109/ACCESS.2019.2925680 [18] SONG Haoqian, SONG Hao, ZHANG Runzhou, et al. Experimental mitigation of atmospheric turbulence effect using pre-signal combining for Uni- and Bi-directional free-space optical links with two 100-Gbit/s OAM-multiplexed channels[J]. Journal of Lightwave Technology, 2020, 38(1): 82–89. doi: 10.1109/JLT.2019.2933460 [19] VASNETSOV M V, PAS'KO V A, and SOSKIN M S. Analysis of orbital angular momentum of a misaligned optical beam[J]. New Journal of Physics, 2005, 7(1): 46. doi: 10.1088/1367-2630/7/1/046 [20] 黎芳, 江月松, 唐华, 等. 光束偏移对轨道角动量信息传输系统的影响[J]. 物理学报, 2009, 58(9): 6202–6209. doi: 10.7498/APS.58.6202LI Fang, JIANG Yuesong, TANG Hua, et al. Influences of misaligned optical beam carrying orbital angular momentum on the information transfer[J]. Acta Physica Sinica, 2009, 58(9): 6202–6209. doi: 10.7498/APS.58.6202 [21] KHALIGHI M A and UYSAL M. Survey on free space optical communication: A communication theory perspective[J]. IEEE Communications Surveys & Tutorials, 2014, 16(4): 2231–2258. doi: 10.1109/COMST.2014.2329501 [22] 张明明. 离轴涡旋光束的传输特性研究[D]. [硕士论文], 南京理工大学, 2014. doi: 10.7666/d.Y2520561.ZHANG Mingming. Study on the propagation characteristics of off-axis vortex beams[D]. [Master dissertation] Nanjing University of Science and Technology, 2014. doi: 10.7666/d.Y2520561. [23] BRIANTCEV D, TRICHILI A, OOI B S, et al. Crosstalk suppression in structured light free-space optical communication[J]. IEEE Open Journal of the Communications Society, 2020, 1: 1623–1631. doi: 10.1109/OJCOMS.2020.3029116 [24] LOU Hanqiong, GE Xiaohu, and LI Qiang. The new purity and capacity models for the OAM-mmWave communication systems under atmospheric turbulence[J]. IEEE Access, 2019, 7: 129988–129996. doi: 10.1109/ACCESS.2019.2940691 [25] HAZAN T and SHASHUA A. Norm-product belief propagation: Primal-dual message-passing for approximate inference[J]. IEEE Transactions on Information Theory, 2010, 56(12): 6294–6316. doi: 10.1109/TIT.2010.2079014 [26] WEISS Y, YANOVER C, and MELTZER T. MAP estimation, linear programming and belief propagation with convex free energies[J]. arXiv: 1206.5286, 2012. -
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