| 摘要: |
| 为解决海上远距离通信给甚高频数据交换系统（VDES）地面子系统带来的严重多径干扰，将正交频分复用（OFDM）技术融入VDES 地面子系统，在协议框架下完成对系统物理层时隙结构的设计，利用OFDM 技术优越的抗多径性能解决VDES 地面子系统存在的严重多径干扰问题。首先，在VDES 地面子系统基础框架下，设计融合了OFDM 技术的VDES 地面子系统完整底层链路系统，并确保各子模块基础性能不差于建议书提供的需求指标。然后，利用MATLAB 软件对系统开展了在逼近循环前缀（CP）大小的极限时延下多径信道环境的仿真测试，结果表明在大时延多径信道环境下系统仍具有很好的抗多径性能，且传输速率略高于当前VDES 标准协议参数。最后，完成了系统的硬件设计并于大连海域完成海上实测，系统最大极限空口速率可达312.7 kbit/s。研究表明，把OFDM 技术引入到VDES 系统，对于帮助VDES 系统对抗多径干扰，提升系统稳健性有相当重要的作用，这也是VDES 系统发展需要探索的方向之一。 |
| 关键词: 海上远距离通信 甚高频数据交换（VDES）地面子系统 正交频分复用 抗多径干扰 |
| DOI： |
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| 基金项目:国家自然科学青年基金资助项目（61401193）；湖南省教育厅科学研究项目（15C1195）；南华大学博士科研启动基金项目（2013XQD03） |
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| Design of an OFDM-based VDES ground subsystem |
| ZHANG Feng,WANG Minghua,ZHU Lihua |
| (School of Electrical Engineering,University of South China，Hengyang 421001，China) |
| Abstract: |
| Multipath interference in long-distance maritime communication systems is serious.To solve this problem,a novel design based on Orthogonal Frequency Division Multiplexing(OFDM) in the VHF Data Exchange System(VDES) ground subsystem is proposed.The new design merges OFDM into the VDES ground subsystem and rebuilds the slots based on framework of protocol.It can improve the reliability and validity of the system by the superior anti-multipath capability of OFDM.Firstly,a link model of VDES ground subsystem is designed which is under the standard constraints of VDES ground subsystem and the performance is not inferior to protocol requirements.Then the system is simulated by MATLAB in a multi-path channel environment and the time delay approximating cyclic prefix(CP).The results show that the system still has excellent anti-multipath performance and higher spectrum efficiency when working in a multipath channel environment with larger delay.Finally,the hardware design and its maritime test have been completed,and the maximum air interface rate of system can reach 312.7 kbit/s.The research shows that the new design can improve the anti-multipath performance and robustness of system,and it is one of the directions for future development of VDES system. |
| Key words: long-distance maritime communication VHF data exchange system(VDES) ground subsystem orthogonal frequency division multiplexing（OFDM） anti-multipath interference |
《电讯技术》编辑部 