基于字典设计的正交线性调频信号复用水声通信系统  

Dictionary Design Based Orthogonal Chirp Division Multiplexing Underwater Acoustic Communication System

作　　者：付晓梅 马馨玉 王思宁 崔俊飞 Fu Xiaomei;Ma Xinyu;Wang Sining;Cui Junfei(School of Marine Science and Technology,Tianjin University,Tianjin 300072,China)

机构地区：[1]天津大学海洋科学与技术学院,天津300072

出　　处：《天津大学学报（自然科学与工程技术版）》2022年第7期682-689,共8页Journal of Tianjin University：Science and Technology

基　　金：天津市技术创新引导专项基金资助项目(21YDTPJC00850);国家自然科学基金资助项目(61571323).

摘　　要：基于离散菲涅耳变换的正交线性调频信号复用技术(OCDM)具有一定的抗多径能力,近年来成为极具潜力的水声多载波通信方法.然而,由于水声信道严重的多径扩展和多普勒扩展,降低了OCDM水声通信系统可靠性,限制了OCDM应用于水声通信系统的可行性.为了增强OCDM水声通信系统的抗多径和抗多普勒能力,可以通过改变载波的时频特性以提高OCDM适应信道环境能力,而改变载波的时频特性可以通过信号分析领域的字典设计来实现.通过把OCDM系统中的菲涅耳变换矩阵等效为信号分析领域中的字典矩阵,将字典设计引入到多载波调制矩阵设计,以改变载波的时频特性,提出了基于字典设计的正交线性调频信号复用(Dic-OCDM)水声通信系统.利用字典设计中的线性变换方法,通过合理设计字典原子,对间隔更大的线性调频原子重新排列,并保持矩阵维度不变,既能保留OCDM系统中线性调频信号抗多径能力,又能在增大Dic-OCDM系统子载波间隔的同时保证调制符号长度不变,进而能够有效抵抗水声信道多径扩展和多普勒扩展.仿真实验验证了Dic-OCDM系统抗多径扩展和多普勒扩展能力,尤其在循环前缀不足和多普勒扩展严重情况下,Dic-OCDM系统误码率性能均优于正交频分复用(OFDM)系统和OCDM系统,同时在欠载条件下,Dic-OCDM性能进一步提高.湖试实验测试了3个系统的误码率性能,进一步验证了Dic-OCDM系统的有效性.Orthogonal chirp division multiplexing(OCDM)is based on discrete Fresnel transform,and it has the antimultipath capability.In recent years,OCDM has been considered a promising underwater acoustic multicarrier communication method.However,because of severe multipath and Doppler spread in underwater acoustic(UWA)channels,the reliability and feasibility of the OCDM underwater acoustic communication system have severely degenerated.Aimed at the antimultipath and anti-Doppler capabilities of the OCDM underwater acoustic communication system,the time-frequency characteristics of carriers can be transformed to ensure that the OCDM can adapt to the channel environment,which can be achieved by dictionary design in the field of signal analysis.In this study,the Fresnel transform matrix in OCDM was regarded as the dictionary matrix,and the dictionary design was introduced into the multicarrier modulation matrix design to develop the dictionary design based orthogonal chirp division multi-plexing(Dic-OCDM)underwater acoustic communication system.Through the translation operation in dictionary design,the chirp atoms with large spacing were rearranged reasonably,with the dimension of the matrix remaining unchanged,i.e.,the Dic-OCDM system can not only inherit the antimultipath capability of the chirp signal in the OCDM but also increase the subcarrier spacing.Meanwhile,the Dic-OCDM system can ensure that the modulation symbol length is unchanged.Thus,the Dic-OCDM effectively resists severe multipath and Doppler spread.Simula-tions verified the antimultipath and anti-Doppler capabilities of the Dic-OCDM system,and the bit error rate(BER)of the Dic-OCDM system is better than those of the orthogonal frequency division multiplexing and OCDM systems,particularly in the case of insufficient cyclic prefix and severe Doppler spread.The performance of under-load Dic-OCDM is further improved.The BER performance of the three systems was tested in the lake experiments,which further verified the effectiveness of the Dic-OCDM system.

关 键 词：水声通信 多载波通信 正交线性调频信号复用技术 正交频分复用技术 字典设计 

分 类 号：TN929.3[电子电信—通信与信息系统]