【作者】 黄婷婷；

【导师】 王琳；

【作者基本信息】 厦门大学 ， 通信与信息系统， 2017， 博士

【摘要】 面向2020年及未来,物联网(IoT)将会呈指数式增长并成为未来通信发展的主要驱动力之一。作为物联网关键技术之一的短距离无线通信技术将以第五代移动通信(5G)为支撑,实现高吞吐量,低功耗的绿色环保通信。由于混沌信号具有宽带、类似白噪声等特性,且混沌系统具有低成本,低功耗,低复杂度等优点,近年来,基于混沌的超宽带(UWB)技术受到广泛关注,并被多种短距离无线通信应用网列入标准中。因此研究高吞吐量混沌通信系统具有深远的意义。本文对高吞吐量差分混沌移位键控(DCSK)通信系统的收发机进行设计,并对差分混沌移位键控超宽带系统的覆盖范围进行分析,主要工作包括以下几个方面:(1)在基于Walsh码的混沌多维调制系统中,针对经典多元DCSK(M-ary DCSK)系统带宽与传输比特数呈指数增长关系的缺点,本文利用Walsh码码分复用功能,提出了一种速率可变的码分复用DCSK调制方法(MCS-DCSK),该方法用正交的Walsh码分别承载了混沌参考信号和混沌信息信号,因而在传输相同比特数的前提下,系统对带宽的需求不再呈指数增长,系统带宽效率大大提升。同时,本文统计了 M-ary DCSK和MCS-DCSK系统加法器和乘法器数量并以此作为评估两个系统复杂度的标准,比较结果显示:MCS-DCSK系统的复杂度大大降低。此外,在相同的带宽效率下,MCS-DCSK系统误码率性能可以和M-ary DCSK系统相媲美。最后,采用高斯近似(GA)方法分析了 MCS-DCSK系统的误码率性能(BER),并通过仿真验证了系统的可行性。(2)为进一步提高混沌通信系统的吞吐量,本文以正交频分复用(OFDM)技术为基础,将混沌信号和多载波调制结合,采用二维星座映射提出了一种基于子载波相关性的多载波多元混沌移位键控系统（MM-DCSK),该系统充分利用了相邻子载波之间的高度相关性,将混沌参考信号与混沌信息信号分别放置于相邻子载波中,因而,与传统DCSK系统相比,该系统的能量效率大大提升。此外,在分析MM-DCSK系统的峰均比(PAPR)性能时发现:输入序列符号间的欧氏距离与系统PAPR性能有直接关联。当符号间的欧氏距离较大时,系统PAPR性能优越。针对以上发现,本文以增大符号间的欧氏距离为准则,提出了一种简单的PAPR减低方法,实验证明该算法能有效地降低系统的PAPR,当调制阶数较大时,PAPR降低效果更加明显。(3)以室内传输技术对覆盖范围的需求为驱动,本文以正交的混沌信号作为二维星座映射的基函数,提出了一种具有传输参考(TR)结构的多载波多元差分混沌移位键控(MC-MDCSK)系统,该系统获得了频率分集,并且发现该系统对循环前缀的长度变化不敏感。因而,可以通过缩短循环前缀长度提高系统的传输效率。接着提出了 FM MC-MDCSK UWB系统,并在IEEE.802.15.4a标准信道下分析系统覆盖范围,研究结果表明:延长混沌脉冲符号的持续时间可以提升系统的覆盖范围。最后,本文发现在误码率性能约束下该系统存在最佳带宽。更多还原

【Abstract】 By 2020,the Internet of Things(IoT)will grow exponentially.As one of the key technologies of the IoT,the short-range wireless communication technology based on the 5th generation(5G)wireless networks is to achieve high-throughput with low-power consumption in green communications.Recently,the chaotic ultra-wideband(UWB)technology has been widely concerned about,and it has been included in some Institute of Electrical and Electronics Engineers(IEEE)standards.Therefore,it is significant to study key technology of high-throughput differential chaotic shift keying(DCSK)systems.In this paper,the transmitter and receiver of high-throughput DCSK systems are designed and analyzed,and the coverage of the DCSK based UWB systems is researched.The main work of the dissertation includes the following aspects:(1)The M-ary DCSK system is one of the classic Multi-dimensional modulation systems based on Walsh code.However,the bandwidth of M-ary DCSK system grows exponentially as the number of transmitted bits increases.To solve the problem,in this paper,a multilevel code-shifted DCSK(MCS-DCSK)system with rate adaptive is proposed where the Walsh code is used for multiplexing.The complexity of MCS-DCSK system is greatly reduced and the bandwidth efficiency is greatly improved.In addition,under the same bandwidth efficiency,the bit error rate(BER)performance of MCS-DCSK system is better than that of M-ary DCSK system.Finally,the BER performance of MCS-DCSK system is analyzed by employing Gaussian approximation(GA)method,and the feasibility of the system is verified by simulations.(2)To further improve the throughput of DCSK system,a multi-carrier chaotic shift keying system(MM-DCSK)combining orthogonal frequency division multiplexing(OFDM)with chaotic modulation is proposed,where subcarrier correlation is employed and two-dimensional constellation mapping is used.By employing the high correlation between adjacent subcarriers,the chaotic reference signal and the information signal are palced in adjacent subcarriers,respectively.Thus,the energy efficiency is greatly increased compared with conventional DCSK system.In addition,the time diversity is achieved.Finally,the PAPR performance of MM-DCSK system is researched,and a simple PAPR reduction algorithm is proposed.Simulation results show that the proposed algorithm can effectively reduces the PAPR.(3)Driven by incresing demand for indoor transmision,a transmitted-reference multi-carrier differential chaotic shift keying(MC-MDCSK)system is proposed,where the orthogonal chaotic signals are used as basis functions for two-dimensional constellation mapping.The simulated results show that the frequency diversity is obtained,and the system performance is insensitive to the length of the cyclic prefix(CP).Then the coverage of FM MC-MDCSK UWB system over IEEE.802.15.4a standard channel is analyzed.It is shown that by extending the chaotic pulse duration the coverage of the system can be improved.Finally,there is an optimal bandwidth for a specific BER performance in the system.更多还原