【作者】 范学云；

【导师】 梁德群；

【作者基本信息】 大连海事大学 ， 信息与通信工程， 2010， 硕士

【摘要】 高质量、高速率一直是人们对通信技术的要求,然而,随着网络的普及和通信用户的增多,异常紧张的频带资源已经成为制约通信技术发展的一大障碍。如何压缩信号的频谱,提高频带利用率成为当今研究的热点。早些年提出OFDM以其优越的性能受到人们青睐,一直沿用至今,调制技术再没有突破性的进展。梁德群教授提出的时移非正交多重调制技术(TS-NMT)突破了正交性的限制。通过严格的理论分析及大量的仿真实验,证明了TS-NMT具有比现有的其它调制方法都高的频带利用率。为了更加有效的利用频带资源,窄带、甚至超窄带技术相继被提出,给通信技术的发展提供了新的思路。因为信号的带宽与码元周期成反比,通过加长码元周期就可以压缩信号的带宽,对传统调制方式而言,加长码元周期传输率会随之降低,信号的功率也会加大。但是TS-NMT由于具有时移的特点,能够在信号功率基本不变的前提下,加长码元周期的同时增加子波数以保持传输率不变,从而大大提高频带利用率,我们称这种方法为窄带TS-NMT.本文通过理论推导证明了窄带TS-NMT高频带利用率的合理性。但是加长码元周期会加大信号的初相位延迟和运算的复杂度,为此我们提出了时域分段解调方法,可以有效的解决这两个问题。本文对窄带TS-NMT及分段解调法进行了Matlab仿真实现。TS-NMT的时移非正交性,在带来了高效率的同时也带来了高采样率的代价。在实际系统中,采样率越高要求系统的硬件系统的处理能力越强,这就增加了系统的成本,不利于TS-NMT的推广,频域分段调制解调能够有效地降低TS-NMT的采样率。本文对频域分段法做了理论分析同时完成在5类线信道上的仿真实现。更多还原

【Abstract】 High quality and high transmission speed have always been the request of people to the communications technology. However, along with the popularization of network and increase of correspondence users, spectrum resources are becoming more and more limited over time, it has already become a big barrier which restricts development of communication technology. How to compress the signal’s frequency spectrum, and how to enhance the frequency spectrum using efficiency, have been the popular direction which is researched in communications now. Orthogonal Frequency Division Multiplexing (OFDM) continues to be used until now since it was proposed because of its superior performance. However, the modulation technology does not have the unprecedented progress again for years. Time Shift Non-orthogonal Multi-modulation Technology(TS-NMT for short) was proposed by Professor Liang Dequn can break through the orthogonal limit. Through the strict theoretical analysis and the massive simulation experiment, it is proved that TS-NMT has higher frequency efficiency compared to other modulation systems.For the more effective using frequency resources, the narrow band technology and the ultra narrow band technology has been proposed one after another, which provided a new mentality to communications’development. Because the signal bandwidth is in inverse proportional to signal element period, through lengthen signal element period may compress signal bandwidth. To the tradition modulation system, lengthen signal element period will reduce transfer rate, and the signal power will be also enlarged at the same time. But TS-NMT, because of its time shift characteristic, can keep signal power basically constant, and maintains transfer rate invariable by increasing the wave number. Thus raises frequency efficiency greatly. This method is called narrow band TS-NMT. This article demonstrates rationality of narrow band TS-NMT’ high frequency efficiency characteristic. However, new problems arise from lengthen signal element period.On the one hand it increases the signal’s initial phase delay, on the other hand it enlarged the complexity of operation. Therefore we proposed the time-subsection demodulation method, this method can effective solute these two problems. Narrow band TS-NMT and time-subsection demodulation method are simulated by matlab.While the time shift Non-orthogonal characteristic of TS-NMT brings its high efficiency, also bring its disadvantage of high sampling rate. In the actual system, higher sampling rate requests system’s hardware handling ability stronger, that will increase system’s cost, and disbennifit to the promotion of TS-NMT. The frequency division modulation and demodulation method demodulation r can reduce TS-NMT the sampling rate effectively. This article made the theoretical analysis to this method and complete simulation.更多还原