第五代移动通信上行波形和多址技术研究

发布时间：2018-04-28 21:40

本文选题：5G + 频谱效率　；参考：《北京交通大学》2017年硕士论文

【摘要】：随着通信技术的飞速发展,5G时代已经到来,对于通信系统的要求也随之越来越高。更高的传输速率,超大规模的用户容量,超低的通信时延,更好的用户体验,以及更高的频谱利用率等等特点。本文主要针对提高频谱效率,以及大规模用户通信两个场景进行讨论。对于提高频谱效率,正交频分复用(OFDM)技术作为一种重要的多载波技术,不仅在4G系统中得到了广泛使用,而且作为5G系统的重要候选波形之一仍然被众多研究人员所推崇。但是与前几代移动通信系统相比,5G系统设计时不仅要考虑移动宽带业务,同时也会考虑未来对于海量机器连接以及高可靠低时延业务的支持。OFDM存在一些固有的缺点:比如对于频率同步误差,时间非同步,多普勒扩展等都比较敏感,所以如果对于未来更加多样化的业务,更高的频谱效率以及海量连接,如果继续仅仅使用OFDM 一种波形技术是不够的。因此本文主要针对于几种新型的OFDM变形技术进行相关的研究比较与理论分析。同时基于LTE链路级平台,分别在不同调制方式,用户干扰、时延、多径、峰值平均功率比/立方度量、误差矢量幅度等几个方面进行相关的仿真验证。展示了在不同情境下,不同波形的优缺点。此外,为了解决大规模用户通信可能产生的拥堵问题,基于竞争的随机接入机制便成为物理层对于未来5G中的一个研究热点。在这种通信模式下,同时多用户传输碰撞会导致信令的扰乱,进而使接收端无法正常的做接收信号的检测。本文针对上述情景设计了一种新型结构的前导序列。可以通过这种具有特定结构的前导序列来检测碰撞用户,同时在碰撞检测的过程中也可以估计信道。本文对提出的前导序列方案在衰落信道,多径信道以及异步等场景进行了理论分析与仿真验证。仿真结果证实了本文提出方案的准确性与鲁棒性。
[Abstract]:With the rapid development of communication technology, the requirement of communication system is becoming higher and higher. Higher transmission rate, large user capacity, ultra-low communication delay, better user experience, and higher spectrum efficiency. This paper mainly discusses the two scenarios of improving spectrum efficiency and large-scale user communication. As an important multicarrier technology, orthogonal Frequency Division Multiplexing (OFDM) is not only widely used in 4G systems, but also one of the important candidate waveforms for 5G systems. However, compared with previous generations of mobile communication systems, the design of the 5G system should not only consider mobile broadband services, At the same time, it will also consider that the future support for mass machine connections and high reliability and low delay traffic. OFDM has some inherent disadvantages: for example, frequency synchronization error, time non-synchronization, Doppler spread and so on are more sensitive. So it is not enough to use only one waveform technology of OFDM for more diversified services, higher spectral efficiency and mass connection in the future. Therefore, this paper mainly focuses on several new OFDM deformation technology related research and theoretical analysis. At the same time, based on the LTE link-level platform, simulations are carried out in different modulation modes, user interference, delay, multipath, peak-to-average power ratio / cubic metric, error vector amplitude and so on. The advantages and disadvantages of different waveforms in different situations are shown. In addition, in order to solve the problem of congestion caused by large-scale user communication, the competition-based random access mechanism has become a research focus in the physical layer for the future 5G. In this communication mode, simultaneous multi-user transmission collision will lead to the disturbance of signaling, which makes the receiver unable to detect the received signal normally. In this paper, a new structure leading sequence is designed for the above scenarios. The collision user can be detected by the preamble sequence with a specific structure, and the channel can be estimated during the collision detection process. In this paper, theoretical analysis and simulation of the proposed preamble scheme in fading channel, multipath channel and asynchronous channel are carried out. Simulation results show that the proposed scheme is accurate and robust.
【学位授予单位】：北京交通大学
【学位级别】：硕士
【学位授予年份】：2017
【分类号】：TN929.5

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