5G通信上行链路中的滤波器组多载技术研究

发布时间：2018-05-08 18:38

本文选题：FBMC + OFDM　；参考：《北京交通大学》2017年硕士论文

【摘要】：5G通信的迅速发展和场景的多样化对上行通信链路的传输提出了更高的要求:希望能够实现更多设备之间的随时随地的互联、获得更快的数据速率、达到更高的系统容量、消耗更小的终端功耗以及具有更低的传输时延等。正交频分复用技术(Orthogonal Frequency Division Multiplexing,OFDM)因对同步要求高、旁瓣大和频谱资源利用率较低等限制已不能满足5G通信的新需求。滤波器组多载波技术(Filter Bank Multicarrier,FBMC)是5G物理层研究的关键技术之一,作为一种非正交波形技术,它具有频谱效率高、旁瓣小和时频聚焦性好等特点。目前,5G应用的波形技术仍没有定论,评判新波形技术需要考虑的因素亦呈多样性;FBMC在5G上行链路的研究仍处于理论研究阶段,FBMC在该场景下性能缺乏完整的链路级仿真的验证;针对多用户传输中存在的时频异步的问题,FBMC对同步误差的鲁棒性能仍缺乏充分验证;FBMC应用于上行链路时,抑制其高峰均功率比(Peak to Average Power Ratio,PAPR)的方案目前有多种,但各种方案的有效性和复杂度仍有待评估。针对以上情况,本文通过搭建MATLAB链路级仿真平台对FBMC进行仿真,其中主要工作和具体贡献如下:(1)分析FBMC的发射机和接收机原理,并推导基于奈奎斯特原理的原型滤波器的定义式,分析滚降因子对滤波器的时频聚焦特性的影响,进而得出使用PHYDYAS原型滤波器的优势。分析FBMC和OFDM的功率谱密度,PHYDYAS滤波器组的应用能够有效的减小发射机带外功率泄露。(2)研究FBMC在同步传输场景下的多种性能,首先本文对FBMC和OFDM系统的复杂度进行理论的推导和仿真验证,因为计算复杂度会导致更高的硬件要求和更长的通信时延,因此我们研究重叠因子和傅里叶变换点数对FBMC计算复杂度的影响。进而基于谱效率和时间效率的理论推导,分析FBMC与OFDM的性能差异性,并得出二者对不同长度的数据包的适用性。最后分析应用不同调制阶数的两种波形技术对上行通信系统误块概率和吞吐量的影响。(3)对5G上行多用户异步场景进行建模,分别研究符号偏差和频率偏差对通信系统的影响,定量分析FBMC对同步误差的鲁棒性。分析相邻用户间的保护带宽对通信系统的影响,时频聚焦性较好的原型滤波器有助于减小保护子载波的开销且有效提高频谱资源的利用率。(4)基于两种已有的PAPR抑制方案——即基于离散傅里叶变换(Discrete Fourier Transform,DFT)的扩展方案和基于滤波器组(Filter Bank,FB)的扩展方案来降低FBMC的PAPR,分析这两种方案在实现原理、性能和复杂度的差异性。
[Abstract]:The rapid development of 5G communication and the diversification of scenarios put forward higher requirements for uplink transmission: it is hoped that more devices can be interconnected at any time, anywhere and anytime, and faster data rates can be obtained to achieve higher system capacity. Lower terminal power consumption and lower transmission delay. Orthogonal Frequency Division Multiplexing (OFDM) can not meet the new requirements of 5G communication due to its high requirement for synchronization, large sidelobe and low utilization of spectrum resources. Filter Bank Multicarrier Bank (FBMC) is one of the key techniques in the 5G physical layer research. As a non-orthogonal waveform technology, it has the characteristics of high spectral efficiency, small sidelobe and good time-frequency focusing. At present, the waveform technology of 5G application is still uncertain, and the factors to be considered in judging the new waveform technology are also diverse. The research of FBMC in 5G uplink is still in the theoretical research stage, and the performance of FBMC in this scenario is not verified by link level simulation. Aiming at the problem of time-frequency asynchronous in multi-user transmission, the robust performance of FBMC against synchronous error is still not fully verified. When FBMC is used in uplink, there are many schemes to suppress its peak to Average Power ratio (PAPR). However, the effectiveness and complexity of various schemes still need to be evaluated. In view of the above situation, this paper simulates FBMC by building MATLAB link-level simulation platform, in which the main work and specific contribution are as follows: (1) analyzing the transmitter and receiver principle of FBMC. The definition of prototype filter based on Nyquist principle is derived, and the influence of rolling factor on the time-frequency focusing characteristic of filter is analyzed, and the advantage of using PHYDYAS prototype filter is obtained. This paper analyzes the power spectral density of FBMC and OFDM. The application of PHYDYAS filter bank can effectively reduce the out-of-band power leakage of transmitter. First of all, the complexity of FBMC and OFDM systems is theoretically deduced and verified by simulation, because the computational complexity will lead to higher hardware requirements and longer communication delay. So we study the influence of overlap factor and Fourier transform points on the computational complexity of FBMC. Then, based on the theoretical derivation of spectral efficiency and time efficiency, the difference of performance between FBMC and OFDM is analyzed, and their applicability to data packets of different lengths is obtained. Finally, the effects of two waveform techniques of different modulation order on the block error probability and throughput of uplink communication system are analyzed. The 5G uplink multi-user asynchronous scene is modeled, and the effects of symbol deviation and frequency deviation on the communication system are studied respectively. The robustness of FBMC to synchronization error is quantitatively analyzed. The influence of the protection bandwidth between adjacent users on the communication system is analyzed. A prototype filter with better time-frequency focusing can reduce the cost of protecting subcarriers and improve the efficiency of spectrum resources efficiently. It is based on two existing PAPR suppression schemes: discrete Fourier transform (DFT) based on discrete Fourier transform (DFT). The scheme and the extended scheme based on filter bank are used to reduce the FBMC, and the implementation principle of these two schemes is analyzed. The difference between performance and complexity.
【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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