GFDM系统带外辐射及PAPR抑制技术研究

发布时间：2018-10-05 12:06

【摘要】：目前,移动通信系统已经由4G逐渐向5G的阶段迈进。正交频分复用(Orthogonal Frequency Division Multiplexing,OFDM)技术是4G中应用的核心技术,但其存在诸如:带外辐射高、系统峰均功率比(Peak to Average Power Ratio,PAPR)高、对载波频率偏移(Carrier frequency offset,CFO)十分敏感、无法满足TI系统对短时延的要求,以及V2V(vehicle to vehicle)对数据短脉冲的要求等局限,无法应用于更高要求的5G通信。而由OFDM衍生出来的广义频分复用(Generalized frequency division multiplexing,GFDM)技术研究可以满足5G通信需求,是5G的主要候选技术。本文将对比分析OFDM和GFDM两个系统的带外辐射(Out-of-band radiation,OOB)和峰均功率比(Peak-to-average power ratio,PAPR)。同时针对GFDM系统的高PAPR,应用两种技术进行抑制。具体而言,本文主要研究内容分为三部分:首先,研究GFDM系统基本原理。针对GFDM与OFDM系统主要差异点——脉冲整形滤波器的存在与否,通过仿真相同信号在经过不同滤波器后的误码率来分析比较各种滤波器性能,重点分析研究4种典型脉冲整形滤波器的性能:RC滤波器、RRC滤波器、Xia 1st滤波器、Xia 4th滤波器。最后,对比分析GFDM系统分别在高斯白噪声信道(AWGN)、频率选择性信道(FSC)、瑞利时变信道(TVC)三种信道下,RC滤波器滚降因子改变时系统通信性能。其次,研究GFDM系统两大特性——OOB辐射及PAPR。一方面,将对OFDM系统高带外辐射进行验证,然后仿真GFDM系统的带外辐射。另一方面,对GFDM系统PAPR值的问题展开研究。首先对OFDM系统PAPR值高进行验证性实验,然后仿真GFDM系统PAPR,考察该系统是否存在这一弊病。最后,研究降低GFDM系统PAPR的两种方法。首先研究Clipping技术在OFDM系统中如何抑制PAPR,然后探究Clipping在GFDM系统中是否可以降低PAPR。最后,将CT改进后应用于GFDM系统,考察是否可以降低PAPR,并将其与限幅(Clipping)技术降低PAPR能力进行对比。结果表明,MCT抑制GFDM系统PAPR效果优于Clipping技术。
[Abstract]:At present, the mobile communication system has gradually moved from 4G to 5 G stage. Orthogonal Frequency Division Multiplexing (Orthogonal Frequency Division Multiplexing,OFDM) is the core technology in 4G applications. However, it is sensitive to carrier frequency offset (Carrier frequency offset,CFO) because of its high out-of-band radiation and high peak-to-average power (Peak to Average Power Ratio,PAPR). It can not meet the requirements of TI system for short delay and V2V (vehicle to vehicle) for short data pulses, so it can not be applied to 5G communication with higher requirements. The generalized frequency division multiplexing (Generalized frequency division multiplexing,GFDM) technique derived from OFDM can satisfy the 5G communication requirement and is the main candidate technology of 5G. In this paper, the out-of-band radiation (Out-of-band radiation,OOB) and peak-to-average power ratio (Peak-to-average power ratio,PAPR) of OFDM and GFDM systems are compared and analyzed. At the same time, two technologies are used to suppress the high PAPR, of GFDM system. Specifically, this paper is divided into three parts: firstly, the basic principle of GFDM system is studied. In view of the existence of pulse shaping filter, which is the main difference point between GFDM and OFDM system, the performance of various filters is analyzed and compared by simulating the bit error rate of the same signal after passing through different filters. The performance of four typical pulse shaping filters is analyzed and studied in this paper. The performance of four typical pulse shaping filters: RRC filters / 1st filters / Xia 4th filters are studied. Finally, the communication performance of GFDM system under three channels of Gao Si white noise channel, (AWGN), frequency selective channel, (FSC), Rayleigh time-varying channel, (TVC), and the rolling factor of RC filter is compared and analyzed. Secondly, we study two characteristics of GFDM system OOB radiation and PAPR.. On the one hand, the high out-of-band radiation of OFDM system is verified, and then the out-of-band radiation of GFDM system is simulated. On the other hand, the problem of PAPR value of GFDM system is studied. First, the high PAPR value of OFDM system is verified, and then the GFDM system PAPR, is simulated to investigate whether the system has this disadvantage. Finally, two methods to reduce PAPR in GFDM system are studied. This paper first studies how Clipping technology can suppress PAPR, in OFDM system and then explores whether Clipping can reduce PAPR. in GFDM system. Finally, the improved CT is applied to the GFDM system to investigate whether it can reduce the PAPR, and compare it with the limited (Clipping) technology to reduce the PAPR capability. The results showed that the inhibitory effect of MCT on PAPR of GFDM system was better than that of Clipping technique.
【学位授予单位】：哈尔滨工业大学
【学位级别】：硕士
【学位授予年份】：2016
【分类号】：TN929.5

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