LTE系统峰均比抑制技术及实现

发布时间：2018-07-07 16:31

本文选题：长期技术演进 + 正交频分复用　；参考：《电子科技大学》2014年硕士论文

【摘要】：LTE技术是以正交频分复用(OFDM)为技术核心。OFDM是适用于无线环境下的高速传输技术,它具有速率高、抗干扰性强等特点。以OFDM为核心的LTE技术体制不仅可以应用于民用移动通信,也可以应用于各类专网,比如集群通信、应急通信、军事专网等。然而,基于OFDM的多载波系统由于多个子载波的叠加造成较大的峰值信号,具有较高的峰均比(PAPR)。这要求系统内的模拟器件要有较大的线性区间,发送端的功率放大器线性度要求很高,如果采用功率回退会导致功放的效率非常低,在工程上造成系统散热困难等问题。降低峰均比,是OFDM系统必须要解决的问题,尤其是针对有小型化、低功耗化要求的产品。鉴于上面的情况,本文首先研究了LTE系统,从LTE系统下行链路的帧结构出发,讨论了物理层的信号处理过程,提出了多种仿真场景,分析了LTE系统峰均较高的原因。针对目前多种峰均比抑制技术,比如限幅法、压缩扩展技术、选择映射法、部分传输序列法、星座扩展法、编码法、信号空间扩展技术、交织限幅法、子载波预留技术等等,对各类算法进行了介绍,并分析了各类算法的优点和缺点。通过充分比较,结合LTE下行链路峰均比抑制要求,以及在工程上实现的难易程度和代价,研究了峰值脉冲抵消削峰(PC-CFR)算法。将该算法模块应用到LTE系统下行链路,采用MATLAB软件进行仿真,评估其峰均比抑制效果及对系统造成的影响。最后,将该算法在FPGA中实现,通过仿真、板级在线测试,验证其在实际系统的峰均比抑制性能。在LTE下行链路中采用PC-CFR峰均比抑制算法,使系统原本15dB的峰均比降低到7dB,并且系统的信噪比损失在可接受的范围内。在实际系统中,使用该算法模块,大大降低了系统对功率放大器线性度要求,减轻了系统散热的压力,降低了产品的体积和功耗。
[Abstract]:LTE technology is based on orthogonal Frequency Division Multiplexing (OFDM). OFDM is a high-speed transmission technology suitable for wireless environment. It has the characteristics of high rate and strong anti-jamming. The LTE system with OFDM as the core can not only be applied to civil mobile communication, but also to all kinds of private networks, such as trunking communication, emergency communication, military private network and so on. However, the multi-carrier system based on OFDM has a high PAPR because of the large peak signal caused by the superposition of multiple sub-carriers. This requires the analog devices in the system to have a large linear range, and the linearity of the power amplifier at the transmitter is very high. If the power retrogression is adopted, the efficiency of the power amplifier will be very low and the system heat dissipation will be difficult in engineering. Reducing PAPR is a problem that must be solved in OFDM systems, especially for products with miniaturization and low power consumption. In view of the above situation, this paper first studies the LTE system. Based on the frame structure of the downlink of the LTE system, the signal processing process of the physical layer is discussed, and various simulation scenarios are proposed, and the reasons for the high peak of the LTE system are analyzed. Aiming at various PAPR suppression techniques, such as limiting, compression and expansion, selective mapping, partial transmission sequence, constellation expansion, coding, signal spatial expansion, interleaving and limiting, subcarrier reservation, etc. Various algorithms are introduced and their advantages and disadvantages are analyzed. In this paper, the peak pulse cancellation (PC-CFR) algorithm is studied by comparing the PAPR suppression requirements of LTE downlink, as well as the difficulty and cost of engineering implementation. The algorithm module is applied to the downlink of LTE system. MATLAB software is used to simulate the algorithm to evaluate the PAPR suppression effect and its impact on the system. Finally, the algorithm is implemented in FPGA, and its PAPR suppression performance is verified by simulation and on-line testing at board level. PC-CFR suppression algorithm is used in LTE downlink to reduce the PAPR of 15 dB to 7 dB, and the SNR loss of the system is within an acceptable range. In the practical system, the algorithm module can greatly reduce the linearity of the power amplifier, reduce the pressure of the system heat dissipation, and reduce the volume and power consumption of the product.
【学位授予单位】：电子科技大学
【学位级别】：硕士
【学位授予年份】：2014
【分类号】：TN929.5

【参考文献】