【作者】 胡力；

【导师】 李少谦；

【作者基本信息】 电子科技大学 ， 通信与信息系统， 2019， 硕士

【摘要】 射频(Radio Frequency,RF)功率放大器(Power Amplifiers,PA)是无线通信系统中发射机后端部分最重要的部件。同时也是无线通信系统中能耗最高的器件,其工作效率在很大程度上决定了整个通信系统的能耗。因此,在提倡节约能源与保护环境的背景下,研究基于高效功率放大器的信号调制技术具有很重要的理论与实践意义。本文首先介绍了研究背景和意义,分析了关于提升功率放大器效率的研究现状。从信号的调制技术及功率放大器的工作特性出发,本文研究了两种基于高效功率放大器的信号调制方案。两种信号调制方案都能提升功率放大器的工作效率,从而降低整个通信系统的功耗。本文的具体工作如下:第一章阐述论文研究背景和意义,分析了关于提升功率放大器效率的研究现状,简要介绍了射频功率放大器,并给出了本文的主要研究内容和结构安排。第二章研究了基于开关型功放(Switching Mode Power Amplifiers,SMPA)的信号调制技术。本章首先分别介绍了正交调制及脉冲宽度调制(Pulse Width Modulation,PWM)的原理。通过将两种调制方式结合,使得功率放大器的输入信号是方波信号,这样就可以利用效率较高的开关型功放,提升功率放大器的能量效率。本章给出了这种信号调制方案的系统框图,并对其信号频谱特性及误比特率(Bit Error Rate,BER)性能进行了仿真分析。第三章研究了应用于MIMO系统的多维超球面相位调制(Phase Modulation on the Hypersphere,PMH)技术。本章首先给出了单射频MIMO系统中PMH调制的系统框图,信号特点。PMH调制的信号星座图位于多维超球面上,因此中心射频功放的输入信号是恒包络的。根据功率放大器的工作特性可知,低峰均比(Peak-to-Average Power Ratio,PAPR)的输入信号能够保证更高的工作效率。本章给出了基于K均值(K-means)聚类算法的码本生成算法,类格雷码的星座图映射算法。研究了常见的几种MIMO信号检测方案,并对比了他们的性能。第四章针对PMH调制解调系统中的最大似然(Maximum Likelihood,ML)检测算法复杂度很高的问题,提出了两种改进方案。其中两级码本及其迭代检测算法虽然能够降低计算复杂度,但是有一定的性能损失,且对信道条件要求苛刻。基于KD树(k-dimension Tree)的信号检测方案能够在不损失性能的情况下降低计算量,只要求信道是平稳的。本章详细介绍了两种算法的原理,分析了两种算法的计算复杂度,通过仿真的方式与ML算法对比了性能及计算量。第五章对全文进行了全面的总结,说明了本文的主要贡献及创新点,并对以后的工作给出了建议。更多还原

【Abstract】 Radio Frequency(RF)Power Amplifiers(PA)is the most important component in the back end of a transmitter in a wireless communication system.It is also the most energy-consuming device in wireless communication systems,and its energy efficiency largely determines the energy efficiency of the entire communication system.Therefore,under the background of promoting energy conservation and protecting the environment,it is of great theoretical and practical significance to study the signal modulation technology based on high efficiency power amplifier.This paper first analyzes the studing background and significance,and introduces the research status of imoving the efficiency of PA.Based on the modulation technology and characteristics of the PA,two signal modulation schemes based on high efficiency PA are studied.Both signal modulation schemes increase the efficiency of the power amplifier,thereby reducing the power consumption of the entire communication system.The detailed descriptions of this article are as follows.Chapter 1 expounds the background and importance of the research,analyzes the research status of improving the efficiency of PA,briefly introduces the RF PA,and gives the main research contents and structure of this paper.Chapter 2 studies the signal modulation technology based on switching mode power amplifiersignal(SMPA).This chapter first introduces the principle of quadrature and Pulse Width Modulation(PWM).By combining the two modulation methods,the inputs of the PA are square wave signals,so that we can improve energy efficiency of the PA by using a higher efficiency switch type PA.This chapter gives a system block diagram of this signal modulation scheme,and simulates the signal spectrum characteristics and bit error rate(BER)performance.Chapter 3 studies the Phase Modulation on the Hypersphere(PMH)technology that can be applied to MIMO systems.This chapter first gives a system block diagram of single-RF MIMO system and signal characteristics of PMH.The signal constellation of the PMH is located on the multi-dimensional hypersphere,so the input signal of the central RF PA is constant envelope.According to characteristics of the PA,low Peak-to-Average Power Ratio(PAPR)of inputs can ensure higher efficiency.This chapter presents a codebook generation algorithm based on K-means clustering algorithm and a constellation mapping algorithm based on Gray code.This chapter studies several common MIMO signal detection schemes and compared their performance.Chapter 4 proposes two improved schemes for the problem of high complexity of Maximum Likelihood(ML)detection algorithm in PMH system.Among them,the two-stage codebook and its iterative detection algorithm can reduce the computational complexity,but have a certain performance loss and are demanding on channel conditions.The KD-Tree-based signal detection scheme can reduce the amount of calculation without losing performance,but only requires the channel to be stable.The principle of the two algorithms is introduced in detail,and the computational complexity of the two algorithms is analyzed.The performance and calculation amount are compared with the ML algorithm by simulation.Chapter 5 gives a comprehensive summary of the paper,explains the main contributions and innovations of this paper,and gives suggestions for future work.更多还原