CPM的SC-FDE技术的研究与实现

发布时间：2019-05-07 10:04

【摘要】：连续相位调制(CPM)具有恒包络和高频谱效率的优良特性,具有广阔的应用前景,尤其是在幅度衰落信道中实现高数据传输速率,但是在衰落信道下,接收端均衡器的设计非常困难,时域均衡的复杂度非常高。而单载波频域均衡(SC-FDE)技术是消除码间干扰的一种有效方法,结合CPM和频域均衡技术,不仅具有SC-FDE技术复杂度低的优点,而且保持了CPM恒包络与频谱效率高的优势,充分发挥了两者的优势,本文研究并实现了基于CPM的SC-FDE技术。本文的内容概述如下：首先,对无线通信的发展历程进行了回顾,总结了CPM技术与SC-FDE技术的发展现状及未来的趋势。其次,研究了CPM以及SC-FDE的基本原理。研究了CPM的调制原理和解调原理,介绍了基于Viterbi算法(VA)的最大似然序列检测(MLSD)方法,并对CPM信号各种变量与系统误比特率(BER)之间的关系做了仿真。研究了正交频分复用(OFDM)和SC-FDE的基本理论并从理论上对SC-FDE以及OFDM技术做了对比。同时研究了单载波系统在频域进行线性均衡的基本算法,对这两种算法进行了推导和证明。SC-FDE相比OFDM具有峰均比(PAPR)较小,且对载波频率偏移不敏感的特性,是通信系统中的对抗多径干扰的一种有效方法。在此基础上,把CPM和SC-FDE技术相结合,对其存在的主要问题做了深入分析。通过相位归零法对帧格式重新设计保证了插入循环前缀(CP)后相位的连续性；通过对CPM信号进行离散线性分解,使CPM信号可以变换到频域从而在频域完成均衡。深入研究了两种分解方式及如何将SC-FDE应用于CPM技术中,之后对均衡的性能在COST-207信道模型下进行了仿真分析。这之后研究了一种适用于特定调制指数的预编码CPM系统的SC-FDE算法,在数据进行CPM调制前先进行差分预编码,该算法在不增加复杂度的情况下,使系统的误比特率降低了将近一半。最后,将FDE的算法用Verilog HDL来描述,进行了FPGA的设计,并利用Xilinx ISE以及Modelsim软件对算法做了模拟,通过与Matlab仿真数据的对比,可以看出此硬件设计是可行的且具有不错的性能。
[Abstract]:Continuous phase modulation (CPM) (CPM) has the characteristics of constant envelope and high spectral efficiency. It has broad application prospects, especially in amplitude fading channels to achieve high data transmission rate, but in fading channels, it has a wide range of applications. The design of receiver equalizer is very difficult, and the complexity of time domain equalization is very high. Single carrier frequency domain equalization (SC-FDE) is an effective method to eliminate inter-symbol interference (ISI). Combining CPM and frequency domain equalization, it not only has the advantages of low complexity of SC-FDE technology, but also keeps the advantages of CPM constant envelope and high spectral efficiency. After giving full play to the advantages of both, this paper studies and implements the SC-FDE technology based on CPM. The contents of this paper are summarized as follows: firstly, the development process of wireless communication is reviewed, and the development status and future trend of CPM and SC-FDE technology are summarized. Secondly, the basic principles of CPM and SC-FDE are studied. The modulation principle and demodulation principle of CPM are studied. The maximum likelihood sequence detection (MLSD) method based on Viterbi algorithm (VA) is introduced. The relationship between the variables of CPM signal and the bit error rate (BER) of the system is simulated. The basic theories of orthogonal Frequency Division Multiplexing (OFDM) and SC-FDE (orthogonal Frequency Division Multiplexing) are studied and the SC-FDE and OFDM technologies are compared theoretically. At the same time, the basic algorithm of linear equalization in frequency domain for single carrier system is studied, and the two algorithms are deduced and proved. Compared with OFDM, SC-FDE has a smaller peak-to-average ratio than (PAPR) and is not sensitive to carrier frequency offset. It is an effective method to resist multipath interference in communication system. On this basis, the combination of CPM and SC-FDE technology, the main problems of its in-depth analysis. The frame format is redesigned by the phase return-to-zero method to ensure the continuity of the phase after inserting the cyclic prefix (CP), and the discrete linear decomposition of the CPM signal enables the CPM signal to be transformed into the frequency domain to achieve equalization in the frequency domain. In this paper, two kinds of decomposition methods and how to apply SC-FDE to CPM technology are deeply studied. Then the performance of equalization is simulated and analyzed under the COST-207 channel model. After that, a SC-FDE algorithm for a precoded CPM system with specific modulation index is studied. The differential precoding is performed before the data is modulated by CPM. The algorithm does not increase the complexity of the algorithm. It reduces the bit error rate of the system by nearly half. Finally, the algorithm of FDE is described by Verilog HDL, and the design of FPGA is carried out. The algorithm is simulated by Xilinx ISE and Modelsim software. Compared with the simulation data of Matlab, the hardware design is feasible and has good performance.
【学位授予单位】：西安电子科技大学
【学位级别】：硕士
【学位授予年份】：2014
【分类号】：TN911.3

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