单载波频域均衡研究

发布时间：2018-07-17 02:28

【摘要】：人们的生活随着宽带无线通信技术的迅猛发展发生了很大改变。为提供更优质的通信服务,人们在不断研究探索如何提高通信质量。在高速无线通信中,我们面临的挑战是如何消除多径时延和多普勒效应。目前,由于OFDM技术有较低的复杂度,而且有比较强的抗干扰能力,已经成为当前最流行的技术之一。然而,单载波频域均衡(SC-FDE)的抗多径性能和实现复杂度,与OFDM相似。而且,SC-FDE具有低峰均功率比,并克服了频偏敏感特性,已经成为OFDM的强有力竞争对手,经常作为OFDM的备选方案。首先,介绍了无线通信系统的信道特性,分析了无线信道对数字信号传输的影响以及衰落信道的统计模型。讨论了宽带无线信道的动态特征,指出由于多径时间扩散和多普勒扩展引起的时间频率双选择性。分析了仿真用的SUI信道模型,给出了SUI-5信道的时、频特性。其次,介绍了均衡技术的分类、原理、准则和算法,简要介绍了单载波频域均衡的系统结构、基本原理和信道估计。对线性均衡和判决反馈均衡的原理进行了介绍,并对其性能进行了分析评估。最后,本文介绍了块迭代判决反馈均衡器(IBDFE),并进行了仿真分析。基于最小均方误差准则,介绍了一种简化的计算前向和反馈滤波器系数的参数估计方法,明显降低了均衡器的实现复杂度。仿真结果表明,在较低的复杂度的情况下,所改进的简化设计在多径衰落信道中的性能与传统的块迭代判决反馈频域均衡相似。
[Abstract]:People's lives have changed greatly with the rapid development of broadband wireless communication technology. In order to provide better communication service, people are constantly exploring how to improve communication quality. In high-speed wireless communication, the challenge is how to eliminate multipath delay and Doppler effect. At present, OFDM technology has become one of the most popular technologies because of its low complexity and strong anti-jamming ability. However, single-carrier frequency domain equalization (SC-FDE) is similar to OFDM in anti-multipath performance and complexity. Moreover, SC-FDE has low peak-to-average power ratio (PAPR) and overcomes the characteristics of frequency offset sensitivity. It has become a strong competitor of OFDM and is often used as an alternative to OFDM. Firstly, the channel characteristics of wireless communication system are introduced, the influence of wireless channel on digital signal transmission and the statistical model of fading channel are analyzed. The dynamic characteristics of wideband wireless channel are discussed, and the time frequency double selectivity caused by multipath time diffusion and Doppler spread is pointed out. The SUI channel model used in simulation is analyzed, and the time and frequency characteristics of SUI-5 channel are given. Secondly, the classification, principle, criterion and algorithm of equalization are introduced, and the system structure, basic principle and channel estimation of single-carrier frequency domain equalization are briefly introduced. The principle of linear equalization and decision feedback equalization is introduced, and its performance is analyzed and evaluated. Finally, the block iterative decision feedback equalizer (IBDFE) is introduced and simulated. Based on the minimum mean square error criterion, a simplified parameter estimation method for calculating the coefficients of forward and feedback filters is presented, which reduces the complexity of the equalizer obviously. Simulation results show that the performance of the improved simplified design in multipath fading channels is similar to that of traditional block iterative decision feedback frequency-domain equalization under low complexity.
【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】：TN929.5

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