低信噪比短突发通信系统下载波频偏估计算法研究

发布时间：2018-04-05 15:25

本文选题：载波同步　切入点：导频　出处：《西安电子科技大学》2014年硕士论文

【摘要】：随着通信技术的高速发展,在低信噪比、大多普勒频偏等条件下,数据可以进行高速率的正确传输是无线通信技术所必需的一个条件。短突发通信系统广泛的应用于卫星通信、高速移动通信、卫星通信中,由于通信双方高速的相对移动产生很大的频偏。而近年来,具有编码增益高,工作信噪比门限低等特点的香农极限码受到了广泛的关注,但是其优异的性能只有在满足精确的同步下才能体现出来,即使存在很小的载波频偏,误码性能也会急剧下降,因此,如何在低信噪比以及大频偏的条件下,运用开销较小的导频序列进行精确的载波频偏估计是无线通信中一个关键的问题。为了解决上述问题,本文研究了国内外载波同步算法,如频域算法中的FFT算法、基于FFT的改进插值算法、RO、AVG、RA、RPA算法、二次内插算法等,对它们进行了介绍以及分析,又研究了时域算法中的时域相关和算法,研究了它的特点,并针对该算法分析了不同的帧结构条件下的估计范围及估计精度。其次,本文结合FFT算法和时域相关和算法,提出了一种新的时频联合的载波频偏估计算法,其基本思想是在一定导频开销下,将频域估计算法估计范围大和时域估计算法估计精度高的优势结合起来,首先利用频域周期图谱峰进行频偏粗估计,剩余频偏进一步利用时域相关和方法进行细估计,系统参数设置需根据误码性能要求和复杂度折衷选择。最后针对QPSK调制和直扩系统进行了仿真,仿真结果表明在50%符号速率的估计范围内,该算法具有估计精度较高的特点,且该算法的计算复杂度较低,比较适合应用于短突发系统。
[Abstract]:With the rapid development of communication technology, under the conditions of low SNR and large Doppler frequency offset, it is necessary for wireless communication technology to transmit data correctly at high rate.Short burst communication system is widely used in satellite communication, high-speed mobile communication, satellite communication, because of the relative high speed of both sides of the communication to produce a large frequency offset.In recent years, Shannon limit codes with high coding gain and low operating SNR threshold have attracted wide attention, but their excellent performance can only be realized under accurate synchronization, even if there is a very small carrier frequency offset.The performance of BER will also decline sharply. Therefore, how to estimate the carrier frequency offset accurately by using pilot sequence with low SNR and large frequency offset is a key problem in wireless communication.In order to solve the above problems, this paper studies the carrier synchronization algorithms at home and abroad, such as the FFT algorithm in frequency domain, the improved interpolation algorithm based on FFT, the quadratic interpolation algorithm, and so on.The time domain correlation and algorithm in time domain algorithm are also studied, and its characteristics are studied, and the estimation range and estimation accuracy under different frame structure conditions are analyzed.Secondly, combined with FFT algorithm and time-domain correlation algorithm, a new time-frequency joint carrier frequency offset estimation algorithm is proposed. Its basic idea is to estimate carrier frequency offset under certain pilot overhead.Combining the advantages of large estimation range in frequency domain and high estimation accuracy in time domain estimation, the coarse frequency offset is estimated by using frequency domain periodic map peak, and the residual frequency offset is further estimated by time domain correlation and method.The system parameters should be set according to the error performance requirements and the complexity of the tradeoff.Finally, the simulation of QPSK modulation and DSSS system is carried out. The simulation results show that the algorithm has high estimation accuracy and low computational complexity in the range of 50% symbol rate estimation.It is suitable for short burst system.
【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】：TN914

【共引文献】