频偏估计算法研究及FPGA实现

发布时间：2018-03-06 13:29

本文选题：频偏估计　切入点：OQPSK(偏移正交相移键控)　出处：《天津大学》2014年硕士论文　论文类型：学位论文

【摘要】：载波同步是数字通信系统中的关键问题,由于系统中发射端和接收端载波之间存在频率偏差以及多普勒频移现象的影响会使下变频处理后的信号产生一定的频率偏移从而导致信号的相位发生变化,直接影响接收机性能。本论文在研究了经典载波频偏估计算法和OQPSK载波同步体系的基础上,提出了一种新的适用于OQPSK调制方式的载波同步方案。对帧起始位置检测算法进行改进:在基于接收信号自相关运算的基础上,加入匹配滤波运算,提高算法性能;并选取适合的频偏估计算法,针对硬件实现对算法进行可行性调整。并对本论文提出的载波同步方案进行仿真,从仿真结果对整个方案进行性能分析,证明了本论文提出的方案信噪比门限更低,频偏估计范围大,估计精度较高。论文中论述了该方案基于FPGA实现的设计思路和实现方法。本文提出可行的FPGA实现方案,针对硬件实现方面进行优化,避免了帧起始位置检测算法和频偏估计算法需要做大量自相关运算的问题。该方案通过对数据流的控制,降低了硬件资源占用率;并利用相关运算中的重叠数据,改进相关运算,降低了运算复杂度。最后对整个方案做时序仿真验证,并在实时实验中对本论文提出的载波同步方案进行性能验证,证明本论文提出的载波同步系统可以有效实现载波同步。
[Abstract]:Carrier synchronization is a key problem in digital communication system. Because of the frequency deviation between the transmitter and receiver carrier and the influence of Doppler frequency shift, the frequency offset of the signal after down-conversion will be produced, which will lead to the change of the signal phase. This paper studies the classical carrier frequency offset estimation algorithm and OQPSK carrier synchronization system. A new carrier synchronization scheme suitable for OQPSK modulation is proposed. The frame starting position detection algorithm is improved: based on the autocorrelation operation of the received signal, the matched filtering operation is added to improve the performance of the algorithm; The suitable frequency offset estimation algorithm is selected, the feasibility of the algorithm is adjusted for hardware implementation, and the carrier synchronization scheme proposed in this paper is simulated, and the performance of the whole scheme is analyzed from the simulation results. It is proved that the proposed scheme has lower signal-to-noise ratio threshold, wider range of frequency offset estimation and higher estimation accuracy. This paper discusses the design idea and implementation method of the scheme based on FPGA. A feasible FPGA implementation scheme is proposed in this paper. The hardware implementation is optimized to avoid the problem that the frame start position detection algorithm and the frequency offset estimation algorithm need to do a lot of autocorrelation operation. This scheme reduces the hardware resource occupancy by controlling the data flow. Using the overlapping data in the correlation operation, the correlation operation is improved, and the computational complexity is reduced. Finally, the timing simulation of the whole scheme is done, and the performance of the carrier synchronization scheme proposed in this paper is verified in the real-time experiment. It is proved that the carrier synchronization system proposed in this paper can effectively realize carrier synchronization.
【学位授予单位】：天津大学
【学位级别】：硕士
【学位授予年份】：2014
【分类号】：TN914.3

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