一种改进的GFDM时频同步算法

针对广义频分复用( GFDM)系统对符号定时同步要求较高的问题，提出了一种新的基于前缀码的同步算法。在接收端，在获取粗略定时信息的基础上，利用前缀码前后两部分的相位差实现载波频偏估计，并对接收序列的频率偏移进行纠正，然后通过纠正后序列与已知发射前缀的互相关函数实现精确的符号定时估计。由于该前缀码具有共轭对称的特性，使其避免了“平顶效应”的出现。结合5G中低时延高可靠场景，在频率选择性信道中对其进行仿真，并通过均方误差对其性能进行了评估。理论分析及仿真结果表明，该算法相对于原算法具有更好的定时同步性能和更低的复杂度，提升了GFDM系统的整体性能。

An improved timing and frequency synchronization algorithm for generalized frequency division multiplexing system

According to the higher requirements of generalized frequency division multiplexing ( GFDM ) system for symbol timing synchronization,a synchronization algorithm is proposed based on a new pream-ble. At the receiver,after obtaining the coarse timing synchronization,the carrier frequency offset is esti-mated through the phase difference between the two halves of the preamble. Then the carrier frequency off-set in the received signal is corrected. And a more accurate estimation of symbol timing offset is obtained by the cross-correlation with the transmitted preamble. Due to the conjugate symmetry characteristic of the preamble,this algorithm can avoid the plateau effect. In the low-latency high-reliability scenario of 5G, simulations are done in frequency-selective channels,and the performance of the scheme is evaluated in terms of mean squared error( MSE) of the frequency and time offset estimation. Theoretical analysis and simulation results show that the new algorithm has a better timing synchronization performance and can re-duce the complexity of the system,thus enhancing the overall performance of system.