低信噪比短前导突发通信的频偏估计

Short preamble-based estimation of frequency offset in burst system under low SNR

为了解决低信噪比、短前导码突发通信系统的解调性能随着载波频偏增大而恶化的问题,设计了一种混合频偏估计方案,将频偏估计分解为粗估计和细估计两个过程,对每个过程采用不同的估计算法,从理论推导、数值仿真、实验验证三个方面入手,有效解决了多进制数字相位调制(MPSK)下突发通信的大频偏解调问题。结果表明,在四相移键控(QPSK)调制通信系统中,所提方案能够以小于0.5 d B的解调损失估计出±3%符号率内的载波频偏。

In order to solve the problem that the receiver＇ s performance deteriorates with the increase of carrier frequency offset in burst system under low Signal-to-Noise Ratio （SNR） and short preamble, a mixed frequency offset estimation scheme was designed, which was decomposed into coarse estimation and fine estimation using different estimation algorithms. The problem in burst communication with Multiple Phase Shift Keying （MPSK） modulation was effectively solved in three aspects which were theoretical derivation, numerical simulation and experimental verification. The experimental results show that a precise estimation of carrier frequency offset in range of ~ 3% symbol rate with less than 0.5 dB demodulation loss was observed in a communication system modulated by Quadrature Phase Shift Keying （QPSK）.