编码辅助载波同步算法的优化设计

鉴于低信噪比下编码辅助载波同步算法存在同步范围小的问题,提出一种导频联合编码辅助载波同步算法。首先分析了导频结构对粗估计算法同步范围和同步精度的影响机理,提出适合大频偏情况的导频结构及其对应的频偏粗估计算法,并推导了它的估计方差;然后将该导频结构应用到简化的EM辅助精同步算法中,得到了同步范围大和估计精度高的导频和编码辅助的同步算法。仿真结果表明,在不损失估计精度的前提下,新算法能大幅提高同步参数的估计范围,在一定的导频长度下BER性能可逼近理想同步。

Optimization of Code Aided Carrier Synchronization Algorithm

Considering the small synchronization range of code-aided (CA) carrier recovery algorithms at low signal to noise ratio (SNR), a pilot-code joint assisted carrier synchronization algorithm is proposed. Firstly, through analyzing the impact of pilot structure on synchronization range and accuracy of coarse estimation, a new algorithm for estimating pilot structure and coarse frequency offset is proposed and its mean squared error (MSE) is also derived. And then a pilot-code joint assisted synchronization with large synchronization range and high estimation accuracy is achieved by using pilot symbols with simplified expectation maximization (EM) fine synchronization. Simulations verify that the new algorithm can increase synchronization range greatly without accuracy decrease, which can achieve perfect synchronization with a certain amount of pilot symbols.