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.