Extended Range Code-Aided Carrier Recovery Algorithm

The code-aided (CA) synchronization algorithm exploits soft decoding information to estimate synchronization parameters, and it can achieve the reliable carrier synchronization at lower signal to noise ratio (SNR) values. But the algorithm performs small synchronization range and high complexity. Firstly, a new evaluation function is defined in view of the symbols with high decision reliability, and the signal is compensated using coarse parameters estimation corresponding to the maximum of the function. And then the modulated information of compensated signal is eliminated by posterior average value. Finally, the residual frequency and phase offset is rectified by the improved algorithm based on autocorrelation function and maximum likelihood (ML) criterion respectively, so the accurate carrier recovery is achieved. The simulation results verify that this algorithm can increase synchronization range greatly at the cost of some less computation complexity, and almost perfect synchronization decoding performance is achieved.