A Novel Code-Aided Carrier Recovery Algorithm for Coded Systems

We present a novel code-aided carrier recovery method for low-density parity-check (LDPC) coded systems, which comprises two supporting algorithms: 1) a coarse synchronization by maximizing a cost function, the mean absolute value of the soft outputs of the LDPC decoder, followed by a simple interpolation operation to improve the estimation accuracy and 2) a fine synchronization based on the soft decisions produced by the LDPC decoder. With moderate computational complexity, this proposed algorithm is designed to synchronize signals with large carrier frequency offset and phase offset at low signal-to-noise ratio (SNR). When applied to the case of an 8-PSK system with (1944,972) LDPC code, the performance loss compared to the case of ideal synchronization is negligible.