Novel iterative APPA carrier phase recovery and detection for turbo-coded systems

This paper introduced a novel a priori probability aided (APPA) carrier phase recovery and signal detection algorithm. The algorithm utilized the soft value of the extrinsic information generated by iterative MAP decoders by means of iteration after iteration. This method provided robust carrier phase estimation along with reliable signal decoding with a wide range of phase errors at such low signal-to-noise ratio (SNR) conditions that turbo coded systems operate on. In order to take full advantage of turbo iterative decoding structure and the output soft information, we improved turbo decoding iterative structure and proposed a novel turbo iterative scheme which include iterative calculation of both information and parity bits Log-likelihood Ratio (LLR). We applied the above iterative structure into APPA carrier estimator. Compared with traditional turbo iteration methods, the novel turbo iteration algorithm can improve the acquisition region from -40 to 40 degrees while acquisition region is from -30 to 30 degrees in traditional methods at the same 3^rd iteration stage. The overall BER decreases greatly at the same number of turbo iteration. The algorithm has additional advantages including reasonable hardware complexity and easy to be implemented.