Phase estimation with the aid of soft output from turbo decoding

This paper proposes a carrier phase recovery approach when turbo codes are used. The phase estimation is implemented with the aid of the extrinsic information from the turbo decoder. A series of look-up tables are pre-computed to reduce the computation complexity, and thereby we avoid introducing delay to the decoding. Simulations are carried out both in BPSK and QPSK systems. If the block size is 1024, a phase error up to 82° in a BPSK system, and up to 37° in a QPSK system can be removed completely. Compared with the conventional method, which has separate phase recovery and decoding, this approach exhibits a great improvement. The effect of block size is also considered. The results demonstrate that the longer the block size, the better the performance.