Iterative carrier phase synchronization in the presence of residual frequency offset

We propose an iterative carrier phase recovery method to be used in conjunction with a turbo-decoder based on the BCJR (Bahl-Cocke-Jelinek-Raviv) algorithm. The basic idea consists of: (i) exploiting the forward recursion of only one SISO decoder in order to calculate a sort of expectation of the transmitted symbols; (ii) using such soft decision symbols in a modified Costas loop to update the (time-variant) carrier phase offset. The simulation results show that the proposed estimation scheme is quite robust, even with a severe frequency offset.