Iterative carrier phase synchronization without reconstructing the soft symbols

摘要

In an energy-efficient receiver employing iterative decoders, phase synchronization errors reduce much of the gains that can be achieved at low SNRs. To address this problem, the concept of an iterative receiver has received much attention in the past. In such a framework, signal degradation at low SNR is overcome by repeated phase synchronization executed over the soft symbols generated by the iterative decoder. However, an obvious problem is the immense computational complexity, one aspect of which is the need to reconstruct the soft symbols from Log Likelihood Ratios (LLRs) of both the information and the parity bits. In this paper, we propose a heuristic algorithm for crude carrier phase synchronization based on LLRs of information bits only (which are required for detection purpose in any case). Thus, the computations of the LLRs of the parity bits can be avoided to strike a tradeoff between complexity and performance. Results show that this approach has significant performance advantage in comparison to a conventional receiver and complexity advantage in comparison to an iterative receiver.