Efficient Weighted Least-Squares Frequency Synchronization Scheme for Digital Terrestrial Broadcasting System

Abstract

The integrated services digital broadcasting-terrestrial (ISDB-T) system provides the interesting advantages of hierarchical transmission and partial reception using band segmented transmission orthogonal frequency division multiplexing scheme. In ISDB-T, the hierarchical configuration varies depending on whether a segment is modulated coherently or differentially. Thus, it is important to accomplish frequency synchronization regardless of segment type. For this purpose, an effective weighted least-squares (WLS) carrier frequency synchronization method is presented using transmission and multiplexing configuration control (TMCC) and auxiliary channel (AC) in a blind manner. Thus, the proposed estimation scheme is performed without resorting to a priori knowledge on segment type that can be known after correct TMCC decoding. To eliminate bias caused by using non-uniformly distributed TMCC and AC subcarriers, an appropriate subset is selected to form the basis of robust WLS estimation. Extensive simulations are conducted to verify the efficiency of the proposed WLS estimation method and compare its performance with that of the conventional WLS estimation scheme.