Efficient Estimation Algorithm of Carrier Frequency Offset for LTE Machine-Type Communication Using Frequency Hopping

The demanding challenge of cellular-based machine type communication (MTC) is to meet emerging requirements of user equipment (UE), which can provide improved coverage and lower power consumption. To this end, an improved coverage UE is needed to estimate frequency error in the low coverage area. In this paper, an improved frequency offset synchronization scheme is proposed for MTC over long term evolution system. To perform the improved frequency offset estimation, the proposed method is based on repetitive nature and frequency hopping of the physical downlink shared channel (PDSCH), which is integrated with weighted least-squares estimation to eliminate the effect of channel fading. This design makes it possible to effectively estimate the residual frequency offset when there is frequency selective fading. It is shown from simulation results that the frequency-hopped PDSCH signal is effectively used to minimize the estimation error for coverage enhancement of MTC UEs in poor channel conditions.