Robust FFT Window Replacement in Non-Ideal CoMP Networks with Timing Offset

Coordinated multipoint (CoMP) transmission is one of key technologies to provide broadband communication and coverage for cell edge user equipments (UEs) in long term evolution (LTE) systems. The basic concept behind CoMP transmission are geographically distributed transmitters working jointly in coordinated manner. As the transmit signals reach the UE at different times, CoMP networks might experience high timing offsets (TOs) leading to a fast Fourier transform (FFT) window mismatch. Positive TOs with synchronization signals reaching the UE prior to data signals impose an acceptable performance loss, whereas the presence of negative TOs disables CoMP transmission saturating in error floor at unacceptable bit error rate. In this paper a novel approach to overcome negative TO is proposed that guaranties robust performance while keeping system complexity low. Shifting the FFT window towards the data signal by the estimated TO, the negative TO turns positive and as a result near optimum performance is achieved.