Inter-Carrier Interference Cancellation for OFDM Systems with Macrodiversity and Multiple Frequency Offsets

摘要

Macrodiversity provides improved coverage in wireless communications. It is used in single frequency networks (SFN), and in some cellular systems, when a mobile is in a soft handoff. The combination of OFDM and macrodiversity is very attractive for the ability of OFDM to cope with delay spread resulting from macrodiversity. However, such system is very sensitive to poor frequency synchronization among transmitters, which results in multiple frequency offsets. These cause inter-carrier interference (ICI), which severely degrades performance. In this paper we quantify the degradation, providing expressions for the receiver SINK, and find the optimum receiver frequency synchronization. Furthermore, we propose to mitigate ICI degradation using linear and decision feedback interference cancellation. In each case, we provide a solution using both the decorrelating and the MMSE criteria. Simulation results show that, for macrodiversity OFDM, our approach results in significantly improved performance and robustness to frequency offsets.