Time and Frequency Synchronization for OFDMA Uplink System using the SAGE Algorithm

Abstract

In this letter, we propose an iterative time and frequency synchronization scheme for orthogonal frequencydivision multiple access (OFDMA) uplink system using the space-alternating generalized expectation-maximization (SAGE) algorithm. In the proposed scheme, the expectation step of the SAGE algorithm is intended to remove the multiple-access interference (MAI) caused by the other asynchronous users. Then, the maximization step is utilized in the timing and frequency offset estimation of each asynchronous user using the MAI-canceled signals. Simulation results present that the proposed scheme shows performance enhancement in the presence of multiple asynchronous users.