Detection of Interleaved OFDMA Uplink Signals in the Presence of Residual Frequency Offset Using the SAGE Algorithm

In this paper, we propose an iterative detection scheme in the presence of residual frequency offsets (RFOs) using the spacealternating generalized expectation–maximization algorithm for an orthogonal-frequency-division-multiple-access uplink system. In the proposed scheme, the expectation step intends to remove intercarrier interference (ICI) due to the RFOs of simultaneous users in the received signals. Then, the maximization step is utilized to estimate the required parameters for each user (i.e., RFO, data symbols, and channel state information) employing the ICI-cancelled signals. Simulation results show that the proposed scheme achieves almost ideal bit-error-rate performance as long as the magnitude of the normalized RFO value is within 0.2.This work was supported in part by the University IT Research Center Project and in part by the Brain Korea 21 Project