Low complexity iterative interference cancelation for OFDMA uplnik with carrier frequency offsets

For the uplink transmission of an orthogonal frequency division multiple access (OFDMA) system, frequency synchronizaion is particularly challenging due to the presence of multiple Carrier Frequency Offsets (CFOs), which destroy the orthogonality among subcarriers and introduce massive multiuser interference (MUI) and inter-carrier interference (ICI). To prevent the consequent performance degradation, CFOs must be accurately estimated and properly corrected to cancel the interference. Among all the proposed interference cancelation solutions for OFDMA uplink, the best performance is achieved by an algorithm proposed in [1], which is however prohibitively complex. A banded matrix approximation was proposed in the same paper to reduce the complexity, however, at the cost of performance degradation. In this paper, a decision aided interative interference cancelation algorithm is proposed based on the banded matrix, which exploits the detected signal to interatively reconstruct and eliminate the residual interference incurred by the banded system. The simulation results show that the interative algorithm could entirely overcome the performance degradation and achieve the best performance. At the same time, it significantly reduces the computational complexity required by the interference cancelation.