Author(s)

Zhongshan Zhang, Jian Liu, Keping Long

Advanced Network Technologies and New Services, University of Science and Technology Beijing (USTB), Beijing, China.

In this paper, we consider the frequency offset estimation for Orthogonal Frequency-Division Multiple Access (OF-DMA) uplink (UL) transmissions. We first analyze the negative effect of Multi-Access-Interference (MAI) on OFDMA UL, and then propose two interference reduction/elimination methods, i.e., the Reduced-Rank-Projector (RRP) and Shift-Sampling-Projector (SSP) methods, to eliminate/reduce the heavy MAI due to the frequency offsets. Finally, we propose a new training sequence group named the Round-Robin Training Sequence Group (RRTSG), which has a high interference mitigation capabilities for OFDMA UL transmission. The Cramer-Rao Lower Bound (CRLB) for an unbiased frequency offset estimator in a Multiple Access (MA) system is also derived. Numerical results show that the proposed methods are suitable to eliminate/mitigate the effect of the frequency offset on OFDMA UL transmission.

Synchronization; Timing Offset; Frequency Offset; OFDMA

Z. Zhang, J. Liu and K. Long, "OFDMA Uplink Frequency Offset Estimation with Multi-Access Interference Mitigation," Communications and Network, Vol. 4 No. 3, 2012, pp. 205-218. doi: 10.4236/cn.2012.43025.