Maximum likelihood (ML) carrier-frequency offset (CFO) estimation in the uplink of an orthogonal frequency-division multiple-access (OFDMA) system with a generalized carrier- assignment scheme (GCAS) is a complex multiple-parameter estimation problem. The computational complexity of the ML solution based on a multi-dimensional exhaustive search is prohibitive. The existing solutions reduce the complexity by replacing the multidimensional search with a sequence of single-dimensional searches. However, those solutions suffer from either poor estimation accuracy or is still of high complexity. In this paper, we propose a new approach called as the divide-and-update frequency estimator (DUFE), which outperforms the existing solutions in the sense that it has lower computational complexity while maintaining high estimation accuracy similar to the exact ML solution. Performance and complexity comparisons are provided with numerical results to illustrate the effectiveness of the proposed method.
[1]
C.-C. Jay Kuo,et al.
Maximum-likelihood synchronization and channel estimation for OFDMA uplink transmissions
,
2006,
IEEE Transactions on Communications.
[2]
Per Ödling,et al.
A time and frequency synchronization scheme for multiuser OFDM
,
1999,
IEEE J. Sel. Areas Commun..
[3]
Yu-Dong Yao,et al.
Deterministic multiuser carrier-frequency offset estimation for interleaved OFDMA uplink
,
2004,
IEEE Transactions on Communications.
[4]
Umberto Mengali,et al.
Carrier-frequency estimation for transmissions over selective channels
,
2000,
IEEE Trans. Commun..
[5]
Sergio Barbarossa,et al.
Channel-independent synchronization of orthogonal frequency division multiple access systems
,
2002,
IEEE J. Sel. Areas Commun..
[6]
Gene H. Golub,et al.
Matrix computations
,
1983
.