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Iterative Frequency Domain Equalization and Carrier Synchronization for Multi-Resolution Constellations

Pedrosa, P. ; Dinis, R. ; Nunes, F.

IEEE Transactions on Broadcasting Vol. 56, Nº 4, pp. 551 - 557, December, 2010.

ISSN (print): 0018-9316
ISSN (online):

Journal Impact Factor: 1,673 (in 2008)

Digital Object Identifier: 10.1109/TBC.2010.2073251

Abstract
Broadband broadcast and multicast wireless systems
usually employ OFDM modulations (Orthogonal Frequency
Division Multiplexing) combined with non-uniform hierarchical
constellations. However, these schemes are very prone to nonlinear
distortion effects and have high carrier synchronization
requirements. SC-FDE (Single-Carrier with Frequency-Domain
Equalization) is an attractive alternative for OFDM, especially
when an efficient power amplification is intended. In this paper we
consider the use of SC-FDE schemes combined with non-uniform
hierarchical constellations in broadband broadcast and multicast
wireless systems. We study the impact of residual CFO (Carrier
Frequency Offset) on the performance of multi-resolution schemes
and we propose iterative frequency domain receivers with joint
detection and carrier synchronization to cope with residual CFO
estimation errors (a coarse CFO estimation and compensation is
assumed before the equalization procedure). Our results show that
while a very high carrier synchronization accuracy is required for
the least protected bits, the most protected bits are relatively robust
to the CFO. By employing the proposed receiver we increase
significantly the robustness to residual CFO estimation errors.