TY - JOUR
T1 - IQ-imbalance compensation for OFDM in the presence of IBI and carrier-frequency offset
AU - Barhumi, Imad
AU - Moonen, Marc
N1 - Funding Information:
Manuscript received June 13, 2005; revised January 16, 2006. This work was carried out at the ESAT Laboratory of the Katholieke Universiteit Leuven, in the frame of Belgian Programme on Interuniversity Attraction Poles, initiated by the Belgian Federal Science Policy Office IUAP P5/22 (“Dynamical Systems and Control: Computation, Identification and Modelling”) and P5/11 (“Mobile multimedia communication systems and networks”), the Concerted Research Action GOA-MEFISTO-666 (Mathematical Engineering for Information and Communication Systems Technology) of the Flemish Government, and Research Project FWO nr.G.0196.02 (“Design of efficient communication techniques for wireless time-dispersive multi-user MIMO systems”). The work of I. Barhumi was supported in part by the Palestinian European Academic Cooperation in Education (PEACE) Programme. The associate editor coordinating the review of this manuscript and approving it for publication was Dr. Kostas Berberidis.
PY - 2007/1
Y1 - 2007/1
N2 - In this paper, we propose a frequency-domain equalization technique for orthogonal frequency division multiplexing (OFDM) transmission over frequency-selective channels. We consider the case where the receiver analog front-end suffers from IQ-imbalance and the local oscillator suffers from carrier-frequency offset (CFO). While the IQ-imbalance results in a mirroring effect, the CFO induces inter-carrier interference (ICI). In addition to ICI, we consider the channel delay spread is larger than the cyclic prefix (CP). This means that inter-block interference (IBI) is present. The frequency-domain equalizer is obtained by transferring a time-domain equalizer (TEQ) to the frequency-domain resulting in a per-tone equalizer (PTEQ). Due to the presence of IQ-imbalance the conventional TEQ (where only one TEQ is applied to the received sequence) is not sufficient to cope with the mirroring effect. A sufficient TEQ consists of two time-domain filters; one applied to the received sequence and another applied to a conjugated version of the received sequence. For the case of IQ-imbalance and CFO, the TEQs are designed according the basis expansion model (BEM) which showed to be able to cope with the ICI problem. Finally, in addition to the frequency-domain PTEQ design procedure, a training-based RLS type initialization scheme for direct per-tone equalization is also proposed.
AB - In this paper, we propose a frequency-domain equalization technique for orthogonal frequency division multiplexing (OFDM) transmission over frequency-selective channels. We consider the case where the receiver analog front-end suffers from IQ-imbalance and the local oscillator suffers from carrier-frequency offset (CFO). While the IQ-imbalance results in a mirroring effect, the CFO induces inter-carrier interference (ICI). In addition to ICI, we consider the channel delay spread is larger than the cyclic prefix (CP). This means that inter-block interference (IBI) is present. The frequency-domain equalizer is obtained by transferring a time-domain equalizer (TEQ) to the frequency-domain resulting in a per-tone equalizer (PTEQ). Due to the presence of IQ-imbalance the conventional TEQ (where only one TEQ is applied to the received sequence) is not sufficient to cope with the mirroring effect. A sufficient TEQ consists of two time-domain filters; one applied to the received sequence and another applied to a conjugated version of the received sequence. For the case of IQ-imbalance and CFO, the TEQs are designed according the basis expansion model (BEM) which showed to be able to cope with the ICI problem. Finally, in addition to the frequency-domain PTEQ design procedure, a training-based RLS type initialization scheme for direct per-tone equalization is also proposed.
KW - Basis expansion model (BME)
KW - Carrier-frequency offset (CFO)
KW - IQ-imbalance
KW - Orthogonal frequency-division multiplexing (OFDM)
KW - Per-tone equalizer (PTEQ)
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U2 - 10.1109/TSP.2006.882102
DO - 10.1109/TSP.2006.882102
M3 - Article
AN - SCOPUS:33947388367
SN - 1053-587X
VL - 55
SP - 256
EP - 266
JO - IEEE Transactions on Signal Processing
JF - IEEE Transactions on Signal Processing
IS - 1
ER -