| Paper Details: | Downloads: 426 |
| Serial Number: | P1180820004
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| Title: | ADAPTIVE MODULATION WITH CFO CORRECTION FOR OFDM SYSTEMS
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| Authors: | K.Gunaseelan and A.Kandaswamy
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| Abstract: | Adaptive modulation technique can be employed to maximize the spectral efficiency of the Orthogonal Frequency Division Multiplexing (OFDM) systems if the channel state information (CSI) is available at the transmitter. The performance of adaptive modulation technique depends on the accurate estimation of CSI. But in OFDM systems, the carrier frequency offset (CFO) will severely degrade the performance of adaptive modulation technique in terms of spectral efficiency. In practice the CFO will make the estimated CSI to deviate from the actual CSI which reduces the spectral efficiency of the adaptive modulation schemes. As an attempt, in this paper the effect of CFO in adaptive modulation schemes, CFO estimation and correction techniques are analysed. During the analysis, the fixed modulation schemes and adaptive modulation with CFO provides very poor spectral efficiency to maintain the acceptable BER. In this paper, a novel adaptive modulation technique to maximize the spectral efficiency of the OFDM system has been proposed. In this proposed method, the CFO is estimated using maximum likelihood estimation (MLE), compensated using direct method and then adaptive modulation has been performed. The simulation results show that the proposed method maximizes the spectral efficiency with an acceptable BER than the adaptive modulation with CFO and non adaptive modulation schemes.
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| Keywords: | Orthogonal Frequency Division Multiplexing, Carrier Frequency Offset, Inter Carrier Interference, Channel State Information, Bit Error Rate, Maximum likelihood Estimation.
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| Journal/Conference: | International Journal of Digital Signal Processing
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| Volume: | 8
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| Issue: | 1
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| Submission Date: | 5/1/2008 12:00:00 AM
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| Review Date: | 8/1/2008 12:00:00 AM
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| Publishing Date: | 12/1/2008 12:00:00 AM
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| Article Downloads: | 426
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