Proceedings ArticleDOI
Efficient multi user CFO estimation and correction techniques in uplink OFDMA systems
Neetha I. Eappen,J. Arun Prakash,G. Ramachandra Reddy +2 more
- pp 306-310
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TLDR
In this article, an Extended Viterbi-and-Viterbi (EVAV) algorithm is employed for CFO estimation in uplink OFDMA systems, where an iterative Conjugate Gradient (CG) method is used to compute the MMSE filter output without an inverse operation.Abstract:
Inter carrier interference and multiple access interference are induced in uplink OFDMA systems due to Carrier Frequency Offset (CFO) which is a mismatch between the transmitter and receiver frequencies that in turn affects the orthogonality among subcarriers. A different CFO value is experienced by each user data and each of these CFO values needs to be estimated and corrected. A novel Extended Viterbi-and-Viterbi (EVAV) algorithm is employed for CFO estimation in the present study. A conventional algorithm for CFO compensation that deals with Minimum Mean Square Error (MMSE) filter output, involves inversion of interference matrix, adding to the computational complexity. The complexity was found to increase with the number of subcarriers. Hence, here an iterative Conjugate Gradient (CG) method is used to compute the MMSE filter output without an inverse operation, thereby reducing the complexity. Both the EVAV method and the CG method have been analyzed in terms of various performance measures. The results showed that they function better than their conventional counterparts.read more
Citations
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Journal ArticleDOI
Novel Adaptive Filter Design for Filter Bank Multicarrier System Under Doubly Dispersive Channel Conditions
TL;DR: An adaptive filter design method is proposed in which the prototype filter is designed as the weighted sum of a time-limited Nyquist filter, a band-limited Nilsson filter, and doubly localized Gaussian filter based on the analysis of discrete ambiguity function (DAF).
Proceedings ArticleDOI
EP-based Detection for Uplink OFDM-IDMA with Carrier Frequency Offsets
TL;DR: A novel detection algorithm is proposed for multiuser detection in uplink orthogonal frequency division multiplexing-interleave division multiple access (OFDM-IDMA) systems employing the expectation propagation (EP) algorithm that can effectively mitigate the influence of multiple CFOs.
Proceedings ArticleDOI
Low-complexity CFO compensation technique for uplink OFDMA
TL;DR: An iterative low complexity carrier frequency offset (CFO) compensation technique for uplink OFDMA by using simple and code-aided time domain multiuser interference cancellation (SACA-MUIC) algorithm that achieves a significant performance compared to conventional receiver.
References
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An Introduction to the Conjugate Gradient Method Without the Agonizing Pain
TL;DR: The Conjugate Gradient Method as discussed by the authors is the most prominent iterative method for solving sparse systems of linear equations and is a composite of simple, elegant ideas that almost anyone can understand.
Journal ArticleDOI
Non-data-aided carrier offset estimators for OFDM with null subcarriers: identifiability, algorithms, and performance
TL;DR: Identifiability issues involving high-resolution techniques that have been proposed for blind CFO estimation based on null subcarriers are investigated and new approaches that do not suffer from the lack of identifiability and adopt adaptive algorithms that are computationally feasible are proposed.
Proceedings ArticleDOI
Effect of carrier frequency offset on OFDM systems for multipath fading channels
TL;DR: The paper presents an exact analysis of the effect of the carrier frequency offset on orthogonal frequency division multiplexing (OFDM) systems for a general multipath fading channel and determines how small the frequency offset should be in order to maintain the SNR degradation to negligible levels.
Journal ArticleDOI
Blind Frequency Synchronization in OFDM via Diagonality Criterion
T. Roman,S. Visuri,Visa Koivunen +2 more
TL;DR: This paper addresses the problem of blind carrier frequency offset (CFO) estimation in orthogonal frequency-division multiplexing (OFDM) systems in the case of frequency-selective channels and derives the Cramer-Rao bound (CRB) for the blind CFO estimation problem.
Journal ArticleDOI
Blind Carrier Frequency Offset Estimation for OFDM Systems with Constant Modulus Constellations
TL;DR: This paper proposes a blind carrier frequency offset (CFO) estimation scheme for OFDM systems and shows that the proposed scheme is better than the conventional schemes through simulations.
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