Blind Channel Shortening in OFDM System using Nulltones and Cyclic Prefix

Jabeur, Taoufik Ben; Abed-Meraim, Karim; Boujemâa, Hatem

doi:10.1109/icassp.2008.4518291

Cited by 8 publications

(6 citation statements)

References 8 publications

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“…As for single-user OFDM systems, the above condition was derived by Ben Jabeur et al [7]. Note that unlike the null subcarrier condition (22), the data subcarrier condition (27) ensures to shorten only the channel between the kth TEQ and lth mobile user.…”

Section: Data Subcarrier Conditionmentioning

confidence: 97%

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On carrier nulling approaches for channel shortening in OFDMA systems

Miyajima

Ding²

2010

2010 IEEE 11th International Workshop on Signal Processing Advances in Wireless Communications (SPAWC)

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This paper considers blind and semiblind channel shortening methods based on carrier nulling criteria to mitigate the effect of inter-block interference in uplink OFDMA systems. We derive a sufficient condition that states that if the number of subcarriers unused by a desired user exceeds a given threshold then uplink channels can be shortened perfectly. Simulation results are shown to verify the analytical result.

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Section: Data Subcarrier Conditionmentioning

confidence: 97%

“…Recently, Ben Jabeur et al [7] showed that CNA can achieve the perfect shortening in single-user OFDM systems if the number of data (used) subcarriers exceeds a given threshold. There are no previous reports on the application of CNA to OFDMA systems.…”

Section: Introductionmentioning

confidence: 99%

On carrier nulling approaches for channel shortening in OFDMA systems

Miyajima

Ding²

2010

2010 IEEE 11th International Workshop on Signal Processing Advances in Wireless Communications (SPAWC)

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“…In [4], a similar approach is used for channel shortening in OFDM systems, and in [5], [6], semi-blind channel identification methods are considered where data-aided and blind techniques are combined together to shorten the training sequence while preserving a high channel estimation quality.…”

Section: Introductionmentioning

confidence: 99%

Quasi-Convexity of the Asymptotic Channel MSE in Regularized Semi Blind Estimation

Kammoun

Abed-Meraim

Affes

2011

IEEE Trans. Inform. Theory

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In this paper, the quasi-convexity of a sum of quadratic fractions in the form n i=11+c i x 2 (1+d i x) 2 is demonstrated where ci and di are strictly positive scalars, when defined on the positive real axis R + . It will be shown that this quasi-convexity guarantees it has a unique local (and hence global) minimum.Indeed, this problem arises when considering the optimization of the weighting coefficient in regularized semi-blind channel identification problem, and more generally, is of interest in other contexts where we combine two different estimation criteria.Note that V. Buchoux et.al have noticed by simulations that the considered function has no local minima except its unique global minimum but this is the first time this result, as well as the quasi-convexity of the function is proved theoretically.

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“…Getting intuition from [12] we define a linear The joint cost function is a linear combination of the two cost functions introduced above. The optimization can be casted as follows:…”

Section: Combined Approachmentioning

confidence: 99%

Blind channel shortening for zero-padded OFDM

Chen

Huang

Wang

et al. 2010

Oceans 2010 MTS/Ieee Seattle

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Abstract-When the channel delay spread is larger than the guard interval of zero-padded (ZP) OFDM transmissions, interblock interference (IBI) might lead to significant performance degradation. Without altering the signal design, a time-domain equalizer (TEQ) can be applied at the receiver to shorten the channel for IBI suppression. In this paper we study several known designs of blind channel shortening in the ZP-OFDM context, exploiting the signal redundancy in the form of guard zeros in the time domain, or null subcarriers in the frequency domain, or both. Numerical results show that blind channel shortening algorithms can catch up or even exceed the performance of a benchmark scheme assuming perfect channel knowledge. Only time-invariant channels are considered in this paper; channel shortening for time-varying channels with large delay spreads such as underwater acoustic channels is an interesting subject that warrants further investigation. Index Terms-OFDM, zero padding, inter-block interference, time-domain equalizer, blind channel shortening.

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Blind Channel Shortening in OFDM System using Nulltones and Cyclic Prefix

Cited by 8 publications

References 8 publications

On carrier nulling approaches for channel shortening in OFDMA systems

On carrier nulling approaches for channel shortening in OFDMA systems

Quasi-Convexity of the Asymptotic Channel MSE in Regularized Semi Blind Estimation

Blind channel shortening for zero-padded OFDM

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