Robust channel estimation in wireless LANs for mobile environments

Grünheid, R.; Rohling, Hermann; Ran, J.; Bolinth, E.; Kern, Robert S.

doi:10.1109/vetecf.2002.1040475

Cited by 18 publications

(11 citation statements)

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“…Robust channel estimation techniques for frames requiring long transmission time are proposed in [10,14]. The former injects mid-amble which plays the same role as PLCP preamble, i.e., allowing the receiver to learn the channel, in the middle of A-MPDU reception while the latter develops scattered pilot technique which reorganizes the pilot pattern periodically.…”

Section: Related Workmentioning

confidence: 99%

MoFA

Byeon

Yoon

Lee

et al. 2014

Proceedings of the 10th ACM International on Conference on Emerging Networking Experiments and Technologies

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IEEE 802.11n WLAN supports frame aggregation called aggregate MAC protocol data unit (A-MPDU) as a key MAC technology to achieve high throughput. While it has been generally accepted that aggregating more subframes results in higher throughput by reducing protocol overheads, our measurements reveal various situations where the use of long A-MPDU frames frequently leads to poor performance in time-varying environments. Especially, since mobility intensifies the time-varying nature of the wireless channel, the current method of channel estimation conducted only at the beginning of a frame reception is insufficient to ensure robust delivery of long A-MPDU frames. Based on extensive experiments, we develop MoFA, a standard-compliant mobilityaware A-MPDU length adaptation scheme with ease of implementation. Our prototype implementation in commercial 802.11n devices shows that MoFA achieves the throughput 1.8x higher than a fixed duration setting (i.e., 10 ms, the maximum frame duration according to IEEE 802.11n standard). To our best knowledge, this is the first effort to optimize the A-MPDU length for commercial 802.11n devices.

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Section: Related Workmentioning

confidence: 99%

MoFA

Byeon

Yoon

Lee

et al. 2014

Proceedings of the 10th ACM International on Conference on Emerging Networking Experiments and Technologies

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“…Adaptive filters can be used to estimate the changes in their pilot tones and interpolate them to estimate the channel response to the whole band [2] [3]. Refernce [4], shows that 4 pilot tones in 64 subcarriers in WLAN systems are not sufficient for pilot assisted channel tracking. It proposes to swap the pilot tones positions in OFDM symbols to track to whole band.…”

Section: Introductionmentioning

confidence: 99%

Low complexity decision directed channel tracking for MIMO WLAN system

Chen

Jayalath

Abhayapala

2005

2005 International Symposium on Intelligent Signal Processing and Communication Systems

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It is expected that the next generation wireless local area networks will be predominantly based on MIMO-OFDM physical layer. The performance of coherent MIMO-OFDM based systems critically depends on the availability of accurate channel estimations. Preambles, at the beginning of each packet, are used to estimate the channels in IEEE 802.11n Systems. However, in mobile communication, when the channel is time varying, the channel variations within a given packet increases the packet error rate (PER) in the system. So the channel variations have to be tracked by the receiver. This paper proposes a low complexity channel tracking scheme for 802.11n systems to improve the PER. The delay introduced by the channel tracking scheme is within the acceptable limits.

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“…Generally, they can be grouped into two categories. The first necessitates modifications of the standard frame structures [11]- [17], whereas the second adheres to the original data structure [18]- [30].…”

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confidence: 99%

“…Therefore, necessary modifications become helpful to achieve performance improvement under this circumstance. In [11], a midamble-assisted scheme was first proposed and further investigated in [12] and [13]. Considering that the traditional preamble ahead of data cannot support reliable channel updating, midamble sequences are periodically inserted between data symbols to enable continuous channel information tracking.…”

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confidence: 99%

Constructed Data Pilot-Assisted Channel Estimators for Mobile Environments

Zhao

Cheng

Wen

et al. 2014

IEEE Trans. Intell. Transport. Syst.

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Nowadays, more and more communication systems are deployed under mobile environments with very high velocity. This paper focuses on the channel estimation problem in vehicular scenarios, which is very challenging in view of the extremely time-varying characteristics of mobile channels. Specifically, we propose a novel channel estimator named constructed data pilot (CDP) estimator for the current communication standards by fully exploiting the channel correlation characteristics across two concatenated symbols. On the basis of the CDP estimator, we further resort to two efficient techniques to improve its performance over the entire signal-to-noise-ratio (SNR) region. For the first technique, the time-variant mobile channel is modeled as a first-order Markov process so that the exact autocorrelation value of the two adjacent symbols can be derived. For the second technique, the SNR is estimated and serves as a priori information. Simulation results reveal that our proposed channel estimators outperform existing alternatives with lower computational complexity.

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Robust channel estimation in wireless LANs for mobile environments

Cited by 18 publications

References 0 publications

MoFA

MoFA

Low complexity decision directed channel tracking for MIMO WLAN system

Constructed Data Pilot-Assisted Channel Estimators for Mobile Environments

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