On the Influence of the non-WSSUS Condition in the Performance of IEEE 802.11-Based Channel Estimators for Vehicular Communications

Ortega, Nicolas M.; Azurdia-Meza, César A.; Gutiérrez, Carlos; Maciel-Barboza, F. M.

doi:10.1109/latincom.2018.8613204

Cited by 2 publications

(9 citation statements)

References 14 publications

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“…1. We note that a WSSUS channel model is obtained from (10) if the factor τ ℓ (t)(f c + f ) is replaced by f 0 D t + f τ 0 , as this is equivalent to assume that f Dℓ (f ) = f 0 D for all |f | ≤ B/2 and τ ℓ (t) = τ 0 ℓ for all t. The reader is referred to [22] for a detailed description of the four channel estimation techniques and our simulation set up.…”

Section: Influence Of the Frequency-varying Ds On The Performance Of A Vehicular Communication Systemmentioning

confidence: 99%

Doppler Shift Characterization of Wideband Mobile Radio Channels

Gutiérrez

Pätzold

Ortega

et al. 2019

IEEE Trans. Veh. Technol.

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The prevailing approach for characterizing the Doppler shift (DS) of mobile radio channels assumes the transmission of an unmodulated carrier. This consideration is valid for the analysis of narrowband channels, but its pertinence is questionable in regards to the modeling of wideband channels. In this correspondence, we redefine the DS from a time-frequency analysis perspective that does not depend on the aforementioned assumption. We systematically demonstrate that the DS can be characterized by the instantaneous frequency of the channel transfer function. This generic definition makes evident a fundamental aspect of the DS that is seldom acknowledged, namely, the DS is a frequency-varying quantity. We show that the secondorder statistics of wideband mobile radio channels are nonstationary due to the DS's frequency variations. In addition, we present numerical results of a case study showing that such non-stationarities can cause significant system performance degradations.

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Section: Influence Of the Frequency-varying Ds On The Performance Of A Vehicular Communication Systemmentioning

confidence: 99%

Doppler Shift Characterization of Wideband Mobile Radio Channels

Gutiérrez

Pätzold

Ortega

et al. 2019

IEEE Trans. Veh. Technol.

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“…In VCSs, the particular propagation conditions of the vehicular environment make channel estimation and equalization a relevant challenge, especially because the high velocity of vehicles leads to variations in time and frequency [6]. In order to adapt to the harsh vehicular channel, the effective data rates of the IEEE 802.11p amendment were reduced to half in comparison to IEEE 802.11-based standards [7].…”

Section: Introductionmentioning

confidence: 99%

“…In order to adapt to the harsh vehicular channel, the effective data rates of the IEEE 802.11p amendment were reduced to half in comparison to IEEE 802.11-based standards [7]. Traditional IEEE 802.11-based standards are the basis of Wireless Fidelity (WiFi) systems, which are commonly used in indoor scenarios and characterized by their low mobility [6,7]. Despite the particular propagation conditions of the vehicular environment and the high mobility of the vehicles, no modifications were made to the IEEE 802.11p amendment regarding the channel estimation techniques adopted by traditional IEEE 802.11-based standards.…”

Section: Introductionmentioning

confidence: 99%

“…A well-known channel estimation technique is the Least Squares (LS), which estimates the impulse response of the channel at the start of a frame [8]. LS works well for typical indoor Orthogonal Frequency Division Multiplexing (OFDM) systems; however, its performance is degraded in vehicular environments because the channel changes rapidly over time, which is more critical for higher velocities [6]. Another channel estimation technique corresponds to the Spectral Temporal Averaging (STA) [9], which uses time and frequency dependencies to properly perform the estimation stage.…”

Section: Introductionmentioning

confidence: 99%

“…Finally, the signal is demodulated, and the data can be recovered. The signal received after the FFT operation is given as follows [6]…”

Section: Introductionmentioning

confidence: 99%

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Semi-Supervised Extreme Learning Machine Channel Estimator and Equalizer for Vehicle to Vehicle Communications

et al. 2021

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Wireless vehicular communications are a promising technology. Most applications related to vehicular communications aim to improve road safety and have special requirements concerning latency and reliability. The traditional channel estimation techniques used in the IEEE 802.11 standard do not properly perform over vehicular channels. This is because vehicular communications are subject to non-stationary, time-varying, frequency-selective wireless channels. Therefore, the main goal of this work is the introduction of a new channel estimation and equalization technique based on a Semi-supervised Extreme Learning Machine (SS-ELM) in order to address the harsh characteristics of the vehicular channel and improve the performance of the communication link. The performance of the proposed technique is compared with traditional estimators, as well as state-of-the-art machine-learning-based algorithms over an urban scenario setup in terms of bit error rate. The proposed SS-ELM scheme outperformed the extreme learning machine and the fully complex extreme learning machine algorithms for the evaluated scenarios. Compared to traditional techniques, the proposed SS-ELM scheme has a very similar performance. It is also observed that, although the SS-ELM scheme requires the largest operation time among the evaluated techniques, its execution time is still far away from the latency requirements specified by the standard for safety applications.

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On the Influence of the non-WSSUS Condition in the Performance of IEEE 802.11-Based Channel Estimators for Vehicular Communications

Cited by 2 publications

References 14 publications

Doppler Shift Characterization of Wideband Mobile Radio Channels

Doppler Shift Characterization of Wideband Mobile Radio Channels

Semi-Supervised Extreme Learning Machine Channel Estimator and Equalizer for Vehicle to Vehicle Communications

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