A differential OFDM approach to coherence time mitigation in DSRC

Zhang, Youwei; Tan, Ian L.; Chun, C.; Laberteaux, Kenneth P.; Bahai, A.

doi:10.1145/1410043.1410045

Cited by 24 publications

(10 citation statements)

References 11 publications

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“…On the other hand, [10] proposed a method that is based on the time-domain differentiation to compensate for the short coherence time of the channel. Although this method is both facile and robust, it requires modification to the IEEE 802.11p standard.…”

Section: Enhanced Channel Estimation Algorithm For Dedicated Short-ramentioning

confidence: 99%

“…Therefore, the propagation paths and their respective delays and Doppler shifts are considered invariant for the duration of several dozens of symbols. Moreover, because the Doppler shifts are far smaller than the sampling frequency, according to equation (10), the DDE vector i b changes slowly and thus can be more easily estimated and predicted.…”

Section: Ddp Channel Estimation Schemementioning

confidence: 99%

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Enhanced Channel Estimation Algorithm for Dedicated Short-Range Communication Systems

Liu

Van

2015

TELKOMNIKA

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The Dedicated Short-Range Communication (DSRC) has been widely accepted as a promising wireless technology for enhancing traffic safety. In such Keywords: dedicated short range communications (DSRC), IEEE 802.11p standard, orthogonal frequency division multiplexing (OFDM), channel estimationCopyright © 2015 Universitas Ahmad Dahlan. All rights reserved. IntroductionDedicated Short-Range Communications (DSRC) is a wireless communication technique that enhances the safety and efficiency of transportation systems by enabling for a high-speed data exchange between vehicles. The U.S. Department of Transportation has estimated that vehicle-to-vehicle (V2V) communication can be used to manage up to 82% of all crashes arising from unimpaired drivers [1]. Currently, the most common worldwide DSRC standard is the IEEE 802.11p [2], which is based on orthogonal frequency division multiplexing (OFDM) [3]. Due to the high mobility of vehicles, the channels within the vehicular communication scenarios vary significantly in both time and frequency domain. Compared to the indoor channels, the time-varying characteristic of wireless propagation channels is a severe obstacle for reliable packet delivery. We focus on the practical methods for improving the reliability of V2V communications using enhanced channel estimation inherent to the IEEE 802.11p standard.The V2V channel propagation characteristics differ significantly from those of cellular and indoor stationary channels, especially in terms of their frequency-selectivity, time-selectivity, and associated fading statistics [4,5]. Time-variation results in a short channel coherence time, which causes the channel to change significantly from the start of the packet to the end of the packet. A commercially-available channel estimation scheme for chip set implementation in an indoor environment is the preamble-based least square (LS) [3] estimator. In the V2V communication environment, however, the LS estimator will significantly degrade system performance because it neglects the time-varying characteristic. A simple and accurate method to trace the time-varying channel is a linear interpolation either in the frequency direction only or the time-frequency-direction [6][7][8][9]. However, only four sub-carriers are allocated as pilots in the IEEE 802.11p standard, and they are not spaced closely enough to accurately sample the

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Section: Enhanced Channel Estimation Algorithm For Dedicated Short-ramentioning

confidence: 99%

Section: Ddp Channel Estimation Schemementioning

confidence: 99%

Enhanced Channel Estimation Algorithm for Dedicated Short-Range Communication Systems

Liu

Van

2015

TELKOMNIKA

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“…However, solutions exist that overcome these limitations, e.g. by using an advanced receiver as proposed in Alexander et al (2007) in which a time-domain channel estimation and a frequency-domain channel tracking are performed to equalize the channel, or by using differential OFDM modulation proposed in Zhang et al (2008). IEEE 802.11p specifies more adaptions that hardware devices have to fulfill, e.g.…”

Section: Physical Layermentioning

confidence: 99%

MAC Layer and Scalability Aspects of Vehicular Communication Networks

Mittag

Schmidt-Eisenlohr

Killat

et al. 2009

Vanet

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“…For instance, the coherence time of the channel, i.e. the time during which the channel impulse response is essentially invariant, can be smaller than the duration of a single packet transmission [6], which could result in an increased probability of bit and packet errors. This is an issue, since the IEEE 802.11p frame format provides only a preamble to fully estimate the channel and only four pilot sub-carriers to partially track the state of the channel [7].…”

Section: Introductionmentioning

confidence: 99%

“…This is an issue, since the IEEE 802.11p frame format provides only a preamble to fully estimate the channel and only four pilot sub-carriers to partially track the state of the channel [7]. Hence, the initial estimate can become invalid at the end of the reception leading to an increased probability of bit and packet errors [6]. As a consequence, the channel impulse response of two consecutive packet transmissions will most likely not be correlated, and the channel can only be considered symmetric for an instant of time, but not for slightly different timestamps.…”

Section: Introductionmentioning

confidence: 99%

Congestion and Awareness Control in Cooperative Vehicular Systems

et al. 2011

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Abstract-Cooperative vehicular systems have been identified as a promising solution to overcome the current and future needs for increasing traffic safety and efficiency, while providing infotainment and added-value services on the move. To achieve their objectives, cooperative vehicular systems will be based on wireless communications between vehicles and with other infrastructure nodes, and will have to deal with highly dynamic nodes, challenging propagation conditions, and stringent application requirements. By looking at cooperative applications and their data traffic, as well as the current and foreseen spectrum allocations for cooperative vehicular systems, there is a risk that the corresponding radio channels could easily be saturated if no control algorithms are used. The saturation of the radio channels would result in unstable vehicular communications, and thus in an inefficient operation of cooperative systems. As a prime example of upcoming ubiquitous networks contributing to the vision of "a thousand radios per person", cooperative vehicular systems need to be designed to scale to high densities of radios without centralized coordination, while at the same time guaranteeing the requirements of the implemented applications and services, for example the stringent needs of active traffic safety applications. In this paper, we survey and classify various decentralized methods to control the load on the radio channels and to ensure each vehicle's capacity to detect and communicate with the relevant neighbouring vehicles, with a particular focus on approaches based on transmit power and rate control. Finally, we discuss the open research challenges that are imposed by different application requirements and potential existing contradictions.

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A differential OFDM approach to coherence time mitigation in DSRC

Cited by 24 publications

References 11 publications

Enhanced Channel Estimation Algorithm for Dedicated Short-Range Communication Systems

Enhanced Channel Estimation Algorithm for Dedicated Short-Range Communication Systems

MAC Layer and Scalability Aspects of Vehicular Communication Networks

Congestion and Awareness Control in Cooperative Vehicular Systems

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