Cooperative Intelligent Transport Systems: 5.9-GHz Field Trials

Cohda Wireless Pty. Ltd., Adelaide, SA, Australia
Proceedings of the IEEE (Impact Factor: 4.93). 08/2011; 99(7):1213 - 1235. DOI: 10.1109/JPROC.2011.2105230
Source: IEEE Xplore


The mobile outdoor radio environment is challenging for vehicular communications. Although multipath propagation offers diversity and benefits in non-line-of-sight (NLOS) conditions, simultaneous multipath and mobility results in a doubly-selective fading channel. In practice, this means that the channel parameters vary significantly in both time and frequency within the bandwidth and typical packet durations used in 802.11p/WAVE standards for short-range vehicular communications. This paper presents the results of extensive field trial campaigns conducted in several countries, totaling over 1100 km. These field trials are scenario based, focusing on challenging low-latency, high-reliability vehicle-to-vehicle (V2V) safety applications including intersection collision warning, turn across path, emergency electronic brake light, do not pass warning, and precrash sensing. Vehicle-to-infrastructure (V2I) applications are also considered. The field trials compared the performance of off-the-shelf WiFi-based radio equipment with a more advanced 802.11p compliant radio employing more sophisticated channel estimation and tracking. Field trial results demonstrate significantly improved performance using the advanced radio, translating into greatly increased driver warning times and stopping distances. In fact the results show that off-the-shelf WiFi equipment fails to provide sufficient stopping distance to avert accidents in some cases. During the field trials, channel sounding data were also captured. Analysis of these channel measurements reveals the critical importance of accurate channel estimation, tracking the channel in both time and frequency within each packet. Delay spread and Doppler spread statistics computed from the channel measurements validate previously reported results in the literature. The results in this paper, however, provide the first instance of channel measurements performed simultaneously to application performance evaluation. The objective is to-
firmly establish the link between radio channel characteristics and the performance of critical V2V safety applications.

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    • "As a part of the assigned driving task, each vehicle i is tracking a reference velocity v ir (t). 2) State and control constraints: Each vehicle i is subject to state and control constraints x i (t) ∈ [x imin (t), x imax (t)], ∀i ∈ N , (3) u i (t) ∈ [u imin (t), u imax (t)], ∀i ∈ N ,(4)where the inequalities are imposed for all time instances t ∈ [0, t if ]. The final time t if , when the vehicle reaches its final destination p if , is free. "
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    ABSTRACT: We study the problem of optimally controlling autonomous vehicles to safely cross an intersection. The problem is approached by solving an optimal control subproblem for all permutations of crossing sequences. For a chosen crossing sequence, we show that the subproblem of optimal longitudinal vehicle control, subject to collision avoidance constraints, can be formulated as a convex program. The proposed method transforms the problem from the original time domain to a space domain, and introduces a change of optimization variables by replacing vehicles' speed with its inverse. A case study is provided showing the effectiveness of the proposed method.
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    • "IEEE 802.11p [2], [3] has emerged as the most accepted standard for wireless access in vehicle-to-vehicle [4] and vehicle-to-infrastructure [5] communication. The claim can be further supported by citing some real world implementations on the road [6] and on the seaport [7]. The 802.11p standard is part of the more versatile IEEE 802.11 standard and includes amended specifications necessary for wireless communication in a vehicular environment. "
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    ABSTRACT: The article presents out-of-vehicle channel measurement results in the 5.8 GHz frequency band which is used in the IEEE 802.11p standard. Experiments for two different distances and three different angles around the parked car are carried out. It is found that a two-term exponential decay model can satisfactorily describe the mean measured power delay profiles. For each measurement, this large scale variation is used to calculate the corresponding channel impulse response and to construct a Rician tap-delay multipath channel model. Bit error rate (BER) performance for each measured location is then evaluated through MATLAB based simulation. The simulation results indicate that the error performances do not vary much and it is possible to determine an average BER curve for the whole set of data.
    Full-text · Conference Paper · Oct 2015
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    • "A similar study was reported in our previous work [6], where we concentrated on the evaluation of the impact of vegetation on V2V communication through a 5.9 GHz measurement campaign conducted at intersections with different types of vegetation. In [7], results for 35 field trial data sets collected in Australia, Austria, Germany, Italy, and the United States, covering over 1100 km on the road in a wide variety of physical environments were presented. The performance of commercial off-the-shelf radio wireless card compared with a more advanced 802.11p compliant radio was also presented. "
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