Path loss modeling for vehicular system performance and communicaitons protocols evaluation

Vehicular communications are receiving considerable attention due to the introduction of the intelligent transportation system (ITS) concept, enabling smart and intelligent driving technologies and applications. To design, evaluate and optimize ITS applications and services oriented to improve vehicular safety, but also non-safety applications based on wireless systems, the knowledge of the propagation channel is vital. In particular, the mean path loss is one of the most important parameters used in the link budget, being a measure of the channel quality and limiting the maximum allowed distance between the transmitter (Tx) and the receiver (Rx). From a narrowband vehicular-to-vehicular (V2V) channel measurement campaign carried out at 5.9 GHz in three different urban environments characterized by high traffic density, this paper analyzes the path loss in terms of the Tx-Rx separation distance and fading statistics. Based on a linear slope model, values for the path loss exponent and the standard deviation of shadowing are reported. We have evaluated the packet error rate (PER) and the maximum achievable Tx-Rx separation distance for a PER threshold level of 10% according to the digital short-range communications (DSRC) specifications. The results reported here can be incorporated in an easy way to vehicular networks (VANETs) simulators in order to develop, evaluate and validate new protocols and systems architecture configurations under realistic propagation conditions.Fernández González, HA.; Rubio Arjona, L.; Reig, J.; Rodrigo Peñarrocha, VM.; Valero-Nogueira, A. (2013). Path loss modeling for vehicular system performance and communicaitons protocols evaluation. Mobile Networks and Applications. 18(6):755-765. doi:10.1007/s11036-013-0463-xS755765186Gallager B, Akatsuka H, Suzuki H (2006) Wireless communications for vehicle safety: radio link performance and wireless connectivity. IEEE Veh Technol Mag 1(4):4–24Rubio L, Reig J, Fernández H (2011) Propagation aspects in vehicular networks, Vehicular technologies. Almeida M (ed) InTechWang C-X, Vasilakos A, Murch R, Shen SGX, Chen W, Kosch T (2011) Guest editorial. Vehicular communications and networks – part I. IEEE J Select Areas Commun 29(1):1–6ASTM E2213-03 (2003) Standard specification for telecommunications and information exchange between roadside and vehicle systems – 5 GHz band Dedicated Short Range Communications (DSRC) Medium Access Control (MAC) and Physical Layer (PHY) specifications. American Society for Testing Materials (ASTM), West ConshohockenIEEE 1609 – Family of Standards for Wireless Access in Vehicular Environments (WAVE). [Online]. Available: http://www.standards.its.dot.govETSI TR 102 492–2 Part 2 (2006) Technical characteristics for Pan European Harminized Communications Equipment Operating in the 5 GHz frequency range intended for road safety and traffic management, and for non-safety related ITS applications, European Telecommunications Standard Institute (ETSI), Technical Report, Sophia Antipolis, FranceThe Car-to-Car Communication Comsortium (C2CC): http:/www.car-to-car.orgMecklenbräuker C, Molisch A, Karedal J, Tufvesson F, Paier A, Bernado L, Zemen T, Klemp O, Czink N (2011) Vehicular channel characterization and its implications for wireless system design and performance. IEEE Proc 99(7):1189–1212Ghafoor KZ, Bakar KA, Lloret J, Khokhar RH, Lee KC (2013) Intelligent beaconless geographical routing for urban vehicular environments. Int J Wireless Netw 19(3):345–362Ghafoor KZ, Lloret J, Bakar KA, Sadiq AS, Mussa SAB (2013) Beaconing approaches in vehicular ad hoc networks: a survey. Int J Wirel Pers Commun. Published Online (May 2013)Michelson DG, Ghassemzadeh SS (2009) New directions in wireless communications, Springer Science+Busines Media (Chapter 1)IEEE 802.11p (2010) Wireless LAN Medium Access Control (MAC) and Physical Layer (PHY) Specifications Amendment 6: Wireless Access in Vehicular Environments, Institute of Electrical and Electronic Engineers (IEEE), New York, USA.Karedal J, Czink N, Paier A, Tufvesson F, Moisch AF (2011) Path loss modeling for vehicle-to-vehicle communications. IEEE Trans Veh Technol 60(1):323–327Cheng L, Henty B, Stancil D, Bai F, Mudalige P (2007) Mobile vehicle-to-vehicle narrow-band channel measurement and characterization of the 5.9 GHz dedicated short range communication (DSRC) frequency band. IEEE J Select Areas Commun 25(8):1501–1516Cheng L, Henty B, Cooper R, Stancil D, Bai F (2008) Multi-path propagation measurements for vehicular networks at 5.9 GHz. IEEE Wireless Communications and Networking Conference, pp. 1239–1244Tan I, Tang W, Laberteaux K, Bahai N (2008) Measurement and analysis of wireless channel impairments in dsrc vehicular communications. IEEE International Conference on Communications, pp. 4882–4888.Campuzano AJ, Fernández H, Balaguer D, Vila-Jiménez A, Bernardo-Clemente B, Rodrigo-Peñarrocha VM, Reig J, Valero-Nogueira A, Rubio L (2012) Vehicular-to-vehicular channel characterization and measurement results. WAVES 4(1):14–24Kunisch J, Pamp J (2008) Wideband car-to-car radio channel measurements and model at 5.9 GHz. IEEE 68th Vehicular Technology Conference, pp. 1–5Gozalvez J, Sepulcre M (2007) Opportunistic technique for efficient wireless vehicular communications. IEEE Veh Technol Mag 2(4):33–39Zang Y, Stibor L, Orfanos G, Guo S, Reumerman H (2005) An error model for inter-vehicle communications in highway scenarios at 5.9 GHz. Proc. Int. Workshop on performance evaluation of wireless ad hoc, sensor, and ubiquitous networks, pp. 49–5

A predefined channel coefficients library for vehicle-to-vehicle communications

It is noticeable that most of VANETs communications tests are assessed through simulation. In a majority of simulation results, the physical layer is often affected by an apparent lack of realism. Therefore, vehicular channel model has become a critical issue in the field of intelligent transport systems (ITS). To overcome the lack of realism problem, a more robust channel model is needed to reflect the reality. This paper provides an open access, predefined channel coefficients library. The library is based on 2x2 and 4x4 Multiple – Input – Multiple – Output (MIMO) systems in V2V communications, using a spatial channel model extended SCME which will help to reduce the overall simulation time. In addition, it provides a more realistic channel model for V2V communications; considering: over ranges of speeds, distances, multipath signals, sub-path signals, different angle of arrivals, different angle departures, no line of sight and line of sight. An intensive evaluation process has taken place to validate the library and acceptance results are produced. Having an open access predefined library, enables the researcher at relevant communities to test and evaluate several complicated vehicular communications scenarios in a wider manners with less time and efforts

Modeling and Analysis of 802.11p Physical Layer for V2X Connected Transport Systems Considering Harsh Operating Conditions and HW Device Performance

Intelligent driving is a promising area for increased safety and comfort. Vehicular communication is an essential part to build such systems. This paper describes the modelling and the implementation of the IEEE 802.11p Physical (PHY) Layer to determine its reliability for vehicle-to-everything (V2X), and particularly vehicle-to-vehicle (V2V), communications in the automotive field. A Matlab/Simulink simulation is carried out to analyze not only the baseband processing of the transceiver, but also the RF hardware part, the physical channel in different operating conditions and environments, and all the main impairments and sources of interferences/noise. The transceiver model consists of three parts, the transmitter, the receiver and the intermediate channel block. The model can be used to explore the performance (bit-rate, successfully delivered packet-rate, latency,..) of V2X links in different conditions (line-of-sight, non-line-of-sight), and environments (urban, suburban, rural and highway), considering single-hop or multi-hop networking, and allowing also dynamically changing the channel characteristics, or even using different modulation and coding schemes and physical transmission parameters. To assess the proposed V2X simulation tool, the simulation results are compared to the theoretical performance and to experimental results, obtained using the NEC LinkBird-MX C2X device. The proposed simulation tool can be useful to study the impact of vehicles distance, speed and operating scenario on the reliability of the communication system, once fixed the hardware apparatus, or to specify the performance of the hardware components needed to ensure a given V2X communication performance

Propagation aspects of vehicle-to-vehicle communications - an overview

Vehicle-to-vehicle (VTV) wireless communications have many envisioned applications in traffic safety, congestion avoidance, etc., but the development of suitable communications systems and standards requires accurate models for the VTV propagation channel. This paper provides an overview of existing VTV channel measurement campaigns, describing the most important environments, and the delay spread and Doppler spreads obtained in them. Statistical as well as geometry-based channel models have been developed based on measurements and intuitive insights. A key characteristic of VTV channels is the nonstationarity of their statistics, which has major impact on the system performance. Extensive references are provided

A Primer on Vehicle-to-Barrier Communications: Effects of Roadside Barriers, Encroachment, and Vehicle Braking

Today, more than half of the traffic fatalities are a result of run-off-road (RoR) crashes, which usually involve a single vehicle. Roadside barriers are often the last means to mitigate the severity of a RoR crash into hazardous objects or features. While the recent research on vehicular communications primarily focus on safety related wireless communications for vehicle-to-vehicle (V2V) and vehicle-to-infrastructure (V2I) scenarios, the interactions between vehicles and barriers in next generation vehicular systems have not been well-studied. In this paper, vehicle-to-barrier (V2B) wireless communication paradigm is introduced as a potential missing link in preventing single-vehicle RoR fatalities1. V2B communications, which take place between vehicles and radios embedded in roadside barriers can contribute to keeping cars on the road and help mitigate RoR crashes. The realization of V2B communication services necessitates an in-depth understanding of the underlying physical characteristics of the environment and channel. To this end, in this paper, some of the first real world field test measurement results of V2B communications are presented. More specifically, the effects of two types of commonly-utilized barriers (rigid concrete barrier and corrugated-beam guardrail) on the V2B channel communications are illustrated. The results show that guardrail barriers exhibit a waveguiding effect on signal transmission, while higher signal attenuation is observed with rigid barriers. Moreover, experiments illustrate the characteristics of V2B orthogonal frequency-division multiplexing (OFDM) communication during vehicle encroachment and braking in terms of received signal strength, error vector magnitude, and phase error statistics. The results highlight that barrier-height antenna deployments result in high channel quality for long distances and are not influenced by mobility and vehicle brake during encroachment scenarios, making them a strong candidate for V2B communications

DSRC Versus LTE-V2X: Empirical Performance Analysis of Direct Vehicular Communication Technologies

Vehicle-to-Vehicle (V2V) communication systems have an eminence potential to improve road safety and optimize traffic flow by broadcasting Basic Safety Messages (BSMs). Dedicated Short-Range Communication (DSRC) and LTE Vehicle-to-Everything (V2X) are two candidate technologies to enable V2V communication. DSRC relies on the IEEE 802.11p standard for its PHY and MAC layer while LTE-V2X is based on 3GPP’s Release 14 and operates in a distributed manner in the absence of cellular infrastructure. There has been considerable debate over the relative advantages and disadvantages of DSRC and LTE-V2X, aiming to answer the fundamental question of which technology is most effective in real-world scenarios for various road safety and traffic efficiency applications. In this paper, we present a comprehensive survey of these two technologies (i.e., DSRC and LTE-V2X) and related works. More specifically, we study the PHY and MAC layer of both technologies in the survey study and compare the PHY layer performance using a variety of field tests. First, we provide a summary of each technology and highlight the limitations of each in supporting V2X applications. Then, we examine their performance based on different metrics

Exploring Smart Infrastructure Concepts to Improve the Reliability and Functionality of Safety Oriented Connected Vehicle Applications

Cooperative adaptive cruise control (CACC), a form of vehicle platooning, is a well known connected vehicle application. It extends adaptive cruise control (ACC) by incorporating vehicle-to-vehicle communications. A vehicle periodically broadcasts a small message that includes in the least a unique vehicle identifier, its current geo-location, speed, and acceleration. A vehicle might pay attention to the message stream of only the car ahead. While CACC is under intense study by the academic community, the vast majority of the relevant published literature has been limited to theoretical studies that make many simplifying assumptions. The research presented in this dissertation has been motivated by our observation that there is limited understanding of how platoons actually work under a range of realistic operating conditions. Our research includes a performance study of V2V communications based on actual V2V radios supplemented by simulation. These results are in turn applied to the analysis of CACC. In order to understand a platoon at scale, we resort to simulations and analysis using the ns3 simulator. Assessment criteria includes network reliability measures as well as application oriented measures. Network assessment involves latency and first and second order loss dynamics. CACC performance is based on stability, frequency of crashes, and the rate of traffic flow. The primary goal of CACC is to maximize traffic flow subject to a maximum allowed speed. This requires maintaining smaller inter-vehicle distances which can be problematic as a platoon can become unstable as the target headway between cars is reduced. The main contribution of this dissertation is the development and evaluation of two heuristic approaches for dynamically adapting headway both of which attempt to minimize the headway while ensure stability. We present the design and analysis of a centralized and a distributed implementation of the algorithm. Our results suggest that dynamically adapting the headway time can improve the overall platoon traffic flow without the platoon becoming unstable