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

Evaluation of Interference-Cancellation Based MAC Protocols for Vehicular Communications

Vehicular communications form an important part of future intelligent transport systems. Wireless connectivity between vehicles can enhance safety in vehicular networks and enable new services such as adaptive traffic control, collision detection and avoidance. As several new algorithms are being developed for enhancing vehicle to vehicle wireless connectivity, it is important to validate the performance of these algorithms using reasonably accurate wireless channel models. Specifically, some recent developments in the medium access control (MAC) layer algorithms appear to have the potential to improve the performance of vehicle to vehicle communications; however, these algorithms have not been validated with realistic channel models encountered in vehicular communications. The aforementioned issues are addressed in this thesis and correspondingly, there are two main contributions - (i) A complete IEEE 802.11p based transceiver model has been simulated in MATLAB and its performance & reliability are tested using existing empirically-developed wireless channel models. (ii) A new MAC layer algorithm based on slotted ALOHA with successive interference cancellation(SIC) has been evaluated and tested by taking into consideration the performance of underlying physical layer. The performance of slotted ALOHA-SIC and the already existing carrier sense multiple access with collision avoidance (CSMA/CA) scheme with respect to channel access delay and average packet loss ratio is also studied

Simulation of WLAN Based V2X Signal Models Using Deterministic Channel

Vehicle to everything (V2X) communication is one of the important topics in the telecommunication field aiming to provide a great improvement in the transport sector by increasing safety and comfort while driving as well as reducing traffic congestion and as a result there are a lot of researches , developments and investments made in this field. This thesis presents the use of Unity 3D game engine program for the creation of a deterministic channel model through which we can analyse and study the performance of the WLAN based signal models that are used in the vehicle to everything (V2X) technology.AN open source V2X simulator was used for the process of channel creation and performance assessment making use of its real time stochastic measurements .Two different methods were used to assess the performance of both the IEEE 802.11p and 802.11bd signal models with different calculations but eventually the latter proved to be the superior since it is considered the most advanced and latest version of the IEEE 802.11 family

Open Platforms for Connected Vehicles

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Degradation of Communication Range in VANETs Caused by Interference 2.0 - Real-World Experiment

High channel load in vehicle-to-vehicle communication leads to a degradation of the vehicles’ communication range, due to interference and hence packet loss at larger distances. Packet loss results from two or more concurrent transmissions, colliding at receivers located inbetween, which is also known as the hidden station problem. In previous works, our simulation study has shown that this packet loss leads to a degradation of 90% of the communication range. In this paper, we confirm the simulation results by real-world measurements. We present a methodology for transferring the simulation scenario to a real-world measurement scenario, able to evaluate the problem of hidden stations. With three radios applying the IEEE 802.11p standard, we measure the degradation of the communication range under interference. In the measurement, we find a degradation of 50 to 70%. On the one hand, there are less collisions due to only one hidden station. On the other hand, we identify that the receiving vehicle as a shadowing object itself is an additional origin for hiding the other station which slightly increases the number of collisions even at close distances

Beaconing Performance in IEEE 802.11p Vehicular Networks: the Effect of Radio Channel Congestion

In this paper, we study the performance of the beaconing mechanism underlying active safety vehicular applications in presence of different levels of channel congestion. The importance of this study lies in the fact that channel congestion is considered a major factor influencing communication performance in vehicular networks, and that ours is the first investigation of the effects of congestion based on extensive, real-world measurements. The results of our study reveal that congestion has a profound impact on the most important beaconing performance metric, namely, packet (beacon) inter reception time, influencing not only the average value, but also the shape of the distribution. Congestion also considerably increases the frequency of potentially dangerous situation-awareness blackouts, with a likely negative impact on the effectiveness of active safety applications. Our study also reveals that multihop propagation of beaconing information can be used as an effective means of lessening the negative impact of congestion on beaconing performance

Spectral Efficiency and Outage Performance Evaluation of Measured Vehicular Communication Radio Channels

[ES] Los sistemas cooperativos para entornos vehiculares tienen la capacidad de mejorar tanto la seguridad en carretera, como la gestión del tráfico. Tienen como base la norma del estándar de comunicaciones inalámbrico de red de área local (Wireless Local Area Network, WLAN) para el uso comunicaciones vehiculares (Vehicle-to-Vehicle/Infrastructure, V2I), denominada IEEE 802.11p, la cual se está desarrollando actualmente, y que dará lugar a la nueva tecnología de comunicaciones entre vehículos e infraestructura WAVE (Wireless Access in Vehicular Environments). Funcionando en el rango de frecuencias de 5.850 a 5.925 GHz, los sistemas WAVE adoptan la técnica de multiplexación OFDM (Orthogonal Frequency Division Multiplexing) y alcanzan tasas de transmisión de datos en el rango de 6 a 27 Mbps. El estudio del canal es clave para conocer el efecto de las condiciones de propagación reales sobre la transmisión. Habrá que tener en cuenta que en entornos de comunicaciones vehiculares se da la propagación con línea de visión directa (Line of Sight, LoS), por lo que a la hora de caracterizar el canal, habrá que considerar tanto el desvanecimiento Rayleigh como el desvanecimiento Ricean. Este estudio se hará a partir del procesado de la función de transferencia del canal obtenido para diferentes escenarios durante la campaña de medidas realizada en Lund, Suecia. en 2007 por la Universidad Técnica de Viena. El sistema radio utilizado considera múltiples antenas, es decir, el canal es Multiple-Input Multiple-Output (MIMO), dado que gracias a la diversidad consigue un mayor rendimiento. De cara a analizar el efecto de las condiciones de propagación sobre el rendimiento alcanzable, se caracterizará el canal mediante el Power Delay Profile (PDP) y el perfil de Path Loss. A continuación se estudiarán más en detalle los canales MIMO con desvanecimiento Ricean, cruciales para las comunicaciones Vehicle-to-Vehicle, (V2V). En estos canales hay una tasa de datos crítica (RCRIT) dependiente de una relación señal a ruido (Signal-to- Noise Ratio, SNR) bajo la cual la transmisión de datos con cero outage es posible, de manera que el canal se comporta como un canal con ruido aditivo gaussiano (Additive White Gaussian Noise, AWGN). Se analizará la tanto eficiencia espectral en términos de capacidad ergódica y como la probabilidad de outage del canal vehicular para diferentes valores de relación señal a ruido.[EN] Roadway-vehicle cooperative systems will lead to improve driving safety. These systems relay on a wireless local area network (WLAN) standard for automotive use, called IEEE 802.11p, which is under development in order to implement Wireless Access in Vehicular Environments (WAVE). Operating at 5.850¿5.925 GHz, WAVE systems adopt orthogonal frequency-division multiplexing (OFDM) and achieve data rates of 6¿27 Mbps. The development of efficient vehicle-to-vehicle (V2V) communications systems requires an understanding of the underlying radio propagation channels in order to analyze the real impact of real-world propagation conditions. Vehicular communication channels are non-stationary, because the conditions of the channel vary abruptly due to the speed of the vehicles. The studied wireless communication scenario is predominantly Line of Sight (LoS) propagation scenario, therefore Rayleigh fading and Ricean fading have to be considered for channel characterization. The reference data to be analyzed have been obtained from a channel sounding campaign carried out by the Vienna University of Technology in Lund, Sweden in 2007. The radio system used for this campaign is a multiple-input multiple-output (MIMO) system. Radio channel parameters such as the power delay profile and the path loss are going to be analyzed in order to study the impact of real-world propagation conditions. Reliability in Ricean MIMO channel is going to be more deeply characterized, as it is crucial for safety related V2V applications. In such channels, there is a SNR-dependent critical data rate (RCRIT) below which signaling with zero outage is possible, and hence the fading channel behaves like an AWGN channel. For the vehicular time variant channel spectral efficiency is going to be evaluated in terms of ergodic capacity and outage performance is also going to be studied by means of outage probability.Alonso Gómez, A. (2009). Spectral Efficiency and Outage Performance Evaluation of Measured Vehicular Communication Radio Channels. http://hdl.handle.net/10251/27442.Archivo delegad

Robust Low-Cost Multiple Antenna Processing for V2V Communication

Cooperative V2V communication with frequent, periodic broadcast of messages between vehicles is a key enabler of applications that increase traffic safety and traffic efficiency on roads. Such broadcast V2V communication requires an antenna system with omnidirectional coverage, which is difficult to achieve using a single antenna element. For a mounted, omnidirectional antenna on a vehicle is distorted by the vehicle body, and exhibits a nonuniform directional pattern with low gain in certain directions. The thesis addresses this problem by developing schemes that employ multiple antennas (MAs) to achieve an effective radiation pattern with omnidirectional characteristics at both the transmit- and the receive-side. To ensure robust communication, the MA schemes are designed to minimize the burst error probability of several consecutive status messages in a scarce multipath environment with a dominant path between vehicles.First, at the receive-side, we develop a hybrid analog-digital antenna combiner. The analog part of the combiner is composed of low-cost analog combining networks (ACNs) of phase shifters that do not depend on channel stateinformation (CSI), while the digital part uses maximal ratio combining. We show that the optimal phase slopes of the analog part of the combiner (i.e., the phase slopes that minimize the burst error probability) are the same found under the optimization of a single ACN, which was done in earlier work. We then show how directional antennas can be employed in this context to achieve an effective omnidirectional radiation pattern of the antenna system that is robust in all directions of arrival of received signals.Secondly, at the transmit-side, we develop two low-cost analog MA schemes, an analog beamforming network (ABN) of phase shifters, and an antenna switching network (ASN), for the case when receivers employ the ACN or the hybrid combiner. Both schemes are shown to achieve an effective radiation pattern with improved omnidirectional characteristics at the transmit-side without relying on CSI.Thirdly, the schemes above were developed assuming that all vehicles broadcast their messages with the same fixed period. Therefore, we tackle the practical scenario when different vehicles use different and potentially varying broadcast periods. We show that the phase slopes of the MA schemes at the receiver and/or transmitter can be designed to support multiple broadcast periods.\ua0Lastly, the optimal phase slopes of the MA schemes were analytically derived under a worst-case propagation corresponding to a dominant path with an angle of departure, and an angle of arrival that are approximately non-varying over the time it takes to transmit and receive several packets. We relax this assumption and study the system performance under a time-varying dominant component instead. We derive a design rule that yields robust phase slopes that effectively mitigate the losses due to the time-variation of the dominant path

Understanding Vehicle-to-Vehicle IEEE 802.11p Beaconing Performance in Real-World Highway Scenarios

Periodic exchange of situational information (beacons) is at the basis of most active safety applications in vehicular environments. Despite its fundamental role in raising the level of "situational awareness" onboard vehicles, very little is known to date on beaconing performance in a real vehicular environment. This paper analyzes the results of two measurement campaigns that have been designed with the purpose of disclosing beaconing performance in a variety of vehicular links, for what concerns vehicle configuration (tall/short), line-of-sight conditions (LOS/NLOS), as well as single-hop or two-hop propagation of the information reported in the beacons. For the first time, beaconing performance is characterized in terms of not only the packet (beacon) delivery rate (PDR), but also in terms of the packet (beacon) inter-reception (PIR) time. The latter metric has been suggested in the literature as more accurately measuring the level of "situation awareness" onboard vehicles than the traditional PDR metric. This paper also presents a simulation-based analysis aimed at estimating the benefit of multi-hop propagation of situational information beyond the second hop of communication. The analysis of the data collected in the measurement campaigns as well as the simulation-based analysis disclose a number of interesting insights which might prove useful in the design of active safety applications. Finally, another major contribution of this paper is promoting the Gilbert-Elliot model, previously proposed to model bit-error bursts in packet switched networks, as a very accurate model of beacon reception behavior observed in real-world scenarios