Oyunchimeg Shagdar

Vehicle to pedestrian communications for protection of vulnerable road users

Vehicle and pedestrian collisions often result in fatality to the vulnerable road users, indicating a strong need of technologies to protect such vulnerable road users. Wireless communications have potential to support road safety by enabling road users to exchange information. In contrast to vehicle to vehicle (V2V) and vehicle to infrastructure (V2I) communications for avoidance of inter-vehicle collisions, very limited efforts are made on communication mechanisms for pedestrian safety. This paper addresses the issue in a concrete way. We first formulate the requirement of the minimum information exchange distance for providing road users to have the necessary amount of time to perceive the situation and react. We then report our field tests and measurement based analysis to investigate if a Wi-Fi system can satisfy the application requirement. We also introduce a pedestrian protection application, V2ProVu, which provides the functionalities of the Wi-Fi communications, risk calculation, and hazard alarming. Our study discloses several useful insights including 1) information exchange for a velocity of 80 km/h has to be made before vehicle to pedestrian (V2P) distance is below 72 meters and 2) while this requirement is not too hard for radio communications technologies, the V2P communication range is greatly reduced if the signal is blocked by a human body.

Platooning control using visible light communications: A feasibility study

The major benefits of driving vehicles in controlled close formations such as platoons are that of increasing traffic fluidity and reducing air pollution. While Vehicle-toVehicle (V2V) communications is requisite for platooning stability, the existing radio communications technologies (e.g., the IEEE 802.11p) suffer from poor performance in highly dense road scenarios, which are exactly to be created by platooning. This paper studies the applicability of visible light communications (VLC) system for information exchange between the platoon members. A complete VLC model is built enabling precise calculations of Bit-Error-Rate (BER) affected by inter-vehicle distance, background noise, incidence angle and receiver electrical bandwidth. Based on our analytical model, the optical parameters suiting platooning application are defined. Finally, a SIMULINK model is developed to study the performances of a platooning longitudinal and lateral control, where VLC is used for V2V information exchange. Our study demonstrates the feasibility of VLC-based platooning control even in the presence of optical noise at significant levels and up to a certain road curvature.

Study on Perception and Communication Systems for Safety of Vulnerable Road Users

The existing R&D efforts for protecting vulnerable road users (VRU) are mainly based on perception techniques, which aim to detect VRUs utilizing vehicle embedded sensors. The efficiency of such a technique is largely affected by the sensors visibility condition. Vehicle-to-Pedestrian (V2P) communication can also contribute to the VRU safety by allowing vehicles and pedestrians to exchange information. This solution is, however, largely affected by the reliability of the exchanged information, which most generally is the GPS data. Since perception and communication have complementary features, we can expect that a combination of such approaches can be a solution to the VRU safety. This is the motivation of the current work. We develop theoretical models to present the characteristics of perception and communications systems. Experimental studies are conducted to compare the performances of these techniques in real-world environments. Our results show that the perception system reliably detects pedestrians and other objects within 50 m of range in the line-of-sight (LOS) condition. In contrast, the V2P communication coverage is approximately 340 and 200 meters in LOS and non-LOS (NLOS) conditions, respectively. However, the communication-based system fails to correctly position the VRU w.r.t the vehicle, preventing the system from meeting the safety requirement. Finally, we propose a cooperative system that combines the outputs of the communication and perception systems.

Extended mobility management and routing protocols for internet-to-VANET multicasting

Emerging ITS applications such as fleet management and point of interest distribution require vehicles to have Internet access. However, allowing vehicles to access to the Internet is particularly challenging due to the special characteristics of the vehicular environment. So far, multicasting approaches have been demonstrated to be effective for supporting group communication in traditional networks. However, such Internet-to-VANET multicast service involves several challenges including efficient multicast mobility management and multicast message delivery. This paper proposes a scheme that combines the existing multicast mobility management scheme with vehicular networking solutions to achieve Internet-to-VANET multicasting. The proposed scheme aims to: (i) provide multicast mobility management with low control overhead and efficient bandwidth utilization, as well as (ii) extend the service coverage provided by VANET membership management and multicast message delivery protocol. Simulation results indicate that our Motion-MAODV scheme improves the performance of both MAODV and traditional flooding dissemination schemes in terms of both packet delivery ratio and end-to-end transmission latency.

Beacon delivery over practical V2X channels

The problem of modelling V2X system based on partial (RSSI) measurements of the wireless propagation channel is considered. The study shows that the dual slope linear model well approximates pathloss in the V2X systems. We also show that in addition to distance dependent pathloss, incorporation of fast fading as well as its frequency selectivity have significant effect on the overall performance of the system. Interference from simultaneous transmissions is estimated based on medium access control (MAC) and realistic road traffic models. Our simulation results show how car traffic parameters and MAC behavior provide direct impact on the effective communication range of the V2X system.

Optimisation of spatial CSMA using a simple stochastic geometry model for 1D and 2D networks

In modern wireless networks especially in Machine-to-Machine (M2M) systems and in the Internet of Things (IoT) there is a high densities of users and spatial reuse has become an absolute necessity for telecommunication entities. This paper studies the maximum throughput of Carrier Sense Multiple Access (CSMA) in scenarios with spatial reuse. Instead of running extensive simulation with complex tools which would be somewhat time consuming, we evaluate the spatial throughput of a CSMA network using a simple model which produces closed formulas and give nearly instantaneous values. This simple model allows us to optimize the network easily and study the influence of the main network parameters. The nodes will be deployed as a Poisson Point Process (PPP) of a one or two dimensional space. To model the effect of (CSMA), we give random marks to our nodes and to elect transmitting nodes in the PPP we choose those with the smallest marks in their neighborhood. To describe the signal propagation, we use a signal with power-law decay and we add a random Rayleigh fading. To decide whether or not a transmission is successful, we adopt the Signal-over-Interference Ratio (SIR) model in which a packet is correctly received if its transmission power divided by the interference power is above a capture threshold. We assume that each node in our PPP has a random receiver at a typical distance from the transmitter i.e. the average distance between a node and its closest neighbor. We also assume that all the network nodes always have a pending packet. With all these assumptions, we analytically study the density of throughput of successful transmissions and we show that it can be optimized with regard to the carrier-sense threshold.

Study and evaluation of laser-based perception and light communication for a platoon of autonomous vehicles

Visible Light Communication (VLC) is a new emerging technology that is being proposed as a reliable and supportive choice for short range communications in ITS. On the same context, Laser Range Finders (LRF) sensors are used for the vehicular environment perception. Compared to VLC, LRF can provide more coverage range and extended viewing angle. To take the full advantages of both technologies features, this paper studies and demonstrate the proposal of using VLC for information exchange among the platoon members and LRF for inter-vehicle distance estimation. A hand-over algorithm is proposed to manage the switching process for any failure occurrence by assessing LRF and VLC performance using three different metrics: LRF confidence value, vehicles angular orientation, and the VLC link latency. The evaluation of the proposed system is verified using VLC prototype and Pro- SiVIC Simulator driving platoon of two autonomous vehicles over different curvature scenarios. Our results show that the proposed combination are extending the VLC limitations and satisfying the platooning requirement. However, in the very sharp curvature, LRF was capable of driving the platoon except for the 90° curve scenario, the system experienced non-stable behaviour due to the LRF area of interest limitation.

Visible Light inter-vehicle Communication for platooning of autonomous vehicles

In this paper, we study a use of Visible Light Communication (VLC) technology for a platoon of autonomous vehicles. We present a low-cost, low-latency and simple outdoor VLC prototype, which can be installed as a vehicular tail-lighting system. The architecture of our VLC system is introduced, followed by performance evaluation with an especial attention on the VLC link resilience to ambient noise and communication range. Through the experiments, we observe that a use of proper optical filter stage at the receiver side, together with narrowing the transmitter Field-of-view (FOV), result in an extended communication range and make the VLC system more resilient to the ambient noises. Experimental results show that the system can provide 30 meters of inter-vehicle communication with 36 ms of latency, yet on sunny day conditions. The benefit of using the VLC system for platooning control is showed using a Simulink system that integrates our VLC platform for inter-communications to simulates the performance of autonomous vehicles platoon.

Study on merging control supported by IEEE 802.11p systems for highway environments

Cooperative Adaptive Cruise Control (CACC) systems are intended to make driving safer and more efficient by utilizing information exchange between vehicles (V2V) and/or between vehicles and infrastructures (V2I). An important application of CACC is safe vehicle merging when vehicles join a main road, achieved by compiling information on the movement of individual main road vehicles. To support such road safety applications, the IEEE standardized the 802.11p amendment dedicated to V2V and V2I communications. This paper seek answers to the questions as to whether the IEEE 802.11p can support merging control and how the communications performance is translated into the CACC performance. We build an analytical model of the IEEE 802.11p medium access control (MAC) for transmissions of the ETSI-standardized Cooperative Awareness Messages (CAM) and Decentralized Environmental Notification Messages (DENM) to support merging control. We also developed a highway merging decision algorithm. Using computer simulations, packet delivery ratio (PDR), and packet inter-reception (PIR) time of IEEE 802.11p-based V2V and V2I communications and their impact on the CACC performance are investigated. Our study discloses several useful insights including that PIR and throughput provide a good indication of the CACC performance, while improving PDR does not necessarily enhance the CACC performance. Moreover, thanks to its ability to reliably provide information at constant time intervals, the V2I structure preferred over V2V as a support for CACC.

Performance study of CAM over IEEE 802.11p for cooperative adaptive cruise control

The IEEE 802.11p is the de-facto vehicular radio communication technology for road safety and efficiency applications. With the advancements in the autonomous vehicle technology, studies on applicability of the IEEE 802.11p and the related protocols for the autonomous driving applications are needed. In this paper, we study the impacts of vehicular communication on platooning control considering that the ETSI-standardised message set Cooperative Awareness Message (CAM) and the IEEE 802.11p are used for both the platooning and cooperative awareness applications. We first develop a theoretical model for the probability of a successful CAM transmission over IEEE 802.11p between platoon members by taking account of the existence of non-platoon vehicles on the road. The model is verified by comparing against simulation results obtained from the NS3 simulator. Finally, we investigate the impacts of the communication performance on the behaviour of platoons, specially the chain stability, when hundreds of vehicles share the wireless channel. The theoretical model reveals that thanks to the capture effect, communications between platoon members drastically outperform communications between arbitrary two vehicles on the road. The simulation results show that in contrast to an adaptive cruise control (ACC), which does not use vehicular communication, the IEEE 802.11p based vehicle to vehicle (V2V) communication aids for realizing stable platoons in highway scenarios.