Pedro M. d'Orey

On the Impact of Virtual Traffic Lights on Carbon Emissions Mitigation

Considering that the transport sector is responsible for an increasingly important share of current environmental problems, we look at Intelligent Transportation Systems (ITS) as a feasible means of helping in solving this issue. In particular, we evaluate the impact in terms of Carbon Dioxide (CO2)emissions of Virtual Traffic Light (VTL), which is a recently proposed infrastructureless traffic control system solely based on Vehicle-to-Vehicle (V2V) communication. Our evaluation uses a real-city scenario in a complex simulation framework, involving microscopic traffic, wireless communication, and emission models. Compared with an approximation of the physical traffic light system deployed in the city, our results show a significant reduction on CO2 emissions when using VTLs, reaching nearly 20% under high-density traffic.

Empirical evaluation of a dynamic and distributed taxi-sharing system

Modern societies rely on efficient transportation systems for sustainable mobility. In this paper, we perform a large-scale and empirical evaluation of a dynamic and distributed taxi-sharing system. The novel system takes advantage of nowadays widespread availability of communication and computation to convey a cost-efficient, door-to-door and flexible system, offering a quality of service similar to traditional taxis. The shared taxi service is assessed in a real-city scenario using a highly realistic simulation platform. Simulation results have shown the systems advantages for both passengers and taxi drivers, and that trade-offs need to be considered. Compared with the current taxi operation model, results show a increase of 48% on the average occupancy per traveled kilometer with a full deployment of the taxi-sharing system.

ITS for Sustainable Mobility: A Survey on Applications and Impact Assessment Tools

Road transportation is one of the main sources of greenhouse gas emissions, which lead to global warming and climate change. Promoting the decarbonization of this sector through more efficient and greener mobility is a challenging task that can be achieved by intelligent transportation systems (ITS) enabled by vehicular communications. In this paper, we briefly present how mobility players and enablers (driver, vehicle, and road network) influence energy consumption and pollutant emissions. Furthermore, this survey paper details how different ITS, ranging from eco-routing to intelligent intersection management, can lead to sustainable mobility by promoting a more efficient vehicle usage and enhanced efficiency on road network utilization. Results shown that ITS has the potential to considerably reduce fuel consumption and pollutant emissions, namely, by smoothing the traffic flow, reducing the number of start-stops, and reducing the total travel distance. In addition, we present and analyze two main methods for evaluating green transportation systems: 1) field operational tests; and 2) simulation-based evaluations. We give special emphasis to simulation-based assessment of Green ITS measures by detailing the necessary models and their interactions. Finally, we propose a number of recommendations and future research directions in the area of Green ITS.

DIVERT for realistic simulation of heterogeneous vehicular networks

Simulation of vehicular networks has been extensively studied in the last few years. In order to have an holistic view of the network functioning, communications and vehicle mobility aspects should be modeled in detail and fully integrated. This article presents a tool for simulating heterogeneous vehicular networks. The existing microscopic traffic simulator, DIVERT, has been extended by adding NS-3 support resulting in a very tightly integrated simulator. The feasibility of the approach has been tested by means of an application example: in-vehicle traffic lights. The provided results demonstrate the superior performance and the scalability of this novel simulator.

Self-automated parking lots for autonomous vehicles based on vehicular ad hoc networking

Parking is a major problem of car transportation, with important implications in traffic congestion and urban landscape. Reducing the space needed to park cars has led to the development of fully automated and mechanical parking systems. These systems are, however, limitedly deployed because of their construction and maintenance costs. Leveraging on semi and fully-autonomous vehicular technology, as well as on the electric propulsion paradigm and in vehicular ad hoc networking, we propose a new parking concept where the mobility of parked vehicles is managed by a parking lot controller to create space for cars entering or exiting the parking lot, in a collaborative manner. We show that the space needed to park such vehicles can be reduced to half the space needed with conventional parking lot designs. We also show that the total travelled distance of vehicles in this new parking lot paradigm can be 30% less than in conventional parking lots. Our proposal can have important consequences in parking costs and in urban landscape.

Measurement-based evaluation of cooperative awareness for V2V and V2I communication

We analyze the efficacy of cooperative awareness enabled by periodic message exchange between vehicles and roadside infrastructure. To measure cooperative awareness, we use three metrics: 1) neighborhood awareness ratio; 2) ratio of neighbors above range; and 3) packet delivery rate. Using the measurement data collected within the scope of the DRIVE-C2X project in four European test sites, we analyze the efficacy of cooperative awareness in urban, suburban, and highway environments. Further, we investigate the ability of periodic message exchange to enable cooperative awareness for both Vehicle to Vehicle (V2V) and Vehicle to Infrastructure (V2I) links and with different effective transmit power levels. Our results show that: i) the efficacy of cooperative awareness varies greatly in different environments; ii) V2V and V2I communication have distinct awareness and interference patterns; and iii) high awareness levels imply high interference; therefore, a balance needs to be found between them, depending on the context that the vehicles are in.

Exploring the Practical Limits of Cooperative Awareness in Vehicular Communications

We perform an extensive study of cooperative awareness in vehicular networks based on periodic message exchange. We start by analyzing measurements collected on four test sites across Europe. To measure cooperative awareness, we use three metrics: 1) neighborhood awareness ratio, 2) ratio of neighbors above range, and 3) packet delivery rate. Using the collected data, we define a simple model for calculating neighborhood awareness given a packet delivery ratio for an environment. Finally, we perform realistic large-scale simulations to explore the achievable performance of cooperative awareness under realistic transmit power and transmit rate constraints. Our measurements and simulation results show the following: 1) Above a certain threshold, there is little benefit in increasing the cooperative message rate to improve awareness; higher transmit power and fewer message transmissions are a better approach, since message delivery is dominated by shadowing; 2) The efficacy of cooperative awareness varies greatly in different environments on both large scale (e.g., 90% awareness is achievable up to 200 m in urban compared to 500 m in highway) and small scale (e.g., vehicles in nearby streets can have significantly different awareness levels); 3) Vehicle-to-vehicle (V2V) and vehicle-to-infrastructure (V2I) communications have distinct awareness patterns; 4) Each location has distinct transmit power that achieves high awareness; 5) Achieving high awareness levels results in increased reception of potentially unwanted messages; therefore, a balance needs to be found between awareness and interference, depending on the specific context. We hope that our results will serve as a starting point for designing more effective periodic message exchange services for cooperative awareness.

Empirical Evaluation of Cooperative Awareness in Vehicular Communications

Vehicular networks will enable a number of active safety and traffic efficiency applications. At the core of many of those applications is cooperative awareness: the ability to detect location, speed, and heading of surrounding vehicles. We empirically analyze three key metrics that shed light on the communication performance available to applications: Packet Delivery Ratio: link quality in terms of the proportion of received messages over distance; Neighborhood Awareness Ratio: the proportion of detected neighbors within a given distance, which serves as an indicator of the effectiveness of cooperative awareness message exchange; and Neighborhood Interference Ratio: the proportion of neighbors above the desired range of interest, which can provide insight into the interference levels of fully deployed systems. By analyzing the measurement data collected within the scope of the DRIVE-C2X project, we conclude that the link layer delivery and neighborhood awareness criterion can be fulfilled for safety applications: in the analyzed datasets, the cooperative awareness ratio is close to 100% up to 100 meters. Depending on the desired region of interest, the interference from far-away vehicles can be considerable, thus requiring effective congestion control to balance between neighborhood awareness and interference.

NAVI: Neighbor-Aware Virtual Infrastructure for Information Collection and Dissemination in Vehicular Networks

Vehicular Networks enable a vast number of innovative applications, which rely on the efficient exchange of information between vehicles. However, efficient and reliable data dissemination is a particularly challenging task in the context of vehicular networks due to the underlying properties of these networks, limited availability of network infrastructure and variable penetration rates for distinct communication technologies. This paper presents a novel system and mechanism for information collection and dissemination based on virtual infrastructure selection in combination with multiple communication technologies. The system has been evaluated using a simulation framework, involving network simulation in conjugation with realistic vehicular mobility traces. Simulation results show the feasibility of the proposed mechanism to achieve maximum message penetration in a geographical area with reduced overhead. The judicious vehicle selection also enables scalable data collection and leads to improved network utilization through the offload of traffic to the short-range communication network.

Automatic link balancing using Fuzzy Logic Control of handover parameter

Self-optimisation will enable future wireless networks to manage themselves in a continuous and independent way. By dynamically adjusting relevant radio parameters during network operation a system that adapts to environmental changes can be created. This paper presents a novel self-optimisation algorithm based on Fuzzy Logic Controlling. Taking into consideration measurements gathered from the network, the Fuzzy Logic Controller balances continuously the individual link gain and the network gain. Results have shown the feasibility of the proposed approach, superior improvements on network performance and a capacity increase of 23%. It is envisioned that self-optimisation will lead to significant reductions in capital and operational expenditures by maximizing the utilisation of the air interface.