Oanh Tran Thi Kim

A shared parking model in vehicular network using fog and cloud environment

At the present, the traffic is really in a mess when the number of vehicles is increasing rapidly. As a consequence, finding a parking space is remarkably difficult and expensive. Therefore, solving this problem has attracted the attention of both scientists and companies. Our study also focuses on solving parking problem to relieve the traffic congestion, reduce air pollution and enhance driving effectively. However, unlike other studies, we consider parking problem in the view of IoT. From this perspective, Fog Computing and Roadside Cloud are utilized to find a vacant spot. By utilizing this infrastructures, any parking space at many places can be shared. Then, we analyze and apply the matching theory to solve the parking problem. Accordingly, our proposal not only helps drivers finding an ideal available space but also brings the owners of these places profit. Simulation results demonstrate that the proposed approach is a reliable solution for the finding parking slot.

Application of the lowest-ID algorithm in cluster-based TDMA system for VANETs

To gather data of a larger area and improve the capability in the system, vehicles in Vehicular Ad-hoc NETworks (VANETs) are organized into clusters. Moreover, the effectiveness of application in VANET depends on performance of Medium Access Control (MAC) protocol. In addition, cluster-based MAC protocols can avoid or limit channel contention, provide fairness to channel access, increase radio network capacity management by reusing the spatial network and effectively controlling the topology of the network. This paper proposes a cluster-based TDMA system using the lowest-ID algorithm for Vehicular Ad hoc NETworks (VANETs). Using the lowest-ID algorithm, the analytical and simulated results show that not only the average number of time slots for electing a vehicle head but also total number of time slots before data can be successfully transmitted is less than the existing cluster-based TDMA system and IEEE 802.11p.

Improving time slot acquisition through RSU's coordination for TDMA-based MAC protocol in VANETs

Vehicles and Road Side Units (RSUs) are essential units to create a dynamic network, called Vehicular Ad hoc NETwork (VANETs). An RSU plays a role of collecting and analyzing traffic data given from vehicles. RSUs and vehicles have to assign time slots to broadcast service applications on the control channel in VANETs. One of MAC protocol versions named VeMAC is proposed. VeMAC protocol can decrease the rate of transmission collisions and increase the throughput on the control channel. However, VeMAC protocol did not consider to special properties of an RSU in VANETs. In this paper, we propose an improvement of time slot acquisition through RSUs coordination for TDMA-based MAC protocol in VANET, called RCMAC protocol. In our protocol, RSUs exploit time slots assignment and disseminate control information. Hence, RCMAC protocol reduces the rate transmission collisions due to all nodes on the control channel receive a control information from an RSU. Simulation results show that RCMAC protocol outperforms both VeMAC and ADHOC-MAC protocols in term of average of number of frames that all nodes successfully acquire a time slot and average number of access collisions until all nodes successfully acquire a time slot.

Finding realistic shortest path in road networks with lane changing and turn restriction

Most existing work on path computation has been focused on the shortest-path problem, which is to find the optimal path between an origin and destination pair. To get an optimal route, they usually consider travel time moving forward on the road and distance from a source to a target as crucial factors to value and select a path. However, it is not sufficient for real life traffic. Firstly, when we drive on the road, the road driving time includes the duration of moving forward on the road section, going through an intersection and performing lane changes. Secondly, it is not possible, in practice, to go on any road section. Some road sections have restricted rules. Turn restrictions are commonly restricted in a real network to reduce disruption to traffic. Therefore, in our work, we direct to find not only the shortest path but also realistic or feasible path. Both lane changes and turn restrictions are considered in our work. Simulation results show that two these additional constraints are necessarily considered to achieve a realistic shortest path. In addition, our proposal is not only giving a practical path but also a satisfied path for each individual car.

An efficient and reliable Green Light Optimal Speed Advisory system for autonomous cars

An autonomous car is a self-driving car that is to keep the human being out of the car and to relieve them from the task of driving. An autonomous car can make more convenient, safer, and less energy intensive. In addition, Green Light Optimal Speed Advisory (GLOSA) systems reduce the travel time and CO2 emission. In this paper, we propose a novel GLOSA, called R-GLOSA system to support to autonomous cars. We assume that an autonomous car can access to all traffic light schedules that it will encounter on its route. The route is divided into each segment according to traffic lights. In each segment, an autonomous car can communicate to Road Side Units (RSUs) distributed among the road. An autonomous car collects the road information transmitted by an RSU and then, it optimizes speed in order to arrive at the intersection when the light is green. The R-GLOSA system provides an autonomous car with speed advisory for each RSUs coverage. The simulation results show that an autonomous car using R-GLOSA system outperforms in terms of travel time and waiting time compared to using single-segment and multi-segment GLOSA system.

Performance Analysis of a Hybrid Efficient and Reliable MAC Scheme for Vehicular Ad Hoc Networks in Safety Applications

Safety applications are the highest priority services in the Vehicular Ad Hoc NETworks (VANETs). To support the highest priority service, the Medium Access Control (MAC) protocol is designed to provide efficient broadcast. Compared to IEEE 1609.4, a new multi-channel MAC for VANET (HER-MAC) is proposed which is more reliable in safety applications. In this paper, we propose an analytical model to evaluate the performance of HER-MAC protocol under non-saturation condition through the packet delivery ratio. We also describe two MAC access schemes for HER-MAC protocol: safety application packets using TDMA access scheme and safety application packets using Distributed Coordination Function (DCF). Simulation results show that safety application packets using TDMA access scheme has higher packet delivery ratio and more reliability than safety application packets using distributed coordination function.