Towards Scalable Beaconing in VANETs

Beaconing is envisioned to build a cooperative awareness in future intelligent vehicles, from which many ITS applications can draw their inputs. The problem of scalability has received ample attention over the past years and is primarily approached using power control methods. We reason power control alone will not be sufficient if we are to meet application requirements; the rate at which beacons are generated must also be controlled. Ultimately, adaptive approaches based on actual channel and traffic state can tune MAC and beaconing properties to optimal values in the dynamic VANET environment

Routing in a many-to-one communication scenario in a realistic VDTN

In this paper, we evaluate and compare the performance of different routing protocols in a many-to-one communication within a Vehicular Delay Tolerant Network (VDTN). Seven groups with three stationary sensor nodes sense the temperature, humidity and wind speed and send these data to a stationary destination node that collect them for statistical and data analysis purposes. Vehicles moving in Tirana city roads in Albania during the opportunistic contacts will exchange the sensed data to destination node. The simulations are conducted with the Opportunistic Network Environment (ONE) simulator. For the simulations we considered two different scenarios where the distance of the source nodes from the destination is short and long. For both scenarios the effect of node density, ttl and node movement model is evaluated. The performance is analyzed using delivery probability, overhead ratio, average latency, average number of hops and average buffer time metrics. The simulation results show that the increase of node density increases the delivery probability for all protocols and both scenarios, and better results are achieved when shortest-path map-based movement model is used. The increase of ttl slightly affects the performance of all protocols. By increasing the distance between source nodes and destination node, delivery probability is decreased almost 10% for all protocols, the overhead for sprayandwait protocol does not change, but for other protocols is slightly increased and the average number of hops and average latency is increased.Peer ReviewedPostprint (author's final draft

An SDN-based Overlay Networking Solution for Transparent Multi-homed Vehicular Communications

This dissertation consists in the design and development of an Overlay Network for vehicular applications using the SDN paradigm, capable of supporting seamless handover and load balancing between multiple Vehicle-to-Infrastructure (V2I) networks, and also seamless handover of users' terminals between different vehicle zones, such as train carriages. The main contributions of this work are threefold: 1) the overlay SDN-based network architecture designed for vehicular applications such as trains, contemplating the support for multiple V2I operators and multiple gateways per vehicle (e.g., one per carriage); 2) the SDN orchestration component that implements the handover (performed by a User Terminal) from one carriage to another, without Internet connection interruption; and 3) the SDN orchestration component that implements the load-balancing of traffic over multiple V2I links that connect each carriage to the Internet, optimizing the utilization of available network resources and resulting QoS. All the features related to these contributions were implemented in a centralized SDN controller, which has a holistic view of the overlay network, which orchestrates the network hardware on-board of the vehicles. A Proof-of-Concept of the overlay network and the developed components was implemented using Virtual Machines emulating: the network elements of two carriages; the user terminals; a centralized orchestrator; an Internet gateway; and multiple V2I connections representing different operators. Different functional and performance tests were executed, targeting each component, which allowed to successfully validate each contribution