Alessandro Bazzi

SHINE: Simulation platform for Heterogeneous Interworking Networks

The interworking of different radio access technologies aimed at providing always the best service to mobile users is the future of wireless communications. Many researchers are already investigating appropriate architectural solutions, coexistence problems, common radio resource management algorithms and other topics concerning this issue. In this paper we illustrate a simulation platform developed in our research group to investigate the performance and to test new management strategies of such interworking networks. Our purpose, however, is not to show the details of our tool, that would be useless for the reader; we aim, on the contrary, at providing those researchers who are facing the realization of a similar simulation tool with the main general criteria to develop a flexible and efficient simulation platform.

IEEE 802.11p for cellular offloading in vehicular sensor networks

The use of vehicles as sensors is a new paradigm to enable an efficient environment monitoring and an improved traffic management. In most cases, the sensed information must be collected at a remote control center and one of the most challenging aspects is the uplink acquisition of data from vehicles, which is presently performed through cellular networks. With the objective to offload cellular networks, in this paper we propose and discuss the adoption of the WAVE/IEEE 802.11p protocols, which represent the state of the art for short range vehicle-to-vehicle and vehicle-to-roadside communications. More specifically, we discuss the system design and assess the cellular resource saving that can be obtained in urban scenarios through the deployment of WAVE/IEEE 802.11p devices on the vehicles and roadside units, evaluating the impact of the percentage of equipped vehicles, of the number of deployed road side units, and of the adopted routing protocol. Results, obtained through an integrated simulation platform taking both realistic vehicular environments and wireless network communication aspects into account, show that the deployment of few road side units and the use of low complexity routing protocols leads to a significant reduction of cellular resource occupation, even approaching 100% with a high density of equipped vehicles.

Performance Analysis of V2V Beaconing Using LTE in Direct Mode With Full Duplex Radios

Vehicles will soon be equipped with wireless communication systems enabling a variety of new services. At the basis of each service is the transmission of beacon messages that advertise the vehicles presence. In this letter, we investigate long term evolution (LTE) as the enabling technology for vehicle to vehicle (V2V) beaconing by exploiting: 1) the direct device to device (D2D) communication provided by Release 12 of LTE; and 2) the full duplex (FD) radio, which allows a wireless device to transmit and receive at the same time. Furthermore, we introduce a novel analytical framework to evaluate the resource occupation of the beaconing service in LTE and compare the results with those obtained using LTE for vehicle to infrastructure (V2I) communications.

On the Frequent Acquisition of Small Data Through RACH in UMTS for ITS Applications

Wireless communications are currently considered the most promising solutions to provide real-time traffic information, suggest alternative routes, and help to reduce congestion. These new services are all based on the real-time acquisition of traffic information directly from vehicles, which act as sensors that travel on the roads. With the idea of having new widespread and real-time infomobility services in the short-medium term, neither installations onboard nor new roadside infrastructures that have been set up can be taken into account. Hence, in this paper, we aim at verifying the feasibility of the real-time acquisition of traffic information from vehicles in dense areas through the universal mobile telecommunication system (UMTS). In particular, we first analytically evaluate the capacity and the coverage of a UMTS cell when multiple users frequently transmit their traffic measurements to a remote control center through a shared (common) channel. Then, we extend our results to a realistic urban scenario by investigating, through simulations, the feasibility of the service and its impact on the quality of service (QoS) perceived by other users (e.g., voice).

Multiradio Resource Management: Parallel Transmission for Higher Throughput?

Mobile communication systems beyond the third generation will see the interconnection of heterogeneous radio access networks (UMTS, WiMax, wireless local area networks, etc.) in order to always provide the best quality of service (QoS) to users with multimode terminals. This scenario poses a number of critical issues, which have to be faced in order to get the best from the integrated access network. In this paper, we will investigate the issue of parallel transmission over multiple radio access technologies (RATs), focusing the attention on the QoS perceived by final users. We will show that the achievement of a real benefit from parallel transmission over multiple RATs is conditioned to the fulfilment of some requirements related to the kind of RATs, the multiradio resource management (MRRM) strategy, and the transport-level protocol behaviour. All these aspects will be carefully considered in our investigation, which will be carried out partly adopting an analytical approach and partly by means of simulations. In this paper, in particular, we will propose a simple but effective MRRM algorithm, whose performance will be investigated in IEEE802.11a-UMTS and IEEE802.11a-IEEE802.16e heterogeneous networks (adopted as case studies).

Measurement based call admission control strategies in infrastructured IEEE 802.11 WLANs

In this paper two simple but efficient call admission control (CAC) strategies for IEEE 802.11 WLANs are investigated, which are both based on a simple centralized evaluation of the current network congestion level. A realistic scenario has been considered for the evaluation of the proper choice of the CAC parameters as well as for the assessment of the performance level they provide for different traffic mixes. Simulation results show that the investigated CAC strategies could significantly improve users satisfaction and network fairness

V2V and V2R for cellular resources saving in vehicular applications

Considering vehicles as sensors for traffic and pollution information is a new paradigm to monitor the environment and to open the way to an efficient smart navigation. In this work we focus on the uplink acquisition of traffic information from vehicles toward a remote control center. With the increase in the number of vehicles equipped with on board units (OBUs) enabling cellular transmissions, this service is leading to higher loads for the cellular network itself and, consequently, to higher costs. In this paper we discuss the opportunity to take advantage of vehicle-to-vehicle (V2V) and vehicle-to-roadside communications in addition to vehicle-to-infrastructure cellular transmissions. The objective is twofold: to investigate the potential reduction of data transmitted over the cellular networks and to verify the potential transmission delay reduction, by sharing and aggregating information through V2V communications. Results are obtained through an integrated simulation platform jointly taking into account both realistic vehicular environments and wireless network communication aspects.

Architecture of a simulation platform for the smart navigation service investigation

Efficient mobility management is an issue of vast economic importance for its consequences on urban and suburban mobility. In this context, telecommunications are gaining a key role, allowing to increase people safety, traffic efficiency, and travel comfort. To investigate the telecommunication systems behavior in new infomobility scenarios, advanced simulations tools are needed jointly taking into account realistic road traffic mobility and telecommunication networks protocols in all their aspects. In this paper we discuss the architecture of a complex and complete simulation platform we are developing on the behalf of the Italian project PEGASUS: the choice of traffic simulators, the network simulation and their interface will be presented and described.

Visible light communications as a complementary technology for the internet of vehicles

The paradigm of vehicular visible light network (VVLN) is introduced, highlighting its peculiarities, and discussing the present state of the art focusing on standardization and real experimentations.The limits of visible light communication (VLC) for pure VVLNs are discussed and its potentiality when used as complementary wireless technology is highlighted.An algorithm (called congestion-adaptive VLC-DSRC) is proposed to jointly manage VLC and dedicated short range communications (DSRC) in heterogeneous vehicular networks.Example results of VLC added to DSRC are shown focusing on the example application of crowd sensing vehicular networks (CSVNs) through simulations in realistic urban scenarios. The paradigm of connected vehicles is moving from research to implementation, thus enabling new applications that start from safety improvement and widen to the so called Internet of vehicles (IoV). The candidate enabling technologies in the radio frequency (RF) bands are cellular and short range technologies. However, the limited bandwidth shared among several applications pushes researchers to look at new technological solutions. To this end, an option is provided by visible light communication (VLC). Based on the use of the light emission diodes (LEDs) that are already available on the majority of vehicles, VLC would enable short range communication in large, unlicensed, and uncongested bands with limited costs. In this work we first highlight the main properties of VLC in vehicular networks and revise the state of the art focusing on both the IEEEź802.15.7 standard and on the performance demonstrated by field tests that have been conducted worldwide. Then, we discuss the limitations of using VLC for pure vehicular visible light networks (VVLNs) and its application as complementary technology, to be implemented with other wireless standards in future heterogeneous vehicular networks. Finally, we show numerical results provided by simulations in a realistic urban scenario focusing, as a case study, on the crowd sensing vehicular network application with VLC added to short range IEEEź802.11p technology. Results demonstrate that the addition of VLC improves the performance of a conventional vehicular network based only on IEEEź802.11p.

On the Impact of Routing Strategies on the Interference of Ad Hoc Wireless Networks

Routing strategies deeply affect the performance of wireless ad hoc networks, in terms of coverage, interference, and delay. In this work, we investigate the impact of different routing strategies on the overall amount of interference generated in a distributed ad hoc network with power control. To this end, we derive an analytical model for the evaluation of the performance in terms of mean value and variance of the interference when signal level power control is adopted and different routing strategies, based on long-hop and short-hop relay selections schemes, are considered. This model allows us to quantify the performance of the overall network in terms of interference, average number of hops and path efficiency. Numerical results have been also verified by simulations.