Cesare Sottile

Routing Optimization in Vehicular Networks: A New Approach Based on Multiobjective Metrics and Minimum Spanning Tree

Recently, distributed mobile wireless computing is becoming a very important communications paradigm, due to its flexibility to adapt to different mobile applications. As many other distributed networks, routing operations assume a crucial importance in system optimization, especially when considering dense urban areas, where interference effects cannot be neglected. In this paper a new routing protocol for VANETs and a new scheme of multichannel management are proposed. In particular, an interference-aware routing scheme, for multiradio vehicular networks, wherein each node is equipped with a multichannel radio interface is investigated. NS-2 has been used to validate the proposed Multiobjective routing protocol (MO-RP) protocol in terms of packet delivery ratio, throughput, end-to-end delay, and overhead.

An On Demand Interference Aware Routing Protocol for VANETS

Vehicular communication systems represent one of the most desirable technologies when the safety, efficiency and comfort of everyday road travel need to be improved. The main advantage is the absence of an infrastructure, typical of centralized networks, that makes them adequate for highly-variable network topologies. On the other hand, communication protocols become very complex and, sometimes, signaling overhead may waste bandwidth availability. Vehicular Ad-hoc NETworks (VANETs) are able to provide a wireless networking capability in situations where no fixed infrastructure exists: communication performance and Quality of Service (QoS) strongly depend on how the routing takes place in the network, on how protocol overhead affects the available bandwidth and on how different channels are selected in order to minimize interference levels. Attention is focused on the routing level of VANET and we propose an interference aware routing scheme for multi-radio vehicular networks, wherein each node is equipped with a multi-channel radio interface. In order to relieve the effects of the co-channel interference perceived by mobile nodes, transmission channels are switched on the basis of a periodical Signal-to-Interference Ratio (SIR) evaluation. A new metric is also proposed, based on the maximization of the average SIR level of the connection between source and destination. Our solution has been integrated with the Ad-Hoc On-Demand Distance Vector (AODV) routing protocol to design an enhanced Signal-to-Interference-Ratio-AODV (SIR-AODV). NS-2 has been used for implementing and testing the proposed idea, and significant performance enhancements were obtained, in terms of throughput, packet delivery and, obviously, interference.

A New Channel Assignment Scheme for Interference-Aware Routing in Vehicular Networks

Mobile computing and vehicular communications are becoming a very important paradigm for wireless communications, mainly because of their ability to adapt to different mobile applications. In this paper, we propose a new scheme for reducing the interference level during mobile transmissions in the VehiculAr inter-NETworking (VANET) environment, taking the advantage of the multi-channel nature of IEEE802.11p standard. In order to relieve the effects of the co-channel interference perceived by mobile nodes, transmission channels are switched on a basis of a periodical Signal-to-Interference Ratio (SIR) evaluation. The attention is focused on the routing level of VANET and we propose an interference aware routing scheme for multi-radio vehicular networks, wherein each node is equipped with a multi-channel radio interface. A new metric is also proposed, based on the maximization of the average SIR level of the connection between source and destination. Our solution has been integrated with the AODV routing protocol to design an enhanced Signal-to-Interference-Ratio-AODV (SIR-AODV). NS-2 has been used for implementing and testing the proposed idea, and significant performance enhancements were obtained, in terms of throughput, packet delivery and, obviously, interference.

A distance vector routing protocol for VANET environment with Dynamic Frequency assignment

Vehicular mobile communications are attracting much attention in wireless communications field. In this paper a new routing protocol for the reduction of interference level during mobile transmissions in VANET environment is proposed, considering the availability of different channels in the DSRC spectrum. The attention is mainly focused on the routing level of VANET and we propose an interference aware routing scheme for multi-radio vehicular networks based on a new metric, for the maximization of the average SIR level of the connection between source and destination. The proposed idea has been integrated with the AODV routing protocol to design an enhanced Dynamic-Frequency-Interference-Aware-AODV (DFIA-AODV). The proposed idea has been tested and significant performance enhancements were obtained.

A Predictive Cross-Layered Interference Management in a Multichannel MAC with Reactive Routing in VANET

Vehicular ad hoc networks (VANETs) represent a particular mobile technology that permits communication between vehicles, offering security and comfort. Nowadays, distributed mobile wireless computing is becoming a very important communication paradigm, due to its flexibility to adapt to different mobile applications. In this work, an interference aware metric is proposed in order to reduce the level of interference between each pair of nodes at the MAC and routing layer. In particular, this metric with a prediction algorithm is proposed to work in a cross-layered MAC and an on-demand routing scheme in multi-radio vehicular networks, wherein each node is equipped with two multi-channel radio interfaces. The proposed metric is based on the maximization of the average signal-to-interference ratio (SIR) level of the connection between source and destination. In order to relieve the effects of the cochannel interference perceived by mobile nodes, transmission channels are switched on a basis of a periodical SIR evaluation. Our solution has been integrated with an on-demand routing scheme but it can be applied to other routing strategies. Three on-demand interference aware routing schemes integrating IEEE 802.11p Multi-channel MAC have been tested to assess the benefits of the novel metric applied to a vehicular context. NS-3 has been used for implementing and testing the proposed idea, and significant performance improvements were obtained: in particular, the proposed policy has resulted in an enhancement of network performance in terms of throughput and packet delivery ratio.

PAMTree: partitioned multicast tree protocol for efficient data dissemination in a VANET environment

The way to distribute a wide range of services on Vehicular Ad Hoc Networks is going to be a very interesting research topic, due to the willingness of the investors and the standardization institutions. In fact, the higher the number of available services is, the higher the impact and the market penetration of the considered technology will be. Also governance institutions appreciate the benefits of VANETs, having the possibility to increase safety level along the roads, saving lots of human lives, and reducing the severity of the collisions among vehicles. In this work we propose a multicast protocol, called partitioned multicast tree (PAMTree), which is suitable for spreading several kinds of services, increasing the reliability of the network, and giving the possibility to a higher number of users of having access to those services. The proposed protocol aims to exploit the characteristics of the VANET architecture in order to distribute services along the nodes of the network; owing to the high nodes mobility, several issues have to be faced to supply an optimal distribution, having a look at the quality of service (QoS) satisfaction.

A reactive routing protocol for VANETs based on composite metric concept

In the last years, the interest on vehicular networking has incredibly increased in the scientific and industrial community, due to the enormous potentialities that this emerging technology offers. In this context, routing protocols become fundamental for enhancing QoS, related to the different services offered to final users. The implementation of new routing protocols becomes challenging in VANETs so, at this aim, we propose a new reactive routing scheme in which the available channels are exploited for the optimization of a new metric, which takes into account different characteristics. Network Simulator 2 (NS2) has been employed to validate the Reactive Routing Protocol for VANETs (RRPV), showing how it performs better than other protocols in terms of different performance variables.

Mobility prediction in wireless cellular networks for the optimization of Call Admission Control schemes

In last years there have been a growing interest for cellular networking, due to the availability of different mobile applications and the explosion of mobile devices utilization. If managed in an adequate way, cellular systems with mobile hosts can offer excellent performance and satisfactory QoS levels. In order to avoid service degradations, it is very important to decide whether a new connection can be accepted into the system, with the main aim of maximizing bandwidth utilization while avoiding quality degradations, with more emphasis for non-tolerant applications. Our proposed idea shows how a statistical approach can enhance system performance, without considering a particular prediction scheme (based on Markov theory, neural networks, data mining, Holt-Winters or similars): the proposal has been integrated with a threshold-based statistical bandwidth multiplexing scheme in order to propose the In-Advance Multiplexing Call Admission Control (IAM-CAC) scheme for cellular networks. Simulation campaigns have shown that the performance of the proposed idea in terms of admitted flows, and bandwidth utilization are really acceptable.

Safety Enhancement and Carbon Dioxide (CO2) reduction in VANETs

Nowadays one of the hottest theme is the application of the newest technologies in road safety. Several proposals have been made and both US and European standardization institutes are working on them. In this work we present a novel cooperative architecture that allows vehicles to communicate between them exploiting Vehicle to Vehicle (V2V) and Vehicle to Infrastructure (V2I) connections. In order to spread information we propose a network protocol called Safety Enhancement for WAVE based protocol (SeAWave) that takes advantages of IEEE802.11p standard and tries to enhance it adding useful messages increasing vehicles’ passive and active safety systems. In this work we propose a novel protocol in order to gather important data about environment such as collisions, block, emission levels and so on. These data are collected by the City Traffic Manager (CTM) exploiting dedicated messages sent by the vehicle and infrastructure devices. They are used by the system to activate alerting mechanism using protocol messages in a controlled broadcasting. In addiction, CTM knowing the whole status of the road network can avoid traffic blocks making some high level decisions. Also a smart traffic management system is addressed in the proposed framework in order to reduce vehicles’ CO2 emissions in the urban area increasing, where possible, air quality. In order to validate proposed framework and protocol we use a well know Discrete-Event Simulator (DES) simulator with a dynamic mobility generator that allow us to change and control reference areas, area size, and loads rate.

Pattern prediction in infrastructured wireless networks: Directional vs temporal statistical approach

The main desire of end-users of a telecommunication system is to take advantage of satisfactory services, in terms of Quality of Service (QoS), especially when they pay for a required needing. Unfortunately, when hosts are moving into an infrastructured network, it is very important to mitigate hand-over effects, which may cause heavy flow degradations or disruptions. In this paper, we are interested in investigating how the continuity of services can be guaranteed in QoS networks, by the analysis of users mobility from two different points of view: the first based on a directional modeling of users mobility, the second based on a time-based modeling of Cell Permanence Time (CPT). After a hand-over event, bandwidth availability should always be granted for those users who need to take benefits from QoS networks: the only way to face this issue is represented by the employment of a mobility prediction scheme, in order to know “how and when” users move among infrastructured coverage areas. Based on a large number of experiments, the proposed schemes are then compared, in order to observe what are the benefits of the considered policies and when it is preferred to use each of them.