Peppino Fazio

Link-Stability and Energy Aware Routing Protocol in Distributed Wireless Networks

Energy awareness for computation and protocol management is becoming a crucial factor in the design of protocols and algorithms. On the other hand, in order to support node mobility, scalable routing strategies have been designed and these protocols try to consider the path duration in order to respect some QoS constraints and to reduce the route discovery procedures. Often energy saving and path duration and stability can be two contrasting efforts and trying to satisfy both of them can be very difficult. In this paper, a novel routing strategy is proposed. This proposed approach tries to account for link stability and for minimum drain rate energy consumption. In order to verify the correctness of the proposed solution a biobjective optimization formulation has been designed and a novel routing protocol called Link-stAbility and Energy aware Routing protocols (LAER) is proposed. This novel routing scheme has been compared with other three protocols: PERRA, GPSR, and E-GPSR. The protocol performance has been evaluated in terms of Data Packet Delivery Ratio, Normalized Control Overhead, Link duration, Nodes lifetime, and Average energy consumption.

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.

Enhancements of Epidemic Routing in Delay Tolerant Networks from an energy perspective

In last years, the challenge of providing end-to-end service where end-to-end forwarding paths do not exist is faced by the new emerging approach of Delay Tolerant Networks (DTNs), that support interoperability of “regional networks” by accommodating long delay between and within regional networks, such as space communications, networking in sparsely populated areas, vehicular ad-hoc networks and underwater sensor networking. The common issue of these environments consists in the absence of guarantees about the existence of continuous end-to-end paths between source and destination nodes. In this paper we consider epidemic schemes to solve this problem, proposing an extended approach aimed at the routing optimization in terms of energy consumption and message delivery probability. The performance of our idea have been evaluated through a deep campaign of simulations, verifying that the proposed extended epidemic approach leads the system to an overall enhancement.

A New Distributed Application and Network Layer Protocol for VoIP in Mobile Ad Hoc Networks

In this work a new protocol for Voice over IP (VoIP) transmissions in wireless ad-hoc networks is proposed. Distributed architecture is necessary when dealing with dynamic environments, such as ports or battlefields, where creating infrastructures becomes expensive or impossible. Mobile ad-hoc networks (MANETs) are based on a peer-to-peer approach and each node participates in the organization of the whole network. VoIP over MANETs is a challenging issue due to the intrinsic distributed nature of the existing peer-to-peer paradigm. This paper proposes a new protocol, capable of ensuring a quality of service (QoS) level for VoIP calls over a MANET and to manage a large number of calls in the system. Novel metric and utility functions are proposed to perform the best path selection from source to destination nodes, respecting the QoS parameters for VoIP quality. In particular, an objective metric such as R-factor is considered, and a flexibility index is defined in order to maximize the number of acceptable VoIP calls. Performance evaluation shows that the proposed approach led to better network management in terms of admitted calls and respected QoS constraints.

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.

Two-level Trajectory-Based Routing Protocol for Vehicular Ad Hoc Networks in Freeway and Manhattan Environments

This paper focuses on the routing protocol issue in two important environments for Vehicular Ad Hoc Networks (VANET): Manhattan and the Freeway. A novel protocol called Two-level Trajectory Based Routing (TTBR) protocol is proposed. Deterministic vehicles movement permits advantage to be taken of the map info to build a specific local trajectory to reach the destination node. However, in order to offer network scalability also a high level cell-based trajectory is applied to have a coarse knowledge of the cell where the destination node is moving. Our proposal needs Peer Servers and Grid subdivision of the space. Simulation results were assessed to show the improvements and scalability offered by TTBR in comparison with other Ad Hoc networks protocols such as AODV and GPSR. Performance Evaluation was evaluated in terms of Normalized Control Overhead and Data Packet Delivery Ratio. TTBR is more performing than AODV for a high speed and high density scenario for both the Manhattan and Freeway scenarios.

Call Admission Control for Aggregate MPEG-2 Traffic Over Multimedia Geo-Satellite Networks

This paper presents a novel call admission control (CAC) algorithm based on the statistical multiplexing of VBR traffic. The proposed algorithm is called statistical multiplexing based on discrete bandwidth levels of GOP rate (SMDB) because the solution is based on the discretization of the GOP rate in a set of bandwidth levels and on the time characteristics of discrete bandwidth levels of MPEG sources. SMDB is compared with another statistical CAC based on the normal/lognormal distribution of the GOP rate (SMND). SMDB outperforms SMND in many situations such as high variance around the average video traffic GOP rate of sources and heavy traffic load. The new CAC has been tested in the new generation satellite platform called digital video broadcasting via return channel satellite (DVB-RCS). A high system utilization and multiplexing gain with respect to QoS constraints is obtained.

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 New Routing Protocol for Interference and Path-Length Minimization in Vehicular Networks

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 very scalable and adequate for highly-variable network topologies. Vehicular Ad-hoc NETworks (VANETs) are able to provide wireless networking capability in situations where no fixed infrastructure exists and the communication among nodes can be either direct or made via relaying nodes, as in the classical ad-hoc networks. In this paper, the attention is focused mainly on the network layer of VANETs, proposing a novel approach to reduce the interference level during mobile transmission, also considering the minimization of path lengths. We propose an interference aware routing scheme for multi-radio vehicular networks and a new metric is also proposed, based both on the maximization of the average Signal to Interference level and on the minimization of the path length of the connection between source and destination. Our solution has been integrated with the AODV routing protocol to design a new MIMO Distance Vector Protocol. NS-2 has been used for implementing and testing the proposed idea, and significant performance improvements have been obtained.

Cell Stay Time Analysis under Random Way Point Mobility Model in WLAN

This letter presents an analytical framework of the cell stay time (CST) in wireless LAN environment. CST is an important parameter that can be used to estimate how long a mobile user will stay in a particular cell and how many cells he will probably visit during his call holding time. CST can be also used to make predictive advanced reservations. A probability density function (p.d.f.) of the CST is obtained and an analytical expression of its main parameters such as the average and standard deviation values is outlined as a function of the average mobile user speed and cell radius