F. De Rango

EE-OLSR: Energy Efficient OLSR routing protocol for Mobile ad-hoc Networks

This paper presents two novel mechanisms for the OLSR routing protocol, aiming to improve its energy performance in Mobile ah-hoc Networks. Routing protocols over MANET are an important issue and many proposals have been addressed to efficiently manage topology information, to offer network scalability and to prolong network lifetime. However, few papers consider a proactive protocol (like OLSR) to better manage the energy consumption. OLSR presents the advantage of finding a route between two nodes in the network in a very short time, thanks to its proactive scheme, but it can expend a lot of resources selecting the MultiPoint Relays (MPRs) and exchanging Topology Control information. We propose a modification in the MPR selection mechanism of OLSR protocol, based on the Willingness concept, in order to prolong the network lifetime without losses of performance (in terms of throughput, end-to-end delay or overhead). Additionally, we prove that the exclusion of the energy consumption due to the overhearing can extend the lifetime of the nodes without compromising the OLSR functioning at all. A comparison of an Energy-Efficient OLSR (EE-OLSR) and the classical OLSR protocol is performed, testing some different well-known energy aware metrics such as MTPR, CMMBCR and MDR. We notice how EE-OLSR outperforms classical OLSR, and MDR confirms to be the most performing metric to save battery energy in a dense mobile network with high traffic loads.

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.

Hop-by-Hop Local Flow Control over InterPlaNetary Networks Based on DTN Architecture

Deep space communications are an important research line in scientific community. The possibility of performing the communication between earth and other planets is an excitant challenge. The main issue of the communication between planet, called interplanetary (IPN) communication, is the intermittent visibility due to planet movement and the long propagation delay. In order to solve these problems a delay tolerant network (DTN) has been deployed. DTN is an architecture particularly useful in scenarios where very long transmission delays or intermittent connectivity are present, such as IPN network. The routers in DTN perform a transmission mechanism similar to the model of mail transfer protocols or the store-and-forward and it permits to determine a hop-by-hop based messages exchange. Our main contribute in this paper is the introduction of an asynchronous congestion control mechanism on the network that it is not present in the traditional DTN protocol. This control tries to resolve buffer overflow, link saturation and useless retransmission problems in order to better utilize the overall system.

ML-SOR

Opportunistic networks are a generalization of DTNs in which disconnections are frequent and encounter patterns between mobile devices are unpredictable. In such scenarios, message routing is a fundamental issue. Social-based routing protocols usually exploit the social information extracted from the history of encounters between mobile devices to find an appropriate message relay. Protocols based on encounter history, however, take time to build up a knowledge database from which to take routing decisions. While contact information changes constantly and it takes time to identify strong social ties, other types of ties remain rather stable and could be exploited to augment available partial contact information. In this paper, we start defining a multi-layer social network model combining the social network detected through encounters with other social networks and investigate the relationship between these social network layers in terms of node centrality, community structure, tie strength and link prediction. The purpose of this analysis is to better understand user behavior in a multi-layered complex network combining online and offline social relationships. Then, we propose a novel opportunistic routing approach ML-SOR (Multi-layer Social Network based Routing) which extracts social network information from such a model to perform routing decisions. To select an effective forwarding node, ML-SOR measures the forwarding capability of a node when compared to an encountered node in terms of node centrality, tie strength and link prediction. Trace driven simulations show that a routing metric combining social information extracted from multiple social network layers allows users to achieve good routing performance with low overhead cost.

A multiobjective approach for energy consumption and link stability issues in ad hoc networks

This letter presents a novel analytical framework that jointly accounts the energy consumption and the link stability of mobile nodes. Two indexes for energy and link-lifetime are defined and a multiobjective integer linear programming problem has been defined. The proposed target function separates the energy and the link-stability contributions in order to differently change the weights of two opposite characteristics of mobile ad hoc networks. Some simulation results has been presented and the jointed impact of energy and stability has been evaluated.

A scalable framework for in IP-oriented terrestrial-GEO satellite networks

The exponential growth of the Internet, the heterogeneity of networks, and the need for QoS maintenance have urged researchers to develop ideas for managing network scalability and end-to-end QoS assurance. In this article, an IP IntServ architecture in the satellite access network is combined with a scalable IP DiffServ-like architecture in the terrestrial core network. The proposed architecture aims at guaranteeing fine-grained bandwidth control in the satellite access network and stateless scalability in the core network, by exploiting per-aggregate traffic flow control, typical of the aggregate RSVP protocol, and stateless service assurance, typical of the SCORE approach.

An integrated satellite-HAP-terrestrial system architecture: resources allocation and traffic management issues

This paper explains the potential role of an integrated satellite-HAP (high altitude platform)-terrestrial system. A simple and suitable architecture is presented. The proposed architecture consists of three layers: the terrestrial layer, HAP layer and GEO layer. The terrestrial layers terminals, within the same HAP coverage area, have to use a HAP transponder and HAP master control station (HMCS) to send and receive data amongst themselves. Moreover the HAP gateway stations (HGTW) guarantees communications among users belonging to different HAP coverage areas using the GEO satellite links. Since high quality multimedia application support is a key objective for upcoming communication systems, this paper investigates the issues related to this topic. In order to guarantee an adequate quality of service to these kinds of service requires an efficient resources allocation and traffic management algorithm to be implemented inside the HMCS and HGTW stations.

A modified location-aided routing protocol for the reduction of control overhead in ad-hoc wireless networks

This paper contributes to the issue of location-aided routing in ad-hoc wireless networks. It focuses on the location-aided routing (LAR) protocol and its way of building the forwarding zone. A modified-LAR algorithm is proposed and three variants of it are examined. All of them are based on the idea of enlarging the request zone, in case of failure of the route discovery phase, instead of restoring to flooding. Simulation results show that the proposed algorithm leads to an improvement in the control overhead.

Multicast QoS Core-Based Tree Routing Protocol and Genetic Algorithm Over an HAP-Satellite Architecture

In this paper, a quality-of-service (QoS) multicast routing protocol, i.e., the core-based tree based on heuristic genetic algorithms (GAs), has been implemented and applied over a high-altitude platform (HAP)-satellite platform. The proposed multicast routing algorithm is called the constrained cost-bandwidth-delay GA (CCBD-GA). To achieve a better optimization of the multicast tree cost, a new algorithm called HULK-GA, which is based on the GA and on a proposed broadcast metric, has been developed. Finally, an algorithm called hybrid cost-bandwidth-delay GA has been proposed, taking into account both CCDB-GA and HULK-GA characteristics to obtain an overall algorithm that can consider QoS routing constraints and minimize the overall cost per link of the considered multicast tree. The joint bandwidth-delay metrics can be very useful in hybrid platforms such as the platform considered, because it is possible to take advantage of the single characteristics of the satellite and HAP segments. The HAP segment offers low propagation delay, permitting QoS constraints based on maximum end-to-end delay to be met. The satellite segment, instead, offers a larger footprint but higher propagation delay. The joint bandwidth-delay metric permits the traffic load to be balanced, respecting both QoS constraints.

Markovian approach to model Underwater Acoustic channel: Techniques comparison

In the last years, Underwater Acoustic (UWA) sensor networks have exponentially grown in many scientific, industrial and research areas. Wireless underwater communications are required in many application fields, such as real time remote control of seabed and oil rigs, monitoring of underwater environments, collecting of scientific data recorded by stations on the seabed, conversation between divers, mapping of the seabed (in order either to detect objects or to discover new resources), prevention of disasters, and many others. In order to allow these applications, the aspect of physical phenomena affecting acoustic communications cannot be neglected. The shallow-water acoustic channel is different from the radio channels in many aspects. The available bandwidth of the UWA channel is limited and it depends on both range and frequency. Within this limited bandwidth, the acoustic signals are affected by time-varying multipath, which may create severe inter symbol interference (ISI) and large Doppler shifts and spreads. These characteristics restrict the range and bandwidth for the reliable communications. Many works have already treated underwater acoustic channel modeling problem, however, at the best of our knowledge, they work only at the bit level and they are not suitable for those contexts in which a high level model is required. For this purpose, our paper discusses about a high level channel model based on Markov Chain approach for the underwater environment. Finite State Markov Model is developed for Packet Error Rate (PER) evaluation in an underwater channel, using the concept of error trace analysis. Some high level models well known in literature are compared to obtain statistical evaluations in order to find the model best fitting the underwater channel dynamics. Simulation and analysis are made in Matlab.