Mobile Ad-Hoc Networks

Being infrastructure-less and without central administration control, wireless ad-hoc networking is playing a more and more important role in extending the coverage of traditional wireless infrastructure (cellular networks, wireless LAN, etc). This book includes state-of-the-art techniques and solutions for wireless ad-hoc networks. It focuses on the following topics in ad-hoc networks: quality-of-service and video communication, routing protocol and cross-layer design. A few interesting problems about security and delay-tolerant networks are also discussed. This book is targeted to provide network engineers and researchers with design guidelines for large scale wireless ad hoc networks

Previous hop routing: exploiting opportunism in VANETs

Routing in highly dynamic wireless networks such as Vehicular Ad-hoc Networks (VANETs) is a challenging task due to frequent topology changes. Sustaining a transmission path between peers in such network environment is difficult. In this thesis, Previous Hop Routing (PHR) is poposed; an opportunistic forwarding protocol exploiting previous hop information and distance to destination to make the forwarding decision on a packet-by-packet basis. It is intended for use in highly dynamic network where the life time of a hop-by-hop path between source and destination nodes is short. Exploiting the broadcast nature of wireless communication avoids the need to copy packets, and enables redundant paths to be formed. To save network resources, especially under high network loads, PHR employs probabilistic forwarding. The forwarding probability is calculated based on the perceived network load as measured by the arrival rate at the network interface. We evaluate PHR in an urban VANET environment using NS2 (for network traffic) and SUMO (for vehicular movement) simulators, with scenarios configured to re ect real-world conditions. The simulation scenarios are configured to use two velocity profiles i.e. Low and high velocity. The results show that the PHR networks able to achieve best performance as measured by Packet Delivery Ratio (PDR) and Drop Burst Length (DBL) compared to conventional routing protocols in high velocity scenarios

Communication Networks in CubeSat Constellations: Analysis, Design and Implementation

CubeSat constellations are redefining the way we approach to space missions, from the particular impact on scientific mission possibilities, constellations potential is growing with the increasing accessibility in terms of low development and launch costs and higher performances of the available technologies for CubeSats. In this thesis we focus on communication networks in CubeSat constellations: the project consist of developing a clustering algorithm able to group small satellites in order to create an optimized communication network by considering problems related to mutual access time and communication capabilities we reduce the typical negative effects of clustering algorithms such as ripple effect of re-clustering and optimizing the cluster-head formation number. The network creation is exploited by our proposed hardware system, composed by a phased array with up to 10dB gain, managed by a beamforming algorithm, to increase the total data volume transferable from a CubeSat constellation to the ground station. The total data volume earned vary from 40% to a peak of 99% more, depending on the constellation topology analyzed