Overlay Protection Against Link Failures Using Network Coding

This paper introduces a network coding-based protection scheme against single and multiple link failures. The proposed strategy ensures that in a connection, each node receives two copies of the same data unit: one copy on the working circuit, and a second copy that can be extracted from linear combinations of data units transmitted on a shared protection path. This guarantees instantaneous recovery of data units upon the failure of a working circuit. The strategy can be implemented at an overlay layer, which makes its deployment simple and scalable. While the proposed strategy is similar in spirit to the work of Kamal '07 & '10, there are significant differences. In particular, it provides protection against multiple link failures. The new scheme is simpler, less expensive, and does not require the synchronization required by the original scheme. The sharing of the protection circuit by a number of connections is the key to the reduction of the cost of protection. The paper also conducts a comparison of the cost of the proposed scheme to the 1+1 and shared backup path protection (SBPP) strategies, and establishes the benefits of our strategy.Comment: 14 pages, 10 figures, accepted by IEEE/ACM Transactions on Networkin

Post-disaster 4G/5G Network Rehabilitation using Drones: Solving Battery and Backhaul Issues

Drone-based communications is a novel and attractive area of research in cellular networks. It provides several degrees of freedom in time (available on demand), space (mobile) and it can be used for multiple purposes (self-healing, offloading, coverage extension or disaster recovery). This is why the wide deployment of drone-based communications has the potential to be integrated in the 5G standard. In this paper, we utilize a grid of drones to provide cellular coverage to disaster-struck regions where the terrestrial infrastructure is totally damaged due to earthquake, flood, etc. We propose solutions for the most challenging issues facing drone networks which are limited battery energy and limited backhauling. Our proposed solution based mainly on using three types of drones; tethered backhaul drone (provides high capacity backhauling), untethered powering drone (provides on the fly battery charging) and untethered communication drone (provides cellular connectivity). Hence, an optimization problem is formulated to minimize the energy consumption of drones in addition to determining the placement of these drones and guaranteeing a minimum rate for the users. The simulation results show that we can provide unlimited cellular service to the disaster-affected region under certain conditions with a guaranteed minimum rate for each user.Comment: 2018 IEEE Global Communications Conference: Workshops: 9th International Workshop on Wireless Networking and Control for Unmanned Autonomous Vehicle

Teaching critical thinking and writing in higher education: an action research project

Critical thinking (CT) and critical writing (CW) skills are no doubt one of the core requirements and necessary tools required in Higher Education (HE). Previous research has highlighted the need as well as the benefits of supporting students with critical thinking, yet few have identified strategies which can be used effectively to promote students’ understanding and development of the concepts. This study identified some of the challenges often faced by students in HE with regards to CT and CW and explores how a targeted intervention could potentially develop students’ understanding and application of CT and CW. In particular, the study found that although students were aware of what CT and CW were, they required explicit instruction on how to apply and demonstrate these concepts in their assignments. Using an action research methodology with a random sample of 10 students from Black and Minority Ethnic (BME) backgrounds at a university in London, England, the research found effective strategies through the use of a targeted workshop as an intervention to develop and enhance students’ CT and CW skills. Participant feedback revealed the workshop had a positive impact on all the students highlighting the need for such interventions in order to suitably equip students with the ‘critical’ demands of studying

Band Structures of Symmetrical Graphene Superlattice with Cells of three Regions

We study the electronic band structures of massless Dirac fermions in symmetrical graphene superlattice with cells of three regions. Using the transfer matrix method, we explicitly determine the dispersion relation in terms of different physical parameters. We numerically analyze such relation and show that there exist three zones: bound, unbound and forbidden states. In the central zone of the band structures, we determine and enumerate the vertical Dirac points, opening gaps and additional Dirac points. Finally, we inspect the potential effect on minibands, the anisotropy of group velocity and the energy bands contours near Dirac points. We also discuss the evolution of gap edges and cutoff region near the vertical Dirac points.Comment: 19 pages, 10 figure

1+N Network Protection for Mesh Networks: Network Coding-Based Protection Using p-Cycles and Protection Paths

A method and system for providing protection of multiple communication sessions using the bandwidth resources on the order of those required to protect a single communication session. This is facilitated through the use of network coding on a protection cycle. Transmissions from all connections are coded together using network coding and transmitted in two different directions on a cycle, so that the signal can be recovered by the receiver in two ways: on the working path, and on the protection (cycle) path