Slim Abdellatif

Software defined networking and virtualization for broadband satellite networks

Satellite networks have traditionally been considered for specific purposes. Recently, new satellite technologies have been pushed to the market enabling high-performance satellite access networks. On the other hand, network architectures are taking advantage of emerging technologies such as software-defined networking (SDN), network virtualization and network functions virtualization (NFV). Therefore, benefiting communications services over satellite networks from these new technologies at first, and their seamless integration with terrestrial networks at second, are of great interest and importance. In this paper, and through comprehensive use cases, the advantages of introducing network programmability and virtualization using SDN and/or NFV in satellite networks are investigated. The requirements to be fulfilled in each use case are also discussed.

Publish/subscribe-enabled software defined networking for efficient and scalable IoT communications

The Internet of Things (IoT) is the result of many different enabling technologies such as embedded systems, wireless sensor networks, cloud computing, big-data, etc., which are used to gather, process, infer, and transmit data. Combining all these technologies requires a research effort to address all the challenges of these technologies, especially for sensing and delivering information from the physical world to cloud-hosted services. In this article we outline the most important issues related to standardization efforts, mobility of objects, networking and gateway access, and QoS support. In particular, we describe a novel IoT network architecture that integrates software defined networking (SDN) and data distribution service (DDS) middleware. The proposed architecture will improve service delivery of IoT systems and will bring flexibility to the network.

Evaluating Routing Protocols for the Wireless Mesh Backbone

Wireless mesh networks offer promising solutions for extending the coverage of wireless local area networks along with increased communication reliability. The wireless mesh backbone serves as an access network for a large number of heterogeneous networks, providing them internet connectivity. Comprising of dedicated routers, the backbone differs significantly from conventional ad hoc networks due to lack of mobility and energy constraints. Classical ad hoc routing protocols developed for typical ad hoc networks, concentrate on mobility and energy conservation and their suitability and possible adoption for the backbone warrants careful evaluation. In this paper, we analyze the performance of four popular ad hoc routing protocols including two reactive (DSR, AODV) and two proactive (OLSR, DSDV) protocols for the mesh backbone using simulation. We provide results for routing overhead, packet delivery fraction and end-to-end delay metrics. Optimizations for these protocols are proposed and design directions for future backbone routing protocols are outlined.

Route Maintenance in IEEE 802.11 wireless mesh networks

In this paper, we propose a novel Route Maintenance scheme for IEEE 802.11 wireless mesh networks. Despite lack of mobility and energy constraints, reactive routing protocols such as AODV and DSR suffer from frequent route breakages in 802.11 based infrastructure wireless mesh networks. In these networks, if any intermediate node fails to successfully transmit a packet to the next hop node after a certain number of retransmissions, the link layer reports a transmission problem to the network layer. Reactive routing protocols systematically consider this as a link breakage (and therefore a route breakage). Transmission failures can be caused by a number of factors e.g. interference or noise and can be transient in nature. Frequent route breakages result in significant performance degradation. The proposed mechanism considers multiple factors to differentiate between links with transient transmission problems from those links which have permanent transmission problems and takes a coherent decision on link breakage. The proposed mechanism is implemented in AODV for single-radio single-channel mesh network and an extension is incorporated in multi-radio multi-channel scenarios. Simulation results show substantial performance improvement compared to classical AODV and local route repair schemes.

A DDS/SDN Based Communication System for Efficient Support of Dynamic Distributed Real-Time Applications

Many distributed real-time applications have dynamic requirements regarding communication delay and bandwidth. The Data Distribution Service (DDS) middleware is a key enabling technology used to support such applications. Indeed, the publish/subscribe distribution model of DDS with the ability to assign dynamic QoS (Quality of Service) parameters to DDS distribution services is able to take into account changes in the exchanged data flows and in the required QoS. This variability is taken into account at the middleware level to adjust some of DDS QoS mechanisms but is rarely propagated to the network layer to provide dynamic network communication services that fit the varying DDS distribution service needs. Usually, an over provisioned network is used, leading to network resource wastage. This paper addresses this issue and proposes a communication architecture that combines DDS with a new emerging class of communication networks named Software Defined Networks (SDN) to support efficiently dynamic distributed applications. SDN bring flexibility to the network and enable the provision of on-demand dynamic network communication services.

On resource management in heterogeneous wireless access networks application to automated highway systems

This paper discusses a general solution to provide quality of service (QoS) in heterogeneous wireless networks. The mechanisms we mainly discuss in this paper is resource management in a WiMAX-WiFi heterogenous wireless network within the context of an automated highway system (AHS). We show how different mechanisms within each network can be combined in order to insure the required QoS.

Virtual Link Embedding in Software-Defined Multi-radio Multi-channel Multi-hop Wireless Networks

There is rising interest in applying SDN principles to wireless multi-hop networks, as this paves the way towards bringing the programmability and flexibility that is lacking in todays distributed wireless networks (ad-hoc, mesh or sensor networks) with the promising perspectives of better mitigating issues as scalability, mobility and interference management and supporting improved controlled QoS services. This paper investigates this latter aspect and proposes an Integer Linear Programming (ILP) based wireless resource allocation scheme for the provision of point-to-point and point-to-multipoint end-to-end virtual links with bandwidth requirements in software-defined multi-radio multi-channel wireless multi-hop networks. The proposed scheme considers the specificities of wireless communications: the broadcast nature of wireless links which can be leveraged for point-to-multipoint links resource allocations, and, the interference between surrounding wireless links. It also considers switching resource consumption of wireless nodes since, for the time being, the size of SDN forwarding tables remains quite limited. A Genetic Algorithm derived from the ILP formulation is also proposed to address the case of large wireless networks. Our simulation results show that both methods work effectively.

LoRa technology MAC layer operations and Research issues

Abstract LoRaWAN is a wireless technology for Low Power Wide Area Network (LPWAN). Today, it is considered as one of the most serious alternatives for IoT thanks to its low cost, low power consumption equipments and its open business model. LoRaWAN specifications proposes interesting solutions regarding Medium Access Control (MAC) layer operations to deliver the best communication performances to connected things. Despite its crucial impact on the overall performances, few researches consider the LoRaWAN MAC layer. This paper presents LoRaWAN MAC layer operations and services based on the LoRaWAN Alliance technical specifications. In addition, it proposes an overview of recent studies related to LoRaWAN performances and stands out the major challenges to be addressed in order to enhance the performance of data exchanges.

Supporting end-to-end internet QoS for DDS-based large-scale distributed simulation

Supporting end-to-end quality-of-service (QoS) in Large-scale distributed interactive simulations (DIS) is hard due to the heterogeneity and scale of communication networks, transient behavior, and the lack of mechanisms that holistically schedule different resources end-to-end. This paper aims to cope with these problems in the context of wide area network (WAN)-based DIS applications that use the OMG Data Distribution Service (DDS) QoS-enabled publish/subscribe middleware. First, we show the design and implementation of the QoS framework, which is a policy-driven architecture that shields DDS-based DIS applications from the details of network QoS mechanisms by specifying per-flow network QoS requirements, performing resource allocation and validation decisions (such as admission control), and enforcing per-flow network QoS at runtime. Second, we evaluate the capabilities of the framework in an experimental large-scale multi-domains environment. The evaluation of the architecture shows that the proposed QoS framework improves the delivery of DDS services over heterogeneous IP networks, and confirms its potential impact for providing network-level differentiated performance.

Multi-level Model for Synchronizing Temporal Streams on HLA-Based Distributed Multimedia Applications Using HTSPN

The major issue in distributed multimedia simulation is how to specify and implement synchronization scheme satisfying the QoS applications requirements. This paper suggests the use of a powerful synchronization scheme based on HTSPN between different flows issued from distributed multimedia systems to fulfill these requirements. Such an interpreted model permits powerful analysis techniques for validating the quality of service in computer networks before protocol implementation. Consequently, it allows the specification of both the temporal non-determinism of weakly distributed applications and the temporal variability of the multimedia processing. An example is used to demonstrate the capabilities of this scheme to specify the QoS requirements of simulated applications.