Guy Pujolle

Service level agreement and provisioning in optical networks

This article proposes a service level agreement applied to the optical domain (O-SLA), which is expected to be the near- and long-term network technology of the great bandwidth capacity offered by optical devices. After an exposition of the rationale behind an optical SLA, parameters that could be included in this O-SLA, as well as their values for four classes of services are proposed. Different client (wavelength or subwavelength) and service types (from leased wavelength to bandwidth on demand) are distinguished when necessary. The last part of this article presents issues related to the provisioning of services emanating from this O-SLA.

VNE-AC: Virtual Network Embedding Algorithm Based on Ant Colony Metaheuristic

In this paper, we address a virtual network embedding problem. Indeed, our objective is to map virtual networks in the substrate network with minimum physical resources while satisfying its required QoS in terms of bandwidth, power processing and memory. In doing so, we minimize the reject rate of requests and maximize returns for the substrate network provider. Since the problem is NP-hard and to deal with its computational hardness, we propound a new scalable embedding strategy named \texttt{VNE-AC} based on the Ant Colony metaheuristic. The intensive simulations and evaluation results show that our proposal enhances the substrate providers revenue and outperforms the related strategies found in current literature.

QoS for Ad hoc Networking Based on Multiple Metrics: Bandwidth and Delay

A link state routing approach makes available detailed information about the connectivity and the condition found in the network. OLSR protocol is an optimization over the classical link state protocol, tailored for mobile ad hoc networks. In this article, we design a QoS routing scheme over OLSR protocol, called QOLSR. In our proposal, we introduce more appropriate metrics than the hop distance used in OLSR. In order to improve quality requirements in routing information, delay and bandwidth measurements are applied. The implications of routing metrics on path computation are examined and the relational behind the selection of bandwidth and delay metrics are discussed. We first consider algorithms for single-metric approach, and then present a distributed algorithm for multiple metrics approach. We also present a scalable simulation model close to real operations in Ad Hoc Networks. The performance of our protocol are extensively investigated by simulation. Our results indicate that the attained gain by our proposal represent an important improvement in such mobile wireless networks.

FCRA: Femtocell Cluster-Based Resource Allocation Scheme for OFDMA Networks

Recently, operators have resorted to femtocell networks in order to enhance indoor coverage and quality of service since macro-antennas fail to reach these objectives. Nevertheless, they are confronted to many challenges to make a success of femtocells deployment. In this paper, we address the issue of resources allocation in femtocell networks using OFDMA technology (e.g., WiMAX, LTE). Specifically, we propose a hybrid centralized/distributed resource allocation strategy namely \textit{Femtocell Cluster-based Resource Allocation} (\texttt{FCRA}). Firstly, \texttt{FCRA} builds interference-free femtocell clusters. Then, within a cluster the optimal resource allocation for each femtocell is performed by its cluster-head. Finally, the contingent collisions among different clusters are fixed. To achieve this, we formulate the problem mathematically as Min-Max optimization problem. Performance analysis shows that \texttt{FCRA} converges to the optimal solution in small-sized networks and outperforms two prominent related schemes (\texttt{C-DFP} and \texttt{DRA}) in large-sized ones. The results concern the throughput satisfaction rate, the spectrum spatial reuse, and the convergence time metrics.

Enhancing peer-to-peer content discovery techniques over mobile ad hoc networks

Content dissemination over mobile ad hoc networks (MANETs) is usually performed using peer-to-peer (P2P) networks due to its increased resiliency and efficiency when compared to client-server approaches. P2P networks are usually divided into two types, structured and unstructured, based on their content discovery strategy. Unstructured networks use controlled flooding, while structured networks use distributed indexes. This article evaluates the performance of these two approaches over MANETs and proposes modifications to improve their performance. Results show that unstructured protocols are extremely resilient, however they are not scalable and present high energy consumption and delay. Structured protocols are more energy-efficient, however they have a poor performance in dynamic environments due to the frequent loss of query messages. Based on those observations, we employ selective forwarding to decrease the bandwidth consumption in unstructured networks, and introduce redundant query messages in structured P2P networks to increase their success ratio.

Performance management issues in ATM networks: traffic and congestion control

The goal is first to introduce performance monitoring aspects of asynchronous transfer mode (ATM) networks and then to focus on traffic and congestion control schemes. To deal with this performance monitoring management, a framework for defining a generic intelligent and integrated model for network management is described. As an example of the efficiency of this intelligent management architecture, we measure the performance of a new congestion control scheme. This scheme uses the cell loss priority (CLP) bit, the explicit forward congestion indicator and the explicit backward congestion indicator. The intelligent management uses different parameters and builds a complex but efficient control scheme. We show that this new control scheme allows performance to be increased by an order of magnitude.

An intelligent handover management system for future generation wireless networks

Future generation wireless networks should provide to mobile users the best connectivity to services anywhere at anytime. The most challenging problem is the seamless intersystem/vertical mobility across heterogeneous wireless networks. In order to answer it, a vertical handover management system is needed. In our paper, we propose an intelligent solution answering user requirements and ensuring service continuity. We focus on a vertical handover decision strategy based on the context-awareness concept. The given strategy chooses the appropriate time and the most suitable access network among those available to perform a handover. It uses advanced decision algorithms (for more efficiency and intelligence) and it is governed by handover policies as decision rules (for more flexibility and optimization). To maintain a seamless service continuity, handover execution is based on mobile IP functionalities. We study our decision system in a case of a 3G/UMTS-WLAN scenario and we discuss all the handover decision issues in our solution.

Seamless Continuity of Service across WLAN and WMAN Networks: Challenges and Performance Evaluation

Future network environments will be heterogeneous and mobile terminals will have the opportunity to dynamically select among many different access technologies. Therefore, it is important to provide service continuity in case of vertical handoff when terminals change the access technology. Two important wireless access technologies are WLAN (wireless local access networks) and WMAN (wireless metropolitan access networks). In this paper, we address several challenges related to a seamless integration of those technologies. We highlight important aspects for designing a WLAN/WMAN interworking architecture and we address important quality of service (QoS) issues for such interworked systems like degree of QoS support provided by the technologies, QoS mapping and signalling for vertical handoff. By formulating several interworking scenarios, where WLAN users with ongoing voice, video and data sessions handoff to WMAN, we study QoS and performance issues and analyze feasibility of seamless session continuity through simulations.

A Survey on Identity Management for the Future Network

The Internet as a platform for ubiquitous communication has quickly advanced in the last years. New services have emphasized the limits of the current Internet and motivated the development of the Future Internet. Future communication infrastructures intend to be more distributed and, ideally, more secure, resulting in high complexity. Further, as new technologies emerge, new requirements and security issues are highlighted. These issues reinforce the importance of Identity Management systems for the network infrastructure in the Future Internet, termed Future Network, to provide adequate dynamic services in relation to users personal data and requirements. Hence, this survey presents the state of the art of Identity Management systems for the Future Network. It highlights the existing architectures, specific devices applied, challenges and future perspectives.

L-VIRT: Range-free 3-D localization of RFID tags based on topological constraints

RFID is an automatic identification technique that stores and remotely retrieves data on small devices called tags. This technology enables tracking of people and objects, supporting the conception of pervasive networks if identities are linked in real-time to their locations. We propose L-VIRT, a 3-D localization method for RFID tags based only on connectivity information. Virtual landmarks are combined with defined topological constraints to localize tags. A relaxation of the constraints is introduced to attenuate the effect of reading errors and, thus, to increase the precision of the localization. Simulation results show a fine-grained accuracy in free space or moderately obstructive environments, and a satisfactory accuracy in very cluttered environments. Moreover, the use of additional mobile readers enables rapid and large localization error reduction in sparse deployments of static readers.