Showing papers by "Bernard Cousin published in 2016"

ESR: Energy aware and stable routing protocol for WBAN networks

Abstract: Wireless body area network (WBAN) calls for a next generation in wireless networks. This new generation is designed to operate autonomously, to connect various medical sensors and appliances located on or inside a human body. Mobile WBANs have been designed, offering numerous practical and innovative services so that health care and quality of life can be improved. Thus, the equipment used in WBAN is usually mobile and autonomous which imposes high constraint on energy. That is, the energy efficiency must be taken into account as one of the objectives of the routing protocol designed for this type of network. Although mobile nodes may cause link breaks, most of studies ignore the link stability. In this paper, we propose a stable, reliable, energy efficient routing protocol for mobile Wireless Body Area Networks. It preserves the residual energy of nodes with an increase network lifetime. To achieve this goal, we use an objective model to select energy-efficient paths with stable links. Simulation results demonstrate that our protocol improves the state of the art in terms of energy consumption and routing overhead.

A Hybrid Approach for Radio Access Technology Selection in Heterogeneous Wireless Networks

Abstract: In heterogeneous wireless networks, different radio access technologies are integrated and may be jointly managed. To optimize network performance and capacity, efficient common radio resource management (CRRM) mechanisms need to be defined. This paper tackles the radio access technology (RAT) selection, a key CRRM functionality, and proposes a hybrid decision framework that dynamically integrates operator objectives and user preferences. Mobile users are assisted in their decisions by the network that broadcasts cost and QoS information. Our hybrid approach involves two inter-dependent decision-making processes. The first one, on the network side, consists in deriving appropriate network information so as to guide user decisions in a way to meet operator objectives. The second one, where individual users combine their needs and preferences with the signaled network information, consists in selecting the RAT to be associated with in a way to maximize user utility. We first focus on the user side and present a satisfaction-based multi-criteria decision-making method. By avoiding inadequate decisions, our algorithm outperforms existing solutions and maximizes user utility. Further, we introduce two heuristic methods, namely the staircase and the slope tuning policies, to dynamically derive network information in a way to enhance resource utilization. The performance of each decision-making process, on the network and user sides, is evaluated separately through extensive simulations. A comparison of our hybrid approach with six different RAT selection schemes is also presented.

Optical power control in GMPLS control plane

Abstract: The exponential traffic growth in optical networks has triggered the evolution from fixed-grid to flex-grid technology. This evolution allows better spectral efficiency and spectrum usage over current optical networks in order to facilitate huge dynamic traffic demands. The promise of flex-grid technology in terms of increasing the number of optical channels established over optical links, however, may not be sustainable because of the associated increase in optical amplification power. In this work, we detail a power control process that takes advantage of link optical power and channel optical signal-to-noise ratio (OSNR) margins to allow network operators to support this optical power increase while maintaining the use of legacy optical amplifiers. New generalized multiprotocol label switching (GMPLS) protocol extensions are proposed on which to integrate the optical power control process in the control plane. The performance of the process is evaluated in terms of the blocking ratio and network throughput over fixed-grid and flex-grid networks. Results show that controlling optical power benefits from the flex-grid technology in terms of spectrum and capacity gain and reduces optical connection blocking.

Flexible call admission control with preemption in LTE networks

Abstract: This paper introduces a new call admission control (CAC) mechanism for Long Term Evolution (LTE) networks supporting multimedia services with different classes of traffic. Our CAC mechanism classifies calls into real time and non-real time users, then estimates the channel quality based upon the received signal strength (RSS) value, and finally identifies the call as either new call (NC) or handoff call (HC) request before performing admission control decision. We also use a simple preemption technique in order to allocate the resources to high priority bearer requests. We show through extensive simulation analysis that our CAC mechanism provides high number of accepted users with higher priorities while providing high system throughput.

Optical power control to efficiently handle flex-grid spectrum gain over existing fixed-grid network infrastructures

Abstract: The exponential traffic growth in optical networks has triggered the evolution from Fixed-Grid to Flex-Grid technology. This evolution allows better spectral efficiency and spectrum usage over current networks in order to facilitate dynamic and huge traffic demands. The integration of Flex-Grid technology increases the number of optical channels established over optical links, leading, however, to an increase in amplification power and possibly saturating optical amplifiers. In this work, we propose a power adaptation process that takes advantage of link optical signal to noise ratio (OSNR) margins to allow network operators to support this power increase while maintaining the use of legacy amplifiers. Results show that controlling channel optical power benefits from the Flex-Grid in terms of spectrum and capacity gain using in-place amplifier infrastructure.

Centralized multi-cell resource and power allocation for multiuser OFDMA networks

Abstract: Multiuser Orthogonal Frequency Division Multiple Access (OFDMA) networks, such as Long Term Evolution networks, use the frequency reuse-1 model to face the tremendous increase of mobile traffic demands, and to increase network capacity. However, inter-cell interference problems are generated, and they have a negative impact on cell-edge users performance. Resource and power allocation should be managed in a manner that alleviates the negative impact of inter-cell interference on system performance. In this paper, we formulate a novel centralized multi-cell resource and power allocation problem for multiuser OFDMA networks. The objective is to maximize system throughput while guaranteeing a proportional fair rate for all the users. We decompose the joint problem into two independent problems: a resource allocation problem and a power allocation problem. We prove that each of these problems is a convex optimization problem, and that their optimal solution is also an optimal solution to the original joint problem. Lagrange duality theory and subgradient projection method are used to solve the centralized power allocation problem. We study the convergence of our centralized approach, and we find out that it reduces inter-cell interference, and increases system throughput and spectral efficiency in comparison with the frequency reuse-1 model, reuse-3 model, fractional frequency reuse, and soft frequency reuse techniques.

Link Design and Legacy Amplifier Limitation in Flex-Grid Optical Networks

Abstract: Flex-grid technology is an effective means to improve the spectral efficiency of optical communication. For a given amplifier spectral bandwidth, it gives rise to the increase in the number of optical channels as it reduces channel spacing. Therefore, in order to reap full benefits from the flex-grid saved spectrum, further amplification power is required with respect to conventional fixed grid. This is a strong limitation if the legacy amplifiers cannot meet this new requirement due to their optical power limits. In this paper, we demonstrate that exploiting the link margins allows the support of this increase while maintaining in use legacy amplifiers.

Resource saving: Which resource sharing strategy to protect primary shortest paths?

Abstract: Two strategies of resource sharing are proposed in literature to provide protection while saving resources: (1) restrained sharing which applies the resource sharing to the backup paths only and (2) global sharing which extends the resource sharing to the primary and backup paths. In this paper, we compared the two strategies of resource sharing when the primary paths correspond to the shortest ones according to a strictly positive and static metric. Even when the amount of resources that can be shared between the primary and the backup paths is unbounded, we proved that the maximum number of backup paths is still bounded. Besides, our simulations showed that the resource sharing between the primary and backup paths has very slight impact on the backup path rejection, i.e. the two strategies of resource sharing have very close performances.

Performance evaluation of legacy QCN for multicast and multiple unicast traffic transmission

Abstract: A multicast congestion control scheme is an interesting feature to control group communication applications such as teleconferencing tools and information dissemination services. This paper addresses a comparison between multiple unicast and multicast traffic congestion control for Carrier Ethernet. In this work, we proposed to study the quantized congestion notification QCN, which is a layer 2 congestion control scheme, in the case of multicast traffic and multiple unicast traffic. Indeed, the QCN has recently been standardized as the IEEE 802.1Qau Ethernet Congestion Notification standard. This scheme is evaluated through simulation experiments, which are implemented by the OMNeT++ framework. This paper evaluates the reaction point start time congestion detection, feedback rate, loss rate, stability, fairness and scalability performance of the QCN for multicast traffic transmission and multiple unicast traffic transmission. This paper also draws a parallel between QCN for multicast traffic transmission and that for multiple unicast traffic transmission. Despite the benefit of integrating the multicast traffic, results show that performance could degrade when the network scales up. The evaluation results also show that it is probable that the feedback implosion problem caused by the bottlenecks could be solved if we choose to set the queue parameter Qeq threshold value at a high value, 75% of the queue capacity for instance. Copyright © 2016 John Wiley & Sons, Ltd.

Enhanced ethernet congestion management scheme for multicast traffic

Abstract: The Quantized Congestion Notification QCN is a Layer 2 congestion control scheme for Carrier Ethernet data center networks. The QCN has been standardised as an IEEE 802.1Qau Ethernet Congestion Notification standard. This paper report a results of a QCN study with multicast traffic and proposes an enhancement to the QCN. In fact, in order to be able to scale up, the feedback implosion problem has to be solved. Therefore, we resorted to the representative technique, which uses a selected congestion point i.e. the overloaded queue in a switch, to provide timely and accurate feedback on behalf of the congested switches in the path of multicast traffic. This paper evaluates the rate variation, the feedback overhead, the loss rate, the stability, the fairness and the scalability performance of the standard QCN with multicast traffic and the enhanced QCN for multicast traffic. This paper also compares their performance criteria. The evaluation results show that the enhanced proposition of the QCN for multicast traffic gives better results than the standard QCN with multicast traffic. Indeed, the feedback implosion problem is settled by decreasing remarkably the feedback rate. Copyright © 2016 John Wiley & Sons, Ltd.