Required Density of Multicast Capable Optical Cross Connects to Assure Efficient Multicasting

International audienceMany algorithms are developed to deploy multicast in optical networks. Those algorithms are designed to resolve the main issue of multicasting in optical networks, which is not all optical cross-connect in the network are capable to split an incoming light signal to more than one output interface. Some of those algorithms are based on additional signaling exchanged to generate the appropriate multicast trees, some use rerouting to source, and some generate multiple multicast trees for the same multicast group. The performance of those algorithms depends basically on the number and location of multicast capable cross-connects. A multicast capable cross-connect (MCOXC) is an optical node equipped with light splitter that allows splitting an incoming light signal to any two or more output interfaces. This paper studies how many nodes in optical networks must be equipped with light splitters to assure good performance of multicast algorithms in sparse splitting networks. This depends basically on the topology in terms of number of nodes, the average node degree and the variation of the node degree distribution over the network nodes. The more the variation of the node degree is, the more splitters are required

Performance Evaluation of Pre-computation Algorithms for Inter-Domain QoS Routing

International audienceInter-domain QoS routing is a very challenging problem area. This problem combines the complexity of QoS routing, with the limitations of inter-domain routing, such as domain heterogeneity and information confidentiality. The pre-computation offers a very promising solution for addressing this problem. Although the pre-computation scheme has been investigated in several previous studies for a single routing domain, applying pre-computation on an inter-domain level is not straightforward and necessitates deeper investigation. In this work, we study different algorithms for QoS routing based on pre-computation. First, we investigate an exact algorithm. This algorithm provides an optimal solution for the QoS routing problem. However, its application in large scale networks is not always practical. Second, heuristic solutions are also investigated in this work. Particularly, a detailed study of the ID-MEFPA and the ID-PPPA heuristics is provided. Analytical studies and extensive simulations confirm that the exact algorithm achieves the best success rate, but has a very high computational complexity. The ID-MEFPA heuristic has a lower complexity and provides a success rate always close to the exact algorithm. When inter-domain connectivity is high, the ID-PPPA heuristic is the most appropriate with the lowest computation complexity and a success rate very close to the exact algorithm

Hybrid Decision Algorithm for Access Selection in Multi-operator Networks

In this paper, we propose a hybrid decision algorithm for the selection of the access in multi-operator networks environment, where competing operators share their radio access networks to meet traffic and data rate demands. The proposed algorithm guarantees the user satisfaction and a global gain for all cooperating operators. Simulation results prove the efficiency of the proposed scheme and show that the cooperation between operators achieves benefits to both users and operators; user acceptance as well as the operator resource utilization and the operator revenue increase.Comment: WCNC, Istanbul : Turkey (2014

Best Operator Policy in a Heterogeneous Wireless Network

In this paper, we perform a business analysis of our hybrid decision algorithm for the selection of the access in a multi-operator networks environment. We investigate the ability of the operator to express his strategy and influence the access selection for his client. In this purpose, we study two important coefficients of the previously proposed cost function, Wu and Wop, and show that the value of these coefficients is not arbitrary. Simulation results show that the value of the ratio Wu/Wop enables a selection decision respecting operator's strategy and it affects the achieved global profit for all cooperating operators.Comment: ICeND, Beyrouth : Lebanon (2014

Localization of Single Link-Level Network Anomalies: Problem Formulation and Heuristic

Achieving accurate, cost-efficient, and fast anomaly localization is a highly desired feature in computer networks. A necessary and sufficient condition on the set of paths that need to be monitored upon detecting a single link-level anomaly in order to localize its source unambiguously have been established. However, this paper demonstrates that this condition is sufficient but not necessary. A necessary and sufficient condition that reduces the localization overhead, cost and delay significantly, as compared to the existing condition, is established. Furthermore, an Integer Linear Programming (ILP) algorithm that selects monitoring paths and monitor locations satisfying the established condition jointly, thereby enabling a trade-off between the number and locations of monitoring devices and the quality of monitoring paths, is devised. The problem is shown to be NP-hard through a polynomial-time reduction from the NP-hard facility location problem, and therefore, a scalable near-optimal heuristic is proposed. The effectiveness and the correctness of the proposed anomaly localization scheme are verified through theoretical analysis and extensive simulations

Multi-constrained path computation for inter-domain QoS-capable services

International audienceComputing inter-domain MultiProtocol Label Switching Traffic Engineering Label Switched Path (MPLS-TE LSP) using the Path Computation Element (PCE) through a predetermined sequence of domains is quite straight. Each PCE, using the Backward Recursive PCE-based Computation (BRPC), knows who is the next to be contacted in order to continue the computation. The optimality of the inter-domain MPLS-TE LSP path depends strongly on the choice of the predetermined sequence of domains on which the calculation works. In this paper we propose a novel procedure allowing a forward discovery of multiple inter-domain sequences and the computation of constrained inter-domain paths for MPLS-TE LSPs over these domains sequences. Other issues around the inter-domain path computation, such as route discovery and inter-domain loop avoidance, are investigated. Experimental evaluation shows that our solution is effective in terms of protocol and algorithmic efficiency and provides satisfiable performance with high success rate, reasonable message overhead and runtime

Optimizing Network Information for Radio Access Technology Selection

International audienceThe rapid proliferation of radio access technologies (e.g., HSPA, LTE, WiFi and WiMAX) may be turned into advantage. When their radio resources are jointly managed, heterogeneous networks inevitably enhance resource utilization and user experience. In this context, we tackle the Radio Access Technology (RAT) selection and propose a hybrid decision framework that integrates operator objectives and user preferences. Mobile users are assisted in their decisions by the network that broadcasts cost and QoS parameters. By signaling appropriate decisional information, the network tries to globally control users decision in a way to meet operator objectives. Besides, mobiles combine their needs and preferences with the signaled network information, and select their access technology so as to maximize their own utility. Deriving network information is formulated as a Semi-Markov Decision Process (SMDP). We show how to dynamically optimize long-term network reward, aligning with user preferences. Index Terms—Radio access technology selection, Semi-Markov Decision Process, hybrid decision-making approach

Comparison between access selection algorithms in multi-operator wireless networks

International audienceIn fifth generation mobile network, Radio Access Network sharing is an attractive solution for operators to counter the traffic growth and build cost-effective networks in order to improve coverage and capacity at reasonable investments and operational costs. It consists of sharing radio access resources between two or more operators. In such multi-operator environment access selection decision is an important issue for the mobile user and his home operator which the user has contract with. In literature, the majority of access selection algorithms are based on game theory which is very complex for implementation and the decision is slower in comparison with Multiple Attributes Decision Making (MADM) methods. In this paper, we use Simple Additive Weighting (SAW) methods and Nearest Performance Handover (NPH) algorithm for the access selection in a multi-operator environment. These algorithms based on MADM were initially conceived for the selection decision in a single operator environment. In addition, we compare the performance of these algorithms with our previously proposed cost function for the access selection in a multi-operator sharing network. Performance analyses are made in terms of user blocking percentages and global achieved profit. Simulation results showed that our decision algorithm guarantee the lowest blocking probability for all operators, it prevents overloading operator's with high numbers of guest users which affect own clients acceptance. In addition, it improves global achieved profits for all cooperating operators. However, SAW methods showed better performance than NPH concerning users blocking percentages, but NPH guarantees higher profits than SAW methods for the operators with limited capacity

Collaboration Schemes Evaluation in Multi-domain Networks

International audienceThe monitoring of the quality of service in a multi-domain network supervises the multi-domain service performance. A multi-domain service is a service that crosses several domains which can be managed by different providers. Since each domain can be managed with its own policies and may require confidentiality of its topology and its monitoring processes, we propose that the monitoring architecture has to be configurable. In this paper, we propose two collaboration schemes that are based on the reactive and the proactive modes. Both of collaboration schemes allow the multi-domain monitoring architecture to select the measurement points that will participate in the multi-domain monitoring and to configure the selected measurement points. In this paper, we present our proposed collaboration schemes and then we evaluate their performance through extensive simulations using Network Simulator (NS-2)

Export Methods in Fault Detection and Localization Mechanisms

International audienceMonitoring the quality of service in a multi-domain network allows providers to ensure the control of multi-domain service performance. A multi-domain service is a service that crosses multiple domains. In this paper, we propose several mechanisms for fault detection and fault localization. A fault is detected when an end-to-end contract is not respected. Faulty domains are domains that do not fulfill their Quality of Service (QoS) requirements. Our three proposed fault detection and localization mechanisms (FDLM) depend on the export method used. These export methods define how the measurement results are exported for analysis. We consider the periodic export, the triggered export, and a combined method. For each FDLM, we propose two sub-schemes that use different fault detection strategies. In this paper, we describe these mechanisms and evaluate their performance using Network Simulator (NS-2)