Nizar Bouabdallah

Resolving the fairness issues in bus-based optical access networks

Packet-based optical access ring is becoming a promising solution in metropolitan networks. Its performance depends mainly on how optical resource sharing takes place among the different competing access nodes. This network architecture has mostly been explored with regard to synchronous transmission, i.e., slotted wavelength-division multiplexing (WDM) ring. However, in this paper, we focus on the performance of asynchronous transmission-based networks with variable packet sizes. Analytical models are presented in an attempt to provide explicit formulas that express the mean access delay of each node of the bus-based optical access network. We prove that in such a network, fairness problems are likely to arise between upstream and downstream nodes sharing a common data channel. Furthermore, we show that sharing the channels available bandwidth fairly but arbitrarily between access nodes, as in slotted WDM rings, does not resolve the fairness problem in asynchronous system. In this regard, we exhibit the inherent limitations of the token bucket access rate-based algorithm once applied to asynchronous transmission bus-based networks. To alleviate the aforementioned problem, we device a new strategy called traffic control architecture using remote descriptors. The proposed solution is based on a preventive mechanism to grant access to the shared resource. As illustrated in this paper, the proposed solution alleviates the performance degradation and the resource underutilization, while achieving fairness among bus nodes.

Matching fairness and performance by preventive traffic control in optical multiple access networks

We present and evaluate a novel protocol of traffic control that aims at solving the fairness issue typical of shared medium networks such as metropolitan rings. The proposed solution called TCARD (Traffic Control Architecture using Remote Descriptors) is based on a preventive mechanism to grant access to the resource -- i.e. free bandwidth is preserved by a node according to the traffic requirements from the other network nodes. A review of the existing methods used to manage fairness in ring networks is done and points out their inherent problems (performance issues, resource wastage or inadequacy). In contrast, we show how the new protocol addresses the above limitations, notably through a performance evaluation study. The major conclusion is the ability to avoid the degradation in performances and the resource sub-utilization while achieving fairness within the network.

Sensor placement for maximizing wireless sensor network lifetime

The main concern in current wireless sensor networks is maximizing the network lifetime. Research activities conducted in this field rely on the partial utilization of the sensor network resources. Nonetheless, most of these works neglect the coverage problem. In this paper, we investigate the relationship between the network lifetime and the coverage problem. We show that efficient sensor network deployment, can lead to optimal energy saving. To do so, we propose an efficient placement algorithm addressing the case where the monitored area density is equal to two. Keywords-Sensor network lifetime; node placement; density control; simulation and analytical models

A practical traffic grooming scheme in all-optical networks

In this paper, we propose and evaluate a new concept of traffic aggregation in mesh networks that aims to alleviate both the bandwidth underutilization and scalability concerns typical of all-optical wavelength routed networks

An Approach for Mobility Modeling - Towards an Efficient Mobility Management Support in Future Wireless Networks

Multi-protocol label switching (MPLS) is deployed in the Internet backbone to support service differentiation and traffic engineering. In recent years, there has been an interest to extend the MPLS capability to the wireless access networks for mobility management support. In this paper, we present an analytical approach to study the handoff performance of a wireless system with a new micro-mobility support called micro mobile MPLS. Our scheme includes two protocol variants. In the first variant called FH-micro mobile MPLS, we consider the fast handoff mechanism, which anticipates the LSP procedure setup with an adjacent neighbor subnet that an mobile node (MN) is likely to visit. This mechanism is proposed to reduce service disruption by using the link-layer (L2) functionalities. In the second variant called FC-micro mobile MPLS, the forwarding chain concept, which is a set of forwarding path, is provided to track efficiently the host mobility within a domain. This concept can significantly reduce the resource reservation cost, the registration updates cost and provide low handoff latency. Analytical models, which capture the mobility behavior of an MN, are developed for cost analysis. Numerical and simulation results are given to justify the benefits of our proposed mechanisms

Performance analysis of micro mobile MPLS for future wireless networks

In this paper, we propose a practical approach to address how micro-mobility can be provided in an efficient way with continuous quality of service (QoS) support. Our proposal is based on multiprotocol label switching (MPLS) and mobile IP and relies on two-level hierarchy architecture. It supports two protocol variants. First, the fast handoff process, which anticipates the LSPs procedure setup with the neighboring locations where a mobile node (MN) may move to, is provided to reduce the service disruption. Second, a new mechanism based on the forwarding chain concept is proposed to track efficiently the host mobility within a domain. This concept can significantly reduce the registration updates cost and provide low handoff latency. Analytical models are developed and simulations are conducted to justify the benefits of our proposed mechanisms

Handoff support for mobility in future wireless MPLS networks: a proposal and analysis

In this paper, we propose a practical approach to address how micro-mobility can be provided in an efficient way with continuous quality of service (QoS) support. Our proposal is based on multiprotocol label switching (MPLS) and mobile IP and relies on two-level hierarchy architecture. It supports two protocol variants. First, the fast handoff process, which anticipates the LSP procedure setup with an adjacent neighbor subnet that a mobile node (MN) is likely to visit, is provided to reduce service disruption. Second, a new mechanism based on a master forwarding chain concept is proposed to track efficiently the host mobility within a domain. Our concept can significantly reduce the total signaling cost and provide low handoff latency. This can be achieved by dynamically controlling the number of registration updates with the root of the domain according to a cost comparison. Analytical models are developed and simulations are conducted to justify the benefits of our proposed mechanisms

A novel approach for improving wireless sensor network lifetime

One of the main concerns in wireless sensor networks is improving the network lifetime. The basic idea underlying current studies is the partial utilization of the sensor network resources. Nevertheless, most of the existing works focus on the connection upholding issue, while neglecting the coverage problem. Therefore, we investigate, in this paper, the relationship between the network lifetime and the coverage problem. We show that controlling the density function, relying on efficient sensor nodes placement, can improve significantly network lifetime. In this regard, we propose an efficient placement algorithm addressing the case where the monitored area density is equal to two. Afterwards, we extend the algorithm dealing with the case where the terrain density is higher than two. Finally, we gauge the efficiency of our proposal through analytical models and simulations

On the analysis of micro mobile mpls access networks: the fast handoff and the forwarding chain mechanisms

In this paper, we present analysis of Micro Mo- bile MPLS, a new micro-mobility management scheme which integrates the Mobile IP and MPLS protocols by using two- level hierarchy architecture. Our proposal supports two protocol variants. First, the fast handoff process, which anticipates the LSP procedure setup with an adjacent neighbor subnet that an mobile node (MN) is likely to visit, is provided to reduce service disruption by using the link-layer (L2) functionalities. Second, a new mechanism based on the forwarding chain concept is proposed to track efficiently the host mobility within a domain. This concept can significantly reduce the registration updates cost and provide low handoff latency. New analytical models, which capture the mobility behavior of an MN, are developed for cost analysis. Numerical and simulation results are given to justify the benefits of our proposed mechanisms.

On balancing between minimum energy and minimum delay with radio diversity for wireless sensor networks

The expected number of transmissions (ETX) metric represents the link quality in wireless sensor networks, which is highly variable for a specific radio and it can influence dramatically both of the delay and the energy. To adapt to these fluctuations, radio diversity has been recently introduced to improve the delivery rate but at the cost of increases in energy for wireless sensor networks. In this paper, we propose a scheme for radio diversity that can balance, depending on the traffic nature in the network, between minimizing the energy consumption or minimizing the end-to-end delay. The proposed scheme combines the benefit of two metrics, which aim separately to minimize the energy consumption, and to minimize delay when delivering packets to the end-user. We show by both analysis and simulation that our proposed scheme can adapt to the type of traffic that can occur in a network so that it minimizes both energy and delay for the respective traffic classes.