Farouk Kamoun

ADMA: autonomous decentralized management architecture for MANETs: a simple self-configuring case study

ADMA represents an Autonomous Decentralized Management Architecture designed to provide Mobile Ad Hoc Networks (MANETs) with autonomic principles. It allows the network to configure and reconfigure itself under environment changes without any human intervention. Our solution operates in a peer-to-peer manner and does not require any centralized entity to perform network management functions. Each mobile node implementing ADMA components is able to take the appropriate decision based on predefined high level policies and collected monitoring information. We present in this paper the basic components of an ADMA node. Then, we provide a simple self-configuring case study of our design considering Voice over IP (VoIP) as a test application. Simulation results show an improvement of the VoIP delay and loss rate while applying predefined policies.

An interference-aware routing metric for multi-radio multi-channel wireless mesh networks

Achieving efficient QoS routing is one of the major concerns in multi-radio multi-channel wireless mesh networks (WMNs). Due to interference among links, bandwidth in these networks is neither a concave nor an additive metric. Thus, choosing the highest-throughput path among all feasible ones is a very challenging task. We propose in this paper a new routing metric which strikes a balance between the quality of wireless links and the resulting inter-flow and intra-flow interference introduced using such links on specific channels. Our metric does not necessarily choose the best path in terms of throughput. It selects a high-throughput path with low inter-flow and intra-flow interference by making a judicious use of different channels. Simulation results show that our routing metric significantly outperforms previously proposed metrics especially in large-scale WMNs. An improvement up to 20% of the total network throughput is particularly observed when multiple concurrent flows are considered in the network.

A high-throughput routing for multiuser diversity multicast

In this paper, we introduce a new routing strategy that allows high-throughput and channel-aware multi-rate multicast in wireless networks. This new routing strategy, based on the so-called End-to-end Multicast Session Efficiency (EMSE), is founded on the multi-user diversity (MUD) and the wireless broadcast advantage (WBA) features. It aims at: i) joining users that provide the best-received multicast throughput, ii) guaranteeing the use of homogenous capacities, iii) considering the effect of the transmission/retransmission number needed to exploit the multi-rate diversity on the routing throughput and iv) constructing the multicast structure composed of paths that give the best end-to-end throughput. Compared to other routing strategies and multicast schemes, the new routing algorithms show considerable improvement in terms of the average throughput and an important reduction in the relays number needed to convey the multicast data.

A generic conflict-aware multicast routing overlay for wireless networks

Multicast routing is a fundamental issue in wireless networks and related routing strategies should select the lowest number of parallel conflicting transmissions. However, current works on this problem accounts only for conflicts occurring within the transmission ranges of the nodes. Particularly, no work is interested in studying conflicting transmissions while using multi-rate concurrent multicast transmissions. In this paper, we develop a conflict-aware routing model, which aims at increasing the probability of scheduling conflict-free transmissions and improving the throughput by extremely exploiting the network availabilities in terms of link capacities, using different rates. The suggested conflict-aware routing strategy is implemented by means of a set of greedy heuristic algorithms. This strategy, called the CAware routing strategy, is “generic” because it can be coupled with any throughput-based routing metric or any routing structure. The proposed algorithms are studied to justify their performance trends and to show that conflict-awareness gives considerable routing benefits.

PEMSE: A high-throughput multicast routing protocol for multi-rate IEEE802.11

In the context of multi-rate communication, the throughput-based multicast routing that aims at maximizing the end-to-end throughput is very different from the commonly adopted delay-based multicast routing that aims at minimizing the end-to-end delay. Definitely, the delay-based approach is not suitable for applications that need to transfer large amounts of data (e.g. grid applications). In view of that, we introduce in this paper the first distributed routing strategy that allows high-throughput multicast in multi-rate IEEE802.11 networks. The new mesh-based routing, called the Protocol for End-to-end Multicast Session Efficiency (PEMSE), exploits the rate-diversity (MUD) and on the broadcast-nature of the wireless medium (WBA). It aims at: i) considering the effect of the number of transmissions/retransmissions, required to exploit the MUD, on the end-to-end multicast throughput and ii) establishing the routing structure that guarantees the best end-to-end multicast throughput. Simulations prove that PEMSE achieves considerable throughput improvement compared to the PUMA [11] routing protocol. They also show that PEMSE attains reasonable delays and delivery ratios.

Accurate and fast multi-rate multicast scheme in wireless networks

Exploiting multi-user diversity (MUD) for multicast consists in choosing the data rate(s) utilized to serve a number of users who have different channel qualities. Some of the proposed multicast schemes aim to maximize the throughput (e.g. EMTH), while others seek to reduce the transmission time (e.g. EMTT). Actually, it is well known that the process of computing the accurate MUD multicast throughput has a complexity that increases if the number of users rises. Generally, the metrics that maximize the throughput give an approximation of the achievable throughput. In this paper, we suggest an accurate, distributed, low-complexity and stateless multicast scheme that exploits the MUD. This scheme is called MOST. It selects the transmission strategy, i.e. the utilized set of data rates which maximizes the multicast throughput. MOST is computed using a very fast special way. It finds the best transmission strategy without any need to check all the transmission possibilities, or data rate combinations. This study highlights the complexity of the multicast scheme that verifies all the transmission strategies and describes the design and the performance of the new one, MOST.

Conflict-aware multicast in multiuser diversity-based wireless networks

Owing to the broadcast nature of the wireless medium, information transmitted to one or many users is often blocked by other concurrent transmissions. In a random access network, this issue, known as access conflicts, has a great impact on the overall performance, especially when performing multicast communications. To make the multi-rate multicast more vigorous and to reduce its vulnerability to access conflicts, we introduce an efficient, conflict-aware multicast transmitter scheduling that largely reduces the effect of close-by transmissions. We exploit the diversity between users to provide an efficient multicast strategy that enables each transmitter to select the data rates to use to serve the interested neighbours. Subsequently, we introduce two new concepts: the Transmission Rate-based Interference graph (TRIGraph) and the Concurrent Multi-rate Multicast Transmitter Set (CMMS). By means of a mathematical formulation, we prove that the transmitter schedule proposed outperforms the conflict-unaware multi-rate multicast schemes suggested.

Semantic Interactions for Context-Aware and Service-Oriented Architecture

Designing an architecture that supports pervasive computing usually addresses two issues: the context within interact the system components and the services which are available in the environment. This paper proposes a semantic approach to design an architecture for pervasive systems focusing on these two issues. The ambient is viewed as a set of context elements named CoxEl. Physically a CoxEl is a (mobile) device presents in the environment. The core of a CoxEl is an ontology that represents the context, the services, the resources and the neighbourhood of every CoxEl. This ontology is also used for semantic interaction between the CoxEls. This paper illustrates the different semantic interactions that may occurs among the CoxEls. It also describes the roles that play the CoxEls within the ambient.