Houda Labiod

A performance comparison of multicast routing protocols in ad hoc networks

Multicast routing in mobile ad hoc NETworks (MANETs) is a recent research topic. In this paper, we present a performance study of three multicast protocols: ODMRP, ADMR, and SRMP. Source routing-based multicast protocol (SRMP) is a new on-demand multicast routing protocol that applies a source routing mechanism and constructs a mesh to connect group members. The strength of SRMP lies on its nodes selection criteria during mesh construction. Instead of using the shortest path as most of the other protocols, SRMP provides paths in terms of connectivity strength, higher battery life, and links availability. A performance comparison with ODMRP and ADMR shows that SRMP provides better route lifetime and battery lifetime.

Multicast Routing in Mobile Ad Hoc Networks

We focus on one critical issue in mobile ad hoc networks that is multicast routing. Advantages and limitations of existing routing protocols are illustrated. Optimal routes, stable links, power conservation, loop freedom, and reduced channel overhead are the main features to be addressed in a more efficient mechanism. In this paper, we propose a new on-demand multicast routing protocol, named Source Routing-based Multicast Protocol (SRMP). Our proposition addresses two important issues in solving routing problems: (i) path availability concept, and (ii) higher battery life paths. SRMP applies a source routing mechanism, and constructs a mesh to connect group members. It provides stable paths based on links availability according to future prediction of links states, and higher battery life paths. This protocol succeeded to minimize network load via designing optimal routes that guarantee reliable transmission and active adaptability. A performance comparison study with On-demand Multicast Routing Protocol (ODMRP) and Adaptive Demand-driven Multicast Routing (ADMR) protocol is undertaken. Analysis results show the strength of the SRMP nodes selection criteria and its efficient energy consumption compared to the other two protocols.

Hybrid Wireless Networks: Applications, Architectures and New Perspectives

With the advent and ubiquitous of wireless technology, a wide range of advanced services are expected to be supported including appealing services that currently exist in wired systems. Nevertheless, the resource constraints in wireless environment may render difficulty to realizing all the desirable services. Consequently, an infrastructure with high data rate is necessary to complement the resource constraints and to act as anchor points linking mobile nodes to other fixed networks as the Internet. Hybrid wireless networks have emerged as a promising solution, allowing mobile clients to achieve higher performance and service access in a seamless manner independent of their existence in wireless LAN (WLAN) communication range. In this paper we address the benefits of hybrid wireless networks, showing their possible applications and presenting a classification for their emerging architectures. Also, we identify the research challenge arising from the problem of applying the grid computing concept in such hybrid wireless environment, showing the expected benefits from the aggregated fixed-mobile capacity. Finally, we propose our vision for a potential architectural model, which is expected to provide useful services by the network operator or the service provider in such a hybrid environment

Dynamic Admission Control Algorithm for WLANs 802.11

Quality of service (QoS) is a key problem in wireless environments where bandwidth is scarce and channel conditions are time varying and sometimes implies highly packet losses. IEEE 802.11b/g/a wireless LAN (WLAN) are the most widely used WLAN standards today, and the IEEE 802.11e QoS enhancement standard exists and introduces QoS support for multimedia applications. This paper presents an admission control algorithm for 802.11e based wireless local area networks . The strengths of our admission control is dynamicity and flexibility of the algorithm, which adapts to the situation of the BSS, like global load, number of best effort AC, and position of QSTA by report of QAP. Thus it achieves higher throughput than other admission control for 802.11e. The 802.lie standard starves the low priority traffic in case of high load, and leads to higher collision rates, and did not make a good estimate of weight of queues, so there is an unbalance enters the flows with high priorities. A discussion is presented in detail using simulation-based evaluations, with an aim of comparing results of our admission control algorithm, with the 802.11e standard and the FHCF algorithm. Results reveal an improvement of the network load and a decrease of the number of collisions.Dynamic Admission Control Algorithm for WLANs 802.11

Load Balanced Multipath Routing in Mobile Ad hoc Network

A critical issue in the design of ad hoc network is the development of efficient routing protocols that can provide high quality communication for each data session and especially in the presence of a large amount of traffic. Several routing protocols have already been proposed. However, most of them focus only on single path routing. In this paper, we propose a load balancing technique based on multipath routing called LOBAM (load balanced multipath routing) and apply our scheme as an extension to the OLSR (optimized link state routing) protocol. In LOBAM routing, traffic is routed over multiple paths simultaneously. Our protocol uses a per packet allocation scheme to distribute data packets into multiple paths considering the load in its neighborhood. A simulation study is performed in heavily loaded network to demonstrate the effectiveness of our proposed scheme in comparison with the existing best effort OLSR protocol in terms of queuing delay, buffer size and packet delivery

A mobility-based scheme for dynamic clustering in vehicular ad-hoc networks (VANETs)

Vehicle clustering is an efficient approach to improve the scalability of networking protocols in vehicular ad-hoc networks (VANETs). However, some characteristics, like highly dynamic topology and intermittent connections, may affect the performance of the clustering. Establishing and maintaining stable clusters is becoming one of big challenging issues in VANETs. Recent years researches prove that mobility metric based clustering schemes show better performance in improving cluster stability. Mobility metrics, including moving direction, vehicle density, relative velocity and relative distance, etc., are more suitable for VANETs instead of the received radio strength (RSS) and identifier number metrics, which are applied for MANETs clustering. In this paper, a new dynamic mobility-based and stability-based clustering scheme is introduced for urban city scenario. The proposed scheme applies vehicles moving direction, relative position and link lifetime estimation. We compared the performance of our scheme with Lowest-ID and the most recent and the most cited clustering algorithm VMaSC in terms of cluster head duration, cluster member duration, number of clusters, cluster head change rate and number of state changes. The extensive simulation results showed that our proposed scheme shows a better stability performance.

Event Based Mobility Model for Subway Scenarios

High cost and complexity of mobile ad hoc networks (MANETs) testbeds let simulation as the best solution to experiment MANETs protocols and applications. Thus improving current simulation tools become crucial to provide valuable results. Mobility and propagation models are key element to realistically simulate users behaviour and wave propagations and therefore assure the validity of the simulations results. Unfortunately, accurate mobility models are complex and consider a wide range of parameters. Indeed to reflect reality every detail which may modify the mobility of users has to be included in the models. Consequently most of the realistic simulations models are not scalable and involve excessive computation time. Furthermore, these models are very generic and fail to capture the impact of event in real environments. In this paper we present an accurate subway mobility model which requires only few parameters. Moreover the simulated environment represents an application prolific context which can easily be set up. Finally we provide average simulation execution time for large networks and a comparison with the random waypoint model.

An analysis of ASMA trust evolution in a dense subway environment

Security in Mobile Ad hoc NETworks (MANETs) is a very prolific research topic. Many solutions have already been proposed to solve important security flaws regarding routing protocols conceived for these emerging networks. However most of them just focus on a small part of the security problems and only few frameworks have been proposed yet. In this paper we present an analysis study of a new framework named Adaptive Secured Multipath for Ad hoc networks (ASMA) that may be used to combine different security mechanisms and provide a global security solution. To improve the security of the framework, a new structure, named MacroGraph, is defined applying multipath routing and trust management. To analyze our solution, we focus on a realistic environment representing a subway and study the trust evolution of ASMA under different attack configurations.

A New Access Control Solution for a Multi-Provider Wireless Environment

The fundamental goal in future 4G mobile multi-service networks is to provide an efficient mobile computing environment. We presume that future terminals will be equipped with multiple heterogeneous wireless interfaces. We want to enable each user to seamlessly move between different providers’ networks. Besides seamless roaming, a key consideration is also devoted to quality-of-service provision. In this article, we propose a model and an architectural framework for supporting quality of service in the context of interconnected multi-provider wireless systems. The proposed integrated COPS-based management and RADIUS-based access control architecture will allow providers to offer multimedia services while optimizing the use of the underlying network resources. We suggest new concepts and protocols to provide solutions to these challenges and describe the French national research project named MMQoS aiming on building such future networks.

Physical rate and contention window based admission control (PRCW) for 802.11 WLANs

Quality of service (QoS) is a key problem in wireless environments where bandwidth is scarce and channel conditions are time varying and sometimes implies highly packet losses. IEEE 802.11b/g/a wireless LAN (WLAN) are the most widely used WLAN standards today, and the IEEE 802.11e QoS enhancement standard exists and introduces QoS support for multimedia applications. This paper presents a class based admission control algorithm for 802.11e based wireless local area networks. The strengths of our admission control is dynamicity and flexibility of the algorithm, which adapts to the situation of the BSS, like global load, number of best effort AC, and position of QSTA by report of QAP, thing that have never been taken together, but each solutions have used a point of sight separately. Thus it achieves higher throughput than other admission control for 802.11 e. The idea which consists of changing parameters [AIFSN, CWmin and CWmax] of best effort flows, for decreasing collisions, is used, so we think that it is an efficient way to protect QoS flows from best effort flows, and to allow reducing then number of collisions. So we increase AIFSN [best effort flow], CWmin and CWmax only at 70% of load of network, to prevent starvations of best effort flows, and so we increase rate utilization of channel. We also use the current rate transmission of QSTAs, according to their positions, instead of the minimum rate transmission used by standard 802.11e, for calculate the load of network and derived the TXOPi necessary for all the stations, with i=1 to number of active stations. The 802.11e standard starves the low priority traffic in case of high load, and leads to higher collision rates, and did not make a good estimate of weight of queues, so there is an unbalance enters the flows with high priorities. A discussion is presented in detail using simulation-based evaluations, with an aim of comparing results of our admission control algorithm, with the 802.11e standard and the FHCF algorithm. Results reveal an improvement of the network load and a decrease of the number of collisions.