Rami Langar

Region-Based Location-Service-Management Protocol for VANETs

The efficiency by which a node of a vehicular ad hoc network (VANET) can route messages to destinations heavily depends on the VANETs ability to keep track of the locations of its nodes (vehicles). Current location-management schemes lack scalability and, hence, are proven unable to work in large-scale networks. Therefore, location management in VANETs remains a major challenge. In this paper, we propose a new region-based location-service-management protocol (RLSMP) that uses mobility patterns as means to synthesize node movement and, thus, can be used in large VANET applications. The protocol attempts to relax the scalability issue suffered by other protocols by employing message aggregation in location updating and in querying. Furthermore, due to the protocols intrinsic locality awareness, it achieves minimum control overhead. To evaluate the efficiency of the protocol, we study its performance analytically and by using simulation for a 2-D random-walk model, as well as on real mobility patterns. The performance of the protocol is compared with that of other prominent location-management protocols.

Intersection-Based Geographical Routing Protocol for VANETs: A Proposal and Analysis

This paper presents a class of routing protocols for vehicular ad hoc networks (VANETs) called the Intersection-based Geographical Routing Protocol (IGRP), which outperforms existing routing schemes in city environments. IGRP is based on an effective selection of road intersections through which a packet must pass to reach the gateway to the Internet. The selection is made in a way that guarantees, with high probability, network connectivity among the road intersections while satisfying quality-of-service (QoS) constraints on tolerable delay, bandwidth usage, and error rate. Geographical forwarding is used to transfer packets between any two intersections on the path, reducing the paths sensitivity to individual node movements. To achieve this, we mathematically formulate the QoS routing problem as a constrained optimization problem. Specifically, analytical expressions for the connectivity probability, end-to-end delay, hop count, and bit error rate (BER) of a route in a two-way road scenario are derived. Then, we propose a genetic algorithm to solve the optimization problem. Numerical and simulation results show that the proposed approach gives optimal or near-optimal solutions and significantly improves VANET performance when compared with several prominent routing protocols, such as greedy perimeter stateless routing (GPSR), greedy perimeter coordinator routing (GPCR), and optimized link-state routing (OLSR).

FCRA: Femtocell Cluster-Based Resource Allocation Scheme for OFDMA Networks

Recently, operators have resorted to femtocell networks in order to enhance indoor coverage and quality of service since macro-antennas fail to reach these objectives. Nevertheless, they are confronted to many challenges to make a success of femtocells deployment. In this paper, we address the issue of resources allocation in femtocell networks using OFDMA technology (e.g., WiMAX, LTE). Specifically, we propose a hybrid centralized/distributed resource allocation strategy namely \textit{Femtocell Cluster-based Resource Allocation} (\texttt{FCRA}). Firstly, \texttt{FCRA} builds interference-free femtocell clusters. Then, within a cluster the optimal resource allocation for each femtocell is performed by its cluster-head. Finally, the contingent collisions among different clusters are fixed. To achieve this, we formulate the problem mathematically as Min-Max optimization problem. Performance analysis shows that \texttt{FCRA} converges to the optimal solution in small-sized networks and outperforms two prominent related schemes (\texttt{C-DFP} and \texttt{DRA}) in large-sized ones. The results concern the throughput satisfaction rate, the spectrum spatial reuse, and the convergence time metrics.

A Survey of Autonomic Network Architectures and Evaluation Criteria

Autonomic network management is a promising approach to reduce the cost and the complexity of managing network infrastructures. It attempts to lead the human administrator out of the network control loop, leaving the management tasks to be performed by the network itself. Due to its important implication on automating management systems, this area has attracted a growing attention from both academia and industry. In this paper, we provide a holistic view of autonomic architecture proposals and the evaluation metrics existing so far. Based on this, we identify some new criteria important to the autonomic architectures. Finally, we compare different existing autonomic architectures and describe the pros and cons of each one regarding to the network management and performances.

Mobility-aware clustering algorithms with interference constraints in wireless mesh networks

One of the major concerns in wireless mesh networks (WMNs) is the radio resource utilization efficiency, which can be enhanced by managing efficiently the mobility of users as well as the interference effect among neighboring links. To achieve this, we propose in this paper the use of clustering and a new interference-aware routing metric, called INX. Specifically, we first propose two mobility-aware clustering algorithms that take into consideration the mobility properties of users in order to improve the WMN performance. Then, we propose the use of INX in the clustering process in order to maximize the total network throughput. We prove through simulations that both clustering schemes can achieve significant gains in terms of radio resource utilization and load balancing, especially when using the INX metric. Hence, and as a main contribution, we show that by taking into account the interference effect between links, we can improve the performance of our clustering algorithms and increase the gain initially observed with the conventional hop-count metric.

Cluster-Based Resource Management in OFDMA Femtocell Networks With QoS Guarantees

Recently, operators have resorted to femtocell networks to enhance indoor coverage and increase system capacity. Nevertheless, to successfully deploy such solution, efficient resource-allocation algorithms and interference mitigation techniques should be deployed. The new applications delivered by operators require large amounts of network bandwidth. Although, some customers may want to pay more in exchange for a better quality of service (QoS), some others need fewer resources and can be charged accordingly. Hence, we consider an orthogonal frequency-division multiple-access (OFDMA) femtocell network serving both QoS-constrained high-priority (HP) and best-effort (BE) users. Our objective is to satisfy a maximum number of HP users while serving BE users as well as possible. This multiobjective optimization problem is NP-hard. For this aim, we propose in this paper a new resource-allocation and admission control algorithm, which is called QoS-based femtocell resource allocation (Q-FCRA), based on clustering and taking into account QoS requirements. We show through extensive network simulations that our proposal outperforms two state-of-the-art schemes [centralized-dynamic frequency planning (C-DFP) and distributed random access (DRA)] and our previous proposal, i.e., femtocell resource allocation (FCRA), in both low- and high-density networks. The results concern the throughput satisfaction rate, spectrum spatial reuse, the rate of rejected users, fairness, and computation and convergence time.

A comprehensive analysis of mobility management in MPLS-based wireless access networks

Efficient mobility management is one of the major challenges for next-generation mobile systems. Indeed, a mobile node (MN) within an access network may cause excessive signaling traffic and service disruption due to frequent handoffs. The two latter effects need to be minimized to support quality-of-service (QoS) requirements of emerging multimedia applications. In this perspective, we propose in this paper a new mobility management scheme designed to track host mobility efficiently so as to minimize both handoff latency and signaling cost. Building on and enhancing Mobile IP and taking advantage of MPLS traffic engineering capability, three mechanisms (FH-, FC- and MFC-Micro Mobile MPLS) are introduced. In order to assess the efficiency of our proposals, all protocols are compared. To achieve this, we develop analytical models to evaluate the signaling cost and link usage for both two-dimensional and one-dimensional mobility models. Additional mathematical models are also provided to derive handoff latency and packet loss rate. Numerical and simulation results show that the proposed mechanisms can significantly reduce the registration updates cost and provide low handoff latency and packet loss rate under various scenarios.

QoS-based power control and resource allocation in OFDMA femtocell networks

This paper proposes a new joint power control and resource allocation algorithm in OFDMA femtocell networks. We consider both QoS constrained high-priority (HP) and best-effort (BE) users having different types of application and bandwidth requirements. Our objective is to minimize the transmit power of each femtocell, while satisfying a maximum number of HP users and serving BE users as well as possible. This optimization problem is multi-objective NP-hard. Hence, we propose a new scheme based on clustering and taking into account QoS requirements of users. We show by extensive network simulation results that our proposal outperforms three state of the art schemes (Centralized-Dynamic Frequency Planning, C-DFP, Distributed Random Access, DRA and Distributed Resource Allocation with Power Minimization, DRAPM as well as our previous proposal, FCRA, in both low and high density networks. The results concern the rate of rejected users, the throughput satisfaction rate, the spectrum spatial reuse, fairness, as well as computation time.

Proposal and Analysis of Region-Based Location Service Management Protocol for VANETs

One of the major challenges for vehicular ad hoc networks (VANETs) is related to efficient location management issue. In this paper, we propose a new region-based location service management protocol (RLSMP) that uses mobility patterns as means to synthesize vehicle movement and thus can be used in VANETs applications. One of the key distinguishing features of our solution from existing literature is its scalability since it uses message aggregation in both updating and querying, and promises locality awareness as well as minimum signaling overhead. To evaluate the efficiency of our proposal, we compare our scheme with existing solutions using both analytical and simulation approaches. To achieve this, we develop analytical models to evaluate the location updates cost. Numerical and simulation results show that our protocol scales better than existing schemes, when increasing the size of VANET which enhances the feasibility of such large scale ad hoc networks.

Online flow-based energy efficient management in Wireless Mesh Networks

The last few years have witnessed an increase in energy consumption in Information and Communication Technology (ICT). Naturally, energy efficient solutions are becoming crucial for both local and wireless access networks. In this paper, we propose a new framework to support energy efficient management in Wireless Mesh Networks (WMNs). A key distinguishing feature of our solution is its online flow-based routing approach since existing flows are dynamically consolidated or even re-routed at fixed intervals according to live arrival and departure of mesh clients. The proposed solution is compliant with emerging Software Defined Networking (SDN) paradigm since it relies on a central controller to monitor and manage the network. To achieve this, we first formulate the problem as an integer linear program (ILP). As this problem is known to be NP-hard, we then propose a simple yet efficient Ant Colony-based approach to solve the formulated ILP problem. Through extensive simulations, we show that our proposed approach is able to achieve significant gains in terms of energy consumption, compared to conventional routing solutions such as the Shortest Path (SP) routing, the Minimum link Residual Capacity routing metric (MRC) and the load balancing (LB) scheme. Specifically, we show that our approach reduces the energy consumption by up to 13%, 20%, and 52%, compared to MRC, SP and LB, respectively, while achieving the required QoS.