Nidal Nasser

Handoffs in fourth generation heterogeneous networks

As mobile wireless networks increase in popularity and pervasiveness, we are faced with the challenge of combining a diverse number of wireless networks. The fourth generation of wireless communications is expected to integrate a potentially large number of heterogeneous wireless technologies in what could be considered a huge step forward toward universal seamless access. One of the main challenges for seamless mobility is the availability of reliable horizontal (intrasystem) and vertical (intersystem) handoff schemes. Efficient handoff schemes enhance quality of service and provide flawless mobility. This article presents different and novel aspects of handoff and discusses handoff related issues of fourth generation systems. Desirable handoff features are presented. Handoff decisions, radio link transfer, and channel assignment are described as stages of the complete handoff process. A vertical handoff decision function, which enables devices to assign weights to different network parameters, is also presented

Enhanced Intrusion Detection System for Discovering Malicious Nodes in Mobile Ad Hoc Networks

As mobile wireless ad hoc networks have different characteristics from wired networks and even from standard wireless networks, there are new challenges related to security issues that need to be addressed. Many intrusion detection systems have been proposed and most of them are tightly related to routing protocols, such as Watchdog/Pathrater and Routeguard. These solutions include two parts: intrusion detection (Watchdog) and response (Pathrater and Routeguard). Watchdog resides in each node and is based on overhearing. Through overhearing, each node can detect the malicious action of its neighbors and report other nodes. However, if the node that is overhearing and reporting itself is malicious, then it can cause serious impact on network performance. In this paper, we overcome the weakness of Watchdog and introduce our intrusion detection system called ExWatchdog. The main feature of the proposed system is its ability to discover malicious nodes which can partition the network by falsely reporting other nodes as misbehaving and then proceeds to protect the network. Simulation results show that our system decrease the overhead greatly, though it does not increase the throughput obviously.

SEEM: Secure and energy-efficient multipath routing protocol for wireless sensor networks

A Wireless Sensor Network (WSN) is a collection of wireless sensor nodes forming a temporary network without the aid of any established infrastructure or centralized administration. In such an environment, due to the limited range of each nodes wireless transmissions, it may be necessary for one sensor node to ask for the aid of other sensor nodes in forwarding a packet to its destination, usually the base station. One important issue when designing wireless sensor network is the routing protocol that makes the best use of the severely limited resource presented by WSN, especially the energy limitation. Another import factor required attention from researchers is providing as much security to the application as possible. The proposed routing protocols in the literature focus either only on increasing lifetime of network or only on addressing security issues while consuming much power. None of them combine solutions to the two challenges. In this paper, we propose a new routing protocol called SEEM: Secure and Energy-Efficient multipath Routing protocol. SEEM uses multipath alternately as the path for communicating between two nodes thus prolongs the lifetime of the network. On the other hand, SEEM is effectively resistive to some specific attacks that have the character of pulling all traffic through the malicious nodes by advertising an attractive route to the destination. The performance of our protocol is compared to the Directed Diffusion protocol. Simulation results show that our protocol surpasses the Directed Diffusion protocol in terms of throughput, control overhead and network lifetime.

Tramcar: A Context-Aware Cross-Layer Architecture for Next Generation Heterogeneous Wireless Networks

Major research challenges in the next generation (4G) of wireless networks include the provisioning of worldwide seamless mobility across heterogeneous wireless networks, the improvement of end-to-end Quality of Service (QoS) and enabling users to specify their personal preferences. Under this motivation, we design a novel cross-layer architecture that provides context-awareness, smart handoff and mobility control in heterogeneous wireless IP networks. We develop a Transport and Application Layer Architecture for vertical Mobility with Context-awareness (Tramcar). Tramcar is tailored for a variety of different network technologies with different characteristics and has the ability of adapting to changing environment conditions and unpredictable background traffic. Furthermore, Tramcar allows users to identify and prioritize their preferences. Simulation results demonstrate that Tramcar increases user satisfaction levels and network throughput under rough network conditions and reduces overall handoff latencies.

Comparison of Clustering Algorithms and Protocols for Wireless Sensor Networks

One of the mechanisms used to enlarge the lifetime of wireless sensor networks (WSN) and to provide more efficient functioning procedures is clustering. By assuming roles within a cluster hierarchy, the nodes in a WSN can control the activities they performed and therefore, reduce their energy consumption. However, the election of when to act as a data provider (saving energy) and when to act as a gateway (cluster head) between the nodes and the base station is not a simple task. To make this decision it is necessary to take into account aspects like power level signal, transmission schedules and networking functioning (proactive or reactive). In this paper we study some basic concepts related to the clustering process in WSN and presenting a comparison survey between different clustering protocols

Generic vertical handoff decision function for heterogeneous wireless

As mobile wireless networks increase in popularity and pervasiveness, we are facing the challenge of integration of diverse wireless networks such as WLANs and WWANs. Consequently, it is becoming progressively more important to arrive at a vertical handoff solution where users can move among various types of networks efficiently and seamlessly. The ability to remain connected as a mobile device roams across different types of networks still remains an unachieved objective. Frequently, just choosing the best network to connect to, is a challenging problem due to the large number of network characteristics that need to be considered. Identifying these decision factors is therefore one of the principal objectives for seamless mobility. In this paper, we discuss the different factors and metric qualities that give an indication of whether or not a handoff is needed. We then describe a vertical handoff decision function, VHDF, which enables devices to assign weights to different network factors such as monetary cost, quality of service, power requirements, personal preference, etc.

Middleware Vertical Handoff Manager: A Neural Network-Based Solution

Major research challenges in the next generation of wireless networks include the provisioning of worldwide seamless mobility across heterogeneous wireless networks, the improvement of end-to-end quality of service (QoS), supporting high data rates over wide area and enabling users to specify their personal preferences. The integration and interoperability of this multitude of available networks will lead to the emergence of the fourth generation (4G) of wireless technologies. 4G wireless technologies have the potential to provide these features and many more, which at the end will change the way we use mobile devices and provide a wide variety of new applications. However, such technology does not come without its challenges. One of these challenges is the users ability to control and manage handoffs across heterogeneous wireless networks. This paper proposes a solution to this problem using artificial neural networks (ANNs). The proposed method is capable of distinguishing the best existing wireless network that matches predefined user preferences set on a mobile device when performing a vertical handoff. The overall performance of the proposed method shows 87.0 % success rate in finding the best available wireless network. To test for the robustness and effectiveness of the neural network algorithm, some of the features were removed from the training set and results showed a significant impact on the overall performance of the system. Hence, managing vertical handoffs through user preferences can be significantly affected with the selection of features used to provide the closest match of the available wireless networks.

Cluster-based routing protocol for mobile sensor networks

Mobility in wireless sensor networks has attracted a lot of attention in the recent years [6] and has introduced unique challenges in aspects like resource management, coverage, routing protocols, security, etc. The next evolutionary step for sensor networks is to handle the mobility effect in all its forms. In this paper, we propose a mobility-aware routing protocol, using zone-base information and a cluster-like communication between nodes. The routing protocol has two different stages: Route Creation and Route Preservation. Route creation is used to discover a route from source to destination. Route preservation is used to repair the route when it is defective.

Dynamic QoS-Based Bandwidth Allocation Framework for Broadband Wireless Networks

Broadband wireless communication systems, namely, Worldwide Interoperability for Microwave Access (WiMAX) and Long-Term Evolution (LTE), promise to revolutionize the mobile users wireless experience by offering many of the services and features promised by fourth-generation (4G) wireless systems, such as supporting multimedia services with high data rates and wide coverage area, as well as all-Internet Protocol (IP) with security and quality-of-service (QoS) support. These systems, however, require proficient radio resource management (RRM) schemes to provide the aforementioned features they promise. In this paper, we propose a new framework, which is called dynamic QoS-based bandwidth allocation (DQBA), to support heterogeneous traffic with different QoS requirements in WiMAX networks. The DQBA framework operates as such; it dynamically changes the bandwidth allocation (BA) for ongoing and new arrival connections based on traffic characteristics and service demand. The DQBA aims at maximizing the system capacity by efficiently utilizing its resources and by being fair, practical, and in compliance with the IEEE 802.16 standard specifications. To achieve its objectives, DQBA employs a flexible architecture that combines the following related components: 1) a two-level packet scheduler scheme; 2) an efficient call admission control policy; and 3) a dynamic BA mechanism. Simulation results and comparisons with existing schemes show the effectiveness and strengths of the DQBA framework in delivering promising QoS and being fair to all classes of services in a WiMAX network.

Reliable location-aware routing protocol for mobile wireless sensor network

Designing energy efficient and reliable routing protocols for mobility centric applications of wireless sensor network (WSN) such as wildlife monitoring, battlefield surveillance and health monitoring is a great challenge since topology of the network changes frequently. Existing cluster-based mobile routing protocols such as LEACH-Mobile, LEACH-Mobile-Enhanced and CBR-Mobile consider only the energy efficiency of the sensor nodes. However, reliability of routing protocols by incorporating fault tolerance scheme is significantly important to identify the failure of data link and sensor nodes and recover the transmission path. Most existing mobile routing protocols are not designed as fault tolerant. These protocols allocate extra timeslots using time division multiple access (TDMA) scheme to accommodate nodes that enter a cluster because of mobility and thus, increases end-to-end delay. Moreover, existing mobile routing protocols are not location aware and assume that sensor nodes know their coordinates. In this study the authors, we propose a location-aware and fault tolerant clustering protocol for mobile WSN (LFCP-MWSN) that is not only energy efficient but also reliable. LFCP-MWSN also incorporates a simple range free approach to localise sensor nodes during cluster formation and every time a sensor moves into another cluster. Simulation results show that LFCP-MWSN protocol has about 25-30% less network energy consumptions and slightly less end-to-end data transmission delay than the existing LEACH-Mobile and LEACH-Mobile-Enhanced protocols.