Haidar Safa

COACS: A Cooperative and Adaptive Caching System for MANETs

This paper introduces a cooperation-based database caching system for Mobile Ad Hoc Networks (MANETs). The heart of the system is the nodes that cache submitted queries. The queries are used as indices to data cached in nodes that previously requested them. We discuss how the system is formed and how requested data is found if cached, or retrieved from the external database and then cached. Analysis is performed and expressions are derived for the different parameters, including upper and lower bounds for the number of query caching nodes as well as the average load they experience, generated network traffic, node bandwidth consumption, and other performance-related measures. Simulations with the ns-2 software were used to study the performance of the system in terms of average delay and hit ratio, and to compare it with the performance of two other caching schemes for MANETs, namely CachePath and CacheData. The results demonstrate the effectiveness of the proposed system in terms of achieved hit ratio and low delay.

A cluster-based trust-aware routing protocol for mobile ad hoc networks

Routing protocols are the binding force in mobile ad hoc network (MANETs) since they facilitate communication beyond the wireless transmission range of the nodes. However, the infrastructure-less, pervasive, and distributed nature of MANETs renders them vulnerable to security threats. In this paper, we propose a novel cluster-based trust-aware routing protocol (CBTRP) for MANETs to protect forwarded packets from intermediary malicious nodes. The proposed protocol organizes the network into one-hop disjoint clusters then elects the most qualified and trustworthy nodes to play the role of cluster-heads that are responsible for handling all the routing activities. The proposed CBTRP continuously ensures the trustworthiness of cluster-heads by replacing them as soon as they become malicious and can dynamically update the packet path to avoid malicious routes. We have implemented and simulated the proposed protocol then evaluated its performance compared to the clustered based routing protocol (CBRP) as well as the 2ACK approach. Comparisons and analysis have shown the effectiveness of our proposed scheme.

Survey of Security Issues in Cognitive Radio Networks

Cognitive Radio (CR) is a novel technology that promises to solve the spectrum shortage problem by allowing secondary users to coexist with primary users without causing interference to their communication. Although the operational aspects of CR are being explored vigorously, its security aspects have gained little attention. In this paper, a brief overview of the CR technology is provided followed by a detailed analysis of the security attacks targeting Cognitive Radio Networks (CRNs) along with the corresponding mitigation techniques. We categorize the attacks with respect to the layer they target starting from the physical layer and moving up to the transport layer. An evaluation of the suggested countermeasures is presented along with other solutions and augmentations to achieve a secure and trusted CRN.

New Scheduling Architecture for IEEE 802.16 Wireless Metropolitan Area Network

IEEE 802.16 standard defines the specifications for emerging WiMAX networks. It did not however define the scheduling algorithms that determine the uplink and downlink bandwidth allocation. This paper proposes a preemptive deficit fair priority queue (PDFPQ) scheduling architecture for QoS management for the IEEE 802.16 standard. The proposed scheduling architecture is an extension of the DFPQ scheduling technique found in the literature. It enhances the QoS requirements of real time polling service (rtPS) flow class, and improves its delay and throughput. Compared to DFPQ, preliminary results show that a significant rtPS delay reduction and throughput increase can be realized with our new scheduling technique.

LTE uplink scheduling algorithms: Performance and challenges

LTE uses the SC-FDMA radio access technology for its uplink transmission. As a result, resources assigned to the same user must be contiguous in the frequency domain. Several uplink scheduling algorithms were proposed in the literature to fit that constraint. These algorithms take as input a matrix which is used by the Packet Scheduler for an efficient resource allocation. The performance of these algorithms is affected by the paradigm that is used to construct that matrix. Two main paradigms exist in the literature, channel dependent and proportional fairness. In this paper, we evaluate the performance of some LTE uplink scheduling algorithms for both channel dependent and proportional fairness paradigms. As a result, we identify the weaknesses of the existing paradigms and define some challenges for future enhancement.

A novel localization algorithm for large scale wireless sensor networks

Abstract Localization has been a major challenge in wireless sensor networks. The data reported from a sensor is only useful when the position of that sensor is found. In this paper, we propose a new algorithm that accurately localizes sensors while minimizing their power consumption and memory requirements. The proposed algorithm splits the task of localization between sensor nodes and the base station (i.e., sink) and does not necessitate the presence of many anchor nodes (nodes with preconfigured positions). It recommends placing the anchors in a circle or a semi-circle around the perimeter of the WSN. Not only this placement strategy leads to more accurate localization, but it is also very convenient for WSNs used for environment monitoring, military surveillance, or tracking applications. The proposed approach can also be tailored to route the sensed data to the base station which alleviates the sensors from the overhead incurred in establishing routes to the base station. The performance of the proposed approach was evaluated and compared to other peer algorithms using the network simulator (NS-2). Results show that significant enhancement is obtained with the proposed algorithm when measuring metrics such as energy and localization error while varying other simulation parameters such as the number of sensors and the area size.

A hybrid honeypot framework for improving intrusion detection systems in protecting organizational networks

This paper proposes a hybrid and adaptable honeypot-based approach that improves the currently deployed IDSs for protecting networks from intruders. The main idea is to deploy low-interaction honeypots that act as emulators of services and operating systems and have them direct malicious traffic to high-interaction honeypots, where hackers engage with real services. The setup permits for recording and analyzing the intruders activities and using the results to take administrative actions toward protecting the network. The paper describes the basic components, design, operation, implementation and deployment of the proposed approach, and presents several performance and load testing scenarios. Implementation and performance plus load testing show the adaptability of the proposed approach and its effectiveness in reducing the probability of attacks on production computers.

Adaptive approach for QoS support in IEEE 802.11e wireless LAN

the IEEE 802.11e standard has been introduced recently for providing quality of service (QoS) capabilities in the emerging wireless local area networks. This standard introduces a contention window based enhanced distributed channel access (EDCA) technique that provides a prioritized traffic to guarantee the minimum bandwidth needed for time critical applications. However, the EDCA technique resets statically the contention window of the mobile station after each successful transmission. This static behavior does not adapt to the network state hence reduces the network usage and results in bad performance and poor link utilization whenever the demand for link utilization increases. This paper proposes a new adaptive differentiation technique for IEEE 802.11e wireless local area networks that takes into account the network state before resetting the contention window. The performance of the proposed technique is evaluated compared to the original differentiation techniques of the IEEE 802.11a and IEEE 802.11e standards. Preliminary results show that the proposed adaptive technique enhances the channel utilization and increases throughput.

PHAODV: Power aware heterogeneous routing protocol for MANETs

Abstract Devices in mobile ad hoc networks (MANETs) have limited power resources and may be equipped with different transmission technologies. These characteristics make MANET traditional routing protocols inconvenient in a heterogeneous environment. Hence, the need for designing routing protocols that support interoperability between heterogeneous nodes and efficiently uses the available resources. In this paper, we propose a power aware routing protocol for a MANET formed of heterogeneous nodes. The proposed approach takes into consideration the battery status of nodes when building the routing table; in addition, in case of the existence of multiple routes between two nodes, the route that consumes least power is selected and the nodes falling on this route will be added to the routing table. Also, the proposed approach ensures fair distribution of routing load among the nodes and avoids exhausting nodes that are falling on optimal routes across the network, thus providing better connectivity and extending the network lifetime. We implemented the protocol as an extension to JiST/SWANS network simulator, and compared its performance to other heterogeneous and power aware routing protocols found in the literature.

A product-line architecture for web service-based visual composition of web applications

A web service-based web application (WSbWA) is a collection of web services or reusable proven software parts that can be discovered and invoked using standard Internet protocols. The use of these web services in the development process of WSbWAs can help overcome many problems of software use, deployment and evolution. Although the cost-effective software engineering of WSbWAs is potentially a very rewarding area, not much work has been done to accomplish short time to market conditions by viewing and dealing with WSbWAs as software products that can be derived from a common infrastructure and assets with a captured specific abstraction in the domain. Both Product Line Engineering (PLE) and Agile Methods (AMs), albeit with different philosophies, are software engineering approaches that can significantly shorten the time to market and increase the quality of products. Using the PLE approach we built, at the domain engineering level, a WSbWA-specific lightweight product-line architecture and combined it, at the application engineering level, with an Agile Method that uses a domain-specific visual language with direct manipulation and extraction capabilities of web services to perform customization and calibration of a product or WSBWA for a specific customer. To assess the effectiveness of our approach we designed and implemented a tool that we used to investigate the return on investment of the activities related to PLE and AMs. Details of our proposed approach, the related tool developed, and the experimental study performed are presented in this article together with a discussion of planned directions of future work.