Mohamed N. El-Derini

GAC: Energy-Efficient Hybrid GPS-Accelerometer-Compass GSM Localization

Adding location to the available information enables a new category of applications. With the constrained battery on cell phones, energy-efficient localization becomes an important challenge. In this paper we introduce a low-energy calibration- free localization scheme based on the available internal sensors in many of todays phones. We start by energy profiling the different sensors that can be used for localization. Based on that, we propose GAC: a hybrid GPS/accelerometer/compass scheme that depends mainly on using the low-energy accelerometer and compass sensors and uses the GPS infrequently for synchronization. We implemented our system on Android-enabled cell phones and evaluated it in both highways and intra-city driving environments. Our results show that the proposed hybrid scheme has an exponential saving in energy, with a linear loss in accuracy compared to the GPS accuracy. We also evaluate the effect of the different parameters on the energy-accuracy tradeoff.

Defending against energy efficient link layer jamming denial of service attack in wireless sensor networks

Wireless Sensor Networks (WSNs) are vulnerable to attacks due to their limited software and hardware capabilities. Energy efficient link layer jamming attacks have proven to be a real threat to wireless sensor networks. This type of attacks is able to prevent network communication for relatively long periods as it does not spend a lot of power while jamming. This paper proposes and evaluates two modifications to the Lightweight Medium Access Control (LMAC) [3] protocol. The first is Data Packet Separation Slot Size Randomization (DS-SSR); the second is Round Robin (RR) slot size assignment. The paper shows that (DS-SSR) can increase the WSN resistance against the Energy efficient denial of service link layer jamming attacks. The paper also shows that employing RR slightly eliminates the negative impact on the network throughput when using countermeasures against energy efficient jamming. Two measures are used to evaluate the resistance of the proposed protocol against the attack: lifetime advantage and censorship rate. Experimental results show that about 8 % reduction of the attacker lifetime advantage can be achieved with DS-SSR LMAC compared to other countermeasure. Furthermore, results show that the censorship rate of our proposed protocol was similar to the other countermeasures.

MSR: A multipath secure reliable routing protocol for WSNs

Many routing protocols have been proposed for wireless sensor networks (WSNs). However, only few of them addressed secure routing. This work contributes in solving secure and reliable routing problems by presenting a secure and reliable multipath routing protocol (MSR) for WSNs. MSR consists of three key components: on-demand multipath routing, enhanced passive acknowledgment, and erasure coding. On-demand routing enhances the security and reliability of the routing protocol while enhanced passive acknowledgment is used to both enhance the security of the protocol and reduce its overhead. In addition, erasure coding is further used to increase the protocol security and reliability. We present the details of the protocol along with a study of major security attacks in WSNs and determines the level of MSRs resistance against these attacks. The evaluation of the proposed protocol using the NS2 simulator shows that it can significantly enhance the security of WSNs under different attacker models.

Structure and performance evaluation of a replicated banyan network based ATM switch

Banyan networks are commonly used as interconnection structures in ATM switches. This paper is concerned with the replication technique which was applied to the standard banyan networks. We apply this technique to the plane interconnected parallel network (PIPN) which is a switch introduced previously as a better banyan-based interconnection structure. The normalized throughput of unbuffered and buffered replicated PIPN is analyzed analytically under uniform traffic model. We apply the simulation technique to verify the analytical results under the uniform traffic model and to study the performance of different heterogeneous traffic models. The performance is shown to increase significantly when the replicated PIPN is used which supports the idea of using this switch as a new high-performance ATM switch.

Heuristics for rerouting of label switched paths in MPLS based IP networks

The growth of the Internet has caused the development of new protocols that enable IP networks to be engineered efficiently. One such protocol, multiprotocol label switching (MPLS) enables IP networks with quality of service to be traffic engineered well. Rerouting of label switched paths (LSP) is caused due to link or node failure or recovery, connection admission or load balancing. In this paper, we deal with the problem of reroute sequence planning of LSPs. We introduce a number of new heuristic approaches, and refinements into the existing ones, which are evaluated by simulation using data from real network topologies. Results show that two of the new heuristic approaches behave better than the existing ones and improve the performance.

A dynamic uplink scheduling scheme for WiMAX networks

Over the past few years, there has been a rapid growth of new services such as online video games, video conferences, and multimedia services to end users. WiMAX is an emerging technology for next generation wireless networks which supports a large number of users. To achieve Quality of Service (QoS) requirements, an efficient and reliable scheduling algorithm is urgently needed. Among a large number of the proposed approaches in the literature, a variably weighted round robin scheduling algorithm (VWRR) has been proven to provide the best performance in an IP backbone network with no attempts on WiMAX networks. This paper proposes a dynamic uplink scheduling algorithm for WiMAX networks based on VWRR to allocate the bandwidth to users to maximize the throughput and ensure the constraints of delay, jitter, and load. A comparative study between the proposed scheduling algorithm and the two most famous scheduling algorithms: weighted round robin algorithm (WRR) and modified deficit round robin algorithm (MDRR) over WiMAX networks, is presented. Simulation results obtained using OPNET reveal that the proposed algorithm has a superior performance compared with WRR with respect to throughput, delay, jitter, and load. Additionally, the proposed scheduling algorithm is shown to provide an excellent level of reliability and scalability when increasing the number of served subscriber stations.

Using co-operating agents for partial results protection in mobile agent paradigm

Abstract E-commerce can be implemented using mobile agent paradigm which is considered as an extension to distributed system approach. Mobile agent paradigm is an approach where a source node generates a software program (mobile agent) to be released through nodes (vendors); collecting offers regarding the application’s criteria and finally returning back to the source. According to the mobility of mobile agent, it is vulnerable to various penetrations of malicious nodes; a well-known vulnerability is the truncation attack. This paper proposes a new protocol (Co-T1) which leverages the protection of collected offers and restoring hacked information of mobile agent without recycling it. The proposed protocol relies on the negotiation of co-operating mobile agents for satisfying the integrity of collected offers, where the source node releases the co-operating agents that consist of two types of agents; one agent (bid-agent) to collect offers and uses the notion of publicly verified chained signature [2], and the other agent (monitoring-agent) to generate a one time public/private key pair that is applied for signature and to restore hacked information of the bid-agent.

Performance Comparison of CBT and PIM Multicast Routing Protocols over MPLS Networks

Multi-protocol label switching (MPLS) is a promising cutting-edge technology for advanced forwarding of IP packets. Better performance of multicast routing in large-scale networks is expected when it is implemented over MPLS. In this paper, we simulate core-based tree (CBT) multicast routing protocol over MPLS-based networks using NS2, and compare its performance with protocol-independent multicast-sparse mode (PIM-SM). Simulations are performed for different network topologies with various group sizes using a modified version of the MPLS Network Simulator (MNS). Results reveal that as the number of source nodes increases CBT gives better performance than PIM-SM in terms of routing table size, join time, and total hop count. On the other hand, PIM-SM has less end-to-end delay than CBT

A cloudlet architecture using mobile devices

With the increasing ubiquity of mobile devices with computational capabilities comparable to many personal computers, they became the dominant personal computing devices nowadays. However, mobile devices still suffer short battery life and many of them are not capable of running rich-media, data-intensive and compute-intensive applications. Offloading to the cloud is a promising solution, however, long WAN latencies and the large amount of consumed energy using cellular data connectivity guided researchers to bring cloud capabilities to LANs to form cloudlets. On the other hand, in the last few years, there has been a new trend of making use of the computing resources of the vast amount of mobile devices available everywhere. In this paper, we introduce DroidCloudlet as a cloudlet architecture that is based on mobile devices. DroidCloudlet is empowered by available resource-rich mobile devices, while resource-constrained mobile devices can offload compute-intensive workloads to them. Offloading is carried out dynamically at runtime according to specific policies that target reducing execution time or saving energy. We also propose a lightweight cost model that is used to make offloading decision based on both context parameters and historical offloading performance results. To make use of all reachable mobile devices, we introduce a multilevel architecture in which offloading can bubble recursively from local cloudlet servers to other remote servers in any reachable cloudlet. For evaluation, we have built a prototype of the proposed architecture and performance results show that it succeeded to save up to 72% of execution time and 98% of consumed energy.

Behavior of task scheduling algorithms with probabilistic module execution times

Static task scheduling in distributed computing systems is a very complex problem and known to be NP-hard. This problem is even harder when the module execution times become probabilistic. In this paper we study the effect of probabilistic module execution times on the performance of task-scheduling algorithms. We show that in static task scheduling, for probabilistic module execution times, and in the existence of some factors there is no need to use an expensive task-scheduling algorithm. Given any two static task-scheduling algorithms that use deterministic module execution times in assigning task modules to the distributed system, the performance of these two algorithms will not remain the same when these module execution times become probabilistic rather than deterministic. We also study the effects of some factors an our results.