Sonia Fahmy

Bio: Sonia Fahmy is an academic researcher from Purdue University. The author has contributed to research in topics: Asynchronous Transfer Mode & Wireless sensor network. The author has an hindex of 39, co-authored 217 publications receiving 11177 citations. Previous affiliations of Sonia Fahmy include Ohio State University & Hewlett-Packard.

Design and analysis of queue control functions for explicit rate switch schemes

Abstract: The ABR rate allocation schemes can achieve high link utilizations by maintaining non-zero (small) queues in the steady state, and draining queues when the sources do not have data to send. The queue length (and queuing delays) can be controlled if part of the available bandwidth is used for draining queues in the event of queue build up. A simple threshold function can allocate such bandwidth to drain queues. Better control of the queues, and hence delay, can be achieved using more sophisticated queue control functions. We study the design and analysis of several such queue control functions: the step, linear, hyperbolic and inverse hyperbolic functions. Analytical explanation and simulation results consistent with analysis are presented. From the study, we conclude that the inverse hyperbolic is the best queue control function. To reduce complexity, the linear function can be used since it performs satisfactorily in most cases.

Energy-efficient provenance transmission in large-scale wireless sensor networks

Abstract: Large-scale sensor-based decision support systems are being widely deployed. Assessing the trustworthiness of sensor data and the owners of this data is critical for quality assurance of decision making in these systems. Trust evaluation frameworks use data provenance along with the sensed data values to compute the trustworthiness of each data item. However, in a sizeable multi-hop sensor network, provenance information requires a large and variable number of bits in each packet, which, in turn, results in high energy dissipation with extended period of radio communication, making trust systems unusable. We propose an energy-efficient provenance transmission and construction scheme, which we refer to as Probabilistic Provenance Flow (PPF). To the best of our knowledge, ours is the first approach to make the Probabilistic Packet Marking (PPM) approach of IP traceback feasible for sensor networks. We propose two bit-efficient complementary provenance encoding and construction methods, and combine them to handle topological changes in the network. Our TOSSIM simulations demonstrate that PPF requires at least 33% fewer packets and consumes 30% less energy than PPM-based approaches to construct provenance, yet still provides high accuracy in trust score calculation. 1

Automating DDoS experimentation

Abstract: While the DETER testbed provides a safe environment and basic tools for security experimentation, researchers face a significant challenge in assembling the testbed pieces and tools into realistic and complete experimental scenarios. In this paper, we describe our work on automating experimentation for distributed denial-of-service attacks. We developed the following automation tools: (1) the Experimenter's Workbench that provides a graphical user interface, tools for topology, traffic and monitoring setup and tools for statistics collection, visualization and processing, (2) a DDoS benchmark suite that contains a set of diverse and comprehensive attack scenarios, (3) the Experiment Generator that combines chosen AS-level and edge-level topologies, legitimate traffic and a set of attacks into DETER-compatible scripts. Jointly, these tools facilitate easy experimentation even for novice users.

Performance of TCP over ABR with long-range dependent VBR background traffic over terrestrial and satellite ATM networks

Abstract: Compressed video is well known to be self-similar in nature. We model VBR carrying long-range dependent, multiplexed MPEG-2 video sources traffic. The actual traffic for the model is generated using fast-Fourier transform of the fractional Gaussian noise sequence. Our model of compressed video sources bears similarity to an MPEG-2 transport stream carrying video, i.e., it is long-range dependent and generates traffic in a piecewise constant bit rate manner. We study, the effect of such VBR traffic on ABR carrying TCP traffic. The effect of such VBR traffic is that the ABR capacity is highly variant. We find that a switch algorithm like ERICA+ can tolerate this variance in ABR capacity while maintaining high throughput and low delay. We present simulation results for terrestrial and satellite configurations.

HEED: a hybrid, energy-efficient, distributed clustering approach for ad hoc sensor networks

Abstract: Topology control in a sensor network balances load on sensor nodes and increases network scalability and lifetime. Clustering sensor nodes is an effective topology control approach. We propose a novel distributed clustering approach for long-lived ad hoc sensor networks. Our proposed approach does not make any assumptions about the presence of infrastructure or about node capabilities, other than the availability of multiple power levels in sensor nodes. We present a protocol, HEED (Hybrid Energy-Efficient Distributed clustering), that periodically selects cluster heads according to a hybrid of the node residual energy and a secondary parameter, such as node proximity to its neighbors or node degree. HEED terminates in O(1) iterations, incurs low message overhead, and achieves fairly uniform cluster head distribution across the network. We prove that, with appropriate bounds on node density and intracluster and intercluster transmission ranges, HEED can asymptotically almost surely guarantee connectivity of clustered networks. Simulation results demonstrate that our proposed approach is effective in prolonging the network lifetime and supporting scalable data aggregation.

Topology Control in Wireless Ad Hoc and Sensor Networks

Abstract: Topology Control (TC) is one of the most important techniques used in wireless ad hoc and sensor networks to reduce energy consumption (which is essential to extend the network operational time) and radio interference (with a positive effect on the network traffic carrying capacity). The goal of this technique is to control the topology of the graph representing the communication links between network nodes with the purpose of maintaining some global graph property (e.g., connectivity), while reducing energy consumption and/or interference that are strictly related to the nodes' transmitting range. In this article, we state several problems related to topology control in wireless ad hoc and sensor networks, and we survey state-of-the-art solutions which have been proposed to tackle them. We also outline several directions for further research which we hope will motivate researchers to undertake additional studies in this field.