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.

ENVI: Elastic resource flexing for Network function Virtualization.

Abstract: Dynamic and elastic resource allocation to Virtual Network Functions (VNFs) in accordance with varying workloads is a must for realizing promised reductions in capital and operational expenses in Network Functions Virtualization (NFV). However, workload heterogeneity and complex relationships between resources allocated to a VNF and the resulting capacity makes elastic resource flexing a challenging task. We propose an NFV resource flexing system, ENVI, that uses a combination of VNF-level features and infrastructure-level features to construct a machine-learning-based decision engine for detecting resource flexing events. ENVI also extracts the dependence relationship among VNFs in deployed Service Function Chains (SFCs) to carefully plan the sequence of resource flexing steps upon scaling detection. We present preliminary results for the accuracy of ENVI’s resource flexing decision engine with two different VNFs, namely, the caching proxy Squid and the intrusion detection system Suricata. Our preliminary results show that using a combination of features to train a neural network model is a promising approach for scaling detection.

TCP selective acknowledgments and UBR drop policies to improve ATM-UBR performance over terrestrial and satellite networks

Abstract: We study the performance of selective acknowledgements (SACK) with TCP over the ATM-UBR service category. We examine various unspecified bit rate (UBR) drop policies, TCP mechanisms and network configurations to recommend optimal parameters for TCP over UBR. We discuss various TCP congestion control mechanisms compare their performance for LANs and WANs. We describe the effect of satellite delays on TCP performance over UBR and present simulation results for LANs, WANs and satellite networks. SACK TCP improves the performance of TCP over UBR, especially for large delay networks. Intelligent drop policies at the switches are an important factor for good performance in local area networks.

Optimal Sleep/Wake Scheduling for Time-Synchronized Sensor Networks with QoS Guarantees

Abstract: We study sleep/wake scheduling for low-duty cycle sensor networks.1 Our work is different from previous work in that we explicitly consider the effect of the synchronization error. We study a widely used synchronization scheme and show that the synchronization error is non-negligible, and using a conservative guard time is energy wasteful. Hence, we formulate an optimization problem to minimize the expected energy consumption, with the constraint that the message capture probability should be no less than a threshold. We find that the problem is non-convex, hence cannot be solved by conventional convex optimization techniques. By investigating the unique structure of the problem, we transform the problem into a convex equivalent, and solve it using an efficient search method. Simulations show that our scheme significantly outperforms schemes that do not intelligently consider the synchronization error. We also remove the assumption that the capture probability threshold is given, and study how to decide it to meet the Quality of Services (QoS) requirements of the application.

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.