Affan A. Syed

T-Lohi: A New Class of MAC Protocols for Underwater Acoustic Sensor Networks

This paper introduces T-Lohi, a new class of distributed and energy-efficient media-access protocols (MAC) for underwater acoustic sensor networks (UWSN). MAC design for UWSN faces significant challenges. For example, acoustic communication suffers from latencies five orders-of-magnitude larger than radio communication, so a naive CSMA MAC would require very long listen time resulting in low throughput and poor energy efficiency. In this paper, we first identify unique characteristics in underwater networking that may affect all MACs, such as space-time uncertainty and deafness conditions. We then develop T-Lohi employing a novel tone-based contention resolution mechanism that exploits space-time uncertainty and high latency to detect collisions and count contenders, achieving good throughput across all offered loads. Lohi uses our low-power wake-up receiver to significantly reduce energy consumption. Finally, we evaluate design choices and protocol performance through extensive simulation. The results show that the energy cost of packet transmission is within 3-9 % of optimal, and that Lohi achieves good channel utilization, within 30% utilization of the theoretical maximum. We also show that Lohi is stable and fair under both low and very high offered loads.

A Taxonomy of Botnet Behavior, Detection, and Defense

A number of detection and defense mechanisms have emerged in the last decade to tackle the botnet phenomenon. It is important to organize this knowledge to better understand the botnet problem and its solution space. In this paper, we structure existing botnet literature into three comprehensive taxonomies of botnet behavioral features, detection and defenses. This elevated view highlights opportunities for network defense by revealing shortcomings in existing approaches. We introduce the notion of a dimension to denote different criteria which can be used to classify botnet detection techniques. We demonstrate that classification by dimensions is particularly useful for evaluating botnet detection mechanisms through various metrics of interest. We also show how botnet behavioral features from the first taxonomy affect the accuracy of the detection approaches in the second taxonomy. This information can be used to devise integrated detection strategies by combining complementary approaches. To provide real-world context, we liberally augment our discussions with relevant examples from security research and products.

Energy Harvesting and Wireless Transfer in Sensor Network Applications: Concepts and Experiences

Advances in micro-electronics and miniaturized mechanical systems are redefining the scope and extent of the energy constraints found in battery-operated wireless sensor networks (WSNs). On one hand, ambient energy harvesting may prolong the systems’ lifetime or possibly enable perpetual operation. On the other hand, wireless energy transfer allows systems to decouple the energy sources from the sensing locations, enabling deployments previously unfeasible. As a result of applying these technologies to WSNs, the assumption of a finite energy budget is replaced with that of potentially infinite, yet intermittent, energy supply, profoundly impacting the design, implementation, and operation of WSNs. This article discusses these aspects by surveying paradigmatic examples of existing solutions in both fields and by reporting on real-world experiences found in the literature. The discussion is instrumental in providing a foundation for selecting the most appropriate energy harvesting or wireless transfer technology based on the application at hand. We conclude by outlining research directions originating from the fundamental change of perspective that energy harvesting and wireless transfer bring about.

A low-cost and flexible underwater platform to promote experiments in UWSN research

Underwater acoustic sensor networks (UWSN) is a relatively new research area, and remains quite challenging due to limited bandwidth, low data rate, severe multipath, and high variability in the channel conditions. These complicated and non-linear channel characteristics render incorrect most simplifying assumptions used in simulations. We believe that, while researchers have proposed several novel protocols, their use of models and simulations as the only form of validation and intra-protocol comparison remains removed from reality. We argue that research experimentation is hindered by two fundamental constraints: high cost of underwater networking experiments, and lack of a single, easily-replicable platform for evaluation. We present here Underwater Platform to Promote Experimental Research (UPPER): a low-cost (about

Sensors with lasers: building a WSN power grid

25/node) and flexible underwater platform designed to enable cost-effective and repeatable experimentation. We utilize COTS components to provide a HW/SW integrated solution that interfaces our custom hydrophones (

Design and evaluation of a low-cost, DIY-inspired, underwater platform to promote experimental research in UWSN

5 ea.) with laptops that act as an SDR-based physical layer, while allowing higher layer protocols to interact via a plug-and-play interface. We show that our platform can communicate over small (5-10m) distances and over a range of data rates (100-600bps). We believe our platform removes the barrier to validating simulation results in underwater environments and also allowing a fair comparison with related protocols.

Rapid and scalable isp service delivery through a programmable middlebox

We present here a first prac architecture that allows us to decouple en activities in WSN. Such a separation of us to utilize abundant energy sources d location, allowing unrestricted lifetime energy consumption in WSN. We demons practical decoupling using low-cost and -beaming that powers current WSN platf We design and implement LAMP: a tiered energy supply to both mesh and clust using an energy distribution protocol. W show that, for an additional cost of

SoftUPS: eliminating the need and cost of battery backups in the developing world

2 support perpetual mesh functionality for nodes in clustered operation.

A framework to rapidly test SDN use-cases and accelerate middlebox applications

Underwater Acoustic Sensor Networks (UWSN) is challenging research area due to limited bandwidth, low data rate, severe multipath, and high variability in the channel conditions. These complicated and non-linear channel characteristics render incorrect most simplifying assumptions used in simulations. We believe that, while researchers have proposed several novel protocols, their use of models and simulations as the only form of validation and intra-protocol comparison remains removed from reality. We argue that research experimentation is hindered by two fundamental constraints: high cost of underwater networking experiments, and lack of a single, easily-replicable platform for evaluation. We present here Underwater Platform to Promote Experimental Research (UPPER): a low-cost and flexible underwater platform designed to enable cost-effective and repeatable experimentation. We utilize commercial off-the-shelf (COTS) components to provide a HW/SW integrated solution that interfaces to two version of our custom hydrophones, from laptops that act as an Software-Defined Radio (SDR)-based physical layer, while allowing higher layer protocols to interact via a flexible API. With a total cost of

SDN-inspired, real-time botnet detection and flow-blocking at ISP and enterprise-level

25 and