Philipp Hurni

Flexible experimentation in wireless sensor networks

Virtual testbeds model them by seamlessly integrating physical, simulated, and emulated sensor nodes and radios in real time.

The Effects of Threading, Infection Time, and Multiple-Attacker Collaboration on Malware Propagation

Self-propagating malware spreads over the network quickly and automatically. Malware propagation should be modeled accurately for fast detection and defense. State-of-the-art malware propagation models fail to consider a number of issues.First, the malware can scan a host for multiple vulnerabilities on multiple ports. Second, the vulnerability scanning can be done by multiple threads concurrently. Third, the exploitation of vulnerabilities and the infection of vulnerable hosts cannot be done instantly. Fourth, the malware propagation can start from multiple places in the network rather than a single release point.Finally, the malware copies can collaborate with each other to cause much more damage.Little was done to understand the effects of Multi-port scanning,Multi-threading, Infection time, Multiple starting points,and Collaboration (MMIMC) on malware propagation. This research quantitatively measures the effects of MMIMC on infected hosts. We employ the Fibonacci Number Sequence (FNS)to model the effects of infection time. We derive the Shift Property, which illustrates that different malware initialization scan be represented by shifting their propagations on the time axis. We prove the Linear Property, which shows that the effects of multiple-attacker collaboration can be represented by linear combinations of individual attacks. Experimental results show that the above issues significantly affect malware propagation and verify our analysis.

MaxMAC: a maximally traffic-adaptive MAC protocol for wireless sensor networks

Energy efficiency is a major concern in the design of Wireless Sensor Networks (WSNs) and their communication protocols. As the radio transceiver typically accounts for a major portion of a WSN node’s power consumption, researchers have proposed Energy-Efficient Medium Access (E2-MAC) protocols that switch the radio transceiver off for a major part of the time. Such protocols typically trade off energy-efficiency versus classical quality of service parameters (throughput, latency, reliability). Today’s E2-MAC protocols are able to deliver little amounts of data with a low energy footprint, but introduce severe restrictions with respect to throughput and latency. Regrettably, they yet fail to adapt to varying traffic load at run-time. This paper presents MaxMAC, an E2-MAC protocol that targets at achieving maximal adaptivity with respect to throughput and latency. By adaptively tuning essential parameters at run-time, the protocol reaches the throughput and latency of energy-unconstrained CSMA in high-traffic phases, while still exhibiting a high energy-efficiency in periods of sparse traffic. The paper compares the protocol against a selection of today’s E2-MAC protocols and evaluates its advantages and drawbacks.

Energy-Efficient Multi-path Routing in Wireless Sensor Networks

The paper investigates the usefulness of multi-path routing to achieve lifetime improvements by load balancing and exploiting cross-layer information in wireless sensor networks. Performance gains in the order of 10-15 % could be achieved by altering path update rules of existing on-demand routing schemes. Problems encountered with concurrent traffic along interfering paths have been identified as a direct consequence of special MAC protocol properties.

On the accuracy of software-based energy estimation techniques

This paper examines the accuracy of software-based on-line energy estimation techniques. It evaluates todays most widespread energy estimation model in order to investigate whether the current methodology of pure software-based energy estimation running on a sensor node itself can indeed reliably and accurately determine its energy consumption - independent of the particular node instance, the traffic load the node is exposed to, or the MAC protocol the node is running. The paper enhances todays widely used energy estimation model by integrating radio transceiver switches into the model, and proposes a methodology to find the optimal estimation model parameters. It proves by statistical validation with experimental data that the proposed model enhancement and parameter calibration methodology significantly increases the estimation accuracy.

Evaluation of WiseMAC and extensions on wireless sensor nodes

In the past five years, many energy-efficient medium access protocols for all kinds of wireless networks (WSNs) have been proposed. Some recently developed protocols focus on sensor networks with low traffic requirements are based on so-called preamble sampling or low-power listening. The WiseMAC protocol is one of the first of this kind and still is one of the most energy-efficient MAC protocols for WSNs with low or varying traffic requirements. However, the high energy-efficiency of WiseMAC has shown to come at the cost of a very limited maximum throughput.In this paper, we evaluate the properties and characteristics of a WiseMAC implementation in simulation and on real sensor hardware. We investigate on the energy-consumption of the prototype using state-of-the-art evaluation methodologies. We further propose and examine an enhancement of the protocol designed to improve the traffic-adaptivity of WiseMAC. By conducting both simulation and real-world experiments, we show that the WiseMAC extension achieves a higher maximum throughput at a slightly increased energy cost both in simulation and real-world experiments.

Increasing Throughput for WiseMAC

The WiseMAC protocol is one of the most energy-efficient medium access control protocols for wireless sensor networks. However, in many typical wireless sensor network scenarios, throughput is limited when high traffic occurs, e.g., if many sensors detect and report an event to the base station. The paper proposes to extend and improve the optional more bit mechanism in WiseMAC. It allows bottleneck nodes to stay awake in case of high traffic instead of strictly sleeping periodically. Simulations show the effectiveness of the mechanism.

Simulation and evaluation of unsynchronized power saving mechanisms in wireless ad hoc networks

Power saving mechanisms in wireless ad hoc network nodes mainly switch off the transmission and reception hardware for a maximal amount of time and turn it on again within a given interval. Many approaches aim to synchronize the state changes of the nodes in the network through distributed beacon generation and introduce mechanisms where nodes synchronously wake up at designated points of time to exchange announcements about pending traffic. Synchronization however is difficult to achieve, in particular in ad hoc networks. This paper describes the simulation, evaluation and refinement of a recently proposed power saving approach based on asynchronous wake-up patterns and wake-up announcements integrated with AODV. We show that significant improvements of the connectivity under low wake ratios can be achieved by carefully designed forwarding strategies of AODV route request messages.

Multi-hop Cross-Layer Design in Wireless Sensor Networks: A Case Study

Cross-layer design has been proposed as a promising paradigm to tackle various problems of wireless communication systems. Recent research has led to a variety of protocols that rely on intensive interaction between different layers of the classical layered OSI protocol architecture. These protocols involve different layers and introduce new ideas how layers shall communicate and interact. In existing cross-layer approaches, the violation of the OSI architecture typically consists in passing information between different adjacent or non-adjacent layers of one single stations protocol stack to solve an optimization problem and exploiting the dependencies between the layers. This paper proposes to go a step further and to consider cross-layer information exchange across different layers of multiple stations involved in multi-hop communication systems. It outlines possible application scenarios of this approach, and trades off between advantages and disadvantages of the proposed \emph {multi-hop cross-layer design}. It examines an application scheme in a scenario of a wireless sensor network environment operating with a recent energy-efficient power saving protocol.

Calibrating Wireless Sensor Network Simulation Models with Real-World Experiments

This paper studies the energy-efficiency and service characteristics of a recently developed energy-efficient MAC protocol for wireless sensor networks in simulation and on a real sensor hardware testbed. This opportunity is seized to illustrate how simulation models can be verified by cross-comparing simulation results with real-world experiment results. The paper demonstrates that by careful calibration of simulation model parameters, the inevitable gap between simulation models and real-world conditions can be reduced. It concludes with guidelines for a methodology for model calibration and validation of sensor network simulation models.