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Glossy networks make use of concurrent transmissions to achieve rapid network flooding in wireless networks with high reliability. They are robust against jamming and header injection attacks. We find that Glossy floods can be hijacked by a packet injection attacker to penetrate into the network and cause severe loss. We demonstrate the design of such an attacker by evaluating its effectiveness in a 30-node testbed., Promos

In this paper we present a new kind of Denial-of-Service attack against the PHY layer of low power wireless sensor networks. Overcoming the very limited range of jamming-based attacks, this attack can penetrate deep into a target network with high power efficiency. We term this the Droplet attack, as it attains enormous disruption by dropping small, payload-less frame headers to its victim's radio receiver, depriving the latter of bandwidth and sleep time. We demonstrate the Droplet attack's high damage rate to full duty-cycle receivers, and further show that a high frequency version of Droplet can even force nodes running on very low duty-cycle MAC protocols to drop most of their packets., WISENET (NES), Promos

In this position paper, we advocate the use of bus snooping to trace radio events. Highly precise and unintrusive, the technique leads to potentially more efficient code and enables more insightful protocol analysis than conventional code instrumentation techniques., GINSENG, CONET

Link quality estimation of reliability-crucial wireless sensor networks (WSNs) is often limited by the observability and testability of single-chip radio transceivers. The estimation is often based on collection of packer-level statistics, including packet reception rate, or vendor-specific registers, such as CC2420's Received Signal Strength Indicator (RSSI) and Link Quality Indicator (LQI). The speed or accuracy of such metrics limits the performance of reliability mechanisms built in wireless sensor networks. To improve link quality estimation in WSNs, we designed a powerful wireless communication monitor based on Software Defined Radio (SDR). We studied the relations between three implemented link quality metrics and packet reception rate under different channel conditions. Based on a comparison of the metrics' relative advantages, we proposed using a combination of them for fast and accurate estimation of a sensor network link., ReSense

ReSense

—Intermediate-quality links often cause vulnerable connectivity in wireless sensor networks, but packet losses caused by such volatile links are not easy to trace. In order to equip link layer protocol designers with a reliable test and debugging tool, we develop a reactive interferer to generate packet loss patterns precisely. By using intentional interference to emulate parameterized lossy links with very low intrusiveness, our tool facilitates both robustness evaluation of protocols and flaw detection in protocol implementation., GINSENG

Link quality estimation has been an important research topic in the wireless sensor networking community and researchers have developed a large number of different methods to estimate link quality. The commonly used CC2420 radio provides simple signal quality indicators. These are agile in that they react fast to changing link quality but they are inaccurate under complicated channel conditions. More sophisticated link quality estimators combine these simple metrics with packet reception statistics collected by the network stack. These approaches compensate the hardware-based metrics to a limited degree but they compromise agility and incur extra overhead. In this paper, we take a novel approach and develop a number of link quality metrics using a software defined radio. We evaluate our metrics under several channel conditions. The results show that they have good accuracy and can handle complicated channel conditions if combined properly., CNS-STANDEMB

GINSENG

We address the problem of analysing performance anomalies in sensor networks. In this paper, we propose an approach that uses the local flash storage of the motes for logging system data, in combination with online statistical analysis. Our results show not only that this is a feasible method but that the overhead is significantly lower than that of communication-centric methods, and that interesting patterns can be revealed when calculating the correlation of large data sets of separate event types., GINSENG, CONET

Low power wireless sensors are limited by current radio technologies to short communication range and low throughput. We envision that future radios with advanced software programmable encoding and modulation will bring sensor networks unprecedented flexibility and performance. We have taken a step towards realizing this vision by designing a softwarebased, narrow-band transceiver using the GNU Radio software and the Universal Software Radio Peripheral hardware. We have verified the compatibility of our implementation with existing wireless sensor platforms. We demonstrate the flexibility of our design with sensing applications running on a sensor network communicating over hybrid radios., ReSense, CONET

GINSENG, CONET, ReSense

Persistent storage offers multiple advantages for sensor networks, yet the available storage systems have been unwieldy because of their complexity and device-specific designs. We present the Coffee file system for flash-based sensor devices. Coffee provides a programming interface for building efficient and portable storage abstractions. Unlike previous flash file systems, Coffee uses a small and constant RAM footprint per file, making it scale elegantly with workloads consisting of large files or many files. In addition, the performance overhead of Coffee is low: the throughput is at least 92\% of the achievable direct flash driver throughput. We show that network layer components such as routing tables and packet queues can be implemented on top of Coffee, leading to increased performance and reduced memory requirements for routing and transport protocols., Contiki, CONET, ESNA, Promos

CONET, GINSENG

CONET, GINSENG, ReSense

Sensor network development is notoriously difficult due to the low visibility of sensor platforms and systems. We propose sensornet checkpointing to increase the visibility of sensor networks. With sensornet checkpointing, we transfer network-wide application checkpoints between simulated and real networks. This approach enable advances in many research areas: visualization, repeatable experiments, fault injection, and application debugging. We demonstrate sensornet checkpointing on a network of Tmote Sky motes running Contiki., CONET, ESNA, Contiki, GINSENG, Promos

For designers of the communication stack of sensor nodes there is a constant tension between performance and modularity. To alleviate this tension, researchers have come up with a number of modular architectures. In this work we take a refreshed view of the design of an abstract link level service, an important component in the communication stack. We start with a critical review of one such service, the Sensornet Protocol (SP), and then we implement an SP-flavored link level service featuring a novel combination of ARQ and MAC. Experimental results of transmission delay and energy efficiency highlight a few subtle architectural design trade-offs we have encountered, namely semantics binding, implicit information sharing, and time scope initialization. These aspects have significant impact on software modularity in tiny sensor nodes., AppSN, Contiki, ESNA

Sensornet Protocol (SP) is a link abstraction layer between the network layer and the link layer for sensor networks. SP was proposed as the core of a future-oriented sensor node architecture that allows flexible and optimized combination between multiple coexisting protocols. This thesis implements the SP sensornet protocol on the Contiki operating system in order to: evaluate the effectiveness of the original SP services; explore further requirements and implementation trade-offs uncovered by the original proposal. We analyze the original SP design and the TinyOS implementation of SP to design the Contiki port. We implement the data sending and receiving part of SP using Contiki processes, and the neighbor management part as a group of global routines. The evaluation consists of a single-hop traffic throughput test and a multihop convergecast test. Both tests are conducted using both simulation and experimentation. We conclude from the evaluation results that SP's link-level abstraction effectively improves modularity in protocol construction without sacrificing performance, and our SP implementation on Contiki lays a good foundation for future protocol innovations in wireless sensor networks.