Wireless sensor networks are composed of large numbers of tiny networked devices that communicate untethered. For large scale networks, it is important to be able to download code into the network dynamically. We present Contiki, a lightweight operating system with support for dynamic loading and replacement of individual programs and services. Contiki is built around an event-driven kernel but provides optional preemptive multithreading that can be applied to individual processes. We show that dynamic loading and unloading is feasible in a resource constrained environment, while keeping the base system lightweight and compact.

/pdf/contiki-a-lightweight-and-flexible-operating-system-for-tiny-17ra90mhum.pdf

Contiki - a lightweight and flexible operating system for tiny networked sensors

In this paper we present X-MAC, a low power MAC protocol for wireless sensor networks (WSNs). Standard MAC protocols developed for duty-cycled WSNs such as BMAC, which is the default MAC protocol for TinyOS, employ an extended preamble and preamble sampling. While this “low power listening” approach is simple, asynchronous, and energy-efficient, the long preamble introduces excess latency at each hop, is suboptimal in terms of energy consumption, and suffers from excess energy consumption at nontarget receivers. X-MAC proposes solutions to each of these problems by employing a shortened preamble approach that retains the advantages of low power listening, namely low power communication, simplicity and a decoupling of transmitter and receiver sleep schedules. We demonstrate through implementation and evaluation in a wireless sensor testbed that X-MAC’s shortened preamble approach significantly reduces energy usage at both the transmitter and receiver, reduces per-hop latency, and offers additional advantages such as flexible adaptation to both bursty and periodic sensor data sources.

X-MAC: A Short Preamble MAC Protocol for Duty-Cycled Wireless Sensor Networks ; CU-CS-1008-06

Many technical communities are vigorously pursuing research topics that contribute to the Internet of Things (IoT). Nowadays, as sensing, actuation, communication, and control become even more sophisticated and ubiquitous, there is a significant overlap in these communities, sometimes from slightly different perspectives. More cooperation between communities is encouraged. To provide a basis for discussing open research problems in IoT, a vision for how IoT could change the world in the distant future is first presented. Then, eight key research topics are enumerated and research problems within these topics are discussed.

/pdf/research-directions-for-the-internet-of-things-2x8dpg1w6r.pdf

Research Directions for the Internet of Things

In this paper we present X-MAC, a low power MAC protocol for wireless sensor networks (WSNs). Standard MAC protocols developed for duty-cycled WSNs such as BMAC, which is the default MAC protocol for TinyOS, employ an extended preamble and preamble sampling. While this "low power listening" approach is simple, asynchronous, and energy-efficient, the long preamble introduces excess latency at each hop, is suboptimal in terms of energy consumption, and suffers from excess energy consumption at nontarget receivers. X-MAC proposes solutions to each of these problems by employing a shortened preamble approach that retains the advantages of low power listening, namely low power communication, simplicity and a decoupling of transmitter and receiver sleep schedules. We demonstrate through implementation and evaluation in a wireless sensor testbed that X-MAC's shortened preamble approach significantly reduces energy usage at both the transmitter and receiver, reduces per-hop latency, and offers additional advantages such as flexible adaptation to both bursty and periodic sensor data sources.

/pdf/x-mac-a-short-preamble-mac-protocol-for-duty-cycled-wireless-3g39p5984w.pdf

X-MAC: a short preamble MAC protocol for duty-cycled wireless sensor networks

They are susceptible to a variety of attacks, including node capture, physical tampering, and denial of service, while prompting a range of fundamental research challenges.

/pdf/security-in-wireless-sensor-networks-119x7nks5g.pdf

Security in wireless sensor networks

The MANTIS MultimodAl system for NeTworks of In-situ wireless Sensors provides a new multithreaded cross-platform embedded operating system for wireless sensor networks. As sensor networks accommodate increasingly complex tasks such as compression/aggregation and signal processing, preemptive multithreading in the MANTIS sensor OS (MOS) enables micro sensor nodes to natively interleave complex tasks with time-sensitive tasks, thereby mitigating the bounded buffer producer-consumer problem. To achieve memory efficiency, MOS is implemented in a lightweight RAM footprint that fits in less than 500 bytes of memory, including kernel, scheduler, and network stack. To achieve energy efficiency, the MOS power-efficient scheduler sleeps the microcontroller after all active threads have called the MOS sleep() function, reducing current consumption to the µA range. A key MOS design feature is flexibility in the form of cross-platform support and testing across PCs, PDAs, and different micro sensor platforms. Another key MOS design feature is support for remote management of in-situ sensors via dynamic reprogramming and remote login.

/pdf/mantis-os-an-embedded-multithreaded-operating-system-for-297bti43zu.pdf

MANTIS OS: an embedded multithreaded operating system for wireless micro sensor platforms

Wireless sensor networks are highly vulnerable to the failure of base stations. An adversary can render a wireless sensor network useless by launching remote, softwarebased attacks or physical attacks on the base stations. This paper addresses the problem of defending a base station against physical attacks by concealing the geographic location of a base station. Typical packet traffic in a sensor network reveals pronounced patterns that allow an adversary analyzing packet traffic to deduce the location of a base station. The paper investigates several countermeasures against traffic analysis techniques aimed at disguising the location of a base station. First, a degree of randomness is introduced in the multi-hop path a packet takes from a sensor node to a base station. Second, random fake paths are introduced to confuse an adversary from tracking a packet as it moves towards a base station. Finally, multiple, random areas of high communication activity are created to deceive an adversary as to the true location of the base station. The paper evaluates these techniques analytically and via simulation using three evaluation criteria: total entropy of the network, total energy consumed, and the ability to guard against heuristic-based techniques to locate a base station.

Countermeasures Against Traffic Analysis Attacks in Wireless Sensor Networks

This paper evaluates the performance of INSENS, an INtrusion-tolerant routing protocol for wireless SEnsor Networks. Security in sensor networks is important in battlefield monitoring and home security applications to prevent intruders from eavesdropping, from tampering with sensor data, and from launching denial-of-service (DOS) attacks against the entire network. The resilience of INSENS's multipath performance against various forms of communication-based attacks by intruders is evaluated in simulation. Within the context of INSENS, the paper evaluates implementations on the motes of the RC5 and AES encryption standards, an RC5-based scheme to generate message authentication codes (MACs), and an RC5-based generation of one-way sequence numbers.

/pdf/a-performance-evaluation-of-intrusion-tolerant-routing-in-3wzj7fec54.pdf

A performance evaluation of intrusion-tolerant routing in wireless sensor networks

Wireless sensor networks face acute security concerns in applications such as battlefield monitoring. A central point of failure in a sensor network is the base station, which acts as a collection point of sensor data. In this paper, we investigate two attacks that can lead to isolation or failure of the base station. In one set of attacks, the base station is isolated by blocking communication between sensor nodes and the base station, e.g. by DOS attacks. In the second attack, the location of the base station is deduced by analyzing data traffic towards the base station, which can lead to jamming and/or discovery and destruction of the base station. To defend against these attacks, two secure strategies are proposed. First, secure multi-path routing to multiple destination base stations is designed to provide intrusion tolerance against isolation of a base station. Second, anti-traffic analysis strategies are proposed to help disguise the location of the base station from eavesdroppers. A performance evaluation is provided for a simulated sensor network, as well as measurements of cryptographic overhead on real sensor nodes.

/pdf/intrusion-tolerance-and-anti-traffic-analysis-strategies-for-3mtmit72p1.pdf

Intrusion tolerance and anti-traffic analysis strategies for wireless sensor networks

Denial of service (DoS) attacks can cause serious damage in resource-constrained, wireless sensor networks (WSNs). This paper addresses an especially damaging form of DoS attack, called PDoS (Path-based Denial of Service). In a PDoS attack, an adversary overwhelms sensor nodes a long distance away by flooding a multi-hop end-to-end communication path with either replayed packets or injected spurious packets. This paper proposes a solution using one-way hash chains to protect end-to-end communications in WSNs against PDoS attacks. The proposed solution is lightweight, tolerates bursty packet losses, and can easily be implemented in modern WSNs. The paper reports on performance measured from a prototype implementation.

Jing Deng

Papers

MANTIS OS: an embedded multithreaded operating system for wireless micro sensor platforms

Countermeasures Against Traffic Analysis Attacks in Wireless Sensor Networks

A performance evaluation of intrusion-tolerant routing in wireless sensor networks

Intrusion tolerance and anti-traffic analysis strategies for wireless sensor networks

Defending against path-based DoS attacks in wireless sensor networks