Resource-constrained Sensor Nodes Research Articles

Providing Virtual Memory Support for Sensor Networks with Mass Data Processing

With the development of sensor networks and emerging of various sensors, sensor networks are capable of acquiring mass data to achieve much more complex monitoring tasks than ever. For example, image sensor nodes take photos using cameras, and images are collected and processed or stored for further processing. So, mass data processing is required for these sensor networks. However, low-power resource-constrained sensor nodes are normally equipped with kilobytes of RAM which might be not enough for storing large data for processing. In this paper, we propose an optimized virtual memory mechanism for large data processing on low-power sensor nodes. We point out the major overhead of virtual memory for large data processing on sensor nodes and introduce efficient solutions to address these issues. Evaluation shows that the overhead of the proposed virtual memory is reduced to an affordable range. We further compare the energy consumption of data processing programs using virtual memory with other means that process or transmit data. Data processing using virtual memory can be significantly more energy efficient than data processing using rich-resource sensor nodes or transmitting data to powerful gateways for central processing.

ESF: an efficient security framework for wireless sensor network

A wireless sensor network WSN consists of a large number of resource constrained sensor nodes, usually deployed in hostile environments, where they face a variety of malicious attacks. To address the security vulnerabilities in WSN, this paper proposes an efficient security framework ESF, which comprises of two security building blocks. The first one security building block is to establish key between the sending and receiving nodes while other component provides confidentiality and integrity of data. Owing to the limited resources available with the sensor nodes, ESF avoids intensive computations like public key cryptography and encryption mechanisms. Analysis of ESF shows that the framework provides a secure environment and resistant against the wireless threats using simple bit-wise operations and cryptographic hash functions.

Knowledge-based duty cycle estimation in wireless sensor networks: Application for sound pressure monitoring

Wireless sensor networks comprise an important research area and a near future for industry and communications. Wireless sensor networks contain resource-constrained sensor nodes that are powered by small batteries, limited process and memory and wireless communication. These features give sensors their versatility and drawbacks, such as their limited operating lifetimes. To feasibly deploy wireless sensor networks with isolated motes, several approaches and solutions have been developed; the most common, apart from using alternative power sources such as solar panels, are those that put sensors to sleep for time periods established by the application. We thus propose a fuzzy rule-based system that estimates the next duty cycle, taking the magnitude being tested and battery charge as input. To show how it works, we compare an analytical delta system to our contribution. As an application to test both systems, a sound pressure monitoring application is presented. The results have shown that the fuzzy rule-based system better predicts the evolution of the magnitude by which errors committed by idle periods decrease. This work also shows that application-oriented duty cycle control can be an alternative for measuring systems, thus saving battery and improving sensor node lifetime, with a reasonable loss of precision.

Sensor Node Localization with Uncontrolled Events

Event-driven localization has been proposed as a low-cost solution for node positioning in wireless sensor networks. In order to eliminate the costly requirement for accurate event control in existing methods, we present a practical design using uncontrolled events. The main idea is to estimate both event generation parameters and the location of sensor nodes simultaneously, by processing node sequences that can be easily obtained from event detections. Besides the basic design, we proposed two enhancements to further extract information embedded in node orderings for two scenarios: (i) node density is high; and (ii) abundant events are available. To demonstrate the generality of our design, both straight-line scan and circular wave propagation events are addressed in the article, and we evaluated the design with extensive simulation as well as a testbed implementation with 41 MICAz motes. Results show that with only randomly generated events, our design can effectively localize nodes with great flexibility while adding little extra cost at the resource constrained sensor node side. In addition, localization via uncontrolled events provides a potential option of achieving node positioning through long-term ambient events.

Containing bogus packet insertion attacks for broadcast authentication in sensor networks

Broadcast is a critical communication primitive in wireless sensor networks. The multihop nature of sensor networks makes it necessary for sensor nodes to forward broadcast messages so that the messages can reach an entire network. Authentication of broadcast messages is an important but challenging problem in sensor networks. Public key cryptography (PKC) has been used recently to address this problem. However, PKC-based authentication techniques are susceptible to bogus packet insertion attacks in which attackers keep broadcasting bogus messages and force resource-constrained sensor nodes to forward such messages. Moreover, because it takes time to do signature verifications, it is impractical for each node to authenticate every received message before forwarding it. In this article, we propose a dynamic window scheme to thwart the aforementioned bogus packet insertion attacks which permits sensor nodes to efficiently broadcast messages. Within this scheme, a sensor node has the ability to determine whether or not to verify an incoming message before forwarding the message. We further study the property of this dynamic window scheme and investigate the best strategy for thwarting bogus packet insertion attacks. We propose three strategies for finding the optimal parameters by an improved additive increase multiplicative decrease (AIMD) window updating function so that the proposed dynamic window scheme can achieve the best overall performance with respect to the authentication and forwarding times of messages. Numerical validations show that our proposed scheme performs very well in terms of energy saving and broadcast delays based on three different metrics, including average authentication delays, the percentage of nodes receiving fake messages, and the percentage of nodes forwarding fake messages.

PKC Based Broadcast Authentication using Signature Amortization for WSNs

Public Key Cryptography (PKC) is widely used for broadcast authentication. Intensive use of PKC for broadcast authentication, however, is thought to be expensive to resource constrained sensor nodes. In this paper, we propose a novel PKC based broadcast authentication scheme using signature amortization for Wireless Sensor Networks (WSNs). The proposed scheme exploits only one Elliptic Curve Digital Signature Algorithm (ECDSA) signature to authenticate all broadcast messages. Thus, the overhead for the signature is amortized over all broadcast messages. Besides low overhead, the proposed scheme retains high security that is as strong as conventional PKC based broadcast authentication schemes. Moreover, the proposed scheme can achieve immediate authentication and does not require time synchronization. For the implementation of the proposed scheme, an efficient public key distribution protocol is also presented in this paper. Experimental results of a testbed show that the overhead for authenticating a broadcast message is reduced significantly.

DiCode: DoS-Resistant and Distributed Code Dissemination in Wireless Sensor Networks

Code dissemination in a wireless sensor network (WSN) is the process of propagating a new program image or relevant commands to sensor nodes. As a WSN is usually deployed in hostile environments, secure code dissemination is and will continue to be a major concern. Most code dissemination protocols are based on the centralized approach in which only the base station has the authority to initiate code dissemination. However, it is desirable and sometimes necessary to disseminate code images in a distributed manner which allows multiple authorized network users to simultaneously and directly update code images on different nodes without involving the base station. Motivated by this consideration, we develop a secure and distributed code dissemination protocol named DiCode. A salient feature of DiCode is its ability to resist denial-of-service attacks which have severe consequences on network availability. Further, the security properties of our protocol are demonstrated by theoretical analysis. To verify the efficiency of the proposed approach in practice, we also implement the proposed mechanism in a network of resource-constrained sensor nodes.

Elitist Genetic Algorithm Based Energy Efficient Routing Scheme For Wireless Sensor Networks

Wireless Sensor Networks have gained world-wide attention in recent years due to the advances made in wireless communication, information technologies and electronics field. They consist of resource constrained sensor nodes that are usually randomly or manually deployed in an area to be observed, collecting data from the sensor field and transmitting the gathered data to a distant Base Station. The nodes are energy limited sensors, and therefore it is important to increase the network lifetime. Energy saving is one of the critical issues in the routing design in WSNs. The factors causing the unequal energy dissipation are firstly, the distance between the nodes and base station and secondly, the distance between the nodes themselves. Using traditional methods it is difficult to obtain the high precision of solution as the problem is NP hard. Applying genetic algorithms (GAs) in finding energy efficient shortest route for WSNs is emerging as an important field. The routing in WSN is a combinatorial optimization problem, hence GA can provide optimized solution to energy efficient shortest path problem in WSN. This paper uses a forward address based shortest path routing in the network. Genetic algorithm with elitism concept is used to obtain energy efficient routing by minimizing the path length and thus maximizing the life of the network. The proposed algorithm has its inherent advantage that it keeps the elite solutions in the next generation so as to quickly converge towards the global optima. The results show that GAs are efficient for finding the optimal energy constrained route as they can converge faster than other traditional methods used for combinatorial optimization problems.

Adjusting Transmission Power for Real-Time Communications in Wireless Sensor Networks

As the new requirements for wireless sensor networks are emerging, real-time communications is becoming a major research challenge because resource-constrained sensor nodes are not powerful enough to accommodate the complexity of the protocol. In addition, an efficient energy management scheme has naturally been a concern in wireless sensor networks for a long time. However, the existing schemes are limited to meeting one of these two requirements. To address the two factors together, we propose real-time communications with two approaches, a protocol for satisfied conditions and one for unsatisfied. Under the satisfied requirement, existing real-time protocol is employed. On the other hand, for the unsatisfied requirement, the newly developed scheme replaces the existing scheme by adjusting the transmission range of some surplus nodes. By expanding the transmission range, the end-to-end delay is shortened because the number of intermediate nodes decreases. These nodes conserve their energy for real-time communications by avoiding other activities such as sensing, forwarding, and computing. Finally, simulation results are given to demonstrate the feasibility of the proposed scheme in high traffic environments.

A proposal for proxy-based mobility in WSNs

Inability to meet the key requirement of efficient mobility support is becoming a major impairment of wireless sensor network (WSN). Many critical WSN applications need not only reliability, but also the ability to adequately cope with the movement of nodes between different sub-networks. Despite the work of IETF’s 6lowPAN WG and work on the use of MIPv6 (and many of its variants) in WSNs, no practical mobility support solution exists for this type of networks. In this paper we start by assessing the use of MIPv6 in WSNs, considering soft and hard handoff, showing that, although feasible in small networks, MIPv6 complexity leads to long handoff time and high energy consumption. In order to solve these problems, we propose a proxy-based mobility approach which, by relieving resource-constrained sensor nodes from heavy mobility management tasks, drastically reduces time and energy expenditure during handoff. The evaluation of both MIPv6 and the proposed solution is done by implementation and simulation, with a varying number of nodes, sinks and mobility strategies.

CONSTRAINED RELAY NODE DEPLOYMENT FOR UNDERWATER ACOUSTIC WIRELESS SENSOR NETWORKS

An underwater acoustic wireless sensor network (UA-WSN) consists of many resource-constrained underwater sensor nodes (USNs), which are deployed to perform collaborative monitoring tasks over a given region. One way to preserve network connectivity while guaranteeing other network QoS is to deploy some relay nodes (RNs) in the networks. Although RNs' function is more powerful than USNs, but they can lead to more interference and their cost is more expensive. This paper addresses constrained low-interference relay node deployment problem for 3-D UA-WSNs in which the RNs are placed at a subset of candidate locations to ensure connectivity between the USNs such that the number of RNs deployed and the value of total incremental interference are minimized. We first prove that it is NP-hard, then propose a general approximation algorithm framework. Based on the framework, we get two polynomial time O(1)-approximation algorithms.

센서네트워크 동작 및 센싱 알고리즘 검증을 위한 소프트웨어 프레임워크

Most of sensor networks are difficult to be debugged, verified, and upgraded once they are deployed in the fields, for they are usually deployed in real world and large scale. Therefore, before deploying the sensor networks, we should test and verify them sufficiently in realistic testbeds. However, since we need to control physical environments which interact with sensor networks, it takes much of time and cost to test and verify sensor networks at the level of resource-constrained sensor nodes in such environments. This paper proposes an efficient software framework for evaluating and verifying sensor networks in the view points of network and application operations (i.e., accuracy of sensing algorithms). Applying the proposed software framework to the development of a simulator for a smart parking application based on wireless sensor network, this paper verifies the feasibility of the proposed framework.

A Comparative Study of Security Protocols for Wsns

Wireless sensor network is a network comprises of low cost resource constrained sensor nodes that are communicating using wireless medium. Similar to other technologies, in WSNs there are some considerable issues that should be taken into account. One of that issues is security. As the wireless sensor nodes are employed in a remote or hostile environmental area that is prone to attacks frequently, so security is an important and valuable criterion to be considered in WSNs [6]. Many Secured protocols are proposed in wireless sensor networks. This paper is presented to do a comparative study of all these protocols considering all the challenging issues and requirements of security. Summary: This paper analyzes five popular WSN security protocols: SPINS [6,7], LEAP[8] TINYSEC [6,7], MINYSEC[4,9], and ZIGBEE[10], And SIM[11]. The paper also presents an application characteristics table which helps to select the appropriate security protocols. Rest of the paper is organized as follows. Section 2 describes the general security constraints of WSN. Section 3 defines the security challenges in WSNs. Section 4 provides the major features of selected security protocols. Section 5 analyzes and compares the selected security protocols. Finally, Section 6 concludes the paper.

Energy-aware Key Management in Mobile Wireless Sensor Networks

Wireless sensor networks have received wide attention recently across the indoor and outdoor applications. On the other hand, more and more application scenarios require sensor nodes to be mobile, which imposes new technological challenges for security. Key management is the core for secure data communications among the resource-constrained sensor nodes. In this paper, based on the Group Diffie-Hellman key agreement protocols and the energy level of each node in the network, we propose Energy Aware Group Diffie-Hellman key management protocol for mobile wireless sensor networks. The simulation results show that the proposed key management protocol provide significant improvement in maximizing the lifetime of networks.

A Survey on Transport Protocols for Wireless Multimedia Sensor Networks

Wireless networks composed of multimedia-enabled resource-constrained sensor nodes have enriched a large set of monitoring sensing applications. In such communication scenario, however, new challenges in data transmission and energy-efficiency have arisen due to the stringent requirements of those sensor networks. Generally, congested nodes may deplete the energy of the active congested paths toward the sink and incur in undesired communication delay and packet dropping, while bit errors during transmission may negatively impact the end-to-end quality of the received data. Many approaches have been proposed to face congestion and provide reliable communications in wireless sensor networks, usually employing some transport protocol that address one or both of these issues. Nevertheless, due to the unique characteristics of multimedia-based wireless sensor networks, notably minimum bandwidth demand, bounded delay and reduced energy consumption requirement, communication protocols from traditional scalar wireless sensor networks are not suitable for multimedia sensor networks. In the last decade, such requirements have fostered research in adapting existing protocols or proposing new protocols from scratch. We survey the state of the art of transport protocols for wireless multimedia sensor networks, addressing the recent developments and proposed strategies for congestion control and loss recovery. Future research directions are also discussed, outlining the remaining challenges and promising investigation areas.

Practical and secure localization and key distribution for wireless sensor networks

In many applications of wireless sensor networks, sensor nodes are manually deployed in hostile environments where an attacker can disrupt the localization service and tamper with legitimate in-network communication. In this article, we introduce Secure Walking GPS, a practical and cost effective secure localization and key distribution solution for real, manual deployments of WSNs. Using the location information provided by the GPS and inertial guidance modules on a special master node, Secure Walking GPS achieves accurate node localization and location-based key distribution at the same time. We evaluate our localization solution in real deployments of MicaZ. Our experiments show that 100% of the deployed nodes localize (i.e., have a location position) and that the average localization errors are within 1–2m, due mainly to the limitations of the existing commercial GPS devices. Our further analysis and simulation results indicate that the Secure Walking GPS scheme makes a deployed WSN resistant to the Dolev-Yao, the wormhole, and the GPS-denial attacks, the scheme is practical for large-scale deployments with resource-constrained sensor nodes and has good localization and key distribution performance.

Highly Secure Key Predistribution Using Affine Planes And Reed Muller Codes In Wireless Sensor Networks

Wireless Sensor Networks (WSN) consist of low powered and resource constrained sensor nodes which are left unattended for long duration of time. Hence it is very challenging to design and implement cost effective security protocols for such networks. Thus symmetric key cryptographic techniques are preferred over public key techniques for communication in such scenarios. Prior to deployment, keys are usually predistributed into the nodes and this problem has been well studied. Highlighting that connectivity and communication are two separate aspects of a WSN, we propose a secure connectivity model using Reed Muller codes. The model is then utilized to securely establish communication keys and exchange messages in a WSN designed on the basis of a scheme that uses affine planes for key predistribution. By the introduction of connectivity model, the node identifiers (ids) are converted from public to private information to each node. These private node ids can be used to generate new communication keys from old ones by applying cryptographic hash functions. Novel combination of these ideas yields highly resilient communication model with full connectivity between nodes.

Secure-TWS: Authenticating Node to Multi-user Communication in Shared Sensor Networks

Recent works have shown the usefulness of network and application layer protocols that connect low-power sensor nodes directly to multiple applications and users on the Internet. We propose a security solution for this scenario. While previous works have provided security support for various communication patterns in sensor networks, such as among nodes, from nodes to a base station, and from users to nodes, the security of communication from sensor nodes to multiple users has not been sufficiently addressed. Specifically, we explore this design space and develop a security solution, named Secure Tiny Web Service, for efficient authentication of data sent by a resource-constrained sensor node to multiple users, using digital signatures. We investigate the resource overheads in communication and computation of four suitable signature schemes—the Elliptic Curve Digital Signature Algorithm, the (elliptic curve) Schnorr signature, and the Boneh–Lynn–Shacham and Zhang–Safavi-Naini–Susilo short signature schemes. We implement these schemes on two popular sensor node architectures (based on AVR ATmega128L and MSP430 processors with 802.15.4 radios) and experimentally characterize relevant trade-offs.

Dynamic hinting: Collaborative real-time resource management for reactive embedded systems

The increasing complexity of today's reactive embedded applications can rapidly result in reduced real-time capabilities of the underlying hard and software. As an example for this paper we'll refer to the specific and growing demands on the severely resource constrained sensor nodes in sensor/actuator networks (SANet). While preemptive operating systems are one way to retain acceptable reactivity within highly dynamic environments, their concurrency paradigm commonly leads to severe resource management problems, caused by the coexistence of tasks with interfering and even varying requirements. To counteract these problems, we present the novel Dynamic Hinting approach for maintaining good reactivity in typically resource constrained sensor/actuator systems by efficient combination of preemptive task scheduling and collaborative resource allocation. With respect to task priorities, our technique significantly improves classical methods for handling priority inversions (and deadlocks where required) under both short- and long-term resource allocations. Furthermore, we facilitate compositional software design by providing independently developed tasks with runtime information for yet collaborative and reflective resource sharing - e.g. by means of time-utility-functions. In many cases this even allows to reduce blocking delays as otherwise imposed by bounded priority inversion.

무선 센서 노드를 위한 FSM 기반 운영체제의 구현

무선 센서 네트워크는 단거리 무선 통신으로 연결된 지능 센서가 사람과 실세계 객체간의 효과적인 매개자 역할을 하므로 최근 유비쿼터스 컴퓨팅 환경을 가능하게 할 수 있는 핵심적인 기술 중 하나로 각광을 받고 있다. 무선 센서 네트워크는 대량으로 분산된 극도의 내장형 시스템으로 볼 수 있다. 이 시스템은 분산 시스템으로서 병행성과 비동기적 이벤트 처리 능력에 대한 요구사항과 함께 내장형 시스템으로서 자원제한성에 따른 심각한 요구사항을 갖고 있다. 이러한 일견 상충하는 두 가지 요구사항을 갖는 무선 센서 네트워크의 운영 환경과 구조는 시스템 개발자에게 매우 독특한 어려움을 제기하고 있으므로 우리는 유한상태기계에 기반을 둔, 매우 새로운 형태의 센서 네트워크용 운영체제를 제안한다. 본 논문에서는 센서 네트워크의 특성을 감안한 설계 목표를 명시하고, 간결하고 효율적인 상태기반 운영체제인 SenOS 설계와 구현의 핵심 사항을 제시한다. 또한 이러한 SenOS가 심각한 자원제한성을 갖는 센서 노드 상에서 원하는 반응성을 갖으면서도 적은 비용으로 동적 재구성이 가능하다는 것을 설명한다. 이러한 성능은 대표적인 센서 노드용 운영체제인 TinyOS의 성능평가에 사용된 벤치마크 프로그램을 수행하고 그 결과를 TinyOS의 경우와 비교한다. Wireless sensor networks have emerged as one of the key enabling technologies for ubiquitous computing since wireless intelligent sensor nodes connected by short range communication media serve as a smart intermediary between physical objects and people in ubiquitous computing environment. We recognize the wireless sensor network as a massively distributed and deeply embedded system. Such systems require concurrent and asynchronous event handling as a distributed system and resource-consciousness as an embedded system. Since the operating environment and architecture of wireless sensor networks, with the seemingly conflicting requirements, poses unique design challenges and constraints to developers, we propose a very new operating system for sensor nodes based on finite state machine. In this paper, we clarify the design goals reflected from the characteristics of sensor networks, and then present the heart of the design and implementation of a compact and efficient state-driven operating system, SenOS. We describe how SenOS can operate in an extremely resource constrained sensor node while providing the required reactivity and dynamic reconfigurability with low update cost. We also compare our experimental results after executing some benchmark programs on SenOS with those on TinyOS.