Wireless Sensor Network Research Research Articles

Application Research of Wireless Sensor Network in Intelligent Transportation System

The research of using wireless sensor network to settle the problem of urban traffic has become a hotspot in the fields of intelligent transportation system. In this paper, a wireless sensor network model based on mobile agents is proposed. Since mobile agents have characteristics of autonomous collaboration and asynchronous interaction, this model owns the abilities of adapting to the dynamic network changes, reducing the network load and enhancing the data fusion. In the application of the model, the travelers can be guided to choose the right road line through calculation of the predicated value of traffic congestion, so the condition of the traffic congestion can be remitted in some way.

Robust Aggregation Algorithm in Sensor Networks

Saving energy to prolong network life is a big challenge for WSNs (wireless sensor networks) research. In-Network query can reduce the number or size of packets through processing data in intermediate nodes so as to consume energy effectively. Present aggregation algorithms suppose all the sample data are correct. The existing outlier detection algorithms regard detection rate as the primary object and do not consider energy consumption and query characteristic. So the simple combination of the two aspects can not bring good performance. By analyzing the influence of faulty and outlier readings to aggregation results, this paper puts forward a robust aggregation algorithm RAA (robust aggregation algorithm). RAA improves traditional aggregation query using reading vector to judge whether a faulty or outlier has happened. RAA deletes faulty readings, aggregates normal readings and reports outliers. Thus, customers can know the networks condition clearly. Finally, this paper compares RAA and TAGVoting which uses tiny aggregation algorithm to complete aggregation and the Voting algorithm to realize outlier detection at the same time. Experimental results show that RAA outperforms TAGVoting in terms of both energy consumption and detection rate.

Where is the return on investment in wireless sensor networks?

Research and development of wireless sensor networks (WSNs) is motivated by their potential for ubiquitous monitoring and response . Expanded spatial and temporal monitoring coupled with actuation has huge promise for a range of defense, energy, agriculture, and manufacturing applications. However, WSNs still fall well below this potential. In this article I discuss reasons for this gap, based on lessons learned from developing multiple WSN systems. Specifically, I focus on the need for technologies to enable WSN software development, and rigorous models to improve the understanding of each WSN application.

Energy Conservation Challenges in Wireless Sensor Networks: A Comprehensive Study

A Wireless Sensor Network (WSN) consists of a large number of randomly deployed sensor nodes. These sensor nodes organize themselves into a cooperative network and perform the three basic functions of sensing, computations and communications. Research in WSNs has become an extensive explorative area during the last few years, especially due to the challenges offered, energy constraints of the sensors being one of them. In this paper, a thorough comprehensive study of the energy conservation challenges in wireless sensor networks is carried out. The need for effective utilization of limited power resources is also emphasized, which becomes pre-eminent to the Wireless Sensor Networks.

Integration of wireless sensor networks in environmental monitoring cyber infrastructure

Wireless sensor networks (WSNs) have great potential to revolutionize many science and engineering domains. We present a novel environmental monitoring system with a focus on overall system architecture for seamless integration of wired and wireless sensors for long-term, remote, and near-real-time monitoring. We also present a unified framework for sensor data collection, management, visualization, dissemination, and exchange, conforming to the new Sensor Web Enablement standard. Some initial field testing results are also presented. The monitoring system is being integrated into the Texas Environmental Observatory infrastructure for long-term operation. As part of the integrated system, a new WSN-based soil moisture monitoring system is developed and deployed to support hydrologic monitoring and modeling research. This work represents a significant contribution to the empirical study of the emerging WSN technology. We address many practical issues in real-world application scenarios that are often neglected in the existing WSN research.

Design of Modified Adaptive Huffman Data Compression Algorithm for Wireless Sensor Network

Problem statement: Efficient utilization of energy has been a core area of research in wireless sensor networks. Sensor nodes deployed in a network are battery operated. As batteries cannot be recharged frequently in the field setting, energy optimization becomes paramount in prolonging the battery-life and, consequently, the network lifetime. The communication module utilizes a major part of the energy expenditure of a sensor node. Hence data compression methods to reduce the number of bits to be transmitted by the communication module will significantly reduce the energy requirement and increase the lifetime of the sensor node. The present objective of the study contracted with the designing of efficient data compression algorithm, specifically suited to wireless sensor network. Approach: In this investigation, the natural correlation in a typical wireless sensor network data was exploited and a modified Huffman algorithm suited to wireless sensor network was designed. Results: The performance of the modified adaptive Huffman algorithm was analyzed and compared with the static and adaptive Huffman algorithm. The results indicated better compression ratio. Conclusion: Hence the proposed algorithm outperformed both static and adaptive Huffman algorithms, in terms of compression ratio and was well suited to embedding in sensor nodes for compressed data communication.

Lacas: learning automata-based congestion avoidance scheme for healthcare wireless sensor networks

One of the major challenges in wireless sensor network (WSN) research is to curb down congestion in the network's traffic, without compromising with the energy of the sensor nodes. Congestion affects the continuous flow of data, loss of information, delay in the arrival of data to the destination and unwanted consumption of significant amount of the very limited amount of energy in the nodes. Obviously, in healthcare WSN applications, particularly in the ones that cater to medical emergencies or in the ones that closely monitor critically ailing patients, it is desirable in the first place to avoid congestion from occurring and even if it occurs, to reduce the loss of data due to congestion. In this work, we address the problem of congestion in the nodes of healthcare WSN using a learning automata (LA)-based approach. Our primary objective in using this approach is to adaptively make the processing rate (data packet arrival rate) in the nodes equal to the transmitting rate (packet service rate), so that the occurrence of congestion in the nodes is seamlessly avoided. We maintain that the proposed algorithm, named as learning automata-based congestion avoidance algorithm in sensor networks (LACAS), can counter the congestion problem in healthcare WSNs effectively. An important feature of LACAS is that it intelligently' learns' from the past and improves its performance significantly as time progresses. Our proposed LA based model was evaluated using simulations representing healthcare WSNs. The results obtained through the experiments with respect to performance criteria having important implications in the healthcare domain, for example, the number of collisions, the energy consumption at the nodes, the network throughput, the number of unicast packets delivered, the number of packets delivered to each node, the signals received and forwarded to the medium access control (MAC) layer, and the change in energy consumption with variation in transmission range, have shown that the proposed algorithm is capable of successfully avoiding congestion in typical healthcare WSNs requiring a reliable congestion control mechanism.

A generic model for optimizing single-hop transmission policy of replenishable sensors

Energy harvesting from the working environment has received increasing attention in the research of wireless sensor networks. Recent developments in this area can be used to replenish the power supply of sensors. However, power management is still a crucial issue for such networks due to the uncertainty of stochastic replenishment. In this paper, we propose a generic mathematical framework to characterize the policy for single hop transmission over a replenishable sensor network. Firstly, we introduce a Markov chain model to describe different modes of energy renewal. Then, we derive the optimal transmission policy for sensors with different energy budgets. Depending on the energy status of a sensor and the reward for successfully transmitting a message, we prove the existence of optimal thresholds that maximize the average reward rate. Our results are quite general since the reward values can be made application-specific for different design objectives. Compared with the unconditional transmit-all policy, which transmits every message as long as the energy storage is positive, the proposed optimal transmission policy is shown to achieve significant gains in the average reward rate.

A Power-Saving Data Aggregation Algorithm for Byzantine Faults in Wireless Sensor Networks

The wireless sensor network is a resource-constrained self-organizing system that consists of a large number of tiny sensor nodes. Due to the low-cost and low-power nature of sensor nodes, sensor nodes are failure-prone when sensing and processing data. Most presented fault-tolerant research for wireless sensor networks focused on crash faults or power faults and less on Byzantine faults. Hence, in this paper, we propose a power-saving data aggregation algorithm for Byzantine faults to provide power savings and high success rates even in the environment with high fault rates. The algorithm utilizes the concept of Byzantine masking quorum systems to mask the erroneous values and to finally determine the correct value. Our simulation results demonstrate that when the fault rate of sensor nodes is up to 50%, our algorithm still has 48% success rate to obtain the correct value. Under the same condition, other fault-tolerant algorithms are almost failed.

EPet: A Physical Game Based on Wireless Sensor Networks

This paper describes ePet, a novel multi-player physical game based on the WSN (Wireless Sensor Network). ePet shifts the traditional virtual pet games to the real world, featuring with the popular RPG (Role-Playing Game) elements. The game, capitalizing on the wireless communication, mobile computing, and sensing ability, can be played both indoors and outdoors, and thus gives players a new exciting gaming experience that profits by the blend of real and virtual game elements. The physical game acquires physical interactions among players, which can bring exciting and novel features to the game and more importantly, avoids some problems caused by traditional computer games such as health problems. The WSN is a promising technology for developing physical games. Although there is already some research and applications of WSN based physical games, the major advantages of the WSN (e.g. wireless communication, mobile computing, and sensing ability) are not fully cultivated in these gaming applications. ePet, which takes good advantages of both the WSN and traditional computer games, simulates a pet both indoors and outdoors. The pet has two life modes: Peaceful Life Mode (PLM) and Aggressive Life Mode (ALM). In the PLM, ePet simulates the physiological activities of a real pet such as hunger and easily getting flu when it is cold in the real world. Moreover, the pet can date with other pets to increase its physiological values. In the ALM, the pet is a character of an RPG controlled by the player and the pet can have a fight with other pets, from which the pet gains experience for level up. This ALM is similar to the computer RPG games but relatively novel in WSN based games. All of the above features are enabled by the WSN technology. For the two life modes, a friend-making protocol and an RPG battle protocol are designed respectively. The architecture design and implementation of ePet are described in detailed. Unlike traditional WSN based games, ePet does not need a centralized base station to organize the network. To implement a self-adaptive wireless sensor network in which each node has a similar functionality, and solve the network conflict problems in the WSN communications, a multi-hop communication routing protocol is designed for ePet. Furthermore, a PC application was developed as the game interface, from which players can check out the ePet's properties and interact with ePet. It makes ePet more attractive than traditional WSN based games without losing WSN's advantages.

On the energy consumption of Pure and Slotted Aloha based RFID anti-collision protocols

A recent development in wireless sensor networks (WSNs) research is to equip sensor nodes with an RFID reader so that they can be used to track animate or in-animate RFID tagged objects. A key problem in such networks, however, is the energy efficiency of current RFID anti-collision protocols. Specifically, the energy cost incurred by a RFID reader to read and monitor n tags.This paper, therefore, aims to identify the most energy efficient variant among 12 Pure and Slotted Aloha based RFID anti-collision protocols. We present an analytical methodology that evaluates the energy consumed in the following phases: (i) success, (ii) collision, and (iii) idle listening. We first calculate the delay of each phase and then use it to formulate the energy consumption, battery lifetime, and battery wastage of all variants. We found that the Pure Aloha with fast mode consumes the lowest energy and is suitable for tag identification. However, none of the protocols promises energy efficient monitoring of identified tags. In other words, the reader is required to re-read all tags every time to sense their presence; a process that consumes a significant amount of energy.

Intelligent actor mobility in wireless sensor and actor networks

In wireless sensor and actor network research, the commonly used mobility models for a mobile actor are random walk model, random waypoint mobility model, or variants thereof. For a fully connected network, the choice of mobility model for the actor is not critical because, there is at least one assured path from the sensor nodes to the actor node. But, for a sparsely connected network where information cannot propagate beyond a cluster, random movement of the actor may not be the best choice to maximize event detection and subsequent action. This paper presents static and dynamic intelligent mobility models that are based on the inherent clusters’ information of a sparsely connected network. Simulation results validate the idea behind the intelligent mobility models and provide insights into the applicability of these mobility models in different application scenarios.

Dynamic duty cycle and adaptive contention window based QoS-MAC protocol for wireless multimedia sensor networks

Rapid penetration of small, customized wireless devices and enormous growth of wireless communication technologies has already set the stage for large-scale deployment of wireless sensor networks. While the need to minimize the energy consumption has driven significant researches in wireless sensor networks, offering some precise quality of service (QoS) for multimedia transmission over sensor networks has not received significant attention. However, the emerging new applications like video surveillance, telemedicine and traffic monitoring needs transmission of wireless multimedia over sensor networks. Naturally, offering some better QoS for wireless multimedia over sensor networks raises significant challenges. The network needs to cope up with battery-constraints, while providing improved QoS (end-to-end delay and bandwidth requirement). This calls for a suitable sensory MAC protocol capable of achieving application-specific QoS. In this paper, we have proposed a new QoS-based sensory MAC protocol, which not only adapts to application-oriented QoS, but also attempts to conserve energy without violating QoS-constraints. Performance modeling, analysis and simulation results demonstrate that the proposed protocol is capable of providing lower delay and better throughput, at the cost of reasonable energy consumption, in comparison to other existing sensory MAC protocols.

Security software engineering in wireless sensor networks

Th ee ngineering of security is an essential discipline in software engineering. It requires one to embrace a holistic approach, as any weakness along the engineering process of the system may lead to future security breaches. It is in general difficult to achieve and becomes particularly acute in wireless sensor networks, owing to the stringent limitations in communication an dc omputational power. We survey the current state of the art on this topic and set forth issues that require further study. The analysis of current work covers general security issues of wireless sensor network research and discusse st he present achievements for engineering security with regards to earlier surveys in this domain. We also cover security capabilities of major implementation platforms, namely TinyOS and Sun SPOT TM ,a ndpresent available and required mechanisms that will become essential for software engineers.

Clique-based group key assignment in Wireless Sensor Networks

Security has become the corner stone of research in Wireless Sensor Networks (WSNs). Watchdog-based-monitoring systems require pairwise-connectivity of group-members to avoid information asymmetry attacks. Existing group-key protocols in literature don't address this requirement. Although, pairwise-key protocols resolve this drawback, they are highly restrictive and impose substantial storage overhead. Additionally, messages encrypted with pairwise-keys render monitoring systems useless. In this paper, we propose CAGE – a novel, distributed, clique-based group-key protocol that strikes an optimal balance between pairwise-key and group-key protocols. We then present E-CAGE, an improvisation of CAGE that mitigates computation-time to achieve the same results as CAGE.

The impact of fading and shadowing on the network performance of wireless sensor networks

Most ad hoc and sensor network research assumes idealised radio propagation models without considering fading and shadowing effects. Experimental results have shown that many well-designed protocols will fail simply because of fading and shadowing experienced in a realistic wireless environment. While fading and shadowing for radio propagation are well understood in the wireless communication community, they are rarely studied in network level research for wireless sensor networks. This paper studies the fading and shadowing effects on the performance of different systems for wireless sensor networks. We show that fading and shadowing can have a significant influence on network performance. We study and compare network performance for three different systems: (1) a multichannel CDMA system; (2) a pure CDMA system; (3) a contention-based system. Through discrete event simulation (using ns-2), we show that the multichannel CDMA system outperforms the pure CDMA system as well as the contention-based system under fading and shadowing environments.

Fuzzy Logic Control Based QoS Management in Wireless Sensor/Actuator Networks.

Wireless sensor/actuator networks (WSANs) are emerging rapidly as a newgeneration of sensor networks. Despite intensive research in wireless sensor networks(WSNs), limited work has been found in the open literature in the field of WSANs. Inparticular, quality-of-service (QoS) management in WSANs remains an important issue yetto be investigated. As an attempt in this direction, this paper develops a fuzzy logic controlbased QoS management (FLC-QM) scheme for WSANs with constrained resources and indynamic and unpredictable environments. Taking advantage of the feedback controltechnology, this scheme deals with the impact of unpredictable changes in traffic load on theQoS of WSANs. It utilizes a fuzzy logic controller inside each source sensor node to adaptsampling period to the deadline miss ratio associated with data transmission from the sensorto the actuator. The deadline miss ratio is maintained at a pre-determined desired level sothat the required QoS can be achieved. The FLC-QM has the advantages of generality,scalability, and simplicity. Simulation results show that the FLC-QM can provide WSANswith QoS support.

Efficiently reconfigurable backbones for wireless sensor networks

We present the definition and performance evaluation of a protocol for building and maintaining a connected backbone among the nodes of a wireless sensor networks (WSN). Building backbones first, and then coping with network dynamics is typical of protocols for backbone formation. Rules for building the backbone, however, do not take into account the following network dynamics explicitly. This makes maintaining a connected backbone quite costly, especially in terms of reorganization time, overhead and energy consumption. Our protocol includes in the backbone forming operations a fail-safe mechanism for dealing with the addition and the removal of nodes, which are typical events in a WSN. More specifically, the network is kept partitioned into clusters that are cliques, i.e., nodes in each cluster are directly connected to each others. Therefore, removing a node does not disrupt a cluster, and adding one requires simple operations for checking node admission to the cluster. The protocol, termed CC (“double C”, for clique clustering), comprises three phases, each designed to render the operations of the others swift and efficient. The first phase partitions the network into clusters that are cliques. Clusters are then joined to form a backbone that is provably connected. Finally, the third, more on-line phase, maintains the backbone connected in face of node additions and removals. We compare the performance of CC with that of DMAC, a protocol that has been previously proposed for building and maintaining clusters and backbones in presence of network dynamics. Our comparison concerns metrics that are central to WSN research, such as time for clustering and backbone reorganization, corresponding overhead, extent of the reorganization (i.e., number of nodes involved in it), and properties of the resulting backbone, such as its size, backbone route length, number of gateways and nodes per cluster. Our ns2-based simulation results show that the design criteria chosen for CC are effective in producing backbones that can be reconfigured quickly and with remarkably lower overhead.

Distributed power control algorithm based on game theory for wireless sensor networks

Energy saving is the most important issue in research and development for wireless sensor networks. A power control mechanism can reduce the power consumption of the whole network. Because the character of wireless sensor networks is restrictive energy, this paper proposes a distributed power control algorithm based on game theory for wireless sensor networks which objects of which are reducing power consumption and decreasing overhead and increasing network lifetime. The game theory and OPNET simulation shows that the power control algorithm converges to a Nash Equilibrium when decisions are updated according to a better response dynamic.

A lightweight encryption and authentication scheme for wireless sensor networks

The research of Wireless Sensor Networks (WSNs) has recently received a strong boost from IEEE 802.15.4 task group, which focuses on the specifications for low rate wireless personal area networks. Another important driving force of WSNs is the ZigBee Alliance, an industrial alliance concentrating on WSNs. This paper addresses the security of WSNs with respect to the protocol stack defined by IEEE 802.15.4 and the ZigBee Alliance. Some security problems are identified and remedies are suggested. A new security architecture based on a lightweight public key scheme, called Derivable Public Key (DPK), is proposed. The DPK scheme significantly simplifies the public key operations and reduces the related cost by eliminating the need for distributing and storing public keys other than the one from the trust centre. It makes possible to support authentications for multicast/broadcast communications in WSNs, which are not available and account for many attacks so far.