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Sensor Nodes (SN) represent a tiny, inexpensive and main constituent part of Wireless Sensor Networks (WSN). As the main source of power supply of SNs is usually battery, which have a strictly limited capacity, the battery life extension is the main driver for energy-efficient WSN design. So, the crucial parameter for energy-efficient applications in WSN is to apply the techniques that greatly reduce...
When we try to use a sensor network outdoors, for purposes such as collecting information related to large-scale natural disasters and agricultural applications, it often happens that the communication distance is insufficient. Many sensor network users in Japan utilize sensor nodes that use 2.4 GHz frequency. The communication distance of these sensor nodes is short (a few hundred meters). Therefore,...
Wireless sensor networks (WSN) have received a lot of attention recently due to their wide applications such as target tracking, environment monitoring, and scientific exploration in dangerous environments. Secure time synchronization is a key service for wireless sensor networks (WSN). Time synchronization protocol synchronizes local clocks of group nodes to a common clock. In group, some of the...
Sensor nodes compensate clock drift with guard times (GT), which results in idle listening. By applying prediction methods nodes can limit drift uncertainty for upcoming frames and shorten GT. However, a common solution based on linear regression requires floating-point arithmetic, i.e. large computation and memory overhead. We present an approach for drift prediction based on moving average, which...
Localization services are one of the most important services provided by wireless sensor networks. In this paper, a relative-localization identification of random deployed non-anchored nodes will be presented. Based on relative RSSI information, the system can identify which sensor nodes are placed in locations planned on map. The method can let user put any nodes anywhere (random distributed), and...
Program codes running on the sensor nodes need to be updated from time to time to fix bugs, tune the parameters, insert new functions, or delete useless codes. In this paper, we propose a policy-based reprogramming framework that can optimize the reprogramming process based on the execution characteristics of modules that constitute the WSN applications. To accomplish this we model the characteristics...
For Wireless Sensor Networks (WSNs), utilizing the same set of measurement data for simultaneous localization and time synchronization is potentially useful for achieving higher estimation accuracy, lower communication overhead and power consumption. However, localization and time synchronization are traditionally treated as two separate problems. In this paper, we propose to use Semidefinite Programming...
Since the duty cycle of S-MAC is fixed and longer, it will cause longer idle time and latency of data packets under light loads. To solve these problems we present a new MAC protocol in which the sleep/wakeup schedules of the sensor nodes are adaptively determined, sensor nodes may sleep frequently. And also it minimizes control-packet overhead. Simulation shows that the new MAC is of significant...
Pairwise Broadcast is a novel low-power wireless sensor network clock synchronization method. A subset of sensor nodes are synchronized by overhearing the timing message exchanges of a pair of sensor nodes. Therefore, a group of sensor nodes can be synchronized without sending any extra messages. This paper mainly account for the problem that the original Pairwise Broadcast Synchronization in absence...
Monitoring of industrial and community environments and infrastructures are increasing targets for wireless sensor network (WSN) applications. Such applications are distributed by their nature and require essentially timing synchronization and location awareness of the sensor nodes. In this paper we present a WSN platform suitable for environment and condition monitoring applications. Time synchronization...
In this paper, we propose a new centralized routing protocol named WRP that aims at maximizing the network lifetime. In WRP, the sink node is assumed to be with more capabilities and basically collects each node's estimated wakeup time. This enables the sink node to estimate the wakeup times of all sensor nodes even if some of them are multi-hops away from the sink node. The estimated information...
Due to the ability of sensor nodes to collaborate, time synchronization is essential for many sensor network operations. This work presents a novel clock synchronization method for energy-constrained wireless sensor networks (WSNs). To conserve WSN energy, this study adopts the flooding time synchronization scheme based on one-way timing messages. Via the proposed approach, the maximum-likelihood...
Based on the analysis to the phenomenon and methods of denial-of-sleep attacking in wireless sensor network, a scheme is proposed employing fake schedule switch with RSSI measurement aid. The sensor nodes can reduce and weaken the harm from collision, exhaustion and broadcast attack and on the contrary make the attackers lose their energy quickly so as to die. Simulation results show that at a bit...
Large propagation delay and node movement are considered to be two significant attributes that differentiate an underwater wireless sensor network (UWSN) from a ground wireless sensor network (WSN). Considering the effects of both propagation delay and movement, we propose a time synchronization algorithm suitable for a UWSN. An underwater node can move out of and into another node's range frequently...
Time synchronization is an indispensable piece of infrastructure in sensor networks. As the limited resource of the sensor nodes, energy efficiency become a main concern of the wireless sensor networks. In this paper , a spanning subtree based event-triggered time synchronization algorithm for sensor networks is proposed. Firstly , a spanning tree construction starts and the spanning tree is divided...
We propose a new type of wireless sensor network system named die-hard sensor network. Conceptually, this system performs continuous monitoring without any maintenance, even if some sensor nodes die. A significant difference between our system and the ordinary wireless sensor networks is that each sensor node in our system should have an automatic sensing-function alternation mechanism in addition...
Providing a powerful synchronization system is one of the most important goals to be pursued if an efficient utilization of sensor networks has to be addressed. The basic concept behind a Wireless Sensor Network is to deploy a large number of sensor nodes able to acquire and process data. Most of WSNs applications require sensor nodes to maintain local clocks both to determine the events order and...
Collaborative beamforming has already demonstrated its potential of significant power savings in distributed sensor networks. In collaborative beamforming, the antennas of the sensor nodes form a distributed antenna array in an effort to direct the radiated energy to the desired direction and thus increase the overall power efficiency of the network. Existing studies, however, have not addressed several...
In this paper, we propose a variable packet length adaptive MAC Protocol (VPLA-MAC) for wireless sensor networks. VPLA-MAC is designed for clustering hierarchy networks based on the routing information collected from sensor nodes. A sensor node in cluster sends packet length and routing information to cluster head node, this cluster head node calculates the cycle length and selects nodes for data...
In this paper, we propose a new control method to cover ldquoholesrdquo in wireless sensor networks. Many applications often face the problem of holes when some sensor nodes are disabled from the collaboration due to their failures and misbehavior. These holes may occur dynamically, and such a problem cannot be solved completely by simply deploying more redundant sensors. With synchronization around...
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