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Mobile robots can be used to deploy static wireless sensor nodes to achieve the coverage and connectivity requirements of the applications considered. Many solutions have been provided in the literature to compute the set of locations where the sensor nodes should be placed. In this paper, we show how this set of locations can be used by a mobile robot to optimize its tour to deploy the sensor nodes...
In this article, we study the issue of delay optimization and energy efficiency in grid wireless sensor networks (WSNs). We focus on STDMA (Spatial reuse - Time Division Multiple Access) scheduling, where a predefined cycle is repeated, and where each node has fixed transmission opportunities during specific slots of the cycle (defined by colors). We assume a STDMA algorithm that takes advantage of...
The unlicensed spectrum bands become overcrowded causing an increased level of interference for current wireless sensor nodes. Cognitive Radio Sensor Networks (CRSNs) overcome this problem by allowing sensor nodes to access opportunistically the underutilized licensed spectrum bands. The sink assigns the spectrum holes to the secondary users (SUs). Therefore, it must rely on reliable information about...
Current Wireless Sensor Networks (WSNs) are deployed over unlicensed frequency bands that face an increased level of interference from various wireless systems. Cognitive Radio Sensor Networks (CRSNs) overcome this problem by allowing sensor nodes to access new spectrum bands to minimize interferences. In this paper, we focus on the MultiChannel Time Slot Assignment problem (MC-TSA) in CRSNs. Each...
The distributed virtual forces deployment algorithm provides a very good area coverage and guarantees network connectivity for a sufficient number of sensor nodes. It relies on local information between neighboring sensor nodes. However, its main drawback is node oscillations and hence a high amount of sensor node energy wasted. The grid based strategy divides the monitored area into virtual cells...
In this work, we study raw convergecast in multichannel wireless sensor networks (WSNs) where the sink may be equipped with multiple radio interfaces. We propose Wave, a simple and efficient distributed joint channel and time slot assignment. We evaluate the number of slots needed to complete the convergecast by simulation and compare it to the optimal schedule and to a centralized solution.
A typical task in wireless sensor networks (WSNs) is to collect data from sensor nodes towards one or many sinks in a multi-hop convergecast structure. In this paper, we focus on the data gathering problem with differentiated traffic, each addressed to a specific sink in multichannel WSNs. In order to find a collision-free optimized multichannel time slot assignment that minimizes the data gathering...
In many applications (e.g military, environment monitoring), wireless sensors are randomly deployed in a given area. Unfortunately, this deployment is not efficient enough to ensure area coverage and network connectivity. Algorithms based on Virtual Forces are used to improve the random initial deployment. In this paper, we want to ensure coverage and network connectivity in a given area containing...
In aerospace applications, wireless sensor networks (WSNs) collect data from sensor nodes towards a sink in a multi-hop convergecast structure. The throughput requirement of these applications is difficult to meet with a single wireless channel. That is why, in this paper, we focus on a multichannel time slot assignment that minimizes the data gathering cycle. We first formalize the problem as a linear...
Wireless sensor networks (WSN) are generally randomly deployed in a given area. This initial deployment does not achieve neither area coverage, nor network connectivity. Thus, a redeployment algorithm has to be applied in order to achieve these two goals. This algorithm should meet performance criteria like saving energy and achieving stability. Our contribution in this paper is the design of DVFA,...
Wireless sensor networks, WSNs, are an efficient way to deal with low-rate communications in confined environments such as mines or nuclear power plants because of their simplicity of deployment and low cost. In these application domains, WSNs are used to gather data from sensor nodes towards a sink in a multi-hop convergecast structure. In this paper, we focus on a traffic-aware time slot assignment...
In data gathering applications which is a typical application paradigm in wireless sensor networks, sensor nodes may have different traffic demands. Assigning equal channel access to each node may lead to congestion, inefficient use of the bandwidth and decrease of the application performance. In this paper, we prove that the time slot assignment problem is NP-complete when p-hop nodes are not assigned...
Industrial applications have specific needs which require dedicated solutions. On the one hand, MEMS can be used as affordable and tailored solution while on the other hand, wireless sensor networks (WSNs) enhance the mobility and give more freedom in the design of the overall architecture. Integrating these two technologies would allow more optimal solutions in terms of adaptability, ease of deployment...
Wireless sensor networks are usually randomly deployed in the monitored region. This initial deployment does neither achieve area coverage, nor ensure network connectivity. Thus, a redeployment algorithm has to be applied in order to meet these two requirements. In this paper, we overview existing centralized redeployment algorithms such as virtual forces or particle swarm optimization category, as...
The myriad of potential applications supported by wireless sensor networks (WSNs) has generated much interest from the research community. Various applications range from small size low industrial monitoring to large scale energy constrained environmental monitoring. In all cases, an operational network is required to fulfill the application missions. In addition, energy consumption of nodes is a...
Micaz motes can communicate on multiple frequencies as specified in the 802.15.4 standard. This reality has given birth to multichannel communication paradigm in Wireless Sensor Networks (WSNs). Obviously, multichannel communication mitigates interferences, jamming and congestion, whereas it brings also challenging issues. Thus, in this paper, we are motivated to draw a picture of multichannel assignment...
Coloring is used in wireless networks to improve communication efficiency, mainly in terms of bandwidth, energy and possibly end-to-end delays. In this paper, we define the h-hop node coloring problem, with h any positive integer, adapted to two types of applications in wireless networks. We specify coloring in both general mode for general applications and strategic mode for data gathering applications...
In this article, we describe experiments with the multicast protocol MOST (Multicast Overlay minimum Spanning Tree) on a real testbed. The testbed is a wireless multi-hop network with nodes running a MANET protocol, the OLSRv2 routing protocol, and with IEEE 802.11g hardware. We present our specification and implementation of MOST for OLSRv2. Its main feature is to build an (unicast) overlay tree...
Clustering schemes offer a practical way of providing scalability when dealing with large and dense Mobile Ad hoc Networks (MANETs). The feasibility of clustering can be determined by the complexity of the cluster head selection. Optimizing the cluster head selection allows for the network to be more efficient by minimizing the signaling overhead while ensuring that the network connectivity is maintained...
In wireless sensor networks, energy efficiency is achieved by making nodes sleep. In this paper, we propose SERENA, a node activity scheduling algorithm based on three-hop coloring. We study the performance of SERENA by simulating the conditions of a realistic environment including unidirectional links. The existence of unidirectional links causes color conflicts, which can be solved by exploiting...
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