Search results for " sensor network"
showing 10 items of 373 documents
Hybrid Observer for Indoor Localization with Random Time-of-Arrival Measurments
2018
In this work an indoor position estimation algorithm will be proposed. The position will be measured by means of a sensor network composed by fixed beacons placed on the indoor environment and a mobile beacon mounted on the object to be tracked. The mobile beacon communicates with all the fixed beacons by means of ultra wide-band signals, and the distance between them is computed by means of time of flight techniques. Moreover, inertial measurements will be used when the position measurements are not available. Two main problems will be considered in the proposed architecture: the fact that the beacons work with a lower update rate than the IMU, and that the mobile beacon can comunicate wit…
Time synchronization enhancements in wireless networks with ultra wide band communications
2022
The emergence of low cost Ultra Wide Band (UWB) transceivers has enabled the implementation of Wireless Sensor Networks (WSN) based on this communication technology. These networks are composed of distributed autonomous low cost nodes (also known as motes) with their own processing unit, memory and communications. Usually these nodes are power-limited and due to the poor performance and quality of their clocks, time synchronization is in the order of milliseconds and in some specific scenarios till microseconds. The integration of commercial UWB transceivers in these nodes can improve the synchronization accuracy. In particular, we focus on WSN nodes based on off-the-shelf commercial produc…
Real-Life Experiments based on IQRF IoT Testbed: From Sensors to Cloud
2018
Master's thesis Information- and communication technology IKT590 - University of Agder 2018 Internet of things (IoT) is the next generation internet technology which connects devices and objects intelligently to control data collected by diverse types of sensors, radio frequency identification and other physical objects. To address the challenges in IoT such as integrating artificial intelligent techniques with IoT concept, developing green IoT technologies and combining IoT and cloud computing, various platforms which support reliable and low power wireless connectivity are required. IQRF is a recently developed platform for wireless connectivity. It provides low power, low speed, reliable…
Capacity and Energy-Consumption Optimization for the Cluster-Tree Topology in IEEE 802.15.4
2011
International audience; 802.15.4 proposes to use a cluster-tree hierar- chy to organize the transmissions in Wireless Sensor Networks. In this letter, we propose a framework to analyze formally the capacity and the energy consumption of this structure. We derive a Mixed Integer Linear Programming (MILP) formulation to obtain a topology compliant with the standard. This formulation provides the optimal solution for the network capacity: this con- stitutes an upper bound for any distributed algorithms permitting to construct a cluster-tree. This framework can also be used to evaluate the capacity and to compare quantitatively different cluster-tree algorithms.
On-body and off-body transmit power control in IEEE 802.15.6 scheduled access networks
2014
Wireless Body Area Networks (WBANs) have received much attention due to the possibility to be used in healthcare applications. For these applications, energy saving is a critical issue, as in many cases, batteries cannot be easily replaced. A transmit power control scheme, able to adapt to the variations of the wireless body channel, will allow consistent energy saving and longer battery life. In this paper we propose a transmit power control scheme suitable for IEEE 802.15.6 narrowband scheduled access networks, in which the transmission power is modulated frame by frame according to a run-time estimation of the channel propagation conditions. A simple and effective line search algorithm i…
Design of energy efficient MAC protocols in wireless sensor networks
2014
Masteroppgave i Informasjons- og kommunikasjonsteknologi IKT590 Universitetet i Agder 2014 Wireless sensor networks (WSNs) have been used in variety of applications such as in military and defense, process control industry and health monitoring applications. In WSNs, sensors are in small size with limited battery capacity and idle listening is a crucial problem which consumes more energy. Duty cycling (DC) is a technique which is used in many medium access control (MAC) protocols to reduce idle listening. In this thesis, we propose an asynchronous DC protocol, namely energy balancing asynchronous cooperative transmission medium access control (EB-ACT-MAC), which balances the remaining energ…
Gatherer: an environmental monitoring application based on IPv6 using wireless sensor networks
2013
In this paper, we present an environmental monitoring application based on IPv6 using wireless sensor networks. We show the guidelines to connect this network to internet using the 6LowPAN standard with a real prototype in the evolution of the Internet of Things. We assign a unique IPv6 address to the different nodes motes of the network. Gatherer is based on TinyOS using IPv6 and UDP protocols and allows the data gathering of temperature and relative humidity from the different motes, requesting specific data from individual motes when required, increasing the accuracy of the measures. We compare the performance of our IPv6-based proposed application against others and show the benefits of…
Low Complexity Image Compression using Pruned 8-point DCT Approximation in Wireless Visual Sensor Networks
2017
International audience; Since the transmission of the uncompressed image in the context of wireless visual sensor networks (WVSNs) consumes less energy than transmitting the compressed image, developing energy-aware compression algorithms are mandatory to extend the camera node's lifetime and thereby the whole network lifetime. The present paper studies a low-complexity image compression algorithm in the context of WVSNs. This algorithm consists of applying a pruning approach on a DCT approximation transform. The scheme is investigated in terms of computation cycles, processing time, energy consumption and image quality. Experimental works are conducted using the Atmel Atmega128 processor o…
Wireless energy and information transmission in FSO and RF-FSO links
2018
We propose and analyze a wireless energy and information transmission scheme in free-space optical (FSO) links. The results are presented for both quasi-static and fast-fading conditions. We derive closed-form expressions for throughput, outage probability, and optimal power allocation optimizing the system throughput/outage probability. Finally, we complement the FSO link with an additional radio frequency (RF) link to create a hybrid RF-FSO system and reduce the system outage probability. The results show that joint implementation of the RF and FSO links leads to considerable performance improvement, compared to the cases with only FSO-based communication.
Performance Study of Non-beaconed and Beacon-Enabled Modes in IEEE 802.15.4 under Bluetooth Interference
2008
The IEEE 802.15.4 protocol is a flexible technology with great potential for wireless sensor networks applications. The standard distinguishes two network modes; beacon-enabled and nonbeacon-enabled. In this paper, the performance study of beaconed and non-beaconed modes of IEEE 802.15.4 is evaluated using on site PER measurements. The tests are carryout in an urban outdoor environment with commercial available equipment. Likewise, the impact of Bluetooth interference over IEEE 802.15.4 modes is evaluated. The results show that Bluetooth interference and the mode selected have effects over the PER. Furthermore, for distances between 3 to 10 meters the PER doesn't show significance distance …