1,721,014 research outputs found
Low-Power IoT Environmental Monitoring and Smart Agriculture for Unconnected Rural Areas
No full textThis paper considers massive IoT devices
deployed in remote areas without terrestrial Internet
connectivity. IoT devices use sensors for continuously
monitoring ground data for smart agriculture and
environmental purposes. We connect these sensors to the
Internet via an aerial system based on Unmanned Aerial
Vehicle (UAV), High-Altitude Platform Station (HAPS), or
cubesat. Then, our particular focus is on using a UAV flying
over the remote area that receives data from distributed IoT
devices on the ground. An opportunistic protocol has been
introduced that is based on the synchronization of sensor
transmission to be consistent with the UAV pass close to them.
A model has allowed validating the applicability of this scheme
depending on a set of parameters, including the distance to be
covered. Finally, a preliminary experimental testbed has been
built to verify a path loss model in a benchmark configuration
with the gateway on the ground. This experiment will be
replicated using the gateway onboard the UAV
Detail-preserving segmentation of polarimetric SAR imagery
No full textPolarimetric SAR data help researchers understand and quantify the scattering properties of natural scenes, and their variability under different conditions, better than single polarization SAR data. In this paper, we propose two detail-preserving segmentation algorithms for multiband images and evaluate their performance using real multi-frequency multi-polarization SAR complex data. Adaptive neighborhood structures are selected for modeling the polarimetric complex amplitudes and the region labels, and for achieving detail preservation. Experimental results obtained from multi-band and multi-polarization SIR-C data, selected for archaeological applications studies, show that the novel schemes produce significant visual improvements for detail preservation, and exhibit equivalent or higher classification performance with respect to the classical classification schemes
Design and implementation of a new scheduler for enhancing multi-rate fairness in IEEE 802.16
No full textWithout the definition of a mandatory scheduling algorithm for channel resource assignment, WiMAX is open to Quality of Service (QoS) enhancements by research groups and developers, at the aim of managing heterogeneous flows with different QoS requirements. Furthermore, besides performance enhancement, another key issue arises for QoS delivery: it is known as multi-rate fairness and it deals with efficient resource allocation for providing sufficient bandwidth to high rate flows, without penalizing low rate ones. In this paper, uplink scheduling algorithms are studied and an innovative solution is proposed to achieve performance enhancement, multi-rate fairness and improved QoS management. After an overview of the state of the art, two scheduling algorithms based on Deficit Round Robin are studied, implemented and tested in NS2 simulator. The schedulers are validated and compared through exhaustive simulations, showing the benefits coming from the adoption of the proposed scheduling mechanism
TV as an experience conveyer for better acceptance of ICT services by older adults
No full textIn today’s society, the average age of the population is constantly increasing, together with the need to assist them through specific social services. Information technologies can be exploited to help monitoring pathologies in long-term care programs and can offer very useful tools to empower social inclusion and independent living. However, such tools should be carefully designed in order to be easily accepted by that part of population that is not familiar with digital technologies. Focusing on the challenge of providing ICT services through easier forms of interaction, this paper proposes a new e-service provisioning model that adopts a “hidden” computer as a flexible platform to provide social e-services. It adopts the TV as the most familiar interface for info-marginalized audiences, with a set of input/output devices to ease the interaction. Two platforms, specifically a TV box and an all-in-one touchscreen, have been implemented and evaluated with older adults, retrieving their opinions and feedback. Results show that the proposed solutions help to decrease the usual reluctance of seniors with respect to ICT, thanks to more familiar and easier forms of interaction able to reduce the digital gap toward new communications paradigm
Edge-preserving classification of multifrequency multipolarization SAR images
No full textTwo edge-preserving segmentation algorithms for multiband images are proposed in this paper. In particular, when dealing with multi-polarization SAR data, adaptive neighborhood structures are selected for modeling polarimetric complex amplitudes and region labels, and for achieving detail-preservation. Experimental results show that the novel schemes produce significant visual improvements for detail preservation, and exhibit equivalent or higher classification performance with respect to the classical classification schemes. These results have been obtained from multi-band, polarimetric SAR SIR-C data, selected for archaeological application studies
A new NS2 tool to investigate QoS management over mobile WiMAX
No full textWiMAX is one of the most interesting solutions for broadband wireless access, supporting multimedia traffics and applications through an appropriate QoS flow management both for fixed and mobile devices. To study its performance and to test new functionalities, simulation tools play a central role. In this paper we propose a new simulation module compliant to IEEE 802.16. Our key contribution is to offer the research community a useful tool for the investigation of QoS management on mobility in the WiMAX scenario. The developed tool includes the implementation of five QoS classes and of handover procedures. This module is validated and tested through exhaustive simulations, showing its conformance with the defined specifications. Copyright © 2011 ICST.WiMAX is one of the most interesting solutions for broadband wireless access, supporting multimedia traffics and applications through an appropriate QoS flow management both for fixed and mobile devices. To study its performance and to test new functionalities, simulation tools play a central role. In this paper we propose a new simulation module compliant to IEEE 802.16.
Our key contribution is to offer the research community a useful tool for the investigation of QoS management on mobility in the WiMAX scenario. The developed tool includes the implementation of five QoS classes and of handover procedures.
This module is validated and tested through exhaustive simulations, showing its conformance with the defined specifications
Integration of Video and Data Bursty Traffics in Wireless ATM Networks
No full textFuture wireless systems will allow a mobile access to Asynchronous Transfer Mode (ATM) networks. Towards this end, one of the main problems is the management of different traffics, each of them having specific Quality of Service (QoS) requirements. This paper proposes a novel Medium Access Control (MAC) protocol coordinated by a controller at the access point. In particular, a polling technique is considered to enable cyclically the transmissions of different terminals. The maximum number of packets that each source can send at each cycle is regulated by a token bucket scheme. We have considered the joint management of real time-Variable Bit Rate (rt-VBR) traffics and bursty Available Bit Rate (ABR) traffics. The controller estimates the congestion of the rt-VBR buffers and accordingly adapts the cycle order. The obtained MAC scheme, called Adaptive Token Bucket - priority based Round Robin (ATB-RR), has permitted to achieve satisfactory QoS levels for both rt-VBR and ABR traffics also in the presence of a scenario with mixed real-time sources
Analysis of Downlink Scheduling for Web Traffics in 2G and 2.5G Mobile Networks
No full textThis paper compares two possible scenarios for mobile Internet surfing according to the Personalised Access to Local Information and services for tOurists (PALIO) Project (IST-1999-20656). In particular, we consider WAP phones with Short Message Service (SMS) and Personal Digital Assistants (PDA) with General Packet Radio Service (GPRS). Suitable round robin scheduling schemes are analyzed for downlink transmissions. Part of this work has been also contributed to the COST 273 Project
A DCT-based adaptive compression algorithm customized for radar imagery
No full textIn this paper an adaptive DCT-based image compression algorithm for radar images is proposed, tested and compared to JPEG and to classical coding algorithms for remote sensing imagery. The Modified Adaptive Discrete Cosine Transform (MADCT) scheme is proposed, which allows to classify each image block by means of a threshold criterion based on AC and DC activity. The strategy of transmission of the DCT coefficients, the recovering process of blocks incorrectly discarded, and the bit-allocation phase have been properly designed to provide high compression of two classes of images: X-band real-aperture radar images for ship traffic control, and SAR images for browsing applications. The experimental results, in terms of PSNR and compression ratio, prove the superiority of the novel scheme with respect to standard coding techniques
- …
