1,721,130 research outputs found
High-speed indoor wireless COFDM systems at 60 GHz: performance and design criteria
No full textWith the aim of defining system design criteria, the performance of a high-speed indoor wireless communication system using COFDM and working at 60 GHz is analyzed. An actual propagation environment, which has been characterized by means of a ray-tracing technique, is considered for the analysis. Suitable algorithms are introduced to evaluate the performance in this environment. The effects of antenna sectorization, OFDM clustering, frequency diversity and code choices are investigated and discussed. Moreover, a definition of coverage is proposed and discussed. The feasibility of a COFDM system for 155 Mbit/s ATM transmission with transmitter power of 10 dBm and an 80% coverage of the NLOS points in the scenario considered is shown in the results
Novel low complexity technique to reduce non-linear distortion effects in OFDM systems
No full textThis paper proposes a new technique to reduce non-linear distortion effects in Orthogonal Frequency Division Multiplexing (OFDM) systems. It exploits virtual carriers, which are modulated by using properly defined 'dummy symbols', to obtain a transmitted signal with reduced envelope variations. With this method no additional redundancy is introduced, thus preserving spectrum efficiency, and no changes at the receiver are required. To evaluate dummy symbols some optimization criteria are investigated; an optimum algorithm and a low complexity iterative algorithm are proposed and compared from the point of view of system performance. The effectiveness of this technique is tested by considering some typical High Power Amplifier (HPA) models and by evaluating performance degradation. A comparisons with other techniques proposed in the literature is also carried out
Wireless Multimedia Assessment with Traffic, Access and Transmission Protocols in Actual Environment at Millimeter Waves
No full textPerformance of UWB backscatter modulation in multi-tag RFID scenario using experimental data
No full textFuture advanced radio-frequency identification
(RFID) systems are expected to provide both identification and
high-definition localization of objects with improved reliability
and security while maintaining low power consumption and
cost. Ultrawide bandwidth (UWB) technology is a promising
solution for next generation RFID systems to overcome most
of the limitations of current narrow bandwidth RFID technology
such as: reduced area coverage, insufficient ranging resolution
for accurate localization, sensitivity to interference and scarce
multiple access capability. In this paper, the UWB technology is
applied to semi-passive RFID relying on backscatter modulation.
The potential performance of backscatter RFID communication
using UWB signals is investigated in terms of clutter suppression
and multiple access capability using both simulated and experimental
data
Enhanced Localization Coverage with Non-Regenerative UWB Relays
No full textPublication in the conference proceedings of EUSIPCO, Bucharest, Romania, 201
Fast ray-tracing characterization of indoor propagation channels at 60 GHz
No full textFor the design of high speed wireless networks, special attention has been paid to short range communication at 60 GHz due to the large bandwidth availability. In order to give proper channel characterization, a ray tracing method has been applied to a realistic environment. The large-scale received power as a function of receiver position is investigated in the presence of room furniture and a model for path-loss prediction based on the `room partitioning' is proposed. Moreover, due to the high absorption of materials at 60 Ghz, the characterization of the room coverage has been shown to be possible by considering only 1 or 2 reflections thus allowing fast ray-tracing prediction. Finally, wideband characterization is carried out in terms of RMS delay statistics in various situations and the effects of sectored antennas are investigated
Wideband indoor communication channels at 60 GHZ
No full textDesign of high quality, high speed wireless networks to connect mobile users requires large bandwidth availability. For this reason and with the aim of implementing new wireless systems, special attention has been paid to millimetre waves networks (e.g. at 60 GHz) based on short range communications. The paper presents some results concerning indoor channel characterisation. A ray tracing method has been applied to a realistic environment, with the view to define proper analytical models for propagation parameters. More precisely, large-scale received power, Rice factor, delay spread as a function of distance and small-scale variations statistics have been investigated in the presence and in the absence of room furnitures: a two-state model has been proposed and checked
Backscatter Communication Using Ultrawide Bandwidth Signals for RFID ApplicationsThe Internet of Things
No full textRFID technology for use in real-time object identification is being rapidly adopted in several fields such as logistic, automotive, surveillance, automation systems, etc. [1]. A radiofrequency identification (RFID) system consists of readers and tags applied to objects. The reader interrogates the tags via a wireless link to obtain the data stored on them. The cheapest RFID tags with the largest commercial potential are passive or semi-passive, and the energy necessary for tag–reader communication is harvested from the reader’s signal. Passive RFID tags are usually based on backscatter modulation, where the antenna reflection properties are changed according to information data [2]
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