J. Lopez-Perez
University of Las Palmas de Gran Canaria
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Featured researches published by J. Lopez-Perez.
ursi general assembly and scientific symposium | 2011
Iván A. Pérez-Álvarez; S. Zazo-Bello; Mounir Ghogho; J. Lopez-Perez
Achieving reliable communication over HF channels is known to be challenging due to the particularly hostile propagation medium. To address this problem, diversity techniques were shown to be promising. In this paper, we demonstrate through experimental results the benefits of different diversity strategies when applied to multi-input-multi-output (MIMO) multicarrier systems. The performance gains of polarisation, space and frequency diversities are quantified using different measurement campaigns.
European Transactions on Telecommunications | 2006
Héctor Santana-Sosa; S. Zazo-Bello; Iván A. Pérez-Álvarez; Ivana Raos; Eduardo Mendieta-Otero; J. Lopez-Perez
SUMMARYThe HF band data communication link has been traditionally desired by many of the large rangetransmission systemsalthough it is associated tounfavourable performancesas low transmission rate, largedelayandlowconfidenceintermsoflinkestablishmentandmaintenance.Althoughtransmissionrates maybe highenough totransmit digitalvoice, delay,usuallyover severalseconds, has beenthe mainhandicap tolet the systems provide interactive digital voice links. Indeed, there is no unclassified equipment with thiscapability.Themainachievementofthisproposalisthatweareabletoguaranteedigitalvoicetransmissionwith low latency, around 135ms (modemþcodec), providing a full interactive digital voice link.Performances of two new 2460bps HF modems are presented versus the 39-tone 2400bps MIL-STD-188-110A modem, working over an ITU-R moderate channel. Furthermore, these results are corroborated byreal tests carried out in a 1800Km link in the 18MHz band. Copyright # 2006 AEIT. 1. INTRODUCTION1.1. The HF channelIn the HF band (3–30MHz), long distance communica-tions are feasible, thanks to the use of the ionosphere aspassive reflector. However, the atmospheric nature of thisreflector makes the systems face a very hard communica-tionenvironment.Multipatheffects arealways present andhave to be considered in depth, besides the very fast time-varying channel characteristics.The main parameters used to measure channel behaviourare frequencycoherence ( f
military communications conference | 2007
J. Lopez-Perez; S. Zazo-Bello; Iván A. Pérez-Álvarez; Ivana Raos; E. Mendieta-Otero
Multi-carrier modulations are widely employed in HF communications, and particularly OFDM, mainly because their ease of generation by means of DFT and also their appealing properties that can turn a selective fading channel into a set of flat channels. In order to cope with deep nulls in the channel traditional approach has been the use of channel coding and interleaving, thus causing an increase in communication delay. For delay-sensitive applications, spreading schemes over OFDM, such as OFDM-CDM can be applied. If CSI is known at transmitter, system performance can be improved by BER-optimum power loading and channel matrix SVD decomposition of OFDM-CDM signal. These techniques are well suited to delay-sensitive applications as they incur in no further delays.
Ionospheric radio Systems and Techniques, 2009. (IRST 2009). The Institution of Engineering and Technology 11th International Conference on | 2009
Iván A. Pérez-Álvarez; J. Lopez-Perez; Santiago Zazo; Ivana Raos; B. Perez-Diaz; E. Jimenez-Yguacel
Ionospheric radio Systems and Techniques, 2009. (IRST 2009). The Institution of Engineering and Technology 11th International Conference on | 2009
B. Perez-Diaz; E. Jimenez-Yguacel; J. Lopez-Perez; Iván A. Pérez-Álvarez; S. Zazo-Bello; E. Mendieta-Otero
Ionospheric radio Systems and Techniques, 2009. (IRST 2009). The Institution of Engineering and Technology 11th International Conference on | 2009
C. Peco; Santiago Zazo; Iván A. Pérez-Álvarez; J. Lopez-Perez
International Conference on Ionospheric Radio Systems and Techniques (IRST) | 12th International Conference on Ionospheric Radio Systems and Techniques (IRST) | 15/05/2012 - 17/05/2012 | York, UK | 2012
Iván A. Pérez-Álvarez; S. Zazo; Mounir Ghogho; J. Lopez-Perez; B. Pérez-Díaz; E. Jiménez-Yguacel
Wireless Networks | 2011
José L. Sanz-González; Santiago Zazo; Iván A. Pérez-Álvarez; J. Lopez-Perez
Ionospheric Radio Systems and Techniques (IRST 2012), 12th IET International Conference on | 2012
J. Lopez-Perez; Laura Melián-Gutiérrez; Iván A. Pérez-Álvarez; Santiago Zazo; Ivana Raos; B. Perez-Diaz
Ionospheric radio Systems and Techniques, 2009. (IRST 2009). The Institution of Engineering and Technology 11th International Conference on | 2009
Santiago Zazo; Ivana Raos; J. Lopez-Perez; Iván A. Pérez-Álvarez; B. Perez-Diaz; E. Jimenez-Yguacel