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On the Use of Wavelet-Based Denoising to Improve Power Delay Profile Estimates from 1.8 GHz Indoor Wideband Measurements

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Abstract

This work presents an alternative processing scheme to improve measurement-based power delay profiles (PDP) estimates, using wavelet-based denoising. The usual PDP processing comprises cutting off all the data below a previously determined flat noise threshold. The proposed method is a more refined approach, since it tries to extract the noise from the measured data, keeping only the estimated signal. Wavelet denoising can be performed in many different ways, for it depends on several parameters, like the noise threshold selection rule, the wavelet function, the choice or not for a wavelet coefficients shrinkage and the number of decomposition levels. Several parameter combinations have been tested, in special for the Visu selection rule, which presented the best performance for the available data in the overall. Denoising was applied to real data from indoor environments, collected from wideband channel sounding surveys, centered at 1.8 GHz. Since frequency domain sounding has been carried out, denoising has been tested both directly over the frequency domain, and over the time–delay domain (PDP). The major result of the proposed processing was a qualitative improvement of the PDP, with smoother noise floors, and also with increases up to 8 dB on signal-to-noise ratios, in special for delay domain denoising.

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Authors and Affiliations

  1. Department of Electrical Engineering, Military Institute of Engineering, Pc Gen Tibúrcio, 80, Rio de Janeiro, RJ, 22290-270, Brazil

    M. H. C. Dias

  2. Center for Telecommunications Studies, Pontifical Catholic University of Rio de Janeiro, Rua Marquês de São Vicente, 225, Ed Kennedy, 7∘ andar, Rio de Janeiro, RJ, 22543-900, Brazil

    G. L. Siqueira

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  1. M. H. C. Dias
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  2. G. L. Siqueira
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Correspondence to M. H. C. Dias.

Additional information

Maurício H.C. Dias was born in São Paulo, SP, Brazil on 25 July 1970. He received a degree of Telecommunication Engineer and his M.Sc. degree from Military Institute of Engineering (IME) in 1992 and 1998 respectively. In 2003, he received the degree of D.Sc. from Pontifical Catholic University of Rio de Janeiro (PUC/Rio). Since then he is back to the Electrical Engineering Department (DE/3) at Military Institute of Engineering (IME), also in Rio de Janeiro, this time as teacher and researcher. He has published a few engineering papers on national periodicals, and has also presented some articles on national and international conferences. In 2001, he has been awarded together with professor Gláucio L. Siqueira for having presented the best graduate paper on the IEEE International Microwave and Optoelectronics Conference, at Belém, Brazil. His present research interests include wave propagation, electromagnetic compatibility, space-time signal processing and wavelet theory.

Gláucio L. Siqueira was born in Belo Horizonte, MG, Brazil on August, 1952. He received a degree of Electronic and Telecommunication Engineer from Pontifical Catholic University of Minas Gerais and a degree of Mathematician from Federal University of Minas Gerais in 1977 and 1978 respectively. In 1982 he received a degree of MSc from Campinas State University (UNICAMP). He received his Ph.D. degree in Electrical Engineering from University College London, England in 1989. Since them he is with Center for Telecommunication Studies (CETUC) at Pontifical Catholic University of Rio de Janeiro (PUC/Rio). He has published several research papers including two IEEE transactions, and was awarded a number of lecturing distinctions. His research interests include random media propagation, rain induced attenuation and mobile radio channel characterization and modeling. He is a member of IEEE since 1989.

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Dias, M.H.C., Siqueira, G.L. On the Use of Wavelet-Based Denoising to Improve Power Delay Profile Estimates from 1.8 GHz Indoor Wideband Measurements. Wireless Pers Commun 32, 153–175 (2005). https://doi.org/10.1007/s11277-005-2511-8

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