Please use this identifier to cite or link to this item: http://hdl.handle.net/10553/46878
Title: Improved PPM modulations for high spectral efficiency IR-WLAN
Authors: Perez-Jimenez, Rafael 
Rabadan, Jose A. 
Melian, Victor M. 
Betancor, Manuel J.
UNESCO Clasification: 3307 Tecnología electrónica
Keywords: Infrared spectra
Optical receivers
Decision feedback equalizers
Gaussian noise
Interference, et al
Issue Date: 1996
Journal: IEEE International Symposium on Personal, Indoor and Mobile Radio Communications, PIMRC
Conference: Proceedings of the 1996 7th IEEE International Symposium on Personal, Indoor and Mobile Radio Communications, PIMRC'96. Part 3 (of 3) 
Abstract: This article presents a modified PPM modulation technique for infrared wireless LAN that improves the spectral efficiency of the system significantly. The resulting signal (improved PPM or IPPM), which is based on FQPSK IJF filters, is jitter- and ISI-free and can be recovered with any standard PPM receiver. In order to reduce the bandwidth a pulse-conformation system is added to the basic PPM emitter. It is based on a differential sub-codification of the original PPM signal. IPPM presents a waveform similar to the frequency response of a raised-cosine filter with /spl alpha/=0.25. This signal can be recovered with any standard PPM receiver. We have worked with a receiver that uses a maximum likelihood criterion with block decision. Measurements show that the bandwidth required for a 4-IPPM signal, with a rate of 2 Mb/s, is reduced to 3.6 MHz, for the same quality criterion of -21 dBr. The spectral efficiency for -21 dBr rises from 0.2 to 0.55 b/s/Hz. The performance of both PPM and IPPM modulation versus white Gaussian noise are similar (less than 1 dB difference). Both models are also equally sensitive to low frequency interference, results show that their behavior in a highly lit environment is similar. Their performance can be improved by the use of BDFE (block decision feedback equalizer) presenting also similar results. IPPM is more robust against jitter than PPM. Extensive simulation results show that the 4-IPPM scheme improves the performance against jitter of the basic 4-PPM 2 Mb/s around 3 dB for an error probability of 10/sup -6/.
URI: http://hdl.handle.net/10553/46878
ISBN: 0-7803-3692-5
DOI: 10.1109/PIMRC.1996.567560
Source: IEEE International Symposium on Personal, Indoor and Mobile Radio Communications, PIMRC,v. 1, p. 262-266
Appears in Collections:Actas de congresos
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