NDLI: Spectrum-shaping method to improve spectral efficiency of OFDM systems

Content Provider	IEEE Xplore Digital Library
Author	Izuka, N. Daido, Y. Mizuno, S. Yamakita, Y.
Copyright Year	2002
Description	Author affiliation: Japan Telecom, Tokyo, Japan (Izuka, N.)
Abstract	This paper proposes a spectrum-shaping filter for an OFDM signal. In the proposed method, the transmitted signal after multi-carrier modulation with the inverse Fourier transform is spectrally shaped by root-roll-off filters, and the received signal before Fourier transform is also shaped by the filters. An out-of-band emission level can be significantly reduced under the condition that the transmitted data can be perfectly recovered. The paper also describes an optimized impulse response of the filter to reduce the emission level. The resultant. filter has a new impulse response different from the root-roll-off filter. The effective roll-off factor of 0.1 and the emission level of less than -100 dB are obtained with the optimization when the number of filter taps is 201 at an over-sampling rate of 4. We calculate output power spectra with the proposed filter and a conventional raised cosine window in the time domain. The calculation results show that the signal bandwidth with the proposed method can be less than one third of the bandwidth with the conventional method at an emission level of -60 dB. Therefore, the proposed method can significantly improve the spectral efficiency of OFDM systems.
Starting Page	234
Ending Page	238
File Size	264021
Page Count	5
File Format	PDF
ISBN	0780375106
DOI	10.1109/ICCS.2002.1182472
Language	English
Publisher	Institute of Electrical and Electronics Engineers, Inc. (IEEE)
Publisher Date	2002-11-28
Publisher Place	Singapore
Access Restriction	Subscribed
Rights Holder	Institute of Electrical and Electronics Engineers, Inc. (IEEE)
Subject Keyword	Filters Bandwidth Modems Wireless LAN OFDM modulation Fourier transforms Streaming media Demodulation Power generation Telecommunications
Content Type	Text
Resource Type	Article

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