Orthogonal frequency division multiplexing based on offset QAM

Authors

Helmut Bölcskei

Reference

Chapter in "Advances in Gabor Analysis", H. G. Feichtinger and T. Strohmer, eds., Birkhäuser, pp. 321-352, 2003.

Abstract

One of the factors determining the performance of wireless Orthogonal Frequency Division Multiplexing (OFDM) systems is time-frequency localization of the transmitter and receiver pulse shaping filters. OFDM based on offset quadrature amplitude modulation (OFDM/OQAM) bypasses a major disadvantage of OFDM based on ordinary QAM, namely the fact that time-frequency well-localized pulse shaping filters are prohibited in the case of critical time-frequency density where spectral efficiency is maximal. In this chapter, we study the problem of pulse shaping filter design for OFDM/OQAM systems and we establish relations between OFDM/OQAM and Wilson and Gabor expansions. We derive general orthogonality conditions for OFDM/OQAM systems and we propose a computationally efficient method for designing time-frequency well-localized OFDM/OQAM pulse shaping filters with arbitrary length and arbitrary overlapping factors. We furthermore introduce biorthogonal frequency division multiplexing based on OQAM (BFDM/OQAM). Finally, design examples are presented to assess the performance of the proposed design algorithm.

Keywords

OFDM, offset QAM, Weyl-Heisenberg frames, pulse shaping, time-varying channels

Download this document:

This material is presented to ensure timely dissemination of scholarly and technical work. Copyright and all rights therein are retained by authors or by other copyright holders. All persons copying this information are expected to adhere to the terms and constraints invoked by each author's copyright. In most cases, these works may not be reposted without the explicit permission of the copyright holder.