Classic OFDM Systems and Pulse Shaping OFDM/OQAM Systems

Abstract

ISRN KTH/ICT/ECS/R-07/01{SE In this report, we provide a comparative study of state-of-the-art in Orthogo-nal Frequency Division Multiplexing (OFDM) techniques with orthonormal analy-sis and synthesis basis. Two main categories, OFDM/QAM which adopts base-band Quadrature Amplitude Modulation (QAM) and rectangular pulse shape, and OFDM/OQAM which uses baseband oset QAM and various pulse shapes, are in-tensively reviewed. OFDM/QAM can provide high data rate communication and eectively remove intersymbol interference (ISI) by employing guard interval, which costs a loss of spectral eciency and increases power consumption. Meanwhile it remains very sensitive to frequency oset which causes intercarrier interference (ICI). In order to achieve better spectral eciency and reducing combined ISI/ICI, OFDM/OQAM using well designed pulses with proper Time Frequency Localiza-tion (TFL) is of great interest. Various prototype functions, such as rectangular, half cosine, Isotropic Orthogonal Transfer Algorithm (IOTA) function and Extended Gaussian Functions (EGF) are discussed and simulation results are provided to il-lustrate the TFL properties by the ambiguity function and the interference function. Contents