Localized discrete fourier transform spread OFDM (DFT-SOFDM) systems for 4G wireless communication

Abstract

Broadband wireless mobile communications suffer from multipath frequency selective fading. Orthogonal frequency division multiplexing (OFDM), which is a multicarrier communication technique, has become widely used because of its robustness against frequency selective fading channel. Despite the many advantages, OFDM system suffers from high peak to average power ratio (PAPR).Discrete Fourier Transform Spread OFDM (DFT-SOFDM), which has a lowerPAPR is currently the system considered for uplink scheme in 3rd Generation Partnership Project Long Term Evolution (3GPP LTE).In this thesis, we model a transceiver of Localized Discrete Fourier Transform Spread Orthogonal Frequency Division Multiplexing (DFT-SOFDM) through an Additive White Gaussian Noise (AWGN) channel and a Rayleigh fading channel. To extend our current understanding of modulation schemes and reception techniques taking into account the effects of fading channel, we propose a transmission and reception scheme in the uplink through a frequency and time-selective fading channel. We derive a signal model for MIMO DFT-SOFDM utilizing repeated Alamouti codes to combat time selectivity. We propose MMSE estimation scheme which provides superior BER performance compared to the MRRC solution.