Alamouti space time coded design for OFDMA systems based layered FFT structure

Abstract

Orthogonal Frequency-Division Multiple Access (OFDMA) is a multiuser orthogonal frequency-division multiplexing (OFDM) digital modulation scheme. Multiple accesses can be achieved in OFDMA by assigning subsets of subcarriers to individual users. This allows simultaneous low data rate transmission from several users. However, the OFDMA system exhibits high peak to average power ratio (PAPR) and introduce larger complexity by applying discrete Fourier transform (DFT) at the transmitter and inverse DFT (IDFT) at the receiver section. In this paper, we propose a space time block coding (STBC) for OFDMA based layered FFT structure, which provides better PAPR reduction property, low complexity in user terminals. The STBC scheme is also provide full diversity from both OFDMA signaling and STBC coding transmission.