BER performance of OFDMA system based on DCT and phase modulation

Abstract

Orthogonal Frequency Division Multiplexing (OFDM) is a popular and widely accepted modulation technique in the area of wireless communication. Multi-user version of the OFDM system is called Orthogonal Frequency Division Multiple Access (OFDMA). Although OFDM and OFDMA have many benefits contributing to its popularity, a well-known drawback of multicarrier transmission is its inherited large peak-to-average power ratio (PAPR). The proposed system uses an alternative method to solve the PAPR problem in OFDMA, which is based on signal transformation using phase modulation (PM). The discrete Fourier transform in traditional DFT-OFDMA systems are replaced by a discrete cosine transform (DCT), the resulting DCT-OFDMA system is then used to develop a new transceiver system called DCT-OFDMA-PM. The PM input signal to be modulated must be real which can be produced using DCT-OFDMA with pulse amplitude modulation (M-PAM). Phase modulation based systems have the advantage of constant envelope (CE) signals and the ability to improve the diversity of multipath environment. The goal of this paper is to compare the performance of the proposed DCT-OFDMA-PM system with DCT-OFDMA as well as the traditional DFT-OFDMA system. The simulation result shows that proposed system outperforms in terms of BER and PAPR.