Reduction of PAPR Performance in Alamouti Coded MIMO-OFDM System using Selected Mapping Techniques with BPSK Modulation

Orthogonal frequency division Multiplexing (OFDM) is one of the most popular multicarrier or multiplexing modulation techniques in high speed wireless communication. The main principle of OFDM system is to transmit multiple numbers of signals simultaneously over a single transmission path. OFDM convert high data rate stream in to smaller data rate stream. Due to this high data rate and ability to combat frequency selective fading, OFDM has a strong candidate for 4G wireless networks. OFDM combined with multiple-input multiple-output (MIMO) to increase system capacity over the time variant frequency-selective channels and the diversity gain. The main idea of MIMO system is to use multiple antennas at both the transmitter and receiver end in order to improve communication performance. MIMO-OFDM system has a major drawback that might exhibit high peak-toaverage power ratio (PAPR). In this paper, we present Selected Mapping scheme (SLM) based on alamouti coded MIMO OFDM system with reduced PAPR using BPSK modulation schemes for N=128, 256 and 512. Simulation results show that MIMO OFDM system using SLM in alamouti code has low PAPR when compared to conventional MIMO OFDM system. MATLAB simulations show that our proposed SLM modification significantly improves the PAPR reduction.