PERFORMANCE EVALUATION OF PAPR USING PTS-PSO IN MIMO-OFDM SYSTEMS FOR VARIOUS HIGHER ORDERMODULATION SCHEMES

摘要

OFDM is a most attractive fast growing multi-carrier modulation technology enabling high capacity of data transmission over a single path. The major problem in OFDM is its high peak-to-average power ratio with respect to independent subcarrier. Transmitter containing non-linear components distorts the signal due to presence of large PAPR there by increasing the complexity and reducing the efficiency of power amplifier. The various techniques are surveyed to reduce level of complexity and PAPR. Partial Transmit Sequence is one of the distortions less techniques that improve PAPR performance. However, the major disadvantage of PTS due to many IFFT operations is high computational complexity. In this paper, it is proposed that a particle swarm optimization (PSO) based partial transmit sequence (PTS) technique is used to achieve least Peak-to-Average Power Ratio (PAPR) in Multiple Input Multiple Output-Orthogonal Frequency Division Multiplexing systems (MIMO-OFDM) systems for 512 subcarriers. The approach is to apply PSO based PTS on each antenna of the system supporting to find the optimal phase factors, which is a direct method to achieve minimum PAPR. PSO based PTS algorithm when applied with a wide range of phase factors to MIMO-OFDM systems, results in high performance after simulation. The PAPR achieved using 2×2, 4×4, 8×8 and 16×16 MIMO-OFDM systems without PTS-PSO using16-QAM is 15.9dB whereas with and with PTS-PSO is 6dB therefore overall reductions PAPR with and without PTS-PSO is 9.9dB. Similarly, the PAPR reduction is achieved using QPSK and 8-QAM respectively.