PERFORMANCE ANALYSIS OF PAPR REDUCTION FOR STBC MIMO-OFDM BY USING MODIFIED PTS TECHNIQUES FOR DIFFERENT MODULATION

摘要

Higher bandwidth for wireless communications is today's requirement. To meet the requirements new systems are being implemented. These systems are specified by multi carrier frequencies, high data transmission rate and mobility and are implemented with MIMO OFDM (Multiple Input Multiple Output Orthogonal Frequency Division Multiplexing). Integration of STBC to MIMO OFDM over frequency selective channel is adopted to improve further performance which convert frequency selective channel to several flat fading channels thereby eliminating ISI. But the multicarrier technique STBC MIMO-OFDM has high Peak-to-Average Power Ratio (PAPR). To achieve better performance this PAPR has to be reduced. In this paper, the effect on PAPR by variation of different parameters like number of subcarriers, OFDM symbols, and modulation techniques has been presented. We use lower order modulation like QPSK and higher order modulation like 32-QAM which will provide reduction in original PAPR but reduced PAPR will show small difference for low to high modulation. The basic idea of PTS is to produce alternative transmit sequences seeded from the same data source and then to select the transmit signal exhibiting the lowest PAPR. Results show that there is only small difference in PAPR reduction for different subcarriers. But when OFDM symbols are varied, there is recognizable reduction in PAPR. Thus, different subcarriers have minimum influence on PAPR performance compared to OFDM symbol variation.