Research On PAPR Reduction Technology Based On MIMO-OFDM Systemsk

Orthogonal frequency division multiplexing (OFDM) is a multi-carrier transmission technology which has the advantages of high spectrum efficiency and robustness against frequency selective fading. It has been regarded and used as one of the core technologies of the fourth generation mobile communication. MIMO technology can exponentially increase the spectral efficiency in the case of not increasing the bandwidth and the antenna transmission power. Combination of the two technologies not only can improve the data transfer rate and increase system capacity but also can effectively against noise and multipath fading, promoting the future development of wireless communication technology. MIMO-OFDM system is still a multi-carrier modulation system, the high peak to average power ratio (PAPR) become the key factor restricting its development.This paper studies using efficient algorithms to reduce the PAPR value in space-time coding MIMO-OFDM systems. First, introduce the basic principles of MIMO-OFDM system, then focusing on several classic PAPR reduction techniques:signal distortion technology, coding technology and probability technologies.The main work and innovation contains:(1)Analyze the Cross-Antenna Rotation and Inversion (CARI) algorithm for multi-antenna system, because of the large amount of calculation we proposed two improved algorithms. The improved algorithms own better PAPR performance at the cost of increasing the number of computation.In this paper,we combined the improved algorithms with Constellation Extension algorithm (ACE) in order to own better PAPR performance.(2) Partial Transmit Sequence (PTS) algorithm is an effective algorithm to improve the PAPR performance. In multi-antenna system, each antenna separately use this algorithm will substantially increase the computational complexity and high requirements on the physical device will make it difficult to obtain effective application. We discovered the optimization algorithm of PTS based on the characteristics of the space-time coding, we call it alternately PTS algorithm. Alternately PTS algorithm can effectively reduce the amount of computation at the same time the PAPR performance will be declined. In this paper, we proposed the improved algorithm based on the alternately PTS algorithm. In this algorithm we own better PAPR performance at the expense of increasing the amount of computation. The improved algorithm has better PAPR performance and can be used in practical systems.