中文摘要：

多输入多输出-正交频分复用（MIMO-OFDM）是第四代移动通信系统的关键技术,该技术由于采用多载波调制,存在较高的峰均功率比（PAPR）,为了降低MIMO-OFDM系统中较高的PAPR,在近似梯度投影（AGP）和部分传输序列（PTS）的基础上提出QAP算法。该算法首先将MIMO-OFDM信号经过AGP算法,然后用PTS算法进一步降低该系统的PAPR。仿真分析表明,所提出的QAP方案与其他传统方案相比,系统PAPR性能得到明显改善,且不破坏系统的误码率（BER）性能;同时QAP算法的PAPR值受子载波数目影响,PAPR值随着子载波数目（N=32,64,128,256,512）的增加而增加;QAP算法在随机分组方式下PAPR性能最佳。

英文摘要：

The MIMO-OFDM technology is a key technology of the fourth generation mobile communication system. The high peak-to-average power ratio （PAPR） exists in the MIMO-OFDM system because the multi-carrier modulation is adopted in the technology. In order to reduce the high PAPR of the MIMO-OFDM system, a QAP algorithm is proposed based on the ap- proximate gradient project （AGP） and partial transmission sequence （PTS）. The MIMO-OFDM signal is processed with the AGP algorithm. The PTS algorithm is used to reduce the system PAPR further. The simulation analysis results show that, in compari- son with the traditional schemes, the system PAPR is dramatically improved with QAP scheme while the performance of the sys- tem bit error rate （BER） isn＇t destroyed; the PAPR reduced by the QAP algorithm is affected by the quantity of the subearrier, and increased with the increase of the subcarrier quantity （N=32, 64, 128, 256, 512）; the PAPR performance of the QAP algorithm is best in the mode of the random allocation.