用于SFBC MIMO-OFDM系统的改进SLM算法

摘要

In the multiple-input multiple-output ( MIMO ) orthogonal frequency division multiplexing ( OFDM) system with space-frequency block coding ( SFBC) , the transmission symbols have problem with high peak-to-average power ratio( PAPR) . The selective mapping ( SLM) algorithm is proposed to reduce the PAPR effectively, but with the increase of transmitting antenna number, more inverse fast Fourier transform( IFFT) will increase the computational complexity of the system. This paper constructs an F ma-trix and proposes an improved SLM algorithm based on the F matrix for SFBC MIMO-OFDM system. The F matrix is used as phase sequences to deal with the signal after Space-Frequency Blocking Coding ( SF-BC) to obtain the optimal phase sequence and its conjugation. In the conjugation sequence, two factors form one unit, within which they exchange their location. The sequence scrambles signals from each anten-na after SFBC. Therefore, the number of IFFT for each of the transmitting antenna is reduced. Theoretical analysis and MATLAB simulation show that the method achieves good peak-to-average power ratio ( PA-PR) performance as well as reduces the computational complexity of the system.%在空频编码( SFBC)多输入多输出正交频分复用( MIMO-OFDM)系统中传输符号存在较高峰均功率比( PAPR)问题，采用SLM算法能够有效降低系统峰均功率比，但随着发射天线数的增加，较多的快速傅里叶反变换( IFFT)会增加系统的计算复杂度，因此，构造F矩阵并提出了一种基于F矩阵SFBC MIMO-OFDM系统的改进SLM算法。采用F矩阵作为相位序列组对空频编码信号进行独立处理，获得最优相位序列取共轭，将共轭序列中每两个旋转因子为一个单位交换位置，并扰码SFBC后各天线的信号，以此减少了每根发射天线上的IFFT次数。理论和MATLAB仿真分析表明，该算法获得了良好的峰均比性能，同时也降低了系统的计算复杂度。