多路DFT扩频的低峰均比OSFBC传输方法

Multiple-DFT Spread Orthogonal SFBC with Low PAPR

  • 摘要: 空频分组码(SFBC)可以为MIMO系统带来发射分集增益,而单载波频分多址(SC-FDMA)系统的发送信号具有低峰均比(PAPR),但直接传输正交SFBC(OSFBC)会出现PAPR过大的问题。为此,本文以四发射天线为例针对OSFBC提出了一种基于DFT扩频的低PAPR传输方案,通过设置多个并行DFT单元并将得到的多组频域数据等间隔交叉排列映射到子载波上,根据频域循环移位和内插的性质使时域信号等效为多条单载波信号的叠加,PAPR与同点数SC-FDMA信号大致相当。同时,本文方案未带来误码率性能的下降,能够取得的分集增益与正交空时分组码(OSTBC)相同。

     

    Abstract: Space-Frequency Block Code(SFBC) has full diversity in MIMO systems, and Single-carrier Frequency Division Multiple Access(SC-FDMA) is a modulation technique with low Peak-to-Average Power Ratio(PAPR) of single-carrier transmission, but transmitting Orthogonal SFBC(OSFBC) signals by SC-FDMA will lead to high PAPR. To solve this problem, a new transmitting scheme based on multi-DFT spectrum spreading with four transmit antennas was proposed. By setting up parallel DFT units, frequency domain symbols were arranged crosswise with equal spacing on subcarriers, avoiding adjusting the symbol order in one DFT units. The corresponding transmitter and receiver were given and were easy to implement. It was proved that the generated signal is equivalent to the sum of multiple single-carrier signals according to frequency cyclic shift and interpolation property, and the overall PAPR obtained a low value close to single-carrier signals. Furthermore, the proposed scheme does not degrade the BER performance, and has the same diversity of OSTBC.

     

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