众所周知，目前四发射天线上还没有满速率和满分集复杂空时分组码（STBC）。提出了一种四发射天线和nR接收天线上的简单准正交空时频分组码（QO-STFBC）的编码方案，其中每两个发射天线为一组，每组通过不同的子载波发射信号。接收方可由奇/偶索引傅里叶运算区分不同的组。在将接收天线上收到的不同信号重组之后，可用等效半速率正交STFBC（O-STFBC）进行解码。因此，在发射端和接收端分别都能获得满速率和满分集特性。仿真结果表明，QO-STFBC编码方案比其他方案具有更好的性能。在传输速率为2 bit/s/Hz，误码率为10-3的情况下，所提出方案的SNR增益分别是：2速分层Alamouti方案大约为4 dB，满速QO-STBC方案约为5 dB，半速O-STBC方案约为7 dB。%It is well known that the full rate and full diversity complex Space-Time Block Code(STBC)doesn’t exist in four transmit antennas. This paper proposes a simple Quasi-Orthogonal Space-Time-Frequency Block Code(QO-STFBC) scheme with four transmit antennas and nR receive antennas, where every two transmit antennas constitute one group and each group transmits signals over different subcarriers. The receiver can separate the received signals from each group via odd/even index FFT operation. After recombining the separated received signals from received antennas, an equivalent half rate orthogonal STFBC(O-STFBC)can be used for decoding. Thus, the full rate and full diversity are achieved at the transmitter and receiver, respectively. Simulation result shows that the proposed QO-STFBC scheme has better perfor-mance than the other schemes. The proposed scheme SNR gain is about 4 dB in rate 2 layered Alamouti scheme, about 5 dB in full rate QO-STBC scheme and about 7 dB in half rate O-STBC scheme at 10-3 BER for the transmission of 2 bit/s/Hz.
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