空时交织码

Space time interleaving code

提出了一种可在频率选择性信道中获得分集增益的满速率满分集空时码.由于所设计方案在不同的天线上设置不同的随机交织器,因此称之为空时交织码.证明了该码满足准静态频选衰落信道满分集准则,并且无速率损失.由于方案仅在各天线处增加交织器,因此易于推广至多个发射天线的场景.同时交织器还使接收机可通过迭代检测逼近最大似然检测性能,因此分别设计了两种迭代接收结构,一种是直接在卷积关系与相等关系间迭代,另一种是在叠加关系、多路卷积关系与相等关系间进行迭代.这些简化了接收机复杂度,使之随发射天线数线性增长.与频选信道中的其他空时码方案相比,该方案在速率、分集以及复杂度方面做出了有效折中.仿真表明,瑞利块衰落信道中该码性能接近多重分集理论曲线.

Multi input multi output system in frequency selective channel provides space and frequency diversity at the same time. Traditional space time codes suffer from rate loss or diversity order loss. Space time interleaving code （STIC） achieves full space and frequency diversity without rate loss. Random interleavers are embedded on different transmit antennas. Thus it is easy to apply the code to various number of transmit antennas. In order to simplify the complexity of STIC decoding, two kinds of iterative decoding structures were designed. One is passing extrinsic information between convolutional constraint and equalization constraint, the other is passing iteratively between summing constraint, eonvolutional constraint and equalization con- straint. The simplified iterative decoders lower the receiver complexity from growing exponentially with the number of transmit antennas to growing approximately linearly with the number of transmit antennas. STIC not only achieves full rate full diversity but also makes it easy to implement in practice. Numerical experiments are implemented to prove the observations.