Star-QAM 调制在STBC-SM系统中的应用和拓展

空间调制（SM）系统这些年来受到人们的关注，它克服了MIMO系统的一些缺点，同时又比SIMO系统具有较高的传输率。为了提高空间调制系统的分集增益，有学者把空时编码技术应用在空间调制系统中，提出了STBC-SM系统。另外，有些学者针对SM系统，对星座图上进行研究，提出了star-QAM调制，其误码性能优于传统的PSK调制和QAM调制。然而，仿真发现star-QAM调制与STBC-SM系统结合并没有取得期望中的性能提升。因此，本文提出了一种针对STBC-SM系统的简化star-QAM调制方式，在STBC-SM系统的不同码本中分别应用双层star-QAM调制的内环与外环星座图，以此增大了STBC-SM系统的最小编码增益距离（CGD），提高了系统的性能。本文还给出了简化star-QAM调制中内环与外环星座图半径的选择标准。最后计算机仿真表明简化star-QAM调制确实提高了STBC-SM系统的BER性能，证实了简化star-QAM调制的可行性和有效性。 

Application and Development of star-QAM modulation in the STBC-SM scheme

The spatial modulation (SM), which overcomes several drawbacks of the MIMO system and obtains a higher spectral efficiency compared with SIMO system, has received much attention recently. And the STBC-SM was proposed by combining the STBC with SM to improve the diversity gain of SM. Furthermore, some researchers proposed the star-QAM modulation for SM, which has a better BER performance compared with PSK and QAM modulation. However, the STBC-SM with star-QAM modulation does not have a better BER performance as expected. Consequently, in this paper, a simplified star-QAM modulation is proposed, which applies each ring of constellation point of star-QAM in the different STBC-SM codebook to increase the minimum coding gain distance (CGD). The standard to choose the amplitude of each ring is also presented in this paper. Finally, the simulation results show the performance advantages of the STBC-SM scheme with simplified star-QAM.