中文摘要：

基于OFDMA（Orthogonal Frequency—Division Multiple Access）中不同用户所分配的子载波不同，提出了频率选择性衰落信道下分层结构的差分空时分组编码LDSTBC（Layered Differential Space-Time Block Code）的一种新的分层方法。发射端采用分层结构的差分空时分组编码结合OFDM技术，在接收端提出了利用OFDM中子载波选择矩阵进行分组干扰抑制，然后对LDSTBC的每层进行差分空时分组码的传统解码。相对于基于奇异值分解的分组干扰抑制方法，该文提出的方法只需要1根接收天线，降低了系统接收机设计的复杂度。仿真结果验证了所提出的方法的性能优于基于奇异值分解的方法。

英文摘要：

A novel grouping method is proposed for LDSTBC（Layered Differential Space-Time Block Code） over frequency selective channels, relying on mutual orthogonality between subcarriers of different users in OFDMA（Orthogonal Frequency-Division Multiple Access） systems. At the transmitter, LDSTBC combined with OFDM is applied. At the receiver, the group suppression based on subcarrier selection matrices is used, then the traditional decoding method for DSTBC is used for each layer. Compared with SVD the improved approach only needs one receive antenna so the complexity of the receiver decreases remarkably. Simulation results show that the performance of the improved method is better than the one based on SVD.