DSTBC-OFDM系统及性能分析

正交频分复用技术可以有效的消除信号符号间干扰并具有较高的频带利用率。空时分组码可以弥补正交频分复用技术对移动造成的多普勒频移比较敏感的缺陷,所以这两种技术的结合在下一代无线通信中的应用引起了越来越多的关注。本文研究了DSTBC(D ifferential Space-Tim e B lockCodes,差分空时分组编码)和OFDM(O rthogonal Frequency D ivisionMu ltip lexing,正交频分复用)技术相结合的系统收发机结构。由于接收端不需要进行信道估计,可大大简化接收机复杂度。通过仿真给出了DSTBC-OFDM系统与STBC-OFDM系统及纯OFDM系统在Rayle igh衰落信道及SUI信道下的比特差错性能。通过比较可看出,在静止情况下或中速移动但信道条件较好的情况下,DST-BC-OFDM系统可作为STBC-OFDM系统的替代。

DSTBC-OFDM System and Its Performance Analysis

OFDM(Orthogonal Frequency Division Multiplexing) can effectively eliminate the ISI between different symbols and has high frequency efficiency.OFDM is sensitive to the Doppler frequency offset caused by moving that can be overcome by Space-time coding.So the application the combination of the space-time coding and OFDM in next generation wireless telecommunications has attracted more and more attention.In this article,the structure of DSTBC(Differential space-time block coding) combined with OFDM system is given first. Because of no need of channel estimation,the complexity of the receiver is simpler than STBC-OFDM system.Then,performance comparison is made by simulation among pure OFDM system,STBC-OFDM system and DSTBC-OFDM system under Rayleigh fading channel and SUI channel.It is concluded that the STBC-OFDM system can be replaced by DSTBC-OFDM system under stationary or low to moderate velocity conditions.