瑞利衰落下的空时频(STF)分组编码OFDM系统

基于正交频分复用(OFDM)系统，提出了一种发射分集方案——比特交织空时频(BI—STF)分组编码。其基本思路是：应用子载波分群方法并选择合适的系统参数，将OFDM系统转化成分群OFDM(G-OFDM)，对每个群分别进行空时频分组编码(GSTFBC)；在编码比特被重组和映射成GSTF分组编码前进行合理的比特交织，并按一定的规则分配给各个单群子载波进行酉星座旋转(CR)预编码。随后讨论了该方案的频谱利用率和成对错误概率(PEP)。仿真结果表明，同其它编码方案相比，提出的方案能在频率选择性瑞利衰落信道下获得最大的空间分集和频率分集增益，且只有较低的解码复杂性。

Space-time-frequency block coding over OFDM systems for rayleigh fading channels

In this paper, a novel space time frequency code scheme-Bit interleaved space time frequency block coding (BI STFBC) being fit for orthogonal frequency division multiplexing (OFDM) systems is considered for frequency selective Raleigh fading channels. Combining subcarrier grouping with choosing appropriate system parameters, general OFDM system is converted into a set of group OFDM system, within which STF coding is considered. Code bits are bit wise interleaved across every grouping subcarrier before grouped and mapped to space time frequency code, followed the Unitary constellation rotating precodes. The spectral efficiency and pairwise error probability (PEP) is also considered. Compared with existing alternatives, the scheme can attain maximum space and frequency diversity with low decoding flexibility. Simulation results confirmed the effective of the proposed scheme.