基于STBC-OFDM的非协作虚拟MIMO传输策略

针对多用户配对虚拟MIMO(multiple input multiple output)安全性差、对信道估计器依赖性强的问题,在分析理想MIMO系统和多径SISO(single input single output)系统本质关系的基础上,提出一种基于空时分组编码STBC(space-time block coding)和正交频分复用(orthogonal frequency division multiplexing,OFDM)的非协作式虚拟MIMO传输策略.在发送端,为了获得最佳发射分集增益,利用信道循环矩阵奇异值分解(singular value decomposition,SVD)后得到的左酉矩阵进行预编码;在接收端,为了获得平行子信道传输效果,提出一种基于低复杂度线性STBC译码和傅里叶变换预解码的非协作虚拟MIMO接收方案.该虚拟MIMO在收发两端均无需信道瞬时信息,以非协作方式在单天线内模拟多天线收发效果.仿真分析结果表明该虚拟MIMO系统能有效逼近实际理想MIMO的系统容量和误比特率性能,显著降低了虚拟MIMO系统的检测门限.该结果验证了其有效性和优越性.

Non-cooperative virtual MIMO transmission based on STBC-OFDM

on basis of analyzing the essential relationship between the ideal MIMO and multi-path SISO, a non-collaborative virtual MIMO based on STBC and OFDM was proposed to counter the poor security performance and strong dependence on channel estimation of virtual MIMO using user-pairing algorithm. To obtain full diversity gain, a valid pre-encoding for virtual MIMO was implemented at the transmitter by use of the left unitary matrix, which was obtained by singular value decomposing on the channel cyclic matrix. At the receiver, a detection scheme for the virtual MIMO based on a linear STBC decoding with low complexity and the Fourier transform pre-decoding was also presented to achieve the transmission effect being similar to those of parallel sub-channels. Although the instantaneous channel state information was unavailable at both sender and receiver, the single-antenna users even gain the multiple antennas transmission effect in a non-cooperative way. Simulation results show that the proposed virtual MIMO achieves similar performance on the capacity and bit error rate to ideal MIMO. These results verify its effectiveness and superiority.