基于单载波频域均衡的异步空时协作传输机制

 异步环境下,空时协作传输系统的各中继站点无法精确同步,导致不能直接使用正交空时分组码;异步还可能导致采样时刻的不理想,由于脉冲成型滤波器的缘故,使得平衰落信道变成频率选择性衰落信道,严重影响系统性能.针对这些问题,本文提出一种基于单载波频域均衡的异步空时协作传输机制.各中继站点基于正交空时分组码的思想对数据执行逆序共轭等简单操作后发送;目的站点对接收数据进行快速傅立叶变换(FFT)后,通过线性组合分离重叠在一起的数据帧,然后对组合输出的数据执行频域均衡,最后执行快速傅立叶逆变换(IFFT)还原发送数据.由于FFT和IFFT有快速算法,因此新机制有较低的复杂度.理论分析和仿真结果表明:即使在异步环境下,提出的新机制也能获得空时分组码所提供的分集增益.

Asynchronous Space-Time Cooperative Transmission Scheme Based on Single-Carrier Frequency Domain Equalization

Two key problems in the asynchronous space-time cooperative transmission systems are the loss of OSTBC’s orthogonality and the channel dispersion,which may prevent the direct use of OSTBC and lead to severe performance degradation.To solve these problems,this paper proposes a new cooperative transmission scheme based on SC-FDE.Adopting the idea of OSTBC,simple operations such as reversal and conjugation are performed on the transmitting data at each relay node.The destination node performs FFT on the receiving data,then separates the superimposed frames by linear combination.The outputs of the combination are equalized by a frequency domain equalizer.At last IFFT is performed on the equalized data to recover the original data.By using FFT and IFFT,the new scheme has low complexity.Theoretic analysis and simulation results show that the new scheme can achieve diversity gain supplied by OSTBC even without perfect synchronization.