MIMO-OFDM系统中反馈插值方法和复杂度

Interpolation of beamforming in the reduced feedback of MIMO-OFDM systems

在多输入多输出-正交频分复用(MIMO-OFDM)系统中,为了降低每个子载波在波束形成时的高反馈开销,通过充分利用发射端在某些特定子载波上的信道信息和信道系数在频域的相关性,提出了新的3种波束插补方法,分别为三阶样条插补、变换域插补和低通插值方法.这些方法只需接收机反馈部分子载波上的波束矢量就能确定其他子载波上的波束矢量,避免了因矢量旋转带来的复杂搜索,降低了角度反馈开销.减小系统反馈量,同时保证较好的性能.仿真结果表明,在频谱利用率、误码性能和反馈量方面,所提方案均优于现有的插补方案.与现有方法相比,在同样反馈量的条件下,所提方法能够获得明显的性能增益.

In order to decrease the feedback overhead caused by the beamforming on every subcarrier in multiple-input multiple-output orthogonal frequency division multiplexing（MIMO-OFDM） systems,the beamforming issue is investigated for the MIMO-OFDM system,where the channel state information on certain subcarriers at the transmitter as well as the feature of the channel correlation in frequency band are fully exploited.By employing some interpolation methods among many beamformers at different carriers,namely,cubic-spline interpolation,zero-padding and DFT（discrete Fourier transform）/IDFT（inverse DFT） interpolation and low-pass interpolation,the system performance can be improved greatly with very small feedback overhead.The numerical results show that the new algorithms acquire proper gain in performance,indicating that the proposed schemes improved the system performances greatly.