分布式MIMO中的最大似然频偏估计

在考虑分布式多入多出(MIMO)系统中各收发天线对之间的频偏均可能不同的一般情况 下，推导出了平坦衰落MIMO信道模型下的最大似然频偏估计。针对收端是否采用分布式天线 的两种不同情况，分别提出了一种只涉及一维最大化问题的较低复杂度频偏估计方法。仿真 结果表明，所提频偏估计方法在平坦衰落MIMO信道下可以获得令人满意的估计性能；而在收 端仍采用集中式天线这一特殊情况下，利用所有接收天线上的接收信号进行联合估计，可以 进一步提高估计性能。

Maximum likelihood estimation of frequency offsets in distributed MIMO systems

In consideration of the general case where the frequency offsets(FO) between each transmitting antenna and each receiving antenna are possibly different in d istrib uted multi input multi output(MIMO) systems,the maximum likelihood( ML) FO estimation in flat-fading MIMO channels is derived. Aiming at the cases w ith co loca ted and distributed receiving antennas, two low complexity FO estimation method s involving only 1 dimensional maximization are proposed, respectively. Simulation results show that the proposed FO estimation methods can achieve satisfactory pe rformance in flat fading MIMO channels. While in the special case where the rece iving antennas are still co located, the estimation performance can be further improved by joint estimation using all receiving antennas.