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MIMO-OFDMA的波束成形算法中,接收机需要反馈信道状态信息。当系统用户、子载波、天线数增加时,反馈量随之线性增长。为了限制反馈量在一个固定的限度之下,文中提出一种预设门限的反馈算法。接收机在确定每个子载波上的最优波束成形矢量及相应的信噪比之后,只有当信噪比大于门限时,才反馈最优波束成形矢量的索引及相应的信噪比值。该算法可以大大降低反馈量,同时保证频谱利用率几乎不变。
In MIMO-OFDMA beamforming algorithms, the receiver needs to feed back channel state information. When the number of system users, subcarriers, and antennas increases, the amount of feedback increases linearly. In order to limit the amount of feedback under a fixed limit, a threshold feedback algorithm is proposed in this paper. After determining the optimal beamforming vector and the corresponding signal-to-noise ratio on each subcarrier, the receiver feeds back the optimal beamforming vector index and the corresponding signal to noise ratio only when the signal to noise ratio is greater than the threshold. The algorithm can greatly reduce the amount of feedback, while ensuring that the spectrum utilization is almost unchanged.