To achieve the minimum mean square error, the training sequences transmitted from multiple antennas must have impulse-like autocorrelation functions and zero cross-correlation functions.

• 为了使我们的通道估测均方差最小化，从多根天线传送出的训练序列皆必须有脉冲式的自我相关函数，彼此之间的交互相关函数也须为零。