"When the channel transfer function matrix H containing channel information in Equation 1 is subject to QR decomposition, it can be represented as the following: H=QR, where Q is a unitary matrix and R is an tipper triangular matrix.When a QR decomposition result of the channel transfer function matrix H is applied to Equation 1, r=QRs+n.If the obtained r is multiplied by a Hermitian matrix Q at th" . . . .