A method of closed-loop multi-stream wireless communication between a
transmitter (1) comprising a transmit antenna array of N transmit antenna
elements and a receiver (3) comprising a receive antenna array (4) of M
receive antenna elements, wherein a plurality of distinct data steams (x1
X2) are transmitted from the transmit antenna array to the receive
antenna array and the data streams are weighted by respective complex
weighting matrices before being applied to the transit antenna array. The
distinct data steams are separated and estimated at the receiver. The
distinct data streams (x1 xG) are applied to respective sub-groups (6,7)
of the transmit antenna elements at least one of which comprises a
plurality of the transmit antenna elements each of the sub-groups
comprising at least Nd transmit antenna elements, where M is greater than
or equal to (N/Nd). The complex weighting matrices (v1 to vn) are
functions of the respective transmission channels (hij) of the data
streams (x1, to xG) including the respective sub-groupes of transmit
antenna elements. Nd is preferably greater than or equal to two. Each of
the complex weighting matrices is calculated to be substantially equal to
the eigenvector corresponding to the largest eigenvalue of the matrix H
H, where H is the matrix of the equivalent channel including the
respective sub-groups of transmit antenna elements (6,7) seen by the
corresponding data stream HH is the Hermitian transform of the matrix H.
The number of the transmit antenna elements in each of the sub-groups is
preferably re-configurable during operation as a function of channel
conditions.