Patent ID: 7382840

Claim:
A method for processing radio frequency (RF) signals in a multi-antenna system, comprising: generating L t input data streams in a transmitter with t transmit antennas, where t is an integer, and where L t is an integer less than or equal to t; modulating the L t input data streams to RF signals; switching the RF signals to t RF branches; applying a phase-shift transformation to the RF branches by a t×t matrix multiplication operator Φ 1 , whose output are t RF signals, and in which entries of the matrix Φ 1 have constant modulus phase-only terms and the modulus phase-only terms adapt to an estimate of an average channel state; transmitting the t RF signals over a channel by the t transmit antennas; receiving the transmitted signals in a receiver with r receive antennas, where r is an integer; applying a phase-shift transformation to the r RF signals by a r×r matrix multiplication operator Φ 2 to generate r streams; selecting L r signal streams from the r streams, where L r is an integer less than or equal to r; demodulating the L r signal streams; and processing the demodulated L r signal streams in baseband to recover output data streams corresponding to the input data streams.