RF signal processing in multi-antenna systems
View Patent ↗A method for antenna subset selection by joint processing in RF and baseband in a multi-antenna systems. L t input data streams are generated in a transmitter for either diversity transmission or multiplexing transmission. These streams are modulated to RF signals. These signals are switched to the t branches associated with the t transmit antennas, and a phase-shift transformation is applied to the RF signals by a t×t matrix multiplication operator Φ 1 , whose output are t≧L t RF signals. These signals are transmitted over a channel by t antennas. The transmitted signals are received by r antennas in a receiver. A phase-shift transformation is applied to the r RF signals by a r×r matrix multiplication operator Φ 2 . L r branches of these phase shifted streams are demodulated and further processed in baseband to recover the input data streams.
1. 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.
2. The method of claim , in which each of the L t input data stream has a weight, and further comprising:
summing the L r weighted data streams before the demodulating and decoding.
3. The method of claim 1 , in which the L t input data streams are generated by a space-time block coder.
4. The method of claim 1 , in which the L t input data streams are generated by a space-time trellis coder.
5. The method of claim 1 , in which the input data streams are space-time layered structures.
6. The method of claim 1 , in which t=L t , and the matrix Φ 1 is an identity matrix.
7. The method of claim 1 , in which r=L r and the matrix Φ 2 is an identity matrix.
8. The method of claim 1 , in which the phase-only terms adapt to an estimate of an instantaneous channel state.
9. The method of claim 1 , in which entries of the matrix Φ 2 have constant modulus phase-only terms.
10. The method of claim 1 , in which entries of the matrices Φ 1 and Φ 2 have constant modulus phase-only terms.
11. The method of claim 1 , in which the matrix Φ 1 is a fast Fourier transform matrix.
12. The method of claim 1 , in which the matrix Φ 2 is a fast Fourier transform matrix.
13. The method of claim 1 , in which the matrices Φ 1 and Φ 2 are fast Fourier transform matrices.