Closed-loop transmit diversity scheme in frequency selective multipath channels
View Patent ↗Closed loop multiple-antenna wireless communications system with antenna weights determined by maximizing a composite channel signal-to-interference-plus-noise ratio minimum. Multiplexed symbol streams over subsets of antennas enhance throughput.
1. A method of transmission, comprising:
(a) providing P transmit antennas where P is an integer greater than or equal to 2;
(b) providing weights for said P antennas, said weights determined from information of communication channels from said P antennas to Q receive antennas) where Q is a positive integer, said weights determined to suppress multipath interference at a remote receiver having said Q receive antenna(s); and
(c) transmitting symbols modified by said weights from said P antennas.
2. The method of claim 1 , wherein:
(a) said weights determined in step (b) of claim 1 includes off-diagonal minimization of elements of a channel matrix premultiplied by its Hermitian conjugate.
3. The method of claim 1 , wherein:
(a) said weights determined in step (b) of claim 1 includes information of a detection method to account for said multipath interference.
4. The method of claim 3 , wherein:
(a) said weights determined in step (b) of claim 1 includes minimization of an error rate when using said detection method.
5. The method of, claim 4 , wherein:
(a) said weights determined includes minimization of symbol error rate for a maximum likelihood detection method.
6. The method of claim 3 , wherein:
(a) said weights determined in step (b) of claim 1 includes maximization of a signal-to-interference-plus-noise ratio when using said detection method.
7. The method of claim 6 , wherein:
(a) said weights determined in step (b) includes maximization of minimum signal-to-interference-plus-noise ratio for a detection method selected from the group consisting of linear zero-forcing, linear minimum mean square error, iterative zero-forcing, and iterative minimum mean square error.
8. The method of claim 3 , wherein:
(a) said providing weights in step (b) includes channel information estimated from reception of signals from said Q antenna(s).
9. The method of claim 1 , wherein:
(a) said providing weights in step (b) of claim 1 includes reception of channel information from said Q antenna(s).
10. The method of claim 1 , wherein:
(a) said providing weights in step (b) of claim 1 includes reception of said weights from said Q antenna(s).
11. The method of claim 1 , wherein:
(a) said communication channel is a wideband or CDMA channel with a single user using multiple codes having the same weights.
12. The method of claim 11 , wherein:
(a) said weights determined in step (b) includes information of a detection method to account for said multipath interference; wherein said detection method is multicode interference cancellation with method selected from the group consisting of linear zero-forcing, linear minimum mean square error, iterative zero-forcing, and iterative minimum mean square error.
13. The method of claim 3 , wherein:
(a) said communication channel is a wideband or CDMA channel with multiple users having differing weights; and
(b) said differing weights are from claim 3 by joint maximization.
14. The method of claim 13 , wherein:
(a) said weights determined in step (b) includes information of a detection method to account for said multipath interference; wherein said detection method is multiuser interference cancellation with method selected from the group consisting of linear zero-forcing, linear minimum mean square error, iterative zero-forcing, and iterative minimum mean, square error.
15. The method of claim 3 , wherein:
(a) said weights of step (b) of claim 1 are updated.
16. The method of claim 1 , wherein:
(a) said integer Q is greater than or equal to said integer P.
17. A transmitter, comprising:
(a) P transmit antennas where P is an integer greater than or equal to 2; and
(b) multipliers with weights coupled to said P antennas, said weights determined from (i) information of communication channels from said P antennas to Q receive antenna(s) where Q is a positive integer, said weights determined to suppress multipath interference at a remote receiver having said Q receive antenna(s) and/or (ii) a detection method to suppress multipath interference at said remote receiver.
18. The transmitter of claim 17 , wherein:
(a) said weights are determined by a processor coupled to said multipliers.
19. The transmitter of claim 17 , wherein:
(a) said weights are determined outside of said transmitter and received by said transmitter from said signals from said Q antenna(s).
20. A receiver, comprising:
(a) Q antenna(s) where Q is a positive integer;
(b) a detector coupled to said Q antenna(s), said detector adapted to detect signals from P transmit antennas where P is an integer greater than or equal to 2 and with weights applied to said P antennas, where said weights are determined from (i) information of, communication channels from said P antennas to said Q receive antenna(s), said weights determined to suppress multipath interference at said receiver and/or (ii) a detection method of said detector to suppress multipath interference at said receiver.
21. The receiver of claim 20 , wherein:
(a) said detection method is selected from the group consisting of linear zero-forcing, linear minimum mean square error, iterative zero-forcing, and iterative minimum mean square error; and
(b) said weights determination includes maximization, of minimum signal-to-interference-plus-noise ratio.
22. The receiver of claim 20 , wherein:
(a) said detection method is maximum likelihood; and
(b) said weights determination includes minimization of symbol error rate.