METHOD AND APPARATUS FOR PRE-PROCESSING DATA TO BE TRANSMITTED IN MULTIPLE-INPUT COMMUNICATION SYSTEM

• US 20100303170A1
• Filed: 05/10/2007
• Published: 12/02/2010
• Est. Priority Date: 05/10/2007
• Status: Active Grant

• Current Assignee: Alcatel-Lucent SA (Nokia Corporation)
• Original Assignee: Alcatel-Lucent SA (Nokia Corporation)
• Inventors: Zhu, Xiaolong, Cai, Liyu, Yang, Hongwei
• Granted Patent: US 8,325,842 B2
• Time in Patent Office: Days
• US Class Current: 375/297
• CPC Class Codes: H04B 7/0417 Feedback systems
• CPC Class Codes: H04B 7/0617 for beam forming
• CPC Class Codes: H04B 7/0689 using different transmission schemes, at least one of them being a diversity transmission scheme

Abstract

A method for pre-processing data to be transmitted in a multiple-input communication system comprises the following steps: generating a beamforming matrix and a pre-coding matrix; combining the beamforming matrix and the pre-coding matrix to generate a weight matrix; and pre-processing the data by using the generated weight matrix. There are also provided a transmitter, a base station, and a communication system using the method.

Claims

1. A method for pre-processing data to be transmitted in a multiple-input communication system, the method comprising:

generating a beamforming matrix and a pre-coding matrix;

combining the beamforming matrix and the pre-coding matrix to generate a weight matrix; and

pre-processing the data by using the generated weight matrix.

2. The method according to claim 1, wherein a linear combination is performed on the beamforming matrix and the pre-coding matrix according to the following formula, in order to generate the weight matrix:

W=a×

B+b×

P

in which B is a beamforming matrix, P is a pre-coding matrix, W is a weight matrix, and a and b are constants, wherein the values of a and b are selected according to a measured interference level.

3. The method according to claim 1, wherein beamforming weighted vectors are generated according to estimated location information of a target user and/or interference users, and the beamforming weighted vectors are arranged in order to generate a beamforming matrix.

4. The method according to claim 3, wherein

if the dimension of the beamforming weighted vector is equal to the number of transmit antennas, the beamforming weighted vectors are arranged in a column order to generate the beamforming matrix;

and

if the dimension of the beamforming weighted vector is less than the number of transmit antennas, zero is filled at a specific location of the beamforming weighted vector to generate weighted vectors with the dimension equal to the number of transmit antennas, and the weighted vectors are arranged in a column order to generate the beamforming matrix.

5. The method according to claim 3, wherein the location information is the direction of arrival.

6. The method according to claim 1, wherein a pre-coding matrix is generated according to channel information.

7. The method according to claim 6, wherein a pre-coding matrix is generated according to long-term channel information, and wherein the long-term channel information is the covariance matrix or mean matrix of channels.

8. The method according to claim 6, wherein a pre-coding matrix is generated according to an instantaneous channel matrix.

9. The method according to claim 6, wherein a pre-coding matrix is generated according to long-term channel information and an instantaneous channel matrix.

10. The method according to claim 1, wherein if channel information is not available, then a pre-coding matrix is selected as an identity matrix or a certain sub-matrix formed by part of column vectors of an identity matrix.

11. The method according to claim 2, wherein if the interference level is very high, a is selected to be close or equal to 1, and b is selected to be close or equal to 0.

12. The method according to claim 2, wherein if the interference level is very low, a is selected to be close or equal to 0, and b is selected to be close or equal to 1.

13. The method according to claim 2, wherein if the interference level is medium, values of a and b are selected such that 0<

a<

1 and 0<

b<

1.

14. The method according to claim 13, wherein if more beamforming gain is required than pre-coding gain, values of a and b are selected such that a>

b.

15. The method according to claim 13, wherein if more pre-coding gain is required than beamforming gain, values of a and b are selected such that a<

b.

16. The method according to claim 1, wherein the multiple-input communication system is a multiple-input single-output communication system.

17. The method according to claim 1, wherein the multiple-input communication system is a multiple-input multiple-output communication system.

25. The device according to claim 13, wherein the pre-coding matrix generation means generates a pre-coding matrix according to an instantaneous channel matrix.

18. A device for pre-processing data to be transmitted in a multiple-input communication system, the device comprising:

beamforming matrix generation means for generating a beamforming matrix;

pre-coding matrix generation means for generating a pre-coding matrix;

combination means for combining the beamforming matrix and the pre-coding matrix to generate a weight matrix; and

pre-processing means for pre-processing the data by using the generated weight matrix.

19. The device according to claim 18, wherein the combination means performs a linear combination on the beamforming matrix and the pre-coding matrix according to the following formula, in order to generate the weight matrix:

W=a×

B+b×

P

in which B is a beamforming matrix, P is a pre-coding matrix, W is a weight matrix, and a and b are constants, wherein the values of a and b are selected according to a measured interference level.

20. The device according to claim 18, wherein the beamforming matrix generation means generates beamforming weighted vectors according to estimated location information of a target user and/or interference users, and arranges the plurality of beamforming weighted vectors in order to generate a beamforming matrix.

21. The device according to claim 20, wherein

if the dimension of the beamforming weighted vector is equal to the number of transmit antennas, the plurality of beamforming weighted vectors is arranged in a column order to generate the beamforming matrix;

and

if the dimension of the beamforming weighted vector is less than the number of transmit antennas, zero is filled at a specific location of the beamforming weighted vector to generate weighted vectors with the dimension equal to the number of transmit antennas, and the weighted vectors are arranged in a column order to generate the beamforming matrix.

22. The device according to claim 20, wherein the location information is the direction of arrival.

23. The device according to claim 18, wherein the pre-coding matrix generation means generates a pre-coding matrix according to channel information.

24. The device according to claim 23, wherein the pre-coding matrix generation means generates a pre-coding matrix according to long-term channel information, and wherein the long-term channel information is the covariance matrix or mean matrix of channels.

26. The device according to claim 18, wherein the pre-coding matrix generation means generates a pre-coding matrix according to long-term channel information and an instantaneous channel matrix.

27. The device according to claim 18, wherein if channel information is not available, then a pre-coding matrix is selected as an identity matrix or a certain sub-matrix formed by part of column vectors of an identity matrix.

28. The device according to claim 20, wherein if the interference level is very high, a is selected to be close or equal to 1, and b is selected to be close or equal to 0.

29. The device according to claim 20, wherein if the interference level is very low, a is selected to be close or equal to 0, and b is selected to be close or equal to 1.

30. The device according to claim 20, wherein if the interference level is medium, values of a and b are selected such that 0<

a<

1 and 0<

b<

1.

31. The device according to claim 30, wherein if more beamforming gain is required than pre-coding gain, values of a and b are selected such that a>

b.

32. The device according to claim 30, wherein if more pre-coding gain is required than beamforming gain, values of a and b are selected such that a<

b.

33. The device according to claim 18, wherein the multiple-input communication system is a multiple-input single-output communication system.

34. The device according to claim 18, wherein the multiple-input communication system is a multiple-input multiple-output communication system.

35. A device according to claim 18 implemented in a transmitter.

36. A device according to claim 35 wherein the transmitter is implemented in a base station.

37. A device according to claim 36 wherein the base station is implemented in a communication system.