METHOD OF TRANSFORMING PRE-CODED SIGNALS FOR MULTIPLE-IN-MULTIPLE-OUT WIRELESS COMMUNICATION

• US 20120281783A1
• Filed: 05/02/2011
• Published: 11/08/2012
• Est. Priority Date: 05/02/2011
• Status: Active Grant

• Current Assignee: WSOU Investments, LLC (WSOU Holdings, LLC)
• Original Assignee: Alcatel-Lucent Telecom Limited (Nokia Corporation), Alcatel-Lucent USA, Inc. (Nokia Corporation)
• Inventors: CHENG, FANG-CHEN, Baker, Matthew P.J.
• Granted Patent: US 8,675,762 B2
• Time in Patent Office: Days
• US Class Current: 375/295
• CPC Class Codes: H04B 7/0456 Selection of precoding matrices or codebooks, e.g. using matrices antenna weighting
• CPC Class Codes: H04B 7/0469 taking special antenna structures, e.g. cross polarized antennas into account
• CPC Class Codes: H04B 7/0473 taking constraints in layer or codeword to antenna mapping into account
• CPC Class Codes: H04B 7/063 Parameters other than those covered in groups H04B7/0623 - H04B7/0634, e.g. channel matrix rank or transmit mode selection
• CPC Class Codes: H04B 7/0632 Channel quality parameters, e.g. channel quality indicator [CQI]
• CPC Class Codes: H04B 7/0639 Using selective indices, e.g. of a codebook, e.g. pre-distortion matrix index [PMI] or for beam selection
• CPC Class Codes: H04L 25/03343 Arrangements at the transmitter end
• CPC Class Codes: H04L 25/0391 construction details of matrices

Abstract

The present invention provides a method of transforming pre-coded signals for transmission over an air interface in a MIMO wireless communication system. Embodiments of the method may include applying, at a transmitter, a transform matrix and a pre-coding matrix to a signal prior to transmitting the signal using a plurality of antennas deployed in a first antenna configuration. The pre-coding matrix is selected from a codebook defined for a second antenna configuration deployed in a non-scattering environment. The transform matrix is defined based on the first antenna configuration and a scattering environment associated with the transmitter.

Claims

1. A method, comprising:

applying, at a transmitter, a transform matrix and a pre-coding matrix to a signal prior to transmitting the signal using a plurality of antennas deployed in a first antenna configuration, wherein the pre-coding matrix is selected from a codebook defined for a second antenna configuration, and wherein the transform matrix is derived from at least the first antenna configuration.

2. The method of claim 1, wherein the pre-coding matrix is selected from a codebook defined for at least one of a linear antenna array or a cross-polarized antenna array.

3. The method of claim 2, wherein applying the transform matrix to the signal comprises applying a transform matrix defined based on at least one of a circular antenna array or a linear antenna array that is oriented at a different angle than the linear antenna array used to define the codebook.

4. The method of claim 1, wherein the transmitter is implemented in a base station, and wherein applying the transform matrix comprises selecting the transform matrix based on location information for user equipment and applying the selected transform matrix to signals transmitted over a downlink towards the user equipment.

5. The method of claim 1, 2, 3, or 4, wherein applying the transform matrix comprises applying the transform matrix to at least one reference signal, and wherein applying the pre-coding matrix comprises selecting the pre-coding matrix based on feedback that is provided by user equipment in response to said at least one reference signal.

6. The method of claim 5, wherein the user equipment comprises memory containing a stored predetermined codebook of feedback codewords, and wherein the base station indicates to the user equipment a subset of said feedback codewords from which the user equipment may select a codeword, and wherein the feedback provided by the user equipment comprises a codeword selected from said subset.

7. The method of claim 6, wherein the subset indicated by the base station is derived from the first antenna configuration.

8. The method of claim 5, wherein applying the transform matrix comprises applying a plurality of transform matrices associated with a plurality of user equipment to a plurality of reference signal configurations and transmitting the plurality of reference signal configurations in a plurality of different time intervals.

9. The method of claim 1, wherein the transmitter is implemented in user equipment, and wherein applying the transform matrix comprises applying a transform matrix received from a base station.

10. The method of claim 9, wherein the transform matrix is determined based on a location of the user equipment.

11. The method of claim 9, wherein the transform matrix is determined based on a measurements made by the base station on reference signal transmissions made by the user equipment.

12. The method of claim 9, wherein applying the transform matrix comprises applying the transform matrix to at least one of a signal transmitted over a shared uplink channel or a sounding reference signal transmitted over the uplink.

13. The method of claim 1, wherein the pre-coding matrix is selected from a codebook defined for a second antenna configuration assuming a non-scattering environment, and wherein the transform matrix is determined based on information indicative of a scattering environment.

14. The method of claim 1, comprising transmitting the signal via the plurality of antennas deployed in the first antenna configuration after modifying the signal by applying the transform matrix and the pre-coding matrix.

15. A method, comprising:

selecting, at a functional entity within a wireless communication network, a transform matrix associated with user equipment, wherein the transform matrix and a pre-coding matrix are selected for application to a first signal prior to transmitting the first signal using a plurality of antennas deployed in a first antenna configuration, wherein the pre-coding matrix is selected from a codebook defined for a second antenna configuration, and wherein the transform matrix is defined based on the first antenna configuration; and

transmitting a second signal using the plurality of antennas, wherein the second signal is formed by applying the transform matrix and the pre-coding matrix to the first signal.

16. The method of claim 15, wherein selecting the transform matrix comprises selecting the transform matrix based on a location of the user equipment.

17. The method of claim 15, wherein selecting the transform matrix comprises selecting the transform matrix for application to the first signal for transmission over a downlink from a base station to the user equipment.

18. The method of claim 15, wherein selecting the transform matrix comprises selecting the transform matrix for application to the first signal for transmission over an uplink from the user equipment to at least one base station.

19. The method of claim 18, comprising providing information indicating the selected transform matrix to said at least one base station for transmission to the user equipment.

20. A method, comprising:

determining a transform matrix for a transmitter based on a first antenna configuration and a second antenna configuration, wherein the transform matrix and a pre-coding matrix are configured to be applied to a signal prior to transmitting the signal using a plurality of antennas deployed in the first antenna configuration, wherein the pre-coding matrix is selected from a codebook defined for the second antenna configuration; and

storing a representation of the transform matrix in a computer-readable form.

21. The method of claim 20, wherein determining the transform matrix comprises determining the transform matrix by simulating propagation of radiofrequency signals in a scattering environment associated with the transmitter.

22. The method of claim 20, wherein determining the transform matrix comprises determining the transform matrix based on a first antenna configuration comprising a circular antenna array and a second antenna configuration comprising a linear antenna array.

23. The method of claim 20, wherein determining the transform matrix comprises determining the transform matrix based on a first antenna configuration comprising a first linear antenna array having a first orientation and a second antenna configuration comprising a second linear antenna array having a second orientation that is different than the first orientation.

24. The method of claim 20, wherein determining the transform matrix comprises determining the transform matrix for application to a downlink signal transmitted from a base station to user equipment.

25. The method of claim 24, comprising calibrating the transform matrix based on measurements feedback from the user equipment indicating a signal-to-noise ratio for signals modified using the transform matrix and received by the user equipment.

26. The method of claim 20, wherein determining the transform matrix comprises determining the transform matrix for application to an uplink signal transmitted from user equipment to a base station.

27. The method of claim 26, comprising calibrating the transform matrix by providing a plurality of transform matrices to the user equipment and selecting at least one of the provided transform matrices based on measured qualities of signals received from the user equipment.

28. (canceled)

29. A transmitter, comprising:

a transceiver configured to transmit or receive signals using a plurality of antennas deployed in a first antenna configuration;

a pre-coding matrix generator for generating or storing a codebook comprising a plurality of pre-coding matrices defined for a second antenna configuration;

a transform matrix generator for generating or storing at least one transform matrix derived from at least the first antenna configuration, wherein the transceiver is configurable to apply said at least one transform matrix and a pre-coding matrix selected from the codebook to a signal prior to transmitting the signal.

30. The transmitter of claim 29, wherein the transmitter is implemented in a base station, and wherein applying the transform matrix comprises selecting a transform matrix based on location information for user equipment and wherein the transceiver is configurable to apply the selected transform matrix to signals transmitted over a downlink towards the user equipment.

31. The transmitter of claim 29, wherein the transmitter is implemented in user equipment, and wherein the transform matrix generator is configured to store said at least one transform matrix received from a base station.

32. The transmitter of claim 29, wherein the transform matrix generator is configurable to generate said at least one transform matrix based on a location of the user equipment.

33. A base station, comprising:

a plurality of antennas deployed in a first antenna configuration;

a transmitter configured to transmit signals using the plurality of antennas;

a pre-coding matrix generator for generating or storing a codebook comprising a plurality of pre-coding matrices defined for a second antenna configuration;

a transform matrix generator for generating or storing at least one transform matrix derived from at least the first antenna configuration, wherein the transceiver is configurable to apply said at least one transform matrix and a pre-coding matrix selected from the codebook to a signal prior to transmitting the signal.

34. The base station of claim 33, wherein the base station is configurable to select a transform matrix based on location information for user equipment and the transmitter is configurable to apply the selected transform matrix to signals transmitted over a downlink towards the user equipment.

35. The base station of claim 33, wherein the transmitter is configurable to apply the transform matrix to at least one reference signal transmitted using the plurality of antennas, and wherein the base station is configurable to select the pre-coding matrix based on feedback that is provided by user equipment in response to said at least one reference signal.

36. The base station of claim 35, wherein the transmitter is configurable to transmit signals to the user equipment indicating a subset of said feedback codewords from which the user equipment may select a codeword, and wherein the feedback provided by the user equipment comprises a codeword selected from said subset.

37. The base station of claim 36, wherein the subset indicated by the base station is derived from the first antenna configuration.

38. The base station of claim 33, wherein the transmitter is configured to apply a plurality of transform matrices associated with a plurality of user equipment to a plurality of reference signal configurations and transmit the plurality of reference signal configurations in a plurality of different time intervals.

39. User equipment, comprising:

a plurality of antennas deployed in a first antenna configuration;

a transmitter configured to transmit signals using the plurality of antennas;

a pre-coding matrix generator for generating or storing a codebook comprising a plurality of pre-coding matrices defined for a second antenna configuration;

a transform matrix generator for generating or storing at least one transform matrix derived from at least the first antenna configuration, wherein the transceiver is configurable to apply said at least one transform matrix and a pre-coding matrix selected from the codebook to a signal prior to transmitting the signal.

40. The user equipment of claim 39, wherein the user equipment is configurable to receive information indicating said at least one transform matrix from the base station, and wherein the transmitter is configurable to apply said at least one transform matrix received from the base station.

41. The user equipment of claim 39, wherein said at least one transform matrix is determined based on a location of the user equipment.

42. The user equipment of claim 39, wherein the transform matrix generator is configurable to determine said at least one transform matrix based on a measurement made by the base station on reference signal transmission made by the user equipment.

43. The user equipment of claim 39, wherein the transmitter is configured to apply the transform matrix to at least one of a signal transmitted over a shared uplink channel or a sounding reference signal transmitted over the uplink.

44. The user equipment of claim 39, wherein the user equipment is configured to select at least one pre-coding matrix to be used by a base station to transmit downlink signals, wherein said at least one pre-coding matrix is selected based upon measurements performed on at least one downlink signal received from the base station.

45. The user equipment of claim 44, wherein the transmitter is configured to transmit feedback indicating said at least one pre-coding matrix.