High Data Rate Closed Loop MIMO Scheme Combining Transmit Diversity and Data Multiplexing

• US 20060291581A1
• Filed: 08/30/2006
• Published: 12/28/2006
• Est. Priority Date: 11/21/2001
• Status: Active Grant

• Current Assignee: Apple Inc.
• Original Assignee: Anand G. Dabak, Eko N. Onggosanusi, Timothy M. Schmidl
• Inventors: Onggosanusi, Eko N., Dabak, Anand G., Schmidl, Timothy M.
• Granted Patent: US 7,715,798 B2
• Time in Patent Office: Days
• US Class Current: 375/267
• CPC Class Codes: H04B 7/0632 Channel quality parameters, e.g. channel quality indicator [CQI]
• CPC Class Codes: H04B 7/0854 using error minimizing algorithms, e.g. minimum mean squared error [MMSE], "cross-correlation" or matrix inversion
• CPC Class Codes: H04B 7/0857 using maximum ratio combining techniques, e.g. signal-to- interference ratio [SIR], received signal strenght indication [RSS]

Abstract

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.

Claims

1-24. -24. (canceled)

25. A method of transmission of a symbol stream, comprising:

(a) providing P transmit antennas where P is an integer greater than or equal to 3;

(b) providing M symbol streams to transmit from said P antennas through communication channels where M is an integer greater than or equal to 2;

(c) providing weights for said P antennas, said weights multiplying said symbols.

26. The method of claim 25, wherein said weights of step (c) are derived from the estimates of communication channels from said P antennas to Q receive antenna(s) where Q is a positive integer.

27. The method of claim 25, wherein said weights of step (c) are derived from the estimates of communication channels from said P antennas to Q receive antenna(s) where Q is a positive integer

28. The method of claim 27, further comprising a method for detecting said M data streams at said Q antenna(s),

29. The method of claim 25, wherein said weights of step (c) are selected from a finite set of P-by-M matrices.

30. The method of claim 25, wherein said weights of step (c) are selected by maximizing a minimum signal-to-interference-plus-noise ratio of said M symbol streams after detection.

31. The method of claim 27, wherein said M data streams are detected using one of the group of linear zero-forcing, linear minimum mean square error, iterative zero-forcing, and iterative minimum mean square error.

32. The method of claim 27, wherein said M data streams are detected using a maximum likelihood detector with SER selection criterion.

33. The method of claim 25, wherein said weights of step (c) correspond to a diagonal M×

M block matrix of (P/M)×

1 blocks where each (P/M)×

1 block corresponds to weights for a symbol stream of said M symbol streams.

34. The method of claim 25, wherein said weights of step (c) correspond to a (P/M)×

1 block matrix of M×

M blocks where each M×

M block is an M×

M unitary matrix.

35. The method of claim 25, wherein said weights of step (c) are received from a receiver in said channels.

36. The method of claim 35, wherein said weights of step (c) are provided by channel information in said receiver.

37. The method of claim 25, wherein:

(a) said weights of step (c) are derived from estimates of communication channels from said P antennas to Q receive antenna(s).

(b) said channel estimates are updated; and

(c) said weights are updated in response to said channel estimates update.

38. The method of claim 25, wherein said M symbol streams of step (b) are derived from a single input symbol stream.

39. The method of claim 25, wherein at least one of said communication channels is a wideband or code division multiple access (CDMA) channel with multiple users.

40. The method of claim 25, wherein at least one of said communication channels is a wideband or CDMA channel with a single user with multiple codes.

41. The method of claim 25, wherein at least one of said communication channels is a narrowband or time division multiple access (TDMA) channel.

42. The method of claim 25, wherein at least one of said communication channels is an OFDM-type channel.

43. A method of transmitting a symbol stream, comprising:

(a) providing a transmitter with P transmit antennas where P is an integer greater than or equal to 3;

(b) providing M symbol streams to transmit from said P antennas through said communication channels where M is an integer greater than or equal to 2;

(c) providing weights for said P antennas, said weights multiplying said symbols;

(d) providing a receiver with Q receive antennas where Q is a positive integer; and

(e) wherein said weights of step (c) are derived from reception from said receiver in said channel.

44. A transmitter, comprising:

(a) P transmit antennas where P is an integer greater than or equal to 3;

(b) an apparatus for generating PM weights from signal reception from a receiver, where M is less than P; and

(c) M symbol stream inputs coupled to said P antennas by said weights.

45. The transmitter of claim 44, wherein said weights are all 0 except for M sets, each set of size P/M, and each of said M sets couples one of said data streams to a set of P/M antennas.

46. The transmitter of claim 44, wherein said weights are partitioned into P/M sets, each set forming an M×

M unitary transformation of symbols at said M data stream inputs, and each of said P/M sets couples said M data streams inputs to a corresponding set of M antennas.

47. The transmitter of claim 44, wherein said weights are determined outside of said transmitter and received by said transmitter in signals from said receiver.

48. The transmitter of claim 44, wherein said weights are determined at said transmitter from signals from said receiver, wherein said signals comprise channel information.

49. The transmitter of claim 44, further comprising P streams coupled to said P transmit antennas by at least one OFDM modulator.

50. A receiver, comprising:

(a) Q receive antennas where Q is a positive integer;

(b) a channel estimator for estimating communication channels from P transmit antennas to said receive antenna(s);

(c) an apparatus for selecting MP weights as a response to said channel estimates, where M is less than P;

(d) a detector for extracting M symbol streams, wherein said detector responds to said channel estimates and previously selected weights.

51. The receiver of claim 50, wherein said selection of weights is signaled to the transmitter via a feedback channel.

52. The receiver of claim 50, wherein channel information derived from said channel estimates is signaled to the transmitter via a feedback channel.

53. The receiver of claim 50, wherein the said detector is selected from a group consisting of linear zero-forcing, linear minimum mean square error, iterative zero-forcing, iterative minimum mean square error, and maximum likelihood detectors.