Method and system for providing multi-input-multi-output (MIMO) downlink transmission

• US 20050259627A1
• Filed: 05/19/2004
• Published: 11/24/2005
• Est. Priority Date: 05/19/2004
• Status: Active Grant

• Current Assignee: DIRECTV, LLC (AT&T, Inc.)
• Original Assignee: The DIRECTV Group, Inc. (AT&T, Inc.)
• Inventors: Song, Jian, Karimullah, Khalid
• Granted Patent: US 7,492,749 B2
• Time in Patent Office: Days
• US Class Current: 370/342
• CPC Class Codes: H04B 7/04 using two or more spaced independent antennas
• CPC Class Codes: H04B 7/0626 Channel coefficients, e.g. channel state information [CSI]
• CPC Class Codes: H04B 7/0691 using subgroups of transmit antennas
• CPC Class Codes: H04B 7/0851 using training sequences or error signal minimizing error signal H04B7/0854
• CPC Class Codes: H04B 7/0862 receiver computing weights based on information from the transmitter
• CPC Class Codes: H04L 5/0007 the frequencies being orthogonal, e.g. OFDM(A), DMT
• CPC Class Codes: H04L 5/0023 Time-frequency-space
• CPC Class Codes: H04L 5/0028 Variable division signaling therefor H04L5/0092
• CPC Class Codes: H04L 5/006 Quality of the received signal, e.g. BER, SNR, water filling
• CPC Class Codes: H04W 52/34 TPC management, i.e. sharing limited amount of power among users or channels or data types, e.g. cell loading

Abstract

An approach is provided for supporting transmission in a multi-input-multi-output (MIMO) communication system including a plurality of terminals. A preamble portion of a frame is transmitted by a multiple transmit antennas of a hub using Orthogonal Frequency Division Multiplexing (OFDM) to the terminals over a channel, wherein each of the terminals determines a characteristic of the channel with respect to the transmit antennas as feedback information. The hub receives the feedback information from the terminals. The hub selects, according to the feedback information, a subset of the antennas for transmission of a remaining portion of the frame to the terminal.

Claims

1. A method for supporting transmission in a multi-input-multi-output (MIMO) communication system including a plurality of terminals, the method comprising:

transmitting a preamble portion of a frame from a plurality of antennas to the terminals over a channel, wherein each of the terminals determines a characteristic of the channel with respect to the antennas as feedback information;

receiving the feedback information from the terminals; and

selecting, according to the feedback information, a subset of the antennas for transmission of a remaining portion of the frame to the terminals.

2. A method according to claim 1, wherein the characteristic specifies a complete frequency response of the channel over an entire allocated bandwidth.

3. A method according to claim 1, wherein the frame is transmitted to the terminals using Orthogonal Frequency Division Multiplexing (OFDM), each of the antennas being assigned a subset of OFDM sub-carriers.

4. A method according to claim 3, wherein the subset assignment is different from frame to frame.

5. A method according to claim 1, further comprising:

transmitting the remaining portion of the frame over the subset of antennas, wherein the subset includes two antennas among a total of four antennas.

6. A method according to claim 5, wherein each of the terminals includes two antennas for receiving the frame.

7. A method according to claim 1, wherein the preamble portion is transmitted over a downlink channel and the feedback information is received over a return channel that is of a lower transmission rate than the downlink channel.

8. A method according to claim 1, further comprising:

adjusting, based on the feedback information, one of transmission power and transmission rate for transmitting the frame.

9. A method according to claim 1, further comprising:

adjusting, based on the feedback information, transmission power and transmission rate for transmitting the frame.

10. A method according to claim 1, wherein one of the terminals is not within a line of sight of the subset of antennas.

11. A method according to claim 1, wherein the frame includes a plurality of distinct data streams for receipt by corresponding ones of the terminals.

12. A computer-readable medium bearing instructions for supporting transmission in a multi-input-multi-output (MIMO) communication system including a plurality of terminals, said instruction, being arranged, upon execution, to cause one or more processors to perform the method of claim 1.

13. A hub device for supporting transmission in a multi-input-multi-output (MIMO) communication system including a plurality of terminals, the device comprising:

means for transmitting a preamble portion of a frame from a plurality of antennas to the terminals over a channel, wherein each of the terminals determines a characteristic of the channel with respect to the antennas as feedback information;

means for receiving the feedback information from the terminals; and

a processor configured to select, according to the feedback information, a subset of the antennas among a plurality of antennas for transmission of a remaining portion of the frame to the terminals.

14. A device according to claim 13, wherein the characteristic specifies a complete frequency response of the channel over an entire allocated bandwidth.

15. A device according to claim 13, wherein the frame is transmitted to the terminals using Orthogonal Frequency Division Multiplexing (OFDM), each of the antennas being assigned a subset of OFDM sub-carriers.

16. A device according to claim 15, wherein the subset assignment is different from frame to frame.

17. A device according to claim 13, wherein the remaining portion of the frame is transmitted over the subset of antennas, wherein the subset includes two antennas among a total of four antennas.

18. A device according to claim 17, wherein each of the terminals includes two antennas for receiving the frame.

19. A device according to claim 13, wherein the preamble portion is transmitted over a downlink channel and the feedback information is received over a return channel that is of a lower transmission rate than the downlink channel.

20. A device according to claim 13, further comprising:

means for adjusting, based on the feedback information, one of transmission power and transmission rate for transmitting the frame.

21. A device according to claim 13, further comprising:

means for adjusting, based on the feedback information, transmission power and transmission rate for transmitting the frame.

22. A device according to claim 13, wherein one of the terminals is not within a line of sight of the subset of antennas.

23. A device according to claim 13, wherein the frame includes a plurality of distinct data streams for receipt by corresponding ones of the terminals.

24. A method for communicating in a multi-input-multi-output (MIMO) communication system including a hub, the method comprising:

receiving a preamble portion of a frame from a plurality of antennas of the hub over a channel;

determining a characteristic of the channel with respect to the antennas as feedback information; and

transmitting the feedback information to the hub,

wherein the hub selects, according to the feedback information, a subset of the antennas among a plurality of antennas of the hub for transmission of a remaining portion of the frame.

25. A method according to claim 24, wherein the characteristic specifies a complete frequency response of the channel over an entire allocated bandwidth.

26. A method according to claim 24, wherein the frame is transmitted by the hub over the channel using Orthogonal Frequency Division Multiplexing (OFDM), the frame corresponding to a subset of OFDM sub-carriers.

27. A method according to claim 26, wherein the subset is assigned differently from frame to frame.

28. A method according to claim 24, wherein the remaining portion of the frame is transmitted over the subset of antennas, wherein the subset includes two antennas among a total of four antennas.

29. A method according to claim 28, wherein the preamble portion of the frame is received over two local antennas.

30. A method according to claim 24, wherein the preamble portion is received over a downlink channel and the feedback information is transmitted over a return channel that is of a lower transmission rate than the downlink channel.

31. A method according to claim 24, wherein the hub adjusts, based on the feedback information, one of transmission power and transmission rate for transmitting the frame.

32. A method according to claim 24, wherein the hub adjusts, based on the feedback information, transmission power and transmission rate for transmitting the frame.

33. A method according to claim 24, wherein the hub is not within a line of sight.

34. A method according to claim 24, wherein the frame includes a plurality of distinct data streams.

35. A computer-readable medium bearing instructions for communicating in a multi-input-multi-output (MIMO) communication system including a hub, said instruction, being arranged, upon execution, to cause one or more processors to perform the method of claim 24.

36. A terminal device for communicating in a multi-input-multi-output (MIMO) communication system including a hub, the device comprising:

means for receiving a preamble portion of a frame from a plurality of antennas of the hub over a channel;

means for determining a characteristic of the channel with respect to the antennas as feedback information; and

means for transmitting the feedback information to the hub,

wherein the hub selects, according to the feedback information, a subset of the antennas among a plurality of antennas of the hub for transmission of a remaining portion of the frame.

37. A device according to claim 36, wherein the characteristic specifies a complete frequency response of the channel over an entire allocated bandwidth.

38. A device according to claim 36, wherein the frame is transmitted by the hub over the channel using Orthogonal Frequency Division Multiplexing (OFDM), the frame corresponding to a subset of OFDM sub-carriers.

39. A device according to claim 38, wherein the subset is assigned differently from frame to frame.

40. A device according to claim 36, wherein the remaining portion of the frame is transmitted over the subset of antennas, wherein the subset includes two antennas among a total of four antennas.

41. A device according to claim 40, wherein the preamble portion of the frame is received over two local antennas.

42. A device according to claim 36, wherein the preamble portion is received over a downlink channel and the feedback information is transmitted over a return channel that is of a lower transmission rate than the downlink channel.

43. A device according to claim 36, wherein the hub adjusts, based on the feedback information, one of transmission power and transmission rate for transmitting the frame.

44. A device according to claim 36, wherein the hub adjusts, based on the feedback information, transmission power and transmission rate for transmitting the frame.

45. A device according to claim 36, wherein the hub is not within a line of sight.

46. A device according to claim 36, wherein the frame includes a plurality of distinct data streams.

47. A method for distributing audio/video information in a point-to-multipoint multiple access system including a hub communicating with a plurality of terminals, the method comprising:

generating a preamble symbol according to an Orthogonal Frequency Division Multiplexing (OFDM) scheme, wherein all OFDM sub-carriers are divided uniformly into a plurality of sub-carrier sets, the sub-carrier sets being assigned to a respective plurality of antennas of the hub;

transmitting the preamble symbol, based on the sub-carrier set assignment, to the terminals for determination of channel response by the respective terminals to provide feedback information to the hub;

receiving the feedback information from the terminals; and

mapping data symbols associated with the preamble symbol to one or more of the antennas, according to the feedback information, for transmission to the terminals.

48. A point-to-multipoint multiple access system for distributing audio/video information, the system comprising:

a hub configured to generate a preamble symbol according to an Orthogonal Frequency Division Multiplexing (OFDM) scheme, wherein all OFDM sub-carriers are divided uniformly into a plurality of sub-carrier sets, the sub-carrier sets being assigned to a respective plurality of antennas of the hub; and

a plurality of terminals communicating with the hub, wherein the hub transmits the preamble symbol, based on the sub-carrier set assignment, to the terminals for determination of channel response by the respective terminals to provide feedback information to the hub,

wherein the hub is further configured to map data symbols associated with the preamble symbol to one or more of the antennas, according to the feedback information, for transmission to the terminals.