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

• US 7,492,749 B2
• Filed: 05/19/2004
• Issued: 02/17/2009
• 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
• Primary Examiner(s): D'Agosta; Stephen M
• Application Number:
  US10/849,101
• Publication Number:
  US 20050259627A1
• Time in Patent Office: 1,735 Days
• Field of Search: 370/348, 370/347, 370/338, 370/328, 370/208, 370/341, 370/342, 455450-453, 455/101, 455/132, 455/143, 342/383
• 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 of audio/video data in a multi-input-multi-output (MIMO) communication system including a plurality of terminals, the method comprising:

receiving a satellite signal and shifting a frequency of the received signal;

transmitting a preamble portion of a frame from a plurality of antennas to the terminals over a downlink channel using Orthogonal Frequency Division Multiplexing (OFDM), each of the antennas being assigned a distinct subset of OFDM sub-carriers, wherein each of the terminals determines a characteristic that specifies a complete frequency response of the channel over an entire allocated bandwidth, with respect to the antennas as feedback information;

receiving the feedback information from the terminals over a return channel that is of a lower transmission rate than the downlink channel; and

selecting, according to the feedback information for the associated frame, a subset of the antennas for transmission of a remaining portion of the frame to the terminals, wherein at least one of the terminals is not within a line of sight of the subset of antennas.

2. A method according to claim 1, wherein the subset assignment is different from frame to frame.

3. 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.

4. A method according to claim 3, wherein each of the terminals includes two antennas for receiving the frame.

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

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

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

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

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

8. A method according to claim 1, further comprising providing a personal computer with internet access via the satellite signal.

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

means for receiving a signal from a satellite system;

means for transmitting a preamble portion of a frame from a plurality of antennas to the terminals over a downlink channel using Orthogonal Frequency Division Multiplexing (OFDM), each of the antennas being assigned a distinct subset of OFDM sub-carriers, wherein each of the terminals determines a characteristic that specifies a complete frequency response of the channel over an entire allocated bandwidth, with respect to the antennas as feedback information;

means for receiving the feedback information from the terminals over a return channel that is of a lower transmission rate than the downlink channel; and

a processor configured to select, according to the feedback information for the associated frame, a subset of the antennas among a plurality of antennas for transmission of a remaining portion of the frame to the terminals, wherein at least one of the terminals is not within a line of sight of the subset of antennas.

10. A device according to claim 9, wherein the subset assignment is different from frame to frame.

11. A device according to claim 9, 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.

12. A device according to claim 11, wherein each of the terminals includes two antennas for receiving the frame.

13. A device according to claim 9, further comprising:

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

14. A device according to claim 9, further comprising:

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

15. A device according to claim 9, wherein the frame includes a plurality of distinct data streams for receipt by corresponding ones of the terminals.

16. A device according to claim 9, further comprising means for providing a personal computer with data access via the satellite system.

17. 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:

receiving a satellite signal having a first frequency;

converting the received signal to a second frequency different from the first frequency;

providing a personal computer with internet access via the satellite signal;

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, wherein the subset assignment is different from frame to frame;

transmitting the preamble symbol over a downlink channel, 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 over a return channel that is of a lower transmission rate than the downlink channel, wherein at least one of the terminals is not within a line of sight of the subset of antennas;

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.

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

a hub configured to receive a satellite signal having a first frequency, convert the received signal to a second frequency different from the first frequency, providing a personal computer with internet access via the satellite signal, 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, wherein the subset assignment is different from frame to frame; and

a plurality of terminals communicating with the hub, wherein the hub transmits the preamble symbol over a downlink channel, 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 over a return channel that is of a lower transmission rate than the downlink channel, wherein at least one of the terminals is not within a line of sight of the subset of antennas, and

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.

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

receiving a satellite signal and shifting a frequency of the received signal;

transmitting a preamble portion of a frame from a plurality of antennas to the terminals over a channel using Orthogonal Frequency Division Multiplexing (OFDM), each of the antennas being assigned a distinct subset of OFDM sub-carriers, wherein the subset assignment is different from frame to frame, and wherein each of the terminals determines a characteristic that specifies a complete frequency response of the channel over an entire allocated bandwidth, with respect to the antennas as feedback information;

receiving the feedback information from the terminals; and

selecting, according to the feedback information for the associated frame, a subset of the antennas for transmission of a remaining portion of the frame to the terminals, wherein at least one of the terminals is not within a line of sight of the subset of antennas.

20. A method according to claim 19, 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.