Multiple-access multiple-input multiple-output (MIMO) communication system

• US 20060121946A1
• Filed: 01/13/2006
• Published: 06/08/2006
• Est. Priority Date: 11/06/2001
• Status: Active Grant

• Current Assignee: Jay R. Walton, Mark Wallace, Steven J. Howard
• Original Assignee: Jay R. Walton, Mark Wallace, Steven J. Howard
• Inventors: Howard, Steven J., Wallace, Mark, Walton, Jay R.
• Granted Patent: US 7,636,573 B2
• Time in Patent Office: Days
• US Class Current: 455/561
• CPC Class Codes: H04B 7/0417 Feedback systems
• CPC Class Codes: H04B 7/0452 Multi-user MIMO systems
• CPC Class Codes: H04B 7/0626 Channel coefficients, e.g. channel state information [CSI]
• CPC Class Codes: H04B 7/066 Combined feedback for a number of channels, e.g. over several subcarriers like in orthogonal frequency division multiplexing [OFDM]
• CPC Class Codes: H04B 7/0689 using different transmission schemes, at least one of them being a diversity transmission scheme
• CPC Class Codes: H04B 7/0891 Space-time diversity rake receivers H04B1/7115; space-time decoding H04L1/0631
• CPC Class Codes: H04L 1/0026 Transmission of channel quality indication
• CPC Class Codes: H04L 1/0687 Full feedback
• CPC Class Codes: H04L 1/0693 Partial feedback, e.g. partial channel state information [CSI]

Abstract

Techniques to achieve better utilization of the available resources and robust performance for the downlink and uplink in a multiple-access MIMO system. Techniques are provided to adaptively process data prior to transmission, based on channel state information, to more closely match the data transmission to the capacity of the channel. Various receiver processing techniques are provided to process a data transmission received via multiple antennas at a receiver unit. Adaptive reuse schemes and power back-off are also provided to operate the cells in the system in a manner to further increase the spectral efficiency of the system (e.g., reduce interference, improve coverage, and attain high throughput). Techniques are provided to efficiently schedule data transmission on the downlink and uplink. The scheduling schemes may be designed to optimize transmissions (e.g., maximize throughput) for single or multiple terminals in a manner to meet various constraints and requirements.

Claims

1. A method for transmitting data in a multiple-access multiple-input multiple-output (MIMO) communication system, comprising:

updating at least one parameter utilized to schedule transmission for each of a plurality of terminals;

ranking the terminals for scheduling based upon the at least one parameter;

selecting terminals for data transmission based upon the ranking;

assigning channels for data transmission for the terminals that were selected, wherein assigning includes assigning a spatial multiplexing mode for data transmission for each terminal; and

performing data transmission for the selected terminals.

2. The method of claim 1, wherein performing comprises transmitting data to the terminals.

3. The method of claim 1, wherein performing comprises receiving data transmissions from the terminals.

4. The method of claim 1, wherein at least one of the spatial multiplexing modes assigned is a multi-user MIMO mode characterized by use of the plurality of transmit antennas for data transmission to a plurality of the terminals collectively having a plurality of receive antennas.

5. The method of claim 1, wherein at least one of the spatial multiplexing modes assigned is a mixed mode characterized by use of the plurality of transmit antennas for data transmission to a combination of terminals having a single receive antenna and terminals each having a plurality of receive antennas.

6. The method of claim 1, wherein at least one of the spatial multiplexing modes assigned is a diversity mode characterized by use of the plurality of transmit antennas for reliable transmission of a single data stream to a single terminal having a plurality of receive antennas.

7. The method of claim 1, wherein at least one of the spatial multiplexing modes assigned is a transmit diversity mode characterized by use of the plurality of transmit antennas for data transmission to a single terminal having a single receive antenna.

8. The method of claim 1, wherein updating comprises updating channel state information (CSI).

9. The method of claim 8, wherein updating CSI comprises processing received CSI from the terminals to update the CSI.

10. The method of claim 8, wherein updating CSI comprises processing transmissionf from the terminals to determine CSI to update the CSI.

11. The method of claim 1, wherein ranking comprises ranking based upon an average throughput of the terminal.

12. The method of claim 1, further comprising adjusting at least one characteristic of modulated signals prior to performing data transmission for the selected terminals.

13. The method of claim 12, wherein adjusting comprises adjusting a transmit power.

14. The method of claim 12, wherein adjusting comprises adjusting data rates.

15. The method of claim 1, further comprising determining power levels for transmitting data for the terminals based upon one or more power back-off factors indicative of maximum allowed power levels.

16. The method of claim 15, wherein the one or more power back-off factors are selected to reduce interference to adjacent cells.

17. The method of claim 15, wherein the one or more power back-off factors are selected based on system loading.

18. The method of claim 15, wherein the one or more power back-off factors are selected based on achievable performance by terminals within the system.

19. A base station in a multiple-access multiple-input multiple-output (MIMO) communication system, comprising:

a controller configured to update at least one parameter utilized to schedule transmission for each of a plurality of terminals;

a scheduler operative to rank the terminals for scheduling based upon the at least one parameter, select terminals for data transmission based upon the ranking, and assigning channels for data transmission for the terminals that were selected, wherein assigning includes assigning a spatial multiplexing mode for data transmission for each terminal;

a TX data processor operative to process data for the one or more terminals; and

a plurality of transmit antennas configured to transmit data transmission to the selected terminals.

20. The apparatus of claim 19, wherein at least one of the spatial multiplexing modes assigned is a multi-user MIMO mode characterized by use of the plurality of transmit antennas for data transmission to a plurality of the terminals collectively having a plurality of receive antennas.

21. The apparatus of claim 19, wherein at least one of the spatial multiplexing modes assigned is a mixed mode characterized by use of the plurality of transmit antennas for data transmission to a combination of terminals having a single receive antenna and terminals each having a plurality of receive antennas.

22. The apparatus of claim 19, wherein at least one of the spatial multiplexing modes assigned is a diversity mode characterized by use of the plurality of transmit antennas for reliable transmission of a single data stream to a single terminal having a plurality of receive antennas.

23. The apparatus of claim 19, wherein at least one of the spatial multiplexing modes assigned is a transmit diversity mode characterized by use of the plurality of transmit antennas for data transmission to a single terminal having a single receive antenna.

24. The apparatus of claim 19, wherein controller updates the at least one parameter by updating channel state information (CSI).

25. The apparatus of claim 19, wherein the controller ranks based upon an average throughput of the terminal.

26. The apparatus of claim 19, wherein the controller determines power levels for transmitting data for the terminals based upon one or more power back-off factors indicative of maximum allowed power levels.

28. The apparatus of claim 26, wherein at least one of the spatial multiplexing modes assigned is a multi-user MIMO mode characterized by use of the plurality of transmit antennas for data transmission to a plurality of the terminals collectively having a plurality of receive antennas.

29. The apparatus of claim 26, wherein at least one of the spatial multiplexing modes assigned is a mixed mode characterized by use of the plurality of transmit antennas for data transmission to a combination of terminals having a single receive antenna and terminals each having a plurality of receive antennas.

30. The apparatus of claim 26, wherein wherein at least one of the spatial multiplexing modes assigned is a diversity mode characterized by use of the plurality of transmit antennas for reliable transmission of a single data stream to a single terminal having a plurality of receive antennas.

31. The apparatus of claim 26, wherein at least one of the spatial multiplexing modes assigned is a transmit diversity mode characterized by use of the plurality of transmit antennas for data transmission to a single terminal having a single receive antenna.

32. The apparatus of claim 26, wherein the means for updating comprises means for updating channel state information (CSI).

33. The apparatus of claim 26, wherein the means for ranking comprises means for ranking based upon an average throughput of the terminal.

34. The apparatus of claim 26, further comprising means for adjusting at least one characteristic of modulated signals prior to performing data transmission for the selected terminals.

35. The apparatus of claim 26, further comprising means for determining power levels for transmitting data for the terminals based upon one or more power back-off factors indicative of maximum allowed power levels.

27. An apparatus comprising:

means for updating at least one parameter utilized to schedule transmission for each of a plurality of terminals;

means for ranking the terminals for scheduling based upon the at least one parameter;

means for selecting terminals for data transmission based upon the ranking;

means for assigning channels for data transmission for the terminals that were selected, wherein assigning includes assigning a spatial multiplexing mode for data transmission for each terminal; and

means for performing data transmission for the selected terminals.