Method and apparatus for allocating downlink resources in a multiple-input multiple-output (MIMO) communication system

• US 7,907,972 B2
• Filed: 06/21/2007
• Issued: 03/15/2011
• Est. Priority Date: 05/16/2001
• Status: Expired due to Fees

• Current Assignee: Qualcomm, Inc.
• Original Assignee: Qualcomm, Inc.
• Inventors: Walton, Jay R., Howard, Steven J., Wallace, Mark S.
• Primary Examiner(s): VO, NGUYEN THANH
• Application Number:
  US11/766,362
• Publication Number:
  US 20080013638A1
• Time in Patent Office: 1,363 Days
• Field of Search: 455/562.1, 455/450, 455/451, 455/452.1, 455/452.2, 455/561, 455/69, 455/101, 455/102, 455/103, 455/509, 455/513, 375/347, 375/349
• US Class Current: 455/562.1
• CPC Class Codes: H04B 7/0417 Feedback systems
• CPC Class Codes: H04B 7/0452 Multi-user MIMO systems
• CPC Class Codes: H04B 7/061 using feedback from receiving side
• CPC Class Codes: H04L 1/0003 by switching between different modulation schemes
• CPC Class Codes: H04L 1/0009 by adapting the channel coding H04L1/1812 takes precedence
• CPC Class Codes: H04L 1/0026 Transmission of channel quality indication
• CPC Class Codes: H04L 1/06 using space diversity
• CPC Class Codes: H04L 2025/03426 transmission using multiple-input and multiple-output channels
• CPC Class Codes: H04L 25/0204 of multiple channels
• CPC Class Codes: H04W 16/00 Network planning, e.g. coverage or traffic planning tools; Network deployment, e.g. resource partitioning or cells structures
• CPC Class Codes: H04W 16/28 using beam steering
• CPC Class Codes: H04W 84/14 WLL [Wireless Local Loop]; RLL [Radio Local Loop]

Abstract

Techniques to schedule downlink data transmission to a number of terminals in a wireless communication system. In one method, one or more sets of terminals are formed for possible data transmission, with each set including a unique combination of one or more terminals and corresponding to a hypothesis to be evaluated. One or more sub-hypotheses may further be formed for each hypothesis, with each sub-hypothesis corresponding to specific assignments of a number of transmit antennas to the one or more terminals in the hypothesis. The performance of each sub-hypothesis is then evaluated, and one of the evaluated sub-hypotheses is selected based on their performance. The terminal(s) in the selected sub-hypothesis are then scheduled for data transmission, and data is thereafter coded, modulated, and transmitted to each scheduled terminal from one or more transmit antennas assigned to the terminal.

Claims

1. A method of transmitting data in a wireless communication system, comprising:

selecting multiple terminals to simultaneously receive a first set of multiple data streams from multiple transmit antennas in a first operating mode; and

selecting a single terminal to receive at least one data stream from the multiple transmit antennas in a second operating mode.

2. The method of claim 1, wherein each of the multiple terminals receives a single data stream in the first set.

3. The method of claim 2, further comprising:

selecting at least two terminals to simultaneously receive a second set of multiple data streams from the multiple transmit antennas in a third operating mode, wherein one of the at least two terminals receives a single data stream in the second set and another one of the at least two terminals receives at least two data streams in the second set.

4. The method of claim 1, wherein the first set includes one data stream from each of the multiple transmit antennas.

5. The method of claim 1, wherein the single terminal receives one data stream from each of the multiple transmit antennas.

6. The method of claim 1, wherein the selecting the multiple terminals comprises

evaluating multiple sets of single-input multiple-output (SIMO) terminals, and

selecting one set of SIMO terminals as the multiple terminals based on a performance metric.

7. The method of claim 1, wherein the selecting the single terminal comprises

evaluating at least one multiple-input multiple-output (MIMO) terminal, and

selecting one MIMO terminal as the single terminal based on a performance metric.

8. The method of claim 1, further comprising:

determining a performance metric for each of multiple hypotheses for the first operational mode, each of the multiple hypotheses corresponding to a different set of single-input multiple-output (SIMO) terminals;

determining the performance metric for each of at least one hypothesis for the second operational mode, each of the at least one hypothesis corresponding to a different multiple-input multiple-output (MIMO) terminal; and

selecting the first operational mode or the second operational mode based on performance metrics for the multiple hypotheses for the first operational mode and the at least one hypothesis for the second operational mode.

9. The method of claim 8, wherein the performance metric relates to throughput.

10. The method of claim 1, wherein the multiple terminals and the single terminal are selected from among a pool of terminals based on channel state information (CSI) for each terminal in the pool.

11. The method of claim 10, wherein the CSI for each terminal comprises signal-to-noise-plus-interference ratio (SNR) estimates for the multiple transmit antennas.

12. The method of claim 1, further comprising:

determining a coding and modulation scheme for each of the multiple data streams in the first set; and

determining at least one coding and modulation scheme for the at least one data stream.

13. The method of claim 1, further comprising:

transmitting the first set of data streams to the multiple terminals in a first time interval; and

transmitting the at least one data stream to the single terminal in a second time interval.

14. The method of claim 1, wherein the multiple transmit antennas are formed based on at least one beam-forming matrix.

15. The method of claim 1, wherein each of the multiple terminals is equipped with multiple receive antennas.

16. The method of claim 15, wherein the number of receive antennas for each of the multiple terminals is equal to or greater than the number of data streams in the first set.

17. An apparatus comprising:

means for selecting multiple terminals to simultaneously receive a first set of multiple data streams from multiple transmit antennas in a first operating mode; and

means for selecting a single terminal to receive at least one data stream from the multiple transmit antennas in a second operating mode.

18. The apparatus of claim 17, wherein each of the multiple terminals receives a single data stream in the first set, and wherein the apparatus further comprises:

means for selecting at least two terminals to simultaneously receive a second set of multiple data streams from the multiple transmit antennas in a third operating mode, wherein one of the at least two terminals receives a single data stream in the second set and another one of the at least two terminals receives at least two data streams in the second set.

19. The apparatus of claim 17, wherein the means for selecting the multiple terminals comprises

means for evaluating multiple sets of single-input multiple-output (SIMO) terminals, and

means for selecting one set of SIMO terminals as the multiple terminals based on a performance metric.

20. The apparatus of claim 17, wherein the means for selecting the single terminal comprises means for evaluating at least one multiple-input multiple-output (MIMO) terminal, and means for selecting one MIMO terminal as the single terminal based on a performance metric.

21. The apparatus of claim 17, further comprising:

means for determining a performance metric for each of multiple hypotheses for the first operational mode, each of the multiple hypotheses corresponding to a different set of single-input multiple-output (SIMO) terminals;

means for determining the performance metric for each of at least one hypothesis for the second operational mode, each of the at least one hypothesis corresponding to a different multiple-input multiple-output (MIMO) terminal; and

means for selecting the first operational mode or the second operational mode based on performance metrics for the multiple hypotheses for the first operational mode and the at least one hypothesis for the second operational mode.

22. An apparatus comprising:

at least one processor configured to select multiple terminals to simultaneously receive a first set of multiple data streams from multiple transmit antennas in a first operating mode, and to selecting a single terminal to receive at least one data stream from the multiple transmit antennas in a second operating mode; and

a memory coupled to the at least one processor.

23. The apparatus of claim 22, wherein each of the multiple terminals receives a single data stream in the first set, and wherein the at least one processor is configured to select at least two terminals to simultaneously receive a second set of multiple data streams from the multiple transmit antennas in a third operating mode, wherein one of the at least two terminals receives a single data stream in the second set and another one of the at least two terminals receives at least two data streams in the second set.

24. The apparatus of claim 22, wherein the at least one processor is configured to evaluate multiple sets of single-input multiple-output (SIMO) terminals and to select one set of SIMO terminals as the multiple terminals based on a performance metric.

25. The apparatus of claim 22, wherein the at least one processor is configured to evaluate at least one multiple-input multiple-output (MIMO) terminal and to select one MIMO terminal as the single terminal based on a performance metric.

26. The apparatus of claim 22, wherein the at least one processor is configured to determine a performance metric for each of multiple hypotheses for the first operational mode, each of the multiple hypotheses corresponding to a different set of single-input multiple-output (SIMO) terminals, to determine the performance metric for each of at least one hypothesis for the second operational mode, each of the at least one hypothesis corresponding to a different multiple-input multiple-output (MIMO) terminal, and to select the first operational mode or the second operational mode based on performance metrics for the multiple hypotheses for the first operational mode and the at least one hypothesis for the second operational mode.

27. A non-transitory computer-readable storage medium comprising code, which, when executed by a processor, cause the processor to perform operations for transmitting data in a wireless communication system, the non-transitory computer-readable storage medium comprising:

code for selecting multiple terminals to simultaneously receive a first set of multiple data streams from multiple transmit antennas in a first operating mode; and

code for selecting a single terminal to receive at least one data stream from the multiple transmit antennas in a second operating mode.

28. The non-transitory computer-readable storage medium of claim 27, wherein each of the multiple terminals receives a single data stream in the first set, and wherein the computer-readable storage medium further comprises:

code for selecting at least two terminals to simultaneously receive a second set of multiple data streams from the multiple transmit antennas in a third operating mode, wherein one of the at least two terminals receives a single data stream in the second set and another one of the at least two terminals receives at least two data streams in the second set.

29. The non-transitory computer-readable storage medium of claim 27, wherein the code for selecting the multiple terminals comprises

code for evaluating multiple sets of single-input multiple-output (SIMO) terminals, and

code for selecting one set of SIMO terminals as the multiple terminals based on a performance metric.

30. The non-transitory computer-readable storage medium of claim 27, wherein the code for selecting the single terminal comprises

code for evaluating at least one multiple-input multiple-output (MIMO) terminal, and

code for selecting one MIMO terminal as the single terminal based on a performance metric.

31. The non-transitory computer-readable storage medium of claim 27, further comprising:

code for determining a performance metric for each of multiple hypotheses for the first operational mode, each of the multiple hypotheses corresponding to a different set of single-input multiple-output (SIMO) terminals;

code for determining the performance metric for each of at least one hypothesis for the second operational mode, each of the at least one hypothesis corresponding to a different multiple-input multiple-output (MIMO) terminal; and

code for selecting the first operational mode or the second operational mode based on performance metrics for the multiple hypotheses for the first operational mode and the at least one hypothesis for the second operational mode.

32. A method of transmitting data in a wireless communication system, comprising:

selecting an operating mode for transmitting data streams to a plurality of terminals, the operating mode being selected from a group comprising;

a multiple-input, multiple-output (MIMO) mode in which a first set of multiple data streams from multiple transmit antennas are allocated to a single MIMO terminal employing multiple antennas, and

a single-input, multiple-output (N-SIMO) mode in which a single data stream from the first set of multiple data streams is allocated to each of a number of distinct SIMO terminals, each SIMO terminal employing multiple antennas; and

simultaneously transmitting the data streams to the plurality of terminals in accordance with the selected operating mode.

33. The method of claim 32, wherein the group of operating modes further comprises:

a mixed-mode in which the first set of multiple data streams is allocated to a combination of SIMO and MIMO terminals, with both types of terminals being simultaneously supported.