APPROACH TO A UNIFIED SU-MIMO/MU-MIMO OPERATION

• US 20080132281A1
• Filed: 08/20/2007
• Published: 06/05/2008
• Est. Priority Date: 08/21/2006
• Status: Active Grant

• Current Assignee: Qualcomm, Inc.
• Original Assignee: Qualcomm, Inc.
• Inventors: Malladi, Durga Prasad, Kim, Byoung-Hoon
• Granted Patent: US 8,271,043 B2
• Time in Patent Office: Days
• US Class Current: 455/562.1
• CPC Class Codes: H04B 17/24 with feedback of measurements to the transmitter
• CPC Class Codes: H04B 17/336 Signal-to-interference ratio [SIR] or carrier-to-interference ratio [CIR]
• CPC Class Codes: H04B 7/0413 MIMO systems
• CPC Class Codes: H04B 7/0465 taking power constraints at power amplifier or emission constraints, e.g. constant modulus, into account
• CPC Class Codes: H04B 7/063 Parameters other than those covered in groups H04B7/0623 - H04B7/0634, e.g. channel matrix rank or transmit mode selection
• CPC Class Codes: H04B 7/0632 Channel quality parameters, e.g. channel quality indicator [CQI]
• CPC Class Codes: H04B 7/0634 Antenna weights or vector/matrix coefficients
• CPC Class Codes: H04B 7/0686 Hybrid systems, i.e. switching and simultaneous transmission
• CPC Class Codes: H04B 7/0874 using subgroups of receive antennas
• CPC Class Codes: H04W 72/542 using measured or perceived quality

Abstract

An apparatus and method to dynamically schedule user devices in a wireless communication system in single-user multiple-input multiple-output (SU-MIMO) or multiple-user multiple-input multiple-output (MU-MIMO) modes of operation. The dynamic scheduling employs an efficient differential reporting of channel state information that reduces uplink feedback overhead, whereby a base layer value of a channel quality indicator (CQI) is reported in conjunction with a CQI offset value. Antenna subset selection is also reported. The offset value reflects gains by detection with successive interference cancellation if multiple antennas are reported (rank>1), while it reflects the actual offset between single-layer SU-MIMO CQI and MU-MIMO CQI if a single antenna is reported. Scheduled SU-MIMO mode of operation is optimized for a user reporting either a single antenna or multiple antennas, whereas MU-MIMO operation is optimized for a user reporting a single antenna.

Claims

1. An apparatus that operates in a wireless communication environment, the apparatus comprising:

a processor configured to evaluate a channel quality indicator (CQI) base layer value (CQI), a CQI offset value (Δ

CQI), to select a virtual or physical antenna set, and to report the evaluated CQI, Δ

CQI and the selected virtual or physical antenna set; and

a memory coupled to the processor for storing the evaluated data.

2. The apparatus of claim 1, the processor further configured to detect data employing successive interference cancellation.

3. The apparatus of claim 1, the channel quality indicator corresponding at least to one of signal-to-noise-and-interference ratio, throughput, and peak data rate.

4. The apparatus of claim 1, the processor evaluates channel quality indicator base layer value by assuming single-user multiple-input multiple-output operation mode

5. The apparatus of claim 1, the processor evaluates the channel quality indicator base layer value as the average of channel quality indicator full values over a set of multiple virtual antennas.

6. The apparatus of claim 1, the processor evaluates the channel quality indicator base layer value by assuming that data layers are symmetrically permuted in frequency-domain or time-domain before being transmitted over a set of multiple virtual antennas, the permutation further assumed to be at least simple cyclic or pseudo-random.

7. The apparatus of claim 1, the processor computes successive interference cancellation gains between successively decoded data layers when multiple virtual antennas are selected.

8. The apparatus of claim 1, the processor evaluates the channel quality indicator offset value by computing the average of successive interference cancellation gains over multiple virtual antennas.

9. The apparatus of claim 1, the processor evaluates the channel quality indicator offset value by computing the difference between single-user multiple-input multiple-output mode and multi-user multiple-input multiple-output mode when a single virtual antenna is selected.

10. The apparatus of claim 1, the processor quantizes the full value of CQI to a selected number of bits and quantizes the full value of Δ

CQI to a smaller selected number of bits to reduce reporting feedback overhead.

11. The apparatus of claim 1, the processor selects a virtual antenna set by computing a channel quality indicator over a plurality of virtual antenna configurations.

12. A method used in wireless communication system, the method comprising:

evaluating a channel quality indicator (CQI) base layer value (CQI, and a CQI offset value (Δ

CQI) for a selected set of virtual or physical antennas; and

reporting the evaluated CQI, Δ

CQI and the selected virtual or physical antenna set.

13. The method of claim 12, evaluating the channel quality indicator base layer value comprising assuming single-user multiple-input multiple-output operation mode.

14. The method of claim 12, evaluating the channel quality indicator offset value comprising computing successive interference cancellation gains between successively transmitted data layers when multiple virtual antennas are selected.

15. The method of claim 12, evaluating the channel quality indicator (CQI) offset value comprising computing the difference between CQI in single-user multiple-input multiple-output mode and CQI in multi-user multiple-input multiple-output mode when a single virtual antenna is selected.

16. An electronic device configured to execute the method of claim 12.

17. An apparatus that operates in a wireless communication environment, the apparatus comprising:

means for evaluating a channel quality indicator (CQI) base layer value (CQI), and a CQI offset value (Δ

CQI), and selecting a set of virtual or physical antennas;

means for quantizing the full value of CQI to a selected number of bits and quantizing the full value of Δ

CQI to a smaller selected number of bits; and

means for reporting the evaluated CQI, Δ

CQI and the selected virtual or physical antenna set.

18. The apparatus of claim 17, further comprising means for quantizing to a selected number of bits the full values of the channel quality indicator (CQI) base layer value, and the CQI offset value.

19. A machine-readable medium comprising instructions which, when executed by a machine, cause the machine to perform operations including:

evaluating a channel quality indicator (CQI) base layer value (CQI), a CQI offset value (Δ

CQI);

selecting a virtual or physical antenna set; and

reporting CQI, Δ

CQI and the set of virtual or physical antennas.

20. An apparatus operable in a wireless communication system, the apparatus comprising:

a processor, configured to receive a channel quality indicator (CQI) base layer value (CQI), a CQI offset value (Δ

CQI), and a virtual or physical antenna set selection; and

a memory coupled to the processor for storing the received data.

21. The apparatus of claim 20, further comprising a scheduler component that dynamically determines a user device operates in single-user multiple-input multiple-output mode or multi-user multiple-input multiple-output mode.

22. The apparatus of claim 21, further comprising a transmitter that applies a symmetric permutation to multiple data layers in frequency-domain or time-domain prior to sending the data layers over a selected virtual antenna set in the single-user multiple-input multiple-output mode;

the permutation being at least simple cyclic or pseudo-random.

23. The apparatus of claim 21, further comprising a transmitter that applies a symmetric permutation to multiple data layers in frequency-domain or time-domain prior to sending the data layers over a selected virtual antenna set assigned to each user in a plurality of users in the multi-user multiple-input multiple-output mode, but avoids a symmetric permutation across data layers belonging to disparate users in the plurality of users in the MIMO mode, the permutation being at least simple cyclic or pseudo-random.

24. The apparatus of claim 21, the scheduler component includes a processor that executes a scheduling algorithm or an optimization algorithm stored in an algorithm store.

25. A method used in a wireless communication system, the method comprising:

receiving a channel quality indicator (CQI) base layer value (CQI), a CQI offset value (Δ

CQI), and a virtual or physical antenna set selection;

selecting a modulation and coding scheme according to the received base layer value and offset value; and

scheduling a terminal in one of single-user multiple-input multiple-output operation mode or multi-user multiple-input multiple-output operation mode based on the received CQI, Δ

CQI and virtual or physical antenna set selection.

26. The method of claim 25, further comprising sending data to the terminal in the scheduled mode of operation.

27. The method of claim 25, further comprising applying a symmetric permutation to multiple data layers in frequency-domain or time-domain prior to sending the data layers over a selected virtual antenna set in the single-user multiple-input multiple-output mode;

the permutation being at least simple cyclic or pseudo-random.

28. The method of claim 25, further comprising applying a symmetric permutation to multiple data layers in frequency-domain or time-domain prior to sending the data layers over a selected virtual antenna set assigned to each user in a plurality of users in the multi-user multiple-input multiple-output (MIMO) mode, and avoiding the symmetric permutation across data layers that belong to disparate users in the plurality of users in the MIMO mode;

the permutation being at least simple cyclic or pseudo-random.

29. The method of claim 25, further comprising changing the scheduled mode of operation based at least on population of a service cell.

30. An apparatus used in a wireless communication system, comprising:

means for receiving a channel quality indicator (CQI) base layer value (CQI), a CQI offset value (Δ

CQI), and a virtual or physical antenna set selection; and

means for scheduling a terminal in one of single-user multiple-input multiple-output operation mode or multi-user multiple-input multiple-output operation mode based on the received CQI, Δ

CQI and virtual or physical antenna set selection.

31. The apparatus of claim 30, further comprising means for sending data in the scheduled mode of operation.

32. The apparatus of claim 30, further comprising means for applying a symmetric permutation to multiple data layers in frequency-domain or time-domain prior to sending the data layers over a selected virtual antenna set in the single-user multiple-input multiple-output mode;

the permutation being at least simple cyclic or pseudo-random.

33. The apparatus of claim 30, further comprising means for applying a symmetric permutation to multiple data layers in frequency-domain or time-domain prior to sending the data layers over a selected virtual antenna set assigned to each user in a plurality of users in the multi-user multiple-input multiple-output (MIMO) mode, and means for avoiding the symmetric permutation across data layers that belong to disparate users in the plurality of users in the MIMO mode;

the permutation being at least simple cyclic or pseudo-random.

34. A machine-readable medium comprising instructions which, when executed by a machine, cause the machine to perform operations including:

scheduling a wireless device in one of single-user multiple-input multiple-output operation mode or multi-user multiple-input multiple-output operation mode based on received differential channel quality indicators, and virtual or physical antenna set selection; and

optimizing the scheduled resources.