METHOD OF VARIABLE RATE SINGLE USER AND MULTI USER MIMO FEEDBACK FOR MOBILE COMMUNICATIONS SYSTEM

• US 20130034000A1
• Filed: 01/11/2011
• Published: 02/07/2013
• Est. Priority Date: 01/12/2010
• Status: Abandoned Application

• Current Assignee: ZTE Corporation
• Original Assignee: ZTE Corporation
• Inventors: Huo, David, Li, Shupeng, Yuan, Yifel
• Application Number:
  US13/521,960
• Publication Number:
  US 20130034000A1
• Time in Patent Office: Days
• US Class Current: 370/252
• CPC Class Codes: H04B 7/0417 Feedback systems
• CPC Class Codes: H04B 7/0452 Multi-user MIMO systems
• CPC Class Codes: H04B 7/0456 Selection of precoding matrices or codebooks, e.g. using matrices antenna weighting
• CPC Class Codes: H04L 25/0204 of multiple channels
• CPC Class Codes: H04L 25/03343 Arrangements at the transmitter end
• CPC Class Codes: H04L 5/0007 the frequencies being orthogonal, e.g. OFDM(A), DMT
• CPC Class Codes: H04W 24/08 Testing, supervising or monitoring using real traffic
• CPC Class Codes: H04W 72/0466 the resource being a scrambling code

Abstract

A spatial channel state information (CSI) feedback technique is incorporated into multiple-input multiple-output mobile communications technologies. User equipment (UE) channel conditions are measured and, based on the measurements, codebook subsets are selected to which indices are assigned and fed back to a base station.

Claims

1. A method to generate feedback in a multiple-input multiple-output (MIMO) system which comprises:

performing at least one measurement of a channel condition;

selecting a subset of a codebook based on the at least one measurement, the subset comprising a plurality of codewords and a plurality of indices;

selecting one of the plurality of codewords based on a certain criterion and assigning one of the plurality of indices to the one of the plurality of codewords; and

transmitting a feedback signal comprising the one of the plurality of indices.

2. The method of claim 1, wherein the codebook is predetermined.

3. The method of claim 1, further comprising dividing a cell into a plurality of feedback rate regions, wherein each of the plurality of feedback rate regions uses a subset of a codebook having a different characterization based on average radio channel conditions.

4. The method of claim 1, further comprising dividing a cell area into a plurality of feedback rate regions according to long term radio channel conditions.

5. The method of claim 4, wherein the long term radio channel conditions are determined by mobile radio channel measurement reporting.

6. The method of claim 1, further comprising determining an indication of a feedback rate region, wherein the determining is by predefined radio channel thresholds known at the mobile station and by transmission of certain messages from a base station.

7. The method of claim 1, further comprising partitioning a plurality of codewords into multiple sub-codebooks, each sub-codebook corresponding to one of a plurality of feedback regions.

8. The method of claim 7, wherein each sub-codebook has a different feedback granularity.

9. The method of claim 1, wherein the one of the plurality of indices is assigned so a distance between a quantized composite spatial CSI and a floating-point composite spatial CSI is minimized.

10. A method to generate feedback in a multiple-input multiple-output (MIMO) system which comprises:

measuring, at a UE, a radio channel condition, resulting in a channel condition measurement;

reporting the channel condition measurement to a base station; and

deciding, by one of the UE and the base station, a feedback rate region classification for the UE based on the channel condition measurement.

11. The method of claim 10, wherein the deciding is by the base station;

and further comprising conveying the feedback rate region classification for the UE to the UE through a downlink signaling form.

12. The method of claim 11, further comprising:

measuring, by the UE, an instantaneous radio channel; and

choosing codewords from a subset of a codebook corresponding to the feedback rate region classification.

13. The method of claim 12, further comprising choosing codewords from a subset of a codebook corresponding to the feedback rate region classification based on one of (i) a minimal distance of a codeword and a channel vector, and (ii) a maximal capacity criterion.

14. The method of claim 12, further comprising feeding back the codewords from the UE to the base station.

15. The method of claim 14, further comprising calculating precoding matrices by the base station.

16. The method of claim 10, wherein the deciding is by the UE and is further based on a predefined threshold.

17. The method of claim 16, wherein the predefined threshold is known to both the base station and the UE.

18. The method of claim 16, further comprising choosing codewords from a subset of a codebook corresponding to the feedback rate region classification based on one of (i) a minimal distance of a codeword and a channel vector, and (ii) a maximal capacity criterion.

19. The method of claim 18, further comprising feeding back the codewords from the UE to the base station.

20. The method of claim 19, further comprising calculating precoding matrices by the base station.

21. A system to generate feedback in a multiple-input multiple-output (MIMO) system which comprises:

means for performing at least one measurement of a channel condition;

means for selecting a subset of a codebook based on the at least one measurement, the subset comprising a plurality of codewords and a plurality of indices;

means for selecting one of the plurality of codewords based on a certain criterion and assigning one of the plurality of indices to the one of the plurality of codewords; and

means for transmitting a feedback signal comprising the one of the plurality of indices.

22. The system of claim 21, wherein the codebook is predetermined.

23. The system of claim 21, further comprising means for dividing a cell into a plurality of feedback rate regions, wherein each of the plurality of feedback rate regions uses a subset of a codebook having a different characterization based on average radio channel conditions.

24. The system of claim 21, further comprising means for dividing a cell area into a plurality of feedback rate regions according to long term radio channel conditions.

25. The system of claim 24, wherein the long term radio channel conditions are determined by mobile radio channel measurement reporting.

26. The system of claim 21, further comprising means for determining an indication of a feedback rate region, wherein the determining is by predefined radio channel thresholds known at the mobile station and by transmission of certain messages from a base station.

27. The system of claim 21, further comprising means for partitioning a plurality of codewords into multiple sub-codebooks, each sub-codebook corresponding to one of a plurality of feedback regions.

28. The system of claim 27, wherein each sub-codebook has a different feedback granularity.

29. The system of claim 21, wherein the one of the plurality of indices is assigned so a distance between a quantized composite spatial CSI and a floating-point composite spatial CSI is minimized.

30. An apparatus to generate feedback in a multiple-input multiple-output (MIMO) system comprising

a UE configured to (i) measure a radio channel condition, resulting in a channel condition measurement, and (ii) report the channel condition measurement to a base station;

and

one of the UE and the base station, configured to decide a feedback rate region classification for the UE based on the channel condition measurement.

31. The apparatus of claim 30, wherein the base station is further configured to convey the feedback rate region classification for the UE to the UE through a downlink signaling form.

32. The apparatus of claim 31, wherein the UE is further configured to (i) measure an instantaneous radio channel, and (ii) choose codewords from a subset of a codebook corresponding to the feedback rate region classification.

33. The apparatus of claim 32, wherein the UE is further configured to choose codewords, from a subset of a codebook corresponding to the feedback rate region classification, based on one of (i) a minimal distance of a codeword and a channel vector, and (ii) a maximal capacity criterion.

34. The apparatus of claim 32, wherein the UE is further configured to feed back the codewords to the base station.

35. The apparatus of claim 34, wherein the base station is further configured to calculate precoding matrices.

36. The apparatus of claim 30, wherein the UE is further configured to decide the feedback rate region classification for the UE further based on a predefined threshold.

37. The apparatus of claim 36, wherein the predefined threshold is known to both the base station and the UE.

38. The apparatus of claim 36, wherein the UE is further configured to choose codewords, from a subset of a codebook corresponding to the feedback rate region classification, based on one of (i) a minimal distance of a codeword and a channel vector, and (ii) a maximal capacity criterion.

39. The apparatus of claim 38, wherein the UE is further configured to feed back the codewords to the base station.

40. The apparatus of claim 39, where in the base station is further configured to calculate precoding matrices.