Method and apparatus for interference control in wireless communication systems

• US 20060229089A1
• Filed: 04/07/2005
• Published: 10/12/2006
• Est. Priority Date: 04/07/2005
• Status: Abandoned Application

• Current Assignee: Qualcomm, Inc.
• Original Assignee: Qualcomm, Inc.
• Inventors: Hou, Jilei, Smee, John E., Fan, Mingxi, Tokgoz, Yeliz
• Application Number:
  US11/102,134
• Publication Number:
  US 20060229089A1
• Time in Patent Office: Days
• US Class Current: 455/501
• CPC Class Codes: H04B 17/345 Interference values signal-to-interference ratio [SIR] or carrier-to-interference ratio [CIR] H04B17/336
• CPC Class Codes: H04B 7/0848 Joint weighting
• CPC Class Codes: Y02D 30/70 in wireless communication networks

Abstract

Embodiments disclosed herein relate to providing effective interference control in a wireless communication system. In one embodiment, a method for determining an interference level in a wireless communication system is described, including: determining a rise-over-thermal (RoT) metric based on an RoT received at each receiver antenna of an access network, the RoT relating to a ratio of a total energy to a thermal energy received at each receiver antenna; determining an interference-reduction factor (ρ) in relation to an interference energy reduced from the total energy received at each receiver antenna; and determining an effective rise-over-thermal (RoT^eff) based on the RoT metric and the interference-reduction factor, the RoT^eff relating to the interference level in the wireless communication system. The method may further include comparing the RoT^eff with a threshold and relating the result of the comparison (e.g., the sector loading status) to each access terminal in communication with the access network.

Claims

1. An apparatus adapted for wire communications, comprising:

a processor configured to;

determine a rise-over-thermal (RoT) metric based on a rise-over-thermal received at each receiver antenna of an access network, the rise-over-thermal relating to a ratio of a total energy to a thermal energy received at each receiver antenna;

determine an interference-reduction factor in relation to an interference energy reduced from the total energy received at each receiver antenna; and

determine an effective rise-over-thermal (RoT^eff) based on the rise-over-thermal metric and the interference-reduction factor, the effective rise-over-thermal relating to an interference level in a wireless communication system.

2. The apparatus of claim 1, wherein the processor is further configured to compare the effective rise-over-thermal with a first threshold.

3. The apparatus of claim 2, wherein the processor is further configured to relate a result of the comparison to each access terminal in communication with the access network.

4. The apparatus of claim 3, wherein the relating includes setting a corresponding status for a reverse activity bit (RAB) to be transmitted to each access terminal.

5. The apparatus of claim 2, wherein the processor is further configured to determine a loading status associated with the wireless communication system, based on the result of the comparison.

6. The apparatus of claim 2, wherein the processor is further configured to compare a maximum rise-over-thermal received at a particular receiver antenna of the access network with a second threshold, if the effective rise-over-thermal is less than the first threshold, and to relate a result of the comparison to each access terminal in communication with the access network.

7. The apparatus of claim 6, wherein the relating includes setting a corresponding status for a reverse activity bit to be transmitted to each access terminal.

8. The apparatus of claim 1, wherein the effective rise-over-thermal is proportional to a product of the interference-reduction factor and the rise-over-thermal metric.

9. The apparatus of claim 1, wherein the interference-reduction factor is determined based on a sequence of pre-interference-reduction sample measurements and a sequence of post-interference-reduction sample measurements in accordance with a predetermined scheme.

10. The apparatus of claim 1, wherein the interference energy reduced includes an energy associated with at least one of a pilot channel, a data channel, and an overhead channel transmitted from each access terminal in communication with the access network.

11. The apparatus of claim 1, wherein the access network includes a plurality of receiver antennas and is configured to implement a spatial interference reduction scheme, the processor further configured to determine a signal-to-noise-plus-interference ratio (SINR) associated with each access terminal in communication with the access network.

12. The apparatus of claim 11, wherein the spatial interference reduction scheme includes a minimum-mean-square-error (MMSE) combining technique, the processor further configured to compute a ratio of an uncorrelated-interference SINR, γ

_Io,MMSE, and a post-MMSE SINR, SINR_MMSE, for each access terminal in communication with the access network, the interference-reduction factor being associated with the largest ratio of γ

_Io,MMSE to SINR_MMSE among one or more access terminals in communication with the access network.

13. The apparatus of claim 11, wherein the spatial interference reduction scheme includes a minimum-mean-square-error (MMSE) combining technique and a maximum-rate combining (MRC) technique, the processor further configured to compute a ratio of a signal-to-noise-plus-interference ratio determined by the MRC technique, SINR_MRC, and a signal-to-noise-plus-interference ratio determined by the MMSE technique SINR_MMSE, for each access terminal in communication with the access network, the interference-reduction factor being associated with the largest ratio of SINR_MRC to SINR_MMSE among one or more access terminals in communication with the access network.

14. The apparatus of claim 13, wherein the access network is further configured to implement a temporal interference reduction scheme in conjunction with the spatial interference reduction scheme, the professor further configured to determine the interference-reduction factor based on the largest ratio of SINR_MRC to SINR_MMSE, along with a sequence of pre-interference-reduction sample measurements and a sequence of post-interference-reduction sample measurements in accordance with the temporal interference reduction scheme.

15. A computer readable medium embodying instructions executable by a processor to:

determine a rise-over-thermal metric based on a rise-over-thermal received at each receiver antenna of an access network, the rise-over-thermal relating to a ratio of a total energy to a thermal energy received at each receiver antenna;

determine an interference-reduction factor in relation to an interference energy reduced from the total energy received at each receiver antenna; and

determine an effective rise-over-thermal based on the rise-over-thermal metric and the interference-reduction factor, the effective rise-over-thermal relating to an interference level in a wireless communication system.

16. The computer readable medium of claim 15, further comprising instructions to compare the effective rise-over-thermal with a first threshold.

17. The computer readable medium of claim 16, further comprising instructions to relate a result of the comparison to each access terminal in communication with the access network.

18. The computer readable medium of claim 17, wherein the relating includes setting a corresponding status for a reverse activity bit to be transmitted to each access terminal.

19. The computer readable medium of claim 16, further comprising instructions to determine a loading status associated with the wireless communication system, based on the result of the comparison.

20. The computer readable medium of claim 16, further comprising instructions to compare a maximum rise-over-thermal received at a particular receiver antenna of the access network with a second threshold, if the effective rise-over-thermal is less than the first threshold, and to relate a result of the comparison to each access terminal in communication with the access network.

21. The computer readable medium of claim 15, wherein the interference-reduction factor is determined based on a sequence of pre-interference-reduction sample measurements and a sequence of post-interference-reduction sample measurements in accordance with a predetermined scheme.

22. The computer readable medium of claim 15, wherein the interference energy reduced includes an energy associated with at least one of a pilot channel, a data channel, and an overhead channel transmitted from each access terminal in communication with the access network.

23. The computer readable medium of claim 15, wherein the access network includes a plurality of receiver antennas and is configured to implement a spatial interference reduction scheme, the computer readable medium further comprises instructions to determine a signal-to-noise-plus-interference ratio associated with each access terminal in communication with the access network.

24. The computer readable medium of claim 23, wherein the access network is further configured to implement a temporal interference reduction scheme in conjunction with the spatial interference reduction scheme, and wherein the computer readable medium further comprises instructions to determine the interference-reduction factor based in part on a sequence of pre-interference-reduction sample measurements and a sequence of post-interference-reduction sample measurements in accordance with the temporal interference reduction scheme.

25. An access network in a wireless communication system, comprising:

at least one receiver antenna; and

a processor configured to;

determine a rise-over-thermal metric based on a rise-over-thermal received at each receiver antenna, the rise-over-thermal relating to a ratio of a total energy to a thermal energy received at each receiver antenna;

determine an interference-reduction factor in relation to an interference energy reduced from the total energy received at each receiver antenna; and

determine an effective rise-over-thermal based on the rise-over-thermal metric and the interference-reduction factor, the effective rise-over-thermal relating to an interference level in the wireless communication system.

26. The access network of claim 25, wherein the processor is further configured to compare the effective rise-over-thermal with a first threshold and relate a result of the comparison to each access terminal in communication with the access network.

27. The access network of claim 26, wherein the relating includes setting a corresponding status for a reverse activity bit to be transmitted to each access terminal.

28. The access network of claim 26, wherein the processor is further configured to determine a loading status associated with the wireless communication system, based on the result of the comparison.

29. The access network of claim 26, wherein the processor is further configured to compare a maximum rise-over-thermal received at a particular receiver antenna of the access network with a second threshold, if the effective rise-over-thermal is less than the first threshold, and to relate a result of the comparison to each access terminal in communication with the access network.

30. The access network of claim 25, wherein the interference-reduction factor is determined based on a sequence of pre-interference-reduction sample measurements and a sequence of post-interference-reduction sample measurements in accordance with a predetermined scheme.

31. The access network of claim 25, wherein the interference energy reduced includes an energy associated with at least one of a pilot channel, a data channel, and an overhead channel transmitted from each access terminal in communication with the access network.

32. The access network of claim 25, wherein the access network includes a plurality of receiver antennas and is configured to implement a spatial interference reduction scheme, the processor further configured to determine a signal-to-noise-plus-interference ratio associated with each access terminal in communication with the access network.

33. The access network of claim 32, wherein the access network is further configured to implement a temporal interference reduction scheme in conjunction with the spatial interference reduction scheme, the processor further configured to determine the interference-reduction factor based in part on a sequence of pre-interference-reduction sample measurements and a sequence of post-interference-reduction sample measurements in accordance with the temporal interference reduction scheme.

34. The access network of claim 25, further comprising a memory embodying instructions executable by the processor.

35. The access network of claim 25, further comprising an interference-reduction unit, in communication with the processor.

36. The access network of claim 25, further comprising a Rake receiver in communication with the at least one receiver antenna and the processor.

42. The apparatus of claim 36, wherein the wireless communication system includes an access network, each receiver antenna being in communication with the access network.

37. An apparatus adapted for wireless communications, comprising:

means for determining a rise-over-thermal metric based on a rise-over-thermal received at each receiver antenna in a wireless communication system, the rise-over-thermal relating to a ratio of a total energy to a thermal energy received at each receiver antenna;

means for determining an interference-reduction factor in relation to an interference energy reduced from the total energy received at each receiver antenna; and

means for determining an effective rise-over-thermal based on the rise-over-thermal metric and the interference-reduction factor, the effective rise-over-thermal relating to an interference level in the wireless communication system.

38. The apparatus of claim 37, further comprising means for comparing the effective rise-over-thermal with a first threshold.

39. The apparatus of claim 38, further comprising means for relating a result of the comparison to each access terminal in the wireless communication system.

40. The apparatus of claim 39, further comprising means for setting a status for a reverse activity bit to be transmitted to each access terminal, the status being associated with the result of the comparison.

41. The apparatus of claim 38, wherein the means for comparing further determines a loading status associated with the wireless communication system, based on a result of the comparison.

43. A method for wireless communications, comprising:

determining a rise-over-thermal metric based on a rise-over-thermal received at each receiver antenna of an access network, the rise-over-thermal relating to a ratio of a total energy to a thermal energy received at each receiver antenna;

determining an interference-reduction factor in relation to an interference energy reduced from the total energy received at each receiver antenna; and

determining an effective rise-over-thermal based on the rise-over-thermal metric and the interference-reduction factor, the effective rise-over-thermal relating to an interference level in a wireless communication system.

44. The method of claim 43, further comprising comparing the effective rise-over-thermal with a first threshold and relating a result of the comparison to each access terminal in communication with the access network.

45. The method of claim 44 wherein the relating includes setting a corresponding status for a reverse activity bit to be transmitted to each access terminal.

46. The method of claim 44, further comprising comparing a maximum rise-over-thermal received at a particular receiver antenna of the access network with a second threshold, if the effective rise-over-thermal is less than the first threshold, and relating a result of the comparison to each access terminal in communication with the access network.