HANDOVER MECHANISM THAT EXPLOITS UPLINK CHANNEL QUALITY OF A TARGET CELL

• US 20090028112A1
• Filed: 03/17/2008
• Published: 01/29/2009
• Est. Priority Date: 03/19/2007
• Status: Active Grant

• Current Assignee: Qualcomm, Inc.
• Original Assignee: Qualcomm, Inc.
• Inventors: Damnjanovic, Aleksandar, Malladi, Durga Prasad, Attar, Rashid Ahmed Akbar, Grilli, Francesco
• Granted Patent: US 8,891,489 B2
• Time in Patent Office: Days
• US Class Current: 370/332
• CPC Class Codes: H04W 36/008375 based on historical data
• CPC Class Codes: H04W 36/30 by measured or perceived connection quality data
• CPC Class Codes: H04W 36/302 due to low signal strength

Abstract

System(s) and method(s) are provided for handover of a mobile terminal in a wireless communication system. Handoff resolution relies on both a downlink channel quality indication between a serving base station and the mobile terminal,, and uplink channel quality indications amongst the terminal and a measurement set of target base stations. To generate UL channel quality indicators, the mobile station conveys a narrowband or broadband, sounding reference signal, and serving and target base stations measure UL and DL performance metrics (e.g., RSRP, RSSI, or RSOT). In backward handover, UL channel state information from target cells is received at the serving base station through backhaul communication, and handoff is resolved based on both UL and DL quality reports. In forward handover, the set of UL quality reports are conveyed to the mobile station to determine a target cell for handoff.

Claims

1. A method for facilitating handover in wireless system, the method comprising:

receiving a set of uplink (UL) channel quality metrics through a backhaul communication interface;

generating an UL channel quality metric;

receiving a set of downlink channel conditions;

resolving handoff based at least in part on the received UL and DL channel quality indications.

2. The method of claim 1, further comprising conveying the set of UL channel quality metrics via a wireless link.

3. The method of claim 1, further comprising conveying the generated UL channel quality metric via a backhaul communication interface.

4. The method claim 3, further comprising conveying the generated UL channel quality metric when the metric is above a threshold.

5. The method of claim 1, further comprising conveying a set of communication indicators through a backhaul communication interface.

6. The method of claim 5, wherein the set of communication indicators includes at least one of a system bandwidth, a pilot sequence, a channel quality indicator directive, a downlink timing information, or a cell specific UL timing offset relative to a DL.

7. The method of claim 3, generating an UL channel quality metric further comprising measuring a UL sounding reference signal.

8. The method of claim 7, wherein measuring a UL SRS includes performing a measurement periodically.

9. The method of claim 7, wherein measuring a UL SRS includes effecting a measurement over a set of time-frequency resources.

10. The method of claim 9, wherein measuring a UL SRS includes performing at least one of a time-averaged measurement or a frequency-averaged measurement.

11. The method of claim 7 wherein measuring a UL SRS includes conducting an event-triggered measurement.

12. The method of claim 7, wherein measuring an UL sounding reference signal (SRS) includes at least one of measuring a SRS reference power, SRS strength indicator or a sounding reference signal over thermal noise.

13. An electronic device to execute the method of claim 1.

14. A wireless device, comprising:

a processor configured to receive a set of uplink channel quality reports through a point-to-point backbone network communication;

to receive a set of downlink channel condition indicators over a wireless link;

to establish a handover based at least in part on the received UL channel quality reports and the DL channel condition indicators; and

a memory coupled to the processor.

15. The wireless device of claim 14, the processor further configured to generate a set of UL channel quality metrics.

16. The wireless device of claim 15, wherein to generate a set of UL channel quality metrics includes to measure at least one of a sounding reference signal (SRS) reference power, a SRS strength indicator, or a SRS over thermal noise.

17. The wireless device of claim 16, wherein a measurement of at least one of a SRS reference power, a SRS strength indicator, or a SRS over thermal noise further includes a measurement that is conducted periodically.

18. The wireless device of claim 16, wherein a measurement of at least one of a SRS reference power, a SRS strength indicator, or a SRS over thermal noise further includes a measurement that is conducted on a set of time-frequency resources.

19. The wireless device of claim 16, wherein a measurement of at least one of a SRS reference power, a SRS strength indicator, or a SRS over thermal noise further includes at least one of a time-averaged measurement or a frequency-averaged measurement.

20. The wireless device of claim 16, wherein a measurement of at least one of a SRS reference power, a SRS strength indicator, or a SRS over thermal noise further includes an event-triggered measurement

21. The wireless device of claim 15, the processor further configured to convey a set of UL channel quality metrics via a wireless link.

22. The wireless device of claim 15, the processor further configured to convey at least one of the UL channel quality metrics in the set of UL channel quality metrics when the at least one metric is above a metric threshold.

23. The wireless device of claim 14, the processor further configured to convey a set of communication indicators through a backhaul communication interface.

24. The wireless device of claim 23, wherein the set of communication indicators includes at least one of a system bandwidth, a pilot sequence, a channel quality indicator directive, a downlink timing information, or a cell specific UL timing offset relative to a DL.

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

means for receiving a set of uplink (UL) channel quality metrics through a backhaul communication interface;

means for generating an UL channel quality indication;

means for receiving a set of downlink (DL) channel conditions; and

means for resolving handoff based at least in part on the received UL channel quality metrics and the set of DL channel quality indications.

26. The apparatus of claim 25, further comprising means for generating an UL channel quality indication including means for measuring at least one of a sounding reference signal (SRS) reference power, SRS strength indicator, or SRS over thermal noise.

27. The apparatus of claim 25, further comprising means for conveying the set of UL channel quality metrics over a wireless link.

28. The apparatus of claim 27, further comprising means for conveying at least one of the UL channel quality metrics in the set of UL channel quality metrics over a wireless link when the at least one metric is above a metric threshold.

29. A computer program product comprising a computer-readable medium including:

code for causing at least one computer to receive a set of uplink (UL) channel quality reports through a backhaul communication interface;

code for causing at least one computer to generate an UL channel quality metric;

receiving a set of downlink (DL) channel metrics;

establishing a handover based at least in part on the set of UL channel quality reports and the set of DL channel metrics.

30. The computer-readable medium of claim 29, further including code for causing the at least one computer to convey a set of UL channel quality reports over a wireless link.

31. The computer-readable medium of claim 29, wherein code for causing at least one computer to generate an UL channel quality metric includes code for causing the at least one computer to determine at least one of a SRS reference power, a SRS strength indicator, or a sounding reference signal over thermal noise.

32. A method for facilitating handover in wireless system, the method comprising:

receiving an uplink (UL) channel quality metrics;

retaining a handover fitness score associated with a source of the received UL channel quality metrics;

establishing a handoff based at least in part on the received UL channel metrics and the retained channel quality metrics.

33. The method of claim 32, further comprising determining a measurement set, wherein the measurement set comprises a set of base stations, the set of base stations are targets for handoff.

34. The method of claim 33, further comprising conveying a sounding reference signal to a base station in the set of base stations when a handover fitness score associated with the base station is above a threshold.

35. The method of claim 34, further comprising excluding at least one base station form the set of base stations when a channel quality metric fails to be received from the at least one base station.

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

a processor configured to receive a set of uplink (UL) channel qualify indicators;

to convey a sounding reference signal;

to generate a set of downlink channel condition reports;

to resolve a handover based at least in part on the received set of UL channel metrics; and

a memory coupled to the processor.

37. The apparatus of claim 36, the processor further configured to retain a handover fitness score associated with at least one source of the received set UL channel quality indicators;

38. The apparatus of claim 37, processor further configured to resolve handover based at least in part on the received set of UL channel metrics and the handover fitness score,

39. The apparatus of claim 36, the processor further configured to determine a measurement set, wherein the measurement set comprises a set of base stations, the set of base stations are targets for handoff.

40. The apparatus of claim 36, the processor further configured to convey a sounding reference signal to a base station in the set of base stations when a handover fitness score associated with the base station is above a threshold.

41. The apparatus of claim 40, the processor further configured to exclude at least one base station form the set of base stations when a channel quality metric fails to he received from the at least one base station.

42. The apparatus of claim 40, wherein the sounding reference signal is a narrowband signal.

43. The apparatus of claim 40, wherein the sounding reference signal is a broadband signal.

44. A wireless device, comprising:

means for receiving an uplink (UL) channel metric;

means for determining a set of downlink (DL) channel conditions;

means for retaining a handover fitness score associated with a source of the received DL channel metric;

means for establishing a handoff based at least in part on the received UL channel metric; and

means for resolving a handover based at least in part on the received UL channel metric and the retained handover fitness score.

45. A computer program product comprising a computer readable medium including:

code for causing at least one computer to receive an uplink (UL) channel metric;

code for causing the least one computer to retain a handover fitness score associated with a source of the received UL channel metric;

code for causing the at least one computer to determine a handoff based at least in part on the received UL channel metric; and

code for causing the at least one computer to resolve a handover based at least in part on the received UL channel metric and the retained handover fitness score.