Method and apparatus for mitigating data loss during autonomous system information reading

• US 9,179,395 B2
• Filed: 01/17/2011
• Issued: 11/03/2015
• Est. Priority Date: 01/18/2010
• Status: Active Grant

• Current Assignee: Qualcomm, Inc.
• Original Assignee: Qualcomm, Inc.
• Inventors: Ji, Tingfang, Gaal, Peter, Fong, Gene, Bhattad, Kapil, Wei, Yongbin
• Primary Examiner(s): Phillips, Hassan
• Assistant Examiner(s): JONES, PRENELL P
• Application Number:
  US13/007,950
• Publication Number:
  US 20120020310A1
• Time in Patent Office: 1,751 Days
• US Class Current: 1/1
• CPC Class Codes: H04L 1/1845 Combining techniques, e.g. code combining
• CPC Class Codes: H04L 1/1867 Arrangements specially adapted for the transmitter end
• CPC Class Codes: H04W 36/0016 Hand-off preparation specially adapted for end-to-end data sessions
• CPC Class Codes: H04W 36/0061 of neighbour cell information
• CPC Class Codes: H04W 48/16 Discovering, processing access restriction or access information
• CPC Class Codes: H04W 56/001 Synchronization between nodes

Abstract

Techniques for mitigating data loss during autonomous system information (SI) reading by a user equipment (UE) are described. For autonomous SI reading, the UE may autonomously determine when to read system information from neighbor cells and may not inform a serving cell. In one design, the UE may autonomously select a SI reading gap for reading system information from a neighbor cell. During the SI reading gap, the UE may suspend reception of downlink transmission from the serving cell, receive system information from the neighbor cell, and maintain capability to transmit on the uplink to the serving cell. In one design, the serving cell may determine SI reading gaps autonomously selected by the UE for reading system information from neighbor cells. The serving cell may communicate with the UE by accounting for the SI reading gaps of the UE, e.g., may suspend communication with the UE during the SI reading gaps.

Claims

1. A method for wireless communication, comprising:

suspending reception of downlink transmission from a serving cell by a user equipment (UE) during a system information (SI) reading gap;

receiving system information from a neighbor cell by the UE during the SI reading gap;

skipping updating at least one tracking loop for an uplink based on the serving cell during the SI reading gap;

updating at least one tracking loop for a downlink based on the neighbor cell during the SI reading gap; and

maintaining capability to transmit on the uplink to the serving cell by the UE during the SI reading gap such that the UE has the capability to transmit on the uplink to the serving cell and receive the system information on the downlink from the neighbor cell during the SI reading gap.

2. The method of claim 1, further comprising:

updating the at least one tracking loop for the uplink based on the serving cell when the UE is receiving downlink transmission from the serving cell.

3. The method of claim 1, further comprising:

sending uplink transmission to the serving cell, with the at least one tracking loop for the uplink being frozen, during all or part of the SI reading gap.

4. The method of claim 1, wherein the at least one tracking loop for the uplink comprises at least a frequency tracking loop, a time tracking loop, or a combination thereof.

5. The method of claim 1, further comprising:

updating the at least one tracking loop for the downlink based on the serving cell when the UE is receiving downlink transmission from the serving cell.

6. The method of claim 1, further comprising:

sending tune-away information to the serving cell, the tune-away information being indicative of SI reading gaps during which the UE intends to receive system information from at least one neighbor cell.

7. The method of claim 1, further comprising:

sending timing information for at least one neighbor cell to the serving cell, the timing information being indicative of timing of the at least one neighbor cell from which the UE intends to receive system information.

8. The method of claim 1, wherein the serving cell and the neighbor cell operate on a same frequency, and wherein the UE performs intra-frequency SI reading during the SI reading gap.

9. The method of claim 1, wherein the serving cell and the neighbor cell operate on different frequencies, and wherein the UE performs inter-frequency SI reading during the SI reading gap.

10. An apparatus for wireless communication, comprising:

means for suspending reception of downlink transmission from a serving cell by a user equipment (UE) during a system information (SI) reading gap;

means for receiving system information from a neighbor cell by the UE during the SI reading gap;

means for skipping updating at least one tracking loop for an uplink based on the serving cell during the SI reading gap;

means for updating at least one tracking loop for a downlink based on the neighbor cell during the SI reading gap; and

means for maintaining capability to transmit on the uplink to the serving cell by the UE during the SI reading gap such that the UE has the capability to transmit on the uplink to the serving cell and receive the system information on the downlink from the neighbor cell during the SI reading gap.

11. The apparatus of claim 10, further comprising:

means for updating the at least one tracking loop for the uplink based on the serving cell when the UE is receiving downlink transmission from the serving cell.

12. The apparatus of claim 10, further comprising:

means for updating the at least one tracking loop for the downlink based on the serving cell when the UE is receiving downlink transmission from the serving cell.

13. The apparatus of claim 10, further comprising:

means for sending tune-away information to the serving cell, the tune-away information being indicative of SI reading gaps during which the UE intends to receive system information from at least one neighbor cell.

14. The apparatus of claim 10, further comprising:

means for sending timing information for at least one neighbor cell to the serving cell, the timing information being indicative of timing of the at least one neighbor cell from which the UE intends to receive system information.

15. An apparatus for wireless communication, comprising:

a memory unit; and

at least one processor coupled to the memory unit, the at least one processor being configured;

to suspend reception of downlink transmission from a serving cell by a user equipment (UE) during a system information (SI) reading gap,

to receive system information from a neighbor cell by the UE during the SI reading gap,

to skip updating at least one tracking loop for an uplink based on the serving cell during the SI reading gap,

to update at least one tracking loop for a downlink based on the neighbor cell during the SI reading gap, and

to maintain capability to transmit on the uplink to the serving cell by the UE during the SI reading gap such that the UE has the capability to transmit on the uplink to the serving cell and receive the system information on the downlink from the neighbor cell during the SI reading gap.

16. The apparatus of claim 15, wherein the at least one processor is further configured to update the at least one tracking loop for the uplink based on the serving cell when the UE is receiving downlink transmission from the serving cell.

17. The apparatus of claim 15, wherein the at least one processor is further configured to update the at least one tracking loop for the downlink based on the serving cell when the UE is receiving downlink transmission from the serving cell.

18. The apparatus of claim 15, wherein the at least one processor is further configured to send tune-away information to the serving cell, the tune-away information being indicative of SI reading gaps during which the UE intends to receive system information from at least one neighbor cell.

19. The apparatus of claim 15, wherein the at least one processor is further configured to send timing information for at least one neighbor cell to the serving cell, the timing information being indicative of timing of the at least one neighbor cell from which the UE intends to receive system information.

20. A computer program product, comprising:

a non-transitory computer-readable medium comprising;

code for causing at least one computer to suspend reception of downlink transmission from a serving cell by a user equipment (UE) during a system information (SI) reading gap,

code for causing the at least one computer to receive system information from a neighbor cell by the UE during the SI reading gap,

code for causing the at least one computer to skip updating at least one tracking loop for an uplink based on the serving cell during the SI reading gap;

code for causing the at least one computer to update at least one tracking loop for a downlink based on the neighbor cell during the SI reading gap; and

code for causing the at least one computer to maintain capability to transmit on the uplink to the serving cell by the UE during the SI reading gap such that the UE has the capability to transmit on the uplink to the serving cell and receive the system information on the downlink from the neighbor cell during the SI reading gap.

21. A method for wireless communication, comprising:

estimating, at a serving cell, system information (SI) reading gaps for a user equipment (UE) to read system information from at least one neighbor cell when the serving cell is unaware of when the UE will read the SI from the at least one neighbor cell based on the SI reading gaps autonomously selected by the UE; and

communicating with the UE by the serving cell based at least in part on the estimated SI reading gaps.

22. The method of claim 21, wherein the estimating the SI reading gaps comprises

receiving tune-away information indicative of the autonomously selected SI reading gaps, and

estimating the SI reading gaps based on the tune-away information.

23. The method of claim 21, wherein the estimating the SI reading gaps comprises

obtaining timing information for the at least one neighbor cell, and

estimating the SI reading gaps based on the timing information for the at least one neighbor cell.

24. The method of claim 21, wherein the estimating the SI reading gaps comprises

detecting missing transmissions of acknowledgement (ACK) information from the UE, and

estimating the SI reading gaps based on the missing transmissions of ACK information from the UE.

25. The method of claim 21, wherein the estimating the SI reading gaps comprises

detecting missing transmissions of data on uplink from the UE, and

estimating the SI reading gaps based on the missing transmissions of data from the UE.

26. The method of claim 21, wherein the estimating the SI reading gaps comprises

detecting missing transmissions of sounding reference signal (SRS) on uplink from the UE, and

estimating the SI reading gaps based on the missing transmissions of SRS from the UE.

27. The method of claim 21, wherein the estimating the SI reading gaps comprises estimating the SI reading gaps based on statistics for data transmission with hybrid automatic repeat request (HARQ) for the UE, the statistics being related to missing acknowledgement (ACK) information, or number of transmissions of data for correct decoding, or both.

28. The method of claim 21, wherein the communicating with the UE comprises extending a target termination for data transmission with hybrid automatic repeat request (HARQ) for the UE due to the estimated SI reading gaps.

29. The method of claim 21, further comprising:

identifying tune-away subframes based on the estimated SI reading gaps, the UE tuning away from the serving cell during the tune-away subframes to read the system information from the at least one neighbor cell.

30. The method of claim 29, wherein the communicating with the UE comprises

suspending communication with the UE on downlink in the tune-away subframes, and

continuing communication with the UE on uplink in the tune-away subframes.

31. The method of claim 29, wherein the communicating with the UE comprises sending control information to the UE in subframes other than the tune-away subframes.

32. The method of claim 29, wherein the communicating with the UE comprises scheduling the UE for new transmission of data on uplink in subframes other than the tune-away subframes.

33. The method of claim 29, wherein the communicating with the UE comprises

receiving a transmission of a transport block from the UE in a first subframe,

sending a fake acknowledgement (ACK) for the transport block to the UE in a second subframe to suspend transmission of the transport block from the UE in a third subframe, the third subframe being one of the tune-away subframes, and

scheduling the UE for transmission of the transport block in a fourth subframe after the third subframe.

34. The method of claim 29, wherein the communicating with the UE comprises

combining multiple transmissions of a transport block received from the UE in multiple subframes other than the tune-away subframes,

skipping combining at least one transmission of the transport block received from the UE in at least one of the tune-away subframes, and

decoding the multiple transmissions of the transport block, after combining, to recover the transport block from the UE.

35. The method of claim 21, wherein the communicating with the UE comprises

identifying a subframe in which the UE communicates with the serving cell during only a portion of the subframe, and

selecting a modulation and coding scheme for data transmission in the identified subframe to account for the UE communicating with the serving cell during only a portion of the subframe.

36. The method of claim 35, further comprising:

estimating an amount of time in which the UE communicates with the serving cell in the identified subframe based on whether the UE performs inter-frequency or intra-frequency system information reading.

37. The method of claim 21, wherein the communicating with the UE comprises

sending a transmission of a transport block to the UE,

detecting missing acknowledgement (ACK) information for the transport block from the UE,

determining the missing ACK information to likely be an ACK that is not sent by the UE due to the UE reading system information from a neighbor cell, and

sending another transmission of the transport block to the UE to receive ACK information for the transport block.

38. The method of claim 21, wherein the communicating with the UE comprises

sending a downlink grant and a transmission of a transport block to the UE,

detecting missing acknowledgement (ACK) information for the transport block from the UE,

determining the missing ACK information to likely be a negative acknowledgement (NACK) that is not sent by the UE due to the UE missing the downlink grant when reading system information from a neighbor cell, and

sending another transmission of the transport block to the UE.

39. An apparatus for wireless communication, comprising:

means for estimating, at a serving cell, system information (SI) reading gaps for a user equipment (UE) to read system information from at least one neighbor cell when the serving cell is unaware of when the UE will read the SI from the at least one neighbor cell based on the SI reading gaps autonomously selected by the UE; and

means for communicating with the UE by the serving cell by accounting for the estimated SI reading gaps.

40. The apparatus of claim 39, wherein the means for estimating the SI reading gaps comprises

means for receiving tune-away information indicative of the autonomously selected SI reading gaps, and

means for estimating the SI reading gaps based on the tune-away information.

41. The apparatus of claim 39, wherein the means for estimating the SI reading gaps comprises

means for obtaining timing information for the at least one neighbor cell, and

means for estimating the SI reading gaps based on the timing information for the at least one neighbor cell.

42. The apparatus of claim 39, wherein the means for estimating the SI reading gaps comprises

means for estimating the SI reading gaps based on missing transmissions of acknowledgement (ACK) information from the UE, or missing transmissions of data from the UE, or missing transmissions of a sounding reference signal (SRS) from the UE, or statistics for data transmission with hybrid automatic repeat request (HARQ) for the UE, or number of transmissions of data for correct decoding, or a combination thereof.

43. The apparatus of claim 39, wherein the means for communicating with the UE comprises

means for identifying tune-away subframes based on the estimated SI reading gaps, the UE tuning away from the serving cell during the tune-away subframes to read the system information from the at least one neighbor cell,

means for suspending communication with the UE on downlink in the tune-away subframes, and

means for continuing communication with the UE on uplink in the tune-away subframes.

44. The apparatus of claim 39, wherein the means for communicating with the UE comprises

means for combining multiple transmissions of a transport block received from the UE in multiple subframes other than the tune-away subframes,

means for skipping combining at least one transmission of the transport block received from the UE in at least one of the tune-away subframes, and

means for decoding the multiple transmissions of the transport block, after combining, to recover the transport block from the UE.

45. A serving cell configured for wireless communication, comprising:

a memory unit; and

at least one processor coupled to the memory unit, the at least one processor being configured;

to estimate system information (SI) reading gaps for a user equipment (UE) to read system information from at least one neighbor cell when the serving cell is unaware of when the UE will read the SI from the at least one neighbor cell based on the SI reading gaps autonomously selected by the UE, and

to communicate with the UE based at least in part on the estimated SI reading gaps.

46. A computer program product, comprising:

a non-transitory computer-readable medium comprising;

code for causing at least one computer to estimate, at a serving cell, system information (SI) reading gaps for a user equipment (UE) to read system information from at least one neighbor cell when the serving cell is unaware of when the UE will read the SI from the at least one neighbor cell based on the SI reading gaps autonomously selected by the UE, and

code for causing the at least one computer to communicate with the UE by the serving cell by accounting for the estimated SI reading gaps.