PHYSICAL RANDOM ACCESS CHANNEL (PRACH) TRANSMISSION IN MULTICARRIER OPERATION

• US 20100067470A1
• Filed: 09/10/2009
• Published: 03/18/2010
• Est. Priority Date: 09/12/2008
• Status: Active Grant

• Current Assignee: Qualcomm, Inc.
• Original Assignee: Qualcomm, Inc.
• Inventors: Ho, Sai Yiu Duncan, Montojo, Juan, Chen, Wanshi, Gaal, Peter, Damnjanovic, Jelena M.
• Granted Patent: US 8,526,374 B2
• Time in Patent Office: Days
• US Class Current: 370/329
• CPC Class Codes: H04L 5/0048 Allocation of pilot signals, i.e. of signals known to the receiver
• CPC Class Codes: H04L 5/0053 Allocation of signaling, i.e. of overhead other than pilot signals
• CPC Class Codes: H04L 5/0094 Indication of how sub-channels of the path are allocated
• CPC Class Codes: H04W 72/0453 Resources in frequency domain, e.g. a carrier in FDMA
• CPC Class Codes: H04W 74/0866 using a dedicated channel for access

Abstract

Systems and methodologies are described that facilitate selecting an uplink carrier for random access within a wireless environment having multiple carriers. Selection of an uplink carrier for random access can be randomly selected from a set of available uplink carriers. Additionally, the uplink carrier for random access can be selected based upon which uplink carrier is paired with an anchor carrier. Further, the uplink carrier for random access can be identified based upon a bandwidth related to the user equipment (UE). Reference signals can also be employed in order to identify an uplink carrier to perform random access.

Claims

1. A method for wireless communication that facilitates performing random access within a multiple carrier wireless environment, comprising:

determining an uplink carrier to be used by a user equipment (UE) for random access from among multiple uplink carriers; and

performing random access via the determined uplink carrier.

2. The method of claim 1, determining the uplink carrier further comprises:

determining a downlink anchor carrier among multiple downlink carriers, and

selecting an uplink carrier corresponding to the downlink anchor carrier as the uplink carrier to be used for random access.

3. The method of claim 1, determining the uplink carrier further comprises:

determining a downlink carrier on which the UE is camped on the downlink carrier to which the UE is synchronized and receives at least a portion of system information, and

selecting an uplink carrier corresponding to the downlink carrier as the uplink carrier to be used for random access.

4. The method of claim 1, determining the uplink carrier further comprises randomly selecting one of the multiple uplink carriers for which the UE knows the random access parameters as the uplink carrier to be used for random access.

5. The method of claim 1, determining the uplink carrier further comprises:

determining a set of one or more uplink carriers based on bandwidth capability of the UE, and

selecting an uplink carrier from among the set of one or more uplink carriers as the uplink carrier to be used for random access.

6. The method of claim 1, performing random access further comprises:

sending a random access preamble to a base station;

receiving a random access response comprising an uplink grant from the base station; and

sending a scheduled transmission to the base station in accordance with the uplink grant.

7. The method of claim 1, further comprising:

receiving reference signals from detectable cells on interference cleared resources; and

obtaining reference signal measurements for the detectable cells.

8. The method of claim 7, performing random access further comprises:

sending the reference signal measurements to a first cell;

receiving a message identifying a second cell selected based on the reference signal measurements; and

accessing the second cell.

9. The method of claim 8, accessing the second cell further comprises:

obtaining system information of the second cell from the received message; and

accessing the second cell based on the system information.

10. The method of claim 7, determining the uplink carrier further comprises selecting a cell and an uplink carrier for random access based on the reference signal measurements, and performing random access further comprises performing random access to the selected cell via the selected uplink carrier.

11. The method of claim 10, selecting the cell and the uplink carrier further comprises selecting the cell and the uplink carrier based further on loading information for the detectable cells.

12. The method of claim 1, performing random access further comprises sending a random access preamble on uplink resources cleared of interference from neighbor cells.

13. The method of claim 1, further comprising:

if the random access is unsuccessful,

selecting a different uplink carrier from among the multiple uplink carriers; and

performing random access via the different uplink carrier.

14. The method of claim 1, performing random access further comprises:

identifying a set of Physical Random Access Channel (PRACH) parameters for each of at least one downlink (DL) carrier;

selecting an uplink carrier corresponding to the acquired downlink carrier as the uplink carrier to be used for random access; and

performing the random access on the selected uplink carrier using the corresponding PRACH parameters

enabling a base station to identify the downlink carrier acquired by the UE based upon the set of PRACH parameters identified and used by the UE to perform random access; and

receiving the random access response on the acquired downlink carrier.

15. The method of claim 14, wherein the acquired DL carrier is the downlink anchor carrier.

16. The method of claim 14, further comprising identifying at least one of a specific radio frame, a subframe within the radio frame, and a physical resource block in a frequency domain based upon the set of PRACH parameters.

17. The method of claim 1, performing random access further comprises:

identifying a set of Physical Random Access Channel (PRACH) parameters with each of at least one DL carrier;

determining a downlink anchor carrier among the at least one downlink carrier;

selecting an uplink carrier corresponding to the downlink anchor carrier as the uplink carrier to be used for random access; and

performing the random access on the selected uplink carrier using the corresponding PRACH parameters;

enabling a base station to identify the downlink anchor carrier based upon the set of PRACH parameters identified; and

receiving the random access response on the downlink anchor carrier.

18. A wireless communications apparatus, comprising:

at least one processor configured to;

determine an uplink carrier to be used by a user equipment (UE) for random access from among multiple uplink carriers;

perform random access via the determined uplink carrier; and

a memory coupled to the at least one processor.

19. The wireless communications apparatus of claim 18, further comprising:

at least one processor configured to;

determine a downlink anchor carrier among multiple downlink carriers, and

select an uplink carrier corresponding to the downlink anchor carrier as the uplink carrier to be used for random access.

20. The wireless communications apparatus of claim 18, further comprising:

at least one processor configured to;

determine a downlink carrier on which the UE is camped on the downlink carrier to which the UE is synchronized and receives at least a portion of system information, and

select an uplink carrier corresponding to the downlink carrier as the uplink carrier to be used for random access.

21. The wireless communications apparatus of claim 18, further comprising:

at least one processor configured to randomly select one of the multiple uplink carriers for which the UE knows the random access parameters as the uplink carrier to be used for random access.

22. The wireless communications apparatus of claim 18, further comprising:

at least one processor configured to;

determine a set of one or more uplink carriers based on bandwidth capability of the UE, and

select an uplink carrier from among the set of one or more uplink carriers as the uplink carrier to be used for random access.

23. A wireless communications apparatus selects an uplink carrier for random access, comprising:

means for determining an uplink carrier to be used by a user equipment (UE) for random access from among multiple uplink carriers; and

means for performing random access via the determined uplink carrier.

24. The wireless communications apparatus of claim 23, means for determining the uplink carrier further comprises:

means for determining a downlink anchor carrier among multiple downlink carriers, and

means for selecting an uplink carrier corresponding to the downlink anchor carrier as the uplink carrier to be used for random access.

25. The wireless communications apparatus of claim 23, means for determining the uplink carrier further comprises:

means for determining a downlink carrier on which the UE is camped on the downlink carrier to which the UE is synchronized and receives at least a portion of system information, and

means for selecting an uplink carrier corresponding to the downlink carrier as the uplink carrier to be used for random access.

26. The wireless communications apparatus of claim 23, means for determining the uplink carrier further comprises randomly selecting one of the multiple uplink carriers for which the UE knows the random access parameters as the uplink carrier to be used for random access.

27. The wireless communications apparatus of claim 23, means for determining the uplink carrier further comprises:

means for determining a set of one or more uplink carriers based on bandwidth capability of the UE, and

means for selecting an uplink carrier from among the set of one or more uplink carriers as the uplink carrier to be used for random access.

28. The wireless communications apparatus of claim 23, means for performing random access further comprises:

means for sending a random access preamble to a base station;

means for receiving a random access response comprising an uplink grant from the base station; and

means for sending a scheduled transmission to the base station in accordance with the uplink grant.

29. The wireless communications apparatus of claim 23, further comprising:

means for receiving a reference signal from detectable cells; and

means for obtaining the reference signal measurement for the detectable cells.

30. The wireless communications apparatus of claim 29, wherein the reference signal from detectable cells is on interference cleared resources.

31. The wireless communications apparatus of claim 29, means for performing random access further comprises:

means for sending the reference signal measurement to a first cell;

means for receiving a message identifying a second cell selected based on the reference signal measurement; and

means for accessing the second cell.

32. The wireless communications apparatus of claim 31, means for accessing the second cell further comprises:

means for obtaining system information of the second cell from the received message; and

means for accessing the second cell based on the system information.

33. The wireless communications apparatus of claim 29, means for determining the uplink carrier further comprises:

means for selecting a cell and an uplink carrier for random access based on the reference signal measurement; and

means for performing random access further comprises performing random access to the selected cell via the selected uplink carrier.

34. The wireless communications apparatus of claim 33, means for selecting the cell and the uplink carrier further comprises means for selecting the cell and the uplink carrier based further on loading information for the detectable cells.

35. The wireless communications apparatus of claim 23, means for performing random access further comprises means for sending a random access preamble on uplink resources cleared of interference from neighbor cells.

36. The wireless communications apparatus of claim 23, further comprising:

if the random access is unsuccessful,

means for selecting a different uplink carrier from among the multiple uplink carriers; and

means for performing random access via the different uplink carrier.

37. The wireless communications apparatus of claim 23, performing random access further comprises:

means for identifying a set of Physical Random Access Channel (PRACH) parameters for each of at least one downlink (DL) carrier, wherein a base station defines the set of PRACH parameters;

means for selecting an uplink carrier corresponding to the acquired downlink carrier as the uplink carrier to be used for random access; and

means for performing the random access on the selected uplink carrier using the corresponding PRACH parameters

means for enabling a base station to identify the downlink carrier acquired by the UE based upon the set of PRACH parameters identified and used by the UE to perform random access; and

means for receiving the random access response on the acquired downlink carrier.

38. The wireless communications apparatus of claim 37, wherein the downlink carrier is the anchor downlink carrier.

39. The wireless communications apparatus of claim 37, further comprising means for identifying at least one of a specific radio frame, a subframe within the radio frame, and a physical resource block in a frequency domain based upon the set of PRACH parameters.

40. A computer program product, comprising:

a computer-readable medium comprising;

code for causing at least one computer to determine an uplink carrier to be used by a user equipment (UE) for random access from among multiple uplink carriers; and

code for causing at least one computer to perform random access via the determined uplink carrier.

41. A method for wireless communication that facilitates performing random access for multiple carriers in a wireless environment, comprising:

receiving a random access preamble related to a random access for a user equipment (UE) via an uplink carrier, wherein the uplink carrier is determined among multiple uplink carriers; and

performing random access based on the determined uplink carrier.

42. The method of claim 41, further comprising:

determining a downlink carrier among multiple downlink carriers, and

selecting an uplink carrier corresponding to the downlink carrier as the uplink carrier to be used for random access; and

notifying the UE about the uplink carrier selection to perform the random access.

43. The method of claim 42, wherein the downlink carrier is the anchor carrier.

44. The method of claim 42, determining the downlink carrier further comprises selecting a cell and a downlink carrier for random access based on at least one of the reference signal measurements, channel quality feedback, and loading information for the detectable cells.

45. The method of claim 41, further comprising:

determining a set of one or more uplink carriers based on bandwidth capability of the UE, and

selecting an uplink carrier from among the set of one or more uplink carriers as the uplink carrier to be used for random access; and

notifying the UE about the uplink carrier selection to perform the random access.

46. The method of claim 45, selecting the uplink carrier further comprises selecting a cell and an uplink carrier for random access based on at least one of the reference signal measurements, channel quality feedback, and loading information for the detectable cells.

47. The method of claim 41, performing random access further comprises:

receiving a random access preamble at a base station;

determining the set of one or more downlink carriers to use for random access

transmitting a random access response on the determined set of one or more downlink carriers comprising an uplink grant from the base station; and

receiving a scheduled transmission at the base station in accordance with the uplink grant.

48. The method of claim 47, further comprising:

identifying the downlink carrier acquired by the UE based upon the set of PRACH parameters defined and used by the UE to perform random access; and

transmitting the random access response on the identified downlink carrier.

49. The method of claim 41, performing random access further comprises receiving a random access preamble on uplink resources cleared of interference from neighbor cells.

50. The method of claim 41, further comprising:

if the random access is unsuccessful,

selecting a different uplink carrier from among the multiple uplink carriers;

notifying the UE about the uplink carrier selection to perform the random access. and

performing random access based on the different uplink carrier.

51. The method of claim 41, further comprising clearing a resource of interference for at least one detectable cell, wherein the resource is needed for random access.

52. A method for wireless communication that facilitates performing random access for multiple carriers in a wireless environment, comprising:

defining a set of Physical Random Access Channel (PRACH) parameters for each of at least one downlink (DL) carrier.

53. The method of claim 52, wherein the set of parameters includes at least a specific radio frame, a subframe within the radio frame, and a physical resource block in a frequency domain.

54. The method of claim of claim 52, further comprising:

identifying the downlink carrier acquired by the UE based upon the set of PRACH parameters defined and used by the UE to perform random access; and

transmitting the random access response on the identified downlink carrier.

55. The method of claim 52, further comprising:

determining a downlink carrier among the at least one downlink carrier;

selecting an uplink carrier corresponding to the downlink carrier as the uplink carrier to be used for random access; and

notifying the UE about the uplink carrier selection to perform the random access.

56. The method of claim 52, determining the downlink carrier further comprises selecting a cell and a downlink carrier for random access based on at least one of the reference signal measurements, channel quality feedback, and loading information for the detectable cells.

57. A wireless communications apparatus, comprising:

at least one processor configured to;

receive a random access preamble related to a random access for a user equipment (UE) via an uplink carrier, wherein the uplink carrier is determined among multiple uplink carriers; and

perform random access based on the determined uplink carrier; and

a memory coupled to the at least one processor.

58. A wireless communications apparatus, comprising:

at least one processor configured to;

define a set of Physical Random Access Channel (PRACH) parameters for each of at least one downlink (DL) carrier.

59. The wireless communications apparatus of claim 58, further comprising:

at least one processor configured to;

identify the downlink carrier acquired by the UE based upon the set of PRACH parameters defined and used by the UE to perform random access; and

transmit the random access response on the identified downlink carrier.

60. The wireless communications apparatus of claim 58, further comprising:

at least one processor configured to;

determine a downlink carrier among the at least one downlink carrier;

select an uplink carrier corresponding to the downlink carrier as the uplink carrier to be used for random access; and

notify the UE about the uplink carrier selection to perform the random access.

61. A wireless communications apparatus that performs random access for multiple carriers in a wireless environment, comprising:

means for receiving a random access preamble related to a random access for a user equipment (UE) via an uplink carrier, wherein the uplink carrier is determined among multiple uplink carriers; and

means for performing random access based on the determined uplink carrier.

62. A wireless communications apparatus that performs random access for multiple carriers in a wireless environment, comprising:

means for defining a set of Physical Random Access Channel (PRACH) parameters for each of at least one downlink (DL) carrier.

63. The wireless communications apparatus of claim 62, further comprising:

means for identifying the downlink carrier acquired by the UE based upon the set of PRACH parameters defined and used by the UE to perform random access; and

means for transmitting the random access response on the identified downlink carrier.

64. The wireless communications apparatus of claim 62, further comprising:

means for determining a downlink carrier among the at least one downlink carrier;

means for selecting an uplink carrier corresponding to the downlink carrier as the uplink carrier to be used for random access; and

means for notify the UE about the uplink carrier selection to perform the random access.

65. A computer program product, comprising:

a computer-readable medium comprising;

code for causing at least one computer to receive a random access preamble related to a random access for a user equipment (UE) via an uplink carrier, wherein the uplink carrier is determined among multiple uplink carriers; and

code for causing at least one computer to perform random access via the determined uplink carrier.

66. A computer program product, comprising:

a computer-readable medium comprising;

code for causing at least one computer to define a set of Physical Random Access Channel (PRACH) parameters for each of at least one downlink (DL) carrier.

67. The computer program product of claim 66, further comprising:

a computer-readable medium comprising;

code for causing at least one computer to identify the downlink carrier acquired by the UE based upon the set of PRACH parameters defined and used by the UE to perform random access; and

code for causing at least one computer to transmit the random access response on the identified downlink carrier.

68. The computer program product of claim 66, further comprising:

a computer-readable medium comprising;

code for causing at least one computer to determine a downlink carrier among the at least one downlink carrier;

code for causing at least one computer to select an uplink carrier corresponding to the downlink carrier as the uplink carrier to be used for random access; and

code for causing at least one computer to notify the UE about the uplink carrier selection to perform the random access.

69. A method that facilitates utilizing an offset with a downlink carrier, comprising:

defining one or more time offsets that corresponds to a downlink carrier to which Physical Random Access Channel (PRACH) is intended;

employing the one or more time offsets when communicating a message via an uplink; and

identifying the downlink carrier based upon the received time offset.

70. The method of claim 69, wherein the one or more time offsets are different for different downlink carriers sharing the same PRACH parameters.

71. The method of claim 69, further comprising broadcasting the one or more time offsets that corresponds to the downlink carrier.

72. The method of claim 69, further comprising retaining the one or more time offsets in a memory.

73. The method of claim 69, wherein the one or more time offsets are at least one of predefined, dynamically determined, or retained in memory.