RANDOM ACCESS CHANNEL DESIGN FOR NARROWBAND WIRELESS COMMUNICATION

• US 20170064743A1
• Filed: 08/23/2016
• Published: 03/02/2017
• Est. Priority Date: 08/28/2015
• Status: Active Grant

• Current Assignee: Qualcomm, Inc.
• Original Assignee: Qualcomm, Inc.
• Inventors: Lei, Jing, Vajapeyam, Madhavan Srinivasan, Chen, Wanshi, Rico Alvarino, Alberto, Wang, Renqiu, Xu, Hao, Fakoorian, Seyed Ali Akbar, Patel, Shimman Arvind, Gaal, Peter
• Granted Patent: US 10,080,244 B2
• Time in Patent Office: Days
• US Class Current: 1/1
• CPC Class Codes: H04L 5/0048 Allocation of pilot signals, i.e. of signals known to the receiver
• CPC Class Codes: H04W 16/30 Special cell shapes, e.g. doughnuts or ring cells
• CPC Class Codes: H04W 72/02 Selection of wireless resources by user or terminal
• CPC Class Codes: H04W 72/0453 Resources in frequency domain, e.g. a carrier in FDMA
• CPC Class Codes: H04W 74/002 Transmission of channel access control information
• CPC Class Codes: H04W 74/0833 Random access procedures, e.g. with 4-step access

Abstract

Random access techniques may use subcarriers allocated for random access requests in narrowband communication. Physical resources may be selected for transmission of a random access request based on a “coverage class” of a user equipment (UE). In some examples, a set of coverage classes may be identified based on one or more UE channel conditions, such as pathloss. Each coverage class may have one or more associated subcarriers of a set of subcarriers in a narrowband bandwidth, and random access messages may be transmitted using the associated subcarrier(s) for the coverage class of a UE. In some examples, different coverage classes may have different numbers of redundant transmissions of a random access message, which may be based on channel conditions associated with a particular coverage class. A UE, based on a measured channel condition, may determine a coverage class and select a subcarrier based on the determined coverage class.

Claims

1. A method for wireless communication, comprising:

identifying a set of coverage classes for a wireless device based at least in part on a characteristic of a communication link associated with the wireless device;

identifying, for each coverage class of the set of coverage classes, one or more subcarriers of a set of subcarriers for transmitting random access messages; and

communicating on the one or more subcarriers of the set of subcarriers.

2. The method of claim 1, further comprising:

measuring the characteristic of the communication link at the wireless device;

determining that the wireless device is in a first coverage class based at least in part on the characteristic of the communication link; and

selecting a first subcarrier of the set of subcarriers for transmission of a random access message based at least in part on the first coverage class.

3. The method of claim 2, further comprising:

identifying a token for each coverage class, wherein transmitting the random access message comprises;

determining a random number associated with the random access message; and

transmitting the random access message in response to the random number corresponding to the identified token.

4. The method of claim 1, further comprising:

signaling the identified one or more subcarriers for transmitting random access messages for each coverage class to a plurality of wireless devices.

5. The method of claim 1, wherein the set of subcarriers comprises a plurality of subcarriers within a narrowband region of a wireless communications system bandwidth.

6. The method of claim 5, wherein a subcarrier spacing of adjacent subcarriers of the set of subcarriers corresponds to a same subcarrier spacing as used for data communications within the narrowband region of the wireless communications system bandwidth.

7. The method of claim 5, wherein random access messages are transmitted using a single subcarrier of the set of subcarriers.

8. The method of claim 1, wherein random access messages and data communications are time division multiplexed on one or more of the subcarriers.

9. The method of claim 1, further comprising:

identifying a repetition level for transmitting redundant versions of a random access message for each coverage class of the set of coverage classes.

10. The method of claim 1, wherein random access messages are transmitted asynchronously.

11. The method of claim 10, wherein the random access messages comprise a pilot signal and a payload.

12. The method of claim 11, wherein the payload comprises one or more of an identification of a random access type, a wireless device identity, an access cause, or a coverage class of the wireless device.

13. The method of claim 1, further comprising:

selecting a subcarrier based at least in part on an identified coverage class;

transmitting a random access message using the selected subcarrier, wherein the random access message comprises a random identification number;

receiving an uplink resource allocation based at least in part on the random access message;

transmitting an uplink data packet based at least in part on the uplink resource allocation; and

receiving feedback to acknowledge successful receipt of the uplink data packet.

14. The method of claim 13, further comprising:

determining that additional uplink resources are needed for transmission of uplink data;

transmitting a second random access message based at least in part on the determining, the second random access message comprising an identification provided for the wireless device by a base station;

receiving a second uplink resource allocation based at least in part on the second random access message; and

transmitting a second uplink data packet based at least in part on the second uplink resource allocation.

15. The method of claim 1, further comprising:

identifying a subcarrier of the set of subcarriers within a narrowband region of a wireless communications system bandwidth for transmitting a random access message;

identifying a payload to include in the random access message; and

transmitting the random access message and payload using the identified subcarrier.

16. The method of claim 15, wherein the payload is transmitted using a subset of subcarriers of the set of subcarriers.

17. The method of claim 16, further comprises:

transmitting the payload on each subcarrier of the subset of subcarriers.

18. The method of claim 16, further comprising:

dividing the payload into a plurality of portions;

generating redundancy portions from the payload; and

transmitting a subset of the plurality of portions and a subset of redundancy portions on each subcarrier of the subset of subcarriers.

19. The method of claim 1, wherein the characteristic of the communication link is a pathloss of the communication link.

20. The method of claim 1, wherein the characteristic of the communication link is one of a reference signal received power (RSRP), a reference signal received quality (RSRQ), or a received signal strength indicator (RSSI).

21. An apparatus for wireless communication, comprising:

means for identifying a set of coverage classes for a wireless device based at least in part on a characteristic of a communication link associated with the wireless device;

means for identifying, for each coverage class of the set of coverage classes, one or more subcarriers of a set of subcarriers for transmitting random access messages; and

means for communicating on the one or more subcarriers of the set of subcarriers.

22. The apparatus of claim 21, further comprising:

means for measuring the characteristic of the communication link at the wireless device;

means for determining that the wireless device is in a first coverage class based at least in part on the characteristic of the communication link; and

means for selecting a first subcarrier of the set of subcarriers for transmission of a random access message based at least in part on the first coverage class.

23. The apparatus of claim 22, further comprising:

means for identifying a token for each coverage class;

means for determining a random number associated with the random access message; and

means for transmitting the random access message in response to the random number corresponding to an identified token.

24. The apparatus of claim 21, further comprising:

means for signaling one or more subcarriers for transmitting random access messages for each coverage class to a plurality of wireless devices.

25. The apparatus of claim 21, wherein the set of subcarriers comprises a plurality of subcarriers within a narrowband region of a wireless communications system bandwidth.

26. The apparatus of claim 25, wherein a subcarrier spacing of adjacent subcarriers of the set of subcarriers corresponds to a same subcarrier spacing as used for data communications within the narrowband region of the wireless communications system bandwidth.

27. The apparatus of claim 25, further comprising:

means for transmitting the random access messages using a single subcarrier of the set of subcarriers.

28. The apparatus of claim 21, wherein the random access messages and data communications are time division multiplexed on one or more of the subcarriers.

29. The apparatus of claim 21, further comprising:

means for identifying a repetition level for transmitting redundant versions of a random access message for each coverage class of the set of coverage classes.

30. The apparatus of claim 21, further comprising:

means for transmitting the random access messages asynchronously.

31. The apparatus of claim 30, wherein the random access messages comprise a pilot signal and a payload.

32. The apparatus of claim 31, wherein the payload comprises one or more of an identification of a random access type, a wireless device identity, an access cause, or a coverage class of the wireless device.

33. The apparatus of claim 21, further comprising:

means for selecting a subcarrier based at least in part on an identified coverage class;

means for transmitting a random access message using a selected subcarrier, wherein the random access message comprises a random identification number;

means for receiving an uplink resource allocation based at least in part on the random access message;

means for transmitting an uplink data packet based at least in part on the uplink resource allocation; and

means for receiving feedback to acknowledge successful receipt of the uplink data packet.

34. The apparatus of claim 33, further comprising:

means for determining that additional uplink resources are needed for transmission of uplink data;

means for transmitting a second random access message based at least in part on the determining, the second random access message comprising an identification provided for the wireless device by a base station;

means for receiving a second uplink resource allocation based at least in part on the second random access message; and

means for transmitting a second uplink data packet based at least in part on the second uplink resource allocation.

35. The apparatus of claim 21, further comprising:

means for identifying a subcarrier of the set of subcarriers within a narrowband region of a wireless communications system bandwidth for transmitting a random access message;

means for identifying a payload to include in the random access message; and

means for transmitting the random access message and payload using the identified subcarrier.

36. The apparatus of claim 35, wherein the means for transmitting the random access message and is operable to use a subset of subcarriers of the set of subcarriers.

37. The apparatus of claim 36, further comprising:

means for transmitting the payload on each subcarrier of the subset of subcarriers.

38. The apparatus of claim 36, further comprising:

means for dividing the payload into a plurality of portions;

means for generating redundancy portions from the payload; and

means for transmitting a subset of the plurality of portions and a subset of redundancy portions on each subcarrier of the subset of subcarriers.

39. The apparatus of claim 21, wherein the characteristic of the communication link is a pathloss of the communication link.

40. The apparatus of claim 21, wherein the characteristic of the communication link is one of a reference signal received power (RSRP), a reference signal received quality (RSRQ), or a received signal strength indicator (RSSI).

41. An apparatus for wireless communication, comprising:

a processor;

memory in electronic communication with the processor; and

instructions stored in the memory and operable, when executed by the processor, to cause the apparatus to;

identify a set of coverage classes for a wireless device based at least in part on a characteristic of a communication link associated with the wireless device;

identify, for each coverage class of the set of coverage classes, one or more subcarriers of a set of subcarriers for transmitting random access messages; and

communicate on the one or more subcarriers of the set of subcarriers.

42. The apparatus of claim 41, wherein the instructions are executable by the processor to cause the apparatus to:

measure the characteristic of the communication link at the wireless device;

determine that the wireless device is in a first coverage class based at least in part on the characteristic of the communication link; and

select a first subcarrier of the set of subcarriers for transmission of a random access message based at least in part on the first coverage class.

43. The apparatus of claim 42, wherein the instructions are executable by the processor to cause the apparatus to:

identify a token for each coverage class;

determine a random number associated with the random access message; and

transmit the random access message in response to the random number corresponding to an identified token.

44. The apparatus of claim 41, wherein the instructions are executable by the processor to cause the apparatus to:

signal or more subcarriers for transmitting random access messages for each coverage class to a plurality of wireless devices.

45. The apparatus of claim 41, wherein the set of subcarriers comprises a plurality of subcarriers within a narrowband region of a wireless communications system bandwidth.

46. The apparatus of claim 45, wherein a subcarrier spacing of adjacent subcarriers of the set of subcarriers corresponds to a same subcarrier spacing as used for data communications within the narrowband region of the wireless communications system bandwidth.

47. The apparatus of claim 45, wherein the instructions are executable by the processor to cause the apparatus to:

transmit the random access messages using a single subcarrier of the set of subcarriers.

48. The apparatus of claim 41, wherein the random access messages and data communications are time division multiplexed on one or more of the subcarriers.

49. The apparatus of claim 41, wherein the instructions are executable by the processor to cause the apparatus to:

identify a repetition level for transmitting redundant versions of a random access message for each coverage class of the set of coverage classes.

50. The apparatus of claim 41, wherein the instructions are executable by the processor to cause the apparatus to:

transmit the random access messages asynchronously.

51. The apparatus of claim 50, wherein the random access messages comprise a pilot signal and a payload.

52. The apparatus of claim 51, wherein the payload comprises one or more of an identification of a random access type, a wireless device identity, an access cause, or a coverage class of the wireless device.

53. The apparatus of claim 41, wherein the instructions are executable by the processor to cause the apparatus to:

select a subcarrier based at least in part on an identified coverage class;

transmit a random access message using a selected subcarrier, wherein the random access message comprises a random identification number;

receive an uplink resource allocation based at least in part on the random access message;

transmit an uplink data packet based at least in part on the uplink resource allocation; and

receive feedback to acknowledge successful receipt of the uplink data packet.

54. The apparatus of claim 53, wherein the instructions are executable by the processor to cause the apparatus to:

determine that additional uplink resources are needed for transmission of uplink data;

transmit a second random access message based at least in part on the determining, the second random access message comprising an identification provided for the wireless device by a base station;

receive a second uplink resource allocation based at least in part on the second random access message; and

transmit a second uplink data packet based at least in part on the second uplink resource allocation.

55. The apparatus of claim 41, wherein the instructions are executable by the processor to cause the apparatus to:

identify a subcarrier of the set of subcarriers within a narrowband region of a wireless communications system bandwidth for transmitting a random access message;

identify a payload to include in the random access message; and

transmit the random access message and payload using the identified subcarrier.

56. The apparatus of claim 55, wherein the instructions are executable by the processor to cause the apparatus to:

transmit the payload using a subset of subcarriers of the set of subcarriers.

57. The apparatus of claim 56, wherein the instructions are executable by the processor to cause the apparatus to:

transmit the payload on each subcarrier of the subset of subcarriers.

58. The apparatus of claim 56, wherein the instructions are executable by the processor to cause the apparatus to:

divide the payload into a plurality of portions;

generate redundancy portions from the payload; and

transmit a subset of the plurality of portions and a subset of redundancy portions on each subcarrier of the subset of subcarriers.

59. The apparatus of claim 41, wherein the characteristic of the communication link is a pathloss of the communication link.

60. The apparatus of claim 41, wherein the characteristic of the communication link is one of a reference signal received power (RSRP), a reference signal received quality (RSRQ), or a received signal strength indicator (RSSI).

61. A non-transitory computer readable medium storing code for wireless communication, the code comprising instructions executable by a processor to:

identify a set of coverage classes for a wireless device based at least in part on a characteristic of a communication link associated with the wireless device;

identify, for each coverage class of the set of coverage classes, one or more subcarriers of a set of subcarriers for transmitting random access messages; and

communicating on the one or more subcarriers of the set of subcarriers.