TECHNIQUES FOR CELL ACCESS USING AN UNLICENSED RADIO FREQUENCY SPECTRUM BAND

• US 20160242213A1
• Filed: 02/16/2016
• Published: 08/18/2016
• Est. Priority Date: 02/18/2015
• Status: Active Grant

• Current Assignee: Qualcomm, Inc.
• Original Assignee: Qualcomm, Inc.
• Inventors: Dabeer, Onkar Jayant, Damnjanovic, Aleksandar, Vajapeyam, Madhavan Srinivasan, Zhang, Xiaoxia, Patel, Shimman Arvind, Chen, Wanshi, Wei, Yongbin
• Granted Patent: US 10,201,016 B2
• Time in Patent Office: Days
• US Class Current: 1/1
• CPC Class Codes: H04W 16/14 Spectrum sharing arrangements between different networks
• CPC Class Codes: H04W 74/0808 using carrier sensing, e.g. carrier sense multiple access [CSMA]
• CPC Class Codes: H04W 74/0833 Random access procedures, e.g. with 4-step access

Abstract

Techniques are described for wireless communication. One method includes winning a contention for access to an unlicensed radio frequency spectrum band, transmitting a request message upon winning the contention for access to the unlicensed radio frequency spectrum band, and receiving a response message over the unlicensed radio frequency spectrum band. The request message is transmitted by a user equipment (UE) on an enhanced physical random access channel (ePRACH) or shortened ePRACH (SePRACH), to access a cell that operates in the unlicensed radio frequency spectrum band. The response message is received in response to transmitting the request message, and the request message may be transmitted irrespective of whether a base station has gained access to the unlicensed radio frequency spectrum band.

Claims

1. A method of wireless communication comprising:

determining a subframe within a radio frame available for transmission of a request message for access to an unlicensed radio frequency spectrum band;

identifying a first subset of symbols within the subframe for performing a contention-based access procedure for gaining access to the unlicensed radio frequency spectrum band, and a second subset of symbols within the subframe for transmission of the request message for access to the unlicensed radio frequency spectrum band;

performing the contention-based access procedure during the first subset of symbols; and

transmitting the request message during the second subset of symbols based on an outcome of the contention-based access procedure.

2. The method of claim 1, further comprising:

transmitting the request message comprises transmitting the request message on an enhanced physical random access channel (ePRACH) over the unlicensed radio frequency spectrum band, to access a cell that operates in the unlicensed radio frequency spectrum band.

3. The method of claim 1, wherein the first subset of symbols is identified based at least in part on a hardware delay or software delay for detecting a channel occupancy signal from another node and a subframe boundary of the subframe within the radio frame, and wherein the second subset of symbols is identified based at least in part on the first subset of symbols, an identified symbol within the subframe for transmission of the channel occupancy signal from another node, or a transmit-to-receive switching delay.

4. The method of claim 1, wherein the request message comprises a first symbol and a second symbol, the first symbol including a demodulation reference signal (DMRS) and the second symbol comprising data associated with the request message.

5. The method of claim 4, wherein the request message is multiplexed with one or more other nodes through a DMRS shift for the first symbol and data interlacing for the second symbol.

6. The method of claim 1, wherein the transmission of the request message is unaligned with a subframe boundary of the subframe and aligned with a symbol boundary.

7. The method of claim 1, further comprising:

receiving, in a system information block, an indication of at least one of the subframe, the first subset of symbols, or the second subset of symbols.

8. The method of claim 1, further comprising:

determining that one or more other resources are available for transmission of the request message; and

selecting one of the available resources for transmission of the request message based at least in part on a prioritization of available resources.

9. The method of claim 8, wherein the prioritization of available resources for transmission of the request message is based on a prioritization of resources received in a system information block or a biased random selection of available resources.

10. The method of claim 9, wherein the request message is an unscheduled request message.

11. A method of wireless communication comprising:

identifying one or more subframes within one or more radio frames for reception of a request message for access to an unlicensed radio frequency spectrum band by a user equipment (UE); and

identifying a subset of symbols within the identified one or more subframes for reception of the request message for access to the unlicensed radio frequency spectrum band.

12. The method of claim 11, further comprising:

transmitting an indication of the identified one or more subframes and the subset of symbols to the UE, wherein the indication is transmitted in a system information block (SIB).

13. The method of claim 11, wherein the indication further comprises a further identification of one or more other resources available for transmission of the request message and a prioritization of available resources.

14. The method of claim 11, further comprising:

monitoring the subset of symbols for a request message from the UE to access the unlicensed radio frequency spectrum band.

15. The method of claim 11, wherein the subset of symbols is identified based at least in part on a time for transmission of a channel occupancy signal from another node, or a transmit-to-receive switching delay.

16. The method of claim 11, wherein the request message comprises a first symbol and a second symbol, the first symbol including a demodulation reference signal (DMRS) and the second symbol comprising data associated with the request message.

17. An apparatus for wireless communications at a wireless device, comprising:

a processor; and

memory coupled with the processor, wherein the processor is configured to;

determine a subframe within a radio frame available for transmission of a request message for access to an unlicensed radio frequency spectrum band;

identify a first subset of symbols within the subframe for performing a contention-based access procedure for gaining access to the unlicensed radio frequency spectrum band, and a second subset of symbols within the subframe for transmission of the request message for access to the unlicensed radio frequency spectrum band;

perform the contention-based access procedure during the first subset of symbols; and

transmit the request message during the second subset of symbols based on an outcome of the contention-based access procedure.

18. The apparatus of claim 17, wherein the processor is further configured to:

transmit the request message comprises transmitting the request message on an enhanced physical random access channel (ePRACH) over the unlicensed radio frequency spectrum band, to access a cell that operates in the unlicensed radio frequency spectrum band.

19. The apparatus of claim 17, wherein the first subset of symbols is identified based at least in part on a hardware delay or software delay for detecting a channel occupancy signal from another node and a subframe boundary of the subframe within the radio frame, and wherein the second subset of symbols is identified based at least in part on the first subset of symbols, an identified symbol within the subframe for transmission of the channel occupancy signal from another node, or a transmit-to-receive switching delay.

20. The apparatus of claim 17, wherein the request message comprises a first symbol and a second symbol, the first symbol including a demodulation reference signal (DMRS) and the second symbol comprising data associated with the request message.

21. The apparatus of claim 20, wherein the request message is multiplexed with one or more other nodes through a DMRS shift for the first symbol and data interlacing for the second symbol.

22. The apparatus of claim 17, wherein the transmission of the request message is unaligned with a subframe boundary of the subframe and aligned with a symbol boundary.

23. The apparatus of claim 17, wherein the processor is further configured to:

receive, in a system information block, an indication of at least one of the subframe, the first subset of symbols, or the second subset of symbols.

24. The apparatus of claim 17, wherein the processor is further configured to:

determine that one or more other resources are available for transmission of the request message; and

select one of the available resources for transmission of the request message based at least in part on a prioritization of available resources.

25. The apparatus of claim 24, wherein the prioritization of available resources for transmission of the request message is based on a prioritization of resources received in a system information block or a biased random selection of available resources.

26. The apparatus of claim 25, wherein the request message is an unscheduled request message.

27. An apparatus for wireless communications at a wireless device, comprising:

a processor; and

memory coupled with the processor, wherein the processor is configured to;

identify one or more subframes within one or more radio frames for reception of a request message for access to an unlicensed radio frequency spectrum band by a user equipment (UE); and

identify a subset of symbols within the identified one or more subframes for reception of the request message for access to the unlicensed radio frequency spectrum band.

28. The apparatus of claim 27, wherein the processor is further configured to:

transmit an indication of the identified one or more subframes and the subset of symbols to the UE, wherein the indication is transmitted in a system information block (SIB).

29. The apparatus of claim 27, wherein the indication further comprises a further identification of one or more other resources available for transmission of the request message and a prioritization of available resources.

30. The apparatus of claim 27, wherein the processor is further configured to:

monitor the subset of symbols for a request message from the UE to access the unlicensed radio frequency spectrum band.