CHANNEL RESERVATION SIGNAL IN NR SHARED SPECTRUM

• US 20190053269A1
• Filed: 08/02/2018
• Published: 02/14/2019
• Est. Priority Date: 08/08/2017
• Status: Active Grant

• Current Assignee: Qualcomm, Inc.
• Original Assignee: Qualcomm, Inc.
• Inventors: LEI, Jing, Sun, Jing, Kadous, Tamer
• Granted Patent: US 10,687,356 B2
• Time in Patent Office: Days
• CPC Class Codes: H04W 28/26 Resource reservation
• CPC Class Codes: H04W 72/0446 Resources in time domain, e.g. slots or frames
• CPC Class Codes: H04W 74/004 in the uplink, i.e. towards network
• 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

Methods, systems, and devices for wireless communication are described. A transmitting device may obtaining channel access after a clear channel assessment (CCA) operation. The transmitting device may then determine an offset between a boundary of a symbol and a particular time at which the channel access is obtained. The transmitting device may generate a channel reservation (CR) preamble based on the offset and transmit the CR preamble. The transmitting device may also generate the CR preamble based on occupancy of sub-bands or beams used by the transmitting device. A receiving device may monitor for a CR message based on the CR preamble.

Claims

1. A method comprising:

obtaining channel access after a clear channel assessment (CCA) operation;

determining an offset between a boundary of a symbol and a particular time at which the channel access is obtained;

generating a channel reservation (CR) preamble based on the offset; and

transmitting the CR preamble.

2. The method of claim 1, wherein the generating the CR preamble includes partitioning the CR preamble into a plurality of segments, each segment comprising a different waveform.

3. The method of claim 2, wherein the plurality of segments comprises a first segment having a fixed duration, a second segment having a variable duration, and a third segment having a fixed duration.

4. The method of claim 3, wherein the variable duration of the second segment is determined so that a total duration of the CR preamble aligns with a duration of the offset.

5. The method of claim 3, wherein the generating the CR preamble further comprises applying a different correlation type to each segment.

6. The method of claim 5, wherein the generating the CR preamble further comprises applying an auto correlation type to the first segment and a cross correlation type to the third segment.

7. The method of claim 1, wherein the CR preamble comprises a dual layer waveform construction, and wherein the generating the CR preamble includes using a short spreading sequence for a first layer and a code cover sequence for a second layer of the CR preamble.

8. The method of claim 7, wherein the generating the CR preamble includes performing a cross product operation of the code cover sequence denoted by a length L vector with the spreading sequence denoted by a length K vector.

9. The method of claim 8, wherein the offset has a duration shorter than a duration of the CR preamble.

10. The method of claim 9, further comprising truncating the CR preamble such that the CR preamble has a starting point aligned with the particular time and an ending point aligned with the boundary of the symbol.

11. The method of claim 9, further comprising aligning an ending point of the CR preamble with a boundary of a next symbol following the symbol and adding a filler signal between the particular time and a beginning of the CR preamble.

12. The method of claim 8, wherein the offset has a duration longer than a duration of the CR preamble.

13. The method of claim 12, further comprising adding at least one filler sample in a gap between an end of the CR preamble and the boundary of the symbol.

14. The method of claim 13, wherein the at least one filler sample comprises at least one of a copy of at least one sample from a beginning of the CR preamble, a copy of at least one sample from an end of a CR message scheduled for transmission in a next symbol following the symbol, or a PN-like signal.

15. 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;

obtain channel access after a clear channel assessment (CCA) operation;

determine an offset between a boundary of a symbol and a particular time at which the channel access is obtained;

generate a channel reservation (CR) preamble based on the offset; and

transmit the CR preamble.

16. The apparatus of claim 15, wherein the generating the CR preamble includes partitioning the CR preamble into a plurality of segments, each segment comprising a different waveform.

17. The apparatus of claim 16, wherein the plurality of segments comprises a first segment having a fixed duration, a second segment having a variable duration, and a third segment having a fixed duration.

18. The apparatus of claim 17, wherein the variable duration of the second segment is determined so that a total duration of the CR preamble aligns with a duration of the offset.

19. The apparatus of claim 17, further comprising applying a different correlation type to each segment.

20. The apparatus of claim 19, further comprising applying an auto correlation type to the first segment and a cross correlation type to the third segment.

21. The apparatus of claim 15, wherein the CR preamble comprises a dual layer waveform construction, and wherein the generating the CR preamble includes using a short spreading sequence for a first layer and a code cover sequence for a second layer of the CR preamble.

22. The apparatus of claim 21, wherein the generating the CR preamble includes performing a cross product operation of the code cover sequence denoted by a length L vector with the spreading sequence denoted by a length K vector.

23. The apparatus of claim 22, wherein the offset has a duration shorter than a duration of the CR preamble.

24. The apparatus of claim 23, further comprising truncating the CR preamble such that the CR preamble has a starting point aligned with the particular time and an ending point aligned with the boundary of the symbol.

25. The apparatus of claim 23, further comprising aligning an ending point of the CR preamble with a boundary of a next symbol following the symbol and adding a filler signal between the particular time and a beginning of the CR preamble.

26. The apparatus of claim 22, wherein the offset has a duration longer than a duration of the CR preamble.

27. The apparatus of claim 26, further comprising adding at least one filler sample in a gap between an end of the CR preamble and the boundary of the symbol.

28. The apparatus of claim 27, wherein the at least one filler sample comprises at least one of a copy of at least one sample from a beginning of the CR preamble, a copy of at least one sample from an end of a CR message scheduled for transmission in a next symbol following the symbol, or a PN-like signal.

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

obtain channel access after a clear channel assessment (CCA) operation;

determine an offset between a boundary of a symbol and a particular time at which the channel access is obtained;

generate a channel reservation (CR) preamble based on the offset; and

transmit the CR preamble.

30. An apparatus for wireless communication, comprising:

means for obtaining channel access after a clear channel assessment (CCA) operation;

means for determining an offset between a boundary of a symbol and a particular time at which the channel access is obtained;

means for generating a channel reservation (CR) preamble based on the offset; and

means for transmitting the CR preamble.