COLLISION DETECTION IN A SHARED RADIO FREQUENCY SPECTRUM BAND

• US 20170111931A1
• Filed: 08/24/2016
• Published: 04/20/2017
• Est. Priority Date: 10/15/2015
• Status: Active Grant

• Current Assignee: Qualcomm, Inc.
• Original Assignee: Qualcomm, Inc.
• Inventors: Damnjanovic, Aleksandar, Wentink, Maarten Menzo, Yerramalli, Srinivas, Wang, Qingsi, Wei, Yongbin, Montojo, Juan
• Granted Patent: US 10,182,456 B2
• Time in Patent Office: Days
• CPC Class Codes: H04L 5/0055 Physical resource allocation for ACK/NACK for physical mapping arrangements in ARQ protocols H04L1/1861
• CPC Class Codes: H04W 16/14 Spectrum sharing arrangements between different networks
• CPC Class Codes: H04W 74/0825 with collision detection
• CPC Class Codes: H04W 74/0858 collision detection
• CPC Class Codes: H04W 88/06 adapted for operation in multiple networks or having at least two operational modes, e.g. multi-mode terminals

Abstract

Detection and reporting techniques for collisions between transmitters of two different radio access technologies (RATs) transmitting in a shared radio frequency spectrum band is described. The collision may occur following a listen-before-talk procedure but prior to transmission of data, and may not affect the reception of the transmitted data. Collisions may be detected using for example, energy sensing, preamble or ready-to-send (RTS) signal detection, or unsuccessful decoding of all or part of a channel reservation signal. A transmitting device may determine a collision has occurred by detecting an energy level during a preamble transmission is greater than a threshold level or by detecting that an energy level during a transmission gap of a time-domain energy pattern is above a threshold level. A receiving device, such as a user equipment (UE), that detects the collision may report the collision to the transmitter.

Claims

1. A method for wireless communication at a user equipment, comprising:

detecting a signal in a shared radio frequency spectrum band, the signal including a first communication transmitted using a first radio access technology and a second communication transmitted using a second radio access technology, the second communication overlapping at least a portion of the first communication;

determining a collision of the first communication and the second communication based at least in part on the detecting; and

reporting the collision to a node of a wireless communications network associated with the user equipment.

2. The method of claim 1, wherein the first communication comprises a channel reservation signal transmitted by a first transmitter using the first radio access technology.

3. The method of claim 2, wherein the collision occurs at the beginning of a transmission opportunity (TxOP), and collides over a portion of the channel reservation signal.

4. The method of claim 2, wherein the channel reservation signal comprises one or more of a channel usage beacon signal (CUBS) or a fractional CUBS transmitted by the first transmitter.

5. The method of claim 1, wherein the second communication comprises a request to send (RTS) transmission transmitted by a second transmitter using the second radio access technology.

6. The method of claim 1, wherein the determining the collision comprises:

identifying a difference in an energy level of the signal for a first portion of a transmission time period that exceeds an energy level of the first communication.

7. The method of claim 6, wherein determining the collision further comprises:

identifying that a duration of the difference in the energy level corresponds to a transmission duration used for a request to send (RTS) transmission associated with the second radio access technology.

8. The method of claim 1, wherein reporting the collision comprises transmitting an indication on one or more of a physical uplink shared channel (PUSCH) or a physical uplink control channel (PUCCH) to the node of the wireless communications network associated with the user equipment.

9. The method of claim 1, wherein the first communication comprises a data portion, the method further comprising:

identifying that the collision occurred between the first communication and the second communication prior to the data portion of the first communication being transmitted.

10. The method of claim 9, wherein identifying that the collision occurred comprises:

attempting to decode a second signal transmitted by a first transmitter prior to the data portion of the first communication; and

identifying the collision based at least in part on unsuccessfully decoding at least a portion of the second signal.

11. The method of claim 10, wherein the second signal transmitted by the first transmitter prior to the data portion of the first communication comprises a code sequence having a transmission duration that is greater than or equal to a request to send (RTS) duration of an RTS signal of the second radio access technology and extends to a signal transmission boundary associated with the first radio access technology, and

wherein identifying the collision is based at least in part on unsuccessful decoding at least a portion of the code sequence.

12. The method of claim 9, further comprising

receiving a second signal transmitted by a first transmitter prior to the data portion of the first communication;

and

wherein identifying that the collision occurred is based at least in part on an energy level detected during the second signal.

13. The method of claim 12, wherein the received second signal comprises a time-domain energy signature that includes a first high energy period and a subsequent first low energy period;

and

wherein identifying that the collision occurred is based at least in part on identifying that an energy level detected during the first low energy period is greater than a threshold.

14. The method of claim 13, wherein the received second signal comprises a second high energy period, following the first low energy period, that extends to a signal transmission boundary associated with the first radio access technology.

15. The method of claim 13, wherein the received second signal further comprises a second low energy period, following the first low energy period;

the method further comprising;

identifying that a second collision occurred prior to the data portion of the first communication between the first transmitter and a third transmitter that transmits over the shared radio frequency spectrum band using the first radio access technology based at least in part on an energy level detected during the second low energy period.

16. An apparatus for wireless communication at a user equipment, 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;

detect a signal in a shared radio frequency spectrum band, the signal including a first communication transmitted using a first radio access technology and a second communication transmitted using a second radio access technology, the second communication overlapping at least a portion of the first communication;

determine a collision of the first communication and the second communication based at least in part on detecting; and

report the collision to a node of a wireless communications network associated with the user equipment.

17. The apparatus of claim 16, wherein the instructions are further operable to cause the apparatus to:

receive the first communication as a first transmission from a first transmitter over the shared radio frequency spectrum band;

identify that the collision occurred between the first communication and the second communication prior to a data portion of the first transmission being transmitted.

18. A method for wireless communication at a base station, comprising:

transmitting a first communication to a user equipment over a shared radio frequency spectrum band using a first radio access technology, wherein the first communication comprises a time-domain energy signature that includes a first high energy period and a subsequent first low energy period;

identifying that a collision occurred between the first communication and a second communication from a second transmitter using a second radio access technology based at least in part on an energy level detected during the time-domain energy signature; and

increasing a contention window for a subsequent communication transmitted over the shared radio frequency spectrum band based at least in part on the identifying.

19. The method of claim 18, further comprising:

transmitting a third communication to the user equipment over the shared radio frequency spectrum band using the first radio access technology;

receiving an acknowledgement that the third communication has been successfully received by the user equipment; and

resetting the contention window to a predetermined value based at least in part on the acknowledgement being received without a second indication that a second collision occurred.

20. The method of claim 18, wherein increasing the contention window comprises linearly increasing or exponentially increasing the contention window.

21. The method of claim 18, further comprising:

observing a maximum time period of the contention window for the subsequent communication.

22. The method of claim 18, wherein the first communication comprises a code sequence having a transmission duration that is greater than or equal to a request to send (RTS) duration of an RTS signal of the second radio access technology and extends to a signal transmission boundary associated with the first radio access technology.

23. The method of claim 18, further comprising:

receiving an acknowledgement that a data portion of the first communication was successfully decoded by the user equipment.

24. The method of claim 18, wherein the first communication further comprises a second high energy period, following the first low energy period, that extends to a signal transmission boundary associated with the first radio access technology.

25. The method of claim 18, wherein the first communication further comprises a second low energy period, following the first low energy period, wherein an interval for the second low energy period is randomly selected.

26. The method of claim 18, wherein identifying that the collision occurred is based at least in part on identifying that the energy level detected during the first low energy period of the time-domain energy signature is greater than a threshold.

27. The method of claim 18, wherein the identifying that the collision occurred comprises receiving, from a UE, an indication that the collision occurred based at least in part on the energy level being detected by the UE during the time-domain energy signature.

28. The method of claim 18, wherein a time duration of the first low energy period is less than a maximum time duration for discontinuing a transmission over the shared radio frequency spectrum band that allows the transmission to be resumed without performing a listen before talk (LBT) procedure.

29. The method of claim 18, wherein the first communication further comprises a data portion, and wherein the time-domain energy signature is transmitted prior to the data portion.

30. An apparatus for wireless communication at a base station, 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;

transmit a first communication to a user equipment over a shared radio frequency spectrum band using a first radio access technology, wherein the first communication comprises a time-domain energy signature that includes a first high energy period and a subsequent first low energy period;

identifying, by the base station, that a collision occurred between the first communication and a second communication from a second transmitter using a second radio access technology based at least in part on an energy level detected during the time-domain energy signature; and

increase a contention window for a subsequent communication transmitted over the shared radio frequency spectrum band based at least in part on the identifying.