Close loop listen before talk for NR operation in unlicensed spectrum
Various embodiments disclosed herein provide for a closed loop Listen Before Talk (LBT) which is a coexistence mechanism used by wireless technologies such as Wi-Fi, to access unlicensed shared spectrum, such as the ISM UNII bands (5 GHz). The embodiments disclosed herein enable a base station to coordinate the LBT process at both the base station and a receiver in order to avoid hidden node interference where the interfering nodes are outside the sensing range of the transmitting node. The base station device can send a LBT trigger to the receiver to synchronize the clear channel assessments that are performed at each device to determine if there is any activity on the channel. The receiving device can send back a report to the base station device, and if no activity on the channel is detected, the base station device can schedule a transmission on the channel.
1. A device, comprising:
a processor; and
a memory that stores executable instructions that, when executed by the processor, facilitate performance of operations, comprising:
transmitting a first listen before talk trigger to a user equipment, comprising:
in response to a listen before talk duration associated with a first clear channel assessment of a channel to be performed by the user equipment being determined to be less than a length of a slot of control channel, transmitting the first listen before talk trigger to the user equipment in a mini-slot within a duration of a first slot of the control channel in which the first clear channel assessment is to occur, and
in response to the listen before talk duration associated with the first clear channel assessment being determined not to be less than the length of the slot of the control channel, transmitting the first listen before talk trigger to the user equipment in a second slot prior to the first slot.
2. The device of claim 1 , wherein the operations further comprise:
performing a second clear channel assessment of the channel at a defined time associated with the first slot;
receiving a first result of the first clear channel assessment from the user equipment; and
in response to the first result of the first clear channel assessment and a second result of the second clear channel assessment indicating that the channel is clear, scheduling a transmission to the user equipment via the channel.
3. The device of claim 2 , wherein the first result is received in another mini-slot within the duration of the first slot of the control channel in response to the listen before talk duration being determined to be less than the length of the slot.
4. The device of claim 2 , wherein the first result of the first clear channel assessment further comprises information associated with a duration of the first clear channel assessment, a channel occupied indication, and a signal strength measurement.
5. The device of claim 2 , wherein the operations further comprise:
in response to the first result of the first clear channel assessment or the second result of the second clear channel assessment indicating that activity has been detected on the channel, facilitating transmitting a second listen before talk trigger to the user equipment.
6. The device of claim 1 , wherein the first clear channel assessment is performed on an unlicensed frequency band, and the control channel uses a licensed frequency band.
7. The device of claim 1 , wherein the channel comprises a group of beams, and the first clear channel assessment determines that a first beam of the channel is clear and that a second beam of the channel is not clear.
8. A method, comprising:
determining, by a device comprising a processor, that a first clear channel assessment of a channel is to be performed by a mobile device;
transmitting, by the device, a first listen before talk trigger to the mobile device, comprising:
in response to a listen before talk duration associated with the first clear channel assessment being less than a length of a slot of control channel, transmitting the first listen before talk trigger to the mobile device in a mini-slot within a duration of a first slot of the control channel in which the first clear channel assessment will occur, and
in response to the listen before talk duration associated with the first clear channel assessment not being less than the length of the slot of the control channel, transmitting the first listen before talk trigger to the mobile device in a second slot prior to the first slot.
9. The method of claim 8 , further comprising:
performing, by the device, a second clear channel assessment of the channel at a defined time associated with the first slot;
receiving, by the device, a first result of the first clear channel assessment from the user equipment; and
in response to the first result of the first clear channel assessment and a second result of the second clear channel assessment indicating that the channel is clear, scheduling, by the device, a transmission to the mobile device via the channel.
10. The method of claim 9 , wherein the first result is received in another mini-slot within the duration of the first slot of the control channel in response to the listen before talk duration being less than the length of the slot.
11. The method of claim 9 , wherein the first result of the first clear channel assessment further comprises information associated with a duration of the first clear channel assessment, a channel occupied indication, and a signal strength measurement.
12. The method of claim 9 , further comprising:
in response to the first result of the first clear channel assessment or the second result of the second clear channel assessment indicating that activity has been detected on the channel, facilitating transmitting a second listen before talk trigger to the mobile device.
13. The method of claim 8 , wherein the first clear channel assessment is performed on an unlicensed frequency band, and the control channel uses a licensed frequency band.
14. The method of claim 8 , wherein the channel comprises a group of beams, and the first clear channel assessment determines that a first beam of the channel is clear and that a second beam of the channel is not clear.
15. A non-transitory machine-readable medium, comprising executable instructions that, when executed by a processor of a system, facilitate performance of operations, comprising:
transmitting a first listen before talk trigger to a user equipment, comprising:
in response to a listen before talk duration associated with a first clear channel assessment of a channel to be performed by the user equipment being less than a length of a slot of control channel, transmitting the first listen before talk trigger to the user equipment in a mini-slot within a duration of a first slot of the control channel in which the first clear channel assessment is going to occur, and
in response to the listen before talk duration associated with the first clear channel assessment not being less than the length of the slot of the control channel, transmitting the first listen before talk trigger to the user equipment in a second slot prior to the first slot.
16. The non-transitory machine-readable medium of claim 15 , wherein the operations further comprise:
performing a second clear channel assessment of the channel at a defined time associated with the first slot;
receiving a first result of the first clear channel assessment from the user equipment; and
in response to the first result of the first clear channel assessment and a second result of the second clear channel assessment indicating that the channel is clear, scheduling a transmission to the user equipment via the channel.
17. The non-transitory machine-readable medium of claim 16 , wherein the first result is received in another mini-slot within the duration of the first slot of the control channel in response to the listen before talk duration being less than the length of the slot.
18. The non-transitory machine-readable medium of claim 16 , wherein the first result of the first clear channel assessment further comprises information associated with a duration of the first clear channel assessment, a channel occupied indication, and a signal strength measurement.
19. The non-transitory machine-readable medium of claim 16 , wherein the operations further comprise:
in response to the first result of the first clear channel assessment or the second result of the second clear channel assessment indicating that activity has been detected on the channel, facilitating transmitting a second listen before talk trigger to the user equipment.
20. The non-transitory machine-readable medium of claim 15 , wherein the first clear channel assessment is performed on an unlicensed frequency band, and the control channel uses a licensed frequency band.