Method and device for performing random access process in unlicensed band
Provided are a method for performing a random access process in an unlicensed band, and a device using the same. The device receives a random access preamble (RAP) order instructing the transmission of a RAP. The device performs a clear channel assessment (CCA) in an unlicensed cell during an RAP window so as to transmit the RAP when the device succeeds in CCA.
1. A method for performing a random access in an unlicensed band, the method performed by a wireless device and comprising:
transmitting a random access preamble;
receiving a random access response as a response to the random access preamble, wherein the random access response includes a timing advance command (TAC) to be applied to a transmission of a scheduled message, an uplink resource allocation assigned to the transmission of the scheduled message and a listen before talk (LBT) parameter to be applied to a LBT operation for the transmission of the scheduled message; and
sensing a channel based on the LBT parameter before transmitting the scheduled message,
wherein
based on the LBT parameter being related to a first LBT scheme, the scheduled message is transmitted by the wireless device after the channel is sensed to be idle for a predefined time, and
based on the LBT parameter being related to a second LBT scheme, the scheduled message is transmitted by the wireless device based on the channel being sensed to be idle for a channel detection time related to a value which is randomly selected by the wireless device.
2. The method of claim 1 , wherein the random access response further includes a temporary identifier to be used in the scheduled message.
3. The method of claim 1 , further comprising:
transmitting the scheduled message by using the uplink resource.
4. A device comprising:
a processor; and
a memory operatively coupled with the processor and storing instructions that when executed by the processor cause the device to:
transmit a random access preamble; and
receive a random access response as a response to the random access preamble, wherein the random access response includes a timing advance command (TAC) to be applied to a transmission of a scheduled message, an uplink resource allocation assigned to the transmission of the scheduled message and a listen before talk (LBT) parameter to be applied to a LBT operation for the transmission of the scheduled message; and
sense a channel based on the LBT parameter before transmitting the scheduled message,
wherein
based on the LBT parameter being related to a first LBT scheme, the scheduled message is transmitted by the device after the channel is sensed to be idle for a predefined time, and
based on the LBT parameter being related to a second LBT scheme, the scheduled message is transmitted by the device based on the channel being sensed to be idle for a channel detection time related to a value which is randomly selected by the device.
5. The device of claim 4 , wherein the random access response further includes a temporary identifier to be used in the scheduled message.
6. A method for performing a random access in an unlicensed band, the method performed by a base station and comprising:
receiving, from a wireless device, a random access preamble; and
transmitting, to the wireless device, a random access response as a response to the random access preamble, wherein the random access response includes a timing advance command (TAC) to be applied to a transmission of a scheduled message, an uplink resource allocation assigned to the transmission of the scheduled message and a listen before talk (LBT) parameter to be applied to a LBT operation for the transmission of the scheduled message,
wherein:
based on the LBT parameter being related to a first LBT scheme, the base station instructs the wireless device to transmit the scheduled message based on a channel in the unlicensed band being sensed to be idle for a predefined time, and
based on the LBT parameter being related to a second LBT scheme, the base station instructs the wireless device to transmit the scheduled message base on a channel in the unlicensed band being sensed to be idle for a channel detection time related to a value which is randomly selected by the wireless device.
7. The method of claim 6 , wherein the random access response further includes a temporary identifier to be used in the scheduled message.
8. The method of claim 6 , further comprising:
receiving, from the wireless device, the scheduled message by using the uplink resource.
9. A base station comprising:
a processor; and
a memory operatively coupled with the processor and storing instructions that when executed by the processor cause the device to:
receive, from a wireless device, a random access preamble; and
transmit, to the wireless device, a random access response as a response to the random access preamble, wherein the random access response includes a timing advance command (TAC) to be applied to a transmission of a scheduled message, an uplink resource allocation assigned to the transmission of the scheduled message and a listen before talk (LBT) parameter to be applied to a LBT operation for the transmission of the scheduled message,
wherein:
based on the LBT parameter being related to a first LBT scheme, the base station instructs the wireless device to transmit the scheduled message based on a channel in the unlicensed band being sensed to be idle for a predefined time, and
based on the LBT parameter being related to a second LBT scheme, the base station instructs the wireless device to transmit the scheduled message based on a channel in the unlicensed band being sensed to be idle for a channel detection time related to a value which is randomly selected by the wireless device.
10. The bae station of claim 9 , wherein the random access response further includes a temporary identifier to be used in the scheduled message.