Method, user equipment and base station for transmitting uplink signals
The present disclosure provides several methods, user equipment (UEs) and base stations for transmitting uplink signals. After receiving uplink synchronization command information, the UE may transmit an uplink signal on at least one idle unlicensed cell. Besides, the UE may try to transmit the uplink signal on multiple uplink signal resources within an uplink signal transmission window. By using the present disclosure, transmission probability of uplink signals may be improved, and time delay of uplink synchronization may be shortened.
1. A method performed by a terminal for a random access procedure in unlicensed frequency bands, the method comprising:
receiving, from a base station, uplink synchronization command subframe n for initiating the random access procedure, the uplink synchronization command including resource allocation information on uplink carriers associated with a timing advance group (TAG);
identifying an uplink resource based on the resource allocation information; and
transmitting, to the base station, a random access preamble in an idle subframe of the uplink resource after subframe n+k on at least one of the uplink carriers, the k being a predetermined value.
2. The method of claim 1 , further comprising:
identifying, from the uplink carriers, one or more uplink carrier, a subframe of the uplink resource after subframe n+k of which is idle by performing a clear channel assessment, CCA, detection to the subframe.
3. The method of claim 2 , wherein the idle subframe of the uplink resource is an idle subframe located at first in the uplink resource in a time domain.
4. The method of claim 2 , wherein the at least one of the uplink carriers is selected based on a priority.
5. A terminal for a random access procedure in unlicensed frequency bands, comprising:
at least one module for transmitting and receiving a signal; and
a controller coupled with the at least one module and configured to control to:
receive, from a base station, uplink synchronization command in subframe n for initiating the random access procedure, the uplink synchronization command including resource allocation information on uplink carriers associated with a timing advance group (TAG),
identify an uplink resource based on the resource allocation information, and
transmit, to the base station, a random access preamble in an idle subframe of the uplink resource after subframe n+k on at least one of the uplink carriers, the k being a predetermined value.
6. The terminal of claim 5 , wherein the controller is further configured to control to:
identifying, from the uplink carriers, one or more uplink carriers, a subframe of the uplink resource after subframe n+k of which is idle by performing a clear channel assessment, CCA, detection to the subframe.
7. The terminal of claim 6 , wherein the idle subframe of the uplink resource is an idle subframe located at first in the uplink resource in a time domain.
8. The terminal of claim 6 , wherein the at least one of the uplink carriers is selected based on a priority.
9. A method performed by a base station for a random access procedure in unlicensed frequency bands, the method comprising:
transmitting, to a terminal, uplink synchronization command in subframe n for initiating the random access procedure, the uplink synchronization command including resource allocation information on uplink carriers associated with a timing advance group (TAG); and
receiving, from the terminal, a random access preamble in an idle subframe of an uplink resource after subframe n+k on at least one of the uplink carriers based on the resource allocation information, the k being a predetermined value.
10. The method of claim 9 , wherein the at least one uplink carrier belongs to one or more uplink carriers, a subframe of the uplink resource after subframe n+k of which is idle based on a clear channel assessment, CCA, detection to the subframe.
11. The method of claim 10 , wherein the idle subframe of the uplink resource is an idle subframe located at first in the uplink resource in a time domain.
12. The method of claim 10 , wherein the at least one of the uplink carriers is based on a priority.
13. A base station for a random access procedure in unlicensed frequency bands, comprising:
at least one module for transmitting and receiving a signal; and
a controller coupled with the at least one module and configured to control to:
transmit, to a terminal, uplink synchronization command in subframe n for initiating the random access procedure, the uplink synchronization command including resource allocation information on uplink carriers associated with a timing advance group (TAG), and
receive, from the terminal, a random access preamble in an idle subframe of an uplink resource after subframe n+k on at least one of the uplink carriers based on the resource allocation information, the k being a predetermined value.
14. The base station of claim 13 , wherein the at least one uplink carrier belongs to one or more uplink carriers, a subframe of the uplink resource after subframe n+k of which is idle based on a clear channel assessment, CCA, detection to the subframe.
15. The base station of claim 14 , wherein the idle subframe of the uplink resource is an idle subframe located at first in the uplink resource in a time domain.
16. The base station of claim 14 , wherein the at least one of the uplink carriers is based on a priority.