Method and apparatus for performing contention based random access procedure over contention free random access procedure in wireless communication system
AssigneeLG Electronics Inc.
InventorsYoungdae Lee, Seungjune Yi, Sangwon Kim, Sunyoung Lee
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Abstract
A method and apparatus for performing a random access procedure in a wireless communication system is provided. A user equipment (UE) performs a contention free random access procedure on a first frequency, detects a failure of the contention free random access procedure, and performs a contention based random access procedure. When the first frequency is occupied by other media as a result of listen-before-talk (LBT) operation, the contention based random access procedure may be performed on a second frequency.
Claims11
A method performed by a user equipment (UE) in a wireless communication system, the method comprising:
- receiving a physical downlink control channel (PDCCH) order related to a dedicated random access preamble for a contention free random access procedure from a network on a first downlink component carrier (DL CC) of a first frequency;
- transmitting the dedicated random access preamble for the contention free random access procedure to the network on a first uplink component carrier (UL CC) linked to the first DL CC;
- starting a timer related to the contention free random access procedure;
- performing a listen-before-talk (LBT) operation, while the timer is running;
- detecting that the first UL CC is occupied by other media and that a second UL CC is not occupied as a result of the LBT operation;
- re-transmitting the dedicated random access preamble for the contention free random access procedure on the first UL CC with power ramping, until the timer related to the contention free random access procedure expires, in response to detecting that the first UL CC is occupied by other media;
- and
- initiating a contention based random access procedure on the second UL CC in response to detecting that the second UL CC is not occupied, when the timer related to the contention free random access procedure expires,
- wherein the timer is configured per unlicensed cell or per UL CC.
A user equipment (UE) in a wireless communication system, the UE comprising:
- a memory;
- a transceiver;
- and a processor coupled to the memory and the transceiver, wherein the processor is configured to:
- control the transceiver to receive a physical downlink control channel (PDCCH) order related to a dedicated random access preamble for a contention free random access procedure from a network on a first downlink component carrier (DL CC) of a first frequency;
- control the transceiver to transmit the dedicated random access preamble for the contention free random access procedure to the network on a first uplink component carrier (UL CC) linked to the first DL CC;
- start a timer related to the contention free random access procedure;
- perform a listen-before-talk (LBT) operation, while the timer is running;
- detect that the first UL CC is occupied by other media and that a second UL CC is not occupied as a result of the LBT operation;
- control the transceiver to re-transmit the dedicated random access preamble for the contention free random access procedure on the first UL CC with power ramping, until the timer related to the contention free random access procedure expires, in response to detecting that the first UL CC is occupied by other media;
- and
- initiate a contention based random access procedure on the second UL CC in response to detecting that the second UL CC is not occupied, when the timer related to the contention free random access procedure expires,
- wherein the timer is configured per unlicensed cell or per UL CC.
Dependencies are inferred from the claim text.