Method and user equipment for transmitting random access signals, and method and base station for receiving random access signals
Disclosed herein are a method and apparatus for transmitting/receiving random access signals. A first random access channel (RACH) resource for a first RACH preamble format and a second RACH resource for a second RACH preamble format are configured, separately. The first RACH resource and the second RACH resource are for a UE at which Tx/Rx beam correspondence holds and for a UE at which Tx/Rx beam correspondence does not hold, respectively. A UE can use the first or second RACH resource, depending on whether or not Tx/Rx beam correspondence holds at the UE.
1. A method for transmitting, by a user equipment (UE), random access signals, the method comprising:
receiving, by the UE from a base station (BS), configuration information of a first random access channel (RACH) resource for a first RACH preamble format and configuration information of a second RACH resource for a second RACH preamble format; and
transmitting, by the UE to the BS, a physical RACH (PRACH) with the first RACH preamble format on the first RACH resource or with the second RACH preamble format on the second RACH resource,
wherein the UE transmits the PRACH with the first RACH preamble format on the first RACH resource if transmission (Tx) and reception (Rx) (Tx/Rx) beam correspondence holds at the UE, and the UE transmits the PRACH with second RACH preamble format on the second RACH resource if Tx/Rx beam correspondence does not hold at the UE,
wherein if the Tx/Rx beam correspondence does not hold at the UE and holds at the BS, the UE transmits the PRACH with the second RACH preamble format by changing Tx beam directions of the UE on the second RACH resource in a form of repetition of a cyclic prefix (CP) and a preamble sequence and a guard time (GT), and
wherein if the Tx/Rx beam correspondence does not hold at both the UE and the BS, the UE transmits the PRACH with the second RACH preamble format by changing Tx beam directions of the UE on the second RACH resource in a form of the CP and repetition of the preamble sequence and the GT.
2. The method according to claim 1 , wherein the UE transmits the PRACH with the first RACH preamble format on the first RACH resource one time before a random access response (RAR) window if the Tx/Rx beam correspondence holds at the UE.
3. A user equipment (UE) for transmitting random access signals, the UE comprising:
a radio frequency (RF) unit, and
a processor configured to control the RF unit,
wherein the processor is further configured to:
control the RF unit to receive, from a base station (BS), configuration information of a first random access channel (RACH) resource for a first RACH preamble format and configuration information of a second RACH resource for a second RACH preamble format; and
control the RF unit to transmit, to the BS, a physical RACH (PRACH) with the first RACH preamble format on the first RACH resource or with the second RACH preamble format on the second RACH resource,
wherein the processor is configured to control the RF unit to transmit the PRACH with the first RACH preamble format on the first RACH resource if transmission (Tx) and reception (Rx) (Tx/Rx) beam correspondence holds at the UE, and the processor is configured to control the RF unit to transmit the PRACH with second RACH preamble format on the second RACH resource if the Tx/Rx beam correspondence does not hold at the UE,
wherein if the Tx/Rx beam correspondence does not hold at the UE and holds at the BS, the processor is configured to control the RF unit to transmit the PRACH with the second RACH preamble format by changing Tx beam directions of the UE on the second RACH resource in a form of repetition of a cyclic prefix (CP) and a preamble sequence and a guard time (GT), and
wherein if the Tx/Rx beam correspondence does not hold at both the UE and the BS, the processor is configured to control the RF unit to transmit the PRACH with the second RACH preamble format by changing Tx beam directions of the UE on the second RACH resource in a form of the CP and repetition of the preamble sequence and the GT.
4. The UE according to claim 3 , wherein the processor is configured to control the RF unit to transmit the PRACH with the first RACH preamble format on the first RACH resource one time before a random access response (RAR) window if the Tx/Rx beam correspondence holds at the UE.