Apparatus and method for performing random access in beam-formed system
A method for performing a random access is provided. The method includes identifying a first downlink (DL) reception (RX) beam based on a measurement on a beam measurement signal, identifying a first uplink (UL) transmission (TX) beam corresponding to the identified first DL RX beam and transmitting at least one random access preamble for an RX sweeping at a base station, using the identified first UL TX beam based on a first power.
1. A method performed by a terminal in a wireless communication system, the method comprising:
transmitting, to a base station, a first random access preamble using a first transmission beam based on a first power;
identifying whether a random access response is received from the base station as a response to the first random access preamble;
in case that the random access response is not received, incrementing a power ramping counter and identifying a second transmission beam for transmitting a second random access preamble;
determining a second power for transmitting the second random access preamble, wherein:
in case that the second transmission beam is identical to the first transmission beam, the second power is determined based on the first power and the incremented power ramping counter, or
in case that the second transmission beam is different from the first transmission beam, the second power is determined based on an initial power value; and
transmitting, to the base station, the second random access preamble using the second transmission beam based on the determined second power,
wherein a maximum value of the power ramping counter is configured by the base station.
2. The method of claim 1 , wherein the power ramping counter is incremented, in case that the power ramping counter is less than the maximum value.
3. The method of claim 1 , further comprising:
selecting a first synchronization signal block (SSB) among at least one SSB based on signal strength of the first SSB being above a threshold,
wherein the first random access preamble is transmitted in a first physical random access channel (PRACH) occasion corresponding to the first SSB.
4. The method of claim 3 , further comprising:
receiving, from the base station, configuration information through a broadcast signaling or a dedicated signaling, the configuration information including information on PRACH occasions and information on association between the PRACH occasions and SSBs.
5. The method of claim 4 , wherein the first PRACH occasion corresponding to the first SSB is identified based on the configuration information.
6. The method of claim 1 , further comprising:
selecting a second SSB among at least one SSB based on signal strength of the second SSB being above a threshold,
wherein the second random access preamble is transmitted in a second PRACH occasion corresponding to the second SSB.
7. The method of claim 1 , wherein different SSBs correspond to different transmission beams, respectively.
8. A terminal in a wireless communication system, the terminal comprising:
a transceiver; and
at least one processor configured to:
transmit, to a base station via the transceiver, a first random access preamble using a first transmission beam based on a first power,
identify whether a random access response is received from the base station as a response to the first random access preamble,
in case that the random access response is not received, increment a power ramping counter and identify a second transmission beam for transmitting a second random access preamble,
determining a second power for transmitting the second random access preamble, wherein:
in case that the second transmission beam is identical to the first transmission beam, the second power is determined based on the first power and the incremented power ramping counter, or
in case that the second transmission beam is different from the first transmission beam, the second power is determined based on an initial power value, and
transmit, to the base station via the transceiver, the second random access preamble using the second transmission beam based on the determined second power,
wherein a maximum value of the power ramping counter is configured by the base station.
9. The terminal of claim 8 , wherein the power ramping counter is incremented, in case that the power ramping counter is less than the maximum value.
10. The terminal of claim 8 , wherein the at least one processor is further configured to:
select a first synchronization signal block (SSB) among at least one SSB based on signal strength of the first SSB being above a threshold, and
transmit the first random access preamble in a first physical random access channel (PRACH) occasion corresponding to the first SSB.
11. The terminal of claim 10 , wherein the at least one processor is further configured to receive, from the base station via the transceiver, configuration information though a broadcast signaling or a dedicated signaling, the configuration information including information on PRACH occasions and information on association between the PRACH occasions and SSBs.
12. The terminal of claim 11 , wherein the at least one processor is further configured to identify the first PRACH occasion corresponding to the first SSB based on the configuration information.
13. The terminal of claim 8 , wherein the at least one processor is further configured to:
select second SSB among at least one SSB based on signal strength of the second SSB being above a threshold, and
transmit the second random access preamble in a second PRACH occasion corresponding to the second SSB.
14. The terminal of claim 8 , wherein different SSBs correspond to different transmission beams, respectively.