Method and apparatus for uplink synchronization according to beam switching in communication network

A method of a base station, comprising:

• transmitting, through a serving beam, a physical downlink control channel (PDCCH) order including information on a target beam for a beam switching operation of a terminal to the terminal;
• receiving, through the target beam, a random access channel (RACH) preamble based on the PDCCH order from the terminal;
• measuring a timing advance (TA) value for the target beam based on the RACH preamble;
• transmitting TA information including the TA value to the terminal through the serving beam;
• and
• transmitting, through the serving beam, beam switching indication information for switching from the serving beam to the target beam to the terminal, based on determination of whether the beam switching operation of the terminal is to be performed.

A terminal comprising at least one processor, wherein the at least one processor causes the terminal to perform:

• receiving, through a serving beam, a physical downlink control channel (PDCCH) order including information on a target beam from a base station;
• transmitting, based on the PDCCH order, a random access channel (RACH) preamble to the base station through the target beam;
• receiving, through the serving beam, timing advance (TA) information for the target beam from the base station, the TA information being determined based on the RACH preamble;
• receiving, through the serving beam, beam switching indication information from the base station;
• performing a beam switching operation from the serving beam to the target beam based on the beam switching indication information, using the TA information;
• and
• acquiring uplink synchronization for the target beam based on the TA information.