Method and apparatus for beam tracking in a wireless communication system

A base station for updating a beam set of a UE (User Equipment) in a cell of a wireless communication system, wherein the base station applies beam-forming for transmission and/or reception in the cell and there are at least two beams in the cell, the base station comprising:

• a control circuit;
• a processor installed in the control circuit;
• and
• a memory installed in the control circuit and operatively coupled to the processor;
• wherein the processor is configured to execute a program code stored in the memory to:
• determine the beam set of the UE;
• monitor an uplink transmission from the UE via the beam set;
• send a signaling to the UE for triggering at least an aperiodic reference signal transmission if no DM RS (De-Modulation Reference Signal) associated with the uplink transmission is detected via at least one beam in the beam set;
• and
• update the beam set according to at least a beam or beams via which the aperiodic reference signal is received from the UE.

A method for transmitting signal for beam set detection by a UE (User Equipment) in a cell of a wireless communication system, wherein beam-forming is applied for transmission and/or reception in the cell and there are at least two beams in the cell, comprising:

• the UE transmits a first signal periodically for channel quality estimation in a cell;
• the UE transmits a second signal periodically for beam set detection;
• the UE receives a third signal from the base station;
• and
• the UE performs at least an aperiodic transmission of the second signal in response to reception of the third signal.