Method and apparatus for monitoring radio link in wireless communication system

Abstract

A method of performing a radio link monitoring (RLM) by a terminal in a wireless communication system is provided. The method includes receiving RLM configuration information from a base station; identifying an RLM measurement time window, at least one position of a radio link monitoring-reference signal (RLM-RS) on the RLM measurement time window and a type of the RLM-RS for an out-of-synchronization (OOS) evaluation and an in-synchronization (IS) evaluation based on the RLM configuration information; detecting at least one reference signal on the at least one identified position on the RLM measurement window; and performing the OOS evaluation or the IS evaluation by using the detected at least one reference signal based on the identified RLM measurement time window and the identified type of the reference signal.

What is claimed is: 
     
         1 . A method of performing a radio link monitoring (RLM), by a terminal in a wireless communication system, the method comprising:
 receiving RLM configuration information from a base station;   identifying an RLM measurement time window, at least one position of a radio link monitoring-reference signal (RLM-RS) on the RLM measurement time window and a type of the RLM-RS for an out-of-synchronization ( 00 S) evaluation and an in-synchronization (IS) evaluation based on the RLM configuration information;   detecting at least one reference signal on the at least one identified position on the RLM measurement window; and   performing the OOS evaluation or the IS evaluation by using the detected at least one reference signal based on the identified RLM measurement time window and the identified type of the reference signal.   
     
     
         2 . The method of  claim 1 , wherein identifying the RLM measurement time window, the at least one position of the RLM-RS and the type of the reference signal comprises identifying which RLM-RS within or outside the RLM measurement time window is utilized for the OOS evaluation and the IS evaluation. 
     
     
         3 . The method of  claim 1 , wherein
 detecting the at least one reference signal comprises detecting a plurality of synchronization signal blocks (SSBs) in the RLM measurement time window or a channel state information-reference signal (CSI-RS) out of the RLM measurement window as the at least one reference signal, and   performing the OOS evaluation or the IS evaluation comprises:   
       performing the OOS evaluation based on the plurality of SSBs detected in the RLM measurement time window; and 
       performing the IS evaluation based on the plurality of SSBs detected in the RLM measurement time window or the CSI-RS detected out of the RLM measurement time window. 
     
     
         4 . The method of  claim 1 , wherein detecting the at least one reference signal comprises detecting a plurality of synchronization signal blocks (SSBs) as the at least one reference signal in the RLM measurement time window, and identifying at least one valid SSB among the plurality of SSBs. 
     
     
         5 . The method of  claim 1 , wherein performing the OOS evaluation or the IS evaluation comprises:
 identifying a first threshold value for the OOS evaluation and a second threshold value for the IS evaluation based on the RLM configuration information; and   performing the OOS evaluation based on the first threshold or the IS evaluation based on the second threshold.   
     
     
         6 . A method of performing a radio link monitoring (RLM), by a base station in a wireless communication system, the method comprising:
 obtaining RLM configuration information including information regarding an RLM measurement time window and a type of a reference signal for an out-of-synchronization (OOS) evaluation and an in-synchronization (IS) evaluation;   transmitting the RLM configuration information; and   receiving an indication regarding an occurrence of OOS or IS, in response to an OOS evaluation or an IS evaluation being performed based on the RLM configuration information at a terminal.   
     
     
         7 . The method of  claim 6 , wherein the RLM configuration information indicates which RLM-RS within or outside the RLM measurement time window is utilized for the OOS evaluation and the IS evaluation. 
     
     
         8 . The method of  claim 6 , wherein
 a plurality of synchronization signal blocks (SSBs) are detected, at the terminal, as the reference signal in the RLM measurement time window, and   the OOS evaluation is performed based on the plurality of SSBs received in the RLM measurement time window.   
     
     
         9 . A terminal for performing a radio link monitoring (RLM) in a wireless communication system, the terminal comprising:
 a transceiver; and   a processor coupled with the transceiver and configured to:   control the transceiver to receive RLM configuration information from a base station,   identify an RLM measurement time window, at least one position of a radio link monitoring-reference signal (RLM-RS) on the RLM measurement time window and a type of the RLM-RS for an out-of-synchronization (OOS) evaluation and an in-synchronization (IS) evaluation based on the RLM configuration information,   detect at least one reference signal on the at least one identified position on the RLM measurement window, and   perform the OOS evaluation or the IS evaluation by using the detected at least one reference signal based on the identified RLM measurement time window and the identified type of the reference signal.   
     
     
         10 . The terminal of  claim 9 , wherein the processor is further configured to identify which RLM-RS within or outside the RLM measurement time window is utilized for the OOS evaluation and the IS evaluation. 
     
     
         11 . The terminal of  claim 9 , wherein
 the processor is further configured to detect a plurality of synchronization signal blocks (SSBs) in the RLM measurement time window or a channel state information-reference signal (CSI-RS) out of the RLM measurement window as the at least one reference signal, perform the OOS evaluation based on the plurality of SSBs detected in the RLM measurement time window, and perform the IS evaluation based on the plurality of SSBs detected in the RLM measurement time window or the CSI-RS detected out of the RLM measurement time window.   
     
     
         12 . The terminal of  claim 9 , wherein the processor is further configured to:
 detect a plurality of synchronization signal blocks (SSBs) as the at least one reference signal in the RLM measurement time window, and   identify at least one valid SSB among the plurality of SSBs.   
     
     
         13 . The terminal of  claim 9 , wherein the processor is further configured to:
 identify a first threshold value for the OOS evaluation and a second threshold value for the IS evaluation based on the RLM configuration information, and   perform the OOS evaluation based on the first threshold or the IS evaluation based on the second threshold.   
     
     
         14 . A base station for performing a radio link monitoring (RLM) in a wireless communication system, the base station comprising:
 a transceiver; and   a processor coupled with the transceiver and configured to:   obtain RLM configuration information including information regarding an RLM measurement time window and a type of a reference signal for an out-of-synchronization (OOS) evaluation and an in-synchronization (IS) evaluation; and   control the transceiver to transmit the RLM configuration information and receive an indication regarding an occurrence of OOS or IS, in response to an OOS evaluation or an IS evaluation being performed based on the RLM configuration information at a terminal.   
     
     
         15 . The base station of  claim 14 , wherein the RLM configuration information indicates which RLM-RS within or outside the RLM measurement time window is utilized for the OOS evaluation and the IS evaluation.