Method and apparatus of preventing bandwidth part misalignment in a wireless communication system

Abstract

A method and apparatus are disclosed from the perspective of a UE (User Equipment). In one embodiment, the method includes transmitting a Scheduling Request (SR) on a first uplink bandwidth part (BWP). The method further includes receiving a response for the SR on a first downlink BWP. The method also includes detecting a beam failure when using the first uplink BWP and the first downlink BWP. In addition, the method includes transmitting a beam failure recovery (BFR) request to a network node on the first uplink BWP. Furthermore, the method includes receiving a control signalling on a second downlink BWP from the network node after transmitting the BFR request, wherein the control signalling is a response for the BFR request and the second downlink BWP is associated with the first uplink BWP.

1 . A method for a UE (User Equipment), comprising:
 transmitting, to a network node, a beam failure recovery (BFR) request on a first uplink bandwidth part (BWP), wherein the transmitting comprises indicating, to the network node, information of an active downlink BWP of a cell, wherein each BWP of the first uplink BWP and the active downlink BWP is associated with a specific numerology; and   receiving, from the network node, a response to the BFR request on a specific downlink BWP, wherein the specific downlink BWP is associated with the first uplink BWP and the specific downlink BWP is the active downlink BWP of the cell when receiving the response to the BFR request.   
     
     
         2 . The method of  claim 1 , further comprising:
 detecting a beam failure on the cell, wherein the transmitting the BFR request is performed in response to the beam failure.   
     
     
         3 . The method of  claim 1 , wherein the specific downlink BWP is a first downlink BWP if the first downlink BWP is associated with the first uplink BWP, and the specific downlink BWP is a second downlink BWP if the first downlink BWP is not associated with the first uplink BWP. 
     
     
         4 . The method of  claim 2 , further comprising:
 in response to detecting the beam failure, at least one of:
 before transmitting the BFR request, identifying a new candidate beam based on downlink reference signals received on the cell; or 
 changing the active downlink BWP of the cell from a first downlink BWP to a second downlink BWP if the first downlink BWP is not associated with the first uplink BWP. 
   
     
     
         5 . The method of  claim 1 , wherein the association of the specific downlink BWP with the first uplink BWP is:
 at least one of defined in a specification or configured by the network node.   
     
     
         6 . The method of  claim 1 , wherein the information of the active downlink BWP is derived based on the transmitting the BFR request on the first uplink BWP and the association of the specific downlink BWP with the first uplink BWP. 
     
     
         7 . The method of  claim 2 , wherein in response to detecting the beam failure, the UE does not change an active uplink BWP from a first uplink BWP to a second uplink BWP. 
     
     
         8 . The method of  claim 1 , further comprising:
 before transmitting the BFR request, changing the active downlink BWP of the cell.   
     
     
         9 . The method of  claim 2 , wherein the beam failure is detected based on quality of beam. 
     
     
         10 . The method of  claim 1 , wherein the BFR request is transmitted on Physical Random Access Channel (PRACH) of the cell. 
     
     
         11 . A User Equipment (UE), 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:
 transmit, to a network node, a beam failure recovery (BFR) request on a first uplink bandwidth part (BWP), wherein the transmitting comprises indicating, to the network node, information of an active downlink BWP of a cell, wherein each BWP of the first uplink BWP and the active downlink BWP is associated with a specific numerology; and 
 receive, from the network node, a response to the BFR request on a specific downlink BWP, wherein the specific downlink BWP is associated with the first uplink BWP and the specific downlink BWP is the active downlink BWP of the cell when receiving the response to the BFR request. 
   
     
     
         12 . The UE of  claim 11 , wherein the processor is further configured to execute the program code stored in the memory to:
 detect a beam failure on the cell, wherein the transmitting the BFR request is performed in response to the beam failure.   
     
     
         13 . The UE of  claim 11 , wherein the specific downlink BWP is a first downlink BWP if the first downlink BWP is associated with the first uplink BWP, and the specific downlink BWP is a second downlink BWP if the first downlink BWP is not associated with the first uplink BWP. 
     
     
         14 . The UE of  claim 12 , wherein the processor is further configured to execute the program code stored in the memory to:
 in response to detecting the beam failure, at least one of:
 before transmitting the BFR request, identify a new candidate beam based on downlink reference signals received on the cell; or 
 change the active downlink BWP of the cell from a first downlink BWP to a second downlink BWP if the first downlink BWP is not associated with the first uplink BWP. 
   
     
     
         15 . The UE of  claim 11 , wherein the association of the specific downlink BWP with the first uplink BWP is:
 at least one of defined in a specification or configured by the network node.   
     
     
         16 . The UE of  claim 11 , wherein the information of the active downlink BWP is derived based on the transmitting the BFR request on the first uplink BWP and the association of the specific downlink BWP with the first uplink BWP. 
     
     
         17 . The UE of  claim 12 , wherein in response to detecting the beam failure, the UE does not change an active uplink BWP from a first uplink BWP to a second uplink BWP. 
     
     
         18 . The UE of  claim 11 , wherein the processor is further configured to execute the program code stored in the memory to:
 before transmitting the BFR request, change the active downlink BWP of the cell.   
     
     
         19 . The UE of  claim 12 , wherein the beam failure is detected based on quality of beam. 
     
     
         20 . The UE of  claim 11 , wherein the BFR request is transmitted on Physical Random Access Channel (PRACH) of the cell.