Communication terminal and base station

Abstract

When being connected to a macro cell (S-MeNB) and a small cell (SeNB), a user equipment device performs a pre-handover process of disconnecting the connection with the SeNB before a handover process of switching a macro cell connected with the UE from the macro cell (S-MeNB) that is a moving source to a macro cell (T-MeNB) that is a moving destination along with moving of the UE, and after the handover process, performs a post-handover process of reestablishing the connection with the SeNB.

1 . (canceled) 
     
     
         2 . A communication system comprising:
 a communication terminal; and   at least one base station that configures a plurality of cells for performing radio communication with the communication terminal,   wherein the plurality of cells include:
 a first cell; 
 a second cell that provides a first dual connectivity along with the first cell; and 
 a third cell that provides a second dual connectivity along with the first cell, and 
   the communication terminal is configured to keep a connection with the first cell while the communication terminal performs a handover from the second cell to the third cell for shifting from the first dual connectivity to the second dual connectivity.   
     
     
         3 . The communication system according to  claim 2 ,
 wherein a configuration of a bearer that has been configured using the first cell is not changed while the communication terminal performs the handover from the second cell to the third cell.   
     
     
         4 . A communication terminal that is used in a communication system comprising the communication terminal, and at least one base station that configures a plurality of cells for performing radio communication with the communication terminal,
 wherein the plurality of cells include:
 a first cell; 
 a second cell that provides a first dual connectivity along with the first cell; and 
 a third cell that provides a second dual connectivity along with the first cell, and 
   the communication terminal is configured to keep a connection with the first cell while the communication terminal performs a handover from the second cell to the third cell for shifting from the first dual connectivity to the second dual connectivity.   
     
     
         5 . A base station that is used in a communication system comprising a communication terminal, and at least one base station that configures a plurality of cells for performing radio communication with the communication terminal,
 wherein the plurality of cells include:
 a first cell; 
 a second cell that provides a first dual connectivity along with the first cell; and 
 a third cell that provides a second dual connectivity along with the first cell, 
   the first cell and the second cell are configured by the base station or another base station, and the third cell is configured by the base station, and   the base station is configured to:
 determine whether a configuration of a bearer that has been configured using the first cell can be handed over from the second cell in a case where the communication terminal performs a handover from the second cell to the third cell for shifting from the first dual connectivity to the second dual connectivity; and 
 decide to keep a connection between the communication terminal and the first cell during the handover when determining the configuration of the bearer can be handed over from the second cell.