Radio communication system, base station apparatus, radio terminal, and communication control method

Abstract

A radio communication system includes a first base station ( 11 ) that manages a first cell ( 110 ), a second base station ( 12 ) that manages a second cell ( 120 ), and a radio terminal ( 2 ). The radio terminal ( 2 ) supports dual connectivity involving a bearer split in which a first network bearer between the radio terminal ( 2 ) and a core network ( 3 ) is split over the first base station ( 11 ) and the second base station ( 12 ). The first base station ( 11 ) receives, from the second base station ( 12 ), bearer split status information about communication of the first network bearer in the second base station ( 12 ), and performs control of an access stratum related to the first network bearer. It is thus possible to contribute, for example, to an improvement in control of an access stratum when dual connectivity involving a bearer split is performed.

1 - 43 . (canceled) 
     
     
         44 . A first radio station, comprising:
 a memory storing instructions; and   at least one processor configured to process the instructions to:
 serve a first cell; 
 control a radio terminal to cause the radio terminal to perform dual connectivity using the first cell and a second cell served by a second radio station; 
 receive a first Power Headroom on the first cell and a second Power Headroom on the second cell from at least the radio terminal; and 
 transmit the first Power Headroom on the first cell and the second Power Headroom on the second cell to at least the second radio station. 
   
     
     
         45 . A second radio station, comprising:
 a memory storing instructions; and   at least one processor configured to process the instructions to:
 serve a second cell; 
 communicate with a radio terminal configured to perform dual connectivity using a first cell served by a first radio station and the second cell; and 
 receive a first Power Headroom on the first cell and a second Power Headroom from at least the first radio station. 
   
     
     
         46 . A radio communication system comprising:
 a first radio station configured to serve a first cell;   a second radio station configured to serve a second cell; and   a radio terminal configured to perform dual connectivity using the first cell and the second cell, wherein
 the radio terminal is configured to transmit a first Power Headroom on the first cell and a second Power Headroom on the second cell to at least the first radio station, and 
 the first radio station is configured to transmit the first Power Headroom on the first cell and the second Power Headroom on the second cell to at least the second radio station. 
   
     
     
         47 . A control method for a first radio station, comprising:
 serving a first cell;   controlling a radio terminal to cause the radio terminal to perform dual connectivity using the first cell and a second cell served by a second radio station;   receiving a first Power Headroom on the first cell and a second Power Headroom on the second cell from at least the radio terminal; and   transmitting the first Power Headroom on the first cell and the second Power Headroom on the second cell to at least the second radio station.   
     
     
         48 . A control method for a second radio station, comprising:
 serving a second cell;   communicating with a radio terminal configured to perform dual connectivity using the first cell and a second cell served by a second radio station; and   receiving a first Power Headroom on the first cell and a second Power Headroom on the second cell from at least the first radio station.