Mobile communication system and communication method

Abstract

A wireless communication system comprises a first base station, a second base station, and a wireless terminal. The wireless terminal performs a handover from the first base station to the second base station. The first base station transmits information related to data volume of downlink data to the second base station, when the handover is performed. The second base station receives information related to the data volume.

1 . A base station for communicating with a wireless terminal, said base station comprising:
 transmission means for transmitting information related to data volume of downlink data to a second base station, when said wireless terminal performs a handover from said base station to said second base station.   
   
   
       2 . The base station according to  claim 1 , wherein said downlink data is data transmitted from said base station to said wireless terminal. 
   
   
       3 . The base station according to  claim 1 , wherein said downlink data is data successfully transmitted from said base station to said wireless terminal. 
   
   
       4 . The base station according to  claim 1 , wherein the information includes time information on a time period in which said downlink data is transmitted. 
   
   
       5 . The base station according to  claim 1 , wherein said transmission means transmits the information by a message requesting a handover. 
   
   
       6 . The base station according to  claim 1 , comprising a second transmission means for transmitting a message indicating completion of resource release from said base station to said second base station, wherein
 said second transmission means transmits the information including the message indicating completion of said resource release, before said handover.   
   
   
       7 . The base station according to  claim 1 , wherein, after communication with said wireless terminal is completed, the information is transmitted to a core network as a message indicating completion of resource release. 
   
   
       8 . The base station according to  claim 1 , wherein the information is information on the number of packets of said downlink data. 
   
   
       9 . A wireless communication system comprising a first base station, a second base station, and a wireless terminal, wherein
 said wireless terminal performs a handover from said first base station to said second base station,   said first base station transmits information related to data volume of downlink data to said second base station, when said handover is performed, and   said second base station receives the information.   
   
   
       10 . The wireless communication system according to  claim 9 , wherein said downlink data is data transmitted from said first base station to said wireless terminal. 
   
   
       11 . The wireless communication system according to  claim 9 , wherein said downlink data is data successfully transmitted from said first base station to said wireless terminal. 
   
   
       12 . The wireless communication system according to  claim 9 , wherein the information includes time information on a time period in which said downlink data is transmitted. 
   
   
       13 . The wireless communication system according to  claim 9 , wherein said first base station transmits the information by a message requesting a handover. 
   
   
       14 . The wireless communication system according to  claim 9 , wherein said second base station transmits the information in a message indicating completion of a handover to a core network. 
   
   
       15 . The wireless communication system according to  claim 9 , wherein said first base station includes the information in a message indicating completion of said resource release, before said handover, and transmits to said second base station. 
   
   
       16 . The wireless communication system according to  claim 9 , wherein, after communication between said first base station and said wireless terminal is completed, the information is transmitted to a core network as a message indicating completion of resource release. 
   
   
       17 . The wireless communication system according to  claim 9 , wherein said second base station transmits the information in a message reporting handover completion to a core network. 
   
   
       18 . The wireless communication system according to  claim 9 , wherein,
 after transmission of a message requesting context information of a UE, to a first core network communicating with said first base station, from a second core network communicating with said second base station,   said first core network includes information related to data volume of uplink and downlink data summed up until then, as the information, in a message responding to a message requesting context information of a UE, and transmits to said second core network.   
   
   
       19 . The wireless communication system according to  claim 9 , wherein the information is information on the number of packets of said downlink data. 
   
   
       20 . A communication method of a base station with respect to a wireless terminal, comprising: performing, by said wireless terminal, a handover from said base station to a second base station; and
 transmitting information related to data volume of downlink data to a second base station, when said handover is performed.   
   
   
       21 - 27 . (canceled)