Wireless communication system, mobile station, base station, and wireless communication method

1. A base station configured to communicate data with a mobile station, comprising:

a controller;

a communicator configured to transmit data to the mobile station;

a transmitter configured to transfer a portion of data to be transmitted to the mobile station to another wireless communication apparatus; and

a receiver configured to receive, from the mobile station, a PDCP status report on information indicating a state of a buffer of the mobile station from the mobile station, wherein

the receiver configured to transmit the received PDCP status report to the controller, and

the controller configured to notify the mobile station of a parameter setting for the PDCP status report, and

the parameter setting for the PDCP status report includes a parameter to determine whether to send the PDCP status report,

the PDCP status report includes a first missing sequence number representing a sequence number of the oldest packet among packets that have not arrived for the other wireless communication apparatus, and

a size of the first missing sequence number has a plurality of sequence lengths.

2. The base station according to claim 1 , wherein the PDCP status report further includes information indicating an arrival state of packets following the packet corresponding to the sequence number.

3. The base station according to claim 1 , the controller further configured to:

confirm packets accumulated in the buffer of the mobile station and the packets that have not arrived from the other wireless communication apparatus; and

calculate a delivery amount of user data to be transmitted from the base station to the other wireless communication apparatus by using the retention amount of data in the buffer of the mobile station.

4. The base station according to claim 3 , wherein the controller further configured to:

stop transmission of user data to the other wireless communication apparatus in response to information indicating the retention amount of data in the buffer of the mobile station, the information being transmitted from the mobile station, when the retention amount of data accumulated in the buffer of the mobile station exceeds the threshold; and

resume the transmission of user data to the other wireless communication apparatus upon confirming that the retention amount of data in the buffer of the mobile station is zero.

5. The base station according to claim 1 , wherein

one of the sequence length of the first missing sequence number is either of 7 bit length, 12 bit length or 15 bit length.

6. A mobile station comprising:

a communicator configured to perform multiple communications with a first wireless communication apparatus and a second wireless communication apparatus ( 200 ) to which data is transferred from the first wireless communication apparatus; and

a transmitter configured to transmit, to the first wireless communication apparatus, a PDCP status report on information indicating a state of a buffer of the mobile station, wherein the first wireless communication apparatus notifies the mobile station of a parameter setting for the PDCP status report,

wherein

the parameter setting for the PDCP status report includes a parameter to determine whether to send the PDCP status report,

the PDCP status report includes a first missing sequence number representing a sequence number of the oldest packet among packets that have not arrived for the another wireless communication apparatus and

a size of the first missing sequence number has a plurality of sequence lengths.

7. The mobile station according to claim 6 , wherein the PDCP status report further includes information indicating an arrival state of packets following the packet corresponding to the sequence number.

8. The mobile station according to claim 6 , wherein

one of the sequence length of the first missing sequence number is either of 7 bit length, 12 bit length or 15 bit length.