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

1. A wireless terminal of a wireless communication system, the wireless communication system including a wireless base station and one or more wireless terminals, the wireless terminal comprising:

a radio communication circuit configured to perform wireless communication with the wireless base station; and

a controller configured to:

allocate a part of an allocation amount of a wireless resource indicated in an uplink grant which is assigned according to a status report of a transmission buffer to transmission of an updated status report of the transmission buffer when the uplink grant is received from the wireless base station,

transmit the updated status report and uplink data stored in the transmission buffer via the radio communication circuit, the updated status report being a status report according to a variation amount of uplink data stored in the transmission buffer after transmitting the updated status report, the variation amount reflecting an actual amount of uplink data currently stored in the transmission buffer after transmitting the updated status report, wherein the actual amount of uplink data currently stored in the transmission buffer reflects at least one of: an amount data added to the transmission buffer after transmitting the status report, an amount of data discarded from the transmission buffer after transmitting the status report, and a difference between an amount of transmission buffer data transmitted according to the uplink grant and an amount of transmission buffer data stored in the transmission buffer prior to transmitting the uplink data stored in the transmission buffer, taken alone or in any combination.

2. The wireless terminal according to claim 1 , further comprising:

a memory configured to store a conversion table having a plurality of small ranges into which a range from a lower limit value of the transmission buffer to an upper limit value of the transmission buffer is divided, and indexes corresponding to the respective small ranges, wherein the controller is configured to:

specify the small range corresponding to an amount of data staying in the transmission buffer according to the conversion table,

acquire the index corresponding to the specified small range, and

store the index into the status report of the transmission buffer.

3. The wireless terminal according to claim 1 , wherein the controller is configured to:

allocate a part of the allocation amount of the wireless resource indicated in the uplink grant to transmission of the status report of the transmission buffer in a case where a status of the transmission buffer satisfies a predetermined condition, and

not allocate a part of the allocation amount of the wireless resource indicated in the uplink grant to transmission of the status report of the transmission buffer in a case where a status of the transmission buffer does not satisfy the predetermined condition.

4. The wireless terminal according to claim 3 , wherein the controller is configured to receive the predetermined condition from the wireless base station via using the radio communication circuit.

5. A wireless base station of a wireless communication system, the wireless communication system including a wireless base station and one or more wireless terminals, the wireless base station comprising:

a radio communication circuit configured to perform wireless communication with at least one wireless terminal; and

a controller configured to transmit, to the at least one wireless terminal via the radio communication circuit, an uplink grant indicating an allocation amount of a wireless resource allocated to the at least one wireless terminal, the uplink grant being assigned according to a status report of a transmission buffer of the at least one wireless terminal,

wherein the controller is configured to:

transmit the uplink grant to the at least one wireless terminal, and

receive an updated status report of the transmission buffer of the at least one wireless terminal via the radio communication circuit, the updated status report transmitted from the at least one wireless terminal using a part of the allocation amount of the wireless resource, the updated status report being a status report according to a variation amount of uplink data stored in the transmission buffer of the at least one wireless terminal after the at least one wireless terminal transmits the updated status report, the variation amount reflecting an actual amount of uplink data currently stored in the transmission buffer after the at least one wireless terminal transmits the updated status report, wherein the actual amount of uplink data currently stored in the transmission buffer reflects at least one of: an amount data added to the transmission buffer after transmitting the status report, an amount of data discarded from the transmission buffer after transmitting the status report, and a difference between an amount of transmission buffer data transmitted according to the uplink grant and an amount of transmission buffer data stored in the transmission buffer prior to transmitting the uplink data stored in the transmission buffer, taken alone or in any combination.

6. A wireless communication system comprising:

a wireless base station; and

at least one wireless terminal,

wherein the at least one wireless terminal includes:

a first radio communication circuit configured to perform wireless communication with the wireless base station, and

a first controller configured to:

allocate a part of an allocation amount of a wireless resource indicated in an uplink grant which is assigned according to a status report of a transmission buffer to transmission of an updated status report of the transmission buffer when the uplink grant is received from the wireless base station, and

transmit the updated status report and uplink data stored in the transmission buffer via the radio communication circuit, the updated status report being a status report according to a variation amount of uplink data stored in the transmission buffer after transmitting the updated status report, the variation amount reflecting an actual amount of uplink data currently stored in the transmission buffer after transmitting the updated status report, wherein the actual amount of uplink data currently stored in the transmission buffer reflects at least one of: an amount data added to the transmission buffer after transmitting the status report, an amount of data discarded from the transmission buffer after transmitting the status report, and a difference between an amount of transmission buffer data transmitted according to the uplink grant and an amount of transmission buffer data stored in the transmission buffer prior to transmitting the uplink data stored in the transmission buffer, taken alone or in any combination, and

wherein the wireless base station includes:

a second radio communication circuit configured to perform wireless communication with the at least one wireless terminal, and

a second controller configured to:

transmit the uplink grant indicating an allocation amount of a wireless resource allocated to the at least one wireless terminal through scheduling of the wireless resource,

acquire the updated status report of the transmission buffer from an uplink signal received from the at least one wireless terminal in response to transmission of the uplink grant, and

acquire a buffer estimation amount of the at least one wireless terminal based on the acquired updated status report.

7. The wireless communication system according to claim 6 ,

wherein the at least one wireless terminal further includes a memory configured to store a conversion table having a plurality of small ranges into which a range from a lower limit value of the transmission buffer to an upper limit value of the transmission buffer is divided, and indexes corresponding to the respective small ranges,

wherein the first controller included in the at least one wireless terminal is configured to:

specify the small range corresponding to an amount of data staying in the transmission buffer according to the conversion table,

acquire the index corresponding to the specified small range, and

store the index in the updated status report.

8. The wireless communication system according to claim 6 ,

wherein the first controller included in the at least one wireless terminal is configured to:

allocate a part of the allocation amount of the wireless resource indicated in the uplink grant to transmission of the status report of the transmission buffer in a case where a status of the transmission buffer satisfies a predetermined condition, and

not allocate a part of the allocation amount of the wireless resource indicated in the uplink grant to transmission of the status report of the transmission buffer in a case where a status of the transmission buffer does not satisfy the predetermined condition.

9. The wireless communication system according to claim 8 ,

wherein the second controller included in the wireless base station is configured to transmit the predetermined condition to the at least one wireless terminal via the second radio communication circuit, and

wherein the first controller included in the at least one wireless terminal is configured to receive the predetermined condition from the wireless base station via the first radio communication circuit.

10. A wireless communication method implemented by a wireless terminal of a wireless communication system, the wireless communication system including a wireless base station and one or more wireless terminals, the wireless communication method comprising:

receiving an uplink grant which is assigned according to a status report of a transmission buffer from the wireless base station; and

allocating a part of an allocation amount of a wireless resource indicated in the uplink grant to transmission of an updated status report of the transmission buffer when uplink data stored in the transmission buffer is transmitted according to the uplink grant, the updated status report being a status report according to a variation amount of uplink data stored in the transmission buffer after transmitting the updated status report, the variation amount reflecting an actual amount of uplink data currently stored in the transmission buffer after transmitting the updated status report, wherein the actual amount of uplink data currently stored in the transmission buffer reflects at least one of: an amount data added to the transmission buffer after transmitting the status report, an amount of data discarded from the transmission buffer after transmitting the status report, and a difference between an amount of transmission buffer data transmitted according to the uplink grant and an amount of transmission buffer data stored in the transmission buffer prior to transmitting the uplink data stored in the transmission buffer, taken alone or in any combination.

11. The wireless communication method according to claim 10 , further comprising:

specifying a small range corresponding to an amount of data staying in the transmission buffer according to a conversion table having a plurality of small ranges into which a range from a lower limit value of the transmission buffer to an upper limit value of the transmission buffer is divided, and indexes corresponding to the respective small ranges;

acquiring the index corresponding to the specified small range according to the conversion table; and

storing the index into the status report of the transmission buffer.

12. The wireless communication method according to claim 10 , wherein the allocating is configured to:

allocate a part of the allocation amount of the wireless resource indicated in the uplink grant to transmission of the status report of the transmission buffer in a case where a status of the transmission buffer satisfies a predetermined condition, and

not allocate a part of the allocation amount of the wireless resource indicated in the uplink grant to transmission of the status report of the transmission buffer in a case where a status of the transmission buffer does not satisfy the predetermined condition.

13. The wireless communication method according to claim 12 , wherein the allocating includes receiving the predetermined condition from the wireless base station.