Wireless communication apparatus and wireless communication system

1. A first wireless communication apparatus comprising:

controller circuitry configured to, in the first wireless communication apparatus that is different from a second wireless communication apparatus:

perform numbering of multiple pieces of data;

control to transmit the multiple pieces of data that are numbered by the first wireless communication apparatus, to the second wireless communication apparatus; and

structure a Medium Access Control protocol data unit (MAC-PDU), in response to specific data among the multiple pieces of data being discarded by the first wireless communication apparatus after the numbering by the first wireless communication apparatus and before transmission, by the first wireless communication apparatus, of the structured MAC-PDU,

the structuring of the MAC-PDU by the first wireless communication apparatus being performed without renumbering, by the first wireless communication apparatus, of the multiple pieces of data subsequent to the discarding by the first wireless communication apparatus,

the structured MAC-PDU including:

the multiple pieces of data subsequent to the discarding by the first wireless communication apparatus, the multiple pieces of data in the structured MAC-PDU having not been transmitted by the first wireless communication apparatus to the second wireless communication apparatus, after the numbering of the multiple pieces of data; and

discarding notification information indicating that the specific data have been discarded by the first wireless communication apparatus; and

a transmitter configured to:

in a state where a missing number occurs as a result of the numbering that depends on the discarding by the first wireless communication apparatus, transmit the structured MAC-PDU from the first wireless communication apparatus to the second wireless communication apparatus, the multiple pieces of data subsequent to the discarding, and the discarding notification information being included in the same transmitted MAC-PDU.

2. The first wireless communication apparatus according to claim 1 , wherein the controller circuitry performs numbering of the multiple pieces of data corresponding to a plurality of protocol layers or sublayers, and performs a first processing in a case where, among the multiple pieces of data, a specific data set in at least one protocol layer or sublayer is discarded after the numbering and before transmitting the multiple pieces of data.

3. The first wireless communication apparatus according to claim 1 , wherein the discarding notification information is included in a Medium Access Control (MAC) Control Element (CE).

4. The first wireless communication apparatus according to claim 2 , wherein the plurality of protocol layers or sublayers include is at least one of: a Packet Data Convergence Protocol (PDCP) layer; a Radio Link Control (RLC) layer; and a Medium Access Control (MAC) layer.

5. The first wireless communication apparatus according to claim 2 , wherein the multiple pieces of data corresponding to each of the plurality of protocol layers or sublayers are structured as at least one of a protocol data unit (PDU) and a service data unit (SDU) according to a hierarchy of each of the plurality of protocol layers or sublayers.

6. The first wireless communication apparatus according to claim 2 , wherein the first processing is configured to generate the discarding notification information.

7. The first wireless communication apparatus according to claim 1 , wherein each piece of the multiple pieces of data in the structured MAC-PDU has not been transmitted by the first wireless communication apparatus to the second wireless communication apparatus, after the numbering of the multiple pieces of data.

8. The first wireless communication apparatus according to claim 1 , wherein the controller circuitry is further configured to discard specific data among the multiple pieces of data in accordance with an elapsed time counted by a timer in a Packet Data Convergence Protocol (PDCP) layer.

9. The first wireless communication apparatus according to claim 1 , wherein the controller circuitry is further configured to notify, to a MAC layer, information regarding discarding of the specific data in a layer that is upper than the MAC layer.

10. The first wireless communication apparatus according to claim 9 , wherein the controller circuitry is further configured to structure the MAC-PDU in response to the MAC layer being notified of the information regarding the discarding in the layer upper than the MAC layer.

11. The first wireless communication apparatus according to claim 9 , wherein the layer upper than the MAC layer is a Packet Data Convergence Protocol (PDCP) layer.

12. The first wireless communication apparatus according to claim 1 , wherein the specific data indicated by the discarding notification information in the MAC-PDU is discarded in a layer that is upper than a MAC layer.

13. The first wireless communication apparatus according to claim 1 , wherein the specific data is discarded in a Packet Data Convergence Protocol (PDCP) layer, and wherein the multiple pieces of data subsequent to the discarding in the PDCP layer, and the discarding notification information, which is related to the discarding in the PDCP layer, are included in the same transmitted MAC-PDU.

14. A second wireless communication apparatus comprising:

a receiver configured to receive a Medium Access Control protocol data unit (MAC-PDU), from a first wireless communication apparatus that is different from the second wireless communication apparatus, by the second wireless communication apparatus,

the MAC-PDU being received by the receiver of the second wireless communication apparatus in a case where, among multiple pieces of data, specific data has been discarded by the first wireless communication apparatus after numbering of the multiple pieces of data by the first wireless communication apparatus and before transmission, by the first wireless communication apparatus, of the MAC-PDU,

the MAC-PDU including:

the multiple pieces of data subsequent to the discarding by the first wireless communication apparatus, the multiple pieces of data in the MAC-PDU being numbered by the first wireless communication apparatus, the multiple pieces of data in the MAC-PDU being not renumbered by the first wireless communication apparatus after the numbering, and the multiple pieces of data in the MAC-PDU having not been transmitted by the first wireless communication apparatus to the second wireless communication apparatus, after the numbering of the multiple pieces of data; and

discarding notification information indicating that the specific data have been discarded by the first wireless communication apparatus; and

controller circuitry configured to perform rearranging processing on the multiple pieces of data that are received in the MAC-PDU, based on the numbering,

in a state where a missing number occurs as a result of the numbering that depends on the discarding by the first wireless communication apparatus, the MAC-PDU being received, from the first wireless communication apparatus by the second wireless communication apparatus, and

the multiple pieces of data subsequent to the discarding, and the discarding notification information being included in the same received MAC-PDU.

15. The second wireless communication apparatus according to claim 14 , wherein the controller circuitry is further configured to perform the rearranging processing with the specific data as being discarded, based on the discarding notification information.

16. A wireless communication system comprising:

a first wireless communication apparatus; and

a second wireless communication apparatus, the first wireless communication apparatus being configured to:

perform numbering of multiple pieces of data;

transmit the multiple pieces of data that are numbered to the second wireless communication apparatus,

structure a Medium Access Control protocol data unit (MAC-PDU), in response to specific data among the multiple pieces of data being discarded by the first wireless communication apparatus after the numbering by the first wireless communication apparatus and before transmission, by the first wireless communication apparatus, of the structured MAC-PDU,

the structuring of the MAC-PDU by the first wireless communication apparatus being performed without renumbering, by the first wireless communication apparatus, of the multiple pieces of data subsequent to the discarding by the first wireless communication apparatus,

the structured MAC-PDU including:

the multiple pieces of data subsequent to the discarding by the first wireless communication apparatus, the multiple pieces of data in the structured MAC-PDU having not been transmitted by the first wireless communication apparatus to the second wireless communication apparatus, after the numbering of the multiple pieces of data; and

discarding notification information indicating that the specific data have been discarded by the first wireless communication apparatus, and

transmit, in a state where a missing number occurs as a result of the numbering that depends on the discarding by the first wireless communication apparatus, the structured MAC-PDU from the first wireless communication apparatus to the second wireless communication apparatus, the multiple pieces of data subsequent to the discarding, and the discarding notification information being included in the same transmitted MAC-PDU.