Communication device, communication method, and communication system

1. A first communication device in a communication systems including the first communication device and a second communication device that performs wireless connection with the first communication device and relays communication with the first communication device, the first communication device comprising:

a receiver configured to receive packets from the second communication device; and

a transmitter configured to:

store reception confirmation packets in a buffer, the reception confirmation packets corresponding to the received packets,

perform transmission of at least a portion of the reception confirmation packets stored in the buffer, and

discard reception confirmation packets not to be transmitted in the transmission according to a discard ratio; and

a controller configured to determine the discard ratio used in the communication according to a state of the wireless connection, the state of the wireless connection including a requested amount of resources requested from the second communication device by the first communication device and an allocated amount of resources allocated to the first communication device by the second communication device.

2. The first communication device according to claim 1 , wherein

the controller is configured to determine the discard ratio used in the connection according to a throughput in the wireless connection and a number of transmissions of the reception confirmation packets from the first communication device.

3. The first communication device according to claim 2 , wherein

the controller is configured to determine a discard ratio that is a minimum number of transmissions among discard ratios with the throughput equal to or higher than a first threshold as the discard ratio used in the communication.

4. The first communication device according to claim 2 , wherein

the transmitter is configured to perform one or more types of transmission number determination processing that determine the number of transmissions of the reception confirmation packets in the processing of transmitting at least a part of the reception confirmation packets, and

the controller is configured to determine the transmission number determination processing used in the communication among the one or more types of transmission number determination processing.

5. The first communication device according to claim 4 , wherein

the controller is configured to

select a discard ratio with a minimum number of transmissions from among discard ratios with the throughput equal to or higher than a first threshold for each of the one or more types of transmission number determination processing, and

determine the transmission number determination processing that is a minimum number of transmissions at the selected discard ratio as the transmission number determination processing used in the communication.

6. The first communication device according to claim 1 , wherein

the controller is configured to determine a discard ratio at which a difference between the requested amount of resources and the allocated amount of resources is within a second threshold as the discard ratio used in the communication.

7. The first communication device according to claim 1 , wherein

the controller is configured to determine the discard ratio according to a number of transmissions of the reception confirmation packets.

8. The first communication device according to claim 7 , wherein

the controller is configured to determine a fourth discard ratio that minimums the number of transmissions among fourth discard ratios as the discard ratio used in the communication, the fourth discard ratios being between a second discard ratio and a third discard ratio, the second discard ratio being higher by a predetermined number than a first discard ratio at which a difference between the requested amount of resources and the allocated amount of resources is within a second threshold, the third discard ratio being lower than the first discard ratio by a predetermined number.

9. The first communication device according to claim 4 , wherein

the one or more types of transmission number determination processing includes first transmission number determination processing that determines the number of transmissions of the reception confirmation packets according to an allocated amount of resources allocated to the first communication device by the second communication device.

10. The first communication device according to claim 4 , wherein

the one or more types of transmission number determination processing includes second transmission number determination processing that determines a number of response confirmation packets stored in the buffer by the receiver, as the number of transmissions of the reception confirmation packets.

11. The first communication device according to claim 4 , wherein

the one or more of transmission number determination processing includes third transmission number determination processing that performs both of first transmission number determination processing that determines the number of transmissions of the reception confirmation packets according to an allocated amount of resources allocated to the first communication device by the second communication device, and second transmission number determination processing that determines a number of response confirmation packets stored in the buffer by the receiver, as the number of transmissions of the reception confirmation packets.

12. The first communication device according to claim 1 , wherein

the transmitter is configured to transmit, to the second communication device, a reception confirmation packet other than the reception confirmation packets to be discarded.

13. The first communication device according to claim 1 , wherein

the discard ratio is defined according to an accumulation threshold of the buffer.

14. A communication system comprising:

a first communication device; and

a second communication device that performs wireless connection with the first communication device and relays communication with the first communication device, wherein the first communication device includes:

a receiver configured to receive packets from the second communication device, and

a transmitter configured to:

store reception confirmation packets corresponding to the received packets in a buffer,

perform transmission at least a portion of the reception confirmation packets stored in the buffer, and

discard reception confirmation packets not to be transmitted in the transmission according to a discard ratio; and

a controller configured to determine the discard ratio used in the communication according to a state of the wireless connection, the state of the wireless connection including a requested amount of resources requested from the second communication device by the first communication device and an allocated amount of resources allocated to the first communication device by the second communication device.

15. A communication method for a first communication device in a communication system including the first communication device and a second communication device that performs wireless connection with the first communication device and relays communication with the first communication device, the communication method comprising:

receiving packets from the second communication device, and

storing reception confirmation packets corresponding to the received packets in a buffer,

performing transmission at least a portion of the reception confirmation packets stored in the buffer, and

discarding reception confirmation packets not to be transmitted in the transmission according to a discard ratio; and

a controller configured to determine the discard ratio used in the communication according to a state of the wireless connection, the state of the wireless connection including a requested amount of resources requested from the second communication device by the first communication device and an allocated amount of resources allocated to the first communication device by the second communication device.