Hybrid automatic repeat request (HARQ) retransmission using multiple timers

1. A first apparatus, comprising:

at least one processor; and

at least one memory including computer program codes;

the at least one memory and the computer program codes are configured to, with the at least one processor, cause the first apparatus at least to:

transmit a transport block of a hybrid automatic repeat request process on preconfigured resources for an uplink transmission to a second apparatus while starting a first timer and a second timer for the hybrid automatic repeat request process, wherein the first timer indicates a time period during which the transport block is able to be retransmitted, and wherein the second timer is configured to expire before the first timer;

monitor a response associated with the transport block from the second apparatus; and

in response to the second timer expiring before receiving the response and before expiry of the first timer, retransmit the transport block while restarting the second timer, wherein the at least one memory and the computer program codes are further configured to cause the first apparatus to

in response to determining that at least one other transport block of a further hybrid automatic repeat request process associated with a selected hybrid automatic repeat request process identifier is to be retransmitted, retransmit the at least one other transport block on the preconfigured resources prior to transmitting the transport block.

2. The first apparatus of claim 1 , wherein the at least one memory and the computer program codes are further configured to cause the first apparatus to

determine whether the preconfigured resources are available for retransmitting the transport block; and

in response to determining that the preconfigured resources are available, retransmit the transport block on the preconfigured resources.

3. The first apparatus of claim 1 , wherein the at least one memory and the computer program codes are further configured to cause the first apparatus to restart the first timer upon retransmission of the transport block.

4. The first apparatus of claim 1 , wherein the at least one memory and the computer program codes are further configured to cause the first apparatus to

in response to receiving from the second apparatus the response, wherein the response indicates a dynamic grant resource for retransmitting the transport block, retransmit the transport block on the dynamic grant resource while restarting the first timer.

5. The first apparatus of claim 4 , wherein the response is received on a physical downlink control channel.

6. The first apparatus of claim 4 , wherein the at least one memory and the computer program codes are further configured to cause the first apparatus to stop the second timer upon the reception of the response.

7. The first apparatus of claim 1 , wherein the at least one memory and the computer program codes are further configured to cause the first apparatus to

in response to receiving the response, wherein the response indicates a successful reception of the transport block by the second apparatus, stop both of the first timer and the second timer.

8. The first apparatus of claim 1 , wherein the at least one memory and the computer program codes are further configured to cause the first apparatus to

in response to determining that no prior transport block of a further hybrid automatic repeat request process is to be retransmitted, transmit the transport block on the preconfigured resources.

9. The first apparatus of claim 1 , wherein the at least one memory and the computer program codes are further configured to cause the first apparatus to

in response to determining that a first prior transport block and a second prior transport block are to be retransmitted, compare a first priority of the first prior transport block on a first hybrid automatic repeat request process and a second priority of the second prior transport block on a second hybrid automatic repeat request process; and

in response to determining that the first priority is higher than the second priority, retransmit the first prior transport block.

10. The first apparatus of claim 9 , wherein the first priority comprises at least one of:

a time priority indicating a time duration left for a retransmission of the first prior transport block on a first hybrid automatic repeat request process and the second priority comprises a time priority indicating a time duration left for a retransmission of the second prior transport block on a second hybrid automatic repeat request process;

a logical channel priority of the first prior transport block on a first hybrid automatic repeat request process and the second priority comprises a logical channel priority of the second prior transport block on a second hybrid automatic repeat request process, wherein the logical channel priority indicates a highest priority among logical channels multiplexed in a transport block; or

a retransmission attempt priority indicating a number of retransmission times of the first prior transport block on a first hybrid automatic repeat request process and the second priority comprises a retransmission attempt priority indicating a number of retransmission times of the second prior transport block on a second hybrid automatic repeat request process.

11. The first apparatus of claim 1 , wherein the first apparatus comprises a terminal device and the second apparatus comprises a network device.

12. A first apparatus, comprising:

at least one processor; and

at least one memory including computer program codes;

the at least one memory and the computer program codes are configured to, with the at least one processor, cause the first apparatus at least to:

determine, at the first apparatus, whether at least one prior transport block on a hybrid automatic repeat request process to be retransmitted on preconfigured resources for an uplink transmission; and

in response to determining that at least one other transport block is to be retransmitted, retransmit the at least one other transport block on the preconfigured resources, wherein the at least one memory and the computer program codes are further configured to cause the first apparatus to

in response to determining that no prior transport block on the hybrid automatic repeat request process is to be retransmitted, transmit a transport block on a further hybrid automatic repeat request process associated with a selected hybrid automatic repeat request process identifier on the preconfigured resources while starting a first timer and a second timer for the further hybrid automatic repeat request process, wherein the first timer indicates a time period during which the transport block is able to be transmitted, and wherein the second timer is configured to expire before the first timer.

13. The first apparatus of claim 12 , wherein the at least one memory and the computer program codes are further configured to cause the first apparatus to

in response to determining that a first prior transport block and a second prior transport block are to be retransmitted, compare a first priority of the first prior transport block on a first hybrid automatic repeat request process and a second priority of the second prior transport block on a second hybrid automatic repeat request process; and

in response to determining that the first priority is higher than the second priority, retransmit the first prior transport block.

14. The first apparatus of claim 13 , wherein the first priority comprises at least one of:

a time priority indicating a time duration left for a retransmission of the first prior transport block on a first hybrid automatic repeat request process and the second priority comprises a time priority indicating a time duration left for a retransmission of the second prior transport block on a second hybrid automatic repeat request process;

a logical channel priority of the first prior transport block on a first hybrid automatic repeat request process and the second priority comprises a logical channel priority of the second prior transport block on a second hybrid automatic repeat request process, wherein the logical channel priority indicates a highest priority among logical channels multiplexed in a transport block; or

a retransmission attempt priority indicating a number of retransmission times of the first prior transport block on a first hybrid automatic repeat request process and the second priority comprises a retransmission attempt priority indicating a number of retransmission times of the second prior transport block on a second hybrid automatic repeat request process.

15. The first apparatus of claim 12 , wherein the at least one memory and the computer program codes are further configured to cause the first apparatus to

monitor a response associated with the transport block from the second apparatus; and

in response to the second timer expiring before receiving the response and before expiry of the first timer, retransmit the transport block while restarting the second timer.

16. The first apparatus of claim 12 , wherein the at least one memory and the computer program codes are further configured to cause the first apparatus to

determine whether the preconfigured resources are available for retransmitting the transport block; and

in response to determining that the preconfigured resources are available, retransmit the transport block on the preconfigured resources.

17. The first apparatus of claim 12 , wherein the at least one memory and the computer program codes are further configured to cause the first apparatus to restart the first timer upon retransmission of the transport block.

18. The first apparatus of claim 12 , wherein the at least one memory and the computer program codes are further configured to cause the first apparatus to

in response to receiving from the second apparatus the response, wherein the response indicates a dynamic grant resource for retransmitting the transport block, retransmit the transport block on the dynamic grant resource while restarting the first timer.