Relay link HARQ operation

A first network node in a wireless telecommunications system, comprising:

• a processor configured, when a ten millisecond periodicity is used for Multicast/Broadcast Single Frequency Network (MBSFN) subframes, to set a time between an uplink grant from the first network node to a second network node and an acknowledgement/negative-acknowledgement message (ACK/NACK) from the first network node to the second network node equal to ten milliseconds, and the processor further configured, when a forty millisecond periodicity is used for MBSFN subframes, to send the second network node a grant for an uplink retransmission when a data packet is missed.

A first network node in a wireless telecommunications system, comprising:

• a processor configured, when a ten millisecond periodicity is used for Multicast/Broadcast Single Frequency Network (MBSFN) subframes, to receive an acknowledgement/negative-acknowledgement message (ACK/NACK) from a second network node, a time between an uplink grant from the second network node to the first network node and the ACK/NACK from the second network node to the first network node being set equal to ten milliseconds, the processor further configured, when a forty millisecond periodicity is used for MBSFN subframes, to receive from the second network node an asynchronous grant for an uplink retransmission when a data packet is missed, and the processor further configured to retransmit the missed data packet when the first network node receives the grant for the uplink retransmission.

A first network node in a wireless telecommunications system, comprising:

• a processor configured to aggregate a plurality of acknowledgement/negative-acknowledgement messages (ACK/NACKs) when a second network node sends multiple transmissions of data to the first network node before the next opportunity for the first network node to transmit corresponding ACK/NACKs for the data transmissions to the second network node, the processor further configured to send the aggregated ACK/NACKs to the second network node in a single subframe, wherein the second network node explicitly informs the first network node which downlink transmissions to the first network node are allowed to have the ACK/NACKs for the downlink transmissions aggregated and explicitly informs the first network node which subframe the first network node is to use to transmit the aggregated ACK/NACK to the second network node.

A first network node in a wireless telecommunications system, comprising:

• a processor configured to receive an aggregated acknowledgement/negative-acknowledgement message (ACK/NACK) in a single subframe from a second network node, the aggregated ACK/NACK being formed from a plurality of ACK/NACKs when the first network node sends multiple transmissions of data to the second network node before the next opportunity for the second network node to transmit corresponding ACK/NACKs for the data transmissions to the first network node, wherein the first network node explicitly informs the second network node which downlink transmissions to the second network node are allowed to have the ACK/NACKs for the downlink transmissions aggregated and explicitly informs the second network node which subframe the second network node is to use to transmit the aggregated ACK/NACK to the first network node.