A method comprising: determining, by a user device, that the user device compliant with the 3GPP LTE standard is a low-latency mode user device ; receiving a downlink data block in downlink subframe n ; determining a hybrid automatic repeat request, HARQ, feedback for the data block ; determining, by the low-latency mode user device, an uplink subframe n+k at a HARQ feedback offset of k subframes from subframe n , wherein a minimum HARQ feedback offset for the low-latency mode user device is less than a minimum HARQ feedback offset of a normal-latency mode user device, wherein there is defined a first uplink subframe type for subframes with HARQ feedback from only low-latency mode user devices, a second uplink subframe type for subframes with HARQ feedback from only normal-latency mode user devices, and a third uplink subframe type for subframes with HARQ feedback from both the low-latency mode user devices and the normal-latency mode user devices, and wherein the determined uplink subframe n+k is of the the third uplink subframe type, determining that one or more first uplink HARQ resources for uplink subframe n+k have been allocated for HARQ feedback from a normal-latency mode user device for a downlink data frame having a HARQ feedback offset that is different than k subframes; and determining, by the low-latency mode user device based on the determined uplink subframe type, one or more uplink HARQ feedback resources allocated for the uplink subframe n+k and for the HARQ feedback from the low-latency mode user device, wherein one or more HARQ resources for the low-latency mode user device are mapped to physical uplink control channel, PUCCH, resources with highest indices, starting after the highest indexed HARQ resources mapped to the normal-latency mode user device; and transmitting, by the low-latency mode user device, the HARQ feedback via the determined uplink subframe n+k and the determined one or more uplink HARQ feedback resources . determining, by a user device, that the user device compliant with the 3GPP LTE standard is a low-latency mode user device ; receiving a downlink data block in downlink subframe n ; determining a hybrid automatic repeat request, HARQ, feedback for the data block ; determining, by the low-latency mode user device, an uplink subframe n+k at a HARQ feedback offset of k subframes from subframe n , wherein a minimum HARQ feedback offset for the low-latency mode user device is less than a minimum HARQ feedback offset of a normal-latency mode user device, wherein there is defined a first uplink subframe type for subframes with HARQ feedback from only low-latency mode user devices, a second uplink subframe type for subframes with HARQ feedback from only normal-latency mode user devices, and a third uplink subframe type for subframes with HARQ feedback from both the low-latency mode user devices and the normal-latency mode user devices, and wherein the determined uplink subframe n+k is of the the third uplink subframe type, determining that one or more first uplink HARQ resources for uplink subframe n+k have been allocated for HARQ feedback from a normal-latency mode user device for a downlink data frame having a HARQ feedback offset that is different than k subframes; and determining, by the low-latency mode user device based on the determined uplink subframe type, one or more uplink HARQ feedback resources allocated for the uplink subframe n+k and for the HARQ feedback from the low-latency mode user device, wherein one or more HARQ resources for the low-latency mode user device are mapped to physical uplink control channel, PUCCH, resources with highest indices, starting after the highest indexed HARQ resources mapped to the normal-latency mode user device; and transmitting, by the low-latency mode user device, the HARQ feedback via the determined uplink subframe n+k and the determined one or more uplink HARQ feedback resources . <EOS>