The network node of a cellular network assigns a first part of a shared radio resource to a first User Equipment, UE, for uplink transmissions in the cell, and instructs the first UE to apply a first UE-specific Hybrid Automatic Repeat Request, HARQ, process for transmitting on the assigned first part. The network node also assigns a second part of the shared radio resource to a second UE for uplink transmissions in the cell, and instructs the second UE to apply a second UE-specific HARQ process for transmitting on the assigned second part, the second HARQ process being separate from the first HARQ process. The network node then receives data transmitted from the first UE on the assigned first part based on the first HARQ process and data transmitted from the second UE on the assigned second part based on the second HARQ process.