The technology in this application provides for efficient use of a common uplink radio resource, like the common E-DCH resource. A UE lacking a valid radio network identifier, e.g., a UE in an idle mode, receives a data unit and adds error detection bits to generate a new data unit. The new data unit is divided into segments at a lower protocol layer which are provided for transmission to the network via the common uplink radio resource. A network node detects lower protocol layer data unit segments received on the common uplink radio resource and assembles them into an assembled data unit at a higher protocol layer. Error detection bits included with the assembled data unit are used to determine if the assembled data unit includes correctly received data unit segments, e.g., data unit segments from the same UE.