Base station, comprising: - a computing unit for forming a first plurality of resources and a second plurality of resources, from resources on an uplink of a contention-based multiple-access channel without prior resource reservation, - a transmission unit for transmitting a unique transmission code to each of a plurality of mobile stations, said transmission codes being codes that are orthogonal or quasi-orthogonal to one another and each transmission code allowing the associated mobile station to indicate the transmission of a random access attempt to access the first plurality of resources, - a reception unit for receiving, from at least one mobile station, in the first plurality of resources, at least one random access attempt with a view to establishing a latency-critical service, the access attempt comprising address information allowing the associated mobile station to be uniquely identified, and in the second plurality of resources, at least one previously transmitted unique transmission code, - the computing unit is furthermore configured to determine, based on the received transmission code and on the plurality of received random access attempts, at least one mobile station for which the random access attempt to access the first plurality of resources failed, referred to as failed mobile station, and - the transmission unit is furthermore configured to transmit non-acknowledgement of receipt information to the failed mobile station. - a computing unit for forming a first plurality of resources and a second plurality of resources, from resources on an uplink of a contention-based multiple-access channel without prior resource reservation, - a transmission unit for transmitting a unique transmission code to each of a plurality of mobile stations, said transmission codes being codes that are orthogonal or quasi-orthogonal to one another and each transmission code allowing the associated mobile station to indicate the transmission of a random access attempt to access the first plurality of resources, - a reception unit for receiving, from at least one mobile station, in the first plurality of resources, at least one random access attempt with a view to establishing a latency-critical service, the access attempt comprising address information allowing the associated mobile station to be uniquely identified, and in the second plurality of resources, at least one previously transmitted unique transmission code, in the first plurality of resources, at least one random access attempt with a view to establishing a latency-critical service, the access attempt comprising address information allowing the associated mobile station to be uniquely identified, and in the second plurality of resources, at least one previously transmitted unique transmission code, - the computing unit is furthermore configured to determine, based on the received transmission code and on the plurality of received random access attempts, at least one mobile station for which the random access attempt to access the first plurality of resources failed, referred to as failed mobile station, and - the transmission unit is furthermore configured to transmit non-acknowledgement of receipt information to the failed mobile station.