Example embodiments describe a transmitter including data encapsulation circuitry configured to encapsulate data packets into Data Transport Units, DTUs, for further transmission over a communication medium. The data packets have respective Quality of Service, QoS, tolerances. The data encapsulation circuitry is configured to delay transmission of first data packets with a lower QoS tolerance and to group the first data packets in a subset of DTUs available for transportation of the first data packets.