Abstract: A method of data transmission in a network sharing a medium using a time division multiple access scheme in which a network unit receives data packets from a subnetwork, stores the data packets in a buffer until the arrival of a time-slot and sends the data packets over the shared medium in the upstream direction during the time-slot. Each of the data packets includes a payload and a header that includes a source address and a destination address. Storing the data packets in the buffer includes: determining the paired source and the destination addresses of a received packet; determining whether a composite frame having a composite frame header including the paired source and destination addresses already exists; if negative, creating the composite frame for the paired source and destination addresses; and aggregating the payload of the packet to a composite frame payload of the composite frame.