Scheduling and admission control of packet data traffic

A network node in a communications system for processing real-time data packet traffic, comprising

• a packet error rate determining unit to determine a packet error rate (Pj) of a communications channel (j),
• a bit rate determining unit to determine a bit rate (Rj) of said communications channel (j),
• a timer to determine for at least one data packet that is received at the network node a current time value (t),
• an evaluation means to evaluate control parameters given by at least one control packet (ACP, SCP) embedded in a traffic flow,
• a calculator unit for calculations of deadlines for data packets, and
• a first queue (EDF) for data packets.

A computer program,

• loadable into a memory of a digital computer,
• comprising software code portions for performing the steps of
• detecting in a data packet stream, which carries real-time data traffic, and which is received at a packet scheduler, at least one synchronisation control packet (SCP), which is followed by a synchronisation entity that comprises at least one payload data packet, said synchronisation control packet comprising synchronisation control parameters,
• reading from the synchronisation control packet a number of packets in the synchronisation entity (N), a maximum transmission time (I) allowed for a real-time transmission of the synchronisation entity and a byte-size (S) of the synchronisation entity,
• determining a packet error rate (Pj) of a channel (j) that is used for transmitting said sub-stream,
• determining a bit rate (Rj) of said channel,
• determining a time value (t) indicating a current arrival time of payload data packets, and,
• calculating for each payload data packet a delivery deadline therefrom,
• sorting each payload packet according to its deadline into a time stamp based first queue (EDF), and setting a time stamp of the first queue to the calculated deadline,
• when said computer program is executed on a computer.