Patent ID: 7110418

Claim:
A method of ensuring quality of preferred services, in a data network in which stations transmit data as packets of different types of services on a shared transmission medium and data collision on the shared transmission medium is managed by a collision detection protocol in which different re-transmission rules after detection of data collisions are applied corresponding to the type of service, the method comprising: determining a type of service of a packet to be transmitted on the shared transmission medium by a station of the data network, said type of service including at least a preferred type of service and a non-preferred type of service; detecting a collision of the packet, which is transmitted by the station on the shared transmission medium, with at least one other packet; and calculating a random backoff time according to an algorithm that utilizes the different re-transmission rules depending on the type of service of the packet that is determined, wherein the different re-transmission rules each define a set of different parameters of the algorithm to randomly calculate the backoff time, which the station waits after the collision is detected until retransmitting the data packet that is affected by the collision, the sets of different parameters comprising each at least a preferred service mean value of the backoff time and a non-preferred service mean value of the backoff time, which is less than said preferred service mean value, wherein said random backoff time is calculated with said preferred service mean value if the packet is determined to be the preferred type of service and the random backoff time is calculated with said non-preferred service mean value if the packet is determined to be the non-preferred service.