Patent ID: 6917606

Claim:
A priority data transfer method for a communication system using random access control, said priority data transfer method comprising the steps of: detecting collision of a sent packet against other packet on a transmission line (a collision detection step); upon the detection of the collision of the packet against other packet in the collision detection step, generating a random number (a random number generation step); judging the priority level of the sent packet (a priority level judging step); generating a delay time, which elapses until the sent packet is resent, based on the random number generated in the random number generation step and the priority level of the sent packet judged in the priority level judging step (a delay time generation step); and resending the packet after the elapse of the delay time generated in the delay time generation step; said method further comprising the step of: providing a hop count recording field for recording a hop count as a measure of the priority level of the sent packet; and judging the priority level of the sent packet based on the hop count recorded in the hop count recording field; and wherein, in the delay time generation step includes multiplying the random number generated in the random number generation by a value obtained by subtracting a value proportional to the hop count from 1 (one) to generate the delay time, and wherein the resending step includes preferentially resending the packet having a larger hop count recorded in the hop count recording field.