Patent ID: 7174374
Filing Date: 2007-02-06
Classification: H04J

Abstract:
1. A multi-priority media access control method for a multi-channel slotted ring network having a plurality of nodes connected in a ring topology, a plurality of channels for transmitting data packets and control packets, and providing a plurality of slots that synchronously and circularly flow in one direction, every control packets carrying headers of slots of corresponding channels within a slot time and providing a priority value field corresponding to a slot in one channel, each node having a plurality of queues and a stack for one channel, each queue storing packets with the same priority and having a predefined high threshold and a predefined low threshold, the method comprising the steps of: (A) setting the priority value fields of the control packets with priority values to identify a priority for each slot by: (A1) calculating a waiting time of a queue when a node transmits a packet from the queue; (A2) if the waiting time of the queue is larger than its high threshold, seeking a priority value field of the corresponding channel whose value is lower than the priority of the queue, pushing the value of the priority value field into its stack, and setting the priority value field with the priority of the queue; and (A3) if the waiting time of the queue is smaller than its low threshold, seeking a priority value field of the corresponding channel whose value is the same as the priority of the queue, popping a value from the stack, and setting the priority value field with the popped value; and (B) each node depending on the priority value fields of control packets to select a queue at every slot time in such a manner that the priority of a slot is the smallest priority of packets that can be carried by the slot.