1. A system for scheduling packets from different flows for transmission via a channel, said system comprising: a data processor; a computer readable medium for storing computer program code which, when executed by the processor, builds a data structure, stored in memory, for holding information utilized to implement scheduling of packets, said data structure including information resident in a data base, used by said computer program code, including: a plurality of nodes stored in the memory, with each node identified by an index; tree structure information, associated with each node, determining parent, child, and sibling relationships to form calendar slots of a radix tree structure with multiple levels, with all nodes in a level being siblings, with a root level including no more than four nodes, with a leaf level including leaf nodes having no descendents; scheduling information in the form priority/eligibility keys held in each leaf node object, where the eligibility key held in a leaf node corresponds to the leaf node's index and the priority key indicates a priority level, and where the priority key indicating the highest priority of two adjacent nodes is copied to a parent node of the two adjacent nodes to augment the radix tree structure with a heap structure.