Communications cell scheduler and scheduling method for providing

Abstract

A method and apparatus are provided for scheduling the transmission of cells of a plurality of data streams in a communications network. A best effort scheduler is provided for scheduling the transmission of cells of a plurality of data streams in a communications network. The best effort scheduler includes a best effort operational mode and can include more than one timing wheel. When the best effort scheduler includes more than one timing wheel, then the priority of the best effort timing wheel is lower than the priority of the other timing wheel or wheels. Data of each data stream is enqueued to a corresponding data cell queue. A target next transmission time for each data cell queue is calculated utilizing predetermined logical channel descriptor parameters. A lower priority or a higher priority timing wheel is selected and a timing wheel time slot is calculated based on an identified target transmission time for each active data cell queue. An active indication is set for the identified timing wheel time slot and an entry is stored to point to the corresponding data cell queue for the identified timing wheel time slot. The relative rates between data streams are maintained, while the absolute rates of the data streams are increased or decreased in the low priority wheel. Scheduling opportunities can be defined utilizing a predefined pseudo data cell queue. Then the calculation of the target transmission time for each data cell queue includes the predefined pseudo data cell queue, and the identified target transmission time for the predefined pseudo data cell queue defines scheduling opportunities of multiple timing wheel time slots.