| 摘要 |
In order to schedule the transmission of cells of guaranteed-bandwidth virtual channels, a circular list is provided having a predetermined number of entry slots and each channel with cells to send has a corresponding identifier VCN placed in a respective slot in the list, only one VCN being allowed per slot. The list is advanced through slot by slot and each VCN encountered is processed to cause the transmission of a cell for the corresponding virtual channel. The list is also updated for each slot advanced past by freeing that slot and inserting back into the list any VCN that occupied the slot if that VCN relates to a virtual channel with another cell to transmit. This insertion is effected at an offset from the slot previously occupied by the VCN, dependent on a transmission rate indicator (SRP, PRP) of the virtual channel concerned. In the event of the target slot being occupied a conflict resolution procedure is effected based on the relative priority of the channel involved, the unsuccessful channel being displaced to the following slot, subject to availability.
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