Design of adaptive MAC for high speed packet access system

Medium Access Control (MAC) entity forms the most important part of any high speed packet access system. Complying with the high data rate requirements, MAC Layer requires a highly efficient Scheduler algorithm working in tandem with the Flow Control, buffer utilization , access terminalpsilas capability and with Channel Quality requirements. The MAC entity mainly consists of the Flow Control Engine, Buffer Management, Scheduler , Encoder and HARQ process that together provide a steady packet flow to the physical layer. In this paper, we study the new design methodology for MAC layerpsilas based on the modified Opportunistic Proportionate Fairness Scheduler (OPFS)¹² algorithm which dynamically adapts the Transport Format (TF) Selection either based on legacy algorithm or access terminalpsilas feedback taking stress condition in the system, balancing Proportionate and Priority factor dynamically per scheduling cycle , providing the correct feedback to Flow Control and the HARQ retransmission process. MAC calculates the weighted capability per queue per user depending on the retransmission, actual buffer occupancies, dynamic token value , Traffic Class Priority, as well as in varying channel conditions and sends the selected queue to the physical layer.