Design of a medium access control feedback mechanism for cellularTDMA packet data systems

摘要

Cellular packet data systems require medium access control (MAC)nprotocols that allow flexible resource allocation on both the uplink andnthe downlink. The overhead introduced for managing MAC functions shouldnbe minimized, and control fields should be well protected in order tonprovide robustness to channel errors. The IS-136 TDMA digital controlnchannel specifies shared channel feedback (SCF) procedures and fieldsnfor managing uplink resources. However, the SCF mechanism is not wellnsuited to long packet data transactions. We describe a simple and robustnpacket channel feedback (PCF) mechanism for an IS-136 based TDMA packetndata channel by identifying the minimal set of functions and fieldsnrequired to manage both contention access and reserved access. Thenproposed scheme has unambiguous state transitions and better performancenunder error conditions. The PCF scheme provides considerable flexibilitynin assigning bandwidth to multiple users, and allows the efficientnscheduling of contention and reservation opportunities on eachnsubchannel without wasted slots