Packet Switching in a Multiaccess Broadcast Channel: Dynamic Control Procedures

In a companion paper [1], the rationale for multiaccess broadcast packet communication using satellite and ground radio channels has been discussed. Analytic tools for the performance evaluation and design of uncontrolled slotted ALOHA systems have been presented. In this paper, a Markovian decision model is formulated for the dynamic control of unstable slotted ALOHA systems and optimum decision rules are found. Numerical results on the performance of controlled channels are shown for three specific dynamic channel control procedures. Several practical control schemes are also proposed and their performance compared through simulation. These dynamic control procedures have been found to be not only capable of preventing channel saturation for unstable channels but also capable of achieving a throughput-delay channel performance close to the theoretical optimum.