The dynamic frame protocol

A novel MAC protocol is being developed for use with a satellite communications (SATCOM) on-the-move (SOTM) prototype development terminal. The dynamic frame protocol (DFP) was proposed based on anticipated efficiency for shared transponder access for mobile SATCOM. The protocol supports multiple levels of quality of service (QoS), multicast messaging, can scale to 10s of nodes and can be implemented on low cost commercial off-the-shelf (COTS) hardware. The protocol was based on the time division multiple access (TDMA) interface processor (TIP), a dynamically assigned TDMA protocol with centralized timeslot allocation. This base protocol was chosen for its QoS support, low, delay properties, and channel efficiency. DFP is the result of modifying the TIP protocol to combat the effects of long modem acquisition times, a consequence of the currently available hardware and the mobile environment in which it is being used. DFP improves both the channel efficiency and overall message delay by grouping channel accesses for a single node into variable length timeslot groups. Channel efficiency is further improved by the use of variable length frames. This adapts the sum total channel access time of all nodes within a network to the current message volume. Mathematical models show significant improvement of DFP over TIP in both overall delay and channel efficiency.