Guidelines for Sizing Traffic Queues in Terminals of Future Protected SATCOM Systems

Future Military Satellite Communication systems will feature Time-Division Multiple Access (TDMA) uplinks in which uplink resources will be granted on demand to each terminal by a centralized resource controller. Due to the time-shared nature of the uplink, a terminal will not be constantly transmitting. It will only transmit in its assigned timeslots so as not to cause interference to other terminal transmissions. Packets arriving at a terminal during idle transmission periods will have to be buffered or queued, potentially in a terminal router, else they will be dropped. At the next assigned timeslot these queues will be serviced via a queue scheduling policy that maintains Quality-of-Service (QoS) requirements to the different traffic classes. These queues must be sized large enough to ensure no packet loss when operating in an uncongested state; how large is a function of the distribution of timeslots assigned to the terminal. In this paper, we investigate the relationship between timeslot assignment distributions and queue requirements of a terminal router providing insight of how to size router queues given an assigned timeslot distribution, or reciprocally, constraints placed on timeslot distribution given a set queue size, in order to avoid packet loss. Presented at the Military Communications Conference held in Boston, MA on 18-21 Oct 2009.