Effect of mobility on Future Satellite Packet Networks routing protocols

Current communication satellites are generally based on circuit technology and fixed-location terminals. In the future, satellites are expected to use packet-based (i.e., Internet) technology, and to support mobile as well as fixed-location terminals. We refer to these types of networks as future satellite packet networks (FSPNs). FSPNs will allow anywhere-to-anywhere global network connectivity for mobile nodes. However, due to blocking and/or fading, link connectivity will be dynamic. To preserve network connectivity in this dynamic environment, mobile nodes can be connected by terrestrial wireless as well as satellite links. The terrestrial links provide alternate paths from blocked terminals to the network. In this paper, we look at two types of outages, (1) payload-terminal outages, and (2) terrestrial wireless link outages. Using OPNET simulation, we examine how Internet routing adapts to link outages. We show that by properly adjusting the hold timer and the "hello" interval, we can speed up routing adaptation while keeping control traffic overhead low. We also look at how routing protocols behave when blockage ends and connectivity is restored. There are two basic approaches to dealing with the newly available link, keeping the current link, or having a "preferred" link. We discuss the tradeoffs of these two approaches.