Routing and Re-Routing in a LEO/MEO Two-tier Mobile Satellite Communications System with Inter-Satellite Links

A novel LEO/MEO two-tier satellite communication system with inter-satellite links ( I S L r ) is proposed for providing multimedia services to global mobile users. This two-tier syxtem architecture can reduce the transmission delay for long-distunce users via ME0 satellites while keeping the benefits of using LEO satellites as the service access nodes. The routing and re-routing during a handoff operation is simplified. Since the physical topor'ogy of ihe underlying neiwork is time-dependent, routing is crucial for guaranteeing the delay and delay variation pegormanre for interactive applications. In this paper, we decompose the routing problem into two parts, routing in the access network and routing in the core ME0 ISL neiwork For access neiwork, a new routing algorithm called Maximum Holding Access Protocol (MHAP) is proposed for minimizing the number of LEO handoffs. For core ME0 ISL network, both Minimum Transmission Delay Routing (MTDR) and Minimum Transmission Time Jitter Routing (MTI'JR) are investigated. Using computer simulations, we show that the proposed routing algorithms can reduce the probability of call rerouting and thus are very suitable for providing interactive multimedia services.