Performance estimation of asymmetric satellite-closed network for inter-university communication system

We have carried out a performance estimation of reliable data transmission in an asymmetric satellite-closed network that makes carrier assignments using FDM (frequency division multiplexing) and TDMA (time division multiple access). Satellite-terrestrial connections have been used in asymmetric networks such as hybrid Internet access. However, the inter-university satellite network switches transmitting stations, and the network topology dynamically changes. This makes the router setting complicated at each station. One solution is to construct a satellite-closed network with FDM downstream links and TDMA feedback links. This simple configuration may enable users to manage data transmission without detailed knowledge of the network equipment, but the performance may drop because of mainly propagation errors and delay. We then simulated throughput performance of multicast communications with a SR (selective-repeat) protocol for error control using a slotted-ALOHA scheme. The simulation results show the feedback link traffic dominates the throughput in the network. This suggests that the retransmission process needs to work by avoiding traffic congestion at the feedback links.