Ku‐Band satellite data networks using very small aperture terminals—part II: System design

Abstract

AbstractIn this part of the paper on Ku‐band VSAT networks, the issue of overall system design is considered. After discussing possible system architectures, primary attention is given to the star network configuration in which customer‐premise VSATs communicate with a central hub station, co‐located with, or terrestrially connected to a host computer. The component elements of a Ku‐band star network for interactive data applications are discussed and the critical items from the point‐of‐view of performance, capacity and cost are identified. An analytical model for the network, which combines delay‐throughput characterization of the multi‐access inbound and TDM outbound channels with satellite link analysis is described. The analytical model is exercised over a range of typical system component, traffic model and performance objective scenarios to provide a set of general design guidelines. These guidelines are useful for evaluating the trade‐offs between key system elements (channel access unit, modem, VSAT antenna and satellite), VSAT traffic message length parameters and the performance objectives (average and peak network response time and availability). The results are used to address the issue of multi‐access protocol selection over a range of scenarios typical of 1.2 or 1.8m VSAT‐based interactive networks using current commercial Ku‐band satellites. The results show that interactive star networks are often limited by satellite power rather than bandwidth, so that the use of simple contention access for VSATs may not imply a significant system capacity penalty.