Dynamics of TCP over BoD Satellite Networks

Bandwidth-on-Demand (BoD) mechanisms are used by most next generation satellite systems to efficiently share a limited radio spectrum among a large number of users. BoD design needs to consider a range of engineering issues: the anticipated number of users, interactions with other subsystems, and the contradictory design goals of optimising system utilization and delay/capacity offered to the network traffic. A BoD system may provide a range of quality of service classes to support different user classes and allow optimisation of allocation efficiency. Each class may have different delay and delay variation characteristics. The performance achieved by a TCP flow using such a BoD satellite network is highly dependent on the delay and the variation of the delay experienced by TCP. This paper describes the BoD mechanisms, and their expected impact on TCP behaviour. This discussion is supplemented by simulation results using an implementation of TCP combined with a model of some simple satellite BoD access schemes to characterize the performance and efficiency of BoD algorithms. Copyright (C) 2003 John Wiley Sons, Ltd.