Time, clocks, and the ordering of events in a distributed system
Communications of the ACM
Critical path analysis of TCP transactions
IEEE/ACM Transactions on Networking (TON)
Integrating satellite and terrestrial technologies for emergency communications: the WISECOM project
QShine 2007 Workshop: Satellite/Terrestrial Interworking
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The viability of a satellite link for the interconnection of two TETRA networks using the Inter-System Interface (ISI) is studied with respect to desired functionality and QoS. ISI-based TETRA over satellite can be used in emergency situations when no terrestrial infrastructure exists between the two networks, as well as in normal operations as an alternative to ground based interconnection infrastructure. The response time of different services in a given network architecture is of primary concern because large propagation delay is the main source of service degradation. A modified version of critical path analysis, as it applies to protocols, is used to estimate total propagation delays for a set of ISI services. The estimates give an insight into the delay-related problems expected in this particular interconnection scenario and represent quantitative measure of QoS degradations as experienced by the end users. Limits on the system timers can be deduced in order to avoid their premature expiration. The impact of satellite interconnection on ISI-based services is significant. A performance enhancing proxy functionality is foreseen to reduce the delays.