ACE/2: a scalable modular SATCOM system emulator

Simulation is widely used to evaluate the performance of telecommunication services. One interesting case is the access to the Internet through satellites, where a critical parameter is the quality of service perceived by the users (P-QoS). Unfortunately, TCP, the data transport protocol of the Internet, reacts to packet losses decreasing the packet transmission rate. This is perfectly suited to reduce congestion, the main reason of losses in terrestrial networks, but it further decreases the performance when losses are due to transmission errors, as in satellite links. The problem is made more complex by the interaction between TCP and the applications used to surf the Internet. To address this problem the Italian Space Agency (ASI) financed a two-year research program, during which two SATCOM system emulators, dubbed ACE and ACE/2, respectively, where built. This paper describes the second emulator, an enhanced version of the first one.