On the application of importance sampling to the simulation of digital satellite and multihop links

The applicability of importance sampling to the simulation of nonregenerative digital satellite links (i.e., two-hop systems) is demonstrated formally, the emphasis being on the presentation of the method of application rather than specific numerical results. Two cases are distinguished: one where the receiver (prior to the decision device) can be considered linear and the other where this assumption cannot be made. If the receiver is linear, a quasi-analytical approach may be used to further improve the benefit of importance sampling; the actual amount of variance reduction, however, cannot be easily ascertained for arbitrary systems. When the effect of imperfect phase and timing estimation is to be included, two basic types of approach are possible, one in which this effect is accounted for separately, after the simulation run proper, and the other where these functions are simulated explicitly.