PERFORMANCE EVALUATION, VOL.53, NO.1, PP.43-69, 2003. TITLE: Iterative Disaggregation for a Class of Lumpable Discrete-Time Stochastic Automata Networks AUTHORS: Oleg Gusak, Tugrul Dayar, and Jean-Michel Fourneau ABSTRACT: Stochastic automata networks (SANs) have been developed and used in the last 15 years as a modeling formalism for large systems that can be decomposed into loosely connected components. In this work, we concentrate on the not so much emphasized discrete-time SANs. First, we remodel and extend an SAN that arises in wireless communications. Second, for an SAN with functional transitions, we derive conditions for a special case of ordinary lumpability in which aggregation is done automaton by automaton. Finally, for this class of lumpable discrete-time SANs we devise an efficient aggregation-iterative disaggregation algorithm and demonstrate its performance on the SAN model of interest. KEY WORDS: Discrete-time stochastic automata networks; Ordinary lumpability; Iterative disaggregation; Wireless asynchronous transfer mode system.