%0 Journal Article %T Product-form solutions for a class of structured multi-dimensional Markov processes %A Jori Selen %A Ivo J. B. F. Adan %A Johan S. H. van Leeuwaarden %J Mathematics %D 2013 %I arXiv %R 10.1137/130943297 %X Motivated by queueing systems with heterogeneous parallel servers, we consider a class of structured multi-dimensional Markov processes whose state space can be partitioned into two parts: a finite set of boundary states and a structured multi-dimensional set of states, exactly one dimension of which is infinite. Using separation of variables, we show that the equilibrium distribution, typically of the queue length, can be represented as a linear combination of product forms. For an important subclass of queueing systems, we characterize explicitly the waiting time distribution in terms of mixtures of exponentials. %U http://arxiv.org/abs/1310.8114v3