Approximation of discrete time tandem queueing networks with unreliable servers and blocking

We consider the discrete time tandem queues with single unreliable server at each service station and a buffer of finite capacity between service stations. The blocking after service (BAS) mechanism and operation dependent failure (ODF) rule are adopted. The service time of each server is a constant unit time. A failure of each server occurs in a time slot with a fixed probability and the repair time distribution of each server is of discrete phase type. In this paper, we present an approximate analysis for the system based on the decomposition method and show that the approach can be applied to the variants of the system.