In this work, we are interested in evaluating the performance of IP-Ad Hoc gateways. Indeed, we modelled the data transmission between a fixed node (router) and a node of ad hoc network by a tandem queues M / M / 1 / ∞ → M / M / 1 / N, where customers are packages, the first queue represents the fixed node and the second queue represents the Ad Hoc node.

This model is multidimensional and nonproduct queuing network, which makes the calculation of its stationary probabilities difficult. In the theory of queuing systems, truncation is to approximate the characteristics of an infinite state Markov chain by the corresponding ones of a Markov chain with finite state space. The study of these methods is initiated by Seneta  in 1967.

In  this  we use the strong stability approach to establish analytic error bounds for the truncation of a tandem queue with blocking queue tandem with blocking and infinite buffer (M / M / 1 / ∞ → M / M / 1 / N) by a  tandem with blocking and finite buffer  (M / M / 1 / Q → M / M / 1 / N).