On the efficient solution of a multiserver system with two reattempt orbits

In communication networks that guarantee seamless mobility of users across service areas, reattempts occur as a result of user behavior but also as automatic retries of blocked handovers. A multiserver system with two reattempt orbits is obtained when modeling these networks. However, an exact Markovian model analysis of such systems has proven to be infeasible and resorting to approximate methods is mandatory. To the best of our knowledge all the existing methods are based on computing the steady state probabilities. We propose another approach based on the relative state values that appear in the Howard equations. We compare the proposed method with the most well-known methods appeared in the literature in a wide range of scenarios. The results of the numerical evaluation carried out show that this solution outperforms the previous approaches in terms of both accuracy and computation cost for the most common performance parameters used in retrial systems.