An Efficient Computation Algorithm for A Multiserver Feedback Retrial Queue With A Large Queueing Capacity

Kumar et al. consider the M/M/c/N+c feedback queue with constant retrial rate [1]. They provide a solution for the steady state probability based on the matrix-geometric method. We show that there exists a more efficient computation method to calculate the steady state probabilities when N + c is large. We prove that the number of zero-eigenvalues of the characteristic matrix polynomial associated with the balance equation is b(N + c+ 2)/2c. As consequence, the remaining eigenvalues inside the unit circle can be computed in a quick manner based on the Sturm sequences. Therefore, the steady state probabilities can be determined in an efficient way.