Usar I. Analysis and optimization of retrial queues with variable rate of input flow.

We deal with a Markov models of the systems with repeated calls and variable rate of input flow without limitation on the capacity of the orbit controlled by different strategies. At first for such models the existence conditions of stationary regime are pointed out. Further analysis is based on the approximation of the initial systems by the ones with limited orbit for which explicit vector-matrix formulas of stationary probabilities are found. As a result, we obtained effective calculating algorithms for the characteristics of the systems in stationary regime in terms of parameters of the systems according to the control strategy. For threshold and hysteresis control strategies the optimization problem of the total income of the system was stated and solved. The rate of convergence of the stationary distribution of finite systems involved one and two servers to those of infinite systems under different control strategies were obtained.