In this research, a single-server M-class retrial queueing system (orbit queue) with constant rates and Poisson inputs is considered. The main purpose to construct the upper lower bounds of stationary workload in expressed via workloads classical M/G/1 systems where service time has M-component mixture distributions. This analysis applied establish extreme behaviour Pareto service-time distribu...

In this paper, models of unreliable multi-server retrial queues with delayed feedback are examined. The Bernoulli is allowed upon the arrival both primary (from outside) and customers orbit), as well that may occur after each service in system. Servers can break down during when they idle. If a server breaks customer, then interrupted accordance scheme, decides either to leave system or join co...

A polling model with n stations and switchover times is considered. The customers are of n different types, arrive to the system according to the Poisson distribution in batches of random size, and if they find the server unavailable, they start to make retrials until succeed to find a position for service. Each batch may contain customers of different types while the numbers of customers belon...

In this paper, we first consider single server retrial queues with two way communication. Ingoing calls arrive at the server according to a Poisson process. Service times of these calls follow an exponential distribution. If the server is idle, it starts making an outgoing call in an exponentially distributed time. The duration of outgoing calls follows another exponential distribution. An ingo...

Abstract: Generally in call centers, voice calls (say Type 1 calls) are given higher priority over e-mails (say Type 2 calls). An arriving Type 1 call has a preemptive priority over a Type 2 call in service, if any, and the preempted Type 2 call enters into a retrial buffer (of finite capacity). Any arriving call not able to get into service immediately will enter into the pool of repeated call...