This paper proposed an improved handoff strategy with combination of channel reservation and preemptive priority for integrated real-time and non real-time service cellular mobile systems.

A handoff scheme is introduced in this paper, which considers the dynamic thresholds and preemptive priority level in intergrated voice and data LEO(Low Earth Orbit) satellite systems.

In this paper, a round-robin preemptive priority scheduling algorithm is analyzed, which will lead to priority inversion when multiple tasks seeking access to shared resources use the semaphore mechanism.

We assume the first kind of cell has the preemptive priority on the second kind of cell,and the first kind of cells is impatient.

Two kinds of customers flow into the system with the first kind of customers a preemptive priority over the second kind of the customers.

First, this paper studies multiple servers queues with impatient customers of preemptive priority.

In this paper,a Geo_1■Geo_2/Geo_1,Geo_2/s/s+K queue system is considered,there are two class of customer in the system,the first class of customer is delay and lossy,the second class of customer is lossy,and the second class of customer has preemptive resume priority than the first class of customer.