In this paper we analyze the performance of mobile users in a LTE macrocell with different transmission zones. To this end, we develop a simple model based on a muticlass Processor Sharing queue, that captures mobility of users between zones through the distribution of the sojourn time a user stays in each zone. The originality of the model is to decouple the mobility model from the cell model itself, by relating both the input rates and the service rates of the PS queue to performance parameters. The unknowns of the underlying system are thus solution of a fixed-point iterative technique. We compare the cell performance obtained by the model to simulation and show the accuracy of the solution. We believe that this very encouraging result will be the starting point of numerous extensions.