In this paper, we deal with a dynamic and stochastic admission control and mobile association problem in an heterogeneous wireless network. We extend the usual problem by adding mobility features described by a Markov Modulated Poisson Process. The aim is to optimize the average performance of the system. This dynamic control problem is modeled and solved using a Semi Markov Decision Process (SMDP) framework. We then assess the impact of the mobility and show that (i) our network centric approach outperforms a simple user centric algorithm and (ii) mobility improves the performance of the system when optimal policy of the problem is used.