With the advancement of telecommunication systems in recent years, demand for higher data rates has been rising. One of the proposed key solutions to meet this demand is the use of Heterogeneous Networks (HetNets), in other words, the use of small cells, including microcells, picocells and femtosecells along with the conventional macrocells. One of the main challenges in HetNets is the energy consumption during network's lower load situations, and there are several techniques to reduce it. One of these techniques is to balance the load of base stations by defining a sleep state among them. One of the proposed approaches to achieve this purpose is to model it with a non-cooperative game that is explored in this thesis. Another major challenge is to manage the mobility and Handover of users in such networks. Due to the limited power of small base stations, such as microcells, Handover in HetNets unlike traditional networks is not just based on power as other elements are involved. In addition, in such networks, the handover is not just to keep the user in contact, but also to maintain load balancing and reduce energy consumption. Therefore, the handover is very significant. In this thesis, the sleep-based HetNets are surveyed and a handover algorithm for such networks is provided. In the proposed algorithm, the parameters of received power, along with the base station load and users’ velocities have been used in the handover process and effort has been made to reduce number of additional handovers by using the users’ velocities and encouraging the users with high velocities to connect to macro base station. Also it has been tried to keep the load balance between base stations and prevent overloading. Finally the aforementioned algorithm has been simulated. The simulation results indicate reduction in the number of handover in presented algorithm compared to the conventional algorithms and algorithms in which velocity is not considered. The proposed algorithm also results in reduction in base stations’ power consumption and has higher throughput compared to similar algorithms presented in papers. Keywords: Heterogeneous Networks, Game Theory, Microcell, Handover