Mobile communications and wireless networks are developing at an outstanding speed, with evidences of significant growth in the areas of mobile subscribers and terminals, mobile and wireless access networks and mobile services and applications. Mobility management, network selection, handover mechanisms and QoS control in next generation heterogeneous networks are still open research issues and all of them depended to each other. In this paper, different mobility solutions in heterogeneous wireless networks are over-viewed and classified according to their layer. QoS support for mobility, network selection and handover mechanisms are also reviewed to have complete picture of next generation networks.