Wireless access allows independency between the user’s position and the physical bearer used to access services from the network. However, this independency does not imply that wireless networks show a full ability to cope with any degree of mobility. This is because other constraints can limit the mobility when accessing the network. The main constraints are registration and addressing (e.g., of user, terminal, application) and handover. In general, procedures needed to cope with those issues have a cost in terms of quality degradation, need for more resources, or both; this is known as mobility cost. Performance evaluation of mobility related issues in wireless networks requires a precise knowledge and understanding of the way in which terminals move, the impact of the movement on performance and quality, and the procedures and resources allocated in the network to minimize the impact of the mobility.