ntroduction In most networks LTE will be deployed on multiple frequency bands and carrier frequencies. For this reason the design and optimization of mobility parameters between LTE layers and different radio access technologies (RATs) easily develops into an unmanageable tangle of cell change rules controlled by a large number of interdependent parameters. In order to easily maintain and optimize complex multi-layer networks it is therefore beneficial to have some kind of systematic - and preferably simple - approach to the management of mobility parameters. The purpose of this chapter is to summarize some potentially useful concepts and information for handling mobility in multi-layer LTE networks. The mobility design problem can be split into two regimes: coverage and capacity-limited cases. During initial LTE network roll-out the main emphasis is on guaranteeing continuous service coverage for the subscribers. In this phase the average network utilization is low, and the mobility thresholds can be set assuming that service level is limited by radio conditions rather than network capacity. At a later stage, when parts of the network become heavily utilized, it is the resource congestion that dominates the service-level degradation. This degradation can to certain extent LTE Small Cell Optimization: 3GPP Evolution to Release 13, First Edition. Edited by Harri Holma, Antti Toskala and Jussi Reunanen. © 2016 John Wiley & Sons, Ltd. Published 2016 by John Wiley & Sons, Ltd. LTE Small Cell Optimization be mitigated by balancing resource usage between cells of the network, necessitating steering of traffic to layers with free capacity. Without carrier aggregation the steering can be realized either by tuning of static mobility thresholds or dynamically by employing some form of load-adaptive mobility rules. While carrier aggregation is likely to be the long-term solution for inter-layer load balancing, single-carrier mobility will be needed for some time before multi-band carrier aggregation becomes widely available