Local Anchor Based Location Management Schemes for Small Cells in HetNets

(c) 2015 IEEE. Personal use of this material is permitted. Permission from IEEE must be obtained for all other users, including reprinting/ republishing this material for advertising or promotional purposes, creating new collective works for resale or redistribution to servers or lists, or reuse of any copyrighted components of this work in other works.[EN] Existing location management (LM) methods for macrocells in LTE-Advanced have tracking area list (TAL) granularity. Therefore, a user equipment (UE) triggers a location update (LU) whenever it leaves its current TAL, and it is searched through paging (PG) with TAL accuracy. However, these procedures are not well-suited for small cells (SCs). The reasons are twofold. First, dense deployments of SCs imply that paging has a low probability to be successful in the first attempt, increasing the signaling overhead in the core network (CN). Second, smaller coverage areas lead to a higher mobility among cells, increasing the signaling overhead in the CN due to LUs. In this work, two LM schemes with fine granularity are proposed. These schemes update UE's location to a local anchor (LA) in a SC or tracking area (TA) basis, respectively. By increasing the accuracy of UE's location, a significant reduction of signaling overhead in the CN due to PG is achieved. Moreover, LUs to the LA are performed through direct X2-interface links to avoid signaling overhead in the CN. A versatile mobility model is developed and closed-form expressions for UEs' mobility metrics are found to validate the proposed schemes through variations of critical parameters such as TA/TAL configuration, UE's mobility patterns and cell residence times.This work has been supported by European Commission under the FP7 S2EuNet project and the Spanish Government through project TIN2013-47272-C2-1-RPacheco-Paramo, DF.; Akyildiz, IF.; Casares Giner, V. (2016). Local Anchor Based Location Management Schemes for Small Cells in HetNets. IEEE Transactions on Mobile Computing. 15(4):883-894. https://doi.org/10.1109/TMC.2015.2431717S88389415