A spatial estimation-based handover management for challenging femtocell deployments

In next generation cellular systems, femtocell technology has been emerged as one of the leading deployment strategies aiming for a better indoor coverage and '5-bar' signal strength. Although widely studied in the literature, mobility and handover managements in these networks remain as a technical challenge in need of effective solutions. Especially in challenging indoor environments which consist of several walls and other physical obstacles, unnecessary handovers caused by unpredictable path losses are triggered in many situations. In order to manage the misleading handover decisions caused by these challenging topological infrastructures, a spatial estimation can be implemented into the handover algorithm. With this motivation, in this paper, we propose a new handover algorithm based on path loss measurements. To minimize the number of unnecessary handovers not only the measured path loss but also spatially estimated path loss values are considered for handover decision. Since empirical path loss models estimate path loss based on the average measurements, these models may not be suitable for challenging femtocell deployments. In this paper, instead of using empirical path loss models, Kriging interpolation methods are used so as to spatially estimate path loss measurements. The simulation results show that the proposed algorithm can minimize unnecessary handovers and lower the ping-pong handover rate compared with conventional scheme in challenging indoor environments.