Analytical Modeling for Mobility Signalling in Ultradense HetNets

Abstract

Multiband and multitier network densification is being considered the most promising solution to overcome the capacity-crunch problem of cellular networks. In this direction, small cells are being deployed within the macro cell (MC) coverage, to off-load some of the users associated with the MCs. This deployment scenario raises several problems. Among others, signalling overhead and mobility management will become critical considerations. Frequent handovers (HOs) in ultradense small cell (SC) deployments could lead to a dramatic increase in signalling overhead. This suggests a paradigm shift toward a signalling conscious cellular architecture with smart mobility management. To this end, the control/data separation architecture (CDSA) with dual connectivity is being considered for the future radio access. Considering the CDSA as the radio access network architecture, we quantify the reduction in HO signalling w.r.t. the conventional approach. We develop analytical models which compare the signalling generated during various HO scenarios in the CDSA and conventionally deployed networks. New parameters are introduced, which can with optimum value significantly reduce the HO signalling load. The derived model includes HO success and HO failure scenarios along with specific derivations for continuous and noncontinuous mobility users. Numerical results show promising CDSA gains in terms of saving in HO signalling overhead.