An Evolved Mobility Robustness Optimization Algorithm for LTE Heterogeneous Networks

Small cells have been integrated into the LTE system of 3GPP (3rd Generation Partnership Project), and the mobility situation in the resulting Heterogeneous Networks (HetNet) is more challenging due to more complex cell topologies and radio channel conditions. The outdoor deployment of small cells will also typically suffer user speed variations which impact handover performance a lot. A conventional tuning of handover parameters by a Mobility Robustness Optimization (MRO) algorithm suffers limitations in this new situation. In this paper, we propose a soft-metric assisted and network controlled handover optimization mechanism, which is self adaptive to the user speed variation in a quick manner. Simulations demonstrate that the new mechanism can save many handover failures compared to the conventional algorithm.