Study on impact of Vertical Sectorization on mobility and existing MRO performance

Mobility robustness optimization (MRO) is one of the Self Organizing Network (SON) features that automatically adjusts network mobility configurations by detecting problems and correcting handover (HO) parameters. The existing MRO operation is based on stationary network deployment assumption where handover error statistics are continuously monitored between cell-pair borders as long as the cells shape and neighbor relationships are maintained. In the dynamic deployment case, where cell deployment layout is changing by following the nature of the traffic distribution, existing neighbor relationships might not be maintained and new neighbors could appear in the network. In such cases, MRO instances and counters used before deployment change might not be valid any longer for the new network layout. In this paper work, we have studied the impact of deployment and network layout change introduced by Vertical Sectorization (VS), a typical Active Antenna Systems (AAS) feature, on the performance of MRO. A crucial aspect here is the treatment of MRO statistics while introducing a change in the network deployment layout. The study gives information if there is a need to enhance the existing MRO concepts by introducing inter-node coordination during execution of a deployment change in the network.