High density small cell deployment creates more cell boundaries and potentially more handover events. UltraSON avoids excessive handovers while ensuring robustness of necessary handovers.
With Frequent Handover Mitigation feature, small cells will identify UEs that handover frequently. For those that ping-pong among a set of small cells (shown by repetition of Cell ID in handover history), their handover parameters will be adjusted to prevent these ping-pong events. For those that handover among a set of different small cells (no repetition of Cell ID in handover history), such as vehicular UEs, they will be redirected to the macro layer.
UltraSON also supports Mobility Robustness Optimization (MRO) by tracking handover successes and failures (and their causes) over time (per UE category). Small cells can then adjust their handover parameters to reduce future handover failures.