To address the femtocell discovery issue, an innovative approach based on cell-reselection-beacons is proposed in which the femtocell transmits a beacon on macro–only frequencies. The beacon is designed to trigger mobile device to search the small cell carrier and reselect to a small cell.
Further, beacon transmission is used to facilitate inter-frequency hand-in of macro users to small cells in active mode. Beacons solve key challenges of active hand-in namely (1) the absence of a reliable inter-frequency hand-in trigger and (2) the presence of PSC confusion arising from PSC reuse among small cells.
The Small Cells R&D group has performed extensive research in the area of femto mobility management, and conducted numerous simulations and lab experiments to demonstrate the effectiveness of these innovations in addressing the femtocell discovery issue in both idle and active modes.
As the density of NSCs can be very high and network configuration and topology may change rapidly, it is essential to have UltraSON (add link to UltraSON subpage) features to ensure robust operations of the small cells.