The Active Antenna Systems (AAS) can enable system optimization to be adaptive to traffic demands and address network evolution issues through flexible software re-configuration of the BS and antenna system.

28.6273GPPRelease 17RequirementsSelf-Organizing Networks (SON) Policy Network Resource Model (NRM) Integration Reference Point (IRP)Telecommunication managementTS

SON mechanism with OAM support can be beneficial to optimize the inter-operability of AAS operations for the following AAS capabilities:

1) Cell splitting.

2) Cell merging.

3) Cell Shaping.

5.4.5.2 Use case 1: Cell splitting

Cell Splitting adopts higher order sectorisation (vertical, horizontal or a combination) to an eNB by changing the coefficients of the antenna elements of an active antenna system (AAS) to form more antenna beams, each beam may be presented by one cell.

The number of cells split by AAS from an original cell is not fixed, i.e. it is flexible based on the antenna capability.

The cells newly split from an original cell may or may not change the coverage of the original cell. In order to simplify the description, the term SO-Cell and SP-Cell are used to signify the original cell and the new cell split from the original cell in Cell Splitting.

As Cell Splitting operation is changing coverage, interference and handover settings for SP-cells and their neighbours, coordination with neighbour eNBs is needed to keep coverage and inter-cell interference under control.

The SP-Cells need to be manageable as soon as possible after they are split from the SO-Cell

The SP-Cell, once split from the SO-Cell, needs to be made known to management system as soon as possible, at least before AAS operation is applied to the SP-Cell.

The PCI of the SP-Cell may be or may be not the same as the PCI of the SO-Cell, however PCI conflict or confusion with other cells needs to be avoided. So the PCI or PCI range of each SP-Cell may be pre-allocated.

ECGI of each SP-Cell needs to be globally unique, it should be possible to be configured (or pre-configured) by OAM.

5.4.5.3 Use case 2: Cell Merging

Cell Merging is the contrary operation of Cell Splitting.

The number of cells can be merged by AAS into one cell is not fixed, i.e. it is based on AAS algorithm.

The cell merged from the original cells (in respect to Cell Merging) may or may not change the coverage of these original cells. In order to simplify the description, the term MO-Cell and MT-Cell are used to signify the original cell and the target cell merged from the original cells in Cell Merging.

As Cell Merging operation is changing coverage, interference and handover settings created by the cell under consideration, coordination with neighbour eNBs is needed to keep coverage, interference and handover settings under control.

The entity triggering the Cell Merging should be the same as the entity triggering the Cell Splitting for one active antenna system.

For Cell Merging, the MT-Cell is normally assigned with a new ECGI, but may inherit the PCI from one of its MO-cells. So, in the view of other (e.g. neighbour/adjacent) cells, the Cell Merging is the case that one MO-Cell (whose id is continuously used by the MT-Cell) enlarges its coverage while the other MO-Cells become unavailable.

5.4.5.4 Use case 3: Cell Shaping

Cell Shaping adapts the cell edge to load demand while maintaining the main coverage unchanged.

As Cell Shaping operation is changing coverage, interference and handover settings created by the cell under consideration, coordination with neighbour eNBs is needed to keep coverage, inter-cell interference and handover settings under control.

If the eNB executes Call Shaping in a fully unconstrained manner, it may decrease the reliability of handovers with its neighbour cells since in this case an appropriate handover margin cannot be guaranteed. So, the eNB may be pre-configured with alternative coverage configurations and the eNB may autonomously select and switch between these configurations using AAS operations including Cell Shaping. the number of allowed coverage configurations is limited.

The eNB needs to consider each allowed coverage configuration, to:

1) make the right selection for the coverage change during Cell Shaping; and

2) set the proper handover margin with neighbour cells.

Therefore, each pre-configured coverage configuration should include a state identifier and the range of the parameters (e.g. tilt, power) affecting the coverage range.