Multiple SON use cases
have been specified by 3GPP for self-configuration, self-optimization and
self-healing areas. In general self-configuration use cases are important at
earlier phases when providing coverage whereas self-optimization and healing
consider quality and capacity and they are more relevant when network usage
increases.
The SON use cases are
specified by three working groups according to their responsibilities: RAN2,
RAN3 and SA5. RAN2 addressed only one use case: Minimization of Drive Tests
(MDT) while other cases are defined by RAN3 and SA5.
While self-configuration
features are mainly specified in 3GPP Release 8 and include Automated
Configuration of Physical Cell Identity (ID) and Automatic Nei hbour Relation Function,
self-optimization is the core content of 3GPP Release 9, where focus is on Mobility
Load Balancing (MLB), Mobility Robustness Optimization (MRO) and RACH optimization.
SA5 deals with self-healing features:
Cell
Outage Compensation (COC) is part of Release 10. Release 10 work started in
2010 and provides MRO and MLB enhancements and Minimization of Drive Tests
(MDT).
Release
11 SON still focuses mainly on failure scenarios; that is MRO in inter-RAT and HetNet
plus minimization of ping-pong events; avoiding ping-pongs will reduce the
number of unnecessary mobility events (i.e. signalling) and decrease UE power
consumption. The main focus of Release 11 MDT is QoS verification.
Energy
Saving (ES) has been specified since Release 9 for Intra-LTE. However, an
Energy Saving Release 10 Study Item extends ES to more scenarios, like the
multi-RAT one; in addition mechanisms for waking up cells which are in ‘energy
saving’ state have also been discussed. The Energy Saving Work Item is in
Release 11.
LTE-Advanced features are
introduced in Release 10: those include carrier aggregation, uplink and
downlink MIMO enhancements, relay nodes and optimized interworking between cell
layers in heterogeneous network. Self-configuration and Automatic Neighbour
Relations are specified for relay nodes. While the SON use cases specified for
macro apply nicely to small cells as well, SON work Item in Release 11
specifically addresses multi-layer scenarios to tailor SON use cases to
heterogeneous networks even further.
