DL - 4G Americas

B.2.6 SELF‐ORGANIZING NETWORKS (SON)
SON concepts are included in the LTE (E-UTRAN) standards starting from the first release of the
technology (Rel-8) and expand in scope with subsequent releases. A key goal of 3GPP standardization is
the support of SON features in multi-vendor network environments. 3GPP has defined a set of LTE SON
use cases and associated SON functions. The standardized SON features effectively track the expected
LTE network evolution stages as a function of time. With the first commercial networks being launched in
2010, the focus of Rel-8 was the functionality associated with initial equipment installation and integration.
The scope of the first release of SON (Rel-8) includes the following 3GPP functions, covering different
aspects of the eNodeB self-configuration use case:
� Automatic Inventory
� Automatic Software Download
� Automatic Neighbor Relations: Each eNB can autonomously generate and manage its own
intra-frequency neighbor relation tables (NRTs) by requesting UEs to report neighbors’ identifiers
(PCI, CGI) and/or by sharing information with another eNBs through an X2 connection. This
feature benefits the operator by reducing the planning and deployment-related OPEX as it will
work as an automated planning and optimization tool on a daily operational basis.
� Automatic PCI Assignment: Physical Cell IDs are automatically selected to avoid collision and
confusion with neighbors to minimize pre-provisioning during LTE network deployments, as well
as to limit re-planning exercises during capacity extensions.
The next release of SON, as standardized in Rel-9, provided SON functionality addressing more maturing
networks. It included the following additional use cases:
� Mobility Robustness Optimization. Mobility Robustness Optimization aims at reducing the
number of hand-over related radio link failures by optimally setting the hand over parameters. A
secondary objective is to avoid the ping-pong effect or prolonged connection to a non-optimal
cell.
� Inter-RAT ANR: Extension of ANR techniques to support operation in Inter-RAT allows the
identification of neighbors from other radio technologies (UMTS and GSM) and other frequencies
utilizing UE measurements. This increases the value of ANR by reducing further the amount of
initial and ongoing planning necessary on the mobile network.
� Mobility Load Balancing. Related to Mobility Robustness Optimization is Mobility Load
Balancing, which aims to optimize the cell reselection and handover parameters to deal with
unequal traffic loads for both Intra-LTE and Inter-RAT scenarios. The goal of the study is to
achieve this while minimizing the number of handovers and redirections needed to achieve the
load balancing.
� RACH Optimization. RACH is the common channel used by the UE to access the network. To
improve the access to the system, RACH optimization allows the optimization of the system
parameters based upon monitoring the network conditions, such as RACH load and the uplink
interference. The goal is to minimize the access delays for all the UEs in the system, the RACH
load, the UL interference to other eNBs due to RACH.
www.4gamericas.org February 2011 Page 135