# Self-Organizing Networks for 5G and Beyond: A View from the Top
## 2 SON Operation Rationale, Use Cases, Standardization, Architectures and Dimensioning
### Principles of Dimensioning and Designing a SON System
Decision about the needed SON applications and tuning of the latter according to the current network planning and optimization strategy. 3. Decision and prediction about the expected KPI improvement. Technoeconomic decisions such as system pricing, human resources and system deployment project time plans are taken as well but these are out of the scope of this paper. In terms of hardware infrastructure, the prementioned input shall lead to the decision of the servers' cluster (number/type of servers) hosting the platform and applica \begin{table}
\begin{tabular}{c c} \hline LTE to 3G layer IRAT handover rules & SON-related application according to 3 GPP defined use cases \\ \hline Circuit Switching (CS) fallback to 2 nd carrier & \\ \hline Packet Switching (PS) redirection to 2 nd carrier & ANR (Automatic Neighbor Relations) \\ \hline Cell reselection to 1 st carrier & \\ \hline GSM to 3G layer IRAT handover rules & SON-related application according to 3 GPP defined use cases \\ \hline GSM to UMTS: Cell reselection only (no handover) & \\ \hline UMTS to GSM: Cell reselection and no handover & ANR (Automatic Neighbor Relations) \\ \hline Define the value of admission control parameters (UMTS) & SON-related application according to 3 GPP defined use cases \\ \hline Power admission control settings: 1 st carrier: 85\%; 2 nd and 3 rd & \\ carriers: 75\% & \\ \hline Codes admission control: 90\% & \\ \hline UL/DL channel elements admission control: 95\% & \\ \hline Describe the load balancing features activated & SON-related application according to 3 GPP defined use cases \\ \hline Example: Intrafrequency load sharing & MLB (Mobility Load Balancing) \\ \hline \end{tabular}
\end{table} 
Table 1: Correlation of basic radio access parameters with SON applications. tions and providing disaster recovery, database replication, system orchestration and load balancing capabilities. We suggest that SON platforms interact with a geolocation database including all needed cell antenna directions, antenna type, cell name, site ID, operating frequency, BSC/RNC/MME/AMF hosting the cell, latitude, longitude and location parameters instead of the manual loading of such information since the latter might be error prone. Especially for the 5G case, static information about the equipment served in specific areas (either UEs or IoT sensors) can be added as well. After having installed the servers, the database and the SON platform software modules must proceed with the final IP planning of the system, ensure connectivity to the operators' data network, and enable connectivity with the OSS assigned to handle each technology, as depicted in Figure 6. This figure is an extension of Figure 4 and includes the coexistence of a UMTS and an LTE network. In case a 5G network is included, the design rationale is identical to an AMF interacting with the gNBs, the 5G OSS and the 5G KPIs database (db). Finally, the initial tuning of the platform and applications according to the desired policy must be performed before starting the system.