In a distributed approach, SON algorithms reside within the eNB’s, thus allowing autonomous decision making at the eNBs based on UE measurements received on the eNBs and additional information from other eNBs being received via the X2 interface. A distributed architecture allows for ease of deployment in multi-vendor networks and optimization on faster time scales. Optimization could be done for different times of the day. However, due to the inability to ensure standard and identical implementation of algorithms in a multi-vendor network, careful monitoring of KPIs is needed to minimize potential network instabilities and ensure overall optimal operation.
Radio Access Network Equipment Vendors offer D-SON to self-configure, optimize, and self-heal their proprietary equipment. D-SON runs on the Vendor’s edge equipment with limited scope and functionality. There are three few limitations to deploying only D-SON.
Limited Data accessibility: D-SON algorithms have access to a limited set of data stored on edge elements, eNodeBs for LTE.
Scope of operation is restricted to a small set of neighboring nodes so as not to negatively impact the performance of the network by overloading the inter-node communication paths (X2 interface for LTE.)
The Load and coordination overhead increase very quickly as the number of nodes increase. D-SON operates with limited knowledge and control.
Difficulty to handle multi-vendor configurations: D-SON Vendors optimize the performance of their own equipment using proprietary algorithms, data schema, and interfaces.
The standards don’t currently define the implementation of D-SON functions. So it is not possible to make parameter updates reliably across D-SON Vendors because there are unknown consequences to these black-box updates. This can cause misalignment between neighboring nodes. The problem is particularly strong in small-cell deployment scenarios when multiple-vendor cells are serving same coverage area.
These difficulties with D-SON limit the ability of the Operator to realize the full benefits of SON. D-SON uses a lower level, micro view of local regions of network performance to execute low-latency SON algorithms, such as Inter-cell Interference Coordination (ICIC), Automated Neighbor Relations (ANR), and some use cases of Energy Saving (ES), etc
