Self Organizing Network Self Organizing Network

Self Organizing Network

The answer to the increasing complexity of network configuration, optimization and assurance processes.

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The Self-Organizing Network (SON) concept was introduced by 3GPP since the initial releases of LTE standardization, in order to help mobile access network operators to cope with the increasing complexity of configuration, optimization and assurance processes.

TIM has played an active role in 3GPP SON standardization activities since their beginning, combining the innovation vision with the “in field” experience in 2G/3G/LTE radio access design and optimization. The work of TIM has been mainly focused in promoting open, interoperable and flexible solutions.   

Based on this experience, in the last years TIM defined the “Open SON” approach, including “in house” software development, as a key initiative in the path toward virtualization and automation of the radio access network.

The complexity challenge and the “Self-Organizing Network” paradigm

Recent years have seen a rapid development of mobile access networks with an increasing complexity due to the following factors:

- Deployment of a plurality of radio technologies in many frequency ranges, some of which are shared between different technologies.
- Wide range of user equipment operating in the network, with different capabilities and features.
- Network nodes with different vendor implementations.
- Operational requirements and constraints for the full respect of the regulatory framework.

To face this increasing complexity new solutions are required. The objective of SON is, therefore, to realize a "closed loop" management, by collecting network elements quality indicators and, based on these, by identifying in "real time" the actions to improve the performance and/or solve local problems.

The picture below summarizes the complexity of TIM’s mobile network and the operating context of SON.

With the advent of 4G, the mobile access evolution gave a first response to the increasing complexity of network management, by introducing features “distributed” in network elements able to automatize some basic configuration and optimization processes (e.g. related to mobility support, traffic balancing, improvement of the radio signal coverage, etc.). The main feature of “distributed SON approach” is the capability of “fast closed loop reaction” to network events. In addition to “distributed SON” paradigm, a “centralized approach” was also introduced in the network management domain, in order to enable a unified and coordinated “closed loop” control over multiple network nodes, considering also different radio access network technologies, while allowing less stringent reaction timing.

TIM “Open SON” approach

In 2015 TIM defined an “Open SON” architecture, to be used as a reference for trials and deployment, based on the following pillars:

- Wide availability of open interfaces (i.e. Application Programming Interfaces, API) for an effective data/command exchange between the functional blocks of the architecture.
- Various levels of programmability, in order to assure the needed flexibility for managing a constantly evolving radio access network (the architecture includes applications developed “in house” by TIM, such as TIMPLAN tool supporting radio access design and optimization).

The “Open SON” architecture can be applied to both the legacy 2G/3G/LTE radio access networks and the evolution towards the so called “Virtual RAN”, based on the NFV (Network Function Virtualization) paradigm within the radio access domain.

The “Open SON” approach enables two different “closed loop” optimization processes:

- “Automatic Closed Loop” addressing basic optimization and configuration activities, for which a complete automation can be envisaged.
- “Human Closed Loop” addressing more complex activities, where TIM radio access specialists are supported by software applications (mainly developed “in house”), enabling also an effective control of automatic functions (through API).

The architecture defined by TIM is summarized in following picture:

Above mentioned activities are defined in order to reach two different targets:

- Improving radio network creation, design and optimization processes, by introducing automation and flexibility.
- Defining an “abstraction level” for radio access network domain, enabling the integration in End-to-End service oriented orchestration architecture.

The path towards 5G

Softwarization and virtualization paradigms have been preliminary applied in LTE radio access, while they will find a full exploitation in 5G mobile systems, whose standardization started in 2015, and which will drive further agility in network realization and optimization processes.   

LTE will evolve and will be complemented by new radio technologies, improving radio performance and enabling new services: bit rate up to several Gbit/s to allow multimedia contents, end-to-end latencies of few milliseconds to allow real-time services, high reliability for mission-critical and public-safety applications, massive connection of IoT devices.

In order to efficiently and flexibly support such a plurality of use cases, 5G access architecture will be designed in order to allow different deployment options (flexible functional split) and to aggregate/coordinate network resources adaptively by considering specific service needs (network slicing).

The “Open SON” approach will evolve in this context, in order to manage new 5G technologies and to extend the network management model, enabling an effective "network slicing" in the radio access domain.