SON: The Key to LTE Commercialization

LTE is preferred by operators because it can reduce user delay, it can handle higher user data rates, it has higher volume and better coverage, maintenance costs are lower, and it can be smoothly evolved. However, these advantages do not guarantee the LTE will be successful commercialized. Better user experience and lower operation costs bring with them new challenges in terms of network deployment, maintenance, and implementation. Self organization is a newly introduced network concept that improves the intelligence of LTE networks.

What is SON?

Self organizing network (SON) is a complete set of network concepts for the development of LTE. It is designed for operators who are trying to reduce LTE network construction and OAM costs. It has now been extended to include the entire wireless network.

SON is a new idea for network construction, operation, and maintenance. It is based on the latest wireless technology and combines the advantages of traditional network planning and optimization. SON is mainly applied to LTE but can also be applied to 2G and 3G networks.

What Functions Does SON Have?

SON is characterized by self-configuration, self-optimization, and self-healing.  

Self-configuration means that there is little or no human intervention, from equipment installation to network access. It simplifies new station measurement processes, reduces the necessity for human intervention, and lowers construction needed for realizing plug and play. It substantially reduces the difficulty of deploying new base stations and OAM costs. A SON is capable of autonomously establishing transmission, authenticating nodes, installing and updating software versions, testing equipment, planning neighbourhoods, managing assets, and planning wireless parameters.

Self-optimization involves automatic optimization of network parameters. UE and eNB performance are measured in order to improve network quality and reduce optimization costs. Traditional optimization of OAM is based on assessments made by engineers after drive tests have been performed and simulation data analyzed. SON reduces the need to hire specialists and provides timely reminders and more accurate, detailed test data for network defects. It quickens the processing speed of the trouble ticket. Self-optimisation includes optimizing coverage and capacity, adjusting power transmission (or even shutting down cells) to save energy, detecting and reconfiguring to avoid conflict or confusion, optimizing mobility robustness and load balance, optimizing RACH, coordinating intercell interference and optimizing QoS.   

Self-healing, by definition, means the network can cure itself of network problems. Self-healing involves correlating alarms, locating root causes, detecting silent cells, detecting and compensating for faulty cells, and automatically tracking and diagnosing problems.

SON involves all aspects of network deployment, and makes traditional OAM methods more intelligent.

Why Does LTE Need SON?

The network element node of an LTE access network is evolved NodeB. eNB evolved from NodeB and RNC in 3G. X2 is the interface between nodes, and S1 is the interface of the core network. The compressed nodes considerably improve processing speed and efficiency in internal signalling. The full evolution of packet networks is a typical improvement in LTE networks. The 3GPP definition of SAE architecture specifies support for multiple wireless modes and the necessity for high speed, low latency, and optimized packet transmission. S1 is must be used to switch between different network standards, and X2 can be used to switch between LTE cells.

Because of LTE’s flat structure, eNBs encompass two original elements of the access network of 2G and 3G. Therefore, the number and complexity of wireless base station configuration parameters increases sharply. The cost of network planning, OAM, and upgrading is unacceptably high for operators. Also, the number of element nodes and eNBs increases significantly for the full-coverage LTE network. Because of the considerably weakened LTE frequency and penetration loss at high-frequency, small cells are used by leading telecommunication manufacturers and operators.

For full coverage and high capacity, HetNet is proposed. In addition to macro eNB, home eNB is introduced to extend indoor coverage and increase capacity in urban hotspots. Wireless relay stations are used for low-cost coverage. All these elements form a real heterogeneous network. Macro stations reduce the operation cost of SON, and home eNB meets the needs of SON in various scenarios. It is necessary to consider the affect of changing wireless environment, turn-on time and frequency flexibility, and power consumption for end users. These are challenges in traditional network planning, construction, and maintenance.

In addition, the coexistence of LTE, 2G and 3G networks needs to be taken into account to ensure smooth future evolution.

Many other issues cannot be dealt with by traditional maintenance methods. Such issues include capacity and power consumed as a result of wide coverage, flexible deployment and changed OAM modes based on home eNB, interference caused by hotspot coverage, and load adaptation. These increase labor and maintenance costs, and so operators have long awaited the arrival of SON.

SON’s Progressive Development

SON is an essential part of LTE development and commercialization. As a result of 3GPP and NGMN-related projects, issue-tracking and legalization are under way. There is still much work to be done in terms of functional collaboration and improvement. Commercialization involves a run-in period. ZTE, the leading provider of LTE equipment and solutions has been keeping abreast of relevant legislation and is conducting R&D on SON. As the result of substantial investment in R&D, ZTE has come up with a series of SON solutions.

SON is an essential driving force behind the evolution from mobile telecommunication networks to smart networks and is playing an increasingly important role in LTE.