With the rapid growth of mobile communications, deployment and maintenance of mobile networks are becoming more complex, time-consuming, and expensive. In order to meet the requirements of network operators, self-optimizing/organizing networks (SON) technology was developed and continues to grow in importance as operators discover how much simpler and cost-effective it is to have networks with self-configuration, self-optimization and self-healing capabilities. But as the awareness of SON’s positive impact grows, so do the expectations of what it can achieve.
SON is considered a necessity in future mobile networks (LTE and beyond) due to increased cost pressures. The main drivers are to reduce CAPEX and OPEX, which would otherwise increase dramatically due to the expanded number of network parameters which has to be monitored and set, and the rapidly increasing numbers of cell types (e.g. pico-, micro-, macro-, and femto-), which will coexist in the network.
However, passed are the days where operators simply expect “typical” SON functions such as Automatic Inventory, Automatic Software Download, Automatic Neighbor Relation, and Automatic Physical Cell ID Assignment. They have evolved with the industry to demand a richer suite of SON capabilities for macro- and micro-networks overlaid on, and interoperating with, existing mobile networks.
Today, SON systems are highly capable of taking on a major role in automating functions in the three main phases of mobile network operations – planning, configuration, and operation. The aim of SON was to minimize the amount of manual human work by performing tasks in each of these phases as autonomously as possible. Here is an overview of how SON systems currently work:
In the planning phase, the locations of base stations and network devices, and the associated parameters, are determined before the equipment is actually installed. The links between base stations and network devices are also designed. SON systems derive optimum values for the parameters so that the amount of manual intervention is minimized.
In the configuration phase, the base stations and network devices are installed and the parameters for each unit of equipment must be set and tested. SON systems provide the means for detecting equipment, downloading software, performing authentication, and testing equipment autonomously.
In the operation phase, network optimization and monitoring/maintenance occur. SON systems are able to automate these operations as much as possible.
However, these SON functions are now considered standard and network operators now require more sophisticated capabilities and advanced use cases from SON systems such as Mobility Load Balancing, Random Access Channel (RACH) Optimization, and Cell Outage Detection and Compensation, in order to further improve the management of their networks and secure optimal ROI from their SON deployments.
Mobility Load Balancing (MLB) – This key technology intelligently spread user traffic across the systems’ radio resources in order to provide quality end-user experience and performance while optimizing system capacity. With MLB, if the network detects an imbalance in traffic loads between cells, it automatically adjusts the operation parameters in accordance with the load in each cell. The goal is to handover some of the terminals connected to a base station with high-load cells to one with low-load cells in order to better distribute the total load. This improves the use of system capacity and increases average user throughput. Compared to manual intervention, MLB makes it possible to deal with redistributing load concentrations quickly and thoroughly.
Random Access Channel (RACH) Optimization – The performance of RACH influences the capacity of the entire mobile network. Therefore, an optimized RACH configuration enables network performance gains and end-user benefits through reduced connection time, higher throughput, and better cell coverage. By automating the optimization of RACH, maximum performance is achieved with no operator intervention. The network will dynamically adapt to network changes and end-user behavior to always deliver the best possible performance and resource utilization.
Cell Outage Detection and Compensation (CODC) – In the case where an eNodeB is unable to recognize being out of service and fails to notify network operators of the outage, CODC provides automatic mitigation of the eNodeB downtime. Cell Outage Detection typically combines multiple mechanisms to determine whether an outage has occurred in order to identify latent fault cases where network operators are unaware of the issue. Cell Outage Compensation activates after standard recovery techniques have failed to restore normal service. Previous generations of network infrastructures have experienced failures of which operators had no knowledge of until they receive a notice from customer support indicating problems in the field. CODC empowers operators to identify and address faults before the end-user does in order to obviate outages, which can be detrimental to a networks’ integrity and user base.
There are additional advanced SON features which are being supported by 3GPP’s upcoming Release 9 and 10 SON functionalities. These include enhancements to existing use cases and definitions of new use cases such as Mobility Robustness / Handover Optimization, Enhanced Inter-cell Interference Coordination, Minimization of Drive Testing, and Energy Savings, to name a few.
As LTE continues to evolve to support new services such as Voice-over-LTE and other Rich Communication Services, mobile networks will continue to increase in complexity and sophistication to the point where management of the complete network environment may seem convoluted even to the most experienced network engineers without the help of innovative SON solutions. The addition of multiple cell types into the RAN, not to mention their coexistence with WiFi access technologies, makes it imperative for network equipment manufacturers to develop SON solutions for heterogeneous networks (HetNets).
Future mobile networks will be marked by a drastic change in user behavior triggered by the rampant growth of bandwidth-hungry applications such as video streaming and multimedia file-sharing. Network management will undoubtedly be more complex given that it’s going to be an environment comprised of network operators, equipment manufacturers, access providers, service providers, software developers, content providers, and customers. This trend manifests itself as tremendous pressure on network operators in terms of satisfying demands for capacity and increasing Quality of Experience.
For SON solution providers to maintain a competitive advantage, they must offer solutions that don’t address the current needs of mobile networks, but meet the requirements of future mobile networks. They’ll need to address the long-term necessities covering multiple aspects across the broader scale of network operations including planning, deployment, optimization, and maintenance. Only then will they play a key role in satisfying the expectation of what SON is able to achieve.