More Intelligent LTE Networks with SON

Increasingly Complex Wireless Networks

In 1896 when M.G. Marconi carried out the world’s first long-distance wireless communication experiment, he could not have imagined that only 100 years later, wireless communications would become an indispensable part of everyday life.  Wireless networks have evolved to such a degree that wireless antennas can now be seen on buildings, utility poles, and on special iron towers every 200m in many downtown areas. Operators may deploy thousands of base stations to support more than 10,000 cellular areas in a major city in China.

With the constant expansion of mobile networks and continuous technological upgrades, mobile network technology has developed from the AMPS system—put into use in 1983—through AMPS/TACS, GSM/CDMA and UMTS/TD-SCDMA/CDMA2000, into LTE. The speed of wireless communication has soared from 2bps in the Marconi era to 1Gbps. Even if a Marconi telegraph was used to transfer data unceasingly from 1896 to the present, the amount of information transferred to date would be far less than what an LTE user can access in a single minute.

With the evolution and dense deployment of networks, there are more and more optimization parameters and wireless environment evaluation indexes. Network complexity is also growing exponentially. The coexistence of network systems further increases this complexity.

With a variety of 2G, 3G and LTE networks in use, resource allocation and scheduling scenarios are like a dispatcher at a transportation center who needs to organize and coordinate a variety of transport modes from ox carts to jets to provide continuous transport for many customers. This requires the dispatcher to master the characteristics of each mode. In highly complex networks, manual network configuration used in the 2G/3G era as well as traditional O&M and optimization based on drive tests have gradually been overloaded. Automatic network configuration is now a trend in the post-3G era.

The Introduction of SON

In 2007, 3GPP started to research use cases and standards proposals in RAN3 and RAN5 to introduce self-organizing networks (SON) into LTE networks. In its R8 and R9 versions, 3GPP has completed all the definitions and specifications of various scenarios, including automatic discovery of adjacent cells and automatic physical cell identity (PCI) allocation. Scenarios and technology programs for optimizing mobile robustness, coverage, capacity, and random access channel will be discussed in the specifications of the follow-up R9 and R10 versions. Mobile load balancing and minimum drive test and energy savings will also be discussed. Currently, the basic technical direction is to implement network self-organizing, self-optimizing and self-healing by enhancing measurement capacity of terminals and strengthening exchange of configuration and load information between base stations.

ZTE has deployed SON functions such as automatic discovery of adjacent cells in its LTE products. In-depth research has been done on network stability, improved user perception and system cost and energy savings, and much technology has been accumulated. This helps to develop a more cost-efficient, reliable and intelligent network solution.

ZTE’s Uni-RAN solution, based on the unified SDR hardware and software platform, fully supports self-detection, self-discovery, self-configuration, self-linking, self-update and self-testing in base stations—from system power-up to service provisioning. This full-function support avoids complex on-site configuration required in traditional base station commissioning and greatly reduces human error. 

A key feature of SON technology is that base stations can automatically make decisions, change cell topology and wireless configuration, and perform handover by collecting user measurement reports and exchanging information with adjacent cells. However, a network with these features only has the basic characteristics of a self-organizing system. There are no external commands (such as human interference), and new structures such as cell range, adjacent cell topology, and user distribution are formed through mutual coordination. In the case of large-scale nodes, the convergence speed of a self-organizing system depends on the algorithm, interaction period, and effect manifestation period. If the algorithms are not designed properly, the system may exist in a long-term shock or chaotic state. Algorithms for automatically discovering adjacent cells, optimizing mobile robustness, balancing mobile load can cause chain reactions. ZTE has performed full system simulations and has carefully designed algorithms and delay indicators that make the system responds quickly to disturbances and optimally balance signaling load and function coordination within the convergence time. These algorithms and indicators also support stable and continuous network improvement.

When designing and implementing SON functions, ZTE understands that operators need to continue to provide services using their existing networks and that data configuration and optimization needs to happen as quickly as possible during LTE deployment. With SON functions deployed by ZTE, the relevant 2G/3G adjacent cell parameters in the LTE base stations can be quickly configured. The newly deployed LTE network can also complete data configuration for existing 2G/3G networks in the shortest time and initiate the appropriate interoperability functions.

Measurement done by enhanced user terminals in current SON technology increases overall measuring and signaling traffic as well as terminal power consumption to a certain extent. This reduces system capacity. But if the measurement operation is performed too frequently, user experience is affected (e.g. terminal battery life is shortened). Using a unique CDT/MR data acquisition and analysis tool called NetMax, ZTE incorporates a proprietary SON minimum-user terminal selection function. This reduces the user terminal measurement and signaling interaction to a minimum so that users do not feel the impact of these features.

Future SON: End-to-End Optimization

ZTE is a leading supplier of LTE equipment and a primary contributor to LTE standardization. ZTE is committed to promoting standard LTE technologies, including SON. In future SON technology, self-organization and self-optimization will be expanded from the current wireless network to the entire end-to-end network. Network coverage optimization will be expanded to end-to-end service-awareness optimization and service-based coverage optimization and adjustment. ZTE will continue to drive the growth of LTE standards and technologies and provide operators with mature end-to-end equipment and solutions. ZTE will continue to help operators deploy LTE services faster and more effectively and create new business opportunities.