China Mobile Optimizing LTE Networks

 

With the explosion of mobile communication, networks now need to handle a lot more data. This has been the impetus for large-scale LTE deployment. In 2014, China Mobile deployed its LTE networks widely.

After the first phase deployment of LTE networks, China Mobile put them into commercial use. However, many problems arose due to a discrepancy between the plans and actual construction. These problems were low performance, inadequate network coverage, complaints about voice services, and a huge impact on network security and performance caused by major events.

As a major equipment supplier of China Mobile’s LTE networks, ZTE leveraged its experience in product development and delivery and addressed these problems. ZTE delivered a complete LTE network optimization service, helping China Mobile survive the fierce competition in the market.

 

Rapid Network Performance Improvement

After deploying large-scale LTE networks, China Mobile encountered problems with engineering quality and network planning that meant network performance was not up to expectations. Therefore, rapidly improving network quality became the primary task for China Mobile.

ZTE helped China Mobile quickly improve network performance by handling network alarms, verifying planning information, adjusting antennas and feeders, and checking configuration parameters. All this laid a good foundation for China Mobile to commercialize its LTE networks.

The Xuzhou branch of Jiangsu Mobile (Xuzhou Mobile) deployed the initial phase-I LTE network in early 2014. However, they were not satisfied with the network performance. In seven of ten areas, the download speed did not meet the requirements, nor did the average SINR in eight areas meet the requirements. Overall, only 20% of requirements were met. To address this issue, a ZTE team optimized the network over the course of a month. This helped Xuzhou Mobile increase the average downlink throughput of its LTE network to 37.35 Mbps and increase the average SINR to 14.86 dB. The network O&M also significantly improved, reaching an advanced level in China.

 

Building Advanced LTE Networks

By cooperating with ZTE to build advanced LTE networks in key cities, China Mobile has gained experience in network O&M and has promoted it across the country to rapidly improve network performance.

In Dali, Yunnan province, China Mobile and ZTE have established a joint network optimization war room. After three months of network optimization, Dali Mobile has increased its LTE network coverage rate from 96.22% to 97.31%, its average SINR value from 13.21 dB to 15.12 dB, and its average download speed from 26.32 Mbps to 38.11 Mbps. Network performance and user experience have been greatly enhanced.

 

Increasing LTE Coverage

As LTE networks use high-band spectrum that has a relatively poor penetration, they are inadequate for extending coverage in many scenarios. This greatly affects user experience and the reputation of the LTE network. The basis for good LTE network experience and user satisfaction is to provide users with access to LTE networks anytime and anywhere. Therefore, increasing coverage is the focus of LTE network optimization.

ZTE’s LTE network planning and optimization solution can leverage its small cells, integrated microcells, and small antennas to address coverage issues in typical residential areas and CBD. For instance, Beijing Financial St. is a typical CBD area spanning 1.846 km². Existing macrocells in Beijing Financial St. could not meet coverage requirements; therefore, ZTE made a plan for integrated microcells. After these were deployed, the ratio of signal strength with RSRP greater than -101 dBm increased from 79.32% to 97.16%, and the ratio with SINR greater than -3 dB remained unchanged at about 96.71%. In this way, network coverage was significantly increased.

 

Optimizing Interference to Improve Network Quality

Network interference severely affects network performance and user experience. ZTE’s LTE interference optimization involves optimizing regional centralized interference, single-cell interference, D-band interference, and F-band interference.

After LTE interference optimization, Beijing Mobile has decreased the number of cells with F-band interference to 139, a decline of 29.08%. The total number of cells experiencing interference has decreased by 42.59% to 213.

During the interference optimization, ZTE has also found that external interference with the network can be caused by illegal use of cordless phones. To solve this problem, ZTE has developed an anti-interference algorithm that mitigates the effect of such interference on the network.

 

Optimizing CSFB to Make Smooth Voice

China Mobile has not yet deployed VoLTE on LTE networks, so it enables voice service by falling back to a GSM network through CSFB. CSFB may result in high delay and low call success rate because it involves multiple network elements, several scenarios, and complex processes. To address these issues, ZTE’s CSFB solution has been designed for whole-process signaling analysis and special optimization of wireless network coverage, neighbor cell configuration, and boundary frequency points. The optimization also involves configuring key parameters for the access side, paging, and interoperability. All this improves CSFB performance.

 

Securing Network Operations to Safeguard Major Events

At concerts, sporting events, large exhibitions, and festivals, a heavy concentration of users often leads to a surge in voice and data traffic. This significantly affects the network and greatly diminishes user experience. ZTE has developed a special solution to ensure network performance for major events. The solution involves adding temporary sites, adjusting network coverage, and configuring network parameters. In 2014, China Mobile worked with ZTE to safeguard major events such as Dalian International Beer Festival, Zhuhai Air Show, Internet Conference, and APEC Conference.

At the Dalian International Beer Festival, China Mobile and ZTE established a joint team for guaranteeing network security. The LTE network in Dalian withstood the challenges of a large volume of traffic during the festival. On the opening day, the network withstood its maximum of 800 users. The indicators on the NMS showed that the RRC setup success rate of the sites around the Xinghai Square exceeded 99.8%, the cell radio connection rate exceeded 99.7%, the intra-system handover success rate exceeded 99.5%, and the paging congestion rate was 0. These good results were recognized by China Mobile. The network optimization service starts with basic optimization and makes an in-depth analysis of extended coverage, interference, CSFB, and major events to help China Mobile completely improve its LTE network performance and user experience.