China Mobile Hong Kong: A New Milestone in 4G LTE

On July 20, 2012, China Mobile Hong Kong (CMHK) announced that it would cooperate with ZTE and Ericsson to introduce TD-LTE technology into CMHK’s existing FDD-LTE network and build a converged, dual-mode network. ZTE would provide network equipment and solutions in the main business districts, including Hong Kong Island and Kowloon. CMHK’s network is the first dual-mode LTE network in Asia Pacific and also China Mobile’s first commercial TD-LTE network.

Ouvm has predicted that TD-LTE will account for 25 percent of all worldwide LTE connections by 2016. In its 2012 Q1 report, Infonetics predicted that TDD and FDD will account for almost 70 percent of worldwide equipment revenue by 2016. China Mobile is the leader in TD-LTE. At Mobile World Congress in February 2012, Li Yue, president of China Mobile, revealed for the first time the TD-LTE development roadmap in China. He said that China Mobile would expand its TD-LTE trials to 13 cities throughout 2012 and increase the number of TD-LTE base stations to more than 200,000 by 2013. It would do this by building new stations and upgrading existing ones. China Mobile selected the highly competitive Hong Kong market to test its commercial TD-LTE network, which indicates that China Mobile might soon be ready to launch TD-LTE on a large scale.

ZTE won the CMHK project by virtue of its integrated end-to-end solutions, experience in constructing dual-mode commercial networks, and strong after-sales service.

Key Indicators Are Met

Tests showed that the average downlink FTP throughput of a Cat4 terminal used by ZTE is stable at 102 Mbps. A peak throughput of 110 Mbps (the theoretical maximum) is also possible. ZTE connected to Ericsson’s existing EPC network architecture to test functionality and performance, and the results were far better than China Mobile expected. ZTE also ran connection tests with more than 30 terminal and chip suppliers.

PS Handover

The redirection method is generally used in the industry to enable handover between LTE and GSM/UMTS networks or between FD-LTE and TD-LTE networks. When switching from one network to another, the user has to release all network resources before accessing the internet on another network. This definitely affects user experience. The ideal solution is PS handover, which guarantees continuity during handover by preserving resources in the target cell before the switch. The user’s data session is not interrupted, and the handover is not perceived by the user. In May, ZTE completed the world’s first FDD/TDD LTE bi-directional PS handover test, which provides a foundation for seamless communications between 4G and 2G/3G.

World’s First Broadband, Multicarrier, Super-High-Output-Power Base Station

The distributed base station provided by ZTE comprises a baseband unit and RF unit. The baseband unit is based on the advanced SDR platform and supports TD-LTE and FD-LTE. It has highly integrated, large-capacity baseband process boards, each of which supports up to six 20 MHz, 2 × 2 MIMO cells. A base station supports a maximum of 36 cells, the highest capacity in the industry. To coordinate with multiple carriers, the transmitting power of an RF unit is increased 25 percent (100 W for every two channels). The base station supports an operational bandwidth of 60 MHz and up to four carriers. This provides hardware support for the RAN-sharing solution.

Mature RAN-Sharing Solution

The RAN-Sharing solution has received much attention from operators over the years. Limited spectrum resources and the boom in data services have meant that operators are trying to maximize spectrum use by integrating spectrum resources.  They may flexibly allocate bandwidth within 60 MHz, share the mobile network, or use different core networks and charging systems to provide customized services. The RAN-sharing solution requires network equipment to support multiple carriers. The TD-LTE base station provided by ZTE supports up to four carriers and has super-high output power, which meets the requirements of RAN sharing.

Multimode Networks Share Antenna Feeders

ZTE uses existing GSM and FD-LTE machine rooms and antenna feeders in order to avoid building new sites. Base stations can be installed indoors or outdoors. If baseband and RF units are fixed on L racks, an indoor TD-LTE base station only takes up a space of 40 cm2. If an existing shelter is being used and space is limited, the RF unit can be installed outdoors and can be connected with the baseband unit through optical fiber. This reduces feeder loss. CMHK’s GSM and FD-LTE networks use broadband antennas, so TD-LTE base stations share antennas and feeders with FD-LTE and GSM base stations to make the most of existing resources. This ensures a stable network and speeds up network construction.

Multiple Clock Solutions

Precision synchronization between TD-LTE base stations is very important. A high-precision clock puts high requirements on the transmission network and base station installation. ZTE has a number of clock synchronization solutions for different scenarios. In typical scenarios, a common solution for synchronizing GPS clocks is connecting the feeder with GPS antenna. This is the most mature and most widely used solution. In atypical scenarios, where feeder construction is difficult or the baseband module is too far from the GPS antenna, ZTE connects the GPS antenna via optical fiber. This makes construction easier and eliminates loss caused by a long feeder. The solution supports 1588V2 clock transmission so that many base stations can share one clock source. Also, the clock can be shared via the existing transmission network, which saves network construction cost.

Rich Local Delivery Experience

ZTE has much experience in delivering big projects in Hong Kong. In a large turnkey project, ZTE provided CSL Hong Kong with solutions for network planning, site design, land acquisition, site construction, site debugging/opening, project maintenance, and network OAM. More than 2000 3G base stations were put into service within 12 months, which was a record in Hong Kong. In a third-party evaluation, CSL was found to have the highest network quality in Hong Kong and the third-highest network quality in the world. This proves ZTE’s strength in LTE planning, design, and network optimization.

ZTE is capable of highly efficient logistics. The company has a 2000 m2 warehouse in Kwai Chung, Hong Kong; and equipment production lines in Shenzhen, which neighbors Hong Kong. These allow fast delivery and convenient custom clearance. ZTE has experience implementing large mobile projects in Hong Kong and maintains close partnerships with many Hong Kong and overseas outsourcers. ZTE also has hundreds of engineering teams.