China Mobile: Building a National Backbone Transport Network in Western China

About China Mobile

China Mobile Communications Corporation (China Mobile) was established on April 20, 2000. With registered capital of RMB 300 billion and assets exceeding RMB 1 trillion, currently China Mobile boasts the world’s largest mobile network and subscriber base. Having mobile telephony, data, IP telephony and multimedia services as its major lines of business, China Mobile has also been granted with the license to operate internet services and international communications access services. In addition to basic voice service, the Company also offers many value-added services such as fax, data and IP telephony. Its famous consumer brands include GoTone, Easyown and M-Zone. By the end of 2012, China Mobile had more than 1.07 million base stations and more than 700 million customers.

Seizing Opportunities

China Mobile has the world’s largest WDM/OTN bearer network, and this network is the cornerstone of China Mobile’s mobile network. China Mobile led the way by deploying large-scale national and provincial backbone WDM networks as early as 2000. After 2006, China Mobile started building a 3G TD-SCDMA mobile network and vigorously developed key customer services. Because the existing metropolitan MSTP and backbone WDM network could not keep up with the rapid growth of data services, China Mobile took steps to deploy multilayer backbone WDM networks and metropolitan OTN networks. This improved the bearing capacity of the entire network. Since 4G LTE was deployed in 2013, the demand for data bandwidth has increased. China Mobile is determined to upgrade its 10G WDM/OTN to 100G OTN and use the 100G OTN in both backbone and metropolitan areas to handle a high volume of data.

100G OTN is a state-of-the-art optical transmission technology and has the largest capacity in the optical communications industry by far. 100G OTN is capable of 100 Gbit/s single-wave transmission and up to 8 Tbit/s single-fiber transmission. 100G OTN standards and technology have been well developed, and the world’s leading optical communications equipment vendors, including ZTE, can provide 100G solutions. A number of 100G networks are currently being operated by international carriers.

Cover Diversified Environment

China Mobile’s NBN in western China stretches from Xinjiang in the north to Hainan in the south. It operates in both sub-arctic and tropical areas. The western backbone network has G.652 and G.655 optical fibers and traverses 20 provinces. The total length of the network is 22,000 km. The network, which can be regarded as an optical network system, has the largest span and most challenging conditions in the world.

From 2G and 3G wireless services to 4G LTE and full-service operation, the western backbone network is responsible for bearing and transmitting all China Mobile provincial services in western China. It has a strategic role in China in promoting economic development and attracting investment in the western region.

After 10 phases of construction, the single-link capacity of the western backbone network has been upgraded from the original 800G to the current 8T, achieving a leapfrog development.

Delivery Services and Values

Adhering to the idea of  “Deliver Quality Services to Customers”, ZTE proposed 100G OTN based on ZXONE 8700 CX71. First, ZTE had to fully understand China Mobile’s requirements for the western backbone network, provide a planned solution, and provide line designs.

100G OTN has the following features:

●    a combination of soft decision and hard decision. ZXONE 8700 provides two 100G line solutions—soft decision and hard decision—for adapting to the complicated optical fiber line conditions of the western backbone network. This lowers the network construction cost while ensuring the transmission performance at the same time.

●    largest number of slots and highest bandwidth utilization. ZXONE 8700 CX71 cross-connect subrack has as many as 94 100G service slots, the industry’s largest number of slots that can support a cross-connect capacity of 9.4T (the actual access capacity of 7.4T and the ratio of the customer side to the line side is 1:1). 100G OTN boasts the highest bandwidth utilization compared with the listed OTN devices from other vendors, thus contributing to the full use of backplane bandwidth resources, reduction of the cross-connect capacity usage, and protection of investments.

●    optimal dispersion tolerance and PMD tolerance. With the dispersion tolerance of +/-70000ps/nm and the maximum DGD tolerance of 180 ps, 100G OTN is the optimal one in the industry, which means that it costs least under the same PMD. In addition, it needs no dispersion compensation or PMD compensation below 3500 km transmission, so as to guarantee a reliable long-distance backbone transmission.

●    full service access types. 100G OTN offers various access services to meet different access requirements. 10G customer side boards support the access of 10GE-LAN/WAN/10G POS/STM-64/OTU2/2e, while 40G customer side boards support the access of 40GE-LAN/40G POS/OTU3.

●    comprehensive service and system protection. ZTE developed a series of service and system protections, including SNCP-I, SNCP-N, SNCP-S, Och 1+1, OLP, OMS 1+1, Och SPring. Moreover, 100G OTN provides 4:2 shared protections, which can tolerate larger system damage.

Establish Strategic Partnership

Before the launch, China Mobile conducted many laboratory tests and weighed the strengths of vendors in terms of equipment and technology, engineering implementation, and network planning. Finally, China Mobile chose ZTE to construct the NBN in western China. The strategic partnership between China Mobile and ZTE indicates China Mobile’s recognition of ZTE’s 100G OTN R&D, engineering, and technical service capabilities and represents ZTE’s strong competitiveness in 100G OTN market.

Focus on Coastal Areas

While helping China Mobile build the NBN in western China, ZTE has also invested in coastal areas and has undertaken a 100G OTN provincial backbone project for China Mobile Zhejiang (Zhejiang Mobile).

After analyzing the current businesses and future network plans of Zhejiang Mobile, ZTE has proposed a quality 100G OTN network solution. In this solution, ZXONE 8700 CX71 is used to build the 100G OTN provincial backbone intelligent network. With 9.4T electrical cross-connect capacity, 94 service slots and 8T single-link bandwidth, ZXONE 8700 CX71 also supports the WASON intelligent control plane.

Zhejiang Mobile approved the proposal and established a strategic partnership with ZTE to build the 100G OTN provincial network.