Telkom is the Indonesian state-owned telecom operator offering enterprise, mobile (via its Telkomsel brand), home (mostly via IndiHome), wholesale, and international (via WIB) communications services. Telkom is the perennial leader in the country's fixed and mobile telecom markets.
Major operators across the globe have been advancing their digital transformation in recent years. Telkom also seeks transformation by focusing on digitalization (developing and deploying digital services), optimization (enabling more agile and efficient operations) and experience (bringing the best user experience).
Initial Achievement in Optical Access Network Construction
Telkom's home services grow fast under its IndiHome brand. Since 2009, Telkom and ZTE have started a close cooperation to provide high-speed connectivity services through fiber-to-the-home (FTTH) deployment and diverse video services using ZTE's IPTV platform. This greatly enhances user satisfaction, expanding Telkom's subscriber base to more than 4.7 million. Accounting for 64% of home service revenue, IndiHome has become Telkom's star brand service.
Amid a rapidly developing broadband market, Telkom launched a large-scale FTTH construction in 2009 to provide users with higher bandwidth and better service experience. After nearly ten years of development, Telkom has boasted an optical distribution network (ODN) with a coverage capacity of around 16 million lines. The vast fiber resources have given Telkom huge advantages in business operation and have further boosted its IndiHome brand. To accelerate its digital transformation, Telkom has also actively explored fiber-to-the-mobile (FTTM) deployment that can quickly expand mobile backhaul transport services while fully utilizing existing fibers.
FTTM Analysis and Implementation
FTTM relies on a passive optical network (PON) to deliver the backhaul from wireless base transceiver stations (BTSs) to the transport network. It brings significant advantages to fixed network operators who have substantial fiber resources, allowing them to use the resources to expand new services. FTTM has high requirements for transmission metrics including clock synchronization and QoS assurance.
2G, 3G and 4G BTSs coexist in Telkom's existing network, and their service bandwidth and interfaces are different. 2G BTSs use E1 interfaces, while 3G and 4G BTSs adopt GE/FE interfaces.
ZTE's FTTM solution is compatible with the in-service BTSs and ensures smooth network evolution. By allowing TDM services to be carried over a PON, the solution can make full use of existing fiber resources.
Frequency and Time Synchronization
The Telkom network meets the technical requirements of synchronization. Clocks are imported through Metro-E, synchronization data is transferred over GPON, and the baseband units (BBUs) resolve the synchronization data for BTSs.
Timing information is transferred over PON. The network reference clock is input from the OLT side and after being traced by a phased-lock loop, acts as the public clock source of the entire PON. The local system clocks of ONUs are synchronized with the clock source. The PON ranging mechanism supports IEEE1588 v2 protocol, providing high-precision frequency and time synchronization for the BTSs connected to ONUs.
QoS Assurance Mechanism
BTSs require the transport network to have traffic classification, service differentiation, and bandwidth multiplexing capabilities. ZTE's FTTM solution enables GPON to differentiate services and set proper priorities for them to guarantee their respective bandwidth. Commercial verifications show that GPON has strict QoS assurance. For one-way end-to-end traffic, the transmission delay is less than 50 ms, the delay jitter is shorter than 10 ms, and the packet loss ratio is lower than 1%. In the signaling plane, the transmission delay is less than 100 ms, the delay jitter is shorter than 10 ms, and the packet loss ratio is lower than 0.1%.
BTSs also require the transport network must meet carrier-grade reliability requirements. Protection switching should take less than 50 ms to complete so that services can be rapidly recovered without affecting customer experience. PON is a typical tree topology and supports type B/C protection in the FTTM solution.
Compared with traditional IP transport, FTTM not only meets basic mobile backhaul requirements such as QoS, synchronization, multi-service transport and high reliability, but also has advantages in terms of simple topology, ODN reuse and fast site activation.
Commercial FTTM Deployment
Telkom has deployed ZTE's FTTM solution to achieve integrated access to TDM and IP data. The commercial FTTM has become the world's largest GPON-based integrated network for mobile backhaul and fixed access and also the industry's first GPON transport network for all service scenarios.
The FTTM solution employs ZTE's multi-unit access terminals including F820 and F829 to connect to the Node Bs and BTSs in the downlink and the OLT in the uplink. From the OLT, the uplink connection extends to Metro-E and IP/MPLS networks (Fig. 1).
Currently, Telkom's mobile transport network contains about 180,000 BTSs of different standards, and roughly 30% of them are backhauled through a GPON. The successful implementation of the ZTE FTTM solution won a high recognition from Telkom. With its deployment still expanding, the solution will help Telkom further increase the utilization of its GPON network.
Exploring New 5G Applications of FTTM
With the advent of the 5G era, Telkom, as a telecom industry leader, is also actively building its presence in the 5G landscape. Telkomsel, a Telkom subsidiary, already carried out 5G tests in 2018. The three typical scenarios of 5G—eMBB, mMTC and URLLC—all depend on the support of optical networks. Moreover, as 5G networks aim to provide a higher-speed experience for a denser crowd, BTSs will be smaller and deployed increasingly closer to end users. That means more fiber resources will be needed in the 5G future. Therefore, being a stable and economical transmission medium, optical fibers can greatly meet the transmission needs of customers in the 5G network architecture.
25G WDM-PON will be a better solution for 5G FTTM fronthaul, and its related technical standards are being formulated. The solution has many attractions.
—Multiple channels: WDM PON supports 20 pairs of wavelengths, and a single PON port can connect to 20 active antenna units (AAUs).
—PON: Passive optical network and passive components can reduce costs and improve O&M efficiency.
—P2MP: The point-to-multipoint tree topology can save trunk fiber resources.
—Colorless ONU: A colorless ONU can be flexibly deployed to provide high-quality, big-bandwidth and long-haul transmission.
TITAN, ZTE's flagship new-generation OLT, supports various PON technologies. TITAN delivers both 5G fronthaul and backhaul services, and is also compatible with 3G and 4G services. It supports P2MP 10G PON/50G PON or P2P transmission in the downstream direction and provides n×100GE or OTU4 interfaces in the upstream direction. Telkom can use TITAN to upgrade its existing 4G LTE sites to 5G and backhaul its 5G services.
TITAN can also offer enhanced functions like MEC, network slicing and SDN/NFV, providing stronger technical support for Telkom's 5G rollout down the road. At present, Telkom has completed the first-phase test with TITAN. With its new architecture and technologies, TITAN will soon be ready for Telkom's 5G deployment.
Telkom's large-scale commercial deployment of FTTM is a good example of successful FTTM application, because it fully reuses fiber resources of home broadband and simplifies network while ensuring service quality. As long-term partners, Telkom and ZTE keep exploring new technologies and solutions together to help Telkom lead the 5G race.