Telkomsel is boosting capacity for 4G, by refarming 3G spectrum in the 2100 MHz band

5G has arrived in Indonesia. In May 2021, Telkomsel launched commercial 5G services in limited parts of the country, followed by Indosat’s 5G rollout in Surakarta. XL also announced the launch of its 5G service in five locations last month. Meanwhile, other national operators — 3 and Smartfren — are still preparing their networks to adopt the new technology. However, insufficient access to 5G spectrum remains one of the key challenges across operators; Indonesia has allocated only about a third of what is required to support 4G and 5G deployments, according to the Ministry of Communication and Information. And to overcome the spectrum crunch, Indonesian operators are looking to make use of their existing spectrum holdings by repurposing some or all of the spectrum that they are currently using for 3G and/or 4G networks.

Opensignal is examining how different Indonesian operators have been using the existing 3G spectrum to accelerate 4G and future implementations of 5G. In this analysis, we have looked into Telkomsel’s spectrum usage to understand its approach and the impact on its users’ mobile experience.

Our data shows that Telkomsel used to rely on three 5 MHz downlink channels on Band 1 (the 2100 MHz band) to provide 3G services across 40 of some of Indonesia’s largest cities. However, over the past eight months the operator has re-used, or refarmed, the majority of that spectrum to boost the capacity of its 4G networks, and now relies mainly on a single 5 MHz downlink channel for 3G.

We then looked at Telkomsel’s usage of Band 1 across these cities and found that, at the beginning of the year, the operator had already refarmed two out of three 5 MHz downlink channels from 3G to 4G in 10 cities — Kota Bandung, Kota Tangerang, Kota Sukabumi, Kota Malang, Semarang and Surakarta from Java, Sumatra’s Palembang, Lesser Sunda Islands’ Denpasar and Mataram, and Kota Yogyakarta. However, by the end of August 2021, the operator had repurposed 10 MHz (2x5 MHz) in 35 out of 40 cities including the capital city of Jakarta, Kalimantan’s Balikpapan and Kota Tasikmalaya, Maluku Islands’ Ambon and Papua’s Kota Jayapura among others. Medan, Makassar, Palangka Raya, Tarakan and Kota Gorontalo were the only exceptions, where the operator continued to use 15 MHz of spectrum in the 2100 MHz band for 3G.

Telkomsel users see improvement in mobile experience
Looking at the change in users’ mobile experience between January and August, Opensignal users on Telkomsel across the above-mentioned 40 cities saw their 4G download speeds rise by 16.8%, on average. In August they observed an average 4G Download Speed of 21.6 Mbps compared to 18.5 Mbps observed in January, which suggests the spectrum refarming, among multiple factors, contributed to the positive impact on users’ mobile experience. 

On the other hand, our users’ average 3G Download Speed did not see a significant change between January 2021 and August 2021 (in absolute terms), which indicates that 5 MHz of Band 1 spectrum is sufficient for Telkomsel to support the existing traffic on its 3G network.

Indonesia’s operators are taking different approaches to mitigate spectrum scarcity
While Telkomsel has been refarming spectrum in Band 1 to add capacity for 4G usage and using the new spectrum in Band 40 (2.3 GHz) to launch 5G, its competitors have taken different approaches. For example, unlike Telkomsel, Indonesia’s 4G-only operator Smartfren plans to use the new spectrum in Band 40 to increase the capacity and quality of existing services and expand its footprint outside currently operational areas. On the other hand, XL hasn’t secured this new spectrum and will be using Dynamic Spectrum Sharing (DSS) technology on the 1800 MHz and 2100 MHz spectrum for 5G. Meanwhile, Indosat has reportedly launched 5G in 1800 MHz, and signed agreements for the proposed merger with 3. Nokia and 3 have partnered to deploy spectrum sharing (DSS) technology for 3G and 4G on its live network.

Refarming the existing spectrum could be advantageous as 3G-only users upgrade to 4G
While Indonesia is making strides to adopt fifth-generation networks, a proportion of its population still relies on old 3G network technology. This means Indonesian operators face challenges with switching off 3G networks completely and re-using the 3G spectrum for more efficient 4G technology now, and in time for 5G. However, our data shows that migrating 3G-only users to 4G and refarming 3G spectrum will have a positive impact on users’ overall mobile experience.