How Colombia’s operators are re-using existing spectrum for modern 4G services

In this analysis, Opensignal has looked at how three national operators in Colombia use their spectrum holdings in one of the legacy 3G bands — 1900 MHz (band 2), also known as the PCS band. We observed that mobile operators have been shifting their use of this band from 3G to 4G technology and also have moved to larger channel widths for 4G connections which helps to boost the mobile experience of users.

Repurposing the 3G spectrum to newer mobile technology generations in Colombia is especially crucial in the context of much anticipated 5G roll-outs, as these will rely on strong 4G foundations in the initial stages. Plus, more spectrum dedicated to 4G services will help improve users’ mobile experience. This is especially important because Colombia is yet to assign new 5G-capable spectrum to mobile operators due to auction delays. As we only looked at the1900 MHz legacy band, the analysis didn’t cover new operator WOM because it doesn’t hold spectrum licenses in these bands. 

Note – a previous version of this Insight used data on spectrum holdings from an external spectrum database of holdings. However, this information on holdings was not up to date. Therefore, we now have updated this Insight to use exclusively Opensignal data — this represents the actual spectrum holdings used by smartphone users rather than operators’ original spectrum license allocation.

Claro and Tigo shifted their 3G use to the edge of their spectrum holdings

We observed that since March 2021, both Claro and Tigo dedicated more of their spectrum blocks in the 1900 MHz exclusively to 4G services, while focusing their 3G use in the edge blocks of their spectrum holdings. At the same time, we haven’t seen any major changes in how Movistar used its spectrum blocks for 3G connectivity.

Looking at Claro’s 3G use, the operator used two 5 MHz blocks in March 2021 for 3G services — 1935-1940 MHz and 1940-1945 MHz. However, in March 2022, we observed a shift in the concentration of 3G readings towards the 1940-1945 MHz block entirely, while the 1935-1940 MHz saw barely any 3G readings. This is a significant change, as we saw 31.3% of Claro’s 3G readings in this block in 2021. 

Our data shows that Tigo has phased out 15 MHz in the 1975-1990 MHz range, which was previously used for 3G connectivity. Interestingly, Tigo also set aside 10 MHz for 3G use only, in the 1965-1975 MHz range, on the edge of its spectrum holding block — with 80.1% of readings focused in the 1965-1970 MHz block and 19.9% in the neighboring 1970-1975 MHz block. 

As we saw Colombia’s operators use fewer spectrum blocks for 3G services, we also looked at the spectrum used for 4G connectivity. Looking at Claro, the operator increased the use of 4G services in its 1935-1940 MHz — we saw this block used in nearly all of our 4G readings for Claro in March 2022, compared to 43.7% a year earlier. We also observed Movistar dedicating its 1950-1955 MHz block to 4G services more frequently — as we saw an increase in 4G readings for this block from 18.3% to 51.3% of the total Movistar 4G readings on the PCS band.

As we saw Tigo concentrate its 3G use in the 1965-1975 MHz, we observed barely any 4G readings within this range in March 2022. Tigo seemed to use these blocks for 4G services back in March 2021, as we saw about 15% of 4G readings on both of these blocks. There’s a shift from the 1965-1975 MHz range to the 1975-1980 MHz block — which saw an increase in the share of readings observed on Tigo’s network from 47.3% to 72.8%. Similar to the 1980-1990 MHz range, where readings increased from over 85% per 5 MHz block to nearly 100%.

With more spectrum blocks in the 1900 MHz band dedicated to 4G use, it is easier for operators to have larger contiguous spectrum blocks which 4G technology can better utilize to improve users' experience compared with more fragmented holdings. With this in mind, we also looked at the proportions of channel widths used by each operator in March 2021 and March 2022. We observed the most significant change for Claro — in 2021 we saw 5 MHz bandwidth used in 55.9% of our 4G readings and 10 MHz — in 35.3% of 4G readings.

A year later, we observed the channel width of 10 MHz in 88.3% of 4G readings for Claro, while 5 MHz bandwidth became scarce in our 4G readings. This aligns with what we found about Claro’s spectrum blocks being repurposed to 4G. The 1930-1940 MHz range seems to be exclusively dedicated to 4G use, after repurposing the 1935-1940 MHz between March 2021 and March 2020. This gives Claro the opportunity to use a continuous 10 MHz block for its 4G connectivity. 

Looking at other operators, we also saw significant shifts towards using higher spectrum bandwidths for 4G connectivity. The proportion of 4G readings using 10 MHz bandwidth used by Movistar increased from 23.5% to 47.4% — which aligns with the increase in 4G readings we saw in the 1950-1955 MHz block. As for Tigo, it used the 15 MHz channel more commonly than 12 months earlier, as the proportion of readings increased from 47% to 69.2%. 

As our previous research in South Korea and Europe shows, contiguous 4G spectrum is more amenable to carrier aggregation, which will contribute to an improved 5G experience for Colombia’s mobile users in the future. 

More spectrum used for 4G is key for future 5G deployments in Colombia

Colombia’s government and national operators are preparing to introduce 5G services in the country. The government is hoping to complete the much-anticipated spectrum auction in 2022, while Claro, Movistar and Tigo have all been trialing 5G. Operators aim to repurpose the 3G spectrum for more efficient 4G technology now, as our analysis shows, and in time for the upcoming 5G deployments. However, the progress of spectrum refarming in the 1900 MHz bands is challenging, given how a large proportion of Colombia’s population still relies on 3G services. 

Refarming the 3G spectrum to 4G will have a positive impact on users’ overall mobile experience and set the foundation for upcoming 5G deployments. These will require well-developed 4G infrastructure and spectral assets — especially in the initial roll-out stage when Colombian operators are more likely to launch 5G services on non-standalone networks.