Spectrum in the skies – The Battle for the C-Band

The US model of C Band-and the 5G FAST PLAN
On March 17, 2023 two satellites SES-18 and SES-19 were launched using a Falcon-9 rocket, heralding the completion of the FCC plan to re-engineer the C-Band spectrum for accommodating 5G services in the mid C-Band. This US model of C-Band usage neatly cut the C-Band spectrum in half, with new satellites funded by FCC and launched by SES and Intelsat. The purpose of creating the two parts – the lower half to be used for 5G and the upper half by C-Band satellites. Intelsat also completed launching its set of satellites, culminating with IS-37 and going live with the plan, which the FCC called as 5G FAST PLAN, with a targeted completion date of 31 Dec 2023.

The two worlds of 5G and C-Band satellite were separated by a small guard band of 20 MHz. The satellite signals being very weak, its receivers were required to use a sharp filter to filter out the LTE-5G signals. The problem remained that the lower part of spectrum from 4000 to 4100 MHz still had interference from 5G, and the new satellites had a higher EIRP. The lower band for 5G was subject to auctions while the C-Band users continued to use the spectrum with them under the ITU process.

India 5G in C-Band
The protagonists of 5G in India had been gunning for the US model (or split of the C-Band) to be adopted In India but apparently without any compensating payments to the satellite operators or receiving entities, which happened to be the broadcasters, MSOs, cable operators as well as VSATs. The demand for C-Band spectrum (called mid-band for 5G) was made as early as 2020, which understandably drew a lot of protests from the C&S fraternity as the C-Band is the backbone of India’s television eco-system, and there are over 900 channels transmitted in the C-Band.

The TRAI in its recommendations on the C-Band affirmed that the spectrum between 3700 and 4200 MHz should be preserved for C-Band satellites, and a guard band of 30 MHz below that should be used by satellite operators to design sharp filters and protect the entire C-Band. This was a very balanced recommendation taken after wide consultations and study by the TRAI, which is highly respected. The broadcasters, including their various associations, protested strongly that such a short guard band would still leave interference in the lower band of 3700–3800 MHz due to out-of-band emissions. Consequently, the operators were advised to preferably shift to over 3800 MHz to avoid interference – a term which came to be known as repackaging of channels. The broadcasters did also provide filters at their own cost.

Fast forward 2024 – The India model of 5G
Even though the 5G spectrum till 3670 MHz is still not used up in India, there is now a sudden resurgence to adopt the US model as the India model progressively by slicing the spectrum in an identical manner as in the US, with the first step being to slice till 3800 MHz (Plan n78). But there is silence as to how what was done in the US, i.e., launching of up to 10 new satellites, their funding and filters required would be accomplished.

In all fairness, the current move is that 100 MHz of spectrum now used by C-Band television of 3700–4200 MHz be set aside till 3800 MHz be used by 5G (i.e., implement Band n78 of 3GPP/ITU), without recognizing the fact that it will lead to all the filters installed so far becoming worthless, and the reception from satellites will be affected for an additional 100 MHz beyond 3800 MHz, i.e., between 3700 and 3900 MHz. How is this to be accomplished? There is talk of repackaging the channels in the remaining band beyond 3900 MHz. However, technical studies have so far suggested that the problem of LNB overloading cannot be overcome. Repackaging of channels – as was done last time by broadcasters will no longer be a solution as the entire C-Band was still intact. However, the fact remains that the 5G operators have made their intention clear to move to the N77 Band, which encompasses the entire C-Band (3700–4200 MHz).

5G in other countries has smoothly moved to the mmWave spectrum (30 GHz and above), and is no longer critically dependent on the mid C-Band.

Skirmishes in the Ku-Band
The LEO satellite constellations, which have a downlink in the Ku-Band, are now being licensed in India with two such constellations having already bagged the licenses and more to come. At the same time, the FCC in USA has been working on expanding the KU-Band in 12.2 to 12.7 and further till 13.25 GHz for mobile broadband or other expanded use (Leo Constellations). As these satellites transmit at very high power as compared to GEO satellites 36,000 km away, there have been reports of interference in reception by Ku-Band systems. However, this battle will take a couple of years to pan out.

Existential threat C&S ecosystem
Driven by high potential auction revenues of 5G, the C&S ecosystem in India is facing an unprecedented existential threat not witnessed anywhere else in the world due to the large number of broadcast channels as well as MSOs and cable operators being solely dependent on the C-Band signals.

Faith in regulatory agencies
India’s C&S system is much more satellite-dependent than was the case in USA. The industry continues to have full faith in the regulatory agencies in India and the Department of Space, which are the primary gatekeepers and drivers of India’s policies and regulation. We believe that a balanced decision will be taken considering that there continue to exist alternatives for 5G in additional bands and the US model or further slicing of the C-Band cannot be adopted in India.