C-band loss pushes broadcasters to internet for video transport

The current US anguish over reallocation of some C-band radio spectrum in the 4 to 8 GHz range is being keenly watched elsewhere as China, South Korea and some European countries are poised to follow. The exact portion of spectrum affected varies by geography but in the US, the FCC has been considering transfer of part or all of the C-band in the 3.7 to 4.2 GHz range to impending 5G networks.

This was first proposed in June 2018 and has come to a head this month at a meeting hosted by the Technology Policy Institute in Washington DC to hear various presentations on the proposal to restructure 180 MHz of that spectrum to help expedite roll-out of 5G in the US. The issue now is more how to sell the spectrum and whether to accept a proposal from the C-Band Alliance (CBA) established in September 2018 by the four satellite operators, Intelsat, SES, Eutelsat and Telesat that provide the majority of C-band satellite services in the US. The CBA’s proposal to the FCC is to act as facilitator for clearing and repurposing that spectrum to accelerate deployment of next generation 5G services while protecting incumbent users and their content distribution networks in the US from potential interference. Interference to existing satellite services from mobile networks operating in adjacent spectrum is indeed one of the main concerns of broadcasters.

We are not talking here of DTH transmissions by operators such as Sky and AT&T’s DirecTV which have since the early days of satellite TV used higher frequencies typically in the Ku band (11.2 GHz to 14.5 GHz) which enables use of smaller receive dishes. The C-Band still however plays a vital role for broadcasters and content makers in live production, including on-site news gathering and sports, which often rely on one or more C-band satellite links to transport video to main studios prior to playout. Satellite downlinks in the C-band are then used in the field for returns feeds and confidence monitoring. In the US especially, affiliate stations and local cable operators also rely on the C-band for reception and distribution of live broadcasts as well as syndicated programming.

At these lower frequencies the C-band is more robust and less susceptible to rain fade, which is a particular advantage for operations in wet tropical climates where atmospheric moisture levels are higher. The large dish size is not an issue for such production and video transport use cases.

At first sight, this reallocation of just part of the C-band spectrum might not appear too critical because it still leaves the rest of the 4 to 8 GHz band with fairly similar properties, including resilience to atmospheric moisture. But in order to clear the reallocated bands and utilize the smaller remaining frequencies efficiently, new satellites will have to be designed and launched, which of course comes at a substantial cost. This has given providers of internet services and their vendors an opening to come in and take away this business before such satellites have even been launched.

Among vendors hovering over the decaying body of C-band spectrum for broadcasters is Haivision, which has come to prominence as a lead proponent of the SRT (Secure Reliable Transport) protocol designed to combine low latency with jitter and buffering protection for video streaming. Haivision contends that the C-band re-allocation will accelerate migration by broadcasters of contribution and distribution from satellite to the internet and that with maturation of SRT their experience will improve, enabling tighter integration with IP workflows. Ironically some of this contribution traffic will in future make use of that re-allocated C-band spectrum over 5G.