US MNOs may get more 2.5 GHz and C-band spectrum despite satellite concerns

Ajit Pai, chairman of US regulator the FCC, announced in a blog post that the agency is veering towards opening up underused portions of the 2.5 GHz band for 5G. He has circulated an order to this effect, calling this the “single largest band of continuous spectrum below 3 GHz”. The vote will take place at the next FCC meeting on July 10.

Sprint owns over 110 MHz of 2.5 GHz spectrum in most markets and has demonstrated the ideal balance between capacity and moderate coverage that it provides for high speed mobile broadband. Sprint has used some of its airwaves for 4G and will deploy others for 5G, having successfully driven a bid to makes its particular band a 3GPP-designated 5G band, which is important for access to a broad device ecosystem.

“Midband spectrum, which offers an important combination of 5G coverage and capacity, is central to our strategy,” Pai wrote, saying that much of the band “has been unused for decades”. Last May, the FCC adopted a notice of proposed rulemaking (NPRM) to consider an updated framework for licensing spectrum in the 2.5 GHz band (2496-2690 MHz). It particularly focused on the Educational Broadband Service (EBS) spectrum that “currently lies fallow across approximately one-half of the United States, primarily in rural areas …. Subject to outdated regulations,” the FCC said at the time.

The FCC is also examining the midband 3.7-4.2 GHz spectrum – part of the far wider C-band in 4-8 GHz – which is used today by satellite companies and others mostly for video transmission.

A transfer of some of this spectrum to mobile broadband was first proposed in June 2018 and the issue came to a head earlier this month at a meeting hosted by the Technology Policy Institute in Washington DC. This was convened to hear various presentations on the proposal to restructure 180 MHz of the spectrum to help expedite roll-out of 5G in the US; 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, which 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 use higher frequencies, typically in the Ku band (11.2 GHz to 14.5 GHz) which enables smaller receive dishes. But the C-Band still 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 play-out. 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 4-8 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 reallocation 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 reallocated C-band spectrum over 5G.