Navigating World Radio Congress 2023: What’s at Stake for SatCom?

The 2023 World Radiocommunication Congress in Dubai, UAE (WRC-23) is on the horizon. Set to take place between November 20th to December 15th, 2023, the month-long conference will revise the international treaty governing radio frequency (RF) spectrum. Critical agenda items will be addressed at this conference which will have a direct impact on the future of the wireless ecosystem and the satellite communications (SatCom) sector. Among agenda items such as spectrum for intersatellite links (ISLs) and Earth Stations in Motion (ESIM), is the possible identification of the extended C-band (upper 6 GHz – 6,425 to 7,125 MHz) – long used for fixed satellite services (FSS), Mobile satellite service (MSS) downlinks, and WiFi 6E – for International Mobile Telecommunications (IMT) systems or mobile phone and internet access services.  

The agenda items under consideration highlight the intersection of established uses of spectrum as well as emerging services enabled by the satellite sector. The following are the key agenda items under consideration.

Support for Intersatellite links (Agenda item 1.17)

This agenda item proposes investigating the possibility of allowing satellite-to-satellite transmissions within the current FSS 11.7-12.7 GHz, 18.1-18.6 GHz, 18.8-20.2 GHz, and 27.5-30 GHz frequency bands. Some proposals are being considered for expanding the scope to include the C-band, which could boost the operational and spectral efficiency of C-band satellite operations through the effective reuse of spectrum for transmission between space stations. Ultimately, this would allow satellites in different orbital slots to communicate with each other and ground stations via radio frequency (RF). This will be tremendously beneficial for operators with significant existing satellite infrastructure with long lifecycles (Geosynchronous Earth Orbit (GEO) and Medium Earth Orbit MEO) satellites) and leveraging a multi-orbit solution, like SES S.A (MEO-GEO) or the recently formed Eutelsat Group (GEO-LEO). This may also be what legacy SatCom players need to compete and work alongside with emerging Low Earth Orbit (LEO) mega-constellations the likes of Starlink, Lightspeed, Kuiper, IRIS2, the SDA, and more which will leverage optical inter-satellite links (OSILs), see Insight-7043 “Embracing Light: The Satellite Industry’s Transition from RF to Optical”.

Harmonizing satellite spectrum for Earth Stations in Motion (ESIM) (Agenda items 1.15 & 1.16)

The WRC will also consider the use of 12.75-13.25 GHz frequencies for satellite broadband communication on Earth Stations in Motion (ESIM) such as aircraft and ships with agenda items 1.15. With agenda item 1.16, a regulatory framework for Ka-band (26.5-40 GHz) ESIM connecting with Non-Geostationary Orbits (NGSO), essentially LEO and MEO constellations, is being explored which will allow for appropriate regulatory, technical, and operational provisions for ESIM to co-exist with other spectrum users. This agenda item is timely as the exponential growth of LEO and MEO orbit Ka-band constellations is rapidly growing and supporting increasing demand for bandwidth used for continuous connectivity along travel routes. This also highlights the common issue of technological advancement outpacing the enhancement of regulatory frameworks, as satellite terminals operating with NGSO connections are already widely implemented on aircraft, ships, and other vehicles. Clearly, this has upside potential for the Aviation in-flight-connectivity (IFC) and Maritime connectivity sectors. Both segments benefit from low latency LEO services for multimedia access as well as multi-band, multi-orbit solutions which can provide critical connectivity, redundancy, and even differentiated service offerings.

Optimization of the C-band (Agenda items 1.2 &1.3)

One of the most critical items on the agenda is the potential identification of the upper 6 GHz band for use by IMT systems in region 1 (Europe, Middle East, and Africa). This has implications not only for current satellite services using the C-band, but also for future initiatives such as the proposed IMT initiatives for WRC-27 which will target the full Ku-band. The upper C-band is already used by companies like Viasat+Inmarsat to operate feeder links for their MSS network, while other companies such as Intelsat and AsiaSat, use the C-band for critical satellite services such as broadcast, air navigation, meteorology, emergency response, mobile backhaul, as well as telecommand applications and for radionavigation signaling. In this way, the adoption of the upper 6 GHz for IMT systems could lead to significant interference with satellite receivers operating in the same bands and eventually displace satellite C-band services. Furthermore, the clearing of the bands by satellite systems will be difficult. Foremost, movement to other satellite frequency bands is an uncertain path, as the other satellite frequency bands are congested and require additional frequency coordination with multiple regions. Alongside this, replacement of GEO satellite systems could take several decades given their lifespan and would prove costly for operators currently deploying C-band payloads.

There is much at stake for SatCom with the upcoming WRC-23. The continued identification of the C-band sets a precedence of uncertainty for satellite operators in that their systems and spectrum will be stripped for terrestrial systems with ever increasing spectrum requirements. This could also reinforce the notion that the industries as they currently operate, would eventually collide in competition for spectrum. Alongside the work being done by the 3rd Generation Partnership (3GPP) to bring satellite and terrestrial systems into a globally available network ecosystem, where satellites serve as an extension of the terrestrial system, the writing on the wall may very well be that satellite networks will eventually need to partner with terrestrial networks to access spectrum and unlock unified 6G services.

Given this outlook, satellite services are providing critical and reliable services globally from national defence to global trade and closing the digital divide which can only be done with sufficient preservation and protections in place. Therefore, for SatCom operators, there is a clear need for WRC-23 and WRC-27 to defer IMT systems to consider solutions such as spectrum refarming and optimization of existing spectrum before moving on to identifying new bands. Most prominent is the use of existing spectrum such as the 2 GHz allocation in the 3.4 to 3.6 GHz range, and in the millimetre wave (mmWave) bands. These bands can also serve the same purpose as the upper C band for mobile operators with the provision of high-density local area capacity.