NTN Feeder Link
Also known as: Non-Terrestrial Network Feeder Link
Definition
The point-to-point RF or free-space-optical link connecting a ground-based satellite gateway to a non-terrestrial network payload, over which all user-plane and control-plane traffic between the terrestrial core network and the satellite's coverage area is carried.
Key Points
- Distinct from the service link (satellite-to-UE); the feeder link is exclusively gateway-to-satellite
- Typically operates in Ka-, Q-, or V-band to obtain the bandwidth needed for aggregate capacity, unlike lower-frequency service links
- In bent-pipe payloads, feeder link capacity is a hard ceiling on total satellite throughput regardless of service-link RF performance
- Gateway diversity (multiple geographically separated ground gateways) is the primary mitigation against rain fade outages on the feeder link
- Regenerative payloads reduce but do not eliminate feeder link dependency, since telemetry, command, and any non-cached traffic still transit it
Concept
A satellite gateway — typically a large tracking antenna at a teleport — maintains the feeder link to one or more satellites as they pass overhead or, for GEO, continuously. All traffic destined for users under that satellite's beams is uplinked over this single high-capacity link, then relayed by the satellite down to users over separate service-link beams. Because Ka/Q/V-band frequencies used for feeder links are more susceptible to rain fade than lower-frequency service links, gateway sites are chosen for favorable rain statistics and are often paired with a geographically distant backup gateway.
Explainer
The feeder link's throughput sets the practical capacity limit of a bent-pipe satellite regardless of how much service-link spectrum or how many spot beams the satellite has, because every bit destined for a user must first cross the feeder link. Operators size feeder link bandwidth against expected aggregate demand across all simultaneously active beams, which is why high-throughput satellite systems increasingly use multiple feeder links per satellite or move processing onboard (regenerative payloads) to reduce feeder link dependency for at least some traffic classes. Rain fade is the dominant availability threat: Ka/Q/V-band feeder links can see tens of dB of attenuation during heavy precipitation, which is why gateway diversity — routing around a rain-affected gateway to a clear one — is treated as a required design element rather than an optional enhancement for any feeder link serving latency- or availability-sensitive traffic. This matters operationally for CE verticals relying on NTN for continuous coverage: a maritime or aviation broadband service backed by a single-gateway feeder link inherits that gateway's local weather as a single point of failure, which is why teleport-grade deployments for these verticals are built with at least dual-gateway diversity from the outset.