Carrier-to-interference ratio is the ratio between the received carrier power and the aggregate interfering power that shares the same or adjacent channel resources.

Key Points

It compares wanted signal power to interfering power.
It is a direct indicator of interference tolerance.
It affects throughput, availability, and modulation choice.
It is relevant in crowded wireless and satellite environments.
It is one of the core metrics in link engineering.

Concept

C/I matters because a link can have enough raw signal but still fail if other transmitters or reflections dominate the channel. The metric is therefore a practical way to express how much interference headroom the link has. It is often analyzed together with fade margin, modulation scheme, and antenna discrimination.

Explainer

For satellite and wide-area systems, C/I is a daily engineering concern rather than an abstract metric. Beam reuse, adjacent-channel emissions, and environmental conditions all change the ratio. If C/I falls too far, the network has to reduce modulation, accept more errors, or re-engineer the interference environment.

Cite this entry

Carrier-to-Interference Ratio. ConnectedEarth Knowledge Base. https://connectedearth.space/knowledge-base/carrier-to-interference-ratio/ (updated 13 September 2026).