Adjacent Channel Interference (ACI) occurs when extraneous power from a signal in one channel bleeds into an adjacent frequency channel. This overlap raises the noise floor for receivers tuned to the neighboring band, leading to poor signal quality, dropped packets, or reduced throughput. Engineers mitigate it through strict transmit filters, guard bands, and physical separation of antennas.
We're seeing high ACI on sector three because the new LTE carrier is transmitting too close to our guard band.
ACI is usually a symptom of poor transmitter filtering or operating transmitters too physically close to receivers on nearby frequencies.
Related terms
Guard band
An intentionally unused portion of the radio spectrum placed between active channels.
ACLR
A transmitter measurement comparing the power in the main channel to the power leaking into a neighboring channel.
ACPR
A metric that specifies how much of a transmitter's power spreads into adjacent frequency channels.