What is ACLR?
ACLR (Adjacent Channel Leakage Ratio) is the ratio of the transmitted power on the assigned channel to the power measured on an adjacent channel after applying a root raised-cosine filter. It is one of the most critical RF performance metrics defined by 3GPP for both base stations and user equipment, directly determining how well a transmitter confines its energy within its allocated spectrum and avoids interfering with other users or systems.
How Does ACLR Work?
ACLR is measured by transmitting a fully loaded signal (e.g., a 5G NR waveform with the maximum number of resource blocks) and then measuring the power that leaks into the first and second adjacent channels. A root raised-cosine (RRC) matched filter is applied at the receiver to emulate real-world channel selection. The result is expressed in dB — higher values indicate better performance. 3GPP specifies minimum ACLR requirements that vary by frequency band, channel bandwidth, and device class.
Use Cases
5G NR and LTE device type approval and conformance testing, base station RF performance verification, spectrum coexistence analysis for adjacent operators, power amplifier design optimization, and regulatory compliance measurements.
3GPP / Standards Reference
3GPP TS 38.101-1/2 (NR UE radio transmission), 3GPP TS 38.104 (NR BS radio transmission)
Related Terms
ACLR | ACPR | SEM | OFDM | EVM
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This glossary entry is part of the 5GWorldPro Complete 5G Glossary. To go deeper into 5G architecture and technology, explore our 5G Training courses.
