Technical data

Chapter 5 161
Adjacent Channel Power
W-CDMA Adjacent Channel Leakage Power Ratio (ACLR)
Measurements
Adjacent Channel Power
W-CDMA Adjacent Channel Leakage Power Ratio
(ACLR) Measurements
One of the most important measurements on RF signals for digital communication
systems is the leakage power into the adjacent channels. A quantitative figure of
merit is adjacent channel power ratio (ACPR) or adjacent channel leakage ratio
(ACLR). The ACLR measurement determines how much of the transmitted power
is allowed to leak into the first and second neighboring carriers (high side and low
side). Leakage of RF power into adjacent channels or bands can cause major
interference to occur on another carrier’s network.
The measurement of ACLR is defined as the ratio of the average power in the
adjacent frequency channel to the average power in the transmitted frequency
channel. It is reported in dBc (dB relative to the main carrier).
Test models are used to have pre-defined test conditions for base station
conformance test of ACLR. Under 3GPP TS 25.141, five types of test models are
defined. Each test model consists of PCCPCH (Primary Common Control Physical
Channel), PICH (Paging Indication Channel), CPICH (Common Pilot Channel),
SCH (Synchronization Channel) and some DPCHs (Dedicated Physical Channels).