Adjacent Channel Power (Acp) Measurement Concepts - Keysight X Series Measurement Manual

Concepts
MSR Measurement Concepts

Adjacent Channel Power (ACP) Measurement Concepts

Purpose
Adjacent Channel Power (ACP), as it applies to LTE, is the power contained in a
specified frequency channel bandwidth relative to the total carrier power. It
may also be expressed as a ratio of power spectral densities between the
carrier and the specified offset frequency band.
As a composite measurement of out-of-channel emissions, ACP combines
both in-band and out-of-band specifications to provide useful figures-of-merit
for spectral regrowth and emissions produced by components and circuit
blocks without the rigor of performing a full spectrum emissions mask
measurement.
To maintain a quality call by avoiding channel interference, it is important to
measure and reduce any adjacent channel leakage power transmitted from a
mobile phone. The characteristics of adjacent channel leakage power are
mainly determined by the transmitter design, particularly the low-pass filter.
Measurement Method
This ACP measurement analyzes the total power levels within the defined
carrier bandwidth and at given frequency offsets on both sides of the carrier
frequency. Carrier bandwidth is automatically determined from radio format
and its parameter and each of the offset frequency pairs up to 6. Each pair may
be defined with unique measurement bandwidths.
For Meas Method of RBW, it uses an appropriate RBW and capture all of the
power in the carrier channel and the offsets. For Meas Method of integration
bandwidth (IBW), the channel integration bandwidth is analyzed using the
user defined resolution bandwidth (RBW), which is much narrower than the
channel bandwidth. The measurement computes an average power of the
channel over a specified number of data acquisitions, automatically
compensating for resolution bandwidth and noise bandwidth. The predefined
Measurement Noise BW and Method for Carrier values are defined in "Carrier
Power Measurement Bandwidth and Filter" on page 67.
If Total Pwr Ref is selected as the measurement type, the results are displayed
as relative power in dBc and as absolute power in dBm. If PSD Ref (Power
Spectral Density Reference) is selected, the results are displayed as relative
power in dB, and as absolute power in dBm/Hz.
56 Keysight N9083A & W9083A Measurement Guide