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AMF – Access and mobility management function
A component of the 3GPP core network architecture that
manages user equipment registration, authentication,
identification, and mobility. AMF also terminates non-access
stratum signaling.
AM/PM distortion
Undesirable distortion that causes signal degradation in
a communications system, typically as the result of the
interaction between an amplifier’s phase response and the
power level (or amplitude) of the input signal.
Antenna reciprocity
A theory that states that the transmit properties of an antenna
will be identical to the receive properties of that antenna in a
given medium.
AUSF – Authentication server function
A major component of the 5G core network used to facilitate
security processes. The AUSF authenticates UEs and stores
authentication keys.
AWG – Arbitrary waveform generator
Electronic equipment used to generate signals for injection into
a device under test (DUT) to characterize its performance.
Backhaul
The part of the network responsible for transporting
communication data between the baseband unit (BBU) and
the core network. Connects smaller outlying networks with the
core network. Backhaul was often proprietary in earlier cellular
generations but is moving to ethernet in 5G.
Base station network emulator
A tool for simulating protocol and network traffic in a test
environment. Works in concert with UE emulation and channel
emulation to provide an end-to-end system for testing and
measuring 5G network performance at scale.
BBU – Baseband unit
A component of the base station. Equipment which handles
radio communications and radio control processing functions.
The baseband unit converts data into a digital signal and sends
it on to the remote radio head (RRH), which then converts it into
an analog signal. In a C-RAN architecture, the baseband unit is
usually geographically separated from the radio head.
Beam acquisition
The process of discovering and connecting with UEs. This
process is substantially changing in 5G with the deployment of
highly directional antenna arrays and beamforming techniques.
Beamforming
The method of applying relative phase and amplitude shifts to
each antenna element to shape and provide discrete control
of the direction of a transmitted beam. Beamforming requires
communication channel feedback to implement real-time
control of the beam.
Beam steering
A set of techniques used to focus the direction and shape of a
radiation pattern. In wireless communications, beam steering
changes the direction of the signal and narrows the width of
the transmitted signal, typically by manipulating relative phase
and amplitude shifts of the signal through an array of multiple
antenna elements.
Carrier aggregation
A major feature introduced with LTE-Advanced, enabling
mobile network operators to combine multiple carriers in
fragmented spectrum bands to increase peak user data rates
and overall capacity of the network.
CATR – Compact antenna test range
Equipment for testing of antennas at frequencies when difficult
to obtain far-field spacing. The CATR uses the 3GPP-approved
indirect far-field (IFF) test method to overcome the path loss
and excessive far-field distance issues associated with 5G
cellular communications.
CE – Channel emulator
Electronic equipment that enables real-time performance
testing of wireless devices and base stations. Channel
emulators simulate the impairments of real-world radio channel
conditions to validate the performance of base stations,
chipsets, and devices.