Atec Spirent-TAS5600 - Manual (Page 6)

6 TAS5600 Universal Interference Emulator
In order to verify that UMTS User
Equipment and Node-Bs conform to
3GPP standards, various co-channel
and adjacent channel interference tests
are required. These conformance tests
verify a minimum level of receiver or
transmitter performance in the presence
of co-channel and adjacent channel
Accurate Interferer Generation
interfering signals. The types of signals
required can include uplink and
downlink WCDMA signals, GSM signals
with propagation effects, single and
dual tones, or AWGN. The level
accuracy required for these interfering
signals is demanding. The Answer to 3GPP Testing
The TAS5600 exceeds the 3GPP
accuracy requirements by combining
precision signal generation techniques
with extremely accurate hardware
calibration to provide unprecedented
interference performance. The low
phase noise CW generators combined
with the precision baseband signal
generators within the instrument create
modulated RF signals with extremely
low Adjacent Channel Leakage Ratio
(ACLR). These low phase noise CW and
low ACLR modulated interferers assure
that during adjacent channel selectivity,
blocking, or spurious response tests,
the receiver under test will not have its
receive channel falsely polluted with
phase noise, spectral re-growth, or
spectrum “spill-over” which would
greatly devalue the test results.
An important characteristic of the
WCDMA or GSM modulated interferers
is their data sequence repetition rate.
To produce accurate BLER/BER test
case results, the data contained in the
Dedicated Physical Channels should
not repeat for the duration of the test.
However, sequences from digital signal
generation engines in signal generators
used for WCDMA and GSM performance
testing can repeat as frequently as every
frame. Uniquely, the TAS5600 uses a
real-time approach to achieve a data
sequence length of greater than one
hour, while generating a 3GPP-specified
Downlink Modulated Interferers that
contains common channels and 16
Dedicated Physical Channels. Similarly,
the TAS5600 generates Uplink
Modulated Interferers that contain one
control channel and one data channel
with a data sequence length of over
one hour.
The TAS5600 includes the following
UMTS interferer types:
■ WCDMA Uplink
■ WCDMA Downlink
■ Faded GSM
■ Single and Dual CW
■ AWGN
The interferers in the
TAS5600 are designed
to exceed the ACLR
requirements of all
adjacent interference
tests currently
specified by 3GPP for
WCDMA receiver
performance.
Modulated Interferer
Interferer
Channel
ACLR Interferer
Channel
ACLR
UMTS Receiver Testing
Low Adjacent Channel Leakage Ratio (ACLR)
3GPP ACLR Specification