CDMA2000 Signaling
R&S
®
CMW-KG8xx/-KM8xx/-KS8xx
474
User Manual 1173.9511.02 ─ 11
4.2.6 Internal Fading
Testing under realistic air interface conditions is important in order to verify the receiver
performance and the correct operation of the DUT's protocol stack implementation. For
example, packet error rates, throughput performance and correct operation of layer 1
procedures like RLP and IP statistics, where retransmission can be evaluated.
The internal fading module comes with a fading simulator and AWGN generator that
can be selectively enabled. It manipulates the generated forward link I/Q data stream
to emulate typical signal conditions at the DUT's receiver.
The following options are required to use the internal fading simulator in 1xEV-DO:
●
one fader I/Q board R&S CMW-B510F or R&S CMW-B520F per signaling instance
using internal fading
●
a single option R&S CMW-KE100 "Basic Fading Support: AWGN generator"
●
a single option R&S CMW-KE800 "CDMA2000 Fading Profiles from C.S0032-
C6.4.1 and C.S0011-C6.4.1"
4.2.6.1
Fading Simulator
Multi-path fading is an effect which occurs in real world situations. A signal sent from
the base station may take different routes (direct line of sight and/or reflected) and
reach the receiving antenna at different times leading to a sum of phase shifted and, if
the receiver is moving, frequency shifted signals.
The internal fading simulator supports propagation conditions defined in the table
6.4.1.3-1 of 3GPP2 C.S0011 e.g. various vehicle speeds, numbers of paths, path
power settings and delays.
A faded signal has a higher crest factor than an unfaded one. In order to avoid distor-
tion, the baseband signal must be attenuated before entering the fading module, with
the necessary attenuation (insertion loss) depending on the selected fading profile.
In CDMA2000 signaling, the insertion loss at the baseband level can be calculated
automatically or set manually. It is automatically compensated on the HF level, which
implies a shift of the allowed DL power level range to the same extent, but in opposite
direction.
4.2.6.2
AWGN Generator
Additional White Gaussian Noise (AWGN) is typically modeled in receiver tests,
because it may lead to a decrease of throughput. The quality of the received signal is
affected by the ratio of the signal power to the surrounding traffic noise level (signal to
noise ratio). The modulated signals from neighbor cells simply appear as noise. This
effect is simulated by adding AWGN to the signal.
The internal fading module supports AWGN insertion with configurable noise level.
Insertion loss at the baseband level is calculated and compensated automatically at
the HF.
The properties of the AWGN interferer comply with the requirements of 3GPP2
C.S0011, section 6.4.4 (e.g. minimum bandwidth 1.8 MHz for spreading rate 1 and 5.4
General Description
深圳德标仪器
135-1095-0799
