Rohde & Schwarz SMW200A - Simulating Fading, Adding Noise and Predistortions, and Impairing the Signal

Simulating Fading, Adding Noise and Predistortions, and Impairing the Signal
R&S
®
SMW200A
389User Manual 1175.6632.02 ─ 16
5 Simulating Fading, Adding Noise and Pre-
distortions, and Impairing the Signal
The test case scenarios in accordance with the specifications often require a not
"clean" signal but rather a signal that is impaired or interfered. To fulfill such require-
ments, the R&S SMW is equipped with a fading simulator and noise generator and pro-
vides the possibility to impair and predistort the digital I/Q signal.
This section describes the following functions:
● Simulating Fading................................................................................................. 389
● Adding Noise to the Signal....................................................................................389
● Impairing the Signal.............................................................................................. 406
● Frequency Response Correction.......................................................................... 414
● Applying Digital Predistortion................................................................................ 414
5.1 Simulating Fading
A wireless signal transmitted over the air is subject to noise interference and fading.
Fading can impair the transmitted signal significantly and hence strongly influence the
performance of a communication system. Fading can cause deceased signal-to-noise
ratio or can introduce inter-symbol interference.
To simulate real-word conditions, the R&S SMW is equipped with an integrated real-
time fading simulator. With the provided functions, you can simulate repeatable fading
conditions for receiver tests.
For a description of the fading simulator, refer to the user manual "Fading Simulator".
5.2 Adding Noise to the Signal
This section introduces the concept of the AWGN generator (Additive White Gaussian
Noise) and describes the settings for generation of noise, sine wave interferer, and
adding noise to the generated signal.
5.2.1 Required Options
The equipment layout for generating an AWGN signal includes:
●
Option Standard or Wideband Baseband Generator (R&S SMW-B10/-B9) per sig-
nal path and
●
Option Baseband main module, one/two I/Q paths to RF (R&S SMW-B13/-B13T) or
Option Wideband baseband main module two I/Q paths to RF (R&S SMW-B13XT)
●
Option Noise Generator (R&S SMW-K62) per signal path
Adding Noise to the Signal