Fading

After selecting a channel configuration, waveform file (or real-time), and MIMO Order, the Fading graphical user-interface (GUI) presents you with a set of parameters for each signal path. The intended workflow progresses left to right, as available parameter selections are often dependent on what was selected prior (to left).

Enable Fading

MIMO Order

Enable Fading

Enables or disables the fader processing for the specified Group. This control also appears on the Signal Summary screen.

GUI Location	Signals > Signal Summary selection > Fading Setup > Enable Fading
SCPI Command	[:SOURce]:GROup<group>:FADing ON\|OFF\|1\|0 [:SOURce]:GROup<group>:FADing?
SCPI Example	GRO:FAD ON GRO:FAD?
Notes	Setting cannot be set to On when license N7605AP0C is not present or the specified Group’s Configuration is not supported. Supported Configuration Modes are Independent and MIMO2. Attempts to set a value not allowed will generate error: -224,”Illegal parameter value”
Preset	OFF
State Saved	Yes
Initial S/W Revision	A.10.00

MIMO Order

Specifies the desired number of signals within the specified Group to apply fading to. This is the N in NxM MIMO. This parameter also appears on the Signal Summary screen.

GUI Location	Signals > Signal Summary selection > Fading Setup > MIMO Order
SCPI Command	[:SOURce]:GROup<group>:FADing:MORDer 1\|2\|4\|8 [:SOURce]:GROup<group>:FADing:MORDer?
SCPI Example	GRO:FAD:MORD 1 GRO:FAD:MORD?
Notes	Setting cannot be changed without Option 8SG and license N7605AP0C. Attempts to set a value not allowed will generate error: -224,”Illegal parameter value” The value of this setting will affect the available options for Channel Model, Correlation Matrix, and Doppler Shifts.
Preset	1
State Saved	Yes
Initial S/W Revision	A.10.00

Function

Specifies the fader processing for the specified signal and RF Output. Selecting “FADE” will apply the selected fading profile to the specified fading path. Selecting “PASSthrough” will play the signal with no fading applied. Selecting “OFF” is equivalent to muting this signal path.

GUI Location	Signals > Signal Summary selection > Fading Setup > Function
SCPI Command	[:SOURce]:GROup<group>:SIGNal<signal>:FADing<path>:FUNCtion FADE\|PASSthrough\|OFF [:SOURce]:GROup<group>:SIGNal<signal>:FADing<path>:FUNC?
SCPI Example	GRO:SIGN:FAD2:FUNC FADE ! This sets fading for the first signal in the first group’s output on the second RF Output. GRO:SIGN:FAD2:FUNC?
Notes	Fading (FADing SCPI command parameter) cardinality is based upon the channels configured in each group.
Dependencies	Note the group “Enable Fading” command supersedes this signal level fading function. If “Enable Fading” is not turned on for the group, the status of signal fading is ignored.
Preset	PASS
Choices	FADE \| PASSthrough \| OFF
State Saved	Yes
Initial S/W Revision	A.10.00

Standard

Selects the radio standard for the specified fader. The standard models cover propagation environments that allow you to test whether your device meets the performance requirements as defined by the respective standard.

GUI Location	Signals > Signal Summary selection > Fading Setup > Standard
SCPI Command	[:SOURce]:GROup<group>:SIGNal<signal>:FADing<path>:STANdard NR5G\|LTE [:SOURce]:GROup<group>:SIGNal<signal>:FADing<path>:STANdard?
SCPI Example	GRO:SIGN:FAD:STAN NR5G GRO:SIGN:FAD:STAN?
Notes	Fading (FADing SCPI command parameter) cardinality is based upon the channels configured in each group.
Preset	NR5G
State Saved	Yes
Initial S/W Revision	A.10.0

Channel Model

The channel model setting specifies the channel model (simulation type) for the specified fader. There are different models available for each standard. They are listed in more detail below.

A channel model is a mathematical representation of the effects of a communication channel through which wireless signals are propagated. The channel model can represent the power loss incurred by the signal as it travels through the wireless medium to the receiver.

GUI Location	Signals > Signal Summary selection > Fading Setup > Channel Model
SCPI Command	[:SOURce]:GROup<group>:SIGNal<signal>:FADing<path>:CMODel STATic\|TDLA30\|TDLB100\|TDLC60\|TDLC300\|HST1000\|HST750\|CQI112\|CQI450\|CQI\|EPA\|ETU\|EVA\|HST\|MBSFN [:SOURce]:GROup<group>:SIGNal<signal>:FADing<path>:CMODel?
SCPI Example	GRO:SIGN:FAD:CMOD TDLA30 GRO:SIGN:FAD:CMOD?
Notes	Attempts to set a value not allowed for the current instrument configuration and standard will generate error: -224,”Illegal parameter value” Fading (FADing SCPI command parameter) cardinality is based upon the channels configured in each group. The models available for 5G are: STATIC, TDLA30, TDLB100, TDLC60, TDLC300, HST1000, HST750, CQI112, CQI450 The models available for LTE are: STATIC, CQI, EPA, ETU, EVA, HST, MBSFN The STATIC channel model is essentially an unfaded signal. The amplitude is constant and there is no doppler shift. The STATIC channel model may be used to simulate the original LOS (Line of sight) signal. Tapped Delay Line (TDL) models are typically more suitable for simplified evaluations, e.g., for non-MIMO evaluations. TDL-A, TDL-B and TDL-C were created to represent three different channel profiles for NLOS (non-line of sight). TDL models usually contain power, delay, and Doppler spectrum information for the taps. Doppler is not explicitly defined, because it is determined by power and angular information combined with array configurations. The HST1000 and HST750 (High Speed Train) channel models are suitable to model the behavior of a receiver on a high-speed train or more generally a fast-moving receiver passing a stationary transmitter. The CQI is the Channel Quality Indicator. The EPA (Extended Pedestrian A) channel model uses Rayleigh fading. The ETU (Extended Typical Urban) channel model uses Rayleigh fading. The EVA (Extended Vehicular A) channel model uses Rayleigh fading. The MBSFN channel model is the Multicast-Broadcast Single-Frequency Networks channel model.
Dependencies	The set of allowed values depends upon the group configuration and standard.
Preset	STATIC
Choices	Static \| TDLA30 \| TDLB100 \| TDLC60 \| TDLC300 \| HST1000 \| HST750 \| CQI112 \| CQI450 \| CQI \| EPA \| ETA \| EVA \| HST \| MBSFN
State Saved	Yes
Initial S/W Revision	A.10.0

Correlation Matrix

The correlation matrix setting specifies the correlation level in spatial paths to use between the RF Outputs in the instrument group. In general, the higher the correlation between channels, the worse the “channel disparity”. Because MIMO is banking on spatial differences in the channel to increase throughput, the higher correlated models represent worse conditions and subsequently lower throughput.
The correlation matrix settings are related to 3GPP standards. 5GNR base station conformance tests have correlations defined by 38.141-1 document in Annex G.

GUI Location	Signals > Signal Summary selection > Fading Setup > Correlation Matrix
SCPI Command	[:SOURce]:GROup<group>:SIGNal<signal>:FADing<path>:CMATrix NONE\|LOW\|MEDIUM\|MEDIUMA\|HIGH\|XPOLLOW\|XPOLMEDIUM\|XPOLMEDIUMA\|XPOLHIGH [:SOURce]:GROup<group>:SIGNal<signal>:FADing<path>:CMATrix?
SCPI Example	GRO:SIGN:FAD:CMAT MEDIUMA GRO:SIGN:FAD:CMAT?
Notes	Attempts to set a value not allowed for the current instrument configuration and channel model will generate error: -224,”Illegal parameter value” Fading (FADing SCPI command parameter) cardinality is based upon the channels configured in each group. XPOL is an abbreviation for cross polarization. The “XPOLMEDIUMA\|XPOLHIGH” settings are specifically calling out models that account for antenna cross-polarization in some capacity. It serves the same function as spatial correlation considerations, though it is calculated specifically for antenna effects.
Dependencies	The set of allowed values depends upon the group configuration and channel model. For single RF output group configurations, NONE is the only available selection.
Preset	NONE
Choices	None \| Low \| Medium \| Medium A \| High \| X Pol Low \| X Pol Medium \| X Pol Medium A \| X Pol High
State Saved	Yes
Initial S/W Revision	A.10.0

Doppler Shift

This parameter specifies the doppler shift for the given fader. Doppler shift describes the changes in frequency of a propagated wave produced by a moving source with respect to an observer. Waves transmitted by an object traveling toward an observer get compressed resulting in a higher frequency as the source approaches the receiver.

GUI Location	Signals > Signal Summary selection > Fading Setup > Doppler Shift
SCPI Command	[:SOURce]:GROup<group>:SIGNal<signal>:FADing<path>:DSHift <freq> [:SOURce]:GROup<group>:SIGNal<signal>:FADing<path>:DSHift?
SCPI Example	GRO:SIGN:FAD:DSH 75 !Sets the fader doppler shift to 75 Hz GRO:SIGN:FAD:DSH?
Notes	Fading (FADing SCPI command parameter) cardinality is based upon the channels configured in each group. There are limited sets of values for the current instrument configuration, standard, correlation matrix. The closest available value will be used from the fading profiles installed on the instrument.
Dependencies	The set of allowed values depends upon the group configuration, channel model, and correlation matrix.
Preset	0 Hz
State Saved	Yes
Min	0
Max	The min, max and resolution are based upon the discrete values inside the fading profiles installed on the instrument. In other words, the actual value used will be quantized by the possibilities present. The preset value above is the doppler shift value in the “STATIC” channel model, which is the preset channel model.
Initial S/W Revision	A.10.0