3. Impairments in Waveform

Channel State

Use this cell to enable or disable the fading channel for the 802.11n.

Channel

Use this cell to configure fading channel parameters. When you click the button in this cell, the Channel Configuration Dialog opens.

IQ Impairment Mode

Choice: Constant | Frequency Dependent

Default: Constant

Select the IQ impairment mode. Each mode has a unique pair of impairment adjustments.

Constant -- IQ impairment is independent of frequency.
Frequency Dependent -- IQ impairment is a function of frequency with vector impairment adjustments applied to subcarriers.

This feature is only available for 802.11n with Option H and 802.11ac.

Quadrature Angle Adjustment for Waveform n

Use this cell to add quadrature skew impairment (-90 to + 90 degrees) to the generated waveform for the specific signal generator. This affects the waveform data so it applies to both RF and baseband I/Q outputs.This parameter is only available when the IQ Impairment Mode is set to Constant.

The baseband Quadrature Angle (angle) and the baseband IQ Gain (gain) values are used to modify the output I and Q data according to the following equations:

Real (output) = Real (input) - Gs * Imag (input)

Imag (output) = Gc * Imag\ (input)

where:

Gs = Gain * sin (angle) and

Gc = Gain * cos (angle)

I/Q Gain Balance for Waveform n

Use this cell to add quadrature gain impairment (-10 dB to 10 dB) to the generated waveform for the specific signal generator. This affects the waveform data so it applies to both the RF and baseband I/Q outputs. This parameter is only available when the IQ Impairment Mode is set to Constant.

Quadrature Angle Adjustment Vector for Waveform n

Default: all zeros

This is a vector with a maximum length of 512. Click in the parameter field to open a window where you can specify the quadrature angle for every subcarrier in the OFDM signal. ‘n’ specifies the index of the antenna. When you click on the button at the rightmost side of the field, a window appears, allowing you enter a phase error for each subcarrier. This parameter is only available when the IQ Impairment Mode is set to Frequency Dependent.

I/Q Gain Balance Vector for Waveform n

Default: all zeros

This is a vector with a maximum length of 512. Click in the parameter field to open a window where you can specify the in-phase gain for every subcarrier in the OFDM signal. ‘n’ specifies the index of the antenna. When you click on the button at the rightmost side of the field, a window appears, allowing you enter a phase error for each subcarrier. This parameter is only available when the IQ Impairment Mode is set to Frequency Dependent.