Multipath propagation - fast fading

 


In this experiment a frequency-selective channel is analyzed. Multipath fading propagation conditions are simulated using the Extended Pedestrian A model, a LTE channel model. Small movements - i.e. minor changes in the path delays - have major impact on the channel characteristics.

Animated transfer function - extended pedestrian a model
The animation shows in real time how the transfer function changes for a garden snail moving 7.5 cm along the 2nd path and back. Pedestrians are about a hundred times as fast.

Start

The initial channel setup results in a transfer function showing a fading dip at about 1007 MHz.

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Transfer function - extended pedestrian a model Extended pedestrian A model - properties
Transfer function - Extended Pedestrian A model

Experiment

Now we simulate a movement and watch how the transfer function changes.

Note that even small movements can have major impact on the channel characteristics. This effect is known as fast fading and describes mobile radio channels.

Transfer function after a minor change of the 2. echo delay Extended pedestrian A model properties - minor change of the 2. echo delay
Transfer function after a minor change of the 2. Echo delay

Next steps

Now change further channel settings and see how the transfer function changes.

This simulation app implements the Extended Pedestrian A model, a LTE channel model.

Extended Pedestrian A model simulation
Extended Pedestrian A model simulation

Change some channel settings and see how the transfer function changes.

Mouse Action

Left click on Extended Pedestrian A model

Pedestrian
Extended

Adjust an echo delay, e.g. 2. Echo delay.

Properties

Right click on Extended Pedestrian A model and select Impulse response.

model
response