## DeepMIMO Forum

# [Solved] Some questions about the example_2.m

Hello,

When I try to run the DeepMIMOv2_example_2.m without changing any of the default parameters, MATLAB(2015) will give the following feedback:

DeepMIMO Dataset Generation startedError using >

Matrix dimensions must agree.

Error in find_users (line23)

prev_grids = rows > end_of grids;

What changes do I need to make to the parameters? Thanks.

By the way, I have one more question to ask you, can DeepMIMO be used to generate near-field channels? Thanks.

Hi @Fan

Is there any chance you could try the example with a newer MATLAB version? I'm able to run it with 2019a and later versions.

For the near-field question, the DeepMIMO scenario data provides point-to-point **ray-tracing** paths. The generator code uses this to generate MIMO channels assuming the far-field approximation holds (you can find the details in the documentation). Therefore, it is not possible to use the generator to produce near-field channels.

However, you can use scenarios where the access point is already represented by multiple points (i.e. the indoor I1 scenario).

In such a case, a thorough design is needed. The generator can be designed to generate the channels of a small UPA for each point, with a UPA array size that makes the far-field approximation holds for one point. Then, the channels of all points can be used to construct a near-field channel matrix of a large UPA for the multi-antenna access point (the antenna spacing needs to be taken into account in the design process).

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