Should I use nrChannelEstimate or lteDLChannelEstimate?

I am working with 5G NR NTN channel model, and I am trying to generate the estimated DL channel.

As I understand, in Channel Estimation documentation, it has anote that "Virtual pilots are only created for the MATLAB® 'linear' and 'cubic' interpolation methods. "

So I am not sure if nrChannelEstimate use virtual pilots or not? or only lteDLChannelEstimate with 'linear' or 'cubic' methods have the virtual pilots?

And one more point, because the Doppler effect is too strong, I don't want to have the time-averaging step (and I don't need the nois estimation) - but I see that nrChannelEstimate always perform that time-averaging. With lteDLChannelEstimate, can I set the parameters to not time-averaging?

(And because of its name, lte, I am afraid lteDLChannelEstimate is related to 4G, not 5G settings, can I use it for my 5G NR NTN setting?)

------> In short, I would like to use virtual pilots to assist my interpolation, and not to have time-averging - which function can help me to do that?

Thank you so much.

Answer 1

[Tridib]

Hi @Thien Hieu,

The "nrChannelEstimate" function in MATLAB does not use virtual pilots. It performs interpolation using the actual reference signals present in the NR grid. The concept of virtual pilots applies only to LTE, specifically within the "lteDLChannelEstimate" function when the interpolation method is set to 'linear' or 'cubic'.

Virtual pilots are designed to improve interpolation accuracy and are available only in "lteDLChannelEstimate" with those methods. This feature is not implemented in "nrChannelEstimate".

In "nrChannelEstimate", time averaging of pilot signals is always performed, and this behavior cannot be disabled. In contrast, "lteDLChannelEstimate" provides control over time averaging through the averaging window parameter.

However, "lteDLChannelEstimate" is designed for LTE (4G) systems and should not be used for 5G NR, as the reference signals and grid structures differ between LTE and NR. For 5G NR, "nrChannelEstimate" should be used. To implement virtual pilots or disable time averaging in 5G NR, a custom channel estimation or interpolation method must be developed, either by post-processing the output from "nrChannelEstimate" or by directly using the reference signals.

Hope this helps!

[Thien Hieu]

oh thank you so much, it shortens my time reading the functions a lot ^^

So I will need to define my own function similar to nrChannelEstimate.

Thank you again.

[Thien Hieu]

And if I want to implement virtual pilot for extrapolation in nrChannelEstimate, I also need to define in my own function, right?

One more question, if you can helf me, is that virtual pilot for extrapolation is not implemented (recommended) in the 3GPP 5G NR documentations? And do you know why they don't use it any more in 5G?

Thank you

[Thien Hieu]

And, I saw the parameter AveragingWIndow of nrChannelEstimation function - is it related to the time-averaging we mentioned before? but why the default value is [0 0] but it is still time averaging?

Thank you so much :<< I am very new to this area