LTE Toolbox Index Returning Functions

Hi,

I have been trying to implement some LTE toolbox functions myself but I am confused on indexing. For example "ltePUCCH1DRSIndices" function with "sub" option returns subcarrier, symbol and port indices and is directly used for mapping DMRS to PUCCH Format 1. However, MATLAB starts indexing from top left but LTE resource grid starts from bottom left (as specified in ETSI 36.211), I have taken this into account in my implementation and my function returns subcarrier indices at the opposite edge of what LTE toolbox returns. So, my question is that if LTE toolbox returns the indices in standard or adjusted indices ?

Thanks

[Hakan Asdasd]

Btw, I have checked the "info" struct that "ltePUCCH1DRSIndices" returns and resource indices are same as mine. So the question is why MATLAB is directly using those indices to map on grid, shouldn't they be inverted on vertical axis ?

Answer 1

[vidyesh]

Hi Hakan,

The indices returned by the ltePUCCH1DRSIndices function are organized according to the PUCCH format 1 DRS modulation symbol mapping, as detailed in the MATLAB documentation for this function. https://www.mathworks.com/help/lte/ref/ltepucch1drsindices.html

Given MATLAB's implementation, inverting the indices is generally unnecessary. The indices are designed to be directly applicable for operations such as mapping, without the need for additional transformations to reconcile MATLAB's indexing conventions with those of the LTE standard. Please note that this assumes a standard approach and is dependent on the specifics of your implementation.

For a practical demonstration of index mapping in the LTE Toolbox, see this example and how it maps "PUCCH 1" and "PUCCH 1 DRS" to the "resource grid":

https://www.mathworks.com/help/lte/ug/pucch1a-ack-missed-detection-probability-conformance-test.html

Hope this helps.