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Decoding Range256 FreqListRange is not correct #161

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jewalt opened this issue Nov 25, 2021 · 2 comments
Open

Decoding Range256 FreqListRange is not correct #161

jewalt opened this issue Nov 25, 2021 · 2 comments
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@jewalt
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jewalt commented Nov 25, 2021

When decoding the following GSM SIB2:
59061A8BE7D683080000000000000000000000FF010000

I get the following ARFCNs (975 is the original ARFCN):
975, 1023, 1148 and 1152

The correct networks should be:
975, 124 ,128, 975 and 1023

This is due to a missing mod 1024 for Range256 and Range128 networks.

I am pretty sure there is also a bug in Range512 in that the result should be N, not W(0) + N mod 1024. Since Range 512, 256, 128 and BitmapVar are all decoded in

def decode(self):

Correct?

@p1-bmu p1-bmu self-assigned this Nov 29, 2021
@p1-bmu p1-bmu added the bug label Nov 29, 2021
@p1-bmu
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p1-bmu commented Nov 29, 2021

Thanks for your submission.
I never checked those encodings too deeply, so you may be correct. Could you eventually provide some SIB buffers with various ARFCN range encodings, so that after patching, I can integrate specific tests ?

@jewalt
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jewalt commented Nov 29, 2021

I will do my best, but I'm not sure I can generate useful (and accurate) data for all ranges. I know I can generate 256 as that is the default in the tools I am using, but I will check and see if I can manipulate that to use the other ranges.

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