UE: No SIBx detected in TDD with 5MHz preventing UE to proceed cell attachment
cause:
Incorrect maximum number of CCEs calculation in PDCCH decoding when running in TDD mode, falsely triggering the "too many CCEs" error checking at the following line of code and giving up the PDSCH decoding procedure. So no SIBx are received
https://gitlab.eurecom.fr/oai/openairinterface5g/blob/develop/openair1/PHY/LTE_TRANSPORT/dci.c#L2700
solution:
a quick hacking is to change the if (nCCE > get_nCCE(3,frame_parms,1))
into if (nCCE > get_nCCE(3,frame_parms,0))
.
background:
For FDD mi
is always 1 for all subframe so get_nCCE(CFI=3,ul-dl-config,mi=1)
is a correct maximum number of CCEs. But in TDD some subframes can have mi=0
meaning no PHICH, and the get_nCCE(CFI=3,ul-dl-config,mi=1)
will give a number smaller than the actual maximum.
The checking against the incorrect maximum may be observed only in 5MHz because eNB will likely set CFI = 3 in this case.