[srslte-users] Bug with PUSCH (Collision) in srsENB

[Ilshat Shaidullin]

Hello SRS Team,

I've noticed strange behavior in srsENB. It occurs when I connect 2 UEs.
I've attached log files (info level for phy, mac and rrc).

Let the 1st UE be A and the 2nd UE be B.
[FirstExample.log] I successfully connect A with rnti=0x46. Then I try to
connect B with rnti=0x47. But after eNB sends RRCConnectionSetup all UL
transmissions of B are always KO (though SNR is good). B can be
successfully connected only with next rnti (0x48).

[SecondExample.log] I successfully connect B with rnti=0x46. Then I
successfully connect A with rnti=0x47. But as soon as A is connected,  B's
UL transmissions are always KO (though SNR is good). So after some time B
will perform RACH and connect with new rnti. Only after that B's UL
transmissions will be OK.


I think that in the examples above when eNB sends DCI Format 0 for B, A
mistakenly uses it and performs UL transmission too. This may happen
because C-RNTI values are close to each other. If I change C-RNTI
allocation method ( replace "last_rnti++"  with "last_rnti += 10" in MAC )
I don't observe this issue.

What can cause such strange behavior?


Best regards,
Ilshat
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