Currently, NR PDCP ticks are active only with monolithic gNB, triggered by the MAC scheduler in gNB_scheduler.c.
In F1 split mode, as there is no MAC, there’s no source to advance the NR PDCP timer via "nr_pdcp_wakeup_timer_thread()".
This commit introduces a dedicated thread for NR PDCP ticks in gNB-CU and CU-UP mode.
Without it, packet losses at the F1 uplink would cause indefinite buffering, as t-Reordering won't expire due to the lack of NR PDCP timer ticks.
38.473 requires to reset UE-related contexts in F1 Setup Request, so do
it.
However, avoid resetting UE states in phy_test: it has preconfigured UE
which we should not reset. Note that if NSA/phy-test used F1, we could
likely reset the UE state here, as the F1 UE context setup would come
afterwards.
The next commit implements the release of all UEs following the F1 Reset
message. It uses nr_mac_release_ue(), which as of now, triggered a
release complete message automatically, which we don't want in the case
of F1 Reset.
This commit refactors the code to split UE release at MAC/RLC and
release complete message sending to allow to release UEs without sending
the complete. Corresponding users are updated.
From the spec, it does not seem to be mandated to check that the random
identity needs to be unique within a cell. Also, from experience we see
that this only happens when the same UE "comes back"; so since one UE
can only have one connection, the other RRC UE contexts (with the same
identity) should be removed at some point, anyway, leaving only one with
the same identity.
Xin Zhe Khooi