At this point we are successfully able to build.
Additionally, we can run the scenario,
however, it does not pass. It seems that the gNB
is not connecting to the proxy correctly. Just
wanted to push the progress so far. FYI, the items
that had to be changed to correct the linking issues
were the following:
- mac_rrc_data_ind_ue vs. nr_mac_rrc_data_ind_ue
- rrc_data_req vs. nr_rrc_data_req
- mac_rrc_data_req_ue vs. nr_mac_rrc_data_req_ue
- rrc_data_req_ue vs. rrc_data_req_nr_ue
- rrc_data_req vs. nr_rrc_data_req
The listed functions should be declard in the LTE/NR
UE directory depending on the functionality. Several
were mixed. i.e.: LTE functions being called in NR UE.
Also, removing siWindowLength, siWindowLength_int,
SIBType, SIBPeriod, and siPeriod_int from the NR UE RRC.
These variable were not used in the NR UE and are defined
for LTE only.
Lastly, in the NR_IF_Module.c of the NR UE, the global
variable def_dci_pdu_rel15 is not accessible. Need to
revisit this. For not it is commented out.
At this point we can see the UDP uplink data
getting to the GTP layer of the gNB. This
only works if you change the memcpy in serialize_sdu()
to not have the encoded.byte
In the PDCP layer, if the sdu size < 3, this
just means control information is being passed.
In this case, we do not want to cipher the sdu,
its better to just return.
]
The IP traffic still does not work. But we are
updating the NR UE scheduler to ensure we are are
sending true IP traffic. Also, we were getting an
assert(); as well, and there was no logs, so we
fix that in this commit as well.
Also changed logic in the NR UE schedule to read
IP traffic. Also, configured the RLC layer in the
NR UE softmodem and the DRBs with the cRNTI once
the RACH procedure is complete in the NR UE.
1. If VNF is slower than PNF, next scheduling will be done after resync.
2. If VNF is unstable in slot progress, next scheduling will be done in next stable status.
3. SFN/SLOT indications are queued in nrUE.
4. get_queue is used instead of unquque for FIFO operation.
When there is a retransmission, we want to use the same number of RBs.
The RBs are allocated by groups (RBGs).
In some cases (like a cell with 25 PRBs), the last RBG contains less RBs.
So in case of a retransmission, if this last RBG was used before we need
to reuse it to have the same number of RBs. If not, we will use more RBs
for the retransmission than the previous transmission.
In an experiment with two UEs (quectel modules) it was seen that when a
retransmission happens with a different number of RBs then the UE is not
happy at all, leading to way more NACKs in the harq processes than should
happen (actually the first NACK was not a NACK at all, but the eNB did
interpret it as a NACK; so the next transmission should simply be discarded
by the UE that successfully received the first transmission; instead the UE
fails to decode the data and sends a NACK, a real one this time).
Maybe it's not the correct solution, but it improve things, there are
much less NACKs.
The problem is that when using those RBs with MCS 28 we may exceed the
code rate 0.93 and according to 36.213 7.1.7 the UE may skip decoding
PDSCH entirely in this case.
This is a hack. The real solution is to check that the code rate is below
0.93 for each scheduling decision and, I don't know, reduce the MCS if the
code rate is above, so that in the end it is below. That means that we need
a proper resource grid for the configuration of the eNB and this is not an
easy thing (at least from my point of view) given all the possible
configurations for the eNB, so I prefer not to do it rather than do something
incorrect, thus this hack.
The problem of this hack is that we won't use all the available RBs for
scheduling, potentially reducing the maximum throughput achievable.
To be fixed properly at some time, by someone who understands fully the
resource grid and all the possible combinations (fdd/tdd, number of
antennas, whatever else).
I have to revert this to be consistent with the OAI gNB.
But I think it is wrong to take the BWPSize from scc or scc_SIB, and the BWPStart from DLbwp[0].
Once the LTE UE's tunnel interface with the EPC
is ready to be established, if we are in NSA mode,
we do not want to launch the tunnel interface
from the LTE UE side, but in the NR UE. Via itti_msgs
we send the string containing the tunnel interface
'up' command to the NR UE and bring it up from the NR UE.
Melissa Elkadi