Running TCP DL traffic with one connected UE showed a lot of
fluctuations in throughput. After analysis it was found that
sometimes the RLC UM PDU was not correct. It contained one byte
more than it should. On the receiver side, the TCP packet
contained in the RLC packet seems to be rejected by the TCP
stack of the UE (it has one byte more than it should),
leading to a brutal reduction of the throughput, probably due
to some congestion detection in the TCP implementation.
Or something.
This hotfix seems to solve the problem. Using iperf in downlink
with a 5MHz eNB, we see no more fluctuations, the traffic is
very steady at 16.8Mb/s, as reported by the iperf server running
on the phone. (17.5 in the PHY plot of the T tracer.)
A rewrite of both the MAC and RLC UM packet generation is needed.
The code is way too complex for what it does and may contain
several similar problems that only trigger in specific rare
conditions.
Summary of changes:
- fix dlsim/ulsim
- fix centOS compilation
- Move the accounting phase of the DL pre-processor in a separate procedure
and fix some issues
- additional Mac stats and Improvements
- minor fix in test setup v2
With value 4 when connecting one UE and doing some downlink
iperf TCP there is a crash. Probably due to the multiple wrong
RA detected leading to uplink failure of fake UE that never
sends Msg3 (because, well, there is no other UE).
This is another problem that will be fixed at some point.
Anyway, this value 4 fails. Let's put back 3.
Some more fixes for some bad conflict resolutions.
I ran:
git diff 2018.w04 2018.w05
And saw some problems with config_sib2.
There was also something strange in openair2/LAYER2/openair2_proc.c
in the function dump_eNB_l2_stats. Maybe the fix is wrong for
this one. To be checked.
Doing an iperf UDP uplink test, we could reach only 6Mb/s
with very good radio conditions instead of around 8Mb/s.
It turns out the MCS was limited to 16.
With this commit, we are back to a bit more than 8Mb/s
as it used to be.
(This is with a 5MHz bandwidth.)
Doing airplane mode off to connect a cots UE followed by airplane mode on
to disconnect it gives very bad results (bad disconnection with lots of
UL failures followed by lots of logs in the eNB). It used to work properly
after the work done by Xu Bo.
It turns out that in 2018.w04 things were still working okay. But
in 2018.w05 no.
So I ran:
git diff 2018.w04 2018.w05
And I checked all the modifications that I thought were relevant
(everything related to the UE, oaisim, if4 and fapi has not been checked).
This commits takes back the version of 2018.w04.
The modifications in openair2/RRC/LITE/rrc_eNB.c are necessary, I think.
The other modifications may not be necessary or even wrong. To be checked
at some point.
- move IMSI extraction code to function, remove FLEXRAN comp. directive
- refactor the code, esp. don't do deep if-nesting
- remove m-tmsi part (does not give correct value)
- copy complete IMSI info to UE context, decode in RAN API
Original Author: Xenofon Foukas
Changed formatting
does not compile
RS: cast to get rid of compiler warning
-> ImsiEpsMobileIdentity_t to ImsiMobileIdentity_t which is defined the same
way
oai