1. 09 Mar, 2018 1 commit
    • Cedric Roux's avatar
      hack: try to avoid "buffer full" problem when pushing DL traffic · 71e7f971
      Cedric Roux authored
      This is hack-level development.
      
      With this commit you can do UDP DL traffic of say 100Mb/s over
      a 5MHz link with one connected UE and the eNB should not crash
      because of memory exhaustion. Of course on the receiver side
      you won't get 100Mb/s and many many lost packets. But the system
      should not crash. 1Gb/s does not work. So in any case try to
      remain within some reasonable limits. There is no reason to
      push more than twice the maximum achievable throughput of
      the link.
      
      This work is based on a patch proposed by Francesco Gringoli.
      71e7f971
  2. 08 Mar, 2018 3 commits
    • Cedric Roux's avatar
      add a stop_rf function in the RU · 96380582
      Cedric Roux authored
      When the program exits it has to stop the streaming of the USRP.
      The function exit_fun is supposed to do that. When quitting with
      control+c (very common case) this function is not called. The
      code is very unclear there, so let's add a stop_rf in the RU,
      as there is already a start_rf.
      
      If we don't call trx_end_func, then at the next run the USRP
      device may be in an unstable state and behave improperly.
      
      If the program crashes then the USRP device may be in an
      unstable state. The only solution to this problem is to reset
      the USRP device.
      
      Maybe there is a way to clean the state of the device when we
      open it, before we start using it. Sort of a cleanup before
      use. That could be a better solution to "bad state after program
      crash".
      
      What has been tested:
      - monolithic eNB only
      96380582
    • Cedric Roux's avatar
      cleanup - remove unnecessary calls to get_cpu_freq_GHz · 5a61f994
      Cedric Roux authored
      The one in lte-enb.c disrupts the realtime. Using a B200mini with
      20MHz bandwidth leads to the UE unable to connect for it seesms like
      the UL and DL are not properly time synched because of this sleep
      of one second that happens after the USRP streaming has started.
      We see some random access attempts but the decoded preamble is
      wrong.
      
      This may be dependant on the setup. I had sporadic errors with
      a B210, where sometimes the UE could connect and sometimes not.
      5a61f994
    • Cedric Roux's avatar
      cleanup MAC PDU generation (plus some general cleanup) · 1a8d81ba
      Cedric Roux authored
      The code was very unclear and potentially buggy.
      This new version is more robust.
      
      We can waste up to 2 bytes because the last header in the MAC PDU
      does not contain a length field and when we request data from RLC
      we suppose a 3-bytes MAC header. This might be optimized at some
      point, but the benefit would be low.
      
      This commit also contains some general cleanup:
      - formatting
      - variables' types: let's use 'int' instead of trying to be clever
        by using small types that may generate bugs if the value is
        too big
      - remove 'tpc_accumulated' which was globally used for all UEs
        and has no purpose other than logging. We may want to rework
        a bit the TPC machinery at some point. As the code is today
        we may repeatedly send TPC over and over without caring about
        the 3GPP limits, in which case no one knows how the UE is
        supposed to behave: does it clamp the current max value or does
        it accumulate over and over and take the clamped value to compute
        its actual power? If we send a reverse TPC (reduce power instead
        of increase) does it do it immediately or does it have to decrease
        n+1 times if we previously ordered it to increase n times?)
      
      We do not address the problem of prioritizing LCIDs. As of today there
      is only one dedicated traffic channel (DTCH), so it's not a problem
      at this point.
      
      What has been tested:
      - monolithic eNB 5/10/20MHz with one cots UE, TCP/UDP UL/DL. At 20MHz the
        machine used was not capable of keeping up, generating lots of Us
        and Ls when the throughput reaches 60Mb/s. USRP B210 was used.
      1a8d81ba
  3. 02 Mar, 2018 3 commits
    • Cedric Roux's avatar
    • Cedric Roux's avatar
    • Cedric Roux's avatar
      hotfix: fix bad RLC UM packet creation · 26d68e9c
      Cedric Roux authored
      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.
      26d68e9c
  4. 01 Mar, 2018 1 commit
  5. 26 Feb, 2018 2 commits
  6. 22 Feb, 2018 13 commits
  7. 20 Feb, 2018 1 commit
  8. 19 Feb, 2018 2 commits
  9. 18 Feb, 2018 3 commits
  10. 17 Feb, 2018 2 commits
  11. 16 Feb, 2018 2 commits
  12. 15 Feb, 2018 4 commits
  13. 14 Feb, 2018 3 commits
    • Cedric Roux's avatar
      fixup previous bad merge (UE disconnection did not work properly anymore) · 91332d39
      Cedric Roux authored
      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.
      91332d39
    • Robert Schmidt's avatar
      a4f260f5
    • Niccolò Iardella's avatar
      Niccolo: Add sorting policy · 7e3b1f5d
      Niccolò Iardella authored and Robert Schmidt's avatar Robert Schmidt committed
      7e3b1f5d