Problem about Output of RLC dldatatrace in LTE

[Jona Huang]

Hi~ guys
      when I use NS3 to simulate the performance of scheduler algorithm of LTE system , I found that the DlRxPDU is more than the DlTxPDU as report in the file "DlRlcStats.txt", as following blow.
      I saw some previous posts said the same problem, finally it was defined as a bug and it was reported to the NS3 Team. As the report said, this bug has been fixed.
     post:   https://groups.google.com/forum/?fromgroups=#!topic/ns-3-users/mObbn4aD0vk
     bug  report: https://www.nsnam.org/bugzilla/show_bug.cgi?id=1630

    The version of ns3 I used is 3.21.  I didn't modify anything about the data trace.   what I did is some modification about the process of scheduling radio resource  for HARQ retrasmission in MAC Layer( pf-ff-mac-scheduler.cc ). My codes have no error and my script  ran formally.
     I wonder how it could happen.  Any comment is appreciated~

% start    end    CellId    IMSI    RNTI    LCID    nTxPDUs    TxBytes    nRxPDUs    RxBytes    delay    stdDev    min    max    PduSize    stdDev    min    max
0    3    1    1    4    3    1347    512470    1356    520131    0.00530457    0.00330751    0.003    0.012    383.577    250.379    81    2052   
0    3    1    2    13    3    1022    354768    1389    505583    0.00960691    0.00276054    0.003    0.024    363.991    217.902    75    1095   
0    3    1    3    2    3    1016    237656    1210    302052    0.00952727    0.00304523    0.003    0.018    249.63    150.527    47    775   
0    3    1    4    16    3    1011    185332    1094    201833    0.00921755    0.00369444    0.003    0.024    184.491    116.988    32    775   
0    3    1    5    1    3    932    152265    929    150791    0.00993649    0.00337927    0.003    0.024    162.315    105.46    22    621   
0    3    1    6    24    3    909    126253    764    108795    0.00960864    0.0036602    0.003    0.024    142.402    90.9744    22    517   
0    3    1    7    23    3    913    102571    742    84681    0.00951078    0.00355208    0.003    0.024    114.125    72.0141    22    453   
0    3    1    8    21    3    940    88222    756    63232    0.00955026    0.00412023    0.003    0.024    83.6402    53.2919    22    317   
0    3    1    9    22    3    919    78818    808    69829    0.00955569    0.00359703    0.003    0.024    86.422    58.7811    9    277   
0    3    1    10    15    3    901    68331    882    66276    0.00961451    0.00347766    0.003    0.024    75.1429    48.8956    15    389   
0    3    1    11    14    3    902    59817    862    60280    0.00982018    0.00378872    0.003    0.024    69.9304    44.9158    15    277   
0    3    1    12    3    3    870    51156    792    48285    0.00947475    0.0033087    0.003    0.018    60.9659    41.7822    9    317   
My script :

using namespace ns3 ;

int main(int argc, char *argv[])
{

      uint16_t m_nmUser = 12;
      uint16_t m_dist = 1800;
      double speed = 10 ;
      double ber = 0.03;// it doesn't work in fact

      // Command line arguments
       CommandLine cmd;
       cmd.AddValue("m_nmUser", "Number of mobile UE", m_nmUser);
       cmd.AddValue("m_dist", "Distance between eNBs [m]", m_dist);
       cmd.Parse(argc, argv);

       // Config::SetDefault ("ns3::LteEnbNetDevice::DlBandwidth ", UintegerValue(100));//build failed
        Config::SetDefault ("ns3::LteAmc::Ber", DoubleValue (ber));
        Config::SetDefault ("ns3::LteAmc::AmcModel", EnumValue (LteAmc::PiroEW2010));
        Config::SetDefault ("ns3::LteHelper::UseIdealRrc", BooleanValue (true));
        Config::SetDefault ("ns3::LteSpectrumPhy::CtrlErrorModelEnabled", BooleanValue (true));
        Config::SetDefault ("ns3::LteSpectrumPhy::DataErrorModelEnabled", BooleanValue (true));
        Config::SetDefault ("ns3::PfFfMacScheduler::HarqEnabled", BooleanValue (true));
        //Config::SetDefault ("ns3::PfFfMacScheduler::HarqEnabled", BooleanValue (false));
       // LogComponentEnable ("BLERofHarqRex", LOG_LEVEL_ALL);
       //  LogComponentEnable ("PfFfMacScheduler", LOG_LEVEL_ALL);
       // LogComponentEnable ("RrFfMacScheduler", LOG_LEVEL_ALL);
        //   LogComponentEnable ("LteMiErrorModel", LOG_LEVEL_ALL);
        //   LogComponentEnable ("LteEnbRrc", LOG_LEVEL_ALL);
        //   LogComponentEnable ("LteUeRrc", LOG_LEVEL_ALL);
        //   LogComponentEnable ("LteEnbMac", LOG_LEVEL_ALL);
        //   LogComponentEnable ("LteUeMac", LOG_LEVEL_ALL);
        //   LogComponentEnable ("LteRlc", LOG_LEVEL_ALL);
        //   LogComponentEnable ("LtePhy", LOG_LEVEL_ALL);
        //   LogComponentEnable ("LteEnbPhy", LOG_LEVEL_ALL);
        //   LogComponentEnable ("LteUePhy", LOG_LEVEL_ALL);
        LogComponentEnable("LteEnbNetDevice",LOG_LEVEL_ALL);


        Ptr<LteHelper> lena = CreateObject<LteHelper> ();

        // Create Nodes: eNodeB and UE
        NodeContainer enbNodes;
     //   NodeContainer ueNodes;
        NodeContainer ueMnodes;
        enbNodes.Create (1);
        ueMnodes.Create (m_nmUser);//creat mobile ue

        // Install Mobility Model
        MobilityHelper mobility;
        mobility.SetMobilityModel ("ns3::ConstantPositionMobilityModel");
        mobility.Install (enbNodes);
        BuildingsHelper::Install (enbNodes);
       //set mobile UE
       Ptr<ListPositionAllocator> positionAlloc = CreateObject<ListPositionAllocator> ();
        for (uint16_t i = 0; i < m_nmUser ; i++)
           {
            positionAlloc->Add (Vector(1000+2000*i, 1000*i, 1.0));
           }
        mobility.SetPositionAllocator (positionAlloc);
        mobility.SetMobilityModel ("ns3::ConstantVelocityMobilityModel");
         mobility.Install (ueMnodes);
         BuildingsHelper::Install (ueMnodes);

         for (uint16_t i = 0; i < m_nmUser ; i++)
         {
        ueMnodes.Get (i)->GetObject<ConstantVelocityMobilityModel> ()->SetVelocity (Vector (speed, 0, 0));
         }

           lena->SetAttribute ("FadingModel", StringValue ("ns3::TraceFadingLossModel"));
           lena->SetFadingModelAttribute ("TraceFilename", StringValue ("src/lte/model/fading-traces/fading_trace_EVA_60kmph.fad"));
           lena->SetFadingModelAttribute ("TraceLength", TimeValue (Seconds (10.0)));
           lena->SetFadingModelAttribute ("SamplesNum", UintegerValue (10000));
           lena->SetFadingModelAttribute ("WindowSize", TimeValue (Seconds (0.5)));
           lena->SetFadingModelAttribute ("RbNum", UintegerValue (100));

        // Create Devices and install them in the Nodes (eNB and UE)
        NetDeviceContainer enbDevs;
        NetDeviceContainer ueMDevs;
        lena->SetSchedulerType ("ns3::PfFfMacScheduler");
        lena->SetSchedulerAttribute ("UlCqiFilter", EnumValue (FfMacScheduler::PUSCH_UL_CQI));

        enbDevs = lena->InstallEnbDevice (enbNodes);
        ueMDevs = lena->InstallUeDevice(ueMnodes);


        // Attach a UE to a eNB
        lena->Attach (ueMDevs, enbDevs.Get (0));

        // Activate an EPS bearer
        enum EpsBearer::Qci q = EpsBearer::GBR_CONV_VOICE;
        EpsBearer bearer (q);
        lena->ActivateDataRadioBearer (ueMDevs, bearer);

        Ptr<LteEnbNetDevice> lteEnbDev = enbDevs.Get (0)->GetObject<LteEnbNetDevice> ();
        Ptr<LteEnbPhy> enbPhy = lteEnbDev->GetPhy ();
        enbPhy->SetAttribute ("TxPower", DoubleValue (25));
        enbPhy->SetAttribute ("NoiseFigure", DoubleValue (5.0));
        Ptr<MobilityModel> mm = enbNodes.Get (0)->GetObject<MobilityModel> ();
        mm->SetPosition (Vector (0.0, 0.0, 30.0));

        //config mobile UE
        for (int i = 0; i < m_nmUser; i++)
        {
            Ptr<LteUeNetDevice> lteUeDev = ueMDevs.Get (i)->GetObject<LteUeNetDevice> ();
            Ptr<LteUePhy> uePhy = lteUeDev->GetPhy ();
            uePhy->SetAttribute ("TxPower", DoubleValue (20.0));
            uePhy->SetAttribute ("NoiseFigure", DoubleValue (9.0));
        }

        // Above is configing the mobile UE

        lena->EnableRlcTraces ();
        lena->EnableMacTraces();
        lena->EnablePhyTraces();
        Time simulationTime = Seconds (3.000);

        Simulator::Stop (simulationTime);

        Ptr<RadioBearerStatsCalculator> rlcStats = lena->GetRlcStats ();
        rlcStats->SetAttribute ("EpochDuration", TimeValue (simulationTime));

        Simulator::Run ();

        Simulator::Destroy ();
      }

[Tommaso Pecorella]

Hi,

dunno about the issue, maybe there's still something to fine tune. I guess Nicola can take a look at it.

Cheers,

T.

[Jona Huang]

  According to the output files, "DlRxPhyStats.txt“ "DlTxPhyStats.txt"  ,  I made a table to compare the calculation of Tx and Rx . 
  PHY-Tx 1347 is the number of RV==0  while 452 is the number of rv=1,2 or 3 . 
  PHY-Rx 1352 is the number of Correct==1 while 447 is the number of Correct==0 .
  It shows that the RLC-Tx is almost equal to PHY-Tx(first transmission), so how about the RLC-Rx ?  It makes me more confused, how to calculate the RLC-Rx .
  If  I want to calculate the rate of loss packet, what data should I use ? 
  Any comment and advice is appreciated ~~~~ 

IMSI	1	2	3	4	5	6	7	8	9	10	11	12
RLC-Tx	1347	1022	1016	1011	932	909	913	940	919	901	902	870
RLC-Rx	1356	1389	1210	1094	929	764	742	756	808	882	862	792
PHY-Tx	1347 (452)	1022 (1190)	1016 (1218)	1011 (1202)	931 (1238)	909 (1257)	912 (1251)	939 (1228)	919 (1200)	901 (1139)	902 (1087)	868 (1055)
PHY-Rx	1352 (447)	1020 (1192)	919 (1315)	862 (1350)	671 (1495)	536 (1619)	520 (1618)	563 (1566)	561 (1475)	598 (1321)	756 (1193)	511 (1072)
MAC

[Jona Huang]

Hi ~ All
   I have solved this problem.  Finally, I found there was logic bug in the file"pf-ff-mac-scheduler.cc", source code file, line965 ,  as showing below:
              else
                {
                  // HARQ retx cannot be performed on this TTI -> store it
                  dlInfoListUntxed.push_back (m_dlInfoListBuffered.at (i));
                  NS_LOG_INFO (this << " No resource for this retx -> buffer it");
                }
            }
          // retrieve RLC PDU list for retx TBsize and update DCI
          BuildDataListElement_s newEl;
          std::map <uint16_t, DlHarqRlcPduListBuffer_t>::iterator itRlcPdu =  m_dlHarqProcessesRlcPduListBuffer.find (rnti);
          if (itRlcPdu == m_dlHarqProcessesRlcPduListBuffer.end ())
            {
              NS_FATAL_ERROR ("Unable to find RlcPdcList in HARQ buffer for RNTI " << rnti);
            }
         ........
   when the condition of “else” is met, this "dlInfo" should be buffered without resource. But, it would be restransmitted anyway as the codes below (line973) ,  
    BuildDataListElement_s newEl;
   It means that no matter there are resource for retx or not , this retransmission would be transmitted.
   Attention here, if the HARQ retransmission is always allocated resource, this bug won't cause any problem. However, when " No resource for this retx", it would be retx at every TTI  untill it get the MaxRetxTime . That's why the Rx data calculated is more than Tx.

[Tommaso Pecorella]

Hi,

thanks for finding this. Mind opening a bug in Bugzilla ?

The web address is here: https://www.nsnam.org/bugzilla/

If you can't, please let me know and I'll open one.

Thanks,

T.

[Jona Huang]

 Sorry for the late reply. If you can open one is nice~

[Tommaso Pecorella]

Opened here:

https://www.nsnam.org/bugzilla/show_bug.cgi?id=2040

T.

[Nicola Baldo]

Hi Jona,

thanks a lot for reporting this bug and investigating the issue. I understand you already fixed the problem in your code, could you please share a patch so that we can review it and possibly commit to ns-3-dev?

Regards,

Nicola

[Pinewood Liu]

sorry to bother you after two years,you said you have solved this bug.could tell me how you fixed it?Because the bug is still in ns3.26.....

在 2015年1月5日星期一 UTC+8下午12:56:53，Joanna Huang写道：