[srsran-users] srsran-users Digest, Vol 88, Issue 15

[Edward Colbert]

Hi,

I am using SRSRAN-Emane which is based off the 2021 LTE code and have
attached an Open5GS core for experimentation with handovers.  I now have 2
ENBs connected to the MME and have configured the rr.conf file for handover
to the opposite ENB (see example snippet below).  The ENBs will attach and
establish link to internet if I start them individually without any
handover modification to rr.conf.  When I start both ENBs after handover
modification to rr.conf,  a handover is automatically initiated to the
another ENB but it does not succeed in that connectivity (ping Internet)
through the UE TUN device stops and the following appears on the UE.  I am
a newbie and any help is appreciated.

Thanks
Ed Colbert

UE output:

Network attach successful. IP: 10.45.0.40

 nTp) 23/6/2022 18:7:32 TZ:0

Received HO command to target PCell=6, NCC=2

Timer t304 expired: Handover failed

HO unsuccessful

.

.


Can anyone offer some advice for troubleshooting?  I don't understand why
the handover is automatically initiated, but that's for another day.

rr.conf snippet from ENB#1:

cell_list =

(

  {

    // yy rf_port = 0;

    rf_port = 0;

    cell_id = 1;

    tac = 0x0007;

    pci = 1;

    // yy root_seq_idx = 204;

    root_seq_idx = 204;

    dl_earfcn = 2850;

    //ul_earfcn = 21400;

    // xx ho_active = false;

    ho_active = true;

    //meas_gap_period = 0; // 0 (inactive), 40 or 80

    //meas_gap_offset_subframe = [6, 12, 18, 24, 30];

    // target_pusch_sinr = -1;

    // target_pucch_sinr = -1;

    // enable_phr_handling = false;

    // min_phr_thres = 0;

    // allowed_meas_bw = 6;

    // t304 = 2000; // in msec. possible values: 50, 100, 150, 200, 500,
1000, 2000


    // CA cells

    scell_list = (

      // {cell_id = 0x02; cross_carrier_scheduling = false;
scheduling_cell_id = 0x02; ul_allowed = true}

    )


    // Cells available for handover

    meas_cell_list =

    (

      {

        // yy eci = 0x19C02;

        eci = 0x19C02;

        // yy dl_earfcn = 3050;

        dl_earfcn = 2850;

        // yy pci = 4;

        pci = 6;

        //direct_forward_path_available = false;

        //allowed_meas_bw = 6;

        //cell_individual_offset = 0;

      }

    );


    // Select measurement report configuration (all reports are combined
with all measurement objects)

    meas_report_desc =

    (

        {

          eventA = 3

          a3_offset = 6;

          hysteresis = 0;

          time_to_trigger = 480;

          trigger_quant = "RSRP";

          max_report_cells = 1;

          report_interv = 120;

          report_amount = 1;

        }

    );

    meas_quant_desc = {

        // averaging filter coefficient

        rsrq_config = 4;

        rsrp_config = 4;

     };

  }

  // Add here more cells

);

rr.conf snippet from ENB#2:

cell_list =

(

  {

    // rf_port = 0;

    rf_port = 1;

    // xxx  cell_id = 1;

    cell_id = 2;

    tac = 0x0007;

    // xxx pci = 1;

    pci = 6;

    // yy root_seq_idx = 204;

    root_seq_idx = 268;

    dl_earfcn = 2850;

    //ul_earfcn = 21400;

    // xxx ho_active = false;

    ho_active = true;

    //meas_gap_period = 0; // 0 (inactive), 40 or 80

    //meas_gap_offset_subframe = [6, 12, 18, 24, 30];

    // target_pusch_sinr = -1;

    // target_pucch_sinr = -1;

    // enable_phr_handling = false;

    // min_phr_thres = 0;

    // allowed_meas_bw = 6;

    // t304 = 2000; // in msec. possible values: 50, 100, 150, 200, 500,
1000, 2000


    // CA cells

    scell_list = (

      // {cell_id = 0x02; cross_carrier_scheduling = false;
scheduling_cell_id = 0x02; ul_allowed = true}

    )


    // Cells available for handover

    meas_cell_list =

    (

      {

        // yy eci = 0x19C02;

        eci = 0x19B01;

        // yy dl_earfcn = 3050;

        dl_earfcn = 2850;

        // yy pci = 4;

        pci = 1;

        //direct_forward_path_available = false;

        //allowed_meas_bw = 6;

        //cell_individual_offset = 0;

      }

    );


    // Select measurement report configuration (all reports are combined
with all measurement objects)

    meas_report_desc =

    (

        {

          eventA = 3

          a3_offset = 6;

          hysteresis = 0;

          time_to_trigger = 480;

          trigger_quant = "RSRP";

          max_report_cells = 1;

          report_interv = 120;

          report_amount = 1;

        }

    );

    meas_quant_desc = {

        // averaging filter coefficient

        rsrq_config = 4;

        rsrp_config = 4;

     };

  }

  // Add here more cells

);
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