[srslte-users] Sending RRC Connection Reconfiguration message

Kewin Rausch krausch at fbk.eu
Wed Aug 2 11:57:38 UTC 2017


Hi Paul,
thank you for the quick reply!

I didn't think to use the ASN decoder... my bad! :-P

The "No. of ReportConfigToAddModList" is in fact NOT correct, as it should
be 1.
The RRC Measurement message is filled as follows (there are some variables
used which are passed as argument to the routine):

  meas.meas_obj_to_add_mod_list_present = true;
  meas.rep_cnfg_to_add_mod_list_present = true;
  meas.meas_id_to_add_mod_list_present  = true;
  meas.quantity_cnfg_present            = false;
  meas.meas_gap_cnfg_present            = false;
  meas.s_meas_present                   = false;
  meas.pre_reg_info_hrpd_present        = false;
  meas.speed_state_params_present       = false;
  meas.N_meas_id_to_remove              = 0;
  meas.N_meas_obj_to_remove             = 0;
  meas.N_rep_cnfg_to_remove             = 0;

  // Measurement object:

  meas.meas_obj_to_add_mod_list.N_meas_obj
        = 1;
  meas.meas_obj_to_add_mod_list.meas_obj_list[0].meas_obj_id
        = obj_id;
  meas.meas_obj_to_add_mod_list.meas_obj_list[0].meas_obj_type
        = LIBLTE_RRC_MEAS_OBJECT_TYPE_EUTRA;


meas.meas_obj_to_add_mod_list.meas_obj_list[0].meas_obj_eutra.offset_freq_not_default
           = false;

meas.meas_obj_to_add_mod_list.meas_obj_list[0].meas_obj_eutra.presence_ant_port_1
               = true;

meas.meas_obj_to_add_mod_list.meas_obj_list[0].meas_obj_eutra.cells_to_remove_list_present
      = false;

meas.meas_obj_to_add_mod_list.meas_obj_list[0].meas_obj_eutra.black_cells_to_remove_list_present
= false;

meas.meas_obj_to_add_mod_list.meas_obj_list[0].meas_obj_eutra.cell_for_which_to_rep_cgi_present
 = false;

meas.meas_obj_to_add_mod_list.meas_obj_list[0].meas_obj_eutra.N_black_cells_to_add_mod
          = 0;

meas.meas_obj_to_add_mod_list.meas_obj_list[0].meas_obj_eutra.N_cells_to_add_mod
                = 0;


meas.meas_obj_to_add_mod_list.meas_obj_list[0].meas_obj_eutra.allowed_meas_bw
   = LIBLTE_RRC_ALLOWED_MEAS_BANDWIDTH_MBW25;
  meas.meas_obj_to_add_mod_list.meas_obj_list[0].meas_obj_eutra.offset_freq
       = LIBLTE_RRC_Q_OFFSET_RANGE_DB_0;

meas.meas_obj_to_add_mod_list.meas_obj_list[0].meas_obj_eutra.carrier_freq
      = freq;

  // Measurement report:

  meas.rep_cnfg_to_add_mod_list.N_rep_cnfg
        = 1;
  meas.rep_cnfg_to_add_mod_list.rep_cnfg_list[0].rep_cnfg_id
        = rep_id;
  meas.rep_cnfg_to_add_mod_list.rep_cnfg_list[0].rep_cnfg_type
        = LIBLTE_RRC_REPORT_CONFIG_TYPE_EUTRA;


meas.rep_cnfg_to_add_mod_list.rep_cnfg_list[0].rep_cnfg_eutra.trigger_type
      = LIBLTE_RRC_TRIGGER_TYPE_EUTRA_PERIODICAL;

meas.rep_cnfg_to_add_mod_list.rep_cnfg_list[0].rep_cnfg_eutra.trigger_quantity
  = LIBLTE_RRC_TRIGGER_QUANTITY_RSRQ;

meas.rep_cnfg_to_add_mod_list.rep_cnfg_list[0].rep_cnfg_eutra.periodical.purpose
= LIBLTE_RRC_PURPOSE_EUTRA_REPORT_STRONGEST_CELL;

meas.rep_cnfg_to_add_mod_list.rep_cnfg_list[0].rep_cnfg_eutra.report_amount
     = LIBLTE_RRC_REPORT_AMOUNT_INFINITY;

meas.rep_cnfg_to_add_mod_list.rep_cnfg_list[0].rep_cnfg_eutra.report_quantity
   = LIBLTE_RRC_REPORT_QUANTITY_BOTH;

meas.rep_cnfg_to_add_mod_list.rep_cnfg_list[0].rep_cnfg_eutra.report_interval
   = rep_int;

meas.rep_cnfg_to_add_mod_list.rep_cnfg_list[0].rep_cnfg_eutra.max_report_cells
  = max_cells;

  // Measurement IDs:

  meas.meas_id_to_add_mod_list.N_meas_id
        = 1;
  meas.meas_id_to_add_mod_list.meas_id_list[0].meas_id
        = meas_id;
  meas.meas_id_to_add_mod_list.meas_id_list[0].meas_obj_id
        = obj_id;
  meas.meas_id_to_add_mod_list.meas_id_list[0].rep_cnfg_id
        = rep_id;

I'll look deeper into this problem then, and try to detect where the
miss-parsing occurs.

Cheers,
Kewin R.

On Wed, Aug 2, 2017 at 1:43 PM, Paul Sutton <paul at softwareradiosystems.com>
wrote:

> Hi Kewin,
>
> Running your message through an ASN analyzer, I get the attached RRC ASN
> decode.
> Looking at this, it seems that "No. of ReportConfigToAddModList" is
> incorrect which suggests a bug in the ASN packing routines. Can you compare
> the decode with your intended LIBLTE_RRC_MEAS_CONFIG_STRUCT to check?
>
> Thanks,
> Paul
>
> On 02/08/17 12:34, Kewin Rausch wrote:
>
> Hi everyone,
>
> I'm trying to send an RRC Connection Reconfiguration message using srsenb
> to a connected UE, but for some reason I don't see the trace of such
> message incoming at the receiver.
> The message is about RRC Measurements, which is a feature already included
> by liblte ASN1 parser.
> The receiver is a common Nexus 5, rooted to intercept and show RRC
> messages as they flow from the internal modem.
>
> The message is sent using: send_dl_dcch(&dl_dcch_msg).
> This procedure is present inside rrc::ue nested class, which manages UEs
> as seen by RRC perspective. The procedure performs like the following:
>
> void rrc::ue::send_connection_reconf_meas(LIBLTE_RRC_MEAS_CONFIG_STRUCT *
> msg)
> {
>   LIBLTE_RRC_CONNECTION_RECONFIGURATION_STRUCT * conn_reconf = 0;
>   LIBLTE_RRC_MEAS_CONFIG_STRUCT * mconf = 0;
>
>   LIBLTE_RRC_DL_DCCH_MSG_STRUCT dl_dcch_msg;
>
>   memset(&dl_dcch_msg, 0, sizeof(LIBLTE_RRC_DL_DCCH_MSG_STRUCT));
>
>   dl_dcch_msg.msg_type = LIBLTE_RRC_DL_DCCH_MSG_TYPE_RRC_CON_RECONFIG;
>   dl_dcch_msg.msg.rrc_con_reconfig.rrc_transaction_id =
> (transaction_id++)%4;
>
>   conn_reconf = &dl_dcch_msg.msg.rrc_con_reconfig;
>
>   conn_reconf->N_ded_info_nas        = 0;
>   conn_reconf->rr_cnfg_ded_present   = false;
>   conn_reconf->mob_ctrl_info_present = false;
>   conn_reconf->sec_cnfg_ho_present   = false;
>
>   conn_reconf->meas_cnfg_present     = true;
>
>   mconf = &conn_reconf->meas_cnfg;
>   memcpy(mconf, msg, sizeof(LIBLTE_RRC_MEAS_CONFIG_STRUCT));
>
>   parent->rrc_log->info("Sending RRCMeasConfiguration for RNTI:0x%x\n",
> rnti);
>
>   send_dl_dcch(&dl_dcch_msg);
> }
>
> The last memcpy operation copies the given meas_config inside the message
> that has to be sent.
> Trace of the operation can be seen in the log file of the eNB itself:
>
> 06:10:07.662581 [RRC ] Info    Sending RRC Measurement Configuration
> 06:10:07.662596 [RRC ] Info    SRB1 - rnti=0x46, Sending: RRC Connection
> Reconfiguration
>              0000: 20 10 15 00 00 00 1a 2c a3 c0 02 d2 70 00 00
> 06:10:07.662607 [PDCP] Info    TX SRB1 SDU, do_security = true
>              0000: 20 10 15 00 00 00 1a 2c a3 c0 02 d2 70 00 00
> 06:10:07.662709 [RLC ] Info    SRB1 Tx SDU
>              0000: 05 20 10 15 00 00 00 1a 2c a3 c0 02 d2 70 00 00
>              0010: e9 d9 0d 4a
> 06:10:07.662716 [RLC ] Info    Buffer state: rnti=0x46, lcid=1, tx_queue=22
> 06:10:07.663103 [MAC ] Info    [07871] SCHED: DL tx rnti=0x46, pid=0,
> mask=0x1800, dci=1,8, n_rtx=0, tbs=22, buffer=0
> 06:10:07.663120 [RLC ] Info    SRB1 PDU scheduled for tx. SN: 5
> 06:10:07.663148 [PHY1] Info    [07871] PDCCH: DL DCI Format1  rnti=0x46,
> cce_index=8, L=2, tti_tx=7875
> 06:10:07.663158 [PHY1] Info    [07871] PDSCH: rnti=0x46, l_crb= 4,
> mask=0x1800, harq=0, tbs=22, mcs=2, rv=0, tti_tx=7875
>              0000: 01 88 05 05 20 10 15 00 00 00 1a 2c a3 c0 02 d2
>              0010: 70 00 00 e9 d9 0d
> 06:10:07.664124 [MAC ] Info    [07872] SCHED: DL tx rnti=0x46, pid=1,
> mask=0x1800, dci=1,8, n_rtx=0, tbs=11, buffer=0
> 06:10:07.664137 [RLC ] Info    SRB1 Complete SDU scheduled for tx. Stack
> latency: 0 us
>
> No errors are visible from the log file.
> Now I have to find where the error is, and the available options here can
> be:
>
>    - The message is never sent by the eNB.
>    - The ASN1 message is formatted in the wrong way, the UE receives it
>    but discard and don't let me see it.
>
> The question then is:
>
> - Is that log trace enough to consider the message as sent to the UE?
> If yes, then it means that I have to concentrate on how LIBLTE is
> formatting the message, because there can be some problem there.
>
> Thank you,
> Kewin R.
>
>
> _______________________________________________
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>
> --
> ________________________________________________________________
> Paul Sutton Ph.D.
>
> Software Radio Systems (SRS)http://www.softwareradiosystems.com
> +353-87-9813473 <+353%2087%20981%203473> | paul at softwareradiosystems.com
>
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