[srsran-users] ue rsrp and snr threshold settings

[J Giovatto]

Hi Folks,

I've been using the ZMQ GNU radio handover experiment link below (thanks 
for this, I find it very useful).

https://docs.srsran.com/en/latest/app_notes/source/handover/source/index.html

Looking into handover and cell interference w/r to PCI and possibly 
other sources of interference I made some config changes.

For reference I have only changed the rx/tx gain for both enb and ue to 
0, and set the enb tx power to 30 (rs_power = 30);

Using the GNRC channel gain sliders I was able to successfully achieve 
sync and attach provided that the delta between the settings was around 
2 to 3 points.

Anything less than that then the snr would fall below 3 and this check 
would kick in (see: srsue/src/phy/phy_common.cc)


     if (cc_idx == 0) {
       if (avg_rsrp_dbm[0] > args->in_sync_rsrp_dbm_th && avg_snr_db[0] 
 > args->in_sync_snr_db_th) {
         logger.debug("SNR=%.1f dB, RSRP=%.1f dBm sync=in-sync from 
channel estimator", avg_snr_db[0], avg_rsrp_dbm[0]);
       } else {
         logger.warning(
             "SNR=%.1f dB RSRP=%.1f dBm, sync=out-of-sync from channel 
estimator", avg_snr_db[0], avg_rsrp_dbm[0]);
         insync = false;
       }
     }
   }

tracking these 2 threshold values to ue.conf

# in_sync_rsrp_dbm_th:    RSRP threshold (in dBm) above which the UE 
considers to be in-sync def -130
# in_sync_snr_db_th:      SNR threshold (in dB) above which the UE 
considers to be in-sync    def 3


I just had to try and adjust the snr from 3 to 1 and push the sliders to 
a delta of 1 and the signal still passes see log below, so we can still 
decode PBCH among other things.

cc_idx 0, noise 3.540, rsrp -25.142, rsrq -6.427, rssi -3.137, tx_power 
30.00, pathloss 55.142, sinr 1.091, snr 1.356, sync_err 0.000000


So I am curious as to the choice for the default values for the 
threshold checks and if there is any criteria for adjusting these values ?


Thanks

Joe

-------------- next part --------------
A non-text attachment was scrubbed...
Name: OpenPGP_signature
Type: application/pgp-signature
Size: 840 bytes
Desc: OpenPGP digital signature
URL: <https://lists.srsran.com/pipermail/srsran-users/attachments/20230118/f6f13ef0/attachment.sig>