Skip to content

Issue observed in nr_dlsim for 2x2, 273 PRBs

nr_dlsim does not succeed for 100 MHz bandwidth, 2x2 MIMO, SNR = 30 with current develop branch (2024.w38b). When we test with 2024.w35, nr_dlsim test succeeds.

Some remarks:

  • introduced in week 2024.w36
  • same behavior observed for all MCS > 22, for lower MCS test succeeds
  • it might be related to MR !2918 (merged), @francescomani could you please take a look?

How to reproduce: run nr_dlsim with 273 PRBs, 2x2 MIMO, MCS = 25, SNR = 30

sudo ./nr_dlsim -n100 -s30 -e25 -b273 -R273 -X8 -x2 -z2 -y2 -P

I attached output of the simulator with SNR 39.8:

*****************************************
SNR 39.800000: n_errors (100/100,0/100,0/0,0/0) (negative CRC), false_positive 0/100, errors_scrambling (72699/47174400,73035/47174400,0/0,0/0)

SNR 39.800000: Channel BLER (1.000000e+00,0.000000e+00,-nan,-nan), Channel BER (1.541069e-03,1.548191e-03,-nan,-nan) Avg round 2.00, Eff Rate 188448.0000 bits/slot, Eff Throughput 50.00, TBS 376896 bits/slot
*****************************************


gNB TX function statistics (per 500 us slot, NPRB 273, mcs 25, block 376896)
PHY proc tx                                   -nan us (0 trials)
 Statistics std=-nan, median=0.00, q1=0.00, q3=0.00 µs (on 0 trials)
    |__ DLSCH encoding time                354.37 us (200 trials)		( 70.87 total [ms])
        |__ DLSCH segmentation time         28.14 us (200 trials)
        |__ DLSCH LDPC input processing time   1.19 us (1200 trials)
        |__ DLSCH LDPC input preparation time   0.01 us (1200 trials)
        |__ DLSCH LDPC parity generation time  19.13 us (1200 trials)
        |__ DLSCH LDPC output generation time   4.31 us (1200 trials)
        |__ DLSCH Rate Mataching time        0.00 us (  0 trials)
        |__ DLSCH Interleaving time          0.00 us (  0 trials)
    |__ DLSCH modulation time               14.10 us (200 trials)		(  2.82 total [ms])
    |__ DLSCH scrambling time                7.48 us (200 trials)		(  1.50 total [ms])
    |__ DLSCH Resource Mapping time         80.79 us (10003 trials)		(808.17 total [ms])
    |__ DLSCH Layer Precoding time          27.37 us (10003 trials)		(273.83 total [ms])

UE function statistics (per 500 us slot)
|__ RX_PDSCH_STATS                         858.10 us (10003 trials)		(8583.59 total [ms])
|__ DLSCH_RX_PDCCH_STATS                    30.28 us (10003 trials)		(302.87 total [ms])
|__ RX_DFT_STATS                             3.92 us (280084 trials)		(1097.52 total [ms])
|__ DLSCH_CHANNEL_ESTIMATION_STATS         221.12 us (10003 trials)		(2211.86 total [ms])
|__ DLSCH_DECODING_STATS                   2632.37 us (10003 trials)		(26331.57 total [ms])
|__ DLSCH_RATE_UNMATCHING_STATS              4.21 us (450135 trials)		(1896.53 total [ms])
|__ DLSCH_LDPC_DECODING_STATS               50.48 us (450135 trials)		(22723.98 total [ms])
|__ DLSCH_DEINTERLEAVING_STATS               2.80 us (450135 trials)		(1260.48 total [ms])
|__ DLSCH_EXTRACT_RBS_STATS                  3.18 us (130039 trials)		(413.34 total [ms])
|__ DLSCH_CHANNEL_SCALE_STATS                0.78 us (130039 trials)		(101.80 total [ms])
|__ DLSCH_CHANNEL_LEVEL_STATS                0.54 us (130039 trials)		( 69.66 total [ms])
|__ DLSCH_MRC_MMSE_STATS                    16.73 us (130039 trials)		(2175.23 total [ms])
|__ DLSCH_UNSCRAMBLING_STATS                23.65 us (10003 trials)		(236.60 total [ms])
|__ DLSCH_CHANNEL_COMPENSATION_STATS         6.54 us (130039 trials)		(850.86 total [ms])
|__ DLSCH_LLR_STATS                          4.60 us (130039 trials)		(598.70 total [ms])
|__ DLSCH_LAYER_DEMAPPING                  255.96 us (10003 trials)		(2560.34 total [ms])
|__ PHY_RX_PDCCH_STATS                       0.00 us (  0 trials)		(  0.00 total [ms])
|__ DLSCH_PROCEDURES_STATS                 2660.70 us (10003 trials)		(26614.96 total [ms])