Need to understand TDD pattern configuration in general

[wei-lou]

I want to configure TDD radio frame pattern in DDDSUDDDSU format and Special slot format as 10:2:2. Here is my configuration for tdd_ul_dl_cfg.

  tdd_ul_dl_cfg:
    dl_ul_tx_period: 5                   
    nof_dl_slots: 3                        
    nof_dl_symbols: 10                
    nof_ul_slots: 1                        
    nof_ul_symbols: 2                      

From the gnb log from SIB1 message, I do see correct configuration there

    "tdd-UL-DL-ConfigurationCommon": {
      "referenceSubcarrierSpacing": "kHz30",
      "pattern1": {
        "dl-UL-TransmissionPeriodicity": "ms2p5",
        "nrofDownlinkSlots": 3,
        "nrofDownlinkSymbols": 10,
        "nrofUplinkSlots": 1,
        "nrofUplinkSymbols": 2
      }

But the gnb program just aborted due to error as such.

--== srsRAN gNB (commit 55c984b55) ==--

Connecting to AMF on 192.168.70.210:38412
Initializing Open Fronthaul Interface sector=0: ul_comp=[BFP,9], dl_comp=[BFP,9], prach_comp=[BFP,9] prach_cp_enabled=true, downlink_broadcast=false.
Warning: Configured PRACH occasion collides with PUCCH RBs ([0..1) intersects [0..12)). Some interference between PUCCH and PRACH is expected.
Warning: Configured PRACH occasion collides with PUCCH RBs ([0..1) intersects [0..12)). Some interference between PUCCH and PRACH is expected.
Cell pci=78, bw=40 MHz, dl_arfcn=643464 (n78), dl_freq=3651.96 MHz, dl_ssb_arfcn=642432, ul_freq=3651.96 MHz

==== gNodeB started ===
Type <t> to view trace
/home/labuser/srsRAN_Project/lib/ofh/receiver/../support/prach_context_repository.h:118: void srsran::ofh::prach_context::write_iq(unsigned int, unsigned int, unsigned int, srsran::span<const std::complex<float> >):
Assertion `symbol < nof_symbols' failed - Invalid symbol index.
Aborted

So why is this error and what should be the correct configuration for my application?

Thanks,

[sauka]

Hi @wei-lou ,

Could you share cell_cfg.prach configuration in you gnb config file? Or better the whole config file.

[wei-lou]

I got it to work. Here is the working config file
gnb_ru_fuji_tdd_n78_40mhz_4x2_23101BM.yml.txt

[sauka]

Glad it works, thanks for sharing it! The original error was fixed in the latest release of the code.