* the mismatch between UE capabilities, passed to PHY by NFAPI PDU, and --ue-nb-ant-tx
  causes a segfault in SRS modulation
* issue with indexing txdataF[p_index], which fails due to an out-of-bounds access
  since first dimension of txdataF is sized based on ue->frame_parms.nb_antennas_tx
* N_ap used in SRS modulation is based on the number of antenna ports
  in the SRS configuration (srs_config_pdu->num_ant_ports)