- If you get real-time problems on heavy UL traffic, reduce the maximum UL MCS using an additional command-line switch: `--MACRLCs.[0].ul_max_mcs 14`.
- You can also reduce the number of LDPC decoder iterations, which will make the LDPC decoder take less time: `--L1s.[0].max_ldpc_iterations 4`.
## 6.3 Uplink issues related with noise on the DC carriers
- There is noise on the DC carriers on N300 and especially the X300 in UL. To avoid their use or shift them away from the center to use more UL spectrum, use the `--tune-offset <Hz>` command line switch, where `<Hz>` is ideally half the bandwidth, or possibly less.
## 6.4 Lower latency on user plane
- To lower latency on the user plane, you can force the UE to be scheduled constantly in uplink: `--MACRLCs.[0].ulsch_max_frame_inactivity 0` .
- If you get real-time problems on heavy UL traffic, reduce the maximum UL MCS using an additional command-line switch: `--MACRLCs.[0].ul_max_mcs 14`.
- You can also reduce the number of LDPC decoder iterations, which will make the LDPC decoder take less time: `--L1s.[0].max_ldpc_iterations 4`.
## 6.3 Uplink issues related with noise on the DC carriers
- There is noise on the DC carriers on N300 and especially the X300 in UL. To avoid their use or shift them away from the center to use more UL spectrum, use the `--tune-offset <Hz>` command line switch, where `<Hz>` is ideally half the bandwidth, or possibly less.
- Sometimes, the nrUE would keep repeating RA procedure because of Msg3 failure at the gNB. If it happens, add the `-A` option at the nrUE and/or gNB side, e.g., `-A 45`. This modifies the timing advance (in samples). Adjust +/-5 if the issue persists.
- This can be necessary since certain USRPs have larger signal delays than others; it is therefore specific to the used USRP model.
- The x310 and B210 are found to work with the default configuration; N310 and x410 can benefit from setting this timing advance.
## 6.5 Lower latency on user plane
- To lower latency on the user plane, you can force the UE to be scheduled constantly in uplink: `--MACRLCs.[0].ulsch_max_frame_inactivity 0` .
