For the Tx streaming in our application we have to give the baseband I/Q samples 1 ms earlier than other SDRs we have tested with (total 3 ms ahead of when it is actually transmitted on air). We have tested with the SRS-LTE UE/eNB and observe the same behavior. This gets in the way of meeting the 4 ms round-trip requirement of LTE/NB-IoT. If we ask for the samples to be transmitted sooner we see the received signal is incorrect. Is there a way to avoid this extra delay?
Do you get late packets when trying to lower the timestamp? If so, reducing stream throughtputVsLatency might help getting samples to FPGA sooner.
Another way of making samples being sent sooner besides decreasing the timestamp value is lowering interpolation, disabling GFIR filters, IQ Gain and phase corrections.
Thanks for your response, with throughtputVsLatency set to 0.0 (least latency), The TX streaming is happening as expected.