Troubleshooting (NB-IoT)

NPRS demodulation fails

Certain combinations of NPRS ID and Cell ID can cause overlapping resource elements between NRS and NPRS.

Change NPRS ID or Cell ID so that elements do not overlap.

Demodulation fails to lock-on signal

Signal not present.

Check test setup connections.

Carrier too far from center frequency.

Enable extended frequency lock range and adjust center frequency to within ± 7.5 kHz kiloHertz: A radio frequency measurement (one kilohertz = one thousand cycles per second). of the carrier frequency.

Input is over-loaded or under ranged.

Adjust input range.

Frequency span is too narrow.

Increase frequency span.

Downlink: Incorrect Cell ID or Half-subcarrier Shift.

Make sure that the NB-IoT demodulator settings match the input signal.

I and Q channels are swapped.

Enable the Mirror Freq. Spectrum setting.

I/Q misaligned using I+jQ receiver.

Ensure that trigger delays for the hardware channels assigned to I and Q are correct.

High EVM Error vector magnitude (EVM): A quality metric in digital communication systems. See the EVM metric in the Error Summary Table topic in each demodulator for more information on how EVM is calculated for that modulation format.

Time capture includes data where no NB-IoT frame is being transmitted.

Make sure that the entire time capture is filled with an NB-IoT signal.

The demodulator uses all of the time capture data (see Result Length) to calculate equalization coefficients.

I/Q misaligned using I+jQ receiver.

Make sure you only analyze a single burst.