Hi,
I'm trying to get a better understanding what causes some unexpected current peaks while nRF9160 is in RRC-IDLE with the NB-IoT mode. I have been experimenting with the UDP sample with and without eDRX with data transfer interval of 1 minute (10 byte payload).
In the first case, both PSM and eDRX are disabled. The network sets the paging cycle (T_c) as 10.24 s and the number of paging occasions (nB) as 1, i.e. UE listens to NPDCCH for paging once per 10.24 s. This can be seen from the figure below as expected. However, I'm wondering what are the smaller current peaks that appear at the periodicity of 30 s?
In the second case, eDRX is enabled with eDRX cycle (T_eDRX) of 40.96 s and paging time window (PTW) left to its default value of 10.24 s. Now I would expect to see one paging occasion per 40.96 s. However, there is always another slightly higher current peak approx. 5 s before each PO visible. Please see the figure below. I also tried with a longer eDRX cycle and PTW to get multiple POs per eDRX cycle. Again, there was an additional spike 5 s before the POs. What causes this current peak 5 s before the paging time window?
Our setup is:
nRF9160DK HW: 0.9.0 2019.20
modem FW: 1.3.1
UDP sample: 1.9.1
Best regards, Olli
