LTE IoT devices often use eDRX (Extended Discontinuous Reception) to save power when idle.
Instead of monitoring continuously, the UE “sleeps” for most of the time and wakes periodically to check for Paging messages for the device.
Here’s an example from a CAT-M device under test, captured using QXDM:
ML1 Serving Cell Meas and Eval shows periodic wake-up
Measured eDRX cycle = 81.92 sec
Matches configured eDRX settings and network acceptance.
In this test, eDRX was configured via AT command:
AT+CEDRXS=2,4,“0101” → Request eDRX cycle 81.92 sec for LTE Cat-M1.
Network response:
+CEDRXP: 4,“0101”,“0101”,“0000” → Network provided eDRX = 81.92 sec, PTW = 1.28 sec
“0101” = 81.92 sec → a typical value used in IoT applications such as gas meters, where devices need to remain reachable within a target time frame (e.g. ~90 seconds).
This behaviour is key for battery life optimisation in IoT devices and is an essential part of our field testing process.
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