# Power saving features

In order to ensure maximum battery saving, the logger is set to PSM = 0, eDRX = disabled. This means that the device will finish the transmission automatically after sending data to the server and (possibly) receiving a new configuration from it. The device does not stay awake waiting for additional transmission from the server. The only possible way to transfer data from the server to the logger is to send them in response to the data packet received from the logger.

The NB-IoT standard provides for the retry of data transmission, if it is impossible to send it correctly. The method of repeating the transmission is not configurable by the user, it is done automatically by the logger. The number of retries is determined by the ECL (Coverage Enhancement Level) parameter, which specifies the number of retries of failed transmission attempts defined as 2<sup>i</sup> (i = 1… 7). The parameter is set from 0 (normal operation) to 2 (bad signal quality / high noise, large number of retransmissions required). The higher the ECL value, the higher the energy cost of sending data, and therefore the shorter the battery life. When installing the NB-IoT logger, it is worth checking the ECL level in the place where it is to work (the issue is described in the "Device status" section).

NB-IoT devices should not move between base stations, as this results in the need to re-register to the network each time the base station changes. The registration process takes a relatively long time, therefore frequent relocation of the logger between base stations adversely affects the battery life.


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