How mobile network affects your cellular IoT device battery lifetime

The focus of every battery powered IoT device owner is to make sure the devices reach a specified lifetime. Whether it is a month or a number of years with the desired amount of data transferred.

In comparison with e.g. LoRaWAN technology, mobile network communication between the terminal device and the mobile network is very complex and not atomic as such. This particularly means that one cannot easily determine how much energy is required to send a fixed amount of data in all scenarios.

Mobile network technologies like NBIoT and LTE Cat-M1 are built with power efficiency in mind. However only if implemented correctly from end-to-end with the correct configuration of all components in the chain, it will create longer battery life-time. Features like PSM, eDRX and release assistance are the key enablers, but must not be taken for granted globally. Variations in configuration configuration and implementations at the terminal side may result in order of magnitude greater power consumption then envisioned.

What a power-efficient cellular IoT product should implement

These 3 things are essential:

  • Mobile network connectivity strategy that requires a minimal amount reconnections ✅

  • A limited but effective reconnection intervals, to reduce power-usage ✅

  • A correct use of eDRX or PSM ✅

These are the very basic concepts, which must not hinder the solution from delivering valuable data on-time to the customer.

Common mistakes that drain battery and reduces device-lifetime

1. An IoT device in areas with poor network coverage, where it keeps reconnecting

Connecting to the mobile network is the most power hungry part. Continuing to connect where there is no coverage at all simply means the device is burning the energy.

2. The device reboots or looses the eDRX/PSM connection

Every time the device loses a mobile connection, a full reconnection is required. These events must be limited or eliminated for as much as possible.

3. Device remains online for much longer periods than required with poorly configured timeouts

Data communication may at times fail and if the IoT device does not correctly time-out in all data transmissions steps, it may remain connected for a very long period waiting for the data transmission to occur, whereas it may be better of just disconnecting and retrying at a more favorable time.

To give a quick perspective: properly configured NBIoT network and the right use of NBIoT modems for a cIoT product can make the product last on a single 3.6v battery for 8 years, or it can drop down to less than 2 years.

Our experience is that often it is incredibly difficult to validate correct behavior of IoT devices in all edge-cases across multiple countries without a rigorous testing process in place. Most often there is time and budget wasted to do so and often critical problems are occurring in the field after deployment.

Testnik focuses on solving exactly this problem, streamlining and simplifying the validation of IoT connectivity across the globe and enabling a rapid convergence to a stable and reliable solution with minimal associated costs and headaches.

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