The Importance of eDRX and PSM for Cellular IoT Deployments

In the evolving landscape of cellular IoT, efficient power management is critical for the success of battery-operated devices. Extended Discontinuous Reception (eDRX) and Power Saving Mode (PSM) are two key technologies that enhance the battery life of IoT devices, ensuring they remain operational for extended periods without frequent battery replacements. In this post, we explain the necessity of eDRX and PSM in cellular IoT deployments and how they contribute to the efficiency and sustainability of IoT solutions.

Understanding eDRX and PSM

Extended Discontinuous Reception (eDRX):

eDRX is a feature that allows IoT devices to reduce the frequency of communication with the network, thereby conserving battery life. It enables devices to "sleep" for longer intervals between listening for network messages. This is particularly useful for applications where data transmission is infrequent, such as in smart meters or environmental sensors.

Power Saving Mode (PSM):

PSM is a feature that puts the modem into a low-power state when it is not actively communicating. This mode significantly reduces power consumption by turning off certain components of the modem that are not needed for ongoing activities. For example, it may switch off the Wi-Fi radio or reduce transmission power during idle periods. PSM is crucial for battery-powered devices deployed in remote or hard-to-reach areas where replacing batteries frequently is impractical.

Key Considerations for Using eDRX and PSM

Device Power Source:

Battery-Operated Devices: eDRX and PSM are particularly beneficial for battery-operated devices. If your IoT deployment relies on batteries, these power-saving features can drastically extend the device's operational life.

Non-Battery Devices: For devices connected to a stable power source, the need for eDRX and PSM is less critical but can still contribute to overall energy efficiency and cost savings.

Power Consumption Management:

Energy Efficiency: By reducing power consumption during idle periods, eDRX and PSM help in lowering electricity costs and minimizing the environmental impact of network operations.

Battery Life Extension: For battery-powered devices, these features are essential in extending the time between battery replacements, reducing maintenance costs, and enhancing the reliability of IoT solutions in remote areas.

Carrier Dependency:

Network Compatibility: The effectiveness of eDRX and PSM can vary depending on the carrier. Different carriers have specific settings and support levels for these features, which can influence the device's behavior and connectivity performance.

Firmware Updates: To ensure optimal performance, it is important to keep the modem's firmware up to date. Consult with your Field Application Engineer (FAE) to follow best practices and access the latest firmware versions.

Connectivity Trade-offs:

Potential Issues: While eDRX and PSM improve power efficiency, they may introduce challenges in network connectivity, such as delays in inbound communication. Proper configuration and testing are necessary to balance power savings with connectivity requirements.

Network Requirements:

Request eDRX Requirements: To ensure proper operation, you need to request the eDRX requirements from the network and set your device to match. Different networks have varying eDRX configurations, and aligning your device settings with the network’s specifications is crucial for optimal performance.

Practical Implementation

To implement eDRX and PSM effectively, consider the following AT commands for managing power-saving settings:

Disabling Power Saving Mode:

AT+CFUN=0

AT+CPSMS=0

AT+CEDRX=0,2

AT+CEDRX=0,4

AT+CEDRX=0,5

AT+CFUN=15

```

Checking eDRX Status:

AT+CEDRXS?

```

If the command returns `+CEDRXS:OK`, then eDRX has been successfully disabled, ensuring no connectivity issues.

Conclusion

eDRX and PSM are essential features for optimizing the power consumption of cellular IoT devices. By carefully implementing these technologies, you can enhance the battery life of your devices, reduce operational costs, and contribute to a more sustainable IoT ecosystem. For further assistance, reach out to your FAE and engage with the community to share experiences and solutions.

By understanding and leveraging eDRX and PSM, you can ensure that your IoT deployments are efficient, reliable, and sustainable, meeting the demands of modern IoT applications.