Extended Discontinuous Reception (eDRX) is another power-saving feature introduced in LTE and especially optimized for IoT devices running on LTE-M and NB-IoT networks. Like Power Saving Mode (PSM), the primary goal of eDRX is to extend battery life, but it operates differently and is best suited for devices that need more frequent data updates while still conserving power.
Here’s a breakdown of how eDRX works:
Purpose: eDRX allows devices to “sleep” between data transmissions but wake up periodically to check for incoming data or network paging without fully re-establishing the network connection.
- In standard DRX, a device will have periods where it “listens” to the network and periods where it sleeps to conserve power. eDRX extends these sleeping periods.
- During the eDRX sleep cycle, the device will turn off its radio components to save power.
- After the specified eDRX cycle time, the device briefly “wakes up” to check for any network signals or incoming data before going back to sleep if there’s nothing pending.
eDRX Cycles: The duration of an eDRX cycle (the time between when a device wakes up to check for signals) can be configured based on the use case. Depending on the network and device capabilities, these cycles can range from a few seconds to several hours.
Applications: eDRX is ideal for devices that need semi-frequent updates, such as:
- Health monitors that may need to receive periodic instructions or updates.
- Connected vehicles that need sporadic data but not continuous connectivity.
- Smart meters that report at regular intervals but also listen for commands from the network.
- Better Battery Life Than Standard DRX: By extending the sleep periods, devices use less power than they would under standard DRX.
- More Regular Updates Than PSM: While PSM is designed for devices that transmit very infrequently, eDRX is suitable for devices that need to communicate more often while still conserving energy.
Coexistence with PSM: Devices can use both PSM and eDRX together. For example, a device might use eDRX to check for updates every hour and then enter PSM for longer periods when no communication is expected.
In summary, eDRX provides a middle ground between continuous connectivity and the extended sleep periods of PSM. It’s another tool that network designers and IoT developers can use to balance communication needs with power conservation.