eDRX

Extended Discontinuous Reception (eDRX) is a power-saving feature used in LTE-based IoT networks, particularly NB-IoT and LTE-M (Cat-M1). It extends device battery life by allowing longer sleep periods between downlink checks while keeping the device reachable by the network for occasional data.

Operation of eDRX builds on the standard DRX mechanism. The device periodically wakes to monitor paging occasions, but in eDRX the interval between wakeups is extended by increasing the DRX cycle length. The exact cycle length and monitoring window are negotiated between the device and the network and may be restricted by operator configuration. During a long cycle, the device largely remains off, waking only when a paging occasion occurs or when an uplink transmission is needed.

Benefits and typical use cases include enhanced battery life for devices that transmit infrequently, such as environmental sensors or smart meters. eDRX helps maintain network reachability for downlink messages while reducing energy consumption. It is commonly used with NB-IoT and LTE-M and can be employed alongside or independently of Power Saving Mode (PSM).

Limitations and considerations involve trade-offs between energy savings and downlink latency. Longer eDRX cycles can increase the time to receive a downlink or command, and a device may require re-synchronization after extended sleep. Availability and configurable options depend on the network operator, device modem capabilities, and 3GPP release support.

See also: DRX, NB-IoT, LTE-M, PSM.