PSM: what it is and how it works within IoT and mobile networks

PSM (Power Saving Mode) is an energy-saving feature within mobile networks that allows IoT devices to enter a full sleep mode for extended periods. During this time, the device is not reachable by the network, which significantly reduces energy consumption.

Within IoT and connectivity, PSM is widely used in technologies such as NB-IoT and LTE-M to keep battery-powered devices operational for years.

Summary

PSM is a technique that allows a device to enter full sleep mode to save energy.

Important to remember:

• PSM stands for Power Saving Mode
• device is temporarily not reachable
• significantly reduces energy consumption
• applied in NB-IoT and LTE-M
• ideal for long-term battery applications

What PSM is exactly

PSM is designed to minimize the energy consumption of IoT devices by taking the device completely out of the active network state.

In this mode, the device disables almost all communication. It remains registered on the network but does not perform active communication until it “wakes up” again.

This makes it possible to achieve extremely long battery life.

How PSM works

PSM works by placing the device into a deep sleep mode after an active period.

In practice, this means that a device sends or receives data and then sets a timer. Once this timer expires, the device enters PSM.

During this period, the device is not reachable for incoming communication. Only when the device becomes active again can it send or receive data.

This process is repeated according to a predefined cycle.

PSM vs eDRX

PSM is often compared with eDRX, another energy-saving technique.

PSM

The device is completely unreachable during sleep mode and consumes minimal energy.

eDRX

The device remains periodically reachable, but at longer intervals.

PSM provides maximum energy savings, while eDRX offers a balance between reachability and energy consumption.

Applications within IoT

PSM is used in applications where devices only need to send data occasionally.

Examples:

• smart meters that send data periodically
• sensors with low data requirements
• agricultural and environmental sensors
• asset tracking with sporadic updates
• infrastructure monitoring

In these applications, reachability is less important than battery life.

Advantages of PSM

PSM makes it possible for IoT devices to operate on a battery for years without maintenance.

Energy consumption is significantly reduced because the device is inactive most of the time. This lowers operational costs and makes large-scale deployments feasible.

Implementation of PSM in IoT solutions

When applying PSM, it is important to choose the correct configuration.

Timer settings

Determine how long a device remains active and how long it enters sleep mode.

Data frequency

Align the frequency of data transmission with the application requirements.

Network support

Check whether the network being used supports PSM and configures it correctly.

Device configuration

Devices must support PSM and be correctly configured via firmware or network parameters.

Points of attention with PSM

Although PSM is very efficient, there are also limitations.

The device is not reachable during sleep mode, which means incoming communication is not possible. In addition, it can be difficult to manage devices remotely when they are offline for long periods.

Timing must also be carefully aligned with the use case.

Why PSM is important

Many IoT applications require devices that can operate autonomously for years. PSM makes this possible by minimizing energy consumption.

This allows organizations to operate more efficiently and reduce maintenance costs.

Conclusion

PSM is an energy-saving technique that allows IoT devices to enter full sleep mode to maximize battery life. It is widely used in NB-IoT and LTE-M applications.

For organizations working with battery-powered IoT solutions, PSM provides a powerful way to minimize energy consumption and extend device lifespan.

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