Creating a Low-Power Mindset for Today’s Advanced IoT Devices

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Creating a Low-Power Mindset for Today’s Advanced IoT Devices

Thanks to advances in technology, materials, and manufacturing, IoT devices are becoming increasingly sophisticated while form factors are becoming smaller. And despite their shrinking size, next-generation devices will need to collect, transmit and even make decisions based on a growing volume of data. Effective performance in the field demands an equally advanced approach to power management. Maintaining a low-power mindset requires doing everything possible to optimize the energy used to power the device.

There are thousands of use cases for IoT, and each has specific requirements for connectivity and battery life. Whether devices are intended to be stationary (like POS terminals, smart locks, pipeline monitoring solutions, water conservation, metering systems) or to perform on the move (like pet monitoring collars, toll collection devices, smart watches, and asset management trackers), IoT innovators must use power and connectivity hand in hand to make each device as efficient as possible.

Most batteries for IoT devices have a shelf life of years. However, consistent use, powering up and down, demanding tasks while in use, and the realities of inherently low-profile housings mean that the average battery lifetime can be shorter. It’s critical to explore key IoT design considerations across vertical markets to maximize hardware battery life.

As with everything in device design, there are trade-offs. For IoT, developers need to find the sweet spot between power consumption, data volume, speed, and latency. Here are three factors every IoT innovator should consider:

1. Reducing power consumption. Airtime is the largest drain on battery-powered devices – the longer a device keeps the radio on, the more power it consumes. There are several ways to decrease air activity:

• Reducing transceiver activity by either sending less data or using a faster speed to minimize airtime. Depending on the amount of data and the device characteristics, using a high bitrate codec to reduce airtime may consume less power than using a low bitrate codec.
• Reducing receiver activity by listening and receiving less data.
• Improving or removing handover scenarios. For example, a metering device in a building’s basement does not need to hand the transmission signal over to a different cell, which may remove the need for a neighboring cell scan.
• Changing the dynamics of the device’s cycle. There are two ways to look at a device’s cycle: shutting down and powering up a device, or using a sleep/wakeup cycle. Which is better for battery consumption depends on the specific device and use case.

2. Choosing the right cellular technology. There are benefits and limitations when using either LTE-M and NB-IoT connectivity, making it crucial that businesses select the best option for their specific needs. LTE-M offers access to energy saving features, like Extended Discontinuous Reception (eDRX) and PSM (power saving mode), that can increase uptime of deployed IoT devices compared to LTE Cat 1 and above.

When devices are not actively sending or receiving data, an LTE-M module can enter into the PSM or eDRX cycles, which improves operational efficiency while maintaining the connection and does not require additional signaling on wakeup. LTE-M module complexity is also lower compared to LTE Cat 1 and above. LTE-M thus makes it possible to both simplify module design and optimize overall power consumption.

For devices that mostly stay in fixed locations, NB-IoT can extend this capability even further. Since NB-IoT devices rely on simple waveforms for their connectivity, they consume even less power than LTE-M and the module cost can be reduced. The trade-off is that NB-IoT devices can’t send as much data as LTE-M and, because of the lack of mobility support, a device needs to perform a signaling handshake when it moves from one area to another.

3. Selecting the right data protocol. The less data a device transmits, the lower the demand on the device’s battery. Transmitting data via signaling messages such as SMS, NIDD, and USSD, and using lower overhead protocols over the user plane are available options. On the user plane, the lowest overhead can be achieved by UDP and TCP raw sockets. However, there are challenges to consider, such as security and authentication. Most cloud platforms only accept data sent over TLS such as HTTPS and MQTTS. A best-case scenario involves using the simplest protocol in a secure environment and adding the overhead of secure transmission later when passing data through public network. If the connectivity provider offers an endpoint that securely accepts data with those low overhead protocols, such as UDP/TCP raw sockets and can convert to HTTPS/MQTT/ Sparkplug or call cloud APIs on the device’s behalf, that’s the best of both worlds.

Inefficient battery use is a major factor that, if ignored, can easily sink an IoT deployment. By adopting a low-power mindset, IoT innovators can make the best decision based on their actual applications and use cases, setting them up well for a successful IoT implementation.


About The Author

Cofounder & CTO, SORACOM

Kenta Yasukawa is CTO and co-founder of Soracom, where he has led deployment of the industry’s most advanced cloud-native telecom platform, designed specifically for the needs of connected devices. ...