Internet Of Things (IoT) Blog | Link Labs

What Is A Low Power Wireless Sensor Network?

Written by Brian Ray | December 22, 2014

Advancements in technology have made it easier to collect data in the home, in warehouses and on production floors, and across cities. As this data is collected and interpreted, decision makers can now make meaningful use of it. These strides are creating what is called the Internet of Things (IoT), the Internet of Everything (thanks Cisco!), or as it used to be known, Machine to Machine (M2M) communication. City managers, businesses, and citizens are (and will be) the beneficiaries of information created from these data flows. But in the vast majority of cases, the people who have wanted access to this data haven’t been able to get it. To date, existing solutions have been too limited in network coverage, are too power hungry, or both. However, this situation is changing rapidly with the creation of low power wireless sensor networks. Now all of this data can be collected and given to the people who need it.

To understand what a low power wireless sensor network is and how it functions, we’ve put together this article. It answers the key questions: where does all this data come from, and how much energy is used to get it? To start, we’ll take a step back and describe what a wireless sensor network is, so we’re all on the same page.

Wireless Sensor Networks (WSN)

A wireless sensor network (WSN) is a group of spatially distributed, independent devices that collect data by measuring physical or environmental conditions. Some of the conditions being measured are: temperature, pressure, moisture, position, usage information, lighting, and sound. These readings, in the form of data, are passed through the network, are collated and organized, and then delivered to the end user. WSNs are already used for many applications like industrial process monitoring and control, electricity system controls, and human health monitoring.

Traditionally, these WSNs tend to need a lot of power to function, but decreasing the power needs of the system increases the lifetime of the sensor devices, and creates space for battery-powered applications. Battery-powered devices allow for wide-ranging use cases and opens opportunities for lower-ROI applications. This is where low power wireless sensor networks come in.

Low Power Wireless Sensor Networks

The key to achieving a longer lifetime for WSN is to design wireless sensor networks that minimize power consumption of wireless sensor devices, hence the name “low power.” To cut down on overall power consumption, low power wireless sensor networks control the active time or “awake time” of the devices (such as a radio or microcontroller) and limit the current draw when they are “sleeping.” These networks accomplish this by varying the power setting modes of the devices, such as “always on”, “standby”, or “hibernation” modes.

For example, think about a basic remote temperature sensor that collects data over a long period of time. In “active” mode, the device uses power to take temperature readings and to manipulate data using a sophisticated noise-filtering algorithm, but the device does not have to do this constantly. When not in active mode, the microcontroller can return to sleep mode until more sample measurements are taken. Then, at regular intervals, the Real-Time Clock and Calendar (RTCC) will wake up from sleep mode to see if there is another task to perform. If not, it will go back to sleep, conserving power usage. When the amount of time the microcontroller spends running is smartly managed and controlled, the overall amount of power consumption is drastically reduced.

One ideal use case for low power wireless sensor networks is in “smart city” applications. Low-power network technology is optimal for monitoring the condition of things such as parking, streetlights, traffic control, municipal transportation systems (buses), snow plowing, trash collection, and public safety. Data is collected from these devices, then interpreted into meaningful information in a format that allows city employees to make informed decisions about allocating resources and delivering services. In many cases, responses to changing conditions can be made ahead of time and automated, resulting in a “smart city.”

Who Is Building Low Power WSNs?

There are several wireless machine-to-machine (M2M) companies that are building powerful low power wireless sensor networks. Here are a few:

SIGFOX

SIGFOX Ready™ modems operate with low transmission power and no continuous network synchronization, which produces gains in energy efficiency along with years of functionality. Typical power consumption of a SIGFOX Ready™ modem varies from 20mA to 70mA and they consume next to nothing when inactive. Right now SIGFOX employs an uplink only network, and they are developing a next generation bi-directional feature, but their underlying technology means that the downlink will not have a symmetrical link.

Linear Technology

Another company that is using low power WSN is Dust Networks, part of Linear Technology. Their SmartMesh IP and SmartMesh WirelessHART products are designed for harsh industrial environments that require low power, reliability, and scalability, and are well-suited for general industrial applications.

OnRamp Wireless

OnRamp Wireless is also making advances with their low power RPMA network. This network allows communication for both residential and commercial metering, and can support smart metering capabilities on the same network infrastructure that supports grid automation, all while utilizing energy efficiency.

Actility

Actility has its foot in the door as well. Actility’s end-to-end M2M service, ThingPark Wireless, offers a bi-directional, low power network that allows for coverage on a range of 2-5 km in dense urban areas and up to 15 km for rural applications.

Link Labs

Link Labs is building its low power wireless sensor networks. With class leading sensitivity and power consumption, a flexible protocol stack, and symmetric uplink and downlink, Link Labs’ low power wireless sensor network is an ideal platform for everything from parking and water meters to streetlights and asset tracking.

Conclusion

A low power wireless sensor network is a lower cost solution to transferring and gathering data in the IoT space. By conserving and limiting power used by remote devices, low power wireless networks open space for a variety of new applications in the IoT ecosystem.  By better understanding the power management features on low power WSN, engineers are well on their way to developing green, energy-efficient wireless solutions. By listening to our customers and providing a flexible solution through its Wide Area Low Power Protocol, Symphony Link, Link Labs is leading the way in developing low power wireless sensor networks.