How to think about LPWAN for commercial real estate applications

The data throughput from IoT devices will grow exponentially each year. Users rely on this data to inform decision-making, and more businesses are allowing their processes to be driven by IoT data. One salient example, which will be the focus of this article, is commercial real estate buildings; however, the information provided can be used for other applications as well.

Commercial real estate buildings have hundreds of pieces of equipment that require maintenance and other upkeep to make sure the asset functions as intended. With rooftop unit(s) in the penthouse mechanical room, domestic water pumps in the basement and air handler units in tenant spaces — installing sensors on each piece of equipment can be challenging. Traditional systems, such as building management systems, often wire sensors throughout the property — but the price tag for these systems can reach seven figures.

If you don’t want to wire every single sensor due to the cost and complexity, there are several questions to answer when evaluating IoT:

1. What type of data do I need to capture for the pieces of equipment within my building?
2. How critical are these systems? Do I need to control any of these pieces of equipment remotely?
3. What network infrastructure is available in the building?
4. How old is the building? What is the approximate height between floors? What is the thickness between concrete slabs?
5. What is my overall implementation cost? Will there be any added subscription costs moving forward?

Based on the answers to the questions above, the infrastructure required for an IoT system can vary significantly. The most common building protocols between devices are BACnet MSTP/IP, Modbus RTU/TCP, digital outputs (dry or wet contacts), and analog outputs (4-20 mA, 0-10 V).

All of these protocols traditionally require a physical connection between the data logging equipment and each sensor. These data logging devices convert the analog output into a readable format respective to the sensor.

It is not always possible to achieve the desired economics with wired sensors across an entire building. We can use better, modern IoT systems that have the capability of reading common protocols by transmitting over a wireless communication medium. These wireless devices are using a version of a low-power wide area network (LPWAN). These technologies, generally battery operated, can send data on ad-hoc, intermittent and/or consistent time frequencies. This protocol is already in use in Europe and increasingly in North America and the rest of the world.

There are several LPWAN technologies, each with its pros and cons. Some of these include LTE-M (cellular), Narrowband-IoT (cellular), LoRaWAN and Sigfox. There are other options available, but these are the most common and currently available for deployment. Of the four, LoRaWAN is the most common worldwide. LTE-M and Narrowband-IoT (NB-IoT) are close seconds, but unlike LoRaWAN, the deployment is carrier-specific and not region-specific (more on this below).

You may be asking: For a wireless deployment, why not use Wi-Fi or Bluetooth? While these are viable options for some instances, they are not the preferred strategy for small amounts of data being transmitted across long distances and through walls.

The key difference here is that LPWAN technologies communicate in sub-GHz frequency. LPWAN can communicate through an entire building for the same reason that walkie-talkies and cordless phones in the 1990s had such a wide range. They communicated in a sub GHz range — in the United States about 900 MHz.

As the frequency decreases, the communication range between devices increases because the wireless signal generated by these devices has a higher chance to pass through floors and walls. Having said that, the amount of data the device can send decreases the further away it is from the communication recipient. The relationship between the two is a negative slope.

The advantage with LPWAN is that it minimizes the total time required to deploy an IoT sensor compared to a traditional physical connection between sensors. The cost of these technologies is also decreasing and will continue to do so over the next five to 10 years. The chart below summarizes all four technologies with their capabilities:

As seen above, each wireless technology has its pros and cons. However, as of today, the most promising long-range wireless technology is LoRaWAN, followed by LTE-M and NB-IoT. In the long run, LTE-M and NB-IoT are capable of taking higher market share, but are significantly affected by their ability to have a single provider cover global coverage.

For example, in the United States, AT&T and Verizon have adopted LTE-M, Sprint is currently deploying an LTE-M network, and T-Mobile has decided to ditch LTE-M and put resources into NB-IoT right away. Every carrier around the world is deploying at its own pace subject to regulations. There is no action plan for global coverage yet.

Unlike LTE-M and NB-IoT, LoRaWAN and Sigfox are carrier-free, which allows one to install wireless bridges in ad-hoc locations within buildings. Communication from these bridges can connect to existing building networks and/or cellular connectivity.

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