A wireless sensor network (or IoT network) is a collection of distributed nodes. These nodes gather data from various sensors and relay that information to a central point through a wireless network. There, the data can be aggregated and have something useful done with it. These types of networks deal primarily with the transmission of small amounts of data that needs to be sent very efficiently.
Wireless sensor networks have plenty of applicable use cases. For example, if you want to remotely read the electricity meters of several homes in a development, you could install a wireless power meter on each home, which would relay data through a sensor network to a central point. That way, you wouldn’t have to drive around and read the meters by hand. Or, if you are creating a smart building, you can enable a wireless sensor network to check the status of your door locks and alarm systems, remotely turn lights on and off, and more.
There are many technologies that enable wireless sensor networks, including cellular, Bluetooth, Bluetooth LE, ZigBee, Symphony, and more. But if you’re going to switch underlying technologies, there are some “gotchas” you need to be aware of; we’ve outlined them below.
6 Things To Remember When Switching Wireless Technologies
1. Bidirectionality
Many wireless sensors collect data from their environments and send it up to the gateway, but the ability to send the data the other direction is arguably just as important. If you purchase technology that allows for bidirectionality, data can flow both to and from the gateway. For example, not only can you see that someone left a light on in an office, but with bidirectionality, you can also turn the light off.
2. Cost
Cost is a major issue when it comes to wireless sensor networks, and often, it’s tied to range. If you have longer range and fewer gateways, the cost of setting up your network may be lower.
Another cost complexity comes with cellular networks. For example, 2G cellular networks are being phased out, which is causing big problems for some people. And even if your 2G cellular modems are working fine, you’ll likely have to switch over to a different underlying technology very soon. This is difficult for many who don’t need the extended capabilities of 3G and cannot handle the extra cost. If you’re in this situation, you should start looking at other wireless technologies.
3. Energy Consumption
If you need a wireless application to last five to ten years, you’ll need something very low power. But there will likely be a tradeoff between latency and energy consumption. In other words, the number of times you transmit data in a given period may be affected in a low-power sensor network. If you need to gather data every 30 seconds instead of every five minutes, you will have to deal with a system that uses more energy.
4. Range
Range is a big question for all wireless sensor networks. Keep in mind, while cellular radios don’t have quite the same range as some LPWAN systems, there’s ubiquitous coverage with cell towers. But this trickles down into the cost of the system—so be aware of your needs.
See also: Symphony Link Range Calculator
5. Topology
The placement of sensors and repeaters in a mesh network like ZigBee is extremely important, while the placement of individual sensors in relation to one another—like in a star network—isn’t as important ( you just need to have a centrally located gateway).
For example, if you’re setting up an alarm system on multiple floors of a building, you’ll need great coverage. A mesh network may not have the capacity or reliability you need. But, if you switch to a star network and put a gateway at the center of the building, you could get more reliable coverage to all of those nodes.
6. Data Usage
It’s important to remember that the amount of data you can send over a star or mesh wireless sensor network is smaller than what you can send over a cellular network. So, you’ll need to be more efficient with your data transmissions if you switch from a cellular technology.
The Bottom Line
If you’re switching to or from any kind of wireless sensor network, keep this in mind:
- You’re going to have to make changes. There’s no shortcut or easy swap available, so prepare yourself for the work ahead of time.
- You can’t compare data sheets for apple to oranges. It can be difficult to compare and contrast wireless sensor network systems in a useful manner. So, make sure when you go to switch underlying technologies, you define the requirements for your application ahead of time, and look for specifications that meet those requirements. Don’t fall in love with a particular technology and try to squeeze your application into it.
