Lee Williams, COO
Of all the choices will you make as an Internet of Things (IoT) entrepreneur, one can have a disproportionately large impact on your success: connectivity. The choice between 3G/4G LTE, Wi-Fi and Bluetooth, and combinations thereof, will dramatically affect your user experience and business model.
Going into this discussion, lets remember that 4G LTE, Wi-Fi and Bluetooth are just marketing terms crafted for consumers. Were really talking about radio waves in different frequency bands. 4G LTE falls in the 2.5 to 7 GHz range; Wi-Fi spans from 2.4 GHz to 5.9 GHz; Bluetooth operates from 2.4 GHz to 2.485 GHz, though only at short distances.
Your connectivity strategy has to be based on the nature of the experience and level of service you aim to provide. You are dealing with an invisible landscape of evolving protocols, standards, and frequencies. Interference is more common than not, and you need to plan for change and really understand the life of your product and where it will be used. In general, 4G wins in reliability, range and security, Wi-Fi is good for device interoperability, and Bluetooth is good for creating rich user experiences. You can draw a direct correlation between the latency of the responses to a connected system and the connectivity technology used.
The Big Differences: Wi-Fi versus 4G LTE
Wi-Fi may not be the best choice for connectivity. Compared to 4G LTE, Wi-Fi is less reliable, less secure, more limited in range and less configurable. It is going to be the most popular choice, and is perfect for devices on a personal area network. Keep in mind, it replaced wired connections, and as a result it is good for the home-office, the kitchen, or the entertainment system in the living room, but it is not likely to be a good choice as the only form of connectivity outside the range of those areas.
Bluetooth is the black sheep of the trio. As a machine-to-machine communication protocol, Bluetooth is not an IoT technology per se unless its paired with a device that connects to the internet. Thus, for most IoT entrepreneurs, the big debate is 4G LTE versus Wi-Fi.
The first consideration is reliability. If you make a smart coffee makers, lightbulbs or other home appliances, Wi-Fi might be fine. If the power goes out, nothing disastrous happens. However, when safety and mission-critical functions are dependent on internet connectivity, you cant let power outages cause interruptions. So for a smart alarm system or sensor that measures the integrity of a construction crane, 4G LTE is necessary. Wi-Fi is also extremely sensitive to interference. A 2.4 GHz wireless landline phone can degrade Wi-Fi, and so can a deformed coaxial splitter, as I recently learned the hard way.
With regard to security, Wi-Fi is only as safe as the network administrator (i.e. the consumer) makes it. Whereas nobody can join a 4G network uninvited, anybody can join a Wi-Fi network that isnt password protected. Even when consumers password protect Wi-Fi, they arent known for choosing strong passwords (no offense to anyone who uses 123456). 4G LTE excels at security and verification without placing any burden on consumers.
Distance is another key issue, especially for IoT entrepreneurs focused on outdoor applications. Whereas Wi-Fi is constrained to about 100 feet, at best, distance is no issue with 4G LTE (or 3G) anywhere with decent coverage. People will be annoyed with your Wi-Fi smart swimming pool controller if they have to install Wi-Fi extenders to use it. For agricultural, industrial and infrastructural applications, like smart highways, the problem is even more pronounced. Rigging hundreds or thousands of acres with Wi-Fi is prohibitively expensive. As Google learned from its attempt to provide public Wi-Fi throughout Mountain View, Wi-Fi struggles with scale.
Although Wi-Fi technically provides higher speeds than 4G LTE, that is only the case when Wi-Fi is performing at its peak. Only trained IT professionals seem to make Wi-Fi work optimally, and most consumers arent aware how poorly their network might be operating relative to what their telecom provider promised (Ookla Speedtest, anyone?). Either way, cellular technology will soon surpass wireless broadband in speed, and it already offers tremendous advantages for IoT service providers. With 4G LTE, we can control attributes like provisioning, authentication, bandwidth and packet exchange, for instance and as a result provide a much more reliable and higher quality of service.
That being said, Wi-Fi is currently important for interoperability. For instance, if you want your IoT alarm clock to tell the smart coffee maker to start brewing when the customer wakes up, Wi-Fi is the way to go. I would also add that Wi-Fi does not require relationships with cell carriers, as 4G LTE does. If you create a 4G LTE IoT device, you will owe Verizon, AT&T or another carrier a monthly fee, and you will have to collaborate with the carriers to register and activate devices.
For appliances, dedicated services, and mission-critical and safety-related IoT, 4G LTE always wins. For simple consumer applications, Wi-Fi might suffice. The good news is that 4G and Wi-Fi are not mutually exclusive options.
Your choices regarding 4G, Wi-Fi and Bluetooth all come down to the service and business model you wish to operate. Here at ETwater, where my coworkers and I make smart outdoor controllers that eliminate water waste, and provide other features for a landscape or remote sites, we need a constant connection, and one that helps provide a rich form of interactivity with the services. We chose to use all three connectivity methods. We call this concentric connectivity. While this is a safe model for all IoT services, it might be overkill for some.
At ETwater, we need 3G/4G because our irrigation controllers cannot optimally water plants without an internet connection. Our platform analyzes weather, soil conditions, plant types and other factors in the cloud before sending irrigation directions to the controller. These environmental factors are changing all the time. Particularly on large properties, Wi-Fi may not reach the controller, and as I discussed, power outages and interference could thwart a proper connection. Cellular coverage also enables us to push software updates to devices and remotely service them when Wi-Fi is unavailable.
However, Wi-Fi is important in areas where wireless internet is available, but not cell coverage (yes, these places exist). Wi-Fi will also be useful as we begin to link other devices, sensors, and accessories to our forthcoming sustainability platform, Unity. Two 4G devices can exchange information via the cloud, but communication over a Wi-Fi network will reduce latency.
Finally, Bluetooth is all about enriching the experience for our users. The smart irrigation controller is headless, meaning it has no display or user interface. Accessories and connections can be made seamlessly by pairing over BT. Compared to hunching over an installed irrigation controller, using a smartphone is much more convenient, and mobile devices can support sophisticated controls without incurring additional hardware costs and software hassles on our end.
In the end we decided it was best to provide a seamless user experience in terms of connectivity. The products should just be available to software and other products and services, and no matter where they are placed, or how someone may or may not have configured a local area network.
Ok, So What Should I Use?
If you wish to provide hands-on services, including regular software updates and remote maintenance, and want to be always on, 4G is for you. You cant depend on your customers to maintain reliable Wi-Fi. Make sure you understand that you are leaving reliability and the quality of the connectivity solely in someone else hands. Likewise, if data enrichment is integral to your service meaning you continuously modify the service based on external data or information you are gathering again, I recommend 4G LTE.
Finally, consider cutting out Wi-Fi altogether if you plan to deploy your device in areas that will likely never have wireless internet. For some of our commercial smart irrigation devices, we strictly use 2G, 3G and 4G LTE for that reason. Box retailers dont want to install Wi-Fi network in their parking lots. There is a subtler reason too: for banks, retailers and other businesses that are vigilant about security, Wi-Fi devices are problematic. Each end point connected to their network introduces an additional security vulnerability.
The Bluetooth choice is more about form factor and the types of interoperability or content you are providing. IoT device makers turn to Bluetooth for its energy efficiency and its miniscule size chips. For wearables like smartwatches, 4G and Wi-Fi hardware are too bulky. It makes sense to use Bluetooth and pair the device with a 4G smartphone. As ETwater did, you might also Bluetooth to outsource the user interface to a smartphone or tablet, and to connect to accessories. Finally, Bluetooth is a good technology for supplementary sensors. With a smart alarm system, for instance, it makes sense to connect motion sensors and cameras to a central console via Bluetooth.
By this point, it should be clear that I would take 4G LTE and Bluetooth over Wi-Fi any day. Why use cheap consumer tech like Wi-Fi when you can use an industrial-grade protocol like 4G LTE? Remember, connectivity could make or break the success of your products and services. Dont take this choice lightly, and make sure you understand the future use of or evolution of the wireless technologies you choose.
For more information please visit www.etwater.com