As the name implies, IoT (Internet of Things) devices need a stable and secure way of connecting to the Internet in order to communicate and exchange data. Deciding which of these methods to use, however, isn’t always clear-cut.
Wi-Fi and cellular are the two most popular wireless technologies that make IoT networks possible—they literally provide the “I” in “IoT.” Although Wi-Fi has been the dominant choice for IoT for years, cellular has recently grown in popularity and is now a highly viable alternative.
In this article, we’ll discuss the pros and cons of both Wi-Fi and cellular when it comes to IoT networks, and how you can decide between Wi-Fi and cellular for your next IoT project.
Wi-Fi for IoT
Wi-Fi technology uses multiple bands of radio waves in order to transmit information between devices.
In order to have Wi-Fi connectivity, a device must have a wireless adapter that translates between data and radio signals. The device communicates with the adapter’s chip using a protocol such as UART or SPI. The adapter then communicates with an external router, which sends this data to the Internet via a wired Ethernet connection.
The three components of this system—device, chip, and router—must all agree upon the same Wi-Fi standard: the upcoming Wi-Fi 6, 802.11ac (also known as Wi-Fi 5), etc.
Cellular for IoT
IoT devices that use cellular technology connect to the Internet using the same networks as smartphones and other mobile devices. Devices with cellular capability must have a modem to communicate with the nearest cell tower, sending and receiving information. In order to control the modem, the device uses a low-level communications protocol such as UART or SPI.
Two of the most popular modern cellular IoT technologies are LTE-M (Long-Term Evolution for Machines) and NB-IoT (Narrowband IoT). LTE-M is faster and is compatible with the existing LTE infrastructure. On the other hand, NB-IoT requires cellular providers to upgrade their hardware, which is why its rollout has been slower than LTE-M so far. NB-IoT also has a wider range than LTE-M, but requires the device to be stationary.
Wi-Fi vs. Cellular: IoT Feature Comparison
This section will dive into how Wi-Fi and cellular stack up in terms of different features for IoT devices.
Cellular networks tend to be much more expensive than Wi-Fi on a per-bit basis. As a result, Wi-Fi is clearly preferable when you plan to make big data transfers such as security updates on a recurring basis. In addition, you can sometimes “piggyback” off an existing public or private Wi-Fi network to save on costs.
Security and Privacy
Cellular networks enjoy two major security advantages over Wi-Fi:
- Cellular data is encrypted by default, while encryption must be enabled for Wi-Fi connections.
- Cellular security updates are done by providers with knowledgeable, dedicated cybersecurity staff and very strong financial and reputational incentives to prioritize security. On the other hand, Wi-Fi security requires the individual Wi-Fi network owner to proactively install updates.
As a result, cellular networks are generally held to a higher security standard than public Wi-Fi networks. However, private Wi-Fi networks that are well-maintained by a large organization will likely offer security that’s as strong as any cellular network.
Both Wi-Fi and cellular can provide accurate location information by measuring your distance from the nearest router or cell tower, respectively. In some instances, cellular networks may be able to pin down your location when you’re out of range of Wi-Fi.
Today, cellular networks are both extensive and growing. Cellular IoT technologies like LTE-M and NB-IoT provide deeper coverage than do traditional cellular technologies, expanding connectivity to places like underground, metal buildings, and rural environments.
Wi-Fi has a larger range than cellular, but it’s also more easily obstructed by obstacles. As a local area network (LAN), Wi-Fi can provide strong coverage in a limited area close to an access point. Once the device leaves that area, however, connectivity will decline rapidly. In other words, Wi-Fi isn’t the best choice if the device will be highly mobile or deployed in a remote location.
The maximum speeds of both Wi-Fi and cellular have now reached relative parity, with one big caveat: you’ll pay significantly more to achieve these speeds on a cellular network.
Wi-Fi has traditionally performed better than cellular in terms of bandwidth. Older 802.11b/g/n Wi-Fi technologies offered speeds up to 450 megabits per second (Mbps), and the newer 802.11ac standard can reach 1.3 gigabits per second (Gbps).
Cellular technologies based on the 4G LTE standard are today as fast as 1 Gbps, making cellular bandwidth roughly on par with Wi-Fi. These days, cellular is sufficient for nearly every IoT use case (except perhaps streaming high-definition video). In addition, the impending 5G upgrade is expected to offer further improvements to cellular bandwidth.
Wi-Fi does have one disadvantage: the more devices trying to access the network, the more the Wi-Fi signal will degrade. This means that Wi-Fi performs noticeably worse in high-population areas as devices compete for bandwidth. Cellular networks typically don’t face this issue, thanks to the technology’s underlying protocols and hardware.
Both cellular and Wi-Fi technologies can eat up a lot of power if you’re not judicious in saving battery, although Wi-Fi will probably use somewhat less. Device manufacturers deal with these issues in two ways: either putting the device to sleep and waking it up at regular intervals, or disabling the connectivity when it’s not in use.
Wi-Fi vs. Cellular: Which is Better for Your IoT Project?
Deciding between cellular vs. Wi-Fi for your IoT device? As we’ve discussed, there are many factors and variables that can make this decision more complicated than it first appears.
Choosing between Wi-Fi and cellular for your IoT project will depend largely on the priorities of your device and what it will be used for. Ultimately, the decision will come down to making the tradeoff between power consumption, bandwidth, coverage, and security.
In many cases, either Wi-Fi or cellular will be obviously preferable for your situation in terms of technology. However, business requirements can be a complicating factor as well. For example, you might prefer to use Wi-Fi for your next IoT project, but the devices will be deployed in third-party retail stores that may not be able or willing to provide their Wi-Fi credentials.
No Clear-Cut Winner
The question of Wi-Fi vs. cellular for IoT may not even be a direct competition at all. Both technologies are used for different kinds of problems, and neither one is clearly superior in all instances. Many IoT products even use both cellular and Wi-Fi in order to have a backup in place if the primary technology fails.
Here at Very, we help our clients create IoT devices with the technology that best suits their situation—whether it’s Wi-Fi, cellular, or something else entirely. To learn more about our development philosophy for IoT projects, check out our complete guide to the IoT development process.