When it comes to the internet of things, perhaps the key enabling technology is wireless networking technologies. Without the two primary wireless data networking technologies — cellular and Wi-Fi — almost every IoT device would require a wired connection to the internet, dramatically limiting the ability of developers to create IoT applications that deliver value to businesses and consumers.
However, thanks to these two wireless networking technologies, IoT is big and getting bigger — research firm Gartner forecasted that in 2017, 8.4 billion connected things will be in use worldwide, with this number reaching 20.4 billion by 2020. With as many as 10 billion additional connected devices forecast to be deployed over the next three years, IoT application developers face an important question as the market continues to mature — given each technology’s bandwidth, cost, coverage and security characteristics, should they design their IoT applications to use cellular, Wi-Fi or both?
While the differences between Wi-Fi and cellular in terms of bandwidth and cost have been narrowing or disappearing, cellular is expanding on its coverage advantages. By definition, Wi-Fi is a local area network (LAN) which provides great coverage in a very limited area. Yet, the moment a connected device leaves that area, coverage is lost, which results in significant design limitations for IoT application developers. On the other hand, cellular data coverage today is extensive and growing, as wireless network operators compete with each other to offer better coverage to their customers. In addition, standard low-power wide-area (LPWA) cellular IoT technologies (LTE-M and NB-IoT) provide deeper coverage than traditional cellular technologies, expanding cellular connectivity to underground spaces, buildings and rural environments. While LPWA is new, it is rapidly being embraced by network operators, as upgrading 4G LTE infrastructure to support LPWA only requires a simple software update. For developers who want to deploy IoT applications around the world or to remote, underground or similar hard-to-reach locations, cellular provides clear advantages — advantages that will only grow over the coming years.
When evaluating the security differences between Wi-Fi and cellular, one must always remember that no network can ever be made 100% secure. Nonetheless, cellular does possess several security advantages over Wi-Fi. First, all cellular data is encrypted by default. Wi-Fi data can be encrypted, but this encryption has to be turned on. This introduces human error into the Wi-Fi security equation, and as seen in recent cybersecurity attacks, such human-error related vulnerabilities can and will be exploited by cybercriminals. In addition, cellular security updates are made by network operators who have dedicated cybersecurity staff in place and very strong financial and reputational incentives to ensure such updates are made as quickly as possible. However, Wi-Fi depends on individual Wi-Fi network owners to make security updates, and it is easy for individual Wi-Fi network owners to delay or overlook these updates. The problem with overlooking such updates was recently demonstrated by the Key Reinstallation AttaCK, aka KRACK, on the key exchange handshakes used in the Wi-Fi Protected Access (WPA) and Wi-Fi Protected Access II (WPA2) security protocols. Another security issue with Wi-Fi is cybercriminals can create “fake” Wi-Fi networks that unsuspected device owners connect to, allowing these criminals to hack into these owners’ devices. While creating fake cellular networks is theoretically possible, cellular’s built-in security advantages, as well as size and scale of network operators, make the creation of similar fake cellular networks much more difficult. As cyberattacks continue to increase, cellular’s security advantages give it a leg up on Wi-Fi for developers building applications where security is a key design consideration.
For years, Wi-Fi had a significant advantage in bandwidth over cellular, with older 802.11b/g/n Wi-Fi technologies offering speeds up to 450 megabits per second and the newer 802.11ac Wi-Fi technology offering speed up to 1.3 gigabits per second (Gbps). However, cellular technologies based on the 4G LTE standard are now as fast as 1 Gbps, making cellular bandwidth comparable with Wi-Fi. In addition, while new Wi-Fi technologies based on the 802.11ax standard promise speeds of up to 10 Gbps, new cellular technologies using the 5G standard will offer similar speeds. With cellular now able to come close, if not match, Wi-Fi in regard to bandwidth, when it comes to video and other high-bandwidth IoT applications, there is little to no difference between the two technologies on speed.
Security, bandwidth and coverage are not the only capabilities developers need to consider when deciding whether they their IoT applications should use cellular, Wi-Fi or both, but they might be the most important. In terms of cost and bandwidth, cellular has in recent years caught up to Wi-Fi, and today Wi-Fi’s advantages in these areas are minimal or non-existent. However, when it comes to coverage and security, cellular has significant advantages over Wi-Fi, advantages that it will build on over the coming years.
Despite these advantages, Wi-Fi is not going away anytime soon. Wi-Fi has a strong established base in most households, and the fact there are no additional costs to connect multiple devices to a Wi-Fi network means that Wi-Fi will likely continue to be used for many consumer and smart home IoT applications over the coming years. In addition, with costs coming down for both technologies, building IoT applications that support both Wi-Fi and cellular connectivity is an increasingly attractive option for developers looking to cover all their bases and differentiate their consumer versus enterprise-level services. However, with cellular increasingly equal to or better than Wi-Fi in terms of bandwidth, cost, coverage and security, many developers who previously might have only considered Wi-Fi for their IoT applications are likely to be looking at, if not switching to, cellular over the coming years.
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