Bluetooth Low Energy, WiFi-6 and the future of IoT
New developments in both technologies, Bluetooth Low Energy (BLE) versions 4.2 and 5.2 and Wifi 6 are starting to bring them together. But what about this?
Bluetooth Low Energy is arguably the technology that “started” the Internet of Things (IoT). The problem with “classic” Bluetooth is that it requires a continuous connection. Battery life is limited and battery-powered devices need to be charged frequently. In the Internet of Things, this limits the use cases to which it can be easily applied. Bluetooth Low Energy solved these problems by putting devices to sleep between transmissions and maintaining their connectivity. It also allows for easy ad-hoc pairing. Along with various other technical improvements, this allowed the deployment of large numbers of low-power devices sharing relatively little data while significantly improving overall connectivity.
Until now, WiFi has evolved in a different direction, focusing primarily on faster data rates to enable high-definition content streaming and meet cloud computing needs. Power consumption was not a major issue, and frequency spectrum issues were not a major concern. The target market is a relatively small number of large, powerful, data-intensive devices. You could say that WiFi is like a sledgehammer and Bluetooth Low Energy is a scalpel – different tools for different jobs.
New Bluetooth developments
However, new developments in the two technologies are beginning to bring them closer together. On the Bluetooth side, data throughput increased with version 4.2, and version 5.2 introduced streaming capabilities for audio, as well as a new CODEC. It’s not quite high-definition video, but it moves Bluetooth Low Energy away from its IOT data-driven roots.
WiFi-6 brings new possibilities
When it comes to WiFi, WiFi-6 is an evolution that aims to improve WiFi capabilities for IoT solutions. As we mentioned above, previous iterations of WiFi were all about speed. This has been made possible through broadband channels. The other side of the coin is that they cannot be in large numbers in the limited spectrum allocated for free over-the-air use. It doesn’t matter if one or two users are streaming from the home router. But as anyone who’s used public WiFi in a busy place knows, networks can easily become saturated.
That’s why WiFi-6 takes a few tricks from the mobile world and divides the spectrum into subcarriers. This allows more users to transmit simultaneously, but at a lower data rate. These subcarriers can be used flexibly enough that different users can allocate different numbers of resource units depending on their needs during the same period.
Another improvement is the introduction of ‘Target Wake Time’, which allows devices to request to wake up after a set time interval and go to sleep in between. This feature aims to reduce the minimum power consumption level required for a WiFi device.
To further increase WiFi capacity in dense environments, MiMo antennas are included at both ends of the link to enable spatial sharing of the network. Additional features allow you to ignore overlapping networks with weak signals.
Crossover
All this brings WiFi to the field of information and communication technologies (IoT): dense networks, flexible use of data, battery-powered devices that use a limited amount of data. All of this is very similar to the Bluetooth Low Energy conversation a decade ago.
Bluetooth Low Energy and WiFi-6 – competitors?
But what about this? Now one will “win” and the other will “lose”, are these technologies “competitors”?
Not exactly. There is a clear connection. Both technologies are designed for a greater variety of IoT applications than ever before. However, significant differences remain: Bluetooth Low Energy still offers better low-power characteristics than WiFi-6, and WiFi’s data transfer capabilities are still significantly greater than Bluetooth’s. Bluetooth frequency hopping technology will always be more robust in noisy environments and ad hoc connection will always be easier to use with Bluetooth.
Convergence might be a better way to put it. IoT applications are becoming increasingly sophisticated, and often a single radio technology is not enough. One of the downsides to the progress of WiFi-6 is that the router has to become a more complex device than ever and handle more connections with different requirements. The Matter home automation standard is a good example of trying to manage different radio standards under one roof. This standard may consider the use of WiFi for bulk data exchange and Bluetooth for local configuration of devices.
It should be noted that Nordic Semiconductor, the leader of the Bluetooth Low Energy market, recently introduced the first WiFi device. Therefore, we can expect several dual-radio devices that support the latest generation of both technologies to arrive soon.
An option for System Designers
For system designers, it will probably be less a matter of choosing one or the other, but rather determining which system functions should use which wireless technology in many cases.
An analogy can be made with the evolution of mobile phones. At first, they were only connected to the mobile network. Over time, they became the multi-radio devices we carry around today. IoT applications follow the same path, starting with a simple point-to-point connection between a device and a device acting as a gateway. Today, we have many different solution architectures, including multi-radio networks, mesh networks, long-haul and short-haul networks, and various other permutations.
In summary, both technologies add capabilities that simply make anything possible. Neither is ready to go away anytime soon.
