Near Field Communication (NFC)
NFC works best for wearables that require low power consumption. It involves the transfer of tiny amounts of data over a very short range, essentially by touching two devices together. The devices will switch between two different modes: Active and passive. The power consumption for NFC is similar to what we see in Bluetooth Low Energy, although higher when communicating with a passive tag.
If you need your wearable to transfer data over a longer range, you should look for other options.
Bluetooth Low Energy (BLE)
This technology is known as an easy to implement, low-cost option that requires very little power from your wearable. Your product can be powered by a coin cell battery for months - even years in some cases. But BLE comes with a compromise: Your data throughput will be limited. As most wearables generally transfer very little data, product owners can usually live with this.
Using BLE requires your device to be paired with a host, most usually a cellphone with an app activated.
If you plan for your wearable to transfer higher amounts of data frequently,Bluetooth Low Energy may not be the best choice. Limited data transfer capacity makes this technology unsuitable for audio and video streaming, for example.
The sensors and other nodes will act as either slaves or masters within a wireless network. Each node can transmit, receive or even function as a repeater to increase the range of the network. You can configure the network to spend long periods in low-power sleep mode, consuming extremely little power.
If your wearable needs to transfer a lot of data with as little lag as possible, Wi-Fi is your best option. The technology is best when streaming huge amounts of data, like video, but its main drawback is high power consumption that will require daily battery charging.
By using Wi-Fi, your wearable product can connect directly to the Internet via a Wi-Fi Access point.
The best of all worlds?
Some wearables combine different wireless technologies to take advantage of different aspects of each method. The Apple Watch uses Bluetooth Classic, BLE, Wi-Fi, and even NFC for mobile payments. Nordic Semiconductor is currently the only manufacturer delivering chips that support both ANT and Bluetooth Low Energy (BLE), as well as NFC - all in one low power, 'system on chip' solution.
Hopefully, you’re now a little clearer on which wireless technology is best for you. If you’re still struggling, consider your product priorities. Is it size, power consumption, user experience, cost, or something else? Once you're clear on the priorities for your wearable, your wireless communication options become a lot clearer, too.