As you may know, the MetaWear platform is a wearable, sensor, and beacon development board that uses Bluetooth Low Energy (BTLE) for wireless communication. We decided to use BTLE over other protocols such as Bluetooth Classic, WiFi, and WiFi Direct because BTLE:
Has lower power consumption.
Can be powered by a coin cell battery
Battery can last for months or even years depending on use case
Is a less complex protocol.
Costs less to implement (unit costs, layout, firmware, etc.).
While the other protocols offer some nice pros, namely higher data throughput and farther range, we believed in the end, BTLE is the best choice for wearables, sensors, and beacons. Now, you may be thinking that it is silly to sacrifice superior data throughput and range however, none of the aforementioned use cases justified trading the power, complexity, and cost benefits of BTLE.
Use Case Breakdown
Take for example, an activity tracker such as the FitBit. While the accelerometer may be producing data at 100Hz or higher, the wearable processes the data on-board converting acceleration data into metrics such as step count and calories burned. These metrics do not need to be recorded with millisecond granularity thus considerably reducing the amount of data that will be transmitted. Moreover, this data is recorded on-board and synced with a mobile device at a later time.
On the sensor side, medical devices that stream live data, such as blood pressure or glucose monitors, usually only need to sample data every few seconds or less and are streamed live to either a mobile device on hand or a visualizer sitting next to the patient. Use cases such as monitoring environmental temperature or humidity, either in a room or outdoors, do not require sampling data more frequently than once every 30 seconds.
Lastly, beacons do not transmit any data. All they do is simply advertise their presence along with some uniquely identifying information to distinguish themselves among each other. A mobile app can utilize the signal strength and unique identifiers to find the closest beacon and lookup specific information about the surrounding area like which bus you are currently riding or which exhibit you are looking at.
In all of these scenarios, the higher throughput and farther range offered by the other solutions are simply not needed. Furthermore, the two biggest priorities for these types of devices are battery life and cost which BTLE delivers in spades. After taking into consideration all advantages BTLE brings to the table , it was a no-brainer for us to use Bluetooth Low Energy for the MetaWear platform.
If you are now curious about Bluetooth Low Energy and want to learn more, check out this post by Laura which covers the basics of BTLE.