Bluetooth 5 is Here
Rejoice developers, Bluetooth 5 has arrived! And with it, a lot of buzz is being generated about its capabilities. I’d like to dive into the meat of some of the more popular features a bit and then talk more about my personal favorite.
One of the key features of Bluetooth 5 is the ability to get 2Msps (mega symbols per second, or megabits when talking in context of low energy for this blog) out of Bluetooth low energy. This is done in the same power envelope as low energy today by changing the way that the signal modulation works. In a nut shell, it’s pretty simple. Bluetooth 5 doubles the modulation rate and we get approximately 2x gain on top of v4.2.
Moving from 1 Mbps to 2 Mbps, we are simply doubling the symbol rate. As a result the bandwidth (as seen in the frequency deviation) becomes twice as wide. This does not reduce the number of channels Bluetooth low energy can have because low energy was already at 2 MHz channel centers.
On the other end of the spectrum, we have increased range. How is this accomplished? Coding. There is a rate ½ code and a rate 1/8th code. The rate ½ code gets us approximately 4-5dB of sensitivity and about 2x the range at 500kbps, and the rate 1/8th code gives up to 12dB of sensitivity plus the 4x range at 125kbps. Bluetooth low energy at 125kpbs will be ~3 dB better than the 802.15.4 tech you see out there today. And at 500 kbps, provides a 15% lower duty cycle than 802.15.4 with twice the throughput.
Okay, so here is the caveat. You don’t get BOTH longer range and higher bandwidth in the same low power envelope. Remember, one is a new coding scheme, and one is a new modulation scheme. Think of this as a dial, or a lever, where you can tune the performance based on your application. Some applications, like firmware updates perhaps, would benefit from increased bandwidth (and distance isn’t a big detractor). Other applications, like an in-home thermostat, would benefit from the increased range (and the data that it transmits doesn’t need high bandwidth as it’s not very much data).
I promised an overview on my favorite feature…and here it is. The feature I am most excited about is the increased ad size.
But, we can’t simply increase the size of the packet without supersaturating the advertising channels if more devices start to advertise.
So, with Bluetooth 5, the advertising payload is offloaded onto the regular Bluetooth data channels, while keeping the ad’s header and overhead data on the normal advertising channels. In this way, we actually reduce the congestion on ad channels and give developers that ability to have up to 255 octets while utilizing the data channels for Bluetooth. Genius!
There is actually a LOT more to this feature, but the blog is a bit short to cover it all. I suggest that you have a look at the new spec to get the bigger picture and all of the benes that it brings.
I am a true believer in the idea of a ‘connectionless’ IoT. What I mean by this is that the standard pairing and bonding that we do today in a lot of Bluetooth device scenarios won’t necessarily be how all of the IoT devices will communicate. I believe that Bluetooth beacons can help in this space tremendously. And now with the advances of advertisements in Bluetooth 5, developers can really start to harness some cool solutions.
Now Go Build
Now that 5 is out and offers a lot of new, cool features for developers, think about how you can use it to make great experiences for your end users. Whole home coverage for you smart home devices. Fitness trackers that cache data after a long run and then transfer that data at lightening speeds when you get back to your phone, tablet, or PC. Beacons that can send 8x the data. This is great stuff…and I can’t wait to see what you all do with it!