Bluetooth Smart (formerly Wibri and then BLE) is being positioned as the likely backbone of IoT device communications. But, it has some serious limitations that call that concept into question:
1. It is a star bus type: one central node (today a smartphone or tablet most typically) to nearby devices. Hardly the always connected model of IoT.
2. Distance is about 150 feet of clear air, much less through walls and even with obstacles in the room.
3. Does not support mesh, so devices must directly connect to a "hub" in the star as noted above. Wifi->Bluetooth hubs add cost and then have to be well positioned to work.
4. No IoT type addressing method. Currently relies on pairing and fixed ID (e.g. "Brand_X_Heartrate_monitor") because they assume only one. A URI/URL could be constructed, but no mechanism exists for it now.
5. Bluetooth does not have any method for timed reconnect or other very very low power way to not be active all the time for end nodes. Keeping the RX on all of the time does not work well for a device left for months/years on one battery. Note that the mouse/keyboard approach of BLE works because they generate the connection on user action; that is, they do not have to listen for "commands" when inactive.
That said, what it shows is that Zigbee continues to be very unpopular (for good reason I think) and Wifi is too high power and too costly for many IoT type devices. 6LoPAN is technically solid, but the infrastructure to support it is not there, especially as the move to IPv6 is happening more in the cloud than in the LAN.
Thoughts?
H Paul, Thanks for the blog and your thoughts on BLE.
Have you heard about Weightless ? What is your take on this new specification that, in some regions, can make use of the TV white space freed up by the move from analogue to digital TV. I say 'in some regions' because I think that this is not applicable in the US - not yet anyway.
I have heard of it along with Cognitive and af and so on. The issue is that people are not looking for yet more different incompatible radio/protocol standards, but one. When every person sees all of these incompatible choices, it takes them back to Betamax vs. VHS, and all of the other incompatibility wars that leaves many losers. If you spend hundreds to thousands of dollars/pounds/euros on equipment using radio form X and the world suddenly tacks to radio form Y, you have worthless junk and you will be quite upset.
This is what has prevented adoption of anything broadly. The power companies seem to have settled on Zigbee Pro for the HAN, but they seem to be the only ones and interest in Zigbee is decaying. People making home-area-network endpoint devices are more likely using bluetooth or Wifi because it would work with smartphones and tablets - working with a Smart Meter is worthless right now especially as there is no controller readily available so it would be speculative at best. There are many other of these open/proprietary initiatives that have been around like ANT, ZWave, 6LoWPAN, various PLC, and of course other purely proprietary in all of the open bands (sub GHz and 2.x GHz and so on). The problem is that to use any of them for home control, building control, general IoT (a superset of those), or personal wireless network (WPAN), you need a control interface of some kind, and those are expensive unless they happen to be in your hands anyway (ie. your phone or tablet or computer). So, a gateway/bridge is needed - that is where this tends to fall apart. My guess is that eventually Wifi router vendors will incorporate bridges to one or more "winners" in this arena because people are generally loathe to install a dedicated bridge, especially if they are building up the network of such devices in a slow piecemeal fashion (where spending lots for the bridge to use the cheap endpoint does not fly). That is not to say that model is impossible. Many mouse/keyboard vendors included such USB bridge devices (often bluetooth) for computers and people did not flinch (too much anyway). But, these were also cheap enough, the location was not an issue (plug into computer or hub), and the single bridging function was well defined or proprietary. For this new model to work, it has to be an open bridge that will work across a wide range of products from various vendors. That likely means you end up with more than one incompatible bridges vs. one unifying one. It also means that "mesh" falls apart unless you buy from one vendor.
Part of the problem is that none of these radios are very cheap, so no one wants to add these things to their consumer electronics unless the customer values it at least as much as it is costs. Remember that it is not just the BOM cost but also getting certification in each country for radios (intentional radiators). Making these things modular is not really an option because there is no backing standard (e.g. USB) to base the modular connection on. That is the real problem here.
So, you have customers on the fence waiting for the dust to settle. You have CE vendors on the fence. You have the bold with nothing to show except extra cost. You have the advocates (e.g. weightless) talking it up over and over. We are at the same stalemate we have been since 2000 when dust/motes/etc was the next big thing except now we have even more contenders and not less! So, I think we may get the VHS type solution of Bluetooth (BLE) which is unsuitable/poor for many uses but easier to fall into because anchored by phones and tablets.