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?
I liked the idea of a mesh network very much.I see it saving power in transmission power as hops are smaller.
Also it makes the network more robust if your full network doesn't rely on the gateway in the middle. That last point would link to Security and deeply embedded: if you only need to take one node down, the hackers will focus on that one.
Worse than taking one node down is using one as a source for attacks. If you have a network of devices and one is vulnerable to attack, it can be used for many nefarious purposes from snooping to spoofing to running DoS attacks on the local network.