Nest's engineers considered a wide variety of home automation protocols before deciding they needed to develop a new one. "WiFi has single points of failure like an access point," so it was not suitable for the device-to-device mesh, says Boross.
ZigBee Pro lacks native IP support. Like other versions of ZigBee, it is limited to a 32-node mesh and has the potential for a single point of failure with its always-on network coordinator. ZigBee IP "doesn't have great power consumption profiles for some kinds of devices," in part because its "routing protocol is not as efficient," Boross contends.
ZWave (like a number of other alternatives) was rejected because it does not support IP and is not open. In addition, "its gateway is complicated."
The OpenWSN implementation of 6LoWPAN came the closest of all the options, but it lacks the built-in encryption and authentication functions Nest wanted. OpenWSN's Constrained Application protocol (CoAP) will run on Thread.
Boross sees the recent AllSeen and Open Interconnect Consortium projects initiated by Qualcomm and Intel, respectively, as app-layer efforts. "They don't include networking stacks, [but] are upper-level protocols that could run on Thread."
Apple is another player here with its HomeKit framework for iOS. "I haven't seen public information on HomeKit, so my opinion is TBD based on the technical details," says Boross.
Oleg Loginov, chairman of IEEE P2413, a new IEEE effort to establish standards for the IoT, says he expects more corporate alliances to form in the area, but he hopes that his group can help unify them.
"Any major technological shift -- and IoT is probably the most significant one in history -- starts with islands of innovation," Loginov says. "These early activities have to transform into global standards enabling the economy of scale and vibrant ecosystems."
Vint Cerf, a Google Fellow and adviser to the Thread group, said in a press release: "Existing wireless networking approaches were introduced long before the Internet of Things gained ground. The Thread protocol takes existing technologies and combines the best parts of each to provide a better way to connect products in the home."
— Rick Merritt, Silicon Valley Bureau Chief, EE Times