SAN JOSE, Calif. — Arch Rock Corp. has formally announced its Compact Application Protocol, software to host Zigbee applications and services on Internet Protocol networks. The move is the first of what could be many efforts to unify fragmented home control networks for emerging smart metering applications.
The move comes at a time when an ad hoc group of utility companies is calling for interoperability standards between different control network technologies. The standards would pave the way for their plans to link residential electric meters, thermostats, lights and other devices.
The low cost wireless 802.15.4 links used by Zigbee are ideal for electric meters. However, the radios cannot reach from clusters of meters into residences in many apartment buildings, driving a need for powerline or other options, said Roland Acra, chief executive of Arch Rock.
In late August, the utilities along with members of the Zigbee Alliance and the HomePlug Powerline Alliance announced plans to extend the existing Zigbee Smart Energy application profile to run on HomePlug networks. Arch Rock detailed its CAP software as a possible solution to members of the group at its latest meeting on October 9 in Vancouver.
The utilities "want to see the same behaviors across different networks," he said. "They hope to have something on the market by the spring of 2010," he added.
Arch Rock, a startup which sells IP sensor networking systems and tools, has been looking for ways to leverage the Zigbee efforts into its vision for leveraging Web technologies to make IP dominant in low end sensor networks. The company demonstrated an early version of CAP at the Sensor Expo conference in June.
The startup submitted a detailed technical draft of CAP as a suggested draft standard to the Internet Engineering Task Force in early October. Acra said the company is open to any group adopting CAP including the IETF, the Zigbee Alliance or the ad hoc working group of utility companies.
CAP marries the application layer profiles and security features of Zigbee on to UDP/IP network and transport layers "without any significant performance penalty," according to Acra. A full IP sensor node stack requires less than 50 Kbytes, while some Zigbee stacks requires as much as 128 Kbytes, he added.
The Arch Rock approach embeds Zigbee application protocol information in UDP packets and chooses a UDP port, allowing devices to communicate using an IP address and port instead of a Zigbee network address. The approach leaves intact the clusters, attributes, commands and data types used by the Zigbee profiles, Arch Rock claims.
CAP implements Zigbee APS acknowledgements and retries and security features. Specifically, the Zigbee Trust Center and Zigbee Discovery Cache run on trusted IP hosts under CAP. The Arch Rock approach modifies Zigbee binding commands and discovery commands to include the IP address and port.
It's not clear what other proposals may come before the utilities' working group. Two other types of powerline technology compete with the HomePlug products. Other home control nets include Insteon, X-10 and LonWorks.
The working group has kicked off committees to define target user scenarios and translate them into market requirements, said Acra. A separate technical group will evaluate technology proposals for how well they serve those market needs, he added.
The CAP spec is available from the IETF. Arch Rock has not yet determined on what basis it will make its implantation of CAP available.
