Thursday, June 18, 2015

Standardization of Zigbee Technology

Picture taken from zigbee.org
As mentioned on Zigbee.org,  "ZigBee is the only open, global wireless standard to provide the foundation for the Internet of Things by enabling simple and smart objects to work together, improving comfort and efficiency in everyday life". For now, it is truly the most widely used and recognised for standardization of low rate wireless communication network. As an open standard, many companies are supporting on development of this technology. It is also the most interoperable connected devices such that has large ecosystem in the market compared to the other technologies in the field of wireless sensor networks.

Zigbee was born due to the necessity of low-power low-cost wireless networking in residential and industrial environments. Two standards groups Zigbee and IEEE 802 Working group 15 work together to work on it in 2000. As a result, IEEE 802.15.4 LR-WPAN (Low Rate Wireless Personal Area Network) standard was released and its specification  had been ratified in December 2004. Zigbee technology refers to this standard as the initial standard. Continuing the standard, in 2006 and 2007 there are amendments for standard. The latest update standard applied for Zigbee technology is Zigbee standard released in 2012.

Apparently, Zigbee Technology only adopt for two bottom OSI layers: PHY and MAC layer from standard IEEE 802.15.4.   Network, security and application support layers are defined by Zigbee alliance. Application layer is adjusted to manufacture definition by each partner companies. But still, it is under supervision of Zigbee Alliance. Only certified companies that have access the standard and granted for permission to use it.

PHY layer defined by IEEE 802.15.4 including  frequency band and corresponding data rate and number of channel, range coverage, latency, channel access method and working temperature. Some other specifications defined by PHY layers are channel switching, link quality estimation, energy detection measurement, and clear channel assessment to assist channel selection. Whereas, MAC layer  must support two operational mode: beacon and non-beacon mechanism. Defined specifications include association-disassociation link, acknowledgement frame delivery, channel access mechanism, frame validation, guaranteed time slot management, and the beacon management. These technical stuff are basic key technologies which enable robust system of Zigbee technology.

For network layer, Zigbee alliance defines several types of standard: Zigbee RF4CE, Zigbee IP and 920IP, and Zigbee Pro with Green Power. Zigbee RF4CE aims for interoperable solution in controlling consumer electronic products for instance controlling home entertainment electronics with robust and low-cost communication. As for Zigbee IP and 920 IP, it is standard for Zigbee which capable to support IP protocol including IPv6. This is the first open-standard IP based for wireless sensor network. The last one is Zigbee Pro with Green Power which aims for foundation of Internet of Things as it is capable to support mesh network supporting large number of nodes.

Zigbee standard for application has been released by Zigbee Alliance. The most widely used is of course Zigbee Home Automation. Another standards for application are: Zigbee Building Automation, Zigbee Health Care, Zigbee Input device, Zigbee Light Link, Zigbee Remote Control, Zigbee Retail Services, Zigbee  Smart Energy, Zigbee Telecom Services and Zigbee 2030.5(specific for global standard ip-based wired/wireless energy management in home area networks). Most of their applications have been mentioned in previous post. All of this standard are then just adopted by the partner companies which has access of Zigbee technology.

Current development of Zigbee is Zigbee 3.0. this standardization is expected to be single standard for all solutions. For all zigbee application standard, this standard can work interoperable each other.  Currently it is under development by several companies and estimated to be ratified in 2015. This standard will be one of milestone of zigbee standardization because it will unify all standard that has existed. In the future, the standard will converge to this standard which is very good.


References:

Callaway, Ed, et al. "Home networking with IEEE 802. 15. 4: a developing standard for low-rate wireless personal area networks." IEEE Communications magazine 40.8 (2002): 70-77.
Stevanovic, Dusan. "Zigbee/IEEE 802.15. 4 Standard." York University, June(2007).
http://www.zigbee.org/