Many Faces of ZigBee

Technologies to enable wireless and low power consumption are required for monitoring and measuring devices and equipment at homes, commercial buildings, and factories. Among the many network protocols, ZigBee is gaining in popularity. It is getting into the mainstream of the home networking area, especially in communication by smart meters. Millions of smart meters will be shipped with ZigBee in them.

So I thought the game was over and ZigBee had won in its original form. As part of researching the network protocols used in commercial buildings, I studied ZigBee in detail. ZigBee is becoming a mainstream name for sure but not necessarily in its original form. I will discuss several flavors of ZigBee in this blog but as an overview, not in technical detail.

As is well known, ZigBee’s stack runs on top of IEEE 802.15.4, which specifies PHY and MAC layers. ZigBee has its own network layer with its application layer on top of it. But there are many flavors:

  • ZigBee (original form: ZigBee 2006)
  • ZigBee Pro (ZigBee 2007)
  • ZigBee RF4CE
  • ZigBee IP

ZigBee’s page states that ZigBee Pro:

the most widely used specification, is optimized for low power consumption and to support large networks with thousands of devices.

According to Wikipedia, it:

offers more features, such as multi-casting, many-to-one routing and high security with Symmetric-Key Key Exchange (SKKE).

ZigBee, on the other hand:

offers a smaller footprint in RAM and flash.

Differences are discussed in more detail by the ZigBee Alliance.

The ZigBee Alliance states that ZigBee RF4CE:

[is] for simple, two-way device-to-device control applications that do not require the full-featured mesh networking capabilities offered by ZigBee 2007. ZigBee RF4CE offers lower memory size requirements thereby enabling lower cost implementations. The simple device-to-device topology provides easy development and testing, resulting in faster time to market.

ZigBee RF4CE provides a multi-vendor interoperable solution for consumer electronics featuring a simple, robust and low-cost communication network for two-way wireless connectivity.

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HP Power Advisor Utility a Tool for Estimating Power Requirements for HP ProLiant Server Systems
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ZigBee IP is an attempt to integrate IP into ZigBee so that ZigBee application profiles can be used in the IP world. ZigBee Alliance has a presentation on this.

In short, ZigBee’s network layer is replaced with 6loWPAN (called the adaptation layer) to be compatible with the IP structure. Only UDP is supported; TCP is not. In addition, the application layer needs a modification (Constrained Application Protocol – CoAP) to accommodate the IP-based lower layers. ZigBee IP is not completed yet.

As I wrote before, both IP and wireless are becoming major forces in building management. In order to add sensors to measure energy consumption without drilling walls and laying cables, it would be ideal to have wireless sensors in existing structures. IP has become the network protocol of choice, designated by NIST as part of the smart grid standard technology.

The technologies are changing so rapidly that it is hard to keep up with the pace. At some point, I plan to write a short technical report on ZigBee.

Zen Kishimoto

About Zen Kishimoto

Seasoned research and technology executive with various functional expertise, including roles in analyst, writer, CTO, VP Engineering, general management, sales, and marketing in diverse high-tech and cleantech industry segments, including software, mobile embedded systems, Web technologies, and networking. Current focus and expertise are in the area of the IT application to energy, such as smart grid, green IT, building/data center energy efficiency, and cloud computing.

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