ZigBee Specification FAQ  

  1. What is the ZigBee specification?
  2. What is a Feature Set?
  3. How do the two Feature Sets in ZigBee work together?
  4. What is the difference between the ZigBee and ZigBee PRO Feature Sets?
  5. How does ZigBee PRO Green Power feature work with ZigBee PRO networks?
  6. What makes devices using the ZigBee PRO Green Power feature battery-less?
  7. What types of devices are ideal for the ZigBee PRO Green Power feature?
  8. What are the IEEE 802.15.4 technical attributes on which the ZigBee specification is based?
  9. What methods does ZigBee use to achieve low power consumption?
  10. How does ZigBee compensate for possible interference in the 2.4GHz band?
  11. How does ZigBee addressing wireless reliability?
  12. How many nodes, or devices, can a ZigBee network support?

  1. What is the ZigBee specification?
    The ZigBee specification offers full mesh networking capable of supporting thousands of devices on a single network. The current ZigBee 2007 has two implementation options or Feature Sets. The ZigBee Feature Set is designed to support smaller networks with hundreds of devices in a single network and is the secondary development choice. The ZigBee PRO Feature Set is the primary development choice and it maximizes all the capabilities of the ZigBee Feature Set, plus facilitates ease-of-use and advanced support for larger networks comprised of thousands of devices. Both Feature Sets are designed to interoperate with each other, ensuring long-term use and stability.

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  2. What is a Feature Set?
    A Feature Set refers to a group, or set, of features that create two implementation options. There are two Feature Sets in the ZigBee 2007 specification: ZigBee PRO Feature Set (primary) and the ZigBee Feature Set (secondary).

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  3. How do the two Feature Sets in ZigBee work together?
    ZigBee PRO is the primary development choice; therefore, products built with the ZigBee Feature Set can only participate in a ZigBee PRO network as end devices. Due to the wide variety of products able to use ZigBee, interoperability of products is determined by ZigBee standards.

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  4. What is the difference between the ZigBee and ZigBee PRO Feature Sets?
    ZigBee PRO has a number of optimizations designed specifically for larger networks comprised of thousands of devices. Please see the Features and Benefits document for a more detailed list of features and a side-by-side comparison.

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  5. How does ZigBee PRO Green Power feature work with ZigBee PRO networks?
    By creating proxies in a ZigBee router device, each ZigBee PRO Green Power device is represented as always present on the ZigBee network - even when it is not powered on or present. These proxies forward and resend packets to ensure reliable communication, especially to destination devices, called sinks, that are not in the direct radio range of the Green Power device.

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  6. What makes devices using the ZigBee PRO Green Power feature battery-less?
    ZigBee PRO devices using the Green Power feature are able to complete communication with an average 100-500 µJ (micro Joule) of energy. This energy is often created by capturing the energy used to flip a switch via common energy harvesting techniques including piezo-electric elements and dynamo/electro-mechanic converters.

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  7. What types of devices are ideal for the ZigBee PRO Green Power feature?
    A variety of devices are well suited for lighting, HVAC, closures and energy management:
    • Lighting - Switch, remote control , light sensor, occupancy detector
    • HVAC- Temperature sensor, humidity sensor, CO² sensor, air flow sensor, valve actuator
    • Closure- Switch, closure sensor, door lock
    • Energy Management - Energy consumption sensor


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  8. What are the IEEE 802.15.4 technical attributes on which the ZigBee specification is based?
    ZigBee takes full advantage of a powerful IEEE 802.15.4 physical radio standard and operation in unlicensed bands worldwide at 2.4GHz (global), 915Mhz (Americas) and 868Mhz (Europe). Raw data throughput rates of 250Kbs can be achieved at 2.4GHz (16 channels), 40Kbs at 915Mhz (10 channels) and 20Kbs at 868Mhz (1 channel). Transmission distances range from 10 to 100 meters, depending on power output and environmental characteristics.

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  9. What methods does ZigBee use to achieve low power consumption?
    ZigBee lets battery powered devices can sleep for hours or even days, reducing battery use. The duty cycle of battery powered nodes within a ZigBee network is designed to be very low, offering even more energy efficiency and greater battery life. Once associated with a network, a ZigBee node can wake up and communicate with other ZigBee devices and return to sleep. Representative times as follows:
    • 30 ms (typical) = new slave enumeration
    • 15 ms (typical) = sleep slave to active
    • 15 ms (typical) = active slave channel access

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  10. How does ZigBee compensate for possible interference in the 2.4GHz band?
    ZigBee products have access to 16 separate, 5MHz channels in the 2.4GHz band. Several of these do not overlap with US and European versions of Wi-Fi™. ZigBee incorporates an IEEE 802.15.4 defined CSMA-CA protocol that reduces the probability of interfering with other users, plus ZigBee uses automatic retransmission of data to ensure network robustness. Because the duty cycle of a ZigBee product is usually extremely low, relatively few packet data units are transmitted, reducing the likelihood of an unsuccessful transmission.

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  11. How does ZigBee addressing wireless reliability?
    ZigBee was designed for the hostile RF environments that routinely exist in mainstream commercial applications. Utilizing Direct Sequence Spread Spectrum with features including collision avoidance, receiver energy detection, link quality indication, clear channel assessment, acknowledgement, security, support for guaranteed time slots and packet freshness; ZigBee-compliant networks offer product manufacturers a highly reliable solution.

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  12. How many nodes, or devices, can a ZigBee network support?
    ZigBee's addressing scheme is capable of supporting more than 64,000 nodes per network and multiple network coordinators can be linked together to support extremely large networks. The logical size of a ZigBee network ultimately depends on which frequency band is selected, how often each device on the network needs to communicate, and how much data loss or retransmissions can be tolerated by the application.

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