What is the Zigbee specification?
The Zigbee specification offers full mesh networking capable of supporting hundreds of devices on a single network. The current Zigbee PRO 2017 features the most up-to-date specification for Zigbee PRO updated with the lessons learned from deployments in tens of millions of devices around the world. The Zigbee PRO has become the primary development choice for low-power networking in IoT applications facilitates ease-of-use and advanced support for larger networks comprised of thousands of devices.
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), 10kbs at 915 – 921Mhz (27 channels) and 100kbs at 868Mhz (63 channel). Transmission distances range from 10 to 100 meters, depending on power output and environmental characteristics. Sub GHz channels transmission ranges up to 1km.
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. Because of regulatory requirements, Zigbee has mitigated interferences in the sub GHz. Zigbee included power measurements to reduce power inputs so they communicate at the exact level of power required. Doing that in a mesh of nodes, reduces interference between nodes. Limits radio activity in order to comply with regulatory requirements.
How does Zigbee address wireless reliability?
Zigbee was designed for the hostile RF environments that routinely exist in mainstream commercial applications. Utilizing Direct Sequence Spread Spectrum in the 802.15.4 radio, with features including collision avoidance, receiver energy detection, link quality indication, clear channel assessment, acknowledgment, security, support for guaranteed time slots and packet freshness; Zigbee networks offer product manufacturers a highly reliable wireless communication solution.
How many nodes, or devices, can a Zigbee network support?
Zigbee’s addressing scheme is capable of supporting hundreds of 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.