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Zigbee is an emerging short-range, low-rate, low-power wireless network technology. It is a technical proposal between wireless tag technology and Bluetooth.It was previously called "HomeRF Lite" or "FireFly" wireless technology, which is mainly used for short-range wireless connections.He has his own radio standard, which coordinates communication among thousands of tiny sensors.

These sensors require very low power consumption,Relay data from one sensor to another through radio waves,Therefore, their communication efficiency is very high. Finally, these data canEnter the computer for analysis or be collected by another wireless technology such as WiMax.The basis of Zigbee is IEEE802.15.4 which is IEEE wireless personal area network(Personal Area Network，PAN)A standard of the working group is called IEEE802.15.4 (Zigbee) technical standard.Zigbee is not just the name of 802.15.4.

IEEE only deals with low-level MAC layer and physical layer protocols, so the Zigbee Alliance standardizes its network layer protocols and APIs (as shown in Figure 2 below).The full protocol is used for the basic section that can be directly connected to one device at a timePoint 4K bytes or 32K bytes as a hub or router coordinator. Each coordinator can connect up to 255 nodes, and several coordinators can form a network,There is no limit to the number of routing transmissions. The Zigbee Alliance has also developed a security layer to ensureThis portable device will not accidentally leak its identification, and this long-distance transmission using the network will not be obtained by other nodes.

The main features of Zigbee technology include the following parts:

   *Low data transmission rate: only 10k bytes/sec to 250k bytes/sec, focusing on low transmission applications;

   *Low power consumption: In the low-power standby mode, two ordinary AA dry batteries can be used for 6 months to 2 years, eliminating the trouble of charging or frequent battery replacement. This is also a unique advantage that Zigbee supporters have always been proud of;

   *Low cost: Because Zigbee has low data transmission rate and simple protocol, it greatly reduces costs. And the Zigbee agreement is free of patent fees.

   *Short time delay: usually the time delay is between 15 ms and 30 ms;

   *Security: Zigbee provides data integrity checking and authentication functions, the encryption algorithm adopts AES-128, and its security attributes can be flexibly determined;

   *Large network capacity: Each Zigbee network can support up to 255 devices, that is, each Zigbee device can be connected to another 254 devices;

   *Excellent network topology ability: ZigBee has the ability of star, tree and cluster network structure. ZigBee devices actually have wireless network self-healing capabilities, which can easily cover a wide area; 

   *The effective range is small: the effective coverage range is between 10 and 75 meters, depending on the actual transmit power and various application modes, which can basically cover ordinary home or office environments;

   * Flexible working frequency band: The frequency bands used are 2.4GHz (global), 868MHz (Europe) and 915MHz (US), all of which are license-free frequency bands