ZigBee introduction and characteristics analysis
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, mainly used for short-range wireless connections. It has its own radio standard that coordinates communication among thousands of tiny sensors. These sensors only require very low power consumption, relaying data from one sensor to another through radio waves, so their communication efficiency is very high. Finally, the data can be entered into a computer for analysis or collected by another wireless technology such as WiMax.
The basis of Zigbee is IEEE802.15.4 (as shown in Figure 1 below), which is a standard of the IEEE Wireless Personal Area Network (Personal Area Network, PAN) working group, and is called the 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 standardized its network layer protocols and APIs (as shown in Figure 2 below). The complete protocol is used for 4K bytes that can be directly connected to the basic node of one device at a time or 32K bytes as the coordinator of Hub or router. 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 ensure that such portable devices will not accidentally leak their identification, and that this long-distance transmission using the network will not be obtained by other nodes.
The Zigbee Alliance was established in August 2001. In the second half of 2002, the four giants Invensys, Mitsubishi Electric, Motorola, and Philips Semiconductors of the Netherlands announced that they will join the "Zigbee Alliance" to develop the next-generation wireless communication standard called "Zigbee". This event became a milestone in the development of the technology.
So far, in addition to internationally renowned large companies such as Invensys, Mitsubishi Electronics, Motorola and Philips, the alliance has about 20 member companies, and is growing rapidly. It includes semiconductor manufacturers, IP service providers, consumer electronics manufacturers and OEMs, such as Honeywell, Eaton and Invensys Metering Systems and other industrial control and home automation companies, and even toy companies like Mattel. All these companies participated in the IEEE 802.15.4 working group responsible for the development of Zigbee physical and media control layer technical standards.
According to the current assumptions of the Zigbee Alliance, Zigbee's target markets mainly include PC peripherals (mouse, keyboard, game joystick), consumer electronic devices (remote control devices on TV, VCR, CD, VCD, DVD, etc.), home Intelligent control (lighting, gas metering control and alarm, etc.), toys (electronic pets), medical care (monitors and sensors), industrial control (monitors, sensors and automatic control equipment) and other very broad fields.
The government's plan gave Zigbee more space, showing its incomparable confidence. According to reports, the US Department of Energy has decided to hire Honeywell InternaTIonal Inc., hoping to use Zigbee sensors to reduce the cost of these energy sources by 15% in steel, aluminum and six other industries. By installing sensors in the pipeline systems of companies such as Alcoa, Dow Chemical, and ExxonMobil, real-time tracking and monitoring of gas usage during product production.
The main features of Zigbee technology include the following parts:
Low data transmission rate: only 10k bytes / second to 250k bytes / second, focusing on low transmission applications;
Low power consumption: In the low-power standby mode, two ordinary No. 5 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 data transmission rate is low and the protocol is simple, the cost is greatly reduced. And Zigbee agreement is free of patent fees.
Short delay: Usually the delay is between 15 ms and 30 ms;
Security: Zigbee provides data integrity check and authentication functions, the encryption algorithm uses AES-128, and can flexibly determine its security attributes;
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 simply cover a wide area;
Small effective range: the effective coverage range is between 10 and 75 meters, depending on the actual transmission power and various application modes, which can basically cover the ordinary home or office environment;
Flexible working frequency band: The frequency bands used are 2.4GHz (global), 868MHz (Europe) and 915MHz (United States), all of which are license-free bands.
More importantly, it is predicted that in the next 6 to 7 years, home users will occupy the Zigbee 2/3 market. In the foreseeable future, Zigbee wireless sensing will truly change your life.
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