Characteristics and application of beer technology

The word ZigBee comes from the fact that when bees find the pollen position, they tell their companions by dancing zigzag to exchange information. It can be said that a small animal has realized "wireless" communication in a simple way, which is called short-distance wireless network communication technology with low power consumption, low cost, low complexity and low speed, and it also contains profound meaning. ZigBee technology is not a completely unique new standard. Its physical layer, MAC layer and link layer all adopt IEEE802. 15.4 standard, but it is improved and expanded on this basis. Its network layer, application convergence layer and high-level application specifications are formulated by ZigBee Alliance. The characteristics of ZigBee are outstanding, especially in terms of low power consumption and low cost, which are mainly manifested in the following aspects [2].

① Low power consumption. In low-power standby mode, two No.5 dry batteries can support 1 node to work for 6 ~ 24 months, or even longer. This is the outstanding advantage of ZigBee. In comparison, Bluetooth can only work for a few weeks, and WiFi can only work for a few hours.

② Low cost. By greatly simplifying the protocol (less than Bluetooth's110), the requirements for the communication controller are reduced. According to the prediction and analysis, based on the 8-bit microcontroller of 805 1, the full-function master node needs 32KB code, the sub-function node only needs 4KB code, and ZigBee is free of protocol patent fees.

(3) slow speed. ZigBee works at a low rate of 20 ~ 250 kbps, providing raw data throughput of 250kbps(2.4GHz), 40kbps(9 15MHz) and 20kbps(868MHz) respectively, which meets the application requirements of low-rate data transmission.

4 Close range. The transmission range is generally between 10 ~ 100 m, and it can be increased to 1 ~ 3 km after increasing the RF transmission power. This refers to the distance between adjacent nodes. If the relay of routing and communication between nodes is adopted, the transmission distance will be further.

⑤ Short delay. The response speed of ZigBee is relatively fast. Generally, it only takes 15ms to switch from sleep to work, and it only takes 30ms for nodes to access the network, which further saves electricity. Comparatively speaking, Bluetooth needs 3 ~ 10, and WiFi needs 3s.

⑥ Large capacity. ZigBee can adopt star, sheet and mesh network structure. A master node can manage multiple child nodes, and a master node can manage up to 254 child nodes. At the same time, the master node can also be managed by the upper network nodes, which can form a large network with up to 65,000 nodes.

⑦ Simple protocol and high security. The average length of ZigBee protocol stack is only 1/4 of Bluetooth. This simplification is very important for low cost, interactivity and maintainability. ZigBee technology provides data integrity check and authentication functions, and provides a three-level security mode, which can flexibly determine its security attributes and effectively guarantee network security.

8 License-free frequency band. Direct sequence spread spectrum is used in industrial science and medical (ISM) frequency bands -—2.4GHz (global), 9 15MHz (USA) and 868MHz (Europe).

From the main technical characteristics of ZigBee mentioned above, it can be seen that thousands of tiny sensors can realize cooperative communication based on IEEE802. 15.4 standard. In addition, using relay to transmit data from one sensor to another through radio waves can make communication efficiency very high. Compared with various existing wireless communication technologies, ZigBee technology is most suitable for wireless sensor networks because of its low power consumption and low rate.