Fangda Zhikong: Understand ZigBee Wireless Smart Street Light Solution Technology in One Article

　　Smartization is currently the hottest topic. From smart homes and smart offices to smart street lights and smart cities, many companies in the lighting industry are actively transitioning to the smart field. As the most widespread lighting infrastructure in cities, street lights have also attracted the attention of many lighting professionals.

　　In recent years, China has vigorously developed smart cities, with new road construction and old light retrofits, all implementing street light smartization. ZigBee technology has also been widely applied in street lights, so how exactly does the ZigBee wireless smart street light solution achieve street light smartization? Today, the editor will give you a general overview.

　　1. What exactly is ZigBee technology?

　　ZigBee is a low-power LAN protocol based on the IEEE 802.15.4 standard. According to international standards, ZigBee technology is a short-range, low-power wireless communication networking technology. It is a communication standard, not a technology owned by any particular company.

　　2. Can a Zigbee wireless gateway support 65,535 nodes or 254 terminals (nodes)?

　　(ZigBee Networking Topology)

　　The topology diagram above uses a star networking method. If this networking method is adopted together with the MESH (routing) function of the router, one coordinator can support 65,535 nodes, with 65,535 being the maximum limit. However, in practical applications, considering network congestion, latency, throughput, and node stability, generally that many nodes will not be configured.

　　In addition, because ZigBee is a low-power, short-range communication mode, the issue of communication distance must be taken into account in practical applications. Therefore, the "dual identity" of the terminal devices used in actual applications (being both nodes and routers), so a coordinator (gateway) generally has a maximum access of 254 terminals.

　　3. How does the ZigBee gateway advertised in the industry manage 300-1000 nodes? What are its advantages and disadvantages?

　　As can be seen from the topology diagram, the system consists of four parts: coordinator, terminal (routing + node), router, and node. By adjusting the ratio of terminals to routers, it is possible to connect 255 to 65,535 nodes.

　　Advantages: A single coordinator (gateway) can support more nodes.

　　Disadvantages: Communication speed slows down. Once the number of nodes exceeds 254, the communication efficiency of the entire network declines — the more nodes, the slower it gets. Regional failures are prone to occur. If a router fails, all nodes under that route will be unable to communicate.

　　The communication distance is actually controlled by the transmission power level.

　　The greater the transmission power, the farther the distance; the lower the power, the closer the distance.

　　The greater the power, the greater the power consumption; the farther the distance, the greater the possibility of mutual interference.

　　The smaller the power, the lower the power consumption; the closer the distance, the greater the possibility of being affected by external interference.

　　According to the application of ZigBee in street light control, a range of 100-200 meters is recommended, because the spacing between light poles is ≤50 meters.

Although the Zigbee wireless gateway can connect up to 254 terminals by adjusting the ratio of terminals and routers, in actual operation it often does not reach 254. Taking Zhejiang Fangda Zhikong Technology Co., Ltd. as an example, its ZigBee streetlight control system recommends that customers only carry 200 nodes.

　　V. So, why do we recommend that customers only carry 200 nodes?

　　1. Select 1 frequency channel and PAN ID to establish a network

　　2. Allow access to 255 routers

　　3. Allow access to 65535 terminals via routing

　　Wireless single-lamp controller LCU51Z (router + terminal):

　　1. Equipped with routing and single-lamp functions

　　2. No external routing device required, can realize a self-organizing network of 255 terminals

　　Street light control application description:

For streetlight control, a linear (along both sides of the road) networking method is adopted, requiring the transmission distance between terminals to be at least >50 meters. The communication distance of LCU51Z/LCU12Z is ≥150 meters.

Each terminal must have MESH (routing) function to ensure that the signal can reach the device farthest from the gateway via relay. It is recommended that the terminals controlled by RTU500Z/RTU200Z should be within 200 units.

Because each terminal is both a node and a router, when a device fails, the system and other terminal devices can still operate normally without regional failure.

(Simulated application scenario of ZigBee communication terminal at streetlight site)