What is Zigbee:
Zigbee is a Personal Area Network (PAN) based on the IEEE 802.15.4 standard. It is a famous wireless protocol due to its low cost, low data rate and low power consumption in wireless communication. Zigbee protocol is used in many applications like Home Automation, smart energy metering and medical field. One Zigbee Network can contain upto 65,000 nodes. It has only one limitation having low data rate, typically not more than 250 kbits/sec. Based on antenna, transmitter output power and frequency Zigbee has range about 10 to 100 meters.
Zigbee in the Frequency Spectrum:
Zigbee operates in the industrial, scientific and medical (ISM) radio bands. 2.4 GHz is most popular band having data rate up to 250kbits/sec. 915 MHz for USA and Australia, 784 MHz for china, 868 MHz for UK and UAE. Data rate varies from 20 kbits/sec to 250 kbits/sec.
How it works:
Zigbee supports star, tree and mesh topology. Zigbee network consists of Zigbee Coordinator, router and end devices. Zigbee coordinator is responsible for forming the network, Router provides routing services and end devices are leaf nodes.
Zigbee coordinator is responsible for forming the network. There will be only one coordinator in the Network. It starts a new Personal Area Network (PAN). After installing coordinator, router and End devices can join the network. It have an PAN ID and it assigns ID's to router as well as end points (Leaf nodes). Any command given to the network is executed by coordinator. It is powered by AC input. As it supports the child nodes therefore never go to sleep mode.
|Zigbee Coordinator||Zigbee Coordinator|
Zigbee router provides routing services to network devices. It associates with other routers and end-devices. First router needs to join the network then after that, you can add routers according to your requirements. There can be more than one router in a network. It can also serve as End Device but its slower.It is powered by AC input and never goes to sleep.
End Devices are basically leaf nodes. All sensors, actuators, meters, switches, dimmers falls in this category.These devices cannot allow other devices to join the Zigbee Network and have no role in routing.These are battery powered and do not support any child devices.They may sleep hence battery consumption can be minimized.
|Zigbee Door lock||Zigbee Motion Sensor||Zigbee Smart Plug|
Zigbee Network Operation:
Zigbee Network operates on Mesh topology. Coordinator is a main controller who controls all the network. It has hierarchy table and identification number of all the devices connected to the network. Router works as an intermediate device who provides a route to deliver information to the end devices. ZigBee networks are designed to conserve the power of the end devices. For most of the time, an end device is in deep sleep mode and wakes up only for a fraction of a second to confirm its presence in the network. Zigbee communication is done in two modes: Beacon and Non-beacon mode.
In a non-beacon mode,the coordinators and routers continuously monitor active state of incoming data hence more power is consumed. In this mode, the routers and coordinators do not sleep because at any time any node can wake up and communicate. However, it requires more power supply. This is used typically for security applications where end devices are motion sensors, door/window sensors, glass breakage sensors etc. End devices wake up on regular bases to ensure their presence in the network.
Beacon mode is more suitable when the network coordinator is battery operated. It enables all the end devices and routers to know when to communicate with each other. Any node added in the coordinator looks for any messages directed to it from coordinator. If no messages are pending, the end device returns to sleep, and awake according to a schedule specified by the coordinator. Once the client communications are completed, the coordinator itself returns to sleep. This property enables Zigbee devices having very long battery life.
Zigbee products are cheaper in price and best for the applications having less data rate. Due to less data rate and less power consumption, Zigbee devices has longer life. It has products regarding medical and health sciences, Home Automation, Industrial Automation, Smart Grid, Wireless metering, retails industry, telecommunication industry, and many more.
When we talk about limitations, Zigbee is on the top of the list. It has less data rate and range as compare to other wireless protocols.
Zigbee Alliance was founded in 2002. The alliance has three levels of membership: Promoters, Participants and Adopters. The purpose of alliance is to provide consumer cutting edge technologies in almost every field of life.
Zigbee security layer provides secured communication between end devices as well as between coordinators, routers and end devices. Every Zigbee network, and the devices within each network, are assigned unique identification numbers that communicate with coordinator of same network only. This makes Zigbee network more secured because any other coordinator can never control your network.
Zigbee technology has played its role in almost every aspect of life. Some Applications are:
Heath: Patient monitoring system: to measure and transmit blood pressure, blood glucose level, bed sensor controller, ECG, Body temperature etc.
Commercial Building Automation: Controlling devices for a large building.
Industrial Automation: For continuous measuring and monitoring of industrial parameters.
Smart Energy Metering: Wireless real time energy metering, for example smart plug.
Telecom Application: Wireless applications within the telecom area.
Retail: Monitoring and information delivery in a retail environment.
Smart Grid: Real time grid status, automatic fault finding and switching.
Home Automation: Control and Automation of Home resources like lighting, cooling, heating, security from anywhere in the world.
|Frequencies:||2.4 GHz, 784 MHz to 915 MHz|
|Maximum Data Speed:||250 kbits/sec|
|Average Data Speed:||100 kbits/sec|
|Network Topology:||Star, Tree and Mesh topology|
|Range:||10 to 100 meters|
|Founded- Union:||Zigbee Alliance|
|Main Application:||Medical, Home and Industrial Automation, Smart Grid|
|Power Consumption:||Idle: 1 μA , Tx: 20 mA, Rx: 40 mA|