A radio transceiver is used by Zigbee smart devices to connect with one another. The chip runs on the IEEE 802.15.4 protocol at 2.4 GHz, which is the same frequency band as Wi-Fi and Bluetooth. A Zigbee message can also be copied and forwarded from one device to the next. This enables a network of devices to be controlled from a single hub or gateway.
ZigBee is a member of the family of wireless personal area networks (WPANs). It was created by the ZigBee Alliance as an open standard for small form factor devices. Devices must be certified by the alliance to be called ZigBee-compliant. There are two main types of ZigBee devices: endpoints, which transmit and receive data; and routers, which act as hubs between other devices and the internet.
Endpoints consist of light bulbs that can be turned on and off from your smartphone, sensors that measure temperature or humidity, and security cameras that can be accessed through a web browser. They usually have a battery life of about 1 year before they need to be replaced. Endpoints can be large or small, expensive or cheap. They just need to support the ZigBee protocol to be able to join a network.
Routers combine the features of a switch with those of a bridge. They allow you to connect several endpoints directly to a local network without using the internet.
Because ZigBee is a local area network (LAN), it is not meant to connect to devices in the immediate vicinity of a user, unlike Bluetooth LE. It instead connects to devices that require a greater range. Thus, ZigBee-enabled products can be connected without requiring physical contact.
ZigBee uses a low-power radio technology called infra-red (IR) to communicate between nodes. These nodes can be sensors, controllers, or other devices. The IR signal has a maximum transmission distance of about 100 feet with good conditions around the room you are in. Beyond this distance, you will need another node in the network to transmit data to others.
Bluetooth on the other hand, utilizes radio frequency (RF) to communicate over longer distances. It works by using modems and radios located in different devices to transmit data over limited distances. Bluetooth allows for voice communication as well as transfer of small files such as pictures, videos, and music. Its main advantage over ZigBee is that it supports more complex networking protocols such as peer-to-peer connections which allow two separate devices to exchange information directly. This is useful when you want your appliance to talk to another appliance rather than just a controller/hub/repeater. ZigBee cannot support these types of connections due to its limited role as a simple LAN technology.
What exactly is Zigbee technology? Zigbee communication is a product of the Zigbee alliance and is designed specifically for control and sensor networks based on the IEEE 802.15.4 standard for wireless personal area networks (WPANs). This communication standard specifies the physical and Media Access Control (MAC) layers required to manage a large number of devices at low data speeds. The first version of the standard was released in 2001 and since then many improvements have been made, with the most recent release occurring in 2016. Devices that use the ZigBee standard include light switches, lamp outlets, water heaters, air conditioners, and security cameras. It can also be used with smartphones and other portable electronics to extend their battery life while reducing the traffic handled by mobile networks.
ZigBee technology operates within a frequency range of 2.4 GHz to 2.5 GHz. All devices that communicate using this technology do so within the unlicensed ISM band. This means that other radio transmissions are possible but must be authorized by the FCC. In addition, devices that use ZigBee operate on very limited power supplies; typically batteries that cannot supply more than 1.5 volts. This makes them unsuitable for operations that require more powerful components such as Wi-Fi or Bluetooth.
Why use ZigBee instead of Wi-Fi? First, ZigBee is much more energy efficient when deployed in large numbers. A single ZigBee network can connect thousands of devices without requiring a huge amount of power.
As a result, Zigbee is a wireless ad hoc network that is low-power, low-data-rate, and close-proximity (i.e., personal area). The Zigbee specification defines a wireless personal area network (WPAN) technology that is designed to be simpler and less expensive than other wireless personal area networks (WPANs) such as Bluetooth or more broad wireless networking such as Wi-Fi. Its goal is to provide simple, reliable, secure communication within limited distances between small devices such as sensors, lights, etc. that are equipped with microcontrollers.
ZigBee nodes communicate via packets called frames. A frame can carry information on temperature, light, motion, sound, or any other phenomenon. It can also carry data from sensor to controller. There are two types of frames: command frames and data frames. Command frames are used by controllers to initiate actions on other nodes. Data frames are used to transfer data. Each node receives all frames sent in the network and ignores those not intended for it. Nodes send frames using either unicast or multicast addressing techniques. Unicast means sending one frame to only one destination address. Multicast means sending the same frame to multiple destinations. ZigBee uses tree broadcasting which is a type of multicasting where every node on the path to the target node sends the frame. This ensures that all nodes along the route receive the frame.
Nodes use the same three main methods to transmit frames: direct transmission, relay, or router. Direct transmission means transmitting a frame from one node to another without passing through a controller.
The IEEE 802.15.4 physical radio specification underpins the Zigbee standard, which runs in unlicensed bands such as 2.4 GHz, 900 MHz, and 868 MHz. It provides a low-power wireless personal area network (WPAN) solution that allows device connectivity within the range of 100 meters or less. The standard was developed by a group known as the ZigBee Alliance.
ZigBee is a widely used wireless personal area network (PAN) technology standard designed to take advantage of the ubiquity of WiFi access points. Devices equipped with ZigBee transceivers can join a network automatically when they come into proximity with another ZigBee-enabled device or WiFi hotspot. This feature eliminates the need for users to configure their devices individually. ZigBee uses small data packets that are sent between nodes during synchronous events, such as connecting to a new device or changing channels. These two actions require the transmission of short messages called beacons. Asynchronous events, such as reading sensor data, do not require beacon transmissions. A node that has received a beacon message will send an acknowledgement back to confirm that it has received the data. If an acknowledgment is not received within a certain time limit, the packet will be dropped and repeated attempts will be made to transmit it.
Zigbee devices can send data over great distances by routing it through a mesh network of intermediary devices to reach further distant devices. Zigbee is commonly used in low data rate applications requiring extended battery life and secure networking. (Zigbee networks are protected by symmetric encryption keys of 128 bits.)
Zigbee devices synchronize their actions with each other so that only one can speak at a time. This is called "slotted synchronization". During this time, all other devices must be listening.
When a device wants to transmit data, it sends out a message called a "probe". The only device that will respond to this probe is the one that is closest to the sender. If more than one device responds, then they all talk at once and no single message gets through.
The first device to receive the probe replies back to the sender containing its ID number. This ID number is used by the sender to determine which direction to route the message in order to get it to its destination.
Since all Zigbee devices synchronize their transmissions, only one can talk at a time across all channels. When their time comes, other devices can start transmitting again.
This process continues until the message reaches its destination where it is received by another device which repeats these steps in reverse to return the message to the first device that sent it out.