What is Zigbee Technology?

ZigBee is all about a wireless protocol. It is an IEEE 802.15.4-based specification for a suite of high-level communication protocols using in to create Personal Area Networks(PANs) with small, low-power digital radios. Such as for home automation, medical device data collection, and other low-power low-bandwidth needs. It is designed for small scale projects which need wireless connection. Hence, Zigbee is a low-power, low data rate, and close proximity (i.e., personal area) wireless ad hoc networks.

The technology defines the Zigbee specification is intending to be simpler and less expensive than other Wireless Personal Area Networks (WPANs), such as Bluetooth or more general wireless networking such as Wi-Fi. Applications include wireless light switches, home energy monitors, traffic management systems, and other consumers. Industrial equipment that requires short-range low-rate wireless data transfer are also included in WPAN.

Moreover, its low power consumption limits transmission distances to 10–100 meters line-of-sight, depending on power output and environmental characteristics. Thus, can transmit data over long distances by passing data through a mesh network of intermediate devices to reach more distant ones. But it is typically using in low data rate applications that require long battery life and secure networking. On the other hand, Zigbee networks are secure by 128-bit symmetric encryption keys. It has a defined rate of 250 kbit/s, best suited for intermittent data transmissions from a sensor or input device.

System Structure of ZigBee

These are of three kinds:-

• ZigBee coordinator (ZC): The most capable device. The coordinator forms the root of the network tree and might bridge to other networks. There is precisely one ZigBee coordinator in each network since it is the device that started the network originally. The ZigBee LightLink specification also allows operation without a ZigBee coordinator. It Makes it more usable for off-the-shelf home products. It stores information about the network, including acting as the trust centre and repository for security keys.
• ZigBee Router (ZR): In running an application function. But, A router can act as an intermediate router, passing data on from other devices.
• ZigBee end device (ZED): It contains just enough functionality to talk to the parent node either the coordinator or a router. Thus, It cannot relay data from other devices. This relationship allows the node to be asleep a significant amount of the time and giving a long battery life. A ZED requires the least amount of memory. Thus can be less expensive to manufacture than a ZR or ZC.

ZigBee Architecture

The software designing is to be easy to develop on small, inexpensive microprocessors. ZigBee protocol architecture consists of a stack of various layers where IEEE 802.15.4 is defined by physical and MAC layers while this protocol is completed by accumulating Zigbee’s own network and application layers.

Physical Layer: This layer does modulation and demodulation operations upon transmitting and receiving signals respectively.  So, It transmits information and receives information from a source

MAC Layer: This layer is responsible for reliable transmission of data by accessing different networks with the carrier sense multiple access collision avoidance (CSMA). This also transmits the prominent position as a warning frame for synchronizing communication.

Network Layer: The main functions of the network layer are to enable the correct use of the MAC sublayer and provide a suitable interface for use by the next upper layer, namely the application layer. So, Its capabilities and structure are those typically associated with such network layers, including routing. The Network Layer’s function is exactly as it sounds. It deals with network functions such as connecting, disconnecting, and setting up networks. Thus, It will add a network, allocate addresses, and add/remove certain devices. This layer makes use of star, mesh and tree topologies. It adds an interface to the application layer.

Application layer: The application layer is the highest-level layer defined by the specification and is the effective interface of the ZigBee system to its end users. It comprises the majority of components added by the ZigBee specification: both ZDO and its management procedures, together with application objects defined by the manufacturer, are considered part of this layer. This layer is responsible for, sending messages between bound devices, managing group addresses, reassembling packets and also transporting data. So, It is responsible for providing service to Zigbee device profiles.

ZigBee Operating Modes

Zigbee two way data is transferred in two modes:

• Beacon Mode: In the beacon mode, a device watches out for the coordinator’s beacon that gets transmitted at periodically, locks on and looks for messages addressed to it. If message transmission is complete, the coordinator dictates a schedule for the next beacon so that the device ‘goes to sleep’; in fact, the coordinator itself switches to sleep mode. While using the beacon mode, all the devices in a mesh network know when to communicate with each other. In this mode, necessarily, the timing circuits have to be quite accurate or wake up sooner to be sure not to miss the beacon. This, in turn, means an increase in power consumption by the coordinator’s receiver, entailing an optimal increase in costs.

• Non-Beacon Mode: The non-beacon mode will be included in a system where devices are ‘asleep’ nearly always, as in smoke detectors and burglar alarms. So, The devices wake up and confirm their continued presence in the network at random intervals. On detection of activity, the sensors ‘spring to attention’, as it were, and transmit to the ever-waiting coordinator’s receiver since it is mains-powered. However, there is the remotest of chances that a sensor finds the channel busy, in which case the receiver, unfortunately, would ‘miss a call’.

ZigBee Topology

Network topology is the design of the elements such as links or nodes of a communication network. It is used to illustrate various types of telecommunication networks. We already talked briefly about one of the three Zigbee network topology in the previous post. Now let dive in a little deeper about all three Zigbee network topology.

Zigbee network topology is of three types:

1.star topology

2. tree topology

3.peer-to-peer or mesh topology.

Each topology will have a different effect on how the messages are routed and which devices connect to which devices.

1. Star Topology:

The first topology is the star topology. So, Star topology consists of a coordinator and a few end devices. It is the simplest and most limited one in the Zigbee. Devices are all connected to single coordinator node and all communication goes via this coordinator. Thus, The interesting part about the star topology is it actually define by the underlying 802.15.4 specification which Zigbee builds on. But, The disadvantage of this topology is it may become a hindrance and there is no option path from the source to the end devices.

2. Tree Topology:

The second topology is tree topology. It consists of a coordinator, few routers and end devices that act as a central node or root tree. The routers operate as an extension for the network coverage. The end nodes connecting to the parent (coordinators or routers) are known as children. Only the end devices can communicate with the parent. The detriment of the tree topology is if one parent is disabled, the children of the disabled parent cannot communicate with other devices in the network even they are close to each other.

3. Mesh Topology:

The third and last topology is peer-to-peer or mesh topology. So, This topology consists of a coordinator, a few routers and end devices. You can expand the network range by adding more devices into the network. If during the transmission one of the paths fails, the node will find the alternate path to reach to the destination, therefore, eliminating dead zones. Using this mesh topology it is easier for a user to add or remove the device because they can communicate with any destination device in the network.

IoT Applications Using ZigBee

The applications of this technology includes:

1. Collection of Medical Data:

This technology is used in-home patient monitoring where the collection of medical data is crucial. In this system, a patient wears a Zigbee device which collects the information like the pulse rate, the temperature of the body, blood pressure etc.

2. Smart Industrial Automation:

In manufacturing and production industries, a communication link continually monitors various parameters and critical equipment. Hence Zigbee considerably reduce this communication cost as well as optimizes the control process for greater reliability.

3. Smart Smoke Alarms:

This smart smoke alarm is for sensing fire smoke and issue acoustic-optic alarm signals to alert people locally and send alarm notifications to user App remotely. So, This smoke alarm, adopts advanced sensor, technology and craftworks, has stylish outlook, high stability and super low power consumption.

4. Smart Home Automation:

Nowadays tech conglomerates are betting big on home automation services with their offering like Google Home, Amazon Alexa etc. Zigbee wireless technology is perfectly suitable for controlling home appliances remotely as a surveillance system, lighting control system, appliance control system, safety systems, and so on.

5. Smart Metering System:

Utility meters need to read on a regular basis to generate utility bills. One way to do so is to read the meters manually at homeowners’ premises and enter the values into a database. A ZigBee-based automatic meter reading (AMR) system can create self-forming wireless mesh networks across residential complexes that link meters with utilities’ corporate offices. On the other hand, AMR provides the opportunity to remotely monitor a residence’s electric, gas, and water usage and eliminate the need for a human visiting each residential unit on a monthly basis.

6. Smart Grid Monitoring:

It is prevailing rapidly in electrical engineering research and it is expecting to provide sustainable and efficient energy services with advanced control and communications infrastructure in a smart grid environment. A smart grid involves all the stakeholders of power systems, from generation to consumption, with the bi-directional flow of power and information. Thus, Communications technologies are a vital part of the smart grid and enable the utility to manage tasks like energy management in Home Area Networks (HANs), Neighbor Area Network (NANs), and Wide Area Network (WANs), etc.

Advantages and Disadvantages of ZigBee

Advantages:

• Zigbee has a flexible network structure
• It has very long battery life
• Zigbee has a mesh network topology with low cost, multi hope data transmission and is power effective
• It is less complex than Bluetooth
• It is easy to install
• Zigbee support a large number of nodes 
• Zigbee is more reliable 
• It is a short working period result in power saving and power consumption of communication

Disadvantages:

• Zigbee disadvantages mainly include short-range
• Low complexity, and low data speed
• Its high maintenance cost, lack of total solution, and slow materialization,
• Low transmission, as well as low network stability, are also some of its disadvantages that takes it a step back as compared to others
• Replacement with Zigbee compliant appliances can be costly 
• Zigbee is not secure like WiFi-base secure system
• It does not have end devices available yet