Zigbee

 Zigbee is a standards-based wireless technology developed to enable low-cost, low-power wireless machine-to-machine (M2M) and internet of things (IoT) networks.

Zigbee is for low-data rate, low-power applications and is an open standard. This, theoretically, enables the mixing of implementations from different manufacturers, but in practice, Zigbee products have been extended and customized by vendors and, thus, plagued by interoperability issues. In contrast to Wi-Fi networks used to connect endpoints to high-speed networks, Zigbee supports much lower data rates and uses a mesh networking protocol to avoid hub devices and create a self-healing architecture.

The 802.15.4 specification upon which the Zigbee stack operates gained ratification by the Institute of Electrical and Electronics Engineers (IEEE) in 2003. The specification is a packet-based radio protocol intended for low-cost, battery-operated devices. The protocol allows devices to communicate in a variety of network topologies and can have battery life lasting several years.

Zigbee 3.0 Protocol:-

The Zigbee protocol has been created and ratified by member companies of the Zigbee Alliance. Over 300 leading semiconductor manufacturers, technology firms, OEMs and service companies comprise the Zigbee Alliance membership. The Zigbee protocol was designed to provide an easy-to-use wireless data solution characterized by secure, reliable wireless network architectures.

The standards created by the alliance can be used to create multivendor interoperable offerings. Manufacturers that are developing custom applications that don't need to operate with the applications of other manufacturers can create their own specific variations and extensions. There are three Zigbee specifications: Zigbee PRO, Zigbee RF4CE and Zigbee IP.

Mesh networking

A key piece of the Zigbee protocol is its ability to support mesh networking. Zigbee uses a mesh network architecture for communication.

A mesh network is a local area network (LAN), wireless LAN (WLAN) or virtual LAN (VLAN) that employs one of two decentralized connection arrangements: full mesh topology or partial mesh topology. The Zigbee protocol defines three types of nodes: coordinators, routers and end devices. Although all nodes can send and receive data, they each play a different role.

There is one coordinator in each network whose job is to store information about the network, including security keys. Routers are intermediate nodes, relaying data from other devices. End devices can be low-power or battery-powered devices, which can talk to the coordinator or a router, but can't relay data from other devices.

#Architecture:-

1. Layered architecture

• Network and Application support layer
• Physical (PHY) layer
• Media access control (MAC) layer

2. These layers facilitate the features that make ZigBee very attractive:

• low cost
• easy implementation
• reliable data-transfer
• short range operations
• very low power consumption
• adequate security features

#Zigbee Devices:-

• There are three different Zigbee device type that operates on the layers inn any self organizing application network.

1.Zigbee Coordinator Node:-

• root of the network tree and a bridge to other network
• able to store information about the network
•  only one ZCN for a network
• it acts as a repository for other security keys

2.The Full Function Device:-

• an intermediatory  router transmitting data from other devices
• needs lesser memory than Zigbee coordinator node
• less manufacturing cost
• can operate on all topologies
• also act as a coordinator

3.The Reduced Function Device:-

• device capable of talking in network
• it cannot relay data from other devices
• less memory
• cheaper than FFD
• it talks only to new coordinator

Topologies Involved....Star Topology, Peer-to-Peer Topology, Mesh Topology, Cluster Network

THE ZIGBEE ADVANTAGE

The Zigbee 3.0 protocol is designed to interact with data through noisy Radio Frequency environments that are common in commercial and industrial areas. 

Version 3.0 builds on the existing Zigbee standard but unifies the market-specific application profiles to allow all devices to be wirelessly connected in the same network, irrespective of their market designation and function.

Zigbee protocol features include:

• Support for multiple network topologies such as point-to-point,
  point-to-multipoint and mesh networks
• Low duty cycle – provides long battery life
• Low latency
• Direct Sequence Spread Spectrum (DSSS)
• Up to 65,000 nodes per network
• 128-bit AES encryption for secure data connections
• Collision avoidance, retries and acknowledgements

#CHARACTERISTICS & APPLICATIONS:-

1. low power consumption with battery life ranging from months to years
2. high density of nodes per network
3. low cost
4. simple implementation
5. low data rate
6. small packet devices

1. the Zigbee alliance targets applications across consumer, commercial, industrial and government markets worldwide 
2. home networking
3. industrial control and management

CONCLUSION - ZIGBEE COMMUNICATIONS TECHNOLOGY COULD FORM THE BASIS OF FUTURE WRELESS SENSORS, OFFERING DATA RELIABILITY, LONG BATTERY LIFE, LOW SYSTEM COSTS, AND GOOD RANGE THROUGH FLEXIBLE NETWORKING.

"It's still magic even if you know how it's done.."

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HAPPY reading.......