Question

Give 2 page summary on ZigBee and show diagrams to illustrate interaction of devices within constructed network.

Answer 1

1. ZigBee Overview The ZigBee protocol was developed to provide low-power, wireless connectivity for a wide range of network applications concerned with monitoring and control. ZigBee is a worldwide open standard controlled by the ZigBee Alliance. ZigBee PRO was then developed as an enhancement of the original ZigBee protocol, providing a number of extra features that are particularly useful for very large networks (that may include hundreds or even thousands of nodes). ZigBee Features The ZigBee standard builds on the established IEEE 802.15.4 standard for packetbased wireless transport. ZigBee enhances the functionality of IEEE 802.15.4 by providing flexible, extendable network topologies with integrated set-up and routing intelligence to facilitate easy installation and high resilience to failure. ZigBee networks also incorporate listen-before-talk and rigorous security measures that enable them to co-exist with other wireless technologies (such as Bluetooth and Wi-Fi) in the same operating environment. ZigBee's wireless connectivity means that it can be installed easily and cheaply, and its built-in intelligence and flexibility allow networks to be easily adapted to changing needs by adding, removing or moving network nodes. The protocol is designed such that nodes can appear in and disappear from the network, allowing some devices to be put into a power-saving mode when not active. This means that many devices in a ZigBee network can be battery-powered, making them self-contained and, again, reducing installation costs. Figure 1 shows a simple example of a ZigBee network in a HVAC (Heating, Ventilation and Air-Conditioning) system. ZigBee 3.0 ZigBee 3.0 employs the ZigBee PRO protocol and is designed to facilitate general wireless networks that are not market-specific. Thus, devices from different market sectors can belong to the same wireless network - for example, lighting and healthcare devices in a hospital may share a single ZigBee network, allowing data to be routed through any intermediate (routing) device, irrespective of the device functionality. Connecting the network to the Internet brings the devices into the ‘Internet of Things’ (IoT), allowing the network devices to be controlled and monitored from IP-based devices such as computers, tablets and smartphones.

ZigBee Network Nodes A wireless network comprises a set of nodes that can communicate with each other by means of radio transmissions, according to a set of routing rules (for passing messages between nodes). A ZigBee wireless network includes three types of node:  Co-ordinator: This is the first node to be started and is responsible for forming the network by allowing other nodes to join the network through it. Once the network is established, the Co-ordinator has a routing role (is able to relay messages from one node to another) and is also able to send/receive data. Every network must have one and only one Co-ordinator.  Router: This is a node with a routing capability, and is also able to send/receive data. It also allows other nodes to join the network through it, so plays a role in extending the network. A network may have many Routers.  End Device: This is a node which is only capable of sending and receiving data (it has no routing capability). A network may have many End Devices.

ZigBee is suitable for a wide range of applications, covering both commercial and domestic use, which include:  Point-to-point cable replacement (e.g. wireless mouse, remote controls, toys)  Security systems (e.g. fire and intruder)  Environmental control (e.g. heating and air-conditioning)  Hospital patient monitoring  Lighting control  Home automation (e.g. home entertainment, doors, gates, curtains and blinds)  Automated meter reading (AMR)  Industrial automation (e.g. plant monitoring and control) ZigBee's wireless communications also enable some applications to be developed that currently cannot be implemented with cabled systems. Examples are applications that involve mobility, which must be free of cabling (e.g. long-term health monitoring, asset tracking in warehouses). Existing applications (such as lighting control and industrial plant monitoring) that currently rely on cable-based systems can be implemented more cheaply as ZigBee reduces or removes cable installation costs. ZigBee can also be beneficial in environments where cable-based solutions can be difficult and expensive to install - for example, in home security systems, sensors need to be easy to install (no cables or power supply wiring), small and self-contained (battery-powered).

Diagram to illustrate interaction of devices within constructed network.