Theory

Personal Area Network

A personal area network or PAN is a computer network connecting different types of devices like mobile phones, small portable devices and computers. It is mainly standardized by IEEE 802.15 working group and certain bodies working on particular technological solutions. The typical range of the personal area network is 10 metres.

ZigBee

Zigbee is an adaptation of the IEEE 80.15 low-data rate WPAN standard. The technology came about as an alternative to Bluetooth and WiFi networking. Unlike Bluetooth and Wifi, Zigbee requires low data rate (from 250 kbps at 2.4 GHZ to 20 kbps at 868 Mhz). Zigbee uses low energy consumption. In addition, these devices are low cost.

ZigBee alliance defined two types of physical devices by in roder to lower the costs. Full Function Device (FFD) allows bilding any topology. It can take a role of a network coordinator and is able to communicate with any other ZigBee device. In a network it takes a similar role toa master unit in Bluetooth, however the physical design is different to the other type of device (in Bluetooth the devices are in general the same any anyone can take the role of a network coordinator). Reduced function device (RFD) can be used only in a star topology and only as a distant unit. It is controlled be an (FFD) and can communicate only with it after. The implementation of an RFD is strongly simplified comparing to FFD, which significantly lower the cost of the whole system.

Zigbee Network Formations

Zigbee defines three difference device types: coordinator, router and end device.

Coordinator: Start a new personal area network (PAN) by selecting the channel and PAN ID. Allow routers and end devices to join the PAN, transmit and receive RF data transmission and route the data through the mesh network.

Router: Transmit and receive RF data transmission, and route data packet through the network

End Device - Cannot assist in routing the data transmission but transmit or receive RF data transmission and intended to be battery powered devices.

Communication with XBee modules is done either via Arduino or via a USB dongle which is connected to a computer. The XBee module interfaces to a host device through a logic-level asynchroous serial port.

1 Burkhard Stiller, Thomas Bocek, Fabio Hecht, Peter Racz, Martin Waldburger, ‘Mobile Systems IV’, ttp:// [|www.ifi.uzh.ch/pax/uploads/pdf/publication/1290/ifi-techreport20100001.pdf] accessed 17th October, 2010. 2 Ibid, 30. 3 Mayalard, Vachirapol et. al, Wirelss Mesh Networking with XBee, [], accessed 18th October, 2010, 1–2. 4 //Ibid//, 2.