ield communications over a distance of a few centimetres for keyless entry to office, to wireless headset for a mobile phone over a distance of a metre, to communicating with a fixed satellite for remote internet access. One way to classify these different wireless telecommunications systems is based on the distance between the transmitter and receiver. Alternatively, the required rate of transmission and the required transmission power may be considered. The Wireless World Research Forum classifies terrestrial public wireless telecommunica- tions systems based on the service needs of an end-user. Table 12.1 illustrates a model based on this classification, with an individual body and personal, immediate and wide area connectivity applications. Personal and body area network (PAN and BAN) address appli- cations include networked glasses, watches, medical monitoring and fitness sensors. A number of such devices exist in the market, for example Google Glass and Samsung Galaxy S5 Gear. These devices wirelessly connect to a central device over a typical distance in the order of a few metres. The next level is the local area, where connection is to net- worked appliances (e.g. TV, fridge, PC, printer). Wireless LAN devices are the most com- monly used devices in this category. Connectivity is also required over wide areas as one needs to connect to other people and sources of information, and smart phones are a prominent example. A number of technologies have been developed to support these networking applications. Each category may emphasise a parameter of interest, such as transmission rate, power and range depending on the application. As noted above, personal (and body) area networking is for applications within a range of a few metres. Two IEEE standards have emerged to address this market: one is the 802.15.1 series, better known as Bluetooth. Bluetooth applications are for short range connectivity at speeds of one to a few megabits per second (Mbps) and transmission power of up to 100 mW. The other is 802.15.4,