easing diversity of personal devices get disconnected, broken, lost and generally get in the way of personal productivity. Getting rid of them has been the major motivation behind the efforts of the numerous working groups and other organisations involved since the late 1990s in developing standards for personal area networks. Within the IEEE, the 802.15 Working Group was established in March 1999 with the objective of providing standards to support the interoperability of low complexity, low power devices that can be worn, carried or located in a personal operating space (POS), defined as extending 10 metres in all directions around a stationary or moving person. An overview of the wireless PAN standards developed by the 802.15 Working Group is shown in Table 10-1. The kind of devices that were envisaged as participating in the PAN were the already ubiquitous mobile phone and then increasingly common personal stereo, pager and PDA. Considering that someone carrying a watch, mobile phone, pager, personal stereo and PDA would be equipped with two input keypads, four speakers, two microphones and potentially five LCD displays, the potential for simplification through interoperability is self-evident. A variety of different PAN standards have been developed since the late 1990s, most notably Bluetooth and IrDA, and more recently ZigBee and Wireless USB have come on the scene. Each of these technologies has its Chapter Ten Table 10-1: Overview of IEEE 802.15 WPAN Standards and Task Groups Standard Description Application 802.15.1 Original 2.4 GHz FHSS specification. Published in 2002. Bluetooth 802.15.2 Recommended practices to facilitate coexistence of 802.15 wireless PANs and 802.11 wireless LANs. Published 2003. 802.15.3a High rate WPAN. UWB PHY with DS-UWB VS OFDM under discussion. Draft published in 2003. Overtaken by MBOA and Wireless USB. Working Group disbanded in January 2006. 802.15.3b MAC amendment Task Group, improving implementation and interoperability of the 802.15 MAC. 802.15.3c Millimetre-wave altern