ative PHY. 57-64 GHz unlicensed band. 1 Gbps data rate and optionally to 2 Gbps. Formed in March 2005. 802.15.4 Low rate WPAN. DSSS 2.4 GHz, 915 and 868 ZigBee MHz. Published in 2003. 802.15.4a Task Group chartered to develop an alternative PHY layer. Two optional PHY specifications under consideration - a UWB impulse radio and a Chirp Spread Spectrum operating in the 2.4 unit space GHz ISM band. 802.15.4b Task Group chartered to address enhancements and clarifications to the 802.15.4 standard. 802.15.5 Developing MAC and PHY mechanisms required to enable mesh networking in wireless PANs. own particular strengths and weaknesses in the way it addresses the challenge of delivering easy to use. In this chapter the characteristics of each of these technologies will be described, from both a technical and a practical standpoint. Bluetooth (IEEE 802.15.1) Origins and Main Characteristics Research on the use of radio to link mobile phones and accessories was started by Ericsson Mobile Communications in 1994, but it was not until Wireless PAN Standards the Bluetooth Special Interest Group (SIG) was launched four years later, by Ericsson, IBM, Intel, Nokia and Toshiba, that the concept started to broaden beyond mobile phones to include connections between PCs and other devices. After the IEEE 802.15 Working Group was formed in 1999 with the task of developing standards for wireless PANs, the Bluetooth SIG was the only respondent to WG15's Call for Responses, and Bluetooth and IEEE 802.15.1 soon became synonymous. Since 2000, when Bluetooth-enabled wireless headsets started to emerge, cost and power usage have reduced significantly, and Bluetooth has become a common add-on feature for many mobile phones and PDAs. Bluetooth 1.1 is a PAN standard that operates in the 2.4 GHz ISM band at a PHY layer data rate of 1 Mbps, for an effective data rate of 721/56 kbps for asymmetric or 432 kbps for full duplex communication. Bluetooth 2.0 was ratified in November 2004, and enhanced data rate (EDR) was introduced which increased the 