operate at 20Mbps or more). Task Group 4 (802.15.4: WPAN Low Rate)-This group is focused on low-data-rate WPANs with very long battery life (months or years). The 802.15.4 standard, known as ZigBee, was produced by this group. The first edition of the standard was released in 2003. The 802.15.4 task group is now in hibernation. The 802.15.4a standard aims to provide a PHY-layer wireless communication protocol with ranging capabilities for low-power applications such as sensor networks. A new task group, 802.15.4b, is also working on enhancing the original standard. The following sections cover these task groups and the main WPAN standards in use today: IEEE 802.15.1 (Bluetooth) IEEE 802.15.3 (WPAN-HR and WPAN-AHR) Ultra-Wideband (UWB) IEEE 802.15.4 (ZigBee) Radio frequency identification (RFID) Near Field Communication (NFC) IEEE 802.15.1 (Bluetooth) IEEE 802.15.1, known as Bluetooth, is an industry specification for short-range RF-based connectivity for portable personal devices. This specification was origi- nally developed by Ericsson (www.ericsson.com) and was ultimately formalized by the Bluetooth SIG (www.bluetooth.org), which includes more than 3,000 mem- bers, including Sony, Ericsson, IBM, Intel, Toshiba, and Nokia. The IEEE licensed wireless technology from the Bluetooth SIG to adapt and copy a portion of the Bluetooth specification as base material for IEEE 802.15.1-2002. approved IEEE 802.15.1 standard, which defines the lower transport layers of the Bluetooth wireless technology, is fully compatible with the Bluetooth vl.1 specifi- cation. Bluetooth technology defines specifications for small-form-factor, low-cost wireless radio communications among notebook computers, PDAs, mobile phones, and other portable, handheld devices and for connectivity to the Internet. The primary focus of Bluetooth technology is to provide a standard designed for low power consumption, operating over a short range, and including a low-cost transceiver microchip in each device. Bluetooth devices can talk to each other Chap