ions involving wearables, all of which require PANs to realize their key benefits. As with many of the other technologies discussed SO far in this book, there are a variety of PAN standards, some of which are from the IEEE, and some of which are more recent and specifically geared toward m2m communications and sensor- based networks. The IEEE 802.15 WPAN Working Group effort focuses on the development of consensus standards for WPANs. These standards address wireless networking of portable and mobile computing devices-such as PCs, PDAs, peripherals, mobile phones, pagers, and consumer electronics-allowing these devices to communi- cate and interoperate with one another. One of the main goals of the working group is to publish standards, recommended practices, and guidelines that have broad market applicability and deal effectively with the issues of coexistence and interoperability with other wired and wireless networking solutions. Four major 802.15 task groups are addressing WPAN standards: Task Group 1 (802.15.1: WPAN/Bluetooth)-This - group deals with Blue- tooth. It produced the 802.15.1 standard, published in 2002, which includes MAC- and PHY-layer specifications derived from the Bluetooth vl.1 founda- tion specifications published by the Bluetooth Special Interest Group (Bluetooth SIG; www.bluetooth.org) Task Group 2 (802.15.2: WPAN Coexistence)-This group developed recommended practices to facilitate coexistence of WPANs (802.15) and WLANs (802.11). It developed a coexistence model to quantify the mutual interference of a WLAN and a WPAN. The task group also devel- oped a set of coexistence mechanisms to facilitate coexistence of WLAN and WPAN devices. This task group is now in hibernation until further notice. Task Group 3 (802.15.3: WPAN High Rate and WPAN Alternate High Rate)-This group currently has two subgroups: 802.15.3 is referred to as WPAN High Rate (WPAN-HR), and 802.15.3a is referred to as WPAN WPANs Alternate High Rate (WPAN-AHR). Both of them deal with high-data-rate WPANs (i.e., WPANs that 