Wireless Personal Area Network (WPAN) are most commonly created using Bluetooth Bluetooth is used by mobile devices to communicate directly without the use of an intermediate device like a Wireless Access Point (WAP) or wireless router.
Wikipedia
A personal area network (PAN) is a computer network for interconnecting electronic devices within an individual person's workspace. A PAN provides data transmission among devices such as computers, smartphones, tablets and personal digital assistants. PANs can be used for communication among the personal devices themselves, or for connecting to a higher level network and the Internet where one master device takes up the role as gateway.
A PAN may be wireless or carried over wired interfaces such as USB. A wireless personal area network (WPAN) is a PAN carried over a low-powered, short-distance wireless network technology such as IrDA, Wireless USB, Bluetooth or Zigbee. The reach of a WPAN varies from a few centimeters to a few meters. WPANs specifically tailored for low-power operation of the sensors are sometimes also called low-power personal area network (LPPAN) to better distinguish them from low-power wide-area network (LPWAN).