Personal area network

A personal area network (PAN) is a specialized type of computer network, which benefits from extremely short range. Among its applications is replacing the cables between a computer and its peripherals, so minimal range is desired to avoid interference with other nearby computers.

Literally personal

The first application proposed, however, was linking computing elements on (or in) different parts of a human body.

In the context of a single-person network, as with wearable computers,

The trick is to allow "wearable" electronic devices to exchange data by capacitively coupling modulated picoamperes currents through the body. A low frequency carrier (below 1 MHz) is used so very little energy is radiated outside the body itself, minimizing interference and remote eavesdropping. A PAN device electrostatically induces picamp currents into the body which is used as a "wet wire" to conduct the modulated currents."

Wireless PANs

Bluetooth is one de facto standard for PANs, but IEEE created the 802.15 group to address the perceived limitations of that and other wireless technologies:

• "balancing cost with range and bandwidth
• "offering coexistence with other wireless devices
• "providing security in roaming environments."

802.15

PANs, as defined by 802.15, have a range of 33 feet, which may be excessive in some applications. Their roaming concerns may address this. An 802.15 PAN uses a time-slot technology to support up to 254 devices, of which one is the timing beacon for the self-organizing network.

The 802.15 group is addressing two classes of requirements, using 2.4 GHz transmission

• 802.15.3 focuses on high-bandwidth (about 55M bit/sec), low-power MAC and physical layer
• 802.15.4 deals with low-bandwidth (about 250K bit/sec), extra-low power MAC and physical layers