• Wednesday 19 November 2008 - 12:53:32
• registered : 1066177
• online : 55422
• questions/day : 4959
• Answer rate : 75.35%

Wireless Personal Area Networks (WPAN)

A wireless personal area network (WPAN for short) is a low-range wireless network which covers an area of only a few dozen metres. This sort of network is generally used for linking peripheral devices (like printers, cellphones, and home appliances) or a personal assistant (PDA) to a computer, or just two nearby computers, without using a hard-wired connection. There are several kinds of technology used for WPANs:

The main WPAN technology is Bluetooth, launched by Ericsson in 1994, which offers a maximum throughput of 1 Mbps over a maximum range of about thirty metres. Bluetooth, also known as IEEE 802.15.1, has the advantage of being very energy-efficient, which makes it particularly well-suited to use in small devices.

HomeRF (for Home Radio Frequency), launched in 1998 by HomeRF Working Group (which includes the manufacturers Compaq, HP, Intel, Siemens, Motorola and Microsoft, among others) has a maximum throughput of 10 Mbps with a range of about 50 to 100 metres without an amplifier. The HomeRF standard, despite Intel's support, was abandoned in January 2003, largely because processor manufacturers had started to support on-board Wi-Fi (via Centrino technology, which included a microprocessor and a Wi-Fi adapter on a single component).

The technology ZigBee (also known as IEEE 802.15.4) can be used to connect devices wirelessly at a very low cost and with little energy consumption, which makes it particularly well-suited for being directly integrated into small electronic appliances (like home appliances, stereos, and toys). Zigbee, which operates on the frequency band of 2.4 GHz and on 16 channels, can reach transfer speeds of up to 250 Kbps with a maximum range of about 100 metres.

Finally, infrared connections can be used to create wireless connections over a few metres, with speeds than can reach a few megabits per second. This technology is widely used in home electronics (like remote controls), but light waves can interfere with the signal. irDA (Infrared Data Association), formed in 1995, has more than 150 members.