Technologies - WLAN

Wireless Local Area Network, or mostly referred to as WLAN, was standardized by IEEE for the first time in 1997 as IEEE 802.11 as a seamless link into the existing wired 802.3 networks (Ethernet). WLAN provides a good transmit/receive range of up to 100m. The WLAN specification is data communication orientated, there are no synchronous channels (as you would normally expect to have for Audio/Video applications). As for the wired counterpart, there are only the two bottom layers according to the specified ISO/OSI reference model (Physical Layer, Medium Access Layer), but the next layers up (Network Layer, Transport Layer) are inherently covered by TCP/IP.

Over the years, the original 802.11 standard was enhanced by several substandards, the most important ones are in the order of appearance:

• 802.11 (2Mbps, 2.4GHz ISM, DSSS)
• 802.11b (11 Mbps, 2.4 GHz ISM, DSSS)
• 802.11a (54 Mbps, 5 GHz ISM, OFDM)
• not compatible to 802.11b, lower range)
• 802.11g (54 Mbps, 2.4 GHz ISM, DSSS, OFDM)
• compatible to 802.11b
• 802.11i enhanced security and authentication features
• 802.11n enhanced data rate up to 600 Mbps (planned for 2006)

DSSS: Direct Spread Spectrum Sequence modulation
OFDM: Orthogonal Frequency Division Multiplex modulation

WLAN technology has a 99% usage of accessing or replacing existing wired Ethernet solutions. It reaches very good data rates at a fair range, but the power consumption is quite high (typically 250mA) and thus WLAN is not a good candidate for battery powered solutions. In terms of security, WLAN had some weak points in the original implementations (WEP encryption has been cracked), but there are safer alternatives (802.11i, WPA, AES) today.

There are very mature products in the market at reasonable prices, and the trend is for these to reduce further. WLAN has spread through the PC and consumer market, and the market penetration is still growing.

Public WLAN hot spots, WLAN enabled PDAs and notebooks or surfing the Internet via WLAN equipment at home have contributed a lot to the propagation of WLAN technology in the last few years. However, there are not so many WLAN products available in the embedded market, even if its marketshare is also growing rapidly.

To learn more about Smart Network Devices WLAN solution please download WLAN Extension.pdf