Wireless Hacks, 2nd Edition

Appendix A. Wireless Standards

The mad rush to bring wireless products to market has left a slew of similar sounding yet often completely incompatible technologies and standards in its wake. 802.11b is the sequel to 802.11a, right? (Wrong.) If I just buy Wi-Fi, then everything will work together, right? (Unfortunately, no.) What is the difference between 802.11 a/b/g, 802.16, and 802.1x? How about GSM, GPRS, GMRS, and GPS? Where does Bluetooth fit into the picture?

802.11: The Mother of All IEEE Wireless Ethernet

The first wireless standard to be defined in the 802 wireless family was 802.11. It was approved by the IEEE in 1997, and defines three possible physical layers: Frequency Hopping Spread Spectrum (FHSS) at 2.4 GHz, Direct Sequence Spread Spectrum (DSSS) at 2.4 GHz, and Infrared. 802.11 could achieve data rates of 1 or 2 Mbps. 802.11 radios that use DSSS are interoperable with 802.11b and 802.11g radios at those speeds, while FHSS radios and Infrared obviously are not.

The original 802.11 devices are increasingly hard to come by, but can still be useful for point-to-point links with low bandwidth requirements.

Pros

• Very inexpensive (a few dollars or even free) when you can find them.

• DSSS cards are compatible with 802.11b/g.

• Infrared 802.11 cards (while rare) can offer interference-free wireless connections, particularly in noisy RF environments.

• Infrared also offers increased security due to significantly shorter range.

Cons

• No longer manufactured.

• Low data rate of 1 or 2 Mbps.

• FHSS ...