Wireless LAN Standards
2005.02.14 13:02 by Philip
Keywords: WLAN, Wireless, Wi-Fi, Standard, IEEE, Frequency, WEP, WPA, WPA2, MIMO, Bluetooth, HomeRF, SSL, VPN, LAN
Different wireless technologies define a rapidly emerging area of growth in networking. The need for mobile computing, wireless peripherals, voice and messaging, hand-held and other internet-enabled devices, easy home networking, media streaming, and cost-effective networking solutions in general have driven the recent development of a number of wireless networking standards.
All those wireless technologies target different niches in the WLAN market, work over different frequencies, and only a few are compatible with each other.
The quick WLAN reference table below will help differentiate between the different wireless networking standards in use today.
|IEEE Standard ||Speed (max) ||Frequency ||Transmission Method ||Security ||Details|
|802.11 legacy ||2 Mbps ||2.4 GHz ||DSSS, FHSS ||WEP, WPA ||IEEE specification extended into 802.11b|
|802.11a ||54 Mbps ||5.0 GHz ||OFDM ||WEP, WPA ||Wi-Fi Alliance standard, 12 non-overlapping channels (each 20 MHz wide). Less potential for RF interference at 5 GHz than 2.4 GHz. Shorter range than, and not interoperable with 802.11b/g. Average actual throughput 10-25 Mbps.|
|11 Mbps ||2.4 GHz ||DSSS, HR-DSSS ||WEP, WPA ||Wi-Fi Alliance standard. 11 channels (each 22 MHz wide, only 3 non-overlapping, 14 usable channels outside the U.S.). Average actual throughput 5 Mbps.|
|802.11g ||54 Mbps ||2.4 GHz ||DSSS, HR-DSSS, OFDM ||WEP, WPA ||Wi-Fi Alliance standard, 11 channels (each 22 MHz wide, only 3 non-overlapping, 14 usable channels outside the U.S.). Compatible with 802.11b, with improved speed and security. Will eventually replace 802.11b. Uses additional OFDM modulation technique above 20 Mbps. Average actual throughput 10-25 Mbps.|
|802.11n ||200+ Mbps ||2.4/5 GHz ||MIMO ||WPA2 ??? ||Emerging Wi-Fi Alliance standard (scheduled to be complete by the end of 2006), backward compatible with 802.11a/b/g. It is to achieve that by adding MIMO (multiple-input, multiple-output), using multiple antennas. Average throughput of 100+ Mbps.|
|Bluetooth ||2 Mbps ||2.45 GHz ||FHSS ||PPTP, VPN or SSL ||No native TCP/IP support. Best suited to connect PDAs, cell phones and peripheral devices at short distances.|
|HomeRF ||10 MBps ||2.4 GHz ||FHSS ||56-bit encryption, separate IPs for each network. ||No longer supported. 150 feet range, intended for home use. Reserves part of available bandwidth for voice services. Responds well to interference because of FHSS.|
|HiperLAN/1 ||20 MBps ||5 GHz ||CSMA/CA ||individual authentication and per-sesison encryption keys ||Only used in Europe. Ad-hoc WLAN, requires no configuration or central controller.|
|HiperLAN/2 ||54 MBps ||5 GHz ||OFDM ||individual authentication and per-session encryption keys ||Only used in Europe.It can carry ATM cells, IP packets, Firewire packets, as well as digital voice (cellular phones).|