5 GHz WLAN Tapio Sokura

Agenda Early Wireless LANs Current standards 5 GHz –IEEE a/h –ETSI HiperLAN/2 The king of the hill Compatibility Conclusions

Early Wireless LANs Military applications as early as WW II ALOHAnet connected the Hawaiian islands in 1970s –CSMA was born here Proprietary WLANs in the 1990s –typically 2 Mb/s on the 900 MHz (USA) and 2.4 GHz (USA & rest of the world) ISM-bands

Current standards, IEEE 1997: (2.4 GHz, 2 Mb/s) 1999: b (2.4 GHz, 11 Mb/s) 1999: a (5 GHz, 54 Mb/s) 2000: Wi-Fi certification began for b Estimated: –summer 2003: g (2.4 GHz, 54 Mb/s) –end of 2003: h, Europe-compatible a –end of 2003: i, security enhancements

Current standards, ETSI HIgh PErformance Radio LAN 1998: HiperLAN/1 –5 GHz, 23 Mb/s –general wireless technology for portable devices 2000: HiperLAN/2 –5 GHz, 54 Mb/s –same as above + wireless LANs

Why 5 GHz? The need for more speed and capacity –requires more bandwidth 2.4 GHz WLAN-band is only 83 MHz wide 5 GHz WLAN-bands cover MHz depending on country Less interference from other devices –2.4 GHz ISM-band has many other users, such as Bluetooth and microwave owens Next stop: 17 GHz?

Global problems with 5 GHz WLAN-usable frequency allocations differ Maximum power levels and indoor/outdoor usage restrictions differ European requirements for 5 GHz WLANs: –Dynamic Frequency Selection, DFS –Transmit Power Control, TPC –802.11h will support DFS & TPC

5 GHz band plan Original by Martin Johnsson:

IEEE a 5 GHz, 54 Mb/s, OFDM, CSMA/CA –no QoS, broken WEP security as in b up to 19 non-overlapping channels available depending on country –only 3-5 non-overlapping channels in b The only practical differences to b are in the physical layer.

ETSI HiperLAN/2 5 GHz, 54 Mb/s, OFDM, TDMA –physical layer is compatible with a/h aimed to be a general wireless access solution –support for Quality-of-Service built-in –compatible with ATM, 3G, LAN... architectures advanced features: –one- and two-way authentication, 3DES encryption –dynamic frequency selection, transmit power contr.

Future king of the hill (1/2) HiperLAN/2 is technically superior to a –but there are no HiperLAN/2 products in the market (estimated price should be about the same) a has many supporters (incl. Wi-Fi) and it’s based on proven technology –and it’s available in the shops now –802.11h will make it easier for manufacturers to offer their products in Europe

Future king of the hill (2/2) Does a typical user really need more speed? –many mobile and PDA users will be happy with b for a long time to come g offers 54 Mb/s on 2.4 GHz (only 3 channels) and is compatible with b äIf something radical doesn’t happen with HiperLAN/2, a/h will dominate 5 GHz

Compatibility IEEE a/h, ETSI HiperLAN/2 and MMAC (Japan) are compatible in the physical layer –it should be possible to use common hardware and change only the soft/firmware between standards a/h is not compatible with b, dual- band access points are needed to cover both g is compatible with b

Conclusions b will be around for a long time –WLAN speed is usually not an issue for mobile or PDA users a/h will probably dominate 5 GHz g gains ground on 2.4 GHz, especially in areas that don’t allow a HiperLAN/2 is in serious danger of becoming (or staying) a dead standard. Betamax anyone?

References HiperLAN/2 Global Forum, ETSI BRAN, Ficora band plans, IEEE Working Group,