Wi-Fi is abbrevasion from Wireless Fidelity, have a undestanding namely a set of standard that use for local network nircable (Wireless Local Area Network - WLAN) that based on specification IEEE 802.11.IEEE 802.11g is a standard niscable network that work on frequency 2,45 GHz and used modulation method OFDM. 802.11 that on publication on june 2003 capable achieve apeed until 54 Mb/s on frequence ribbon 2,45 GHz, like same as IEEE 802.11 ordinary IEEE 802.11b.
excess 802.11g have speed spedy maximum, reach signal is good and not easy hampered. whereas shortage from 802.11g is cost more from 802.11b, equipment can interfere signal on frequence that not to controle.
IEEE 802.11g is a standard nircable Network that work on frequence 2,45 GHz and makemodulation method OFDM. Orthogonal frequency-division multiplexing (OFDM) is a frequence-division multiplexing (FDM) that be used for scema multi-carrier digital modulation method.
Orthogonal Frequency Division Multiplexing is new teknology just start achieve LAN nircable (WLAN) market in form device IEEE 802.11g that be operation on 5 GHZ band. OFDM is a "muty-carrier" modulation scema. data be devided on between some of adjacent "subcarriers"
provide from OFDM is :
- can with easy to adapt with condition channel severe without complexs equalization.
- stronger against narrow-band co-channel interference.
- stronger against interference intersymbol (ISI) and fading caised by multipath propagation.
- high spectrum efficience than with conventional modulation scema, spreat spectrum etc.
- low cencitiveto time sincronisation false.
shortage of OFDM is:
- sensitive against shift doppler.
- sensitive against problem sincronisation frequence.
- Peak-to-rata-Power Ratio (PAPR), require emission circuit
linier, that suffer from efisience power that bad.
- almost a lot of from efisiece spectrume that offered by vestigial sideband modulation for example used in ATSC sistem TV digital.
