Wimax or World wide interoperability for microwave access is a technology by which you get broadband on your mobile.Its like wifi but not a wifi.In wimax you get upto 10Mbps or Practically 2Mbps speed on the move.Move refers to your entire city where as in wifi its limited to particular area.Based on OFDMA that is Orthogonal frequency Division Multiple access and multiple antenna techniques wimax is giving tough competition to other technologies.
What is OFDMA?
Lets take FDM first.. FDM or Frequency Division Multiplexing. FDM can be thought of water flowing out of tap.. Whereas OFDM signals are like shower,that is water from tap comes in big streams and cannot be subdivided whereas shower is made up of lot of little streams.Now what is the advantage?You can stop water flow from tap easily if you put your thumb on tap hole whereas it cannot be done for shower.That is interference is min possible OFDM.In OFDM subchannelisation of signals are done and these subchannels are multiplexed by FDM and forms multi-carrier transmission.For the Subchannelisation the signals must be orthogonally transmitted.That is their product does not hamper the other sub signals.
The multiplexing of signals can also be done by Code Division Multiplexing(CDM) but that is used for CDMA .
OFDMA is same as OFDM but in OFDMA the Subchannelisation of signals are not just limited to Downlink but are even used in Uplink. thus in OFDMA different subchannels may be allocated to different users as a multiple-access mechanism.
IEEE standardised Wimax as 802.16 for LOS communication
802.16a-d for NLOS communication used in fixed Wimax
and 802.16e for mobile Wimax
So Wimax is a next generation technology and is even known as 4G.
What is OFDMA?
Lets take FDM first.. FDM or Frequency Division Multiplexing. FDM can be thought of water flowing out of tap.. Whereas OFDM signals are like shower,that is water from tap comes in big streams and cannot be subdivided whereas shower is made up of lot of little streams.Now what is the advantage?You can stop water flow from tap easily if you put your thumb on tap hole whereas it cannot be done for shower.That is interference is min possible OFDM.In OFDM subchannelisation of signals are done and these subchannels are multiplexed by FDM and forms multi-carrier transmission.For the Subchannelisation the signals must be orthogonally transmitted.That is their product does not hamper the other sub signals.
The multiplexing of signals can also be done by Code Division Multiplexing(CDM) but that is used for CDMA .
OFDMA is same as OFDM but in OFDMA the Subchannelisation of signals are not just limited to Downlink but are even used in Uplink. thus in OFDMA different subchannels may be allocated to different users as a multiple-access mechanism.
IEEE standardised Wimax as 802.16 for LOS communication
802.16a-d for NLOS communication used in fixed Wimax
and 802.16e for mobile Wimax
So Wimax is a next generation technology and is even known as 4G.
4g is the future
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