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What is OFDMA and how can we compare it with TDMA and FDMA?

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What is OFDMA and how can we compare it with TDMA and FDMA?
posted Nov 17, 2014 by anonymous

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1 Answer

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OFDM : Orthogonal Frequency Division Multiplexing
It is a modulation method that divides a channel into multiple narrow orthogonal bands that are spaced so they don’t interfere with one another. Each band is divided into hundreds or even thousands of 15-kHz wide subcarriers.

FDMA: Frequency Division Multiple Access
Here a channel/band is divided into multiple sub bands & each is used by single user.

TDMA : Time Division Multiple Access
Here a single band/channel multiple time slots.

answer Sep 20, 2016 by Shivananda Gavalkar S
Similar Questions
+1 vote

PAPR is the major disadventage of OFDMA which require high resolution D/A and A/D or increasing Transmission Power.
I know that SC-FDMA used on Uplink becuase it has lower PAPR than OFDMA. On downlink direction, the high PAPR Problem of OFDMA solved by increasing eNB transmission power. This solution cannot be implemented on Uplink direction because UL is power limited link. so SC-FDMA used on UL instead of OFDMA, but why? why SC-FDMA has LOWER PAPR

+1 vote

LTE is using OFDMA for downlink and SC-FDMA for uplink. How downlink data rate is high as compare to uplink. what factors create this difference.

+1 vote

I was going through the OFDMA wiki page (http://en.wikipedia.org/wiki/Orthogonal_frequency-division_multiple_access) it seems that it is registered trademark of http://www.runcom.com/ and giving the impression of OFDMA is new technology. But while Googling further I found that it was invented in 1957 [ Kineplex, multi-carrier HF modem (R.R. Mosier & R.G. Clabaugh)]

Now the question is why telecom industry took so much of time to adopt OFDMA as access technology in the form of LTE/WiMax. Was there some reason or it was ignorance of telecom industry?

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