Is OFDMA for mobile communication only?

[mazdaspring]

Is ODFMA for mobile communication only?

and OFDM for fixed wireless communication only?

is MIMO-OFDM different from MIMO-OFDMA system?

I want to do PhD research that I can learn both broadband communication (e.g. wimax) and mobile communication. (both wirless)

what topic should I do.
(about mimo, ofdm, ofdma only)

 

[sajjadi335]

OFDMA and OFDM are not exclusive to mobile or fixed. OFDMA is defined in 802.16.2004 besides OFDM for fixed wireless, and both are being cosidered (maybe standardized) for mobile.
MIMO a feature added to any communications system, so that spatial redundancy is used for better performance, and it has been applied to both OFDM and OFDMA.
If you're gonna do PhD, you should first no much more, but as a point, MIMO is going to be something very important in both systems, and various modulation/access schemes might be discussed there in.

 

[rooftile]

OFDMA is not for mobile communications only: it's an access technique (not a modulation) where substes of subcarriers (obtained with OFDM modulation) are assigned to individual users.

OFDM is not for wireless communications only: it's used even in xDSL systems (I have worked on in the past!)

MIMO-OFDM and MIMO-OFDMA are different in concept: the first is a modulation, the second is a multiple access technique for multi-user version of OFDM.

I hope it can help you.