【在 p********d 的大作中提到】 : rt, : been asked a couple of times, but no good answer. : Thanks!!
H*e
3 楼
how about MIMO-OFDM can achieve higher data rate with low-complexity receiver, can exploit frequency selectivity of channel, require no power control, ...
【在 p********d 的大作中提到】 : rt, : been asked a couple of times, but no good answer. : Thanks!!
p*d
4 楼
What you talked about is the advantage of OFDM over CDMA. The key is how MIMO comes into play.
m*o
5 楼
I am here. How should I play?
【在 p********d 的大作中提到】 : What you talked about is the advantage of OFDM over CDMA. : The key is how MIMO comes into play.
a*e
6 楼
MISO or SIMO is enough for CDMA 'cause SNR is low, while for OFDM MIMO is much more advantagous because of the extra degrees of freedom. Is this a good point?
【在 p********d 的大作中提到】 : What you talked about is the advantage of OFDM over CDMA. : The key is how MIMO comes into play.
O*M
7 楼
or, in MIMO, we can collect enough diversity in the spatial domain (too much diversity may not be necessary as it kind of saturates in the end). Given t hat OFDM is orthogonal in the freq. domain, the complexity of MIMO OFDM woul d be much simpler than MIMO CDMA, which has non-orthogonality at both space and freq domain.
【在 a*******e 的大作中提到】 : MISO or SIMO is enough for CDMA 'cause SNR is low, while for OFDM MIMO is : much more advantagous because of the extra degrees of freedom. : Is this a good point?
【在 H*******e 的大作中提到】 : how about MIMO-OFDM can achieve higher data rate with low-complexity : receiver, can exploit frequency selectivity of channel, require no power : control, ...
higher data rate, absolutely mitiple tx and rx with ofdm
f*g
11 楼
For MIMO, it is difficult to deal with a dispersed channel. There is a method called generalized decision feedback equalizer (GDFE). But it has high complexity and is not practical currently. OFDM provides an easier way to deal with dispersed channel (also called frequency selective fading). Each sub-carrier can be considered as an independend flat-fading channel during MIMO processing. Therefore, the concept, design and implementation are all much easier.
j*c
12 楼
Good point. I think there might be another reason. OFDM can provide high spectral efficiency, while it can not achieve diversity. On the other hand, MIMO can provide spatial diversity. By combining those two, high data-rate and diversity can be achieved at the same time. Just my own understanding.
way
【在 f*****g 的大作中提到】 : For MIMO, it is difficult to deal with a dispersed channel. There is a : method called generalized decision feedback equalizer (GDFE). But it has : high complexity and is not practical currently. OFDM provides an easier way : to deal with dispersed channel (also called frequency selective fading). : Each sub-carrier can be considered as an independend flat-fading channel : during MIMO processing. Therefore, the concept, design and implementation : are all much easier.
f*g
13 楼
It has been a point of debating whether OFDM provides high spectral efficiency. For a well-controlled channel such as a telephone line, both OFDM and single-carrier modulations can achieve spectral efficiencies close to the Shannon bound. The advantage of OFDM is low complexity. But even that is debatable depending on application conditions. For wireless channels, there are many more issues. Probably OFDM is better in handling some of them. But I doubt that in general, OFDM can achieve bet
【在 j******c 的大作中提到】 : Good point. I think there might be another reason. OFDM can provide high : spectral efficiency, while it can not achieve diversity. On the other hand, : MIMO can provide spatial diversity. By combining those two, high data-rate : and diversity can be achieved at the same time. Just my own understanding. : : way