interview question: what's the adv of MIMO OFDM over MIMO CDMA?# EE - 电子工程
p*d
1 楼
rt,
been asked a couple of times, but no good answer.
Thanks!!
been asked a couple of times, but no good answer.
Thanks!!
a*e
2 楼
maybe this article helps
http://www.shorecliffcommunications.com/magazine/volume.asp?Vol=28&story=278
【在 p********d 的大作中提到】
: rt,
: been asked a couple of times, but no good answer.
: Thanks!!
http://www.shorecliffcommunications.com/magazine/volume.asp?Vol=28&story=278
【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!!
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.
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.
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.
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?
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?
t*o
8 楼
low-complexity receiver？跟哪种receiver比吧？正在学MIMO, OFDM的文章。觉得那
个channel estimation不简单。还不知道怎么象 CDMA 那样支持多个用户同时通信。
【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, ...
个channel estimation不简单。还不知道怎么象 CDMA 那样支持多个用户同时通信。
【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, ...
k*a
9 楼
For multiuser, use MIMO-OFDMA as in Wimax.
【在 t***o 的大作中提到】
: low-complexity receiver？跟哪种receiver比吧？正在学MIMO, OFDM的文章。觉得那
: 个channel estimation不简单。还不知道怎么象 CDMA 那样支持多个用户同时通信。
【在 t***o 的大作中提到】
: low-complexity receiver？跟哪种receiver比吧？正在学MIMO, OFDM的文章。觉得那
: 个channel estimation不简单。还不知道怎么象 CDMA 那样支持多个用户同时通信。
a*w
10 楼
higher data rate, absolutely
mitiple tx and rx with ofdm
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.
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.
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
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
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