santosh nath wrote:

> Jerry Avins <jya@ieee.org> wrote in message news:<bkhl5k$fah$1@bob.news=
=2Ercn.net>...
>=20
>>santosh nath wrote:
>>
>>   ...
>>
>>>
>>>I am aware of MIMO since we are currently working on 2 x 2 MIMO as par=
t
>>
>>=20
>>
>>>of project. Definitely I meant single link - no resource resuage like =
M
>>
>> IMO.
>>
>>>My Belief is that there could some system - may be we have to wait for=
=20
>>
>> future!!
>>
>>>Regards,
>>>Santosh
>>
>>
>>Could that system lead us to a hyper-light-speed star drive?
>>
>>Jerry
>=20
>=20
> Remember even light ceases at "Black hole" - time is unlimited there.
> When somethings like that comes first it is hard to believe or prove it=
 to
> others who are biased!
> Regards,
> Santosh

Paraphrasing William James: When something is new, they say it isn't=20
true. Later, when its truth becomes evident, they say it isn't useful.=20
Finally, when its utility is manifest, they say, "So what? It's old!"

Jerry
--=20
Engineering is the art of making what you want from things you can get.
=AF=AF=AF=AF=AF=AF=AF=AF=AF=AF=AF=AF=AF=AF=AF=AF=AF=AF=AF=AF=AF=AF=AF=AF=AF=
=AF=AF=AF=AF=AF=AF=AF=AF=AF=AF=AF=AF=AF=AF=AF=AF=AF=AF=AF=AF=AF=AF=AF=AF=AF=
=AF=AF=AF=AF=AF=AF=AF=AF=AF=AF=AF=AF=AF=AF=AF=AF=AF=AF=AF=AF=AF

Jerry Avins <jya@ieee.org> wrote in message news:<bkhl5k$fah$1@bob.news.rcn.net>...
> santosh nath wrote:
> 
>    ...
> > 
> > 
> > I am aware of MIMO since we are currently working on 2 x 2 MIMO as part
>  
> > of project. Definitely I meant single link - no resource resuage like M
>  IMO.
> > 
> > My Belief is that there could some system - may be we have to wait for 
>  future!!
> > 
> > Regards,
> > Santosh
> 
> 
> Could that system lead us to a hyper-light-speed star drive?
> 
> Jerry

Remember even light ceases at "Black hole" - time is unlimited there.
When somethings like that comes first it is hard to believe or prove it to
others who are biased!
Regards,
Santosh

On Thu, 18 Sep 2003, James K. wrote:

> "Julius Kusuma" <kusuma@mit.edu> wrote in message
> news:Pine.GSO.4.55L.0309171019250.19793@buzzword-bingo.mit.edu...
>
> Thank you for your kindness answer.
> I have another simple question on this issue, too.
>
> > if the noise is correlated with the data you can use it to help estimate
> > your message.  the problem is now how to contruct the best estimator.
>
> Supppose the noise Nc(D)=H(D)*N(D) is
> significantly correlated the channel H(D).
> Is it not true that after the matched filtering with H*(D^-1),
> this colored noise Nc(D) is more amplified at the receiver
> than a white nose N(D) so it is less capacity achievable.
>

inverse filtering is not optimal, you have to construct the ML detector
for this case.  if the noise is correlated with the channel, the
correlation can be taken advantage of.

a simple example if ML detection for ISI channels, which is using a
sequence estimator (ie, viterbi decoder).  if you had tried to invert the
channel then the noise at the output will be correlated with the channel,
and you know that this is not optimal.

> > --
> > The most rigorous proofs will be shown by vigorous handwaving.
> > http://www.mit.edu/~kusuma
> >
> > opinion of author is not necessarily of the institute
>
> Thank you in advance.
> --
> Regards,
> ---
> James (txdiversity@hotmail.com)
> - Private opinions: These are not the opinions from my affiliation.
>
>
>

-- 
The most rigorous proofs will be shown by vigorous handwaving.
http://www.mit.edu/~kusuma

opinion of author is not necessarily of the institute

santosh nath wrote:

   ...
>=20
>=20
> I am aware of MIMO since we are currently working on 2 x 2 MIMO as part=

> of project. Definitely I meant single link - no resource resuage like M=
IMO.
>=20
> My Belief is that there could some system - may be we have to wait for =
future!!
>=20
> Regards,
> Santosh


Could that system lead us to a hyper-light-speed star drive?

Jerry
--=20
Engineering is the art of making what you want from things you can get.
=AF=AF=AF=AF=AF=AF=AF=AF=AF=AF=AF=AF=AF=AF=AF=AF=AF=AF=AF=AF=AF=AF=AF=AF=AF=
=AF=AF=AF=AF=AF=AF=AF=AF=AF=AF=AF=AF=AF=AF=AF=AF=AF=AF=AF=AF=AF=AF=AF=AF=AF=
=AF=AF=AF=AF=AF=AF=AF=AF=AF=AF=AF=AF=AF=AF=AF=AF=AF=AF=AF=AF=AF

eric.jacobsen@ieee.org (Eric Jacobsen) wrote in message news:<3f6b564a.48641277@news.west.earthlink.net>...
> On 17 Sep 2003 15:14:46 -0700, santosh.nath@ntlworld.com (santosh
> nath) wrote:
> 
> >allnor@tele.ntnu.no (Rune Allnor) wrote in message news:<f56893ae.0309170321.2a088de6@posting.google.com>...
> >> "James K." <txdiversity@hotmail.com> wrote in message news:<3f67350c@shknews01>...
> >> > "Rune Allnor" <allnor@tele.ntnu.no> wrote in message
> >> > news:f56893ae.0309140725.22e4b481@posting.google.com...
> >> > 
> >> > Maybe I don't fully catch up with this issue.
> >> > 
> >> > > Shannon tells you the worst case scenario, given SNR and bandwidth. If you
> >> > > design a system that meets the specs in a "Shannon channel", chances are
> >> > > that your system will meet the specs in the real world too.
> >> > 
> >> > However, is *the worst case* really worse than the case
> >> > where the noise is significantly correlated with the source data?
> >> 
> >> Again, this is slightly peripheral to my main interests, but I have a vague
> >> recollection of that Shannon's theory is valid in the simple, linear case, 
> >> i.e. where the recieved signal comprises one coherent copy of the source 
> >> signal and is only messed up by added white, Gaussian noise.
> >> 
> >> In the real world there may be other effects (multipath propagation, 
> >> fading channels) but I don't think they are included in the framework of 
> >> Shannon theory. Hence my proviso ("chances are") in my first post.
> >> 
> >> Of course, you should get second opinions from people who actually know
> >> what they are talking about in these matters...
> >> 
> >> Rune
> >
> >Hi Rune,
> >
> >My purpose of writing the article is to get rid of all " white noise"
> >discussions since it is discussed so many times and well known to
> >every reader
> >familiar with basic Shannon's capacity. At the same time, I did not
> >intend "multipath/fading/correlation" channels to interfere or dilute
> >the purpose of main discussion. ISI is treated/removed separtely by
> >equalizer and only additive white(Gaussian) noise is ensured before a
> >channel decoder(e.g Viterbi decoder)which  is quite robust against
> >white noise.
> >
> >My purpose is to start from the block where ISI due to multipath
> >fading channel
> >is removed already,we also get rid of any substential
> >interference(ACI/CCI) etc.
> >i.e channel is only corrupted by noise. 
> >I guess you pointed out that white noise is the worst case and close
> >to real
> >life purtubation and Shannon capacity is thus based on AWGN. I fully
> >agree and
> >did not deny in my post.
> >
> >My question was:
> >Can we build a noise distribution and also a receiver which can exeeds
> >white noise capacity?
> >If so the key challenges would be
> >
> >1. White noise to optimum noise(don't confuse with "no noise" - it
> >should be some noise! ) conversion
> >
> >2. Receiver tuned to the optimum noise distribution.
> >
> >Regards,
> >Santosh
> 
> I'm still not completely sure what you're asking about, but if you're
> asking whether it is possible to get more information through a
> channel than what is described by Shannon's single-use AWGN model,
> then the answer is yes.   This is what MIMO
> (miltiple-input-multiple-output) is essentially about, which exploits
> multiple uses of the same channel by taking advantage of channel
> decorrelation due to multipath propagation.

I am aware of MIMO since we are currently working on 2 x 2 MIMO as part
of project. Definitely I meant single link - no resource resuage like MIMO.

My Belief is that there could some system - may be we have to wait for future!!

Regards,
Santosh

> 
> The very general idea is that a system with NxN ports (i.e., outputs x
> inputs) can get a roughly Nx improvement in channel capacity.   There
> are caveats, and to my knowledge no one has ever built a practical
> system that really fully achieves this, but that's the general idea.
> 
> 
> 
> Eric Jacobsen
> Minister of Algorithms, Intel Corp.
> My opinions may not be Intel's opinions.
> http://www.ericjacobsen.org

On 17 Sep 2003 15:14:46 -0700, santosh.nath@ntlworld.com (santosh
nath) wrote:

>allnor@tele.ntnu.no (Rune Allnor) wrote in message news:<f56893ae.0309170321.2a088de6@posting.google.com>...
>> "James K." <txdiversity@hotmail.com> wrote in message news:<3f67350c@shknews01>...
>> > "Rune Allnor" <allnor@tele.ntnu.no> wrote in message
>> > news:f56893ae.0309140725.22e4b481@posting.google.com...
>> > 
>> > Maybe I don't fully catch up with this issue.
>> > 
>> > > Shannon tells you the worst case scenario, given SNR and bandwidth. If you
>> > > design a system that meets the specs in a "Shannon channel", chances are
>> > > that your system will meet the specs in the real world too.
>> > 
>> > However, is *the worst case* really worse than the case
>> > where the noise is significantly correlated with the source data?
>> 
>> Again, this is slightly peripheral to my main interests, but I have a vague
>> recollection of that Shannon's theory is valid in the simple, linear case, 
>> i.e. where the recieved signal comprises one coherent copy of the source 
>> signal and is only messed up by added white, Gaussian noise.
>> 
>> In the real world there may be other effects (multipath propagation, 
>> fading channels) but I don't think they are included in the framework of 
>> Shannon theory. Hence my proviso ("chances are") in my first post.
>> 
>> Of course, you should get second opinions from people who actually know
>> what they are talking about in these matters...
>> 
>> Rune
>
>Hi Rune,
>
>My purpose of writing the article is to get rid of all " white noise"
>discussions since it is discussed so many times and well known to
>every reader
>familiar with basic Shannon's capacity. At the same time, I did not
>intend "multipath/fading/correlation" channels to interfere or dilute
>the purpose of main discussion. ISI is treated/removed separtely by
>equalizer and only additive white(Gaussian) noise is ensured before a
>channel decoder(e.g Viterbi decoder)which  is quite robust against
>white noise.
>
>My purpose is to start from the block where ISI due to multipath
>fading channel
>is removed already,we also get rid of any substential
>interference(ACI/CCI) etc.
>i.e channel is only corrupted by noise. 
>I guess you pointed out that white noise is the worst case and close
>to real
>life purtubation and Shannon capacity is thus based on AWGN. I fully
>agree and
>did not deny in my post.
>
>My question was:
>Can we build a noise distribution and also a receiver which can exeeds
>white noise capacity?
>If so the key challenges would be
>
>1. White noise to optimum noise(don't confuse with "no noise" - it
>should be some noise! ) conversion
>
>2. Receiver tuned to the optimum noise distribution.
>
>Regards,
>Santosh

I'm still not completely sure what you're asking about, but if you're
asking whether it is possible to get more information through a
channel than what is described by Shannon's single-use AWGN model,
then the answer is yes.   This is what MIMO
(miltiple-input-multiple-output) is essentially about, which exploits
multiple uses of the same channel by taking advantage of channel
decorrelation due to multipath propagation.

The very general idea is that a system with NxN ports (i.e., outputs x
inputs) can get a roughly Nx improvement in channel capacity.   There
are caveats, and to my knowledge no one has ever built a practical
system that really fully achieves this, but that's the general idea.



Eric Jacobsen
Minister of Algorithms, Intel Corp.
My opinions may not be Intel's opinions.
http://www.ericjacobsen.org

allnor@tele.ntnu.no (Rune Allnor) wrote in message news:<f56893ae.0309170321.2a088de6@posting.google.com>...
> "James K." <txdiversity@hotmail.com> wrote in message news:<3f67350c@shknews01>...
> > "Rune Allnor" <allnor@tele.ntnu.no> wrote in message
> > news:f56893ae.0309140725.22e4b481@posting.google.com...
> > 
> > Maybe I don't fully catch up with this issue.
> > 
> > > Shannon tells you the worst case scenario, given SNR and bandwidth. If you
> > > design a system that meets the specs in a "Shannon channel", chances are
> > > that your system will meet the specs in the real world too.
> > 
> > However, is *the worst case* really worse than the case
> > where the noise is significantly correlated with the source data?
> 
> Again, this is slightly peripheral to my main interests, but I have a vague
> recollection of that Shannon's theory is valid in the simple, linear case, 
> i.e. where the recieved signal comprises one coherent copy of the source 
> signal and is only messed up by added white, Gaussian noise.
> 
> In the real world there may be other effects (multipath propagation, 
> fading channels) but I don't think they are included in the framework of 
> Shannon theory. Hence my proviso ("chances are") in my first post.
> 
> Of course, you should get second opinions from people who actually know
> what they are talking about in these matters...
> 
> Rune

Hi Rune,

My purpose of writing the article is to get rid of all " white noise"
discussions since it is discussed so many times and well known to
every reader
familiar with basic Shannon's capacity. At the same time, I did not
intend "multipath/fading/correlation" channels to interfere or dilute
the purpose of main discussion. ISI is treated/removed separtely by
equalizer and only additive white(Gaussian) noise is ensured before a
channel decoder(e.g Viterbi decoder)which  is quite robust against
white noise.

My purpose is to start from the block where ISI due to multipath
fading channel
is removed already,we also get rid of any substential
interference(ACI/CCI) etc.
i.e channel is only corrupted by noise. 
I guess you pointed out that white noise is the worst case and close
to real
life purtubation and Shannon capacity is thus based on AWGN. I fully
agree and
did not deny in my post.

My question was:
Can we build a noise distribution and also a receiver which can exeeds
white noise capacity?
If so the key challenges would be

1. White noise to optimum noise(don't confuse with "no noise" - it
should be some noise! ) conversion

2. Receiver tuned to the optimum noise distribution.

Regards,
Santosh

On Wed, 17 Sep 2003, James K. wrote:

> "Rune Allnor" <allnor@tele.ntnu.no> wrote in message
> news:f56893ae.0309140725.22e4b481@posting.google.com...
>
> Maybe I don't fully catch up with this issue.
>
> > Shannon tells you the worst case scenario, given SNR and bandwidth. If you
> > design a system that meets the specs in a "Shannon channel", chances are
> > that your system will meet the specs in the real world too.
>
> However, is *the worst case* really worse than the case
> where the noise is significantly correlated with the source data?
>

if the noise is correlated with the data you can use it to help estimate
your message.  the problem is now how to contruct the best estimator.

> > Rune
>
> Sorry if it came from my lack awareness.
> --
> Best regards,
> James K. (txdiversity@hotmail.com)
> - Private opinions: These are not the opinions from my affiliation.
>
>
>

-- 
The most rigorous proofs will be shown by vigorous handwaving.
http://www.mit.edu/~kusuma

opinion of author is not necessarily of the institute

"James K." <txdiversity@hotmail.com> wrote in message news:<3f67350c@shknews01>...
> "Rune Allnor" <allnor@tele.ntnu.no> wrote in message
> news:f56893ae.0309140725.22e4b481@posting.google.com...
> 
> Maybe I don't fully catch up with this issue.
> 
> > Shannon tells you the worst case scenario, given SNR and bandwidth. If you
> > design a system that meets the specs in a "Shannon channel", chances are
> > that your system will meet the specs in the real world too.
> 
> However, is *the worst case* really worse than the case
> where the noise is significantly correlated with the source data?

Again, this is slightly peripheral to my main interests, but I have a vague
recollection of that Shannon's theory is valid in the simple, linear case, 
i.e. where the recieved signal comprises one coherent copy of the source 
signal and is only messed up by added white, Gaussian noise.

In the real world there may be other effects (multipath propagation, 
fading channels) but I don't think they are included in the framework of 
Shannon theory. Hence my proviso ("chances are") in my first post.

Of course, you should get second opinions from people who actually know
what they are talking about in these matters...

Rune