Estimating the channels for implementing an ALAMOUTI technique

Hi

when u implement an ALAMOUTI technique u need to estimate the channel. each path has a complex channel responce 'h'

the received signal at the 1st receiver anntenna is :
r1 = h1*s1 + h2*s2 + n1


where s1 and s2 are the symbols transmitted. and n1 is awgn

how do i estimate this channel responce 'h1' and 'h2' for the idependent channel paths?

alamouti

Hi

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Hi

when u implement an ALAMOUTI technique u need to estimate the channel. each path has a complex channel responce 'h'

the received signal at the 1st receiver anntenna is :
r1 = h1*s1 + h2*s2 + n1


where s1 and s2 are the symbols transmitted. and n1 is awgn

how do i estimate this channel responce 'h1' and 'h2' for the idependent channel paths?
***************************************************

what do u mean by estimating h1 and h2? If you want to use a 2x2 channel matrix then u can create a complex random channel matrix with some meanand variance in MATLAB by using just a single command. i.e.
>>H = complex(rand(mean,variance,N),rand(mean,variance,M))
If your question is some what in some other sense, please let us know a bit more detail, may be we will be helpful.

MAK

what is alamouti scheme

What kind of channel model do you use?
Each channel model allow to calculate matrix H.

alamouti 2x2

thank you

this was what i was asking for

Added after 1 minutes:

i am using an AWGN channel model.

Added after 3 minutes:

how does AWGN model allow to calculate H matrix ?

alamouti channel

Hi MANIAK_44
I did it, it is simple.
If your channel is not fast fade, your channel coefficients (h1, h2) are constant over a period of time. Then if you transmit 2 known symbols to receiver (2 known symbols for transmitter and receiver) you can estimate channel coefficients and use those for another unknown symbols.
aor example channel coefficients are constant over 100 time slots in Alamouti, if u transmit known s1 and s2 in first and second time slots and estimate channel, u can use that in 98 time slots after that.
h1_hat = (r1.*conj(s1) - r2.*s2)./(s1.*conj(s1)+s2.*conj(s2));
h2_hat = (r1.*conj(s2) + r2.*s1)./(s1.*conj(s1)+s2.*conj(s2));

alamouti example

Hi

aor example channel coefficients are constant over 100 time slots in Alamouti, if u transmit known s1 and s2 in first and second time slots and estimate channel, u can use that in 98 time slots after that.
h1_hat = (r1.*conj(s1) - r2.*s2)./(s1.*conj(s1)+s2.*conj(s2));
h2_hat = (r1.*conj(s2) + r2.*s1)./(s1.*conj(s1)+s2.*conj(s2));

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Where s1 and s2 are known symbols. and r1 and r2 are the unknown symbols which keep arriving ? that means channel extimation depends on the symbol being sent ?

on the other hand the below equation given has a fixed channel estimation for all he symbols sent:
H = complex(rand(mean,variance,N),rand(mean,variance,M))

im not sure whcih one to use ?

thanx

Added after 1 minutes:

HI mkhan

can u please send the article of the book by H. BESSAI

thanx

alamonti scheme

Hi.

The Book I have mentioned is available on edaboard ebooks UL/DL section. If you could not find then please contact me on (makb78(at)hotmail.com) and i will give u the whole book.

BR,

MAK

related:www.dsplog.com/2008/10/16/alamouti-stbc/

Hi
My last answer is a common method for channel estimation. I am not sure about your uncertainty.

Re: alamouti channel

m_llaa said:

Hi MANIAK_44
I did it, it is simple.
If your channel is not fast fade, your channel coefficients (h1, h2) are constant over a period of time. Then if you transmit 2 known symbols to receiver (2 known symbols for transmitter and receiver) you can estimate channel coefficients and use those for another unknown symbols.
aor example channel coefficients are constant over 100 time slots in Alamouti, if u transmit known s1 and s2 in first and second time slots and estimate channel, u can use that in 98 time slots after that.
h1_hat = (r1.*conj(s1) - r2.*s2)./(s1.*conj(s1)+s2.*conj(s2));
h2_hat = (r1.*conj(s2) + r2.*s1)./(s1.*conj(s1)+s2.*conj(s2));

Click to expand...

In the above channel estimation, you can choose each si (i=1,2) as equal to 1 and then have:
h1=h1_hat+h2_hat
h2=h2_hat-h1_hat

How do I find the channel coefficients for a two input two output system ? I mean to say that there are two transmitters and two receivers which means that my channel matrix will be a 2*2 one ... any help is appreciated. thanks

please can anyone help with matlab code for channel estimation in Alamouti technique.
Thanks in advance.

hallo m_llaa ...
your post about channel estimation for alamouti it's for 2x1 diversity technique right?
how to estimate the mimo alamuti channel using 2x2 antennas on Tx and Rx? thank you very much