Comments on: Alamouti STBC http://www.dsplog.com/2008/10/16/alamouti-stbc/ Signal Processing for Communication Fri, 30 Jul 2010 01:36:27 +0000 http://wordpress.org/?v=2.9.2 hourly 1 By: Krishna Sankar http://www.dsplog.com/2008/10/16/alamouti-stbc/#comment-32020 Krishna Sankar Wed, 23 Jun 2010 23:09:15 +0000 http://www.dsplog.com/?p=247#comment-32020 @fhuang: Transmitting the same signal from both the antennas does not help to improve diversity. I have discussed this briefly in the post http://www.dsplog.com/2009/04/13/transmit-beamforming/ @fhuang: Transmitting the same signal from both the antennas does not help to improve diversity. I have discussed this briefly in the post
http://www.dsplog.com/2009/04/13/transmit-beamforming/

]]> By: Krishna Sankar http://www.dsplog.com/2008/10/16/alamouti-stbc/#comment-31707 Krishna Sankar Mon, 21 Jun 2010 00:10:01 +0000 http://www.dsplog.com/?p=247#comment-31707 @Maduranga: Sending the same signal from both the antennas does not provide any diversity gain. For eg, consider a 2tx-1rx system having y = h1x + h2x + n, where y - is the received symbol h1 - channel from tx antenna 1 to rx antenna h2 - channel from tx antenna 2 to rx antenna x - transmitted symbol n - noise The above can be written as y = (h1+h2)x + n, which kinda gives similar BER performance to y = hx+n case I have discussed briefly about this @ http://www.dsplog.com/2009/04/13/transmit-beamforming/ @Maduranga: Sending the same signal from both the antennas does not provide any diversity gain.
For eg, consider a 2tx-1rx system having
y = h1x + h2x + n, where
y – is the received symbol
h1 – channel from tx antenna 1 to rx antenna
h2 – channel from tx antenna 2 to rx antenna
x – transmitted symbol
n – noise
The above can be written as
y = (h1+h2)x + n, which kinda gives similar BER performance to y = hx+n case

I have discussed briefly about this @
http://www.dsplog.com/2009/04/13/transmit-beamforming/

]]> By: Krishna Sankar http://www.dsplog.com/2008/10/16/alamouti-stbc/#comment-31704 Krishna Sankar Mon, 21 Jun 2010 00:04:25 +0000 http://www.dsplog.com/?p=247#comment-31704 @metios: What is the distribution of the interference? Gaussian? @metios: What is the distribution of the interference? Gaussian?

]]> By: metios http://www.dsplog.com/2008/10/16/alamouti-stbc/#comment-31551 metios Thu, 17 Jun 2010 14:14:51 +0000 http://www.dsplog.com/?p=247#comment-31551 I had a problem with the detection of the symbols, i had a lot of errors, but i fix its, plaz if you can help me to introduce interference, i cannot find the formula for that.. I have already simulate alamoyti 2×1 and now i want to go further, i want to introduce interference and my channel become Y=Hs+n+I, where I is the interference, assuming that Interference power=1 and distance=100 what is the new formula for sigma to introduce interference and compare it with alamouti without interference.. sigma=0.5*(1/(10^(SNRdb(i)./10))); sqsigma=sqrt(sigma); I had a problem with the detection of the symbols, i had a lot of errors, but i fix its, plaz if you can help me to introduce interference, i cannot find the formula for that..

I have already simulate alamoyti 2×1 and now i want to go further, i want to introduce interference and my channel become Y=Hs+n+I, where I is the interference, assuming that Interference power=1 and distance=100 what is the new formula for sigma to introduce interference and compare it with alamouti without interference..

sigma=0.5*(1/(10^(SNRdb(i)./10)));
sqsigma=sqrt(sigma);

]]> By: Maduranga http://www.dsplog.com/2008/10/16/alamouti-stbc/#comment-31530 Maduranga Thu, 17 Jun 2010 07:29:32 +0000 http://www.dsplog.com/?p=247#comment-31530 Hello Krishana, Thank you very much for all the nice posts you make. I want to ask regarding the Alamouti. You mentioned that Alamouti is similar to MRC in BER performance. And in the context of MIMO, Alamouti is said to achieve full diversity. My confusion is, since the channel is block fading and the antenna paths are uncorrelated, what will be the effect of sending [x1 x1; x2 x2]. So you send the same signal in both antennas and do MRC. In this case, how would the performance change? Thank you. Hello Krishana,

Thank you very much for all the nice posts you make.
I want to ask regarding the Alamouti. You mentioned that Alamouti is similar to MRC in BER performance. And in the context of MIMO, Alamouti is said to achieve full diversity.

My confusion is, since the channel is block fading and the antenna paths are uncorrelated, what will be the effect of sending [x1 x1; x2 x2]. So you send the same signal in both antennas and do MRC. In this case, how would the performance change?

Thank you.

]]> By: Krishna Sankar http://www.dsplog.com/2008/10/16/alamouti-stbc/#comment-31333 Krishna Sankar Mon, 14 Jun 2010 01:15:49 +0000 http://www.dsplog.com/?p=247#comment-31333 @Mohammad Jarrah: Sorry, I have not tried simulating that paper. @Mohammad Jarrah: Sorry, I have not tried simulating that paper.

]]> By: Krishna Sankar http://www.dsplog.com/2008/10/16/alamouti-stbc/#comment-31328 Krishna Sankar Mon, 14 Jun 2010 01:08:46 +0000 http://www.dsplog.com/?p=247#comment-31328 @metios: Plz refer the example code in this post for reference. @metios: Plz refer the example code in this post for reference.

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