Cedric Roux
56c66c09aa
Pre-ci test passed git-svn-id: http://svn.eurecom.fr/openair4G/trunk@4000 818b1a75-f10b-46b9-bf7c-635c3b92a50f
94 lines
3.1 KiB
Matlab
Executable File
94 lines
3.1 KiB
Matlab
Executable File
function [CAP] = capacity_MU_ZF(H,SNR,normalize)
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%
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% [CAP] = capacity_MU_ZF(H,SNR)
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%
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% This function calculate the multiuser (MU) capacity of the estimated
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% EMOS channels assuming a zero forcing (ZF) precoder and one stream per
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% user. This requires that NTx >= NUser. At the receiver antenna
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% selection is assumed.
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% The channel gains are normalized, such that E(|h_{i,j}|^2) = 1 hold for
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% each user. The averaging is done over all snapshots and all frequencies.
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%
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% PARAMATERS
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% - H is the input channel (NRx,NTx,Nfreq,NFrames,NUser)
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% - SNR is the considered SNR (Linear)
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%
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% RETURNS
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% - [CAP] is the capacity values
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% Authors: florian.kaltenberger@eurecom.fr
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% Copyright: Eurecom Sophia Antipolis
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% Created: 17/10/2007
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% Modified last: 17/10/2007 by florian.kaltenberger@eurecom.fr
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[NRx,NTx,NFreq,Nframes,NUser] = size(H);
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if NRx~=2
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warning('[capacity_MU_ZF] The antenna selection in this script might not work properly for more than 2 Rx antennas');
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end
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if nargin<3
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normalize = 1;
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end
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if normalize
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% Normalization of H, such that E(|h_{i,j}|^2) = 1!
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disp('[capacity_MU_ZF] Normalization of H')
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HH = complex(zeros(NRx,NRx,NFreq,Nframes,NUser));
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mean_pow = zeros(1,NUser);
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for kk = 1:NUser ,
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for ii = 1:NFreq,
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for jj = 1:Nframes,
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% this is the frobenious norm of H
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HH(:,:,ii,jj,kk) = H(:,:,ii,jj,kk)*H(:,:,ii,jj,kk)';
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mean_pow(kk) = mean_pow(kk) + trace(HH(:,:,ii,jj,kk));
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end
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end
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mean_pow(kk) = mean_pow(kk)/(NFreq*Nframes);
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H(:,:,:,:,kk) = H(:,:,:,:,kk) .* sqrt(NRx*NTx/real(mean_pow(kk))); %*
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end
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disp(sqrt(NRx*NTx./real(mean_pow)))
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end
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% * make sure the power is real (due to numerical inaccuracies, there might
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% be a small imaginary part)
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% mean_pow = real(mean_pow);
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% Capacity calculation
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disp('[capacity_MU_ZF] Capacity calculation')
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% H_MISO = complex(zeros(NUser,NTx));
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lambda = zeros(Nframes,NFreq);
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for ii = 1:NFreq,
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for jj = 1:Nframes,
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% Select the antenna with the higher channel weight (the
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% received power at Rx antenna m is already computed in
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% HH(m,m,ii,jj,kk)) and form the MU channel matrix.
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% Warning: This antenna selection does not really work
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% For now we take antenna 1
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% if HH(1,1,ii,jj,kk) < HH(2,2,ii,jj,kk)
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% % take antenna 2
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% H_MISO = squeeze(H(2,:,ii,jj,:)).';
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% else
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% take antenna 1
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H_MISO = squeeze(H(1,:,ii,jj,:)).';
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% end
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% The precoder matrix W is given by
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% W = pinv(H_MISO)/norm(pinv(H_MISO))
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% However, we only need the denominator of this expression for
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% the capacity calculations.
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if all(all(H_MISO==0))
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lambda(jj,ii) = Inf;
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else
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lambda(jj,ii) = norm(pinv(H_MISO),'fro');
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end
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end
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end
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CAP = zeros(Nframes,NFreq);
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for kk = 1:NUser
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CAP = CAP + log2(1+ SNR ./ lambda.^2);
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end
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