Cedric Roux
56c66c09aa
Pre-ci test passed git-svn-id: http://svn.eurecom.fr/openair4G/trunk@4000 818b1a75-f10b-46b9-bf7c-635c3b92a50f
91 lines
2.1 KiB
Matlab
Executable File
91 lines
2.1 KiB
Matlab
Executable File
%Block Diagonal Waterfilling
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%Authors: Nihar Jindal, Wonjong Rhee, Sriram Vishwanath, Syed Jafar, Andrea
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%Goldsmith
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%Date: 6/20/05
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function [capacity, Ex] = waterfill_block(H, P);
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%Returns optimal covariance matrix and capacity for
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%block diagonal channel H, where H(:,:,1) is first channel, H(:,:,2) is 2nd
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%etc.
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%Function Inputs
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%H: triply indexed channel
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% H(:,:,k) refers to the UPLINK channel of the kth receiver
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% H(:,:,k) is an (M x N) matrix
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%P: power in linear units
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%Function Outputs
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%capacity: Capacity in bps/Hz
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%Ex: triply indexed matrices containing the capacity achieving
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% covariance matrices
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% Ex(:,:,k) is the (N x N) covariance of user k
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%Other Variables
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%M: # of base station antennas in downlink channel
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%N: # of terminal antennas in downlink channel
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[M,N,K] = size(H);
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for index = 1:K
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%Perform SVD of channel
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v = svd(H(:,:,index)' * H(:,:,index));
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%Create vector with all singular values
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if (index == 1)
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s = v;
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else
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s = [s; v];
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end;
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end;
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channels = length(s);
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s = real(s);
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%Eliminate zeroes
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s = max(s, 1e-10);
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noise_vector = 1./s;
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unsortedN = noise_vector;
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%Put noise variances in increasing order
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noise_vector = sort(noise_vector);
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last = channels; %index of worst channel allocated non-zero power
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loop = 1;
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%Find channels allocated non-zero power
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while (loop)
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water = noise_vector(last); %water level
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power = sum(max(water - noise_vector, 0));
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if (power > P)
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last = last - 1;
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else
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loop = 0;
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end;
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end;
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%Calculate optimal water level
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water = 1/last * (P + sum(noise_vector(1:last)));
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capacity = 0;
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Ex = zeros(N,N,K);
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%Compute covariance matrix for each user
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for index = 1:K
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%Take svd of channel
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[u,v,w] = svd(H(:,:,index)' * H(:,:,index));
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s = svd(H(:,:,index)' * H(:,:,index));
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s = real(s);
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%eliminate zeroes
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s = max(s, 1e-10);
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noise_vector = 1./s;
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Ex(:,:,index) = u * diag(max((water- noise_vector),0)) * u';
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capacity = capacity + real(log2(det(eye(M) + H(:,:,index) *Ex(:,:,index)* H(:,:,index)')));
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end;
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