Cedric Roux
56c66c09aa
Pre-ci test passed git-svn-id: http://svn.eurecom.fr/openair4G/trunk@4000 818b1a75-f10b-46b9-bf7c-635c3b92a50f
74 lines
2.1 KiB
Matlab
Executable File
74 lines
2.1 KiB
Matlab
Executable File
%Sum Power Iterative Waterfilling Algorithm
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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, Covariances] = iterative_waterfill(H, P, iterations);
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%Function Inputs
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%H: triply indexed UPLINK 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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%iterations: # of iterations performed
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%Function Outputs
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%capacity: Sum rate capacity in bps/Hz
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%Covariances: triply indexed matrices containing the capacity achieving
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% UPLINK covariance matrices
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% Covariances(:,:,k) is the (N x N) covariance of user k
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%Other Variables
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%M: # of transmit antennas in downlink channel
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%N: # of receive antennas in downlink channel
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%K: # of receivers
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%Determine # of antennas, users
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[M,N,K] = size(H);
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%Initialize covariances to zero
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Covariances = zeros(N,N,K);
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for wf_iterations = 1:iterations
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sum_int = eye(M);
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for k = 1:K
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sum_int = sum_int + H(:,:,k) * Covariances(:,:,k) * H(:,:,k)';
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end;
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%Generate effective channels of each user (using covariances from the
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%previous step)
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for k = 1:K
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H_eff(:,:,k) = (sum_int - H(:,:,k) * Covariances(:,:,k) * H(:,:,k)')^(-0.5) * H(:,:,k);
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end;
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%Perform waterfilling across effective channels
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[temp, Ex] = waterfill_block(H_eff, P);
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%Update covariances of all users
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%Use original algorithm for first 5 iterations to speed up convergence
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if (wf_iterations <= 5)
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%Updated covariances set equal to new covariances
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for k = 1:K
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Covariances(:,:,k) = Ex(:,:,k);
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end;
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else
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%Update covariances with mixture of old and new covariances
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for k = 1:K
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Covariances(:,:,k) = ((K-1)/K)*Covariances(:,:,k) + (1/K) * Ex(:,:,k);
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end;
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end;
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end;
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%Compute final sum rate
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sum_int = eye(M);
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for k = 1:K
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sum_int = sum_int + H(:,:,k) * Covariances(:,:,k) * H(:,:,k)';
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end;
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capacity = real(log2(det(sum_int)));
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