www.gusucode.com > LTE仿真Matlab源码 > LTE_detect_TxD.m
function [LLR_SD,M,rx_layer_x_equalized] = LTE_detect_TxD(MCS_and_scheduling,BS_nAtPort,rx_user_symbols,UE_nRX,H_est_user,LTE_params,receiver,receiver_k,sigma_n2)
% Transmit diversity detection.
% Author: Stefan Schwarz, sschwarz@nt.tuwien.ac.at
% (c) 2009 by INTHFT
% www.nt.tuwien.ac.at
if (BS_nAtPort == 2)
nLayers = 2;
rx_layer_x_equalized = zeros(length(rx_user_symbols)/2,nLayers);
M = [MCS_and_scheduling.CQI_params.modulation_order] * ones(1,nLayers); % Modulation order
bittable = false(sum(M(1:nLayers)),2^max(M));
symbol_alphabet = zeros(nLayers,2^max(M));
for i = 1:nLayers
bittable(sum(M(1:i-1))+(1:M(i)),1:2^M(i))=LTE_params.bittable{M(i)}; % Bitmapping table
symbol_alphabet(i,1:2^M(i))=LTE_params.SymbolAlphabet{M(i)}.'; % Symbol alphabet
end
symbol_alphabet(2,:) = conj(symbol_alphabet(2,:)); % this is because also the received symbols get conjugated
rx_layer_x = zeros(2,length(rx_user_symbols)/2); % initialization of variable for received layers
LLR_SD = zeros(M(1)*nLayers,length(rx_user_symbols)/2); % Log likelihood Ratios of the Spere decoder
if (UE_nRX == 2) % 2x2 case
for i = 1:2:length(rx_user_symbols)-1
rx_user_symbols_combined = [rx_user_symbols(i,1);rx_user_symbols(i,2);conj(rx_user_symbols(i+1,1));conj(rx_user_symbols(i+1,2))];
H_est_user_combined = [H_est_user(i,1,1),-H_est_user(i,1,2);H_est_user(i,2,1),-H_est_user(i,2,2);conj(H_est_user(i+1,1,2)),conj(H_est_user(i+1,1,1));conj(H_est_user(i+1,2,2)),conj(H_est_user(i+1,2,1))]; % generate equivalent channel matrix
switch receiver
case 'SSD'
% ZF Detector
%%%%%%%%%%%%%%%%%%%
rx_user_symbols_combined_2 = pinv(H_est_user_combined)*rx_user_symbols_combined*sqrt(2); % calculate received symbols
rx_layer_x(1,(i+1)/2)=rx_user_symbols_combined_2(1,:); % map them to the corresponding layer
rx_layer_x(2,(i+1)/2)=rx_user_symbols_combined_2(2,:);
%%%%%%%%%%%%%%%%%%%
[Q,R]= qr(H_est_user_combined);
LLR_SD(:,(i+1)/2) = LTE_softsphere(rx_layer_x(:,(i+1)/2),rx_user_symbols_combined.'*sqrt(2),Q,R,symbol_alphabet,bittable,nLayers,M);
case 'SSDKB'
% ZF Detector
%%%%%%%%%%%%%%%%%%%
rx_user_symbols_combined_2 = pinv(H_est_user_combined)*rx_user_symbols_combined*sqrt(2); % calculate received symbols
rx_layer_x(1,(i+1)/2)=rx_user_symbols_combined_2(1,:); % map them to the corresponding layer
rx_layer_x(2,(i+1)/2)=rx_user_symbols_combined_2(2,:);
%%%%%%%%%%%%%%%%%%%
[Q,R]= qr(H_est_user_combined);
LLR_SD(:,(i+1)/2) = LTE_softsphere_kbest(rx_layer_x(:,(i+1)/2),rx_user_symbols_combined.'*sqrt(2),Q,R,symbol_alphabet,bittable,nLayers,M,receiver_k);
case 'ZF'
inv_temp = pinv(H_est_user_combined);
% ZF Detector
%%%%%%%%%%%%%%%%%%%
rx_user_symbols_combined_2 = inv_temp*rx_user_symbols_combined*sqrt(2); % calculate received symbols
rx_layer_x(1,(i+1)/2)=rx_user_symbols_combined_2(1,:); % map them to the corresponding layer
rx_layer_x(2,(i+1)/2)=rx_user_symbols_combined_2(2,:);
rx_layer_x_equalized((i+1)/2,1) = rx_user_symbols_combined_2(1,:);
rx_layer_x_equalized((i+1)/2,2) = rx_user_symbols_combined_2(2,:)';
%%%%%%%%%%%%%%%%%%%
Hg = inv_temp*H_est_user_combined;
noise_enhancement_tmp = sum(abs(inv_temp).^2,2);
noise_enhancement = [noise_enhancement_tmp(1)*ones(M(1),1);noise_enhancement_tmp(2)*ones(M(2),1)];
LLR_SD(:,(i+1)/2) = LTE_demapper(rx_layer_x(:,(i+1)/2),symbol_alphabet,bittable,nLayers,M,Hg,noise_enhancement);
case 'MMSE'
temp = H_est_user_combined'*H_est_user_combined;
inv_temp = (temp+sigma_n2*eye(size(temp)))^-1*H_est_user_combined';
% MMSE Detector
%%%%%%%%%%%%%%%%%%%
rx_user_symbols_combined_2 = inv_temp*rx_user_symbols_combined*sqrt(2); % calculate received symbols
rx_layer_x(1,(i+1)/2)=rx_user_symbols_combined_2(1,:); % map them to the corresponding layer
rx_layer_x(2,(i+1)/2)=rx_user_symbols_combined_2(2,:)';
rx_layer_x_equalized((i+1)/2,1) = rx_user_symbols_combined_2(1,:);
rx_layer_x_equalized((i+1)/2,2) = rx_user_symbols_combined_2(2,:);
%%%%%%%%%%%%%%%%%%%
Hg = inv_temp*H_est_user_combined;
noise_enhancement_tmp = sum(abs(inv_temp).^2,2);
noise_enhancement = [noise_enhancement_tmp(1)*ones(M(1),1);noise_enhancement_tmp(2)*ones(M(2),1)];
LLR_SD(:,(i+1)/2) = LTE_demapper(rx_layer_x(:,(i+1)/2),symbol_alphabet,bittable,nLayers,M,Hg,noise_enhancement);
end
end
elseif (UE_nRX == 1) % 2x1 case
for i = 1:2:length(rx_user_symbols)-1
rx_user_symbols_combined = [rx_user_symbols(i,1);conj(rx_user_symbols(i+1,1))];
H_est_user_combined = [H_est_user(i,1,1),-H_est_user(i,1,2);conj(H_est_user(i+1,1,2)),conj(H_est_user(i+1,1,1))]; % generate equivalent channel matrix
switch receiver
case 'SSD'
% ZF Detector
%%%%%%%%%%%%%%%%%%%
rx_user_symbols_combined_2 = pinv(H_est_user_combined)*rx_user_symbols_combined*sqrt(2); % calculate received symbols
rx_layer_x(1,(i+1)/2)=rx_user_symbols_combined_2(1,:); % map them to the corresponding layer
rx_layer_x(2,(i+1)/2)=rx_user_symbols_combined_2(2,:);
%%%%%%%%%%%%%%%%%%%
[Q,R]= qr(H_est_user_combined);
LLR_SD(:,(i+1)/2) = LTE_softsphere(rx_layer_x(:,(i+1)/2),rx_user_symbols_combined.'*sqrt(2),Q,R,symbol_alphabet,bittable,nLayers,M);
case 'SSDKB'
% ZF Detector
%%%%%%%%%%%%%%%%%%%
rx_user_symbols_combined_2 = pinv(H_est_user_combined)*rx_user_symbols_combined*sqrt(2); % calculate received symbols
rx_layer_x(1,(i+1)/2)=rx_user_symbols_combined_2(1,:); % map them to the corresponding layer
rx_layer_x(2,(i+1)/2)=rx_user_symbols_combined_2(2,:);
%%%%%%%%%%%%%%%%%%%
[Q,R]= qr(H_est_user_combined);
LLR_SD(:,(i+1)/2) = LTE_softsphere_kbest(rx_layer_x(:,(i+1)/2),rx_user_symbols_combined.'*sqrt(2),Q,R,symbol_alphabet,bittable,nLayers,M,receiver_k);
case 'ZF'
inv_temp = pinv(H_est_user_combined);
% ZF Detector
%%%%%%%%%%%%%%%%%%%
rx_user_symbols_combined_2 = inv_temp*rx_user_symbols_combined*sqrt(2); % calculate received symbols
rx_layer_x(1,(i+1)/2)=rx_user_symbols_combined_2(1,:); % map them to the corresponding layer
rx_layer_x(2,(i+1)/2)=rx_user_symbols_combined_2(2,:);
rx_layer_x_equalized((i+1)/2,1) = rx_user_symbols_combined_2(1,:);
rx_layer_x_equalized((i+1)/2,2) = rx_user_symbols_combined_2(2,:)';
%%%%%%%%%%%%%%%%%%%
Hg = inv_temp*H_est_user_combined;
noise_enhancement_tmp = sum(abs(inv_temp).^2,2);
noise_enhancement = [noise_enhancement_tmp(1)*ones(M(1),1);noise_enhancement_tmp(2)*ones(M(2),1)];
LLR_SD(:,(i+1)/2) = LTE_demapper(rx_layer_x(:,(i+1)/2),symbol_alphabet,bittable,nLayers,M,Hg,noise_enhancement);
case 'MMSE'
temp = H_est_user_combined'*H_est_user_combined;
inv_temp = (temp+sigma_n2*eye(size(temp)))^-1*H_est_user_combined';
% MMSE Detector
%%%%%%%%%%%%%%%%%%%
rx_user_symbols_combined_2 = inv_temp*rx_user_symbols_combined*sqrt(2); % calculate received symbols
rx_layer_x(1,(i+1)/2)=rx_user_symbols_combined_2(1,:); % map them to the corresponding layer
rx_layer_x(2,(i+1)/2)=rx_user_symbols_combined_2(2,:)';
rx_layer_x_equalized((i+1)/2,1) = rx_user_symbols_combined_2(1,:);
rx_layer_x_equalized((i+1)/2,2) = rx_user_symbols_combined_2(2,:);
%%%%%%%%%%%%%%%%%%%
Hg = inv_temp*H_est_user_combined;
noise_enhancement_tmp = sum(abs(inv_temp).^2,2);
noise_enhancement = [noise_enhancement_tmp(1)*ones(M(1),1);noise_enhancement_tmp(2)*ones(M(2),1)];
LLR_SD(:,(i+1)/2) = LTE_demapper(rx_layer_x(:,(i+1)/2),symbol_alphabet,bittable,nLayers,M,Hg,noise_enhancement);
end
end
else error('number of RX antennas not supported');
end
else
nLayers = 4;
M = [MCS_and_scheduling.CQI_params.modulation_order] * ones(1,nLayers); % Modulation order
rx_layer_x_equalized = zeros(length(rx_user_symbols)/4,nLayers);
bittable = false(sum(M(1:nLayers)),2^max(M));
symbol_alphabet = zeros(nLayers,2^max(M));
for i = 1:nLayers
bittable(sum(M(1:i-1))+(1:M(i)),1:2^M(i))=LTE_params.bittable{M(i)}; % Bitmapping table
symbol_alphabet(i,1:2^M(i))=LTE_params.SymbolAlphabet{M(i)}.'; % Symbol alphabet
end
symbol_alphabet(2,:) = conj(symbol_alphabet(2,:)); % this is because also the received symbols get conjugated
symbol_alphabet(4,:) = conj(symbol_alphabet(4,:)); % this is because also the received symbols get conjugated
LLR_SD = zeros(M(1)*nLayers,length(rx_user_symbols)/4); % Log likelihood Ratios of the Spere decoder
rx_layer_x = zeros(4,length(rx_user_symbols)/4); % initialization of variable for received layers
if (UE_nRX == 4) % 4x4 case
for i = 1:4:length(rx_user_symbols)-3
rx_user_symbols_combined = [rx_user_symbols(i,1);rx_user_symbols(i,2);conj(rx_user_symbols(i+1,1));conj(rx_user_symbols(i+1,2));
rx_user_symbols(i+2,1);rx_user_symbols(i+2,2);conj(rx_user_symbols(i+3,1));conj(rx_user_symbols(i+3,2));
rx_user_symbols(i,3);rx_user_symbols(i,4);conj(rx_user_symbols(i+1,3));conj(rx_user_symbols(i+1,4));
rx_user_symbols(i+2,3);rx_user_symbols(i+2,4);conj(rx_user_symbols(i+3,3));conj(rx_user_symbols(i+3,4))];
H_est_user_combined = [H_est_user(i,1,1),-H_est_user(i,1,3),0,0;H_est_user(i,2,1),-H_est_user(i,2,3),0,0;conj(H_est_user(i+1,1,3)),conj(H_est_user(i+1,1,1)),0,0;conj(H_est_user(i+1,2,3)),conj(H_est_user(i+1,2,1)),0,0;... % generate equivalent channel matrix
0,0,H_est_user(i+2,1,2),-H_est_user(i+2,1,4);0,0,H_est_user(i+2,2,2),-H_est_user(i+2,2,4);0,0,conj(H_est_user(i+3,1,4)),conj(H_est_user(i+3,1,2));0,0,conj(H_est_user(i+3,2,4)),conj(H_est_user(i+3,2,2));...
H_est_user(i,3,1),-H_est_user(i,3,3),0,0;H_est_user(i,4,1),-H_est_user(i,4,3),0,0;conj(H_est_user(i+1,3,3)),conj(H_est_user(i+1,3,1)),0,0;conj(H_est_user(i+1,4,3)),conj(H_est_user(i+1,4,1)),0,0;... % generate equivalent channel matrix
0,0,H_est_user(i+2,3,2),-H_est_user(i+2,3,4);0,0,H_est_user(i+2,4,2),-H_est_user(i+2,4,4);0,0,conj(H_est_user(i+3,3,4)),conj(H_est_user(i+3,3,2));0,0,conj(H_est_user(i+3,4,4)),conj(H_est_user(i+3,4,2))];
switch receiver
case 'SSD'
% ZF Detector
%%%%%%%%%%%%%%%%%%%
rx_user_symbols_combined_2(1:2) = pinv(H_est_user_combined([1:4,9:12],1:2))*rx_user_symbols_combined([1:4,9:12])*sqrt(2); % calculate received symbols
rx_user_symbols_combined_2(3:4) = pinv(H_est_user_combined([5:8,13:16],3:4))*rx_user_symbols_combined([5:8,13:16])*sqrt(2);
% rx_user_symbols_combined_2(5:6) = pinv(H_est_user_combined(9:12,1:2))*rx_user_symbols_combined(9:12)*sqrt(2); % calculate received symbols
% rx_user_symbols_combined_2(7:8) = pinv(H_est_user_combined(13:16,3:4))*rx_user_symbols_combined(13:16)*sqrt(2);
rx_layer_x(:,(i+3)/4)=rx_user_symbols_combined_2;
[Q,R]= qr(H_est_user_combined([1:4,9:12],1:2));
LLR_SD(1:sum(M(1:2)),(i+3)/4) = LTE_softsphere(rx_layer_x(1:2,(i+3)/4),rx_user_symbols_combined([1:4,9:12]).'*sqrt(2),Q,R,symbol_alphabet(1:2,:),bittable(1:sum(M(1:2)),:),nLayers/2,M(1:2));
[Q,R]= qr(H_est_user_combined([5:8,13:16],3:4));
LLR_SD(sum(M(1:2))+1:sum(M),(i+3)/4) = LTE_softsphere(rx_layer_x(3:4,(i+3)/4),rx_user_symbols_combined([5:8,13:16]).'*sqrt(2),Q,R,symbol_alphabet(3:4,:),bittable(1:sum(M(1:2)),:),nLayers/2,M(3:4));
case 'ZF'
inv_temp = pinv(H_est_user_combined);
% ZF Detector
%%%%%%%%%%%%%%%%%%%
rx_user_symbols_combined_2 = inv_temp*rx_user_symbols_combined*sqrt(2); % calculate received symbols
rx_layer_x(1,(i+3)/4)=rx_user_symbols_combined_2(1,:); % map them to the corresponding layer
rx_layer_x(2,(i+3)/4)=rx_user_symbols_combined_2(2,:);
rx_layer_x(3,(i+3)/4)=rx_user_symbols_combined_2(3,:);
rx_layer_x(4,(i+3)/4)=rx_user_symbols_combined_2(4,:);
%%%%%%%%%%%%%%%%%%%
rx_layer_x_equalized((i+3)/4,1) = rx_user_symbols_combined_2(1,:);
rx_layer_x_equalized((i+3)/4,2) = rx_user_symbols_combined_2(2,:)';
rx_layer_x_equalized((i+3)/4,3) = rx_user_symbols_combined_2(3,:);
rx_layer_x_equalized((i+3)/4,4) = rx_user_symbols_combined_2(4,:)';
Hg = inv_temp*H_est_user_combined;
noise_enhancement_tmp = sum(abs(inv_temp).^2,2);
noise_enhancement = [noise_enhancement_tmp(1)*ones(M(1),1);noise_enhancement_tmp(2)*ones(M(2),1);...
noise_enhancement_tmp(3)*ones(M(3),1);noise_enhancement_tmp(4)*ones(M(4),1)];
LLR_SD(:,(i+3)/4) = LTE_demapper(rx_layer_x(:,(i+3)/4),symbol_alphabet,bittable,nLayers,M,Hg,noise_enhancement);
case 'MMSE'
temp = H_est_user_combined'*H_est_user_combined;
inv_temp = (temp+sigma_n2*eye(size(temp)))^-1*H_est_user_combined';
% MMSE Detector
%%%%%%%%%%%%%%%%%%%
rx_user_symbols_combined_2 = inv_temp*rx_user_symbols_combined*sqrt(2); % calculate received symbols
rx_layer_x(1,(i+3)/4)=rx_user_symbols_combined_2(1,:); % map them to the corresponding layer
rx_layer_x(2,(i+3)/4)=rx_user_symbols_combined_2(2,:);
rx_layer_x(3,(i+3)/4)=rx_user_symbols_combined_2(3,:);
rx_layer_x(4,(i+3)/4)=rx_user_symbols_combined_2(4,:);
%%%%%%%%%%%%%%%%%%%
rx_layer_x_equalized((i+3)/4,1) = rx_user_symbols_combined_2(1,:);
rx_layer_x_equalized((i+3)/4,2) = rx_user_symbols_combined_2(2,:)';
rx_layer_x_equalized((i+3)/4,3) = rx_user_symbols_combined_2(3,:);
rx_layer_x_equalized((i+3)/4,4) = rx_user_symbols_combined_2(4,:)';
Hg = inv_temp*H_est_user_combined;
noise_enhancement_tmp = sum(abs(inv_temp).^2,2);
noise_enhancement = [noise_enhancement_tmp(1)*ones(M(1),1);noise_enhancement_tmp(2)*ones(M(2),1);...
noise_enhancement_tmp(3)*ones(M(3),1);noise_enhancement_tmp(4)*ones(M(4),1)];
LLR_SD(:,(i+3)/4) = LTE_demapper(rx_layer_x(:,(i+3)/4),symbol_alphabet,bittable,nLayers,M,Hg,noise_enhancement);
end
end
elseif (UE_nRX == 2) % 4x2 case
for i = 1:4:length(rx_user_symbols)-3
rx_user_symbols_combined = [rx_user_symbols(i,1);rx_user_symbols(i,2);conj(rx_user_symbols(i+1,1));conj(rx_user_symbols(i+1,2));
rx_user_symbols(i+2,1);rx_user_symbols(i+2,2);conj(rx_user_symbols(i+3,1));conj(rx_user_symbols(i+3,2))];
H_est_user_combined = [H_est_user(i,1,1),-H_est_user(i,1,3),0,0;H_est_user(i,2,1),-H_est_user(i,2,3),0,0;conj(H_est_user(i+1,1,3)),conj(H_est_user(i+1,1,1)),0,0;conj(H_est_user(i+1,2,3)),conj(H_est_user(i+1,2,1)),0,0;... % generate equivalent channel matrix
0,0,H_est_user(i+2,1,2),-H_est_user(i+2,1,4);0,0,H_est_user(i+2,2,2),-H_est_user(i+2,2,4);0,0,conj(H_est_user(i+3,1,4)),conj(H_est_user(i+3,1,2));0,0,conj(H_est_user(i+3,2,4)),conj(H_est_user(i+3,2,2))];
switch receiver
case 'SSD'
% ZF Detector
%%%%%%%%%%%%%%%%%%%
rx_user_symbols_combined_2(1:2) = pinv(H_est_user_combined(1:4,1:2))*rx_user_symbols_combined(1:4)*sqrt(2); % calculate received symbols
rx_user_symbols_combined_2(3:4) = pinv(H_est_user_combined(5:8,3:4))*rx_user_symbols_combined(5:8)*sqrt(2);
rx_layer_x(:,(i+3)/4)=rx_user_symbols_combined_2;
[Q,R]= qr(H_est_user_combined(1:4,1:2));
LLR_SD(1:sum(M(1:2)),(i+3)/4) = LTE_softsphere(rx_layer_x(1:2,(i+3)/4),rx_user_symbols_combined(1:4).'*sqrt(2),Q,R,symbol_alphabet(1:2,:),bittable(1:sum(M(1:2)),:),nLayers/2,M(1:2));
[Q,R]= qr(H_est_user_combined(5:8,3:4));
LLR_SD(sum(M(1:2))+1:sum(M),(i+3)/4) = LTE_softsphere(rx_layer_x(3:4,(i+3)/4),rx_user_symbols_combined(5:8).'*sqrt(2),Q,R,symbol_alphabet(3:4,:),bittable(1:sum(M(1:2)),:),nLayers/2,M(3:4));
case 'ZF'
inv_temp = pinv(H_est_user_combined);
% ZF Detector
%%%%%%%%%%%%%%%%%%%
rx_user_symbols_combined_2 = inv_temp*rx_user_symbols_combined*sqrt(2); % calculate received symbols
rx_layer_x(1,(i+3)/4)=rx_user_symbols_combined_2(1,:); % map them to the corresponding layer
rx_layer_x(2,(i+3)/4)=rx_user_symbols_combined_2(2,:);
rx_layer_x(3,(i+3)/4)=rx_user_symbols_combined_2(3,:);
rx_layer_x(4,(i+3)/4)=rx_user_symbols_combined_2(4,:);
%%%%%%%%%%%%%%%%%%%
rx_layer_x_equalized((i+3)/4,1) = rx_user_symbols_combined_2(1,:);
rx_layer_x_equalized((i+3)/4,2) = rx_user_symbols_combined_2(2,:)';
rx_layer_x_equalized((i+3)/4,3) = rx_user_symbols_combined_2(3,:);
rx_layer_x_equalized((i+3)/4,4) = rx_user_symbols_combined_2(4,:)';
Hg = inv_temp*H_est_user_combined;
noise_enhancement_tmp = sum(abs(inv_temp).^2,2);
noise_enhancement = [noise_enhancement_tmp(1)*ones(M(1),1);noise_enhancement_tmp(2)*ones(M(2),1);...
noise_enhancement_tmp(3)*ones(M(3),1);noise_enhancement_tmp(4)*ones(M(4),1)];
LLR_SD(:,(i+3)/4) = LTE_demapper(rx_layer_x(:,(i+3)/4),symbol_alphabet,bittable,nLayers,M,Hg,noise_enhancement);
case 'MMSE'
temp = H_est_user_combined'*H_est_user_combined;
inv_temp = (temp+sigma_n2*eye(size(temp)))^-1*H_est_user_combined';
% MMSE Detector
%%%%%%%%%%%%%%%%%%%
rx_user_symbols_combined_2 = inv_temp*rx_user_symbols_combined*sqrt(2); % calculate received symbols
rx_layer_x(1,(i+3)/4)=rx_user_symbols_combined_2(1,:); % map them to the corresponding layer
rx_layer_x(2,(i+3)/4)=rx_user_symbols_combined_2(2,:);
rx_layer_x(3,(i+3)/4)=rx_user_symbols_combined_2(3,:);
rx_layer_x(4,(i+3)/4)=rx_user_symbols_combined_2(4,:);
%%%%%%%%%%%%%%%%%%%
rx_layer_x_equalized((i+3)/4,1) = rx_user_symbols_combined_2(1,:);
rx_layer_x_equalized((i+3)/4,2) = rx_user_symbols_combined_2(2,:)';
rx_layer_x_equalized((i+3)/4,3) = rx_user_symbols_combined_2(3,:);
rx_layer_x_equalized((i+3)/4,4) = rx_user_symbols_combined_2(4,:)';
Hg = inv_temp*H_est_user_combined;
noise_enhancement_tmp = sum(abs(inv_temp).^2,2);
noise_enhancement = [noise_enhancement_tmp(1)*ones(M(1),1);noise_enhancement_tmp(2)*ones(M(2),1);...
noise_enhancement_tmp(3)*ones(M(3),1);noise_enhancement_tmp(4)*ones(M(4),1)];
LLR_SD(:,(i+3)/4) = LTE_demapper(rx_layer_x(:,(i+3)/4),symbol_alphabet,bittable,nLayers,M,Hg,noise_enhancement);
end
end
elseif (UE_nRX == 1) % 4x1 case
for i = 1:4:length(rx_user_symbols)-3
rx_user_symbols_combined = [rx_user_symbols(i,1);conj(rx_user_symbols(i+1,1));rx_user_symbols(i+2,1);conj(rx_user_symbols(i+3,1))]; % generate equivalent channel matrix
H_est_user_combined = [H_est_user(i,1,1),-H_est_user(i,1,3),0,0;conj(H_est_user(i+1,1,3)),conj(H_est_user(i+1,1,1)),0,0;...
0,0,H_est_user(i+2,1,2),-H_est_user(i+2,1,4);0,0,conj(H_est_user(i+3,1,4)),conj(H_est_user(i+3,1,2))];
switch receiver
case 'SSD'
% ZF Detector
%%%%%%%%%%%%%%%%%%%
rx_user_symbols_combined_2(1:2) = pinv(H_est_user_combined(1:2,1:2))*rx_user_symbols_combined(1:2)*sqrt(2); % calculate received symbols
rx_user_symbols_combined_2(3:4) = pinv(H_est_user_combined(3:4,3:4))*rx_user_symbols_combined(3:4)*sqrt(2);
rx_layer_x(:,(i+3)/4)=rx_user_symbols_combined_2;
%%%%%%%%%%%%%%%%%%%
[Q,R]= qr(H_est_user_combined(1:2,1:2));
LLR_SD(1:sum(M(1:2)),(i+3)/4) = LTE_softsphere(rx_layer_x(1:2,(i+3)/4),rx_user_symbols_combined(1:2).'*sqrt(2),Q,R,symbol_alphabet(1:2,:),bittable(1:sum(M(1:2)),:),nLayers/2,M(1:2));
[Q,R]= qr(H_est_user_combined(3:4,3:4));
LLR_SD(sum(M(1:2))+1:sum(M),(i+3)/4) = LTE_softsphere(rx_layer_x(3:4,(i+3)/4),rx_user_symbols_combined(3:4).'*sqrt(2),Q,R,symbol_alphabet(3:4,:),bittable(1:sum(M(1:2)),:),nLayers/2,M(3:4));
case 'ZF'
inv_temp = pinv(H_est_user_combined);
% ZF Detector
%%%%%%%%%%%%%%%%%%%
rx_user_symbols_combined_2 = inv_temp*rx_user_symbols_combined*sqrt(2); % calculate received symbols
rx_layer_x(1,(i+3)/4)=rx_user_symbols_combined_2(1,:); % map them to the corresponding layer
rx_layer_x(2,(i+3)/4)=rx_user_symbols_combined_2(2,:);
rx_layer_x(3,(i+3)/4)=rx_user_symbols_combined_2(3,:);
rx_layer_x(4,(i+3)/4)=rx_user_symbols_combined_2(4,:);
%%%%%%%%%%%%%%%%%%%
rx_layer_x_equalized((i+3)/4,1) = rx_user_symbols_combined_2(1,:);
rx_layer_x_equalized((i+3)/4,2) = rx_user_symbols_combined_2(2,:)';
rx_layer_x_equalized((i+3)/4,3) = rx_user_symbols_combined_2(3,:);
rx_layer_x_equalized((i+3)/4,4) = rx_user_symbols_combined_2(4,:)';
Hg = inv_temp*H_est_user_combined;
noise_enhancement_tmp = sum(abs(inv_temp).^2,2);
noise_enhancement = [noise_enhancement_tmp(1)*ones(M(1),1);noise_enhancement_tmp(2)*ones(M(2),1);...
noise_enhancement_tmp(3)*ones(M(3),1);noise_enhancement_tmp(4)*ones(M(4),1)];
LLR_SD(:,(i+3)/4) = LTE_demapper(rx_layer_x(:,(i+3)/4),symbol_alphabet,bittable,nLayers,M,Hg,noise_enhancement);
case 'MMSE'
temp = H_est_user_combined'*H_est_user_combined;
inv_temp = (temp+sigma_n2*eye(size(temp)))^-1*H_est_user_combined';
% MMSE Detector
%%%%%%%%%%%%%%%%%%%
rx_user_symbols_combined_2 = inv_temp*rx_user_symbols_combined*sqrt(2); % calculate received symbols
rx_layer_x(1,(i+3)/4)=rx_user_symbols_combined_2(1,:); % map them to the corresponding layer
rx_layer_x(2,(i+3)/4)=rx_user_symbols_combined_2(2,:);
rx_layer_x(3,(i+3)/4)=rx_user_symbols_combined_2(3,:);
rx_layer_x(4,(i+3)/4)=rx_user_symbols_combined_2(4,:);
%%%%%%%%%%%%%%%%%%%
rx_layer_x_equalized((i+3)/4,1) = rx_user_symbols_combined_2(1,:);
rx_layer_x_equalized((i+3)/4,2) = rx_user_symbols_combined_2(2,:)';
rx_layer_x_equalized((i+3)/4,3) = rx_user_symbols_combined_2(3,:);
rx_layer_x_equalized((i+3)/4,4) = rx_user_symbols_combined_2(4,:)';
Hg = inv_temp*H_est_user_combined;
noise_enhancement_tmp = sum(abs(inv_temp).^2,2);
noise_enhancement = [noise_enhancement_tmp(1)*ones(M(1),1);noise_enhancement_tmp(2)*ones(M(2),1);...
noise_enhancement_tmp(3)*ones(M(3),1);noise_enhancement_tmp(4)*ones(M(4),1)];
LLR_SD(:,(i+3)/4) = LTE_demapper(rx_layer_x(:,(i+3)/4),symbol_alphabet,bittable,nLayers,M,Hg,noise_enhancement);
end
end
else error('number of RX antennas not supported');
end
end