www.gusucode.com > LTE仿真Matlab源码 > LTE_feedback_TxD.m
function [CQI] = LTE_feedback_TxD(nAtPort,sigma_n2,LTE_params,channel,UE,uu)
% author Stefan Schwarz
% contact stefan.schwarz@nt.tuwien.ac.at
% calculates the PMI, RI and CQI feedback
%% channel prediction
% save channel matrix for channel prediction
UE.previous_channels = circshift(UE.previous_channels,[0,0,-1,0,0]);
UE.previous_channels(:,:,end,:,:)=channel(:,:,:,:);
H_est_complete = LTE_channel_predictor(UE.previous_channels,LTE_params.uplink_delay,LTE_params.ChanMod_config.filtering,UE.predict);
%% some initializations
% rank_i = min(size(H_est_complete,3),size(H_est_complete,4)); % NOTE: remove when rank_i feedback is supported!
rank_loop = LTE_params.scheduler.nLayers(uu);
H = reshape(mean(mean(H_est_complete,1),2),size(H_est_complete,3),size(H_est_complete,4));
CQI = zeros(LTE_params.Nrb,2,rank_loop);
CQI_temp = zeros(LTE_params.Nrb,2,rank_loop);
% if nAtPort == 2
% i_max = [3,2];
% else
% i_max = [15,15,15,15];
% end
if LTE_params.feedback.channel_averaging % use channel averaging
RB_max = LTE_params.Nrb;
I_g = zeros(RB_max,2); % total sum rate over all resource blocks
SNR_g = zeros(RB_max,2,4);
else
RB_max = LTE_params.Ntot;
I_g = zeros(RB_max,2); % total sum rate over all resource blocks
SNR_g = zeros(RB_max,2,4);
end
% figure(1)
% clf
for RB_i = 1:RB_max
for slot_i = 1:2
if LTE_params.feedback.channel_averaging
freq_band = (RB_i-1)*LTE_params.Nsc+1:min(RB_i*LTE_params.Nsc,size(H_est_complete,1));
else
freq_band = RB_i;
end
H_est = H_est_complete(freq_band,(slot_i-1)*LTE_params.Ns+1:slot_i*LTE_params.Ns,:,:);
H_t = reshape(mean(mean(H_est,1),2),size(H_est,3),size(H_est,4)); % Channel of current RB and slot
if ~LTE_params.feedback.ignore_channel_estimation % channel estimation error will be ignored if set so
MSE_mean = mean(UE.MSE(:,freq_band),2); % Channel estimator MSE
else
MSE_mean = zeros(size(UE.MSE,1),1);
end
% I = zeros(1,1);
SNR = zeros(max(rank_loop),1);
for rr = rank_loop % Iterate over all possible layer numbers, to find the one that delivers the maximum sum rate
% if rr == 2 && nAtPort == 2
% i_start = 1;
% i_stop = i_max(rr);
% else
% i_start = 0;
% i_stop = i_max(rr);
% end
% for i = i_start:i_stop
% [Z W U D] = LTE_common_get_precoding_matrix(2,nAtPort,0,rr,LTE_params);
% P = H_t*WDU;
switch size(H,1)
case 1
switch size(H,2)
case 2
P = [H_t(1,1),-H_t(1,2);conj(H_t(1,2)),conj(H_t(1,1))];
case 4
P = [H_t(1,1),-H_t(1,3),0,0;conj(H_t(1,3)),conj(H_t(1,1)),0,0;...
0,0,H_t(1,2),-H_t(1,4);0,0,conj(H_t(1,4)),conj(H_t(1,2))];
otherwise
error('not implemented')
end
case 2
switch size(H,2)
case 2
P = [H_t(1,1),-H_t(1,2);H_t(2,1),-H_t(2,2);conj(H_t(1,2)),conj(H_t(1,1));conj(H_t(2,2)),conj(H_t(2,1))];
case 4
P = [H_t(1,1),-H_t(1,3),0,0;H_t(2,1),-H_t(2,3),0,0;conj(H_t(1,3)),conj(H_t(1,1)),0,0;conj(H_t(2,3)),conj(H_t(2,1)),0,0;... % generate equivalent channel matrix
0,0,H_t(1,2),-H_t(1,4);0,0,H_t(2,2),-H_t(2,4);0,0,conj(H_t(1,4)),conj(H_t(1,2));0,0,conj(H_t(2,4)),conj(H_t(2,2))];
otherwise
error('not implemented')
end
case 4
switch size(H,2)
case 4
% P = [H_t(1,1),-H_t(1,3),0,0;H_t(2,1),-H_t(2,3),0,0;conj(H_t(1,3)),conj(H_t(1,1)),0,0;conj(H_t(2,3)),conj(H_t(2,1)),0,0;... % generate equivalent channel matrix
% 0,0,H_t(1,2),-H_t(1,4);0,0,H_t(2,2),-H_t(2,4);0,0,conj(H_t(1,4)),conj(H_t(1,2));0,0,conj(H_t(2,4)),conj(H_t(2,2));...
% H_t(3,1),-H_t(3,3),0,0;H_t(4,1),-H_t(4,3),0,0;conj(H_t(3,3)),conj(H_t(3,1)),0,0;conj(H_t(4,3)),conj(H_t(4,1)),0,0;... % generate equivalent channel matrix
% 0,0,H_t(3,2),-H_t(3,4);0,0,H_t(4,2),-H_t(4,4);0,0,conj(H_t(3,4)),conj(H_t(3,2));0,0,conj(H_t(4,4)),conj(H_t(4,2))];
P = [H_t(1,1),-H_t(1,3),0,0;H_t(2,1),-H_t(2,3),0,0;H_t(3,1),-H_t(3,3),0,0;H_t(4,1),-H_t(4,3),0,0;conj(H_t(1,3)),conj(H_t(1,1)),0,0;conj(H_t(2,3)),conj(H_t(2,1)),0,0;conj(H_t(3,3)),conj(H_t(3,1)),0,0;conj(H_t(4,3)),conj(H_t(4,1)),0,0;... % generate equivalent channel matrix
0,0,H_t(1,2),-H_t(1,4);0,0,H_t(2,2),-H_t(2,4);0,0,H_t(3,2),-H_t(3,4);0,0,H_t(4,2),-H_t(4,4);0,0,conj(H_t(1,4)),conj(H_t(1,2));0,0,conj(H_t(2,4)),conj(H_t(2,2));0,0,conj(H_t(3,4)),conj(H_t(3,2));0,0,conj(H_t(4,4)),conj(H_t(4,2))];
otherwise
error('not implemented')
end
otherwise
error('not implemented')
end
P = P*1/sqrt(2);
switch LTE_params.UE_config.receiver
% switch 'ZF'
case 'ZF'
F = pinv(P); % ZF receiver
case 'MMSE'
temp = P'*P;
F = (temp+sigma_n2*eye(size(temp)))^-1*P'; % MMSE receiver
% case 'SSD'
% Jr = real(H_t*W);
% Ji = imag(H_t*W);
% J = [Jr(1,1),-Ji(1,1),Jr(1,2),-Ji(1,2);Ji(1,1),Jr(1,1),Ji(1,2),Jr(1,2);Jr(2,1),-Ji(2,1),Jr(2,2),-Ji(2,2);Ji(2,1),Jr(2,1),Ji(2,2),Jr(2,2)]; % Lattice generator
% % calculate error covariance matrix, assuming AWGN
% E(:,:,i) = (J'*J)^-1;
% F = eye(size(P,1));
otherwise
temp = P'*P;
F = (temp+sigma_n2*eye(size(temp)))^-1*P'; % MMSE receiver
end
K = F*P;
SNR(:) = abs(diag(K)).^2./(sum(abs(K-diag(diag(K))).^2,2)+(sigma_n2+MSE_mean(1:rr)).*sum(abs(F).^2,2));
% I(i+1,rr) = sum(log2(1+SNR(i+1,rr,:))); % rate of one resource block for different precoders and ranks
% I(rr) = LTE_feedback_getBICM(LTE_params,squeeze(SNR(rr,:)));
% end
end
% I_g(RB_i,slot_i) = I_g(RB_i,slot_i) + I;
SNR = 10*log10(SNR);
SNR(isnan(SNR))= -inf;
SNR_g(RB_i,slot_i,1:max(rank_loop)) = SNR;
% if UE.PMI_fb_gran == 1
% [~,C1] = max(I,[],1);
% PMI_temp(:,RB_i,slot_i) = C1;
% end
end
end
% I_ges = sum(sum(I_g,2),3);
% [~,I1] = max(max(I_ges,[],1));
rank_i = rank_loop; % choose rank indicator to maximize mutual information
if LTE_params.UE_config.CQI_fb % wheter CQI feedback is used
% for i2 = 1:min(2,rank_i) % iterate over the number of streams
if UE.CQI_fb_gran ~= 1 % single CQI value for whole bandwidth
% if rank_i == 4
% AWGN_SNR = squeeze(SNR_g(:,:,(i2-1)*2+1:i2*2));
% elseif rank_i == 3 && i2 == 2
% AWGN_SNR = squeeze(SNR_g(:,:,i2:rank_i));
% else
AWGN_SNR = squeeze(SNR_g(:,:,1:rank_i));
% end
CQIs = (0:15);
% SINReff = UE.SINR_averager.average(10.^(AWGN_SNR(:)/10),CQIs,[LTE_params.CQI_params(CQIs+1).modulation_order]);
SINReff = UE.SINR_averager.average(10.^(AWGN_SNR(:)/10),CQIs,[LTE_params.CQI_params(20).modulation_order,LTE_params.CQI_params(CQIs(2:end)).modulation_order]);
CQI_temp = LTE_common_CQI_mapping_table(LTE_params.CQI_mapping,SINReff,CQIs+1);
CQI(:,:,:) = CQI_temp*ones(LTE_params.Nrb,2,rank_loop);
else % single CQI value for every resource block
for RB_ii = 1:LTE_params.Nrb
if LTE_params.feedback.channel_averaging
rb_ii = RB_ii;
else
rb_ii = (RB_ii-1)*LTE_params.Nsc+1:RB_ii*LTE_params.Nsc;
end
for slot_ii = 1:2
% if rank_i == 4
% AWGN_SNR = squeeze(SNR_g(i2,rb_ii,slot_ii,(i2-1)*2+1:min(i2*2,rank_i)));
% elseif rank_i == 3 && i2 == 2
% AWGN_SNR = squeeze(SNR_g(rank_i,rb_ii,slot_ii,i2:rank_i));
% else
AWGN_SNR = squeeze(SNR_g(rb_ii,slot_ii,1:rank_i));
% end
CQIs = (0:15);
SINReff = UE.SINR_averager.average(10.^(AWGN_SNR(:)/10),CQIs,[LTE_params.CQI_params(20).modulation_order,LTE_params.CQI_params(CQIs(2:end)).modulation_order]);
CQI_temp = LTE_common_CQI_mapping_table(LTE_params.CQI_mapping,SINReff,CQIs+1);
CQI(RB_ii,slot_ii,:) = CQI_temp*ones(1,1,rank_loop);
end
end
end
% end
else
CQI = [];
end