www.gusucode.com > LTE仿真Matlab源码 > LTE_feedback_OLSM.m
% function CQI = LTE_feedback_OLSM(sigma_n2,channel,UE,LTE_params)
% author Stefan Schwarz
% contact stefan.schwarz@nt.tuwien.ac.at
% calculates the CQI feedback for OLSM
% this function assumes that the channel handed over already incorporates
% the precoders --> feedback delay 0 is not supported (at least the precoder is not incorporated)!
% also the CQI feedback has a granularity of 1 value for the whole number
% of resources that the UE is mapped to
% channel prediction is not supported
% for i = 1:size(channel,1)
% H_t = reshape(channel(i,:,:),size(channel,2),size(channel,3));
% MSE_mean = mean(mean(UE.MSE));
% switch LTE_params.UE_config.receiver
% case 'ZF'
% F = pinv(H_t); % ZF receiver
% case 'MMSE'
% temp = H_t'*H_t;
% F = (temp+sigma_n2*eye(size(temp)))^-1*H_t'; % MMSE receiver
% otherwise
% temp = H_t'*H_t;
% F = (temp+sigma_n2*eye(size(temp)))^-1*H_t'; % MMSE receiver
% end
% K = F*H_t;
% SNR(:,i) = abs(diag(K)).^2./(sum(abs(K-diag(diag(K))).^2,2)+(sigma_n2+MSE_mean).*sum(abs(F).^2,2));
% end
% for i = 1:size(SNR,1)
% CQIs = (0:15);
% SINReff = UE.SINR_averager.average(SNR(i,:),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(:,:,i) = CQI_temp*ones(LTE_params.Nrb,2);
% end
function [rank_i,CQI] = LTE_feedback_OLSM(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!
H = reshape(mean(mean(H_est_complete,1),2),size(H_est_complete,3),size(H_est_complete,4));
max_rank = min(size(H));
CQI = zeros(LTE_params.Nrb,2,min(2,max_rank));
CQI_temp = zeros(LTE_params.Nrb,2,max_rank,min(2,max_rank));
% 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(max_rank,RB_max,2); % total sum rate over all resource blocks
SNR_g = zeros(max_rank,RB_max,2,4);
else
RB_max = LTE_params.Ntot;
I_g = zeros(max_rank,RB_max,2); % total sum rate over all resource blocks
SNR_g = zeros(max_rank,RB_max,2,4);
end
% figure(1)
% clf
if (nAtPort == 2)
c_i = 0;
else
c_i = [12,13,14,15];
end
pick = round(rand);
if LTE_params.UE_config.CQI_fb || LTE_params.UE_config.RIandPMI_fb
for RB_i = 1:RB_max
pick = pick+1;
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,:,:);
if UE.RIandPMI_fb % wheter RI and PMI feedback is activated
rank_loop = 1:max_rank;
else % iterate only over the actual RI value if RI feedback is deactivated
rank_loop = LTE_params.scheduler.nLayers(uu);
end
% rank_loop = 4;
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(max_rank,1);
SNR = zeros(max(rank_loop),max(rank_loop));
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(3,nAtPort,c_i,rr,LTE_params);
if (nAtPort == 2)
% pick = round(rand);
pick = mod(pick,2);
WDU = W*D.^(1+pick)*U;
else
pick = 1:(12*7-4)*LTE_params.Nrb;
k = mod(floor((pick-1)/rr),4)+1;
p = mod(pick-1,rr)+1;
period = lcm(seqperiod(k),seqperiod(p));
WDU = W(:,:,k(mod(RB_i-1,period)+1))*D^(p(mod(RB_i-1,period)+1))*U;
end
P = H_t*WDU;
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(rr,1:rr) = 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(1:max(rank_loop),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(I_ges,[],1);
rank_i = I1; % 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(rank_i,:,:,(i2-1)*2+1:i2*2));
elseif rank_i == 3 && i2 == 2
AWGN_SNR = squeeze(SNR_g(rank_i,:,:,i2:rank_i));
else
AWGN_SNR = squeeze(SNR_g(rank_i,:,:,i2));
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(:,:,i2) = CQI_temp*ones(LTE_params.Nrb,2);
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(rank_i,rb_ii,slot_ii,i2));
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,i2) = CQI_temp;
end
end
end
end
else
CQI = [];
end
if ~UE.RIandPMI_fb
rank_i = [];
end
else
CQI = [];
rank_i = [];
end
% PMI