Fixed bug in LS linear interpolation. Removed pilot averaging. Added SNR estimation through PSS.

matlab/tests/equalizer_test.m

@@ -6,30 +6,35 @@ clear
 
 plot_noise_estimation_only=false;
 
-SNR_values_db=10;%linspace(0,30,8);
-Nrealizations=1 ;
+SNR_values_db=linspace(0,30,7);
+Nrealizations=4;
 
-preEVM = zeros(length(SNR_values_db),Nrealizations);
-postEVM_mmse = zeros(length(SNR_values_db),Nrealizations);
-postEVM_mmse_lin = zeros(length(SNR_values_db),Nrealizations);
-postEVM_srslte = zeros(length(SNR_values_db),Nrealizations);
+Lp=10;
         
+N=512;
+K=300;
+rstart=(N-K)/2;
+P=K/6;
+Rhphp=zeros(P,P);
+Rhhp=zeros(K,P);
+Rhh=zeros(K,K);
 
-enb.NDLRB = 6;                 % Number of resource blocks
+enb.NDLRB = 25;                 % Number of resource blocks
 enb.CellRefP = 1;               % One transmit antenna port
 enb.NCellID = 0;                % Cell ID
 enb.CyclicPrefix = 'Normal';    % Normal cyclic prefix
 enb.DuplexMode = 'FDD';         % FDD
 
 %% Channel Model Configuration
-rng(1);         % Configure random number generators
+cfg.Seed = 0;                  % Random channel seed
+cfg.InitTime = 0;
+cfg.NRxAnts = 1;               % 1 receive antenna
+cfg.DelayProfile = 'EVA';     
 
-cfg.Seed = 2;                  % Random channel seed
-cfg.NRxAnts = 2;               % 1 receive antenna
-cfg.DelayProfile = 'EVA';      % EVA delay spread
-cfg.DopplerFreq = 120;         % 120Hz Doppler frequency
+% doppler 5, 70 300
+
+cfg.DopplerFreq = 200;          % 120Hz Doppler frequency
 cfg.MIMOCorrelation = 'Low';   % Low (no) MIMO correlation
-cfg.InitTime = 0;              % Initialize at time zero
 cfg.NTerms = 16;               % Oscillators used in fading model
 cfg.ModelType = 'GMEDS';       % Rayleigh fading model type
 cfg.InitPhase = 'Random';      % Random initial phases
@@ -42,25 +47,42 @@ cec.PilotAverage = 'UserDefined';    % Type of pilot symbol averaging
 cec.FreqWindow = 9;                 % Frequency window size
 cec.TimeWindow = 9;                 % Time window size
 cec.InterpType = 'Linear';            % 2D interpolation type
-cec.InterpWindow = 'Centered';       % Interpolation window type
+cec.InterpWindow = 'Causal';       % Interpolation window type
 cec.InterpWinSize = 1;               % Interpolation window size
 
 %% Subframe Resource Grid Size
 
 gridsize = lteDLResourceGridSize(enb);
-K = gridsize(1);    % Number of subcarriers
+Ks = gridsize(1);    % Number of subcarriers
 L = gridsize(2);    % Number of OFDM symbols in one subframe
-P = gridsize(3);    % Number of transmit antenna ports
+Ports = gridsize(3);    % Number of transmit antenna ports
+
+%% Allocate memory
+Ntests=5;
+hest=cell(1,Ntests);
+for i=1:Ntests
+    hest{i}=zeros(K,140);
+end
+hls=zeros(4,4*P*10);
+MSE=zeros(Ntests,Nrealizations,length(SNR_values_db));
+noiseEst=zeros(Ntests,Nrealizations,length(SNR_values_db));
+
+legends={'matlab','ls.linear','mmse','r.mmse','r.mmse2'};
+colors={'bo-','rx-','m*-','k+-','c+-'};
+colors2={'b-','r-','m-','k-','c-'};
+
+addpath('../../build/srslte/lib/ch_estimation/test')
+
+offset=-1;
 
 for nreal=1:Nrealizations
 %% Transmit Resource Grid
 txGrid = [];
-RSRP = [];
 
 %% Payload Data Generation
 % Number of bits needed is size of resource grid (K*L*P) * number of bits
 % per symbol (2 for QPSK)
-numberOfBits = K*L*P*2; 
+numberOfBits = Ks*L*Ports*2; 
 
 % Create random bit stream
 inputBits = randi([0 1], numberOfBits, 1); 
@@ -104,7 +126,7 @@ for sf = 0:10
       
 end
 
-txGrid([1:5 68:72],6:7) = zeros(10,2);
+txGrid([1:5 68:72],6:7) = ones(10,2);
 
 %% OFDM Modulation
 
@@ -112,19 +134,16 @@ txGrid([1:5 68:72],6:7) = zeros(10,2);
 txGrid = txGrid(:,1:140);
 
 %% SNR Configuration
-
 for snr_idx=1:length(SNR_values_db)
 SNRdB = SNR_values_db(snr_idx);             % Desired SNR in dB
 SNR = 10^(SNRdB/20);    % Linear SNR  
 
+fprintf('SNR=%.1f dB\n',SNRdB)
 
 %% Fading Channel
 
 cfg.SamplingRate = info.SamplingRate;
-
-% Pass data through the fading channel model
-%rxWaveform = lteFadingChannel(cfg,txWaveform);
-rxWaveform = txWaveform; 
+[rxWaveform, chinfo] = lteFadingChannel(cfg,txWaveform);
 
 %% Additive Noise
 
@@ -134,91 +153,229 @@ N0 = 1/(sqrt(2.0*enb.CellRefP*double(info.Nfft))*SNR);
 % Create additive white Gaussian noise
 noise = N0*complex(randn(size(rxWaveform)),randn(size(rxWaveform)));   
 
-noiseTx(snr_idx) = N0; 
 % Add noise to the received time domain waveform
+rxWaveform_nonoise = rxWaveform;
 rxWaveform = rxWaveform + noise;
 
 %% Synchronization
 
+if (offset==-1) 
     offset = lteDLFrameOffset(enb,rxWaveform);
-rxWaveform = rxWaveform(1+offset+2:end,:);
+end
+
+rxWaveform = rxWaveform(1+offset:end,:);
+rxWaveform_nonoise = rxWaveform_nonoise(1+offset:end,:);
 
 %% OFDM Demodulation
 rxGrid = lteOFDMDemodulate(enb,rxWaveform);
 rxGrid = rxGrid(:,1:140);
 
-addpath('../../build/srslte/lib/ch_estimation/test')
+rxGrid_nonoise = lteOFDMDemodulate(enb,rxWaveform_nonoise);
+rxGrid_nonoise = rxGrid_nonoise(:,1:140);
 
-%% Channel Estimation
-[estChannel, noiseEst(snr_idx)] = lteDLChannelEstimate(enb,cec,rxGrid);
-output=[];
-snrest_srslte = zeros(10,1);
-noise_srslte = zeros(10,1);
-rsrp = zeros(1,10);
-
-[d, ~, out] = srslte_chest(enb.NCellID,enb.CellRefP,rxGrid);
-output = [output out];
-%RSRP = [RSRP rsrp];
-%meanRSRP(snr_idx)=mean(rsrp);
-%SNR_srslte(snr_idx)=mean(snrest_srslte);
-%noiseEst_srslte(snr_idx)=mean(noise_srslte);
-d=reshape(d, size(estChannel));
-plot(1:288,real(reshape(estChannel(:,11:14),1,[])),'b-',...
-     1:288,real(reshape(d(:,11:14),1,[])),'r-')
-
-% if ~plot_noise_estimation_only
-% 
-% %% MMSE Equalization
-%     eqGrid_mmse = lteEqualizeMMSE(rxGrid, estChannel, noiseEst(snr_idx));
-% 
-%     eqGrid_srslte = reshape(output,size(eqGrid_mmse));
-% 
-%     % Analysis
-% 
-%     %Compute EVM across all input values EVM of pre-equalized receive signal
-%     preEqualisedEVM = lteEVM(txGrid,rxGrid);
-%     fprintf('%d-%d: Pre-EQ: %0.3f%%\n', ...
-%             snr_idx,nreal,preEqualisedEVM.RMS*100); 
-% 
-% 
-%     %EVM of post-equalized receive signal
-%      postEqualisedEVM_mmse = lteEVM(txGrid,reshape(eqGrid_mmse,size(txGrid)));
-%      fprintf('%d-%d: MMSE: %0.3f%%\n', ...
-%              snr_idx,nreal,postEqualisedEVM_mmse.RMS*100); 
-% 
-%     postEqualisedEVM_srslte = lteEVM(txGrid,reshape(eqGrid_srslte,size(txGrid)));
-%     fprintf('%d-%d: srslte: %0.3f%%\n', ...
-%             snr_idx,nreal,postEqualisedEVM_srslte.RMS*100); 
-% 
-%     preEVM(snr_idx,nreal) = preEqualisedEVM.RMS;
-%     postEVM_mmse(snr_idx,nreal) = mean([postEqualisedEVM_mmse.RMS]);
-%     postEVM_srslte(snr_idx,nreal) = mean([postEqualisedEVM_srslte.RMS]);
+% True channel
+h=rxGrid_nonoise./(txGrid);
+
+
+%% Channel Estimation with Matlab
+tmpnoise=zeros(10,1);
+for i=1:10
+    enb.NSubframe=i-1;
+    [hest{1}(:,(1:14)+(i-1)*14), tmpnoise(i), hls(:,(1:4*P)+(i-1)*4*P)] = ...
+                    lteDLChannelEstimate2(enb,cec,rxGrid(:,(i-1)*14+1:i*14));
+end
+noiseEst(1,nreal,snr_idx)=mean(tmpnoise)*sqrt(2)*enb.CellRefP;
+
+%% LS-Linear estimation with srsLTE
+[tmp, ~, ~, noiseEst(2,nreal,snr_idx)] = srslte_chest(enb.NCellID,enb.CellRefP,rxGrid);
+hest{2}=reshape(tmp, size(hest{1}));
+
+tmp_noise=zeros(2,1);
+for sf=[0 5]
+    enb.NSubframe=sf;
+    pssSym = ltePSS(enb);
+    pssInd = ltePSSIndices(enb);
+    x=reshape(rxGrid(pssInd),[],1);
+    hh=reshape(hest{2}(pssInd),[],1);
+    y=hh.*pssSym;
+    tmp_noise(sf/5+1)=mean(abs(x-y).^2);
+end
+% noiseEst(2,nreal,snr_idx)=mean(tmp_noise);
+
+%% MMSE estimation with srsLTE 
+
+% Compute Correlation matrices
+M=40;
+a=0.1;
+hidx=zeros(M,1);
+for i=1:M
+    if (mod(i,2)==1)
+        hx=floor((i-1)/2)*7+1;
+    else
+        hx=floor((i-1)/2)*7+5;
+    end
+    hidx(i)=hx;
+    hp=hest{1}(hls(1,(1:P)+P*(i-1)),hx);
+    Rhphp = (1-a)*Rhphp+a*(hp*hp');
+    Rhhp = (1-a)*Rhhp+a*(hest{1}(:,hx)*hp');  
+    Rhh = (1-a)*Rhh+a*h(:,hx)*h(:,hx)';
+end
+snr_lin=10^(SNR_values_db(snr_idx)/10);
+Wi=((Rhphp+(1/snr_lin)*eye(P)))^-1;
+W = Rhhp*Wi;
+
+% for i=1:length(hidx)
+%     hp=hls(3,(1:P)+P*(i-1));
+%     hest{3}(:,hidx(i))=W*transpose(hp);
 % end
+
+w=reshape(transpose(W),1,[]);
+[tmp, ~, ~, noiseEst(3,nreal,snr_idx)] = srslte_chest(enb.NCellID,enb.CellRefP,rxGrid,w);
+hest{3}=reshape(tmp, size(hest{1}));
+
+
+%% Robust MMSE estimation using srsLTE (Eurecom paper)
+t=0:Lp-1;
+alfa=log(2*Lp)/Lp;
+c_l=exp(-t*alfa);
+c_l=c_l/sum(c_l);
+C_l=diag(1./c_l);
+prows=rstart+(1:6:K);
+
+F=dftmtx(N);
+F_p=F(prows,1:Lp);
+F_l=F((rstart+1):(K+rstart),1:Lp);
+Wi=(F_p'*F_p+C_l/snr_lin)^(-1);
+W2=F_l*Wi*F_p';
+
+% for i=1:length(hidx)
+%    hp=hls(3,(1:P)+P*(i-1));
+%    hest{4}(:,hidx(i))=W2*transpose(hp);
+% end
+
+w2=reshape(transpose(W2),1,[]);
+[tmp, ~, ~, noiseEst(4,nreal,snr_idx)] = srslte_chest(enb.NCellID,enb.CellRefP,rxGrid,w2);
+hest{4}=reshape(tmp, size(hest{1}));
+
+
+
+%% Another robust method from Infocom research paper
+ 
+c_l=ones(Lp,1)/Lp;
+c_l2=[c_l; zeros(N-Lp,1)];
+C_l=diag(c_l2);
+F=dftmtx(N);
+R_hh=F*C_l*F';
+R_hphp=R_hh(prows,prows);
+R_hhp=R_hh((rstart+1):(K+rstart),prows);
+W3=R_hhp*(R_hphp+(1/snr_lin)*eye(P))^-1;
+
+% for i=1:length(hidx)
+%     hp=hls(3,(1:P)+P*(i-1));
+%     hest{5}(:,hidx(i))=W3*transpose(hp);    
+% end
+
+w3=reshape(transpose(W3),1,[]);
+[tmp, ~, ~, noiseEst(5,nreal,snr_idx)] = srslte_chest(enb.NCellID,enb.CellRefP,rxGrid,w3);
+hest{5}=reshape(tmp, size(hest{1}));
+
+
+
+%% Compute MSE 
+for i=1:Ntests
+    MSE(i,nreal,snr_idx)=mean(mean(abs(h(:,:)-hest{i}(:,:)).^2));
+    fprintf('MSE test %d: %f\n',i, 10*log10(MSE(i,nreal,snr_idx)));
 end
+
+%% Plot a single realization
+if (length(SNR_values_db) == 1)
+    subplot(1,2,1)
+    sym=1;
+    ref_idx=1:P;
+    ref_idx_x=[1:6:K];% (292:6:360)-216];% 577:6:648];
+    n=1:(K*length(sym));
+    for i=1:Ntests
+        plot(n,abs(reshape(hest{i}(:,sym),1,[])),colors2{i});
+        hold on;
     end
+    plot(ref_idx_x,abs(hls(3,ref_idx)),'ro');
+    hold off;
+    tmp=cell(Ntests+1,1);
+    for i=1:Ntests
+        tmp{i}=legends{i};
+    end
+    tmp{Ntests+1}='LS';
+    legend(tmp)
+
+    xlabel('SNR (dB)')
+    ylabel('Channel Gain')
+    grid on;
+    
+    u(1+ceil(chinfo.PathSampleDelays))=chinfo.PathGains(1,:);
+    
+    subplot(1,2,2)
+    plot(1:P,real(W(150,:)),1:P,real(W2(150,:)),1:P,real(W3(150,:)))
+    legend('mmse','robust1','robust2')
+    grid on
+    
+    fprintf('Mean MMSE Robust %.2f dB\n', 10*log10(MSE(4,nreal,snr_idx)))
+    fprintf('Mean MMSE matlab %.2f dB\n', 10*log10(MSE(1,nreal,snr_idx)))
+
+%     u=zeros(N,1);
+%     u(1+ceil(chinfo.PathSampleDelays))=mean(chinfo.PathGains(7680+(1:512+40),:));
 %     
-% % subplot(1,2,1)
-% 
-% if ~plot_noise_estimation_only
-%     plot(SNR_values_db, mean(preEVM,2), ...
-%         SNR_values_db, mean(postEVM_mmse,2), ...
-%         SNR_values_db, mean(postEVM_srslte,2))
-%     legend('No Eq','MMSE-lin','MMSE-srslte')
-%     grid on
-% end
+%     subplot(2,2,1)
+%     plot(1:length(u),abs(u))
 %     
-% % subplot(1,2,2)
-% if plot_noise_estimation_only
-%     SNR_matlab = 1./(noiseEst*sqrt(2.0)*enb.CellRefP);
+%     subplot(2,2,2)
+%     plot(abs(fftshift(fft(u,N))))
 %     
-%     subplot(1,3,1)
-%     plot(SNR_values_db, SNR_values_db, SNR_values_db, 10*log10(SNR_srslte),SNR_values_db, 10*log10(SNR_matlab))
-%     legend('Theory','srsLTE','Matlab')
+%     subplot(2,2,3)
+%     hf=[zeros((N-K)/2,1); h(1:K/2,1); 0; h(K/2+1:end,1); zeros((N-K)/2-1,1)];
+%     plot(1:Lp,real(ifft(ifftshift(h(:,1)),Lp)))
 %     
-%     subplot(1,3,2)
-%     plot(SNR_values_db, 10*log10(noiseTx), SNR_values_db, 10*log10(noiseEst_srslte),SNR_values_db, 10*log10(noiseEst))
-%     legend('Theory','srsLTE','Matlab')
+%     subplot(2,2,4)
+%     plot(abs(hf))
 %     
-%     subplot(1,3,3)
-%     plot(1:10*length(SNR_values_db),RSRP,10*(1:length(SNR_values_db)),meanRSRP)
-% end
+end
+
+end
+end
+
+
+%% Compute average MSE and noise estimation
+mean_mse=mean(MSE,2);
+mean_snr=10*log10(1./mean(noiseEst,2));
+
+
+%% Plot average over all SNR values
+if (length(SNR_values_db) > 1)
+    subplot(1,2,1)
+    for i=1:Ntests
+        plot(SNR_values_db, 10*log10(mean_mse(i,:)),colors{i})
+        hold on;
+    end
+    hold off;
+    legend(legends);
+    grid on
+    xlabel('SNR (dB)')
+    ylabel('MSE (dB)')
+    
+    subplot(1,2,2)
+    plot(SNR_values_db, SNR_values_db,'k:')
+    hold on;
+    for i=1:Ntests
+        plot(SNR_values_db, mean_snr(i,:), colors{i})
+    end
+    hold off
+    tmp=cell(Ntests+1,1);
+    tmp{1}='Theory';
+    for i=2:Ntests+1
+        tmp{i}=legends{i-1};
+    end
+    legend(tmp)
+    grid on
+    xlabel('SNR (dB)')
+    ylabel('Estimated SNR (dB)')
+end
+

matlab/tests/pdsch_bler.m

@@ -6,11 +6,11 @@
 
 recordedSignal=[];
 
-Npackets = 5;
-SNR_values = linspace(18,25,5);
+Npackets = 30;
+SNR_values = linspace(9,24,5);
 
 %% Choose RMC 
-[waveform,rgrid,rmccFgOut] = lteRMCDLTool('R.9',[1;0;0;1]);
+[waveform,rgrid,rmccFgOut] = lteRMCDLTool('R.0',[1;0;0;1]);
 waveform = sum(waveform,2);
 
 if ~isempty(recordedSignal)
@@ -28,13 +28,13 @@ end
 
 flen=rmccFgOut.SamplingRate/1000;
     
-Nsf = 10; 
+Nsf = 9; 
 
 %% Setup Fading channel model 
-cfg.Seed = 8;                  % Random channel seed
+cfg.Seed = 0;                  % Random channel seed
 cfg.NRxAnts = 1;               % 1 receive antenna
-cfg.DelayProfile = 'EVA';      % EVA delay spread
-cfg.DopplerFreq = 5;           % 120Hz Doppler frequency
+cfg.DelayProfile = 'EPA';      % EVA delay spread
+cfg.DopplerFreq = 120;           % 120Hz Doppler frequency
 cfg.MIMOCorrelation = 'Low';   % Low (no) MIMO correlation
 cfg.InitTime = 0;              % Initialize at time zero
 cfg.NTerms = 16;               % Oscillators used in fading model
@@ -49,7 +49,7 @@ cec.PilotAverage = 'UserDefined';     % Type of pilot averaging
 cec.FreqWindow = 9;                   % Frequency window size
 cec.TimeWindow = 9;                   % Time window size
 cec.InterpType = 'linear';             % 2D interpolation type
-cec.InterpWindow = 'Centered';        % Interpolation window type
+cec.InterpWindow = 'Causal';        % Interpolation window type
 cec.InterpWinSize = 1;                % Interpolation window size
 
 addpath('../../build/srslte/lib/phch/test')
@@ -61,6 +61,10 @@ for snr_idx=1:length(SNR_values)
     SNRdB = SNR_values(snr_idx);
     SNR = 10^(SNRdB/10);    % Linear SNR  
     N0  = 1/(sqrt(2.0*rmccFgOut.CellRefP*double(rmccFgOut.Nfft))*SNR);
+    
+    Rhphp=zeros(30,30);
+    Rhhp=zeros(180,30);
+
     for i=1:Npackets
 
         if isempty(recordedSignal)
@@ -86,7 +90,7 @@ for snr_idx=1:length(SNR_values)
             rmccFgOut.TotSubframes=1;
 
             % Perform channel estimation
-            [hest, nest] = lteDLChannelEstimate(rmccFgOut, cec, subframe_rx);
+            [hest, nest,estimates] = lteDLChannelEstimate2(rmccFgOut, cec, subframe_rx);
 
             [cws,symbols] = ltePDSCHDecode(rmccFgOut,rmccFgOut.PDSCH,subframe_rx,hest,nest);
             [trblkout,blkcrc,dstate] = lteDLSCHDecode(rmccFgOut,rmccFgOut.PDSCH, ... 
@@ -99,7 +103,7 @@ for snr_idx=1:length(SNR_values)
             if (rmccFgOut.PDSCH.TrBlkSizes(sf_idx+1) > 0)
                 [dec2, data, pdschRx, pdschSymbols2, cws2] = srslte_pdsch(rmccFgOut, rmccFgOut.PDSCH, ... 
                                                         rmccFgOut.PDSCH.TrBlkSizes(sf_idx+1), ...
-                                                        subframe_rx, hest, nest);
+                                                        subframe_rx);
             else
                 dec2 = 1;
             end
@@ -117,8 +121,8 @@ for snr_idx=1:length(SNR_values)
 end
 
 if (length(SNR_values)>1)
-    semilogy(SNR_values,1-decoded/Npackets/(Nsf+1),'bo-',...
-             SNR_values,1-decoded_srslte/Npackets/(Nsf+1), 'ro-')
+    semilogy(SNR_values,1-decoded/Npackets/(Nsf),'bo-',...
+             SNR_values,1-decoded_srslte/Npackets/(Nsf), 'ro-')
     grid on;
     legend('Matlab','srsLTE')
     xlabel('SNR (dB)')

srslte/examples/pdsch_ue.c

@@ -519,9 +519,9 @@ int main(int argc, char **argv) {
                         
             nof_trials++; 
             
-            rsrq = SRSLTE_VEC_EMA(srslte_chest_dl_get_rsrq(&ue_dl.chest), rsrq, 0.05);
-            rsrp = SRSLTE_VEC_EMA(srslte_chest_dl_get_rsrp(&ue_dl.chest), rsrp, 0.05);      
-            noise = SRSLTE_VEC_EMA(srslte_chest_dl_get_noise_estimate(&ue_dl.chest), noise, 0.05);      
+            rsrq = SRSLTE_VEC_EMA(srslte_chest_dl_get_rsrq(&ue_dl.chest), rsrq, 0.1);
+            rsrp = SRSLTE_VEC_EMA(srslte_chest_dl_get_rsrp(&ue_dl.chest), rsrp, 0.1);      
+            noise = SRSLTE_VEC_EMA(srslte_chest_dl_get_noise_estimate(&ue_dl.chest), noise, 0.1);      
             nframes++;
             if (isnan(rsrq)) {
               rsrq = 0; 
@@ -545,7 +545,7 @@ int main(int argc, char **argv) {
                    "PDCCH-Miss: %5.2f%%, PDSCH-BLER: %5.2f%%\r",
                    
                   srslte_ue_sync_get_cfo(&ue_sync)/1000,
-                  10*log10(srslte_chest_dl_get_snr(&ue_dl.chest)), 
+                  10*log10(rsrp/noise), 
                   100*(1-(float) ue_dl.nof_detected/nof_trials), 
                   (float) 100*ue_dl.pkt_errors/ue_dl.pkts_total);                            
           }

srslte/include/srslte/ch_estimation/chest_dl.h

@@ -48,6 +48,7 @@
 #include "srslte/resampling/interp.h"
 #include "srslte/ch_estimation/refsignal_dl.h"
 #include "srslte/common/phy_common.h"
+#include "srslte/sync/pss.h"
 
 #define SRSLTE_CHEST_MAX_FILTER_FREQ_LEN    21
 #define SRSLTE_CHEST_MAX_FILTER_TIME_LEN    40
@@ -55,19 +56,10 @@
 typedef struct {
   srslte_cell_t cell; 
   srslte_refsignal_cs_t csr_signal;
-  cf_t *pilot_estimates[SRSLTE_MAX_PORTS];
-  cf_t *pilot_estimates_average[SRSLTE_MAX_PORTS];
-  cf_t *pilot_recv_signal[SRSLTE_MAX_PORTS];
- 
-  uint32_t filter_freq_len;
-  float filter_freq[SRSLTE_CHEST_MAX_FILTER_FREQ_LEN];
-  uint32_t filter_time_len;
-  float filter_time[SRSLTE_CHEST_MAX_FILTER_TIME_LEN];
-  
+  cf_t *pilot_estimates;
+  cf_t *pilot_recv_signal; 
   cf_t *tmp_noise; 
-  cf_t *tmp_freqavg;
-  cf_t *tmp_timeavg[SRSLTE_CHEST_MAX_FILTER_TIME_LEN];
-  cf_t *tmp_timeavg_mult; 
+  cf_t *w_filter; 
 
   srslte_interp_linsrslte_vec_t srslte_interp_linvec; 
   srslte_interp_lin_t srslte_interp_lin; 
@@ -75,7 +67,11 @@ typedef struct {
   float rssi[SRSLTE_MAX_PORTS]; 
   float rsrp[SRSLTE_MAX_PORTS]; 
   float noise_estimate[SRSLTE_MAX_PORTS];
-  float filter_time_ema;
+  
+  /* Use PSS for noise estimation in LS linear interpolation mode */
+  cf_t pss_signal[SRSLTE_PSS_LEN];
+  cf_t tmp_pss[SRSLTE_PSS_LEN];
+  cf_t tmp_pss_noisy[SRSLTE_PSS_LEN];
 } srslte_chest_dl_t;
 
 
@@ -84,16 +80,8 @@ SRSLTE_API int srslte_chest_dl_init(srslte_chest_dl_t *q,
 
 SRSLTE_API void srslte_chest_dl_free(srslte_chest_dl_t *q); 
 
-SRSLTE_API int srslte_chest_dl_set_filter_freq(srslte_chest_dl_t *q, 
-                                               float *filter, 
-                                               uint32_t filter_len);
-
-SRSLTE_API int srslte_chest_dl_set_filter_time(srslte_chest_dl_t *q, 
-                                               float *filter, 
-                                               uint32_t filter_len);
-
-SRSLTE_API void srslte_chest_dl_set_filter_time_ema(srslte_chest_dl_t *q, 
-                                                    float ema_coefficient); 
+SRSLTE_API void srslte_chest_dl_set_filter_w(srslte_chest_dl_t *q, 
+                                             cf_t *w); 
 
 SRSLTE_API int srslte_chest_dl_estimate(srslte_chest_dl_t *q, 
                                         cf_t *input,

srslte/include/srslte/resampling/interp.h

@@ -80,7 +80,12 @@ SRSLTE_API void srslte_interp_linear_vector(srslte_interp_linsrslte_vec_t *q,
                                             cf_t *between, 
                                             uint32_t M); 
 
-
+SRSLTE_API void srslte_interp_linear_vector2(srslte_interp_linsrslte_vec_t *q, 
+                                            cf_t *in0, 
+                                            cf_t *in1, 
+                                            cf_t *start, 
+                                            cf_t *between, 
+                                            uint32_t M); 
 
 /* Interpolation within a vector */
 

srslte/include/srslte/sync/pss.h

@@ -112,6 +112,11 @@ SRSLTE_API void srslte_pss_synch_reset(srslte_pss_synch_t *q);
 SRSLTE_API int srslte_pss_generate(cf_t *signal, 
                                    uint32_t N_id_2);
 
+SRSLTE_API void srslte_pss_get_slot(cf_t *slot, 
+                                    cf_t *pss_signal, 
+                                    uint32_t nof_prb, 
+                                    srslte_cp_t cp); 
+
 SRSLTE_API void srslte_pss_put_slot(cf_t *pss_signal, 
                                     cf_t *slot, 
                                     uint32_t nof_prb, 

srslte/lib/ch_estimation/src/chest_dl.c

@@ -39,32 +39,7 @@
 #include "srslte/utils/vector.h"
 #include "srslte/utils/convolution.h"
 
-#define NOISE_POWER_METHOD 1 // 0: Difference between noisy received and noiseless; 1: power of empty subcarriers
-
-#define DEFAULT_FILTER_FREQ_LEN 11   // Must be odd
-#define DEFAULT_FILTER_TIME_LEN 3
-
-static void init_default_filters(srslte_chest_dl_t *q) {
-  
-  float f[DEFAULT_FILTER_FREQ_LEN];
-  float t[DEFAULT_FILTER_TIME_LEN];
-  
-  for (int i=0;i<DEFAULT_FILTER_FREQ_LEN/2+1;i++) {
-    f[i] = 1+i; 
-    f[DEFAULT_FILTER_FREQ_LEN-i-1] = 1+i;
-  }
-  float norm = srslte_vec_acc_ff(f, DEFAULT_FILTER_FREQ_LEN);
-  srslte_vec_sc_prod_fff(f, 1.0/norm, f, DEFAULT_FILTER_FREQ_LEN);
-  srslte_chest_dl_set_filter_freq(q, f, DEFAULT_FILTER_FREQ_LEN);
-
-  for (int i=0;i<DEFAULT_FILTER_TIME_LEN/2+1;i++) {
-    t[i] = 1+i; 
-    t[DEFAULT_FILTER_TIME_LEN-i-1] = 1+i;
-  }
-  norm = srslte_vec_acc_ff(t, DEFAULT_FILTER_TIME_LEN);
-  srslte_vec_sc_prod_fff(t, 1.0/norm, t, DEFAULT_FILTER_TIME_LEN);
-  srslte_chest_dl_set_filter_time(q, t, DEFAULT_FILTER_TIME_LEN);  
-}
+#define ESTIMATE_NOISE_LS_PSS
 
 /** 3GPP LTE Downlink channel estimator and equalizer. 
  * Estimates the channel in the resource elements transmitting references and interpolates for the rest
@@ -89,34 +64,21 @@ int srslte_chest_dl_init(srslte_chest_dl_t *q, srslte_cell_t cell)
       goto clean_exit;
     }
     
-    q->tmp_freqavg = srslte_vec_malloc(sizeof(cf_t) * SRSLTE_SF_LEN_RE(cell.nof_prb, cell.cp));
-    if (!q->tmp_freqavg) {
-      perror("malloc");
-      goto clean_exit;
-    }
-    q->tmp_noise = srslte_vec_malloc(sizeof(cf_t) * SRSLTE_SF_LEN_RE(cell.nof_prb, cell.cp));
+    q->tmp_noise = srslte_vec_malloc(sizeof(cf_t) * SRSLTE_REFSIGNAL_MAX_NUM_SF(cell.nof_prb));
     if (!q->tmp_noise) {
       perror("malloc");
       goto clean_exit;
     }
-    q->tmp_timeavg_mult = srslte_vec_malloc(sizeof(cf_t) * 12*cell.nof_prb);
-    if (!q->tmp_timeavg_mult) {
+    q->pilot_estimates = srslte_vec_malloc(sizeof(cf_t) * SRSLTE_REFSIGNAL_MAX_NUM_SF(cell.nof_prb));
+    if (!q->pilot_estimates) {
       perror("malloc");
       goto clean_exit;
     }      
-    
-    for (int i=0;i<cell.nof_ports;i++) {
-      q->pilot_estimates[i] = srslte_vec_malloc(2*sizeof(cf_t) * SRSLTE_REFSIGNAL_NUM_SF(cell.nof_prb, i));
-      if (!q->pilot_estimates[i]) {
+    q->pilot_recv_signal = srslte_vec_malloc(sizeof(cf_t) * SRSLTE_REFSIGNAL_MAX_NUM_SF(cell.nof_prb));
+    if (!q->pilot_recv_signal) {
       perror("malloc");
       goto clean_exit;
     }
-      q->pilot_recv_signal[i] = srslte_vec_malloc(sizeof(cf_t) * SRSLTE_REFSIGNAL_NUM_SF(cell.nof_prb, i));
-      if (!q->pilot_recv_signal[i]) {
-        perror("malloc");
-        goto clean_exit;
-      }
-    }
     
     if (srslte_interp_linear_vector_init(&q->srslte_interp_linvec, SRSLTE_NRE*cell.nof_prb)) {
       fprintf(stderr, "Error initializing vector interpolator\n");
@@ -128,7 +90,13 @@ int srslte_chest_dl_init(srslte_chest_dl_t *q, srslte_cell_t cell)
       goto clean_exit; 
     }
     
-    init_default_filters(q);
+    if (srslte_pss_generate(q->pss_signal, cell.id%3)) {
+      fprintf(stderr, "Error initializing PSS signal for noise estimation\n");
+      goto clean_exit;
+    }
+    
+    q->w_filter = NULL; 
+    
     q->cell = cell; 
   }
   
@@ -145,72 +113,63 @@ void srslte_chest_dl_free(srslte_chest_dl_t *q)
 {
   srslte_refsignal_cs_free(&q->csr_signal);
 
-  if (q->tmp_freqavg) {
-    free(q->tmp_freqavg);
-  }
   if (q->tmp_noise) {
     free(q->tmp_noise);
   }
-  if (q->tmp_timeavg_mult) {
-    free(q->tmp_timeavg_mult);
-  }
   srslte_interp_linear_vector_free(&q->srslte_interp_linvec);
   srslte_interp_linear_free(&q->srslte_interp_lin);
   
-  for (int i=0;i<SRSLTE_MAX_PORTS;i++) {
-    if (q->pilot_estimates[i]) {
-      free(q->pilot_estimates[i]);
-    }      
-    if (q->pilot_recv_signal[i]) {
-      free(q->pilot_recv_signal[i]);
+  if (q->pilot_estimates) {
+    free(q->pilot_estimates);
   }      
+  if (q->pilot_recv_signal) {
+    free(q->pilot_recv_signal);
   }
   bzero(q, sizeof(srslte_chest_dl_t));
 }
 
-int srslte_chest_dl_set_filter_freq(srslte_chest_dl_t *q, float *filter, uint32_t filter_len) {
-  if (filter_len <= SRSLTE_CHEST_MAX_FILTER_FREQ_LEN) {
-    q->filter_freq_len = filter_len; 
-    for (int i=0;i<filter_len;i++) {
-      q->filter_freq[i] = filter[i];
-    }
-    return SRSLTE_SUCCESS;
-  } else {
-    return SRSLTE_ERROR;
-  }
+void srslte_chest_dl_set_filter_w(srslte_chest_dl_t *q, cf_t *w) {
+  q->w_filter = w; 
 }
 
-void srslte_chest_dl_set_filter_time_ema(srslte_chest_dl_t *q, float ema_coefficient) {
-  q->filter_time_ema = ema_coefficient;  
-}
+/* Uses the difference between the averaged and non-averaged pilot estimates */
+static float estimate_noise_pilots(srslte_chest_dl_t *q, cf_t *ce, uint32_t port_id) 
+{
+  int nref=SRSLTE_REFSIGNAL_NUM_SF(q->cell.nof_prb, port_id);
+  /* Get averaged pilots from channel estimates */
+  srslte_refsignal_cs_get_sf(q->cell, port_id, ce, q->tmp_noise);
+  /* Substract noisy pilot estimates */
+  srslte_vec_sub_ccc(q->tmp_noise, q->pilot_estimates, q->tmp_noise, nref);  
+  /* Compute average power */
+  float power = sqrt(2.0)*q->cell.nof_ports*srslte_vec_avg_power_cf(q->tmp_noise, nref);
+  return power; 
+}
+
+#ifdef ESTIMATE_NOISE_LS_PSS
+static float estimate_noise_pss(srslte_chest_dl_t *q, cf_t *input, cf_t *ce) 
+{
+  /* Get PSS from received signal */
+  srslte_pss_get_slot(input, q->tmp_pss, q->cell.nof_prb, q->cell.cp);
     
-int srslte_chest_dl_set_filter_time(srslte_chest_dl_t *q, float *filter, uint32_t filter_len) {
-  if (filter_len <= SRSLTE_CHEST_MAX_FILTER_TIME_LEN) {
-    q->filter_time_len = filter_len; 
-    for (int i=0;i<filter_len;i++) {
-      q->filter_time[i] = filter[i];
-    }    
-    return SRSLTE_SUCCESS;
-  } else {
-    return SRSLTE_ERROR;
-  }  
-}
+  /* Get channel estimates for PSS position */
+  srslte_pss_get_slot(ce, q->tmp_pss_noisy, q->cell.nof_prb, q->cell.cp);
 
+  /* Multiply known PSS by channel estimates */
+  srslte_vec_prod_ccc(q->tmp_pss_noisy, q->pss_signal, q->tmp_pss_noisy, SRSLTE_PSS_LEN);
 
+  /* Substract received signal */
+  srslte_vec_sub_ccc(q->tmp_pss_noisy, q->tmp_pss, q->tmp_pss_noisy, SRSLTE_PSS_LEN);
   
-#if NOISE_POWER_METHOD==0
-/* Uses the difference between the averaged and non-averaged pilot estimates */
-static float estimate_noise_port(srslte_chest_dl_t *q, cf_t *average, cf_t *ce, uint32_t len) {
-  /* Use difference between averaged and noisy LS pilot estimates */
-  srslte_vec_sub_ccc(average, ce, q->tmp_noise, len);
-  return srslte_vec_avg_power_cf(q->tmp_noise, len);
+  /* Compute average power */
+  float power = q->cell.nof_ports*srslte_vec_avg_power_cf(q->tmp_pss_noisy, SRSLTE_PSS_LEN)/sqrt(2);
+  return power; 
 }
-#endif
 
-#if NOISE_POWER_METHOD==1
+
+#else 
 
 /* Uses the 5 empty transmitted SC before and after the SSS and PSS sequences for noise estimation */
-static float estimate_noise_port(srslte_chest_dl_t *q, cf_t *input) {
+static float estimate_noise_empty_sc(srslte_chest_dl_t *q, cf_t *input) {
   int k_sss = (SRSLTE_CP_NSYMB(q->cell.cp) - 2) * q->cell.nof_prb * SRSLTE_NRE + q->cell.nof_prb * SRSLTE_NRE / 2 - 31;
   float noise_power = 0; 
   noise_power += srslte_vec_avg_power_cf(&input[k_sss-5], 5); // 5 empty SC before SSS
@@ -224,50 +183,47 @@ static float estimate_noise_port(srslte_chest_dl_t *q, cf_t *input) {
 #endif
 
 
-static void average_estimates(srslte_chest_dl_t *q, cf_t *ce, uint32_t port_id) 
+#define cesymb(i) ce[SRSLTE_RE_IDX(q->cell.nof_prb,i,0)]
+
+static void interpolate_filter_pilots(srslte_chest_dl_t *q, cf_t *pilot_estimates, cf_t *w, cf_t *ce, uint32_t port_id) 
 {
-  int nref=12*q->cell.nof_prb;
-  uint32_t l, i;
-
-  /* For each symbol with pilots in a slot */
-  for (l=0;l<SRSLTE_CP_NSYMB(q->cell.cp);l++) {
-    if (q->filter_freq_len > 0) {
-      /* Filter pilot estimates in frequency */
-      srslte_conv_same_cf(&ce[l*12*q->cell.nof_prb], q->filter_freq, &q->tmp_freqavg[l*12*q->cell.nof_prb], nref, q->filter_freq_len);                        
-    } else {
-      memcpy(&q->tmp_freqavg[l*12*q->cell.nof_prb], &ce[l*12*q->cell.nof_prb], nref * sizeof(cf_t));
+  int nsymbols = srslte_refsignal_cs_nof_symbols(port_id); 
+  int nsc=SRSLTE_NRE*q->cell.nof_prb;
+  int nref=2*q->cell.nof_prb;
+  
+  // Interpolation filter in frequency domain
+  for (uint32_t s=0;s<nsymbols;s++) {
+    for (int i=0;i<nsc;i++) {         
+      uint32_t sym_idx=srslte_refsignal_cs_nsymbol(s,q->cell.cp, port_id);
+      ce[nsc*sym_idx+i] = srslte_vec_dot_prod_ccc(&pilot_estimates[s*nref], &w[i*nref], nref);  
     }
   }
-
-  #if NOISE_POWER_METHOD==0
-  q->noise_estimate[port_id] = estimate_noise_port(q, q->tmp_freqavg, ce, 
-                                                   SRSLTE_SF_LEN_RE(q->cell.nof_prb, q->cell.cp));
-  #endif
-  
-  /* Filter with FIR or don't filter */ 
-  for (l=0;l<SRSLTE_CP_NSYMB(q->cell.cp);l++) {
-    /* Filter in time domain. */
-    if (q->filter_time_len > 0) {
-      /* Multiply symbols by filter and add them  */
-      bzero(&ce[l*12*q->cell.nof_prb], nref * sizeof(cf_t));
-      for (i=0;i<q->filter_time_len;i++) {
-        if (l+i-q->filter_time_len/2 < SRSLTE_CP_NSYMB(q->cell.cp) && l+i-q->filter_time_len/2 > 0) {
-          srslte_vec_sc_prod_cfc(&q->tmp_freqavg[(l+i-q->filter_time_len/2)*12*q->cell.nof_prb], q->filter_time[i], q->tmp_timeavg_mult, nref);
-          srslte_vec_sum_ccc(q->tmp_timeavg_mult, &ce[l*12*q->cell.nof_prb], &ce[l*12*q->cell.nof_prb], nref);            
+  /* Now interpolate in the time domain between symbols */
+  if (SRSLTE_CP_ISNORM(q->cell.cp)) {
+    if (nsymbols == 4) {
+      srslte_interp_linear_vector(&q->srslte_interp_linvec, &cesymb(0), &cesymb(4),  &cesymb(1),  3);
+      srslte_interp_linear_vector(&q->srslte_interp_linvec, &cesymb(4), &cesymb(7),  &cesymb(5),  2);
+      srslte_interp_linear_vector(&q->srslte_interp_linvec, &cesymb(7), &cesymb(11), &cesymb(8),  3);
+      srslte_interp_linear_vector2(&q->srslte_interp_linvec, &cesymb(7), &cesymb(11), &cesymb(11), &cesymb(12), 2);
     } else {
-          srslte_vec_sc_prod_cfc(&q->tmp_freqavg[l*12*q->cell.nof_prb], q->filter_time[i], q->tmp_timeavg_mult, nref);
-          srslte_vec_sum_ccc(q->tmp_timeavg_mult, &ce[l*12*q->cell.nof_prb], &ce[l*12*q->cell.nof_prb], nref);            
-        }
+      srslte_interp_linear_vector(&q->srslte_interp_linvec, &cesymb(8), &cesymb(1), &cesymb(0), 1);
+      srslte_interp_linear_vector(&q->srslte_interp_linvec, &cesymb(1), &cesymb(8), &cesymb(2), 6);
+      srslte_interp_linear_vector(&q->srslte_interp_linvec, &cesymb(1), &cesymb(8), &cesymb(9), 5);
     }    
   } else {
-      memcpy(&ce[l*12*q->cell.nof_prb], &q->tmp_freqavg[l*12*q->cell.nof_prb], nref * sizeof(cf_t));        
+    if (nsymbols == 4) {
+      srslte_interp_linear_vector(&q->srslte_interp_linvec, &cesymb(0), &cesymb(3), &cesymb(1), 2);
+      srslte_interp_linear_vector(&q->srslte_interp_linvec, &cesymb(3), &cesymb(6), &cesymb(4), 2);
+      srslte_interp_linear_vector(&q->srslte_interp_linvec, &cesymb(6), &cesymb(9), &cesymb(7), 2);
+      srslte_interp_linear_vector(&q->srslte_interp_linvec, &cesymb(6), &cesymb(9), &cesymb(9), 2);
+    } else {
+      srslte_interp_linear_vector(&q->srslte_interp_linvec, &cesymb(7), &cesymb(1), &cesymb(0), 1);
+      srslte_interp_linear_vector(&q->srslte_interp_linvec, &cesymb(1), &cesymb(7), &cesymb(2), 5);
+      srslte_interp_linear_vector(&q->srslte_interp_linvec, &cesymb(1), &cesymb(7), &cesymb(8), 4);
     }    
   }
 }
 
-
-#define cesymb(i) ce[SRSLTE_RE_IDX(q->cell.nof_prb,i,0)]
-
 static void interpolate_pilots(srslte_chest_dl_t *q, cf_t *pilot_estimates, cf_t *ce, uint32_t port_id) 
 {
   /* interpolate the symbols with references in the freq domain */
@@ -288,7 +244,7 @@ static void interpolate_pilots(srslte_chest_dl_t *q, cf_t *pilot_estimates, cf_t
       srslte_interp_linear_vector(&q->srslte_interp_linvec, &cesymb(0), &cesymb(4),  &cesymb(1),  3);
       srslte_interp_linear_vector(&q->srslte_interp_linvec, &cesymb(4), &cesymb(7),  &cesymb(5),  2);
       srslte_interp_linear_vector(&q->srslte_interp_linvec, &cesymb(7), &cesymb(11), &cesymb(8),  3);
-      srslte_interp_linear_vector(&q->srslte_interp_linvec, &cesymb(7), &cesymb(11), &cesymb(12), 2);
+      srslte_interp_linear_vector2(&q->srslte_interp_linvec, &cesymb(7), &cesymb(11), &cesymb(11), &cesymb(12), 2);
     } else {
       srslte_interp_linear_vector(&q->srslte_interp_linvec, &cesymb(8), &cesymb(1), &cesymb(0), 1);
       srslte_interp_linear_vector(&q->srslte_interp_linvec, &cesymb(1), &cesymb(8), &cesymb(2), 6);
@@ -320,43 +276,40 @@ float srslte_chest_dl_rssi(srslte_chest_dl_t *q, cf_t *input, uint32_t port_id)
   return rssi/nsymbols; 
 }
 
-#define RSRP_FROM_ESTIMATES
-
-float srslte_chest_dl_rsrp(srslte_chest_dl_t *q, uint32_t port_id) {
-#ifdef RSRP_FROM_ESTIMATES
-  return srslte_vec_avg_power_cf(q->pilot_estimates[port_id], 
-                          SRSLTE_REFSIGNAL_NUM_SF(q->cell.nof_prb, port_id));
-#else
-  return srslte_vec_avg_power_cf(q->pilot_estimates_average[port_id], 
-                          SRSLTE_REFSIGNAL_NUM_SF(q->cell.nof_prb, port_id));
-#endif
-}
-
 int srslte_chest_dl_estimate_port(srslte_chest_dl_t *q, cf_t *input, cf_t *ce, uint32_t sf_idx, uint32_t port_id) 
 {
   /* Get references from the input signal */
-  srslte_refsignal_cs_get_sf(q->cell, port_id, input, q->pilot_recv_signal[port_id]);
+  srslte_refsignal_cs_get_sf(q->cell, port_id, input, q->pilot_recv_signal);
   
   /* Use the known CSR signal to compute Least-squares estimates */
-  srslte_vec_prod_conj_ccc(q->pilot_recv_signal[port_id], q->csr_signal.pilots[port_id/2][sf_idx], 
-              q->pilot_estimates[port_id], SRSLTE_REFSIGNAL_NUM_SF(q->cell.nof_prb, port_id)); 
-
+  srslte_vec_prod_conj_ccc(q->pilot_recv_signal, q->csr_signal.pilots[port_id/2][sf_idx], 
+              q->pilot_estimates, SRSLTE_REFSIGNAL_NUM_SF(q->cell.nof_prb, port_id)); 
   if (ce != NULL) {
-    /* Interpolate to create channel estimates for all resource grid */
-    interpolate_pilots(q, q->pilot_estimates[port_id], ce, port_id);    
+    /* TESTING: Use robust MMSE interpolation filter */
+    if (q->w_filter) {
+      interpolate_filter_pilots(q, q->pilot_estimates, q->w_filter, ce, port_id);
 
-    /* Average channel estimates */
-    average_estimates(q, ce, port_id);
+      /* Estimate noise from difference from averaged and estimated pilots */
+      if (sf_idx == 0 || sf_idx == 5) {
+        q->noise_estimate[port_id] = estimate_noise_pilots(q, ce, port_id);
       }      
+    /* If w filter not defined, resort to LS estimate + linear interpolation */
+    } else {
+      interpolate_pilots(q, q->pilot_estimates, ce, port_id);        
       
-  #if NOISE_POWER_METHOD==1
+      /* If not averaging, compute noise from empty subcarriers */
       if (sf_idx == 0 || sf_idx == 5) {
-    q->noise_estimate[port_id] = estimate_noise_port(q, input);
-  }
+#ifdef ESTIMATE_NOISE_LS_PSS
+        q->noise_estimate[port_id] = estimate_noise_pss(q, input, ce);        
+#else
+        q->noise_estimate[port_id] = estimate_noise_empty_sc(q, input);        
 #endif
+      }
+    }
+  }
     
   /* Compute RSRP for the channel estimates in this port */
-  q->rsrp[port_id] = srslte_chest_dl_rsrp(q, port_id);     
+  q->rsrp[port_id] = srslte_vec_avg_power_cf(q->pilot_estimates, SRSLTE_REFSIGNAL_NUM_SF(q->cell.nof_prb, port_id));     
   if (port_id == 0) {
     /* compute rssi only for port 0 */
     q->rssi[port_id] = srslte_chest_dl_rssi(q, input, port_id);     
@@ -380,7 +333,7 @@ float srslte_chest_dl_get_noise_estimate(srslte_chest_dl_t *q) {
 }
 
 float srslte_chest_dl_get_snr(srslte_chest_dl_t *q) {
-  return srslte_chest_dl_get_rsrp(q)/srslte_chest_dl_get_noise_estimate(q);
+  return srslte_chest_dl_get_rsrp(q)/srslte_chest_dl_get_noise_estimate(q)-1;
 }
 
 float srslte_chest_dl_get_rssi(srslte_chest_dl_t *q) {

srslte/lib/ch_estimation/test/CMakeLists.txt

@@ -37,7 +37,7 @@ ADD_TEST(chest_test_dl_cellid2 chest_test_dl -c 2 -r 50)
 # Downlink MEX libs  
 ########################################################################
 
-BuildMex(MEXNAME chest SOURCES chest_test_dl_mex.c LIBRARIES srslte)
+BuildMex(MEXNAME chest SOURCES chest_test_dl_mex.c LIBRARIES srslte srslte_mex)
 
 
 ########################################################################

srslte/lib/ch_estimation/test/chest_test_dl_mex.c

@@ -35,10 +35,7 @@
 #define CELLID  prhs[0]
 #define PORTS   prhs[1]
 #define INPUT   prhs[2]
-#define FREQ_FILTER   prhs[3]
-#define TIME_FILTER   prhs[4]
-#define NOF_INPUTS 5
-#define SFIDX   prhs[5]
+#define NOF_INPUTS 3
 
 void help()
 {
@@ -101,37 +98,6 @@ void mexFunction(int nlhs, mxArray *plhs[], int nrhs, const mxArray *prhs[])
   }
   
   uint32_t sf_idx=0; 
-  if (nsubframes == 1) {
-    if (nrhs != NOF_INPUTS+1) {
-      mexErrMsgTxt("Received 1 subframe. Need to provide subframe index.\n");
-      help();
-      return;
-    }
-    sf_idx = (uint32_t) *((double*) mxGetPr(SFIDX));
-  } 
-  
-  if (nrhs > 5) {
-    uint32_t filter_len = 0;
-    float *filter; 
-    double *f; 
-    
-    filter_len = mxGetNumberOfElements(FREQ_FILTER);
-    filter = malloc(sizeof(float) * filter_len);
-    f = (double*) mxGetPr(FREQ_FILTER);
-    for (i=0;i<filter_len;i++) {
-      filter[i] = (float) f[i];
-    }
-
-    srslte_chest_dl_set_filter_freq(&chest, filter, filter_len);
-
-    filter_len = mxGetNumberOfElements(TIME_FILTER);
-    filter = malloc(sizeof(float) * filter_len);
-    f = (double*) mxGetPr(TIME_FILTER);
-    for (i=0;i<filter_len;i++) {
-      filter[i] = (float) f[i];
-    }
-    srslte_chest_dl_set_filter_time(&chest, filter, filter_len);
-  }  
   
 
   double *inr=(double *)mxGetPr(INPUT);
@@ -150,6 +116,13 @@ void mexFunction(int nlhs, mxArray *plhs[], int nrhs, const mxArray *prhs[])
   
   srslte_precoding_init(&cheq, nof_re);
 
+  
+  cf_t *w=NULL; 
+  if (nrhs > NOF_INPUTS) {
+    mexutils_read_cf(prhs[NOF_INPUTS], &w);
+    srslte_chest_dl_set_filter_w(&chest, w);
+  } 
+    
   /* Create output values */
   if (nlhs >= 1) {
     plhs[0] = mxCreateDoubleMatrix(nof_re * nsubframes, cell.nof_ports, mxCOMPLEX);
@@ -167,6 +140,7 @@ void mexFunction(int nlhs, mxArray *plhs[], int nrhs, const mxArray *prhs[])
     outi2 = mxGetPi(plhs[2]);
   }
     
+  float noise_power=0; 
   for (int sf=0;sf<nsubframes;sf++) {
     /* Convert input to C complex type */
     for (i=0;i<nof_re;i++) {
@@ -187,6 +161,10 @@ void mexFunction(int nlhs, mxArray *plhs[], int nrhs, const mxArray *prhs[])
       return;
     }    
     
+    if (sf==0) {
+      noise_power = srslte_chest_dl_get_noise_estimate(&chest);
+    }
+           
     if (cell.nof_ports == 1) {
       srslte_predecoding_single(input_signal, ce[0], output_signal2, nof_re, srslte_chest_dl_get_noise_estimate(&chest));            
     } else {
@@ -209,9 +187,9 @@ void mexFunction(int nlhs, mxArray *plhs[], int nrhs, const mxArray *prhs[])
     if (nlhs >= 2) {    
       for (int j=0;j<cell.nof_ports;j++) {
         for (i=0;i<SRSLTE_REFSIGNAL_NUM_SF(cell.nof_prb,j);i++) {
-          *outr1 = (double) crealf(chest.pilot_estimates_average[j][i]);
+          *outr1 = (double) crealf(chest.pilot_estimates[i]);
           if (outi1) {
-            *outi1 = (double) cimagf(chest.pilot_estimates_average[j][i]);
+            *outi1 = (double) cimagf(chest.pilot_estimates[i]);
           }
           outr1++;
           outi1++;
@@ -230,8 +208,12 @@ void mexFunction(int nlhs, mxArray *plhs[], int nrhs, const mxArray *prhs[])
     }
   }
 
+  if (w) {
+    free(w);
+  }
+
   if (nlhs >= 4) {
-    plhs[3] = mxCreateDoubleScalar(srslte_chest_dl_get_noise_estimate(&chest));
+    plhs[3] = mxCreateDoubleScalar(noise_power);
   }
   if (nlhs >= 5) {
     plhs[4] = mxCreateDoubleScalar(srslte_chest_dl_get_rsrp(&chest));

srslte/lib/phch/test/pdsch_test_mex.c

@@ -53,7 +53,6 @@ void mexFunction(int nlhs, mxArray *plhs[], int nrhs, const mxArray *prhs[])
   srslte_pdsch_t pdsch;
   srslte_chest_dl_t chest; 
   cf_t *input_fft;
-  int nof_re; 
   srslte_pdsch_cfg_t cfg;
   srslte_softbuffer_rx_t softbuffer; 
   uint32_t rnti32;
@@ -102,9 +101,6 @@ void mexFunction(int nlhs, mxArray *plhs[], int nrhs, const mxArray *prhs[])
     return;
   }
 
-  
-  nof_re = 2 * SRSLTE_CP_NORM_NSYMB * cell.nof_prb * SRSLTE_NRE;
-
   srslte_ra_dl_grant_t grant; 
   grant.mcs.tbs = mxGetScalar(TBS);
   if (grant.mcs.tbs == 0) {
@@ -188,6 +184,18 @@ void mexFunction(int nlhs, mxArray *plhs[], int nrhs, const mxArray *prhs[])
     ce[i] = srslte_vec_malloc(SRSLTE_SF_LEN_RE(cell.nof_prb, cell.cp) * sizeof(cf_t));
   }
   
+  
+  cf_t *w=NULL; 
+  if (nrhs > NOF_INPUTS) {
+    mexutils_read_cf(prhs[NOF_INPUTS], &w);
+    srslte_chest_dl_set_filter_w(&chest, w);
+    srslte_chest_dl_estimate(&chest, input_fft, ce, cfg.sf_idx);    
+    free(w);
+  } else {
+    srslte_chest_dl_estimate(&chest, input_fft, ce, cfg.sf_idx);    
+  }
+  
+  /*
   if (nrhs > NOF_INPUTS) {
     cf_t *cearray = NULL; 
     nof_re = mexutils_read_cf(prhs[NOF_INPUTS], &cearray);
@@ -203,6 +211,8 @@ void mexFunction(int nlhs, mxArray *plhs[], int nrhs, const mxArray *prhs[])
   } else {
     srslte_chest_dl_estimate(&chest, input_fft, ce, cfg.sf_idx);    
   }
+  */
+
   float noise_power;
   if (nrhs > NOF_INPUTS + 1) {
     noise_power = mxGetScalar(prhs[NOF_INPUTS+1]);

srslte/lib/resampling/src/interp.c

@@ -123,12 +123,21 @@ void srslte_interp_linear_vector_free(srslte_interp_linsrslte_vec_t *q) {
 }
 
 void srslte_interp_linear_vector(srslte_interp_linsrslte_vec_t *q, cf_t *in0, cf_t *in1, cf_t *between, uint32_t M) 
+{
+  srslte_interp_linear_vector2(q, in0, in1, NULL, between, M); 
+}
+
+void srslte_interp_linear_vector2(srslte_interp_linsrslte_vec_t *q, cf_t *in0, cf_t *in1, cf_t *start, cf_t *between, uint32_t M) 
 {
   uint32_t i;
   
   srslte_vec_sub_ccc(in1, in0, q->diff_vec, q->vector_len);
-  srslte_vec_sc_prod_cfc(q->diff_vec, (float) 1/M, q->diff_vec, q->vector_len);
+  srslte_vec_sc_prod_cfc(q->diff_vec, (float) 1/(M+1), q->diff_vec, q->vector_len);
+  if (start) {
+    srslte_vec_sum_ccc(start, q->diff_vec, between, q->vector_len);    
+  } else {
     srslte_vec_sum_ccc(in0, q->diff_vec, between, q->vector_len);
+  }
   for (i=0;i<M-1;i++) {
     srslte_vec_sum_ccc(between, q->diff_vec, &between[q->vector_len], q->vector_len);
     between += q->vector_len;
@@ -193,7 +202,7 @@ void srslte_interp_linear_offset(srslte_interp_lin_t *q, cf_t *input, cf_t *outp
   
   i=0;
   for (j=0;j<off_st;j++) {
-    output[j] = input[i] + (j+1) * (input[i+1]-input[i]) / q->M;
+    output[off_st-j-1] = input[i] - (j+1) * (input[i+1]-input[i]) / q->M;
   }
   srslte_vec_sub_ccc(&input[1], input, q->diff_vec, (q->vector_len-1));
   srslte_vec_sc_prod_cfc(q->diff_vec, (float) 1/q->M, q->diff_vec, q->vector_len-1);

srslte/lib/sync/src/pss.c

@@ -254,6 +254,12 @@ void srslte_pss_put_slot(cf_t *pss_signal, cf_t *slot, uint32_t nof_prb, srslte_
   memset(&slot[k + SRSLTE_PSS_LEN], 0, 5 * sizeof(cf_t));
 }
 
+void srslte_pss_get_slot(cf_t *slot, cf_t *pss_signal, uint32_t nof_prb, srslte_cp_t cp) {
+  int k;
+  k = (SRSLTE_CP_NSYMB(cp) - 1) * nof_prb * SRSLTE_NRE + nof_prb * SRSLTE_NRE / 2 - 31;
+  memcpy(pss_signal, &slot[k], SRSLTE_PSS_LEN * sizeof(cf_t));  
+}
+
 
 /** Sets the current N_id_2 value. Returns -1 on error, 0 otherwise
  */