thomas
087dc65d9a
git-svn-id: http://svn.eurecom.fr/openair4G/trunk@4241 818b1a75-f10b-46b9-bf7c-635c3b92a50f
291 lines
11 KiB
Matlab
291 lines
11 KiB
Matlab
%% Header
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%==========================================================================
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% This testbench simulates transmission mode 4 on subframe 7.
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% Results can be compared to "./dlsim -x5 -S7 -R1 -u1" with perfect chest
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% No OFDM Modulation and Demodulation is applied!
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% Only 5 MHz bandwidth simulated. The Channel is Rayleigh block-fading.
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%
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% The matrices ymf0, ymf1, etc are in the form samples x antennas.
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% More precisely:
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% row dimension = [Re Im Re Im ...]
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% col dimension: Heffx: [tx1->rx1 tx1->rx2 tx2->rx1 tx2->rx2]
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% ymfx, Hmagx, Hmagbx, rho10 : [rx1 rx2 rx3 rx4]
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%
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% The same random data is generate as in dlsim.c by setting the right
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% seed value simparms.tseeds.
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%
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%
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% Author: Sebastian Wagner
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% Date: 10-04-2013
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%
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%==========================================================================
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clear all;
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close all;
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clear mex;
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addpath('../../../PHY/LTE_TRANSPORT/mexfiles');
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addpath('../../../PHY/TOOLS/mexfiles');
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addpath('../../../SIMULATION/TOOLS/mexfiles');
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% profile on;
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%% System parameters
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nt = 2; % number of transmit antennas
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nr = 2; % number of receive antennas
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N = 100; % number of frames (or subframes, codewords)
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nSNR = 1; % number of SNR points
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SNRdB = 5; % SNR per receive antenna in dB
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% nSNR = 13;
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% SNRdB = linspace(8,20,nSNR);
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MCS = [16 16]; % MCS for the 2 users
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j = sqrt(-1);
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amp = 1/32; % amplitude scaling for FXP conversion
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XFORMS = 0; % flag to activate graphics
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% LLRs are computed for 8 RE make sure enough valid memory is allocated
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LLR_GUARD_SAMPLES = 8*6; % max mod_order 6 for 8 REs
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%% Initialize simparms
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simparms = InitSimparms(MCS, N, SNRdB);
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%% Random data, same seed as in dlsim.c
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[tmp simparms.tseeds] = taus(1,simparms.tseeds);
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%% Index of REs carrying data
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data_idx = [901:1400 1501:2300 2401:3500 3601:4200];
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data_idx_int = [1801:2800 3001:4600 4801:7000 7201:8400]; % [Re Im] format
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data_idx_int_r = data_idx_int(1:2:length(data_idx_int));
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data_idx_int_i = data_idx_int(2:2:length(data_idx_int));
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%% Allocate memory
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% The LLRs of subframe
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llr0 = zeros(simparms.codeword(1).G, 1,'int16');
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llr1 = zeros(simparms.codeword(2).G, 1,'int16');
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% received signal transformed to FXP
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y_fxp = zeros(simparms.NB_ANTENNAS_RX*simparms.NB_ANTENNAS_TX,simparms.nb_re_per_frame,'int16');
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% FXP received signal with transformed dimensions
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y_fxp_t = zeros(2*simparms.nb_re_per_frame,simparms.NB_ANTENNAS_RX*simparms.NB_ANTENNAS_TX,'int16');
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% MF output of desired user
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ymf0 = zeros(2*simparms.nb_re_per_frame,simparms.NB_ANTENNAS_RX*simparms.NB_ANTENNAS_TX,'int16');
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% Effective channel will contain the channel estimate at pilot positions
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Heff0 = zeros(2*simparms.nb_re_per_frame,simparms.NB_ANTENNAS_RX*simparms.NB_ANTENNAS_TX,'int16');
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Hmag0 = zeros(2*simparms.nb_re_per_frame,simparms.NB_ANTENNAS_RX*simparms.NB_ANTENNAS_TX,'int16');
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Hmagb0 = zeros(2*simparms.nb_re_per_frame,simparms.NB_ANTENNAS_RX*simparms.NB_ANTENNAS_TX,'int16');
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ymf1 = zeros(2*simparms.nb_re_per_frame,simparms.NB_ANTENNAS_RX*simparms.NB_ANTENNAS_TX,'int16');
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Heff1 = zeros(2*simparms.nb_re_per_frame,simparms.NB_ANTENNAS_RX*simparms.NB_ANTENNAS_TX,'int16');
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Hmag1 = zeros(2*simparms.nb_re_per_frame,simparms.NB_ANTENNAS_RX*simparms.NB_ANTENNAS_TX,'int16');
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Hmagb1 = zeros(2*simparms.nb_re_per_frame,simparms.NB_ANTENNAS_RX*simparms.NB_ANTENNAS_TX,'int16');
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rho10 = zeros(2*simparms.nb_re_per_frame,simparms.NB_ANTENNAS_RX*simparms.NB_ANTENNAS_TX,'int16');
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rho01 = zeros(2*simparms.nb_re_per_frame,simparms.NB_ANTENNAS_RX*simparms.NB_ANTENNAS_TX,'int16');
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H = zeros(simparms.NB_ANTENNAS_RX,simparms.NB_ANTENNAS_TX);
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noise = zeros(simparms.NB_ANTENNAS_RX,simparms.nb_re);
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%% XFORMS
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if (XFORMS)
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scrsz = get(0,'ScreenSize');mu_mimo
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figure('Position',[1 scrsz(4)/2 scrsz(3)/2 scrsz(4)/2])
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subplot(1,2,1);
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xlim([1 simparms.codeword(1).G]);
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title('LLRs of UE 0');
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fig_llr0 = scatter(1:simparms.codeword(1).G,llr0,'.','YDataSource','llr0');
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subplot(1,2,2);
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title('MF output of UE 0');
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fig_ymf = scatter(ymf0(data_idx_int_r),ymf0(data_idx_int_i),'.','XDataSource','ymf0(data_idx_int_r)','YDataSource','ymf0(data_idx_int_i)');
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end
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%% Encode and modulate transmit signal
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% The same data is used throughout the simulation -> saves time
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[data0 simparms.tseeds] = taus(simparms.codeword(1).TBS/8,simparms.tseeds);
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[data1 simparms.tseeds] = taus(simparms.codeword(2).TBS/8,simparms.tseeds);
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% Add 4 bytes CRC
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data0 = [data0; zeros(4,1,'uint8')];
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data1 = [data1; zeros(4,1,'uint8')];
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% Turbo encoding of 2 streams for 2 users
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edata0 = dlsch_encoding(data0,simparms,simparms.codeword(1)); % user 1
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edata1 = dlsch_encoding(data1,simparms,simparms.codeword(2)); % user 2
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% Symbol mapping and modulation
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edata_enc(:,1) = simparms.codeword(1).base2*double(reshape(edata0,simparms.codeword(1).mod_order,simparms.nb_re));
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edata_enc(:,2) = simparms.codeword(2).base2*double(reshape(edata1,simparms.codeword(2).mod_order,simparms.nb_re));
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s(:,1) = simparms.codeword(1).const(edata_enc(:,1)+1);
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s(:,2) = simparms.codeword(2).const(edata_enc(:,2)+1);
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%% Loop over SNRs
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for iSNR=1:length(simparms.snr)
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cSNR = simparms.snr(iSNR); % current SNR
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%% Loop over Frames
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for n=1:simparms.n_frames
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%% Channel
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% Rayleigh channel, constant for whole codeblock/frame
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H(1:nr,1:nt) = (randn(nr,nt) + j*randn(nr,nt))/sqrt(2);
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%% PMI computation
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pmi = 1;
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r = H(:,2)'*H(:,1); % correlation
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rr = real(r);
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ri = imag(r);
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if (rr>ri && rr>-ri)
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pmi = 1;
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elseif (rr<ri && rr>-ri)
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pmi = 3;
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elseif (rr<ri && rr<-ri)
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pmi = 2;
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elseif (rr>ri && rr<-ri)
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pmi = 4;
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end
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% opposite pmi
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if(pmi<3)
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pmi_o = mod(pmi,2) + 1;
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else
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pmi_o = mod(pmi,2) + 3;
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end
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pmi_ext = uint8(repmat(pmi-1,1,simparms.nb_rb));
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pmi_ext_o = uint8(repmat(pmi_o-1,1,simparms.nb_rb));
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% normelized precoding vectors
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g0 = simparms.CB(:,pmi);
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g1 = simparms.CB(:,pmi_o);
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%% Transmit signal (frequency domain)
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x = [g0,g1]*conj(s'); % E[|x|^2] = amp^2
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Ptx = sum(diag(x'*x))/simparms.nb_re; % average transmit power per RE
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%% Noise
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sigma2 = (Ptx/cSNR);
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% E[|noise|^2] = amp^2/sqrt(SNR) -> SNR=1/sigma^2
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noise(1:nr,:) = sqrt(sigma2)*(randn(nr,simparms.nb_re) + j*randn(nr,simparms.nb_re))/sqrt(2);
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% real SNR per receive antenna
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SNR_real = 10*log10(Ptx / ((noise(1,:)*noise(1,:)')/simparms.nb_re));
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%% Received signal
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y = H*x + noise; % flat-fading channel model
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% Quantization
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y_fxp_data = int16(floor(y*pow2(15)));
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H_fxp = int16(fix(H*floor(amp*pow2(15)))); % Perfect Chest
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% insert dummy pilots
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y_fxp(1:2,data_idx) = y_fxp_data;
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% reorder for processing
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H_fxp_t = repmat([real(H_fxp(:)) imag(H_fxp(:))]',simparms.nb_re_per_frame,1);
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y_fxp_t(:,1) = reshape([real(y_fxp(1,:)); imag(y_fxp(1,:))],2*simparms.nb_re_per_frame,1);
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y_fxp_t(:,2) = reshape([real(y_fxp(2,:)); imag(y_fxp(2,:))],2*simparms.nb_re_per_frame,1);
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%% Compute Scaling
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avg = dlsch_channel_level_prec(H_fxp_t,pmi_ext,simparms);
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simparms.log2_maxh = max(double(log2_approx(avg))-13,0);
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%% Inner receiver loop
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llr0p = 1; % LLR pointer for codeword 0
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llr1p = 1; % LLR pointer for codeword 1
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for symbol = 4:14
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idxs = 2*(symbol-1)*simparms.nb_re_per_symbol + 1;
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idxe = 2*(symbol-1)*simparms.nb_re_per_symbol + 2*simparms.nb_re_per_symbol;
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%% Preprocessing
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[ymf0(idxs:idxe,:)...
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Heff0(idxs:idxe,:)...
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Hmag0(idxs:idxe,:)...
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Hmagb0(idxs:idxe,:)]...
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= dlsch_channel_compensation_prec(y_fxp_t,H_fxp_t,pmi_ext,simparms,simparms.codeword(1),symbol-1);
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% Interfering stream
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[ymf1(idxs:idxe,:)...
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Heff1(idxs:idxe,:)...
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Hmag1(idxs:idxe,:)...
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Hmagb1(idxs:idxe,:)]...
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= dlsch_channel_compensation_prec(y_fxp_t,H_fxp_t,pmi_ext_o,simparms,simparms.codeword(2),symbol-1);
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%% Correlation coefficient
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rho10(idxs:idxe,:) = dlsch_dual_stream_correlation(Heff0,Heff1,simparms,symbol-1);
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%% Combining
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[ymf0(idxs:idxe,:)...
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ymf1(idxs:idxe,:)...
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Hmag0(idxs:idxe,:)...
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Hmagb0(idxs:idxe,:)...
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Hmag1(idxs:idxe,:)...
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Hmagb1(idxs:idxe,:)...
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rho10(idxs:idxe,:)]...
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= dlsch_detection_mrc(ymf0,ymf1,Hmag0,Hmag1,Hmagb0,Hmagb1,rho10,simparms,symbol-1);
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%% LLR computation
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% first stream
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llr0_t = dlsch_mu_mimo_llr([ymf0(idxs:idxe,1); zeros(LLR_GUARD_SAMPLES,1,'int16')],...
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[ymf1(idxs:idxe,1); zeros(LLR_GUARD_SAMPLES,1,'int16')],...
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[Hmag0(idxs:idxe,1); zeros(LLR_GUARD_SAMPLES,1,'int16')],...
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[Hmag1(idxs:idxe,1); zeros(LLR_GUARD_SAMPLES,1,'int16')],...
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[rho10(idxs:idxe,1); zeros(LLR_GUARD_SAMPLES,1,'int16')],...
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simparms,...
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symbol-1);
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llr0(llr0p:llr0p+length(llr0_t)-1,:) = llr0_t;
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llr0p = llr0p + length(llr0_t);
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% second stream
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% compute conj. correlation term
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tmp = rho10(idxs:idxe,:);
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tmp(2:2:end) = -tmp(2:2:end);
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rho01(idxs:idxe,:) = tmp;
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llr1_t = dlsch_mu_mimo_llr([ymf1(idxs:idxe,1); zeros(LLR_GUARD_SAMPLES,1,'int16')],...
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[ymf0(idxs:idxe,1); zeros(LLR_GUARD_SAMPLES,1,'int16')],...
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[Hmag1(idxs:idxe,1); zeros(LLR_GUARD_SAMPLES,1,'int16')],...
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[Hmag0(idxs:idxe,1); zeros(LLR_GUARD_SAMPLES,1,'int16')],...
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[rho01(idxs:idxe,1); zeros(LLR_GUARD_SAMPLES,1,'int16')],...
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simparms,...
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symbol-1);
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llr1(llr1p:llr1p+length(llr1_t)-1,:) = llr1_t;
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llr1p = llr1p + length(llr1_t);
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end
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if (XFORMS)
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refreshdata(fig_llr0,'caller');
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drawnow;
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refreshdata(fig_ymf,'caller');
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drawnow; pause(0.1);
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end
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%% Channel decoding
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llr0 = -llr0; % invert (since no scrambling applied)
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llr1 = -llr1; % invert (since no scrambling applied)
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ret0 = dlsch_decoding(llr0,simparms,simparms.codeword(1));
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ret1 = dlsch_decoding(llr1,simparms,simparms.codeword(2));
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% Check if decoded correctly
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if (ret0 >= simparms.MAX_TURBO_ITERATIONS)
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simparms.frame_errors(iSNR,1) = simparms.frame_errors(iSNR,1) + 1;
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end
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if (ret1 >= simparms.MAX_TURBO_ITERATIONS)
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simparms.frame_errors(iSNR,2) = simparms.frame_errors(iSNR,2) + 1;
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end
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end
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fprintf('********************SNR = %3.1f dB processed on %s********************\n',real(simparms.snr_db(iSNR)),datestr(now));
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fprintf('Errors: %d/%d\n',simparms.frame_errors(iSNR,1),N);
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fprintf('Errors: %d/%d\n',simparms.frame_errors(iSNR,2),N);
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end
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%% Post Processing
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% total_frame_errors = sum(frame_errors,2);
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% fer = total_frame_errors/N;
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% figure; semilogy(SNRdB,fer); grid;
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%
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% disp(fer);
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% profile viewer
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