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Added matlab models for prach Pdet a Pfa tests. Exposed PRACH detection scaling factor to the public API

This commit is contained in:
Ismael Gomez 2016-04-28 22:14:33 +02:00
parent 71d7151b1b
commit 85c819dff4
6 changed files with 138 additions and 32 deletions
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25
matlab/tests/prach_detect_test.m
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@ -1,8 +1,10 @@
%% PRACH Detection Conformance Test
clear
numSubframes = 50; % Number of subframes frames to simulate at each SNR
SNRdB = linspace(-12,-4,7); % SNR points to simulate
detect_factor=5;
numSubframes = 100; % Number of subframes frames to simulate at each SNR
SNRdB = linspace(-12,-6,8); % SNR points to simulate
foffset = 270.0; % Frequency offset in Hertz
%% UE Configuration
@ -75,30 +77,25 @@ for nSNR = 1:length(SNRdB)
% Channel modeling
chcfg.InitTime = (nsf-1)/1000;
%[rxwave, fadinginfo] = lteFadingChannel(chcfg, ...
% [txwave; zeros(25, 1)]);
[rxwave, fadinginfo] = lteFadingChannel(chcfg, ...
[txwave; zeros(25, 1)]);
rxwave=txwave;
% Add noise
noise = N*complex(randn(size(rxwave)), randn(size(rxwave)));
rxwave = rxwave + noise;
% Remove the implementation delay of the channel modeling
%rxwave = rxwave((fadinginfo.ChannelFilterDelay + 1):1920, :);
rxwave = rxwave((fadinginfo.ChannelFilterDelay + 1):1920, :);
% Apply frequency offset
%t = ((0:size(rxwave, 1)-1)/chcfg.SamplingRate).';
%rxwave = rxwave .* repmat(exp(1i*2*pi*foffset*t), ...
% 1, size(rxwave, 2));
t = ((0:size(rxwave, 1)-1)/chcfg.SamplingRate).';
rxwave = rxwave .* repmat(exp(1i*2*pi*foffset*t), ...
1, size(rxwave, 2));
% PRACH detection for all cell preamble indices
[detected, offsets] = ltePRACHDetect(ue, prach, rxwave, (0:63).');
txwave_srs = srslte_prach(ue, prach);
plot(abs(txwave-txwave_srs))
[detected_srs] = srslte_prach_detect(ue, prach, rxwave);
[detected_srs] = srslte_prach_detect(ue, prach, rxwave, detect_factor);
% Test for preamble detection

83
matlab/tests/prach_falsealarm_test.m Normal file
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@ -0,0 +1,83 @@
%% PRACH False Alarm Probability Conformance Test
clear
detect_factor=5;
ue.NULRB = 6; % Number of resource blocks
ue.DuplexMode = 'FDD'; % FDD duplexing mode
%% PRACH Configuration
prach.Format = 0; % Preamble format
prach.SeqIdx = 2; % Logical root sequence index
prach.CyclicShiftIdx = 1; % Cyclic shift configuration index
prach.HighSpeed = 0; % High speed flag
prach.FreqOffset = 0; % Use default frequency resource index
prach.PreambleIdx = []; % Empty since no preamble is transmitted
%% Establish PRACH Generator Output Length for this Configuration
info = ltePRACHInfo(ue, prach);
nSamples = info.SamplingRate*info.TotSubframes*0.001;
%% Loop for Detection in Each Subframe
numTrials = 2000;
falseCount = 0; % Initialize false detection counter
falseCount_srs = 0; % Initialize false detection counter
rng('default'); % Random number generator to default state
runningP=zeros(1, numTrials);
runningP_srs=zeros(1, numTrials);
for nt = 1:numTrials
% Create noise
noise = complex(randn(nSamples, 1), randn(nSamples, 1));
% Attempt detection for all cell preamble indices (0...63)
[detected,offset] = ltePRACHDetect(ue, prach, noise, 0:63);
[detected_srs] = srslte_prach_detect(ue, prach, noise, detect_factor);
% Record false alarm
if (~isempty(detected))
falseCount = falseCount+1;
end
if (~isempty(detected_srs))
falseCount_srs = falseCount_srs+1;
end
% Calculate running false alarm probability
runningP(nt) = falseCount/nt*100;
runningP_srs(nt) = falseCount_srs/nt*100;
% Plot information about false alarm (if applicable)
if (~isempty(detected))
plot(nt,runningP(nt),'ro','LineWidth',2,'MarkerSize',7);
hold on;
text(nt,runningP(nt), sprintf(['Preamble index = %d' ...
' \nTiming offset = %0.2f samples '],detected,offset), ...
'HorizontalAlignment','right');
end
if (~isempty(detected_srs))
plot(nt,runningP(nt),'mx','LineWidth',2,'MarkerSize',7);
hold on;
text(nt,runningP(nt), sprintf(['SRS index = %d' ...
' \nTiming offset = %0.2f samples '],detected,offset), ...
'HorizontalAlignment','right');
end
end
%% Compute Final False Alarm Probability
P = falseCount / numTrials;
P_srs = falseCount_srs / numTrials;
plot(1:numTrials,runningP,'b','LineWidth',2);
plot(1:numTrials,runningP_srs,'k','LineWidth',2);
hold off
axis([0 numTrials+1 -0.1 0.2]);
xlabel('Trials');
ylabel('Running false alarm probability (%)');
title('PRACH False Alarm Detection Probability');
fprintf('\nFalse alarm probability = %0.4f%% - %.04f%%\n',P*100, P_srs*100);

6
srslte/include/srslte/phch/prach.h
View File

@ -85,6 +85,9 @@ typedef struct SRSLTE_API {
// ZC-sequence FFT and IFFT
srslte_dft_plan_t *zc_fft;
srslte_dft_plan_t *zc_ifft;
cf_t *signal_fft;
float detect_factor;
} srslte_prach_t;
@ -128,6 +131,9 @@ SRSLTE_API int srslte_prach_detect(srslte_prach_t *p,
uint32_t *indices,
uint32_t *ind_len);
SRSLTE_API void srslte_prach_set_detect_factor(srslte_prach_t *p,
float factor);
SRSLTE_API int srslte_prach_free(srslte_prach_t *p);
SRSLTE_API int srslte_prach_print_seqs(srslte_prach_t *p);

41
srslte/lib/phch/prach.c
View File

@ -337,6 +337,7 @@ int srslte_prach_init(srslte_prach_t *p,
p->rsi = root_seq_index;
p->hs = high_speed_flag;
p->zczc = zero_corr_zone_config;
p->detect_factor = PRACH_DETECT_FACTOR;
// Determine N_zc and N_cs
if(4 == preamble_format){
@ -403,6 +404,13 @@ int srslte_prach_init(srslte_prach_t *p,
fprintf(stderr, "Error creating DFT plan\n");
return -1;
}
p->signal_fft = srslte_vec_malloc(sizeof(cf_t)*p->N_ifft_prach);
if (!p->signal_fft) {
fprintf(stderr, "Error allocating memory\n");
return -1;
}
srslte_dft_plan_set_mirror(p->fft, true);
srslte_dft_plan_set_norm(p->fft, true);
@ -455,6 +463,9 @@ int srslte_prach_gen(srslte_prach_t *p,
return ret;
}
void srslte_prach_set_detect_factor(srslte_prach_t *p, float ratio) {
p->detect_factor = ratio;
}
int srslte_prach_detect(srslte_prach_t *p,
uint32_t freq_offset,
@ -475,7 +486,7 @@ int srslte_prach_detect(srslte_prach_t *p,
}
// FFT incoming signal
srslte_dft_run(p->fft, signal, signal);
srslte_dft_run(p->fft, signal, p->signal_fft);
memset(p->prach_bins, 0, sizeof(cf_t)*p->N_zc);
*n_indices = 0;
@ -487,7 +498,7 @@ int srslte_prach_detect(srslte_prach_t *p,
uint32_t begin = PHI + (K*k_0) + (K/2);
for(int i=0;i<p->N_zc;i++){
p->prach_bins[i] = signal[begin+i];
p->prach_bins[i] = p->signal_fft[begin+i];
}
for(int i=0;i<p->N_roots;i++){
@ -497,20 +508,18 @@ int srslte_prach_detect(srslte_prach_t *p,
float corr_ave = 0;
cf_t *root_spec = p->dft_seqs[p->root_seqs_idx[i]];
for(int j=0;j<p->N_zc;j++){
p->corr_spec[j] = p->prach_bins[j]*conjf(root_spec[j]);
}
srslte_vec_prod_conj_ccc(p->prach_bins, root_spec, p->corr_spec, p->N_zc);
srslte_dft_run(p->zc_ifft, p->corr_spec, p->corr_spec);
srslte_vec_abs_cf(p->corr_spec, p->corr, p->N_zc);
float norm = sqrtf(p->N_zc);
for(int j=0;j<p->N_zc;j++){
p->corr[j] = cabsf(p->corr_spec[j])/norm;
corr_ave += p->corr[j];
}
corr_ave /= p->N_zc;
srslte_vec_sc_prod_fff(p->corr, 1.0/norm, p->corr, p->N_zc);
corr_ave = srslte_vec_acc_ff(p->corr, p->N_zc)/p->N_zc;
uint32_t winsize = 0;
if(p->N_cs != 0){
winsize = p->N_cs;
@ -527,7 +536,7 @@ int srslte_prach_detect(srslte_prach_t *p,
corr_max = p->corr[k];
}
}
if(corr_max > PRACH_DETECT_FACTOR*corr_ave){
if(corr_max > p->detect_factor*corr_ave){
indices[*n_indices] = (i*n_wins)+j;
(*n_indices)++;
}
@ -554,6 +563,10 @@ int srslte_prach_free(srslte_prach_t *p) {
srslte_dft_plan_free(p->zc_ifft);
free(p->zc_ifft);
if (p->signal_fft) {
free(p->signal_fft);
}
bzero(p, sizeof(srslte_prach_t));
return 0;

7
srslte/lib/phch/test/prach_detect_test_mex.c
View File

@ -47,7 +47,7 @@ void help()
void mexFunction(int nlhs, mxArray *plhs[], int nrhs, const mxArray *prhs[])
{
if (nrhs != NOF_INPUTS) {
if (nrhs < NOF_INPUTS) {
help();
return;
}
@ -93,6 +93,11 @@ void mexFunction(int nlhs, mxArray *plhs[], int nrhs, const mxArray *prhs[])
uint32_t preambles[64];
uint32_t nof_detected = 0;
if (nrhs > NOF_INPUTS) {
float factor = mxGetScalar(prhs[NOF_INPUTS]);
srslte_prach_set_detect_factor(&prach, factor);
}
if (srslte_prach_detect(&prach, frequency_offset, &input_signal[prach.N_cp], nof_samples, preambles, &nof_detected)) {
mexErrMsgTxt("Error detecting PRACH\n");

8
srslte/lib/phch/test/prach_test.c
View File

@ -31,14 +31,15 @@
#include <unistd.h>
#include <math.h>
#include <time.h>
#include <sys/time.h>
#include <complex.h>
#include "srslte/phch/prach.h"
#include "srslte/srslte.h"
#define MAX_LEN 70176
uint32_t N_ifft_ul = 128;
uint32_t N_ifft_ul = 1536;
uint32_t preamble_format = 0;
uint32_t root_seq_idx = 0;
uint32_t zero_corr_zone = 1;
@ -109,8 +110,9 @@ int main(int argc, char **argv) {
uint32_t prach_len = p->N_seq;
if(preamble_format == 2 || preamble_format == 3)
prach_len /= 2;
srslte_prach_detect(p, 0, &preamble[p->N_cp], prach_len, indices, &n_indices);
if(n_indices != 1 || indices[0] != seq_index)
return -1;
}