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C

/**
*
* \section COPYRIGHT
*
* Copyright 2013-2014 The libLTE Developers. See the
* COPYRIGHT file at the top-level directory of this distribution.
*
* \section LICENSE
*
* This file is part of the libLTE library.
*
* libLTE is free software: you can redistribute it and/or modify
* it under the terms of the GNU Lesser General Public License as
* published by the Free Software Foundation, either version 3 of
* the License, or (at your option) any later version.
*
* libLTE is distributed in the hope that it will be useful,
* but WITHOUT ANY WARRANTY; without even the implied warranty of
* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
* GNU Lesser General Public License for more details.
*
* A copy of the GNU Lesser General Public License can be found in
* the LICENSE file in the top-level directory of this distribution
* and at http://www.gnu.org/licenses/.
*
*/
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <strings.h>
#include <unistd.h>
#include <math.h>
#include <sys/time.h>
#include <unistd.h>
#include <assert.h>
#include <signal.h>
#include "liblte/rrc/rrc.h"
#include "liblte/phy/phy.h"
#include "liblte/cuhd/cuhd.h"
#include "../cuhd_utils.h"
#include "cell_scanner.h"
#define B210_DEFAULT_GAIN 40.0
#define B210_DEFAULT_GAIN_CORREC 80.0 // Gain of the Rx chain when the gain is set to 40
int cuhd_recv_wrapper(void *h, void *data, uint32_t nsamples) {
DEBUG(" ---- Receive %d samples ---- \n", nsamples);
return cuhd_recv(h, data, nsamples, 1);
}
int cell_scanner_init(cell_scanner_t *q, cell_scanner_config_t *config)
{
bzero(q, sizeof(cell_scanner_t));
memcpy(&q->config, config, sizeof(cell_scanner_config_t));
printf("Opening UHD device...\n");
if (cuhd_open(q->config.uhd_args, &q->uhd)) {
fprintf(stderr, "Error opening uhd\n");
return -1;
}
/* Set receiver gain */
cuhd_set_rx_gain(q->uhd, B210_DEFAULT_GAIN);
return 0;
}
void cell_scanner_close(cell_scanner_t *q) {
cuhd_close(q->uhd);
}
int cell_scanner_all_cells(cell_scanner_t *q, float frequency, cell_scanner_result_t *result)
{
return cell_scanner_cell(q, frequency, -1, result);
}
#define MAX_SINFO 10
int cell_scanner_cell(cell_scanner_t *q, float frequency, int N_id_2, cell_scanner_result_t *result)
{
int ret;
cf_t *sf_buffer;
lte_cell_t cell;
int64_t sf_cnt;
ue_sync_t ue_sync;
ue_mib_t ue_mib;
ue_dl_t ue_dl;
lte_fft_t fft;
chest_dl_t chest;
uint32_t nframes_measure=0;
uint32_t nof_trials = 0;
uint32_t sfn = 0; // system frame number
int n;
uint8_t bch_payload[BCH_PAYLOAD_LEN], bch_payload_unpacked[BCH_PAYLOAD_LEN];
uint32_t sfn_offset;
uint8_t data[1024];
uint8_t data_unpacked[1024];
bzero(result, sizeof(cell_scanner_result_t));
/* set receiver frequency */
cuhd_set_rx_freq(q->uhd, (double) frequency);
cuhd_rx_wait_lo_locked(q->uhd);
printf("Tunning receiver to %.3f MHz\n", (double ) frequency/1000000);
cell_search_cfg_t cfg;
cfg.max_frames_pss = q->config.pss_max_frames;
cfg.max_frames_pbch = q->config.pbch_max_frames;
cfg.threshold = q->config.cell_detect_early_stop_threshold;
ret = cuhd_search_and_decode_mib(q->uhd, &cfg, N_id_2, &cell);
if (ret < 0) {
fprintf(stderr, "Error searching cell\n");
exit(-1);
} else if (ret == 0) {
printf("Cell not found\n");
exit(0);
}
/* set sampling frequency */
int srate = lte_sampling_freq_hz(cell.nof_prb);
if (srate != -1) {
cuhd_set_rx_srate(q->uhd, (double) srate);
} else {
fprintf(stderr, "Invalid number of PRB %d\n", cell.nof_prb);
return LIBLTE_ERROR;
}
INFO("Stopping UHD and flushing buffer...\n",0);
cuhd_stop_rx_stream(q->uhd);
cuhd_flush_buffer(q->uhd);
if (ue_sync_init(&ue_sync, cell, cuhd_recv_wrapper, q->uhd)) {
fprintf(stderr, "Error initiating ue_sync\n");
exit(-1);
}
if (ue_dl_init(&ue_dl, cell, 1234)) {
fprintf(stderr, "Error initiating UE downlink processing module\n");
exit(-1);
}
if (ue_mib_init(&ue_mib, cell)) {
fprintf(stderr, "Error initaiting UE MIB decoder\n");
exit(-1);
}
/* Configure downlink receiver for the SI-RNTI since will be the only one we'll use */
ue_dl_set_rnti(&ue_dl, SIRNTI);
/* Initialize subframe counter */
sf_cnt = 0;
if (lte_fft_init(&fft, cell.cp, cell.nof_prb)) {
fprintf(stderr, "Error initiating FFT\n");
return -1;
}
if (chest_dl_init(&chest, cell)) {
fprintf(stderr, "Error initiating channel estimator\n");
return -1;
}
int sf_re = SF_LEN_RE(cell.nof_prb, cell.cp);
cf_t *sf_symbols = vec_malloc(sf_re * sizeof(cf_t));
cf_t *ce[MAX_PORTS];
for (int i=0;i<MAX_PORTS;i++) {
ce[i] = vec_malloc(sizeof(cf_t) * sf_re);
}
cuhd_start_rx_stream(q->uhd);
memcpy(&result->phy_cell, &cell, sizeof(lte_cell_t));
chest_dl_t *chest_ptr = &ue_dl.chest;
bool mib_decoded = false;
bool sib_decoded = false;
/* Main loop */
while (sf_cnt < q->config.measure_avg_nof_frames) {
ret = ue_sync_get_buffer(&ue_sync, &sf_buffer);
if (ret < 0) {
fprintf(stderr, "Error calling ue_sync_work()\n");
}
/* ue_sync_get_buffer returns 1 if successfully read 1 aligned subframe */
if (ret == 1) {
if (!mib_decoded) {
if (ue_sync_get_sfidx(&ue_sync) == 0) {
pbch_decode_reset(&ue_mib.pbch);
n = ue_mib_decode(&ue_mib, sf_buffer, bch_payload_unpacked, NULL, &sfn_offset);
if (n < 0) {
fprintf(stderr, "Error decoding UE MIB\n");
exit(-1);
} else if (n == MIB_FOUND) {
bit_unpack_vector(bch_payload_unpacked, bch_payload, BCH_PAYLOAD_LEN);
bcch_bch_unpack(bch_payload, BCH_PAYLOAD_LEN, &cell, &sfn);
printf("Decoded MIB. SFN: %d, offset: %d\n", sfn, sfn_offset);
sfn = (sfn + sfn_offset)%1024;
mib_decoded = true;
}
}
}
/* We are looking for SI Blocks, search only in appropiate places */
if (mib_decoded && !sib_decoded &&
(ue_sync_get_sfidx(&ue_sync) == 5 && (sfn%2)==0))
{
n = ue_dl_decode_sib(&ue_dl, sf_buffer, data, ue_sync_get_sfidx(&ue_sync),
((int) ceilf((float)3*(((sfn)/2)%4)/2))%4);
if (n < 0) {
fprintf(stderr, "Error decoding UE DL\n");fflush(stdout);
exit(-1);
} else if (n == 0) {
nof_trials++;
} else {
bit_unpack_vector(data, data_unpacked, n);
void *dlsch_msg = bcch_dlsch_unpack(data_unpacked, n);
if (dlsch_msg) {
printf("\n");fflush(stdout);
cell_access_info_t cell_info;
bcch_dlsch_sib1_get_cell_access_info(dlsch_msg, &cell_info);
printf("Decoded SIB1. Cell ID: 0x%x\n", cell_info.cell_id);
result->cell_id = cell_info.cell_id;
bcch_dlsch_fprint(dlsch_msg, stdout);
sib_decoded = true;
}
}
} else {
chest_ptr = &chest;
/* Run FFT for all subframe data */
lte_fft_run_sf(&fft, sf_buffer, sf_symbols);
chest_dl_estimate(&chest, sf_symbols, ce, ue_sync_get_sfidx(&ue_sync));
}
result->rssi = VEC_CMA(vec_avg_power_cf(sf_buffer,SF_LEN(lte_symbol_sz(cell.nof_prb))),
result->rssi,nframes_measure);
result->rsrq = VEC_EMA(chest_dl_get_rsrq(chest_ptr),result->rsrq,0.01);
result->rsrp = VEC_CMA(chest_dl_get_rsrp(chest_ptr),result->rsrp,nframes_measure);
result->snr = VEC_CMA(chest_dl_get_snr(chest_ptr),result->snr,nframes_measure);
nframes_measure++;
// Plot and Printf
if ((nframes_measure%10) == 0) {
printf("CFO: %+8.4f KHz, SFO: %+8.4f Khz, RSSI: %5.1f dBm, "
"RSRP: %+5.1f dBm, RSRQ: %5.1f dB, SNR: %5.1f dB\r",
ue_sync_get_cfo(&ue_sync)/1000, ue_sync_get_sfo(&ue_sync)/1000,
10*log10(result->rssi*1000)-B210_DEFAULT_GAIN_CORREC,
10*log10(result->rsrp*1000)-B210_DEFAULT_GAIN_CORREC,
10*log10(result->rsrq), 10*log10(result->snr));
if (verbose != VERBOSE_NONE) {
printf("\n");
}
}
if (ue_sync_get_sfidx(&ue_sync) == 9) {
sfn++;
if (sfn == 1024) {
sfn = 0;
}
}
} else if (ret == 0) {
printf("Finding PSS... Peak: %8.1f, FrameCnt: %d, State: %d\r",
sync_get_peak_value(&ue_sync.sfind),
ue_sync.frame_total_cnt, ue_sync.state);
}
sf_cnt++;
} // Main loop
// Correct RSRP and RSSI measurements
result->rssi /= pow(10, 8);
result->rsrp /= pow(10, 8);
ue_sync_free(&ue_sync);
return 0;
}