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273 lines
7.1 KiB
C
273 lines
7.1 KiB
C
/**
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*
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* \section COPYRIGHT
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*
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* Copyright 2013-2014 The libLTE Developers. See the
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* COPYRIGHT file at the top-level directory of this distribution.
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*
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* \section LICENSE
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*
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* This file is part of the libLTE library.
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*
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* libLTE is free software: you can redistribute it and/or modify
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* it under the terms of the GNU Lesser General Public License as
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* published by the Free Software Foundation, either version 3 of
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* the License, or (at your option) any later version.
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*
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* libLTE is distributed in the hope that it will be useful,
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* but WITHOUT ANY WARRANTY; without even the implied warranty of
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* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
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* GNU Lesser General Public License for more details.
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*
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* A copy of the GNU Lesser General Public License can be found in
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* the LICENSE file in the top-level directory of this distribution
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* and at http://www.gnu.org/licenses/.
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*
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*/
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#include <stdio.h>
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#include <stdlib.h>
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#include <string.h>
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#include <strings.h>
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#include <unistd.h>
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#include <math.h>
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#include <sys/time.h>
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#include <unistd.h>
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#include "liblte/phy/phy.h"
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#ifndef DISABLE_UHD
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#include "liblte/cuhd/cuhd.h"
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int decode_pbch(void *uhd, ue_celldetect_result_t *found_cell, uint32_t nof_frames_total, pbch_mib_t *mib)
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{
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ue_mib_t uemib;
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int n;
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int ret = LIBLTE_ERROR;
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uint32_t nof_frames = 0;
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uint32_t flen = MIB_FRAME_SIZE;
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cf_t *buffer = vec_malloc(sizeof(cf_t) * flen);
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if (!buffer) {
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perror("malloc");
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goto free_and_exit;
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}
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bzero(mib, sizeof(pbch_mib_t));
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if (ue_mib_init(&uemib, found_cell->cell_id, found_cell->cp)) {
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fprintf(stderr, "Error initiating PBCH decoder\n");
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goto free_and_exit;
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}
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INFO("Setting sampling frequency 1.92 MHz for PBCH decoding\n", 0);
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cuhd_set_rx_srate(uhd, 1920000.0);
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INFO("Starting receiver...\n", 0);
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cuhd_start_rx_stream(uhd);
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do {
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if (cuhd_recv(uhd, buffer, flen, 1)<0) {
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fprintf(stderr, "Error receiving from USRP\n");
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goto free_and_exit;
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}
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DEBUG("Calling ue_mib_decode() %d/%d\n", nof_frames, nof_frames_total);
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n = ue_mib_decode(&uemib, buffer, flen, mib);
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if (n == LIBLTE_ERROR || n == LIBLTE_ERROR_INVALID_INPUTS) {
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fprintf(stderr, "Error calling ue_mib_decode()\n");
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goto free_and_exit;
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}
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if (n == MIB_FRAME_UNALIGNED) {
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printf("Realigning frame\n");
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if (cuhd_recv(uhd, buffer, 1500, 1)<0) {
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fprintf(stderr, "Error receiving from USRP\n");
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goto free_and_exit;
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}
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bzero(buffer, flen * sizeof(cf_t));
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}
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nof_frames++;
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} while (n != MIB_FOUND && nof_frames < 2*nof_frames_total);
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if (n == MIB_FOUND) {
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printf("\n\nMIB decoded in %d ms (%d half frames)\n", nof_frames*5, nof_frames);
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pbch_mib_fprint(stdout, mib, found_cell->cell_id);
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ret = LIBLTE_SUCCESS;
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} else {
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ret = LIBLTE_ERROR;
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}
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free_and_exit:
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free(buffer);
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cuhd_stop_rx_stream(uhd);
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cuhd_flush_buffer(uhd);
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ue_mib_free(&uemib);
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return ret;
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}
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int find_cell(void *uhd, ue_celldetect_result_t *found_cell, uint32_t N_id_2)
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{
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int ret = LIBLTE_ERROR;
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ue_celldetect_t cd;
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cf_t *buffer = vec_malloc(sizeof(cf_t) * 96000);
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if (!buffer) {
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perror("malloc");
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goto free_and_exit;
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}
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if (ue_celldetect_init(&cd)) {
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fprintf(stderr, "Error initiating UE cell detect\n");
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goto free_and_exit;
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}
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ue_celldetect_set_nof_frames_detected(&cd, 50);
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ue_celldetect_set_nof_frames_total(&cd, 500);
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INFO("Setting sampling frequency 960 KHz for PSS search\n", 0);
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cuhd_set_rx_srate(uhd, 960000.0);
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INFO("Starting receiver...\n", 0);
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cuhd_start_rx_stream(uhd);
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uint32_t flen = 4800;
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int n;
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do {
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if (cuhd_recv(uhd, buffer, flen, 1)<0) {
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fprintf(stderr, "Error receiving from USRP\n");
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goto free_and_exit;
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}
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DEBUG("Scanning cell at N_id_2=%d\n",N_id_2);
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n = ue_celldetect_scan(&cd, buffer, flen, found_cell, N_id_2);
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switch(n) {
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case CS_FRAME_UNALIGNED:
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printf("Realigning frame\n");
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if (cuhd_recv(uhd, buffer, flen/2, 1)<0) {
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fprintf(stderr, "Error receiving from USRP\n");
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goto free_and_exit;
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}
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/* FIXME: What should we do here?? */
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ret = -1;
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goto free_and_exit;
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case CS_CELL_DETECTED:
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if (found_cell->peak > 0) {
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printf("\n\tCELL ID: %d, CP: %s, Peak: %.2f, Mode: %d/%d\n",
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found_cell->cell_id,
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lte_cp_string(found_cell->cp),
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found_cell->peak, found_cell->mode,
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cd.nof_frames_detected);
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}
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ret = 1;
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INFO("Cell found at N_id_2=%d\n",N_id_2);
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break;
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case CS_CELL_NOT_DETECTED:
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ret = 0;
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DEBUG("No cell found at N_id_2=%d\n",N_id_2);
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break;
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case LIBLTE_ERROR:
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case LIBLTE_ERROR_INVALID_INPUTS:
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ret = LIBLTE_ERROR;
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fprintf(stderr, "Error calling cellsearch_scan()\n");
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goto free_and_exit;
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}
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} while(n == 0);
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free_and_exit:
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free(buffer);
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ue_celldetect_free(&cd);
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INFO("Stopping receiver...\n", 0);
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cuhd_stop_rx_stream(uhd);
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cuhd_flush_buffer(uhd);
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return ret;
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}
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int find_all_cells(void *uhd, ue_celldetect_result_t found_cell[3])
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{
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uint32_t N_id_2;
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int ret;
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int nof_detected_cells = 0;
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for (N_id_2=0;N_id_2<3;N_id_2++) {
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ret = find_cell(uhd, &found_cell[N_id_2], N_id_2);
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if (ret == 1) {
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nof_detected_cells++;
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} else if (ret == LIBLTE_ERROR) {
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return LIBLTE_ERROR;
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}
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}
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return nof_detected_cells;
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}
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int cell_search(void *uhd, int force_N_id_2, lte_cell_t *cell, pbch_mib_t *mib)
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{
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int ret;
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ue_celldetect_result_t found_cells[3];
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bzero(found_cells, 3*sizeof(ue_celldetect_result_t));
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if (force_N_id_2 >= 0) {
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ret = find_cell(uhd, &found_cells[force_N_id_2], force_N_id_2);
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} else {
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ret = find_all_cells(uhd, found_cells);
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}
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if (ret < 0) {
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fprintf(stderr, "Error searching cell\n");
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exit(-1);
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}
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int max_peak_cell = 0;
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float max_peak_value = -1.0;
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if (ret > 0) {
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if (force_N_id_2 >= 0) {
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max_peak_cell = force_N_id_2;
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} else {
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for (int i=0;i<3;i++) {
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if (found_cells[i].peak > max_peak_value) {
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max_peak_value = found_cells[i].peak;
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max_peak_cell = i;
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}
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}
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}
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printf("Decoding PBCH for cell %d (N_id_2=%d)\n", found_cells[max_peak_cell].cell_id, max_peak_cell);
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if (decode_pbch(uhd, &found_cells[max_peak_cell], 400, mib)) {
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fprintf(stderr, "Could not decode PBCH from CELL ID %d\n", found_cells[max_peak_cell].cell_id);
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return LIBLTE_ERROR;
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}
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} else {
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fprintf(stderr, "Could not find any cell in this frequency\n");
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return LIBLTE_ERROR;
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}
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cell->cp = found_cells[max_peak_cell].cp;
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cell->id = found_cells[max_peak_cell].cell_id;
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cell->nof_prb = mib->nof_prb;
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cell->nof_ports = mib->nof_ports;
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/* set sampling frequency */
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int srate = lte_sampling_freq_hz(cell->nof_prb);
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if (srate != -1) {
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cuhd_set_rx_srate(uhd, (double) srate);
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} else {
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fprintf(stderr, "Invalid number of PRB %d\n", cell->nof_prb);
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return LIBLTE_ERROR;
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}
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return LIBLTE_SUCCESS;
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}
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#endif
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