srsRAN/examples/mib_scan_usrp.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 "lte.h"

//#define DISABLE_UHD

#ifndef DISABLE_UHD
#include "cuhd.h"
#endif

#define MHZ 			1000000
#define SAMP_FREQ 		1920000
#define RSSI_FS			1000000
#define FLEN 			9600
#define FLEN_PERIOD		0.005

#define RSSI_DECIM		20

#define IS_SIGNAL(i) (10*log10f(rssi[i]) + 30 > rssi_threshold)

int band, earfcn=-1;
float find_threshold = 40.0, track_threshold = 8.0;
int earfcn_start=-1, earfcn_end = -1;
float rssi_threshold = -30.0;
int max_track_lost=9;
int nof_frames_find=8, nof_frames_track=100, nof_samples_rssi=50000;
int track_len=500;

cf_t *input_buffer, *fft_buffer, *ce[MAX_PORTS];
pbch_t pbch;
lte_fft_t fft;
chest_t chest;
sync_t sfind, strack;

float *cfo_v;
int *idx_v, *idx_valid, *t;
float *p2a_v;
void *uhd;
int nof_bands;
float gain = 30.0;

#define MAX_EARFCN 1000
lte_earfcn_t channels[MAX_EARFCN];
float rssi[MAX_EARFCN];
float rssi_d[MAX_EARFCN/RSSI_DECIM];
float freqs[MAX_EARFCN];
float cfo[MAX_EARFCN];
float p2a[MAX_EARFCN];

enum sync_state {INIT, FIND, TRACK, MIB, DONE};


void usage(char *prog) {
	printf("Usage: %s [seRrFfTtgv] -b band\n", prog);
	printf("\t-s earfcn_start [Default All]\n");
	printf("\t-e earfcn_end [Default All]\n");
	printf("\t-R rssi_nof_samples [Default %d]\n", nof_samples_rssi);
	printf("\t-r rssi_threshold [Default %.2f dBm]\n", rssi_threshold);
	printf("\t-F pss_find_nof_frames [Default %d]\n", nof_frames_find);
	printf("\t-f pss_find_threshold [Default %.2f]\n", find_threshold);
	printf("\t-T pss_track_nof_frames [Default %d]\n", nof_frames_track);
	printf("\t-t pss_track_threshold [Default %.2f]\n", track_threshold);
	printf("\t-l pss_track_len [Default %d]\n", track_len);
	printf("\t-g gain [Default %.2f dB]\n", gain);
	printf("\t-v [set verbose to debug, default none]\n");
}

void parse_args(int argc, char **argv) {
	int opt;
	while ((opt = getopt(argc, argv, "bseRrFfTtgv")) != -1) {
		switch(opt) {
		case 'b':
			band = atoi(argv[optind]);
			break;
		case 's':
			earfcn_start = atoi(argv[optind]);
			break;
		case 'e':
			earfcn_end = atoi(argv[optind]);
			break;
		case 'R':
			nof_samples_rssi = atoi(argv[optind]);
			break;
		case 'r':
			rssi_threshold = -atof(argv[optind]);
			break;
		case 'F':
			nof_frames_find = atoi(argv[optind]);
			break;
		case 'f':
			find_threshold = atof(argv[optind]);
			break;
		case 'T':
			nof_frames_track = atoi(argv[optind]);
			break;
		case 't':
			track_threshold = atof(argv[optind]);
			break;
		case 'g':
			gain = atof(argv[optind]);
			break;
		case 'v':
			verbose++;
			break;
		default:
			usage(argv[0]);
			exit(-1);
		}
	}
}

int base_init(int frame_length) {
	int i;

	input_buffer = malloc(2 * frame_length * sizeof(cf_t));
	if (!input_buffer) {
		perror("malloc");
		return -1;
	}

	fft_buffer = malloc(CPNORM_NSYMB * 72 * sizeof(cf_t));
	if (!fft_buffer) {
		perror("malloc");
		return -1;
	}

	for (i=0;i<MAX_PORTS;i++) {
		ce[i] = malloc(CPNORM_NSYMB * 72 * sizeof(cf_t));
		if (!ce[i]) {
			perror("malloc");
			return -1;
		}
	}
	if (sync_init(&sfind, FLEN)) {
		fprintf(stderr, "Error initiating PSS/SSS\n");
		return -1;
	}
	if (sync_init(&strack, track_len)) {
		fprintf(stderr, "Error initiating PSS/SSS\n");
		return -1;
	}
	if (chest_init(&chest, LINEAR, CPNORM, 6, MAX_PORTS)) {
		fprintf(stderr, "Error initializing equalizer\n");
		return -1;
	}

	if (lte_fft_init(&fft, CPNORM, 6)) {
		fprintf(stderr, "Error initializing FFT\n");
		return -1;
	}

	idx_v = malloc(nof_frames_track * sizeof(int));
	if (!idx_v) {
		perror("malloc");
		return -1;
	}
	idx_valid = malloc(nof_frames_track * sizeof(int));
	if (!idx_valid) {
		perror("malloc");
		return -1;
	}
	t = malloc(nof_frames_track * sizeof(int));
	if (!t) {
		perror("malloc");
		return -1;
	}
	cfo_v = malloc(nof_frames_track * sizeof(float));
	if (!cfo_v) {
		perror("malloc");
		return -1;
	}
	p2a_v = malloc(nof_frames_track * sizeof(float));
	if (!p2a_v) {
		perror("malloc");
		return -1;
	}

	bzero(cfo, sizeof(float) * MAX_EARFCN);
	bzero(p2a, sizeof(float) * MAX_EARFCN);

	/* open UHD device */
#ifndef DISABLE_UHD
	printf("Opening UHD device...\n");
	if (cuhd_open("",&uhd)) {
		fprintf(stderr, "Error opening uhd\n");
		return -1;
	}
#endif
	return 0;
}

void base_free() {
	int i;

#ifndef DISABLE_UHD
	cuhd_close(&uhd);
#endif
	sync_free(&sfind);
	sync_free(&strack);
	lte_fft_free(&fft);
	chest_free(&chest);

	free(input_buffer);
	free(fft_buffer);
	for (i=0;i<MAX_PORTS;i++) {
			free(ce[i]);
	}
	free(idx_v);
	free(idx_valid);
	free(t);
	free(cfo_v);
	free(p2a_v);
}

float mean_valid(int *idx_v, float *x, int nof_frames) {
	int i;
	float mean = 0;
	int n = 0;
	for (i=0;i<nof_frames;i++) {
		if (idx_v[i] != -1) {
			mean += x[i];
			n++;
		}
	}
	if (n > 0) {
		return mean/n;
	} else {
		return 0.0;
	}
}

int preprocess_idx(int *in, int *out, int *period, int len) {
	int i, n;
	n=0;
	for (i=0;i<len;i++) {
		if (in[i] != -1) {
			out[n] = in[i];
			period[n] = i;
			n++;
		}
	}
	return n;
}

int rssi_scan() {
	int n=0;
	int i;

	if (nof_bands > 100) {
		/* scan every Mhz, that is 10 freqs */
		for (i=0;i<nof_bands;i+=RSSI_DECIM) {
			freqs[n] = channels[i].fd * MHZ;
			n++;
		}
#ifndef DISABLE_UHD
		if (cuhd_rssi_scan(uhd, freqs, rssi_d, n, (double) RSSI_FS, nof_samples_rssi)) {
			fprintf(stderr, "Error while doing RSSI scan\n");
			return -1;
		}
#endif
		/* linearly interpolate the rssi vector */
		interp_linear_f(rssi_d, rssi, RSSI_DECIM, n);
	} else {
		for (i=0;i<nof_bands;i++) {
			freqs[i] = channels[i].fd * MHZ;
		}
#ifndef DISABLE_UHD
		if (cuhd_rssi_scan(uhd, freqs, rssi, nof_bands, (double) RSSI_FS, nof_samples_rssi)) {
			fprintf(stderr, "Error while doing RSSI scan\n");
			return -1;
		}
#endif
		n = nof_bands;
	}

	return n;
}


int mib_decoder_init(int cell_id) {

	if (chest_ref_LTEDL(&chest, cell_id)) {
		fprintf(stderr, "Error initializing reference signal\n");
		return -1;
	}

	if (pbch_init(&pbch, cell_id, CPNORM)) {
		fprintf(stderr, "Error initiating PBCH\n");
		return -1;
	}
	DEBUG("PBCH initiated cell_id=%d\n", cell_id);
	return 0;
}

int mib_decoder_run(cf_t *input, pbch_mib_t *mib) {
	int i;
	lte_fft_run(&fft, input, fft_buffer);

	/* Get channel estimates for each port */
	for (i=0;i<MAX_PORTS;i++) {
		chest_ce_slot_port(&chest, fft_buffer, ce[i], 1, i);
	}

	DEBUG("Decoding PBCH\n", 0);
	return pbch_decode(&pbch, fft_buffer, ce, 6, 1, mib);
}

int main(int argc, char **argv) {
	int frame_cnt, valid_frames;
	int freq;
	int cell_id;
	float max_peak_to_avg;
	float sfo;
	int find_idx, track_idx, last_found;
	enum sync_state state;
	int n;
	int mib_attempts;
	int nslot;
	pbch_mib_t mib;

	if (argc < 3) {
		usage(argv[0]);
		exit(-1);
	}

	parse_args(argc,argv);

	if (base_init(FLEN)) {
		fprintf(stderr, "Error initializing memory\n");
		exit(-1);
	}

	sync_pss_det_peakmean(&sfind);
	sync_pss_det_peakmean(&strack);

	nof_bands = lte_band_get_fd_band(band, channels, earfcn_start, earfcn_end, MAX_EARFCN);
	printf("RSSI scan: %d freqs in band %d, RSSI threshold %.2f dBm\n", nof_bands, band, rssi_threshold);

	n = rssi_scan();
	if (n == -1) {
		exit(-1);
	}

	printf("\nDone. Starting PSS search on %d channels\n", n);
	usleep(500000);
	INFO("Setting sampling frequency %.2f MHz\n", (float) SAMP_FREQ/MHZ);
#ifndef DISABLE_UHD
	cuhd_set_rx_srate(uhd, SAMP_FREQ);

	cuhd_set_rx_gain(uhd, gain);
#endif

	freq=0;
	state = INIT;
	nslot = 0;
	sfo = 0;
	find_idx = 0;
	frame_cnt = 0;
	max_peak_to_avg = -1;
	last_found = 0;
	cell_id = 0;

	while(freq<nof_bands) {
		/* scan only bands above rssi_threshold */
		if (!IS_SIGNAL(freq)) {
			INFO("[%3d/%d]: Skipping EARFCN %d %.2f MHz RSSI %.2f dB\n", freq, nof_bands,
								channels[freq].id, channels[freq].fd,10*log10f(rssi[freq]) + 30);
			freq++;
		} else {
			if (state != INIT && state != DONE) {
#ifndef DISABLE_UHD
				DEBUG(" -----   RECEIVING %d SAMPLES ---- \n", FLEN);
				cuhd_recv(uhd, &input_buffer[FLEN], FLEN, 1);
#endif
			}
			switch(state) {
			case INIT:
				DEBUG("Stopping receiver...\n",0);
#ifndef DISABLE_UHD
				cuhd_stop_rx_stream(uhd);

				/* set freq */
				cuhd_set_rx_freq(uhd, (double) channels[freq].fd * MHZ);
				cuhd_rx_wait_lo_locked(uhd);
				DEBUG("Set freq to %.3f MHz\n", (double) channels[freq].fd);

				DEBUG("Starting receiver...\n",0);
				cuhd_start_rx_stream(uhd);
#endif
				/* init variables */
				frame_cnt = 0;
				max_peak_to_avg = -1;
				cell_id = -1;

				/* receive first frame */
#ifndef DISABLE_UHD
				cuhd_recv(uhd, input_buffer, FLEN, 1);
#endif
				/* set find_threshold and go to FIND state */
				sync_set_threshold(&sfind, find_threshold);
				sync_force_N_id_2(&sfind, -1);
				state = FIND;
				break;
			case FIND:
				/* find peak in all frame */
				find_idx = sync_run(&sfind, &input_buffer[FLEN]);
				DEBUG("[%3d/%d]: PAR=%.2f\n", freq, nof_bands, sync_get_peak_to_avg(&sfind));
				if (find_idx != -1) {
					/* if found peak, go to track and set lower threshold */
					frame_cnt = -1;
					last_found = 0;
					max_peak_to_avg = -1;
					sync_set_threshold(&strack, track_threshold);
					sync_force_N_id_2(&strack, sync_get_N_id_2(&sfind));
					cell_id = sync_get_cell_id(&sfind);

					state = TRACK;
					INFO("[%3d/%d]: EARFCN %d Freq. %.2f MHz PSS found PAR %.2f dB\n", freq, nof_bands,
												channels[freq].id, channels[freq].fd,
												10*log10f(sync_get_peak_to_avg(&sfind)));
				} else {
					if (frame_cnt >= nof_frames_find) {
						state = INIT;
						freq++;
					}
				}
				break;
			case TRACK:
				INFO("Tracking PSS find_idx %d offset %d\n", find_idx, find_idx - track_len);

				track_idx = sync_run(&strack, &input_buffer[FLEN + find_idx - track_len]);
				p2a_v[frame_cnt] = sync_get_peak_to_avg(&strack);

				/* save cell id for the best peak-to-avg */
				if (p2a_v[frame_cnt] > max_peak_to_avg) {
					max_peak_to_avg = p2a_v[frame_cnt];
					cell_id = sync_get_cell_id(&strack);
				}
				if (track_idx != -1) {
					cfo_v[frame_cnt] = sync_get_cfo(&strack);
					last_found = frame_cnt;
					find_idx += track_idx - track_len;
					idx_v[frame_cnt] = find_idx;
					nslot = sync_get_slot_id(&strack);
				} else {
					idx_v[frame_cnt] = -1;
					cfo_v[frame_cnt] = 0.0;
				}
				/* if we missed to many PSS it is not a cell, next freq */
				if (frame_cnt - last_found > max_track_lost) {
					INFO("\n[%3d/%d]: EARFCN %d Freq. %.2f MHz %d frames lost\n", freq, nof_bands,
							channels[freq].id, channels[freq].fd, frame_cnt - last_found);

					state = INIT;
					freq++;
				} else if (frame_cnt >= nof_frames_track) {
					mib_decoder_init(cell_id);

					cfo[freq] = mean_valid(idx_v, cfo_v, frame_cnt);
					p2a[freq] = mean_valid(idx_v, p2a_v, frame_cnt);
					valid_frames = preprocess_idx(idx_v, idx_valid, t, frame_cnt);
					sfo = sfo_estimate_period(idx_valid, t, valid_frames, FLEN_PERIOD);

					state = MIB;
					nslot=(nslot+10)%20;
				}
				break;
			case MIB:
				INFO("Finding MIB at freq %.2f Mhz offset=%d, cell_id=%d, slot_idx=%d\n", channels[freq].fd, find_idx, cell_id, nslot);

				// TODO: Correct SFO

				// Correct CFO
				INFO("Correcting CFO=%.4f\n", cfo[freq]);
				nco_cexp_f_direct(&input_buffer[FLEN], (-cfo[freq])/128, FLEN);

				if (nslot == 0) {
					if (mib_decoder_run(&input_buffer[FLEN+find_idx], &mib)) {
						INFO("MIB detected attempt=%d\n", mib_attempts);
						state = DONE;
					} else {
						INFO("MIB not detected attempt=%d\n", mib_attempts);
						if (mib_attempts == 0) {
							freq++;
							state = INIT;
						}
					}
					mib_attempts++;
				}
				nslot = (nslot+10)%20;


				break;
			case DONE:
				printf("\n[%3d/%d]: FOUND EARFCN %d Freq. %.2f MHz. "
						"PAR %2.2f dB, CFO=%+.2f KHz, SFO=%+2.3f KHz, CELL_ID=%3d\n", freq, nof_bands,
								channels[freq].id, channels[freq].fd,
								10*log10f(p2a[freq]), cfo[freq] * 15, sfo / 1000, cell_id);
				pbch_mib_fprint(stdout, &mib);
				state = INIT;
				freq++;
				break;
			}

			/** FIXME: This is not necessary at all */
			if (state == TRACK || state == FIND) {
				memcpy(input_buffer, &input_buffer[FLEN], FLEN * sizeof(cf_t));
			}
			frame_cnt++;
		}
	}

	base_free();

	printf("\n\nDone\n");
	exit(0);
}