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346 lines
11 KiB
C
346 lines
11 KiB
C
/**
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*
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* \section COPYRIGHT
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*
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* Copyright 2013-2014 The srsLTE 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 srsLTE library.
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*
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* srsLTE 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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* srsLTE 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 "srslte/ue/ue_dl.h"
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#include <complex.h>
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#include <math.h>
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#define CURRENT_FFTSIZE srslte_symbol_sz(q->cell.nof_prb)
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#define CURRENT_SFLEN SRSLTE_SF_LEN(CURRENT_FFTSIZE)
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#define CURRENT_SLOTLEN_RE SRSLTE_SLOT_LEN_RE(q->cell.nof_prb, q->cell.cp)
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#define CURRENT_SFLEN_RE SRSLTE_SF_LEN_RE(q->cell.nof_prb, q->cell.cp)
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#define MAX_CANDIDATES 64
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int srslte_ue_dl_init(srslte_ue_dl_t *q,
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srslte_cell_t cell)
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{
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int ret = SRSLTE_ERROR_INVALID_INPUTS;
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if (q != NULL &&
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srslte_cell_isvalid(&cell))
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{
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ret = SRSLTE_ERROR;
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bzero(q, sizeof(srslte_ue_dl_t));
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q->cell = cell;
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q->pkt_errors = 0;
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q->pkts_total = 0;
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if (srslte_ofdm_rx_init(&q->fft, q->cell.cp, q->cell.nof_prb)) {
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fprintf(stderr, "Error initiating FFT\n");
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goto clean_exit;
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}
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if (srslte_chest_dl_init(&q->chest, cell)) {
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fprintf(stderr, "Error initiating channel estimator\n");
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goto clean_exit;
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}
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if (srslte_regs_init(&q->regs, q->cell)) {
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fprintf(stderr, "Error initiating REGs\n");
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goto clean_exit;
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}
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if (srslte_pcfich_init(&q->pcfich, &q->regs, q->cell)) {
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fprintf(stderr, "Error creating PCFICH object\n");
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goto clean_exit;
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}
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if (srslte_phich_init(&q->phich, &q->regs, q->cell)) {
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fprintf(stderr, "Error creating PHICH object\n");
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goto clean_exit;
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}
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if (srslte_pdcch_init(&q->pdcch, &q->regs, q->cell)) {
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fprintf(stderr, "Error creating PDCCH object\n");
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goto clean_exit;
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}
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if (srslte_pdsch_init(&q->pdsch, q->cell)) {
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fprintf(stderr, "Error creating PDSCH object\n");
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goto clean_exit;
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}
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for (uint32_t i=0;i<SRSLTE_UE_UL_NOF_HARQ_PROCESSES; i++) {
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if (srslte_harq_init(&q->harq_process[i], q->cell)) {
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fprintf(stderr, "Error initiating HARQ process\n");
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goto clean_exit;
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}
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}
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q->sf_symbols = srslte_vec_malloc(CURRENT_SFLEN_RE * sizeof(cf_t));
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if (!q->sf_symbols) {
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perror("malloc");
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goto clean_exit;
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}
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for (uint32_t i=0;i<q->cell.nof_ports;i++) {
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q->ce[i] = srslte_vec_malloc(CURRENT_SFLEN_RE * sizeof(cf_t));
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if (!q->ce[i]) {
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perror("malloc");
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goto clean_exit;
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}
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}
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ret = SRSLTE_SUCCESS;
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} else {
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fprintf(stderr, "Invalid cell properties: Id=%d, Ports=%d, PRBs=%d\n",
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cell.id, cell.nof_ports, cell.nof_prb);
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}
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clean_exit:
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if (ret == SRSLTE_ERROR) {
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srslte_ue_dl_free(q);
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}
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return ret;
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}
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void srslte_ue_dl_free(srslte_ue_dl_t *q) {
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if (q) {
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srslte_ofdm_rx_free(&q->fft);
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srslte_chest_dl_free(&q->chest);
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srslte_regs_free(&q->regs);
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srslte_pcfich_free(&q->pcfich);
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srslte_phich_free(&q->phich);
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srslte_pdcch_free(&q->pdcch);
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srslte_pdsch_free(&q->pdsch);
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for (uint32_t i=0;i<SRSLTE_UE_UL_NOF_HARQ_PROCESSES; i++) {
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srslte_harq_free(&q->harq_process[i]);
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}
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if (q->sf_symbols) {
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free(q->sf_symbols);
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}
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for (uint32_t i=0;i<q->cell.nof_ports;i++) {
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if (q->ce[i]) {
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free(q->ce[i]);
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}
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}
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bzero(q, sizeof(srslte_ue_dl_t));
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}
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}
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/* Precalculate the PDSCH scramble sequences for a given RNTI. This function takes a while
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* to execute, so shall be called once the final C-RNTI has been allocated for the session.
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* For the connection procedure, use srslte_pusch_encode_rnti() or srslte_pusch_decode_rnti() functions
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*/
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void srslte_ue_dl_set_rnti(srslte_ue_dl_t *q, uint16_t rnti) {
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q->current_rnti = rnti;
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srslte_pdsch_set_rnti(&q->pdsch, rnti);
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}
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void srslte_ue_dl_reset(srslte_ue_dl_t *q) {
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srslte_harq_reset(&q->harq_process[0]);
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}
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srslte_dci_format_t ue_formats[] = {SRSLTE_DCI_FORMAT1,SRSLTE_DCI_FORMAT1A}; // SRSLTE_DCI_FORMAT1B should go here also
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const uint32_t nof_ue_formats = 2;
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srslte_dci_format_t common_formats[] = {SRSLTE_DCI_FORMAT1A,SRSLTE_DCI_FORMAT1C};
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const uint32_t nof_common_formats = 2;
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/** Applies the following operations to a subframe of synchronized samples:
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* - OFDM demodulation
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* - Channel estimation
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* - PCFICH decoding
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* - PDCCH decoding: Find DCI for RNTI given by previous call to srslte_ue_dl_set_rnti()
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* - PDSCH decoding: Decode TB scrambling with RNTI given by srslte_ue_dl_set_rnti()
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*/
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int srslte_ue_dl_decode(srslte_ue_dl_t *q, cf_t *input, uint8_t *data, uint32_t sf_idx) {
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return srslte_ue_dl_decode_rnti_rv(q, input, data, sf_idx, q->current_rnti, 0);
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}
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int srslte_ue_dl_decode_rnti(srslte_ue_dl_t *q, cf_t *input, uint8_t *data, uint32_t sf_idx, uint16_t rnti) {
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return srslte_ue_dl_decode_rnti_rv(q, input, data, sf_idx, rnti, 0);
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}
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int srslte_ue_dl_decode_fft_estimate(srslte_ue_dl_t *q, cf_t *input, uint32_t sf_idx, uint32_t *cfi) {
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float cfi_corr;
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if (input && q && cfi && sf_idx < SRSLTE_NSUBFRAMES_X_FRAME) {
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/* Run FFT for all subframe data */
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srslte_ofdm_rx_sf(&q->fft, input, q->sf_symbols);
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/* Get channel estimates for each port */
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srslte_chest_dl_estimate(&q->chest, q->sf_symbols, q->ce, sf_idx);
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/* First decode PCFICH and obtain CFI */
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if (srslte_pcfich_decode(&q->pcfich, q->sf_symbols, q->ce,
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srslte_chest_dl_get_noise_estimate(&q->chest), sf_idx, cfi, &cfi_corr)<0) {
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fprintf(stderr, "Error decoding PCFICH\n");
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return SRSLTE_ERROR;
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}
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INFO("Decoded CFI=%d with correlation %.2f\n", *cfi, cfi_corr);
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if (srslte_regs_set_cfi(&q->regs, *cfi)) {
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fprintf(stderr, "Error setting CFI\n");
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return SRSLTE_ERROR;
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}
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return SRSLTE_SUCCESS;
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} else {
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return SRSLTE_ERROR_INVALID_INPUTS;
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}
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}
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int srslte_ue_dl_decode_rnti_rv_packet(srslte_ue_dl_t *q, srslte_dci_msg_t *dci_msg, uint8_t *data,
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uint32_t cfi, uint32_t sf_idx, uint16_t rnti, uint32_t rvidx)
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{
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int ret = SRSLTE_ERROR;
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q->nof_detected++;
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if (srslte_dci_msg_to_ra_dl(dci_msg, rnti, q->cell, cfi, &q->ra_dl)) {
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fprintf(stderr, "Error unpacking PDSCH scheduling DCI message\n");
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return SRSLTE_ERROR;
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}
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if (rnti != SRSLTE_SIRNTI) {
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rvidx = q->ra_dl.rv_idx;
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}
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if (srslte_harq_setup_dl(&q->harq_process[0], q->ra_dl.mcs, rvidx, sf_idx, &q->ra_dl.prb_alloc)) {
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fprintf(stderr, "Error configuring HARQ process\n");
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return SRSLTE_ERROR;
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}
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if (q->harq_process[0].mcs.mod > 0 && q->harq_process[0].mcs.tbs >= 0) {
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ret = srslte_pdsch_decode_rnti(&q->pdsch, &q->harq_process[0], q->sf_symbols,
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q->ce, 0,
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rnti, data);
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if (ret == SRSLTE_ERROR) {
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q->pkt_errors++;
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} else if (ret == SRSLTE_ERROR_INVALID_INPUTS) {
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fprintf(stderr, "Error calling srslte_pdsch_decode()\n");
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} else if (ret == SRSLTE_SUCCESS) {
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if (SRSLTE_VERBOSE_ISINFO()) {
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INFO("Decoded Message: ", 0);
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srslte_vec_fprint_hex(stdout, data, q->ra_dl.mcs.tbs);
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}
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}
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q->pkts_total++;
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}
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return ret;
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}
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int srslte_ue_dl_find_ul_dci(srslte_ue_dl_t *q, srslte_dci_msg_t *dci_msg, uint32_t cfi, uint32_t sf_idx, uint16_t rnti)
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{
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srslte_dci_location_t locations[MAX_CANDIDATES];
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uint32_t nof_locations = srslte_pdcch_ue_locations(&q->pdcch, locations, MAX_CANDIDATES, sf_idx, cfi, rnti);
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uint16_t crc_rem = 0;
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for (uint32_t i=0;i<nof_locations && crc_rem != rnti;i++) {
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if (srslte_pdcch_decode_msg(&q->pdcch, dci_msg, &locations[i], SRSLTE_DCI_FORMAT0, &crc_rem)) {
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fprintf(stderr, "Error decoding DCI msg\n");
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return SRSLTE_ERROR;
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}
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INFO("Decoded DCI message RNTI: 0x%x\n", crc_rem);
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}
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return crc_rem == rnti;
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}
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int srslte_ue_dl_find_dl_dci(srslte_ue_dl_t *q, srslte_dci_msg_t *dci_msg, uint32_t cfi, uint32_t sf_idx, uint16_t rnti)
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{
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srslte_dci_location_t locations[MAX_CANDIDATES];
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uint32_t nof_locations;
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uint32_t nof_formats;
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srslte_dci_format_t *formats = NULL;
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/* Generate PDCCH candidates */
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if (rnti == SRSLTE_SIRNTI) {
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nof_locations = srslte_pdcch_common_locations(&q->pdcch, locations, MAX_CANDIDATES, q->cfi);
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formats = common_formats;
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nof_formats = nof_common_formats;
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} else {
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nof_locations = srslte_pdcch_ue_locations(&q->pdcch, locations, MAX_CANDIDATES, sf_idx, q->cfi, rnti);
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formats = ue_formats;
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nof_formats = nof_ue_formats;
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}
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uint16_t crc_rem = 0;
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for (int f=0;f<nof_formats && crc_rem != rnti;f++) {
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INFO("Trying format %s\n", srslte_dci_format_string(formats[f]));
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for (int i=0;i<nof_locations && crc_rem != rnti;i++) {
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if (srslte_pdcch_decode_msg(&q->pdcch, dci_msg, &locations[i], formats[f], &crc_rem)) {
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fprintf(stderr, "Error decoding DCI msg\n");
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return SRSLTE_ERROR;
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}
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INFO("Decoded DCI message RNTI: 0x%x\n", crc_rem);
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}
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}
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return crc_rem == rnti;
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}
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int srslte_ue_dl_decode_rnti_rv(srslte_ue_dl_t *q, cf_t *input, uint8_t *data, uint32_t sf_idx, uint16_t rnti, uint32_t rvidx)
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{
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srslte_dci_msg_t dci_msg;
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int ret = SRSLTE_ERROR;
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if ((ret = srslte_ue_dl_decode_fft_estimate(q, input, sf_idx, &q->cfi)) < 0) {
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return ret;
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}
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if (srslte_pdcch_extract_llr(&q->pdcch, q->sf_symbols, q->ce, 0, sf_idx, q->cfi)) {
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fprintf(stderr, "Error extracting LLRs\n");
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return SRSLTE_ERROR;
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}
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int found_dci = srslte_ue_dl_find_dl_dci(q, &dci_msg, q->cfi, sf_idx, rnti);
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if (found_dci == 1) {
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ret = srslte_ue_dl_decode_rnti_rv_packet(q, &dci_msg, data, q->cfi, sf_idx, rnti, rvidx);
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}
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if (found_dci == 1 && ret == SRSLTE_SUCCESS) {
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return q->ra_dl.mcs.tbs;
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} else {
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return 0;
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}
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}
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/* Computes n_group and n_seq according to Section 9.1.2 in 36.213 and calls phich processing function */
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bool srslte_ue_dl_decode_phich(srslte_ue_dl_t *q, uint32_t sf_idx, uint32_t n_prb_lowest, uint32_t n_dmrs)
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{
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uint8_t ack_bit;
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float distance;
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uint32_t Ngroups = srslte_phich_ngroups(&q->phich);
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uint32_t ngroup = (n_prb_lowest+n_dmrs)%Ngroups;
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uint32_t nseq = ((n_prb_lowest/Ngroups)+n_dmrs)%(2*srslte_phich_nsf(&q->phich));
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INFO("Decoding PHICH sf_idx=%d, n_prb_lowest=%d, n_dmrs=%d, n_group=%d, n_seq=%d\n",
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sf_idx, n_prb_lowest, n_dmrs, ngroup, nseq);
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if (!srslte_phich_decode(&q->phich, q->sf_symbols, q->ce, 0, ngroup, nseq, sf_idx, &ack_bit, &distance)) {
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INFO("Decoded PHICH %d with distance %f\n", ack_bit, distance);
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} else {
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fprintf(stderr, "Error decoding PHICH\n");
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return false;
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}
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if (ack_bit && distance > 5.0) {
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return true;
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} else {
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return false;
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}
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}
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