448 lines
13 KiB
C
448 lines
13 KiB
C
/**
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*
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* \section COPYRIGHT
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*
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* Copyright 2013-2015 Software Radio Systems Limited
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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 Affero 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 Affero General Public License for more details.
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*
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* A copy of the GNU Affero 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 <stdint.h>
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#include <stdio.h>
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#include <string.h>
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#include <strings.h>
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#include <stdlib.h>
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#include <stdbool.h>
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#include <assert.h>
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#include <math.h>
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#include <srslte/phy/common/phy_common.h>
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#include "srslte/phy/phch/regs.h"
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#include "srslte/phy/phch/phich.h"
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#include "srslte/phy/common/phy_common.h"
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#include "srslte/phy/utils/bit.h"
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#include "srslte/phy/utils/vector.h"
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#include "srslte/phy/utils/debug.h"
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/** Table 6.9.1-2 */
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const cf_t w_normal[SRSLTE_PHICH_NORM_NSEQUENCES][4] = { { 1, 1, 1, 1 },
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{ 1, -1, 1, -1 }, { 1, 1, -1, -1 }, { 1, -1, -1, 1 }, { I, I, I, I }, {
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I, -I, I, -I }, { I, I, -I, -I }, { I, -I, -I, I } };
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const cf_t w_ext[SRSLTE_PHICH_EXT_NSEQUENCES][2] = { { 1, 1 }, { 1, -1 }, { I, I }, {
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I, -I } };
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uint32_t srslte_phich_ngroups(srslte_phich_t *q) {
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return srslte_regs_phich_ngroups(q->regs);
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}
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uint32_t srslte_phich_nsf(srslte_phich_t *q) {
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if (SRSLTE_CP_ISNORM(q->cell.cp)) {
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return SRSLTE_PHICH_NORM_NSF;
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} else {
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return SRSLTE_PHICH_EXT_NSF;
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}
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}
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void srslte_phich_reset(srslte_phich_t *q, cf_t *slot_symbols[SRSLTE_MAX_PORTS]) {
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int i;
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for (i = 0; i < SRSLTE_MAX_PORTS; i++) {
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srslte_regs_phich_reset(q->regs, slot_symbols[i]);
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}
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}
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int srslte_phich_init(srslte_phich_t *q)
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{
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return srslte_phich_init_multi(q, 1);
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}
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/** Initializes the phich channel receiver */
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int srslte_phich_init_multi(srslte_phich_t *q, uint32_t nof_rx_antennas)
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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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{
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bzero(q, sizeof(srslte_phich_t));
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ret = SRSLTE_ERROR;
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q->nof_rx_antennas = nof_rx_antennas;
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if (srslte_modem_table_lte(&q->mod, SRSLTE_MOD_BPSK)) {
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goto clean;
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}
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ret = SRSLTE_SUCCESS;
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}
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clean:
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if (ret == SRSLTE_ERROR) {
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srslte_phich_free(q);
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}
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return ret;
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}
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void srslte_phich_free(srslte_phich_t *q) {
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for (int ns = 0; ns < SRSLTE_NSUBFRAMES_X_FRAME; ns++) {
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srslte_sequence_free(&q->seq[ns]);
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}
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srslte_modem_table_free(&q->mod);
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bzero(q, sizeof(srslte_phich_t));
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}
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int srslte_phich_set_cell(srslte_phich_t *q, srslte_regs_t *regs, 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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regs != NULL &&
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srslte_cell_isvalid(&cell))
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{
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q->regs = regs;
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if (cell.id != q->cell.id || q->cell.nof_prb == 0) {
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memcpy(&q->cell, &cell, sizeof(srslte_cell_t));
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for (int nsf = 0; nsf < SRSLTE_NSUBFRAMES_X_FRAME; nsf++) {
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if (srslte_sequence_phich(&q->seq[nsf], 2 * nsf, q->cell.id)) {
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return SRSLTE_ERROR;
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}
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}
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}
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ret = SRSLTE_SUCCESS;
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}
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return ret;
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}
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/* Computes n_group and n_seq according to Section 9.1.2 in 36.213 */
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void srslte_phich_calc(srslte_phich_t *q, uint32_t n_prb_lowest, uint32_t n_dmrs,
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uint32_t *ngroup, uint32_t *nseq)
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{
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uint32_t Ngroups = srslte_phich_ngroups(q);
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*ngroup = (n_prb_lowest+n_dmrs)%Ngroups;
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*nseq = ((n_prb_lowest/Ngroups)+n_dmrs)%(2*srslte_phich_nsf(q));
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}
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/* Decodes ACK
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*
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*/
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uint8_t srslte_phich_ack_decode(float bits[SRSLTE_PHICH_NBITS], float *distance) {
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int i;
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float ack_table[2][3] = {{-1.0, -1.0, -1.0}, {1.0, 1.0, 1.0}};
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float max_corr = -9999;
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uint8_t index=0;
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if (SRSLTE_VERBOSE_ISINFO()) {
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INFO("Received bits: ", 0);
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srslte_vec_fprint_f(stdout, bits, SRSLTE_PHICH_NBITS);
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}
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for (i = 0; i < 2; i++) {
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float corr = srslte_vec_dot_prod_fff(ack_table[i], bits, SRSLTE_PHICH_NBITS);
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INFO("Corr%d=%f\n", i, corr);
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if (corr > max_corr) {
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max_corr = corr;
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if (distance) {
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*distance = max_corr;
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}
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index = i;
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}
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}
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return index;
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}
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/** Encodes the ACK
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* 36.212
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*/
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void srslte_phich_ack_encode(uint8_t ack, uint8_t bits[SRSLTE_PHICH_NBITS]) {
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memset(bits, ack, 3 * sizeof(uint8_t));
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}
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int srslte_phich_decode(srslte_phich_t *q, cf_t *sf_symbols, cf_t *ce[SRSLTE_MAX_PORTS], float noise_estimate,
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uint32_t ngroup, uint32_t nseq, uint32_t subframe, uint8_t *ack, float *distance)
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{
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cf_t *_sf_symbols[SRSLTE_MAX_PORTS];
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cf_t *_ce[SRSLTE_MAX_PORTS][SRSLTE_MAX_PORTS];
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_sf_symbols[0] = sf_symbols;
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for (int i=0;i<q->cell.nof_ports;i++) {
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_ce[i][0] = ce[i];
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}
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return srslte_phich_decode_multi(q, _sf_symbols, _ce, noise_estimate, ngroup, nseq, subframe, ack, distance);
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}
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/* Decodes the phich channel and saves the CFI in the cfi pointer.
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*
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* Returns 1 if successfully decoded the CFI, 0 if not and -1 on error
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*/
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int srslte_phich_decode_multi(srslte_phich_t *q, cf_t *sf_symbols[SRSLTE_MAX_PORTS], cf_t *ce[SRSLTE_MAX_PORTS][SRSLTE_MAX_PORTS], float noise_estimate,
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uint32_t ngroup, uint32_t nseq, uint32_t subframe, uint8_t *ack, float *distance)
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{
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/* Set pointers for layermapping & precoding */
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int i, j;
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cf_t *x[SRSLTE_MAX_LAYERS];
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if (q == NULL || sf_symbols == NULL) {
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return SRSLTE_ERROR_INVALID_INPUTS;
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}
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if (subframe >= SRSLTE_NSUBFRAMES_X_FRAME) {
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fprintf(stderr, "Invalid nslot %d\n", subframe);
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return SRSLTE_ERROR_INVALID_INPUTS;
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}
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if (SRSLTE_CP_ISEXT(q->cell.cp)) {
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if (nseq >= SRSLTE_PHICH_EXT_NSEQUENCES) {
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fprintf(stderr, "Invalid nseq %d\n", nseq);
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return SRSLTE_ERROR_INVALID_INPUTS;
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}
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} else {
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if (nseq >= SRSLTE_PHICH_NORM_NSEQUENCES) {
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fprintf(stderr, "Invalid nseq %d\n", nseq);
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return SRSLTE_ERROR_INVALID_INPUTS;
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}
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}
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if (ngroup >= srslte_regs_phich_ngroups(q->regs)) {
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fprintf(stderr, "Invalid ngroup %d\n", ngroup);
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return SRSLTE_ERROR_INVALID_INPUTS;
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}
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DEBUG("Decoding PHICH Ngroup: %d, Nseq: %d\n", ngroup, nseq);
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/* number of layers equals number of ports */
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for (i = 0; i < SRSLTE_MAX_PORTS; i++) {
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x[i] = q->x[i];
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}
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cf_t *q_ce[SRSLTE_MAX_PORTS][SRSLTE_MAX_PORTS];
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cf_t *q_sf_symbols[SRSLTE_MAX_PORTS];
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/* extract symbols */
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for (int j=0;j<q->nof_rx_antennas;j++) {
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if (SRSLTE_PHICH_MAX_NSYMB
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!= srslte_regs_phich_get(q->regs, sf_symbols[j], q->sf_symbols[j], ngroup)) {
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fprintf(stderr, "There was an error getting the phich symbols\n");
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return SRSLTE_ERROR;
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}
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q_sf_symbols[j] = q->sf_symbols[j];
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/* extract channel estimates */
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for (i = 0; i < q->cell.nof_ports; i++) {
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if (SRSLTE_PHICH_MAX_NSYMB != srslte_regs_phich_get(q->regs, ce[i][j], q->ce[i][j], ngroup)) {
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fprintf(stderr, "There was an error getting the phich symbols\n");
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return SRSLTE_ERROR;
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}
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q_ce[i][j] = q->ce[i][j];
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}
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}
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/* in control channels, only diversity is supported */
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if (q->cell.nof_ports == 1) {
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/* no need for layer demapping */
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srslte_predecoding_single_multi(q_sf_symbols, q_ce[0], q->d0, q->nof_rx_antennas, SRSLTE_PHICH_MAX_NSYMB, noise_estimate);
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} else {
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srslte_predecoding_diversity_multi(q_sf_symbols, q_ce, x, q->nof_rx_antennas, q->cell.nof_ports, SRSLTE_PHICH_MAX_NSYMB);
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srslte_layerdemap_diversity(x, q->d0, q->cell.nof_ports, SRSLTE_PHICH_MAX_NSYMB / q->cell.nof_ports);
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}
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DEBUG("Recv!!: \n", 0);
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DEBUG("d0: ", 0);
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if (SRSLTE_VERBOSE_ISDEBUG())
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srslte_vec_fprint_c(stdout, q->d0, SRSLTE_PHICH_MAX_NSYMB);
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if (SRSLTE_CP_ISEXT(q->cell.cp)) {
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if (ngroup % 2) {
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for (i = 0; i < SRSLTE_PHICH_EXT_MSYMB / 2; i++) {
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q->d[2 * i + 0] = q->d0[4 * i + 2];
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q->d[2 * i + 1] = q->d0[4 * i + 3];
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}
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} else {
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for (i = 0; i < SRSLTE_PHICH_EXT_MSYMB / 2; i++) {
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q->d[2 * i + 0] = q->d0[4 * i];
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q->d[2 * i + 1] = q->d0[4 * i + 1];
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}
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}
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} else {
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memcpy(q->d, q->d0, SRSLTE_PHICH_MAX_NSYMB * sizeof(cf_t));
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}
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DEBUG("d: ", 0);
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if (SRSLTE_VERBOSE_ISDEBUG())
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srslte_vec_fprint_c(stdout, q->d, SRSLTE_PHICH_EXT_MSYMB);
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srslte_scrambling_c(&q->seq[subframe], q->d);
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/* De-spreading */
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if (SRSLTE_CP_ISEXT(q->cell.cp)) {
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for (i = 0; i < SRSLTE_PHICH_NBITS; i++) {
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q->z[i] = 0;
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for (j = 0; j < SRSLTE_PHICH_EXT_NSF; j++) {
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q->z[i] += conjf(w_ext[nseq][j])
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* q->d[i * SRSLTE_PHICH_EXT_NSF + j] / SRSLTE_PHICH_EXT_NSF;
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}
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}
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} else {
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for (i = 0; i < SRSLTE_PHICH_NBITS; i++) {
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q->z[i] = 0;
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for (j = 0; j < SRSLTE_PHICH_NORM_NSF; j++) {
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q->z[i] += conjf(w_normal[nseq][j])
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* q->d[i * SRSLTE_PHICH_NORM_NSF + j] / SRSLTE_PHICH_NORM_NSF;
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}
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}
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}
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DEBUG("z: ", 0);
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if (SRSLTE_VERBOSE_ISDEBUG())
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srslte_vec_fprint_c(stdout, q->z, SRSLTE_PHICH_NBITS);
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srslte_demod_soft_demodulate(SRSLTE_MOD_BPSK, q->z, q->data_rx, SRSLTE_PHICH_NBITS);
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if (ack) {
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*ack = srslte_phich_ack_decode(q->data_rx, distance);
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}
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return SRSLTE_SUCCESS;
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}
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/** Encodes ACK/NACK bits, modulates and inserts into resource.
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* The parameter ack is an array of srslte_phich_ngroups() pointers to buffers of nof_sequences uint8_ts
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*/
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int srslte_phich_encode(srslte_phich_t *q, uint8_t ack, uint32_t ngroup, uint32_t nseq, uint32_t subframe,
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cf_t *slot_symbols[SRSLTE_MAX_PORTS]) {
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int i;
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if (q == NULL || slot_symbols == NULL) {
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return SRSLTE_ERROR_INVALID_INPUTS;
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}
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if (subframe >= SRSLTE_NSUBFRAMES_X_FRAME) {
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fprintf(stderr, "Invalid nslot %d\n", subframe);
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return SRSLTE_ERROR_INVALID_INPUTS;
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}
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if (SRSLTE_CP_ISEXT(q->cell.cp)) {
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if (nseq >= SRSLTE_PHICH_EXT_NSEQUENCES) {
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fprintf(stderr, "Invalid nseq %d\n", nseq);
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return SRSLTE_ERROR_INVALID_INPUTS;
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}
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} else {
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if (nseq >= SRSLTE_PHICH_NORM_NSEQUENCES) {
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fprintf(stderr, "Invalid nseq %d\n", nseq);
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return SRSLTE_ERROR_INVALID_INPUTS;
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}
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}
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if (ngroup >= srslte_regs_phich_ngroups(q->regs)) {
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fprintf(stderr, "Invalid ngroup %d\n", ngroup);
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return SRSLTE_ERROR_INVALID_INPUTS;
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}
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/* Set pointers for layermapping & precoding */
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cf_t *x[SRSLTE_MAX_LAYERS];
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cf_t *symbols_precoding[SRSLTE_MAX_PORTS];
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/* number of layers equals number of ports */
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for (i = 0; i < q->cell.nof_ports; i++) {
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x[i] = q->x[i];
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}
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for (i = 0; i < SRSLTE_MAX_PORTS; i++) {
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symbols_precoding[i] = q->sf_symbols[i];
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}
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/* encode ACK/NACK bit */
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srslte_phich_ack_encode(ack, q->data);
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srslte_mod_modulate(&q->mod, q->data, q->z, SRSLTE_PHICH_NBITS);
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DEBUG("data: ", 0);
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if (SRSLTE_VERBOSE_ISDEBUG())
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srslte_vec_fprint_c(stdout, q->z, SRSLTE_PHICH_NBITS);
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/* Spread with w */
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if (SRSLTE_CP_ISEXT(q->cell.cp)) {
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for (i = 0; i < SRSLTE_PHICH_EXT_MSYMB; i++) {
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q->d[i] = w_ext[nseq][i % SRSLTE_PHICH_EXT_NSF]
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* q->z[i / SRSLTE_PHICH_EXT_NSF];
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}
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} else {
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for (i = 0; i < SRSLTE_PHICH_NORM_MSYMB; i++) {
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q->d[i] = w_normal[nseq][i % SRSLTE_PHICH_NORM_NSF]
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* q->z[i / SRSLTE_PHICH_NORM_NSF];
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}
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}
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DEBUG("d: ", 0);
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if (SRSLTE_VERBOSE_ISDEBUG())
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srslte_vec_fprint_c(stdout, q->d, SRSLTE_PHICH_EXT_MSYMB);
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srslte_scrambling_c(&q->seq[subframe], q->d);
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/* align to REG */
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if (SRSLTE_CP_ISEXT(q->cell.cp)) {
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if (ngroup % 2) {
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for (i = 0; i < SRSLTE_PHICH_EXT_MSYMB / 2; i++) {
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q->d0[4 * i + 0] = 0;
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q->d0[4 * i + 1] = 0;
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q->d0[4 * i + 2] = q->d[2 * i];
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q->d0[4 * i + 3] = q->d[2 * i + 1];
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}
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} else {
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for (i = 0; i < SRSLTE_PHICH_EXT_MSYMB / 2; i++) {
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q->d0[4 * i + 0] = q->d[2 * i];
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q->d0[4 * i + 1] = q->d[2 * i + 1];
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q->d0[4 * i + 2] = 0;
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q->d0[4 * i + 3] = 0;
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}
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}
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} else {
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memcpy(q->d0, q->d, SRSLTE_PHICH_MAX_NSYMB * sizeof(cf_t));
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}
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DEBUG("d0: ", 0);
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if (SRSLTE_VERBOSE_ISDEBUG())
|
|
srslte_vec_fprint_c(stdout, q->d0, SRSLTE_PHICH_MAX_NSYMB);
|
|
|
|
/* layer mapping & precoding */
|
|
if (q->cell.nof_ports > 1) {
|
|
srslte_layermap_diversity(q->d0, x, q->cell.nof_ports, SRSLTE_PHICH_MAX_NSYMB);
|
|
srslte_precoding_diversity(x, symbols_precoding, q->cell.nof_ports,
|
|
SRSLTE_PHICH_MAX_NSYMB / q->cell.nof_ports);
|
|
/**FIXME: According to 6.9.2, Precoding for 4 tx ports is different! */
|
|
} else {
|
|
memcpy(q->sf_symbols[0], q->d0, SRSLTE_PHICH_MAX_NSYMB * sizeof(cf_t));
|
|
}
|
|
|
|
/* mapping to resource elements */
|
|
for (i = 0; i < q->cell.nof_ports; i++) {
|
|
if (srslte_regs_phich_add(q->regs, q->sf_symbols[i], ngroup, slot_symbols[i])
|
|
< 0) {
|
|
fprintf(stderr, "Error putting PCHICH resource elements\n");
|
|
return SRSLTE_ERROR;
|
|
}
|
|
}
|
|
|
|
return SRSLTE_SUCCESS;
|
|
}
|
|
|