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/**
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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 <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 "liblte/phy/phch/regs.h"
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#include "liblte/phy/phch/phich.h"
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#include "liblte/phy/common/phy_common.h"
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#include "liblte/phy/utils/bit.h"
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#include "liblte/phy/utils/vector.h"
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#include "liblte/phy/utils/debug.h"
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/** Table 6.9.1-2 */
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const cf_t w_normal[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[PHICH_EXT_NSEQUENCES][2] = { { 1, 1 }, { 1, -1 }, { I, I }, {
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I, -I } };
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uint32_t phich_ngroups(phich_t *q) {
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return regs_phich_ngroups(q->regs);
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}
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void phich_reset(phich_t *q, cf_t *slot_symbols[MAX_PORTS]) {
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int i;
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for (i = 0; i < MAX_PORTS; i++) {
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regs_phich_reset(q->regs, slot_symbols[i]);
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}
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}
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/** Initializes the phich channel receiver */
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int phich_init(phich_t *q, regs_t *regs, lte_cell_t cell) {
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int ret = LIBLTE_ERROR_INVALID_INPUTS;
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if (q != NULL &&
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regs != NULL &&
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lte_cell_isvalid(&cell))
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{
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bzero(q, sizeof(phich_t));
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ret = LIBLTE_ERROR;
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q->cell = cell;
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q->regs = regs;
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if (precoding_init(&q->precoding, SF_LEN_RE(cell.nof_prb, cell.cp))) {
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fprintf(stderr, "Error initializing precoding\n");
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}
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if (modem_table_lte(&q->mod, LTE_BPSK, false)) {
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goto clean;
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}
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demod_hard_init(&q->demod);
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demod_hard_table_set(&q->demod, LTE_BPSK);
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for (int nsf = 0; nsf < NSUBFRAMES_X_FRAME; nsf++) {
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if (sequence_phich(&q->seq_phich[nsf], 2 * nsf, q->cell.id)) {
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goto clean;
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}
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}
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ret = LIBLTE_SUCCESS;
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}
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clean:
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if (ret == LIBLTE_ERROR) {
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phich_free(q);
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}
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return ret;
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}
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void phich_free(phich_t *q) {
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for (int ns = 0; ns < NSUBFRAMES_X_FRAME; ns++) {
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sequence_free(&q->seq_phich[ns]);
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}
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modem_table_free(&q->mod);
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precoding_free(&q->precoding);
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bzero(q, sizeof(phich_t));
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}
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/* Decodes ACK
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*
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*/
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uint8_t phich_ack_decode(uint8_t bits[PHICH_NBITS], uint32_t *distance) {
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int i, n;
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n = 0;
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for (i = 0; i < PHICH_NBITS; i++) {
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n += bits[i];
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}
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INFO("PHICH decoder: %d, %d, %d\n", bits[0], bits[1], bits[2]);
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if (n >= 2) {
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if (distance) {
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*distance = 3 - n;
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}
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return 1;
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} else {
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if (distance) {
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*distance = n;
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}
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return 0;
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}
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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 phich_ack_encode(uint8_t ack, uint8_t bits[PHICH_NBITS]) {
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memset(bits, ack, 3 * sizeof(uint8_t));
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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 phich_decode(phich_t *q, cf_t *slot_symbols, cf_t *ce[MAX_PORTS], float noise_estimate,
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uint32_t ngroup, uint32_t nseq, uint32_t subframe, uint8_t *ack, uint32_t *distance) {
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/* Set pointers for layermapping & precoding */
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int i, j;
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cf_t *x[MAX_LAYERS];
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cf_t *ce_precoding[MAX_PORTS];
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if (q == NULL || slot_symbols == NULL) {
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return LIBLTE_ERROR_INVALID_INPUTS;
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}
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if (subframe >= NSUBFRAMES_X_FRAME) {
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fprintf(stderr, "Invalid nslot %d\n", subframe);
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return LIBLTE_ERROR_INVALID_INPUTS;
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}
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if (CP_ISEXT(q->cell.cp)) {
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if (nseq >= PHICH_EXT_NSEQUENCES) {
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fprintf(stderr, "Invalid nseq %d\n", nseq);
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return LIBLTE_ERROR_INVALID_INPUTS;
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}
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} else {
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if (nseq >= PHICH_NORM_NSEQUENCES) {
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fprintf(stderr, "Invalid nseq %d\n", nseq);
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return LIBLTE_ERROR_INVALID_INPUTS;
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}
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}
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if (ngroup >= regs_phich_ngroups(q->regs)) {
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fprintf(stderr, "Invalid ngroup %d\n", ngroup);
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return LIBLTE_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 < MAX_PORTS; i++) {
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x[i] = q->phich_x[i];
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}
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for (i = 0; i < MAX_PORTS; i++) {
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ce_precoding[i] = q->ce[i];
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}
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/* extract symbols */
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if (PHICH_MAX_NSYMB
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!= regs_phich_get(q->regs, slot_symbols, q->phich_symbols[0], ngroup)) {
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fprintf(stderr, "There was an error getting the phich symbols\n");
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return LIBLTE_ERROR;
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}
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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 (PHICH_MAX_NSYMB != regs_phich_get(q->regs, ce[i], q->ce[i], ngroup)) {
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fprintf(stderr, "There was an error getting the phich symbols\n");
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return LIBLTE_ERROR;
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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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predecoding_single(&q->precoding, q->phich_symbols[0], q->ce[0], q->phich_d0,
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PHICH_MAX_NSYMB, noise_estimate);
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} else {
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predecoding_diversity(&q->precoding, q->phich_symbols[0], ce_precoding, x,
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q->cell.nof_ports, PHICH_MAX_NSYMB, noise_estimate);
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layerdemap_diversity(x, q->phich_d0, q->cell.nof_ports,
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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 (VERBOSE_ISDEBUG())
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vec_fprint_c(stdout, q->phich_d0, PHICH_MAX_NSYMB);
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if (CP_ISEXT(q->cell.cp)) {
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if (ngroup % 2) {
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for (i = 0; i < PHICH_EXT_MSYMB / 2; i++) {
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q->phich_d[2 * i + 0] = q->phich_d0[4 * i + 2];
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q->phich_d[2 * i + 1] = q->phich_d0[4 * i + 3];
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}
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} else {
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for (i = 0; i < PHICH_EXT_MSYMB / 2; i++) {
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q->phich_d[2 * i + 0] = q->phich_d0[4 * i];
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q->phich_d[2 * i + 1] = q->phich_d0[4 * i + 1];
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}
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}
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} else {
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memcpy(q->phich_d, q->phich_d0, PHICH_MAX_NSYMB * sizeof(cf_t));
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}
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DEBUG("d: ", 0);
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if (VERBOSE_ISDEBUG())
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vec_fprint_c(stdout, q->phich_d, PHICH_EXT_MSYMB);
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scrambling_c(&q->seq_phich[subframe], q->phich_d);
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/* De-spreading */
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if (CP_ISEXT(q->cell.cp)) {
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for (i = 0; i < PHICH_NBITS; i++) {
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q->phich_z[i] = 0;
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for (j = 0; j < PHICH_EXT_NSF; j++) {
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q->phich_z[i] += conjf(w_ext[nseq][j])
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* q->phich_d[i * PHICH_EXT_NSF + j] / PHICH_EXT_NSF;
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}
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}
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} else {
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for (i = 0; i < PHICH_NBITS; i++) {
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q->phich_z[i] = 0;
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for (j = 0; j < PHICH_NORM_NSF; j++) {
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q->phich_z[i] += conjf(w_normal[nseq][j])
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* q->phich_d[i * PHICH_NORM_NSF + j] / 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 (VERBOSE_ISDEBUG())
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vec_fprint_c(stdout, q->phich_z, PHICH_NBITS);
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demod_hard_demodulate(&q->demod, q->phich_z, q->data, PHICH_NBITS);
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if (ack) {
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*ack = phich_ack_decode(q->data, distance);
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}
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return LIBLTE_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 phich_ngroups() pointers to buffers of nof_sequences uint8_ts
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*/
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int phich_encode(phich_t *q, uint8_t ack, uint32_t ngroup, uint32_t nseq, uint32_t subframe,
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cf_t *slot_symbols[MAX_PORTS]) {
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int i;
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if (q == NULL || slot_symbols == NULL) {
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return LIBLTE_ERROR_INVALID_INPUTS;
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}
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if (subframe >= NSUBFRAMES_X_FRAME) {
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fprintf(stderr, "Invalid nslot %d\n", subframe);
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return LIBLTE_ERROR_INVALID_INPUTS;
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}
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if (CP_ISEXT(q->cell.cp)) {
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if (nseq >= PHICH_EXT_NSEQUENCES) {
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fprintf(stderr, "Invalid nseq %d\n", nseq);
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return LIBLTE_ERROR_INVALID_INPUTS;
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}
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} else {
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if (nseq >= PHICH_NORM_NSEQUENCES) {
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fprintf(stderr, "Invalid nseq %d\n", nseq);
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return LIBLTE_ERROR_INVALID_INPUTS;
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}
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}
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if (ngroup >= regs_phich_ngroups(q->regs)) {
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fprintf(stderr, "Invalid ngroup %d\n", ngroup);
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return LIBLTE_ERROR_INVALID_INPUTS;
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}
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/* Set pointers for layermapping & precoding */
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cf_t *x[MAX_LAYERS];
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cf_t *symbols_precoding[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->phich_x[i];
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}
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for (i = 0; i < MAX_PORTS; i++) {
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symbols_precoding[i] = q->phich_symbols[i];
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}
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/* encode ACK/NACK bit */
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phich_ack_encode(ack, q->data);
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mod_modulate(&q->mod, q->data, q->phich_z, PHICH_NBITS);
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DEBUG("data: ", 0);
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if (VERBOSE_ISDEBUG())
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vec_fprint_c(stdout, q->phich_z, PHICH_NBITS);
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/* Spread with w */
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if (CP_ISEXT(q->cell.cp)) {
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for (i = 0; i < PHICH_EXT_MSYMB; i++) {
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q->phich_d[i] = w_ext[nseq][i % PHICH_EXT_NSF]
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* q->phich_z[i / PHICH_EXT_NSF];
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}
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} else {
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for (i = 0; i < PHICH_NORM_MSYMB; i++) {
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q->phich_d[i] = w_normal[nseq][i % PHICH_NORM_NSF]
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* q->phich_z[i / PHICH_NORM_NSF];
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}
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}
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DEBUG("d: ", 0);
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if (VERBOSE_ISDEBUG())
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vec_fprint_c(stdout, q->phich_d, PHICH_EXT_MSYMB);
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|
scrambling_c(&q->seq_phich[subframe], q->phich_d);
|
|
|
|
|
|
|
|
/* align to REG */
|
|
|
|
if (CP_ISEXT(q->cell.cp)) {
|
|
|
|
if (ngroup % 2) {
|
|
|
|
for (i = 0; i < PHICH_EXT_MSYMB / 2; i++) {
|
|
|
|
q->phich_d0[4 * i + 0] = 0;
|
|
|
|
q->phich_d0[4 * i + 1] = 0;
|
|
|
|
q->phich_d0[4 * i + 2] = q->phich_d[2 * i];
|
|
|
|
q->phich_d0[4 * i + 3] = q->phich_d[2 * i + 1];
|
|
|
|
}
|
|
|
|
} else {
|
|
|
|
for (i = 0; i < PHICH_EXT_MSYMB / 2; i++) {
|
|
|
|
q->phich_d0[4 * i + 0] = q->phich_d[2 * i];
|
|
|
|
q->phich_d0[4 * i + 1] = q->phich_d[2 * i + 1];
|
|
|
|
q->phich_d0[4 * i + 2] = 0;
|
|
|
|
q->phich_d0[4 * i + 3] = 0;
|
|
|
|
}
|
|
|
|
}
|
|
|
|
} else {
|
|
|
|
memcpy(q->phich_d0, q->phich_d, PHICH_MAX_NSYMB * sizeof(cf_t));
|
|
|
|
}
|
|
|
|
|
|
|
|
DEBUG("d0: ", 0);
|
|
|
|
if (VERBOSE_ISDEBUG())
|
|
|
|
vec_fprint_c(stdout, q->phich_d0, PHICH_MAX_NSYMB);
|
|
|
|
|
|
|
|
/* layer mapping & precoding */
|
|
|
|
if (q->cell.nof_ports > 1) {
|
|
|
|
layermap_diversity(q->phich_d0, x, q->cell.nof_ports, PHICH_MAX_NSYMB);
|
|
|
|
precoding_diversity(&q->precoding, x, symbols_precoding, q->cell.nof_ports,
|
|
|
|
PHICH_MAX_NSYMB / q->cell.nof_ports);
|
|
|
|
/**FIXME: According to 6.9.2, Precoding for 4 tx ports is different! */
|
|
|
|
} else {
|
|
|
|
memcpy(q->phich_symbols[0], q->phich_d0, PHICH_MAX_NSYMB * sizeof(cf_t));
|
|
|
|
}
|
|
|
|
|
|
|
|
/* mapping to resource elements */
|
|
|
|
for (i = 0; i < q->cell.nof_ports; i++) {
|
|
|
|
if (regs_phich_add(q->regs, q->phich_symbols[i], ngroup, slot_symbols[i])
|
|
|
|
< 0) {
|
|
|
|
fprintf(stderr, "Error putting PCHICH resource elements\n");
|
|
|
|
return LIBLTE_ERROR;
|
|
|
|
}
|
|
|
|
}
|
|
|
|
|
|
|
|
return LIBLTE_SUCCESS;
|
|
|
|
}
|
|
|
|
|