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216 lines
6.0 KiB
C
216 lines
6.0 KiB
C
/**
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*
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* \section COPYRIGHT
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*
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* Copyright 2013-2014 The libLTE Developers. See the
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* COPYRIGHT file at the top-level directory of this distribution.
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*
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* \section LICENSE
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*
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* This file is part of the libLTE library.
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*
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* libLTE is free software: you can redistribute it and/or modify
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* it under the terms of the GNU Lesser General Public License as
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* published by the Free Software Foundation, either version 3 of
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* the License, or (at your option) any later version.
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*
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* libLTE is distributed in the hope that it will be useful,
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* but WITHOUT ANY WARRANTY; without even the implied warranty of
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* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
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* GNU Lesser General Public License for more details.
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*
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* A copy of the GNU Lesser General Public License can be found in
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* the LICENSE file in the top-level directory of this distribution
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* and at http://www.gnu.org/licenses/.
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*
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*/
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#include <stdio.h>
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#include <assert.h>
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#include <complex.h>
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#include <string.h>
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#include <math.h>
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#include "lte/common/base.h"
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#include "lte/mimo/precoding.h"
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#include "lte/utils/vector.h"
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int precoding_single(cf_t *x, cf_t *y, int nof_symbols) {
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memcpy(y, x, nof_symbols * sizeof(cf_t));
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return nof_symbols;
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}
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int precoding_diversity(cf_t *x[MAX_LAYERS], cf_t *y[MAX_PORTS], int nof_ports, int nof_symbols) {
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int i;
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if (nof_ports == 2) {
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/* FIXME: Use VOLK here */
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for (i=0;i<nof_symbols;i++) {
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y[0][2*i] = x[0][i]/sqrtf(2);
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y[1][2*i] = -conjf(x[1][i])/sqrtf(2);
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y[0][2*i+1] = x[1][i]/sqrtf(2);
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y[1][2*i+1] = conjf(x[0][i])/sqrtf(2);
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}
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return 2*i;
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} else if (nof_ports == 4) {
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//int m_ap = (nof_symbols%4)?(nof_symbols*4-2):nof_symbols*4;
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int m_ap = 4 * nof_symbols;
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for (i=0;i<m_ap/4;i++) {
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y[0][4*i] = x[0][i]/sqrtf(2);
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y[1][4*i] = 0;
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y[2][4*i] = -conjf(x[1][i])/sqrtf(2);
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y[3][4*i] = 0;
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y[0][4*i+1] = x[1][i]/sqrtf(2);
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y[1][4*i+1] = 0;
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y[2][4*i+1] = conjf(x[0][i])/sqrtf(2);
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y[3][4*i+1] = 0;
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y[0][4*i+2] = 0;
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y[1][4*i+2] = x[2][i]/sqrtf(2);
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y[2][4*i+2] = 0;
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y[3][4*i+2] = -conjf(x[3][i])/sqrtf(2);
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y[0][4*i+3] = 0;
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y[1][4*i+3] = x[3][i]/sqrtf(2);
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y[2][4*i+3] = 0;
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y[3][4*i+3] = conjf(x[2][i])/sqrtf(2);
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}
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return 4*i;
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} else {
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fprintf(stderr, "Number of ports must be 2 or 4 for transmit diversity\n");
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return -1;
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}
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}
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/* 36.211 v10.3.0 Section 6.3.4 */
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int precoding_type(cf_t *x[MAX_LAYERS], cf_t *y[MAX_PORTS], int nof_layers, int nof_ports, int nof_symbols,
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mimo_type_t type) {
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if (nof_ports > MAX_PORTS) {
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fprintf(stderr, "Maximum number of ports is %d (nof_ports=%d)\n", MAX_PORTS, nof_ports);
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return -1;
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}
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if (nof_layers > MAX_LAYERS) {
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fprintf(stderr, "Maximum number of layers is %d (nof_layers=%d)\n", MAX_LAYERS, nof_layers);
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return -1;
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}
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switch(type) {
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case SINGLE_ANTENNA:
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if (nof_ports == 1 && nof_layers == 1) {
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return precoding_single(x[0], y[0], nof_symbols);
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} else {
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fprintf(stderr, "Number of ports and layers must be 1 for transmission on single antenna ports\n");
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return -1;
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}
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break;
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case TX_DIVERSITY:
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if (nof_ports == nof_layers) {
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return precoding_diversity(x, y, nof_ports, nof_symbols);
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} else {
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fprintf(stderr, "Error number of layers must equal number of ports in transmit diversity\n");
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return -1;
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}
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case SPATIAL_MULTIPLEX:
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fprintf(stderr, "Spatial multiplexing not supported\n");
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return -1;
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}
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return 0;
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}
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/* ZF detector */
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int predecoding_single_zf(cf_t *y, cf_t *ce, cf_t *x, int nof_symbols) {
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vec_div_ccc(y, ce, x, nof_symbols);
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return nof_symbols;
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}
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/* ZF detector */
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int predecoding_diversity_zf(cf_t *y[MAX_PORTS], cf_t *ce[MAX_PORTS],
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cf_t *x[MAX_LAYERS], int nof_ports, int nof_symbols) {
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int i;
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cf_t h0, h1, h2, h3, r0, r1, r2, r3;
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float hh, hh02, hh13;
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if (nof_ports == 2) {
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/* TODO: Use VOLK here */
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for (i=0;i<nof_symbols/2;i++) {
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h0 = ce[0][2*i];
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h1 = ce[1][2*i];
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hh = crealf(h0)*crealf(h0)+cimagf(h0)*cimagf(h0)+
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crealf(h1)*crealf(h1)+cimagf(h1)*cimagf(h1);
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r0 = y[0][2*i];
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r1 = y[0][2*i+1];
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x[0][i] = (conjf(h0)*r0 + h1*conjf(r1))/hh * sqrt(2);
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x[1][i] = (-h1*conj(r0) + conj(h0)*r1)/hh * sqrt(2);
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}
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return i;
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} else if (nof_ports == 4) {
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int m_ap = (nof_symbols%4)?((nof_symbols-2)/4):nof_symbols/4;
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for (i=0;i<m_ap;i++) {
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h0 = ce[0][4*i];
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h1 = ce[1][4*i+2];
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h2 = ce[2][4*i];
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h3 = ce[3][4*i+2];
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hh02 = crealf(h0)*crealf(h0)+cimagf(h0)*cimagf(h0)
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+ crealf(h2)*crealf(h2)+cimagf(h2)*cimagf(h2);
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hh13 = crealf(h1)*crealf(h1)+cimagf(h1)*cimagf(h1)
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+ crealf(h3)*crealf(h3)+cimagf(h3)*cimagf(h3);
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r0 = y[0][4*i];
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r1 = y[0][4*i+1];
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r2 = y[0][4*i+2];
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r3 = y[0][4*i+3];
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x[0][i] = (conjf(h0)*r0 + h2*conjf(r1))/hh02 * sqrt(2);
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x[1][i] = (-h2*conjf(r0) + conjf(h0)*r1)/hh02 * sqrt(2);
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x[2][i] = (conjf(h1)*r2 + h3*conjf(r3))/hh13 * sqrt(2);
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x[3][i] = (-h3*conjf(r2) + conjf(h1)*r3)/hh13 * sqrt(2);
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}
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return i;
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} else {
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fprintf(stderr, "Number of ports must be 2 or 4 for transmit diversity\n");
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return -1;
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}
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}
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/* 36.211 v10.3.0 Section 6.3.4 */
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int predecoding_type(cf_t *y[MAX_PORTS], cf_t *ce[MAX_PORTS],
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cf_t *x[MAX_LAYERS], int nof_ports, int nof_layers, int nof_symbols, mimo_type_t type) {
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if (nof_ports > MAX_PORTS) {
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fprintf(stderr, "Maximum number of ports is %d (nof_ports=%d)\n", MAX_PORTS, nof_ports);
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return -1;
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}
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if (nof_layers > MAX_LAYERS) {
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fprintf(stderr, "Maximum number of layers is %d (nof_layers=%d)\n", MAX_LAYERS, nof_layers);
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return -1;
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}
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switch(type) {
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case SINGLE_ANTENNA:
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if (nof_ports == 1 && nof_layers == 1) {
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return predecoding_single_zf(y[0], ce[0], x[0], nof_symbols);
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} else{
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fprintf(stderr, "Number of ports and layers must be 1 for transmission on single antenna ports\n");
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return -1;
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}
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break;
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case TX_DIVERSITY:
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if (nof_ports == nof_layers) {
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return predecoding_diversity_zf(y, ce, x, nof_ports, nof_symbols);
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} else {
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fprintf(stderr, "Error number of layers must equal number of ports in transmit diversity\n");
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return -1;
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}
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break;
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case SPATIAL_MULTIPLEX:
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fprintf(stderr, "Spatial multiplexing not supported\n");
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return -1;
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}
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return 0;
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}
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