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