157 lines
4.6 KiB
C
157 lines
4.6 KiB
C
/*
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* Licensed to the OpenAirInterface (OAI) Software Alliance under one or more
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* contributor license agreements. See the NOTICE file distributed with
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* this work for additional information regarding copyright ownership.
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* The OpenAirInterface Software Alliance licenses this file to You under
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* the OAI Public License, Version 1.1 (the "License"); you may not use this file
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* except in compliance with the License.
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* You may obtain a copy of the License at
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*
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* http://www.openairinterface.org/?page_id=698
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*
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* Unless required by applicable law or agreed to in writing, software
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* distributed under the License is distributed on an "AS IS" BASIS,
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* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
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* See the License for the specific language governing permissions and
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* limitations under the License.
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*-------------------------------------------------------------------------------
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* For more information about the OpenAirInterface (OAI) Software Alliance:
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* contact@openairinterface.org
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*/
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/*! \file PHY/LTE_TRANSPORT/pcfich.c
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* \brief Top-level routines for generating and decoding the PCFICH/CFI physical/transport channel V8.6 2009-03
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* \author R. Knopp
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* \date 2011
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* \version 0.1
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* \company Eurecom
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* \email: knopp@eurecom.fr
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* \note
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* \warning
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*/
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#include "PHY/defs_UE.h"
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#include "PHY/LTE_REFSIG/lte_refsig.h"
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//#define DEBUG_PCFICH
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#include "openair1/PHY/LTE_TRANSPORT/transport_vars.h"
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void pcfich_unscrambling(LTE_DL_FRAME_PARMS *frame_parms,
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uint8_t subframe,
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int16_t *d)
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{
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uint8_t reset = 1;
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uint32_t x1 = 0; // x1 is set in lte_gold_generic
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uint32_t s = 0;
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uint32_t x2 = ((((2*frame_parms->Nid_cell)+1)*(1+subframe))<<9) + frame_parms->Nid_cell; //this is c_init in 36.211 Sec 6.7.1
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for (uint32_t i=0; i<32; i++) {
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if ((i&0x1f)==0) {
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s = lte_gold_generic(&x1, &x2, reset);
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//printf("lte_gold[%d]=%x\n",i,s);
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reset = 0;
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}
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if (((s>>(i&0x1f))&1) == 1)
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d[i]=-d[i];
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}
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}
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uint8_t rx_pcfich(LTE_DL_FRAME_PARMS *frame_parms,
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uint8_t subframe,
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LTE_UE_PDCCH *lte_ue_pdcch_vars,
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MIMO_mode_t mimo_mode)
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{
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uint8_t pcfich_quad;
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uint8_t i,j;
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uint16_t reg_offset;
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int32_t **rxdataF_comp = lte_ue_pdcch_vars->rxdataF_comp;
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int16_t pcfich_d[32],*pcfich_d_ptr;
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int32_t metric,old_metric=-16384;
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uint8_t num_pdcch_symbols=3;
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uint16_t *pcfich_reg = frame_parms->pcfich_reg;
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// demapping
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// loop over 4 quadruplets and lookup REGs
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// m=0;
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pcfich_d_ptr = pcfich_d;
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for (pcfich_quad=0; pcfich_quad<4; pcfich_quad++) {
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reg_offset = (pcfich_reg[pcfich_quad]*4);
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for (i=0; i<4; i++) {
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pcfich_d_ptr[0] = ((int16_t*)&rxdataF_comp[0][reg_offset+i])[0]; // RE component
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pcfich_d_ptr[1] = ((int16_t*)&rxdataF_comp[0][reg_offset+i])[1]; // IM component
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#ifdef DEBUG_PCFICH
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printf("rx_pcfich: quad %d, i %d, offset %d => (%d,%d) => pcfich_d_ptr[0] %d \n",pcfich_quad,i,reg_offset+i,
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((int16_t*)&rxdataF_comp[0][reg_offset+i])[0],
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((int16_t*)&rxdataF_comp[0][reg_offset+i])[1],
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pcfich_d_ptr[0]);
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#endif
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pcfich_d_ptr+=2;
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}
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/*
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}
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else { // ALAMOUTI
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for (i=0;i<4;i+=2) {
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pcfich_d_ptr[0] = 0;
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pcfich_d_ptr[1] = 0;
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pcfich_d_ptr[2] = 0;
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pcfich_d_ptr[3] = 0;
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for (j=0;j<frame_parms->nb_antennas_rx;j++) {
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pcfich_d_ptr[0] += (((int16_t*)&rxdataF_comp[j][reg_offset+i])[0]+
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((int16_t*)&rxdataF_comp[j+2][reg_offset+i+1])[0]); // RE component
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pcfich_d_ptr[1] += (((int16_t*)&rxdataF_comp[j][reg_offset+i])[1] -
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((int16_t*)&rxdataF_comp[j+2][reg_offset+i+1])[1]);// IM component
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pcfich_d_ptr[2] += (((int16_t*)&rxdataF_comp[j][reg_offset+i+1])[0]-
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((int16_t*)&rxdataF_comp[j+2][reg_offset+i])[0]); // RE component
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pcfich_d_ptr[3] += (((int16_t*)&rxdataF_comp[j][reg_offset+i+1])[1] +
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((int16_t*)&rxdataF_comp[j+2][reg_offset+i])[1]);// IM component
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}
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pcfich_d_ptr+=4;
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}
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*/
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}
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// pcfhich unscrambling
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pcfich_unscrambling(frame_parms,subframe,pcfich_d);
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// pcfich detection
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for (i=0; i<3; i++) {
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metric = 0;
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for (j=0; j<32; j++) {
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// printf("pcfich_b[%d][%d] %d => pcfich_d[%d] %d\n",i,j,pcfich_b[i][j],j,pcfich_d[j]);
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metric += (int32_t)(((pcfich_b[i][j]==0) ? (pcfich_d[j]) : (-pcfich_d[j])));
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}
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#ifdef DEBUG_PCFICH
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printf("metric %d : %d\n",i,metric);
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#endif
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if (metric > old_metric) {
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num_pdcch_symbols = 1+i;
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old_metric = metric;
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}
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}
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#ifdef DEBUG_PCFICH
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printf("[PHY] PCFICH detected for %d PDCCH symbols\n",num_pdcch_symbols);
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#endif
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return(num_pdcch_symbols);
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}
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