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openairinterface5g/openair1/PHY/LTE_ESTIMATION/lte_est_freq_offset.c
T
Raymond Knopp b4635ac44f Clean-up and bug-fixes from S. Held (IMST) 
git-svn-id: http://svn.eurecom.fr/openair4G/trunk@6420 818b1a75-f10b-46b9-bf7c-635c3b92a50f
2015-01-22 07:24:06 +00:00

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/*******************************************************************************
OpenAirInterface
Copyright(c) 1999 - 2014 Eurecom
OpenAirInterface is free software: you can redistribute it and/or modify
it under the terms of the GNU General Public License as published by
the Free Software Foundation, either version 3 of the License, or
(at your option) any later version.
OpenAirInterface 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 General Public License for more details.
You should have received a copy of the GNU General Public License
along with OpenAirInterface.The full GNU General Public License is
included in this distribution in the file called "COPYING". If not,
see <http://www.gnu.org/licenses/>.
Contact Information
OpenAirInterface Admin: openair_admin@eurecom.fr
OpenAirInterface Tech : openair_tech@eurecom.fr
OpenAirInterface Dev : openair4g-devel@eurecom.fr
Address : Eurecom, Campus SophiaTech, 450 Route des Chappes, CS 50193 - 06904 Biot Sophia Antipolis cedex, FRANCE
*******************************************************************************/
/*
file: lte_est_freq_offset.c
author (c): florian.kaltenberger@eurecom.fr
date: 19.11.2009
*/
#include "PHY/defs.h"
//#define DEBUG_PHY
__m128i avg128F;
//compute average channel_level on each (TX,RX) antenna pair
int dl_channel_level(int16_t *dl_ch,
LTE_DL_FRAME_PARMS *frame_parms) {
int16_t rb;
__m128i *dl_ch128;
int avg;
//clear average level
avg128F = _mm_setzero_si128();
dl_ch128=(__m128i *)dl_ch;
for (rb=0;rb<frame_parms->N_RB_DL;rb++) {
avg128F = _mm_add_epi32(avg128F,_mm_madd_epi16(dl_ch128[0],dl_ch128[0]));
avg128F = _mm_add_epi32(avg128F,_mm_madd_epi16(dl_ch128[1],dl_ch128[1]));
avg128F = _mm_add_epi32(avg128F,_mm_madd_epi16(dl_ch128[2],dl_ch128[2]));
dl_ch128+=3;
}
avg = (((int*)&avg128F)[0] +
((int*)&avg128F)[1] +
((int*)&avg128F)[2] +
((int*)&avg128F)[3])/(frame_parms->N_RB_DL*12);
_mm_empty();
_m_empty();
return(avg);
}
int lte_est_freq_offset(int **dl_ch_estimates,
LTE_DL_FRAME_PARMS *frame_parms,
int l,
int* freq_offset) {
int ch_offset, omega, dl_ch_shift;
struct complex16 *omega_cpx;
double phase_offset;
int freq_offset_est;
unsigned char aa;
int16_t *dl_ch,*dl_ch_prev;
static int first_run = 1;
int coef = 1<<10;
int ncoef = 32767 - coef;
ch_offset = (l*(frame_parms->ofdm_symbol_size));
if ((l!=0) && (l!=(4-frame_parms->Ncp))) {
msg("lte_est_freq_offset: l (%d) must be 0 or %d\n",l,4-frame_parms->Ncp);
return(-1);
}
phase_offset = 0.0;
// for (aa=0;aa<frame_parms->nb_antennas_rx*frame_parms->nb_antennas_tx;aa++) {
for (aa=0;aa<1;aa++) {
dl_ch = (int16_t *)&dl_ch_estimates[aa][12+ch_offset];
dl_ch_shift = 6+(log2_approx(dl_channel_level(dl_ch,frame_parms))/2);
// printf("dl_ch_shift: %d\n",dl_ch_shift);
if (ch_offset == 0)
dl_ch_prev = (int16_t *)&dl_ch_estimates[aa][12+(4-frame_parms->Ncp)*(frame_parms->ofdm_symbol_size)];
else
dl_ch_prev = (int16_t *)&dl_ch_estimates[aa][12+0];
// calculate omega = angle(conj(dl_ch)*dl_ch_prev))
// printf("Computing freq_offset\n");
omega = dot_product(dl_ch,dl_ch_prev,(frame_parms->N_RB_DL/2 - 1)*12,dl_ch_shift);
//omega = dot_product(dl_ch,dl_ch_prev,frame_parms->ofdm_symbol_size,15);
omega_cpx = (struct complex16*) &omega;
// printf("omega (%d,%d)\n",omega_cpx->r,omega_cpx->i);
dl_ch = (int16_t *)&dl_ch_estimates[aa][(((frame_parms->N_RB_DL/2) + 1)*12) + ch_offset];
if (ch_offset == 0)
dl_ch_prev = (int16_t *)&dl_ch_estimates[aa][(((frame_parms->N_RB_DL/2) + 1)*12)+(4-frame_parms->Ncp)*(frame_parms->ofdm_symbol_size)];
else
dl_ch_prev = (int16_t *)&dl_ch_estimates[aa][((frame_parms->N_RB_DL/2) + 1)*12];
// calculate omega = angle(conj(dl_ch)*dl_ch_prev))
omega = dot_product(dl_ch,dl_ch_prev,((frame_parms->N_RB_DL/2) - 1)*12,dl_ch_shift);
omega_cpx->r += ((struct complex16*) &omega)->r;
omega_cpx->i += ((struct complex16*) &omega)->i;
// phase_offset += atan2((double)omega_cpx->i,(double)omega_cpx->r);
phase_offset += atan2((double)omega_cpx->i,(double)omega_cpx->r);
// LOG_D(PHY,"omega (%d,%d) -> %f\n",omega_cpx->r,omega_cpx->i,phase_offset);
}
// phase_offset /= (frame_parms->nb_antennas_rx*frame_parms->nb_antennas_tx);
freq_offset_est = (int) (phase_offset/(2*M_PI)/(frame_parms->Ncp==NORMAL ? (285.8e-6):(2.5e-4))); //2.5e-4 is the time between pilot symbols
// LOG_D(PHY,"symbol %d : freq_offset_est %d\n",l,freq_offset_est);
// update freq_offset with phase_offset using a moving average filter
if (first_run == 1) {
*freq_offset = freq_offset_est;
first_run = 0;
}
else
*freq_offset = ((freq_offset_est * coef) + (*freq_offset * ncoef)) >> 15;
//#ifdef DEBUG_PHY
// msg("l=%d, phase_offset = %f (%d,%d), freq_offset_est = %d Hz, freq_offset_filt = %d \n",l,phase_offset,omega_cpx->r,omega_cpx->i,freq_offset_est,*freq_offset);
/*
for (i=0;i<150;i++)
msg("i %d : %d,%d <=> %d,%d\n",i,dl_ch[2*i],dl_ch[(2*i)+1],dl_ch_prev[2*i],dl_ch_prev[(2*i)+1]);
*/
//#endif
return(0);
}
//******************************************************************************************************
// LTE MBSFN Frequency offset estimation
int lte_mbsfn_est_freq_offset(int **dl_ch_estimates,
LTE_DL_FRAME_PARMS *frame_parms,
int l,
int* freq_offset) {
int ch_offset, omega, dl_ch_shift;
struct complex16 *omega_cpx;
double phase_offset;
int freq_offset_est;
unsigned char aa;
int16_t *dl_ch,*dl_ch_prev;
static int first_run = 1;
int coef = 1<<10;
int ncoef = 32767 - coef;
ch_offset = (l*(frame_parms->ofdm_symbol_size));
if ((l!=2) && (l!=6) && (l!=10)) {
msg("lte_est_freq_offset: l (%d) must be 2 or 6 or 10", l);
return(-1);
}
phase_offset = 0.0;
// for (aa=0;aa<frame_parms->nb_antennas_rx*frame_parms->nb_antennas_tx;aa++) {
for (aa=0;aa<1;aa++) {
dl_ch = (int16_t *)&dl_ch_estimates[aa][12+ch_offset];
dl_ch_shift = 4+(log2_approx(dl_channel_level(dl_ch,frame_parms))/2);
// printf("dl_ch_shift: %d\n",dl_ch_shift);
if (ch_offset == 0)
dl_ch_prev = (int16_t *)&dl_ch_estimates[aa][12+(10*(frame_parms->ofdm_symbol_size))];
else
dl_ch_prev = (int16_t *)&dl_ch_estimates[aa][12+6];
//else if
// dl_ch_prev = (int16_t *)&dl_ch_estimates[aa][12+0];
// calculate omega = angle(conj(dl_ch)*dl_ch_prev))
// printf("Computing freq_offset\n");
omega = dot_product(dl_ch,dl_ch_prev,(frame_parms->N_RB_DL/2 - 1)*12,dl_ch_shift);
//omega = dot_product(dl_ch,dl_ch_prev,frame_parms->ofdm_symbol_size,15);
omega_cpx = (struct complex16*) &omega;
// printf("omega (%d,%d)\n",omega_cpx->r,omega_cpx->i);
dl_ch = (int16_t *)&dl_ch_estimates[aa][(((frame_parms->N_RB_DL/2) + 1)*12) + ch_offset];
if (ch_offset == 0)
dl_ch_prev = (int16_t *)&dl_ch_estimates[aa][(((frame_parms->N_RB_DL/2) + 1)*12)+10*(frame_parms->ofdm_symbol_size)];
else
dl_ch_prev = (int16_t *)&dl_ch_estimates[aa][((frame_parms->N_RB_DL/2) + 1)*12+6];
// calculate omega = angle(conj(dl_ch)*dl_ch_prev))
omega = dot_product(dl_ch,dl_ch_prev,((frame_parms->N_RB_DL/2) - 1)*12,dl_ch_shift);
omega_cpx->r += ((struct complex16*) &omega)->r;
omega_cpx->i += ((struct complex16*) &omega)->i;
// phase_offset += atan2((double)omega_cpx->i,(double)omega_cpx->r);
phase_offset += atan2((double)omega_cpx->i,(double)omega_cpx->r);
// printf("omega (%d,%d) -> %f\n",omega_cpx->r,omega_cpx->i,phase_offset);
}
// phase_offset /= (frame_parms->nb_antennas_rx*frame_parms->nb_antennas_tx);
freq_offset_est = (int) (phase_offset/(2*M_PI)/2.5e-4); //2.5e-4 is the time between pilot symbols
// printf("symbol %d : freq_offset_est %d\n",l,freq_offset_est);
// update freq_offset with phase_offset using a moving average filter
if (first_run == 1) {
*freq_offset = freq_offset_est;
first_run = 0;
}
else
*freq_offset = ((freq_offset_est * coef) + (*freq_offset * ncoef)) >> 15;
//#ifdef DEBUG_PHY
// msg("l=%d, phase_offset = %f (%d,%d), freq_offset_est = %d Hz, freq_offset_filt = %d \n",l,phase_offset,omega_cpx->r,omega_cpx->i,freq_offset_est,*freq_offset);
/*
for (i=0;i<150;i++)
msg("i %d : %d,%d <=> %d,%d\n",i,dl_ch[2*i],dl_ch[(2*i)+1],dl_ch_prev[2*i],dl_ch_prev[(2*i)+1]);
*/
//#endif
return(0);
}
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