206 lines
6.5 KiB
C
206 lines
6.5 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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#include <stdio.h>
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#include <stdlib.h>
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#include <math.h>
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#include <string.h>
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#include "sim.h"
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#include "SIMULATION/RF/rf.h"
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#include <complex.h>
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void tv_channel(channel_desc_t *desc,double complex ***H,uint32_t length);
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double frand_a_b(double a, double b);
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void tv_conv(double complex **h, double complex *x, double complex *y, uint32_t nb_samples, uint8_t nb_taps, int delay);
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void multipath_tv_channel(channel_desc_t *desc,
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double **tx_sig_re,
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double **tx_sig_im,
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double **rx_sig_re,
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double **rx_sig_im,
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uint32_t length,
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uint8_t keep_channel)
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{
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double complex **tx,**rx,***H_t;
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double path_loss = pow(10,desc->path_loss_dB/20);
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int i,j,dd;
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dd = abs(desc->channel_offset);
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#ifdef DEBUG_CH
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printf("[TV CHANNEL] keep = %d : path_loss = %g (%f), nb_rx %d, nb_tx %d, dd %d, len %d max_doppler %g\n",keep_channel,path_loss,desc->path_loss_dB,desc->nb_rx,desc->nb_tx,dd,desc->channel_length,
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desc->max_Doppler);
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#endif
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tx = (double complex **)malloc(desc->nb_tx*sizeof(double complex *));
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rx = (double complex **)malloc(desc->nb_rx*sizeof(double complex *));
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H_t= (double complex ***) malloc(desc->nb_tx*desc->nb_rx*sizeof(double complex **));
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for(i=0; i<desc->nb_tx; i++) {
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tx[i] = (double complex *)calloc(length,sizeof(double complex));
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}
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for(i=0; i<desc->nb_rx; i++) {
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rx[i] = (double complex *)calloc(length,sizeof(double complex));
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}
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for(i=0; i<desc->nb_tx*desc->nb_rx; i++) {
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H_t[i] = (double complex **)malloc(desc->nb_taps*sizeof(double complex *));
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for(j=0; j<desc->nb_taps; j++) {
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H_t[i][j] = (double complex *)calloc(length,sizeof(double complex));
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}
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}
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for (i=0; i<desc->nb_tx; i++) {
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for(j=0; j<length; j++) {
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tx[i][j] = tx_sig_re[i][j] +I*tx_sig_im[i][j];
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}
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}
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if (keep_channel) {
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// do nothing - keep channel
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} else {
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tv_channel(desc,H_t,length);
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}
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for(i=0; i<desc->nb_rx; i++) {
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for(j=0; j<desc->nb_tx; j++) {
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tv_conv(H_t[i+(j*desc->nb_rx)],tx[j],rx[i],length,desc->nb_taps,dd);
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}
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}
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for(i=0; i<desc->nb_rx; i++) {
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for(j=0; j<length; j++) {
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rx_sig_re[i][j] = creal(rx[i][j])*path_loss;
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rx_sig_im[i][j] = cimag(rx[i][j])*path_loss;
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}
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}
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for(i=0; i<desc->nb_tx; i++) {
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free(tx[i]);
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}
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free(tx);
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for(i=0; i<desc->nb_rx; i++) {
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free(rx[i]);
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}
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free(rx);
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for(i=0; i<desc->nb_rx*desc->nb_tx; i++) {
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for(j=0; j<desc->nb_taps; j++) {
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free(H_t[i][j]);
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}
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free(H_t[i]);
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}
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free(H_t);
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}
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//TODO: make phi_rad a parameter of this function
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void tv_channel(channel_desc_t *desc,double complex ***H,uint32_t length){
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int i,j,p,l,k;
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double *alpha,***phi_rad,pi=acos(-1),***w_Hz;
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alpha = (double *)calloc(desc->nb_paths,sizeof(double));
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phi_rad = (double ***)malloc(desc->nb_rx*desc->nb_tx*sizeof(double **));
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w_Hz = (double ***)malloc(desc->nb_rx*desc->nb_tx*sizeof(double **));
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for(i=0; i<desc->nb_tx*desc->nb_rx; i++) {
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phi_rad[i] = (double **) malloc(desc->nb_taps*sizeof(double *));
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w_Hz[i] = (double **) malloc(desc->nb_taps*sizeof(double *));
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for(j=0; j<desc->nb_taps; j++) {
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phi_rad[i][j] = (double *) malloc(desc->nb_paths*sizeof(double));
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w_Hz[i][j] = (double *) malloc(desc->nb_paths*sizeof(double));
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}
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}
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for(i=0; i<desc->nb_tx*desc->nb_rx; i++) {
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for (j = 0; j<desc->nb_taps; j++) {
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for(k=0; k<desc->nb_paths; k++) {
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w_Hz[i][j][k] = desc->max_Doppler*cos(frand_a_b(0,2*M_PI));
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phi_rad[i][j][k] = frand_a_b(0,2*M_PI);
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//printf("w_hz[%d][%d][%d]=f_d*cos(theta) = %f\n",i,j,k,w_Hz[i][j][k]);
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//printf("phi_rad[%d][%d][%d] = %f\n",i,j,k,phi_rad[i][j][k]);
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}
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}
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}
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if(desc->ricean_factor == 1) {
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for(i=0; i<desc->nb_paths; i++) {
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alpha[i]=1/sqrt(desc->nb_paths);
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}
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} else {
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alpha[0]=sqrt(desc->ricean_factor/(desc->ricean_factor+1));
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for(i=1; i<desc->nb_paths; i++) {
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alpha[i] = (1/sqrt(desc->nb_paths-1))*(sqrt(1/(desc->ricean_factor+1)));
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}
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}
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// SISO or MIMO
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for (i=0; i<desc->nb_rx; i++) {
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for(j=0; j<desc->nb_tx; j++) {
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for(k=0; k<desc->nb_taps; k++) {
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for(l=0; l<length; l++) {
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for(p=0; p<desc->nb_paths; p++) {
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H[i+(j*desc->nb_rx)][k][l] += sqrt(desc->amps[k])*alpha[p]*cexp(I*(2*pi*w_Hz[i+(j*desc->nb_rx)][k][p]*l*(1/(desc->sampling_rate*1e6))+phi_rad[i+(j*desc->nb_rx)][k][p]));
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}
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}
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//printf("H[tx%d][rx%d][k%d][l%d] = %f+j%f \n",j,i,k,0,creal(H[i+(j*desc->nb_rx)][k][0]),cimag(H[i+(j*desc->nb_rx)][k][0]));
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}
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}
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}
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//accumlate the phase
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/*for(k=0; k<desc->nb_taps; k++) {
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* for(j=0; j<desc->nb_paths; j++) {
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* desc->random_phase[k][j] = fmod(2*pi*w_Hz[k][j]*(length-1)*(1/(desc->sampling_rate*1e6))+phi_rad[k][j],2*pi);
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* }
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* }*/
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free(alpha);
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for(i=0; i<desc->nb_rx*desc->nb_tx; i++) {
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for (j=0; j<desc->nb_taps; j++) {
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free(w_Hz[i][j]);
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free(phi_rad[i][j]);
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}
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free(w_Hz[i]);
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free(phi_rad[i]);
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}
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free(w_Hz);
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free(phi_rad);
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}
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// time varying convolution
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void tv_conv(double complex **h, double complex *x, double complex *y, uint32_t nb_samples, uint8_t nb_taps, int dd)
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{
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for(int i = 0; i < ((int)nb_samples-dd); i++) {
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for(int j = 0; j < nb_taps; j++) {
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if(i >= j)
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y[i+dd] += h[j][i] * x[i-j];
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}
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}
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}
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double frand_a_b(double a, double b) {
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return (rand()/(double)RAND_MAX)*(b-a)+a;
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}
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