channel.c

B3g_phase2_C语言_Matlab程序及说明

/***********************************
*Copyright (C) 2004 FUTURE@NCRL SEU
*All Rights Reserved.

*FileName: _CHANNEL_C_

*Abstract: Get the MIMO Channel's TDL Coef.

*Cur.Ver : 2.0
*Author  : Bin Jiang
*Date    : 2004-04-13 
*Modify  : To save memory, the channel coef is 
           computed online for one sample time.

*Per.Ver : 1.0
*Author  : Bin Jiang
*Date    : 2003-12-8

*Ref.    : D.M. Wang's program.

**********************************/

//Includes Files
#include <stdio.h>
#include <stdlib.h>
#include <math.h>

#include "common.h"
#include "channel.h"

int GenCommonData(double * alpha, double * beta)
{
	int n;
	int n_PathNum;
	
	int N0 = 25;
	int N  = 4*N0;
	int n_TotalPathNum = TxANTENNA_NUM*RxANTENNA_NUM*PATH_NUM_MC;
	
	double Max_Doppler = 2*PI*VELOCITY*Fc/(3.0e8)*1000.0/3600.0;
	
	double gamma;
	
	for(n_PathNum=0; n_PathNum<n_TotalPathNum; n_PathNum++)
	{
		for(n=0; n<N0; n++)
		{
			gamma = PI*( (double)2*n + (double)2*n_PathNum/n_TotalPathNum + (double)1/(2*n_TotalPathNum) )/N;
			*(alpha+n_PathNum*N0+n) = Max_Doppler*cos(gamma);
			 *(beta+n_PathNum*N0+n) = Max_Doppler*sin(gamma);
		}
	}
	
	return n*n_PathNum;
	
}

int GenCurCHData(double * alpha, double * beta, double * p_Time, COMPLEX * p_CHData, CH_PARAMETER * p_CH_Parameter)
{
	int n;
	int n_PathNum;
	int Index;

	int N0 = 25;
	int N  = 4*N0;
	int n_TotalPathNum = TxANTENNA_NUM*RxANTENNA_NUM*PATH_NUM_MC;

	COMPLEX	 temp;
	COMPLEX  CHtemp;
	
	for(n_PathNum=0; n_PathNum<n_TotalPathNum; n_PathNum++)
	{
		CHtemp.real = CHtemp.image = 0;
		for(n=0; n<N0; n++)
		{
			temp.real   = cos((*(alpha+n_PathNum*N0+n))*(*p_Time) + p_CH_Parameter->Phase_R);
			temp.image  = sin( (*(beta+n_PathNum*N0+n))*(*p_Time) + p_CH_Parameter->Phase_I);
			CHtemp      = add_cmx(CHtemp, temp);
		}
		Index = (n_PathNum%(TxANTENNA_NUM*PATH_NUM_MC))/TxANTENNA_NUM;
		*(p_CHData+n_PathNum) = mul_cmxreal(CHtemp, PATH_GAIN[Index]/sqrt(N0));
	}
		
	(*p_Time) += p_CH_Parameter->Tc;	
	
	return n_PathNum;
	
}

int New_MIMO_Channel(COMPLEX * InSignal, int InSignalLen, COMPLEX * OutSignal, double * p_Time, CH_PARAMETER * p_CH_Parameter)
{
	int result;
	int n_Tx;
	int n_Rx;
	int n_Path;
	int n_Sample;
	int Index;
	
	double Energy_Signal;
	double Energy_Noise;
	double SNR_Es_N0;
	COMPLEX tmp;

	int N0 = 25;
	int N  = 4*N0;
	int n_TotalPathNum = TxANTENNA_NUM*RxANTENNA_NUM*PATH_NUM_MC;

	int InLenPerTx  = InSignalLen/TxANTENNA_NUM;
	int OutLenPerRx = InLenPerTx + MAX_DELAY;
	
	//Memory
	double  * alpha;
	double  * beta;
	COMPLEX * p_CHData;
	
	//Allocate memory
	alpha    = (double  *)malloc(N0*n_TotalPathNum*sizeof(double));
	beta     = (double  *)malloc(N0*n_TotalPathNum*sizeof(double));
	p_CHData = (COMPLEX *)malloc(n_TotalPathNum*sizeof(COMPLEX));
	
	
	//Main
	result = GenCommonData(alpha, beta);

	for(n_Sample=0; n_Sample<OutLenPerRx; n_Sample++)
	{
		result = GenCurCHData(alpha, beta, p_Time, p_CHData, p_CH_Parameter);
		
		for(n_Rx=0; n_Rx<RxANTENNA_NUM; n_Rx++)
		{
			tmp.real = tmp.image = 0;
			for(n_Path=0; n_Path<PATH_NUM_MC; n_Path++)
			{
				Index = n_Sample-p_CH_Parameter->Path_Delay[n_Path];
				
				if( Index>=0 &&	Index<InLenPerTx)
				{
					for(n_Tx=0; n_Tx<TxANTENNA_NUM; n_Tx++)
					{
						tmp = add_cmx( tmp, mul_cmx( *(InSignal+n_Tx*InLenPerTx+Index), *(p_CHData+(n_Rx*PATH_NUM_MC+n_Path)*TxANTENNA_NUM+n_Tx) ) );					
					}    	
				}
			}
			(OutSignal+n_Rx*OutLenPerRx+n_Sample)->real  = tmp.real;
			(OutSignal+n_Rx*OutLenPerRx+n_Sample)->image = tmp.image;

		}
	}
/*	
    //The first method:
	//Add Noise   "measured"
	//Measure output signal energy
	Energy_Signal = 0;
	for(n_Sample=0; n_Sample<RxANTENNA_NUM*OutLenPerRx; n_Sample++)
	{
		Energy_Signal += eng_cmx( *(OutSignal+n_Sample) );
	}
	Energy_Signal /= n_Sample;
	printf("OutEnergy = %f\n", Energy_Signal);
	SNR_Es_N0     = p_CH_Parameter->SNR + ((OUTPUT==2) ? 7.1175876 : 5.3566750); //For new slot structure
*/

	//The second method:
	Energy_Signal = 4.0;  //MC is the same with SC!
	SNR_Es_N0     = p_CH_Parameter->SNR + ((OUTPUT==2) ? 8.2090323 : 6.4481197); //For new slot structure
//  SNR_Es_N0     = p_CH_Parameter->SNR + ((OUTPUT==2) ? (8.2090323+0.3437498) : (6.4481197+0.3437498));
	Energy_Noise  = Energy_Signal/pow(10, SNR_Es_N0/10);
	
	for(n_Sample=0; n_Sample<RxANTENNA_NUM*OutLenPerRx; n_Sample++)
	{
		tmp.real  = generate_gaussian_source(Energy_Noise)/sqrt(2);
		tmp.image = generate_gaussian_source(Energy_Noise)/sqrt(2);
		
		*(OutSignal+n_Sample) = add_cmx( *(OutSignal+n_Sample), tmp );
	}
//	printf("SignalEnergy = %f\t NoiseEnergy = %f\t SNR_Es_N0 = %f\t\n", Energy_Signal, Energy_Noise, SNR_Es_N0); 

	//Free memory
	free(alpha);
	free(beta);
	free(p_CHData);
	
	return n_Sample;
	
}