PNC_Channel.cpp

/*
 * PNC_Channel.cpp
 *
 *  Created on: 23 Dec, 2014
 \*      Author: Mehrdad Tahernia
 */
#include <cstdlib>
#include "Definitions.h"
#include "GFq.h"
#include "Utils_2.h"
#include "LDPC.h" //LDPC Code
#include "PNC_Channel.h"


/*********************************************************************************
 *
 * PNC Channel
 *
 ********************************************************************************/

void PNC_Channel::ProcessMapping(LDPC_Code &Code) {
	Code.MapInUse.Normalize();
}

// I use AWGN Channel Capacity formula
double PNC_Channel::CapacityInBits() {
	double No = pow(noise_sigma, 2.);
	double SNR = (h_A*h_A+h_B*h_B)*1.0 / No;
	return 0.5 * log(1. + SNR) / log(2.);
}

void PNC_Channel::PrintChannelData(LDPC_Code &Code) {
//	cout << "FIXME: Channel Data Calculation and Printing Not Implemented!!!!\\";
	double BitRate, No, SNR_A, SNR_B, SNR_A_dB, SNR_B_dB, SNR;

	BitRate = Code.Calc_Bit_Rate();
	No = pow(noise_sigma, 2.);
	SNR_A = h_A*h_A*1.0 / No;
	SNR_B= h_B*h_B*1.0 / No;
	SNR_A_dB = 10. * log10(SNR_A);
	SNR_B_dB = 10. * log10(SNR_B);
	SNR = min(SNR_A,SNR_B);

	cout  	<< "SNR_A(dB) = " << SNR_A_dB << "\tSNR_B(dB) = " << SNR_B_dB << "\n"
			<< "SNR_A = " << SNR_A << "\tSNR_B = " << SNR_B << "\n"
			<< "Noise Sigma = "<< noise_sigma
			<< "\nCapacity at SNR (symbols per channel use) = "<< 0.5 * log(1.0 + SNR) / log((double) GFq::q)
			<< "\nCapacity at SNR (bits per channel use) = "   << 0.5 * log(1.0 + SNR) / log(2.0)
			<< "\nMinimum SNR for rate (dB) = "<< 10.0 * log(pow(2.0, 2.0 * BitRate) - 1.) / log(10.0)
			<< " (absolute value) = " << pow(2.0, 2.0 * BitRate) - 1;
}

double PNC_Channel::CalcProbForInput(double ChannelOutput, double ChannelInput) {
	static const double sqrt_2pi = sqrt(2 * 3.141592653);
	double noise_prob = (1 / (sqrt_2pi * noise_sigma)
			* exp( -pow(ChannelOutput - ChannelInput, 2.)/ (2. * NoiseVariance())) );

	return noise_prob;
}

double PNC_Channel::SimulateOutput(double ChannelInput)
// Simulate the result of passing the input through the AWGN
// Actually pass ChannelInput from a gaussian channel
{
	return ChannelInput + GaussGenerate(noise_sigma);
}

double PNC_Channel::NoiseVariance() {
	return pow(noise_sigma, 2);
}

double PNC_Channel::NoiseStdDev() {
	return noise_sigma;
}


void PNC_Channel::SimulateOutputVector_PNC(vector &InVector_A, vector &InVector_B, vector &OutVector)
{
//	cout << "CWA:" << InVector_A[0] << "\n";
	if (InVector_A.GetSize() != InVector_A.GetSize()){cout << "Error:Channel input vectors must have the same size\n";exit(1); }
	OutVector.Allocate(InVector_A.GetSize());

	for (int i = 0; i < InVector_A.GetSize(); i++)  // Add noise to each component
		OutVector[i] = this->SimulateOutput_PNC( /* channel in */InVector_A[i],/* channel in */InVector_B[i]);
}

double PNC_Channel::SimulateOutput_PNC(double ChannelInput_A, double ChannelInput_B)
// Simulate the result of passing the inputs through the AWGN
{
	return h_A*ChannelInput_A + h_B*ChannelInput_B + GaussGenerate(noise_sigma);
}

void PNC_Channel::SimulateNC_PNC(GFq *A, GFq *B, GFq *N, int BL )
{
	for (int i = 0 ; i<BL ; i++)
		*(N+i) = *(A+i) * alpha + *(B+i) * beta;

}