FIR type Fading generator class. More...

#include <itpp/comm/channel.h>

Inheritance diagram for itpp::FIR_Fading_Generator:

Public Member Functions
	FIR_Fading_Generator (double norm_doppler, int filter_length=500)
	Default constructor.

virtual	~FIR_Fading_Generator ()
	Destructor.

virtual void	set_filter_length (int filter_length)
	Set FIR filter length.

virtual int	get_filter_length () const
	Get filter length.

virtual void	init ()
	Initialize the generator.

virtual void	generate (int no_samples, cvec &output)
	Generate no_samples values from the fading process.

virtual void	set_norm_doppler (double norm_doppler)
	Set normalized Doppler.

virtual void	set_LOS_doppler (double relative_doppler)
	Set relative Doppler (compared to the maximum Doppler) for the LOS component.

virtual void	set_time_offset (int offset)
	Set time offset in samples.

virtual double	get_norm_doppler () const
	Return normalized Doppler.

virtual double	get_LOS_doppler () const
	Get relative Doppler (compared to the maximum doppler) for the LOS component.

virtual double	get_time_offset () const
	Get time offset in samples.

virtual void	shift_time_offset (int no_samples)
	Shift generator time offset by a number of samples.

cvec	generate (int no_samples)
	Generate no_samples values from the fading process.

void	set_LOS_power (double relative_power)
	Set relative LOS power.

virtual void	set_doppler_spectrum (DOPPLER_SPECTRUM spectrum)
	Set Doppler spectrum (for Rice fading generator)

virtual void	set_no_frequencies (int no_freq)
	Set number of sine frequencies (for Rice fading generator)

virtual void	set_rice_method (RICE_METHOD method)
	Set calculation method of Doppler frequencies and amplitudes (for Rice fading generator)

double	get_LOS_power () const
	Get relative power of LOS component (Rice factor)

virtual DOPPLER_SPECTRUM	get_doppler_spectrum () const
	Return Doppler spectrum (for Rice fading generator)

virtual int	get_no_frequencies () const
	Get number of sine frequencies (for Rice fading generator)

virtual RICE_METHOD	get_rice_method () const
	Get calculation method of Doppler frequencies and amplitudes (for Rice fading generator)

Protected Member Functions
vec	Jakes_filter (double norm_dopp, int order=100)
	Jakes spectrum filter.

void	add_LOS (int idx, std::complex< double > &sample)
	add LOS component to the sample with index idx

Protected Attributes
int	fir_length
	Size of FIR filter.

int	upsample_rate

MA_Filter< std::complex < double >, double, std::complex< double > >	fir_filter
	Filter used for fading generation.

cvec	left_overs
	Left-overs from upsampling.

double	n_dopp
	Normalized maximum Doppler frequency.

double	los_dopp
	Relative Doppler on LOS component (0.7 by default)

double	time_offset
	Time offset in samples (time state in the generator)

bool	init_flag
	signals if generator is initialized or not

double	los_power
	Relative power of LOS component compared to diffuse component (K factor)

double	los_diffuse
	Diffuse component: sqrt(1 / (1 + los_power))

double	los_direct
	Direct component: sqrt(los_power / (1 + los_power))

Detailed Description

FIR type Fading generator class.

Author: Tony Ottosson and Adam Piatyszek

A FIR generator is a linear finite impulse response (FIR) filter implementation of a filter method for generation of a fading process. Parameters that define the generator are the normalized Doppler and length of the FIR filter. The default value of filter length is 500. If the normalized Doppler frequency is lower than 0.1 an equivalent process of a higher normalized Doppler is generated and linearly interpolated.

References:

[Stu01] Gordon L. Stuber, Principles of mobile communication, 2nd. ed., Kluwer, 2001.
[Rap96] Theodore S. Rappaport, Wireless communications: principles and practise, Prentice Hall, 1996.

Definition at line 531 of file channel.h.

Member Function Documentation

vec itpp::FIR_Fading_Generator::Jakes_filter	(	double	norm_dopp,
		int	order = `100`
	)

protected

Jakes spectrum filter.

Function that generates the taps in the Jakes filter.

Parameters

order	Number of taps in the filter
norm_dopp	Normalized Doppler frequency, i.e. $f_{norm} = f_{max} T_{s}$ , where $f_{max}$ is the actual Doppler frequency and $T_{s}$ is the sampling interval.