Base class for an N-dimensional (ND) vector (MIMO) modulator. More...

Inheritance diagram for itpp::Modulator_ND:

Public Types
enum	Soft_Demod_Method { FULL_ENUM_LOGMAP, FULL_ENUM_MAXLOG, ZF_LOGMAP }
	Soft demodulation method. More...

Public Member Functions
	Modulator_ND (LLR_calc_unit llrcalc_in=LLR_calc_unit())
	Default constructor.

virtual	~Modulator_ND ()
	Destructor.

void	set_llrcalc (LLR_calc_unit llrcalc_in)
	Set LLR calculation unit.

LLR_calc_unit	get_llrcalc () const
	Get LLR calculation unit.

int	get_dim () const
	Get number of dimensions.

ivec	get_k () const
	Get number of bits per modulation symbol per dimension.

ivec	bits_per_symbol () const
	Get number of bits per modulation symbol per dimension.

ivec	get_M () const
	Get number of modulation symbols per dimension.

Array< ivec >	get_bits2symbols () const
	Get bit pattern in decimal.

Array< bmat >	get_bitmap () const
	Get Bit mapping table.

Protected Member Functions
QLLRvec	probabilities (QLLR l)
	Convert LLR to log-probabilities.

Array< QLLRvec >	probabilities (const QLLRvec &l)
	Convert LLR to log-probabilities, vector version.

void	marginalize_bits (itpp::QLLRvec &llr, Soft_Demod_Method method) const
	Marginalize (sum) over the bits.

void	demodllrbit0 (itpp::QLLR &llr) const
	Hardcoded implementation of 1:st bit demodulation.

void	demodllrbit1 (itpp::QLLR &llr) const
	Hardcoded implementation of 2:nd bit demodulation.

void	demodllrbit2 (itpp::QLLR &llr) const
	Hardcoded implementation of 3:rd bit demodulation.

void	demodmaxbit0 (itpp::QLLR &maxllr) const
	Hardcoded implementation of 1:st bit demodulation.

void	demodmaxbit1 (itpp::QLLR &maxllr) const
	Hardcoded implementation of 2:nd bit demodulation.

void	demodmaxbit2 (itpp::QLLR &maxllr) const
	Hardcoded implementation of 3:rd bit demodulation.

void	update_LLR (const Array< QLLRvec > &logP_apriori, const ivec &s, QLLR scaled_norm, QLLRvec &num, QLLRvec &denom)
	Update LLR (for internal use)

void	update_LLR (const Array< QLLRvec > &logP_apriori, int s, QLLR scaled_norm, int j, QLLRvec &num, QLLRvec &denom)
	Update LLR, for scalar channel (for internal use)

Protected Attributes
int	nt
	Number of dimensions.

int	nb
	Number of bits in the symbol vector.

LLR_calc_unit	llrcalc
	LLR calculation unit.

ivec	k
	Number of bits per modulation symbol.

ivec	M
	Number of modulation symbols along each dimension.

bool	demod_initialized
	Flag indicating whether the demodulator has been initialized.

Array< bmat >	bitmap
	Bit mapping table (one table per dimension)

Array< ivec >	bits2symbols
	Bit pattern in decimal form ordered and the corresponding symbols (one pattern per dimension)

double	gaussnorm
	The normalization factor in the exponent (in front of the square norm) in the Gaussian distribution.

itpp::vec	hnorms
	Norms part dependent on H.

itpp::QLLRvec	Qnorms
	Norms part depending on both H and y.

itpp::QLLRvec	llrapr
	A prioi information.

itpp::ivec	bpos2cpos
	The bit to column mapping.

itpp::ivec	bitcumsum
	The cumulative sum of bits in the symbol vector.

itpp::Array< itpp::Vec < unsigned > >	gray2dec
	The Gray to decimal mapping.

Detailed Description

Base class for an N-dimensional (ND) vector (MIMO) modulator.

See ND_UPAM class for examples.

Note: Can also be used for scalar modulation/demodulation as an alternative to Modulator_1D or Modulator_2D. Mixed use of Modulator_1D or Modulator_2D and Modulator_ND is not advised.; For issues relating to the accuracy of LLR computations, please see the documentation of LLR_calc_unit

Definition at line 63 of file modulator_nd.h.

Member Enumeration Documentation

Soft demodulation method.

Enumerator:

FULL_ENUM_LOGMAP	Log-MAP demodulation by "brute-force" enumeration of all points.
FULL_ENUM_MAXLOG	Max-Log demodulation by "brute-force" enumeration of all points.
ZF_LOGMAP	Zero-Forcing Log-MAP approximated demodulation.

Definition at line 67 of file modulator_nd.h.

void itpp::Modulator_ND::update_LLR	(	const Array< QLLRvec > &	logP_apriori,
		const ivec &	s,
		QLLR	scaled_norm,
		QLLRvec &	num,
		QLLRvec &	denom
	)

protected

Update LLR (for internal use)

This function updates the numerator and denominator in the expression

$\log \left( \frac {\sum_{s:b_k=0} \exp(-x^2) P(s)} {\sum_{s:b_k=1} \exp(-x^2) P(s)} \right)$

Parameters

[in]	logP_apriori	Vector of a priori probabilities per bit
[in]	s	Symbol vector
[in]	scaled_norm	Argument of the exponents in the above equation
[out]	num	Logarithm of the numerator in the above expression
[out]	denom	Logarithm of the denominator in the above expression

Definition at line 94 of file modulator_nd.cpp.

void itpp::Modulator_ND::update_LLR	(	const Array< QLLRvec > &	logP_apriori,
		int	s,
		QLLR	scaled_norm,
		int	j,
		QLLRvec &	num,
		QLLRvec &	denom
	)

protected

Update LLR, for scalar channel (for internal use)

This function updates the numerator and denominator in the expression

$\log \left( \frac {\sum_{s:b_k=0} \exp (-x^2) P(s)} {\sum_{s:b_k=1} \exp (-x^2) P(s)} \right)$

Parameters

[in]	logP_apriori	Vector of a priori probabilities per bit
[in]	s	Symbol
[in]	scaled_norm	Argument of the exponents in the above equation
[in]	j	Channel index (dimension)
[out]	num	Logarithm of the numerator in the above expression
[out]	denom	Logarithm of the denominator in the above expression

Definition at line 68 of file modulator_nd.cpp.

The documentation for this class was generated from the following files: