free5GRAN::phy::signal_processing Namespace Reference

Functions
void	channelEstimation (complex< float > *pilots, complex< float > *reference_pilot, vector< vector< int >> &pilot_indexes, vector< vector< complex< float >>> &coefficients, float &snr, int num_sc, int num_symbols, int pilot_size)
void	hard_demodulation (vector< complex< float >> signal, int *bits, int signal_length, int modulation_scheme)
void	soft_demodulation (vector< complex< float >> signal, double *soft_bits, int signal_length, int modulation_scheme)
void	compute_fine_frequency_offset (vector< complex< float >> input_signal, int symbol_duration, int fft_size, int cp_length, int scs, float &output, int num_symbols)
void	transpose_signal (vector< complex< float >> *input_signal, float freq_offset, int sample_rate, int input_length)
void	channel_demapper (vector< vector< complex< float >>> &input_signal, vector< vector< vector< int >>> &ref, complex< float > **output_channels, vector< vector< vector< int >>> &output_indexes, int num_channels, int num_symbols, int num_sc)
double	compute_freq_from_gscn (int gscn)
free5GRAN::pdcch_t0ss_monitoring_occasions	compute_pdcch_t0_ss_monitoring_occasions (int pdcch_config, int pbch_scs, int common_scs, int i)
void	compute_rb_start_lrb_dci (int RIV, int n_size_bwp, int &lrb, int &rb_start)
void	get_pdsch_dmrs_symbols (const string &type, int duration, int additionnal_position, int l0, int **output, int &size)
void	compute_cp_lengths (int scs, int nfft, int is_extended_cp, int num_symb_per_subframes, int *cp_lengths, int *cum_sum_cp_lengths)
void	compute_phase_decomp (int *cp_lengths, int *cum_sum_symb, float sampling_rate, float f0, int num_symb_per_subframes, complex< float > *phase_decomp_factor)
int	compute_nre (int num_symb_pdsch, int num_dmrs_symb)
void	fft (vector< complex< float >> time_domain_signal, vector< vector< complex< float >>> &output_signal, int fft_size, int *cp_lengths, int *cum_sum_symb, int num_symbols, int num_sc_output, int first_symb_index, int offset)
void	get_candidates_frames_indexes (vector< vector< int >> &frame_indexes, int *frame_numbers, int sfn, int index_first_pss, int num_samples_before_pss, int frame_size)

Function Documentation

channel_demapper()

void free5GRAN::phy::signal_processing::channel_demapper	(	vector< vector< complex< float >>> &	input_signal,
		vector< vector< vector< int >>> &	ref,
		complex< float > **	output_channels,
		vector< vector< vector< int >>> &	output_indexes,
		int	num_channels,
		int	num_symbols,
		int	num_sc
	)

Consumes an input signal and returns different channels containing corresponding data, based on ref indexes

Parameters

[in]	input_signal	Input signal to be de-mapped
[in]	ref	Array containing the indexes of the different channels inside the OFDM grid
[in]	channel_sizes	Array containing the outpu transport_channel sizes
[out]	output_channels	Channels symbols
[out]	output_indexes	Indexes of the output_channels elements
[in]	num_channels	Number of channels
[in]	num_symbols	Number of symbols in the OFDM grid
[in]	num_sc	Number of subcarriers in the OFDM grid

Definition at line 298 of file libphy.cpp.

channelEstimation()

void free5GRAN::phy::signal_processing::channelEstimation	(	complex< float > *	pilots,
		complex< float > *	reference_pilot,
		vector< vector< int >> &	pilot_indexes,
		vector< vector< complex< float >>> &	coefficients,
		float &	snr,
		int	num_sc,
		int	num_symbols,
		int	pilot_size
	)

Estimate channel coefficients for equalization

• Compute channel coefficients for pilots
• Linear interpolation in frequency domain
• Linear interpolation in time domain

Parameters

[in]	pilots	Signal received pilots
[in]	reference_pilot	Generated pilots
[in]	pilot_indexes	Pilot indexes in the signal
[out]	coefficients	Channel coefficient returned by the function
[out]	snr	Computed SNR
[in]	num_sc	Number of subcarriers in the signal
[in]	num_symbols	Number of symbols in the signal
[in]	pilot_size	Pilot size

Definition at line 27 of file libphy.cpp.

compute_cp_lengths()

void free5GRAN::phy::signal_processing::compute_cp_lengths	(	int	scs,
		int	nfft,
		int	is_extended_cp,
		int	num_symb_per_subframes,
		int *	cp_lengths,
		int *	cum_sum_cp_lengths
	)

Compute cyclic prefix size

3GPP standard: TS38.211 V15.2.0 Section 5.3

Parameters

[in]	scs	Subcarrier spacing
[in]	nfft	FFT/iFFT size
[in]	is_extended_cp	True if current CP is extended CP
[in]	num_symb_per_subframes	Number of symbols per subframe
[out]	cp_lengths	Returned CP
[out]	cum_sum_cp_lengths	Cumulative CP sum

Definition at line 483 of file libphy.cpp.

compute_fine_frequency_offset()

void free5GRAN::phy::signal_processing::compute_fine_frequency_offset	(	vector< complex< float >>	input_signal,
		int	symbol_duration,
		int	fft_size,
		int	cp_length,
		int	scs,
		float &	output,
		int	num_symbols
	)

Compute fine frequency offset of a received signal by computing phase offset between cyclic prefix and corresponding symbol data.

Parameters

[in]	input_signal	Received signal
[in]	symbol_duration	Number of samples per symbol
[in]	fft_size	Number of samples in a symbol, after removing cyclic prefix
[in]	cp_length	Cyclic prefix size
[in]	scs	Subcarrier spacing
[out]	output	Frequency offset in Hertz
[in]	num_symbols	Number of symbols in the signal

Definition at line 247 of file libphy.cpp.

compute_freq_from_gscn()

double free5GRAN::phy::signal_processing::compute_freq_from_gscn

(

int

gscn

)

Computing frequency from received GSCN

3GPP standard: TS38.104 V15.2.0 Table 5.4.3.1-1

Parameters

[in]

gscn

Input GSCN

Definition at line 338 of file libphy.cpp.

compute_nre()

int free5GRAN::phy::signal_processing::compute_nre	(	int	num_symb_pdsch,
		int	num_dmrs_symb
	)

Compute number of PDSCH RE per RB

Parameters

[in]	num_symb_pdsch	Number of PDSCH symbols
[in]	num_dmrs_symb	Number of DMRS symbols

Returns

number of PDSCH RE per RB

Definition at line 532 of file libphy.cpp.

compute_pdcch_t0_ss_monitoring_occasions()

free5GRAN::pdcch_t0ss_monitoring_occasions free5GRAN::phy::signal_processing::compute_pdcch_t0_ss_monitoring_occasions	(	int	pdcch_config,
		int	pbch_scs,
		int	common_scs,
		int	i
	)

Compute PDCCH monitoring occasion informations

3GPP standard: TS38.213 V15.2.0 Section 13

Parameters

[in]	pdcch_config	PDCCH config received from MIB
[in]	pbch_scs	PBCH subcarrier spacing
[in]	common_scs	BWP subcarrier spacing
[in]	i	SSB index

Definition at line 369 of file libphy.cpp.

compute_phase_decomp()

void free5GRAN::phy::signal_processing::compute_phase_decomp	(	int *	cp_lengths,
		int *	cum_sum_symb,
		float	sampling_rate,
		float	f0,
		int	num_symb_per_subframes,
		complex< float > *	phase_decomp_factor
	)

Compute phase decompensation vector from frequency

3GPP standard: TS38.211 V15.2.0 Section 5.3

Parameters

[in]	cp_lengths	CP lengths
[in]	cum_sum_symb	CP lengths cumulative sum
[in]	sampling_rate	RF device sample rate
[in]	f0	Frequency in Hz
[in]	num_symb_per_subframes	Number of symbols per subframes
[out]	phase_decomp_factor	Phase de-compensator vector

Definition at line 511 of file libphy.cpp.

compute_rb_start_lrb_dci()

void free5GRAN::phy::signal_processing::compute_rb_start_lrb_dci	(	int	RIV,
		int	n_size_bwp,
		int &	lrb,
		int &	rb_start
	)

Compute RB start and LRB from DCI

3GPP standard: TS38.214 V15.2.0 Section 5.1.2.2.2

Parameters

[in]	RIV	Frequency domain resource allocation
[in]	n_size_bwp	Active BWP size (in RB)
[out]	lrb	Number of PDSCH RB
[out]	rb_start	First PDSCH RB index in BWP

Definition at line 419 of file libphy.cpp.

fft()

void free5GRAN::phy::signal_processing::fft	(	vector< complex< float >>	time_domain_signal,
		vector< vector< complex< float >>> &	output_signal,
		int	fft_size,
		int *	cp_lengths,
		int *	cum_sum_symb,
		int	num_symbols,
		int	num_sc_output,
		int	first_symb_index,
		int	offset
	)

Perform FFT on time domain signal to recover frequency domain signal (= RE grid)

Parameters

[in]	time_domain_signal	Input time domain signal
[out]	output_signal	Output RE grid
[in]	fft_size	FFT size (Number of samples per symbol, excluding CP)
[in]	cp_lengths	Array of CP lengths for 1 subframe (= 1ms)
[in]	cum_sum_symb	Cumulative sum of symbols length in one subframe
[in]	num_symbols	Number of symbols in output RE grid (= Number of rows of output_signal)
[in]	num_sc_output	Number of subcarriers in output RE grid (= Number of columns of output_signal).
[in]	first_symb_index	Index of first symbol to be extracted in frame.
[in]	offset	Number of amples to be left before extracting. Can be used while extracting specific slots in a radio frame.

Definition at line 543 of file libphy.cpp.

get_candidates_frames_indexes()

void free5GRAN::phy::signal_processing::get_candidates_frames_indexes	(	vector< vector< int >> &	frame_indexes,
		int *	frame_numbers,
		int	sfn,
		int	index_first_pss,
		int	num_samples_before_pss,
		int	frame_size
	)

Definition at line 580 of file libphy.cpp.

get_pdsch_dmrs_symbols()

void free5GRAN::phy::signal_processing::get_pdsch_dmrs_symbols	(	const string &	type,
		int	duration,
		int	additionnal_position,
		int	l0,
		int **	output,
		int &	size
	)

Retrieve DMRS symbols

3GPP standard: TS38.211 V15.2.0 Table 7.4.1.1.2-3

Parameters

[in]	additionnal_position	Number of additional positions
[in]	l0	First DMRS symbol
[out]	output	DMRS symbols array
[out]	size	Number of DMRS symbols

Definition at line 438 of file libphy.cpp.

hard_demodulation()

void free5GRAN::phy::signal_processing::hard_demodulation	(	vector< complex< float >>	signal,
		int *	bits,
		int	signal_length,
		int	modulation_scheme
	)

Samples hard demodulation

Parameters

[in]	signal	Input IQ data to be demodulated
[in]	signal_length	Number of symbols to be demodulated
[in]	modulation_scheme	Modulation used (0: BPSK, 1: QPSK)
[out]	bits	Output hard bits

Definition at line 166 of file libphy.cpp.

soft_demodulation()

void free5GRAN::phy::signal_processing::soft_demodulation	(	vector< complex< float >>	signal,
		double *	soft_bits,
		int	signal_length,
		int	modulation_scheme
	)

Samples soft demodulation

• Compute minimum distance to 1 and 0 candidate sample
• Take the difference between shortest distance to 1 and shortest distance to 0

Parameters

[in]	signal	Input IQ data to be demodulated
[out]	bits	Output LLR bits
[in]	signal_length	Number of symbols to be demodulated
[in]	modulation_scheme	Modulation used (0: BPSK, 1: QPSK)

Definition at line 203 of file libphy.cpp.

transpose_signal()

void free5GRAN::phy::signal_processing::transpose_signal	(	vector< complex< float >> *	input_signal,
		float	freq_offset,
		int	sample_rate,
		int	input_length
	)

Shift signal in frequency domain by a frequency offset

Parameters

[in]	input_signal	Input signal to be shifted
[in]	freq_offset	Frequency offset
[in]	sample_rate	Signal sample rate
[in]	input_length	Input signal length

Definition at line 282 of file libphy.cpp.