Single Carrier¶

Single carrier waveforms modulate only a single discrete carrier frequency. They are typically applying a shaping filter around the modulated frequency, of which the following are currently available:

class FilteredSingleCarrierWaveform(symbol_rate, num_preamble_symbols, num_data_symbols, num_postamble_symbols=0, pilot_rate=0, guard_interval=0.0, oversampling_factor=4, pilot_symbol_sequence=None, repeat_pilot_symbol_sequence=True, **kwargs)[source]¶

Bases: ConfigurablePilotWaveform

This method provides a class for a generic PSK/QAM modem.

The modem has the following characteristics: - root-raised cosine filter with arbitrary roll-off factor - arbitrary constellation, as defined in modem.tools.psk_qam_mapping:PskQamMapping

This implementation has currently the following limitations: - hard output only (no LLR) - no reference signal - ideal channel estimation - equalization of ISI with FMCW in AWGN channel only - no equalization (only amplitude and phase of first propagation path is compensated)

Parameters:

symbol_rate (float) – Rate at which symbols are being generated in Hz.
num_preamble_symbols (int) – Number of preamble symbols within a single communication frame.
num_data_symbols (int) – Number of data symbols within a single communication frame.
num_postamble_symbols (int, optional) – Number of postamble symbols within a single communication frame.
guard_interval (float, optional) – Guard interval between communication frames in seconds. Zero by default.
oversampling_factor (int, optional) – The oversampling factor of the waform.
pilot_rate (int, optional) – Pilot symbol rate. Zero by default, i.e. no pilot symbols.
pilot_symbol_sequence (Optional[PilotSymbolSequence], optional) – The configured pilot symbol sequence. Uniform by default.
repeat_pilot_symbol_sequence (bool, optional) – Allow the repetition of pilot symbol sequences. Enabled by default.
kwargs (Any) – Waveform generator base class initialization parameters.

demodulate(signal)[source]¶

Demodulate a base-band signal stream to data symbols.

Parameters:: signal (numpy.ndarray) – Vector of complex-valued base-band samples of a single communication frame.
Return type:: Symbols
Returns:: The demodulated communication symbols

map(bits)[source]¶

Map a stream of bits to data symbols.

Parameters:: data_bits (numpy.ndarray) – Vector containing a sequence of L hard data bits to be mapped onto data symbols.
Returns:: Mapped data symbols.
Return type:: Symbols

modulate(symbols)[source]¶

Modulate a stream of data symbols to a base-band signal containing a single data frame.

Parameters:: data_symbols (Symbols) – Singular stream of data symbols to be modulated by this waveform.
Return type:: ndarray

Returns: Samples of the modulated base-band signal.

pick(symbols)[source]¶

Pick the mapped symbols from the communicaton frame.

Additionally removes interleaved pilot symbols.

Parameters:: placed_symbols (StatedSymbols) – The placed symbols.
Return type:: StatedSymbols

Returns: The symbols with the mapped symbols picked from the frame.

place(data_symbols)[source]¶

Place the mapped symbols within the communicaton frame.

Additionally interleaves pilot symbols.

Parameters:: symbols (Symbols) – The mapped symbols.
Return type:: Symbols

Returns: The symbols with the mapped symbols placed within the frame.

plot_filter()[source]¶

Plot the transmit filter shape.

Return type:: Figure
Returns:: Handle to the generated matplotlib figure.

plot_filter_correlation()[source]¶

Plot the convolution between transmit and receive filter shapes.

Return type:: Figure
Returns:: Handle to the generated matplotlib figure.

unmap(symbols)[source]¶

Map a stream of data symbols to data bits.

Parameters:: symbols (Symbols) – Sequence of K data symbols to be mapped onto bit sequences.
Returns:: Vector containing the resulting sequence of L data bits In general, L is greater or equal to K.
Return type:: np.ndarray

property bit_energy: float¶

Returns the theoretical average (discrete-time) bit energy of the modulated baseband_signal.

Energy of baseband_signal \(x[k]\) is defined as \(\sum{|x[k]}^2\) Only data bits are considered, i.e., reference, guard intervals are ignored.

property guard_interval: float¶

Frame guard interval.

Returns:: Interval in seconds.
Return type:: float

property modulation_order: int¶

Access the modulation order.

Returns:: The modulation order.
Return type:: int

property num_data_symbols: int¶

Number of data symbols per frame.

Raises:: ValueError – If num is smaller than zero.

property num_guard_samples: int¶

Number of samples within the guarding section of a frame.

Returns:: Number of samples.
Return type:: int

property num_postamble_symbols: int¶

Number of postamble symbols.

Transmitted at the end of communication frames.

Returns: The number of symbols.

Raises:: ValueError – If the number of symbols is smaller than zero.

property num_preamble_symbols: int¶

Number of preamble symbols.

Transmitted at the beginning of communication frames.

Returns: The number of symbols.

Raises:: ValueError – If the number of symbols is smaller than zero.

property pilot_rate: int¶

Repetition rate of pilot symbols within the frame.

A pilot rate of zero indicates no pilot symbols within the data frame.

Returns:: Rate in number of symbols
Raises:: ValueError – If the pilot rate is smaller than zero.

property pilot_signal: Signal¶

Model of the pilot sequence within this communication waveform.

Returns:: The pilot sequence.
Return type:: Signal

property power: float¶

Returns the theoretical average symbol (unitless) power,

Power of baseband_signal \(x[k]\) is defined as \(\sum_{k=1}^N{|x[k]|}^2 / N\) Power is the average power of the data part of the transmitted frame, i.e., bit energy x raw bit rate

property samples_per_frame: int¶: Number of time-domain samples per processed communication frame.

property sampling_rate: float¶

Rate at which the waveform generator signal is internally sampled.

Returns:: Sampling rate in Hz.
Return type:: float

property symbol_duration: float¶: Duration of a single symbol block.

property symbol_energy: float¶

The theoretical average symbol (discrete-time) energy of the modulated baseband_signal.

Energy of baseband_signal \(x[k]\) is defined as \(\sum{|x[k]}^2\) Only data bits are considered, i.e., reference, guard intervals are ignored.

Returns:: The average symbol energy in UNIT.

property symbol_rate: float¶

Repetition rate of symbols.

Returns:: Symbol rate in Hz.
Raises:: ValueError – For rates smaller or equal to zero.

class RolledOffSingleCarrierWaveform(relative_bandwidth=1.0, roll_off=0.0, filter_length=16, *args, **kwargs)[source]¶

Bases: FilteredSingleCarrierWaveform

Base class for single carrier waveforms applying linear filters longer than a single symbol duration.

Parameters:

relative_bandwidth (float, optional) – Bandwidth relative to the configured symbol rate. One by default, meaning the pulse bandwidth is equal to the symbol rate in Hz, assuming zero roll_off.
roll_off (float, optional) – Filter pulse shape roll off factor between zero and one. Zero by default, meaning no inter-symbol interference at the sampling instances.
filter_length (float, optional) – Filter length in modulation symbols. 16 by default.

property bandwidth: float¶

Bandwidth of the frame generated by this generator.

Used to estimate the minimal sampling frequency required to adequately simulate the scenario.

Returns:: Bandwidth in Hz.
Return type:: float

property filter_length: int¶

Filter length in modulation symbols.

Configures how far the shaping filter stretches in terms of the number of modulation symbols it overlaps with.

Returns:: Filter length in number of modulation symbols.
Raises:: ValueError – For filter lengths smaller than one.

property relative_bandwidth: float¶

Bandwidth relative to the configured symbol rate.

Raises:: ValueError – On values smaller or equal to zero.

property roll_off: float¶

Filter pulse shape roll off factor.

Raises:: ValueError – On values smaller than zero or larger than one.