Engee documentation

AWGN Channel

Add white Gaussian noise to the input signal.

awgn channel

Description

The AWGN Channel block adds white Gaussian noise to the input signal. It inherits the sampling period from the input signal.

Ports

Input

In - input signal
vector | scalar

Input data signal as a vector NS by 1 or a matrix NS by NC. NS represents the number of samples in the input signal. NC represents the number of channels determined by the number of columns in the input signal matrix. Both NS and NC can be equal to 1.

The block adds frames of Gaussian noise of length NS to each of the NC channels using a separate random assignment to the channels.

Data types: Float16, Float32, Float64, Int8, Int16, Int32, Int64, UInt8, UInt16, UInt32, UInt64, Bool, ComplexF64.

Output

Out - output signal
vector | scalar

Output data signal for the AWGN channel block, returned as a vector or scalar. The data type and dimensions of Out correspond to the data type and dimensions from the input signal In.

The Out data types are: Float64, ComplexF64.

Parameters

Initial seed - initial number of noise generator
67 (by default) | positive scalar

The initial initial number of the noise generator for the mt19937ar algorithm as a positive scalar value.

When the input signal is complex, the block generates random data as:

randData= randn(2* NS, NC)
noise = randData(1:2:end)+1i(randData(2:2:end))

NS is the number of samples, and NC is the number of channels. You can specify different initial values for each DLL assembly.

*Customisable: Yes

Mode - noise dispersion normalisation mode
Signal to noise ratio (Eb/No) (By default)

Noise dispersion normalisation mode as Signal to noise ratio (Eb/No).

Eb/No (dB) - ratio of the energy of information bits per symbol to the noise power spectral power density
10 (by default) | scalar

The ratio of the information bit energy per symbol to the noise power spectral density in decibels as a scalar or vector. The information bit energy represents the magnitude without channel coding.

*Customisable: Yes

Dependencies

To use this setting, set Mode to Signal to noise ratio (Eb/No).

Number of bits per symbol - number of bits in each input symbol
1 (by default) | scalar

Number of bits in each input symbol as a scalar.

Input signal power, referenced to 1 ohm (watts) - RMS input power
1 (By default) | scalar

RMS input power in watts as a scalar.

When Mode is Signal to noise ratio (Eb/No), the parameter represents the RMS power of the input symbols.

Customisable: Yes

Dependencies

To use this setting, set Mode to Signal to noise ratio (Eb/No).

Symbol period (s) - number of samples per symbol
1 (By default) | positive scalar

Number of samples per symbol in samples as a positive scalar value.

Tips

  • You can adjust settings in normal mode, acceleration mode, or fast acceleration mode.

  • Unless otherwise specified, the parameters are not adjustable.

    • For non-configurable parameters, when you use a fast simulation target to create an RSIM executable, you cannot change their values without recompiling the model.

    • If a parameter is configurable, you can change its value at any time. This is useful for Monte Carlo simulations where you run the simulation multiple times (e.g., on multiple computers) with different noise levels.

Algorithms

Relationship between Eb/No, Es/No and SNR modes

For uncoded complex input signals, the AWGN Channel block links Eb/No, Es/No and SNR according to these equations:

в

Where:

  • - signal energy in joules.

  • - bit energy in joules.

  • - noise power spectral density in W/Hz.

  • - value of the Samples per symbol parameter.

  • - period of the signal symbol in seconds.

  • - inherited block calculation time in seconds.

  • - number of information bits per input symbol, parameter value Number of bits per symbol.

For valid input signals, the AWGN Channel block relates Es/No and SNR according to this equation:

  • All power values assume a nominal impedance of 1 ohm.

  • The equation for the real case differs from the corresponding equation for the complex case by a factor of 2. In particular, the facility uses a noise power spectral density of N0/2 W/Hz for real input signals compared to N0 W/Hz for complex signals.

Examples