AWGN Channel
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Adds white Gaussian noise to the input signal.
blockType: AWGN
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Path in the library: |
Description
The AWGN Channel block adds white Gaussian noise to the input signal. It inherits the sampling period from the input signal.
Ports
Output
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Out
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Details
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| Data types |
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| Complex numbers support |
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Parameters
Main
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Initial seed —
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Real number
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| Default value |
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| Program usage name |
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| Tunable |
No |
| Evaluatable |
Yes |
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Mode —
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Signal to noise ratio (Eb/No) | Signal to noise ratio (Es/No) | Signal to noise ratio (SNR) | Variance
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| Values |
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| Default value |
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| Program usage name |
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| Tunable |
No |
| Evaluatable |
No |
# Eb/No (dB) — description missing
Details
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| Default value |
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| Program usage name |
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| Tunable |
No |
| Evaluatable |
Yes |
# Es/No (dB) — description missing
Details
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| Default value |
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| Program usage name |
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| Tunable |
No |
| Evaluatable |
Yes |
# SNR (dB) — description missing
Details
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| Default value |
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| Program usage name |
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| Tunable |
No |
| Evaluatable |
Yes |
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Noise variance source —
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Parameter | Input port
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| Values |
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| Default value |
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| Program usage name |
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| Tunable |
No |
| Evaluatable |
No |
# Noise variance — description missing
Details
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| Default value |
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| Program usage name |
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| Tunable |
No |
| Evaluatable |
Yes |
# Number of bits per symbol — description missing
Details
description missing
| Default value |
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| Program usage name |
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| Tunable |
No |
| Evaluatable |
Yes |
# Input signal power, referenced to 1 ohm (watts) — description missing
Details
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| Default value |
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| Program usage name |
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| Tunable |
No |
| Evaluatable |
Yes |
# Samples per symbol — description missing
Details
description missing
| Default value |
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| Program usage name |
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| Tunable |
No |
| Evaluatable |
Yes |
Algorithms
Relationship between Eb/No, Es/No and SNR modes
For uncoded complex input signals, block AWGN Channel links , and according to these equations:
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in dB,
where
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- signal energy in J
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- bit energy in J;
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- noise power spectral density in W/Hz;
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- parameter value Samples per symbol;
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- signal symbol period in seconds
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- inherited block calculation time in seconds;
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- number of information bits per input symbol, value of the parameters Number of bits per symbol.
For valid input signals, the AWGN Channel block links and according to this equation:
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Specifying noise variance directly or indirectly
To directly specify the variance of the noise generated by AWGN Channel, set the parameters Mode to Variance. When you set the parameters Noise variance source to :
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Parameter- The variance is specified as a positive scalar or vector using the parameters Noise variance. -
Input port- variance is set as a positive scalar or vector using the Var input port. The sampling frequency of the input variance must be equal to the frequency of the input signal.
When you specify the variance as:
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scalar, all channels of the signal are uncorrelated but have the same variance;
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a vector whose length is equal to the number of channels in the input signal, each element representing the variance of the corresponding channel of the signal.
| If you apply complex input signals to the AWGN Channel block, it adds a zero-mean complex Gaussian noise with a calculated or specified variance. The variance for each quadrature component of the complex noise is half of the calculated or specified value. |
To set the variance indirectly, i.e., to have the unit calculate the variance, set the parameters to Mode:
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Signal to noise ratio (Eb/No), at which the block calculates the deviation from the set parameters:-
Eb/No (dB), the ratio of bit energy to noise power spectral density;
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Number of bits per symbol;
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Input signal power, referenced to 1 ohm (watts), the actual power of symbols at the block input;
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Samples per symbol.
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Signal to noise ratio (Es/No), at which the block calculates the deviation from the set parameters:-
Es/No (dB), the ratio of bit energy to noise power spectral density;
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Input signal power, referenced to 1 ohm (watts), actual power of symbols at the block input;
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Samples per symbol.
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Signal to noise ratio (SNR), at which the block calculates the deviation from the set parameters:-
SNR (dB), the ratio of signal power to noise power;
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Input signal power, referenced to 1 ohm (watts), actual power of samples at the block input;
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Changing the symbol period in the block AWGN Channel affects the variance of the noise added per count, which also causes a change in the final error rate.
| Select a symbol period equal to the period of the model symbol. The value depends on what makes up the symbol and what oversampling is applied to it. For example, a symbol may have 3 bits and be oversampled by 4. |