WGN Generator

Description

The WgnGenerator class provides a mechanism for generating a continuous stream of Additive White Gaussian Noise (WGN) samples. It conforms to the common NoiseGenerator interface defined in noise_generators.h. This allows it to be plugged into various parts of the simulation where a sequence of random noise values following a Gaussian (Normal) distribution is required, most commonly for simulating thermal noise effects in receivers.

Assumptions

• Gaussian Model Appropriateness: Assumes that a Gaussian (Normal) distribution is the correct statistical model for the noise phenomenon being simulated (e.g., thermal noise).
• Standard Deviation Accuracy: Assumes the standard deviation (stddev) parameter provided during its construction or use accurately represents the desired noise power or amplitude scale.
• Underlying Distribution Quality: Assumes the std::normal_distribution implementation within the C++ standard library provides a statistically sound approximation of a true Gaussian distribution for simulation purposes.
• RNG Quality: Assumes the underlying pseudo-random number generator (RNG), initialized via ensureInitialized (likely std::mt19937), provides sufficiently high-quality and statistically random bits for the std::normal_distribution to function correctly.

Limitations

• Pseudo-Randomness: As with all standard software generators, this produces pseudo-random numbers based on a deterministic algorithm initialized by a seed. The sequence is repeatable if the same seed is used, and not truly random.
• Finite Precision: The generated noise samples are represented using floating-point numbers (RealType), which have inherent precision limitations.
• Statistical Imperfections: For any finite number of samples generated, the sequence may exhibit minor statistical deviations from a perfect theoretical Gaussian distribution.
• 'White' Noise Spectrum: This generator produces samples intended to be uncorrelated ('white' noise). It does not inherently model frequency-dependent noise characteristics (colored noise) – that requires different generator types (like Multirate (1-over-f alpha) Noise Model).

Related Components

• Code: noise_generators.h::WgnGenerator (Class Definition)
• Code: noise_generators.h::NoiseGenerator (Interface Definition)
• Code: noise_utils.cpp::ensureInitialized (Handles RNG Initialization)
• Code: noise_utils.cpp::normal_dist
• Feature: RNG Initialization and Seeding
• External: C++ <random> library (std::normal_distribution)

Validation Status

• Needs Verification: The statistical properties of the generated noise stream from this class instance require explicit validation. Basic usage confirmed, but output distribution not formally tested.
• Key Areas for Validation:
  • Confirm the mean of a large number of generated samples is statistically close to zero.
  • Confirm the variance of a large number of generated samples matches the square of the input standard deviation parameter used during construction/use.
  • Analyze the distribution shape of generated samples (e.g., using histograms, statistical normality tests) to verify it approximates a Gaussian distribution.
  • Verify the 'whiteness' property by checking that the autocorrelation of the generated sequence is negligible for lags greater than zero.
  • Test and document the behavior when the input standard deviation is very close to or equal to zero.
• Priority: Medium (Fundamental for accurate noise floor simulation, but relies on standard library components assumed to be reasonably correct).