Source code for ran.phy.numpy.utils.awgn

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"""AWGN channel."""

import numpy as np
from numpy.typing import NDArray




def awgn(H: NDArray[np.complex64], snr_db: float) -> NDArray[np.complex64]:
    """Add AWGN to channel.

    Args:
        H: Channel with shape (n_sc, n_sym, n_ant)
        snr_db: SNR in dB

    Returns
    -------
        Noisy channel
    """
    # Calculate noise power
    signal_power = np.mean(np.abs(H) ** 2)
    snr_linear = 10 ** (snr_db / 10)
    noise_power = signal_power / snr_linear

    # Generate complex noise
    noise = np.sqrt(noise_power / 2) * (np.random.randn(*H.shape) + 1j * np.random.randn(*H.shape))

    return H + noise