saleh-valenzuela信道模型代码

以下是一个简单的 Python 代码实现 Saleh-Valenzuela 信道模型：

import numpy as np

def sv_channel_model(fc, d, ht, hr, num_samples):
    """
    Saleh-Valenzuela channel model implementation in Python.

    Parameters:
    fc (float): carrier frequency in Hz
    d (float): distance between transmitter and receiver in meters
    ht (float): height of transmitter in meters
    hr (float): height of receiver in meters
    num_samples (int): number of samples to generate

    Returns:
    h (1D numpy array): channel impulse response
    t (1D numpy array): time vector for the channel impulse response
    """

    # Constants
    c = 299792458  # speed of light in m/s
    lam = c / fc  # wavelength in m
    d_bp = 4 * ht * hr * fc / c  # break point distance in m

    # Calculate path loss
    path_loss = 20 * np.log10(4 * np.pi * d / lam)

    # Calculate small-scale fading
    if d <= d_bp:
        sigma_l = 3.2 * np.sqrt((ht - hr) / d)
        sigma_n = 8.7 * np.sqrt((ht - hr) / d)
        sigma_s = 10 * np.sqrt((ht - hr) / d)
        alpha_l = np.random.normal(0, sigma_l, num_samples)
        alpha_n = np.random.normal(0, sigma_n, num_samples)
        alpha_s = np.random.normal(0, sigma_s, num_samples)
        h = np.exp(1j * 2 * np.pi * np.random.rand(num_samples)) * \
            np.exp(-alpha_l / 20) * \
            (1 - np.exp(-alpha_n / 20)) ** 0.5 + \
            np.exp(-alpha_s / 20)
    else:
        sigma_l = 3.2 * np.sqrt(ht * hr / d ** 2)
        sigma_n = 8.7 * np.sqrt(ht * hr / d ** 2)
        sigma_s = 10 * np.sqrt(ht * hr / d ** 2)
        alpha_l = np.random.normal(0, sigma_l, num_samples)
        alpha_n = np.random.normal(0, sigma_n, num_samples)
        alpha_s = np.random.normal(0, sigma_s, num_samples)
        h = np.exp(1j * 2 * np.pi * np.random.rand(num_samples)) * \
            np.exp(-alpha_l / 20) * \
            (1 - np.exp(-alpha_n / 20)) ** 0.5 + \
            np.exp(-alpha_s / 20)

    # Calculate time vector
    dt = 1 / (fc * 1000)  # time step in ms
    t = np.arange(0, num_samples * dt, dt)

    return h, t

此代码实现了 Saleh-Valenzuela 信道模型中的大尺度衰落和小尺度衰落。大尺度衰落通过计算路径损耗来实现，而小尺度衰落则根据距离是否小于或大于突破点距离来计算不同的参数。

请注意，此代码仅供参考，并不考虑更复杂的情况和参数。