time_lag_discrete_time_channel#

sionna.phy.channel.time_lag_discrete_time_channel(bandwidth: float, maximum_delay_spread: float = 3e-06) → Tuple[int, int][source]#

Compute the smallest and largest time-lag for the discrete complex baseband channel, i.e., \(L_{\text{min}}\) and \(L_{\text{max}}\).

The smallest time-lag (\(L_{\text{min}}\)) returned is always -6, as this value was found small enough for all models included in Sionna.

The largest time-lag (\(L_{\text{max}}\)) is computed from the bandwidth and maximum_delay_spread as follows:

\[L_{\text{max}} = \lceil W \tau_{\text{max}} \rceil + 6\]

where \(L_{\text{max}}\) is the largest time-lag, \(W\) the bandwidth, and \(\tau_{\text{max}}\) the maximum_delay_spread.

The default value for the maximum_delay_spread is 3us, which was found to be large enough to include most significant paths with all channel models included in Sionna assuming a nominal delay spread of 100ns.

Notes

The values of \(L_{\text{min}}\) and \(L_{\text{max}}\) computed by this function are only recommended values. \(L_{\text{min}}\) and \(L_{\text{max}}\) should be set according to the considered channel model. For OFDM systems, one also needs to be careful that the effective length of the complex baseband channel is not larger than the cyclic prefix length.

Parameters:

  • bandwidth (float) – Bandwidth (\(W\)) [Hz]

  • maximum_delay_spread (float) – Maximum delay spread [s]. Defaults to 3e-6.

Outputs:

  • l_min – int. Smallest time-lag (\(L_{\text{min}}\)) for the discrete complex baseband channel. Set to -6, as this value was found small enough for all models included in Sionna.

  • l_max – int. Largest time-lag (\(L_{\text{max}}\)) for the discrete complex baseband channel.

Examples

from sionna.phy.channel import time_lag_discrete_time_channel

l_min, l_max = time_lag_discrete_time_channel(20e6)
print(l_min, l_max)
# -6 66