The following slide shows the different PDPs built into the webdemo. The plot shows the power of the different taps at their respective delays. The weights are normalized in such a way that the total power is equal to one.
The webdemo offers a total of seven different delay profiles: "Default," "Exponential Decay," "TDL-A," "TDL-B," "TDL-C," "TDL-D," and "TDL-E." These profiles define how the delays are spaced and the taps are weighted. The weights are always chosen in such a way that the total power $$ (K+1) \cdot w^2_0 + \sum_{i=1}^{N-1} w^2_i = 1 $$ is equal to one. The delays can be calculated by multiplying the normalized spacings $\tau_{i,\mathrm{norm}}$ with the delay spread $\tau_\mathrm{rms}$. $$ \tau_i = \tau_{i,\mathrm{norm}} \cdot \tau_\mathrm{rms} $$
Default
When choosing the profile "Default," the delays will be evenly spaced and weighted. The delays are given by the equation
$$
\tau_i = \gamma_\tau \cdot i \cdot \tau_\mathrm{rms} \quad \text{with} \ i = 0 \dots N-1
$$
and have the respective weights equal to
$$
w_i = \underbrace{ \sqrt{\dfrac{1}{K+N}} }_\text{normalization} \cdot 1.
$$
The factor $\gamma_\tau$ is quite long and complex and serves only to normalize the delays.
Exponential Decay
When choosing the profile "Exponential Decay", the delays will be evenly spaced and weighted as well. The delays are given by the equation
$$
\tau_i = \gamma_\beta \cdot i \cdot \tau_\mathrm{rms} \quad \text{with} \ i = 0 \dots N-1.
$$
The weights decay exponentially. They can be generated using the equation
$$
w_i = \underbrace{\sqrt{ \dfrac{\beta-1}{K(\beta-1)+\beta^{N}-1}} }_\text{normalization} \cdot \beta^{i/2}.
$$
The factor $\gamma_\beta$ is also quite long and therefore omitted.
TDL-X
Profiles "TDL A" through "TDL E" are taken directly from 3GPP TR 38.901 [2].
Choosing one of these profiles will overwrite user-made changes to the number of delays $N_\text{Delays}$ and the $K\text{-Factor}$.
"TDL A" to "TDL C" do not contain an LoS component, while "TDL D" and "TDL E" do.
[4] 3GPP, “Study on channel model for frequencies from 0.5 to 100 GHz,” Generation Partnership Project (3GPP), Technical Report (TR) 38.901, Version 18.0.0 Release 18, Apr. 2024. [Online].