These are two models that are meant to describe similar phenomena. The clustered model is based on geometry, which makes it appropriate to describe semi-realistic scenarios with spatial consistency when users move. 3GPP uses that kind of models for evaluation.

The finite dimensional model can be used to study limited scattering without having to make overly specific assumptions about the geometry.

So it is mostly a question about how much geometrical structure one wants to select vs. abstract away.

One can take typically rewrite the former model into the second one using the beamspace representation.

The Finite Dimensional Channel (FDC) and Clustered Channel models are both used to represent poor scattering MIMO (Multiple-Input Multiple-Output) channels, but they differ in their approach to modeling the channel.

The FDC model assumes that the channel has a small number of dominant paths that can be characterized by their delay, angle of departure and angle of arrival. The channel is then represented as a finite-dimensional matrix, with the number of rows and columns equal to the number of transmit and receive antennas, respectively. Each element of the matrix represents the complex gain of a specific path. The FDC model is simple and computationally efficient, but it may not capture the full complexity of the channel.

On the other hand, the Clustered Channel model assumes that the channel has a large number of scatterers, each of which contributes to the channel response. The scatterers are typically grouped into clusters based on their delay and angle of departure/arrival, and each cluster is then modeled as a sub-channel with a specific delay and spatial signature. The sub-channels are then combined to form the overall channel response. The clustered channel model is more complex and computationally intensive than the FDC model, but it can capture the full complexity of the channel.

In summary, the main difference between the FDC and Clustered Channel models is that the FDC model assumes a small number of dominant paths, while the Clustered Channel model assumes a large number of scatterers grouped into clusters. The choiceof which model to use depends on the specific characteristics of the MIMO channel being modeled and the desired level of complexity and accuracy of the channel model.

The FDC model is often used when the channel exhibits a limited number of significant propagation paths. It provides a simplified representation of the channel that can be easier to analyze and simulate. However, it may not capture the full complexity of channels with rich scattering, which can result in inaccurate performance predictions for certain MIMO systems.

The Clustered Channel model provides a more realistic representation of channels with limited scattering compared to the FDC model. By considering the presence of clusters, it can capture the spatial and temporal variations of the channel more accurately, leading to improved performance predictions for MIMO systems in poor scattering environments.

The main difference between the Finite Dimensional Channel model and the Clustered Channel model lies in their level of complexity and accuracy in representing poor scattering MIMO channels. The FDC model assumes a finite number of paths without explicitly considering clustering, while the Clustered Channel model introduces the concept of clusters to better capture the characteristics of the channel with limited scattering

Firstly, this is an interesting topic. I have seen and read the specific explanations provided by the experts. Secondly, I personally believe that it is necessary to consider these in conjunction with the challenges and scenarios you are solving.

Moreover, the main difference between the two channel models is not only in the physical sense. It is suggested to use Formula and program simulation to demonstrate. It is best to have a common scenario and issue.

Furthermore, channel models only depict certain main features and cannot exhaust all possibilities. Most importantly, you need to focus on your goals.

Finally, I hope these suggestions can bring you good luck.

Best wishes

Meng Gao