Indoor MIMO Through Post-Processing

Perform indoor network planning with MIMO using post-processing.

Model Type

In this indoor network planning project, the geometry of a multi-story building is preprocessed to use intelligent ray tracing model (IRT).

Sites and Antennas

The transmitter is a single omnidirectional antenna with a carrier frequency of 1849.90 MHz. The antenna (the blue dot near the center of Figure 1) is placed at a height of 10 m, which is three meters above the level of one of the floors.
Tip: Click Project > Edit Project Parameter and click the Sites tab to view the sites and antennas.
The results of interest are computed at a height of 8.5 m (1.5 m above the floor level).
Figure 1. The multi-story building in 3D.


Air Interface

The air interface is based on long term evolution (LTE). Orthogonal frequency division multiple access (OFDM/SOFDMA) is selected for multiple access. No MIMO technology is assigned (yet) for the carrier. MIMO related results are derived through post-processing once the propagation results for the isotropic antenna are known.

Tip: Click Project > Edit Project Parameter and click the Air Interface tab.

Computational Method

The prediction method used in this model is 3D intelligent ray tracing (IRT - with preprocessed data). This method requires a preprocessed geometry database.
Tip: Click Project > Edit Project Parameter and click the Computation tab to change the model.
The preprocessed database is created in WallMan where result resolution and prediction heights are specified.
Tip: Click Project > Edit Project Parameter and click the Simulation tab to set the prediction area.
In this example, the resolution of prediction results is set to 1.0 m and the prediction height is 8.5 m.

The deterministic mode uses Fresnel equations for the determination of the reflection and transmission loss and geometrical theory of diffraction for the determination of the diffraction loss. This approach uses four physical material parameters, namely thickness, permittivity, permeability, and conductivity.

Results

Propagation results show at every location the power received from the transmitting antenna. Results are calculated for a single prediction plane at a height of 8.5 m.

Figure 2. Received power on the prediction plane.


The simulation of a single isotropic (omnidirectional) antenna allows MIMO simulation through post-processing.
Tip: Click Computation > Propagation Postprocessing incl. Tx and Rx to obtain MIMO results.

On the Postprocessing of Mobile station dialog, click Edit Parameters to define antenna patterns and (optionally) small arrays. This can be done for both the base station and the mobile station. Thereafter, click the Start Computation button.

In Figure 3, an example result of channel capacity is shown.
Tip: Click File > Open Result to load channel capacity results.
Figure 3. Channel capacity (MS) results for a MIMO array.


These results are obtained with imported antenna patterns (not part of this example). The effects of the antenna pattern, array orientation and antenna spacing can readily be investigated without solving the entire propagation project again.