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No, Not All Prediction Methods Are The Same

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No, Not All Prediction Methods Are The Same

Kelly Burroughs
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No, Not All Prediction Methods Are The Same

At the WLPC Conference in Phoenix, 2017 (a great conference for Wi-Fi professionals) our Director of Research – Vladan, gave a talk called ‘Algorithms Behind the Heatmaps: A Deeper Dive’ on the different type of prediction algorithms in our iBwave Wi-Fi planning and design software.

Afterward, we got a few comments from attendees saying they didn’t realize that not all prediction models have the same accuracy, or that even the most complex of prediction models can have some measurement of error. 

So in the follow-up to that great talk, and to spread the propagation word further (somehow that seems like a pun?), here’s a simplified breakdown of the different algorithms that Vladan covered, and can be found in our wireless network design software, and what they mean.

COST 231

The COST 231 model is a common direct path model used to simulate the performance of an indoor wireless network.

Algorithm


Example venue types it works best for?

Typically COST 231 is best used in non-complex venues where you know the material penetration loss. 

Pros and Cons

Pros  Cons 
Fast Calculation
Only direct path is accounted for; no reflected or diffracted paths
Good signal accuracy prediction when used with CAD files Heat map shows unnatural looking ‘shadows’
The more complex the venue, the less accurate the prediction

What does it look like?

Here is an example of COST 231 in an office environment:

COST231

VPLE (VARIABLE PATH LOSS EQUATION)

VPLE is an iBwave patented direct path model that can be used to run prediction with user-defined RF propagation environments (in iBwave this is mostly used on our site survey mobile apps to simulate performance on-site during a survey).

VPL Eequation

User-defined RF environments can be:

  • Semi-open (ex: warehouse)
  • Light (ex: shopping center)
  • Medium (ex: office)
  • Dense (ex: hotel)
  • Very dense (ex: hospital)


The benefit of VPLE is that it can be used directly on images and enables fast calculations and network performance simulations.

Example venue types it works best for?

Non-complex venues (cubicle offices, retail stores, etc)

Pros and Cons

Pros
Cons
Very fast calculations
User needs to define RF propagation environments on the floor plan
Can be used directly on images
Can have limited accuracy (no walls, no penetration loss)
 The more complex the venue, the less accurate the result

What does it look like?

Here is an example of VPLE in an office environment:

VPLE

RAY TRACING

Unlike COST 231 and VPLE, Ray Tracing takes into account all signal paths: direct path, reflected path and diffracted paths as shown here:

Ray Tracing Paths

The benefit of Ray Tracing is largely the accuracy you get as a result of it taking into consideration all of the signal paths.

Example venue types it works best for?

Complex venues (stadiums, multi-level subway stations, shopping malls)

Pros and Cons

Pros
Cons
The best accuracy
Computing-intensive
Can accurately predict signal in complex 3D venues

In iBwave software, we have ‘Fast Ray Tracing’ which strikes a balance between the intensive computing time and the accuracy of the prediction.

What does it look like?

Here is Fast Ray Tracing in an office environment:

Fast Ray Tracing

A COMPARISON OF ALL THREE MODELS FOR AN NHL ARENA

You’ve seen the propagation for each of the three methods for an office environment, now let’s take a look at the results for an NHL arena:

COST 231

Arena-Cost231
Results-Arena-Cost231

VPLE

Arena-VPLE
Results-Arena-VPLE

FAST RAY TRACING

Arena-FRT
Results-Arena-FRT

HOW TO USE EACH OF THE METHODS IN iBwave?

Using iBwave Wi-Fi as an example, you can select which propagation method you will use depending on the venue you are designing for.

To select the prediction method, simply go to the ‘Prediction’ panel, select the Properties icon and go under the ‘Specific’ tab to select the Propagation model.

Prediction Methods

WANT TO LEARN MORE?

Vladan, our Director of Research, recently did a great talk that goes into more depth about each of these methods,  including case studies at the recent WLPC show in Phoenix, Arizona.

You can watch Vladan’s presentation, complete with walkthrough of each case study here.

Enjoy

Kelly Burroughs

Kelly Burroughs

Product Marketing, iBwave
Creative geek working in the wireless world. Things I enjoy: wireless jokes, antenna patterns, product stuff, t-shirts, writing, pizza, technology, design, bicycles, basketball and photography. In no particular order.
Kelly Burroughs
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