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I am working with obstacles in Veins 5.0. I looked into veins example and in config.xml, I found that the obtacle of type 'building' is defined as follows:

<type id="building" db-per-cut="9" db-per-meter="0.4" />

I am wondering what are the effects of db-per-cut and db-per-meter?

My scenario is a straight highway with one lane on each direction. There is an obstacle (of type polygon) between the opposite lanes (i.e., in the middle of the highway). There is only one vehicle moving in each direction, i.e., two vehicles moving in opposite direction meet at the center of highway. When I set db-per-cut="9" and db-per-meter="0.4", then both vehicles are exchanging beacon messages. However, when I set db-per-cut="27" and db-per-meter="1.2", then beacons are not received by any vehicle (achieving my objective).

Although I achieved what I wanted (i.e., vehicles should not exchange beacon if there is an obstacle between them) but I am curious to know how db-per-cut and db-per-meter work?

Does anyone has idea about db-per-cut and db-per-meter?

Yasir Saleem
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2 Answers2

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db-per-cut is the value used for borders, e.g. the "start/end of an obstacle."

db-per-meter is correspondingly the loss for each meter of obstacle

thardes2
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  • Thank you @thardes2 for your answer. But for start/end of an obstacle, we provide it while defining the polygon. No? Also, what are the minimum and maximum allowed values for `db-per-cut` and `db-per-meter`? Thanks. – Yasir Saleem Sep 17 '21 at 09:01
  • You can put whatever you want. Minimum should probably something > 0 – thardes2 Sep 17 '21 at 13:05
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I came across this, from the research group who developed Veins: https://veins.car2x.org/documentation/modules/#obstacles

In this specific article from 2011 you find the answer: http://dx.doi.org/10.1109/WONS.2011.5720204

At section V. you can read this formula: Shadowing attenuation model

Read as: "the received power is equal to transmitted power plus gains minus losses..."

Beta = 9.2 dB/wall * n, where n is the number of walls

Gamma = 0.32 dB/m * d_m, where d_m is the distance between two nodes (cars or whatever.)

Values have been rounded to those you wrote in the question (9 and 0.4)

eugene
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