English often prefers prepositional phrases to straight participles.

It is being reconstructed - it is under reconstruction
The observed team - the team under observation

The considered design - the design in question
The disputed matter - the matter in dispute

Základem bezpečnosti je sama použitá technologie
The basis for this security is the actual technique in use

Tak můžeme přidat bezdrátový segment do již stávající klasické sítě
In this way we can add a wireless segment to a standard network that is already in existence.