Using transits to communicate?

[selden]

Exoplanet Transits as the Foundation of an Interstellar Communications Network
Duncan H. Forgan1,2
July 13, 2017

https://arxiv.org/pdf/1707.03730.pdf

An ETI ’A’ can communicate with ETI ’B’ if B is observing transiting planets in A’s star system, either by building structures to produce artificial transits observable by B, or by emitting signals at B during transit, at significantly lower energy consumption than typical electromagnetic transmission schemes.