LOL, I’ll give it a go, but I could be wrong.
It looks like it’s the study of how a signal, once generated, changes and evolves, depending on various factors, by the time it hits the receiver. For instance, looking at computer signals going through a WiFi connection, and how those signals change and possibly evolve by the time they hit another computer.
I would assume that if such things weren’t studied, the data could become corrupt by the time it reaches the end user, and thus would need to be modified to take those variables into account.
That’s my guess from reading those links anyway… :P