The first part of your question, "reference to various definitions of communication by different authors" can actually be contributed to by another answer already on here: http://references-definitions.blurtit.com/311746/what-is-the-definition-of-communication-given-by-different-authors
That's how I discovered your question, by originally coming to the above page.
This guy, Simon Lazarus, has a good understanding of various quotes about communication.
Now I can help you with the second part of your question, "divided into the process and semiotic schools of thought".
semiotic school is mainly concerned with the "semantics" or the exchange of meaning behind communication. It looks as language, for example, as the creation and distribution of meaning through vocalization, writing, etc...
Semiotics looks at how text conveys meaning, and what role that has to play in communication.
Where that differs from process, is in how meaning can possibly evolve and change like a relationship between textual context and meaning. For example, this quote:
"The other is that a sign is not a thing but an evolving relationship, an interpretation process that plays out over time."