If it needs to cover both, electronics & communication, it could be something like circuit analysis for communication signal processing topics. Discussion in this topic is both, broad and deep, so you need to focus on a single issue, step by step.

Cheers

The principles and the main concepts of electronics and communications on the several topics you have studied usually are the main topics for the questions on the interview. Some people concentrate for the topics concerns the job you apply for and others discuss with you on your  final year project, In general you should concentrate on the main principles that show you understand. Some textbooks available on the literature that cover the wide scope of these topics.

Good Luck.

Prof. S. EL-Rabaie 

Most probably the general knowledge and prinicpes of Electronics and Communication. You may not expect culculation question unless it is an entry job where you need to do an aptitude test! All the best