Perhaps you should try some spelling variations:
communication relation » communication relations, communication relational, communication relating
based discussion » brief discussion
relation based » correlation based, location based, equation based
array ang » arrays ang, array along, array range
arrays a » arrays _

You may be able to get more results by adjusting your search query.

• Performing a fuzzy search may retrieve terms with similar spellings: communication relation based discussion ((array ang) or (arrays a))~.
• If you are trying to use Boolean operators, they must be ALL CAPS: communication relation based discussion ((array ang) OR (arrays a)).
• Adding a wildcard symbol may retrieve word variants: communication relation based discussion ((array ang) or (arrays a))*.