Communication equipment communicates in a licensed frequency band using a licensed band physical channel structure (licensed structure) and communicates in an unlicensed frequency communication band using an unlicensed band physical channel structure (unlicensed structure) where the unlicensed structure includes at least the same symbol times and subcarrier frequency divisions as in the licensed structure. The symbol times and subcarriers form a plurality of time-frequency communication resource elements. A set of symbol times and subcarrier frequency divisions form a licensed reference subset of communication resource elements that are allocated for reference signal transmission in the licensed structure. The same set of symbol times and subcarrier frequency divisions form an unlicensed reference subset of communication resource elements that are allocated for reference signal transmission in the unlicensed structure.