Carrier aggregation (CA) enables mobile network operators worldwide to provide faster data, and allows mobile devices to communicate on multiple LTE bands simultaneously. This, however, creates the challenge of avoiding interference between the bands while keeping up good reception and battery life. Multiplexers are an excellent solution for CA combinations that use closely spaced bands since they provide isolation between and within bands, while allowing them to connect to the antenna at the same time. This white paper discusses the challenges of carrier aggregation, and the important benefits of using multiplexer solutions to solve them.