Carrier Aggregation of Three OFDM Signals Using a Single Oscillator and I/Q Modulator

In this paper, a novel method is presented, which makes carrier aggregation (CA) using a single local oscillator and an in-phase/quadrature (I/Q) modulator, possible. Three component carriers with orthogonal frequency division multiplexing are generated at 2.2, 2.5, and 2.9 GHz to show the feasibility of the method for the worst case scenario that is the interband CA. A special procedure to compensate the I/Q imbalances specific to this method is explained as well. Moreover, according to Nyquist criterion, the signal should have a sampling rate at least twice the signal highest frequency. In this method, the sampling rate of the digital-to-analog converter is significantly reduced, because, the baseband signal is distributed over negative and positive frequencies. In addition, the demodulation process of these frequency-aggregated signals using a three-phase demodulator is explained and experimental results are presented.