Performance comparisons of external modulated hybrid analog-digital signals in electrical and optical domains

A multipurpose network which integrates the functionalities of single radio channel and baseband data distribution has been proposed recently. In this letter, we further propose and compare two possible combination schemes which combine multiple radio channel and single digital baseband data in electrical and optical domains. Linearity of multiple radio channels and performance of digital baseband data are studied in this externally modulated hybrid analog-digital link. It is found that signals combined in the optical domain, while with higher cost, will outperform that in the electrical domain on the carrier-to-noise and distortion ratio. In addition, the baseband data performance is also improved with optical combining scheme since the optimum required modulation index is lower.