Speakers:  Lin Cheng and Jing Wang

Title:
Investigation of Channel Cross-Modulation in Multiband Radio-over-Fiber Systems

Abstract:
By exploiting the large bandwidth and low loss of optical fibers, as well as the mobility of wireless services, radio-over-fiber (RoF) technology has been considered as a promising platform to integrate the next generation optical and wireless access networks. In order to simultaneously deliver multiple services, and exploit the entire 7-GHz license- free bandwidth at 60-GHz, multiband RoF systems have attracted intensive research interest; but on the other hand, also suffer from transmission impairments induced by the nonlinearity of RoF links. In this talk, data-dependent channel cross-modulations (XMs) introduced by optical modulators in multiband RoF systems are investigated and illustrated, including the intra-band XM between the in-phase (I) and quadrature (Q) components of vector signals, as well as the inter-band XM between multiple bands of scalar/vector signals. A closed-form theoretical analysis is presented to model both intra- and inter-band XMs, and experimental measurements are carried out to validate the theoretical prediction. It was demonstrated that scalar signals only suffer from inter- band XM; whereas vector signals suffer from both intra- and inter-band XMs. Intra-band XM induces constellation compression distortion to vector signals; while inter-band XM induces eye-diagram degradation to scalar signals, and constellation scaling distortion to vector signals. To mitigate the nonlinear impairments, pre-distortion technique is also implemented, and effective cancellations of both intra- and inter-band XMs are achieved.

Speaker Bio:
Lin Cheng received his B.S. degree and M.S. degree (first-class honors) in electronic engineering from Tsinghua University, Beijing, China, in 2009 and 2012, respectively. He is currently pursuing the Ph.D. degree in electrical engineering at Georgia Institute of Technology, Atlanta, GA. Currently, he is working on radio-over-fiber systems and wireless access networks.