Experimental investigation of cascaded SMF-MMF-dithering technique for nonlinear compensation in fiber-wireless system

Abstract

In order to effectively extend the coverage of an eNodeB (eNB), a simple relay node (RN) is the efficient solution with fiber-wireless connectivity as the interface between eNB and RN. The optimum coverage enhancement can be achieved by connecting many RNs to a single eNB, which requires high splitting ratio at the optical access layer. Therefore, high optical launch power (OLP) is a primary requirement to compensate the loss induced by optical splitters with high splitting ratio. The only drawback in this situation is the underlying nonlinearity induced by high OLP within optical fiber, prominently stimulated Brillouin scattering (SBS). Two well-known solutions were proposed in the past, the first solution was based on Frequency Dithering, and the second solution was by applying specialty fibers with enhanced effective area. Both methods were effective, however, not evaluated under the same conditions, hence the optimum method remains unknown. Furthermore, in order to achieve a more effective method, this paper proposes a unique way to combine both the solutions by cascading multimode fiber (MMF) with traditional single mode fiber (SMF) network and concurrent integration of the Dithering technique, termed as SMF-MMF-Dithering techniques. By applying the unique technique, SBS is further suppressed and provided ∼8 to ∼10 dB of additional power budget.