Multidimensional Multiplexing in Multicore Fibre for Hybrid Optical Backhaul provision: The XCORE Approach

In this paper a critical overview of the required technologies to open up multi-core fibre as a valid solution leveraging optical access networks infrastructure already deployed on the field for hybrid radio-optical backhaul is reported. Optical transmission using multi-core fibre (MCF) has been already proposed as an interesting solution for optical access network, providing a lower installation cost and higher transmission capacity. In this work, we propose and evaluate experimentally the joint use of SSMF and MCF for and hybrid backhaul solution supporting single-carrier (SC) and multi-carrier OFDM connectivity for cellular service and radio transport provision, respectively. The two modulations schemes are supported as a multidimension modulation employing space-dimension multiplexing at the same wavelength over different cores of the MCF, in particular, we compare the performance of single-carrier (SC) and multi-carrier OFDM signals. SC-QAM signals over 2 GHz bandwidth can provide up to 14.22 Gb/s using 256QAM modulation, while OFDM signals with 512 subcarriers over the same bandwidth provide up to 14.36 Gb/s per channel. The optical performance is evaluated for an optical link comprising 10 km on standard single-mode fibre (SSMF) and 150 m multi-core fibre (MCF) for the final connectivity stage considering different received optical power levels. Experimental results confirm that both OFDM and SC-QAM signals meet error-free BER thresholds for modulation orders up to 256QAM, although OFDM requires higher received power levels compared to SC-QAM implementation.