Colorless WDM-PON fronthaul topology for beyond 5G C-RAN architectures

Abstract

The 5G/6G fronthaul link is one of the main drivers for the rising of new passive optical network (PON) standards. Among the possible technologies, wavelength division multiplexing (WDM) is likely the most suitable to meet the stringent performance requirements of fronthaul applications. However, to reduce the implementation and operation costs of WDM-PONs, one of the main issues is the availability of colorless optical sources, in which the same optical hardware can be used to generate any wavelength required by the network. In order to address these needs, in this paper, we propose and analyze a bidirectional colorless WDM-PON topology serving as an analog fronthaul for a 5G and Beyond scenario, comprising the use of recently demonstrated tunable VCSEL lasers for the downlink and the carrier reuse technique for the uplink. We numerically evaluated radio-over-fiber transmission performance when transmitting 1.25 Gbps at the RF carrier frequency of 3.5 GHz and 10 Gbps at the RF carrier frequency of 26 GHz, over a 20 km optical link. The simulation setup is validated by direct comparison against available experimental results, and the obtained results fall within the 3GPP requirements, demonstrating that the proposed topology is a suitable candidate for a future fronthaul configuration.