Digitized Radio-over-Fiber Transceivers for SDM/WDM Back-/Front-Haul

In this paper we analyze the perspective of digitized radio over fiber (DRoF) fronthaul, showing how to meet the requirements to cope with the future radio access networks (RANs). This entails the introduction of space division multiplexing (SDM) while increasing the flexibility and capacity of the DRoF transceivers.Since the evolution of the DRoF fronthaul is being revised and re-defined, in the blueSPACE project we propose two different DRoF transceiver options. The first option consists on simple transceiver, based on the recent standard specifications and, therefore, expected to be deployed in the short-term. The second options is a more advanced transceiver that features high flexibility, relying on a strong DSP and targeting a long-term deployment. Besides a basic characterization of both solutions, we also analyze additional aspects related to the design and implementation of these two DRoF solutions and their integration into an SDM based RAN. This includes the programmability and interaction with the control plane.

1. INTRODUCTION

Digitized radio over fiber (DRoF) is a popular fronthaul technology that is being worldwide deployed for giving service to radio access networks (RANs). In order to deal with the high capacity demand of 5G, new radio waveforms featuring increased bandwidth are expected in an environment where small cells are massively deployed [1]. For example, one single antenna element with 800 MHz bandwidth would require 50 Gb/s DRoF; so a 3-sector cell with single antenna elements and massive (16x16) MIMO would require 2.4 Tb/s data rate. This implies DRoF technology to be upgraded in order to guarantee its scalability while meeting its stringent capacity/latency requirements [1]. This may come with a simple adaptation of DRoF to space division multiplexing (SDM) by deploying multicore fibers (MCFs) [2]. This approach does not only deal with the network external plant, but also with the architectures for central office (CO) and cell sites (CSs).