A Novel Multi-Service Small-Cell Cloud Radio Access Network for Mobile Backhaul and Computing Based on Radio-Over-Fiber Technologies

Small-cell systems based on cloud radio access network (cloud-RAN) architecture have been proposed as promising solutions to meet the capacity demand of the future wireless access networks in a cost-effective and power-efficient way. High-speed and scalable backhaul links between the centralized baseband processing units (BBUs) and the remote antenna units (RAUs) are very important to support the small-cell cloud-RAN. Conventionally, digital baseband I/Q samples are transmitted in the cloud-RAN backhaul, which puts stringent requirements on backhaul bandwidth, latency, and jitter. In this paper, we propose a novel multi-service small-cell wireless access architecture based on radio-over-fiber technologies (cloud-RoF access network). By utilizing analog radio frequency (RF) signal transmission in the optical backhaul links, high-speed data transmission can be achieved with highly simplified RAU design. In addition, by combing RoF with optical wavelength division multiplexing (WDM) techniques, multiple bands, multiple services and multiple operators can coexist in a shared optical infrastructure without interference. Two-operator coexistence in a shared small-cell cloud-RoF access network is demonstrated in an in-building testbed by using off-the-shelf optoelectronic components and commercialized WiMAX base stations and clients. In addition, the feasibility of delivering both conventional wireless services and future-proof millimeter-wave services is also demonstrated in the proposed multi-service small-cell cloud-RoF access system.