Mode Division Multiplexing Bidirectional Transmission System using Double Clad Fiber for Mobile In-Building Solutions

This paper shows the conceptual model of the possibility of simultaneously transmitting data and power on the same optical fiber by adopting the Power Over Fiber PWoF concept and Mode Division Multiplexing MDM. MDM is the data transmission multiplexing scheme of choice where two modes of light are considered; one mode carries the downlink, while the other mode carries the uplink information. Adopting the PWoF, remote devices can be powered by the optical energy transferred on the same optical fiber. Double Clad Fibers DCF are introduced as the transmission medium. DCF consists of the core, which is a few-mode fiber core capable of handling the two needed modes, the inner cladding which has a relatively large diameter and is capable of handling the optical power, and the outer cladding. The proposed system can reduce the complexity and the operations cost, suitable to be used in In-Building Solutions IBS.

I. Introduction

The growth of LTE-based radio access networks has drawn attention to the Cloud Radio Access Network (CRAN), which has lower operating and capital expenses. The Remote Radio Unit (RRU) and Baseband Unit (BBU) are separated in the CRAN. The aggregate BBU serves a significant number of RRUs and is the shared central BBU pool where baseband processing and control/management tasks are carried out. The digitalized data link between RRUs and BBUs is currently specified as fronthaul using the Common Public Radio Interface CPRI. To meet the demands of high-capacity 4G/5G mobile communication services with MIMO antennas, Wavelength Division Multiplexing (WDM) technology has been suggested to transport CPRI data for fronthaul. This is because WDM offers advantages such as high spectrum efficiency, service transparency, and energy savings.