Bi-directional Radio-over-Fiber architecture based on up- and down-Conversion

Radio-over-Fiber (RoF) is a promising technology with a number of benefits including huge bandwidth, high reliability, transparency and flexibility that makes it attractive to fulfill future broadband application requirements. Such ‘optical-wireless network’ architectures have potential to support broadband wireless access over 1 Gbps. Developing a cost-effective bi-directional solution that supports uplink and downlink data transmission between Control Station (CS) and Base Stations (BSs) is one of the research issues in RoF. We present a bi-directional RoF solution, where downlink scheme is based on photonic frequency upconversion. SOA-MZI is used to mix IF and LO signals and all-optically up-convert IF signal. Signals in intermediate frequency (IF) band (2.5GHz) along with LO (37.5GHz) are generated in CS. IF signals are up-converted to RF (40GHz) at remote node (RN). An additional un-modulated carrier at 6.5 GHz is sent along with downlink data and is also up-converted to 44 GHz at RN, this is used as a LO for down conversion of uplink data. Uplink down-converts RF signal (36 GHz) to IF (8 GHz) at BS. As downlink optical carrier at output of SOA-MZI is in double side band format, optical carrier is extracted and re-used for uplink data transmission. Down- and up-link radio signals are DPSK modulated at 155 Mbps. In this paper, we present proposed solution and simulation results for uplink and downlink. Signals at BS and CS, for downlink and uplink respectively are de-modulated with acceptable BER, with BER ≪ 10
⁻⁹
. By deploying the proposed system, a cost-effective RoF architecture can be implemented.