Design and analysis of SCM-RoF system deploying VCSEL

A hybrid technique called SCM-RoF, which synergizes the two communication domains, radio and optical, is employed to transmit the RF signals from base station to RAU (Remote Antenna Units) on optical fibre link to utilize the benefits of both SCM (Sub Carrier Multiplexing) and RoF (Radio over Fibre) technology using a relatively new type of laser called VCSEL laser as optical source. The performance of the SCM-RoF system deploying VCSEL Source is studied by designing a communication system comprising a transmitter deploying VCSEL laser at 1550 nm as optical source, Mach Zender as the optical modulator, single mode optical fibre link and the receiver employing a photo detector. The performance analysis of the system is done by using four parameters viz. fibre length, number of subcarrier channels, frequency spacing between channels and position of first subcarrier frequency using three modulation formats ASK, FSK, PSK. A comparative study in terms of BER (Bit Error Rate) and Eye diagrams for the three modulation formats is presented. The maximum length of 45 km, with 125 channels having subcarrier frequencies between 2-20 GHz is obtained which are shown here graphically.