All Photonic Analogue to Digital and Digital to

All Photonic Analogue to Digital and Digital to Analogue Conversion Techniques for Digital Radio over Fibre System Applications S. R. Abdollahi, H. S. Al-Raweshidy, S. Mehdi Fakhraie*, and R. Nilavalan WNCC Group, School of Eng. and Design, Brunel University, Uxbridge, Middlesex, UB 8 3 PH, UK, and *University College of Engineering, University of Tehran, North Kargar Ave. , Tehran, 14395 -515, Iran. E-mail: {seyedreza. abdollahi, hamed al-raweshidy, rajagopal. nilavalan}@brunel. ac. uk, and fakhraie@ut. ac. ir Radio over Fibre (Ro. F) Technique Integration of wireless and fibre optic communication technologies, and modulating wireless signals over optical carrier for transporting over fibre optic cable. Ro. F Features Centralizing signal processing, performance and error monitoring, share resources, and control and management. Cheaper, smaller size & simpler base stations. Smaller cells: allocates higher bandwidth to end-users. Future proof. Green: Lower power radiated electromagnetic wave, lower power consumption, fibre low attenuation and loss. Reduce the maintenance cost. Could be accommodated with passive optical network (PON) Infrastructures. Can use wavelength division multiplexing (WDM) technique for improving the network throughput. Photonic Analogue-to-Digital and Digital-to-Analogue Conversions An 8 -bits photonic sampling and quantization ADC is designed by using 30 Gigasample/s mode-locked laser. A photonic DAC converts photonic digital waveform to analogue optical signal. By using the proposed PDAC, the necessity of optical to electrical conversion will be fulfilled by only a high-speed photo diode. For reducing the cost and complexity of the system, the optical sampling pulse has been reused at base-station for sampling the uplink RF signal. The SFDR and ENOB at 160 Gigasample/s sampling rate are equal to 9. 82 d. B and 1. 63, respectively. Simulation Results and Conclusions The performance of DRo. F link is investigated and compared with ARo. F system over 15 and 20 kilometres standard single mode fibre length. PADC’s performance is affected by the laser’s jitter, the nonlinearity of MZM, photonic amplifier and other photonic devices performance. In the digital radio over fibre, the dynamic range is independent of the fibre length. Digital Ro. F & Integrated Ro. F System. Digital Ro. F (DRo. F) link can maintain the dynamic range more independent than optical fibre link distance. The analogue RF signal digitized by using the Photonic Analogue-to-Digital Converter (PADC). Generated digitized-RF data stream and RF analogue signal are transported over optical fibre network by using WDM technique. The photonic DAC of RF system at the base station or access point converts digital photonic signals to its analogue optical modulated signal. (Top) RF signal, (Bottom) Sampled optical signal. Eye diagram of 1 Gbps ASK modulated signal with 10 GHz carrier over 15 km ( Left) 20 km (Right) length of single mode fibre: (top) ARo. F system, (bottom) DRo. F system. ENOB variation versus sampling rate.