In this research paper, we report on a simulation study of the Radio over Fibre (RoF) Carrier Suppressed Single Sideband (CS-SSB) modulation scheme. This scheme is based on a Dual Parallel Dual Drive Mach-Zehnder modulator (DP-DDMZM), for a long-distance transmission. The proposed system consists of the combination of a carrier and a message signal at two parallel modulators, where the laser and link power is varied for the two different dispersion compensation techniques. We found that by suppressing the optical carrier and cancelling one sideband, we can limit the nonlinear effects that are caused by power fading and interference. We demonstrate that by varying the launched laser and link power up to optimised threshold levels, the signal to noise ratio (SNR) increases and the Q-Factor improves significantly. Our proposed RoF optic communication architecture can support an extended reach transmission of up to 200 km without dispersion compensation. Moreover, for the bitrate of 10 Gbit/s and span length of 25 km, we achieved a span ratio of 520, alternatively viewed as the system link signal transmission distance of 13,000 km. Therefore, this method is cost-effective and less complex. (C) 2018 Elsevier GmbH. All rights reserved.

In this paper, we have proposed a long-haul optical transmission system, based on a single sideband (SSB) modulation scheme. Analytical and simulation models have been developed, optimised and demonstrated for the proposed SSB system configurations. The SSB modulation scheme was proposed to overcome dispersion in the fibre. We have shown that the related link losses can be minimized by increasing the quality of the optical signal at the modulation. We have optimised the radio over fibre configuration scheme based on dual parallel dual drive Mach–Zehnder Modulator, thereby increasing transmission length of the fibre. With the proposed SSB, by suppressing some of the harmonics and cancelling one of the sidebands, we have halved the RF power fading and interference. The developed analytical (theoretical/mathematical) model agrees very well with the simulation results using two (both) different commercial simulation tools. The optical signal is boosted while minimizing the number of repeaters. We report a SSB configuration, compensation and amplification with individual spans of 150 km, by extending the length of the link up to 3250 km. The proposed system configuration exhibits high performance with less complexity and lower cost.

In this paper, we report a novel approach of microwave frequency downconversion with improved conversion efficiency and high dynamic range, using two different configuration schemes. The first proposed scheme is designed by using a dual-parallel dual-drive Mach-Zehnder modulator and the second one using dual-parallel dual-phase modulator. The radio frequency (RF) message signal and the local oscillator (LO) signal are feeding these two parallel connected modulators. By using a tight control of the system parameters, we have reported an effective optical carrier suppression, resulting in high conversion efficiency. We show that when the link is amplified, the relation between m(LO) and m(RF) plays a vital role and gives a high value of conversion efficiency, where key parameters lead to the LO and RF modulators modulation index. The conversion efficiency is improved by 5.72 dBm, compared with previously published work using DP-MZM, and 28.4 dBm, compared with the cascaded connected modulator. An experimental demonstration of a proof of concept is also carried out where the intermediate frequency to noise ratio of 69.5 dB is reported.

With the recent data rate increase it is very challenging to build a fibre optic network that would enable a high data rate transmission over a long haul distance. The signal suffers large degradation over a certain distance due to distortion by the nonlinear effects of the optical fibres. In particular, transmission of high data rates over existing fibre optic systems, while keeping the cost low, avoiding an increase of the system’s complexity and the usage of expensive devices, would be a very challenging task. In this paper, we address this problem by increasing the transmission distance in the fibre optic links for up to 2500km. We have used Standard Single Mode Fibre (SSMF) and Dispersion Compensation Fibre (DCF), where DCF is used as a loss compensator in Radio-Over-Fibre (RoF) systems. A mixture combination of the pre, post and symmetrical fibre compensation schemes were developed to overcome the dispersion in the fibre. We have found that in order to achieve high RF over fibre optic system performance for high data rates and long transmission, there is a requirement to upgrade the optical configuration scheme in a proportional way, by raising the length of the fibre span, compensation span and amplification. We have reported optimised RF over fibre configuration schemes that would have a great impact on reducing the cost, reducing the system’s complexity and avoiding usage of expensive devices, in order to achieve high data rate transmission over existing fibre optic systems.