A Bidirectional RoF System for the Multi-Band Signal with Mitigation of the Nonlinear Effects

Abstract

A bidirectional full duplex radio over fiber (RoF) system is proposed for multi-band signal generation and transmission. A multi-band signal is generated at the central station (CS), which includes 10 GHz baseband, 40, and 70 GHz millimeter-wave (mm-wave) by optical frequency multiplication technique of radio frequency (RF) local oscillator (LO) with frequency of 15 GHz. The simultaneous transmission of the 16-QAM OFDM-based multi-band downlink signal and 4-QAM uplink signal over a single fiber is demonstrated. The carrier for uplink transmission is extracted from the unmodulated downlink signal with tunable FBG which is modulated by OFDM-based 4-QAM uplink data obtained from the user end via an antenna. The frequency reuse from the downlink signal makes the base station (BS) free from the laser source. At the user end, the multi-band signals for multi-serve application are obtained by heterodyne beating of multiple bands. An increase in launch power induces fiber dispersion and non-linearities like self-phase modulation (SPM) and cross phase modulation (XPM), which depends on the nonlinear refractive index of the fiber. Different industrial standard fibers with common specifications and modulation format along with co-shared components are deployed, and system performance is analyzed. The stimulated Brillouin scattering (SBS) can be mitigated by optimizing the launch power within the SBS threshold. The nonlinear effects are minimized at the system level without the requirement of additional digital signal processor (DSP) . The theoretical and simulation analysis shows that the designed bidirectional RoF link exhibits an improved system performance for bidirectional transmission with negligible power penalty.

KEYWORDS:

• Bidirectional transmission
• Cross-phase modulation (XPM)
• Self-phase modulation (SPM)
• Multi-band signal
• Nonlinear impairments
• Stimulated Brillouin scattering (SBS)

ACKNOWLEDGEMENT

The authors like to mention the support by the Department of Science and Technology, Govt. of India under WOS-A Scheme, and DRDO, DST-FIST, Govt. of India for simulation tool OptiSystem and SRM Institute of Science and Technology. (Grant number: SR/WOS-A/ET-57/2017).

DISCLOSURE STATEMENT

No potential conflict of interest was reported by the author(s).

Additional information

Funding

This work was supported by Department of Science and Technology India: [Grant Number SR/WOS-A/ET-57/2017].

Notes on contributors

C. Kavitha

C Kavitha graduated from Anna University with a Bachelor of Engineering degree in electronics and communication engineering in 2011. She received her master's degree in communication systems from Anna University in 2013. Currently, she has been pursuing PhD in the ECE Department of SRM Institute of Science and Technology, Kattankulathur, since 2018. Her research interests include radio over fiber (RoF) systems, optical communication system design, advanced optical modulation formats, non-linear fibers. Email: [email protected].C T Manimegalai received the Bachelor of Engineering degree in electronics and communication engineering from Bharathidasan University, Tamilnadu, India, in 1996. She received her master's in applied electronics from Madurai Kamaraj University, Tamil Nadu, India, in 1998. She has done her doctorate in the field of wireless communications and working as associate professor at SRM Institute of Science and Technology, Chennai, India.Her research interests lie in the area of ultra-wideband, wireless sensor networks, image processing, and MIMO-OFDM systems.