RoF Signal Research Articles

Secure RoF based 5G backhaul communication using semiconductor laser generated optical chaos

Abstract The fifth generation is considered as the revolutionary technology around the world, but this revolution brings many challenges along with it, especially when employ the advance properties such as massive multiple-input–multiple-output (MIMO) antennae, network densification and new spectrum exploration etc. One more challenge which we consider working on is the cost effective, secure backhaul communication system. The connection of massive and large traffic cells with the core network by using backhaul demands extraordinary requirements concerning availability, latency, capacity, cost efficiency and most importantly security. In the present work, we demonstrated the security implementation in 5G backhaul network by securing RoF signal through optical chaos generated by semiconductor laser. RoF signal of 60 GHz is generated in unlicensed band and after chaos masking with chaos, signal is transmitted over optical fiber to analyze the results. Simulations are carried out by using licensed software (Optisystem version 14.0) and results are analyzed by using multiple data rates and fiber lengths. Moreover, analysis of our scheme is carried out by using RZ and NRZ formats and by varying the power of the laser.

Performance Analysis of the WDM Schemes for RoF System with Various Bit Rate

Communication that combines the methodologies of the two communications can be considered as communication fiber optic communication and can be used in communication systems and wireless. The integration of optical and wireless networks can function to increase mobility and capacity as well as reduce costs in access networks. Radio over fiber (RoF) can be a solution for many problems because it can control many base stations (BS) connected to a central station (CS) with an optical fiber. The high bit error rate (BER) and low Q factor value are caused by the Rof signal head received in low quality, so the receiver may not operate on high data speed networks. The solution to different signal problems and can be done with single mode fiber is the Wavelength Division Multiplexing (WDM) network. BER must be reduced to a guaranteed value, and the Q factor must be increased. WDM-RoF probes with different fiber lengths at various channel distances will be: simulated using Optisystem software, and the performance of the RoF receiver is measured and analyzed depending on the obtained BER, Q-factor value, and eye aperture height. The effects of degradation factors such as attenuation and dispersion are very limited with the addition of EDFA amplifier to Single Mode Fiber (SMF). The higher the bit rate of a communication system, the lower the performance of the system. In this study, analysis of the WDM-Rof system with bit rate variations was carried out to determine the bit rate value that still met the standard. From the simulation results, the Q-Factor and BER values at a bit rate of 11 Gbps do not meet the standards, i.e 4.50508 and 2.5390e-006.

Optomagnonically induced RoF chaotic synchronization

Optomagnonics is a good platform for the interplay of radio frequency and optical signals, which are the primary communication carriers in the present day. On the basis of optomagnonics, we provide a multi-scale method for analyzing its behavior, including frequency comb and RoF chaotic synchronization at the microwave scale. Adjusting the pump light intensity permits the transition of RoF signals between harmonics, frequency combs, and chaotic movements. The dual optomagnonical device enables the synchronization of RoF signals between different cavities. Our study will contribute to the use of multiscale electromagnetic wave coupling in both conventional and quantum information applications.

Overlaying 5G radio access networks on wavelength division multiplexed optical access networks with carrier distribution.

As 5G communication matures, the requirement for advanced radio access networks (RAN) drives the evolution of optical access networks to support these needs. Basic RAN functions, mobile front-haul to the backbone and interconnected front-end remote radio units, must support and enable data rate surges, low-latency applications, RF coordination, etc. Wavelength division multiplexed optical access networks (WDM-OANs) provide sufficient network capacity to support the addition of RAN services, especially in unused portions of WDM. We propose and demonstrate a method for RAN overlay in WDM-OANs that employ distributed carriers. In such systems, the carrier is modulated at the central office for direct-detected downstream digital data services; later the same carrier is remodulated for the uplink. We propose the use of silicon photonics to intercept the downstream and add 5G signals. We examine the distributed-carrier power budget issues in this overlay scenario. The carrier power must be harvested for direct detection of both digital and RoF services, and yet hold in reserve sufficient power for the uplink remodulation of all services. We concentrate on the silicon photonics subsystem at the remote node to add RoF signals. We demonstrate the overlay with a fabricated chip and study strategic allocations of carrier power at the optical network units housing the radio units to support the overlay. After the successful drop and reception of both conventional WDM-OAN and the newly overlaid RoF signals, we demonstrate sufficient carrier power margin for the upstream remodulation.

Design Issues of Digital and Analog Chaotic RoF Link Using Chaos Message Masking

This work presents the joint use of Radio Over Fiber and optical chaos to investigate the secure ROF link. Merging the two technologies, optical chaos for physical layer communication security and Radio over Fiber creates new design issues which have been identified and studied in detail in this paper for both analog Radio Frequency/Intermediate Frequency and digitized data. A semiconductor laser diode is driven into chaotic region using direct modulation scheme and RoF signal is added by chaos message masking scheme. The chaotically masked signal is transmitted over an optical communication link to investigate the propagation issues and synchronization of chaos at the receiver. The transmitted chaos is synchronized at the receiver to unmask the signal by using subtraction rule. To investigate the performance of chaotic communication system for Radio over Fiber transmission, the figure of merits like Bit error rate, Quality factor, Eye Opening Penalty and Root-mean-squared phase jitter are studied for digital data and Signal to Noise ratio and Total Harmonic Distortion are studied for analog waveform to address the effects of link length and data rate/message bandwidth.

Analog Radio-over-Fiber Fronthaul by a WDM-PON employing Double RSOA Self-Seeding and Carrier-Reuse Techniques

WDM-PON has been considered a promising solution for future fronthaul links concerning new mobile networks applications. However, in order to avoid inventory problems and reduce operation costs, there is a need for colorless sources, where the same basic optical source can be used regardless of the desired wavelength. Also, the digital RoF scheme, which has been employed so far, might require a bandwidth that is prohibitive even for optical fiber links. In this paper, we propose and numerically investigate a bidirectional colorless WDM-PON fronthaul transporting analog RoF signals as an alternative to meet these demands. All simulations were performed using a framework calibrated with experimental data. For the downstream, we employ a double-cavity self-seeding technique, while the upstream is performed by a cascaded-RSOAs carrier-reuse approach. BER and EVM simulation analysis are presented for various data rates, modulations formats and RF bands ranging from 1 to 5 GHz, demonstrating the feasibility of our proposed topology as a novel fronthaul approach.

A Study of Secured Enabled Passive Optical Network Enabling RoF

<p>Innovation is an incorporation of radio sign in optical fiber transmission inside of system foundations that are thought to be financially savvy, pragmatic and moderately adaptable framework setup for whole deal transport remote signs. This venture proposes a Next era PON construction modeling backings RoF and OFDMA signal coordination without WDM lasers, and exhibit that 10-Gb/s OFDMA and three RF signals at 2.1GHz are transmitted more than 20km SMF in a 32-ONU in both upstream and downstream bearing. A security control unit and an optical switch are utilized associating four Optical Line Terminations (OLTs) with everyone serving just 32 Optical Network Units (ONUs). Insurance control unit gathers data of ONUs served by each OLT, and when an OLT falls flat, it will educate an active OLT to help its unique ONUs together with the burden served by the fizzled OLT.</p>

Real-Time Q-Band OFDM-RoF Systems With Optical Heterodyning and Envelope Detection for Downlink Transmission

We experimentally demonstrate a real-time optical heterodyning and envelope detection-enabled orthogonal frequency-division-multiplexing-based Q-band radio-over-fiber (OFDM-RoF) system. Envelope-detector-based down-conversion is applied to the mobile terminal (MT), which makes MT insensitive to the phase noise of the beating millimeter wave signal and enables the generation of RoF signals using two free-running non-narrow line-width distributed feedback lasers in the central office. The error-free transmission real-time Reed–Solomon- coded 16-quadrature-amplitude modulation(16-QAM)-OFDM-RoF signals with a net bit rate of 1.2 Gb/s at 35/40 GHz over 4.5-km single-mode fiber (SMF) and 0.8-m wireless distance is reported in this paper. Additionally, the transmission performance of the signals at 35 GHz with the net bit rate from 1.5 to 5.9 Gb/s is also investigated by offline digital signal processing approaches. It indicates that the BER of the signal with the net rate up to 4.4 Gb/s after the SMF and wireless link transmission is below a 7% hard-decision forward error correction (FEC) threshold of 3.8 × 10−3.

Multi-service small-cell cloud wired/wireless access network based on tunable optical frequency comb

In this paper, we demonstrate a novel multi-service wired/wireless integrated access architecture of cloud radio access network (C-RAN) based on radio-over-fiber passive optical network (RoF-PON) system, which utilizes scalable multiple- frequency millimeter-wave (MF-MMW) generation based on tunable optical frequency comb (TOFC). In the baseband unit (BBU) pool, the generated optical comb lines are modulated into wired, RoF and WiFi/WiMAX signals, respectively. The multi-frequency RoF signals are generated by beating the optical comb line pairs in the small cell. The WiFi/WiMAX signals are demodulated after passing through the band pass filter (BPF) and band stop filter (BSF), respectively, whereas the wired signal can be received directly. The feasibility and scalability of the proposed multi-service wired/wireless integrated C-RAN are confirmed by the simulations.

A full-duplex lightwave transmission system with an innovative VCSEL-based PM-to-IM converter.

A full-duplex lightwave transmission system employing innovative VCSEL-based PM-to-IM converters to deliver intensity-modulated CATV/phase-modulated RoF/intensity-remodulated RoF signals over two 40-km SMFs links is proposed and demonstrated. To be the first one of employing VCSEL-based PM-to-IM converters in full-duplex lightwave transmission systems, the downstream light is successfully intensity-remodulated with RoF signal for up-link transmission. Good performances of CNR/CSO/CTB are achieved for downstream CATV signal transmission, and low BER values are obtained for both downstream and upstream RoF signals transmissions. Our proposed systems present brilliant performances in delivering hybrid CATV and RoF signals. Such a full-duplex lightwave transmission system would be very attractive for fiber trunk applications to provide broadband integrated services.

Simultaneous Generation of Independent Wired and Wireless Signals Using a Dual-Electrode MZM in ROF System

In this paper, a novel Radio-over-Fiber scheme to simultaneously generate and transmit baseband (BB) and millimeter-wave (MMW) signal by using a single dual-electrode MZM is proposed. By employing this analog ROF signal transmission techniques, highly transparent fiber-wireless networks, which are ideal for multi-standard wireless system operation can be realized.

Gigabit close-proximity wireless connections supported by 60 GHz RoF links with low carrier suppression

We present an experimental investigation of the 60 GHz optical carrier suppressed radio over fiber systems with less than 5 dB carrier suppression. As a case study, the 60 GHz RoF signal is generated using a 12.5 Gb/s commercially available Mach-Zehnder modulator biased at its minimum point. We report on error free transmission over 20 km of standard single mode fiber and 1 m of wireless distance. Furthermore, the efficiency of photonic RF generation depending on the value of carrier suppression is reported. We argue that transport of RoF signals with low carrier suppression assisted with simplified techniques of lightwave generation, baseband data modulation, and RF downconversion might be a promising enabling technology for fiber support of close-proximity wireless terminals.

Simultaneous generation of WDM RoF signals in an all-optical frequency upconverter utilizing a semiconductor optical amplifier

All-optical frequency upconversion utilizing a semiconductor optical amplifier (SOA) is experimentally demonstrated. Eight optical radiofrequency (RF) signals having the RF frequency of 26.5 GHz are simultaneously generated by four-wave mixing in the SOA. Power penalties for simultaneous generation of eight optical RF signals are less than 1.1 dB. © 2012 Wiley Periodicals, Inc. Microwave Opt Technol Lett 54:2420–2422, 2012; View this article online at wileyonlinelibrary.com. DOI 10.1002/mop.27048

Hybrid Cable Television/Radio-Over-Fiber Transport System Based on Polarization Modulation Technique

A hybrid cable television/radio-over-fiber (ROF) transport system with direction modulation of cable television signals and the polarization modulation of ROF signals is proposed and experimentally demonstrated for the first time. When a multicarrier cable television signal in the optical amplitude domain and an ROF signal in the optical polarization domain are modulated, a single optical wavelength can serve these two signal applications simultaneously. This hybrid transport system not only satisfied the cable television requirements, but also satisfied the demand for high-quality ROF transmission over a 20-km single-mode fiber.

Simultaneous WDM RoF Signal Generation Utilizing an All-Optical Frequency Upconverter Based on FWM in an SOA

A simultaneous all-optical frequency upconversion technique using four-wave mixing in a semiconductor optical amplifier (SOA) is experimentally demonstrated for wavelength-division-multiplexing (WDM) radio-over-fiber applications. Eight WDM optical radio-frequency (RF) signals having the RF frequency of 26.5 GHz are simultaneously generated by mixing eight WDM optical intermediate-frequency (IF) signals having the IF frequency of 2.5 GHz with an optical local oscillator signal of 24 GHz in a single SOA. The power penalty for simultaneous generation of eight WDM optical RF signals at the bit-error rate of 10-9 is less than 2.7 dB.

Phase noise suppression of optical OFDM signals in 60-GHz RoF transmission system

The dispersion-induced phase noise (PN) in an OFDM RoF system at 60 GHz leads to not only subcarrier phase rotation (PRT) but also intercarrier interference (ICI) to severely degrade the transmission performance, when a commercial cost-effective DFB laser with the linewidth of several MHz is adopted. To mitigate both PRT and ICI, a post PN suppression algorithm is proposed, and it does not require any bandwidth-consuming pilot tone. For a 25.78-Gbps 16-QAM OFDM RoF signal using the laser with 1.8-MHz linewidth, employing the algorithm can extend the maximum transmission distance which corresponds to 3-dBm power penalty at the BER of 2 × 10(-3) from 75 km to more than 115 km, i.e. 50% increment of transmission distance.

20-Gb/s QPSK W-band (75-110GHz) wireless link in free space using radio-over-fiber technique

We demonstrate 20-Gb/s W-band wireless transmission in free space with a distance of 30mm using optical signal generation. Optically synthesized QPSK signal and direct optical upconversion technique ease generation of W-band RoF signals for dual purpose of wireline and wireless transmission link. A W-band radio receiver with W-band frequency downconversion and digital signal processing will be applicable for any W-band radio detection.

Adaptively Modulated OFDM RoF Signals at 60 GHz over Long-Reach 100-km Transmission Systems Employing Phase Noise Suppression

We experimentally demonstrated the transmission performance of orthogonal frequency-division-multiplexing (OFDM) signals in a 60-GHz radio-over-fiber system over up to 100-km standard single-mode fiber employing an adaptive bit-loading algorithm. Considering dispersion-induced phase noise, the maximum capacities after different fiber distances are investigated with and without a phase noise suppression (PNS) algorithm for the first time. When a distributed-feedback (DFB) laser with the linewidth of 1.3~4.1 MHz is modulated to carry the radio signals, the PN will result in more than 21.5% capacity decrease after 100-km fiber and 3-m wireless link, and the PNS algorithm which needs no bandwidth-consuming pilot tones can accomplish more than 15.3% capacity increase.

Radio over fiber transceiver employing phase modulation of an optical broadband source

This paper proposes a low-cost RoF transceiver for multichannel SCM/WDM signal distribution suitable for future broadband access networks. The transceiver is based on the phase modulation of an optical broadband source centered at third transmission window. Prior to phase modulation the optical broadband source output signal is launched into a Mach-Zehnder interferometer structure, as key device enabling radio signals propagation over the optical link. Furthermore, an optical CWDM is employed to create a multichannel scenario by performing the spectral slicing of the modulated optical signal into a number of channels each one conveying the information from the central office to different base stations. The operation range is up to 20 GHz with a modulation bandwidth around of 500 MHz. Experimental results of the transmission of SCM QPSK and 64-QAM data through 20 Km of SMF exhibit good EVM results in the operative range determined by the phase-to-intensity conversion process. The proposed approach shows a great suitability for WDM networks based on RoF signal transport and also represents a cost-effective solution for passive optical networks.

Broadband Convergence of 40 GHz-ROF and 10-Gb/s WDM-PON Systems in the Duplex Access Network

A broadly converged 40G-ROF and 10-Gb/s WDM-PON multi-service access system is proposed and experimentally demonstrated. This scheme consists of an integrated system of 40G-ROF and 10-Gb/s WDM-PON simultaneously transmitting independent 2.5-Gb/s wireless and 10-Gb/s wire signal. At the base station, it employs a remodulation scheme, which is achieved by remodulating the upstream OOK signal on the DPSK downstream signal, to reduce the cost of the base station. The transmission experiment is carried out over a 25-km-long single mode fiber (SMF-28). The results show that the sensitivities of downstream PON and ROF signal are −14.5 dBm and −21.5 dBm, respectively, and the sensitivity of upstream signal is −25.3 dBm.