Jair A. L. Silva

A PAPR reduction technique based on a constant envelope OFDM approach for fiber nonlinearity mitigation in optical direct-detection systems

In this paper, we propose a new peak-to-average power ratio reduction technique based on a constant envelope orthogonal frequency division multiplexing (CE-OFDM) approach to mitigate fiber induced nonlinearities in direct-detection optical OFDM (DDO-OFDM) systems. Simulation results show that the proposed 10 Gbps DDO-CE-OFDM system using 16-quadrature amplitude modulation (16-QAM), 2.66 GHz signal bandwidth, and different values of electrical phase modulation index outperforms DDO-OFDM systems as it increases the fiber nonlinearity tolerance in fiber links without optical dispersion compensation. The bit error rate of the proposed transmission scheme is decreased by a factor of 1000 if compared to conventional DDO-OFDM systems, for 10 dBm of optical input power and considering a span of 960 km of standard single-mode fiber.

Transmission of CE-OFDM Signals Over MMF Links Using Directly Modulated 850-nm VCSELs

We report the experimental transmission of constant-envelope orthogonal frequency division multiplexing (CE-OFDM) signals over short-reach multimode fiber links. Error-free transmission of 2.2 Gb/s over a 300-m OM-3 fiber link, using a directly modulated 850-nm vertical-cavity surface emitting laser and direct detection, is achieved. The results confirm the CE-OFDM modulation format as a low peak-to-average power ratio alternative for low-cost data-center interconnects.

Impact of Optical Power in the Guard-Band Reduction of an Optimized DDO-OFDM System

A multiobjective optimization on the parameters of direct-detection optical orthogonal frequency division multiplexing (DDO-OFDM) systems in short-range links is proposed. Based on genetic algorithms, the optimization process takes into account the influence of optical power in the guard-band reduction of such multicarrier systems with 4and 16-quadratic-amplitude modulation (QAM) subcarrier mapping and for propagation in 40 km of standard single-mode fiber (SSMF). Simulation results show that the parameters optimization is responsible for a gain of approximately 2.5 dB [≈ 1.8 dB] in the required optical power for bit-errorrate ≤10-3, for DDO-OFDM system transmission over 40 km of uncompensated SSMF, with a guard band BG equals to 50% of the signal bandwidth Bw and 16-QAM [4-QAM] subcarrier mapping. For an extremely reduced guard band of only 1% of Bw, the gain reduced to ≈ 0.5 dB and ≈ 1.5 dB for 16and 4-QAM mapping, respectively. The optimization process is experimentally validated under the transmission of the optimized DDO-OFDM systems in optical back-to-back (B2B) configuration and 40 km of uncompensated SSMF. A fair performance comparison is discussed in the experimental results considering BG/Bw = 0.5 and BG/Bw = 0.01 in the range of the optimized optical powers. It is shown that a maximum optical power penalty of approximately 2 dBm is registered according to a guard-band reduction from 50% to 1% of the useful bandwidth, for transmission over the 40 km of SSMF, considering 16-QAM subcarrier mapping.

Experimental Demonstration of a 33.5-Gb/s OFDM-Based PON With Subcarrier Pre-Emphasis

Spectral efficiency is one of the critical issues in passive optical networks (PONs). Thus, next generation PON systems must employ advanced modulation techniques and channel compensation to improve the network performance and provide more bandwidth for end users. In this letter, we have experimentally demonstrated a spectral efficiency improvement in PONs based on the bandwidth scalable orthogonal frequency division multiplexing (BSOFDM-PON), considerably reducing the recommended optical guard band of such direct detection systems. The experimental results show that this efficiency can be achieved in a 33.5-Gb/s BSOFDM-PON on one wavelength channel when subcarrier pre-emphasis is used.

Experimental investigation of broadband power line communication modems for onshore oil & gas industry: A preliminary analysis

A field trial of power line communication (PLC) with 200 Mpbs modems in a low voltage test grid is presented in this paper. Throughput and adaptivity to physical channel characteristics are some of the investigated functionalities in order to evaluate their appliance in medium voltage (MV) levels for onshore oil & gas industries. Experimental results obtained from a 180 m low voltage (LV) test network reveal the modems ability to achieve the measured high bit rates.

Electrical constant envelope signals for nonlinearity mitigation in coherent-detection orthogonal frequency-division multiplexing systems

Abstract. A theoretical analysis and a numerical investigation of 3-dB peak-to-average power ratio electrical constant envelope over orthogonal frequency-division multiplexing (OFDM) signals in coherent-detection optical (CO) systems are proposed. A 100-Gb/s optical system is studied to increase the nonlinear tolerance (NLT) to both Mach–Zehnder modulation and optical propagation impairments. Simulation results show that, with 16- and 64-QAM subcarrier modulations, the proposed system outperforms a conventional CO-OFDM system, if an optical modulation index OMI=2.5 and an electrical phase modulation index 2πh=3 are simultaneously adopted. The achieved NLT denoted by a performance gain of 24 dB is attractive after propagation through 1200 km of dispersion-uncompensated standard single-mode fiber, especially for 10-dBm fiber input power and despite the intrinsic bandwidth enlargement of PMs.

Fast optimization of multipump Raman amplifiers based on a simplified wavelength and power budget heuristic

Abstract. We report a simple budget heuristic for a fast optimization of multipump Raman amplifiers based on the reallocation of the pump wavelengths and the optical powers. A set of different optical fibers are analyzed as the Raman gain medium, and a four-pump amplifier setup is optimized for each of them in order to achieve ripples close to 1 dB and gains up to 20 dB in the C band. Later, a comparison between our proposed heuristic and a multiobjective optimization based on a nondominated sorting genetic algorithm is made, highlighting the fact that our new approach can give similar solutions after at least an order of magnitude fewer iterations. The results shown in this paper can potentially pave the way for real-time optimization of multipump Raman amplifier systems.

A passive optical network based on centralized wavelength and bandwidth scalable OFDM signals

In this paper, we propose a simple and cost-effective bandwidth scalable passive optical network (PON) based on orthogonal frequency division multiplexing (BSOFDM-PON). We report performance analysis in terms of the signal-to-noise ratio (SNR), bit-error-rate (BER) and error vector magnitude (EVM) of a PON system accommodating 32 optical network units (ONUs). Our simulations have successfully demonstrated that throughput of 35.5 and 53.2 Gbps can be achieved using 16 and 64 QAM, respectively, within a total distance ranging from 20 to 30 km. It gives throughputs of 1.10 and 1.66 Gbps per ONU.

Telecommunication Technologies for Smart Grids: Total Cost Optimization

Abstract What makes a smart grid really smart is its ability to exchange information among thousands of devices spread over a vast geographic area. However, it is important to build reliable and secure communication networks with a different data capacity and different transmission technologies. In this chapter, we will introduce the basic concepts, requirements, and challenges of such a heterogeneous network. The design of cost-effective smart grid communication networks based on the total cost optimization problem is presented considering optical fiber communications, power line communication, and wireless systems.

Evaluation of selective control information detection scheme in orthogonal frequency division multiplexing-based radio-over-fiber and visible light communication links

Abstract. Block-level detection is required to decode what may be classified as selective control information (SCI) such as control format indicator in 4G-long-term evolution systems. Using optical orthogonal frequency division multiplexing over radio-over-fiber (RoF) links, we report the experimental evaluation of an SCI detection scheme based on a time-domain correlation (TDC) technique in comparison with the conventional maximum likelihood (ML) approach. When compared with the ML method, it is shown that the TDC method improves detection performance over both 20 and 40 km of standard single mode fiber (SSMF) links. We also report a performance analysis of the TDC scheme in noisy visible light communication channel models after propagation through 40 km of SSMF. Experimental and simulation results confirm that the TDC method is attractive for practical orthogonal frequency division multiplexing-based RoF and fiber-wireless systems. Unlike the ML method, another key benefit of the TDC is that it requires no channel estimation.